Title of Invention	DROPLET DEPOSITION APPARATUS .
Abstract	Droplet deposition apparatus comprises at least one droplet ejection unit (302, 304) comprising a plurality of fluid channels disposed side by side in a row, actuator means, and a plurality of nozzles, said actuator means being actuable to eject a droplet of fluid from a fluid channel through a respective nozzle; a support member (300) for said at least one droplet ejection unit: a first conduit (320) extending along said row and to one side of both said support member and said at least one droplet ejection unit for conveying droplet fluid to each of the fluid channels of said at least one droplet ejection unit; and a second conduit (330) extending along said row and to the other side of both said support member and said at least one droplet ejection unit for receiving droplet fluid from each of the fluid channels of said at least one droplet ejection unit.

Title of Invention

DROPLET DEPOSITION APPARATUS .

Abstract

Droplet deposition apparatus comprises at least one droplet ejection unit (302, 304) comprising a plurality of fluid channels disposed side by side in a row, actuator means, and a plurality of nozzles, said actuator means being actuable to eject a droplet of fluid from a fluid channel through a respective nozzle; a support member (300) for said at least one droplet ejection unit: a first conduit (320) extending along said row and to one side of both said support member and said at least one droplet ejection unit for conveying droplet fluid to each of the fluid channels of said at least one droplet ejection unit; and a second conduit (330) extending along said row and to the other side of both said support member and said at least one droplet ejection unit for receiving droplet fluid from each of the fluid channels of said at least one droplet ejection unit.

Full Text	DROPLET DEPOSITION APPARATUS The present invention relates to droplet deposition apparatus, such as, for example, a drop-on-demand inkjet printer. In order to increase the speed of inkjet printing, inkjet printheads are typically provided with an increasing number of ink ejection channels. For example, there are commercially available inkjet printheads having in excess of 500 ink ejection channels, and is anticipated that in future so called "pagewide printers" could include printheads containing in excess of 2000 ink ejection channels. In at least its preferred embodiments, the present invention seeks to provide droplet deposition apparatus suitable for use in a pagewide printer and having a relatively simple and compact structure. Accordingly, the present invention provides a droplet deposition apparatus comprising : at least one droplet ejection unit comprising a plurality of fluid channels disposed side by side in a row extending in a first direction, an actuator, and a plurality of nozzles, each having a nozzle axis extending in a second direction orthogonal to the first direction, said actuator being actuable to eject a droplet of fluid from a fluid channel through a respective nozzle, said ejection unit having an end face extending in both said first and second directions; a support member for said at least one droplet ejection unit; and a conduit for conveying droplet fluid to each of the fluid channels of said at least one droplet ejection unit; and wherein interconnect means, for electrically connecting said actuator means to drive circuit means, are formed on said end face. Where the apparatus comprises a plurality of droplet ejection units, the first conduit is preferably configured to convey droplet fluid to each of the fluid channels of said plurality of droplet ejection units. Thus, all of the ink channels can be supplied with ink from one conduit. This can reduce significantly the number of ink supply channels or conduits required to convey ink to the ink channels, thereby simplifying machining and providing a compact droplet deposition apparatus. Preferably, the apparatus comprises a second conduit for conveying droplet fluid away from each of the fluid channels of said at least one droplet ejection unit. In one embodiment, there are a plurality of rows of channels, the droplet ejection units being arranged on the support member such that at least some of the fluid channels of adjacent rows of fluid channels are substantially co- axial. Thus, there may be effectively one fluid inlet and one fluid outlet for a number of coaxial ink channels. This can reduce significantly the size of the printhead in the direction of the paper feed. This can also allow the printheads to be closely stacked in the direction of paper feed, which is advantageous in achieving accurate drop placement, a compact printer and hence a lower cost. In a preferred arrangement, each fluid channel has a length extending in a first direction and said at least one row extends in a second direction substantially orthogonal to said first direction. With such an arrangement, preferably the at least one droplet ejection unit is arranged on the support member such that there is at least one row of fluid channels extending in the second direction. The increased density of the components of the apparatus, such as the drive circuitry, can lead to problems associated with overheating. Therefore, preferably at least one of the conduits is arranged so as to transfer a substantial part of the heat generated during droplet ejection to droplet fluid conveyed thereby. The apparatus may include drive circuit means for supplying electrical signals to the actuator means. The drive circuit means may be in substantial thermal contact with at least one of the conduits so as to transfer a substantial part of the heat generated in the drive circuit means to the droplet fluid. Arranging the drive circuit means in such a manner can conveniently allow the ink in the printhead to serve as the sink for the heat generated in the drive circuitry. This can substantially reduce the likelihood of overheating, whilst avoiding the problems with electrical integrity that might occur were the integrated circuit packaging containing the circuitry allowed to come into direct contact with the ink. In one arrangement the drive circuit means is mounted on the support member, the support member being in thermal contact with at least one of the conduits. In one embodiment, the support member comprises a substantially U-shaped, or H-shaped, member, the drive circuit means being mounted on at least one of the two facing sides of the arms of the U-shaped, or H shaped, member. With this arrangement, the drive circuit means can be readily physically isolated from the fluid conveyed by the conduits. Alternatively, the drive circuit means may be mounted on the support member so as to contact droplet fluid being conveyed by at least one of the conduits. With this arrangement it may be necessary to electrically passivate the external surfaces of the drive circuit means. In one embodiment the apparatus comprises a coolant conveying conduit for conveying a coolant fluid, the drive circuit means being proximate the coolant conveying conduit so as to transfer a substantial part of the heat generated in the drive circuit means to the coolant fluid. Cooling of the drive circuit can thus be achieved with reduced transfer of heat to the droplet ejection units. This can reduce any variation in droplet ejection velocity due to fluctuations in the viscosity of the fluid caused by heating of the droplet fluid by the drive circuit. The drive circuit means is preferably mounted on the support member, the support member being in thermal contact with the third conduit. Preferably, the third conduit comprises an aperture formed in the support member. Thus, in another aspect the present invention provides droplet deposition apparatus comprising: at least one droplet ejection unit comprising a plurality of fluid channels disposed side by side in a row, actuator means, drive circuit means for supplying actuating electrical signals to said actuator means, and a plurality of nozzles, said actuator means being actuable to eject a droplet of fluid from a fluid channel through a respective nozzle; droplet fluid conveying means for conveying droplet fluid to each of the fluid channels of said at least one droplet ejection unit; and further coolant conveying means for conveying a coolant fluid, at least one of said drive circuit means and said at least one droplet ejection unit being proximate said coolant conveying means so as to transfer a substantial part of the heat generated during droplet ejection to said coolant fluid. Preferably at least one of said at least one droplet ejection unit and said drive circuit means is mounted on said coolant conveying means. More preferably, both said at least one droplet ejection unit and said drive circuit means are mounted thereon. Preferably, the fluid conveying means comprises a conduit extending along said row and to one side of both said coolant conveying means and said at least one droplet ejection unit for conveying droplet fluid to each of the fluid channels of said at least one droplet ejection unit. The fluid conveying means preferably also comprises a second conduit extending along said row and to the other side of both said coolant conveying means and said at least one droplet ejection unit for receiving droplet fluid from each of the fluid channels of said at least one droplet ejection unit. In an alternative arrangement, there are two rows of fluid channels, each row being arranged on a respective support member having a respective conduit for conveying fluid to that row. Preferably, a further conduit is arranged to convey droplet fluid away from both rows of fluid channels. The second conduit preferably extends between the support members. In one arrangement, the at least one row extends in a first direction and the channels have a length extending in a second direction substantially coplanar with and orthogonal to the first direction, the support member having a dimension in said second direction which is substantially equal to n x the length of a fluid channel in the second direction, where n is the number of rows of channels. By reducing the width of the apparatus in the direction of the paper feed, by forming the support member with a thickness substantially equal to the combined lengths of the ink channels in the second direction, improvements in paper/printhead alignment and dot registration can be provided. PZT, from which the ejection units are typically formed, is relatively expensive and so it is advantageous to ensure that a maximum number of channels are provided for a minimum amount of PZT. Thus, in a further aspect, the present invention provides droplet deposition apparatus comprising: at least one droplet ejection unit comprising a plurality of fluid channels disposed side by side in a row extending in a first direction, said channels having a length extending in a second direction substantially coplanar with and orthogonal to said first direction, actuator means, and a plurality of nozzles, each nozzle having a nozzle axis extending in a third direction substantially orthogonal to said first and second directions, said actuator means being actuable to eject a droplet of fluid from a fluid channel through a respective nozzle; means for conveying droplet fluid to said fluid channels; and a support member for said at least one droplet ejection unit, said at least one droplet ejection unit being arranged on said support member such that there are n rows of fluid channels extending in said first direction (n being an integral number), said support member having a dimension in said second direction which is substantially equal to n x the length of a fluid channel in said second direction. In an alternative arrangement, the support member may comprise an arm of a substantially U-shaped member, at least one droplet ejection unit being supported at the end of each of the arms of the U-shaped member. Preferably, the second conduit extends between the arms of the U-shaped member to convey droplet fluid from the droplet ejection units supported by the arms of the U-shaped member. With such an arrangement, the apparatus may comprise a pair of conduits each for conveying droplet fluid to the or each droplet ejection unit supported by a respective arm, each conduit extending along the external side of the respective arm of the U-shaped member. In another arrangement, the apparatus comprises a cover member extending over and to the sides of the support member to define with the support member at least part of the conduits. The support member and the cover member may be attached to a base which defines with the support member and the cover member the conduits. Thus, the number of apparatus components may be reduced, since, for example, the base, cover member and support member perform multiple functions (including the definition of conduits). In yet another aspect the present invention provides droplet deposition apparatus comprising: a support member; at least one droplet ejection unit attached to said support member and comprising a plurality of fluid channels disposed side by side in a row; and a cover member extending over and to the sides of said support member to define with said support member a first conduit extending along said row for conveying fluid to said fluid channels and a second conduit extending along said row for conveying fluid from said fluid channels. The or each droplet ejection unit may comprise actuator means and a plurality of nozzles, the actuator means being actuable to eject a droplet of fluid from a fluid channel through a respective nozzle. The cover may include apertures for enabling droplets to be ejected from the fluid channels. These apertures are preferably etched in the cover member. In one arrangement the nozzles are formed in the cover. In another arrangement the nozzles are formed in a nozzle plate supported by the cover, each fluid channel being in fluid communication with a respective nozzle via a respective aperture. The use of both a cover member and nozzle plate can provided enhanced tolerance for the laser ablation of the nozzles in the nozzle plate, as precise positioning of the nozzle relative to the ink chamber can become less critical. As the nozzle plate is supported by the cover, it can be made thinner, thereby reducing costs. The cover is preferably formed from a material having a coefficient of thermal expansion which is substantially equal to that of the support member. The cover is preferably formed from metallic material, for example, from molybdenum or Nilo (a nickel/iron alloy). The or each droplet ejection unit may comprise a first piezoelectric layer poled in a first poling direction, and a second piezoelectric layer on said first piezoelectric layer and poled in a direction opposite to said first poling direction, said fluid channels being formed in said first and second piezoelectric layers. Thus, the walls of the fluid channels can serve as wall actuators of the so called "chevron" type. These actuators are known to be advantageous because they require a lower actuating voltage to establish the same pressure in the fluid channels during operation than comparable shear mode cantilever type actuators or other conventional piezoelectric drop on demand actuators. The first piezoelectric layer may be attached directly to said support member. This simple arrangement of the ejection unit can enable the channels to be machined in the first and second piezoelectric layers when the layers are in situ on the support member, thereby simplifying production. In this arrangement, the support member is preferably formed from ceramic material. In alternative arrangement, the first piezoelectric layer is formed on a base layer formed from ceramic material, said base layer being attached to said support member. The axes of the nozzles may extend in a direction substantially orthogonal to the direction of extension of said at least one row. In other words, the droplet ejection unit may be an "edge shooter", with droplets being ejected from the top of the ink channel. The invention is further illustrated, by way of example, with reference to the accompanying drawings, in which: Figure 1 represents a perspective view of a module of a droplet ejection unit; Figure 2 represents a side view of the module shown in Figure 1; Figure 3 represents a perspective view of the module of Figure 1 with electrodes and interconnection tracks formed thereon; Figure 4 represents a perspective view of a single drive circuit connected to a droplet ejection module; Figure 5 represents a perspective view of two drive circuits connected to a droplet ejection module; Figure 6 represents a perspective view of a first embodiment of an arrangement of a droplet ejection module with fluid conduits attached thereto for the supply of fluid to the module; Figure 7 represents a perspective view of the arrangement shown in Figure 6 with a heat sink attached thereto; Figure 8 represents a first array of arrangements shown in Figure 7 in a printhead; Figure 9 represents a second array of arrangements shown in Figure 7 in a printhead; Figure 10 represents a third array of arrangements shown in Figure 7 in a printhead; Figure 11 represents a side view of a second embodiment of an arrangement of a plurality of droplet ejection modules attached to a support member; Figure 12 represents an exploded perspective view of the embodiment shown in Figure 11 with fluid conduits for the supply of fluid to the modules; Figure 13 represents a perspective view of the attachment of a nozzle plate to the arrangement shown in Figure 12; Figure 14 represents a perspective view of a third embodiment of an arrangement of a plurality of droplet ejection modules attached to a support member; Figure 15 represents a side view of the arrangement shown in Figure 14 with a cover member attached thereto to define fluid conduits for the supply of fluid to the modules; Figure 16 represents a side view of a portion of the arrangement shown in Figure 15 attached to a base; Figure 17 represents a perspective view of the arrangement shown in Figure 15 with apertures formed in the cover for the ejection of ink from ink channels; Figure 18 represents a perspective view of the arrangement shown in Figure 15 with a nozzle plate attached to the cover; Figure 19 represents a perspective view of a fourth embodiment of an arrangement of a plurality of droplet ejection modules attached to a support member; Figure 20 represents a side view of a fifth embodiment of an arrangement of droplet ejection modules with fluid conduits for the supply of fluid to the modules; and Figures 21 to 25 represent cross-sectional views of further embodiments of arrangements of droplet ejection modules with fluid conduits attached thereto. The present invention relates to droplet deposition apparatus, such as, for example, drop-on-demand inkjet printheads. In the preferred embodiments of the present invention to be described below, the printhead employs a modular layout of droplet ejection modules to provide a pagewide array of droplet ejection nozzles for the ejection of fluid on to a substrate. The manufacture of such a droplet ejection module will first be described. With reference first to Figures 1 and 2, a droplet ejection module 100 comprises a ceramic base wafer 102 on to which are attached first piezoelectric wafer 104 and second piezoelectric wafer 106. In the preferred embodiment, the base wafer 102 is formed from a glass ceramic wafer having a thermal expansion coefficient CTE between that of the material from which the piezoelectric layers 104, 106 are formed (for example, PZT) and the material from which a support member on to which the base wafer 102 is to be attached are formed. The first piezoelectric wafer 104 is attached to the base wafer 102 by resilient glue bond material 108. Similarly, the second piezoelectric wafer 106 is attached to the first piezoelectric wafer 104 by resilient glue bond material 110. The combination of the CTE of the base wafer 102 and the resilience of the glue bond material 108, 110 provides a buffer for avoiding the distortion of the module 100 that might otherwise occur as a result of the differing thermal expansion characteristics of the piezoelectric material and the support member. In this preferred embodiment, this is particularly important due to the compactness of the droplet ejection unit, as described in more detail below. A row of parallel fluid channels 112 are formed in the piezoelectric layers 104, 106. For example, the fluid channels may be provided by grooves formed in the piezoelectric wafers using a narrow dicing blade. As indicated by arrows 114 and 116 in Figure 2, the piezoelectric wafers are poled in opposite directions. As the wafers 104 and 106 are oppositely poled, the walls 118 of the channels serve as wall actuators of the so called "chevron" type, such as are the subject of European Patents No. 0277703 and No. 0278590, the disclosures of which are incorporated herein by reference. These actuators are known to be advantageous because they require a lower actuating voltage to establish the same pressure in the fluid channels during operation. After forming the channels 112, the wafers are diced to form a module as shown in Figure 1. In the preferred embodiment, the module includes 64 fluid channels, each with a length of 2 mm (approximately equal to 2 x the acoustic length of ink in the channel during operation). With reference to Figure 3, metallised plating is deposited on the opposing faces of the ink channels 112, where it extends the full height of the channel walls 118 providing actuation electrodes 120 to which a passivation coating may be applied. In one technique for forming the electrodes, a seed layer, such as Nd:YAG, is sputtered over the module 100 and into the channels 112. An interconnect pattern 122 is formed one or both sides 124 of the module 100, for example, by using the well-known laser ablation, photoresist or masking technique. Formation of the interconnect pattern on both sides 124 of the module can halve the density of the tracks of the interconnect pattern, thereby facilitating formation of the interconnect pattern. With the seed layer having been defined, the layer is plated to form the electrode tracks, for example, using an electroless nickel plating process. The tops of the walls 118 separating the channels 112 are kept free of plating metal so that the track and the electrode for each channel are electrically isolated from other channels. With reference to Figures 4 and 5, each module is connected to at least one associated drive circuitry (integrated circuit ("chip") 130) by means, for example, of a flexible circuit 132. In the arrangement shown in Figure 4, the module 100 has interconnection tracks formed on one side only, and thus only one chip 130 is required to drive the actuators 118, In the Figure 5 arrangement, the module 100 has interconnection tracks formed on both sides of the module, with two chips 130 driving the actuators 118. Via holes 133 may be formed in the flexible circuit 132 to enable the chip to be connected to other components of the drive circuitry, such as resistors, capacitors or the like. As shown in Figure 5, the module 100 is attached to a support member 140. The drive circuitry 130 may be connected to the module prior to its attachment to the support member, thereby enabling the module to be tested prior to attachment on the support member, or may be connected to the module when it is already attached to the support member 140. As described in more detail below, in the embodiment shown in Figure 5 the support member 140 is made of a material having good thermal conduction properties. Of such materials, aluminium is particularly preferred on the grounds that it can be easily and cheaply formed by extrusion. In order to reduce the size of the printhead in the direction of paper feed, the support member 140 has a thickness in the direction of the length of the fluid channels substantially equal to the length of the fluid channels. Figure 6 illustrates the connection of conduits for conveying ink to and from the module shown in Figure 5 in a first embodiment of a droplet deposition apparatus. The conduits comprise a first ink supply manifold 150 for supplying ink to the module 100 and a second ink supply manifold 152 for conveying ink away from the manifold 152. In the arrangement shown in Figure 6, the manifolds 150, 152 are configured so as to convey ink to and from all of the ink channels of the module 100. The manifolds may be formed from any suitable material, such as plastics material. With reference to Figure 7, a heatsink 160 is connected to the ink outlet 154 of the second manifold 152. The heatsink is hollow, and is used to convey ink away from the second manifold 152 to an ink reservoir (not shown). As shown in Figure 7, the drive circuits 130 are mounted in substantial thermal contact with the heatsink 160 so as to allow a substantial amount of the heat generated by the circuits during their operation to transfer via the heatsink 160 to the ink. To this end, the heat sink 160 is also formed from material having good thermal conduction properties, such as aluminium. Thermally conductive pads 134, or adhesive, may be optionally employed to reduce resistance to heat transfer between circuits 130 and the heatsink 160. A nozzle plate 170 is bonded to the uppermost surface of the module 100. The nozzle plate 170 consists of a strip of polymer such as polyimide, for example Ube Industries polyimide UPILEX R or S, coated with a non-wetting coating as provided in US-A-5010356 (EP-B-0367438). The nozzle plate is bonded by application of a thin layer of glue, allowing the glue to form an adhesive bond between the nozzle plate 170 and the walls 118 then allowing the glue to cure. A row of nozzles, one for each ink channel 112, is formed in the nozzle Plate for example by UV excimer laser ablation, the row of nozzles extending in a direction orthogonal to the length of the ink channels 112 so that the actuators are so called "side shooter" actuators. The module 100, when supplied with ink and operated with suitable voltage signals via the tracks 124 may be traversed either normally or at a suitable angle to the direction of motion across a paper printing surface to deposit ink on the printing surface. Alternatively, an array of independent modules 100 may be provided. The array layout may take any suitable form. For example, as shown in Figure 8, three 180 dpi resolution modules may be angled to the direction of feed of a printing surface 180 to form a 360 dpi resolution array, whilst Figure 9 shows "3-tier interleaved" array of modules and Figure 10 shows a "2-row interleaved" array of modules 100 for providing the required printhead resolution. Such a modular array eliminates the need to serially butt together a plurality of modules at facing end surfaces to provide a printhead having the required droplet density. Nonetheless, such modules may be butted together to form a pagewide array of modules. A second embodiment of droplet deposition apparatus comprising such an arrangement of modules will now be described with reference to Figures 11 to 13. With reference first to Figure 11, this embodiment comprises a plurality of modules 100, for example, as shown in Figure 4 with drive circuitry attached to one side 124 of the module 100. Each module is mounted on the end of an arm of a substantially U-shaped pagewide support member 200. On each arm, the modules are serially butted together at the edges 126 of the modules 100, as shown in Figure 1, such that there is a single row of fluid channels extending orthogonal to the longitudinal axis, or length, of each of the ink channels 112. The modules may be butted together using glue bond material, and aligned using any suitable alignment technique. Each array of butted modules provides a 180 dpi resolution, and therefore the combination of two interleaved arrays formed on respective arms of the support member 200 provides a printhead having a 360 dpi resolution. Similar to the first embodiment, the chips 130 are mounted on the outer surface of the support member 200 so as to lie in substantial thermal contact with the support member 200. As shown in Figure 11, further components 202 of the drive circuitry may be connected to the chip 130 via a printed circuit board 204 mounted on the track using solder bumps 206. Following mounting of the chips on the support member 200, each track 132 is folded in the direction indicated by arrows 208, 210 in Figure 11 so that the printed circuit boards 204 also come into thermal contact with the support member 200. As described in more detail below, the U-shaped support member 200 acts as an outlet manifold for conveying fluid away from the droplet ejection units. The drive circuits 130 for the modules 100 are mounted in substantial thermal contact with that part of structure 200 acting as the outlet manifold so as to allow a substantial amount of the heat generated by the circuits during their operation to transfer via the conduit structure to the ink. To this end, the structure 200 is made of a material having good thermal conduction properties, such as aluminium. With reference to Figure 12, ink inlet manifolds 210, 220 extending substantially the entire length of the support member 200 are provided for supplying ink to each of the modules attached to respective arms of the support member (only one module 100 is shown in figure 11 for clarity purposes only). The inlet manifolds 210, 220 may be formed from extruded plastics or metallic materials. As will be appreciated from Figure 12, the inlet manifolds also act to provide external covers to protect the components 202 of the drive circuitry for the modules 100. Endcaps (not shown) are fitted to the ends of the support member 200 and inlet manifolds 210, 220 to form seals to complete the inlet and outlet manifolds and to enclose the drive circuitry. With reference to Figure 13, similar to the first embodiment a nozzle plate 230 is attached to the tops of the actuator walls 118 and two rows of nozzles formed in the nozzle plate, one row for each of the rows of ink channels. As shown in figure 13, the nozzle plate 230 is additionally supported on each side by portions 240 of the ink inlet manifolds 210, 220. The nozzle plate 230 may be further supported by a support blanking actuator component (not shown) provided at each end of each of the arrays of modules. An example of another arrangement of butted modules will now be described with reference to Figures 14 to 18, in which the U-shaped support member 200 is replaced by a planar, parallel-sided support member 300. With reference to Figures 14 and 15, two rows 302, 304 of modules are attached to the support member 300. Whilst Figure 14 shows two rows of four butted modules, any number of modules may be butted together, although it is preferred that the length of each row is substantially equal to the length of a page (typically 12.6 inches (32 cm) for the American "Foolscap" standard). The support member 300 is preferably formed from ceramic material, such as alumina. This enables the base wafer 102 of the modules 100 to be omitted, thereby reducing further the number of components of the printhead. If so, the first layer 104 of each module is attached directly to the support member 300, for example, using a resilient glue bond. Similar to the module shown in Figure 1, a second piezoelectric layer 106 is attached to the first piezoelectric layer 104. Similar to the arrangement shown in figure 1, ink channels 112 are formed in the piezoelectric layers 104,106 by, for example, machining and electrodes and interconnect tracks are formed in the channels 112 and on both sides of the support member 300 (only a small number of ink channels and interconnects are shown in Figure 14 for clarity purposes only). The ink channels are formed such that each ink channel of one row 302 is co-axial with an ink channel of the other row 304. Drive circuitry, or chips 130, are attached directly to the sides of the support member 300 for supplying electrical pulses to the interconnect tracks to actuate the walls 118 of the channels 112. As the support member is formed from alumina, for example, having a relatively low CTE, this substantially prevents heat generated in the chips 130 from being transferred through the support member to the actuators 118. The drive circuitry may be coated, for example, with parylene. Housings 306 for housing electrical connections to the chips 130 are also attached to each side of the support member 300. The housings 306 may be conveniently formed from injection moulded plastics material. In addition, a fluid inlet/outlet 308 is also attached to each side of the support member 300. The fluid inlet/outlet may be integral with the adjacent housing 306, and may include a filter, especially at the inlet side, for filtering ink to be supplied to the modules. A cover 310 extends over the entire length and to both sides of the support member 300. As shown in figure 16, the base of the support member 300 and both ends of the cover 310 are attached to a base plate 315. The cover is preferably formed from a material that is thermally matched to the material of the piezoelectric wafers 104,106. Molybdenum, which has high strength and thermal conductivity in addition to being thermally matched to PZT, has been found to be a particularly suitable material for the cover. The cover 310 defines with the support member an ink inlet conduit 320 and an ink outlet conduit 330 for conveying ink to and from all of the channels of the two rows 302,304 of modules as indicated by arrows 335 in Figure 15. Endcaps (not shown) are fitted to the ends of the support member 300 and cover 310 to form seals to complete, with the housings 306, the inlet and outlet conduits and to enclose the electronics. The co-axial arrangement of the ink channels of the two rows enables ink to flow from the ink inlet conduit 320 into an ink channel of row 302, from that ink channel directly into an ink channel of the other row 304, and from that ink channel to the ink outlet conduit 330. With the arrangement of chips 130 on the sides of the support member 300, heat generated at the surfaces of the chips in thermal contact with the ink carried by the conduits 320,330 is substantially transferred to the ink. As shown in Figure 17, apertures 340 are formed in the cover 310 to enable ink to be ejected from the modules through the cover 310. The apertures 340 may be formed by any suitable method, for example, UV excimer laser ablation, and may serve as nozzles for the droplet ejection modules, alternatively, as shown in Figure 18, a nozzle plate 350 may be attached to the cover, with nozzles being formed in the nozzle plate 350 such that the nozzles are in fluid communication with the ink channels 112 via the apertures 340. As the nozzle plate 350 is supported by the cover 310, this enables the thickness of the nozzle plate to be reduced. Alternatively, the nozzle plate 350 may be attached directly to the modules, with the cover 310 extending over the nozzle plate with apertures 340 aligned with the nozzles formed in the nozzle plate. Operation of the third embodiment will now be described. In its simplest form, when one pair of actuator walls 118 one row, say 304 are required to eject a droplet of fluid from the ink channel 112 between the actuator walls 118, the walls of the ink channel of row 304 which is co-axial with that ink channel may be driven to replicate the acoustics of an ink manifold disposed at the end of that ink channel. In the case of "grey scale" printing, a number of droplets may be ejected from the ink channel of row 302, followed by a similar number of droplets from the co-axial ink channel of row 304. Alternatively, in order to increase the printing speed, a droplet may be fired from each channel in turn. For example, ink can be drawn into one channel followed by (at some specific frequency) by a similar event in the other co-axial channel. This would provide a constant stable acoustic effect within each channel. Whilst the embodiment shown with reference to Figures 14 to 18 includes two rows of modules, a single row of ink modules may alternatively be used. Such an arrangement is shown in Figure 19. In this embodiment, a single row 402 of modules is attached to the support member 400. Whilst Figure 19 shows four butted modules, any number of modules may be butted together, although it is preferred that the length of each row is substantially equal to the length of a page (typically 12.6 inches (32 cm) for the American "Foolscap" standard). With such an arrangement, the width of the support member may be reduced to substantially the length of a single ink channel 112, and chips 130 connected to one side only of the support member. However, there will, of course, be a reduction in the resolution of the printhead (from 360 dpi to 180 dpi). Resolution may be increased by providing two such arrangements "back to back" with a common ink inlet provided between the rows of modules. Figure 20 shows a simplified cross-sectional view of a fifth embodiment of an arrangement of droplet ejection modules with fluid conduits for the supply of fluid to the modules. In this embodiment, the support structure 500 comprises a laminated structure of multiple sheets of alumina. In the embodiment shown in figure 20, there are 4 laminated sheets 502, 504, 506, 508 of alumina, although any number of sheets may be used. The sheets of the support structure 500 are machined or otherwise shaped to define, in the laminated structure, channels 510, 512 for conveying ink towards and away from one or more modules 514 attached to the support structure 500. As shown in Figure 20, channel 510 conveys ink to conduit 516 extending along one side of module 514 for supplying ink to the module 514, and channel 512 conveys ink away from conduit 518 extending along the other side of module 514. Conduit 518 is defined by a cover member 520 attached to the top of the module 514 and having apertures 522 such that nozzles 524 of nozzle plate 526 are in fluid communication with the ink channels of the module via the apertures 522, and by end cap 528 attached to the side of the support structure. Whilst conduit 516 may be defined in a similar manner, in the arrangement shown in Figure 20 this conduit is common to two support structures 500, and so alternatively this conduit is defined by the cover member 520 and alumina plate 530 to which the two support structures are attached. Similar to the previous embodiments, drive circuitry 130 is attached directly to the sides of the support member 500 for supplying electrical pulses to the interconnect tracks to actuate the walls of the channels of the module. As the support member is formed from alumina, for example, having a relatively low CTE, this substantially prevents heat generated in the chips 130 from being transferred through the support member to the actuators. In this embodiment, however, the drive circuitry is not in fluid communication with the ink conveyed to and from the module, but is instead located in a housing formed in the end cap 528. Figure 21 illustrates a cross-sectional view of a further embodiment of an arrangement of droplet ejection modules with fluid conduits for the supply of fluid to the modules. This embodiment is similar to that of the fifth embodiment, in that a cover extends over and to the sides of the support member 300 to define a first conduit 320 and a second conduit 330 both extending along a row of droplet ejection channels and to the sides of the support member 130. In this embodiment, a single row of modules 302 is mounted on the end of a support member 300, and the first and second conduits 320 and 330 are spaced from the chips 130 mounted on the side of the support member 300 so as to avoid the need to passivate the surfaces of the chips 130. In order to dissipate heat generated by the chips 130 during operation, the support member 300 is formed from thermally conducting material in order to conduct heat generated by the chips 130 to the fluid conveyed by the conduits 320 and 330. In the embodiment shown in Figure 22. two rows 302, 304 of ejection units are provided on a substantially U-shaped, or H-shaped, support member 600 comprising a pair of support members 300a, 300b linked by a bridging wall 602. Chips 130 and associated circuitry 602 are mounted on the facing surfaces of the support members 300a, 300b, interconnect tracks 600 being formed on these surfaces for supplying actuating electrical signals to the walls of the ejection units. Fluid is conveyed to and away from the ejection units by conduits 320, 330 defined by cover member 310 and the support member 600, the bridging wall 602 acting to direct fluid from the first row 302 to the second row 304. Heat generated in the chips 130 during operation is conducted by the support members 300a, 300b into fluid carried by the conduits 320, 330. Figure 23 illustrates an embodiment in which heat generated during operation both by the chips 130 mounted on either side of the support member 650 and by the rows 302, 304 of ejection units mounted on the support member is transferred to a coolant fluid, such as water, conveyed by a conduit 660 passing through the support member 650. The walls 670 of the support member are preferably suitably thin so that heat is conducted to the coolant fluid as quickly as possible. To improve conduction, the walls 670 may be formed from metallic material. The body 675 of the support member may be formed from ceramic material. In the embodiment shown in Figure 23, there is no recirculation of droplet fluid, in that the conduit 330 simply receives fluid from the ejection units 304 and does not convey fluid back to a reservoir for re-use. Figure 24 illustrates a modification of this embodiment, in which conduit 330 is configured to convey fluid back to a reservoir for re-use. Figure 25 illustrates an embodiment in which each row 302, 304 of ejection units is mounted on a respective support member 300. Fluid is conveyed to each row by a respective conduit 320 extending along that row and to one side of the support member on which that row is mounted. Fluid is conveyed away from the rows by a mutual conduit 330 extending between the facing side walls of the two support members 300, heat generated by the chips 130 being transferred to fluid conveyed in the conduit 330. Providing two "inlet" conduits 320 can enable the printhead to be flushed effectively during production to remove dirt. A slow bleed of droplet fluids from one of the conduits 320 can be used to remove air bubbles during printing, whilst a larger flow could be induced during a pause in printing for maintenance purposes. Each feature disclosed in this specification (which term includes the claims) and/or shown in the drawings may be incorporated in the invention independently of other disclosed and/or illustrated features. WE CLAIM : 1. Droplet deposition apparatus comprising : at least one droplet ejection unit comprising a plurality of fluid channels disposed side by side in a row extending in a first direction, an actuator, and a plurality of nozzles, each having a nozzle axis extending in a second direction orthogonal to the first direction, said actuator being actuable to eject a droplet of fluid from a fluid channel through a respective nozzle, said ejection unit having an end face extending in both said first and second directions; a support member 140 for said at least one droplet ejection unit; and a conduit (150, 152) for conveying droplet fluid to each of the fluid channels of said at least one droplet ejection unit; and wherein interconnect/ means, 132 for electrically connecting said actuator means (118) to drive circuit means 130 are formed on said end face. 2. Apparatus as claimed in claim 1, having a second conduit for conveying droplet fluid away from each of the fluid channels of said at least one droplet ejection unit. 3. Apparatus as claimed in claim 2, having a plurality of droplet ejection units, said conduits being adapted to convey droplet fluid to and from each of the fluid channels of said plurality of droplet ejection units. 4. Apparatus as claimed in any of claims 1 to 3, wherein each said fluid channel has a length extending in a third direction orthogonal to both said first and second directions. 5. Apparatus as claimed in any of the preceding claims, having a drive circuit for supplying electrical signals to said actuator. 6. Apparatus as claimed in claim 5, wherein said drive circuit is in substantial thermal contact with at least one of said conduits so as to transfer a substantial part of the heat generated in said drive circuit means to said droplet fluid. 7. Apparatus as claimed in claim 6, wherein said drive circuit is mounted on said support member, said support member being in thermal contact with at least one of said conduits. 8. Apparatus as claimed in claim 7, wherein said drive circuit is mounted on said support member so as to contact droplet fluid being conveyed by at least one of said conduits. 9. Apparatus as claimed in claim 7, wherein said drive circuit is mounted on said support member so as to be distant from droplet fluid being conveyed by at least one of said conduits. 10. Apparatus as claimed in claim 9, wherein said support member comprises a substantially U-shaped member, said drive circuit being mounted on at least one of the two facing walls of the arms of the U-shaped member. 11. Apparatus as claimed in claim 5, having a third conduit for conveying a coolant fluid, said drive circuit means being proximate said coolant conveying conduit so as to transfer a substantial part of the heat generated in said drive circuit to said coolant fluid. 12. Apparatus as claimed in claim 11, wherein said drive circuit is mounted on said support member, said support member being in thermal contact with said third conduit. 13. Apparatus as claimed in claim 12, wherein said third conduit comprises an aperture formed in said support member. 14. Apparatus as claimed in claim 1, wherein there are provided a plurality of rows of fluid channels, said droplet ejection units being arranged on said support member such that at least some of the fluid channels of adjacent rows of fluid channels are substantially co-axial. 15. Apparatus as claimed in claim 1, wherein there are provided two rows of fluid channels, each row being arranged on a respective support member having a respective conduit for conveying fluid to that row. 16. Apparatus as claimed in claim 15, wherein an additional conduit extends between said support members for conveying droplet fluid away from said rows. 17. Apparatus as claimed in claim 4, wherein said support member has a dimension in said third direction which is substantially equal to n x the length of a fluid channel in said third direction, where n is the number of rows of channels. Droplet deposition apparatus comprises at least one droplet ejection unit (302, 304) comprising a plurality of fluid channels disposed side by side in a row, actuator means, and a plurality of nozzles, said actuator means being actuable to eject a droplet of fluid from a fluid channel through a respective nozzle; a support member (300) for said at least one droplet ejection unit: a first conduit (320) extending along said row and to one side of both said support member and said at least one droplet ejection unit for conveying droplet fluid to each of the fluid channels of said at least one droplet ejection unit; and a second conduit (330) extending along said row and to the other side of both said support member and said at least one droplet ejection unit for receiving droplet fluid from each of the fluid channels of said at least one droplet ejection unit.

Full Text

DROPLET DEPOSITION APPARATUS
The present invention relates to droplet deposition apparatus, such as, for example,
a drop-on-demand inkjet printer.
In order to increase the speed of inkjet printing, inkjet printheads are typically
provided with an increasing number of ink ejection channels. For example, there are
commercially available inkjet printheads having in excess of 500 ink ejection channels,
and is anticipated that in future so called "pagewide printers" could include printheads
containing in excess of 2000 ink ejection channels.
In at least its preferred embodiments, the present invention seeks to provide droplet
deposition apparatus suitable for use in a pagewide printer and having a relatively simple
and compact structure.
Accordingly, the present invention provides a droplet deposition apparatus
comprising : at least one droplet ejection unit comprising a plurality of fluid channels
disposed side by side in a row extending in a first direction, an actuator, and a plurality of
nozzles, each having a nozzle axis extending in a second direction orthogonal to the first
direction, said actuator being actuable to eject a droplet of fluid from a fluid channel
through a respective nozzle, said ejection unit having an end face extending in both said
first and second directions; a support member for said at least one droplet ejection unit;
and a conduit for conveying droplet fluid to each of the fluid channels of said at least one
droplet ejection unit; and wherein interconnect means, for electrically connecting said
actuator means to drive circuit means, are formed on said end face.
Where the apparatus comprises a plurality of droplet ejection units, the first conduit
is preferably configured to convey droplet fluid to each of the fluid channels of
said plurality of droplet ejection units. Thus, all of the ink channels

can be supplied with ink from one conduit. This can reduce significantly the
number of ink supply channels or conduits required to convey ink to the ink
channels, thereby simplifying machining and providing a compact droplet
deposition apparatus.
Preferably, the apparatus comprises a second conduit for conveying droplet
fluid away from each of the fluid channels of said at least one droplet ejection
unit.
In one embodiment, there are a plurality of rows of channels, the droplet
ejection units being arranged on the support member such that at least some
of the fluid channels of adjacent rows of fluid channels are substantially co-
axial. Thus, there may be effectively one fluid inlet and one fluid outlet for a
number of coaxial ink channels. This can reduce significantly the size of the
printhead in the direction of the paper feed. This can also allow the printheads
to be closely stacked in the direction of paper feed, which is advantageous in
achieving accurate drop placement, a compact printer and hence a lower cost.
In a preferred arrangement, each fluid channel has a length extending in a first
direction and said at least one row extends in a second direction substantially
orthogonal to said first direction. With such an arrangement, preferably the at
least one droplet ejection unit is arranged on the support member such that
there is at least one row of fluid channels extending in the second direction.
The increased density of the components of the apparatus, such as the drive
circuitry, can lead to problems associated with overheating. Therefore,
preferably at least one of the conduits is arranged so as to transfer a
substantial part of the heat generated during droplet ejection to droplet fluid
conveyed thereby.
The apparatus may include drive circuit means for supplying electrical signals
to the actuator means. The drive circuit means may be in substantial thermal

contact with at least one of the conduits so as to transfer a substantial part of
the heat generated in the drive circuit means to the droplet fluid. Arranging the
drive circuit means in such a manner can conveniently allow the ink in the
printhead to serve as the sink for the heat generated in the drive circuitry.
This can substantially reduce the likelihood of overheating, whilst avoiding the
problems with electrical integrity that might occur were the integrated circuit
packaging containing the circuitry allowed to come into direct contact with the
ink. In one arrangement the drive circuit means is mounted on the support
member, the support member being in thermal contact with at least one of the
conduits. In one embodiment, the support member comprises a substantially
U-shaped, or H-shaped, member, the drive circuit means being mounted on
at least one of the two facing sides of the arms of the U-shaped, or H shaped,
member. With this arrangement, the drive circuit means can be readily
physically isolated from the fluid conveyed by the conduits.
Alternatively, the drive circuit means may be mounted on the support member
so as to contact droplet fluid being conveyed by at least one of the conduits.
With this arrangement it may be necessary to electrically passivate the
external surfaces of the drive circuit means.
In one embodiment the apparatus comprises a coolant conveying conduit for
conveying a coolant fluid, the drive circuit means being proximate the coolant
conveying conduit so as to transfer a substantial part of the heat generated in
the drive circuit means to the coolant fluid. Cooling of the drive circuit can
thus be achieved with reduced transfer of heat to the droplet ejection units.
This can reduce any variation in droplet ejection velocity due to fluctuations in
the viscosity of the fluid caused by heating of the droplet fluid by the drive
circuit. The drive circuit means is preferably mounted on the support member,
the support member being in thermal contact with the third conduit. Preferably,
the third conduit comprises an aperture formed in the support member.
Thus, in another aspect the present invention provides droplet deposition

apparatus comprising:
at least one droplet ejection unit comprising a plurality of fluid channels
disposed side by side in a row, actuator means, drive circuit means for
supplying actuating electrical signals to said actuator means, and a plurality
of nozzles, said actuator means being actuable to eject a droplet of fluid from
a fluid channel through a respective nozzle;
droplet fluid conveying means for conveying droplet fluid to each of the
fluid channels of said at least one droplet ejection unit; and
further coolant conveying means for conveying a coolant fluid, at least
one of said drive circuit means and said at least one droplet ejection unit being
proximate said coolant conveying means so as to transfer a substantial part
of the heat generated during droplet ejection to said coolant fluid.
Preferably at least one of said at least one droplet ejection unit and said drive
circuit means is mounted on said coolant conveying means. More preferably,
both said at least one droplet ejection unit and said drive circuit means are
mounted thereon.
Preferably, the fluid conveying means comprises a conduit extending along
said row and to one side of both said coolant conveying means and said at
least one droplet ejection unit for conveying droplet fluid to each of the fluid
channels of said at least one droplet ejection unit. The fluid conveying means
preferably also comprises a second conduit extending along said row and to
the other side of both said coolant conveying means and said at least one
droplet ejection unit for receiving droplet fluid from each of the fluid channels
of said at least one droplet ejection unit.
In an alternative arrangement, there are two rows of fluid channels, each row
being arranged on a respective support member having a respective conduit
for conveying fluid to that row. Preferably, a further conduit is arranged to
convey droplet fluid away from both rows of fluid channels. The second
conduit preferably extends between the support members.

In one arrangement, the at least one row extends in a first direction and the
channels have a length extending in a second direction substantially coplanar
with and orthogonal to the first direction, the support member having a
dimension in said second direction which is substantially equal to n x the
length of a fluid channel in the second direction, where n is the number of
rows of channels. By reducing the width of the apparatus in the direction of
the paper feed, by forming the support member with a thickness substantially
equal to the combined lengths of the ink channels in the second direction,
improvements in paper/printhead alignment and dot registration can be
provided. PZT, from which the ejection units are typically formed, is relatively
expensive and so it is advantageous to ensure that a maximum number of
channels are provided for a minimum amount of PZT.
Thus, in a further aspect, the present invention provides droplet deposition
apparatus comprising:
at least one droplet ejection unit comprising a plurality of fluid channels
disposed side by side in a row extending in a first direction, said channels
having a length extending in a second direction substantially coplanar with and
orthogonal to said first direction, actuator means, and a plurality of nozzles,
each nozzle having a nozzle axis extending in a third direction substantially
orthogonal to said first and second directions, said actuator means being
actuable to eject a droplet of fluid from a fluid channel through a respective
nozzle;
means for conveying droplet fluid to said fluid channels; and
a support member for said at least one droplet ejection unit, said at
least one droplet ejection unit being arranged on said support member such
that there are n rows of fluid channels extending in said first direction (n being
an integral number), said support member having a dimension in said second
direction which is substantially equal to n x the length of a fluid channel in said
second direction.
In an alternative arrangement, the support member may comprise an arm of

a substantially U-shaped member, at least one droplet ejection unit being
supported at the end of each of the arms of the U-shaped member.
Preferably, the second conduit extends between the arms of the U-shaped
member to convey droplet fluid from the droplet ejection units supported by the
arms of the U-shaped member. With such an arrangement, the apparatus may
comprise a pair of conduits each for conveying droplet fluid to the or each
droplet ejection unit supported by a respective arm, each conduit extending
along the external side of the respective arm of the U-shaped member.
In another arrangement, the apparatus comprises a cover member extending
over and to the sides of the support member to define with the support
member at least part of the conduits.
The support member and the cover member may be attached to a base which
defines with the support member and the cover member the conduits. Thus,
the number of apparatus components may be reduced, since, for example, the
base, cover member and support member perform multiple functions (including
the definition of conduits).
In yet another aspect the present invention provides droplet deposition
apparatus comprising:
a support member;
at least one droplet ejection unit attached to said support member and
comprising a plurality of fluid channels disposed side by side in a row; and
a cover member extending over and to the sides of said support
member to define with said support member a first conduit extending along
said row for conveying fluid to said fluid channels and a second conduit
extending along said row for conveying fluid from said fluid channels.
The or each droplet ejection unit may comprise actuator means and a plurality
of nozzles, the actuator means being actuable to eject a droplet of fluid from

a fluid channel through a respective nozzle.
The cover may include apertures for enabling droplets to be ejected from the
fluid channels. These apertures are preferably etched in the cover member.
In one arrangement the nozzles are formed in the cover. In another
arrangement the nozzles are formed in a nozzle plate supported by the cover,
each fluid channel being in fluid communication with a respective nozzle via
a respective aperture. The use of both a cover member and nozzle plate can
provided enhanced tolerance for the laser ablation of the nozzles in the nozzle
plate, as precise positioning of the nozzle relative to the ink chamber can
become less critical. As the nozzle plate is supported by the cover, it can be
made thinner, thereby reducing costs. The cover is preferably formed from a
material having a coefficient of thermal expansion which is substantially equal
to that of the support member.
The cover is preferably formed from metallic material, for example, from
molybdenum or Nilo (a nickel/iron alloy).
The or each droplet ejection unit may comprise a first piezoelectric layer poled
in a first poling direction, and a second piezoelectric layer on said first
piezoelectric layer and poled in a direction opposite to said first poling
direction, said fluid channels being formed in said first and second
piezoelectric layers. Thus, the walls of the fluid channels can serve as wall
actuators of the so called "chevron" type. These actuators are known to be
advantageous because they require a lower actuating voltage to establish the
same pressure in the fluid channels during operation than comparable shear mode cantilever type actuators or other conventional piezoelectric drop on
demand actuators.
The first piezoelectric layer may be attached directly to said support member.
This simple arrangement of the ejection unit can enable the channels to be
machined in the first and second piezoelectric layers when the layers are in

situ on the support member, thereby simplifying production. In this
arrangement, the support member is preferably formed from ceramic material.
In alternative arrangement, the first piezoelectric layer is formed on a base
layer formed from ceramic material, said base layer being attached to said
support member.
The axes of the nozzles may extend in a direction substantially orthogonal to
the direction of extension of said at least one row. In other words, the droplet
ejection unit may be an "edge shooter", with droplets being ejected from the
top of the ink channel.
The invention is further illustrated, by way of example, with reference to the
accompanying drawings, in which:
Figure 1 represents a perspective view of a module of a droplet ejection unit;
Figure 2 represents a side view of the module shown in Figure 1;
Figure 3 represents a perspective view of the module of Figure 1 with
electrodes and interconnection tracks formed thereon;
Figure 4 represents a perspective view of a single drive circuit connected to
a droplet ejection module;
Figure 5 represents a perspective view of two drive circuits connected to a
droplet ejection module;
Figure 6 represents a perspective view of a first embodiment of an
arrangement of a droplet ejection module with fluid conduits attached thereto
for the supply of fluid to the module;

Figure 7 represents a perspective view of the arrangement shown in Figure 6
with a heat sink attached thereto;
Figure 8 represents a first array of arrangements shown in Figure 7 in a
printhead;
Figure 9 represents a second array of arrangements shown in Figure 7 in a
printhead;
Figure 10 represents a third array of arrangements shown in Figure 7 in a
printhead;
Figure 11 represents a side view of a second embodiment of an arrangement
of a plurality of droplet ejection modules attached to a support member;
Figure 12 represents an exploded perspective view of the embodiment shown
in Figure 11 with fluid conduits for the supply of fluid to the modules;
Figure 13 represents a perspective view of the attachment of a nozzle plate
to the arrangement shown in Figure 12;
Figure 14 represents a perspective view of a third embodiment of an
arrangement of a plurality of droplet ejection modules attached to a support
member;
Figure 15 represents a side view of the arrangement shown in Figure 14 with
a cover member attached thereto to define fluid conduits for the supply of fluid
to the modules;
Figure 16 represents a side view of a portion of the arrangement shown in
Figure 15 attached to a base;

Figure 17 represents a perspective view of the arrangement shown in Figure
15 with apertures formed in the cover for the ejection of ink from ink channels;
Figure 18 represents a perspective view of the arrangement shown in Figure
15 with a nozzle plate attached to the cover;
Figure 19 represents a perspective view of a fourth embodiment of an
arrangement of a plurality of droplet ejection modules attached to a support
member;
Figure 20 represents a side view of a fifth embodiment of an arrangement of
droplet ejection modules with fluid conduits for the supply of fluid to the
modules; and
Figures 21 to 25 represent cross-sectional views of further embodiments of
arrangements of droplet ejection modules with fluid conduits attached thereto.
The present invention relates to droplet deposition apparatus, such as, for
example, drop-on-demand inkjet printheads. In the preferred embodiments of
the present invention to be described below, the printhead employs a modular
layout of droplet ejection modules to provide a pagewide array of droplet
ejection nozzles for the ejection of fluid on to a substrate. The manufacture
of such a droplet ejection module will first be described.
With reference first to Figures 1 and 2, a droplet ejection module 100
comprises a ceramic base wafer 102 on to which are attached first
piezoelectric wafer 104 and second piezoelectric wafer 106. In the preferred
embodiment, the base wafer 102 is formed from a glass ceramic wafer having
a thermal expansion coefficient CTE between that of the material from which
the piezoelectric layers 104, 106 are formed (for example, PZT) and the
material from which a support member on to which the base wafer 102 is to
be attached are formed. The first piezoelectric wafer 104 is attached to the

base wafer 102 by resilient glue bond material 108. Similarly, the second
piezoelectric wafer 106 is attached to the first piezoelectric wafer 104 by
resilient glue bond material 110. The combination of the CTE of the base wafer
102 and the resilience of the glue bond material 108, 110 provides a buffer for
avoiding the distortion of the module 100 that might otherwise occur as a result
of the differing thermal expansion characteristics of the piezoelectric material
and the support member. In this preferred embodiment, this is particularly
important due to the compactness of the droplet ejection unit, as described in
more detail below.
A row of parallel fluid channels 112 are formed in the piezoelectric layers 104,
106. For example, the fluid channels may be provided by grooves formed in
the piezoelectric wafers using a narrow dicing blade. As indicated by arrows
114 and 116 in Figure 2, the piezoelectric wafers are poled in opposite
directions. As the wafers 104 and 106 are oppositely poled, the walls 118 of
the channels serve as wall actuators of the so called "chevron" type, such as
are the subject of European Patents No. 0277703 and No. 0278590, the
disclosures of which are incorporated herein by reference. These actuators
are known to be advantageous because they require a lower actuating voltage
to establish the same pressure in the fluid channels during operation.
After forming the channels 112, the wafers are diced to form a module as
shown in Figure 1. In the preferred embodiment, the module includes 64 fluid
channels, each with a length of 2 mm (approximately equal to 2 x the acoustic
length of ink in the channel during operation).
With reference to Figure 3, metallised plating is deposited on the opposing
faces of the ink channels 112, where it extends the full height of the channel
walls 118 providing actuation electrodes 120 to which a passivation coating
may be applied. In one technique for forming the electrodes, a seed layer,
such as Nd:YAG, is sputtered over the module 100 and into the channels 112.
An interconnect pattern 122 is formed one or both sides 124 of the module

100, for example, by using the well-known laser ablation, photoresist or
masking technique. Formation of the interconnect pattern on both sides 124
of the module can halve the density of the tracks of the interconnect pattern,
thereby facilitating formation of the interconnect pattern. With the seed layer
having been defined, the layer is plated to form the electrode tracks, for
example, using an electroless nickel plating process. The tops of the walls
118 separating the channels 112 are kept free of plating metal so that the
track and the electrode for each channel are electrically isolated from other
channels.
With reference to Figures 4 and 5, each module is connected to at least one
associated drive circuitry (integrated circuit ("chip") 130) by means, for
example, of a flexible circuit 132. In the arrangement shown in Figure 4, the
module 100 has interconnection tracks formed on one side only, and thus only
one chip 130 is required to drive the actuators 118, In the Figure 5
arrangement, the module 100 has interconnection tracks formed on both sides
of the module, with two chips 130 driving the actuators 118. Via holes 133
may be formed in the flexible circuit 132 to enable the chip to be connected
to other components of the drive circuitry, such as resistors, capacitors or the
like.
As shown in Figure 5, the module 100 is attached to a support member 140.
The drive circuitry 130 may be connected to the module prior to its attachment
to the support member, thereby enabling the module to be tested prior to
attachment on the support member, or may be connected to the module when
it is already attached to the support member 140.
As described in more detail below, in the embodiment shown in Figure 5 the
support member 140 is made of a material having good thermal conduction
properties. Of such materials, aluminium is particularly preferred on the
grounds that it can be easily and cheaply formed by extrusion. In order to
reduce the size of the printhead in the direction of paper feed, the support

member 140 has a thickness in the direction of the length of the fluid channels
substantially equal to the length of the fluid channels.
Figure 6 illustrates the connection of conduits for conveying ink to and from the
module shown in Figure 5 in a first embodiment of a droplet deposition
apparatus. The conduits comprise a first ink supply manifold 150 for supplying
ink to the module 100 and a second ink supply manifold 152 for conveying ink
away from the manifold 152. In the arrangement shown in Figure 6, the
manifolds 150, 152 are configured so as to convey ink to and from all of the
ink channels of the module 100. The manifolds may be formed from any
suitable material, such as plastics material.
With reference to Figure 7, a heatsink 160 is connected to the ink outlet 154
of the second manifold 152. The heatsink is hollow, and is used to convey ink
away from the second manifold 152 to an ink reservoir (not shown). As shown
in Figure 7, the drive circuits 130 are mounted in substantial thermal contact
with the heatsink 160 so as to allow a substantial amount of the heat
generated by the circuits during their operation to transfer via the heatsink 160
to the ink. To this end, the heat sink 160 is also formed from material having
good thermal conduction properties, such as aluminium. Thermally conductive
pads 134, or adhesive, may be optionally employed to reduce resistance to
heat transfer between circuits 130 and the heatsink 160.
A nozzle plate 170 is bonded to the uppermost surface of the module 100.
The nozzle plate 170 consists of a strip of polymer such as polyimide, for
example Ube Industries polyimide UPILEX R or S, coated with a non-wetting
coating as provided in US-A-5010356 (EP-B-0367438). The nozzle plate is
bonded by application of a thin layer of glue, allowing the glue to form an
adhesive bond between the nozzle plate 170 and the walls 118 then allowing
the glue to cure. A row of nozzles, one for each ink channel 112, is formed in
the nozzle Plate for example by UV excimer laser ablation, the row of nozzles
extending in a direction orthogonal to the length of the ink channels 112 so

that the actuators are so called "side shooter" actuators.
The module 100, when supplied with ink and operated with suitable voltage
signals via the tracks 124 may be traversed either normally or at a suitable
angle to the direction of motion across a paper printing surface to deposit ink
on the printing surface. Alternatively, an array of independent modules 100
may be provided. The array layout may take any suitable form. For example,
as shown in Figure 8, three 180 dpi resolution modules may be angled to the
direction of feed of a printing surface 180 to form a 360 dpi resolution array,
whilst Figure 9 shows "3-tier interleaved" array of modules and Figure 10
shows a "2-row interleaved" array of modules 100 for providing the required
printhead resolution.
Such a modular array eliminates the need to serially butt together a plurality
of modules at facing end surfaces to provide a printhead having the required
droplet density. Nonetheless, such modules may be butted together to form
a pagewide array of modules.
A second embodiment of droplet deposition apparatus comprising such an
arrangement of modules will now be described with reference to Figures 11 to
13.
With reference first to Figure 11, this embodiment comprises a plurality of
modules 100, for example, as shown in Figure 4 with drive circuitry attached
to one side 124 of the module 100. Each module is mounted on the end of an
arm of a substantially U-shaped pagewide support member 200. On each
arm, the modules are serially butted together at the edges 126 of the modules
100, as shown in Figure 1, such that there is a single row of fluid channels
extending orthogonal to the longitudinal axis, or length, of each of the ink
channels 112. The modules may be butted together using glue bond material,
and aligned using any suitable alignment technique. Each array of butted
modules provides a 180 dpi resolution, and therefore the combination of two

interleaved arrays formed on respective arms of the support member 200
provides a printhead having a 360 dpi resolution.
Similar to the first embodiment, the chips 130 are mounted on the outer
surface of the support member 200 so as to lie in substantial thermal contact
with the support member 200. As shown in Figure 11, further components 202
of the drive circuitry may be connected to the chip 130 via a printed circuit
board 204 mounted on the track using solder bumps 206. Following mounting
of the chips on the support member 200, each track 132 is folded in the
direction indicated by arrows 208, 210 in Figure 11 so that the printed circuit
boards 204 also come into thermal contact with the support member 200.
As described in more detail below, the U-shaped support member 200 acts as
an outlet manifold for conveying fluid away from the droplet ejection units. The
drive circuits 130 for the modules 100 are mounted in substantial thermal
contact with that part of structure 200 acting as the outlet manifold so as to
allow a substantial amount of the heat generated by the circuits during their
operation to transfer via the conduit structure to the ink. To this end, the
structure 200 is made of a material having good thermal conduction properties,
such as aluminium.
With reference to Figure 12, ink inlet manifolds 210, 220 extending
substantially the entire length of the support member 200 are provided for
supplying ink to each of the modules attached to respective arms of the
support member (only one module 100 is shown in figure 11 for clarity
purposes only). The inlet manifolds 210, 220 may be formed from extruded
plastics or metallic materials. As will be appreciated from Figure 12, the inlet
manifolds also act to provide external covers to protect the components 202
of the drive circuitry for the modules 100. Endcaps (not shown) are fitted to
the ends of the support member 200 and inlet manifolds 210, 220 to form
seals to complete the inlet and outlet manifolds and to enclose the drive
circuitry.

With reference to Figure 13, similar to the first embodiment a nozzle plate 230
is attached to the tops of the actuator walls 118 and two rows of nozzles
formed in the nozzle plate, one row for each of the rows of ink channels. As
shown in figure 13, the nozzle plate 230 is additionally supported on each side
by portions 240 of the ink inlet manifolds 210, 220. The nozzle plate 230 may
be further supported by a support blanking actuator component (not shown)
provided at each end of each of the arrays of modules.
An example of another arrangement of butted modules will now be described
with reference to Figures 14 to 18, in which the U-shaped support member 200
is replaced by a planar, parallel-sided support member 300.
With reference to Figures 14 and 15, two rows 302, 304 of modules are
attached to the support member 300. Whilst Figure 14 shows two rows of four
butted modules, any number of modules may be butted together, although it
is preferred that the length of each row is substantially equal to the length of
a page (typically 12.6 inches (32 cm) for the American "Foolscap" standard).
The support member 300 is preferably formed from ceramic material, such as
alumina. This enables the base wafer 102 of the modules 100 to be omitted,
thereby reducing further the number of components of the printhead. If so, the
first layer 104 of each module is attached directly to the support member 300,
for example, using a resilient glue bond. Similar to the module shown in
Figure 1, a second piezoelectric layer 106 is attached to the first piezoelectric
layer 104.
Similar to the arrangement shown in figure 1, ink channels 112 are formed in
the piezoelectric layers 104,106 by, for example, machining and electrodes
and interconnect tracks are formed in the channels 112 and on both sides of
the support member 300 (only a small number of ink channels and
interconnects are shown in Figure 14 for clarity purposes only). The ink

channels are formed such that each ink channel of one row 302 is co-axial
with an ink channel of the other row 304.
Drive circuitry, or chips 130, are attached directly to the sides of the support
member 300 for supplying electrical pulses to the interconnect tracks to
actuate the walls 118 of the channels 112. As the support member is formed
from alumina, for example, having a relatively low CTE, this substantially
prevents heat generated in the chips 130 from being transferred through the
support member to the actuators 118. The drive circuitry may be coated, for
example, with parylene.
Housings 306 for housing electrical connections to the chips 130 are also
attached to each side of the support member 300. The housings 306 may be
conveniently formed from injection moulded plastics material. In addition, a
fluid inlet/outlet 308 is also attached to each side of the support member 300.
The fluid inlet/outlet may be integral with the adjacent housing 306, and may
include a filter, especially at the inlet side, for filtering ink to be supplied to the
modules.
A cover 310 extends over the entire length and to both sides of the support
member 300. As shown in figure 16, the base of the support member 300
and both ends of the cover 310 are attached to a base plate 315. The cover
is preferably formed from a material that is thermally matched to the material
of the piezoelectric wafers 104,106. Molybdenum, which has high strength
and thermal conductivity in addition to being thermally matched to PZT, has
been found to be a particularly suitable material for the cover.
The cover 310 defines with the support member an ink inlet conduit 320 and
an ink outlet conduit 330 for conveying ink to and from all of the channels of
the two rows 302,304 of modules as indicated by arrows 335 in Figure 15.
Endcaps (not shown) are fitted to the ends of the support member 300 and
cover 310 to form seals to complete, with the housings 306, the inlet and outlet

conduits and to enclose the electronics.
The co-axial arrangement of the ink channels of the two rows enables ink to
flow from the ink inlet conduit 320 into an ink channel of row 302, from that ink
channel directly into an ink channel of the other row 304, and from that ink
channel to the ink outlet conduit 330. With the arrangement of chips 130 on
the sides of the support member 300, heat generated at the surfaces of the
chips in thermal contact with the ink carried by the conduits 320,330 is
substantially transferred to the ink.
As shown in Figure 17, apertures 340 are formed in the cover 310 to enable
ink to be ejected from the modules through the cover 310. The apertures 340
may be formed by any suitable method, for example, UV excimer laser
ablation, and may serve as nozzles for the droplet ejection modules,
alternatively, as shown in Figure 18, a nozzle plate 350 may be attached to the
cover, with nozzles being formed in the nozzle plate 350 such that the nozzles
are in fluid communication with the ink channels 112 via the apertures 340.
As the nozzle plate 350 is supported by the cover 310, this enables the
thickness of the nozzle plate to be reduced. Alternatively, the nozzle plate 350
may be attached directly to the modules, with the cover 310 extending over the
nozzle plate with apertures 340 aligned with the nozzles formed in the nozzle
plate.
Operation of the third embodiment will now be described.
In its simplest form, when one pair of actuator walls 118 one row, say 304 are
required to eject a droplet of fluid from the ink channel 112 between the
actuator walls 118, the walls of the ink channel of row 304 which is co-axial
with that ink channel may be driven to replicate the acoustics of an ink
manifold disposed at the end of that ink channel. In the case of "grey scale"
printing, a number of droplets may be ejected from the ink channel of row 302,
followed by a similar number of droplets from the co-axial ink channel of row

304. Alternatively, in order to increase the printing speed, a droplet may be
fired from each channel in turn. For example, ink can be drawn into one
channel followed by (at some specific frequency) by a similar event in the
other co-axial channel. This would provide a constant stable acoustic effect
within each channel.
Whilst the embodiment shown with reference to Figures 14 to 18 includes two
rows of modules, a single row of ink modules may alternatively be used. Such
an arrangement is shown in Figure 19. In this embodiment, a single row 402
of modules is attached to the support member 400. Whilst Figure 19 shows
four butted modules, any number of modules may be butted together, although
it is preferred that the length of each row is substantially equal to the length
of a page (typically 12.6 inches (32 cm) for the American "Foolscap" standard).
With such an arrangement, the width of the support member may be reduced
to substantially the length of a single ink channel 112, and chips 130
connected to one side only of the support member. However, there will, of
course, be a reduction in the resolution of the printhead (from 360 dpi to 180
dpi). Resolution may be increased by providing two such arrangements "back
to back" with a common ink inlet provided between the rows of modules.
Figure 20 shows a simplified cross-sectional view of a fifth embodiment of an
arrangement of droplet ejection modules with fluid conduits for the supply of
fluid to the modules. In this embodiment, the support structure 500 comprises
a laminated structure of multiple sheets of alumina. In the embodiment shown
in figure 20, there are 4 laminated sheets 502, 504, 506, 508 of alumina,
although any number of sheets may be used.
The sheets of the support structure 500 are machined or otherwise shaped to
define, in the laminated structure, channels 510, 512 for conveying ink towards
and away from one or more modules 514 attached to the support structure
500. As shown in Figure 20, channel 510 conveys ink to conduit 516
extending along one side of module 514 for supplying ink to the module 514,

and channel 512 conveys ink away from conduit 518 extending along the other
side of module 514.
Conduit 518 is defined by a cover member 520 attached to the top of the
module 514 and having apertures 522 such that nozzles 524 of nozzle plate
526 are in fluid communication with the ink channels of the module via the
apertures 522, and by end cap 528 attached to the side of the support
structure. Whilst conduit 516 may be defined in a similar manner, in the
arrangement shown in Figure 20 this conduit is common to two support
structures 500, and so alternatively this conduit is defined by the cover
member 520 and alumina plate 530 to which the two support structures are
attached.
Similar to the previous embodiments, drive circuitry 130 is attached directly to
the sides of the support member 500 for supplying electrical pulses to the
interconnect tracks to actuate the walls of the channels of the module. As the
support member is formed from alumina, for example, having a relatively low
CTE, this substantially prevents heat generated in the chips 130 from being
transferred through the support member to the actuators. In this embodiment,
however, the drive circuitry is not in fluid communication with the ink conveyed
to and from the module, but is instead located in a housing formed in the end
cap 528.
Figure 21 illustrates a cross-sectional view of a further embodiment of an
arrangement of droplet ejection modules with fluid conduits for the supply of
fluid to the modules. This embodiment is similar to that of the fifth
embodiment, in that a cover extends over and to the sides of the support
member 300 to define a first conduit 320 and a second conduit 330 both
extending along a row of droplet ejection channels and to the sides of the
support member 130. In this embodiment, a single row of modules 302 is
mounted on the end of a support member 300, and the first and second
conduits 320 and 330 are spaced from the chips 130 mounted on the side of

the support member 300 so as to avoid the need to passivate the surfaces of
the chips 130. In order to dissipate heat generated by the chips 130 during
operation, the support member 300 is formed from thermally conducting
material in order to conduct heat generated by the chips 130 to the fluid
conveyed by the conduits 320 and 330.
In the embodiment shown in Figure 22. two rows 302, 304 of ejection units are
provided on a substantially U-shaped, or H-shaped, support member 600
comprising a pair of support members 300a, 300b linked by a bridging wall
602. Chips 130 and associated circuitry 602 are mounted on the facing
surfaces of the support members 300a, 300b, interconnect tracks 600 being
formed on these surfaces for supplying actuating electrical signals to the walls
of the ejection units. Fluid is conveyed to and away from the ejection units by
conduits 320, 330 defined by cover member 310 and the support member 600,
the bridging wall 602 acting to direct fluid from the first row 302 to the second
row 304. Heat generated in the chips 130 during operation is conducted by
the support members 300a, 300b into fluid carried by the conduits 320, 330.
Figure 23 illustrates an embodiment in which heat generated during operation
both by the chips 130 mounted on either side of the support member 650 and
by the rows 302, 304 of ejection units mounted on the support member is
transferred to a coolant fluid, such as water, conveyed by a conduit 660
passing through the support member 650. The walls 670 of the support
member are preferably suitably thin so that heat is conducted to the coolant
fluid as quickly as possible. To improve conduction, the walls 670 may be
formed from metallic material. The body 675 of the support member may be
formed from ceramic material.
In the embodiment shown in Figure 23, there is no recirculation of droplet fluid,
in that the conduit 330 simply receives fluid from the ejection units 304 and
does not convey fluid back to a reservoir for re-use. Figure 24 illustrates a

modification of this embodiment, in which conduit 330 is configured to convey
fluid back to a reservoir for re-use.
Figure 25 illustrates an embodiment in which each row 302, 304 of ejection
units is mounted on a respective support member 300. Fluid is conveyed to
each row by a respective conduit 320 extending along that row and to one side
of the support member on which that row is mounted. Fluid is conveyed away
from the rows by a mutual conduit 330 extending between the facing side walls
of the two support members 300, heat generated by the chips 130 being
transferred to fluid conveyed in the conduit 330. Providing two "inlet" conduits
320 can enable the printhead to be flushed effectively during production to
remove dirt. A slow bleed of droplet fluids from one of the conduits 320 can
be used to remove air bubbles during printing, whilst a larger flow could be
induced during a pause in printing for maintenance purposes.
Each feature disclosed in this specification (which term includes the claims)
and/or shown in the drawings may be incorporated in the invention
independently of other disclosed and/or illustrated features.

WE CLAIM :
1. Droplet deposition apparatus comprising :
at least one droplet ejection unit comprising a plurality of fluid channels disposed
side by side in a row extending in a first direction, an actuator, and a plurality of nozzles,
each having a nozzle axis extending in a second direction orthogonal to the first direction,
said actuator being actuable to eject a droplet of fluid from a fluid channel through a
respective nozzle, said ejection unit having an end face extending in both said first and
second directions;
a support member 140 for said at least one droplet ejection unit; and
a conduit (150, 152) for conveying droplet fluid to each of the fluid channels of said at least
one droplet ejection unit; and
wherein interconnect/ means, 132 for electrically connecting said actuator means (118) to
drive circuit means 130 are formed on said end face.
2. Apparatus as claimed in claim 1, having a second conduit for conveying droplet
fluid away from each of the fluid channels of said at least one droplet ejection unit.
3. Apparatus as claimed in claim 2, having a plurality of droplet ejection units, said
conduits being adapted to convey droplet fluid to and from each of the fluid channels of
said plurality of droplet ejection units.
4. Apparatus as claimed in any of claims 1 to 3, wherein each said fluid channel has
a length extending in a third direction orthogonal to both said first and second directions.

5. Apparatus as claimed in any of the preceding claims, having a drive circuit for
supplying electrical signals to said actuator.
6. Apparatus as claimed in claim 5, wherein said drive circuit is in substantial thermal
contact with at least one of said conduits so as to transfer a substantial part of the heat
generated in said drive circuit means to said droplet fluid.
7. Apparatus as claimed in claim 6, wherein said drive circuit is mounted on said
support member, said support member being in thermal contact with at least one of said
conduits.
8. Apparatus as claimed in claim 7, wherein said drive circuit is mounted on said
support member so as to contact droplet fluid being conveyed by at least one of said
conduits.
9. Apparatus as claimed in claim 7, wherein said drive circuit is mounted on said
support member so as to be distant from droplet fluid being conveyed by at least one of
said conduits.
10. Apparatus as claimed in claim 9, wherein said support member comprises a
substantially U-shaped member, said drive circuit being mounted on at least one of the
two facing walls of the arms of the U-shaped member.
11. Apparatus as claimed in claim 5, having a third conduit for conveying a coolant
fluid, said drive circuit means being proximate said coolant conveying conduit so as to

transfer a substantial part of the heat generated in said drive circuit to said coolant fluid.
12. Apparatus as claimed in claim 11, wherein said drive circuit is mounted on said
support member, said support member being in thermal contact with said third conduit.
13. Apparatus as claimed in claim 12, wherein said third conduit comprises an
aperture formed in said support member.
14. Apparatus as claimed in claim 1, wherein there are provided a plurality of rows of
fluid channels, said droplet ejection units being arranged on said support member such
that at least some of the fluid channels of adjacent rows of fluid channels are substantially
co-axial.
15. Apparatus as claimed in claim 1, wherein there are provided two rows of fluid
channels, each row being arranged on a respective support member having a respective
conduit for conveying fluid to that row.
16. Apparatus as claimed in claim 15, wherein an additional conduit extends between
said support members for conveying droplet fluid away from said rows.
17. Apparatus as claimed in claim 4, wherein said support member has a dimension in
said third direction which is substantially equal to n x the length of a fluid channel in said
third direction, where n is the number of rows of channels.

Droplet deposition apparatus comprises at least one droplet ejection unit (302, 304) comprising a plurality of fluid
channels disposed side by side in a row, actuator means, and a plurality of nozzles, said actuator means being actuable to eject a
droplet of fluid from a fluid channel through a respective nozzle; a support member (300) for said at least one droplet ejection unit:
a first conduit (320) extending along said row and to one side of both said support member and said at least one droplet ejection
unit for conveying droplet fluid to each of the fluid channels of said at least one droplet ejection unit; and a second conduit (330)
extending along said row and to the other side of both said support member and said at least one droplet ejection unit for receiving
droplet fluid from each of the fluid channels of said at least one droplet ejection unit.

Documents:

IN-PCT-2002-837-KOL-CORRESPONDENCE.pdf

IN-PCT-2002-837-KOL-FORM 27.pdf

IN-PCT-2002-837-KOL-FORM-27.pdf

in-pct-2002-837-kol-granted-abstract.pdf

in-pct-2002-837-kol-granted-claims.pdf

in-pct-2002-837-kol-granted-correspondence.pdf

in-pct-2002-837-kol-granted-description (complete).pdf

in-pct-2002-837-kol-granted-drawings.pdf

in-pct-2002-837-kol-granted-examination report.pdf

in-pct-2002-837-kol-granted-form 1.pdf

in-pct-2002-837-kol-granted-form 18.pdf

in-pct-2002-837-kol-granted-form 2.pdf

in-pct-2002-837-kol-granted-form 3.pdf

in-pct-2002-837-kol-granted-form 5.pdf

in-pct-2002-837-kol-granted-gpa.pdf

in-pct-2002-837-kol-granted-reply to examination report.pdf

in-pct-2002-837-kol-granted-specification.pdf

in-pct-2002-837-kol-granted-translated copy of priority document.pdf

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Patent Number

228086

Indian Patent Application Number

IN/PCT/2002/837/KOL

PG Journal Number

05/2009

Publication Date

30-Jan-2009

Grant Date

28-Jan-2009

Date of Filing

21-Jun-2002

Name of Patentee

XAAR TECHNOLOGY LIMITED

Applicant Address

SCIENCE PARK, CAMBRIDGE CB4 0XR

Inventors:

#	Inventor's Name	Inventor's Address
1	DRURY PAUL RAYMOND	91 GARDEN WALK, ROYSTON, HERTS SG8 7NJ
2	CONDIE ANGUS	10 CAGE HILL, SWAFFHAM PRIOR, CAMBRIDGE CB5 OJS
3	ZABA JERZY MARCIN	56 MELVIN WAY, HISTON, CAMBRIDGE CB4 9HY

PCT International Classification Number

B41J 2/14

PCT International Application Number

PCT/GB2001/00050

PCT International Filing date

2001-01-05

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	00000368.1	2000-01-07	U.K.