(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`l|l||||ll||||||l||||||||||||l||lll||ll|||||||||l||||l|||||l||l|l|I||||||||||||||
`
`(43) International Publication Date
`11 January 2001 (11.01.2001)
`
`(10) International Publication Number
`
`PCT
`
`WO 01/02172 A1
`
`(51) International Patent Classilication7:
`2/14, 2/175
`
`B4lJ 2/01,
`
`(21) International Application Number:
`
`PCT/AU00/00753
`
`(22) International Filing Date:
`
`30 June 2000 (30.06.2000)
`
`(72) Inventors; and
`(75) Inventors/Applicants (for US only): SILVERBROOK,
`Kia [AU/AU]; Silverbrook Research Pty Ltd. 393 Darling
`Street, Balmain, NSW 2041 (AU). KING, Tobin, Allen
`[AU/AU]; Unit 2, 125 Cremome Road, Cremome, NSW
`2090 (AU).
`
`English
`
`English
`
`SILVERBROOK RE-
`Common Representative:
`SEARCH PTY LTD; 393 Darling Street, Balmain, NSW
`2041 (AU).
`
`Designated States (national): AE, AG, AL, AM, AT, AU,
`AZ. BA, BB, BG. BR, BY, BZ, CA, CH, CN, CR, CU, CZ,
`DE, DK, DM, DZ, EE, ES, FI, 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, M2,
`NO, NZ, PL, PT, RO. RU, SD, SE, SG, SI, SK, SL, TJ, TM,
`TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW.
`
`[Continued on next page]
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`(30) Priority Data:
`PQ 1304
`PQ 1305
`PQ 1306
`
`30 June 1999 (30.06.1999)
`30 June 1999 (30.06.1999)
`30 June 1999 (30.06.1999)
`
`AU
`AU
`AU
`
`Applicant (for all designated States except US): SILVER-
`BROOK RESEARCH PTY LTD [AU/AU]; 393 Darling
`Street, Balmain, NSW 2041 (AU).
`
`(54) Title: PRINTHEAD SUPPORT STRUCTURE AND ASSEMBLY
`
`(57) Abstract: An inkjet printhead assembly (1) includes a hollow
`elongate member (10) having at least one ink supply channel (14)
`formed therein, the or each ink supply channel (14) being in fluid
`communication with an elongate slot (21) in and extending at least
`partly along the elongate member (10). A plurality of printhead seg-
`ment cartiers (8) is received and secured in neighbouring arrangement
`within the slot (21), and at least one printhead segment (4) is mounted
`to each printhead segment carrier (8). Each printhead segment carrier
`(8) includes at least one ink gallery (92) arranged so as to connect
`the or an associated one of said ink supply channels (14) with an ink
`inlet (41) of the at least one printhead segment (4) mounted to that
`printhead segment carrier (8). The inkjet printhead segments (4) are
`both conveniently supported in the elongate member (10) and sup-
`plied with ink, and their printing ranges may overlap longitudinally.
`
`WO01/02172A1
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`Published:
`(84) Designated States (regional): ARIPO patent (GH, GM,
`KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), Eurasian — With international search report.
`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).
`
`For two—lener codes and other abbreviations. refer to the "Guid-
`ance Notes on Codes and Abbreviations " appearing at the begin-
`ning ofeach regular issue of the PCT Gazette.
`
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`PCT/AU00/00753
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`-1-
`
`PRINTHEAD SUPPORT STRUCTURE AND ASSEMBLY
`
`Field of the Invention
`
`This invention relates to the field of ink jet printing systems, and more specifically to a support structure
`
`and ink supply arrangement for a printhead assembly and such printhead assemblies for inkjet printing systems.
`
`Description of the Prior Art
`
`fabricated using standard VLSI semi-conductor chip
`Micro-electromechanical systems ("MEMS"),
`fabrication techniques, are becoming increasingly popular as new applications are developed. Such devices are
`
`becoming widely used for sensing (for example accelerometers for automotive airbags),
`
`inkjet printing, micro-
`
`fluidics, and other applications. The use of semi-conductor fabrication techniques allows MEMS to be interfaced
`
`very readily with microelectronics. A broad survey of the field and of prior art in relation thereto is provided in an
`
`article entitled “The Broad Sweep of Integrated Micro-Systems", by S. Torn Picraux and Paul McWhorter, in IEEE
`
`Spectrum, December 1998, pp24-33.
`
`in PCT Application No. PCT/AU98/00550, the entire contents of which is incorporated herein by reference,
`
`an inkjet printing device has been described which utilizes MEMS processing techniques in the construction of a
`therrnal-bend—actuator-type device for the ejection of a fluid, such as an ink, from a nozzle chamber. Such ink
`
`ejector devices will be referred to hereinafter as MEMJETs. The technology there described is intended as an
`
`alternative to existing technologies for inkjet printing, such as Thermal Ink Jet (TIJ) or “Bubble Jet” technology
`developed mainly by the manufacturers Canon and Hewlett Packard, and Piezoelectric Ink Jet (PIJ) devices, as
`
`used for example by the manufacturers Epson and Tektronix.
`
`While TIJ and PIJ technologies have been developed to very high levels of performance since their
`introduction, MEMJET technology is able to offer significant advantages over these technologies. Potential
`advantages include higher speeds of operation and the ability to provide higher resolution than obtainable with
`
`other technologies. Similarly, MEMJET Technology provides the ability to manufacture monolithic printhead
`
`devices incorporating a large number of nozzles and of such size as to span all or a large part of a page (or other
`
`print surface), so that pagewidth printing can be achieved without any need to mechanically traverse a small
`printhead across the width of a page, as in typical existing inkjet printers.
`
`It has been found difficult to manufacture a long TlJ printhead for full-pagewidth printing. This is mainly
`because of the high power consumption of TlJ devices and the problem associated therewith of providing an
`
`adequate power supply for the printhead. Similarly, waste heat removal from the printhead to prevent boiling of the
`
`ink provides a challenge to the layout of such printhead. Also, differential thermal expansion over the length of a
`
`long TIJ-printhead my lead to severe nozzle alignment difficulties.
`
`Different problems have been found to attend the manufacture of long PIJ printheads for large- or full-
`
`page-width printing. These include acoustic crosstalk between nozzles due to similar time scales of drop ejection
`
`and reflection of acoustic pulses within the printhead. Further, silicon is not a piezoelectric material, and is very
`
`difficult to integrate with CMOS chips, so that separate external connections are required for every nozzle.
`
`Accordingly, manufacturing costs are very high compared to technologies such as MEMJET in which a
`
`monolithic device may be fabricated using established techniques, yet incorporate very large numbers of individual
`nozzles. Reference should be made to the aforementioned PCT application for detailed information on the
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`manufacture of MEMJET inkjet printhead chips; individual MEMJET printhead chips will here be referred to simply
`as printhead segments. A printhead assembly will usually incorporate a number of such printhead segments.
`While MEMJET technology has the advantage of allowing the cost effective manufacture of long
`
`monolithic printheads, it has nevertheless been found desirable to use a number of individual printhead segments
`
`(CMOS chips) placed substantially end-to-end where large widths of printing are to be provided. This is because
`
`chip production yields decrease substantially as chip lengths increase, so that costs increase. Of course, some
`
`printing applications. such as plan printing and other commercial printing, require printing widths which are beyond
`the maximum length that is practical for successful printhead chip manufacture.
`
`Summary of the Invention
`
`The present
`
`invention is broadly directed to the provision of a suitable printhead segment support
`
`structure and ink supply arrangement for an inkjet printhead assembly capable of single—pass, full-page-width
`printing as well as to such printhead assemblies. While the invention was conceived in the context of MEMJET
`
`printhead segments (chips), and thus the following summary and description of the invention is provided with
`
`particular reference to printhead assemblies incorporating MEMJET printhead segments. it is believed that the
`
`invention also has the potential to be employed with other ink jet printhead technologies.
`
`Accordingly, it is one object of the present invention to provide a printhead segment support structure that
`
`is capable of accommodating a series of printhead segments as described in PCT/AU98/00550 in an array that
`
`pennits single—pass pagewidth printing across the width of a surface passing under the printhead assembly.
`
`The term “single—pass pagewidth printing” should here be understood as referring to a printing operation
`
`during which the printhead assembly is moved in only one direction along or across the entire width or length of
`
`any print surface, as compared to a superimposed, generally orthogonal printhead carriage movement as
`
`employed in conventional ink jet printers. (Of course. printhead assembly movement may be relative, with the
`
`surface moving past a stationary printhead assembly.) It will be also understood that there are many possible page
`widths and the inkjet printhead segment support structure of the invention would be suitable for adaptation to a
`
`range of widths. A printhead assembly in accordance with the invention should in particular be useful where a
`
`plurality of generally elongate, but relatively small printhead segments are to be used to print across substantially
`
`the entire width of a sizable surface without the need for mechanically moving the printhead assembly or any
`printhead segment across as well as along the print surface.
`
`The invention has also been conceived in light of potential problems related to the relatively small size of
`
`individual printhead segments, their fragility and the required highly accurate alignment or registration of individual
`
`printhead segments with each other on the support structure and with external components in order to provide a
`
`printhead assembly capable of single-pass, full pagewidth printing. Multiple ink supply channels are required to
`
`supply ink in reliable manner to all printhead segments. Because of the small size of the segments, this in general
`
`would require high quality micro-machined parts. An ink supply conduit, on the other hand, is most economically
`made if it can be formed at a much coarser scale.
`
`Accordingly, another object of the invention is to provide a printhead segment support structure with a
`
`print fluid supply anangement that ensures adequate print fluid (eg ink) supply to individual printhead segments
`
`mounted to the support structure, at an affordable manufacturing cost.
`
`Typical MEMJET printhead segments have a dimension of 2cm length by 0.5mm width, and will include
`
`(in a layout for 4-color printing) four lengthwise-oriented rows of ink ejection nozzles,
`
`the segment being of
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`monolithic fabrication. Longer segments could be made and used, but the size mentioned gives very satisfactory
`fabrication yields. Each printhead segment has ink inlet holes arrayed on one surface and corresponding nozzle
`
`outlets arrayed on an opposite surface. Each of the four rows will then require connection to an appropriate ink
`
`supply, such that an inkjet printhead assembly can be provided for operation with (for example) cyan, magenta,
`yellow and black inks for color printing.
`
`Accordingly, a yet further object is to provide an ink supply arrangement thereby to enable supply of a
`
`number of differently colored inks (or other printing fluids) to selected ink inlets of individual printhead segments
`carried on a support structure for full pagewidth color printing.
`
`Another herewith related object of the invention is to provide a print fluid supply arrangement that is simple
`in layout and thus easy to incorporate in a printhead support structure.
`It should ensure even and reliable
`
`distribution of print fluids in a pagewidth inkjet printhead assembly.
`
`in a first aspect, the invention provides a support for a plurality of inkjet printhead segments, said support
`including:
`
`a hollow elongate member having at least one ink supply channel fonned therein, the or each ink supply
`
`channel being in fluid communication with an elongate slot in and extending at least partly along the elongate
`member; and
`
`a plurality of printhead segment carriers received and secured in neighbouring arrangement within the
`
`slot, each printhead segment carrier being adapted for mounting thereto of at least one printhead segment,
`
`wherein each printhead segment carrier includes at least one ink gallery arranged so as to connect the or
`
`an associated one of said ink supply channels with an ink inlet of said at least one printhead segment when
`mounted to that printhead segment carrier.
`
`in a second aspect, the invention provides an inkjet printhead assembly including:
`
`a hollow elongate member having at least one ink supply channel formed therein, the or each ink supply
`
`channel being in fluid communication with an elongate slot in and extending at least partly along the elongate
`member; and
`
`a plurality of printhead segment carriers received and secured in neighbouring arrangement within the
`
`slot; and
`
`at least one printhead segment mounted to each printhead segment carrier,
`
`wherein each printhead segment carrier includes at least one ink gallery arranged so as to connect the or
`
`an associated one of said ink supply channels with an ink inlet of the at least one printhead segment mounted to
`that printhead segment carrier.
`
`it is preferred that the at least one printhead segment on each printhead segment carrier has a defined
`
`printing range in a direction lengthwise along the elongate member, and that the printing ranges of the printhead
`
`segments mounted to a plurality of adjoining printhead segment carriers overlap, so that the printhead segments
`
`mounted to said plurality of adjoining printhead segment carriers have a combined printing range of greater
`
`lengthwise extent than any of the printing ranges comprised therein. This is a suitable way in which printing may be
`
`accomplished on a surface without the presence of gaps corresponding to lengthwise gaps between individual
`printhead segments.
`
`In a further aspect. the invention provides a method for assembling the inkjet printhead assembly wherein
`
`the step of mounting to each printhead segment carrier its respective at least one printhead segment precedes the
`
`step of securing that printhead segment carrier within the slot.
`
`It is then preferred that the printhead segment
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`carriers are secured within the slot sequentially, and that the at least one printhead segment in each printhead
`
`segment carrier installed after the first is positioned longitudinally relative to the at least one printhead segment in
`
`the printhead segment carrier last installed before being finally secured and immobilized within the slot. Thus.
`
`accurate relative positioning of successive printhead segments lengthwise along the elongate member can be
`achieved.
`
`Other aspects, objects and advantages of the invention, in its different embodiments. will also become
`
`apparent from the description given below of preferred embodiments and from the appended claims.
`
`Brief Description of the Figures
`
`Figure 1
`invention:
`
`is a perspective view of one embodiment of an inkjet printhead assembly according to the
`
`Figure 2 is a perspective view of the inkjet printhead assembly shown in Figure 1, with a cover component
`(shield plate) removed;
`
`Figure 3 is an exploded perspective view of a part only of the inkjet printhead assembly shown in Figure 1;
`
`Figure 4 is a perspective partial view of a support extrusion forming part of the inkjet printhead assembly
`shown in Figure 3;
`
`Figure 5 is a perspective view of a sealing shim fonning part of the inkjet printhead assembly shown in
`
`Figure 3;
`
`Figure 6 is a perspective view of a printhead segment carrier shown in Figure 3;
`
`Figure 7 is a further perspective view of the printhead segment carrier shown in Figure 6;
`Figure 8 is a bottom elevation of the printhead carrier shown in Figures 6 and 7 (as viewed in the direction
`
`of arrow "X" in Figure 6);
`
`Figure 9 is a top elevation of the printhead carrier shown in Figures 6 and 7 (as viewed in the direction of
`
`arrow "Y" in Figure 6);
`
`Figure 10 is a cross-sectional view of the printhead carrier of Figures 6 and 7 taken at station “B-B" in
`
`Figure 8;
`
`Figure 8;
`
`Figure 11 is a cross-sectional view of the printhead carrier of Figures 6 and 7 taken at station “A—A" in
`
`Figure 11a is an enlarged cross-sectional view of the seating arrangement of a printhead segment at the
`
`print carrier as per detail “E" in Figure 11;
`
`Figure 12 is a cross-sectional view of the printhead carrier of Figures 6 and 7 taken at station “D-D” in
`
`Figure 8;
`
`1:
`
`Figure 1;
`
`Figure 13 is an external perspective view of an end cap of the inkjet printhead assembly shown in Figure
`
`Figure 14 is an internal perspective view of the end cap shown in Figure 13
`
`Figure 15 is an external perspective view of a further end cap of the inkjet printhead assembly shown in
`
`Figure 16 is an internal perspective view of the end cap shown in Figure 15;
`
`Figure 17 is a perspective view (from the bottom) of the printhead assembly shown in Figure 1;
`
`Figure 18 is a perspective view of a part assembly of a support profile and modified sealing shim which
`are alternatives to those shown in Figures 4 and 5;
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`Figure 19 is a perspective view showing a molding tool and illustrating the basic arrangement of die
`
`components for injection molding of the printhead carrier shown in Figures 6 and 7;
`
`Fig 20 is a schematic cross-section of the injection molding tool shown in Figure 19, in an open position;
`
`and
`
`Fig 21 is a schematic transverse cross-section of the injection molding tool shown in Figure 19, in a closed
`
`position. taken at a station corresponding to the station “A-A" in Figure 8.
`
`Description of the Preferred Embodiment
`
`Figure 1 shows in perspective view an inkjet printhead assembly 1 according to one aspect of the
`invention and, in phantom outline, a surface 2 on which printing is to be effected. In use, the surface 2 moves
`
`relative to the assembly 1
`
`in a direction indicated by arrow 3 and transverse to the main extension of assembly 1
`
`(this direction is hereinafter also referred to as the transverse direction of the assembly 1), so that elongate
`printhead segments 4,
`in particular MEMJET printhead segments such as described in the above-mentioned
`
`PCT/AU98/00550, placed in stepped overlapping sequence along the lengthwise extension of assembly 1 can print
`
`simultaneously across substantially the entire width of the surface. The assembly 1 includes a shield plate 5 with
`
`which the surface 2 may come into sliding contact during such printing. Shield plate 5 has slots 6, each
`
`corresponding to one of the printhead segments 4, and through which ink ejected by that printhead segment 4 can
`reach surface 2.
`
`The particular assembly 1 shown in Figure 1 has eleven printhead segments 4. each capable of printing
`
`along a 2cm printing length (or,
`
`in other words, within a printing range extending 2cm) in a direction parallel to
`
`arrow 7 (hereinafter also called the lengthwise direction of the assembly 1) and is suitable for sing|e—pass printing
`of a portrait A4-letter size page. However, this number of printhead segments 4 and their length are in no way
`
`limiting, the invention being applicable to printhead assemblies of varying lengths and incorporating other required
`numbers of printhead segments 4.
`
`The slots 6 and the printhead segments 4 are arranged along two parallel lines in the lengthwise direction,
`
`with the printing length of each segment 4 (other than the endmost segments 4) slightly overiapping that of its two
`
`neighboring segments 4 in the other line. The printing length of each of the two endmost segments 4 overlaps the
`
`printing length of its nearest neighbour in the other row at one end only. Thus printing across the surface 2 is
`
`possible without gaps in the lengthwise direction of the assembly. In the particular assembly shown, the overlap is
`approximately 1mm at each end of the 2cm printing length, but this figure is by no means limiting.
`
`Figure 2 shows assembly 1 with the shield plate 5 removed. Each printhead segment 4 is secured to an
`
`associated one printhead segment carrier 8 that will be described below in more detail. Also secured to each
`
`printhead segment 4 is a tape automated bonded (TAB) film 9 which carries signal and power connections (not
`
`individually shown) to the associated printhead segment 4. Each TAB film 9 is closely wrapped around an extruded
`
`support profile 10 (whose function will be explained below) that houses and supports carriers 8, and they each
`terminate onto a printed circuit board (PCB) 11 secured to the profile 10 on a side thereof opposite to that where
`the printhead segments 4 are mounted, see also Figure 3.
`
`Figure 3 shows an exploded perspective view of a part only of assembly 1. In this view. three only of the
`
`printhead segment carriers 8 are shown numbered 8a, 8b and 8c, and only the printhead segment 4 associated
`with printhead segment carrier 8a is shown and numbered 4a, The TAB film 9 associated therewith is terminated at
`
`one end on an outer face of the printhead segment 4 and is otherwise shown (for clarity purposes) in the unwound,
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`flat state it has before being wound around profile 10 and connected to PCB 11. As can be seen in Figure 3,
`
`printhead segment carriers 8 are received (and secured). together with an interposed sealing shim 25, in a slot 21
`
`of half-circular cross-sectional shape in profile member 10 as will be explained in more detail below.
`
`Figure 4 illustrates a cross-section of the profile member 10 (which is preferably an aluminium alloy
`
`extrusion). This component serves as a frame and/or support structure for the printhead segment carriers 8 (with
`
`their associated printhead segments 4 and TAB films 9). the PCB 11 and shield plate 5.
`
`It also serves as an
`
`integral ink supply arrangement for the printhead segments 4, as will become clearer later.
`
`Profile member 10 is of semi—open cross-section, with a peripheral, structured wall 12 of uniform
`
`thickness. Free. opposing, lengthwise running edges 16', 17’ of side wall sections 16 and 17 respectively of wall 12
`border or delineate a gap 13 in wall 12 extending along the entire length of profile member 10. Profile member 10
`
`has three internal webs 14a, 14b, 14c that stand out from a base wall section 15 of peripheral wall 12 into the
`
`interior of member 10, so as to define together with side wall sections 16 and 17 a total of four (4) ink supply
`
`channels 20a, 20b, 20c and 20d which are open towards the gap 13. The shapes, proportions and relative
`arrangement of the webs and wall sections 14a-c, 16. 17 are such that their respective free edges 14a’, 14b’. 14c’
`
`and 16’, 17’, as viewed in the lengthwise direction and cross-section of profile member 10, define points on a semi-
`
`circle (indicated by a dotted line at “a" in Figure 4). In other words, an open slot 21 of semicircular cross-sectional
`
`shape is defined along one side of profile member 10 that runs along its extension, with each of the ink supply
`channels 20a-d opening into common slot 21.
`
`Base wall section 15 of profile member 10 also includes a serrated channel 22 opening towards the
`
`exterior of member 10, which, as best seen in Figure 3, serves to receive fastening screws 23 to fixedly secure
`
`PCB 11 onto profile member 10 in a forrn-fitting manner between free edges 24 (see Figure 4) of longitudinally
`extending curved webs 107 extending from the base wall section 15 of profile member 10.
`
`Referring again to Figure 3, sealing shim 25 is received (and secured) within the half-circular open slot 21.
`
`As best seen in Figures 3 and 5, shim 25 includes four lengthwise extending rows of rectangular openings 26 that
`
`are equidistantly spaced in peripheral (widthwise) direction of shim 25. so that three lengthwise-extending web
`
`sections 27 between the aperture rows (of which two are visible in Figure 5) are located so as to be brought into
`
`abutting engagement against the free edges 14a’, 14b’ and 14c’ of webs 14a, 14b, 14c of profile member 10 when
`
`shim 25 is received in slot 21. As can be gleaned from Figure 4, the free edges 16' and 17’ of side wall sections 16,
`
`17 of profile member 10 are shaped such as to provide a form-lock for retaining the lengthwise extending edges 28
`
`of shim member 25 as a snap fit. In other words. once shim 25 is mounted in profile member 10.
`
`it provides a
`
`perforated bottom for slot 21, which allows passage of inks from the ink supply channels 20a-d through apertures
`26 in shim 25 into slot 21. A glue or sealant is provided where shim webs 27 and edges 28 mate with the free
`
`edges 14a‘, 14b’, 14c’. 16' and 17‘ of profile member 10, thereby preventing cross-leakage between ink supply
`
`channels 20a-d along the abutting interfaces between shim 25 and profile member 10. It will be noted from Figure 5
`
`that not all apertures 26 have the same opening size. Reference numerals 26’ indicate two such smaller apertures,
`
`the significance of which is described _below, which are present in each aperture row at predetermined aperture
`
`intervals. A typical size for the full-sized apertures 26 is 2 mm x 2 mm. The shim is preferably of stainless steel, but
`a plastics sheet material may also be used.
`
`Turning next to Figures 6-12, these illustrate in differentviews and sections a typical printhead segment
`carrier 8. Carrier 8 is preferably a single micro-injection molded part made of a suitable temperature and abrasion
`
`resistant and form-holding plastics material.
`
`(A further manufacturing operation is carried out subsequent to
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`-7.
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`molding, as described below.) As best seen in Figures 6 and 7, the overall external shape of carrier 8 can be
`
`described illustratively as a diametrically slit half cylinder, with a half-circular back face 91, a partly planar front face
`
`82 and stepped end faces 83. Figure 8 shows a plan view of back face 91 and Figure 9 shows a plan view of front
`face 82.
`
`Carrier 8 has a plane of symmetry halfway along, and perpendicular to. its length, that is, as indicated by
`lines marked “b" in Figures 8 and 10 which lie in the plane. Line “D” as shown in Figure 8 extends in a direction that
`
`will hereinafter be described as transverse to the carrier 8. (When the carrier 8 is installed in the assembly 1, this
`direction is the same as the transverse direction of the assembly 1.) Lines marked “c” in Figures 8, 9, 11 and 12
`together similarly indicate the position of an imaginary plane which lies between two sections of the carrier 8 of
`
`different length and whose overall cross-sectional shapes are quarter circles. Line “c” as shown in Figure 9 extends
`in a direction that will hereinafter be described as lengthwise in the carrier 8. (When the carrier 8 is installed in the
`
`assembly 1 this direction is the same as the lengthwise direction of the assembly 1.) These sections will hereinafter
`
`be referred to as the shorter and longer “quarter cylinder” sections 8' and 8", respectively, to allow referenced
`description of features of the carrier 8.
`
`Each stepped end face 83 includes respective outer faces 84' and 85’ of quarter-circular-sector shaped
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`end walls 84 and 85 and an outer face 86' of an intermediate step wall 86 between and perpendicular to end walls
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`84, 85. This configuration enables carriers 8 to be placed in the slot 21 of profile 10 in such a way that adjoining
`carriers 8 overlap in the lengthwise direction with the step walls 86 of pairs of neighbouring carriers 8 facing each
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`and overlapping. Such an “interlocking” arrangement is shown in Figure 2. wherein it is apparent that every one of
`the eleven (11) carriers 8 has an orientation, relative to its neighbouring carrier or carriers 8. such that faces 84'
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`and 85' of each carrier lie adjacent to faces 85' and 84', respectively, of its neighbouring carrier(s) 8.
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`In other
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`words, each carrier 8 is so oriented in relation to its neighbouring carrierts) as to be rotated relatively by 180° about
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`In essence, neighbouring carriers 8 will align along a common lengthwise-
`an axis perpendicular to the face 82.
`oriented plane defined between the step walls 86 of adjoining carriers 8, shorter and longer quarter cylinder
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`sections 8’ and 8" of adjoining carriers 8 alternating with one another along the extension of slot 21.
`Turning now in particular to Figures 7, 9, 11 and 11a, front face 82 of carrier 8 includes on the shorter
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`quarter cylinder section 8' a planar surface 81. Formed in surface 81 are two handling (i.e. pick-up) slots 87 whose
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`purpose is described below. On the longer quarter cylinder section 8", front face 82 incorporates a mounting or
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`support surface 88 recessed with respect to edges 89 of sector-shaped end walls 84 that are co-planar with the
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`surface 81. As best seen in Figure 11, mounting surface 88 recedes in slanting fashion from a point on the back
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`face 91 of the longer quarter cylinder section 8" towards an elongate recess 90 extending lengthwise between
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`walls 84. Recess 90 is of constant transverse cross-section along its length and is shaped to receive in form-fitting
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`manner one printhead segment 4. Figure 11a shows, schematically only, printhead segment 4 in position in recess
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`90. Mounting surface 88 is provided to accommodate in flush manner with respect to the surface 81 the terminal
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`end of TAB film 9 connected to printhead segment 4, as is best seen in Figure 3. Due to the opposing orientations
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`of neighbouring carriers 8 along the extension of assembly 1, the TAB films 9 associated with any two neighbouring
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`carriers 8 lead away from their respective segments 4 in opposite transverse directions, as can be seen in Figure 2.
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`Referring now to Figures 6. 7, 8, 10 and 11 in particular, four rows of ink galleries or ink supply passages
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`92a to 92d of generally quadrilateral cross-section are formed within the printhead segment carrier 8. The ink
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`galleries 92a to 92d act as conduits for ink to pass from the ink supply passages 20a to 20d, respectively, via
`openings 26 in the shim 25, to the printhead segment 4 mounted in recess 90 of the printhead segment carrier 8.
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`WO 01/02172
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`PCT/AU00/00753
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`-3-
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`Galleries 92a-92d extend in quasi-radial arrangement between the half-cylindrical back face 91 of carrier 8 and
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`recess 90 located in the longer quarter cylinder section 8" at front face 82. The expression "quasi-radial” is used
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`here because recess 90 is not located at a transversely central position across carrier 8, but is offset into the longer
`quarter cylinder section 8", so that the inner ends of galleries 92a-92d are similarly off-set, as further described
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`below. Each gallery 92 has a rectangular opening 93 at back face 91. All rectangular openings 93 have the same
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`dimension in a peripheral direction of face 91 and are equidistantly spaced around the periphery of back face 91.
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`Moreover, the openings 93 are symmetrically located on opposing sides of the boundary between shorter quarter
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`cylinder section 8' and longer quarter cylinder section 8". as represented in Figure 11 by the line marked “c”. All
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`openings 93 in the shorter quarter cylinder section 8' are of the same dimension. and equispaced, in the lengthwise
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`direction. This also applies to the openings 93 in the longer quarter cylinder section 8", except that openings 93’ in
`the longer quarter cylinder section 8" which correspond to endmost galleries 92a’ and 92b’ are of smaller
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`dimension in the lengthwise direction than the other galleries 92a and 92b, respectively.
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`By way of further description of how the galleries 92a to 92d are formed, printhead segment carrier 8
`includes a set of five (5) quasi-radially converging walls 95 which converge from back face 91 towards recess 90 at
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`front face 82 and two of which define the