# Patent

## Title
Printhead assembly with reference features

## Abstract

A printhead assembly comprises at least one printhead integrated circuit having a plurality of ink ejection nozzles; and an ink distribution support mounting the at least one printhead integrated circuit, the ink distribution support being arranged to distribute ink to the nozzles, the printhead assembly being arranged to be mounted to a printer at the ink distribution support. The ink distribution support is provided with a plurality of reference features, the plurality of reference features serving to provide information on the location of the nozzles upon mounting of the printhead assembly to the printer. The plurality of reference features include a flat surface provided at each corner of the ink distribution support, and a slot in a mounting zone of the ink distribution support.

## Background
FIELD OF THE INVENTION
The present invention relates a printhead assembly for an inkjet printer which is configured to reference itself with respect to the printer to which it is mounted.
CO-PENDING APPLICATIONS

















7,445,311
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7,513,603
7,467,852
7,465,045









CROSS REFERENCES TO RELATED APPLICATIONS
Various methods, systems and apparatus relating to the present invention are disclosed in the following US patents/patent applications filed by the applicant or assignee of the present invention:

















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BACKGROUND OF THE INVENTION
The position of the ink ejection nozzles of the printhead integrated circuit (IC) must be known to accurately print. In known printing cartridges marks referencing the position of the printhead ICs of the cartridge are provided on the body of the cartridge. Communication of these marks with the printer body is used to determine to position of the nozzles. However, referencing the nozzles in this way fails to take account of misalignment and movement of the printhead ICs relative to the cartridge body. In systems requiring low nozzle alignment tolerances, such as color inkjet printers for digital photo printing, such discrepancies can be detrimental to print quality.
SUMMARY OF THE INVENTION
According to an aspect of the invention, a printhead assembly comprises at least one printhead integrated circuit having a plurality of ink ejection nozzles; and an ink distribution support mounting the at least one printhead integrated circuit, the ink distribution support being arranged to distribute ink to the nozzles, the printhead assembly being arranged to be mounted to a printer at the ink distribution support. The ink distribution support is provided with a plurality of reference features, the plurality of reference features serving to provide information on the location of the nozzles upon mounting of the printhead assembly to the printer. The plurality of reference features include a flat surface provided at each corner of the ink distribution support, and a slot in a mounting zone of the ink distribution support.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a top elevational perspective view of a printhead cartridge of a printer;
FIG. 2 shows a bottom elevational perspective view of the printhead cartridge;
FIG. 3 shows a perspective view of the printer;
FIG. 4 shows a cross-sectional view of the printer taken along the line I-I of FIG. 3;
FIG. 5 shows an exploded view of the printhead cartridge;
FIG. 6 shows an isolated view of a printhead of the printhead cartridge;
FIG. 7 illustrates an arrangement of printhead integrated circuits of the printhead;
FIG. 8 illustrates an arrangement of ink ejection nozzles of the printhead integrated circuits;
FIG. 9 illustrates a nozzle triangle of the printhead;
FIG. 10 illustrates data and power connections between the printhead cartridge and a cradle unit of the printer;
FIG. 11 shows a top elevational, partial cross-sectional view of the printhead taken about line II-II of FIG. 6;
FIG. 12 shows a bottom elevational, partial cross-sectional view of the printhead taken about line II-II of FIG. 6;
FIG. 13 shows a side cross-sectional view of the printhead taken about line II-II of FIG. 6;
FIG. 14 shows a partial side cross-sectional view of the printhead cartridge taken about line III-III of FIG. 1;
FIG. 15 shows an isolated view of an ink supply bag of the printhead cartridge;
FIG. 16 illustrates a folded leaf spring as removed from the ink bag;
FIG. 17 illustrates the leaf spring unfolded;
FIG. 18 illustrates an alternative biasing arrangement of the ink bag;
FIGS. 19A and 19B illustrate priming of ink into the printhead and a capping position of a capper of the printhead cartridge;
FIG. 20 shows an isolated view of the capper;
FIG. 21 shows a cross-sectional view of an operational arrangement of actuator features of the capper with a capping mechanism of the printer;
FIG. 22 illustrates a non-capping position of the capper;
FIG. 23 illustrates assembly of the printhead and capper to a body of the printhead cartridge;
FIG. 24 illustrates a coordinate system of the printhead cartridge;
FIGS. 25 and 25A illustrate reference features of the printhead cartridge; and
FIGS. 26, 26A, 26B and 26C illustrate alignment of the printhead cartridge with the printer.



DETAILED DESCRIPTION OF EMBODIMENTS
A printer 100 is provided which is intended for use as a digital photo color printer and is dimensioned to print 100 millimeter by 150 millimeter (4 inch by 6 inch) photos whilst being compact in size and light in weight. As will become apparent from the following detailed description, reconfiguration and dimensioning of the printer could be carried out so as to provide for other printing purposes.
The printer 100 of the illustrated photo printer embodiment has dimensions of 18.6 cm (W); 7.6 cm (H); 16.3 cm (D), and a weight of less than two Kilograms. The compact and lightweight design of the printer provides portability and ease of use.
The printer 100 may be easily connected to a PC via USB (such as a USB 1.1 port for USB 2.0 compatible PCs) and to digital cameras and other digital photo equipment, such as electronic photo albums and cellular telephones, via USB or PictBridge. Direct printing is available when using Pictbridge compatible digital photo equipment. This enables quick and convenient printing of digital photo images.
Connection to external power is used, preferably to mains power via a 12 Volt; 2 Amp (or 24 Volt; 1 Amp) DC power converter. However, the printer may be configured to operate from an internal power source. The printer is configured to efficiently use power, operating at a maximum power consumption of 36 Watts.
The printer 100 has three core components: a printhead cartridge 200 having a printhead and ink supply; a printer or cradle unit 400 which supports the printhead cartridge and has a media transport mechanism for transporting print media past the printhead; and a media supply cartridge 600 for supplying the media to the printer.
The present invention is concerned with the printhead cartridge 200, and therefore detailed description of the cradle unit and media supply cartridge is not provided herein. A full description of a suitable cradle unit and media supply cartridge for use with the printhead cartridge 200 is described in the Applicant's simultaneously co-filed U.S. patent application Ser. Nos. 11/293,794, 11/293,839, 11/293,826, 11/293,829, 11/293,830, 11/293,827, 11/293,828, 11/293,795, 11/293,823, 11/293,824, 11/293,831, 11/293,815, 11/293,819, 11/293,881, 11/293,817 and 11/293,816, the entire contents of which are hereby incorporated by reference.
The printhead cartridge 200 is an assembly having the necessary components for operation as a printer when mounted to the printer or cradle unit having a media supply.
The printhead cartridge 200 has a body 202 which is shaped to fit securely in a complementarily shaped printhead cartridge 200 support of the cradle unit (see FIGS. 1 and 4). The body 202 of printhead cartridge 200 houses a printhead 204 and an ink supply 206 for supplying ink to the printhead 204 and has a capper 208 for capping the printhead 204 when the printhead 204 is not in use.
The printhead 204 comprises an ink distribution support 210 which is used to mount the printhead 204 to the printhead cartridge body 202 and distribute ink from the ink supply 206 arranged in the body 202 to the printhead 204. The capper 208 is also mounted to the printhead cartridge body 202 via the ink distribution support 210 so as to be located beneath the mounted printhead 204 relative to the ink supply 206. A media path 212 (see arrow of FIG. 4) is formed between the printhead 204 and the capper 208 for the transport of print media past the printhead 204 when the capper 208 is not capping the printhead 204.
In the illustrated embodiment, the printhead is a pagewidth inkjet printhead. By using a pagewidth printhead it is unnecessary to scan the printhead across print media. Rather, the printhead remains stationary with the print media being transported therepast for printing. By operating the printhead to continuously print as the print media is continuously fed past the printhead (so called ‘printing-on-the-fly’), the need to stall the media feed for each print line is obviated, therefore speeding up the printing performed.
The printer incorporating the printhead 204 of the printhead cartridge 200 is configured to print a full colour page in at most two seconds, which provides high-speed printing of about 30 pages per minute. This high speed printing is performed at high quality as well, with a resolution of at least 1600 dots per inch being provided by the printhead. Such a high resolution provides true photographic quality above the limit of the human visual system.
This is achieved by forming the printhead from thousands of ink ejection nozzles 214 across the pagewidth, e.g., about 100 millimeters for 4 inch by 6 inch photo paper. In the illustrated embodiment, the printhead incorporates 32,000 nozzles. The nozzles 214 are preferably formed as MemjetTM or microelectomechanical inkjet nozzles developed by the Applicant. Suitable versions of the MemjetTM nozzles are the subject of a number of the applicant's patent and pending patent applications, the contents of which is incorporated herein by cross reference and the details of which are provided in the cross reference table above.
Brief detail of a printhead suitable for use in the printhead cartridge 200 is now provided. The printhead is formed as a ‘linking printhead’ 216 which comprises a series of individual printhead integrated circuits (ICs) 218. A full description of the linking printhead, its control and the distribution of ink thereto is provided in the Applicant's co-pending U.S. application Ser. Nos. 11/014,769, 11/014,729, 11/014,743, 11/014,733, 11/014,754, 11/014,755, 11/014,765, 11/014,766, 11/014,740, 11/014,720, 11/014,753, 11/014,752, 11/014,744, 11/014,741, 11/014,768, 11/014,767, 11/014,718, 11/014,717, 11/014,716, 11/014,732 and 11/014,742, all filed Dec. 20, 2004 and U.S. application Ser. Nos. 11/097,268, 11/097,185, 11/097,184, all filed Apr. 4, 2005 and the entire contents of which are incorporated herein by reference. In the illustrated embodiment, the linking printhead 216 has five printhead ICs 218 arranged in series to create a printing zone 219 of a 100.9 millimeter pagewidth.
Each printhead IC incorporates a plurality of nozzles 214 positioned in rows 220 (see FIG. 7). The nozzle rows 220 correspond to associated ink colours to be ejected by the nozzles 214 in that row 220. The illustrated embodiment has ten such rows 220 arranged in groups of two adjacent rows 220a-e for five colour channels 222a-e. However, other arrangements may be used. In the illustrated arrangement, each printhead IC has 640 nozzle per row, 1280 nozzles per colour channel, 6400 nozzles per IC and therefore 32000 nozzles for the five ICs of the printhead. Of course, a different number of printhead ICs, including less or more than five printhead ICs may be used.
The nozzles 214 are arranged in terms of unit cells 224 containing one nozzle 214 and its associated wafer space. In order to provide the print resolution of 1600 dots per inch, an ink dot pitch (DP) of 15.875 microns is required. By setting each unit cell to have dimensions of twice the dot pitch wide by five times the dot pitch high and arranging the unit cells 224 in a staggered fashion as illustrated in FIG. 8, this print resolution is achieved.
Due to this necessary staggered arrangement of the nozzles 214 discontinuity is created at the interface between the adjacent printhead ICs 218. Such discontinuity will result in discontinuity in the printed product causing a reduction in print quality. Compensation of this discontinuity is provided by arranging a triangle 226 of nozzle unit cells 224 displaced by 10 dot pitches at the interface of each adjacent pair of printhead ICs 218 (see FIG. 9).
The nozzle triangles 226 allow the adjoining printhead ICs 218 to be overlapped which allows continuous horizontal spacing between dots across the multiple printhead ICs 218 along the printhead and therefore compensates for any discontinuity. The vertical offset of the nozzle triangle 226 is accounted for by delaying the data for the nozzles 214 in the nozzle triangle 226 by 10 row times. The serially arranged nozzles rows 220 and nozzle triangles 226 of the printhead ICs 218 together make up the printing zone 219 of the printhead.
The transfer of data and power to the printhead nozzles is controlled by print control circuitry of the cradle unit when the printhead cartridge 200 is inserted therein. Connection of power and data is made to the printhead 204 via engagement and electrical connection of a connection interface of the cradle unit and a connection panel 228 of the printhead cartridge 200 (see FIGS. 1 and 4).
The connection panel 228 comprises a plurality of electrical contacts 230 positioned on a flexible printed circuit board 232. The flexible printed circuit board 232 is mounted to the ink distribution support 210 so as to wrap around one longitudinal edge thereof to expose the electrical contacts 230 to the connection interface of the cradle unit and to connect the contacts to the nozzles of the printhead 204 (see FIGS. 6 and 13). The specific connections made between the printer/cradle unit and the printhead 204 are illustrated in FIG. 10. In the illustrated embodiment, 40 contacts are provided in the connection panel at a pitch of 2.54 millimeters. The power (VPOS) and data delivered via these contacts is bussed to pins of the printhead ICs 218 and a quality assurance (QA) chip 234 of the printhead cartridge 200. The QA chip 234 is provided for ink quality assurance and defines technical compatibility between the printhead cartridge 200 and printer/cradle unit.
The QA chip 234 is configured to track usage of the nozzles, the number of prints that have been performed by the printhead cartridge 200 and the amount of ink remaining in the ink supply 206. This information is used to ensure that the printhead cartridge 200 is only used by a predetermined usage model. Such a usage model limits the use-lifetime of the printhead cartridge 200 in order to maintain consistent print quality.
For example, the model may either be a page-limited model which sets the number of pages which can be printed using the printhead cartridge 200 (e.g., 200 photo pages) or an ink-limited model which sets a maximum number of pages that can be printed without depleting the ink of the (non-refillable) ink supply 206. In this way, the printhead cartridge 200 is caused to be operational within the operational lifetime of the printhead nozzles 214 and within the supply of ink for full colour printing. Other suitable models for ensuring consistent print quality may also be used.
The QA chip 234 may also be configured to store additional information related to the manufacture of the printhead cartridge 200, including manufacture date, batch number, serial number, manufacturing test results (e.g., a dead nozzle map), etc.
The print control circuitry of the cradle unit interrogates the QA chip 234 via the connection interface and connection panel to read all available information, and uses the results to control the operation of the printer.
In controlling the printhead, the print control circuitry controls the supply of firing power to the nozzles in order to control the ejection of ink onto the passing print media. Each nozzle is configured to eject an ink drop having a volume of about 1.2 picoliters and a velocity of about eight meters per second. In order to consistently eject drops having these parameters, the power routed to the printhead by the cradle unit is regulated at the connection interface. The regulated power is restricted to have variations of less than 100 millivolts in the 5.5 Volts; 3.5 Amp supplied to the printhead from the 12 Volt; 2 Amp power supply. Variations of this order have negligible effect on drop ejection and therefore the firing pulse width supplied by the print control circuitry can be constant.
Firing of the nozzles may also cause brief peaks in the current consumption. These peaks are accommodated by the inclusion of energy storage circuitry in the connection interface of the cradle unit. Further energy storage can also be provided on the printhead 204 in the form of decoupling capacitors 236 on the flexible printed circuit board 232 (see FIGS. 11 and 13).
As discussed earlier, five colour channels 222a-e are provided in the printhead 204. In the illustrated embodiment, the channels comprise two magenta ink channels, two cyan ink channels and one yellow ink channel. In order to distribute ink from the supply of the magenta, cyan and yellow inks to the nozzle rows, the ink distribution support 210 has three ink paths 238 as illustrated in FIGS. 11 to 13. The three ink paths 238 include a magenta ink path 238m, a cyan ink path 238c and a yellow ink path 238y. 
The ink paths 238 are formed by the cooperation of an upper portion 240 and a lower portion 242 of the ink distribution support 210. The upper and lower portion 240,242 are preferably molded portions having details 240a,242a for forming the ink paths 238. Preferably, the upper and lower portion are molded from liquid crystal polymer, which is inert to the ink and can be configured to have thermal expansion characteristics similar to those of silicon which is used in the printhead ICs 218. The upper and lower portion 240,242 are bonded to one another to provide a seal for the ink paths 238.
The printhead 204 is an assembly of the ink distribution support 210 and the linking printhead 216 in which the linking printhead 216 is adhesively mounted to the ink distribution support 210 by a polymer sealing film 244. The sealing film 244 has a plurality of through-holes 244a which correspond to, and align, with conduits 238a from each of the ink paths 238 to the underside of the lower portion 242 of the ink distribution support 210 and associated ink delivery inlets in the underside of each printhead IC of the linking printhead 216. The sealing film 244 provides an effective seal between the ink path 238a and the printhead ink delivery inlets to prevent the wicking and mixing of ink between the different nozzle rows and individual nozzles. It is noted that the magenta and cyan ink paths 238m and 238c each have conduits 238a for feeding ink to two of the five colour channels of the linking printhead 216.
The flexible printed circuit board 232 is mounted to a flange 246 of the upper portion 240 of the ink distribution support 210 so that contact pads 232a of the flexible printed circuit board 232 are able to communicate data and power signals to each of the printhead ICs 218 via pads provided along one edge of the printhead ICs 218 (see FIGS. 12 and 13).
A media shield 248 is also mounted to the ink distribution support 210 along the opposite edge of the linking printhead 216 to the flexible printed circuit board 232. In the illustrated embodiment, the media shield 248 is mounted via an adhesive film 250, however other arrangements are possible. The media shield 248 is configured to maintain the passing media at a predetermined distance from the nozzles 214 of the linking printhead 216. This prevents damage being caused to the nozzles by contact of the media with the nozzles. The media shield 248 is preferably a molding formed of liquid crystal polymer. As can be seen from FIG. 12, the media shield 248 is spaced from the surface of the ink distribution support 210 by details 248a. A space 248b provided by the details 248a provides the predetermined distance of the print media from the nozzles 214.
In the illustrated embodiment, the ink paths 238 of the ink distribution support 210 each have a conical or cylindrical inlet member 238b for fluid connection to an associated ink bag 252 of the ink supply 206 (see FIG. 14). Three ink bags 252 are provided, a magenta ink bag, a cyan ink bag and a yellow ink bag. The ink bags 252 are positioned in a base 202a of the body 202 of the printhead cartridge 200 which is enclosed by a lid 202b. The base and lid of the body are preferably plastics moldings having clip details for snap fitting the lid to the base.
One of the ink bags 252 is illustrated in FIG. 15. The ink bag is formed of two profiled panels 252a which are sealed together to make an ink holding chamber 252b. The ink holding chamber 252b of each ink bag is dimensioned to hold an ink volume of at least 19 milliliters up to about 23 milliliters and is configured to be collapsible so as to reduce the available ink volume. The sealed panels 252a seal about a connector assembly 254 and a folded leaf spring 256. The connector assembly 254 is used for both filling of the ink bag with the required ink volume during manufacture of the printhead cartridge 200 and connecting the ink bag 252 with the inlet member 238b of the respective ink path 238 of the ink distribution support 210.
Distribution of ink from the ink bag 252 to the ink paths 238 via the connector assembly 254 is performed through an outlet 254c of the connector assembly 254. The cylindrical outlet 254c is fitted with a coupling seal 254d which has ring details on the exterior cylindrical surface for preventing ink from leaking between the outlet's inner surface and the coupling seal, and ring details on the interior cylindrical surface for preventing ink from leaking between the coupling seal and the outer surface of the inlet member of the ink path (see FIG. 14).
Filling of the ink bag and priming of ink into the connector assembly 254 is performed by injecting ink into an access hole 254e of the connector assembly 254. Air within the ink bag/connector assembly is able to escape through an outlet 254b during filling. Once filled, a ball seal 254a seals the outlet 254b and the coupling seal 254d, which is provided with a cover seal (not shown), is positioned in the outlet 254c to seal off the access hole, as illustrated in FIG. 14. Air is undesired within the ink bag and connector assembly 254 so as to prevent air from entering the ink distribution support 210 and the nozzles 214. Air or other gases may cause printing problems due to the microscopic size of the nozzles. A suitable air filter (not shown) may also be incorporated within the connector assembly 254 to exclude any air present in the ink bag from entering the ink distribution system.
The connector assembly 254 is mounted within the interior of the cartridge body base 202a by engaging clips 254f of the connector assembly 254 with details 202c in the base 202a which sealingly engages the outlets of the connector assemblies with the inlet members 238b of the respective ink paths 238 (see FIG. 14).
The folded leaf spring 256 of each bag 252 is formed by folding an elongate plate 256a about a centrally disposed slot 256b (see FIGS. 16 and 17). The elongate plate 256a is dimensioned so that when folded it fits within the sealed ink bag 252. The elongate plate 256a is formed so as to be resilient to the folding and the folding is performed so as to create a curvature in the folded plate. This creates a folded leaf spring which is resistant to an inwardly directed force and which in turn applies an outwardly directed force. A leaf spring having a spring constant equivalent to 1.2 Newtons across an eight millimeter distance between the faces is suitable. Mylar is a suitable material for the leaf spring for its shape memory characteristics. When Mylar is used the folded leaf spring may be thermally formed. Other spring materials may be used, such as stainless steel.
The use of the leaf springs 256 within the ink bags 252 provides negative fluid pressure at the nozzles of the printhead 204 when the ink bags 252 are connected to the nozzles and the ink has been fully primed to the nozzles from the ink bags 252. Negative fluid pressure is created by the leaf spring exerting outwardly directed force on the interior walls of the ink bag panels 252a. Negative fluid pressure is desired at the nozzles to ensure that uncontrolled ejection or leakage of ink from the nozzles does not occur.
A negative pressure head of about −100 millimeters is required to effectively prevent ink from leaking at the nozzles. The illustrated leaf springs 256 may cause fluctuations in the negative pressure head as ink is depleted from the ink bags 252 and therefore the ink volume decreases.
In an alternative embodiment, coil springs or like compression springs 258 may be used in place of the leaf springs 256. The use of a suitably configured compression spring 258 within the ink bag 252, and attachment of the ink bag 252 to the underside of the lid 202b of the cartridge body 202 with suitable adhesive, ensures that a constant negative pressure head is created at the nozzles independent of the ink volume in the ink bags 252. A suitably configured compression spring, for an ink bag of area 30 millimeters by 50 millimeters, is a spring having the required free length and a spring constant of 14.7 Newtons per meter.
The required free length is a combination of a free length of 100 millimeters and the height of the printhead cartridge 200 (e.g., from the attached point of the top of the ink bag 252 to the ink ejection plane of the nozzles). In the illustrated embodiment, the printhead cartridge 200 has a height of 41 millimeters from the interior of the lid 202b to the nozzles of the printhead 204, resulting in a free length of 141 millimeters for the compression spring 258 (see FIG. 18).
In the present embodiment, the leaf springs 256 also facilitate the priming of ink from the ink bags 252 to the connected nozzles. Priming is performed before packaging of the printhead cartridge 200 for distribution, and ensures that ink is situated throughout the operational system thereby removing any air or particulate matter in the system prior to printing. In order to prime ink into each of the ink paths 238 of the ink distribution support 210 and nozzles 214, the ink bags 252 are effectively overfilled with ink. That is, the printing volume of ink within each ink bag is set to be less than a 19 milliliter volume. A priming volume of about four milliliters is needed from each ink bag for priming the system. Thus, a printing volume of at least 15 milliliters is provided in each ink bag.
In practice, an additional volume of up to four milliliters is made available in each ink bag in order to account for the inability of the ink bags to be completely collapsed due to the non-zero width of the fully folded (i.e., compressed) leaf spring.
In order to prime the priming volume into the ink paths and nozzles, force is applied with a suitable force applicator to the exterior surface of one or both panels 252a of the ink bags 252, as shown by the arrow in FIG. 19A. In order to provide effective priming, the folded leaf springs 256 are configured to contact the interior surfaces of the ink bags 252 only once the printing volume has been reached in the ink bag. That is, the leaf springs 256 effectively float within the overfilled ink bags 252 prior to priming being performed. The force applicator is arranged to apply the inwardly directed priming force until the resistance caused by the outwardly directed force of the leaf spring is encountered, as shown by the arrows in FIG. 19B. In this way, negative pressure is immediately created at the primed nozzles.
As illustrated in FIGS. 19A and 19B, a cap 260 of the capper 208 is at its capping position on the nozzles of the printhead 204 during the priming operation so as to capture any primed ink which is ejected from the nozzles during priming.
The manner in which the cap of the capper caps the printhead nozzles and the operation of the capper is described in the Applicant's co-pending U.S. patent application Ser. Nos. 11/246,676, 11/246,677, 11/246,678, 11/246,679, 11/246,680, 11/246,681, and 11/246,714, all filed Oct. 11, 2005 and the entire contents of which are hereby incorporated by reference.
For ease of understanding, a brief excerpt of the description provided in these co-pending applications is now provided.
Referring to FIGS. 19A to 22, the cap 260 of the capper 208 comprises an elastically deformable elongate pad 262 having a contact surface 262a mounted on a elongate support 264 which has lugs or actuation features 266 protruding from each longitudinal end. The support 264 is housed within an elongate housing 268 so that the lugs 266 protrude through slots 268a in the housing at each longitudinal end thereof. The housing is mounted to the ink distribution support 210 of the printhead 204 so as to align the pad 262 of the cap 260 with the printhead ICs 218 and the contact surface 262a of the pad 262 is configured to form a capping zone which is commensurate with the printing zone 219 of the printhead 204. Preferably the housing and support are formed as moldings from plastic or like material.
The support is slidably movable within the slots 268a of the housing 268, allowing the pad 262 to be slid relative to the housing 268. The extent of the pad's slidable movement is defined by the length of the slots 268a due to the contact of the lugs 266 with the slot walls. At the upper extent of movement, the cap 260 is placed in its capping position (see FIG. 21) and at the lower extent of movement, the cap 260 is placed in its non-capping position (see FIG. 22). The range of movement may be from about 1.5 millimeters to about 2.6 millimeters, thereby ensuring unobstructed passage of the print media along the media path 212.
A pair of springs 272 is fixed to the bottom wall of the housing 268 to bias the cap 260 into the capping position. In the capping position, the contact surface 262a of the pad 262, which defines the capping zone 270, sealingly engages with the nozzles 214 of the printhead 204 across the entire printing zone 219, thereby capping or covering the nozzles. This capping isolates the ink within the nozzles from the exterior, thereby preventing evaporation of water from the primed ink from the nozzles and the exposure of the nozzles to potentially fouling particulate matter during non-operation of the printhead. In the non-capping position, the contact surface 262a is disengaged from the nozzles, as illustrated in FIG. 22, allowing printing to be performed.
When the printhead cartridge 200 is mounted to the cradle unit 400, the lugs 266 of the support 264 engage with a cam 402 of a capping mechanism of the cradle unit 400, as illustrated in FIG. 21. Rotation of the cam 402, under control of the print control circuitry of the cradle unit 400, causes linear sliding movement of the support 264 and, hence, the pad 262, under control of the springs 272. Accordingly, the pad 262 may be moved reciprocally between its capping position and its non-capping position. The springs 272 are positioned to ensure that all parts of the contact surface 262a of the pad 262 move at the same rate with respect to the printhead 204.
By configuring the capper to be normally capping the printhead in its rest position, i.e., without requiring any electronic mechanism to hold the capper in its capping position, the potential of such an electronic mechanism failing, and therefore uncapping the printhead, is prevented.
As previously mentioned, the linking printhead 216 and capper 208 are commonly mounted to the body 202 of the printhead cartridge 200 via the ink distribution support 210. The ink distribution support 210 is mounted to the cartridge body 202 at mounting zones 210a of the support arranged at either longitudinal end of the printing zone 219 of the linking printhead 216 (see FIG. 6). The mounting zones 210a are formed as widened sections of the upper and lower portion 240,242 of the ink distribution support 210. These widened sections are easily molded as part of the upper and lower moldings.
The mounting zone 210a at one end of the ink distribution support 210 (e.g., the right hand end as depicted in FIG. 23) is formed with a through-hole 210b which aligns with a corresponding through-hole 268b formed in a tab 268c extending from the capper housing 268, as illustrated in FIG. 23. These through-holes 210b,268b of the ink distribution support 210 and capper 208 further align with a similarly positioned through-hole (not shown) provided in the body 202 of the printhead cartridge 200.
The mounting zone 210a at the other end of the ink distribution support 210 (e.g., the left hand end as depicted in FIG. 23) is formed with a slot 210c (see FIG. 6) which aligns with a corresponding slot 268d formed in a tab 268e extending from the capper housing 268, as illustrated in FIG. 23. These slots 210c,268d of the ink distribution support 210 and capper 208 further align with a similarly positioned slot (not shown) provided in the body 202 of the printhead cartridge 200.
A pin 274 is passed through each of the aligned holes at the first end of the printing and capping zones and is locked in place so as to fix the printhead 204 and capper 208 to the cartridge body 202 by a locking member 276, such as a clip (e.g., an E-clip is illustrated).
A second pin 278 is passed through the aligned slots at the second end of the printing and capping zones and is locked in place with a biasing member 280. The biasing member 280 is arranged to bias the cartridge body 202, printhead assembly 204 and capper 208 together at the second pin 278 whilst allowing relative movement of the cartridge body 202, printhead assembly 204 and capper 208. The illustrated biasing member is a sprung clip 280, however other arrangements may be used.
In this way, relative movement of the components of the printhead cartridge 200 is accommodated whilst maintaining a secure mount of, and proper alignment between, the components. In the illustrated embodiment, the slots are configured so as to accommodate movement along the longitudinal direction of the printhead 204 and capper 208 (i.e., in the X-direction of the coordinate system illustrated in FIG. 24). Such longitudinal movement may occur during the performance of printing due to thermal expansion of the linking printhead silicon and the ink distribution support liquid crystal polymer. As well as maintaining alignment, accommodating such thermal expansion alleviates the effect of stresses on the fragile printhead ICs.
Other slotted and/or confining arrangements are possible, so long as proper alignment of the components is maintained throughout the movement accommodated by these arrangements.
Whilst proper alignment of the printhead 204 and capper 208 are assured by the mounting arrangement, the exact position of the nozzles of the mounted printhead 204 must be known to perform high quality printing when the printhead cartridge 200 is inserted in the cradle unit 400. The requirement for this information is exacerbated by the small tolerances allowed by the 100.9 millimeter printing zone 219 of the linking printhead 216 for printing across the 100 millimeters of printable area of four inch wide photo paper.
This information is provided by the cooperation of X, Y and Z datums (in accordance with the coordinate system illustrated in FIG. 24) arranged as reference features of the printhead cartridge 200 with complementary mounting features of the cradle unit 400. A “datum” is defined as a reference position against which other features are located, within given tolerances.
In the illustrated embodiment, the three following key aspects of the printhead cartridge-cradle unit alignment are referenced to the X, Y and Z datums:
(1) the surface of the print media that the media transport mechanism of the printer presents to the printhead cartridge;
(2) the electrical contacts of the flexible printed circuit board on the printhead cartridge; and
(3) the cartridge retention points used to hold the cartridge to the cradle unit.
The cooperation of the reference features of the printhead cartridge 200 and the mounting features of the printer is arranged to restrict the movement of the printhead cartridge 200, so as to keep within the tight tolerances.
As illustrated in FIGS. 25 and 25A, the X datum corresponds to a centreline of a slot 282 in the mounting zone 210a of the ink distribution support 210 at the fixed end of the printhead 204 and capper 208 (e.g., at the right hand end as depicted in FIG. 25A) which is located immediately adjacent the flexible printed circuit board 232 (see also FIG. 6). The Y datum corresponds to a line 284 across the printhead cartridge 200 just above the electrical contacts 230 of the flexible printed circuit board 232, at which point the exterior surface of the printhead cartridge body 202 is at a slight angle to the vertical (e.g., in the illustrated embodiment a clearance angle of five degrees is provided). The Z datum corresponds to four flat surfaces 286 on the corners of the upper portion 240 of the ink distribution support 210 which face the cradle unit 400 (i.e., the corners of the underside of the upper portion 240 as depicted in FIG. 25A, which is the same surface in which the slot 282 of the X datum is defined; see also FIG. 6).
In this way, the X, Y and Z datums are located as close as possible to the printing zone 219 of the printhead 204 in order to reduce the effect of accumulated tolerances across multiple components. Providing these reference features on the printhead itself, allows the printhead to be self referencing, which in turn accommodates the aforementioned tight tolerances. Other referencing arrangements are possible so long as the small tolerances are accommodated.
An example of the manner in which these reference features cooperate with complementary mounting features of the cradle unit is illustrated in FIGS. 26, 26A, 26B and 26C. The X datum slot 282 of the printhead cartridge 200 is received in a complementary shaped mesa feature 404 situated within a cartridge receiving slot 406 of the cradle unit 400 (see FIGS. 4 and 26B). The Y datum angled surface 284 of the printhead cartridge 200 is held against a protrusion 408 situated across the cartridge receiving slot 406 of the cradle unit 400 (see FIG. 26A). The cradle unit protrusion 408 is the part of the connection interface which carries the electrical contacts of the print control circuitry and power supply for connection to the contacts 230 of the flexible printed circuit board 232. The Z datum flat surfaces 286 locate on protrusions 410 within the cartridge receiving slot 406 of the cradle unit 400 (see FIG. 26C).
By locating the X datum slot, one end of the Y datum line and two of the Z datum flat surfaces at the fixed end of the printhead and capper, the exact location of each of the reference features can be known throughout movement of the printhead and capper at the confined end. The print control circuitry of the printer uses the cooperation of these reference features of the printhead cartridge 200 with the known positions of the mounting features of the cradle unit 400 in order to control the firing of the nozzles.
Once the printhead cartridge 200 has been inserted into the cartridge receiving slot 406 of the cradle unit 400 to make the above described cooperative connections, the printhead cartridge 200 is held in place by a lid 412 of the cradle unit 400 (see FIGS. 3 and 4). In the illustrated embodiment, correct alignment and contact can be maintained by configuring the lid 412 of the cradle unit 400 to exert a vertical force of about 20 Newtons to the lid of the printhead cartridge body 202 (with a similar force being required to be exerted by a user to insert the printhead cartridge 200), and by configuring the slant angle of the printhead cartridge body 202 at the Y datum line 284 to cause the connection protrusion 408 of the cradle unit 400 to exert a horizontal force of about 45 Newtons to the electrical contacts 230 of the flexible printed circuit board 232.
In order to ensure that the printhead cartridge 200 may only be used with a printer/cradle unit which is properly configured to operate the printhead cartridge 200, it is possible to arrange a key feature 288 on the printhead cartridge 200, as illustrated in FIGS. 2 and 26, for example, which only allows the printhead cartridge 200 to be inserted into a printer/cradle unit having a complementary key feature. Such ‘branding’ of the printhead cartridge 200 and printer/cradle unit can be carried out after manufacture.
While the present invention has been illustrated and described with reference to exemplary embodiments thereof, various modifications will be apparent to and might readily be made by those skilled in the art without departing from the scope and spirit of the present invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but, rather, that the claims be broadly construed.

## Claims

1. A printhead assembly comprising:
at least one printhead integrated circuit having a plurality of ink ejection nozzles; and
an ink distribution support mounting the at least one printhead integrated circuit, the ink distribution support being arranged to distribute ink to the nozzles, the printhead assembly being arranged to be mounted to a printer at the ink distribution support,
wherein the ink distribution support is provided with a plurality of reference features, the plurality of reference features serving to provide information on the location of the nozzles upon mounting of the printhead assembly to the printer, and
the plurality of reference features include a flat surface provided at each corner of the ink distribution support, and a slot in a mounting zone of the ink distribution support.

2. The printhead assembly according to claim 1, wherein the ink distribution support is an elongate support, and the at least one printhead integrated circuit is mounted to extend longitudinally along the elongate support.

3. A printhead assembly according to claim 2, wherein the at least one printhead integrated circuit is mounted along the elongate support so that the nozzles create a printing zone which extends across a pagewidth.

4. A printhead assembly according to claim 2, wherein the elongate support is formed as a moulding, and one or more of the plurality of reference features are moulded as part of the support moulding.

5. A printhead assembly according to claim 1, wherein at least one of the plurality of reference features is configured to cooperate with a corresponding complementary feature of the printer upon mounting of the printhead assembly to the printer, the cooperation providing the information on the location of the nozzles.

6. A printhead assembly according to claim 5, wherein the complementary feature of the printer is a mesa feature configured to cooperate with the slot in the ink distribution support.