(i2)Un1ted States Patent
`Silverbrook et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,428,142 B1
`Aug. 6, 2002
`
`US006428l42B1
`
`(54) FOUR COLOR MODULAR PRINTHEAD
`SYSTEM
`
`(56)
`
`References Cited
`U .s. PATENT DOCUMENTS
`
`(75)
`
`Inventors: Kia Silverhnmk, Balmain; Tobin Allen
`King, Cremorne; Garry Raymond
`Jackson, I-laberiield, all or(/\U)
`
`(73) Assignee: Silverbrook Research Pty Ltd,
`Balmain (AU)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.; 09/693,312
`
`(22)
`
`Filed:
`
`Oct. 20, 2000
`
`Foreign Application Priority Data
`(30)
`Dec. 9, 1999
`(AU) .......................................... .. PQ 4559
`
`Int. Cl.7 ............................................... .. B41] 2/155
`(51)
`(52) U.S. Cl.
`.......................................... .. 347/42; 347/13
`(58) Field of Search ............................ .. 347/13, 42, 12,
`347/40, 43, 49, 66
`
`1/1990 Newman cl 31.
`4?8g6:168 A
`3/1998 Haekleman ................ .. 347/42
`5,734,394 A *
`5/2000 Ornata el al.
`............... .. 347/12
`6,062,666 A *
`FOREIGN PATENT DOCUMENTS
`
`EP
`
`568175 A
`
`11/1993
`
`* cited by examiner
`
`Primary Examirzer—Lamson D. Nguyen
`
`(57)
`
`ABSTRACT
`
`Aprinthead system includes a plurality of printhead assen1-
`blies aligned in end—to—end relationship. Each printhead
`assembly includes a plurality of printhead modules,
`the
`printhead modules being arranged in end-to-end relationship
`and being angled with respect to a longitudinal axis of the
`assembly such that printhead chips of adjacent modules
`overlap in a direction transversely to a direction of move-
`ment of print media past the assemblies.
`
`9 Claims, 15 Drawing Sheets
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`FIG.7
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`FIG.5
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`FIG.4
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`FIG.6
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`FIG. 8
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`FIG. 9
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`FIG. 70
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`1
`FOUR COLOR MODULAR PRINTHEAD
`SYSTEM
`
`FIELD OF THE INVENTION
`
`This invention relates to a printhead assembly. More
`particularly,
`the invention relates to a pagewidth inkjet
`printhead assembly.
`SUMMARY OF THE INVENTION
`
`According to the invention there is provided a printhead
`system comprising: a plurality of printhead assemblies
`aligned in end—to—end relationship, each printhead assembly
`including a plurality of printhead modules wherein the
`printhead modules are arranged in end—to—end relationship
`and are angled with respect to a longitudinal axis of the
`assembly such that printhead chips of adjacent modules
`overlap in a direction transversely to a direction of n1ove-
`ment of print media past the assemblies.
`The printhead module at one end of each assembly may
`have a projecting portion which projects beyond an end of
`its assembly and the printhead module at the other end has
`a recessed portion to receive the projecting portion of the
`printhead module at said one end of an adjacent assembly.
`The printhead module may comprise a microelec-
`tromechanical printhead chip comprised of a number of
`inkjet nozzles, the nozzles of overlapping portions of adja-
`cent modules to be used being digitally selected.
`The angle of the printhead modules relative to the longi-
`tudinal axis of the assembly may be selected depending on
`a print pattern required. Each printhead module may have
`approximately 1587 dots per inch (dpi). To simulate 1600
`dpi printing the printheads may be angled at approximately
`7° to the longitudinal axis, more specifically 7.17°.
`Each assembly may include a chassis and an ink reservoir
`mounted on the chassis,
`the printhead modules of the
`assembly being attached to the ink reservoir. Preferably, the
`modules are releasably attached to the ink reservoir.
`The assembly may include an ink supply system for
`supplying ink to the reservoirs of each assembly.
`The chassis may be a rigid chassis for imparting torsional
`rigidity to each assembly.
`The ink reservoir of each assembly may have ink inlet
`nozzles at one end and sealable air bleeding openings at an
`opposed end.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention is now described by way of example with
`reference to the accompanying drawings in which:
`FIG. 1 shows a three dimensional view, from above, of a
`printhead assembly, in accordance with the invention;
`FIG. 2 shows a three dimensional view, from below, of the
`assembly;
`FIG. 3 shows a three dimensional, exploded View of the
`assembly;
`FIG. 4 shows a bottom view of the assembly;
`FIG. 5 shows a three dimensional view, from below, of the
`assembly with parts omitted;
`FIG. 6 shows, on an enlarged scale, an end view of the
`assembly;
`FIG. 7 shows, on the enlarged scale, a sectional end view
`of the assembly;
`FIG. 8 shows a three dimensional, exploded view of a
`printhead module of the assembly;
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`FIG. 9 shows a bottom view of the module;
`FIG. 10 shows a plan view of the module;
`FIG. 11 shows a sectional end view of the module taken
`along line XI—XI in FIG. 10;
`FIG. 12 shows a three dimensional, exploded view of an
`ink reservoir of the assembly;
`FIG. 13 shows a three dimensional view of a flexible
`printed circuit board of the assembly;
`FIG. 14 shows a three dimensional, exploded view of a
`busbar arrangement of the assembly;
`FIG. 15 shows a three dimensional view of a multiple
`printhead assembly configuration; and
`FIG. 16 shows, on an enlarged scale a sectional side view
`of the bonding of the printhead chip to the TAB film.
`DETAILED DESCRIPTION OF THE DRAWINGS
`
`In FIGS. 1 and 2, there is generally shown a printhead
`assembly, in accordance with a preferred embodiment of the
`invention. A printhead assembly 10 uses a plurality of
`replaceable printhead modules 12. The advantage of this
`arrangement is the ability to easily remove and replace any
`defective modules 12 in the assembly 10. This eliminates
`having to scrap an entire printhead assembly 10 if only one
`module 12 is defective.
`
`The assembly 10 comprises a chassis 14 on which an ink
`reservoir 16 is secured. The printhead modules 12 are, in
`turn, attached to the reservoir 16.
`Each printhead module 12 is comprised of a microelec-
`tromechanical (Memj et) chip 18 (shown in FIGS. 8 and 9 of
`the drawings) bonded by adhesive 20 to a Tape Automated
`Bond (TAB) film 22, the TAB film 22 being electrically
`connected to the chip 18. The chip 18 and the TAB film 22
`form a sub-assembly 24 which is attached to a micromolding
`26. The micromolding 26 is, in turn, supported on a cover
`molding 28.
`Each module 12 forms a sealed unit with four independent
`ink chambers 30 defined in the cover molding 28, the ink
`chambers 30 supplying ink to the chip 18. Each printhead
`module 12 is plugged into a reservoir molding 32 (shown
`most clearly in FIGS. 3 and 7 of the drawings) of the ink
`reservoir 16 that supplies the ink. Ten modules 12 butt
`together into the reservoir 16 to form a complete 8 inch
`printhead assembly 10. The ink reservoirs 16 themselves are
`modular, so complete 8 inch printhead arrays can be con-
`figured to form a printhead assembly 10 of a desired width.
`The 8 inch modular printhead assembly 10, according to
`the invention, is designed for a print speed and inkflow rate
`that allows up to 160 pages per minute printing at 1600 dpi
`photographic quality. Additionally, a second printhead
`assembly, of the same construction, can be mounted in a
`printer on the opposite side for double sided high speed
`printing.
`As described above, and as illustrated most clearly in FIG.
`8 of the drawings, at the heart of the printhead assembly 10
`is the Memjet chip 18. The TAB film 22 is bonded on to the
`chip 18 and is sealed with the adhesive 20 around all edges
`of the chip 18 on both sides. This forms the core Memjet
`printhead chip sub-assembly 24.
`The sub-assembly 24 is bonded on to the micromolding
`26. This molding 26 mates with the TAB film 22 which,
`together, form a floor 34 (FIG. 11) of the ink chambers 30
`of the cover molding 28. The chambers 30 open in a flared
`manner in a top 36 of the cover molding 28 to define filling
`funnels 38 as shown in FIGS. 10 and 11. A soft elastomeric,
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`hydrophobic collar 40 is arranged above each funnel 38. The
`collars 40 sealingly engage with complementary filling
`formations or nozzles 42 (FIG. 7) of the reservoir molding
`32 of the ink reservoir 16 to duct ink to the chip 18.
`Snap details or clips 44 project from the top 36 of the
`cover molding 28 to clip the cover molding 28 releasably to
`the ink reservoir 16, as shown in FIGS. 10 and 11.
`Tl1e TAB film 22 extends up an angled side wall 46 of the
`cover molding 28 where it is also bonded in place. The side
`wall 46 of the cover molding 28 provides the TAB film 22
`with a suitable bearing surface for data and power contact
`pads 48 (FIG. 8).
`The sub-assembly 24, the micromolding 26 and the cover
`molding 28 together form the Memjet printhead module 12.
`As shown in FIGS. 2 and 7 a plurality of these printhead
`modules 12 snap fit in angled, end—to—end relationship on to
`the ink reservoir 16. The reservoir 16 acts as a carrier for the
`modules 12 and provides ink ducts 52 (FIG. 7) for four ink
`colors, Cyan, Magenta, Yellow and blacK (CMYK). The
`four ink colors are channelled through the individual funnels
`38 of the cover molding 28 into each printhead module 12.
`The printhead modules 12 butt up to one another in an
`overlapping, angled fashion as illustrated most clearly in
`FIGS. 2 and 4 of the drawings. This is to allow the Memjet
`chips 18 to diagonally overlap in order to produce continu-
`ous printhead lengths from 0.8 inches to 72 inches (for wide
`format printers) and beyond.
`The Memjet chip 18 is 21.0 mm long x0.54 mm wide and
`0.3 mm high. A protective silicon nozzle shield that is 0.3
`mm high is bonded to the upper surface of the Memjet chip
`18.
`Each Memjet nozzle includes a thermoelastic actuator that
`is attached to a moving nozzle assembly. The actuator has
`two structurally independent layers of titanium nitride (TiN)
`that are attached to an anchor on the silicon substrate at one
`end and a silicon nitride (nitride) lever arm/nozzle assembly
`at the other end. The top TiN or “heater” layer forms an
`electrical circuit which is isolated fron1 the ink by nitride.
`The moving nozzle is positioned over an ink supply channel
`that extends through the silicon substrate. The ink supply
`channel
`is fluidically sealed around the substrate holes
`periphery by a TiN sealing rim. Ink ejection is prevented
`between the TiN rim and the nitride nozzle assembly by the
`action of surface tension over a 1 micron gap.
`A 1 microsecond 3 V, 27 mA pulse (85 nanoJoules) is
`applied to the terminals of the heater layer, increasing the
`heater temperature by Joule heating. The transient thermal
`field causes an expansion of the heater layer that is struc-
`turally relieved by an “out of plane” deflection caused by the
`presence of the other TiN layer.
`Deflection at the actuator tip is amplified by the lever arm
`and forces the nozzle assembly towards the silicon ink
`supply channel. The nozzle assembly’s movement combines
`with the inertia and viscous drag of the ink in the supply
`channel to generate a positive pressure field that causes the
`ejection of a droplet.
`Memjet actuation is caused by a transient thermal lield.
`The passive TiN layer only heats up by thermal conduction
`after droplet ejection. Thermal energy dissipates by thermal
`conduction into the substrate and the ink, causing the
`actuator to return to the ‘at rest’ position. Thermal energy is
`dissipated away from the printhead chip by ejected droplets.
`The drop ejection process takes around 5 microseconds. The
`nozzle refills and waste heat diffuses within 20 microsec-
`onds allowing a 50 KHz drop ejection rate.
`The Memjet chip 18 has 1600 nozzles per inch for each
`color. This allows true 1600 dpi color printing, resulting in
`
`4
`full photographic image quality. A 21 mm CMYK chip 18
`has 5280 nozzles. Each nozzle has a shift register, a transfer
`register, an enable gate, and a drive transistor. Sixteen data
`connections drive the chip 18.
`Some configurations of Memjet chips 18 require a nozzle
`shield. This nozzle shield is a micromachined silicon part
`which is wafer bonded to the front surface of the wafer. It
`protects the Memjet nozzles from foreign particles and
`contact with solid objects and allows the packaging opera-
`tion to be high yield.
`The TAB film 22 is a standard single sided TAB lllm
`comprised of polyimide and copper layers. A slot accom-
`modates the Memjet chip 18. The TAB lilm 22 includes gold
`plated contact pads 48 that connect with a flexible printed
`circuit board (PCB) 54 (FIG. 13) of the assembly 10 and
`busbar contacts 56 (FIG. 14) of busbars 58 and 60 of the
`assembly 10 to get data and power respectively to the chip
`18. Protruding bond wires are gold bumped, then bonded to
`bond pads of the Memjet chip 18.
`The junction between the TAB Film 22 and all the chip
`sidewalls has sealant applied to the front face in the first
`instance. The sub-assembly 24 is then turned over and
`sealant
`is applied to the rearjunction. This is done to
`completely seal the chip 18 and the TAB film 22 together to
`protect electrical contact because the TAB film 22 forms the
`floor 34 of the ink chambers 30 in the printhead module 12.
`The flexible PCB 54 is a single sided component that
`supplies the TAB films 22 of each printhead module 12 with
`data connections through contact pads, which interface with
`corresponding contacts 48 on each TAB film 22. The flex
`PCB 54 is mounted in abutting relationship with the TAB
`film 22 along the angled sidewall 46 of the cover molding
`28. The flex PCB 54 is maintained in electrical contact with
`the TAB film 22 of each printhead module 12 by means of
`a pressure pad 62 (FIG. 7). The PCB 54 wraps underneath
`and along a correspondingly angled sidewall 64 of the ink
`reservoir molding 32 of the ink reservoir 16. The part of the
`PCB 54 against the sidewall 64 carries a 62 pin connector
`66.
`The sidewall 64 of the ink reservoir molding 32 of the ink
`reservoir 16 is angled to correspond with the sidewall 32 of
`the cover molding 16 so that, when the printhead module 12
`is mated to the ink reservoir 16. The contacts 48 of the TAB
`film 22 wipe against those of the PCB 54. The angle also
`allows for easy removal of the module 12. The flex PCB 54
`is ‘sprung’ by the action of the deformable pressure pad 62
`which allows for positive pressure to be applied and main-
`tained between the contacts of the flex PCB 54 and the TAB
`film 22.
`The micromolding 26 is a precision injection molding
`made of an Acetal type material. It accommodates the Mem
`jet chip 18 (with the TAB film 22 already attached) and
`mates with the cover molding 28.
`Rib details 68 (FIG. 8) in the underside of the micro-
`molding 26 provide support for the TAB film 22 when they
`are bonded together. The TAB film 22 forms the floor 34 of
`the printhead module 12, as there is enough structural
`integrity due to the pitch of the ribs 68 to support a flexible
`film. The edges of the TAB film 22 seal on the underside
`walls of the cover molding 28.
`The chip 18 is bonded on to 100 micron wide ribs 70 that
`run the length of the micromolding 26. A channel 72 is
`defined between the ribs 70 for providing the final ink feed
`into the nozzles of the Memjet chip 18.
`The design of the micromolding 26 allows for a physical
`overlap of the Memjet chips 18 when they are butted in a
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`line. Because the Memjet chips 18 now form a continuous
`strip with a generous tolerance, they can be adjusted digi-
`tally to produce the required print pattern, rather than relying
`on very close tolerance moldings and exotic materials to
`perform the same function. The pitch of the modules 12 is
`20.33 mm.
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`The micromolding 26 fits inside the cover molding 28, the
`micromolding 26 bonding on to a set of vertical ribs 74
`extending from the top 36 of the cover molding 28.
`The cover molding 28 is a two shot, precision injection
`molding that combines an injected hard plastic body
`(Acetal) with soft elastomeric features (synthetic rubber).
`This molding interfaces with the sub-asscmbly 24 bonded to
`the micromolding 26. When bonded into place the base
`sub-asscmbly, comprising the sub-asscmbly 24 and thc
`micromolding 26, mates with the vertical ribs 74 of the
`cover molding 28 to form the scaled ink chambers 30.
`As indicated above, an opening of each chamber 30 is
`surrounded by one of the collars 40. These soft collars 40 are
`made of a hydrophobic, clastomcric compound that scals
`against the ink nozzles 42 of the ink reservoir 16. The snap
`fits 44 on the cover molding 28 locate the module 12 with
`respect to the ink reservoir 16.
`The ink reservoir 16 comprises the ink reservoir molding
`32 and a lid molding 76 (FIG. 7). The molding 32 is a simple
`four chamber injection molding with the lid molding 76 that
`is bonded on top to form a sealed environment for each color
`ink. Ink supply pipes 78 (FIG. 12) are arranged at one end
`of the lid molding 76 to communicate with ink channels 80
`defined in the reservoir molding 32. Labyrinthine, hydro-
`phobic air holes 82 are defined at an opposed end of the lid
`molding 76. The air holes 82 are included for bleeding the
`channels 80 during charging. These holes 82 are covered
`over with a self adhesive film 84 alter charging.
`The lid molding 76 has heat stakes 88, (pins that are
`designed to melt and hold the molding onto another part)
`wl1icl1 position and secure the ink reservoir 16 to the
`punched, sheet metal chassis 14. Additional heat stakes 90
`are arranged along the reservoir molding 32. These stakes
`are shown after deformation in FIG. 1 of the drawings once
`the ink reservoir 16 has been secured to the chassis 14.
`
`Receiving formations 92 are defined along the sides of the
`reservoir molding 32 for releasably receiving the clips 44 of
`the printhead modules 12.
`As previously described, the sidewall 64 on the side of the
`reservoir molding 32 provides a mounting area for the
`flexible PCB 54 and data connector 66. The reservoir
`molding 32 also carries details for facilitating the accurate
`mounting of the V— and V+ busbars 58 and 60, respectively.
`The metal chassis 14 as shown in FIG. 5 is a precision
`punched, folded and plated metal chassis used to mount the
`printhead assembly 10 into various products. The ink res-
`ervoir 16 is heat staked to the chassis 14 via the heat stakes
`88 and 90 as shown in FIG. 12. The chassis 14 includes a
`return cdgc 94 for mechanical strength. Thc chassis 14 can
`be easily customized for printhead mounting and any further
`part additions. It can also be extended in length to provide
`multiple arrays of printhc ad asscmblics 10 for wider format
`printcrs.
`Slots 97 are dcfincd in the chassis 14 for enabling acccss
`to be gained to the clips 44 of thc modules 12 to release the
`modules 12 from the ink reservoir 16 for enabling rcplacc-
`ment of one or more of the modules 12.
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`Thin finger strip metallic strip busbars 58 and 60 conduct
`V+ and V+, respectively,
`to the TAB film 22 on each
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`printhead module 12. The two busbars 58 and 60 are
`separated by an insulating strip 96 (FIG. 14). The flcxiblc,
`finger-like contacts 56 are arranged along one side edge of
`each busbar 58, 60. The contacts 56 electrically engage the
`relevant contact pads 48 of the TAB film 22 of each module
`12 for providing power to thc module 12. The contacts 56
`are separated by fine rib details on the underside of the ink
`reservoir molding 32.
`A busbar sub-assembly 98, comprising the busbars 58, 60
`and the insulating strip 96 is mounted on the underside of the
`sidewall 64 of the reservoir molding 32 of the ink reservoir
`16. The sub-assembly is held captive between that sidewall
`64 and the sidewall 46 of the cover molding 28 by the
`pressure pad 62.
`A single spade connector 100 is fixed to a protrusion 102
`on the busbar 58 for ground. Two spade connectors 104 are
`mounted on corresponding protrusions 106 on the busbar 60
`for power. The arrangement is such that, when the sub-
`assembly 98 is assembled, the spade connectors 104 are
`arranged on opposite sides of the spade connector 100. In
`this way, the likelihood of reversing polarity of the power
`supply to the assembly 10, when the assembly 10 is
`installed, is reduced. During printhead module 12 installa-
`tion or replacement, these are the first components to be
`disengaged, cutting power to the module 12.
`To assemble the printhead assembly 10, a Memjet chip 18
`is dry tested in flight by a pick and place robot, which also
`dices the wafer and transports individual chips 18 to a TAB
`film bonding area. When a chip 18 has been accepted, a TAB
`film 22 is picked, humped and applied to the chip 18.
`Referring to FIG. 16, a slot in the TAB film 22 that accepts
`the chip 18 and has the adhesive 20, which also functions as
`a sealant, applied to the upper and lower surfaces around the
`chip 18 on all sides. This operation forms a complete seal
`with the side walls of the chip 18. The connecting wires are
`potted during this process.
`The Memjet chip 18 and TAB film 22 sub-assembly 24 is
`transported to another machine containing a stock of n1icro—
`moldings 26 for placing and bonding. Adhesive is applied to
`the underside of the fine ribs 70 in the channel 72 of the
`micromolding 26 and the mating side of the underside ribs
`68 that lie directly underneath the TAB film 22. Tl1e sub-
`assembly 24 is mated with the micromolding 26.
`The micromolding sub-assembly, comprising the micro-
`molding 26 and the sub-assembly 24, is transported to a
`machine containing the cover moldings 28. When the micro-
`molding sub-assembly and cover molding 28 are bonded
`together, the TAB film 22 is sealed on to the underside walls
`of the cover molding 28 to form a sealed unit. The TAB film
`22 further wraps around and is glued to the sidewall 46 of
`the cover molding 28.
`The chip 18, TAB film 22, micromolding 26 and cover
`molding 28 assembly form a complete Memjet printhead
`module 12 with four sealed independent ink chambers 30
`and ink inlets 38.
`The ink reservoir molding 32 and the cover molding 76
`are bonded together to form a complete sealed unit. The
`sealing film 84 is placed partially over the air outlet holes 82
`so as not to completely seal the holes 82. Upon completion
`of the charging of ink into the ink reservoir 16, the holes 82
`are sealed by the film 84. The ink reservoir 16 is then placed
`and heat staked on to the metal chassis 14.
`The full length flexible PCB 54 with a cushioned adhesive
`backing is bonded to the angled sidewall 64 of the ink
`reservoir 16. The flcx PCB 54 tcrminatcs in the data con-
`nector 66, which is mounted on an external surface of the
`sidewall 64 of the ink reservoir 16.
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`US 6,428,142 B1
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`7
`Actuator V— and V+ connections are transmitted to each
`module 12 by the two identical metal finger strip busbars 58
`and 60. The busbar sub-assembly 98 is mounted above the
`flex PCB 54 on the underside of the sidewall 64 of the ink
`reservoir molding 32. The busbars 58, 60 and the insulating
`strip 96 are located relative to the ink reservoir molding 32
`via pins (not shown) projecting from the sidewall 64 of the
`ink reservoir molding 32, the pins being received through
`locating holes 108 in the busbars 58, 60 and the insulating
`strip 96.
`The Memjet printhead modules 12 are clipped into the
`overhead ink reservoir molding 32. Accurate alignment of
`the module 12 to the reservoir molding 32 is not necessary,
`as a complete printhead assembly 10 will undergo digital
`adjustment of each chip 18 during final QA testing.
`Each printhead module’s TAB film 22 interfaces with the
`flex PCB 54 and busbars 58, 60 as it is clipped into the ink
`reservoir 16. To disengage a printhead module 12 from the
`reservoir 16, a custom tool is inserted through the appro-
`priate slots 97 in the metal chassis 14 from above. The tool
`‘fingers’ slide down the walls of the ink reservoir molding
`32. where they contact the clips 44 of the cover molding 28.
`Further pressure acts to ramp the four clips 44 out of
`engagement with the receiving formations 92 and disengage
`the printhead module 12 from the ink reservoir 16.
`To charge the ink reservoir 16 with ink, hoses 110 (FIG.
`3) are attached to the pipes 78 and filtered ink from a supply
`is charged into each channel 80. The openings 82 at the other
`end of the ink reservoir cover molding 76 are used to bleed
`oll‘ air during priming.
`The openings 82 have tortuous ink paths that run across
`the surface, which connect
`through to the internal
`ink
`channels 80. These ink paths are partially sealed by the
`bonded transparent plastic 111m 84 during charging. The film
`84 serves to indicate when inks are in the ink channels 80,
`so they can be fully capped off when charging has been
`completed.
`1-‘or electrical connections and testing, power and data
`connections are made to the flexible PCB 54. Final testing
`then commences to calibrate the printhead modules 12.
`Upon successful completion of the testing,
`the Memjet
`printhead assembly 10 has a plastic sealing film applied over
`the underside that caps the printhead modules 12 and, more
`particularly, their chips 18, until product installation.
`It is to be noted that there is an overlap between adjacent
`modules 12. Part of the testing procedure determines which
`nozzles of the overlapping portions of the adjacent chips 18
`are to be used.
`
`on
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`10
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`toLA
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`I»on
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`40
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`As shown in FIG. 15 of the drawings, the design of the
`modular Memjet printhead assemblies 10 allows them to be
`butted together in an end-to-end configuration. It is therefore
`possible to build a multiple printhead system 112 in,
`effectively, unlimited lengths. As long as each printhead
`assembly 10 is fed with ink, then it is entirely possible to
`consider printhead widths of several hundred feet. This
`
`(11U:
`
`8
`me ans that the only width limit for a Memjet printer product
`is the maximum manufacturable size of the intended print
`media.
`
`FIG. 15 shows how a multiple Memjet printhead system
`112 could be configured for wide format printers. Replace-
`able ink cartridges 114, one for each color, are inserted into
`an intermediate ink reservoir 116 that always has a supply of
`filtered ink. Hoses 118 exit from the underside of the
`reservoir 118 and connect up to the ink inlet pipes 78 of each
`printhead assembly 10.
`It will be appreciated by persons skilled in the art that
`numerous variations and/or modifications may be made to
`the invention as shown in the specific embodiments without
`departing from the spirit or scope of the invention as broadly
`described. The present embodiments are, therefore, to be
`considered in all respects as illustrative and not restrictive.
`We claim:
`1. A printhead system comprising:
`a plurality of printhead assemblies aligned in end-to-end
`relationship,
`each printhead assembly including a plurality of printhead
`modules, wherein
`the printhead modules arranged in end-to-end relationship
`and are angled with respect to a longitudinal axis of the
`assembly such that printhead chips of adjacent modules
`overlap in a direction transversely to a direction of
`movement of print media past the assemblies.
`2. The system as claimed in claim 1 in wherein each
`printhead module has an abutting arrangement to overlap
`with an adjacent printhead module.
`3. The system as claimed in claim 2 in which each
`printhead module comprises a microelec—tromechanical
`printhead chip comprised of a number of inkjet nozzles, the
`nozzles of overlapping portions of adjacent modules to be
`used being digitally selected.
`4. The system as claimed in claim 1 in which the angle of
`the printhead modules relative to the longitudinal axis of the
`assembly is selected depending on a print pattern required.
`5. The system as claimed in claim 1 in which each
`assembly includes a chassis and an ink reservoir mounted on
`the chassis, the printhead modules of the assembly being
`attached to the ink reservoir.
`6. The system as claimed in claim 5 in which the modules
`are releasably attached to the ink reservoir.
`7. The system as claimed in claim 5 which includes an ink
`supply system for supplying ink to the reservoirs of each
`assembly.
`8. The system as claimed in claim 5 in which the chassis
`is a rigid chassis for imparting torsional rigidity to each
`assembly.
`9. The system as claimed in claim 5 in which the ink
`reservoir of each assembly has ink inlet nozzles at one end
`and scalable air bleeding openings at an opposed end.
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