(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`(43) International Publication Date
`29 November 2001 (29.11.2001)
`
`(10) International Publication Number
`
`WO 01/89849 A1
`
`(51) International Patent Classificationlz
`
`B4lJ 2/175
`
`(21) InternationalApplication Number:
`
`PCT/AU00/00594
`
`(22) International Filing Date:
`
`24 May 2000 (24.05.2000)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`(71) Applicant (far all designated Slales except US): SILVER-
`BROOK RESEARCH PTY. LTD. [AU/AU]; 393 Darling
`Street, Balmain, NSW 2041 (AU).
`
`(72) Inventor; and
`(75) Inventor/Applicant (/or US only): SILVERBROOK, Kia
`[AU/AU]; Silverbrook Research Pty. Ltd., 393 Darling
`Street, Balmain, NSW 2041 (AU).
`
`(74) Agent: SILVERBROOK, Kia; Silverbrook Research Pty.
`Ltd., 393 Darling Street, Balmain, NSW 2041 (AU).
`
`(81) Designated States (national): AE, AG, AL, AM, AT, AU,
`AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE,
`DK, DM, DZ, EE, ES, FT, GB, GD, GE, GH, GM, HR, HU,
`ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS,
`LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO,
`NZ, Pl., Pl‘, R(), RU, SD, SE, SG, SI, SK, SL, 'l‘.l, TM, TR,
`TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW.
`
`Designated States (regional): ARIPO patent (GH, GM,
`KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), Eurasian
`patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), European
`patent (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE,
`IT, LU, MC, NL, PT, SE), OAPI patent (BF, BJ, CF, CG,
`CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG).
`
`[Continued on next page]
`
`(54) Title: LAMINATED INK DISTRIBUTION ASSEMBLY FOR A PRINTER
`
`(57) Abstract: A laminated ink distribution structure for
`a printhead has a number of layers adhered to one another
`with each layer including a number of ink holes formed
`therethrough. Each ink hole has communicating there-
`with a channel formed in one side of the layer and allow-
`ing passage of ink to a transversely located position upon
`the layer, the transversely located position aligning with
`a slot formed through an adjacent layer of the laminate.
`The laminated ink distribution structure is fixed to a dis-
`tribution housing via which different inks are conveyed
`from an ink cassette. The laminated structure distributes
`the different inks to an array of print chips of a colour
`printer.
`
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`Published:
`— with international search report
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`For two-letter codes and other abbreviations, refer to the "Guid-
`ance Notes on Codes andAbbreviations ” appearing at the begin-
`ning ofeach regular issue ofthe PCT Gazette.
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`"LAMINATED INK DISTRIBUTION ASSEMBLY FOR A PRINTER"
`
`FIELD OF THE INVENTION
`
`This invention relates to an integrated movement sensor within a micro electro-mechanical (MEM) device.
`
`The invention has application in ink ejection nozzles ofthe type that are fabricated by integrating the technologies
`
`applicable to micro electro-mechanical systems (MEMS) and complementary meta|—oxide semiconductor (“CMOS”)
`
`integrated circuits, and the invention is hcreinafier described in the context ofthat application. However, it will be
`
`understood that the invention does have broader application, to a movement sensor within various types Of
`
`MEM devices.
`
`CO-PENDING APPLICATIONS
`
`Various methods, systems and apparatus relating to the present invention are disclosed in the following co-
`
`pending applications filed by the applicant or assignee of the present
`application:
`
`invention simultaneously with the present
`
`PCT/AU00/00518, PCT/AU00/O05 I9, PCT/AU00/00520, PCT/AUOO/0052], PCT/AU00/00522,
`
`PCT/AUO0/00523, PCT/AU00/00524, PCT/AU00/00525, PCT/AUOO/00526, PCT/AU00/00527,
`
`PCT/AUO0/00528, PCT/AU00/00529, PCT/AUOO/00530, PCT/AUO0/00531, PCT/AU00/00532,
`
`PCT/AUO0/00533, PCT/AU00/00534, PCT/AU00/00535, PCT/AUOO/00536, PCT/AUO0/00537,
`
`PCT/AUO0/00538, PCT/AUO0/00539, PCT/AU00/00540, PCT/AUOO/00541, PCT/AUOO/00542,
`
`PCT/AUO0/00543, PCT/AUOO/00544, PCT/AUOO/00545, PCT/AU00/00547, PCT/AU00/00546,
`
`PCT/AU00/00554, PCT/AUO0/00556, PCT/AUOO/00557, PCT/AU00/00558, PCT/AU00/00559,
`
`PCT/AUO0/00560, PCT/AU00/00561, PCT/AUOO/00562, PCT/AU00/00563, PCT/AUO0/00564,
`
`PCT/AUO0/00565, PCT/AU00/00566, PCT/AU00/00567, PCT/AU00/00568, PCT/AUO0/00569,
`
`PCT/AU00/00570, PCT/AU00/00571, PCT/AU00/00572, PCT/AU00/00573, PCT/AU00/00574,
`
`PCT/AU00/00575, PCT/AU00/00576, PCT/AUOO/00577, PCT/AUO0/00578, PCT/AU00/00579,
`
`PCT/AU00/0058i, PCT/‘AUOO/00580, PCT/AUOO/00582, PCT/AU00/00587, PCT/AU00/00588,
`
`PCT/AU00/00589, PCT/AU00/00583, PCT/AUO0/00593, PCT/AU00/00590, PCT/AU00/0059],
`
`PCT/AU00/00592, PCT/AU00/00584, I-‘CT/AUO0/00585, PCT/AU00/00586, PCT/AU00/00594,
`
`PCT/AU00/00595, PCT/AUOO/00596, PCT/AU00/00597, PCT/AU00/00598, PCT/AUOO/00516,
`
`PCT/AU00/00517, PCT/AUOO/0051 I, PCT/AU00/0050l, PCT/AU00/00502, PCT/AU00/00503,
`
`PCT/AU00/00504, PCT/AU00/00505, PCT/AUO0/00506, PCT/AUO0/00507. PCT/AU00/00508,
`
`PCT/AU00/00509, PCT/AU00/00510, PCT/AU00/005l2, PCT/AU00/00513, PC'l‘/AU00/00514,
`PCT/AUO0/00515
`
`The disclosures ofthese co-pending applications are incorporated herein by cross-reference.
`
`BACKGROUND OF THE INVENTION
`
`The following invention relates to a laminated ink distribution structure for a printer.
`
`More particularly, though not exclusively, the invention relates to a laminated ink distribution structure and
`
`assembly for an A4 pagewidth drop on demand printhead capable of printing up to l6(l0 dpi photographic quality at up to
`160 pages per minute.
`
`RECTIFIED SHEET
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`The overall design ofa primer in which the structure/assembly can be utilized revolves around the use of
`
`replaceable printhead modules in an array approximately 8 inches (20 cm) long. An advantage of such a system is the
`ability to easilyiremove and replace any defective modules in a printhead array. This would eliminate having to scrap an
`entire printhead if only one chip is defective.
`
`A printhead module in such a printer can be comprised ofa “Memjet” chip, being a chip having mounted
`
`thereon a vast number ofthermo-actuators in micro-mechanics and micro-electromechanical systems (MEMS). Such
`
`actuators might be those as disclosed in U.S. Paten1No. 6,044,646 to the present applicant, however, there might be other
`MEMS print chips.
`
`The printhead, being the environment within which the laminated ink distribution housing ofthe present
`
`invention is to be situated, might typically have six ink chambers and be capable of printing four color process (CMYK)
`
`as well as infra-red ink and fixative. An air pump would Supply filtered air to the printhead, which could be used to keep
`
`foreign particles away from its ink nozzles. The printhead module is typically to be connected to a replaceable cassette
`
`which contains the ink supply and an air filter.
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`Each printhead module receives ink via a distribution molding that transfers the ink. Typically, ten modules butt
`
`together to form a complete eight inch printhead assembly suitable for printing A4 paper without the need for scanning
`
`movement of the printhead across the paper width.
`
`The pxintheads themselves are modular, so complete eight inch printhead arrays can be configured to fomr
`
`printheads of arbitrary width.
`
`Additionally, a second printhead assembly can be mounted on the opposite side of a paper feed path to enable
`
`double-sided high speed
`
`OBJECTS OF THE INVENTION
`
`It is an object of the present invention to provide an ink distribution assembly for a printer.
`
`It is another object of the present invention to provide an ink distribution structure suitable for the pagewidth
`printhead assembly as broadly described herein
`
`It is another object of the present invention to provide a laminated ink distribution assembly for a printhead
`
`assembly on which there is mounted a plurality of print chips, each comprising a plurality of MEMS printing devices.
`
`It is yet another object of the present invention to provide a method of distributing ink to print chips in a
`
`printhead assembly of a printer.
`
`SUMMARY OF TI-IE INVENTION
`
`The present invention provides an ink distribution assembly for a printlread to which there is mounted an array
`
`of print chips, the assembly serving to distribute different inks from respective ink sources to each said print chip for
`
`printing on a sheet, the assembly comprising:
`
`a longitudinal disuibution housing having a duct for each said different ink extending longitudinally therealong,
`a cover having an ink inlet port corresponding to each said duct for connection to each said ink source and for
`
`delivering said ink from each said ink source to a respective one of said ink ducts, and
`
`a laminated ink distribution structure fixed to said distribution housing and distributing ink from said ducts to
`
`said print chips.
`
`Preferably the lanrinatcd ink distribution structure includes multiple layers situated one upon another with- at
`
`least one of said layers having a plurality of ink holes therethrough, each ink hole conveying ink from one of said ducts
`
`enroute to one of said print chips.
`
`Preferably one or more of said layers includes ink slots therethrough, the slots conveying ink from one or more
`
`of said ink holes in an adjacent layer enroute to one of said print chips.
`
`Preferably, the slots are located with ink holes spaced laterally to either side thereof.
`
`Preferably the layers of the laminated structu.re sequenced from the distribution housing to the array of print
`chips include fewer and fewer said ink holes.
`
`Preferably one or more of said layers includes recesses in the underside thereof communicating with said holes
`
`and transferring ink therefrom transversely between the layers enroute to one of said slots.
`
`Preferably the channels extend from the holes toward an inner portion of the laminated structure over the array
`
`of print chips, which inner portion includes said slots.
`
`Preferably each layer of the laminated is a micro-molded plastics layer.
`Preferably, the layers are adhered to one another.
`
`Preferably, the slots are parallel with one another.
`
`Preferably, at least two adjacent ones of said layers have an array of aligned air holes therethrough.
`
`The present invention also provides a laminated ink distribution structure for a printhead, the structure
`
`comprising:
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`a number of layers adhered to one another, each layer including a plurality of ink holes formed therethrough,
`
`each ink hole having communicating therewith a recess formed in one side of the layer and allowing passage of ink to a
`
`transversely located position upon the layer, which transversely located position aligns with a slot formed through an
`
`adjacent layer.
`
`Preferably the slot in any layer of the structure is aligned with another slot in an adjacent layer of the structure
`
`and the aligned slots are aligned with a respective print chip slot formed in a final layer of the structure.
`
`Preferably the layers are micro-molded plastics layers.
`
`The present invention also provides a method of distributing ink to an array of print chips in a printhead
`
`assembly, the method serving to distribute different inks from respective ink sources to each said print chip for printing on
`
`a sheet, the method comprising:
`
`supplying individual sources of ink to a longitudinal distribution molding having a duct for each said different
`
`ink extending longitudinally therealong,
`
`causing ink to pass along the individual ducts for distribution thereby into a laminated ink distribution structure
`fixed to the distribution housing, wherein
`I
`the laminated ink distribution structure enables the passage therethrough of the individual ink supplies to the
`
`print chips, which print chips selectively eject the ink onto a sheet.
`
`The present invention also provides a method of distributing ink to print chips in a printhead assembly of a
`
`printer, the method utilizing a laminated ink distributing structure formed as a number of micro-molded layers adhered to
`
`one another with each layer including a plurality of ink holes formed therethrough, each ink hole communicating with a
`
`channel formed in one side of a said layer and allowing passage of ink to a transversely located position within the
`
`structure, which transversely located position aligns with an aperture formed through an adjacent layer of the laminated
`
`structure, an adjacent layer or layers of the laminated structure also including slots through which ink passes to the print
`
`chips.
`
`As used herein, the term “ink” is intended to mean any fluid which flows through the printhead to be delivered
`
`to a sheet. The fluid may be one of many different coloured inks, infra-red ink, a fixative or the like.
`BRIEF DESCRJPTION OF THE DRAWINGS
`
`A preferred form of the present invention will now be described by way of example with reference to the
`
`accompanying drawings wherein:
`
`Fig. I is a front perspective View of a print engine assembly
`
`Fig. 2 is a rear perspective view of the print engine assembly of Fig. 1
`
`Fig. 3 is an exploded perspective View of the print engine assembly of Fig. 1.
`
`Fig. 4 is a schematic front perspective view of a printhead assembly.
`
`Fig. 5 is a rear schematic perspective view ofthe printhead assembly ofFig. 4.
`
`Fig. 6 is an exploded perspective illustration of the printhead assembly.
`
`Fig. 7 is a cross-sectional end elevational View of the printhead assembly of Figs. 4 to 6 with the section taken
`
`through the centre of the printhead.
`
`Fig. 8 is a schematic cross-sectional end elevational view of the printhead assembly of Figs. 4 to 6 taken near
`the left end ofFig. 4.
`
`Fig. 9A is a schematic end elevational view of mounting of the print chip and nozzle guard in the laminated
`
`40
`
`stack structure of the printhead
`Fig. 9B is an enlarged end elevational cross section ofFig 9A
`Fig. 10 is an exploded perspective illustration of a printhead cover assembly.
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`Fig. 11 is a schematic perspective illustration of an ink distribution molding.
`
`Fig. 12 is an exploded perspective illustration showing the layers forming part of a laminated ink distribution
`
`structure according to the present invention.
`
`- 4 -
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`'
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`'
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`'
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`. 13 is a stepped sectional view from above of the structure depicted in Figs. 9A and 9B,
`
`. 14 is a stepped sectional view from below of the structure depicted in Fig. 13.
`
`. 15 is a schematic perspective illustration of a first laminate layer.
`
`. 16 is a schematic perspective illustration of a second laminate layer.
`
`. 17 is a schematic perspective illustration of a third laminate layer.
`
`. 18 is a schematic perspective illustration of a fourth laminate layer.
`
`. 19 is a schematic perspective illustration of a fifth laminate layer.
`
`. 20 is a perspective View of the air valve molding
`. 21 is a rear perspective view of the right hand end of the platen
`
`. 22 is a rear perspective view of the left hand end of the platen
`
`. 23 is an exploded view of the platen
`
`Fig. 24 is a transverse cross-sectional view of the platen
`
`Fig. 25 is a front perspective view of the optical paper sensor arrangement
`
`Fig. 26 is a schematic perspective illustration of a printhead assembly and ink lines attached to an ink reservoir
`cassette.
`
`Fig. 27 is a partly exploded view of Fig. 26.
`DETAILED DESCRIPTION OF THE INVENTION
`
`In Figs. 1 to 3 of the accompanying drawings there is schematically depicted the core components of a print
`
`engine assembly, showing the general environment in which the laminated ink distribution structure of the present
`
`invention can be located. The print engine assembly includes a chassis 10 fabricated from pressed steel, alurniniurn,
`
`plastics or other rigid material. Chassis 10 is intended to be mounted within the body of a printer and serves to mount a
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`printhead assembly 11 , a paper feed mechanism and other related components within the external plastics casing of a
`
`printer.
`
`In general terms, the chassis 10 supports the printhead assembly 11 such that ink is ejected therefrom and onto a
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`sheet of paper or other print medium being transported below the printhead then through exit slot 19 by the feed
`
`mechanism The paper feed mechanism includes a feed roller 12, feed idler rollers 13, a platen generally designated as 14,
`
`exit rollers 15 and a pin wheel assembly 16, all driven by a stepper motor 17. These paper feed components are mounted
`
`between a pair of bearing moldings 18, which are in mm mounted to the chassis 10 at each respective end thereof.
`
`A printhead assembly 11 is mounted to the chassis 10 by means of respective printhead spacers 20 mounted to
`
`the chassis 10. The spacer moldings 20 increase the printhead assembly length to 220mm allowing clearance on either
`
`side of 210mm wide paper.
`
`The printhead construction is shown generally in Figs. 4 to 8.
`
`The printhead assembly 11 includes a printed circuit board (PCB) 21 having mounted thereon various electronic
`
`components including a 64 MB DRAM 22, a PEC chip 23, a QA chip connector 24, a microcontroller 25, and a dual
`
`motor driver chip 26. The printhead is typically 203mm long and has ten print chips 27 (Fig. 13), each typically 21mm
`
`long. These print chips 27 are each disposed at a slight angle to the longitudinal axis of the printhead (see Fig. 12 ), with a
`
`slight overlap between each print chip which enables continuous transmission of ink over the entire length of the array.
`Each print chip 27 is electronically connected to an end of one ofthe tape automated bond (TAB) films 28, the other end
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`of which is maintained in electrical contact with the undersurface of the printed circuit board 21 by means of a TAB film
`
`backing pad 29.
`
`The preferred print chip construction is as described in US Patent No 6,044,646 by the present applicant. Each
`
`such print chip 27 is approximately 21mm long, less than lmm wide and about 0.3mm high, and has on its lower surface
`
`thousands of MEMS irikjet nozzles 30, shown schematically in Figs. 9A and 9B, arranged generally in six lines - one for
`
`each ink type to be applied. Each line of nozzles may follow a staggered pattern to allow closer dot spacing. Six
`
`corresponding lines of ink passages 31 extend through from the rear of the print chip to transport ink to the rear of each
`
`nozzle. To protect the delicate nozzles on the surface of the print chip each print chip has a nozzle guard 43, best seen in
`
`Fig. 9A, with microapertures 44 aligned with the nozzles 30, so that the ink drops ejected at high speed from the nozzles
`
`pass through these rnicroapatures to be deposited on the paper passing over the platen 14.
`
`Ink is delivered to the print chips via a distribution molding 35 and laminated stack 36 arrangement forming part
`
`of the printhead ll. Ink from an ink cassette 37 (Figs. 26 and 27) is relayed via individual ink hoses 38 to individual ink
`
`inlet ports 34 integrally molded with a plastics duct cover 39 which forms a lid over the plastics distribution molding 35.
`
`The distribution molding 35 includes six individual longitudinal ink ducts 40 and an air duct 41 which extend throughout
`the length of the array. Ink is transferred from the inlet ports 34 to respective ink ducts 40 via individual cross—flow ink
`
`channels 42, as best seen with reference to Fig. 7. It should be noted in this regard that although there are six ducts
`
`depicted, a different number of ducts might be provided. Six ducts are suitable for a printer capable of printing four color
`
`process (CMYK) as well as infra-red ink and fixative.
`
`Air is delivered to the air duct 41 via an air inlet port 61, to supply air to each print chip 27, as described later
`with reference to Figs. 6 to 8, 20 and 2].
`
`Situated within a longitudinally extending stack recess 45 formed in the underside of distribution molding 35 are
`
`a number of laminated layers forming a laminated ink distribution stack 36. The layers of the laminate are typically
`
`formed of micro-molded plastics material. The TAB film 28 extends from the undersurface of the printhead PCB 21,
`
`around the rear of the distribution molding 35 to be received within a respective TAB film recess 46 (Fig. 21), a number
`
`of which are situated along a chip housing layer 47 of the laminated stack 36. The TAB film relays electrical signals from
`
`the printed circuit board 21 to individual print chips 27 supported by the laminated structure.
`
`The distribution molding, laminated stack 36 and associated components are best described with reference to
`
`Figs. 7 to 19.
`
`Fig. 10 depicts the distribution molding cover 39 formed as a plastics molding and including a number of
`
`positioning spigots 48 which serve to locate the upper printhead cover 49 thereon.
`
`As shown in Fig. 7, an ink transfer port 50 connects one of the ink ducts 39 (the fourth duct from the left) down
`
`to one of six lower ink ducts or transitional ducts 51 in the underside of the distribution molding. All of the ink ducts 40
`
`have corresponding transfer ports 50 communicating with respective ones of the transitional ducts 51. The transitional
`
`ducts 51 are parallel with each other but angled acutely with respect to the ink ducts 40 so as to line up with the rows of
`
`ink holes of the first layer 52 of the laminated stack 36 to be described below.
`
`The first layer 52 incorporates twenty four individual ink holes 53 for each of ten print chips 27. That is, where
`
`ten such print chips are provided, the first layer 52 includes two hundred and forty ink holes 53. The first layer 52 also
`
`includes a row of air holes 54 alongside one longitudinal edge thereof.
`
`The individual groups of twenty four ink holes 53 are formed generally in a rectangular array with aligned rows
`
`of ink holes. Each row of four ink holes is aligned with a transitional duct 51 and is parallel to a respective print chip.
`The undersurface of the first layer 52 includes underside recesses 55. Each recess 55 communicates with one of
`
`the ink holes of the two centre-most rows of four holes 53 (considered in the direction transversely across the layer 52).
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`That is, holes 53a (Fig. 13) deliver ink to the right ha.nd recess 55a shown in Fig. 14, whereas the holes 53b deliver ink to
`
`the left most underside recesses 55b shown in Fig. 14.
`
`The second layer 56 includes a pair of slots 57, each receiving ink from one of the underside recesses 55 of the
`
`first layer.
`
`The second layer 56 also includes ink holes 53 which are aligned with the outer two sets of ink holes 53 ofthe
`
`first layer 52. That is, ink passing through the outer sixteen ink holes 53 of the first layer 52 for each print chip pass
`
`directly through corresponding holes 53 passing through the second layer 56.
`
`The underside of the second layer 56 has formed therein a number of transversely extending channels 58 to
`
`relay ink passing through ink holes 53c and 53d toward the centre. These channels extend to align with a pair of slots 59
`
`formed through a third layer 60 of the laminate. It should be noted in this regard that the third layer 60 of the laminate
`
`includes four slots 59 corresponding with each print chip, with two irmer slots being aligned with the pair of slots formed
`
`in the second layer 56 and outer slots between which the irmer slots reside.
`
`The third layer 60 also includes an array of air holes 54 aligned With the corresponding air hole arrays 54
`
`provided in the first and second layers 52 and 56.
`
`The third layer 60 has only eight remaining ink holes 53 corresponding with each print chip. These outermost
`
`holes 53 are aligned with the outermost holes 53 provided in the first and second laminate layers. As shown in Figs. 9A
`
`and 9B, the third layer 60 includes in its underside surface a transversely extending channel 61 corresponding to each hole
`
`53. These channels 6] deliver ink from the corresponding hole 53 to a position just outside the alignment of slots 59
`
`therethrough.
`
`As best seen in Figs. 9A and 9B, the top three layers of the laminated stack 36 thus serve to direct the ink
`
`(shown by broken hatched lines in Fig. 9B) from the more widely spaced ink ducts 40 of the distribution molding to slots
`aligned with the ink passages 31 through the upper surface of each print chip 27.
`
`As shown in Fig. 13, which is a view from above the laminated stack, the slots 57 and 59 can in fact be
`
`comprised of discrete co-linear spaced slot segments.
`
`The fourth layer 62 of the laminated stack 36 includes an array of ten chip-slots 65 each receiving the upper
`
`portion of a respective print chip 27.
`
`The fifth and final layer 64 also includes an array of chip-slots 65 which receive the chip and noule guard
`
`assembly 43.
`
`The TAB film 28 is sandwiched between the fourth and fifih layers 62 and 64, one or both of which can be
`
`provided with recesses to accommodate the thickness of the TAB film.
`
`The laminated stack is formed as a precision n1icro-molding, injection molded in an Acetal type material. It
`
`accommodates the array ofprint chips 27 with the TAB film already attached and mates with the cover molding 39
`described earlier.
`
`Rib details in the underside of the rnicro-molding provides support for the TAB film when they are bonded
`
`together. The TAB film forms the underside wall of the printhead module, as there is sufficient structural integrity
`
`between the pitch of the ribs to support a flexible film. The edges of the TAB film seal on the underside wall of the cover
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`molding 39. The chip is bonded onto one hundred micron wide ribs that run the length of the micro-molding, providing a
`final ink feed to the print nozzles.
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`The design of the micro-molding allow for a physical overlap of the print chips when they are butted in a line.
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`Because the printhead chips now form a continuous strip with a generous tolerance, they can be adjusted digitally to
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`produce a near perfect print pattern rather than relying on very close toleranced moldings and exotic materials to perform
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`the same flmction. The pitch of the modules is typically 20.33mm.
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`_ 7 _
`The individual layers of the laminated stack as Well as the cover molding 39 and distribution molding can be
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`glued or otherwise bonded together to provide a sealed unit. The ink paths can be sealed by a bonded transparent plastic
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`film serving to indicate when inks are in the ink paths, so they can be fully capped off when the upper part of the adhesive
`fihn is folded over. Ink charging is then complete.
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`The four upper layers 52, 56, 60, 62 of the laminated stack 36 have aligned air holes 54 which communicate
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`with air passages 63 formed as charmels formed in the bottom surface of the fourth layer 62, as shown in Figs. 9b and 13.
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`These passages provide pressurised air to the space between the print chip surface and the nozzle guard 43 Whilst the
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`printer is in operation. Air from this pressurised zone passes through the micro-apertures 44 in the nozzle guard, thus
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`preventing the build-up of any dust or unwanted contaminants at those apertures. This supply of pressurised air can be
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`turned off to prevent ink drying on the nozzle surfaces during periods of non-use of the printer, control of this air supply
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`being by means of the air valve assembly shown in Figs. 6 to 8, 20 and 21.
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`With reference to Figs. 6 to 8, within the air duct 41 of the printhead there is located an air valve molding 66
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`formed as a channel with a series of apertures 67 in its base. The spacing of these apertures corresponds to air passages 68
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`fonned in the base of the air duct 41 (see Fig. 6), the air valve molding being movable longitudinally within the air duct so
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`that the apertures 67 can be brought into alignment with passages 68 to allow supply the pressurized air through the
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`laminated stack to the cavity between the print chip and the male guard, or moved out of alignment to close off the air
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`supply. Compression springs 69 maintain a sealing inter-engagernent of the bottom of the air valve molding 66 with the
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`base of the air duct 41 to prevent leakage when the valve is closed.
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`The air valve molding 66 has a cam follower 70 extending from one end thereof, which engages an air valve
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`cam surface 71 on an end cap 74 of the platen 14 so as to selectively move the air valve molding longitudinally within the
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`air duct 41 according to the rotational positional of the multi-fimction platen 14, which may be rotated between printing,
`capping and blotting positions depending on the operational status of the printer, as will be described below in more detail
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`with reference to Figs. 21 to 24. When the platen 14 is in its rotational position for printing, the cam holds the air valve in
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`its open position to supply air to the print chip surface, whereas when the platen is rotated to the non-printing position in
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`which it caps off the micro-apertures of the nozzle guard, the cam moves the air valve molding to the valve closed
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`position.
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`With reference to Figs. 21 to 24, the platen member 14 extends parallel to the printhead, supported by a rotary
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`shaft 73 mounted in bearing molding 18 and rotatable by means of gear 79 (see Fig. 3). The shafi is provided with a right
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`hand end cap 74 and left hand end cap 75 at respective ends, having cams 76, 77.
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`The platen member 14 has a platen surface 78, a capping portion 80 and an exposed blotting portion 81
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`extending along its length, each separated by 120°. Dining printing, the platen member is rotated so that the platen surface
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`78 is positioned opposite the printhead so that the platen surface acts as a support for that portion of the paper being
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`printed at the time. When the printer is not in use, the platen member is rotated so that the capping portion 80 contacts the
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`bottom of the printhead, sealing in a locus surrounding the microapertures 44. This, in combination with the closure of the
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`air valve by means of the air valve arrangement when the platen 14 is in its capping position, maintains a closed
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`atmosphere at the print nozzle surface. This serves to reduce evaporation of the ink solvent (usually water) and thus
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`reduce drying of ink on the print nozzles while the printer is not in use.
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`The third ftmetion of the rotary platen member is as an ink blotter to receive ink from priming of the print
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`nozzles at printer start up or maintenance operations of the printer. During this printer mode, the platen member 14 is
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`rotated so that the exposed blotting portion 81 is located in the ink ejection path opposite the nozzle guard 43. The
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`exposed blotting portion 81 is an exposed part of a body of blotting material 82 inside the platen member 14, so that the
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`ink received on the exposed portion 81 is drawn into the body of the platen member.
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`Further details of the platen member construction may be seen from Figs. 23 and 24. The platen member
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`consists generally ofan extruded or molded hollow platen body 83 which forms the platen surface 78 and receives the
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`shaped body of blotting material 82 of which a part projects through a longitudinal slot in the platen body to form the
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`exposed blotting surface 81. A flat portion 84 of the platen body 83 serves as a base for attachment of the capping
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`member 80, which consists of a cappfl housing 85, a capper seal member 86 and a foam member 87 for contacting the
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`nozzle guard 43.
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`With reference again to Fig. 1, each bearing molding 18 rides on a pair of vertical rails 101. That is, the capping
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`assembly is mounted to four vertical rails 101 enabling the assembly to move vertically. A spring 102 under either end of
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`the capping assembly biases the assembly into a raised position, maintaining cams 76,77 in contact with the spacer
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`projections 100.
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`The printhead 11 is capped when not is use by the fiill-width capping member 80 using the elastomeric (or
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`similar) seal 86. In order to rotate the platen assembly l4, the main roller drive motor is reversed. This brings a reversing
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`gear into contact with the gear 79 on the end of the platen assembly and rotates it into one of its three functional positions,
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`each separated by 120°.
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`The earns 76, 77 on the platen end caps 74, 75 co-operate with projections 100 on the respective printhead
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`spacers 20 to control the spacing between the platen member and the printhead depending on the rotary position of the
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`platen member. In this ma