Title of Invention

"AN OPTICAL DISC HAVING A REWRITABLE FIRST RECORDING AREA AND READ ONLY SECOND RECORDING AREA"

Abstract

The first recoding area includes first tracks composed of groove tracks and land tracks, the groove tracks and the land tracks being formed on an optical disk substrate alternately in a spiral or concentric shape, each of the first tracks bring divided into a plurality of first sectors, and each of the first sectors including a first header region having identification data for identifying the first sector and a first data region for recording user data by forming recording marks by changing optical characteristic of a recording layer. The second recording area includes second tracks formed with physical bit rows arranged on the optical disk substrate in a spiral or concentric shape, each of the second tracks being divided into a plurality of second sectors, each of the second sectors including a second region having identification data for identifying the second sector and a second data region having read-only data recorded as the bit rows. The first header region includes the physical first pit row, each pit of the first pit row having a width in a radial direction of the optical disk substantially equal to a width of the groove track and being wobbled outward or inward from a center line of the groove track by about a quarter of a pitch of the groove track, and the second header region includes a physical second pit row, each pit of the second pit row having a width radial direction of the optical disk smaller than the width of the groove track and being formed substantially along the center line of the second track.

Full Text

The invention relates in the invention relates to an optical disk. invention relates to a data format Oh an opt±cft disk having a rewritsble area and a read-only area. 2. DESCRIPTION OF THE RELATED ART: Optical disks are classified into a read-only type which only allows for re~roduotion of recorded data and ~ rewritable type whioh allows the user to record data thereon. A read-only optical disk has tracks formed a sp±r~l or shape on a disk substrate. An array o~ pita are pt~ysioally formed along the tracks in a0~ordan~* i4ith i c~rm~t4.oz~ ~o be recozded. A rewritabl. ord data on the disk, the disk i. irradisted with a laser b!~rn along the tracks, and the intensity of the laser beam is modulated in accordance with the data to be reQorded so a~ to form regions with different optical properties (recording marks) on the recordIng layer. In an optical disk, generally, one treck corresponding to one rotation of the optical disk 4 divided irLtQ a pli~ra1ity of sectors as units for recording and ~~p~o4uc±ng d~ts (data units) so as to manage the posit~r~p oi necessary data on the cpticsl disk end realize high-ppeed data retrieval. A read-only optical disk and a rewr±table optical d±s~c hays dift~rsnt d*ta formats and modulation codes from each other. In order to allow the user to record data every vector, the data format of th~ rewritable optical disk is required to have, for example, a region for the laser power at the head of a recording rsg~.o~ of each sector and a region for absorbing a var±at±0~i of th~ rotation of a spindle motor at the end of th~ r~oor4±ng ±egion. In the ease of the read-only 0~tic~l d±~ where no 4ata 4.s rewritten by the user, ±nforniat±on has been rsc~rded on th. optical disk at the pro~oticn of the opticel disk with high precision, and no by Mv$n~ a ~-~~ritable ar~ and a read-only area. The ~tc~ d4g1~ 301 has a r*oord±ng ~.ayer formed on a disk aubstrate so that the uwer can record and reproduce data on ~~id from the optic4 disk. Referring to Figure 21, the.ca± 4isk 301.u4.s read-only areas 302 and 303 The oviter en4 inner portions thereof, respectiv4y, mr4 a area 305 located between the areas 3Q2 and 303. Xra the read-only areas 302 and 303, information and ~ata heve b~en previously recorded by forming physi-. cal pit arrays 304. In the rewritable area 305, grooveshaped guide tracks 30P have been praviously formed so that ~he user cap record and reproduce information and data by tracking the grooves of the tracks (groove adjacent grooves (land tracks). diagram Showing a conventional opt4.oal d~.sk r~ording/repro4ucirig apparatus 300 for recording/reproducing data on/from the optical disk 301 shown in Figure 21 Referring to Figure 22, the optical disk recording/reproducing apparatus 300 includes an optical head 307 for recording/reproducing data, a first signal processing seceion 320 for processing a reproduction signal supplied from the jrewritable area 305 of the optical disk 301, a second signal processing sct±ion 330 for processing a reproduction signal supplied from the read-only ~raas 302 and 303 of the optical 4isj~ 3Q2., s4~d a switch ~08 for connecting the reproduc~ pigr~al from ~ c~tical head 307 to either the first .~n4 ~oc~trg ~0ttQrl 32Q oz~ the mecond signal p~0O.t~g ~BO't&Ofl. 33~. The ii~st signal processing •b*14.or~ 3*0 inclu4~s a first digitiz4.ng circuit 309, a first P~L (phase-locked loop) 310, a first timing generato~ 32.1, and ~ firu~ demodulaior 312. Likewise, the •~cond signal prooess~.ng section 330 includes a second digi~iz±ng circuit 313, a second PLL ~14, a second timing g~nerator 31.5, and a second demodulator 316. When data recorded on the rswritable area 305 is to be ra~roduced, the switch 308 is switched to a terminal ~ 'to b* conr~eotsd with the ~±ret signal processing s~ot~on 32~, Th~ repr~duotion signal supplied to the *L%~st s4.gr~si procesaing section ~2O is first converted 4ritO a 4~q4.~a4. ~igna1 by the first digitizing air~i4.t 3~9, aM clocked by th~ f4r~t PLL 32.0. The first 't±ming~ gen~.rato~ ~1l generates a gate signal for reading u~sr dat~, ar~d the user data is demodulated into binary 0#~p by t~ first d~mod~4lator 32.2. The den~odulated data In a conve.-itional optical disk 301, different data formats and modulation code. are used in the rewritable area 305 and the read-only areas 302 and 303 as described above. Accordingly, the second signal processing s~tion 33Q for the read-only areas is separ~it~y re~u4r~d. When data recorded on the read-only areas 302 arid 3Q3 is to be reproduced, therefore, the switch 308 is switched tQ a terminal B to be connected w±t~ the second signal pzocess±ng section 330. As in the *ir~t s4.gnal processing ~ct±on ~20 described above, the Ze~,rQduction signal supplied to the second signal proopasirig seot4.on 330 is I i~st converted into a digital s~nai ~y th~ SGQQn4 g~.'t±~dng circuit 313, and clocked by the s*con4 P~L 3*.4 The second timing generator 315 ~ener~tes a gate s±gnal for reading user data, and the user data i~ demodu2.ate4 into binary data by the second d~.rnodtA1ato~ 310. The dstnodulatad data is output from a 300CM output ter~ninal 318. $ri~4-e ~3 schematically illustrates a data format o~ a sector 400 on the conventional rewritsble optical disk 3O~.. ~eferring to Figure 23, the sector 400 inoludes a sector identification data region 401 at the head thereof, followed by a gap region 402, a VFO region 403, an information data region 450, and a buffer region 409 in this order. The sector identification data region 401 stores address information and the like for management of the sector. ~'he gap region 402 absorbs signal disturbetr?ce pt th~ start of data recording end sets a laser pc$~~ ~ ?ecozd$~g. Tt~p V~'O re~ion 403 Stores a ropetil~cn pu'tt.~p o~ cc~da~ with ~ ~ng~.e period to stabilize the clocking at the r~p~od~ction. Data stored in the iiiforn~ation data region 450 i~ divided intoa plurality of data blocks 405k, 405fr ... with data synchronous series 404a, 404b, .. prefixed to the respective data blocks. ~aoh of the data synchronous series 404 (404*, 404b, ..) stores a specific code pattern which does not appear in data in the other regions obtained by modulating with a recording code. The buffer regIon 409 absorbs a variation of the rotation at the end of recording. Using the data for~nat with the above configure~ 'th* od~ctio~ 4.s ooridu~tgd in the following ~d~nner. F4~r~t, t~ olopkirLg at the PtjL circuit is stabiXi~~ by th~ r~'t±tipn pat't*~n stored in the V?O relion 403 After. th~ .ol0ck has been sufficiently etabilimed, th~ ~ata synoh~onous series 404* is detected and re~ogni~ed to be the ~iead of the information data region 450. Upon recognition, the first data block 405a is reproduced. Subsequently, the next data synchronous serica 404b ie detected' to reproduce the next data block 405b. By repeating this operation, the data on the information data region 450 can be stably reproduced. With the data synchronous series 404 prefixed to thp reap~ctive data ~Xooks 405. even if the data reprodupt4.o~ at one data block becoming out of synchronization due to an error euch as dropout, the synchronization can b~ ~um~d from th~ nest data block, allowing the data ripro~uction to be contiriUsd. In the conv*ntior~l cpt±c~1 disk, however, the ~1s~a ~orsnats anc~ n~o4ti1~ticn ood~s uped in the rewritable •zga end t~e read-or4y axe. are 4ifi~rent from each other as described above. The conventional recording/reproducing apparatus for such an optical disk needs to have two separate signal processing circuits for the rewritable area and the read-only areas, which complicates and enlarges the circuit size of the apparatus. The present invention there is discloses an optical disk having a rewritable first recording area and a read-only second recording area, wherein the first recording area comprises first tracks composed of groove tracks consisting of grooves and land tracks consisting of spaces between adjacent grooves, the groove tracks and the land tracks being formed on an optical disk substrate alternately in a spiral or concentric shape, each of the first tracks being divided into a plurality of first sectors, each of the first sectors comprises a first header region having identification data for identifying the first sector and a first data region for recording user data by forming recording marks by changing optical characteristics of a recording layer, the second recording area comprises second tracks formed with physical bit rows arranged on the optical disk substrate in a spiral or concentric shape, each of the second tracks being divided into a plurality of second sectors, each of the second sectors comprises a second header region having identification data for identifying the second sector and a second data region having read-only data recorded as the bit rows, characterized in that the first header region comprises a physical first pit row, each pit of the first pit row having a width in a radial direction of the optical disk substantially equal to a width of the groove track and being wobbled outward or inward from a center line of the groove track by about a quarter of a pitch of the groove track, and thc second header region comprises a physical second pit row, each pit of the second pit row having a width in the radial direction of the optical disk smaller than the width of the groove track and being formed substantially along the center line of the second track. SUMMARY OF THE INVENTION 1'he optical disk of this invention has a rewritable first recording area and a read-only sceond recording area, wherein the first recording area includes first tracks composed of groove tracks consisting of grooves and land tracks consisting of spaces between adjacent grooves, the groove tracks and the land tracks being formed on an optical disk substrate alternately in a spiral or concentric shape, each of the first tracks being divided into a piTarality of first sectors, each of the first sectors including a first header region having identification data for identif~y'ing the first sector and a first data region for recording user data by forming recording marks by changing optical characteristics of a recording layer. The second recording area includes second tracks formed with physical bit rows arranged on the optical disk substrate in a spiral or concentric shape, each of the second tracks being divided into a plurality of second sectors, each of the second sectors including a second header region having identification data for identifying the second sector and a second data region having read-only data recorded rows. The first header region includes a physical first pit row, each pit of the first pit row having a width in a radial direction of the optical disk substantially equal to a width of the groove track and being wobbled outwards or inward from a center line of the groove track by about a quarter of a pitch of the groove traek, and the esoond header region includes a physical second pit row, each pit of th~ second pit row having a width in the radial direction of the optical disk smaller than the width of the groove track and being Lormed substantially along the ci~n1er line of the second track. of th~ invention, a data of 'the ~rst ~adex region end a data sequence of th~ ~eco~d h*ader z~~±on are utiodulated with a same iii~dulMion co4~. and a date •eq~~o.f the first data region arid & data sequenc~ of the second data region are modulated with a same modulation code. In another embodiment of the .tnvention, the identification data of the first header region and the ±dentif±cat±~n data of the second header region have data formats with a same data sequence and a same data capacity~nd the first data reg±on and the second data region have data formats with a same data sequence and a same data ~,acity. In still anotM~' embodiment of the invention, a data bi~ interval betweSri the first headAr region and the first data region in th~ ~4.rst recording area is substanii.~lly equal tQ a data bit interval between the second header re~io~i and 'the second data region in the second r4~cording area. In still anotheV embodiment 0± the invention, in t~e rewritabie first re~,or4in~ area, each of the first seoto~s incJ.udes & mirror mark region, a gap region, and a fir8t ~uinxny data region which are formed between the first header region and the first data region and a guard d~e xegi~ri and a buffer region which are formed between the firint data region and a first header region of a next first ~ector, and in the seCond recording area, each of the peoor~rj sectors ±raol4d±ng S seCond dummy data region ftr~iied b~tw~~n t~e second header region and the second 4aj~ ~egi~r~ end a thir4 dum~ny data region formed between th~ ~ecoM 4~ta region ~d a eCcoM header region of a k~0)~t s~coT1d !#ctOr. In still another embodiment of the invention, •ao~ of the first dummy data region, the second dummy d~a region. ~nd the third dwnn~y data region have a~ pcif4.c ee~ence pattern of a modulation code used for mod4at±on of datato be recorded. A1ternativ~ly, the optical disk of this invention h~s a rewritable first recording area and a read-only second recording area, wherein the first recording area ±r~cludes first track~ composed of groove tracks consisting of grooves and land tracks consisting of spaces between adjacent grooves, the groove tracks and the land tracks being formed on an optical disk substrate alternately in a spiral or concentric shape. Each of the first tracks is divided into ~ plurality of first sectors. Each o~ the first Sectore including a first header region havIr~g i~~~tif±cat$ori data for identifying the first •eotot ~nd a first data region for recording user data as x~aozjing n~0rks by chang4.ng optical characteristics of a recording lay.~r. The ~eei~d recording area includes apoond tracks formed with physical bit rows arranged on ~he optical disk substrate in a spiral or concentric shape, Each of the second tracks being divided into a pLuralAty of second sectors, each of the second sectors includ$ng a second header region having identification d~t~ for identifying the second sector and a second data re~on h~ving read-only 4ata recorded as the bit rows. Data series of the first and seQond recording areas are ~iiodU1.~ed w14h a eeni~ ~odulati~ri code, the first and ~ec0r1d seoto~ have a same data capacity, the first and 0sco~1d heac~er regions he~e ~ same date sequence, and the first and s~cond data regions have a same data sequence and a same date ce~city. In one e~nbodinient of the invention, each of the f.r~t sectors ±nc~2.udes a first dummy data region formed ~etwesn the first header region and the first data region. Each of the second sectors includes a second dummy data region formed between the second header region and 'the second ~ta region and a third dummy data region 4~med between the second data region and a second header o~ a ne~ct second sector. Sach of the second and t~i;d 4umrtiy data regions includes, in at least a portion 1~iezecf, data of a data series different from a data aeries of a corresponding dummy data region on an inward or outward pdjacant track on the optical disk substrate. In anothez ~mbo4iment of the invention, each of thB secoh4 ~M th±r4 dA~tM1y data re~icne includes, in at ~.p.st a pordon theXeof, ~ random data series with subAtAr~tially no correlation with a data series provided on a oo~ ponci4ng dumuw d*ta region on an adjacent track. in ~till another embodiment of the invention, the ~ndort~ ~ata seri~~s is a data series generated by an M Xn sjill ariotMr *mbodiment of the invention, e.~oh of the A~oond and thiZ'd d~~mmy data regions includes, in at 1e~*~ ~ portion th~*o~, a rando~n data series with s~bpt*!vt±~lXy no oorxalat40h with a data series formed on * Qor±~p~$in~ du~timy dots rqgi~n an an adjacent track ~ speo~44~ me t~et1os ~tt8rn included in a modulation oo~e ov4.cI~d tol~.ow4.ng th* xandom data series. Zn, still anol:her mm~od±ment of the invention, ~a~h o~ th~ *.oond *n~ *hi~'d dummy 4ata regions includes, ~ l@~at a pp~t±ori ths~of, a data synchronous series foz~ ~p~ci~'±rig a start timing position ~f the second data r~ion. In still another embodiment of the lnv.ntion, 'the data synchronous series included in the second and third dummy data regions are provided so that a pattern of the data synchronous series is switched every track among a plurality of different data synchronous patterns. In still another embodiment of the invention, each of the second and third dummy data region. has, in at X*a.t * por~iQn thexeof~ a pptt*rn gen*rated by scrama p~e~p~#rrhinSd 4~t~ based on sddr.ms information in the W~OtO~ ~ariti~icftt4.on 4a~a aM bY modulating the sani~4ed d#t~ with the modulatior~ code. In ~ti1.l aflQth~x embodtment of the invention, one error eorrection block includ*s a predetermined number k (k is ~n integer) of the firSt or second sectors, and data is recorded on the number of sectors equal to a multiple of k, dwi~my data being recorded on remaining sectoxe of less than k. )dte~ivg~.y, t~* op'~ioal ~±sk ~4 this invention ~ ~*writ~b~., first t ord~.ng areR And a read-only sum~ond re~c~rd4.pg ~ whexe~~ the fixat recording area i~c1udA~ first trac~ composed of groove trwks consistirig of gxoove~ and lend tracks consisting of spaces betw~e~i adjacent grooves, the groove tracks and the land t~acka being formed on am optical disk substrate alternst~ly in a spiral or concentric shap•. Each of the first tracks is divided into a plurality of first sectors. Each of the first sectors including a first header region having identification data for identifying the first u~ctor and a first. data region for recording user data by forming recording marks obtained by changing optical c~acter±st~cs of a recording layer. The second reoording aria iricludes mecorid tracks formed With physical bit rowp ax~rige4 on the opt4.oaX disk substrate in a spiral Ox' o~noenttic bhape. kach of the second tracks is divided into a plUx~lity of scoorid sectors, each of the second •~~tor~ including a p.oond header tegion having identifi~atior~ dat4 for i ntifying the second sector and a ~o~4 4at# rpg~on havit~g r~ad-on1y data recorded as the b~'t rows. At least ona of ~he ~±rst and second data r~gi~ps inc2.tmdpn: a f4.rat data synchronous manes provided ~'t ~ head ~f the ~ata reg~on for specifying a start t4.mtnp poSitich of the d*t~ regioni a second data mynobrc~jou~ seriee preceding the first data synchronous ~ specifying a st*rt timing position of the data tegio4~ aM ~ thi~i dAte synchronous s~rie8 preceding the s,corid data synchronous s~r±es and having a specific r~pet4.tion sequence pattern of a modulation code in the dBte region. Zn one emkod4.msnt ~f the £nVenti~n, the data is div4.ded ihto • plurality of data blocks, the ~i.x*'t 4ata synchronous s,x'4.e5 is provided at a head o~ e~cki o~ the data b1o~ks, and ~he secoM data synchronous sq~±~S po~de~ th~ first data synchronous series providod at a head of a first one of the plurality of data bloo~s. In another prnbodir~ent of the inv5ntion, a digital sUm value w1~ich is obtained by cdnverting "1" end "0" in the second data synchronous series into h3)T and "—1', r~ispectively, and by summing all value. ~s substantially zero. In still another e~bodinient of the invention, the second data synchronous 'aeries satisfies a maximum length and a minimum length as limit values under a modulation co4e rule of a mar1~ length ("I" or "0" level) and a space 1~ngth ("0" ox "1" level) of the data region. ~n still ~oth;r e~~pdiment of the invention, an pv~s,o o~ tM mark lsnqt~ arid the space length of the se~nd data synchronous Esriem is larger than the mark length and the space length of th~ third data synchronous series. In still another embodiment of the invention, the second ~ata eynchronous spriss is a date s*ries composed of ~ combination of a pluxality of any of 4-bit code syn~boIs, "0100", "0010", "1000", "0000". " Thus, the ±nvg~t±on descr~.bed herein makes possible the advantage of providing an optical disk having a rswritable area ~nd a rpad-only area which can reduce the circuit size of a recording/reproducing apparat~.is using the optical disk and provide stable reproducti. on. These and other advantages of the present invent4on will become apparent to those skilled in the art upon rsad4.ng arid underst~riding the following detailed depcri~tion with ~erencC to the accompanying figures. 8~IE7 DESCRIPTION OF T?{E DRAWINGS F~.p~1re 1 ±l~stxets~ an optical disk having a r,w.t~ble area arid ree4-or~1y areas according to the pre~ent ir~vsnt4on. Figures 2A to ~ il1~zstrate data formats and reproduction signa2.~ used In the optical disk according tu the present invention. Figure ~ i~ a bioo}c d4,agram illustrating a re~ro4uotion signel proc~paIn~ section for reproducing du~ta ~om Fhe opti.ca~. disk according to the present invention. to 4~I illustrate data formats and riipro4uotion signals u39d in another optical disk accord$ng to the present invention. F44~ute S is a block diagram illustrating the pr$~c$ple of tracHing conjcol by a phase error detection Fijjure 6 ±X4.ustrates waveforms of tracking error sLgnals obtatne4 wh*n same data series are recorded on a4jpcent tracks. Figure 7 illustrates waveforms of tracking error signals obtained when different data series are recorded op pdj scent tracks. Figures BA to SD illustrate data formats of dummy data regions according to the present invention. Figure 9 illunretqs an optical disk where dummy dna tor S*ctot epritrol tin Lecorded according to the pte$.nt iflventiQfl. Fig4r*S zpa and ~.0D i2,lustrate a data format in the rewritable aret accotd±ng to the present invention. Figures hA and 119 illustrate a data format in the repd-only areas accor4ing to thp present invention. Figure 12 Illustrates a configuration of a circuit for generating scrambled data according to the prqs*nt invention. Figure 13 is Sn ~xampie of a conversion table of m~du1~tion cods~. Figursi 141 end 10 ~.I1vutrate date formats in the t-awrttpbl. area And the readeonly areas c~ an optical disk according to the present invention. Figure 15 is a table illustrating the comparison of the properties of pattern. of a second date uynohroflO4B series according to the pressnt invention. FiQurs 1.6 *lluwttstes a configuration of a deteo*±on Qiroult for the Second data synchronous series. Figure 37 ±11u~trates a detection method and a dgts;t4.on flrige EQZ- the se~on4 date syrtchronouu series. Piggtwg 1~A to 1*0 tZXustrate ah±tt~ in a sues levpl S Qr Qpnvmr4on to b$nary oo4ea, $igurss ~fl nnd *08 erg graphs tlluctrating AutocQtr*~t4.on furQt±ons Qf patterrip I and 4 obta±ried 4 reproduction signal $ncludsu no error. fl.gureu ~OA ~d oi are graphs illustrating AutQ0orr~1~tion functions of pRtterns 1 and 4 obtained when s4~p S~4tt occurs at one to three position(s) within a synchronovs pattern detection window. F±gttres 20C and ZOD are graph. illustrating autocorrolation funct±ons of pattsrns 1 and 4 obtained when the slice level is shifted. F±gure 21 illustrites a convantional opticsel dj.s~. Figure U ta a block diagram illustrating a repro414ot±~n ptgnal processing circuit for reproducing data f;ofli th~ conveption&l- optical disk. Fig~are 33 illustrates a data format of the conventional optical disk. DESCRIPTION OF THE PJtEFERRED EMBODIMENTS The present invention will be described by way of exaspisa with referenc, to the accompanying drawings. (Eternple 1) An d~tioal disk of Example 1 according to the vr~s*t~t tnvAntibn has a ~'*.or4tnq ~.tyar formed on S disk sul~$trete sq a* to al4ow the u;er to record and reproduce data o~i and from the optical 4$*k. Referring tQ Figure Z, an optical disk 1. of Example 1 ±rieluds4 repd-only areas 2 and S located on the outer and inner portions thereof, respectively, end a rewritable area 5 located between the read-only areas 2 and 3. In the reed-only areas 2 and 3, pit rows are physically formed ~s tracks. The length and position of each pit in thR pit robes have been determined in actordeno0 with reed-only data rpcordAd on the reed-only 2 end 3. In the rewritabla area B, guide grooves (gui4~ trac$~s) 6 are formed in a spiral or concentric shape on the disk substrate. Information and data are ecorded along the grooves (groove tracks) or lends between adjacent grooves (lend tracks). Hereinbelow, the groove tracks and th* ~.and tracks are collectively ref erred to ~ information tracku. In Figure 1, the optics], disk 2. is shown to have spiral tracks on either area. Each Qt the information tracks in the rswr±tabls 6154 5 is div±4ed into a ~lutaJ4ty of sectors. Each seo~o$~ ti~o~r4es a ttret he;d.r region having identificati~ri data Lot id*nt±tying the sector and a first data rep$on for •tot4.ng ta.er d4ta b~ tcr~itng reoor~ing marks fri ~hazginq tht optical propsrtteb o~ the recording lay0t. L4.4srX*p, seob treok in thq read-only areas 2 and S ±~ d4~kt4e4 tn~o a p34zrality at sect0rs. Each sector of the r0.A"p4y #t~&. ~ aN ~ inoZudep a second header t00i~r~ Mv±rL0 44*nttticstion data f0r identifying the #*otor •nd it asoan4 ~sts tsg$on hftving read-only date r0por4~4 th*t~on in the tar:n of the pit rows. In this we~y, t~y 4±viding cRab track correspon4$ng to one rotation o42 the optiopi disk into a plurality of sectors C date uriit~), 41aha~eIn0nt ot th; positions at necessary date on th'~ 0pt*0&.L 4i@~t and hi~h-#peed data retrieval can be realised. Figures 2k to 211 shows data formats of the op*±opl disk 2. of this example. A data format in the reVritable area 5 will be first described. Figure 2A shows an exemplified data format of each sector 10 in the rewtitable area 5, and Figure ZC shows a ~hysica1 configuration of the information track corresponding to the sector 10 of Figure 2k. Figure 2k shows data formats of two ad3apent intormation trsckp, i.e., a groove track 7 od~rpond~n~ to th, gu4.de track 6 and a lend track S adjacent to the groov* track 7, for comparison' with the phy~cal corifig~.zrat±ons thereof shown in Figure 2C. Such 4 groove track 7 and ],and track B alternately appear in th~ rew~itable area S of the optical disk 1. The user can record desired information (user data) on both the groove tr4ck 7 end the land track 8 by tracking the groove track 7 and the land track 8 separately. ~efe~ring to Figure 2A, the sector 10 includes a first head•~ region 12. (sector identification data PIDi ~n4 PZt~~) er~4 ~ infor~nat4.on region ~0 A mirror mark ~ (P.1) 4r$4 a g~p reg±ot~ 13 (GAPe and cAPb) are foriitad ~t~eri lhe first h~e4er region 11 and the inforniat*cr~ ±*~ion ~Q. The 4.~fortnat±on region 20 includes a first durtuny 4sta region 15 (VPO region (VPOa and VFOb)), a first data region 17 (DATAa and DATAb), and a guard de~a region ±5 (ODe and Gob) e~ will be described later in detail. A b4ffer region ~ (BUFa and BU?b) is formed between the information region 20 and a first header region 12.' of a next ueot~r 10'. The affix a of the above abbreviated codes (e.g., VFOa and DATAa) indicates that the regions are formed on the groove track 7, while the affix b (e.g., VFOb and DATAb) indicates that the r•g~o~s are formed on the lpnd tzaok B. This i~ also app iC4~.. in t~0 *ollowirig description un~ems otherwise ~eferring to Figure 2C, the first header regio~ 1 ir~olude* a phy~±oa],].y formed pit row 21. (21a and Zib). The wi4~b of each pit of the pit row 21 in the radi4,di~rsction of thC optioaZ disk ~. is substantially equal to the width of t:h~ guide groove 6 (groove track 7). The pit rows 21a and 22.b are displaoed outward end inward from the Center line of the guide groove 6 (i.e~., wobbled) by abo4t a qu~rter of the pitch of the g'44e groove 6 (i.e., groove pitch Tp). In this example, ~ 4rst hea4~r region 4 is divided, into a former half ~.2.e and ~ latter half lib. The pit row 21a correspond±~ t~ ~e fox'me~ half 24.. i* displaced outward to th~ p~r*phe~y of the opt4.oal disk 1, while the pit rc$~ 214, o respr~n4inp to the latter half lib in displaced i~wax'd. With this displaa~~r~t of the pit rows 21. and ~ ~x'om t~ oenter line of the guide groove 6 (groove track 7), tho first beader regIon 12. can be commonly used ~pv *ex'vp tr~ck~.ng of both the groove track 7 and the 1,eri~ track 8. Th~is, ~~arat• exclu~±ve header regionu t~a groove traQk 7 arid the land track 8 are not r~iq4rs~~. Zf esolusive header regions ~re requ±red for the gx'oove track 7 and the lend track 8, a width of the pit rows eh~uld be smaller than the width of the guide groove 6 so that the respective pit rows on the groove track 7 and the lend track 8 do not overlap each other. Suoh ~ narrow pit may be formed by using a light beam different from a light beam for cutting the guide groove 6. It is difficult, however, to keep stable the positional precision between the two beams. In th±~ ~xan~ple, a l.{g~t beam for cutting the gui4p groove ~ is ~o~bled 4~htwerd aM leftward from the ce~.in~ of the ;~4de groove ~ (gr~ove track 7) using an AO m~4ulato~ atid the ii~ to form the pit row 21 of ..the first header region 11. Thus, the pit row 21 can be farmed on the optical diSk 1 easily with high .precision withoUt using another b~am for cutting. The mirror mark region ~.2 following the header region 11 is used to determine whether the groove track 7 or the land track 8 is being tracked. The ~ap region 13 (~.3a and 13b) i. formed on the ~ 7 ~M the lan4 track S to avoid a head 14 of t~p i o~t.ic~ ~*g*.on 20 from overlapping the mirror m~ar~ ~gi~h ~ ot 'the ii~st header region 11 when a jL~er o~cure due to the rotation 0f the optl.oal disk 1. Veer da~a is reoo~ded on the information reg~on 20, which indludes t~ first dummy data region 15 (VPOa and VFQb), th~ first data region 17 (DATAa and DATAb), and the guard data region 18 (~Da and GDb) as deScribed above (see Figure ~). Information is recorded on the information region ~0 by irradiating the recording layer formed on the optical disk 2. with a laser beam to ohange the optical properties (reflectance) of the repordi~g la~'er. for exafl~ple, an irradiated portion of the r~Q~r4~.11g layer n~ay b~ changed from a cryutalline state to St~ Q~phOua state so as to form a recording mark with a reflectance different from the other per ~ As ~hown In ~ur~ 2C, a recording mark array 22. is ~ ofl th~ groo~~• treok 7. whilS a recording mark a~'r~t ~*b is ferm~d on the land track 8. Th~ iikst dummy data region IB is a VFO region a speoi~o pattern is recorded so as to promptly ~~biJ.ize clock the Pt4~ of the r~pro44ctiork signal pro- ceasing circuit. More specifically, a specific pattern (a qpecific bit length) of modulation codes used for data mod~4ation ip sequentially recorded on the dummy data region 15. Desired User data including an error correction code Is r~0ordsd on the tirat data region, 17. The gu4rd data rept0n 15 is formed at the end of the first 4iste rpgion 17 to ensure ths stability of the reproduction 5ignAl processing circuit, The )~uf*er rSg±on 19 ino~.u4es no data but is forTn~d to pvoi4 the end of the information region 20 from ovsrlepp*ng the hea4er region ii' of the next sector 10' When * jitter occurs due to the rotation of the optical disk 1. Thub, in the rewritable area B. data is recorded on the groove track 7 and the land track B in accordance with the c~ata formats described above. Then, a data format in the read-only areas 2 and 3 will be described with reference to FIgures 25 and 2D. Figure 28 shows Sn exemplified data .format of each ssoto~ 30 of th~ read-only areas 2 and 3, and Figure 3D schematically illustrates a physical configuration of the track corresponding to the sector 30 of Figure 23. Zn thp read-only arpas 3 and ~, a track 9 is ccIiflpQ0e4 0~ S $~t0-reoorqed pit row 29 (a pro-pit row). As shown 4.n Pigurt 2~, the pit rows are formed in accor4e.ncp w4.th thp tsarfle physicp.l format over the entire data rj~ion $fl thp rpfl4-only e;eas 2 and 3. More specifically, the width of the pit row 29 ,in the radial direction of th. optical disk 2. is smaller than the width (groove width) of the guide groQvs 6 (groove track 7) formed in the rewritable area 5, and all the pits are lined substant±41y along the center line o~ the track. 4ike th~ r~wr4.tabZ~ area 5, each track in the -~4y area~ 4iv~4ad into a plurality of !IR~tozS 30 fo~' 4R'te ~'0cozding ~ au to manage the posi~42 de~*szy inforn~4t4.on data on the optical disk aV~4 r~a14.se ~i.tg~-~p~a4 dRta ret~ieva].. It will be p~-ef~rable fat. pract4.cRl infor~nation recording/reproduction 4.* the septors in the read-only areas 2 and 3 and the rewritable area 5 can ~e mAnaged in a same manner and the processing such as sector retrieval are unified. To realize thi$ unified processing, in this exampi., the length of each sector and the lengths of the header ~gion and the data region of each sector in the read-only area 2 and 3 are made squal to those in the i~r$ta~e a:~a 5 to match the data form&t in the readonly ~ with that in th~ rswritabl~ area. A specific data ~orznat in the read-only areas 2 ar4 3 wi-lI. be described as an example. Referring to F~u~4 35, the Sector 30 inoludes a second header reg4on 31 (~eotor id.ntifica~±on data PI~l and P1D2) and a peoohd data region 37. A pRoond dummy data region 35 (VFOl) is fa~m~d between the ~~cond header region 31 and t~. ~eccr~ data rpgion 37. A third dummy data region 38 (VFO2) is Lormed between th9 sRccnd data region 37 and a s~cond header region i3' of a next sector 30'. Referrizig to 1~ig~re ZD, the pit row 29 of the eecon4.head~r reg~on ~2. t~ ~.ined eubstantially along the cent~ 1in~ o~ the track 9, not di-ipleced outward or ±nw~rd a~ in the first he~d~r region 11 in the rewritable ares. 5~ Th. width of ths pit row ~9 in the read-only a~*4~ 3 or 3 ~ the radial dirsotion of the optical di~k 1 is ~llsz then th~ groove width unlike the width ~t th* p4.t row 31 in t~ rewr4.table area 5 which is sub~r~t±al.ty ~q'4pl to th~ groove width. In t~e second data region 37, p1-so, the pit row Ms ~,en prsviously formed substantially along the center lir~ of the tr*ok 9 on th0 optical disk 2. in accordance wi-th the d~'ta tot recording. Ae is observed fron~ F±~ures 2k and 28, the first header ie~ion 11 in the rewritpble area 5 and the second header region 31 in the read-only areas 2 and 3 are the same in the data capacity, the data format (signal sequence), and the modulation codes. Also, the first data region 17 in the rewritsble area 5 and the second d4~ta region 37 in the read-only areas 2 and 3 are the same in the data capacity, the data format (signal ~o~uence), and the modulation codes. Further, as shown in Figures 2A and 21, a head (at*xt ~ing) 16 of the first data region 17 in the wr4.te$ie area ~ and a ~ad (wtart timing) 36 in the uecon4 4ata r~ion 37 ir~ the ;ead-on2.y areas 2 and 3 are matched with each other. Thug, by vising th~ same ~formpts (signal sequences) ~or the first and second header regions ii and 31 and for the first and second data regions 17 and 37 in the rewrj,tebls area S and th~ read-only areas 2 and 3, one reproduction signal processing circuit car. be shared by both the rewr4.tabl~ area S an4 the read-only areas 2 and 3, •nd thus th~ circuit size can be reduced. Tbe ~econ4 dumx~iy data r~gicn 35 ~s formed to prevent the eervo traok±n~ from becoming unstable due to d±soon~±nuat±on of trso~ng error signals which may occur if no pit row i~ formed bot~een the second header region 31 aM th~ seobnd data region 37. The second dummy data region 35 includes, for example, a specific data pattern of the same modulation code as that used for the f±rpt dummy data ~epion (VFO region) 15 ±n the rewritable area 5. With this arrangement, it is possible to promptly and stably clock the FLL of the reproduction signal processing circuit. Random data or any other data may also be us*d to stabilize the servo tracking. ~bm third d4m~ny date region 38 is formed to p~event th• servo track±r~ from becoming unstable due to discontinuation of tracking error signals, as in the sI3coM dummy data region 35. As above, in the r!ad-oril.y areas 2 and 3, t~ pit rows both in th* second hsader region 31 and ~ie sscon4 da~A region 37 a~o lined ~ubstantial1y along t~ip oent~r lt~s of the t~aok 9. Turther, the second and t~i~d d#~ reg~on~ ~ and 38 £411 the apace between the •econd header region 21 of tM sector 30 and the s*cc*$ detp ~ior~ 37 o~ the sector 30 and the space bet~~p th~ ~cor~4 data ~eg±on 37 ~f the meOtor 30 and t~hs p~oon~j t~a4#r r~gi.or~ 32.' of the next sector 30'. As a t~*u1t, the phy8ical arrangement of the pit row 29 is ur~iforrn alon~ the track 9 o~sr the entire read-only a~e~s 2 3r~d 3. Thus, according to the data format of the optical d4.*ft 1 o~ ~xe~t~p2.e 1, the first header region 11 is ai~p~n~n2.y ~.i*e4 ~ the treoking of both of the groove t~k 7 and the l*nd trao~ 8. Thus, separate exclusive h',o~~r ~ ~or the groove track 7 and the land trRo~( ~ ar~ ~ot required. ~hs ~ header region 12. can be easily aM pr~ci~~y fo~rfled oh the optical disk by wobbling a l.t~ht bea~n for o'.~tting the guide groove 6 (groove traC)c 7) v±ghtward and l~ftward from the track center, a s~,parate exclusive light source for forming 'the first header region is not required. Thus, the preformat in the rewritable area 5 of the optical disk 1 of this example can be easily formed by use of a single light source for c~.itting, reducing the circuit size of the recording/reproduoing apparatus for this optical disk. F±g~Vire 3 is a b~.ock diagram schematically showing ~ r~producti0n signal processing section of an optical di~1~ r*o0r~±rig/reprOducing apppjratus 2.00 for recordi~q/r.$~roduoing c~eta on/from the optical dlsk 1 of this e~~niplp. R~t~rriflg to Vigure ~, the reproduction signal p~oceesing s*ct4~n of the optical disk recordi~g/rspro4uOiflg •~paratu* 100 includes a 2-part optical deteotp~ 1~, a summing amplifier 12.1, a differential ampJ4fier 2.12, a switoh circuit 2.13, a digitizing circuit 114, & PLL (phase-locked loop) 2.15, a PID reproductIon circuit 116, a timing generator 117, a demodulator 118, and an envelope detector 120. The 2-part optical detector 2.10 (parts llOa and liob)' which is disposed in an optical head (not ehown) ri~cive~ ~eotwc~ light from the groove t.r'~ck 7 and the lend trpCl% ~ (the recording n~ar1~ arrays 22 and the pit rowe 22.) in the rewr±t~4e area 5 o~ the eptical disk 1 and z-e~lecte~i light from the tx'aok 9 (the pit row 29) in the read-only ~reas 2 and 3, and converts the reflected light into a reproduction signal. The swtirning amplifier 111 generates a sum signa4. 81 indic&t±ng the sum of two detection signals obtained from the two parts liQa and ilOb of the 2-part optical detector 110 to supply to the switch circuit 113. Thp d±ff~rential amplifier 112 generates a difference signal 8~ ~epz~e~en'ting the dif~erence between the two 4s~ect4.on si0nali to su~p2.y to the envelope detector 120. ~rfr 5~itoh circuit 113 switches between the sum ~ $1 ~n4 t~e differ*noe signal 12 to supply either si~n4 to th~ dig±t±ziitg circuit 114. The envelope &~t~ctor 1~O 4etects en •nvelop0 in the difference •i~na1 S~. ~har~ en a~np~.ittad~ el~oeeding a predetermined ~hrs~hold i~ observed iz~ the dift~rerkoe signal 82, a cc,ntrc~1 s4gpal 83 Lu uupp:Lied to the switch circuit 113 ~Q force t~i~ switch cirouit 113 to sw4tch to output the 444 e~enc~ ~ig~al 52 as an output signal 14. t~ the case of u~±ng the data formats shown in Fig~irep 2A to 2~, the difference signal 82 is obtained OrxJ4' whprx the reproduction signal is obtained from the first header region 2.1 in the rewritable area 5, as will bo deacr±be~ later ±n ~ptail. Accordingly, as shown in Figure 2~, the control signal 83 output from the envelope ds~ector 120 becomes high only when the first header region 2.1 in the rewritable area 5 is detected. The output ui~na1- 64 f±'on~ the switch circuit 113 is therefore equa~ to the &Lff~r,nce ~ignal 82 Qnly when- the first hsad.r r~gIor~ ~.l is d~tected, Otherwise, the output signal 84 i~ oqua2. to the sum signal 51. That is, the 5u311 signq~. $2. is output ~rorn the ewitch circuit 113 as the outpl.at signal 84 when the reproduction signal is obtained from th~ information region 20 in the rewritable ares 5 ~nd the entire re~d-only areas 2 and 3. The output signal 84 from the switch circuit 113 (the •surn signal Si or the difference signal 52) is supplied to the digitizing circuit 114. The digitizing circuit 114 digitizes the output signal 84 into a binary signal in accordance with a threshold set for each of the suni signal 81 and the difference signal 52, for example, an~ outputs a digital signal S5 to the PLL 115. P~4. l1~ ~tr~ci-tu a reproduction clock from the 4$gi.t4~. p4.gnal $8 axi4 outputs the reproduction clock tc th~ ~D r~product4.pn Oircuit 12.6 which reproduces a sector ±dent~.f±cation signal from the header region. The titnin~ gen0ratOr 12.7 det~rznines the start timing (the heeds 16 and 36 of the data regions shown in Figures 2A and 25) for reading the u~er data recorded on the data regions 17 and 37 based on the sector identification signal from the PID reproduction circuit 2.16, to initiate the demodulator 118 by supplying a control signal 16. The demodulator 2.18 demodulates the user data and outputs the r~sults. ~ereinbelow, the wavefor~tis of the signals obts~n~d whAr~ reoord*4 det~ on the information track in the r~i#z'tt~b1e area ~ (i.e.. user data already recorded on the information r~g±on 20) is reproduced until it is c~nvertsd into a binary ~ign~l will be. described. Figure 20 is an output waveform of the sum signal Si obtained fxom the rewritable area 8, and Figure 27 is an outpvt waveform of the ~i~ferenca signal 82. Au shown in Figure 20, the portion of the sum signal 81 corresponding to the first header region 11 in the rewr±t~b1-e area 5 is not detected by t~±e digitizing ~:Lro1V1it 114 because an amplitude 42. thereof is smaller ihan a ~r*determin.d ~hrpuhold 40 for digitizing. The reft~~on why the amplitu4e 4Z iii small is that the pit row of the first header reqion 11 is slightly displaced outward (the forwar 1~a~t ila) or inward (the latter hedf lib) frott th~ center line of the groove track. This c~ses a 14.~ht beam ~c~m th, optical head to be 4i~rWcted by the pit ro~ 21a and lib and thus reduces ~ie light amount received by the optical detector 110. Orj the contrary, an amplitude 42 of the sum •4~gnal 81 corr~spcnding ~o the information region 20 in the r~writa~l~ area B •~c.Cdo the threshold 40 for dicing beceu~e the recording mark array 22 is formed along th~ c~nt0r line of the ±nform~tion track. The sum signal 81 is therefore deteoted by the digitizing circtiit 114, and the reprod~ction signal is obtained. Figure 2F shows an output of the difference signal 82 obtained from the rewritable area 5. Since the pit row 21. in the former half ha of the first header region 11 is displaced outward, a larger amount of refiected light from the pit row 21a is diffracted to the outward part ilDa of the 2-part optical detector 110. Aooozdingly, the d4Vff~r.nos signal 52 output from the 2-part optical. 4e~ootor 110 ha~ an ampl±tude 51a which e.~oaedo a po*it4.ve thrashold 50. ~or d*gitizing as shown in F±gur~ 2?. The difference signal 52 is therefore di*tecte~ by the digitizing oircuit 114, and the reproduct4.on signal is obtained. Likewise, since the pit row 21h in the latter half llb o~ the first header region 13. is displaced inward, a J.ar~er s.mount of reflected light from the pit ~QW 21b is diffracted to the inward part liOb of the 2- part optical detector 110. Accordingly, the difference s.L~na1 $2 output from the 2-part optical detector 13.0 has azi ~mplitud~ 81~ which exoe~4g a negative threshold SOb ~ ~i±~itiz±~g s~ shown in F4,gure 27. 'Vhs difference s:L~n4 52 is there~or~ detected by the digitizing ciroui* ~.14, s.r~4 1~il~ re~ro4uotion •ignal is obtained. On th~ contrary, in the information region 20 in the rewritable area 5, since the recording mark array 22 is formed aJong the center line of the information track, the light amounts received by the outward and inward parts hOp and hlOb Qf the 2-part optical detector 110 are substantially the same~ Therefore, an amplitude 52 o1 the difference signal 82 is too small to reach the thre~hold 52.~ (5Th) for digitizing as shown in Figure 27. Likewise, in the r~ad-o~ly areas 2 and 3. since the pit rc~w ~9 ie forc~ie4 alor~g the center line of the track 9, th. light amQunts received by the outward and inward p~±ts IlOa and 2.10~ c~ the 2-pert optical detector 110 •~ subota~t4elly the s4.jne. The d±~ference signal S2 is ~u~1anti,lly z~ot otatpw~. Therefore, in the regions oth~r then the first header region 11, the difference signal $2 i. not detected by the binary detector 114, and thus no reproduotion i±gnal is obtained. Figure 211 shows en output waveform of th. sum s:Lgnal $2. obtained from the read-only areas 2 and 3. Referring to Figure ~H, since the pit row 29 i* formed 4~.dn~ th~ cen*!r line ~f the track 9 for servo tracking *n the re~d".on~.y areas ~ and 3, the sum signal 51 has an ar~plitud~ 4~ suff±c±ent3.y large to be detected by the b~nary detsctor 114. Thersf ore, si~na2.s from all the regions in tile repro4~ction-on2.y area~ 2 and 3 including the second header region 31 and the ~eoond data' region 37 b* oonvert~ ihto bir~ary s4~gna1s by use of the sum ~i.pial ~1. Zt is n~t ~ecesu~ry, therefore, to switch the switch circuit ~43 for tile read-only areas 2 and 3. Thus, in the optical disk recording/reproducing ~pparatus iQO for rep'oducing information from the o~tic&l di~1~ 1 with th~ abQve~.described data formats, i~4~ ~he convenflon~l •pparat~s, separate reproduction s4gnai p±oosseinp circuits for the rewritable area and th~ r~p~odi.~otion-v~2.y area are not required, but a common signal pr~ces~ing section can b0 used. This reduces the circuit ~i:e of the optical disk recording/reproducing apparatus, and realizes a reproduction signal processing circuit with a simpler configuration and higher reliability. (Example 2) Figure~ 4A to.4H show data formats of an optical disk of Example 2 according to the present invention. Th~ basic configur~t±on oi che optical disk of this e~ample is the same ~s that of the optical disk 1 of same cornpopents as those of the optical d*sk J~. are denoted by the same refetence numerals, and the description thereof is omitted here. In this exampie, ~ in Example ~., one track corresponding to one rotation of the optical disk is divided into a plurality of sectors. Each sector starts with a header region including sCotor identification data representing address information of the sector. In thie example, the data format in the read-only area will mainly be described. figure 4k is an exemplified data format of each s~ctor 2.0 in the rgwritable area 5, and Figure 4C shows ~ ~h~v~ioal do 4.~u~at4.on o~ the inforin~tion track correspon~ir~g '~o t1x~ a~cto~ 10 of Figure 4k. As shown in ~ 4~, th~ ~roova guide track 6 constitutes the ~oove t~eck 7 and s land between adjacent grooves coz~gtit~.1tee th~ land jrsok 8. $uoh groove tracks 7 and li~n4 tracks 8 alternately appear in the rewritable area 5 of the optical disk 1. The user can record desired information (User data) on both the groove track 7 and the lend treck 8 by tracking the groove track 7 and the land track B separately. ~n this example, as Shown in Pigure 45, the groove ttsck 7 and the land track 8 ae described collectively ~ an information trsck 6'. The sector 3.0 in the tewr4.t*ble aro~ ~ includes the first header region 11. at th~ head th~teof, '~'he first header region 13. Lu divided into the former half ha (sector identification dat~i PIDi) and tile latter half 2.2.b (sector identification data PI~2)9 As uhow~ i~ Figure dC, the physical pit rowS 22.. and ~1b are ~or~ied in corrempondence with the ~o~xfler half 1~ sr~ the 4.att.r he~.f hib, respectively. AS shown in Figure 4C, tile width of each pit of thp pit rowp Zta art~ $1t~ in th! radial direction of the optical d4si.e 1 ii ~ubStantially equal to the width of the ~uid~ groove 6 (groove track 7). The pit rows 21a and Vt ar~ 4ispleoed outward or inward (i.e.. in the oppoaite di~ect4pn0) from the Center line of the guide groove 6, i.e., wobbled, by about a ~.zarter of the pitch at' the gu±4t groove 6 (groove pitch Tp). In this examp~e, the pit r0w 21. 4s displaced inward, while the pit row ~24~ ±~ displaced outward. Thus, by displacing the pit rows 21. and 21b from the center line of the guide groove 6 (the groove track '7), the first hea4er region 12. is commonly used to track either of the groove track 7 and the land track 8. Separate exclusive header regions for the groove track 7 and the land track B are not required. Referring to Figure 4k, the mirror region 12 (Id) follows the first header region 12.. The mirror region 12 is flat with no groove oz pit formed thereon and used to dpterm±ne en otfset of the servo tracking. The ~a~i rQ4.on 2.3 (GA?) *QZZOWS the mirror re~4oh 4. Tt~S gap r4gicrs 2.3 $• Iorjned on the information trap~t 0~ to avoid a hea4 24 of the information region 20 froni ovtrlapping the iiiirror region 2.2 or the first header region 11 when a jitter occur! due to the rotation of the optical disk 1. The information reg±on 20 which stores information and data includes a first guard data region 23 (ODI), the first dummy data region 2.5 (VFO), the first date regioti 17 (DATA), and a eccond guard data region 18 ('3D2). The buffer region 19 (BUF) is formid between the i.nf0rrnation region 20 and the first header region 11' of the nect sector 10'. The first guard data region 23 i. formed to e:neura the stability of the reproduction signal processing circuit. The first dummy data region 15 is a VFO region where a specific pattern (a specific bit length) of the n'iodulation code usec5 for modulation of data is 4~W,nt±allY reoord*d to promptly and stably clock the ~'LZi ~if th* reproduction s4.gn~1 processing oircuit. uSat' ~ ±ncludir~g ~n error correction code is ~i~cor4~d oti the fl.rpt d~t~ region 17. The second guard data region 18 ~s for~nad fqllQwing the first data re~Lon 17 to ensur, the pteb$I.±ty of the production signal pro~susing c~rcu±t. The bu~qr region 19 which includes no 4ata is formed to #vod.4 the and of the information region 2Q from overlapping the header regl.on 11' of the next sector ~.Q' when a Jitter oQcur~ du• to the rotation of the optical disk 1. like the gap region 13. ~nformat±on is recorded on the information t'E~giQfl 2Q ~r ir~adiatir~g the reoording layer formed on t~ di~k 5u~~tr4to cC the optical disk 1 to change the optic~1 Vpert$05 (re~•ctanoe) of the recording layer. Jror eae~'p~.0, an irzadiated portion of the recording layer niay be changed from a crystalline state to an amorphous state so as to form a r~oording mark with a reflectance di~erent fro~n that of the other portions. As shown in ~i.gurs 4C, the recordinc~ mark array 22a is formed on the g~rpove track 7, whil* t~e rsco~d±ng mark array 22b is form&I on the- J arid track 8 Thus, in the rewritablg area 5, the groove track 7 and the 1-and track 8 are formed in accordance with the above-~escribed dat* fo~,nat to record data in th. area, fe~'r~.r~g to Figures 4~ •nd 4P, a data format in ~ ~esd-on2.y areas ~ and S will be described. In this p~%Sm~le, as in ~camp1e 1, the data format in the read~ly areas i~ matchpd with the dete format in the r~,writ~b~ area. Fipt~r~ 4~ shows an exemplified data ~orm~t of eE~ch sector SQ in the read-only areas 2 and 3, and F~igure 4D sohematic4ly sh~wu a physical configuretion of the track compon~d of the pit row 2g correspondirig to th~ •ecto~z 30 oI? Figure 45. In the read-only aeas 2 ~nd 3, the track 9 ii cottiposed of tile pre-rsco~r3ed pit row 29 (a pre-pit row). M ~hpwn 4n 7~.gure 4~, ~ the pit rows in the read-only ~ and ~ a::a formed in accordance with a uniform p~ysic~l format. Moz!e specifically, the width (pit width) Qf the pit row 39 in the radipl direction of the optical disk 1 is small~r than the width (groove width) of the guide groove 6 (groove track 7) formed iz~ the ri~writab1-e area 5, and all the pits are lined substantially along the center line of the track for servo tracking. ~eferring to Figure 43, the sector 30 in the reacl-only armas 2 and 3 includes the second header ~gton ~1- (pe~tor Identification data PIDi and PID2) and th~ 0~cQM 4~ta ~region ~'7 (1~At~A). A second dummy data r~±Ofl ~$ (p$y~) is fo~m.d between the second header he eecpnd data region 37. A third dummy data ~sgion 34 (DMY2) is formed between the second data region 37 and the second header region 31' of the next ssctor SO'. The sector identification data PIDi and PZD2 of the secon" h~?~ader region 31 are repeatedly recorded on the former half and the latter half of the second header region ~1, respectively, in compliance with the sector id*nt±4catJ1.on data PIDi and PID2 of the £irst header ~gion 1±, so that ~hs 1-qngth ~f the second header ri~1.oti 32. becomes sukatantially the same as that of the ~rst header region 11. In t)~e second header region 31, however, the pit row is not wobbled as the pit rows 21a Srid 21b of the ~irst header region 11, but is lined sub~tantially along the center line of the track 9 for servo tracking. The 4.nforniation amount recorded on the second data region 37 of one sector 30 is made equal to that of the first data region 2.7 of one sector 10 in the rewritable area 5, and the same format as that in the rewritable ~-ea ~ is ,.ised for an addit±on~l error correct~.on code and the like, With this arrangement the length ~f the ~eoopd d~ta region 37 is substantially the same as that of the ~rst data region 17. Z~ general, data recording in the read-only area ip perfor~ne4 by embossing with high precision at the te4,ricetion ot the dis~c. Zn the read-only area, data is only repro4uca4 ~nd no nrrangCfl~ent to respond to rewritirig by the user is required. Th~rsfore, regions such as the gap region l~, the fi.r~t guard data region 23, the peicond gu~rd data region lB. and the buffer region 2.9 formed in the rewr4,t~ble atee are not required. These r~gion8 sh~uld be d.l~ted if the recordAng capacity of t~e pp'~ica1 ~isk is considered with priority. However, if these ~egionu are deleted, the data format in the ~'aad-on1y area becomes different from that in the This r0quires to p~~ovide two separate 4.~4u~ive •4.~r~al proo~p~1.ng •~ct±c)ns each including a t~.ming gsn4r4.~Pr ar~d a deni~1ulatoZ' for the read-only area or the rew~itab2.e area, and switch the two processing !e0tiOfl~ SpPrOr~at!~.y, as in the conventional apparatus, and the buffer region 19 in the r;awr4t~Lble 5Z'5, 5 ~re formed in the read-only area so au to ~ync~rp~±~ the r~production timing and no pit row is ttn~4 4.n ~he~e r~gio~3, the tracking error signal is d{scontinued at these regions, making the servo tracking in the r~ad'-only area unstab).e. In order t~ overcome the above problems, in this example, the second dummy data region 33 is formed b~tween the header region 31 and the second data region 37 of each sector 30, and the third dummy data regi~n 34 is formed between the second data region 37 and th~ second header region 31' of the next sector 30'. A bpecifiv pattern of the modulation code used ~ ~1ohi1.StiOfl of dat~ (a pattern of a specific bit ~ngth co±r*~POfldir~g to a specific pulse width and pulse i~erv~l) p~ ~ the 4z'~t dumm~' data region 15 (VFO) in tt~e rewrit~ble ar~a 5~ for example, can be sequentially z~e~orded on the second ~nd third dummy data regions 33 and 34. Using suvh a apecific pattern, prompt and stable clocking of the PLL of th~ reproduction signal proce~jsing circuit can be realized. A mirror region, may be formed between the second header region 32. and the second dummy data region 33 as in the rewritable area. When ~ r~cord~4 on th~ optical disk of this 5215!1$C i~ to be ~e~roduo~, the Same procedure as that de.r1A~e~ in kxamp2.e ~ w4.th the optio~l disk record±n~/zeproductr~ apParatt~s iQO s~iown in Figure 3 can be er~1-oyec~. In this ease, the waveforms of the envelope detection signal, the diffqrenoe signal obtained from the rewr±tab1-e ares, the suni signal obtained from the rewritable area, and th~ sum signal obtained from the reed-only area are as sh~WV~ in ?igures 4~ to 411, respectively. Thus, in thi..S e fl~ple, the sector lengths and main port±~n~ of the 4ata formats of the rewritable area ~nd the re~d-QT4y ar~as are made substantially equal to each other. With this arrp*,gsment, the sectors in the read-on~.y areas and the rewrita~1-e area can be managed in the ssme me~per, aM the processing ~uch as sector re'~riaval c~r~ be unified. Thus, one reproduction signal p±o~ising circuit t~an ha commonly used for the ~e~4jsble a~•~ a~d t~e ro*d-only areas. This reduces the o~.rcui~ size. In th~p enAmplqa. the first data region 17 in the rewrit*ble ares and the second data region 37 in the ~?4.ad-c~ly area are ~rran~jed to start ~t the same timing ap shown in Figures 4k and 49. The unified sector m~iragemett ~coordi~g to the present invention can also be ro4lizs4 iti the opine where these data regions are disyflpced with eac~'i other as long am they have the same l~an~th. (4amp~.e 3) In *ntihple 3, s data sequence which realizes stable ~~tVo tracking #t tM reproduction of data record •dt in tM c4ad-oniy ar0 411 be dest,ribed. In this •npmplq, the d#ta tormat$ in the rewritable area and the read-oN.? areus d~porib~ in Example 2 are used. In gsnerql, the tr~oking control along a track of ~ optic~. 4iqk 0sh be %~erformed by a variety of methods. For e~psplp, p phase difference detection method is Rfl'plO?04 as an effpctive tracking method for the track qcr~pipt4.ng ot the pit row 29 shown in F'igure 4D, for extmple, As de;cribed in Enample 2, each of the second and third dunupy data reg$ons 33 and 34 shown in Figure 43 includes a specific repetition pattern of modulation codes used for mo4ulatiori of data (a pattern of a specifiv bit ler~qth corresponding to a specif to pulse width and pulse interval). When puph a specific repetition pattern i.e formed on adJao*nt trao)%s, however, the servo tracking by the $4WSA difference deteQtion method becomes unstable. The repSon why tile servo tracking becomes unstable will be described $n d9tpil as follow.. The principl0 for obtaining a tracking error signal by the phase difference detection method will be first described with reference to Figure 5. A beam Spot 57 tracks the pit row 29 constituting the track 9. Light ~f the beam spot 57 is ref lected by the pit row 29 end the ~-efl~otsd light is detected by a 4-part optical d0tec~ot 58. ~he 4-~att opticaJ. detector 58 oonverts the reo~4.v~4 light into ~rz electric signal. The 4-part Q~t4-QSl d~tS~tOX 8$ 4.n~u4ss fQuz~ part. A, B, C, and D. A *Um aignal ~ii oorre5pQndii1g to the sum of the parts A an~ C ±~ ~eneret~d by pn ~pe4tiQnal ~niplifier 59, while a ~um signal 813 ~orr~sponding to the sum of the parts B and ~ i~ generated by a~ opez~a~ional amplifier 60. A pha~s cQmpar~tor 81 oompares the phases of the two sum signals ~11 and 812 to generate a tracking error signal S1~. When the beam spot 57 is displaced outward from the center line of the track 9, the reflected light is diffr~ote4 at the edge of the pit row 29, and thus the ph~ps of the sum signal 511 of the parts A and C prooeed~. O~ ~e co~t~a~y, wh~ the beaii spot 57 is displ~~d ±~W~rd from the centor line of the track 9, the phese of the sum signal 512 of the parts B and D procje~ds. ~he phase 4±fferenoe between the sum signals 811 •nd 813 is 4steoted by the phase comparator 61 and ootiverIeL~ into an electric •±g~al, so as to obtain the t~eo)dng srr~~ ~ignai. ~ representing a ~isplecement of 1hs besn~ spot 87 from th* center line of the track g• F$g4ret~ 8 and 7 ~oW tracking error signals pbt~n0d by the phase d fetanco deteotiori method when b*~m spot 87 ±0 d±splec~d from the center line of the treo)~. ~ 5hOW~ output waveforms of the sum $2.1 •n4 S1.2 obta4.ned when completely the same dw~a potte~n has been recorded on a target track 9a Ce pit row ~9a) and a track 9b (a pit row 29b) adjacent to the 1ze*~get ~re~k 9. and the be~n !pot 57 deviates from the target track 95. As shown in F±g~4re 6, a path 64 of tt~~ beep spot 57 is~ dim%leo~d from the target track 9a. Xr~ the above case, li~t of the beam spot 57 is 44.f~radt~d towed the ports A and U by the outward edge ~ pit rc~t ~ of the target tracc ~a. At this time, ~vex, ~inc~ th~ ~djsc~nt treok 9b has the pit row 29b with th~ eame z,atter~ ~s that oi the pit row 29a, the ~h1 of t1~e beam spo~ S7 is aim4ltaneously diffracted tc~w~rd til~ parta C eM D by the inward edge of the pit row ~9b o~ the odj,oe~t track 9b. As & result, as shown in Fipu±-e 6, no phase difference exists between the sum signal 811 of the parts A + C and the sum signal 812 of the ports U + D. Thus, the output of the tracking error signal 813 is zero though the beam spot 57 is actually displaced from the target track 9a. Ain described above, when the tracks 9a and 9b ad~aoent to each other have pit rows with completely the ~a~a pattern, the tra~king error signal 813 is not ~u~er~tp4 even wh~~ the b~em spot deviates from the ~i.8 z~akS~ ~he servo t~aO4ing unstable. ~gure 7 shows out~.it wave~orma of the sum signals ~11 and ~2.2 when a data series Mfferent from that ~f tile target trec~c 9e has been recorded on the adjacent track 9~. AS in Figure 6, the beam spot 57 traQks along the path 64 dipplaced from the target track 9a. .tn the above case, as in the case shown in Figure 6, light of the b0am spot 57 i. diffracted toward the parts A and B by the outward edge of the pit row 29a o15 the target track Qa. At this time, the light of the b~I~ p~ot 57 4-s shno 4i~~acte4 toward the parts C and D ~y th* ir14~4 edqe of the pit row 29b of the adjacent 0b~ Zn '~hts case, hQwever, the patterns of the pit ~c'w~ pr~ different be~we.n the te~get track 9a and the •djsoewt track 9b. Accordingly, since edges of pits on the two adj~~nt tr~cku 4o not c0incide except for posit4-on5 65 ~d 66, a phe~~ difference is generated betwssn the sum tignals 811 and 812, though at the positiOns 65 end 00 the outputs Qf the sum signals 511 an4 512 ~re the same a~ in ~he case shown in Figure 6, generating no p~a~e difference. When patterns of the pit rows of the target track 9. •nd the adjacent track ~b are random having no correla~±@~ with eaoh ~th~r, the pobitions where edges of pit~ of 54j*O~n~ tr~oku coincide ~s th0 positions 65 and ce ~how~ ir~ ~4-gur0 7 a~.so appear ra~dcm1y. The frequency Where such edg& coincidence oo~urs is therefore eufti~$e~tly ~ Such rendom occurrence of the pit-edge ±noidC~Oe hardLy affectS the gen~rstion of the tracking •tr~v s34ns4. $13 ib tile ~r*quency range used for the *~owevsr, w~$n t~ie phase difference between the ~UO~ signal. bil end 512 4-U not obt~inSd over the entire ~eeon4,or t~iitd duflinly date region 33 o~ 34 as shown in ~j.~14~0 6, f~r ~1PX~P the tracking error signal 813 is gS~*rtt*~ eo little ev~n when the beam spot deviates from th1~z~~t t~a~.k the~ t~e sarvo tracking control becomes ~e~gin~e Low, data formats of the second and third dummy 4~tA rop4.ons 33 and 34 which' are effective to p~vpnt the disturbance of servo tracking as described a~ov~ will be descri~,ed. Figuz'0 BA shows an exemplified data format where the ~econ~ and third dummy data regions 33 and 34 include M-sezies random d4ta regions 73 and 7'~, respectively. By setting different 4-nitiel values of the M-.eries random data ~ at least adjacent two tracks, the patterns of pit rowS on t~* edja;en~ track. ilav~ no correlation with e~r~h oth~r, arid thus th~ coincidence of pit edges between th~ ,~p*r~t tr*O)~ i~ ~la4a rendoni9 A~ a result, the ~*~vo t~;ki~ ~ ~e ~h*s~ ~ror d~t*otion method can be FigU~-e ~* shows an •~p~ified data format where the ~ecoru~ dum~w date r~Qion 33 includes thB M-aeriea random data region ~3 as shown in Figure BA and a subsequent VFO region 75 (VTQ~.) composed of a mpeoif{c pattern o~ the modvlation cod~ Qsed fcr modulation of data as tilat used on the VFO region 15 in the rewritable area (see Figure 4A). B~t ir~cludi~g tile VTO region 75 (VYOl) in the lgztter pcrt4.on o~ the secor~d dummy data region 33 am •howr~ in Fig~re ~, the clocI~ing of the ~LL of the r*~prod~otion pi~'n*~. processing circuit for the subsequent d4~ta region 37 cpn ~e stabilized. The tracking error ~gn~l 8~.3 i.s tio~ gene~ated from the VFO region 75. ~Iciwev~r, •ince the ~FO region 75 constitutes a part of the dummy data region 33, the servo tracking can be st~b4-li~ed before pnd efter the VFO region 75. Therefore~ no practical prcbletn ariaes. F4-purea SQ ~pd 81) s~iow .~tsmp~ified data formats wh~rs t~'e ~*oo~4 4~.aflW~r data zs~on 33 includes data uynch~onoUe *e~iee 7~ and 7~, respectively, which can ~pec±fy the tit~iinq ot th~ *ta~t of the data region 37. FigurCin SC and S~ show sectoz.s of an even track and an odd track. respectiVeJ~y. As described ~b~ve, in order to secure stable servo tracking by the phase difference detection method, adjacent tracks ns~d to have data series different from each other. The differant data synchronous series 76 and 77 ~• therefoze provided in the second dummy data ~pgions ~3 a~ the even track (Figure SC) end the odd t~Ok (P'i0ur* ED). ~ef erring to ?igure SC, th. data synchronous ~ries 7~ of the even t~eck count! up at an end value FT ($ex.). With this arrsn~em~nt, due to the regularity (aQL~n~±fl~ ~) o~ the s1~a syrW~hrono'.±s series 76, the ~in~.ng can b* deteoed ira ~eu1. time until the start of ~*'e date ~gion 3? by the second dummy data region 33. T~.in ~stjrSs tl~e identif4-0e~iOfl o~ the start of the data r~igion ~7 Re~e~ing to 1~ig14re Bfl, the data synchronous ~ 7? o~ ~e odd ti~c)~ counts dewn at an end value 00 ~ WVth thii~ arrangement, duB to the regularity (c~ounting down) of the data synchronous series 77, the ~ can be detected real time until the start of the d~t~ ~g$or~ ~7 by tile second dummy data region 33. Th~in, the •xei~p~ified data formats shown in ~iq~r~s SC en4 SD where c~$~faren't 4ate pynchronous series are prov.tde4 in Che second duin~y ~ata regions 33 of the ~4eo0rit t~apks ca~ pta~b4.2.i~e th~ ~sryo tracking and *nsures the ~~tSotion o~ the start of the data region 37. Zn this •~ar~pl~, the sezvo tracking by the phase •rzor de~e~t±on rnst~od can be relatively stably con~ro1led by using random data series for the second dummy d~t~ ~e~ions 33 e~ adjacent tracks. Also, by using different data synchronous series for the second dummy data regions 33 of adjacent tracks, the detection of the start of t~e data re~icn 37, as well. as stable servo track4-r~g, can be ensured. Data sequence suitable for servo tracking can be also used for the third dummy data region 34 in a manner s.Lnvilar to that describad above for the second dummy data region 33. In this exam~.e, the data reproduction (servo tracking) in the ~.ed-oi4y a-*a wa~ described. The data pto~uct*cn ~.n the r~wzttab1.e area can be performed in t~e n~enr~ 4es~d in empj.e ~. with reference to the ~flcp~. disk r0cord4-ng/r~pro04oi~p apparatus 100 shown in ~gure ~. UCxample 4) In ~xample 3 above, the pattern of data (code.) rocorded en the dummy datg regions can be directly generated at the data reproduction. In this example, a modulation code is used to reduce the correlation between dummy data recorded on adjacent tracks. One value i~ initially determined as data to be •c~$~~ o~i th~ dummy data region. Th4.u value is scrambled to gsnel'ate data with little eorrelation. For •)~~4~1p2~S, (U), (OD), and the li)~e in the hexadecimal raot~ti~ oon~ist o~ bits of 0 or ~.. Ba~ed on this value, data can be ea~ily gener~ted, Scrambling is realized by Zirst generating random d4ta such as an M series from a certa4.n initial value and calculating exclusive-OR between this randOm data and data to be recorded. The method of generating scr~mbled data idll be described in ~etail in a later example. Zn the case wheze the same data to be recorded ~r4 tile same initial values are used, data obtained after t~ Bcramblin~ ar~ ~he SSme, I~owever, if the initial vat~0 are di~~r~nt the data to be recorded are thp same, t1~e oo~we1ation between two data obtained after the scrambling can be re~uced. Uowever, using different 4itial Values for all the sectors is difficult since a cQr~m±dsrab1y J.~rge number o~ initial ~ra1-ues are ree~uired. 1Z~ p~0tiq0, ~ow~ver, uui~ d4-fferent initial values f~r adjaoent a~otors is enau~ to reduce the correlation between the ~u~nmy ~ i~eg±on5 of the adjacent tracks. 'rMt is, the s~e in4.t~.a1- values can be used for sectors Q~ ~ aeme t~-aoJ, X~ the osee whs~'e the number of ~aotc~s ir~c1u~e4 in cn~ trao)~ varies, the number of con V~uc,us s~tors hav4.n~ the same initial value should ~t l0~5t ~x0 m~4dr~u~p ~be~ o~ s~ctors included in one t~c3~ As~u~ that ~he nuwb,Z o~ continuous sectors having the same initial value i~ M end the number of initial values is N. The actual values of M ahd N can be co1ver~iently deterirtined based on sector address information included in the sector identification data. For e~mple, if $.s~~yte data is ~jsed as the sector addx.ss in~ormation, a~ou* 18,770,000 sectors can be opver~. I~ the values of M and N are powers of 2, s~r~ii~Xqd 4at, ~n ~s a~~i1-y ger~ereted. Zn this example, the case of N~ w 16 and N m ~ will be described. N in4t4al va1-'i4es oan be obtained in the following manner, ~oz e~e. F$rSt, th~ ad~zeins information included in th~ per4d~ tieio,tiora data is represented in the ~ no~t±on, and 4-bit data corresponding to the fifth t0 eighth bits from th~ learnt significant bit are u~ed. U~±ng this 4-b4t data, N • 16 initial values can be obtained. Th~ initial value is renewed every M • 16 sectors, and one track i~icludes 256 sectors at maximum. Since 16 contin4ous sectors have the same initial value, it iS ensured that the initial values for scrambling are different between adjacent sectors for tracks ~aoh having 1-6 to 256 sectors. Pata to be recorded is scrambled using one of these initial values, modulated with reoordinp code, ar~d recorded on the dummy data rU~g4 on. Zn this war, by scr4mbl±~g the same data using differeht initial val~s b4twe~n aor~eP~onding sectors of &djacent tr~oks, different data series can be recorded on the dummy dp~a regions of the corresponding sectors of ad:jacent tracks. Thus, in this example, since random data series can be effectively obtained for the dummy data regions of adjacent tracks, the servo tracking by the phase error detection method can be relatively stably controlled in the read-only area. (~xen1plG 5) In this exarnp~.e, data Series ±r~ the rewritable atep or the reed-only ereas for realizing effective s~ictor management will be described. Au described with reference to Figures 4K and 43, for example, data to be recorded on the optical disk is divided into parts for a predetermined data capacity corresponding to the data region 17 (the rewritable area) or 37 (the reae~-only areb) of each sector. An error correction code is added to the data for each sector. Puoh ar~ error o~rreet±on code may be complete within each 0~ictOZ~. ~lternat4-vely, error correction coding may be rf~Z~ned for a set of a plurality of sectors. Such a ~Xito$~ of ~ ~l~rs~41~yof sectors i~ referred to as an ECC b1QC~, which is a unit for error oorre~tion coding. When one ~Cd ~ iw rnpo~4 of k sectors (e.g., k • 16), an errox~ hpvin~ A length of about ~ne epotor can be corrected. Using such an error correction code, the number of psotor~ ii~ the rewrit~~.e area end that in the read-only ar*a are ~ult4-p~ss of th~ number of Sectors in one 2CC blor.*, i.e., multiples ~f k. Zn order to effectively manage sectors of an o~icel di~k, tne sectors in the rewritable area and the r~Rd~-OnXy ~zea ar~ preferably managed with track basis. H3wever, th~ number of sectors included in one track is not neo$ssan$ly a multi-plc of the number of sectors included in one ECC block. Accordingly, when data is recorded on a plurality of ECC blocks of sectors, the data i~ not necessarily completed appropriately at the er~d of one track, but often ends midway of one track. In the rewritable area, the tracking control is possible •v~n i~ 4zhe~e are re~eir~ed sectors with no data recorded thpreon be~a4sb t~e groove or land track has been formed as a guide tr*ck. Zn the read-only area, however, the p~.t row is discqntir&t~ed by the sector with no data recorded th~rson, and thus the tracking control becomes unstable. In order to overcome the above problem, in this example, dummy data is recorded on sectors left unrecorded after completion of recording data to fill the entire track with data so as to realize sector management with track basis, An example of such dummy data is a specific repetitiQn pattern of a modulation code (a specific pulse width and p4lse interval) as in the VTO region 15 in the r~w~i.tabl0 area. tiui~g such a pattern as the dummy data, ~ o~ ~ re~roduoti.on signal p~oc0suing circuit can ~ op~a1ed ~ t~he !ector where user data has not ~e.n reco?dCd. 17i this Cxampl0, M-ser4-es random data and a data synchronoue s~r4.es as 4-ri the second dummy data region in ~am~le 3, as we~.l as ecrarnbl~d data as in Example 4, can be used. Figure 9 shows an optical disk 1? of this e~amp4e. As shown in Figure 9, dummy data is recorded on sectors 71 in the read-only area 3 at the junction with the rewrit.ble area 5. Likewise, dummy data is recorded on sectori 72 in the read-Qnly area 2 at the junction with the rewritabl, area 5. Thu., in this e~cample, when data is recorded by •very p~edet~rt~ined recording unit ~uch as the error corxection b.~ock (~CC), a sector left with no data recorded thereon i~ fi-lied with dummy data. With this arrangement, the rewritabls aZ~ea and the read-only areas always start at the ilead of a track. This ensures effective management of sectors on thp optical disk. (Example 6) In Example 6, specific eacamples of data formats of the sector 10 in the rewritable area and the sector 30 i~i the read-only areas will be described. ~'4.gures ~.O& aM 303 show a data format of the spotor 16 in the rewritabte arep, while Figures XlA and UP show a data format of the $ector 30 in the read-only ~reaW~ #'irst, generation of data to be recorded on the data region fl of the sector 10 and the second data region 37 p1 jte sector IQ will be described. MsutRq that the date amount recorded on one sector i~ 20403 (bytes) for both the sectors 10 and 30. To tut~ s~toi*nt, 4~ for data I~ $t~dicating the data region rwrnter (sector ad4ress), 25 tor ISP for error detection ot th0 d4a Zb, 68 for RSV as spare, and 43 for EDC for ~rt0V deteot4.ori of the entire data are added. All of th**e ~ ~re ~o%leot$ve1y referred to as a first data 4fl~t. The data lez~gth of the first data unit is thus ~C'48 + 4 + 2 + 6 + 4 — 20645. The information data portion (2048B) i. then scrambled in the manner as described below which is the same as that used tor the dummy data region in Example 4. First, a shift register is constructed so that s5.o4led N-series data can be generated, and an initial v~.ue is 4et~rmin~d. ~~bis initial value is sequentially ahiftsc~ through the s~itt regist0: tn synchronizatd.on with t~ ± orxnat4~~i~ data so as to generate pseudorandom dets~ Exclus4.ve-O1~ is opsrat~4 between the pseudorandom di~ta and the information datp to be recorded bit by bit thareby to realize scrambling. Since the ~.nformnati~n data is 20488 which is the eleventh power of 2, a prirn~.tive polynominal expression with the eleventh or higher power of 2 is required as the M s~r±s5. The next higher degree in trinominal to qnquenomi~a). expresu±o~is having a term of the eleventh or hiUh0r power o~ ~ ~niong t~e p~itnitive polynominal *xp.o~0 OQnst~1JOtir~g the 14 ae~ies is fifteenth. Zn t~o ~o1low~4~g ~eZ~ip~ion, a priftt4.tive polynominal e~p~*~s±on ~*vipg a ~~fl1 of th~ fi~te~*vth power of 2 (X16 + + 1) is uped as a*~ #x~ple. Figure 12 shows the FI*ali~atiOn of thi; pr~p~itive polyn9m±nal expression by u~e o~ a shift register 150. As shown in Fi~:e 12, the length of the shift register 1.50 is 15 bi~~ (entries :14 to rO). The shift resister 150 calculates exclusive-OR between the bit in the entry r14 and the bit in the entry r1.0 and feeds back the reS4lt to the entry rO. A predetermined 15-bit initial value is set f~r the shift register 150 and is s~uent±ally ~tiifted in response to a bit clock, so as to gqherats p0sudorandof4 data. Then, exclusive-OR is eE.oulated betWean the eight least significant bits (entries :7 to rQ) of th~ shift register 150 and eight b4.ts (1~) of th~ ±nfo~ma~ion data every eight clocks, and th~0 op *tiOn ie repeAted 2048 times. As a result, inf0X~flat±~n dat~ f~r one Osotor is scrambled. The shift register 150 is reset every sector to reset the initial value, so that the information data of each sector is independently scrambled with n~ substantial correlation with one another. Ase'sme that the nu$ber of continuous sectors having the sem* i~itiat value is H and the number of initial v4jaes is N. The valu~p of lvi and N can be obtaihed from ths sector addres* information included in thp ±dent1.~4czetion date. U the values of N and N are ~c'wsr~ of a. sor4tflblsd data can be easily generated. In this euarnp$, the case of H • 10 and N - 16 will be dpscribeq. N initial values c~n be obtained in the fol1c~y4,n~ menotr, tar example. The address information 4-noldd*0 ira the sector l4entif4.oation date is represented 4n tM b*nan' flQtptton (24 bit length if the sector •ddrsse is 3~), And 4-bit 4ata corresponding to the fifth tp eighth bite frorn t~ Xesst significant bit is used. Ut$n~ t~-4~ 4-kit data, N • 16 initial values can be obThe correeponding relationship between the 4-bit value and the initial value ±s previously determined in the form of a table and the like. The initial value is renewed every N - 16 sectors, and one track includes 256 aecto;s at maximum. The scrarnb24d first data unit! of 16 sectors are put together to constitute error correction codes by Reed-Solomon coding. The data unit of one sector is arranged in an array ot 172B x 12 rows and such units of 18 sectorp •;e put together to form an array of l72~ x 292 rows. A 18~ external code is added to each column of tt4e atrey, and a 10! .tnt~rnal code is added to each row of thit array. A data block of 1825 x 208 rows (378588) —5 — i~ thus formed, which is referred to as an ECC block. Then, the ~QC block is intarle5vmd so that the 165 external code is incl~dsd in each sector. The data of !ach sector is then 1823 x 13 rowa - 23663. The data is then modulated with a recording code. A RL~I (:~.zn length 14.nated) code where the run length a~tar mc4Uj~t*on •tp ~.44~jit~d 4.~ used as the recording 0$~. Ppeoit4.osUy, 4ti this exa~p1e, a 8/16 conversion c~d~ ~ ~ 8-b~ data into l~ channel bits is ~ ~soord±n~ ~ode. Thi~ co*wermion is performed in aocordpn0e with ~ pzedat*~miried OOnvOrB±en table (*tate t~~le)1 this c0rive~siOn table allows one 8-bit d~t~ to oorrpspon4 to fvur atates of 2.6-channel-bit data. A st5te to be uped for conversion of next data is also pred6fined in this conv~aion table. Figure 13 shows en exam~1e of *u~h a conversion table. A 16-bit code series (Ye) ii obtained, for example, by oonvextirig a first data (D) under a state 2~ - 1), T1~. next data is se1~cted under a state speci~*Sd ±n the ~'ao~dP~g conversion ($~•~). By controlling ~hs aslect±pn of the ~tat~, a D~ component contained in the op~-4ing code ~mn bS s4pprpskC~, though the detail ot the ttist)'iod of this oontrol is omitted hers. At thi~ t~.me, th~ r~tinimt.zm a~d maximum bit lengths a~s l±z~i~.ad to ~ oh~nh~. bits and 11 channel bits, ~esp0Qt4~ve1y~ Also, ir~ ~d~r to synchronize the reprodotion, a ~ *ynofr~O~~q~5 o~de is inserted every 91B, l.a., a hElf of one roW of 182~. As the synchronous QOd~, several d±~f~ent 32-ohannel-•bit codes having a pattern Which normally 4o~s not appear in the 8/16 cor~vpr~io~ code are pred~ined. 'thus, the data amount of otis ~eotor is 180k x 13 rows • ~43.8B. ~e *bove-desorLbed date configuration is common~y ~~lo?ed in th~ reWritable area and the read-only $teas, 1~'he thus-obtainbd 24~.BB data is recorded on the first d4tA 1~e~±ori 17 i1 t~ie rewni-table area as shown in ~ i0~ or ori t~ie Second dats region 37 in the read0nly a~ap 5~ shown in F~gUr~ 31K. ~eferring to ?igure 30K, ~n the rewritable area, a ~ postasnbZe re0ion 4b (PA) fo~.lows the first data gioti 17. ThC 8/16 oc~nverting code needs to have an end ma~ at t~-~e end (~f th~ zecording code so that the data c~n be ~orrectl1i dem~dulated at the reproduction. Th~refor~, the postemble region 45 has a pattern obtained by demodulating a predetermined code in accordance with a conversion rule as the end mark. A presyno region 44 (PS) precedes the first data region 17, where presyno data is recorded in order to indicate the start of the first data region 17 and provide byte synchronization. The presyno data is predptezrnined to be 3~ (4~ channel bit) long' and consists ~ ~c~de having a pattern with high autocorrelation. For ~pLe, a patter-n o~ "0000 OXOO 0300 1000 0010 0001 0010 0000 1000 0010 000~. 0000" •~ represented in ~'rnzi ~Qde is ~md. The VFO region ±5, i~e first guard data region 23k; ,t~ie seo~nd guard data region 18, the gap region 13, the buffer region 2.~, and the mirror region 12 shown in Figure ZOA are the same as the corresponding ones dopsribed with rsferen~e to Figure 4K. The first guard data region 33, the VFO region 15, and the PS region 44 conWtitt4te a first dutmpy data region 15'.. In Figure 10K, thW tiurtib*t shown u~d4r eactt region represents the byte 1engt~z of the r0gi9ti~ This alpo applies to Figures 103, 31k, and 11~. In the first dt±mmy 4ate region 15', the VFO region 15 preoeding the PS region 44 has a specific ppttbrn for promptly and stably clocking the PLL of the reproduction signa3. pr~oes;ing circuit. For prompt and stable clocking of the PLL, it is better that the cods includes mor~ inversions (i.e., more "l~s" as represented in the NRZI code). For high-density recording, however, when the shortest bit length of a modulation code ±3 repeate4, both the applitude of the reproduction signal and the C/N are reduced, making it 4±fficult to obtain si;p4~ oleokiflg. Thetefore, the repetition of a pattern w±~h 4 oh;nn*l ~it9 which 4-s the second shortest bit length, i.*., "... 1000 1000 ... as represented in the N$~Z code is used. The length of the VFO region 15 is 35~ in order to ensure tha number of inversions end the clooktng time required for Stable clocking. the first Vuerd deta region 33 precedes the VFO 40 end the e*aQnd g~iawd data region 16 follows the ~ r~~ion 4~. A* deecrtb*d in Ezemple 4, when recording a~A pflpUrs pro repeated in a rewritabla optical disk, thp deg~g4ption •t tb0 start and end of the recording portiop o~ the opti-ept disk due to an increasing heat lued. The gt~ard date regions are provided to prevent this de~tsc4*tion from influencing the regions from the V~O region to the PA region. ~ach guard region should therefore be lor.~ enough to prevent this degradation. A reoQrc~±ng mediwn tends to be increasingly d~3grpded when same date is repeatedly recorded on the p~me ~obitiorh To avoid this trouble, the recording o~ the f±r&t data region ±7 is shifted by *~o~gatin~ ~I~4 phprtbn4r~g the f±±st and second guard ,data ~ons ~3 ~r~4 ~P p~~e4±ng and following the data ~~i0r~ ±7, ~sp~ot±ve1y. It should be understood however th&~ the total. of the lengths of the first and second guard d~t~ regions ~3 end 1~ is unchanged. From the reb4lt~ of experiments by the inventors of the present invention, it has been found preferable that the lengths o~ the first and second guard data regions 23 and 19 are (1~+k)B end (4~-k)B, respectively, and the shift amount is k 0 to 75. The total of th* lengths of the two guard data regions is fixed to 609. The repetition of the 4-channel-bit pattern '... 1000 1000 ...' used for the VFO region 15 is used as data to be recorded on the guard data regions, for example. '1'hu~, the first guard d&t~ region 23, the VFO re~4o~ ~.5, the ~~s~'no ~gion 44, the first date reg4on ~.7. the pos~.~ region 4P, and the second guard 4~ta r~giQn 1~ con~titute the information recording region where data i~ recorded with a data length of The gap region 13 is used to set the laser power, and has a length of 109 to secure the time required for laser power setting. The buffer region 19 has no data recorded thereon to secure a region (time width) for F~vPnti~ the ~nc~ ef t!~e recording data from overlapping tha ri~~ ~eot~r due to a v~iation of the r~tation of a d4-~k mo~o~ ~nd an eccsnt~-ioity o~ th~ disk. The buffer r~ion 39 has a lengt~i of ~ Th* mirror region 2.2 has a length of ~ to •sourp the t4rnp required for determining the offset of the eS~VO tracking. Referring to Figure 2.1K, - the sector 30 in the r~ad-~nly areas will be described~ The sector 30 includes a header regior~ 90, the second dummy data region 33, the second data region 37, and the third dummy data region 34. As describCd above, the data length of the *e~ond data region 37 is equal to that of the first dq*ta region 31, i.e., 24183. AS in the sector 10, a 13 ~ost~p~3e r~gton 47 (~'A), a ~econd ~ed region 85, and a tai~ib2-p req4.on OP (P~~) follow the second data region 37 in thip order. in this example, as in ~xa~ple 2, the second d~nitny date region ~3 is formed between the header re90 a~d 4hs se~on4 4ata region 37, while the third auiim~y 4~te ±~gion ~4 is foriped between the second data t~gion 37 and *he heed of the next sector. As in the 4.ti the rewri~ab3s ares, the second dummy data re0*on 33 inc~ludss p 35~ VFO region 84 and a 33 presyno r*gioz'~ 40 (PS) to secure the reliability at the reproduct4on ~4 data fro~fl the d~ts region 37. The second dummy 4e~a ~eg4.on 33 further io~ludes a 303 first pad region 82 arid a vostenbl-e region 83 aS Shown in Figure ilK. The third ~ummy data region 34 includes the postamble region 47, the second pad region 85, and the postamble region 86. The patterns and lengths of data to be recorded on th~ vie r~gion P4 aM the presyric region 46 are the ~.m* ~S tho~e* recorded on the VFO tegionAS and the presyno re~tQn 44 shown ira Figure ZOK. Au the data to be racotded c~ the bedoM sod thjrd dummy data regions 33 Md 34, d#ta series obtained by scrambling hexadecimal (FF1 4ata Using dJ4f*rent initial v~1u~s between adjacent sectors ~nd modulatin; the resi4ts with the 8/16 conversian codes as described in Example 4 are used. The scrambling is performed in the same manner used for the second data region 37. As the initial value, 4-bit data corresponding to the fifth to eighth bits from the least sIgnificant bit of the PID which will be described later is used. The initial Value correSponding to the 4-bit data is the same as that used for the second data region 37. The 8/16 convArsion coding starts from the ptat~ 4 4n the converpion tpble shown in Figure 13, for e)Eiinp4.* Thb thus-gsn~rb'~e4 data series is recorded on the ~ir~t pnd second$ pa4 r~gions 82 and 85. The first ppc~ region $2 corre~ponde to th* ~ap region 13 and the first guard data region 23 shown in figure 10K, while the second pad region 85 correSponds to the second guard data region 18 and the buffer region 19 shown in Figure iQA. In the rewritS~le area, the l~gths of the first and second g~.zard data regions 23 and 18 are varied. In the read-only areas, the lengths of the pad regions are mi~de t9 correspond to the average lengths of the corresponding first and second guard data regions 23 and 18. Thus, the lengths of ttt~ tirst end second pad regions 82 and. 05 are 3O~ a~d 8O~, respectively. The 13 postamble regions 83 and 86 follow the first and second pad regions 82 and 85, respectively, to terminate the modulation code. The header region~ in the rewritable area and the read~-onJ.y are4s will be described. As described in 2 with ze~ezence to ?igure 4A. the header region 14. iz~ the ~ewritable area is ~±v1.ded into the former hui4 lie (sectox~ identification data PIDi) and the latter ~lf lib (sector identification data PZ~2). The correspending pit rows 21a and Zib are diaplaced toward the opposite di~4otions fron~ the center line of the groove track 7 (th* guide g~oov~ ~) by 4bQut ~ quarter of the groov9 ~±tch. In thJp uxamplq, ~l.o, the header zegio~ P0 is fo~sd ir~ the same menn~. Fi~r~ 1O~ shows a data format of the header r~sp4.oti ~O ~ the s~cto~ ~.O in the reWritable area. As shown in Figure 103, the header region 80 is composed of fo~" q•t* of ~eo1or 4dentif±oation date (PID) denoted by ~ ~'ID~, ~ID3, ~n4 PD4. The PIDi a1'4 PI~2 constituting tl~~ 843 fozmer half is displaced outward, while the PIE~3 and PID4 constituting the 64B latter half is displaced inward, for example. In each sector identification data PID, 43 is allocated for a Pid region representing the sector address ±nformptlon, 33 for the sector number, and 13 for var±ous types of information of the sector such as the number of the Pid region. The addres~ information of the sector on the groove trac)c 7, from which the header region is diaplac~d With ~espact t~ the ce:~ter line, is rsoo~d~d on a ~id3 reqio~ 213 in the PZD3 and a Pid4 r.~ion 22.8 of thp P104 4-n the latter half. ThS address information of the sector on the land track 8 outward adjacent to the groove track 7 is recorded on a Pidi regior~ 2~3 of the PID1 and a Pid2 region 208 of the PID2 in the former half. Respective 2~ error detection codes are added to -~he Pid z~egior~s and r~de~ on !E~ regions 204, 209, 214, end 219 ThC data o~ the Pid ~'egions and the lED re~4-o~s are ~oduleted with the abqvs-desoribed 8/16 convp~si~n code. Thi~ ~iodulation ip initiated at the o~ •acih P4.4 regioti u5ing the conversion table shown 4.n Fig4re 13, for •#amp2.., Start±n~ from the state 1. aes~*ctive 1* ~ostambl* ~to~s 205, 22.0, 215, and 220 ~o~.l0w the Z5P regions to '~erRlin4~e the ~nodulation code. A?'~ regio~u 2Q2, ~07, 212, and 217 precede the cortesprn4~.rig P±~ re~ion~ and has an address mark mdioat4.n~ the ~tart of the Pid regions and realizing byte s~hro~4on~ ~s the edd~esa mark, • p.tterr~ ~.~hich dosS rzot ~ ±rx th~ 0/16 conversion code, e.g., a 33 (48 channel bit) long code. For example, a pattern "0001 0001 000~ 0000 0000 0100 0100 0100 0000 0000 0001 0001" ..ae rep~esente4 in the !~JRZI code can be used. This pattern includes two 1,4-channel-bit patterns longer than the longest bi~ length, i.e., 11,-channel-bit length, of the mo~iu1ation code. Therefore, the possibility of erroneouS detection of the address mark at the reproduction of normal data reduces. A V~O r5g±on is provided at the heed of each sector identification data PIP. The VFO region has data • ~psoi4o pattern to ~r~niptly and stably clock the PLtJ of th~ r~eproduotion !ignal pr~ceuSing circuit. For ~ain~le, t1~e repetition of the 4-channel-bit kattern "... 1000 1000 .." rna~' ~e used as in the VPO region described in Example 2. As described above, the former half PIDi and PID2 and ~he latter half PID3 and ~ID4 of the header region 80 are displaced toward the opposite directions from the canter line of the groove track. The first VFO regions ~01 and 22.2. wl~ich are the hepds of the former and the latter hel.ves of the header regiQn 80 need to give more than one chance for bit synchronization to ensure the bit synchronizatiQn. Accordingly, the first VFO re~ione 202. and 211 are made longer than the second VFO regions 206 and 2~.6 which are uSed only for re-synchro~iaation and therefore c~n ~e short. In this example, the 2.en~ths of the ~ V~0 ~eqions 201 and 224. are 363, wh$le the ~er~gth~ of t~ie second V~'0 regions 206 and 216 ~ ~. Thus, the P101, for example, includes the VFO region 201 (vFol), the AM reg~on ~02, the ~id region 203, the IEfl region 204, and th~ pQstamble region 205 in this order, and has a len~tb of 46B. Likewise, the P1D2 includes the VFO region 2P~ (VFO2), the AM region 207, the Pid regior~ 208, the I~D region 209, and the postamble region 2~.O 4-n this order, and has a Xen~th of 189. The P103 ~nd th~ PID4 of the latter half have the similar ooz-1figuration~ to the above. The heed~r zsgi-pn 90 in the r.~d-only areas will b~ d~sqribed with refersnc* to Figures ilk and 113. As described in ~ample 2 with reference to Figures 4K and 4M, the d~t~ prrAngement Qf the headpr region 31 in the reid-only aree~ is matched with the data arrangement of the header region 11 in the rewritable area, but the pit row on the header region 31 is lined along the center line of the tracl 9. The header region 90 in this example i~ fc.~rnied in the manner described in Example 2. That is, the data sequence and the length (bit length) of the header region 90 in the read-only areas are made equal to those of the header region 80 in the rewritable ~rea (Figure 10K). More specifically, as shown in F$g~rSs I.1~ ~M ±2.R, *h~ header region 90 with a length of 4.p c~npope4 of fo~ sector identification data ~ (?~i to PZfl4). The PIDi, fo~ example, includes a ~ir~t VP'O r~iot~ ~32. (VFOX), an AM region 232, a Pid region ~ an ~fl regio~i *34, and A postamble region 235 4n this order, •nd .has • length of 46B. Likewise, the P~D2 inc2.i~des a eecond VP~Q region 236 (VFO2), an AM region ~7, a Pid region Z38, an tED region 239, and a postarnble region 240 in this order, and has a length of 183. The PI~3 and the PID4 Of the latter half have the s~.rnilar configurations to the above. Thus, in this example, different data series can ~s fo~-mec~ on the dummy data regions 33 or 34 on adjacent tz~k* in the read-only areas. This oem be realized by ~oran1bli~ pred~t*rniine4 fixed data (e.g., FF) in the aaz1~e manner a~ tha'~ fbr data recorded on the second data ~eg4.on 37, using 4i~erent initial values between adjacent se~o~s. The re~u1tant ,cran~b1ed data is then modulatSd with the reoord4ng cods used for the date on th~ ~acor4 data r.g*on 47 and recorded on the pad regioi'~ ~ or ~. in 1hi5 ~ the servo tracking by the ph~~ err~v 4et.otic~n ~*~ho~ can be relatively stably oontz-oJ4ed 4.n ~hC read-o4y arees, A scrambling circuit and • reoo~4tng codiig ci~eu4.t used for generating data to be recorded on the second data region 37 can also be used for generating 4ata to b~ recorded .on the pad regionS ~2 aM 85. This sirnplifiWp the configuration of ~ Xeo0~diflg sign4 pzocessing circuit, and the circuit ~iS~ can be red~ic*d. ~n ~h4u exaip2.e, the po*ition of the first data rogi~ 2.7 was shifted by enlarging aM shortening the •nd $eooM gu~rd 4atA regions 23 and 18. Alternativ~.y, the ~ep region 2.3 an4 the butter region 19 may be en2.Ar~e4 and ~hcjz~ter~ed. The combination ~f the enlarging an4 sho2.~ten4-fl~ of these four regior~s may also be used. (~xampl~ 7) In ~iample 6~ exemplified data series on the seotot~S ~.O and 30 in the rewritab1,e area and the readon~' areas were described. As shown in Figures 10K and ~ the pre~yrW region 44 is formed 'following the VFO region ~ and preceding the first data region 2.7 in the - reWrit*~le area, while the presync region 46 is formed following the VFO region B4 and preceding the 5econd data region 37 in the read-only areas. In the conventional optical 'disk as shown in Figure ~3, for example, the data region 450 immediately follQWR the VFO region 403. The data region 450 is composed of a plurality of data blocks 405a, 405b, w~4h tM date •ynchroriQus 5e2~ieS 404a, 404b, ... precedi~ t~ cort'ss~o~~dirig data blool4ii. In such a co~v,htLOnPl 4~ta format, at the reproductiOn, at ~O± stAbl~ clocking of the PLL circuit by th% ~VF0 r0g4-ofl 403, the data synchronous series 404a is detected. By the detection of the data synchronous series 404a, the head of the data region 450 is identifled to repi'oducs the first data block 405a. The above conventional configuration has a drawbeck as follows. If the recording layer of the optical disk is dam~ed at tM portion of the first data ;yr~ohtonous eerie! 4O4~ which Specifies the start timing for the fir*t ~Sta klock 4055, for example, an error &zi-e~s in the ~ynchrono~s data to be read, failing to ~r4~ the start position of the firSt data block 405a. Moreover, when the start position of the first data block 405a is failed to be specified, not only the start pps±tion of the firpt data block 405a but also the block number of the subsequent data b~.oo1c 405b cannot be specified. Errors therefore arise over the entire data region 450 of the sector, and reading of tbr data becomes impossible. flowever, according to the data format in Example 6 deecri~ed ~bpve, which has the presync region fQ1,i.owin~ the VFO region, the start timing of the first data ~Xock can be detected with high reliability even if an error 4r4.ses it~ ~he first data synchronous series of the 4~ta region. In Example 7, tk~q presync region will be de-. ~ 14K showg ~. data format of one sector in 1ha. i~b~s area of an optical disk of this example. ~'i~*0 14R ehows a data format of one sector in the read only •r*~e of the opti~al disk of this example. Zn Z4 and 14w, the ~m. components as those in the p1~vi-Qu* 0xamp~.eg a~ denoted by the same reference numerals. ~erxing to Ti~Ur~ 14K, the sector 10 includes the h*ade~ region 80 (Sector 4.den~ification data PID), the ~iirr~ ~-~g4-on l~ (M), t~e gap region 13 (GAP), the firSt guard 4~te region 23 (GOl), the VFO region 15, the pre~yno ~-egio~ 44 (PpY), the fizst data region 17 (DATA), the pp~1ambte rCgion 45 (PA), the •econd guard data region 18 (0~2), •nd the buffez regio~i 19 (StYF). The first ds~e region ~.7 is d4.vi4ed into a plurality of data ~lpokg ~, ~b, .. with first data eynchronous series 4a, ~oedinq the rssp9otive data blocks. Th~ mirror regi~n 12 is a flat portion with no pit o~ groove formed thereon and used to obtain an offset of the tracking. The first and second guard data regions 23 and ~.B have predetermined data patterns for compensating a oy~le de~radation due to heat load. The first guard data region 23 is located at the head of the recor4ing data while the second guard data region 18 is 1ocate~ at the end of the recording data. The gap region 13 absorbs signal disturbance at the start and end of datp recording and sets ths recording laser power. The V~'C~ reg±~n 2.S includes a third data synchronous series a ~ra~e~t4~d cod~ of a single period is sequent*~i.Zy ~s~ox~d~d. ~ P~0UYflC region 44 includes a second ~at* s1rn~hror1ous seri~ for ~pecifying a start position o~ data reproduction, which w41 be descr [bed in this example in detail. Th~ pogtam~le region 45 terminates a modulation code and allows the reproduction signal processing to be shifted stably to a next sector. Referring to ~igure 143, in the read-only areas, the sector 30 include, the pad region 82 (DMY) and the postambla ragion 83 (PA), in place of the gap region 1~ end ~he ti~st gl4ard data region 23 in the rewritable Ar~a, a~d ~ p~d r~g4.o~ PS (DMY) and the postamble 00 (PA), ip ~.oe o~ thp second guard data repion ~.0 ~nd thA b4ft~r region ~.9 i~ the rewritabl. area, so as to ~ta~i1ise the tracking, The other portions of t~e SectOr 30 ~.s the same as those of the sector 10 shown in Figure 2.4K. The second dat~ synchronous series recorded on the presyno region 44 o~ the sector 10 in the rewritable area and the presyno region 46 of the sector 30 in the rsad-only areas will be described in detail. Hereinbelow, t~a presyno region 44 of the sector 10 will be described as an example. It should be understood that the sen~e is also wp~4ceble to the presyno region 46 of the spot0r ~o. As described above, the data format of this 0xar~ple inQludes the uAo~nd data synchronous series (the prs~no region 44 or 46) between t~~ first data synchrono~ ~er4.~s 4~ as the head of the data region and the th$r4 data ~ynohrono14* se4es (the V~0 region 15 or 84). ~ ,4pt*rrn4.r~d ~~at~e~n whiOh has high autocorrelation and does not a~ear in the othar data portions is used ~ ~ spoond data ~ynch~onQus seri~s So that a specific p4t4.~r~ o~n be dst!cted in the code sequence. At th* signal ~eproduot±on, the third data s~rnchronoua series (the VFO region 15) is first repro~1uoed to ~llow the P~4J oi~-cuit to be clocked stab±1±~ed by detecting the single-period repetition pattern. After the s~f~ioi~tv~ C bilizCtior~ of the clocking, the positio~ of t~a p~ooi~d datC Cynohronous series (the presync region 44) i~ detCc*ed, Fspr~ this detected position, the reed St~~ ~4tion o~ the first date synchronous me~ 4~ ~.o@at~d ~t the h*a4 of thA data region can be 'the Cynohrohi~~tior~ with the data of the data 1~E3~4.O~1 ~.7 i~ •atabli~h~ by use of the first data synchro~ci.~s sar±e~ 4. and piuS the data can be reproduced e~ a furthe~ precise tir~~g. I~ the ~e~e where the data re~ion 17 is divided intO a plurality of data blocks as shown in Figure 14K, a plurality of first data synchronous series 4a, 4b, Corresponding to the respective data blocks are formed on the data regi~n 17. This increases the redundancy, and ther~fo~e, in order to secure a sufficient recording region for user data, each data synchronous series should be ahort. On the contrary, since only one second data synchronous •erie~ (~SY 44) exists in one sector, the second data *ynchrono~s series can be made long. Thus, in thiS ex~mple, the position of the ~tiv*ly Lor~ ~coM q~e*a pynchronous series (PSY 44) b~ d~teot~d withc~ut *42.. ~o~n the detected position of th~ second date *ynoI~ronoU5 s.z4A. (PSY 44), the read start position o~ the fir5t data synchronous series 4a located at the he*d of the data region 2.7 can be identified. 'This allows the first data synchronous series 4a to.be shortened without reducing stable detection thereef. An exemplified code pattern of the second data syr~chrOnou5 series will be described. Zr~ this example, ai~ the recording code, the 8/16 code is used, which ocnv~~-ts S bits of 4~te into ~-6 channel bits of the ddng co4~ hewing a bit length of 3 channel bits at 14.nizhuiTl to 11 chAnnel bits at maximuni. The interval of on~ ohsnn~l ~±t iv re~ireSented by T. The data is reprevented in the N~ZZ QQd* where the signal level i. inverted at bit "1" while it i~ not inverted at bit "0". The second date syno~ronouA sezias needs to satisfy the limit of the mark/Space lengthy of the recording code. A~ord~.ngly, thO shortest recording bit length is "100". In cr2~r to ensure stable reproduction, the third data synchronouS series (VFO 15) needs to have a period longer then the shortest recording bit and include much ~dge in*ormstion (level inversion) which ensures the o~1~ir~ of the ~LL. Zn this ex~fl~ple, therefore, a code ~*ri*s ~o~ipo~e4 of repetition of "1000" 4.s used as the tfrLz4 ~*ta synchronous series to be recorded on the VFO rapien l~, T~s mark/space lengths of the VFO region 15 are *h~re*ore 4T. S±noe the Second 4ata syr~chronous series of the p;QYT~O re~ior~ 44 is 4et~oted ~fter the clock synchroni~a~4.o*~ by thC third 4a1~ synchrcnous series of the VFO region 15 aa ~eso4bed above, using the code capable of ,ynoh~oni~4.ng every 4T further •nsures the synchronous ~pro0i.i~tCon. Con~equently, it is effective to use a combinAtion of a 4-channel-bit patters as the second data ~ynchr7c~nC~i~ ~rip~. in tne case where the average of 'the mark/Space langths of the second data synch~onou5 uurss ~-s ciose to th~ period Qf the repetition pat~ern of the third data nch~or~ous esriep of the V$0 region (hereihafter, such ~ pattern i~ fer~?ec1 t0 0 t1~s VFO pattern), symbols "1" present~d in the N~I cods are boated at similar posit±Q~C bAtwaen th~ ti~0 4ata syn~h~o~ous series. This mnorq~eee the p~o~abi~4ty of z4etakenly detecting the VFO pa~tte~n for the 0eoond data pynchro~ous series. In this example, th~refo~e, t~as inter-code distance between the second data sy~chrono4s series and the VPO pattern is msde l~ge. fl~weVer, *n order to make the average of the m5~J~/spsoe length3 of th~ second data synchronous series gn~lJ,~r than the pe~±o4 4T o~ the VFO pattern, a pattern 3V which is the mh~test recording bit length needs to be included frequently. This reduces the stability at the data reproduction. In prder to overcome this problem, the average of the ~nark/space lengths of the second data synchronous series is made longer than the period 4T of the VEC pattern. The s~cond da~a synchronous series in this example is 4 ~it long, ~nd domposed of a combination of p~4r~lity o~ Oode ~b01S including a code symbol having a single level inversion, i.e., "0001", '~O010", "0100", end ~'1C00'~ ~nd p dodA p~bol h~ving no level inversion, i~4, "0000". A turt~er specific example of the code series constituting the second data synchronous series will be described. In this ex~~iple, the above-described 8/16 oonver~icn code is used. As will bC described later, since a 2-byte code is u~*d as the first data synchronous ~e~ies, three bytes are used for the second data synchro nous sezies. When converted with the B/16 conversion code, t~ s~cond data Cynohronous eerie, has a length of 4~ ~it long as the ~eoordin~ channel bits. That is, in t.4~rh~s of the •~ove comb4n~tiQn of 4.~it long code s~'m~,01S, it hat a J~eng'th o~ 12 symbols. Hereinbelow, four ~peci±ic examples of t~A code ~eries will be described. (1) P4ttern 1 "0100 0010 0100 0010 0010 0010 0100 0100 1000 0010 0100 1000" Pptte:n 1 is the same as the pe~tern standardized in ISO/IEC 10089 and composed of three types of symbols, "0100", "0010", "1000". (~) Patt~ri-~ 2 "1000 OlpO 0100 1000 0010 0001 0000 1000 0010 0100 0100 oclol" Pa~ern 2 is composed ot five types of symbols, "0100", "0010", "1000", "0001", "0000". (3) Pattern 3 "U000 0100 0100 1000 0010 0001 0010 0000 1000 0010 0001 0001" ?attern 3 is coniposed of the sai~e five types of as Pattern 2. (4) Patte~-n 4 "OQOO 0~00 0100 1,000 O0~.0 0001 0010 0000 1000 0010 0001. 0000" Pstt~rn 4 is also composed of the same five types ot ~ymbo1s as P*ttern 2. This unique' pattern was first discovered by the Inventors ~f the present invention, and' exhikits resistance to errors and excellent detection results a~ the data se~iee of the PSY region 44 interposed between the VFO region 15 and the data region 17. Figure 15 showi the cotnpariuon of the character4-sties o~ the above p~tternu I to 4 with respect to the avera~ ~f thA rn~r1~/~~oe ler~gthu, the maximum and JllThiml4zn of the maz'k/epaoe lengths, the number of symbols oon$titUtIn~ the pettern, and the absolute value of the 4ig±tal stimming value (~SV). As ip abaerve~ tronr t±gurC 15, the maximum and o~ thq ~ark/s~ce 1~ngths q~nerated in all ~ernC i~ 3? end El', r *otively, s~-bi*fying the limit vslue~ fo:r 'the no4ulation wi~h the 5/3.6 modulation code ~ ~ongth 11, rntz4nitun l5ngt~ 3?). The averages at ~ i~ark/apaoe lengths of pattern 1 to 4 a~e prefez~abt~ dif~erCnt from the repetition ~4p4 4'~ of the th4-rd data synchronous series as de~oribed ~boVe. AC is observed from Figure 15, the ~vera~ ~f th* mazk/space lengths of pattern 1 is 3.7T which i~ relatively close to 4?. ThiB is because all of ths three types of symbols constituting the code series of pattern 1 include "1" among the four bits. Since pattern I does not include the symbol "0000", it is d4fi-cult to obtain the average of the mark/space lengths la:rger than 4T. On the contrary, since the code series of patterh~ 2 to 4 •re ob~t~possd Qf fivs types of symbols J4wlv44.'n~ the eymbo2. "0000", the average of the ~/apads lengths can be made longer than 4T, Th* digital summing value (DHV) can be used as an in4ibpto± representing th~ cMtaoteriutics of the recording codA. The DSV is obta~.ned ~y converting "1" and "0" as represented ir~ the ?jRZI code into "1" and "-1", respectively, and summing all the bits of the code. When the DSV is zero, the DC ~ompopent included in the recording code is zpro, aM thus the ~C component in the reproduction sigr~al 4oaB not vary. This makes it possible to stably convert the reproduction signal into a binary yalue. As is observed from Figure 15, the DSV is 0 for pattern 4. 'the dCteQti~n of the second data synchronous series (t~ie P$Y reg4.on) will be described. Figure l~ shows • ~SY deteo~ion circuit 200 for detecting th~ second data synchron~us series. Referring ta ~'igur~ 4~, th~ PSY detection cizcuit 200 inoludes a ~i shift ~e~ister 92., • second register 92, a match nupibC~ oo~nter 93, a thr~~old circuit 94, a synchronous ~etection ~errni0ion ~jenqratirag oi4cuit 95, and an AIJD ~i:~cuit 90. ~ 14dS e~~1ip1.s, em described above, the ~eo~n4 d&4a Ryn~hrono~m se4ss i~ as*u~ued to have 48 bits, $.e.. L~ 4-~4.t sy~olp S~ to S~ The pattern of t~, w~opnd d~t~ ayichronous se~ies is therefore ~resent~d by a symbol sequence ~0, ~ ~2' ~ S~. First, the pattern of th8 second data synchronous series (symbol sequence) B0, S~, 8~, ... ~L1 is held in the second register 92. Then, a reproduction signal for the PSY d~ection is input into the first sihft register 91 and OQmpa~e4 with the reproduct~.on •i~al every four bits, i.e., Overy symbol. The number of matched Symbols is co~.int0d by the mAtch nufl~er counter 93, and the count v44~ is ou~p~t to the t~rephold circuit 94. The thresh014 o ctd~ 94 ha~ a p~set thr~shold for determining whether or n~t the second data uynohronous manes has osen det~oted. When the count value output from the rnv'tch number cpunter 93 exceeds the threshold, a detectj.on si~n4 is output from the threshold circuit 94. For s.~campJ.e, assuming that the threshold is preset at 8, the threShold circuit 94 outputs a detection signal when the input reproduction signal and the second synchronous series •~ to ~ match by eight symbols or more. As long as no error arises in the reproduction signal, all of the 12 symbols should match with the signal value of the first shift register 91 when the second data synchronous ~4i~4.~5 i~ *~ctly detected by shifting each bit of the f~-t~ Ch4t ~~ister 92. on~ by one. The synchronous d*o~s4s~ p A ior~ ~n~~~ting ci~cuit 95 outputs a gate 54.gnAl in~i~ting the ti~ie period during which the second 4#~C •y~~h~onpus perie~ ShOuld be dAtected. When the threshold circuit 94 ~~tect~ the second data synchronous s~nies during this detecjion time period, the detection signal for the second data synchronous series is output from the AND c~.rou±t 96 to a system control circuit (not shown). In this example, the pattern match was performed every 4-bit symbol. The pattern mAtch may also be performed for another number of bits, e.g., every bit. A sp*cif 4-c e~ce~ple o~ the data format shown in I'i~re i4i~ with e specific Qode pattern allocated for each region gill be d~so~ibed. This ppecific example is aL5o applicable to the data format shown inFigure 14D. ~igure 17 shows an exagiple of part of the data format :cv~p ~ V~C' ~e~c~n 15 to the first data block Ba. Ref~rrin~ to Figure 17, the VFO region 15 has at ±eagt 64 bits of ~ re t±~c~ pattern of "1000" as the third data synchronous series. The first data synchronous series 4a of the data region 17 following the second d~te ~ynch~-onous series of -the PSY region 44 has a 32-bit pattern 4-1 of "OOO1001QQ1,000l00 OOOOOOOOOOOOOloool" or a 3~-b~ pat~ern 4a-2 of "OOOlOOtOOOOOoloo OOOOOOOQQOO1,000l". In Figure 17, 16 bits of the head portion o~ the data block 5~ following the first data syno~ronous ~eriee 4. is shown. ~e#ir~•low, the ~iattern match obtained in the PSY c~eteotion will bp deso~ihed usis~~g patterns 1 and 4 of th~ spc0nd date ,ynchrorloul series described abcve. ~ ah~. ~ in Figure 2.7, the detection of the we~ond data Cvnchronous senS, is pereormned using a 48 ~,it q±de '.ete~ticn windo~' ~7. A reference position is de~*n*4 as th* ~os4.tion Where the match of all of the 12 ~ ~ould ~e obt~ined es long ap no error arises. At th# 4*tection, the detection win4ow 97 i. shifted within th~ r4nge ~f -64 bits leftward to +48 bits ri~ht.~ard from the reference position. Every four bits of the input signal are compared "~~th each symbol of the se'~ond data synchronous series as described above, to obtain the number of p~ttern matches. The results are sh3wn in Figu~es 19K and 19E, which are graphs generally referred to as autocorrelation function diagrams. The thrpsho$ of th~ number of the pattern matches is preset at B, and th~ position where eight symbols cr more have mnt~t0h*d iu 4qt*r~iioe4 as a 4etection position for the •SOOi$ d*t& •yhchronotis asriem. Zn order to consider the influence of the first da~u Synchronous series 4a and the data block St at the praqtic4 detection of the second data synchronous series, the results shown in Figures 19K and lOb have 1~een determined in the following manner. One of the patterns 4a-l and 4a-2 of the first data synchronous series is selected so that the selected erie gives the larger number of pattern matches at each time (i.e., the one which nine adversely influences the detection of the q*oOhd data synchronous ~r±es is selected). When the 4,*eotion window 91 *hifts rightw~r4 from the reference p0SittQp ~y about 40 btte or more, the data block 5. #o~.low4vag the t$rat d~ta bypchronous series 4a is includ.4 i~ the rtng* at the detection window 97 as shown in flgure 4 Zn thiS cap~, the pattern of the data biocic St (first 16 bits) greatly influences the detection of the second data *yn0hrcncus series. To prepare for the worst case, a p4ttern of the data block 5a (16 bits) where th! number of pett*rn matches is largest is used in this flample. As a result, ~s will, be observed from Figures lOX and 19~, when the dpteotion window 97 is shifted leftward ft~)il the ref qtaace pqu±tiori (i.e. the position of bit shift 0), the ma~*mwn ~unWer of pattern matches is 5 for pstt.rr~ 1, while ±t is 4 for pattern 4. Also, when the det~ction window 97 is shifted rightward from the referqnc~ position within thS range of 40 bits from the reference pc~ition, t~ie m~ximum number of pattern matches is 6 for pattern 1., while it i~ 4 for pattern 4. The number of pattern matohew when the detection window 97 is shifted from the reference position is desirably as small as possible so as to pre~re~t the second data synchronous s~riss Crr~ b~i~ig $staken~.y detected. Accordingly, with w~p~ct to the bit ~hift, the autooorz~elat±on characteri~tics ~f th~ s~q~o~d 4e*s sy~ohronous series is batter when paj~rn 4 is used. The autoo~rrslet4.on Qf eagh pattern of the second d~t~ 5ynchrot~ous sCries when edge shift or slioe level v~tion o~ours hp! ~ee~ •*aznined. flerea.n, 1.-bit edge •~t r~er~ to 4 one-bt~ shift of 4 reproduction signal whe.~e, ~0r ei~4~m~14, th~ r~production signal which should be "0Q~.Q0" 4.~ oh*n~ed to "01.000" or "00010". Figures iSA ~o ~ *r~ j#s~h4 sbowit~ the •Uoe level variation. A ~lipq level 4.e uu~4 ~s a measure to? digitizing a reprooii~ ~Ljn~i. into a binary v~iue. When the value of a !41~1.~4 ~p O~UOt4Qn *~nal is larger than the slice levpl, 4.t is set at "1". The result of the digitized kinaxy velue iui represented in the NRZZ code. The slice l~ve1 is normally set at the center of the amplitude of the reproduction signal as shown in Figure iBA. However, the slice level may riee or fall, as shown in Figures 185 and lOC, varying the measure for digit±~ing into a binary value. As a result, th~ signal series which should be r~produc~d as "10001000" in the NRZI code as shown in Figure iSA is reproduced as "10010000" when the slice level. r4.s~s as •how~ in F'igure 183 or reproduced as "l00001'00" when t~e g~.io~ level falls am shown in FigLr~ t~C. F~~s 20K and ~0B show the rpsults of the worst values 0± pattern matches when 1-bit edge shift occurs at ary one to three positions within the range of the detection window 97 for' detecting the second data synchronous series. Figue ~0C shows the results of the pattern meitches obtained when, due to the rise of slice level, the pattern of the VFO region 15 changes from original "lOQOlOQOf! t~ shifted "3.00~.O0O0" end the mecorid data syflohronove series o~ th~ P~Y region 44 is also subjected to p •$~iI-Cr ohpri~e. ~i~ewise, Figi.~e 20D shows the ~ o~ t~ ~ ~atche* obtained when the slice 4~v~l f~4e~ A! shown in Fi~urpS 20K Snd 20W, as the number of edge ehifta 4.ncrease~ by one, the number of pattern matches in~rea~e~ by or~e at almost all the bit positions ~ whoip. As a result, as is observed from Figure 20K, ~ the c~Ii~ of pattern 1, when the edge shift occurs at two positions, the number of pattern ~iatches becomes B evsp a positions outside the reference position of the detection window V. This may cause miss-detection. Zn the case ~f pattern 4, however, the number of pattern tj~atohes *' 6 at maximum at positions outside the referen~p position of tI~e detection window 97 even when the ed~ shi*t occU±'a St tw0 positionS. The probability of ms-~tect~.on is therefore small. ~,S o~berv84 ~rom Figure ROC, in the case of pR~t~~n ~ when the detection window 97 is shifted le~*wSr4 (toward tM n~g~tive bit shift amount) from the ~e~*rer1c~ ~osit4.on by 04 j~o 48 bits for detection, i.e., wh~$ pattern match ~ ~er~ormed with th~ Signal series of thS VP'b r~.oh ~.5 wit~ the s1.ic~ level variation, there •xista a position where the number of pattern matches abruptly incre~*~s to as high as 8. This ~~iill be mistakenly deteot~4 •! th~ ~econ4 ~ata synchronous series. Zn 'E-~ ceaW of pptt~mn 4, however, the number of pattern ~atohSs i~ $ at znaz~i~in~zh at positions leftward the reference position Qf the 4etection window 97 even when the shoe Level V&rte~. '~e poseibili'ty of miss-detection ii therefore small. Th~.$, pabte~n ~ is pre~er&ble as the second nt0nO~J~ eerie* ~o be tpc~or~ed on the PYS region bqcauae it h~ goqr~ ~roperti.u as the recording code and h~s a ~~iia11~t pos4bil~~ O~ niiss-4~tection of a synchrono~.*s s.tgha~ due to e~ •4ge shift or a variation of the ~hiQp lsVeL. 't~u~p, according to the optical disk of the p~S~tit invention, the sector 4-dentification data of the first hsad.er ~egLon je reproduced when either of the groove track and the land track is traced. This eliminates thp necessity of providing an exclusive header region for each of th. groove trac)c and the land track. Regarding the prefozmat of t~ie rewritable area, the first header region can be formed on the optical disk easily with high precision by wobbling a light beam for cutting and forming guide grooves (groove tracks) outward •M inward from th~ cente J.ine of the groove tracks. Th~.s ~l.tndnateS the n~eoe~siW of providing an additional •~oiusi~e Li~ht source fop forz~±ng thC header region in the rewrita~tt~ aria. Thi4e. acc0rdifl~ to the optical disk of the present invention, the prefor~uat of the rewritable area can be easily formed w~.th high precision using one light so4rca for cutting. This makes it possible to form the preformat using a conventional cutting machine when both the rewritakle area sn4 the read-only area are formed on 0~e optical disk. *~di~ to t~e p*0~ent invention, the sector 4.ength, tk~e l*ngth of j~e ~adsr region, end the length of the dsta region ir~ the re~4"only are, are made equal to those 4~ t~ rei,~4t*~le a~'i5a. AS a result, the data fQrn~t o~ the ~S~d-onl~' area ~1atQhas the data format of the rewritable area. 'Phi. na)CBS it poSsible to unify the pector managements of the re,d.~otgy area and the rewritaW~-e area so as t~ unify the signal processing such em se~toZ retrieval,. According to the p~esent invention, there are provii~ed ~he dummy data regions preceding arid following ~he info~ati~r~ d4ta region in the read-only area. With this ~~ngrnt~nt, the ~c~or len0th, the length of the h.~d~r r~icn, •n4 the length o~ dat4 to be recorded on the spctor ~.n the read-pnly area can be made substantial~y equal to tho~e in the r*writable area. This makes it possible i~ i~nif~ the eeoto~ managet~ante of the read-only pres ~ the ~ew~i.tabls ares so a~ to ~.znify the signal ~r0C~PPing e4~h as ~eo*or retrieval. Aecor4i~g to the pptioa~. disk of the present ve~tiOn, SCpRrStp rAproduction signal processing ~ the rewr±table area and the read-only area ez* ~oi neceePaz'y but one reproduction signal processing ;i~4-t cSn be ~hpre4 When thp ~ewritsb3.e area and the ad.onJ~.? ~r~a are ~orz~d on one optical disk. This it ~ t~ reduce the c~.rcuit -size of an citi~el disk recording/reproducing apparatus. Thus, a rd-~nI,~ ~Q~44.ng tb th~ pzqSent invei~tiQri, the tracking ~r~r sign~. ~ be staNy dete~ta4 even when the phase error tSdj~icn $~Stk~od 4.; amp~ eyed f'r servo tracking, ~ll0Win~ i~tiVSLy Pt~l* servo tracking. Also, by usi4i~ di~C~er~t 4ebs pync~ronous series for the second di~h~ii~' d~ta regiane e~ 44~cent tracks, the servo tracking ~* ~t~b4L~d e~rid t~ p~art of the information data re~i~ can ~p det~~t~d w4..thqut fail. According to t~e present invention, a sector in the read~orily area left with no data recorded thereon is fil1~d with dummy data. With this filling, the r~writable area can a~Aays start from the head of a track, aM th~.~s effective sector management is realized. According to the present invention, the second data s?nchronous sane! '4th high autocorrelation is used for the presyn~ re~ipri. This makes it possible to detect thS p~nO re9~.or~ with ~-i4.ph ~'siiabi24.t~. As a result, ~ ~Q~4.ti0n Pf the ptsr~ oi th~ data tegion following th~ e*~n~ ~giQn ost~ ~ preoiNe~.y specified. This 4~1~ i~ p~~ibl9 to ~tab~' reproduce recorded data. The averag~ o~ the mark/space lengths of the ~e~nd da~a ~y~chror~o~.is series is made longer than that of the V~0 r~gion. This makes it difficult for the second date svnohronouq Renew to match the pattern of the data synchronou~ series used for the 'flO region. This ±5 eQectivS SVCtI in the case where no error arises in th~ reproduoti-ofl •±pn~l or in the case where an edge a4tt 0QPI4r0 or ½~ p14-os level varie'a. Accordingly, such a eeoon4 data •ynohrpnoua series used for the p;tflflc rWgi~n is repistive to errors and provides excellent det~;t$on results. By sbtting thq digital summing value of the second data synchronous series at substantially zero, the DC component does not Vary, and thus the stability of the reproduction signal is not degraded due to the addition ot the second data synobronoub series. mhu secor4 data synchronous series, which satisties thq 24.mit vali~e under the modulation code rule, prevent! troublps e4ch as waveform interference due to th# t*Qbtding mAnes re~cr4~4 on the optical disk being tao swafl 4nd troubies uuoh as unstable clock synchronit*t±Ot' due to the inversion interval of the signal beP4 ~oe long ~qeult±~g $rtm th~ recording mark being too larpe. Venous cth*r rno~4ftcatiofl* will be apparent to aM Q$T~ N ~dilV ~Ad0 ~y thope pkS4led in the art withbU~ dep~wt4.ng t;o~ thS scope and spirit of this invpntion. Aooor4ingly, it is not inten4ed that the svopA Of t~* ot,&tns ~ppehde4 hereto be limited to the desc~4ptioi as e~ forth herein, but rather that the claims be broadl-y construed. We claim: 1. An optical disk having a rewritable first recording area and a read-only second recording area, wherein the first recording area comprises first tracks composed of groove tracks consisting . of grooves and land tracks consisting of spaces between adjacent grooves, the groove tracks and the land tracks being formed on an optical disk substrate alternately in a spiral or concentric shape, each of the first tracks being divided into a plurality of first sectors, each of the first sectors comprises a first header region having identification data for identifying the first sector and a first data region for recording user data by forming recording marks by changing optical characteristics of a recording layer, the second recording area comprises second tracks formed with physical bit rows arranged on the optical disk substrate in a spiral or concentric shape, each of the second tracks being divided into a plurality of second sectors, each of the second sectors comprises a second header region having identification data for identifying the second sector and a second data region having read-only data recorded as the bit rows, characterized in that the first header region comprises a physical first pit row, each pit of the first pit row having a width in a radial direction of the optical disk substantially equal to a width of the groove track and being wobbled outward or inward from a center line of the groove track by about a quarter of a pitch of the groove track, and the second header region comprises a physical second pit row, each pit of the second pit row having a width in the radial direction of the optical disk smaller than the width of the groove track and being formed substantially along the center line of the second track. 2. An optical disk as claimed in claim 1, wherein a data sequence of the first header region and a data sequence of he second header region are modulated with a same modulation code, and a data sequence of the first data region and a data sequence of the second data region are modulated with a same modulation code. An optical disk as claimed in claim 1, Wherein the identification data of the first header region and the identification data of the second header region have data formats with a same data sequence and a same data capacity, and the first data region and the second data region have data formats with a same data sequence and a same data capacity. 4. An optical disk as claimed in claim 3, wherein a data bit interval between the first header region and the first data region in the first recording area substantially equal to a data bit interval between the second header region and the second data region in the second recording area. 5. An optical disk as claimed in claim 3, wherein, in the first recording area, each of the first sectors consists a mirror mark region, a gap region, and a first dummy data region which are formed between the first header region and the first data region and a guard data region and a buffer region which are formed between the first data region and a first header region of a next first sector, and in the second recording area, each of the second sectors consists a second dummy data region formed between the second header region and the second data region and a third dummy data region formed between the second data region and a second header region of a next second sector. 6. An optical disk as claimed in claim 5, wherein each of the first dummy data region, the second dummy data region, and the third dummy data region have a specific sequence pattern of a modulation code used for modulation of data to be receded. 7. An optical disk as claimed in claim 1, wherein the data series of the first and second recording areas are modulated with a same modulation code, the first and second sectors have a same data capacity, the first and second header regions have a same data sequence and the first and second data regions have a same data sequence and a same data capacity. 8. An optical disk as claimed in claim 7, wherein each of the first sectors consists a first dummy data region formed between the first header region and the first data region, each of the second sectors consists a second dummy data region formed between the second header region and the second data region and a third dummy data region formed between the second data region and a second header region of a next second sector, and each of the second and third dummy data regions consists, in at least a portion thereof, data of a data series different from a data series of a corresponding dummy data region on an inward or outward adjacent track on the optical disk substrate. 9. An optical disk as claimed in claim 8, wherein each of the second and third dummy data regions consists, in at least a portion thereof, a random data series with substantially no correlation with a data series provided on a corresponding dummy data region on an adjacent track. 10. An optical disk as claimed in claim 9, wherein the random data series is a data series generated by an M-series sequence. 11. An optical disk as claimed in claim 8, wherein each of the second and third dummy data regions consists, in at least a portion thereof, a random data series with substantially no correlation with a data series formed on a corresponding dummy data region on an adjacent track and a specific sequence pattern comprised in a modulation code provided following the random data series. 12. An optical disk as claimed in claim 8, wherein each of the second and third dummy data regions consists, in at least a portion thereof, a data synchronous series for specifying a start timing position of the second data region. 13. An optical disk as claimed in claim 12, wherein the data synchronous series comprised in the second and third dummy data regions are provided so that a pattern of the data synchronous series is switched every track among a plurality of different data synchronous patterns. 14. An optical disk as claimed in claim 8, wherein each of the second and third dummy data regions has in at least a portion thereof a pattern generated by scrambling a predetermined data based on address information in the sector identification data and by modulating the scrambled data with the modulation code. 15. An optical disk as claimed in claim 7, wherein one error correction block consists a predetermined number k (k is an integer) of the first or second sectors, and data is recorded on the number of sectors equal to a multiple of k, dummy data being recorded on remaining sectors of less than k.. 16. An optical disk as claimed in claim 1, wherein at least one of the first and second data regions comprises: a first data synchronous series provided at a head of the data region for specifying a start timing position of the data region; a second data synchronous series preceding the first data synchronous series for specifying a start timing position of the data region; and a third data synchronous series preceding the second data synchronous series and having a specific repetition sequence pattern of a modulation code in the data region. 17. An optical disk as claimed in claim 16, wherein the data region is divided into a plurality of data blocks, the first data synchronous series is provided at a head of each of the data blocks, and the second data synchronous series precedes the first data synchronous series provided at a head of a first one of the plurality of data blocks. 18. An optical disc as claimed in claim 16, wherein a digital summing value which is obtained by converting "1" and "0" in the second data synchronous series into "1" and "-1", respectively, and by summing all values is substantially zero. 19. An optical disk as claimed in claim 16, wherein the second data synchronous series satisfies a maximum length and a minimum length as limit values under a modulation code rule of a mark length ("1" or "0" level) and a space length ("0" or "1" level) of the data region. 20. An optical disc as claimed in claim 16, wherein an average of he mark length and the space length of the second data synchronous series is larger than the mark length and the space length of the third data synchronous series. 21. An optical disk as claimed in claim 16, wherein the second data synchronous series is a data series composed of a combination of a plurality of any of 4-bit code symbols, "0100", "0010" "1000", "0000". 22. An optical disk as claimed in claim 16, wherein the second data synchronous series is a data series comprising a code series, "0000 0100 0100 1000 0010 0001 0010 0000 1000 00'10 0001 0000". 23. An optical disk substantially as herein described with reference to the foregoing description and the accompanying drawings.

Documents:

913-del-1997-abstract.pdf

913-del-1997-assignment.pdf

913-del-1997-claims.pdf

913-del-1997-correspondence-others.pdf

913-del-1997-correspondence-po.pdf

913-del-1997-description (complete).pdf

913-del-1997-drawings.pdf

913-del-1997-form-1.pdf

913-del-1997-form-19.pdf

913-del-1997-form-2.pdf

913-del-1997-form-4.pdf

913-del-1997-form-6.pdf

913-del-1997-gpa.pdf

913-del-1997-petition-137.pdf

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