Title of Invention

"WIRELESS PHOTOSENSING SYSTEM"

Abstract

A wireless photosensor used for detecting status/presence of any moving/stationary object and accordingly generate output signals for controlling the different motors/valve actuators and counting the events etc. The wireless photosensor is basically comprised of a sensing and transmitting unit and a receiving and processing unit and utilizes phototransistor means to detect status/presence of any moving/stationery object and generate corresponding photosensor signals to actuate relay means for controlling different motors/valves and counting the events. The system avoids the use of huge multi-core wire for transmission of photosensor signal from sensing unit to signal processing unit (output unit) which can be located at different places i,e, near process site and control room respectively. The system would not require the expensive conduit and cable laying and therefore would be simple and cost effective and would be immune to external disturbances such as electromagnetic noise and the like.

Full Text

The present invention relates to photosensors used for detecting status/presence of any moving/stationary object and accordingly generate output signals for controlling the different motors/valve actuators and counter events. In particular, the present invention is specifically directed to wireless photosensor to achieve like purposes discussed above. The conventional photosensors are usually comprised of two units say sensing and processing unit. Normally sensing unit are kept near to process/object which is to be sensed while processing unit are kept in the control room/electrical machine hall. These units are connected by long cable, the length sometimes extended to a k.m. and it passes through difficult route. Time to time there have been improvement in quality of such known cable operated photosensors and its size is also reduced. But these sensors still suffer due to high cost involved in multi core cable and conduit which are laid in between its sensing unit and processing & power supply unit. In rolling mill, the laid conduits and cable frequently get damaged though maximum efforts are put to protect them against falling of hot rolled metal/cobble. It is thus the basic object of the present invention to provide for a wireless photosensor avoiding the use of huge multi-core wire for transmission of photosensor signal from sensing unit to signal processing unit (output unit) which can be located at different places i.e. near process site and control room respectively. Another object of the present invention is to provide a wireless photosensor which would not require the expensive conduit and cable laying and therefore would be simple and cost effective, Yet further object of the present invention is directed to provide for a wireless photosensor which would be immune to external disturbances such as external noise and the like. Yet further object of the present invention is to provide a wireless photo sensing system which would be adapted to function under atmospheric temperatures of upto 70°C without the use for any cooling jackets and the like. SUMMARY OF THE INVENTION Thus according to the present invention there is provided a wireless photosensing system comprising a sensing and transmitting unit and a receiving and processing unit; said sensing and transmitting unit comprising a phototransistor means adapted to generate electrons on falling of light on its base to provide for photo-current flow from collector to emmiter ; means for modulating the variation in collector signal (according to presence/absence of light on the base of photosensor) in a frequency modulated circuit and radiating through antenna coil; said receiving and processing unit comprising means for receiving the photosensor signal as induced voltage, on antenna coil demodulating carrier waves means having an operating frequency same as that of the transmitting section, means for latching the state for transition low to high photosensor signal and vice-versa and means to actuate relevant drive means based on said photosensor signal. The above disclosed system of the invention thus provides for an easy to obtain, simple and cost-effective wireless photo sensing system. In particular, the working of the system of the invention is discussed hereunder. On the falling of light on the base of phototransistor, the electrons are generated and photo-current flows from collector to emitter. The photo current is of low value which needs amplification. Therefore two phototransistors are connected during manufacturing itself and put into darlington pair i.e. parallel connection. The variation in collector signal related to presence/absence of light on the base of photo transistor, is transmitted through frequency modulated circuit. The voltage at output of amplifier works as supply voltage of a first tank circuit of hartley oscillator. Low amplitude oscillatory-voltage is amplified by means or transistors and energy is again pumped back to said first tank circuit through coil which works as antenna and radiates the photosensor signal. At receiving end, the signal is induced voltage at antenna coil. After passing through amplifier means and inverter a second tank circuit is used and adapted to work as demodulating carrier whose operating frequency is exactly same as the tank circuit of transmitting section. The demodulated signal further amplified by transistor means. Further transistor means are used and adapted to work for latching the state for transition low to high photosensor signal and vice versa. A transistor means is used for amplifying the low value latch signal and drive the relay. The potential free contact of relay is used for driving different mechanism like roll table motors, pump motors, solenoids etc. The details of the system of the invention are discussed hereunder in greater detail with reference to non-limiting exemplary illustrations of an embodiment of the system in relation to the accompanying figures wherein : Fig. 1 is a schematic illustration of the sensing/transmitting unit; Fig. 2 is a schematic illustration of the receiving/processing unit. Reference is first invited to figure 1 which shows the sensing/transmitting unit. In particular figure 1 illustrates the basic elements of the sensing unit which is the photo transistor. On the falling of light on the base of pnototransistor, the electrons are generated from base to emitter junction and same amplified by another transistor work in a darlington pair configuration. The signal which is converted from light signal is taken at emitter follower stage. The signal is further amplified by operational amplifier. The amplified signal so obtained is now processed through comparator circuit where signal voltage due to unwanted light get filtered out by adjusting the threshold voltage through variable resistance VR -1. On the arrival of luminous object the signal exceeds the threshold voltage and produced output, can be seen by LED. Fig. 1 further illustrates the transmitting section used in the system of the invention. The output of photosensor section is processed to coil (LI) and capacitor (Cl) along with transistor (T-l) of Hartley oscillator and generate the frequency at fixed value (in range 27MHz - 35 MHz). The signal is amplified by transistor T-2 and fed to the base of transistor T-3. The signal is frequency modulated on the carrier wave which is generated by tank circuit, connected to collector of transistor T-3, The FM modulated wave is transmitted through Coil L-2. Reference is now invited to Fig. 2 which illustrate the receiving/processing unit. As shown in the Fig. 2, the receiving section is comprised of three sub-sections comprising (i) Receiver/Oscillator, (ii) Modulator and (iii) Output section. The r.f. signal is first received by a loop antenna. The signal at this stage is found very weak and needs further amplification before process to demodulator circuit. The emf is amplified by amplifier transistors T-l and T-2 as clearly illustrated in figure 2. The demodulator circuit filter out the modulating signal from carrier frequency. This FM signal is demodulated by transistor T-4 according to the carrier generated by tank circuit L-1, C9, The signal is then further amplified and applied to the bistate latching transistor T-6 and T-7 circuit to latch this state i.e. relay will continue to be energized. The signal acts as a trigger pulse to change the state of bistate latching transistor from one state to another, Finally the signal is processed through driver circuit to drive 12V relay. The output of bistate latching transistor is operated through transistor T-8 and means to drive the relay and provides, open collector transistor output and opto-coupler. The necessary voltage for the receiver is provided through a regulated power supply. Preferably, in order to protect the unit from external disturbance i.e. electromagnetic signal generated due to movement of cranes/welding machines/high transient due to switching on/off of motors etc, and save it from the heat due to radiation of object which is to be sensed, the unit is enclosed in bakellite material. The signal received is amplified and frequency modulated over carrier wave and transmitted (as illustrated in Fig -1), A 9 volts cell is housed inside the unit, Before discharging of cell below to operating level, a LED indication is provided as caution to replace the cell within 24 hours. The unit has in-built facility to charge the system. Presently rechargeable battery cell provides power to transmitting - section, As would be evident from the above, in the system of the invention no wire is used for signal transmission of photosensor signal which obviously avoids the problems and disadvantages associate with the conventional use of multi-core wire for transmitting the photosensor signal from sensing unit to signal processing unit. The system of the invention can have varied application and specifically in relation to the steel industries the same can have the following applications, I. In rolling mill: a) Bloom and billet mill : To sense the rolling of billet before as well as after the flying shear for measuring the length and velocity of billet, Due to cobble prone area, normal photosensor cable used to burn very frequently. b) Wire rod mill: - To sense the billets charging and discharging of billets from reheating furnace. - To sense the billet for controlling the roller table, flying shear, rolling stands. c) Rail mill : To sense the rail at hot saw, at rail finishing for roll table control i.e. energy conservation. II. In Blast Furnace : - To sense the movement of hoisting mechanism at the top of B F. - To prevent the falling of ore bridge cranes by sensing extreme limits of trolley. The system of the invention can therefore have varied end uses and being simple and cost-effective such uses can be extended to various other applications of photosensors. In particular, since the system does not use any cables and conduit the problem of burning and damage of the photosensor cables/conduits can be avoided and the system would thus also be safe and reliable. WE CLAIM : 1. A wireless photosensing system comprising a sensing and transmitting unit (Fig.1) and a receiving and processing unit(Fig.2); means for transmitting variation in collector signal PTI (Fig.1) according to presence/absence of light on the base of photosensor through a frequency modulated circuit and radiating a photosensor signal; said receiving and processing unit comprising means for receiving the photosensor signal PTI(Fig.l) as induced voltage, demodulating carrier means output of L-C9 (Fig.2) having an operating frequency same as that of the transmitting section, means for latching amount of 13 (Fig.2) the state for transition low to high photosensor signal and vice-versa and means to actuate (RL of Fig.2) relevant drive means based on said photosensor signal. 2. A wireless photo sensing system as claimed in claim 1 wherein said transmitting unit comprise frequency modulated circuit. 3. A wireless photo sensing system as claimed in anyone of claims 1 to 2 wherein said transmitting unit comprise a tank circuit (LI-CI) of hertley oscillator adapted to receive the amplified output voltage, low amplified oscillatory voltage being amplified by transistor means Tl (Fig.1) and fed back to said tank circuit through coil means L2 (Fig.I) adapted to function as antenna and radiate photosensor signals. 4. A wireless photo sensing system as claimed in anyone of claims 1 to 3 wherein said receiving unit comprises antenna coil means L3 (Fig.2) for receiving induced voltage ; amplifier (T2) and inverter (T3) means ; tank circuitry (L4 C9) adapted to function as demodulating carrier having operating frequency same as that of the said first tank circuitry of the transmitting section ; means for further amplification (T5) of the demodulated signal and transistor means (T6-T7) adapted to latch the state of transition low to high photosensor signal and vice-versa ; means for amplification(T8) of the low valve latch signal for driving of relay means. 5. A wireless photo sensing system as claimed in anyone of claims 1 to 4, comprising amplifier means (Al) to amplify the signal generated by the photo transistor means (PTI) and pass through comparator circuit comprising filter means A2(Fig.l) wherein signal due to unwanted light is filtered out by means for adjusting the threshold voltage through variable resistance (PT2) such that only upon arrival of luminous object the signal exceeds the threshold voltage to light an LED indicator (Dl). 6. A wireless photo sensing system as claimed in anyone of claims 1 to 5, wherein said transmitting unit comprise a processing means having a coil (LI Cl), capacitor and transistor means (Tl) of heartly oscillation and adapted to generate frequency at fixed value in the range of 27-35 MHz ; means for amplifying (Al) the signal and feeding to a base transistor (Tl); means for frequency modulating (collector amplitude of photo transistor) the signal on the carrier wave generated by tank circuit connected to collector of said transistor; means for transmitting the FM modulated wave through coil (L2). 7. A wireless photo sensing system as claimed in anyone of claims 1 to 6, wherein said receiving/processing unit comprise receiver/oscillator means (L3-C2-CI Tl); demodulator means (shown in Fig.2); and output means(RL) 8. A wireless photo sensing system as claimed in claim 7, wherein said receiver/oscillator means comprise loop antenna means (L3) for receiving the signal and means for amplification (T2) of the signal before passing in the demodulator means (shown in Fig.2); said demodulator means (T4) comprising demodulating circuit for filtering out the demodulated signal from the carrier frequency ; transistor means for demodulating the FM signal according to the carrier generated by the tank circuit. means for further amplifying the signal and applying to bistate latching(T6 T7) transistors and circuitry to latch such state, said signal adapted to trigger pulse to change the state of bistate latching transistors (T6-T7) from one state to another; means to process the signal through driver circuit (T8) to drive corresponding relay means (RL). 9. A wireless photo sensing system as claimed in anyone of claims 1 to 8, wherein the output of the bistate latching transistor (T6-T7) is adapted either to operate through transistor to drive relay, or open collection transistor output (not shown) or opto coupler, the bias voltage from the receiving unit being supplied through a regulated power supply (not shown). 10. A wireless photo sensing system as claimed in anyone of claims 1 to 9, wherein the transmitter unit (Fig.1) is enclosed in bakelite casing, (non- farrite/magnetic) 11. A wireless photo sensing system as claimed in claim 10, wherein the transmitter unit houses a cell (not shown) inside the unit and adapted such that prior to discharge below the operating voltage an LED indicator is adapted to indicate required replacement of the cell. 12. A wireless photo sensing system as claimed in anyone of claims 10 or 11 wherein rechargeable battery (not shown) cell provides power to transmitter section. 13. A wireless photo sensing system substantially as hereinadescribed and illustrated with reference to the accompanying figures.

Documents:

221-del-2000-abstract.pdf

221-del-2000-claims.pdf

221-del-2000-corrrespondence-others.pdf

221-del-2000-corrrespondence-po.pdf

221-del-2000-description (complete).pdf

221-del-2000-drawings.pdf

221-del-2000-form-1.pdf

221-del-2000-form-19.pdf

221-del-2000-form-2.pdf

221-del-2000-form-3.pdf

221-del-2000-gpa.pdf