Silverbrook, Kia (Balmain, AU)
Berry, Norman Micheal (Balmain, AU)
Jackson, Garry Raymond (Balmain, AU)
Nakazawa, Akira (Balmain, AU)

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11/967226

05/01/2008

12/30/2007

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Silverbrook Research Pty Ltd

347/50

B41J2/14

SILVERBROOK RESEARCH PTY LTD (393 DARLING STREET, BALMAIN, 2041, AU)

What is claimed is:

1. A printed circuit board (PCB) assembly for a pagewidth printer, said assembly comprising: a number of modular PCBs each configured to control a respective modular printhead integrated circuit; modular supports defining a raised portion and a recessed portion at an end thereof, each PCB having electrical connecting strips which operatively overlie the respective recessed portions; at least one connecting member for operatively connecting respective PCBs to each other, each connecting member having a series of parallel spaced conducting strips, said member shaped and configured for fitment into a cavity defined by the raised and recessed portions of two abutting supports to connect the connecting strips of two PCBs via said conducting strips; and a printer controller configured to synchronize operation of the respective PCBs during printing.

2. The PCB assembly of claim 1, wherein the conducting strips of each connecting member are provided in a 2:1 relationship with the connecting strips of the PCB.

3. The PCB assembly of claim 1, wherein the connecting strips are each about 0.4 mm wide with a 0.4 mm gap between adjacent strips.

4. The PCB assembly of claim 1, wherein the conducting strips are gold plated.

5. The PCB assembly of claim 1, wherein each connecting member is a rectangular block having the series of conducting strips on each surface thereof.

6. The PCB assembly of claim 1, wherein each conducting strip is formed on one surface of the connecting member.

7. The PCB assembly of claim 1, wherein each connecting member is formed of a strip of silicone rubber printed to provide sequentially spaced conductive and non-conductive material strips.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. Ser. No. 11/482,950 filed on Jul. 10, 2006, which is a continuation of U.S. Ser. No. 10/760,217 filed on Jan. 21, 2004, now issued U.S. Pat. No. 7,090,336, all of which are here incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a printhead unit for use in a printing system. More particularly, the present invention relates to a printhead assembly which is mountable to and demountable from a printing unit.

CROSS-REFERENCE TO CO-PENDING APPLICATIONS

The following applications have been filed by the Applicant simultaneously with the present application:

7156508	7159972	7083271	7165834	7080894	7201469
7156489	10/760233	10/760246	7083257	7258422	7255423
7219980	10/760253	10/760255	10/760209	7118192	10/760194
10/760238	7077505	7198354	7077504	10/760189	7198355
10/760232	10/760231	7152959	7213906	7178901	7222938
7108353	7104629	10/760254	10/760210	10/760202	7201468
10/760198	10/760249	7234802	7303255	7287846	7156511
10/760264	7258432	7097291	10/760222	10/760248	7083273
10/760192	10/760203	10/760204	10/760205	10/760206	10/760267
10/760270	7198352	10/760271	7303251	7201470	7121655
7293861	7232208	10/760186	10/760261	7083272	10/760180
7111935	10/760213	10/760219	10/760237	7261482	10/760220
7002664	10/760252	10/760265	7237888	7168654	7201272
6991098	7217051	6944970	10/760215	7108434	10/760257
7210407	7186042	10/760266	6920704	7217049	10/760214
10/760260	7147102	7287828	7249838	10/760241

The disclosures of these co-pending applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Pagewidth printheads, for use in printing systems, are known. Such printheads typically span the width of the print media on which information is to be printed, and as such the dimensions and configuration of the printheads vary depending upon the application of the printing system and the dimensions of the print media. In this regard, due to the large variation in the required dimensions of such printheads, it is difficult to manufacture such printheads in a manner which caters for this variability.

Accordingly, the applicant has proposed the use of a pagewidth printhead made up of a plurality of replaceable printhead tiles arranged in an end-to-end manner. Each of the tiles mount an integrated circuit incorporating printing nozzles which eject printing fluid, e.g., ink, onto the print media in a known fashion. Such an arrangement has made it easier to manufacture printheads of variable dimensions and has also enabled the ability to remove and replace any defective tile in a pagewidth printhead without having to scrap the entire printhead.

However, apart from the ability to remove and replace any defective tiles, the previously proposed printhead is generally formed as an integral unit, with each component of the printhead fixedly attached to other components. Such an arrangement complicates the assembly process and does not provide for easy disassembly should the need to replace components other than just the defective tiles be necessary. Accordingly, a printhead unit which is easier to assemble and disassemble and which is made up of a number of separable individual parts to form a printhead unit of variable dimensions is required.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, there is provided a printhead assembly, comprising:

at least one printhead module comprising a unitary arrangement of at least two printhead integrated circuits, each of which has nozzles formed therein for delivering printing fluid onto the surface of print media, and a support member supporting and carrying the printing fluid for the at least two printhead integrated circuits; and

a casing in which the at least one printhead module is removably mounted so as to constrain movement of the at least one printhead module relative to the casing in at least the direction of printing fluid delivery from the nozzles to the print media.

In order to provide this constraint, the casing may comprise a longitudinally extending groove in which a first side of the printhead module(s) is slidably received, with a second side of the printhead module(s) being clamped to the casing by a clamping arrangement.

Further, the casing may comprise a longitudinally extending channel portion within which the printhead module(s) is mounted, with the channel comprising first and second side walls joined by a lower wall. The first side wall includes the longitudinally extending groove and the longitudinally extending groove being formed between upper and lower longitudinally extending tabs, and the second side wall has a longitudinally extending upper surface upon which the second side of the at least one printhead module is mounted, the longitudinally extending upper surface having a height from the lower surface of the channel portion substantially equal to a height of the lower longitudinally extending protrusion of the first side wall.

This channel portion of the casing is incorporated in a support frame with which the clamping arrangement engages. A cover portion for covering the support frame is also comprised in the casing.

The printhead module(s) may be formed as a unitary arrangement of the at least two printhead integrated circuits, the support member, at least one fluid distribution member mounting the at least two printhead integrated circuits to the support member, and an electrical connector for connecting electrical signals to the at least two printhead integrated circuits. In this arrangement, the support member has at least one longitudinally extending channel for carrying the printing fluid for the printhead integrated circuits and includes a plurality of apertures extending through a wall of the support member arranged so as to direct the printing fluid from the at least one channel to associated nozzles in both, or if more than two, all of the printhead integrated circuits by way of respective ones of the fluid distribution members.

An embodiment of a printhead module that incorporates features of the present invention is now described by way of example with reference to the accompanying drawings, as is an embodiment of a printhead assembly that incorporates the printhead module.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a perspective view of a printhead assembly in accordance with an embodiment of the present invention;

FIG. 2 shows the opposite side of the printhead assembly of FIG. 1;

FIG. 3 shows a sectional view of the printhead assembly of FIG. 1;

FIG. 4A illustrates a portion of a printhead module that is incorporated in the printhead assembly of FIG. 1;

FIG. 4B illustrates a lid portion of the printhead module of FIG. 4A;

FIG. 5A shows a top view of a printhead tile that forms a portion of the printhead module of FIG. 4A;

FIG. 5B shows a bottom view of the printhead tile of FIG. 5A;

FIG. 6 illustrates electrical connectors for printhead integrated circuits that are mounted to the printhead tiles as shown in FIG. 5A;

FIG. 7 illustrates a connection that is made between the printhead module of FIG. 4A and the underside of the printhead tile of FIGS. 5A and 5B;

FIG. 8 illustrates a “female” end portion of the printhead module of FIG. 4A;

FIG. 9 illustrates a “male” end portion of the printhead module of FIG. 4A;

FIG. 10 illustrates a fluid delivery connector for the male end portion of FIG. 9;

FIG. 11 illustrates a fluid delivery connector for the female end portion of FIG. 8;

FIG. 12 illustrates the fluid delivery connector of FIG. 10 or 11 connected to fluid delivery tubes;

FIG. 13 illustrates a tubular portion arrangement of the fluid delivery connectors of FIGS. 10 and 11;

FIG. 14A illustrates a capping member for the female and male end portions of FIGS. 8 and 9;

FIG. 14B illustrates the capping member of FIG. 14A applied to the printhead module of FIG. 4A;

FIG. 15A shows a sectional (skeletal) view of a support frame of a casing of the printhead assembly of FIG. 1;

FIGS. 15B and 15C show perspective views of the support frame of FIG. 15A in upward and downward orientations, respectively;

FIG. 16 illustrates a printed circuit board (PCB) support that forms a portion of the printhead assembly of FIG. 1;

FIGS. 17A and 17B show side and rear perspective views of the PCB support of FIG. 16;

FIG. 18A illustrates circuit components carried by a PCB supported by the PCB support of FIG. 16;

FIG. 18B shows an opposite side perspective view of the PCB and the circuit components of FIG. 18A;

FIG. 19A shows a side view illustrating further components attached to the PCB support of FIG. 16;

FIG. 19B shows a rear side view of a pressure plate that forms a portion of the printhead assembly of FIG. 1;

FIG. 20 shows a front view illustrating the further components of FIG. 19;

FIG. 21 shows a perspective view illustrating the further components of FIG. 19;

FIG. 22 shows a front view of the PCB support of FIG. 16;

FIG. 22A shows a side sectional view taken along the line I-I in FIG. 22;

FIG. 22B shows an enlarged view of the section A of FIG. 22A;

FIG. 22C shows a side sectional view taken along the line II-II in FIG. 22;

FIG. 22D shows an enlarged view of the section B of FIG. 22C;

FIG. 22E shows an enlarged view of the section C of FIG. 22C;

FIG. 23 shows a side view of a cover portion of the casing of the printhead assembly of FIG. 1;

FIG. 24 illustrates a plurality of the PCB supports of FIG. 16 in a modular assembly;

FIG. 25 illustrates a connecting member that is carried by two adjacent PCB supports of FIG. 24 and which is used for interconnecting PCBs that are carried by the PCB supports;

FIG. 26 illustrates the connecting member of FIG. 25 interconnecting two PCBs;

FIG. 27 illustrates the interconnection between two PCBs by the connecting member of FIG. 25;

FIG. 28 illustrates a connecting region of busbars that are located in the printhead assembly of FIG. 1;

FIG. 29 shows a perspective view of an end portion of a printhead assembly in accordance with an embodiment of the present invention;

FIG. 30 illustrates a connector arrangement that is located in the end portion of the printhead assembly as shown in FIG. 29;

FIG. 31 illustrates the connector arrangement of FIG. 30 housed in an end housing and plate assembly which forms a portion of the printhead assembly;

FIGS. 32A and 32B show opposite side views of the connector arrangement of FIG. 30;

FIG. 32C illustrates a fluid delivery connection portion of the connector arrangement of FIG. 30;

FIG. 33A illustrates a support member that is located in a printhead assembly in accordance with an embodiment of the present invention;

FIG. 33B shows a sectional view of the printhead assembly with the support member of FIG. 33A located therein;

FIG. 33C illustrates a part of the printhead assembly of FIG. 33B in more detail;

FIG. 34 illustrates the connector arrangement of FIG. 30 housed in the end housing and plate assembly of FIG. 31 attached to the casing of the printhead assembly;

FIG. 35A shows an exploded perspective view of the end housing and plate assembly of FIG. 31;

FIG. 35B shows an exploded perspective view of an end housing and plate assembly which forms a portion of the printhead assembly of FIG. 1;

FIG. 36 shows a perspective view of the printhead assembly when in a form which uses both of the end housing and plate assemblies of FIGS. 35A and 35B;

FIG. 37 illustrates a connector arrangement housed in the end housing and plate assembly of FIG. 35B;

FIGS. 38A and 38B shows opposite side views of the connector arrangement of FIG. 37;

FIG. 39 illustrates an end plate when attached to the printhead assembly of FIG. 29;

FIG. 40 illustrates data flow and functions performed by a print engine controller integrated circuit that forms one of the circuit components shown in FIG. 18A;

FIG. 41 illustrates the print engine controller integrated circuit of FIG. 40 in the context of an overall printing system architecture;

FIG. 42 illustrates the architecture of the print engine controller integrated circuit of FIG. 41;

FIG. 43 shows an exploded view of a fluid distribution stack of elements that form the printhead tile of FIG. 5A;

FIG. 44 shows a perspective view (partly in section) of a portion of a nozzle system of a printhead integrated circuit that is incorporated in the printhead module of the printhead assembly of FIG. 1;

FIG. 45 shows a vertical sectional view of a single nozzle (of the nozzle system shown in FIG. 44) in a quiescent state;

FIG. 46 shows a vertical sectional view of the nozzle of FIG. 45 at an initial actuation state;

FIG. 47 shows a vertical sectional view of the nozzle of FIG. 46 at a later actuation state;

FIG. 48 shows in perspective a partial vertical sectional view of the nozzle of FIG. 45, at the actuation state shown in FIG. 46;

FIG. 49 shows in perspective a vertical section of the nozzle of FIG. 45, with ink omitted;

FIG. 50 shows a vertical sectional view of the nozzle of FIG. 49;

FIG. 51 shows in perspective a partial vertical sectional view of the nozzle of FIG. 45, at the actuation state shown in FIG. 46;

FIG. 52 shows a plan view of the nozzle of FIG. 45; and

FIG. 53 shows a plan view of the nozzle of FIG. 45 with lever arm and movable nozzle portions omitted.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The exemplary embodiments of the present invention are described as a printhead assembly and a printhead module that is incorporated in the printhead assembly.

General Overview

The printhead assembly 10 as shown in FIGS. 1 and 2 is intended for use as a pagewidth printhead in a printing system. That is, a printhead which extends across the width or along the length of a page of print media, e.g., paper, for printing. During printing, the printhead assembly ejects ink onto the print media as it progresses past, thereby forming printed information thereon, with the printhead assembly being maintained in a stationary position as the print media is progressed past. That is, the printhead assembly is not scanned across the page in the manner of a conventional printhead.

As can be seen from FIGS. 1 and 2, the printhead assembly 10 includes a casing 20 and a printhead module 30 . The casing 20 houses the dedicated (or drive) electronics for the printhead assembly together with power and data inputs, and provides a structure for mounting the printhead assembly to a printer unit. The printhead module 30 , which is received within a channel 21 of the casing 20 so as to be removable therefrom, includes a fluid channel member 40 which carries printhead tiles 50 having printhead integrated circuits 51 incorporating printing nozzles thereon. The printhead assembly 10 further includes an end housing 120 and plate 110 assembly and an end plate 111 which are attached to longitudinal ends of the assembled casing 20 and printhead module 30 .

The printhead module 30 and its associated components will now be described with reference to FIGS. 1 to 14 B.

As shown in FIG. 3, the printhead module 30 includes the fluid channel member 40 and the printhead tiles 50 mounted on the upper surface of the member 40 .

As illustrated in FIGS. 1 and 2, sixteen printhead tiles 50 are provided in the printhead module 30 . However, as will be understood from the following description, the number of printhead tiles and printhead integrated circuits mounted thereon may be varied to meet specific applications of the present invention.

As illustrated in FIGS. 1 and 2, each of the printhead tiles 50 has a stepped end region so that, when adjacent printhead tiles 50 are butted together end-to-end, the printhead integrated circuits 51 mounted thereon overlap in this region. Further, the printhead integrated circuits 51 extend at an angle relative to the longitudinal direction of the printhead tiles 50 to facilitate overlapping between the printhead integrated circuits 51 . This overlapping of adjacent printhead integrated circuits 51 provides for a constant pitch between the printing nozzles (described later) incorporated in the printhead integrated circuits 51 and this arrangement obviated discontinuities in information printed across or along the print media (not shown) passing the printhead assembly 10 . This overlapping arrangement of the printhead integrated circuits is described in the Applicant's issued U.S. Pat. No. 6,623,106, which is incorporated herein by reference.

FIG. 4 shows the fluid channel member 40 of the printhead module 30 which serves as a support member for the printhead tiles 50 . The fluid channel member 40 is configured so as to fit within the channel 21 of the casing 20 and is used to deliver printing ink and other fluids to the printhead tiles 50 . To achieve this, the fluid channel member 40 includes channel-shaped ducts 41 which extend throughout its length from each end of the fluid channel member 40 . The channel-shaped ducts 41 are used to transport printing ink and other fluids from a fluid supply unit (of a printing system to which the printhead assembly 10 is mounted) to the printhead tiles 50 via a plurality of outlet ports 42 .

The fluid channel member 40 is formed by injection moulding a suitable material. Suitable materials are those which have a low coefficient of linear thermal expansion (CTE), so that the nozzles of the printhead integrated circuits are accurately maintained under operational condition (described in more detail later), and have chemical inertness to the inks and other fluids channelled through the fluid channel member 40 . One example of a suitable material is a liquid crystal polymer (LCP). The injection moulding process is employed to form a body portion 44 a having open channels or grooves therein and a lid portion 44 b which is shaped with elongate ridge portions 44 c to be received in the open channels. The body and lid portions 44 a and 44 b are then adhered together with an epoxy to form the channel-shaped ducts 41 as shown in FIGS. 3 and 4A. However, alternative moulding techniques may be employed to form the fluid channel member 40 in one piece with the channel-shaped ducts 41 therein.

The plurality of ducts 41 , provided in communication with the corresponding outlet ports 42 for each printhead tile 50 , are used to transport different coloured or types of inks and the other fluids. The different inks can have different colour pigments, for example, black, cyan, magenta and yellow, etc., and/or be selected for different printing applications, for example, as visually opaque inks, infrared opaque inks, etc. Further, the other fluids which can be used are, for example, air for maintaining the printhead integrated circuits 51 free from dust and other impurities and/or for preventing the print media from coming into direct contact with the printing nozzles provided on the printhead integrated circuits 51 , and fixative for fixing the ink substantially immediately after being printed onto the print media, particularly in the case of high-speed printing applications.

In the assembly shown in FIG. 4, seven ducts 41 are shown for transporting black, cyan, magenta and yellow coloured ink, each in one duct, infrared ink in one duct, air in one duct and fixative in one duct. Even though seven ducts are shown, a greater or lesser number may be provided to meet specific applications. For example, additional ducts might be provided for transporting black ink due to the generally higher percentage of black and white or greyscale printing applications.

The fluid channel member 40 further includes a pair of longitudinally extending tabs 43 along the sides thereof for securing the printhead module 30 to the channel 21 of the casing 20 (described in more detail later). It is to be understood however that a series of individual tabs could alternatively be used for this purpose.

As shown in FIG. 5A, each of the printhead tiles 50 of the printhead module 30 carries one of the printhead integrated circuits 51 , the latter being electrically connected to a printed circuit board (PCB) 52 using appropriate contact methods such as wire bonding, with the connections being protectively encapsulated in an epoxy encapsulant 53 . The PCB 52 extends to an edge of the printhead tile 50 , in the direction away from where the printhead integrated circuits 51 are placed, where the PCB 52 is directly connected to a flexible printed circuit board (flex PCB) 80 for providing power and data to the printhead integrated circuit 51 (described in more detail later). This is shown in FIG. 6 with individual flex PCBs 80 extending or “hanging” from the edge of each of the printhead tiles 50 . The flex PCBs 80 provide electrical connection between the printhead integrated circuits 51 , a power supply 70 and a PCB 90 (see FIG. 3) with drive electronics 100 (see FIG. 18A) housed within the casing 20 (described in more detail later).

FIG. 5B shows the underside of one of the printhead tiles 50 . A plurality of inlet ports 54 is provided and the inlet ports 54 are arranged to communicate with corresponding ones of the plurality of outlet ports 42 of the ducts 41 of the fluid channel member 40 when the printhead tiles 50 are mounted thereon. That is, as illustrated, seven inlet ports 54 are provided for the outlet ports 42 of the seven ducts 41 . Specifically, both the inlet and outlet ports are orientated in an inclined disposition with respect to the longitudinal direction of the printhead module so that the correct fluid, i.e., the fluid being channelled by a specific duct, is delivered to the correct nozzles (typically a group of nozzles is used for each type of ink or fluid) of the printhead integrated circuits.

On a typical printhead integrated circuit 51 as employed in realisation of the present invention, more than 7000 (e.g., 7680) individual printing nozzles may be provided, which are spaced so as to effect printing with a resolution of 1600 dots per inch (dpi). This is achieved by having a nozzle density of 391 nozzles/mm ² across a print surface width of 20 mm (0.8 in), with each nozzle capable of delivering a drop volume of 1 pl.

Accordingly, the nozzles are micro-sized (i.e., of the order of 10 ⁻⁶ metres) and as such are not capable of receiving a macro-sized (i.e., millimetric) flows of ink and other fluid as presented by the inlet ports 54 on the underside of the printhead tile 50 . Each printhead tile 50 , therefore, is formed as a fluid distribution stack 500 (see FIG. 43), which includes a plurality of laminated layers, with the printhead integrated circuit 51 , the PCB 52 , and the epoxy 53 provided thereon.

The stack 500 carries the ink and other fluids from the ducts 41 of the fluid channel member 40 to the individual nozzles of the printhead integrated circuit 51 by reducing the macro-sized flow diameter at the inlet ports 54 to a micro-sized flow diameter at the nozzles of the printhead integrated circuits 51 . An exemplary structure of the stack which provides this reduction is described in more detail later.

Nozzle systems which are applicable to the printhead assembly of the present invention may comprise any type of ink jet nozzle arrangement which can be integrated on a printhead integrated circuit. That is, systems such as a continuous ink system, an electrostatic system and a drop-on-demand system, including thermal and piezoelectric types, may be used.

There are various types of known thermal drop-on-demand system which may be employed which typically include ink reservoirs adjacent the nozzles and heater elements in thermal contact therewith. The heater elements heat the ink and create gas bubbles which generate pressures in the ink to cause droplets to be ejected through the nozzles onto the print media. The amount of ink ejected onto the print media and the timing of ejection by each nozzle are controlled by drive electronics. Such thermal systems impose limitations on the type of ink that can be used however, since the ink must be resistant to heat.

There are various types of known piezoelectric drop-on-demand system which may be employed which typically use piezo-crystals (located adjacent the ink reservoirs) which are caused to flex when an electric current flows therethrough. This flexing causes droplets of ink to be ejected from the nozzles in a similar manner to the thermal systems described above. In such piezoelectric systems the ink does not have to be heated and cooled between cycles, thus providing for a greater range of available ink types. Piezoelectric systems are difficult to integrate into drive integrated circuits and typically require a large number of connections between the drivers and the nozzle actuators.

As an alternative, a micro-electromechanical system (MEMS) of nozzles may be used, such a system including thermo-actuators which cause the nozzles to eject ink droplets. An exemplary MEMS nozzle system applicable to the printhead assembly of the present invention is described in more detail later.

Returning to the assembly of the fluid channel member 40 and printhead tiles 50 , each printhead tile 50 is attached to the fluid channel member 40 such that the individual outlet ports 42 and their corresponding inlet ports 54 are aligned to allow effective transfer of fluid therebetween. An adhesive, such as a curable resin (e.g., an epoxy resin), is used for attaching the printhead tiles 50 to the fluid channel member 40 with the upper surface of the fluid channel member 40 being prepared in the manner shown in FIG. 7.

That is, a curable resin is provided around each of the outlet ports 42 to form a gasket member 60 upon curing. This gasket member 60 provides an adhesive seal between the fluid channel member 40 and printhead tile 50 whilst also providing a seal around each of the communicating outlet ports 42 and inlet ports 54 . This sealing arrangement facilitates the flow and containment of fluid between the ports. Further, two curable resin deposits 61 are provided on either side of the gasket member 60 in a symmetrical manner.

The symmetrically placed deposits 61 act as locators for positioning the printhead tiles 50 on the fluid channel member 40 and for preventing twisting of the printhead tiles 50 in relation to the fluid channel member 40 . In order to provide additional bonding strength, particularly prior to and during curing of the gasket members 60 and locators 61 , adhesive drops 62 are provided in free areas of the upper surface of the fluid channel member 40 . A fast acting adhesive, such as cyanoacrylate or the like, is deposited to form the locators 61 and prevents any movement of the printhead tiles 50 with respect to the fluid channel member 40 during curing of the curable resin.

With this arrangement, if a printhead tile is to be replaced, should one or a number of nozzles of the associated printhead integrated circuit fail, the individual printhead tiles may easily be removed. Thus, the surfaces of the fluid channel member and the printhead tiles are treated in a manner to ensure that the epoxy remains attached to the printhead tile, and not the fluid channel member surface, if a printhead tile is removed from the surface of the fluid channel member by levering. Consequently, a clean surface is left behind by the removed printhead tile, so that new epoxy can readily be provided on the fluid channel member surface for secure placement of a new printhead tile.

The above-described printhead module of the present invention is capable of being constructed in various lengths, accommodating varying numbers of printhead tiles attached to the fluid channel member, depending upon the specific application for which the printhead assembly is to be employed. For example, in order to provide a printhead assembly for A3-sized pagewidth printing in landscape orientation, the printhead assembly may require 16 individual printhead tiles. This may be achieved by providing, for example, four printhead modules each having four printhead tiles, or two printhead modules each having eight printhead tiles, or one printhead module having 16 printhead tiles (as in FIGS. 1 and 2) or any other suitable combination. Basically, a selected number of standard printhead modules may be combined in order to achieve the necessary width required for a specific printing application.

In order to provide this modularity in an easy and efficient manner, plural fluid channel members of each of the printhead modules are formed so as to be modular and are configured to permit the connection of a number of fluid channel members in an end-to-end manner. Advantageously, an easy and convenient means of connection can be provided by configuring each of the fluid channel members to have complementary end portions. In one embodiment of the present invention each fluid channel member 40 has a “female” end portion 45 , as shown in FIG. 8, and a complementary “male” end portion 46 , as shown in FIG. 9.

The end portions 45 and 46 are configured so that on bringing the male end portion 46 of one printhead module 30 into contact with the female end portion 45 of a second printhead module 30 , the two printhead modules 30 are connected with the corresponding ducts 41 thereof in fluid communication. This allows fluid to flow between the connected printhead modules 30 without interruption, so that fluid such as ink, is correctly and effectively delivered to the printhead integrated circuits 51 of each of the printhead modules 30 .

In order to ensure that the mating of the female and male end portions 45 and 46 provides an effective seal between the individual printhead modules 30 a sealing adhesive, such as epoxy, is applied between the mated end portions.

It is clear that, by providing such a configuration, any number of printhead modules can suitably be connected in such an end-to-end fashion to provide the desired scale-up of the total printhead length. Those skilled in the art can appreciate that other configurations and methods for connecting the printhead assembly modules together so as to be in fluid communication are within the scope of the present invention.

Further, this exemplary configuration of the end portions 45 and 46 of the fluid channel member 40 of the printhead modules 30 also enables easy connection to the fluid supply of the printing system to which the printhead assembly is mounted. That is, in one embodiment of the present invention, fluid delivery connectors 47 and 48 are provided, as shown in FIGS. 10 and 11, which act as an interface for fluid flow between the ducts 41 of the printhead modules 30 and (internal) fluid delivery tubes 6 , as shown in FIG. 12. The fluid delivery tubes 6 are referred to as being internal since, as described in more detail later, these tubes 6 are housed in the printhead assembly 10 for connection to external fluid delivery tubes of the fluid supply of the printing system. However, such an arrangement is clearly only one of the possible ways in which the inks and other fluids can be supplied to the printhead assembly of the present invention.

As shown in FIG. 10, the fluid delivery connector 47 has a female connecting portion 47 a which can mate with the male end portion 46 of the printhead module 30 . Alternatively, or additionally, as shown in FIG. 11, the fluid delivery connector 48 has a male connecting portion 48 a which can mate with the female end portion 45 of the printhead module 30 . Further, the fluid delivery connectors 47 and 48 include tubular portions 47 b and 48 b , respectively, which can mate with the internal fluid delivery tubes 6 . The particular manner in which the tubular portions 47 b and 48 b are configured so as to be in fluid communication with a corresponding duct 41 is shown in FIG. 12.

As shown in FIGS. 10 to 13 , seven tubular portions 47 b and 48 b are provided to correspond to the seven ducts 41 provided in accordance with the above-described exemplary embodiment of the present invention. Accordingly, seven internal fluid delivery tubes 6 are used each for delivering one of the seven aforementioned fluids of black, cyan, magenta and yellow ink, IR ink, fixative and air. However, as previously stated, those skilled in the art clearly understand that more or less fluids may be used in different applications, and consequently more or less fluid delivery tubes, tubular portions of the fluid delivery connectors and ducts may be provided.

Further, this exemplary configuration of the end portions of the fluid channel member 40 of the printhead modules 30 also enables easy sealing of the ducts 41 . To this end, in one embodiment of the present invention, a sealing member 49 is provided as shown in FIG. 14A, which can seal or cap both of the end portions of the printhead module 30 . That is, the sealing member 49 includes a female connecting section 49 a and a male connecting section 49 b which can respectively mate with the male end portion 46 and the female end portion 45 of the printhead modules 30 . Thus, a single sealing member is advantageously provided despite the differently configured end portions of a printhead module. FIG. 14B illustrates an exemplary arrangement of the sealing member 49 sealing the ducts 41 of the fluid channel member 40 . Sealing of the sealing member 49 and the fluid channel member 40 interface is further facilitated by applying a sealing adhesive, such as an epoxy, as described above.

In operation of a single printhead module 30 for an A4-sized pagewidth printing application, for example, a combination of one of the fluid delivery connectors 47 and 48 connected to one corresponding end portion 45 and 46 and a sealing member 49 connected to the other of the corresponding end portions 45 and 46 is used so as to deliver fluid to the printhead integrated circuits 51 . On the other hand, in applications where the printhead assembly is particularly long, being comprised of a plurality of printhead modules 30 connected together (e.g., in wide format printing), it may be necessary to provide fluid from both ends of the printhead assembly. Accordingly, one each of the fluid delivery connectors 47 and 48 may be connected to the corresponding end portions 45 and 46 of the end printhead modules 30 .

The above-described exemplary configuration of the end portions of the printhead module of the present invention provides, in part, for the modularity of the printhead modules. This modularity makes it possible to manufacture the fluid channel members of the printhead modules in a standard length relating to the minimum length application of the printhead assembly. The printhead assembly length can then be scaled-up by combining a number of printhead modules to form a printhead assembly of a desired length. For example, a standard length printhead module could be manufactured to contain eight printhead tiles, which may be the minimum requirement for A4-sized printing applications. Thus, for a printing application requiring a wider printhead having a length equivalent to 32 printhead tiles, four of these standard length printhead modules could be used. On the other hand, a number of different standard length printhead modules might be manufactured, which can be used in combination for applications requiring variable length printheads.

However, these are merely examples of how the modularity of the printhead assembly of the present invention functions, and other combinations and standard lengths could be employed and fall within the scope of the present invention.

The casing 20 and its associated components will now be described with reference to FIGS. 1 to 3 and 15 A to 28 .

In one embodiment of the present invention, the casing 20 is formed as a two-piece outer housing which houses the various components of the printhead assembly and provides structure for the printhead assembly which enables the entire unit to be readily mounted in a printing system. As shown in FIG. 3, the outer housing is composed of a support frame 22 and a cover portion 23 . Each of these portions 22 and 23 are made from a suitable material which is lightweight and durable, and which can easily be extruded to form various lengths. Accordingly, in one embodiment of the present invention, the portions 22 and 23 are formed from a metal such as aluminium.

As shown in FIGS. 15A to 15 C, the support frame 22 of the casing 20 has an outer frame wall 24 and an inner frame wall 25 (with respect to the outward and inward directions of the printhead assembly 10 ), with these two walls being separated by an internal cavity 26 . The channel 21 (also see FIG. 3) is formed as an extension of an upper wall 27 of the support frame 22 and an arm portion 28 is formed on a lower region of the support frame 22 , extending from the inner frame wall 25 in a direction away from the outer frame wall 24 . The channel 21 extends along the length of the support frame 22 and is configured to receive the printhead module 30 . The printhead module 30 is received in the channel 21 with the printhead integrated circuits 51 facing in an upward direction, as shown in FIGS. 1 to 3 , and this upper printhead integrated circuit surface defines the printing surface of the printhead assembly 10 .

As depicted in FIG. 15A, the channel 21 is formed by the upper wall 27 and two, generally parallel side walls 24 a and 29 of the support frame 22 , which are arranged as outer and inner side walls (with respect to the outward and inward directions of the printhead assembly 10 ) extending along the length of the support frame 22 . The two side walls 24 a and 29 have different heights with the taller, outer side wall 24 a being defined as the upper portion of the outer frame wall 24 which extends above the upper wall 27 of the support frame 22 , and the shorter, inner side wall 29 being provided as an upward extension of the upper wall 27 substantially parallel to the inner frame wall 25 . The outer side wall 24 a includes a recess (groove) 24 b formed along the length thereof. A bottom surface 24 c of the recess 24 b is positioned so as to be at the same height as a top surface 29 a of the inner side wall 29 with respect to the upper wall 27 of the channel 21 . The recess 24 b further has an upper surface 24 d which is formed as a ridge which runs along the length of the outer side wall 24 a (see FIG. 15B).

In this arrangement, one of the longitudinally extending tabs 43 of the fluid channel member 40 of the printhead module 30 is received within the recess 24 b of the outer side wall 24 a so as to be held between the lower and upper surfaces 24 c and 24 d thereof. Further, the other longitudinally extending tab 43 provided on the opposite side of the fluid channel member 40 , is positioned on the top surface 29 a of the inner side wall 29 . In this manner, the assembled printhead module 30 may be secured in place on the casing 20 , as will be described in more detail later.

Further, the outer side wall 24 a also includes a slanted portion 24 e along the top margin thereof, the slanted portion 24 e being provided for fixing a print media guide 5 to the printhead assembly 10 , as shown in FIG. 3. This print media guide is fixed following assembly of the printhead assembly and is configured to assist in guiding print media, such as paper, across the printhead integrated circuits for printing without making direct contact with the nozzles of the printhead integrated circuits.

As shown in FIG. 15A, the upper wall 27 of the support frame 22 and the arm portion 28 include lugs 27 a and 28 a , respectively, which extend along the length of the support frame 22 (see FIGS. 15B and 15C). The lugs 27 a and 28 a are positioned substantially to oppose each other with respect to the inner frame wall 25 of the support frame 22 and are used to secure a PCB support 91 (described below) to the support frame 22 .

FIGS. 15B and 15C illustrate the manner in which the outer and inner frame walls 24 and 25 extend for the length of the casing 20 , as do the channel 21 , the upper wall 27 , and its lug 27 a , the outer and inner side walls 24 a and 29 , the recess 24 b and its bottom and upper surfaces 24 c and 24 d , the slanted portion 24 e , the top surface 29 a of the inner side wall 29 , and the arm portion 28 , and its lugs 28 a and 28 b and recessed and curved end portions 28 c and 28 d (described in more detail later).

The PCB support 91 will now be described with reference to FIGS. 3 and 16 to 22 E. In FIG. 3, the support 91 is shown in its secured position extending along the inner frame wall 25 of the support frame 22 from the upper wall 27 to the arm portion 28 . The support 91 is used to carry the PCB 90 which mounts the drive electronics 100 (as described in more detail later).

As can be seen particularly in FIGS. 17A and 17B, the support 91 includes lugs 92 on upper and lower surfaces thereof which communicate with the lugs 27 a and 28 a for securing the support 91 against the inner frame wall 25 of the support frame 22 . A base portion 93 of the support 91 , is arranged to extend along the arm portion 28 of the support frame 22 , and is seated on the top surfaces of the lugs 28 a and 28 b of the arm portion 28 (see FIG. 15B) when mounted on the support frame 22 .

The support 91 is formed so as to locate within the casing 20 and against the inner frame wall 25 of the support frame 22 . This can be achieved by moulding the support 91 from a plastics material having inherent resilient properties to engage with the inner frame wall 25 . This also provides the support 91 with the necessary insulating properties for carrying the PCB 90 . For example, polybutylene terephthalate (PBT) or polycarbonate may be used for the support 91 .

The base portion 93 further includes recessed portions 93 a and corresponding locating lugs 93 b , which are used to secure the PCB 90 to the support 91 (as described in more detail later). Further, the upper portion of the support 91 includes upwardly extending arm portions 94 , which are arranged and shaped so as to fit over the inner side wall 29 of the channel 21 and the longitudinally extending tab 43 of the printhead module 30 (which is positioned on the top surface 29 a of the inner side wall 29 ) once the fluid channel member 40 of the printhead module 30 has been inserted into the channel 21 . This arrangement provides for securement of the printhead module 30 within the channel 21 of the casing 20 , as is shown more clearly in FIG. 3.

In one embodiment of the present invention, the extending arm portions 94 of the support 91 are configured so as to perform a “clipping” or “clamping” action over and along one edge of the printhead module 30 , which aids in preventing the printhead module 30 from being dislodged or displaced from the fully assembled printhead assembly 10 . This is because the clipping action acts upon the fluid channel member 40 of the printhead module 30 in a manner which substantially constrains the printhead module 30 from moving upwards from the printhead assembly 10 (i.e., in the z-axis direction as depicted in FIG. 3) due to both longitudinally extending tabs 43 of the fluid channel member 40 being held firmly in place (in a manner which will be described in more detail below), and from moving across the longitudinal direction of the printhead module 30 (i.e., in the y-axis direction as depicted in FIG. 3), which will be also described in more detail below.

In this regard, the fluid channel member 40 of the printhead module 30 is exposed to a force exerted by the support 91 directed along the y-axis in a direction from the inner side wall 29 to the outer side wall 24 a . This force causes the longitudinally extending tab 43 of the fluid channel member 40 on the outer side wall 24 a side of the support frame 22 to be held between the lower and upper surfaces 24 c and 24 d of the recess 24 b . This force, in combination with the other longitudinally extending tab 43 of the fluid channel member 40 being held between the top surface 29 a of the inner side wall 29 and the extending arm portions 94 of the support 91 , acts to inhibit movement of the printhead module 30 in the z-axis direction (as described in more detail later).

However, the printhead module 30 is still able to accommodate movement in the x-axis direction (i.e., along the longitudinal direction of the printhead module 30 ), which is desirable in the event that the casing 20 undergoes thermal expansion and contraction, during operation of the printing system. As the casing is typically made from an extruded metal, such as aluminium, it may undergo dimensional changes due to such materials being susceptible to thermal expansion and contraction in a thermally variable environment, such as is present in a printing unit.

That is, in order to ensure the integrity and reliability of the printhead assembly, the fluid channel member 40 of the printhead module 30 is firstly formed of material (such as LCP or the like) which will not experience substantial dimensional changes due to environmental changes thereby retaining the positional relationship between the individual printhead tiles, and the printhead module 30 is arranged to be substantially independent positionally with respect to the casing 20 (i.e., the printhead module “floats” in the longitudinal direction of the channel 21 of the casing 20 ) in which the printhead module 30 is removably mounted.

Therefore, as the printhead module is not constrained in the x-axis direction, any thermal expansion forces from the casing in this direction will not be transferred to the printhead module. Further, as the constraint in the z-axis and y-axis directions is resilient, there is some tolerance for movement in these directions. Consequently, the delicate printhead integrated circuits of the printhead modules are protected from these forces and the reliability of the printhead assembly is maintained.

Furthermore, the clipping arrangement also allows for easy assembly and disassembly of the printhead assembly by the mere “unclipping” of the PCB support(s) from the casing. In the exemplary embodiment shown in FIG. 16, a pair of extending arm portions 94 is provided; however those skilled in the art will understand that a greater or lesser number is within the scope of the present invention.

Referring again to FIGS. 16 to 17 B, the support 91 further includes a channel portion 95 in the upper portion thereof. In the exemplary embodiment illustrated, the channel portion 95 includes three channelled recesses 95 a , 95 b and 95 c . The channelled recesses 95 a , 95 b and 95 c are provided so as to accommodate three longitudinally extending electrical conductors or busbars 71 , 72 and 73 (see FIG. 2) which form the power supply 70 (see FIG. 3) and which extend along the length of the printhead assembly 10 . The busbars 71 , 72 and 73 are conductors which carry the power required to operate the printhead integrated circuits 51 and the drive electronics 100 located on the PCB 90 (shown in FIG. 18A and described in more detail later), and may be formed of copper with gold plating, for example.

In one embodiment of the present invention, three busbars are used in order to provide for voltages of Vcc (e.g., via the busbar 71 ), ground (Gnd) (e.g., via the busbar 72 ) and V+ (e.g., via the busbar 73 ). Specifically, the voltages of Vcc and Gnd are applied to the drive electronics 100 and associated circuitry of the PCB 90 , and the voltages of Vcc, Gnd and V+ are applied to the printhead integrated circuits 51 of the printhead tiles 50 . It will be understood by those skilled in the art that a greater or lesser number of busbars, and therefore channelled recesses in the PCB support can be used depending on the power requirements of the specific printing applications.

The support 91 of the present invention further includes (lower) retaining clips 96 positioned below the channel portion 95 . In the exemplary embodiment illustrated in FIG. 16, a pair of the retaining clips 96 is provided. The retaining clips 96 include a notch portion 96 a on a bottom surface thereof which serves to assist in securely mounting the PCB 90 on the support 91 . To this end, as shown in the exemplary embodiment of FIG. 18A, the PCB 90 includes a pair of slots 97 in a topmost side thereof (with respect to the mounting direction of the PCB 90 ), which align with the notch portions 96 a when mounted so as to facilitate engagement with the retaining clips 96 .

As shown in FIG. 3, the PCB 90 is snugly mounted between the notch portions 96 a of the retaining clips 96 and the afore-mentioned recessed portions 93 a and locating lugs 93 b of the base portion 93 of the support 91 . This arrangement securely holds the PCB 90 in position so as to enable reliable connection between the drive electronics 100 of the PCB 90 and the printhead integrated circuits 51 of the printhead module 30 .

Referring again to FIG. 18A, an exemplary circuit arrangement of the PCB 90 will now be described. The circuitry includes the drive electronics 100 in the form of a print engine controller (PEC) integrated circuit. The PEC integrated circuit 100 is used to drive the printhead integrated circuits 51 of the printhead module 30 in order to print information on the print media passing the printhead assembly 10 when mounted to a printing unit. The functions and structure of the PEC integrated circuit 100 are discussed in more detail later.

The exemplary circuitry of the PCB 90 also includes four connectors 98 in the upper portion thereof (see FIG. 18B) which receive lower connecting portions 81 of the flex PCBs 80 that extend from each of the printhead tiles 50 (see FIG. 6). Specifically, the corresponding ends of four of the flex PCBs 80 are connected between the PCBs 52 of four printhead tiles 50 and the four connectors 98 of the PCB 90 . In turn, the connectors 98 are connected to the PEC integrated circuit 100 so that data communication can take place between the PEC integrated circuit 100 and the printhead integrated circuits 51 of the four printhead tiles 50 .

In the above-described embodiment, one PEC integrated circuit is chosen to control four printhead tiles in order to satisfy the necessary printing speed requirements of the printhead assembly. In this manner, for a printhead assembly having 16 printhead tiles, as described above with respect to FIGS. 1 and 2, four PEC integrated circuits are required and therefore four PCB supports 91 are used. However, it will be understood by those skilled in the art that the number of PEC integrated circuits used to control a number of printhead tiles may be varied, and as such many different combinations of the number of printhead tiles, PEC integrated circuits, PCBs and PCB supports that may be employed depending on the specific application of the printhead assembly of the present invention. Further, a single PEC integrated circuit 100 could be provided to drive a single printhead integrated circuit 51 . Furthermore, more than one PEC integrated circuit 100 may be placed on a PCB 90 , such that differently configured PCBs 90 and supports 91 may be used.

It is to be noted that the modular approach of employing a number of PCBs holding separate PEC integrated circuits for controlling separate areas of the printhead advantageously assists in the easy determination, removal and replacement of defective circuitry in the printhead assembly.

The above-mentioned power supply to the circuitry of the PCB 90 and the printhead integrated circuits 51 mounted to the printhead tiles 50 is provided by the flex PCBs 80 . Specifically, the flex PCBs 80 are used for the two functions of providing data connection between the PEC integrated circuit(s) 100 and the printhead integrated circuits 51 and providing power connection between the busbars 71 , 72 and 73 and the PCB 90 and the printhead integrated circuits 51 . In order to provide the necessary electrical connections, the flex PCBs 80 are arranged to extend from the printhead tiles 50 to the PCB 90 . This may be achieved by employing the arrangement shown in FIG. 3, in which a resilient pressure plate 74 is provided to urge the flex PCBs 80 against the busbars 71 , 72 and 73 . In this arrangement, suitably arranged electrical connections are provided on the flex PCBs 80 which route power from the busbars 71 and 72 (i.e., Vcc and Gnd) to the connectors 98 of the PCB 90 and power from all of the busbars 71 , 72 and 73 (i.e., Vcc, Gnd and V+) to the PCB 52 of the printhead tiles 50 .

The pressure plate 74 is shown in more detail in FIGS. 19A to 21 . The pressure plate 74 includes a raised portion (pressure elastomer) 75 which is positioned on a rear surface of the pressure plate 74 (with respect to the mounting direction on the support 91 ), as shown in FIG. 19B, so as to be aligned with the busbars 71 , 72 and 73 , with the flex PCBs 80 lying therebetween when the pressure plate 74 is mounted on the support 91 . The pressure plate 74 is mounted to the support 91 by engaging holes 74 a with corresponding ones of (upper) retaining clips 99 of the support 91 which project from the extending arm portions 94 (see FIG. 15A) and holes 74 b with the corresponding ones of the (lower) retaining clips 96 , via tab portions 74 c thereof (see FIG. 20). The pressure plate 74 is formed so as to have a spring-like resilience which urges the flex PCBs 80 into electrical contact with the busbars 71 , 72 and 73 with the raised portion 75 providing insulation between the pressure plate 74 and the flex PCBs 80 .

As shown most clearly in FIG. 21, the pressure plate 74 further includes a curved lower portion 74 d which serves as a means of assisting the demounting of the pressure plate 74 from the support 91 .

The specific manner in which the pressure plate 74 is retained on the support 91 so as to urge the flex PCBs 80 against the busbars 71 , 72 and 73 , and the manner in which the extending arm portions 94 of the support 91 enable the above-mentioned clipping action will now be fully described with reference to FIGS. 22 and 22A to 22 E.

FIG. 22 illustrates a front schematic view of the support 91 in accordance with a exemplary embodiment of the present invention. FIG. 22A is a side sectional view taken along the line I-I in FIG. 22 with the hatched sections illustrating the components of the support 91 situated on the line I-I.

FIG. 22A particularly shows one of the upper retaining clips 99 . An enlarged view of this retaining clip 99 is shown in FIG. 22B. The retaining clip 99 is configured so that an upper surface of one of the holes 74 a of the pressure plate 74 can be retained against an upper surface 99 a and a retaining portion 99 b of the retaining clip 99 (see FIG. 21). Due to the spring-like resilience of the pressure plate 74 , the upper surface 99 a exerts a slight upwardly and outwardly directed force on the pressure plate 74 when the pressure plate 74 is mounted thereon so as to cause the upper part of the pressure plate 74 to abut against the retaining portion 99 b.

Referring now to FIG. 22C, which is a side sectional view taken along the line II-II in FIG. 22, one of the lower retaining clips 96 is illustrated. An enlarged view of this retaining clip 96 is shown in FIG. 22D. The retaining clip 96 is configured so that a tab portion 74 c of one of the holes 74 b of the pressure plate 74 can be retained against an inner surface 96 c of the retaining clip 96 (see FIG. 20). Accordingly, due to the above-described slight force exerted by the retaining clip 99 on the upper part of the pressure plate 74 in a direction away from the support 91 , the lower part of the pressure plate 74 is loaded towards the opposite direction, e.g., in an inward direction with respect to the support frame 22 . Consequently, the pressure plate 74 is urged towards the busbars 71 , 72 and 73 , which in turn serves to urge the flex PCBs 80 in the same direction via the raised portion 75 , so as to effect reliable contact with the busbars 71 , 72 and 73 .

Returning to FIG. 22C, in which one of the extending arm portions 94 is illustrated. An enlarged view of this extending arm portion 94 is shown in FIG. 22E. The extending arm portion 94 is configured so as to be substantially L-shaped, with the foot section of the L-shape located so as to fit over the inner side wall 29 of the channel 21 and the longitudinally extending tab 43 of the fluid channel member 40 of the printhead module 30 arranged thereon. As shown in FIG. 22E, the end of the foot section of the L-shape has an arced surface. This surface corresponds to the edge of a recessed portion 94 a provided in each the extending arm portions 94 , the centre of which is positioned substantially at the line II-II in FIG. 22 (see FIGS. 16 and 17B). The recessed portions 94 a are arranged so as to engage with angular lugs 43 a regularly spaced along the length of the longitudinally extending tabs 43 of the fluid channel member 40 (FIG. 4A), so as to correspond with the placement of the printhead tiles 50 , when the extending arm portions 94 are clipped over the fluid channel member 40 .

In this position, the arced edge of the recessed portion 94 a is contacted with the angled surface of the angular lugs 43 a (see FIG. 4A), with this being the only point of contact of the extending arm portion 94 with the longitudinally extending tab 43 . Although not shown in FIG. 4A, the longitudinally extending tab 43 on the other side of the fluid channel member 40 has similarly angled lugs 43 a , where the angled surface comes into contact with the upper surface 24 d of the recess 24 b on the support frame 22 .

As alluded to previously, due to this specific arrangement, at these contact points a downwardly and inwardly directed force is exerted on the fluid channel member 40 by the extending arm portion 94 . The downwardly directed force assists to constrain the printhead module 30 in the channel 21 in the z-axis direction as described earlier. The inwardly directed force also assists in constraining the printhead module 30 in the channel 21 by urging the angular lugs 43 a on the opposing longitudinally extending tab 43 of the fluid channel member 40 into the recess 24 b of the support frame 20 , where the upper surface 24 d of the recess 24 b also applies an opposing downwardly and inwardly directed force on the fluid channel member. In this regard the opposing forces act to constrain the range of movement of the fluid channel member 40 in the y-axis direction. It is to be understood that the two angular lugs 43 a shown in FIG. 4A for each of the recessed portions 94 a are merely an exemplary arrangement of the angular lugs 43 a.

Further, the angular lugs 43 a are positioned so as to correspond to the placement of the printhead tiles 50 on the upper surface of the fluid channel member 40 so that, when mounted, the lower connecting portions 81 of each of the flex PCBs 80 are aligned with the corresponding connectors 98 of the PCBs 90 (see FIGS. 6 and 18B). This is facilitated by the flex PCBs 80 having a hole 82 therein (FIG. 6) which is received by the lower retaining clip 96 of the support 91 . Consequently, the flex PCBs 80 are correctly positioned under the pressure plate 74 retained by the retaining clip 96 as described above.

Further still, as also shown in FIGS. 22C and 22E, the (upper) lug 92 of the support 91 has an inner surface 92 a which is also slightly angled from the normal of the plane of the support 91 in a direction away from the support 91 . As shown in FIG. 17B, the upper lugs 92 are formed as resilient members which are able to hinge with respect to the support 91 with a spring-like action. Consequently, when mounted to the casing 20 , a slight force is exerted against the lug 27 a of the uppermost face 27 of the support frame 22 which assists in securing the support 91 to the support frame 22 of the casing 20 by biasing the (lower) lug 92 into the recess formed between the lower part of the inner surface 25 and the lug 28 a of the arm portion 28 of the support frame 22 .

The manner in which the structure of the casing 20 is completed in accordance with an exemplary embodiment of the present invention will now be described with reference to FIGS. 1, 2, 15 A and 23 .

As shown in FIGS. 1 and 2, the casing 20 includes the aforementioned cover portion 23 which is positioned adjacent the support frame 22 . Thus, together the support frame 22 and the cover portion 23 define the two-piece outer housing of the printhead assembly 10 . The profile of the cover portion 23 is as shown in FIG. 23.

The cover portion 23 is configured so as to be placed over the exposed PCB 90 mounted to the PCB support 91 which in turn is mounted to the support frame 22 of the casing 20 , with the channel 21 thereof holding the printhead module 30 . As a result, the cover portion 23 encloses the printhead module 30 within the casing 20 .

The cover portion 23 includes a longitudinally extending tab 23 a on a bottom surface thereof (with respect to the orientation of the printhead assembly 10 ) which is received in the recessed portion 28 c formed between the lug 28 b and the curved end portion 28 d of the arm portion 28 of the support frame 22 (see FIG. 15A). This arrangement locates and holds the cover portion 23 in the casing 20 with respect to the support frame 22 . The cover portion 23 is further held in place by affixing the end plate 111 or the end housing 120 via the end plate 110 on the longitudinal side thereof using screws through threaded portions 23 b (see FIGS. 23, 29 and 39 ). The end plates 110 and/or 111 are also affixed to the support frame 22 on either longitudinal side thereof using screws through threaded portions 22 a and 22 b provided in the internal cavity 26 (see FIGS. 15A, 29 and 39 ). Further, the cover portion 23 has the profile as shown in FIG. 23, in which a cavity portion 23 c is arranged at the inner surface of the cover portion 23 (with respect to the inward direction on the printhead assembly 10 ) for accommodating the pressure plate(s) 74 mounted to the PCB support(s) 91 .

Further, the cover portion may also include fin portions 23 d (see also FIG. 3) which are provided for dissipating heat generated by the PEC integrated circuits 100 during operation thereof. To facilitate this the inner surface of the cover portion 23 may also be provided with a heat coupling material portion (not shown) which physically contacts the PEC integrated circuits 100 when the cover portion 23 is attached to the support frame 22 . Further still, the cover portion 23 may also function to inhibit electromagnetic interference (EMI) which can interfere with the operation of the dedicated electronics of the printhead assembly 10 .

The manner in which a plurality of the PCB supports 91 are assembled in the support frame 22 to provide a sufficient number of PEC integrated circuits 100 per printhead module 30 in accordance with one embodiment of the present invention will now be described with reference to FIGS. 16 and 24 to 27 .

As described earlier, in one embodiment of the present invention, each of the supports 91 is arranged to hold one of the PEC integrated circuits 100 which in turn drives four printhead integrated circuits 51 . Accordingly, in a printhead module 30 having 16 printhead tiles, for example, four PEC integrated circuits 100 , and therefore four supports 91 are required. For this purpose, the supports 91 are assembled in an end-to-end manner, as shown in FIG. 24, so as to extend the length of the casing 20 , with each of the supports 91 being mounted and clipped to the support frame 22 and printhead module 30 as previously described. In such a way, the single printhead module 30 of sixteen printhead tiles 50 is securely held to the casing 20 along the length thereof.

As shown more clearly in FIG. 16, the supports 91 further include raised portions 91 a and recessed portions 91 b at each end thereof. That is, each edge region of the end walls of the supports 91 include a raised portion 91 a with a recessed portion 91 b formed along the outer edge thereof. This configuration produces the abutting arrangement between the adjacent supports 91 shown in FIG. 24.

This arrangement of two abutting recessed portions 91 b with one raised portion 91 a at either side thereof forms a cavity which is able to receive a suitable electrical connecting member 102 therein, as shown in cross-section in FIG. 25. Such an arrangement enables adjacent PCBs 90 , carried on the supports 91 to be electrically connected together so that data signals which are input from either or both ends of the plurality of assembled supports 91 , i.e., via data connectors (described later) provided at the ends of the casing 20 , are routed to the desired PEC integrated circuits 100 , and therefore to the desired printhead integrated circuits 51 .

To this end, the connecting members 102 provide electrical connection between a plurality of pads provided at edge contacting regions on the underside of each of the PCBs 90 (with respect to the mounting direction on the supports 91 ). Each of these pads is connected to different regions of the circuitry of the PCB 90 . FIG. 26 illustrates the pads of the PCBs as positioned over the connecting member 102 . Specifically, as shown in FIG. 26, the plurality of pads are provided as a series of connection strips 90 a and 90 b in a substantially central region of each edge of the underside of the PCBs 90 .

As mentioned above, the connecting members 102 are placed in the cavity formed by the abutting recessed portions 91 b of adjacent supports 91 (see FIG. 25), such that when the PCBs 90 are mounted on the supports 91 , the connection strips 90 a of one PCB 90 and the connection strips 90 b of the adjacent PCB 90 come into contact with the same connecting member 102 so as to provide electrical connection therebetween.

To achieve this, the connecting members 102 may each be formed as shown in FIG. 27 to be a rectangular block having a series of conducting strips 104 provided on each surface thereof. Alternatively, the conducting strips 104 may be formed on only one surface of the connecting members 102 as depicted in FIGS. 25 and 26. Such a connecting member may typically be formed of a strip of silicone rubber printed to provide sequentially spaced conductive and non-conductive material strips. A shown in FIG. 27, these conducting strips 104 are provided in a 2:1 relationship with the connecting strips 90 a and 90 b of the PCBs 90 . That is, twice as many of the conducting strips 104 are provided than the connecting strips 90 a and 90 b , with the width of the conducting strips 104 being less than half the width of the connecting strips 90 a and 90 b . Accordingly, any one connecting strip 90 a or 90 b may come into contact with one or both of two corresponding conducting strips 104 , thus minimising alignment requirements between the connecting members 104 and the contacting regions of the PCBs 90 .

In one embodiment of the present invention, the connecting strips 90 a and 90 b are about 0.4 mm wide with a 0.4 mm spacing therebetween, so that two thinner conducting strips 104 can reliably make contact with only one each of the connecting strips 90 a and 90 b whilst having a sufficient space therebetween to prevent short circuiting. The connecting strips 90 a and 90 b and the conducting strips 104 may be gold plated so as to provide reliable contact. However, those skilled in the art will understand that use of the connecting members and suitably configured PCB supports is only one exemplary way of connecting the PCBs 90 , and other types of connections are within the scope of the present invention.

Additionally, the circuitry of the PCBs 90 is arranged so that a PEC integrated circuit 100 of one of the PCB 90 of an assembled support 91 can be used to drive not only the printhead integrated circuits 51 connected directly to that PCB 90 , but also those of the adjacent PCB(s) 90 , and further of any non-adjacent PCB(s) 90 . Such an arrangement advantageously provides the printhead assembly 10 with the capability of continuous operation despite one of the PEC integrated circuits 100 and/or PCBs 90 becoming defective, albeit at a reduced printing speed.

In accordance with the above-described scalability of the printhead assembly 10 of the present invention, the end-to-end assembly of the PCB supports 91 can be extended up to the required length of the printhead assembly 10 due to the modularity of the supports 91 . For this purpose, the busbars 71 , 72 and 73 need to be extended for the combined length of the plurality of PCB supports 91 , which may result in insufficient power being delivered to each of the PCBs 90 when a relatively long printhead assembly 10 is desired, such as in wide format printing applications.

In order to minimise power loss, two power supplies can be used, one at each end of the printhead assembly 10 , and a group of busbars 70 from each end may be employed. The connection of these two busbar groups, e.g., substantially in the centre of the printhead assembly 10 , is facilitated by providing the exemplary connecting regions 71 a , 72 a and 73 a shown in FIG. 28.

Specifically, the busbars 71 , 72 and 73 are provided in a staggered arrangement relative to each other and the end regions thereof are configured with the rebated portions shown in FIG. 28 as connecting regions 71 a , 72 a and 73 a . Accordingly, the connecting regions 71 a , 72 a and 73 a of the first group of busbars 70 overlap and are engaged with the connecting regions 71 a , 72 a and 73 a of the corresponding ones of the busbars 71 , 72 and 73 of the second group of busbars 70 .

The manner in which the busbars are connected to the power supply and the arrangements of the end plates 110 and 111 and the end housing(s) 120 which house these connections will now be described with reference to FIGS. 1, 2 and 29 to 39 .

FIG. 29 illustrates an end portion of an exemplary printhead assembly according to one embodiment of the present invention similar to that shown in FIG. 1. At this end portion, the end housing 120 is attached to the casing 20 of the printhead assembly 10 via the end plate 110 .

The end housing and plate assembly houses connection electronics for the supply of power to the busbars 71 , 72 and 73 and the supply of data to the PCBs 90 . The end housing and plate assembly also houses connections for the internal fluid delivery tubes 6 to external fluid delivery tubes (not shown) of the fluid supply of the printing system to which the printhead assembly 10 is being applied.

These connections are provided on a connector arrangement 115 as shown in FIG. 30. FIG. 30 illustrates the connector arrangement 115 fitted to the end plate 110 which is attached, via screws as described earlier, to an end of the casing 20 of the printhead assembly 10 according to one embodiment of the present invention. As shown, the connector arrangement 115 includes a power supply connection portion 116 , a data connection portion 117 and a fluid delivery connection portion 118 . Terminals of the power supply connection portion 116 are connected to corresponding ones of three contact screws 116 a , 116 b , 116 c provided so as to each connect with a corresponding one of the busbars 71 , 72 and 73 . To this end, each of the busbars 71 , 72 and 73 is provided with threaded holes in suitable locations for engagement with the contact screws 116 a , 116 b , 116 c . Further, the connection regions 71 a , 72 a and 73 a (see FIG. 28) may also be provided at the ends of the busbars 71 , 72 and 73 which are to be in contact with the contact screws 116 a , 116 b , 116 c so as to facilitate the engagement of the busbars 71 , 72 and 73 with the connector arrangement 115 , as shown in FIG. 31.

In FIGS. 30, 32A and 32 B, only three contact screws or places for three contact screws are shown, one for each of the busbars. However, the use of a different number of contact screws is within the scope of the present invention. That is, depending on the amount of power being routed to the busbars, in order to provide sufficient power contact it may be necessary to provide two or more contact screws for each busbar (see, for example, FIGS. 33B and 33C). Further, as mentioned earlier a greater or lesser number of busbars may be used, and therefore a corresponding greater of lesser number of contact screws. Further still, those skilled in the art will understand that other means of contacting the busbars to the power supply via the connector arrangements as are typical in the art, such as soldering, are within the scope of the present invention.

The manner in which the power supply connection portion 116 and the data connection portion 117 are attached to the connector arrangement 115 is shown in FIGS. 32A and 32B. Further, connection tabs 118 a of the fluid delivery connection portion 118 are attached at holes 115 a of the connector arrangement 115 so as that the fluid delivery connection portion 118 overlies the data connection portion 117 with respect to the connector arrangement 115 (see FIGS. 30 and 32C).

As seen in FIGS. 30 and 32C, seven internal and external tube connectors 118 b and 118 c are provided in the fluid delivery connection portion 118 in accordance with the seven internal fluid delivery tubes 6 . That is, as shown in FIG. 34, the fluid delivery tubes 6 connect between the internal tube connectors 118 b of the fluid delivery connection portion 118 and the seven tubular portions 47 b or 48 b of the fluid delivery connector 47 or 48 . As stated earlier, those skilled in the art clearly understand that the present invention is not limited to this number of fluid delivery tubes, etc.

Returning to FIGS. 32A and 32B, the connector arrangement 115 is shaped with regions 115 b and 115 c so as to be received by the casing 20 in a manner which facilitates connection of the busbars 71 , 72 and 73 to the contact screws 116 a , 116 b and 116 c of the power supply connection portion 116 via region 115 b and connection of the end PCB 90 of the plurality of PCBs 90 arranged on the casing 20 to the data connection portion 117 via region 115 c.

The region 115 c of the connector arrangement 115 is advantageously provided with connection regions (not shown) of the data connection portion 117 which correspond to the connection strips 90 a or 90 b provided at the edge contacting region on the underside of the end PCB 90 , so that one of the connecting members 102 can be used to connect the data connections of the data connection portion 117 to the end PCB 90 , and thus all of the plurality of PCBs 90 via the connecting members 102 provided therebetween.

This is facilitated by using a support member 112 as shown in FIG. 33A, which has a raised portion 112 a and a recessed portion 112 b at one edge thereof which is arranged to align with the raised and recessed portions 91 a and 91 b , respectively, of the end PCB support 91 (see FIG. 24). The support member 112 is attached to the rear surface of the end PCB support 91 by engaging a tab 112 c with a slot region 91 c on the rear surface of the end PCB support 91 (see FIG. 17B), and the region 115 c of the connector arrangement 115 is retained at upper and lower side surfaces thereof by clip portions 112 d of the support member 112 so as that the connection regions of the region 115 c are in substantially the same plane as the edge contacting regions on the underside of the end PCB 90 .

Thus, when the end plate 110 is attached to the end of the casing 20 , an abutting arrangement is formed between the recessed portions 112 b and 91 b , similar to the abutting arrangement formed between the recessed portions 91 b of the adjacent supports 91 of FIG. 24. Accordingly, the connecting member 102 can be accommodated compactly between the end PCB 90 and the region 115 c of the connector arrangement 115 . This arrangement is shown in FIGS. 33B and 33C for another type of connector arrangement 125 with a corresponding region 125 c , which is described in more detail below with respect to FIGS. 37, 38A and 38 B.

This exemplary manner of connecting the data connection portion 117 to the end PCB 90 contributes to the modular aspect of the present invention, in that it is not necessary to provide differently configured PCBs 90 to be arranged at the longitudinal ends of the casing 20 and the same method of data connection can be retained throughout the printhead assembly 10 . It will be understood by those skilled in the art however that the provision of additional or other components to connect the data connection portion 117 to the end PCB 90 is also included in the scope of the present invention.

Returning to FIG. 30, it can be seen that the end plate 110 is shaped so as to conform with the regions 115 b and 115 c of the connector arrangement 115 , such that these regions can project into the casing 20 for connection to the busbars 71 , 72 and 73 and the end PCB 90 , and so that the busbars 71 , 72 and 73 can extend to contact screws 116 a , 116 b and 116 c provided on the connector arrangement 115 . This particular shape of the end plate 110 is shown in FIG. 35A, where regions 110 a and 110 b of the end plate 110 correspond with the regions 115 b and 115 c of the connector arrangement 115 , respectively. Further, a region 110 c of the end plate 110 is provided so as to enable connection between the internal fluid delivery tubes 6 and the fluid delivery connectors 47 and 48 of the printhead module 30 .

The end housing 120 is also shaped as shown in FIG. 35A, so as to retain the power supply, data and fluid delivery connection portions 116 , 117 and 118 so that external connection regions thereof, such as the external tube connector 118 c of the fluid delivery connection portion 118 shown in FIG. 32C, are exposed from the printhead assembly 10 , as shown in FIG. 29.

FIG. 35B illustrates the end plate 110 and the end housing 120 which may be provided at the other end of the casing 20 of the printhead assembly 10 according to an exemplary embodiment of the present invention. The exemplary embodiment shown in FIG. 35B, for example, corresponds to a situation where an end housing is provided at both ends of the casing so as to provide power supply and/or fluid delivery connections at both ends of the printhead assembly. Such an exemplary printhead assembly is shown in FIG. 36, and corresponds, for example, to the above-mentioned exemplary application of wide format printing, in which the printhead assembly is relatively long.

To this end, FIG. 37 illustrates the end housing and plate assembly for the other end of the casing with the connector arrangement 125 housed therein. The busbars 71 , 72 and 73 are shown attached to the connector arrangement 125 for illustration purposes. As can be seen, the busbars 71 , 72 and 73 are provided with connection regions 71 a , 72 a and 73 a for engagement with connector arrangement 125 , similar to that shown in FIG. 31 for the connector arrangement 115 . The connector arrangement 125 is illustrated in more detail in FIGS. 38A and 38B.

As can be seen from FIGS. 38A and 38B, like the connector arrangement 115 , the connector arrangement 125 holds the power supply connection portion 116 and includes places for contact screws for contact with the busbars 71 , 72 and 73 , holes 125 a for retaining the clips 118 a of the fluid delivery portion 118 (not shown), and regions 125 b and 125 c for extension into the casing 20 through regions 110 a and 110 b of the end plate 110 , respectively. However, unlike the connector arrangement 115 , the connector arrangement 125 does not hold the data connection portion 117 and includes in place thereof a spring portion 125 d.

This is because, unlike the power and fluid supply in a relatively long printhead assembly application, it is only necessary to input the driving data from one end of the printhead assembly. However, in order to input the data signals correctly to the plurality of PEC integrated circuits 100 , it is necessary to terminate the data signals at the end opposite to the data input end. Therefore, the region 125 c of the connector arrangement 125 is provided with termination regions (not shown) which correspond with the edge contacting regions on the underside of the end PCB 90 at the terminating end. These termination regions are suitably connected with the contacting regions via a connecting member 102 , in the manner described above.

The purpose of the spring portion 125 d is to maintain these terminal connections even in the event of the casing 20 expanding and contracting due to temperature variations as described previously, any effect of which may exacerbated in the longer printhead applications. The configuration of the spring portion 125 d shown in FIGS. 38A and 38B, for example, enables the region 125 c to be displaced through a range of distances from a body portion 125 e of the connector arrangement 125 , whilst being biased in a normal direction away from the body portion 125 e . The spring portion is formed in the connector arrangement 125 by removing a section of the material making up the body portion 125 e.

Thus, when the connector arrangement 125 is attached to the end plate 110 , which in turn has been attached to the casing 20 , the region 125 c is brought into abutting contact with the adjacent edge of the end PCB 90 in such a manner that the spring portion 125 d experiences a pressing force on the body of the connector arrangement 125 , thereby displacing the region 125 c from its rest position toward the body portion 125 e by a predetermined amount. This arrangement ensures that in the event of any dimensional changes of the casing 20 via thermal expansion and contraction thereof, the data signals remain terminated at the end of the plurality of PCBs 90 opposite to the end of data signal input as follows.

The PCB supports 91 are retained on the support frame 22 of the casing 20 so as to “float” thereon, similar to the manner in which the printhead module(s) 30 “float” on the channel 21 as described earlier. Consequently, since the supports 91 and the fluid channel members 40 of the printhead modules 30 are formed of similar materials, such as LCP or the like, which have the same or similar coefficients of expansion, then in the event of any expansion and contraction of the casing 20 , the supports 91 retain their relative position with the printhead module(s) 30 via the clipping of the extending arm portions 94 .

Therefore, each of the supports 91 retain their adjacent connections via the connecting members 102 , which is facilitated by the relatively large overlap of the connecting members 102 and the connection strips 90 a and 90 b of the PCBs 90 as shown in FIG. 27. Accordingly, since the PCBs 90 , and therefore the supports 91 to which they are mounted, are biased towards the connector arrangement 115 by the spring portion 125 d of the connector arrangement 125 , then should the casing 20 expand and contract, any gaps which might otherwise form between the connector arrangements 115 and 125 and the end PCBs 90 are prevented, due to the action of the spring portion 125 d.

Accommodation for any expansion and contraction is also facilitated with respect to the power supply by the connecting regions 71 a , 72 a and 73 a of the two groups of busbars 70 which are used in the relatively long printhead assembly application. This is because, these connecting regions 71 a , 72 a and 73 a are configured so that the overlap region between the two groups of busbars 70 allows for the relative movement of the connector arrangements 115 and 125 to which the busbars 71 , 72 and 73 are attached whilst maintaining a connecting overlap in this region.

In the examples illustrated in FIGS. 30, 33B, 33 C and 37 , the end sections of the busbars 71 , 72 and 73 are shown connected to the connector arrangements 115 and 125 (via the contact screws 116 a , 116 b and 116 c ) on the front surface of the connector arrangements 115 and 125 (with respect to the direction of mounting to the casing 20 ). Alternatively, the busbars 71 , 72 and 73 can be connected at the rear surfaces of the connector arrangements 115 and 125 . In such an alternative arrangement, even though the busbars 71 , 72 and 73 thus connected may cause the connector arrangements 115 and 125 be slightly displaced toward the cover portion 23 , the regions 115 c and 125 c of the connector arrangements 115 and 125 are maintained in substantially the same plane as the edge contacting regions of the end PCBs 90 due to the clip portions 112 d of the support members 112 which retain the upper and lower side surfaces of the regions 115 c and 125 c.

Printed circuit boards having connecting regions printed in discrete areas may be employed as the connector arrangements 115 and 125 in order to provide the various above-described electrical connections provided thereby.

FIG. 39 illustrates the end plate 111 which may be attached to the other end of the casing 20 of the printhead assembly 10 according to an exemplary embodiment of the present invention, instead of the end housing and plate assemblies shown in FIGS. 35A and 35B. This provides for a situation where the printhead assembly is not of a length which requires power and fluid to be supplied from both ends. For example, in an A4-sized printing application where a printhead assembly housing one printhead module of 16 printhead tiles may be employed.

In such a situation therefore, since it is unnecessary specifically to provide a connector arrangement at the end of the printhead module 30 which is capped by the capping member 49 , then the end plate 111 can be employed which serves to securely hold the support frame 22 and cover portion 23 of the casing 20 together via screws secured to the threaded portions 22 a , 22 b and 23 b thereof, in the manner already described (see also FIG. 2).

Further, if it is necessary to provide data signal termination at this end of the plurality of PCBs 90 , then the end plate 111 can be provided with a slot section (not shown) on the inner surface thereof (with respect to the mounting direction on the casing 20 ), which can support a PCB (not shown) having termination regions which correspond with the edge contacting regions of the end PCB 90 , similar to the region 125 c of the connector arrangement 125 . Also similarly, these termination regions may be suitably connected with the contacting regions via a support member 112 and a connecting member 102 . This PCB may also include a spring portion between the termination regions and the end plate 111 , similar to the spring portion 125 d of the connector arrangement 125 , in case expansion and contraction of the casing 20 may also cause connection problems in this application.

With either the attachment of the end housing 120 and plate 110 assemblies to both ends of the casing 20 or the attachment of the end housing 120 and plate 110 assembly to one end of the casing 20 and the end plate 111 to the other end, the structure of the printhead assembly according to the present invention is completed.

The thus-assembled printhead assembly can then be mounted to a printing unit to which the assembled length of the printhead assembly is applicable. Exemplary printing units to which the printhead module and printhead assembly of the present invention is applicable are as follows.

For a home office printing unit printing on A4 and letter-sized paper, a printhead assembly having a single printhead module comprising 11 printhead integrated circuits can be used to present a printhead width of 224 mm. This printing unit is capable of printing at approximately 60 pages per minute (ppm) when the nozzle speed is about 20 kHz. At this speed a maximum of about 1690×10 ⁶ drops or about 1.6896 ml of ink is delivered per second for the entire printhead. This results in a linear printing speed of about 0.32 ms ⁻¹ or an area printing speed of about 0.07 sqms ⁻¹ . A single PEC integrated circuit can be used to drive all 11 printhead integrated circuits, with the PEC integrated circuit calculating about 1.8 billion dots per second.

For a printing unit printing on A3 and tabloid-sized paper, a printhead assembly having a single printhead module comprising 16 printhead integrated circuits can be used to present a printhead width of 325 mm. This printing unit is capable of printing at approximately 120 ppm when the nozzle speed is about 55 kHz. At this speed a maximum of about 6758×10 ⁶ drops or about 6.7584 ml of ink is delivered per second for the entire printhead. This results in a linear printing speed of about 0.87 ms ⁻¹ or an area printing speed of about 0.28 sqms ⁻¹ . Four PEC integrated circuits can be used to each drive four of the printhead integrated circuits, with the PEC integrated circuits collectively calculating about 7.2 billion dots per second.

For a printing unit printing on a roll of wallpaper, a printhead assembly having one or more printhead modules providing 36 printhead integrated circuits can be used to present a printhead width of 732 mm. When the nozzle speed is about 55 kHz, a maximum of about 15206×10 ⁶ drops or about 15.2064 ml of ink is delivered per second for the entire printhead. This results in a linear printing speed of about 0.87 ms ⁻¹ or an area printing speed of about 0.64 sqms ⁻¹ . Nine PEC integrated circuits can be used to each drive four of the printhead integrated circuits, with the PEC integrated circuits collectively calculating about 16.2 billion dots per second.

For a wide format printing unit printing on a roll of print media, a printhead assembly having one or more printhead modules providing 92 printhead integrated circuits can be used to present a printhead width of 1869 mm. When the nozzle speed is in a range of about 15 to 55 kHz, a maximum of about 10598×10 ⁶ to 38861×10 ⁶ drops or about 10.5984 to 38.8608 ml of ink is delivered per second for the entire printhead. This results in a linear printing speed of about 0.24 to 0.87 ms ⁻¹ or an area printing speed of about 0.45 to 1.63 sqms ⁻¹ . At the lower speeds, six PEC integrated circuits can be used to each drive 16 of the printhead integrated circuits (with one of the PEC integrated circuits driving 12 printhead integrated circuits), with the PEC integrated circuits collectively calculating about 10.8 billion dots per second. At the higher speeds, 23 PEC integrated circuits can be used each to drive four of the printhead integrated circuits, with the PEC integrated circuits collectively calculating about 41.4 billions dots per second.

For a “super wide” printing unit printing on a roll of print media, a printhead assembly having one or more printhead modules providing 200 printhead integrated circuits can be used to present a printhead width of 4064 mm. When the nozzle speed is about 15 kHz, a maximum of about 23040×10 ⁶ drops or about 23.04 ml of ink is delivered per second for the entire printhead. This results in a linear printing speed of about 0.24 ms ⁻¹ or an area printing speed of about 0.97 sqms ⁻¹ . Thirteen PEC integrated circuits can be used to each drive 16 of the printhead integrated circuits (with one of the PEC integrated circuits driving eight printhead integrated circuits), with the PEC integrated circuits collectively calculating about 23.4 billion dots per second.

For the above exemplary printing unit applications, the required printhead assembly may be provided by the corresponding standard length printhead module or built-up of several standard length printhead modules. Of course, any of the above exemplary printing unit applications may involve duplex printing with simultaneous double-sided printing, such that two printhead assemblies are used each having the number of printhead tiles given above. Further, those skilled in the art understand that these applications are merely examples and the number of printhead integrated circuits, nozzle speeds and associated printing capabilities of the printhead assembly depends upon the specific printing unit application.

Print Engine Controller

The functions and structure of the PEC integrated circuit applicable to the printhead assembly of the present invention will now be discussed with reference to FIGS. 40 to 42 .

In the above-described exemplary embodiments of the present invention, the printhead integrated circuits 51 of the printhead assembly 10 are controlled by the PEC integrated circuits 100 of the drive electronics 100 . One or more PEC integrated circuits 100 is or are provided in order to enable pagewidth printing over a variety of different sized pages. As described earlier, each of the PCBs 90 supported by the PCB supports 91 has one PEC integrated circuit 100 which interfaces with four of the printhead integrated circuits 51 , where the PEC integrated circuit 100 essentially drives the printhead integrated circuits 51 and transfers received print data thereto in a form suitable for printing.

An exemplary PEC integrated circuit which is suited to driving the printhead integrated circuits of the present invention is described in the Applicant's co-pending U.S. patent application Ser. Nos. 09/575,108; 09/575,109; 09/575,110; 09/606,999; 09/607,985; and 09/607,990, the dislcosures of which are all incorporated herein by reference.

Referring to FIG. 40, the data flow and functions performed by the PEC integrated circuit 100 will be described for a situation where the PEC integrated circuit 100 is suited to driving a printhead assembly having a plurality of printhead modules 30 . As described above, the printhead module 30 of one embodiment of the present invention utilises six channels of fluid for printing. These are:

• • Cyan, Magenta and Yellow (CMY) for regular colour printing;
  • Black (K) for black text and other black or greyscale printing;
  • Infrared (IR) for tag-enabled applications; and
  • Fixative (F) to enable printing at high speed.

As shown in FIG. 40, documents are typically supplied to the PEC integrated circuit 100 by a computer system or the like, having Raster Image Processor(s) (RIP(s)), which is programmed to perform various processing steps 131 to 134 involved in printing a document prior to transmission to the PEC integrated circuit 100 . These steps typically involve receiving the document data (step 131 ) and storing this data in a memory buffer of the computer system (step 132 ), in which page layouts may be produced and any required objects may be added. Pages from the memory buffer are rasterized by the RIP (step 133 ) and are then compressed (step 134 ) prior to transmission to the PEC integrated circuit 100 . Upon receiving the page data, the PEC integrated circuit 100 processes the data so as to drive the printhead integrated circuits 51 .

Due to the page-width nature of the printhead assembly of the present invention, each page must be printed at a constant speed to avoid creating visible artifacts. This means that the printing speed cannot be varied to match the input data rate. Document rasterization and document printing are therefore decoupled to ensure the printhead assembly has a constant supply of data. In this arrangement, a page is not printed until it is fully rasterized, and in order to achieve a high constant printing speed a compressed version of each rasterized page image is stored in memory. This decoupling also allows the RIP(s) to run ahead of the printer when rasterizing simple pages, buying time to rasterize more complex pages.

Because contone colour images are reproduced by stochastic dithering, but black text and line graphics are reproduced directly using dots, the compressed page image format contains a separate foreground bi-level black layer and background contone col