KR100753525B1 - Air supply arrangement for a printer - Google Patents

Abstract

A paper width inkjet printer is described that includes a printhead 11 having a plurality of print nozzles 30 for ejecting ink droplets to a print medium. One space is defined between the nozzle and a nozzle protector 43 having a series of holes 44 aligned along the nozzle. During the printing operation, constant pressure air is provided to this space, which is released from the space through the hole, to prevent clogging by paper dust. When not printing, the air supply is cut off by the air valve member 66, and a capping member on the rotary platen 14 contacts the print head to seal the atmosphere sealed at the surface of the nozzle. By holding, the ink dries on the nozzles.

Description

Air supply structure for printer {AIR SUPPLY ARRANGEMENT FOR A PRINTER}

The present invention relates to an air supply structure for a printer. In particular, the present invention relates to an air supply structure for a drop-on-demand printhead of A4 paper width capable of printing at resolutions up to 1600 dpi per 160 pages.

The overall design for a printer in a configuration that can be used revolves around the use of a replaceable printhead module in an array of about 8 inches (20 cm) in length. The advantage of such a system is the ability to easily remove and replace any defective modules in the printhead array. This will prevent the case where the entire printhead has to be discarded if only one chip is defective.

The printhead module in such a printer may consist of one "memjet" chip, which is a very large number of thermo-actuators in micro-mechanics and micro-electromechanical systems (MEMS). Is mounted on it. Such actuators may be as disclosed in US Pat. No. 6,044,646 by Applicant, but may also be other MEMS print chips.

As an environment in which the air supply structure of the present invention will be placed, the printhead typically has six ink chambers and will be able to perform four color (CMYK) printing processes as well as infrared ink and fixatives. .

Each printhead module receives the ink via a dispensing molding that delivers the ink. It is typical for the ten modules to work together to form a complete 8 inch printhead assembly suitable for performing printing on A4 paper without having to scan move the printhead across the paper width.

The printhead itself is modular, so that a complete 8 inch printhead arrangement can be configured to form any width printhead.

Moreover, a second printhead assembly can be mounted on the opposite side of the paper feed path to allow double-sided high speed printing.

[Application filed together]

Various methods, systems, and apparatuses of the present invention are disclosed in the following application filed concurrently with the present application by the present applicant or successor.

PCT / AU00 / 00518, PCT / AU00 / 00519, PCT / AU00 / 00520, PCT / AU00 / 00521, PCT / AU00 / 00522, PCT / AU00 / 00523, PCT / AU00 / 00524, PCT / AU00 / 00525, PCT / AU00 / 00526, PCT / AU00 / 00527, PCT / AU00 / 00528, PCT / AU00 / 00529, PCT / AU00 / 00530, PCT / AU00 / 00531, PCT / AU00 / 00532, PCT / AU00 / 00533, PCT / AU00 / 00534, PCT / AU00 / 00535, PCT / AU00 / 00536, PCT / AU00 / 00537, PCT / AU00 / 00538, PCT / AU00 / 00539, PCT / AU00 / 00540, PCT / AU00 / 00541, PCT / AU00 / 00542 , PCT / AU00 / 00543, PCT / AU00 / 00544, PCT / AU00 / 00545, PCT / AU00 / 00547, PCT / AU00 / 00546, PCT / AU00 / 00554, PCT / AU00 / 00556, PCT / AU00 / 00557, PCT / AU00 / 00558, PCT / AU00 / 00559, PCT / AU00 / 00560, PCT / AU00 / 00561, PCT / AU00 / 00562, PCT / AU00 / 00563, PCT / AU00 / 00564, PCT / AU00 / 00565, PCT / AU00 / 00566, PCT / AU00 / 00567, PCT / AU00 / 00568, PCT / AU00 / 00569, PCT / AU00 / 00570, PCT / AU00 / 00571, PCT / AU00 / 00572, PCT / AU00 / 00573, PCT / AU00 / 00574 , PCT / AU00 / 00575, PCT / AU00 / 00576, PCT / AU00 / 00577, PCT / AU00 / 00578, PCT / AU00 / 00579, PCT / AU00 / 00581, PCT / AU00 / 00580, PCT / AU00 / 00582, PCT / AU00 / 00587, PCT / AU00 / 00588, PCT / AU00 / 00589, PCT / AU00 / 00583, PCT / A U00 / 00593, PCT / AU00 / 00590, PCT / AU00 / 00591, PCT / AU00 / 00592, PCT / AU00 / 00584, PCT / AU00 / 00585, PCT / AU00 / 00586, PCT / AU00 / 00594, PCT / AU00 / 00595, PCT / AU00 / 00596, PCT / AU00 / 00597, PCT / AU00 / 00598, PCT / AU00 / 00516, PCT / AU00 / 00517, PCT / AU00 / 00511, PCT / AU00 / 00501, PCT / AU00 / 00502, PCT / AU00 / 00503, PCT / AU00 / 00504, PCT / AU00 / 00505, PCT / AU00 / 00506, PCT / AU00 / 00507, PCT / AU00 / 00508, PCT / AU00 / 00509, PCT / AU00 / 00510, PCT / AU00 / 00512, PCT / AU00 / 00513, PCT / AU00 / 00514, PCT / AU00 / 00515

The contents disclosed in the application filed as such are hereby incorporated by reference.

One object of the present invention is to provide an air supply structure of a print.

Another object of the present invention is to provide an air supply structure suitable for a paper width printhead assembly, as described broadly herein.

It is still another object of the present invention to provide an air supply structure for a printhead assembly, in which a plurality of print chips are mounted, each of which includes a plurality of MEMS print apparatuses.

It is another object of the present invention to provide a method of distributing air to a print module in a printhead assembly of a printer.

The present invention provides a printhead for an inkjet printer, which comprises a plurality of print nozzles for selectively releasing ink droplets to a print medium passing through a nozzle, and the nozzles and the prints for passing ink droplets discharged from the nozzles. It includes a space located between the media, and further includes an air supply means for supplying a positive pressure air to the space.

The space is formed between the nozzle and the nozzle guard, the nozzle guard having a plurality of apertures aligned along the nozzle such that droplets of ink ejected from the nozzle pass through the aperture to produce paper or other print media. It is preferable to settle on.

Preferably, the nozzles are arranged in an array extending across at least one A4 paper width, and the nozzles preferably also comprise a MEMS device. In addition, it is preferable that the nozzle is disposed on a plurality of print modules of the printhead together with respective nozzle protectors and spaces.

In addition, the air supply preferably includes a general air inlet, an air filter, and means for distributing air to each space. The air filter is preferably provided in the replaceable ink cassette of the printer.

The air valve assembly preferably shuts off the air supply to the space when the printer is in a non-printing mode of operation.

As used herein, the term "ink" refers to any fluid that flows through a printhead to paper. The fluid may be one of a variety of color inks, infrared inks, fixatives, and the like.

1 is a front perspective view of a print engine assembly.

FIG. 2 is a rear perspective view of the print engine assembly of FIG. 1. FIG.

3 is an exploded perspective view of the print engine assembly of FIG.

4 is a schematic front perspective view of the printhead assembly.

FIG. 5 is a schematic rear perspective view of the printhead assembly of FIG. 4. FIG.

6 is an exploded perspective view of the printhead assembly.

FIG. 7 is a front view showing an end portion of a cross section taken along the center of the print head of the print head assembly of FIGS. 4 to 6.

FIG. 8 is a front view schematically showing the end of the cross section taken along the portion close to the left end of FIG. 4 of the printhead assembly of FIGS. 4 to 6.

Fig. 9A is a front view schematically showing an end portion of a configuration in which a print chip and a nozzle guard are mounted in a stacked stack structure of a print head.                 

FIG. 9B is a front sectional view showing an end portion of the enlarged configuration of FIG. 9A.

10 is an exploded perspective view of the printhead cover assembly.

Fig. 11 is a perspective view schematically showing ink distribution molding.

Fig. 12 is an exploded perspective view showing layers forming part of the stacked ink distribution structure according to the present invention.

Fig. 13 is a sectional view from above of the structure shown in Figs. 9A and 9B.

FIG. 14 is a staged cross-sectional view of the structure shown in FIG.

Fig. 15 is a perspective view schematically showing a first layer.

Fig. 16 is a perspective view schematically illustrating the second layer.

17 is a perspective view schematically illustrating the third layer.

18 is a perspective view schematically illustrating a fourth layer.

Fig. 19 is a perspective view schematically showing a fifth layer.

20 is a perspective view showing the air valve molding.

Fig. 21 is a rear perspective view showing the right end of a platen.

Fig. 22 is a rear perspective view showing the left end of the platen.

Fig. 23 is an exploded perspective view of the platen.

Fig. 24 is a cross sectional view of the platen.

Fig. 25 is a front perspective view showing the arrangement of the optical paper sensor.

Fig. 26 is a perspective view schematically showing ink lines attached to a printhead assembly and an ink storage cassette.                 

FIG. 27 is a partial exploded view of FIG.

1 to 3 schematically show the main parts of the print engine assembly, and show a general environment in which the laminated ink distribution structure of the present invention is located. The print engine assembly includes a chassis 10 formed of pressed steel, aluminum, plastic or other hard material. The chassis 10 is mounted in the main body of the printer to perform the function of mounting the printhead assembly 11, the paper feed mechanism, and other related parts in the outer plastic casing of the printer.

In general, the chassis 10 supports the printhead assembly 11 so that ink is transported from the printhead assembly 11 down the printhead by a transfer mechanism, and then the discharge hole 19 is removed. Ejected onto paper or other print media being conveyed through. The paper feed mechanism includes a feed roller 12, a feed idler roller 13, a platen 14, a discharge roller 15, and a pin wheel assembly 16. It includes, all are driven by a stepper motor (17). The paper conveying parts are installed between a pair of bearing moldings 18, which are in turn installed at each end of the chassis 10.

The printhead assembly 11 is installed in the chassis 10 by respective printhead spacers 20 mounted to the chassis 10. The spacer molding 20 increases the length of the printhead assembly to 220 mm to allow room on either side of the paper having a width of 210 mm.                 

The structure of the printhead is shown roughly in Figures 4-8.

The printhead assembly 11 includes a 64 MB DRAM 22, a PEC chip 23, a QA chip connector 24, a microcontroller, and a dual motor driver chip 26. Various electronic components include a printed circuit board (PCB) 21 mounted thereon. The printhead has a length of 203 mm and has 10 print chips 27 (see FIG. 13), each of which typically has a length of 21 mm. The print chips 27 are each installed slightly inclined with respect to the longitudinal axis of the print head (see Fig. 12), and each of the chips has a continuous transmission of ink over the entire length of the array. To be possible, they are installed so as to overlap each other slightly. Each of the print chips 27 is electronically coupled to one end of the Tape Automated Bond (TAB) film 28, and the other end of the Tape Automated Bond (TAB) film 28 is The TAB film backing pad 29 maintains electrical contact with the bottom surface of the printed circuit board 21.

Preferred print chip structures are as described in US Pat. No. 6,044,646 by the Applicant. Each of the print chips 27 has a length of about 21 mm, a width smaller than 1 mm, and a height of about 0.3 mm, with thousands of MEMS inkjet nozzles 30 at the bottom thereof, FIGS. 9A and FIG. As schematically shown in 9b, they are generally arranged in six lines, one for each ink type. Each line of the nozzles may be arranged in a staggered pattern to allow closer dot spacing. A corresponding six line of ink passage 31 is formed extending from the back of the print chip to carry ink to the back of each nozzle. In order to protect the fragile nozzles installed on the surface of the printed chip, each of the printed chips has a nozzle guard 43, in which micro apertures 44 are aligned along the nozzle 30. ), The ink discharged at high speed from the nozzle is fixed on the paper passing through the fine holes and passing over the platen 14.

The ink is delivered to the print chip via a laminated stack 36 structure that forms part of the dispensing molding 35 and the printhead 11. The ink is integrated with the plastic duct cover 39 which forms a lid covering the top of the plastic distribution molding 35 via the respective ink hoses 38 from the ink cassettes 37 (see FIGS. 26 and 27). To each ink inlet port 34 molded into. The distribution molding 35 includes six ink ducts 40 and air ducts 41 extending over the length of the array. As shown in FIG. 7, ink is conveyed from the inflow port 34 to each ink duct 40 via each cross-flow ink channel 42. As shown in FIG. Note that although six ducts are shown, the number of the ducts is not limited to six. The six ducts are suitable for printing capable of printing infrared ink and fixing liquid as well as four-color processing (CMYK).

The air is delivered to the air duct 41 via the air inlet port 61, and is supplied to each of the print chips 27, as described later with reference to Figs. 6 to 8, 20 and 21. .                 

In the longitudinally extending stack recess 45 formed below the dispensing molding 35, a plurality of stacked layers forming the stacked ink dispensing stack 36 are located. Each layer of the stack is typically formed from a micro-molded plastic material. The TAB film 28 extends from the bottom of the printhead PCB 21 around the rear of the dispensing molding 35 and is received into each TAB film groove 46 (see FIG. 21), where a plurality of TAB film grooves ( 46 is disposed along the chip housing layer 47 of the stacked stack 36. The TAB film relays an electrical signal from the printed circuit board 21 to each of the print chips 27 supported by the laminated structure.

Dispensing moldings, stacked stacks 36, and related components are well illustrated in FIGS.

Fig. 10 shows a dispensing molding cover 39 formed of plastic molding and including a plurality of positioning protrusions 48 for positioning the upper printhead cover 49 thereon.

As shown in Fig. 7, the ink delivery port 50 includes one ink duct 39 (fourth from the left) and six lower ink ducts or a transitional duct 51 at the bottom of the dispensing molding. Connect to one of the bottoms. Every ink duct 40 has a corresponding delivery port 50 in communication with each intermediate duct 51. The intermediate ducts 51 are parallel to each other, but are inclined at an acute angle with respect to the ink ducts 40, so that the rows of ink holes in the first layer of the stacked stack 36 described later and Aligned.

The first layer 52 includes 24 individual ink holes 53 for each of the ten print chips 27. That is, when such ten print chips are provided, the first layer 52 includes 240 ink holes 53. The first layer 52 also includes one row of air holes 54 along its longitudinal edge.

Individual groups of the twenty four ink holes 53 are generally formed in a rectangular arrangement in which rows of ink holes are aligned. Each row of four ink holes is aligned along the intermediate duct 51 and parallel to each print chip.

The lower surface of the first layer 52 includes a lower groove 55. Each groove 55 communicates with one of the ink holes of the two rows at the center of the four holes 53 (thought in the direction transverse to the layer 52). That is, the hole 53a (see FIG. 13) delivers ink to the right groove 55a shown in FIG. 14, while the hole 53b delivers ink to the leftmost lower groove 55b shown in FIG. 14.

The second layer 56 includes a pair of slots 57, each of which receives ink from one of the lower grooves 55 of the first layer.

The second layer 56 also includes ink holes 53 aligned along two sets of ink holes 53 outside of the first layer 52. That is, for each of the print chips, ink passing through the sixteen ink holes 53 outside the first layer 52 passes directly through the corresponding holes 53 penetrated through the second layer 56. .

In the lower part of the second layer 56, a large number of channels 58 extending in the transverse direction are formed therein, and the ink passing through the ink holes 53c and 53d to the center is relayed. These channels extend to align along a pair of slots 59 formed through the third layer 60 of the stack. In this regard, the third layer 60 of the stack includes four slots 59 corresponding to each print chip, which are two aligned along a pair of slots formed in the second layer 56. It should be noted that the inner slots are composed of outer slots sandwiching the inner slots.

The third layer 60 also includes one arrangement of air holes 54 aligned along the corresponding air hole arrangement 54 provided in the first layer 52 and the second layer 56.

The third layer 60 has only eight remaining ink holes 53 corresponding to each print chip. These outermost holes 53 are aligned along the outermost holes 53 provided in the first and second layers. As shown in Figs. 9A and 9B, the third layer 60 includes a transversely extending channel 61, through each hole 53 at its bottom surface. These channels 61 deliver ink from the corresponding holes 53 to the positions just outside of the slots 59 aligned along the holes.

As best shown in FIGS. 9A and 9B, the top three layers of the stacked stack 36 contain ink (indicated by broken hatched lines in FIG. 9B), with a wider spaced ink duct 40 of the dispensing molding. ), Through the top surface of each print chip 27, to the slots aligned along the ink passage 31.

As shown in FIG. 13, which is a view of the stacked stack from above, the slots 57, 59 may in fact be composed of separate slot segments spaced on the same line.

The fourth layer of the stacked stack 36 comprises one arrangement of ten chip-slots 65 each holding the top of each printed chip 27.

The fifth and last layer 64 also includes an arrangement of chip-slots 65 containing an assembly 43 of chips and nozzle protectors.

The tab film 28 is sandwiched between the fourth layer 62 and the fifth layer 64, and one or both of the fourth layer 62 and the fifth layer 64 is formed of the tab film. Grooves may be provided to accommodate the thickness.

The stacked stack is formed by precision micro-molding, i.e., a molding method which is injected into acetal type material. It accommodates the arrangement of the print chip 27 to which the tab film has been previously attached and engages with the cover molding 39 described above.

Rib details at the bottom of the micro-molding, when glued together, serve as a support for the tab film. Since there is sufficient structural strength between the pitch of the ribs to support one flexible film, the tab film forms the bottom wall of the printhead module. The edges of the tab film seal the bottom wall of the cover molding 39. The chip is glued onto 100 micron wide ribs up to the length of the micro-molding, providing a final ink feed to the print nozzle.

Through the design of micro-molding, when the printed chips are bonded in one line, their physical overlap is possible. Because printhead chips now form continuous strips with sufficient tolerances, they can be numerically adjusted to produce near-perfect print patterns, rather than relying on very tight tolerance moldings and unfamiliar materials to perform the same function. have. The pitch of the modules is typically 20.33 mm.

The cover moldings 39 and the dispensing moldings as well as the individual layers of the stacked stack are stuck or otherwise glued together to provide a sealing unit. The ink passage can be sealed by an adhesive transparent plastic film which makes it visible when the ink is in the ink passage, so that the ink passage can be completely blocked when the top of the adhesive film is folded. Then ink filling is completed.

As shown in Figs. 9B and 13, the four upper layers 52, 56, 60, and 62 of the stacked stack 36 are formed with air passages 63 formed as channels in the bottom surface of the fourth layer 62; It has an aligned air hole 54 in communication. These passages provide compressed air to the space between the print chip surface and the nozzle protector 43 during printer operation. Air from this compressed zone passes through micro-apertures 44 in the nozzle guard, thereby preventing any dust or unwanted contaminants from accumulating in the holes. This supply of compressed air can be shut off to prevent the ink from drying out on the nozzle surface while the printer is not in use, the supply of air to the air valve assembly shown in FIGS. 6-8, 20 and 21. Is adjusted by

As shown in Figs. 6 to 8, in the air duct 41 of the printhead, an air valve molding 66 formed as a channel having a series of holes 67 at its base is located. The spacing of these holes corresponds to the air passage 68 formed at the base of the air duct 41 (see FIG. 6), and since the air valve molding is movable in the longitudinal direction in the air duct, the holes 67 ) Can be aligned along the passageway 68 to supply compressed air to the cavity between the print chip and the nozzle guard through the stacked stack, or to break out of the alignment to block the air supply. Makes it possible. The compression spring 69 seals the bottom of the air valve molding 66 and the base of the air duct 41 together to prevent leakage when the valve is closed.

The air valve molding 66 has one driven cam 70 extending from one end thereof, which couples the air valve cam surface 71 onto the end cap 74 of the platen 14 to provide a multifunctional By selectively moving the air valve molding in the longitudinal direction in the air duct 41 according to the rotational position of the platen 14, the multifunction platen 14 can be printed, capped and It can be rotated between blotting positions. This will be described in more detail below with reference to FIGS. 21 to 24. When the platen 14 is in the printing rotational position, the cam keeps the air valve in the open position to supply air to the print chip surface. On the other hand, when the platen rotates to a non-printing position that blocks the micropores of the nozzle guard, the cam moves the air valve molding to the valve closing position.

As shown in Figs. 21 to 24, the platen member 14 is supported by a rotation shaft 73 mounted to the bearing molding 18, and can be rotated by a gear 79 (see Fig. 3). Extends parallel to the printhead. The shaft is provided with a right end cap 74 and a left end cap 75 with cams 76 and 77 at each end.

The platen member 14 has a platen surface 78, a capping portion 80 and an exposed blotting portion 81, extending along its length and separated by 120 ° from each other. During printing, the platen member is rotated so that the platen surface 78 is positioned opposite the printhead, so that the platen surface acts as a support for that portion of the paper currently being printed. When the printer is not used, the platen member rotates to cause the capping portion 80 to contact the bottom surface of the printhead and to seal the place surrounding the fine hole 44. Thus, the air valve is closed by the air valve structure when the platen 14 is in the capping position, and an airtight atmosphere is maintained at the print nozzle surface. This prevents evaporation of the ink solvent (generally " water "), thereby preventing drying of the ink on the print nozzle while the print is not in use.

The third function of the rotating platen member is as an ink blotter which receives ink from the storage chamber of the print nozzle at the time of printer startup or maintenance operation. During the printer mode, the platen member 14 is rotated so that the exposed blasting portion 81 is located in the ink discharge passage opposite the nozzle protector 43. The exposed bloating portion 81 is an exposed portion of the body 83 of the blasting material in the platen member 14, and the ink received on the exposed portion 81 sucks into the body of the platen member. Is brought in.

More details of the platen member are shown in FIGS. 23 and 24. The platen member generally consists of a hollow platen body 83 extruded or molded, which forms a platen surface 78 and houses a forming body 82 of blasting material, Some of the shaping body 82 of the tinging material protrudes through the longitudinal slots in the platen body, forming an exposed bloating surface 81. The plat portion 84 of the platen body 83 serves as a base for the attachment of the capping member 80, which capping housing 80 has a capper housing 85, a capper. It consists of a foam member 87 for contact with the sealing member 86 and the nozzle protector 43.

As shown in FIG. 1, each bearing molding 18 is mounted on a pair of vertical rails 101. That is, the capping assembly is mounted on four vertical rails 101 so that the assembly can be moved vertically. At either end of the capping assembly, the lower spring 102 biases the assembly to the raised position, bringing the cams 76 and 77 into contact with the spacer protrusion 100.

The print head 11 is covered by a full width capping member 80 using an elastomer (or similar material) seal 86 when not in use. To rotate the platen assembly 14, the main roller drive motor is reversed. This causes the reversing gear to come into contact with the gear 79 on the end of the platen assembly, which is rotated to one of the three function positions separated by 120 °.

Cams 76, 77 on platen end caps 74, 75 cooperate with protrusions 100 on respective printhead spacers 20, between the platen member and the printhead, depending on the rotational position of the platen member. Adjust the interval between In this way, the platen moves away from the printhead during the transition between the platen positions to provide sufficient clearance from the printhead, and to return back the appropriate distance for its respective paper support, capping and blotting functions. Is moved.

Moreover, the cam structure for the rotating platen provides a mechanism for fine adjustment of the distance between the platen surface and the printer nozzle by slightly rotating the platen 14. This compensates for the nozzle-platen distance corresponding to the thickness of the paper or other material being printed, which is detected by the optical paper thickness sensor illustrated in FIG.

The optical paper sensor includes an optical sensor 88 mounted on the lower surface of the PCB 21 and a sensor flag structure mounted on an arm 89 protruding from the dispensing molding. The flag structure includes a sensor flag member 90 mounted on the shaft 91 biased by the torsion spring 92. When the sheet enters the feed roller, the bottommost portion of the flag member contacts the sheet and rotates against the bias of the spring 92 by an amount corresponding to the sheet thickness. The optical sensor senses this movement of the flag member, while the PCB responds to the sensed paper thickness by allowing the distance between the paper surface and the nozzle to be optimized by the compensating rotation of the platen 14.

26 and 27 show the attachment of the illustrated printhead assembly to a replaceable ink cassette 93. Six different inks are supplied to the printhead through a hose 94 leading from one arrangement of female ink valves 95 located inside the printer body. A replaceable cassette 93 comprising a six compartment ink bladder and a corresponding male valve arrangement is inserted into the printer and coupled to the valve 95. In addition, the cassette includes an air inlet 96 and an air filter (not shown), and is coupled to an air inlet connector 97 located next to the ink valve, and an air pump 98 for supplying filtered air to the printhead. To) QA chips are contained within the cassette. The QA chip engages a contact 99 located between the ink valve 95 and the air inlet connector 96 in the print when the cassette is inserted to connect to the QA chip connector 24 on the PCB.

Claims (15)

A plurality of print nozzles for selectively releasing ink droplets passing through the nozzle toward a print medium, and one located between the nozzle and the print medium through which ink droplets discharged from the nozzle pass in the direction of the print medium A printhead for an inkjet printer comprising a space, and additionally comprising air supply means for supplying air of positive pressure to the space, Air supply by the air supply means is cut off when the printer is in a non-printing mode of operation. The method of claim 1, And the space is formed between the nozzle and the nozzle protector. The method of claim 2, The nozzle protector has a plurality of holes aligned along the nozzles so that ink droplets discharged from the nozzles pass through the holes. delete The method of claim 3, And the plurality of nozzles are arranged in one array extending across one A4 paper width. The method of claim 5, And the nozzle comprises a micro-electromechanical device. The method of claim 6, And the nozzle is aligned in the plurality of print modules. The method of claim 7, wherein Each print module is associated with a respective nozzle protector to define a respective space. The method of claim 8, The air supply means is a printhead for an ink jet printer, characterized in that for supplying a constant pressure air to each of the spaces. The method of claim 5, And a plurality of spaces corresponding to respective portions of the nozzle arrangement, wherein the air supply means includes a general air inlet, an air filter, and means for distributing compressed air to the respective spaces. For printhead. The method of claim 10, And the air filter is provided in a replaceable ink cassette of the printer. The method of claim 10, And an air valve assembly to block supply of air to the space when the printer is in a non-printing mode of operation. The method of claim 12, The air valve assembly includes an air distribution duct having a plurality of air passages in communication with each of the spaces and an air valve assembly having a plurality of apertures corresponding to the air passages, And the valve member is movable between a valve opening position in which the air hole communicates with the air passage and a valve closing position in which the air hole does not communicate with the air passage. The method of claim 13, Air is distributed from the air passage to the space by a distribution structure laminated in multiple layers. The method of claim 14, The stacked distribution structure includes a plurality of air holes extending through at least some of the layers, and a transverse air passage formed between two neighboring layers of the layers and reaching the space. Printhead for the printer.

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