Print head maintenance unit movable on print medium support surface

Abstract

To provide a maintenance unit which is compact and inexpensive.SOLUTION: A print head array (5) for defining a print range on a print medium support surface includes a print head maintenance unit (20) for at least partially cleaning the print head array (5) on a drive assembly (30) for moving the print head maintenance unit (20) to the print head array (5), wherein in a first mode, the print head maintenance unit (20) is movable in a transverse direction (Y) on a print medium support surface so as to at least partially clean the print head array (5).SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a printer with a printhead array and to a method for performing maintenance on such a printhead array. [Background technology]

[0002] Printers, particularly sheet printers, may include printhead arrays, commonly referred to as pagewide arrays. Such arrays include multiple printheads extending over a print medium support surface. A transport mechanism is provided for moving the print medium along the printhead array during continuous operation as the printheads eject ink droplets onto the print medium to form an image. The printheads are stationary during ejection and define a print area spanning the width of the print medium. Droplets are ejected from nozzles located in one or more nozzle plates within the printhead array. During operation, ink or other contaminants may accumulate on the nozzle plate, potentially preventing reliable ejection from the nozzles. For example, nozzles may become (partially) blocked, or droplet size or trajectory may be affected by interaction with accumulated ink as droplets exit their respective nozzles. It is known to perform periodic or general maintenance of printhead arrays to at least partially clean one or more nozzle plates. Cleaning can be performed in a variety of ways, such as wiping, spraying, ultrasonic cleaning, suction, etc. It is also known to provide a maintenance unit or station adjacent to the print medium support surface for performing maintenance. When maintenance is required, the printhead array is moved to the location of a maintenance unit where one or more cleaning actions are performed.

[0003] In particular, the nozzle plate may be wiped clean by swiping a wiper medium across the printhead array. It is known to provide the wiper medium in a roll, which is unspooled to provide a constantly clean wiping surface for the nozzle plate. When the roll is depleted, replacement is required. Summary of the Invention

[0004] It is an object of the present invention to provide an improved maintenance unit for a printer, specifically a more compact, simpler and / or less expensive unit.

[0005] According to the present invention, a printer according to claim 1 and a method according to claim 14 are provided.

[0006] The printer is a printhead array defining a print area on a print medium support surface, the printhead array being configured to at least partially form an image on a print medium on the print medium support surface in the print area, the print medium support surface extending in a transport direction, the print medium being movable relative to the printhead array in a lateral direction perpendicular to the transport direction; a printhead maintenance unit mounted on a drive assembly for moving the printhead maintenance unit relative to the printhead array to at least partially clean the printhead array.

[0007] The printer is characterized in that in a first mode, the printhead maintenance unit is movable laterally over the print medium support surface to at least partially clean the printhead array.

[0008] The printhead array extends over the print medium support surface during printing. The print area overlaps the print medium support surface. The print area is preferably at least as wide as the width of the print medium on the print medium support surface. During printing, the maintenance unit is positioned so as not to interfere with the printhead array printing on the print medium moving along the printhead array through the print medium support surface. When maintenance is performed, the drive assembly operates to move the printhead maintenance unit laterally, thereby moving the printhead maintenance unit over the print medium support surface along the printhead array for cleaning. The printhead array remains above the print medium support surface, so cleaning is performed above the print medium support surface. This allows for a more compact configuration compared to performing cleaning completely off the print medium support surface. Lateral movement of the printhead array for maintenance is not required, allowing for a simpler and less costly system. This achieves the objectives of the present invention.

[0009] More specific optional features of the invention are set out in the dependent claims.

[0010] In an embodiment, the first mode is a maintenance mode, in which the printhead maintenance unit engages the printhead array to perform a cleaning operation. The cleaning operation may include any suitable action to remove residue or contaminants from the nozzle plate, such as wiping, purging, suction, spraying, wetting, ultrasonic irradiation / cleaning, etc. Preferably, the printhead maintenance unit can be switched to a second mode and prevented from performing a cleaning operation. It will be appreciated that in the first mode, the printhead maintenance unit is positioned sufficiently close to or in contact with the printhead array to enable cleaning, while in the second mode, the printhead maintenance unit may be relatively far from the printhead array, for example, to the side of the print media support surface.

[0011] In an embodiment, in the second mode, the printhead maintenance unit is positioned in a rest position adjacent to and to the side of the print area in the lateral direction. During printing, the printhead maintenance unit is positioned so as not to interfere with printing. In the rest position, the printhead maintenance unit is laterally positioned relative to the side of the printhead array, at least to a portion that defines the print area. The print area may be defined, for example, by the area covered by the nozzles or nozzle plate. Preferably, in the rest position, the printhead maintenance unit is also laterally positioned relative to the print medium support surface.

[0012] In an embodiment, the operating range through which the printhead maintenance unit moves in the first mode overlaps the print range, and the print range overlaps the print medium support surface when viewed in a height direction perpendicular to the transport direction and the lateral direction. The printhead maintenance unit defines an operating range within which it performs its cleaning action. It will be understood that the printhead maintenance unit may be movable outside of the operating range. The operating range is the area where the printhead maintenance unit actively engages the printhead array for cleaning. The operating range preferably corresponds to the maximum area that can be cleaned in a single lateral pass of the printhead maintenance unit. The operating range overlaps the print range and is preferably equal to or greater in area than the print area. Both the print range and the operating range overlap the print medium support surface. Preferably, both the print range and the operating range are laterally disposed within the width of the print medium support surface when viewed perpendicular to the print medium support surface.

[0013] In an embodiment, the drive assembly includes a support for movably supporting the print head maintenance unit as it moves in the first mode, the support extending laterally on the print head support surface, preferably across at least the width of the printing range in the lateral direction. The drive assembly supports the print head maintenance unit as it moves across the print medium support surface. The support preferably extends across the entire width of the print medium support surface. The support preferably forms a guide that defines the lateral movement of the print head maintenance unit. In a preferred embodiment, the support includes two support units, for example formed as beams, arranged on either side of the print head maintenance unit in the transport direction.

[0014] In an embodiment, the maintenance unit includes at least one wiper unit configured to hold a wiper medium such that the wiper medium moves across the surface of the printhead array when the maintenance unit moves in the first mode. Preferably, the first mode is a wiping mode, and the drive assembly moves the wiper unit along the printhead array such that one or more nozzle plates of the printhead assembly are wiped with the wiper medium. In a preferred embodiment, the wiper unit is configured to hold the wiper medium as a roll, which unspools as the wiper unit moves past the printhead array. During wiping, the roll unspools, preferably at a speed such that the wiper medium at the nozzle plate moves laterally faster than the printhead maintenance unit itself, thereby moving absorbed ink or contaminants away from the interface between the wiper unit and the nozzle plate.

[0015] In an embodiment, the printhead maintenance unit comprises a plurality of holding sites, each configured to releasably hold a wiper unit, the holding sites preferably being arranged in a row extending in the transport direction.

[0016] In an embodiment, the printhead maintenance unit further comprises a wetter configured to supply a wetting fluid to the wiping medium held by the at least one wiper unit. The wiping medium is preferably a so-called "wet" wiping medium, such as a wet tissue wiper. The wiping medium is wetted before contacting the nozzle plate. Preferably, for each wiper unit, the wetter is provided with a wetting device for transferring the wetting fluid from the wetter to the respective wiper medium. Such a wetting device may be a wetting roller, a sprayer, a humidifier, a bath, or the like.

[0017] In an embodiment, the wetter extends as a beam with wetting fluid channels in the transport direction, so that multiple wiping media for multiple wiper units can be supplied via the wetting fluid channels. Wetting fluid is preferably supplied to all available wiper units via a single wetting fluid channel extending in the transport direction. The wetting fluid channel supplies wetting fluid to each individual wetting device, so that it can transfer the wetting fluid onto an individual wiper medium.

[0018] In an embodiment, the support includes a gear rack, and the printhead maintenance unit is provided with a first drive wheel that engages with the gear rack, such that driving the first drive wheel moves the printhead maintenance unit in the lateral direction. The support of the drive assembly includes a gear rack. The gear rack defines an operating range of the printhead maintenance unit and extends above the print media support surface. By driving the drive wheel, the printhead maintenance unit can be moved back and forth along the printhead array.

[0019] In an embodiment, the gear rack comprises: a first gear rack segment disposed adjacent to and beside the print medium support surface when viewed in a height direction perpendicular to the transport direction and the lateral direction; a second gear rack segment extending above the print medium support surface when viewed in the elevation direction.

[0020] The first gear rack segment defines a rest position in the second mode, and the second gear rack segment defines an orbit of the print head maintenance unit in the first mode.

[0021] In an embodiment, the gear rack comprises a first gear segment comprising a raised rack section above a lower rack section in a height direction perpendicular to the conveying direction and the lateral direction, and the first drive wheel is connected to the wetter, such that: - when the first drive wheel is in the raised rack section, the wetter is at a raised level above the at least one wiper unit; When the first drive wheel is in the lower rack section, the wetter is at a lower level for supplying wetting fluid to the wetter medium of the at least one wiper unit.

[0022] The lower level corresponds to the level at which the printhead maintenance unit moves laterally linearly along the printhead array for cleaning. Preferably, the gear rack extends from the lower rack section parallel to the print medium support surface in the laterally direction so as to maintain a constant height relative to the printhead array. The wetter spends most of its movement in its wetting position, supplying wetting fluid to the wiper medium. Upstream of the lower rack section, a raised section defines a rest position, in which the wetter is positioned above and away from the wiper unit. When the first driven wheel moves over the raised rack section, this moves the wetter coupled to the first driven wheel upward. This moves the wetter out of the path of the wiper unit, allowing it to be easily unloaded from its holding position in the opposite lateral direction.

[0023] In an embodiment, the drive assembly further includes a cam mechanism connected to the first drive wheel and the wetter, such that as the first drive wheel travels parallel to the lateral direction, the cam mechanism moves the wetter in the lateral direction from a spaced apart position to engage the wetter medium of the at least one wiper unit. The cam mechanism is configured to move the wetter laterally into and out of contact with the wiper medium of the wiper unit. Initially, the first driven wheel is on a raised rack section so that a wiper unit with an unused roll of wiper medium can be inserted. The first driven wheel then moves downward to the lower rack section, thereby bringing the wetter down to the level of its wetting position but still clear of the wiper medium. As the first driven wheel moves further up the gear rack at a certain height, the driven wheel of the wheel begins to engage the inclined cam surface. As a result, the wetter connected to the cam mechanism is driven forward relative to the wiper unit, thereby bringing the wetter to its wetting position and allowing it to wet the wiper medium. It will be appreciated that movement from the raised rack section to the end of the operating range may be performed as a single movement and may be controlled entirely by driving the first driven wheel, which may be accomplished by a single motor. No additional motors are required to move the wetter or unload the wiper unit.

[0024] In an embodiment, the gear rack includes at least one upward movement limiter disposed along the gear rack to prevent the first drive wheel from disengaging from the gear rack. The first drive wheel is generally pressed toward the gear rack under the influence of gravity. During operation, an upward force may be applied to the first drive wheel to disengage it from the gear rack. One or more upward movement limiters are positioned to prevent such upward movement. Preferably, the first drive wheel is provided with guide rollers, each upward movement limiter extending a short distance above the guide roller to prevent the first drive wheel from lifting off the teeth of the gear rack.

[0025] In one embodiment, the gear rack includes a missing-tooth section disposed between the raised rack section and the lower rack section, where the inclined rack section is located. The inclined rack section has a missing-tooth section at its downstream end, which allows the first driving wheel to transition from the inclined rack section to the lower rack section in a relatively narrow area. In another embodiment, an upward movement limiter is provided facing the missing-tooth section to prevent the first gear from disengaging from the gear rack. The upward movement limiter is, for example, a stop or end face that limits the upward movement of the first driven wheel. The upward movement limiter may directly engage the first driven wheel or may engage a (smooth) guide roller coupled to the shaft of the first driven roller. Additional upward movement limiters may be provided along other sections of the gear rack.

[0026] In one embodiment, the cam mechanism is provided with a curved cam surface segment, preferably in the form of a protrusion, shaped and positioned to exert a reaction force on the first drive wheel when the cam mechanism is at or near the missing tooth section, thereby preventing the first drive wheel from disengaging from the gear rack. At certain locations, particularly at missing tooth sections, the upward travel limiter may include a gap that allows the first drive wheel to pass through the individual sections without jamming. When the first drive wheel is driven laterally opposite the inclined rack section, the first drive wheel experiences a reaction force laterally. This reaction force urges the first drive wheel to disengage from the gear rack. At the location of the gap, the first drive wheel is not restricted from moving away from the gear rack. Instead, the cam mechanism is designed to locally provide a reaction force that is opposite to and greater than the reaction force. This ensures that the first drive wheel in the gap remains engaged with the gear rack. The location of the protrusion corresponds to the location of the gap. When the first drive wheel is in the gap, the driven wheel is in the protrusion. The protrusion is large enough so that the driven wheel can only move laterally past the protrusion when the first drive wheel is actively driven by the motor. The protrusion is large enough so that its own reaction force cannot drive the driven wheel past the protrusion. As a result, the first drive wheel connected to the driven wheel cannot be moved away from the gear rack by the reaction force. This ensures that the first drive wheel and the gear rack remain securely engaged, even in the gap. While protrusions or ridges are used above as examples, it will be understood that a similar effect can be achieved by a suitably formed recess in the cam surface.

[0027] In another aspect, the invention provides a method for performing maintenance on a printhead array disposed on a print media support surface, the method comprising: - moving the print medium in a transport direction along the printhead array; - in a non-cleaning mode, disposing a print head maintenance unit laterally of the print medium support surface in a lateral direction perpendicular to the transport direction, - in a cleaning mode, moving the printhead maintenance unit laterally across the print medium support surface along the printhead array, preferably at least through an entire print range defined by the printhead array. [Brief explanation of the drawings]

[0028] The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings, which are given by way of example only and are therefore not limiting of the invention. [Figure 1] 1 is a schematic cross-sectional view of a printer having a printhead maintenance unit. [Figure 2] FIG. 2 is a top view of the printer of FIG. 1 with the printhead maintenance unit in its rest position. [Figure 3] FIG. 2 is a top view of the printer of FIG. 1 with the printhead maintenance unit moving laterally through its operating range. [Figure 4] FIG. 4 is a detailed perspective view of the print head maintenance unit of FIGS. 1 to 3. [Figure 5] FIG. 5 is a detailed perspective view of a drive assembly for moving the printhead maintenance unit of FIG. 4. [Figure 6] FIG. 10 is a detailed side view of the drive assembly with the printhead maintenance unit in the wiper unit loading position defined by a raised rack section. [Figure 7] FIG. 10 is a detailed side view of the drive assembly with the printhead maintenance unit's wetter in a lowered, spaced apart wetter position defined by the lower rack section. [Figure 8]FIG. 8 is an enlarged side view of the first rack segment of the drive assembly in the situation of FIG. 7. [Figure 9] FIG. 8 is an enlarged side view of the cam mechanism of the drive assembly in the situation of FIG. 7. [Figure 10] FIG. 10 is a detailed side view of the drive assembly with the wetter in a further lowered and spaced apart wetter position defined by the lower rack section. [Figure 11] FIG. 10 is a detailed side view of the drive assembly with the wetter in a wetting position defined by a run-out rack section. [Figure 12] FIG. 10 is a further detailed perspective view of a drive assembly for moving the printhead maintenance. [Figure 13] FIG. [Figure 14] FIG. 2 is a side view of the wiper unit with a portion of the housing removed. [Figure 15] FIG. [Figure 16] FIG. 4 is a perspective view of a forced pinch mechanism of the wiper unit. [Figure 17] FIG. 2 is an exploded perspective side view of the wiper unit. [Figure 18] FIG. 2 is a perspective view of a lamella roller of the wiper unit. [Figure 19] FIG. 4 is a perspective view of a locking mechanism of the wiper unit. [Figure 20] FIG. 4 is a side view of the locking mechanism of the wiper unit. [Figure 21] FIG. 2 is a perspective view of a flange of the wiper unit. [Figure 22] FIG. 10 is a side view of the locking mechanism engaged with the take-up roller of the wiper unit. [Figure 23] FIG. 2 is a perspective view of a release mechanism of the wiper unit. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals are used throughout the several views to identify the same or similar elements.

[0030] Printhead maintenance on the print media support surface FIG. 1 shows a sheet printer 1. A sheet is fed from an input module 2 into a transport path 3. The transport path 3 transports the sheet past a printhead array 5, which includes multiple printhead units arranged next to each other in a transport direction X. The transport path 3 below the printhead assembly 5 is formed by an endless belt 6. The belt 6 is provided with openings so that negative pressure can be applied to the sheet via suction chambers 7. Downstream of the printhead assembly 5, the transport path 3 passes through a fuser unit 8. The fuser unit 8 is configured to strengthen the liquid ink that solidifies on the sheet. The fuser unit 8 includes one or more emitters therein for emitting heat or energy, such as heat, heated air, or radiation, toward the sheet. The fuser unit 8 faces a transport belt 10 with corresponding suction boxes 9. Downstream of the fuser unit 8, an output switch 13 is provided for selectively directing the sheet toward an output module 14 or to a duplex path 11. The fully printed sheet is passed to the output module 14. Sheets requiring duplex printing are passed to a duplex path 11 where they are inverted by an inverter device 12. The inverted sheets are then inserted at an input switch 4 so that they can return to the printhead assembly 5.

[0031] A printhead maintenance unit 20 is provided adjacent to the printhead array 5. The printhead maintenance unit 20 is configured to clean the printheads in the printhead array 5. Each printhead includes a nozzle plate with nozzles formed therein, through which marking fluid or ink is ejected. Marking fluid may accumulate and remain on the nozzle plate, which can affect reliable droplet ejection, particularly if the marking fluid accumulates around or at the nozzle. The maintenance unit 20 is configured to at least partially remove the accumulated marking fluid from the nozzle plate. Additionally, the maintenance unit 20 may include a wiper assembly that can be moved along the printhead array to wipe the nozzle plate. However, it will be understood that other maintenance devices, such as a sprayer, brush, ultrasonic cleaner, etc., may be applied instead of wiping.

[0032] FIG. 2 shows the maintenance unit 20 in its rest position R. The rest position is beside the printhead assembly 5 in the lateral direction Y, which is perpendicular to the transport direction X and lies in the plane of the transport path 3. The transport path 3 is defined by the belt 6, which also forms the print medium support surface. The printhead array 5 is a so-called page-wide printhead array, which defines an operating range W. The operating range W preferably covers most of the width of the belt 5 in the lateral direction Y. In its rest position R, the maintenance unit 20 is adjacent to the printhead assembly 5, preferably within 10 to 20 centimeters, but does not interfere with the jetting operation of the printhead array 5.

[0033] FIG. 3 shows the maintenance unit 20 moving in the lateral direction Y along the printhead assembly 5. The maintenance unit 20 moves out of a rest position R and into an operating range W. The maintenance unit 20 is configured to move along the entire operating range W to wipe all of the nozzles in the printhead array 5. This results in a compact structure because the dimensions of the maintenance unit 20 in the lateral direction Y are generally smaller than the dimensions of the printhead array 5. During wiping, the printhead array 5 is stationary and has the same lateral position as during printing. The range of movement of the maintenance unit 20 overlaps and / or is similar to the print range in which the printhead assembly 5 is arranged to print.

[0034] FIG. 4 is a more detailed view of the maintenance unit 20. The maintenance unit 20 comprises a wetter 22 configured to hold a plurality of wiper units 70. Although only a single wiper unit 70 is shown in FIG. 4, it will be understood that a similar wiper unit 70 may be provided at each of the wiper unit holding locations. Each wiper unit location is provided with an individual wetting device in the form of a wetting roller 24. The wetter 22 is provided with a wetting fluid channel extending in the conveying direction X. Wetting fluid flows through the wetting fluid channel so that it is provided to each individual wetting roller 24. A wetting fluid source (not shown), for example a fluid reservoir with a pump, is connected to the wetting fluid channel.

[0035] A separate wiper unit 70 is provided at the leftmost wiper unit location. The wiper unit 70 includes a wiper medium 72, such as tissue, sheet, or paper, for cleaning the nozzle plate. In FIG. 4 , the wiper medium 72 is provided in roll form inside the wiper unit 70 so that it can be unspooled during wiping to prevent smearing of marking fluid on the nozzle plate. The wiper unit 70 can be fixed to the wetter 22 so that it moves together with the wetter 22. A drive assembly 30 is provided for moving the wetter 22 and the wiper unit 70 in the lateral direction Y.

[0036] Drive Assembly The drive assembly 30 is shown in detail in Figure 5. The drive assembly 30 comprises a first drive wheel 26 in the form of a gear coupled to a guide roller 28. The guide roller 28 has a smooth outer surface, and the first drive wheel 26 is a gear or cog with teeth. The first drive wheel 26 and the guide roller 28 are mounted on a support shaft 27. The support shaft 27 is rotatably mounted on a support structure 25. The support structure 25 in Figure 5 is formed as a plate. The wetter 22 is mounted on the support structure 25. The wetter 22 is rigidly connected to the support structure 25 by screws.

[0037] The first drive wheel 26 engages with a gear rack 31. The gear rack 31 is rigidly connected to a printer frame 39. The printer frame 31 is stationary during operation. By rotating the first drive wheel 26, the wetter 22 and wiper unit 70 can be moved in the lateral direction Y. The gear rack 31 has multiple sections, and a raised rack section 32 is provided at the end closest to the rest position P. The raised rack section 32 is located above a run-out rack section 36. The run-out rack section 36 is parallel to the lateral direction Y and extends above the print medium support surface of the belt 6. The raised rack section 32 is formed by a first gear rack section separate from the second gear rack section, which includes the run-out rack section 36. The second gear rack segment is preferably a linear or straight gear rack. The first gear rack segment further comprises a lower rack section 35, which is parallel to and at the level of the run-out rack section 36. Between the raised rack section 32 and the lower rack section 35, there is an inclined rack section 33 to partially overcome the height difference between these two sections 32, 35. Between the inclined rack section 33 and the lower rack section 35, there is an inclined missing-tooth section 34. The missing-tooth section 35 extends downward in the lateral direction Y to the level of the lower rack section 35. The missing-tooth section 35 is substantially free of teeth that can engage with the teeth of the first drive wheel 26. The missing-tooth section 35 allows the first drive wheel 26 to transition smoothly from the raised rack section 32 to the lower rack section 35, while enabling a space-efficient construction. When the first drive wheel 26 moves in the lateral direction Y, it descends the inclined rack section 33, passes through the missing tooth section 35, and engages with the lower rack section 35.

[0038] The movement of the first drive wheel 26 is defined by a gear rack 31. This movement is guided by a guide roller 28. The guide roller 26 is mounted adjacent to the first drive wheel 26 on the same support shaft 26 as the first drive wheel 26 in the conveying direction X. The path of the guide roller 26 is limited by guides formed by limiters 38, 40-42 mounted on or within a printer frame 39. The printer frame 39 surrounds the guide roller 28 in the conveying direction X. This prevents the first drive wheel 26 from moving out of the gear rack 31 in the conveying direction X. Furthermore, the upward movement of the guide roller 28 is limited by upward movement limiters 40-42. The upward movement limiters 40-42 extend above the path of the guide roller 28 and ensure that the first drive wheel 26 cannot move upward out of engagement with the gear rack 31. With respect to the horizontal rack sections 32, 36, the upward movement limiters 40, 42 extend parallel to the lateral direction Y. Above the tilted rack section 33, a separate upward movement limiter 41 is also tilted. The tilted upward movement limiter 41 is positioned so that the first drive wheel 26 remains engaged with the gear rack 31 when the tilted rack section 33 is lowered or raised. In Figure 5, the upward movement limiters 40-42 are formed as bent portions of a plate that forms the printer frame 39.

[0039] FIG. 6 shows the maintenance unit 20 in a loading position in which the wiper unit 70 can be removed and / or inserted into the maintenance unit 20. In the loading position, the first drive wheel 26 is positioned on the raised rack section 32. As a result of this raised position, the support structure 25 is also pivoted to the raised position. Furthermore, the wetter 22 connected to the support structure 25 is also moved to the raised position. This positions the wetter 22 and its wetting device 24 away from the wiper unit 70. This allows the wiper unit 70 to slide out of the maintenance unit 70 by moving it in the opposite direction to the lateral direction Y. A rod mechanism 55 is provided to support the wetter 22. The rod mechanism 55 is configured to maintain the wetter 22 substantially horizontal to prevent leakage of the wetting fluid from the wetting fluid channel. The rod mechanism 55 moves downward together with the wetter 22 between FIGS. 6 and 7.

[0040] The wiper unit 70 is loaded by inserting it into the wiper unit holder 60. A wiper unit holder 60 is provided for each individual printhead unit. The wiper unit holder 60 includes a wiper unit support 29, and the wiper unit 70 is supported by the maintenance unit 20. The wiper unit holder 60 includes a wiper unit support frame that moves with the wetter 22. As shown in FIG. 12 , the wiper unit support frame may include rollers that allow the wiper unit 70 to be quickly and easily inserted into and retracted from the wiper holder 60.

[0041] A cam mechanism 51 is provided for moving the wetting device 24 into contact with the wetting medium 72 as it moves in the lateral direction Y. A driven wheel 52 is mounted on a cam arm, which is pivotable about a cam shaft 53. The driven wheel 52, cam arm, and cam shaft 53 move with the first drive roller 26 as it moves in the lateral direction Y. A cam surface 50 is provided stationary relative to the gear rack 31. The cam surface 50 has a first surface section with a protrusion 52 and a second surface section 46 that is inclined relative to the vertical direction Z. The cam mechanism 51 is described in detail below with reference to Figures 7 to 10.

[0042] FIG. 7 shows the maintenance unit 20 with the first drive wheel 26 in its first lower position. Compared to FIG. 6, the first drive wheel 26 is driven to move in the lateral direction Y, thereby descending the inclined rack section 33. Initially, the first drive wheel 26 moves over the raised rack section 32, where it is limited by the upward movement limiter 40. The upward movement limiter 40 prevents the guide roller 28 from moving upward, preventing the first drive wheel 26 from losing contact with the gear rack 31. The first drive wheel 26 then reaches the inclined rack section 33, where it begins to descend the gear rack 31. To allow the first drive wheel 26 to pass through the lower transition section, a missing tooth section 34 is provided at the transition section, as shown in FIG. 8. The missing tooth section 34 is sufficiently small so that the first drive wheel 26 can simultaneously maintain contact with the teeth of the inclined rack section 33 and the lower rack section 35. During this downward movement, the tilt limiter 41 prevents the first drive wheel 26 from disengaging from the gear rack 31. FIG. 7 shows a gap G in the upward movement limiter 40 facing the missing tooth section 34. The gap G is between the tilt limiter 41 and the run-out limiter 42, which extends above the missing tooth section 36. The gap G provides sufficient freedom so that the first drive wheel 26 can pass through the missing tooth section 34. If a limiter were provided at the position of the gap G, the first drive wheel 26 would get caught between the teeth of the gear rack 31 and the upward movement limiter 40 and become stuck there.

[0043] As the first drive wheel 26 descends, the support shaft 27 moves downward, pivoting the support structure 25 downward. This forces the wetter 22 downward so that the wetter 22 is at its operating level and remains there during the wiping operation. In response, the rod mechanism 55 moves to carry the wetter 22 downward while maintaining it substantially horizontal to prevent spillage of wetting fluid.

[0044] During this movement, the driven wheel 52 of the cam mechanism 51 follows the substantially horizontal surface section 45 of the cam surface 50, thereby preventing the cam mechanism 51 from operating, as shown in FIG. 9 . The substantially horizontal surface section 45 is flat or level except for a single protrusion 44. The driven wheel 52 runs up to the protrusion 44 included in this section 45, which prevents the first drive wheel 26 from disengaging from the gear rack 31 when the first drive wheel 26 is in gap G in the upward travel limiter 40. At gap G, the first drive wheel 26 is not prevented by the upward travel limiter 40 from disengaging from the gear rack 31. Instead, the cam mechanism 51 prevents the first drive wheel 26 from disengaging from the gear rack 31. When in the protrusion 44, the cam mechanism 51 applies a reaction force F to the first drive wheel 26. w , which urges the first drive wheel 26 towards the missing tooth section 34. The protrusion 44 is in the form of a slight bump. The bump is large enough to allow the cam mechanism 51 to act as a brake to prevent uncontrolled rotation of the first drive wheel 26. When the first drive wheel 26 rotates upward relative to the lateral direction Y in the inclined gear section 33, it exerts an upward force F up Through interaction with the gear rack 31, the first drive wheel 26 is further driven by a reactive outward force F out , which may drive the first drive wheel 26 out of contact with the teeth of the gear rack 31 when in gap G. The protrusion 44 is subjected to a normal force F n F n is the normal force required to overcome the protrusion 44. The shape of the protrusion 44 creates an accompanying reaction force Fw It also provides the reaction force F w is the outward force F out Conversely, the protrusion 44 generates a reaction force F w is the outward force F out The driven wheel 52 cannot pass the projection 44 without additional driving force from the motor. out is the reaction force F w , the first drive wheel 26 is thereby prevented from losing contact with the gear rack 31 at gap G because the first drive wheel 26 is connected to driven wheel 52. It will be appreciated that the above mechanism also prevents the first drive wheel 26 from losing contact with the gear rack 31 when the first drive wheel 26 is driven to descend on an individual section. When descending, the weight of the structure provides an additional force that urges the first drive wheel 26 against the gear rack 26.

[0045] FIG. 10 shows the first drive wheel 26 transitioning from the first gear rack segment to the horizontal second gear rack segment formed by the run-out rack section 36. The first drive wheel 26 is at the level shown in FIG. 7, and therefore the wetter 22 is at the same level as in FIG. 7. The driven wheel 52 of the cam mechanism 51 has passed the protrusion 44 but still remains on the horizontal surface section 45. Movement is controlled by driving the first drive wheel 26. It will be understood that in all of FIGS. 4-10, the maintenance unit 20 may still be considered to be in its rest position. The maintenance unit 20 in these figures is still in a non-wiping mode.

[0046] FIG. 11 shows the first drive wheel 26 advancing further into the run-out rack section 36. In FIG. 11, the maintenance unit 20 enters its wiping mode. The wetter 22 is then moved relative to the wiper unit 70 so that the wetting device 24 contacts the wetting medium 72. The wetting medium 72 is thereby actively wetted by wetting fluid supplied through the wetting fluid channel within the wetter 22. The relative movement between the wetter 22 and the wiper unit 70 is controlled by a cam mechanism 51. In FIG. 11, the driven wheel 52 engages the inclined cam surface 46, thereby actuating the cam arm. The movement of the cam arm urges the wetter 22 and the corresponding wetting section (WE in FIG. 14) of the wiping medium 72 together. The movement is defined by a rod mechanism 55 configured to maintain the wetter 22 substantially horizontal during movement. As shown in FIG. 10, the wiper unit 70 defines a wetting portion 73 to which the wetting medium 72 is exposed. In the wetting section 73 , the wetter 22 engages the wetting medium 72 and transfers wetting fluid to the wetting medium 72 .

[0047] In FIG. 11 , the maintenance unit 20 is in its wiping mode and moves through its operating range W. The wetter 22 actively wets the wiper medium 72, which is wiped along the nozzle plate of the printhead assembly 5 with its wiping section (WI in FIG. 14 ). The wiper medium 72 unspools during lateral movement, so that each section of the nozzle plate is wiped with a clean portion of the wiper medium 72. The ink-laden wiper medium 72 spools away from the printhead. It will be appreciated that, in the contact area, the speed of the wiper medium 22 relative to the printer frame 39 is preferably equal to or (slightly) greater than the speed of the first drive wheel, wiper unit 70, and / or wetter 22.

[0048] FIG. 12 shows the drive wheels of the drive assembly 30. Note that all of the movements in FIGS. 4-11 are controlled in this example by a single motor driving a motor wheel 60. The motor wheel 60 drives a first drive wheel through multiple transmission wheels 58, 59. In FIG. 12, all of the wheels 26, 58-60 are interconnected gears, specifically double gears, where the number of teeth on the receiving wheel is different from the number of teeth on the connected wheel. This allows for the appropriate speeds to be achieved.

[0049] wiper unit A single wiper unit 70 is shown in FIG. 13. The wiper unit 70 is formed as a removable cassette capable of holding a roll of wiping medium 72. The wiper unit 70 allows the wiper medium 72 to be spooled so that it wipes across the nozzle plate. The wiper medium 72 is rewound onto a second roll 82. The roll 82 is disposed inside a housing 90 that forms the outer body of the wiper unit 70. The housing 90 is provided with a grip 92 that allows the wiper unit 70 to be easily manually removed from its individual holding location by pulling the grip 92 in the direction opposite to the lateral direction Y when the maintenance unit 20 is in the (un)loaded position of FIG. 6.

[0050] The path of the wiping medium 72 through the wiper unit 70 is shown in Figures 14 and 15. Figure 14 shows the wiper unit 70 without one of the side panels forming the housing 90. The wiping medium 72 is provided as a first roll 73 on a first roller 74. A limiter 83 may be provided to maintain the shape and position of the first roll 73. From the first roll 73, the wiping medium 72 extends over multiple convex rollers 75-78, resulting in a portion of the wiping medium 72 extending outside the housing 92. The diameter of the convex rollers 75-78 is larger in the middle of each roller 75-78 in the conveying direction than at its ends. The diameter gradually decreases toward each end. This convex shape, combined with the bend in the path of the wiping medium 72 provided by the convex rollers 75-78, continuously guides the wiping medium 72 between these rollers 75-78. Thus, the position of the wiper medium 72 is limited without the need for an active or automated control mechanism.

[0051] The convex rollers 75-78 further define a wetting section WE, where the wetter 22 can apply wetting fluid to the wiper medium 72. In the wetting section WE, the wiper medium 72 extends outside the housing 90. A curved recess 95 is provided in the side plate of the housing 90 to allow the wetter 22 to engage with the wiper medium 72 in the wetting section WE. The convex rollers 75-78 define a negative turn section in the path of the wiper medium 72. Inside this negative turn section, a portion of the wiper medium 72 is exposed and therefore accessible to the wetter 22. Thus, when the printhead maintenance unit 20 is in its wetting position of FIG. 11 , the wiper medium 72 is wetted in the negative turn section. The wiper medium 72 is wetted between the central convex rollers 76 and 77. Downstream of the first central convex roller 76, the wiper medium 72 is provided with wetting fluid during the wetting operation.

[0052] The downstream convex rollers 77-78 interact with a forcing pinch mechanism 100 via the wiper medium 72. The forcing pinch mechanism 100 provides a substantially constant tension to the wiper medium 72 during operation. The forcing pinch mechanism 100 is shown in detail in FIG. 16. The forcing pinch mechanism 100 comprises a frame 102 pivotally or rotatably mounted to the housing 90. The frame 102 is pivotable about an axis extending in the conveying direction X and passing through an axis opening 106. The axis opening 106 defines a pivot arm 105 that defines the movement of the frame 102. The pivot arm 105 is rigidly fixed to the frame 102 by a fixing means 111. The frame 102 is further connected to the housing 90 by spring elements 108, 109. The spring elements 108, 109 are pretensioned in both directions of movement of the frame 102 about the axis within the axis opening 106. In FIG. 16 , more spring elements 108 are provided on one side compared to a single spring element 109 on the opposite side. During operation, the wiper medium 72 is generally under tension, which acts against the spring elements 108. An opposing spring element 109 is provided when the tension is temporarily reduced. Effectively, the combined spring elements bias the force pinch mechanism 100 toward the printhead array 5. Furthermore, the movement of the frame 102 may be limited to a predetermined range by, for example, a limiting opening 104 that engages a stop rigidly attached to the housing 90 to define an end position for the movement of the frame 102. Such a stop may be formed, for example, by a particular convex roller 77.

[0053] In FIG. 16 , the forcing pinch mechanism 100 further includes a toothed roller 79 that defines a wiping section WI. In the wiping section WI, the wiper medium 72 wipes across the printhead array during a cleaning operation. The toothed roller 79 includes teeth that extend in the transport direction X during use, resembling tiny toothed gears. The toothed roller 79 is the first roller to contact the wiper medium 72 that has wiped ink or contaminants from the nozzle plate. By only locally pressing on the wiper medium 72, the toothed roller 79 prevents or reduces the likelihood of fluid being squeezed out of the wiper medium 72. The toothed roller 79 is rigidly connected to the frame 102 by a panel 110.

[0054] As shown in FIG. 17, the wiper medium 72 extends from a toothed roller 79 onto a lamella roller 80. The lamella roller 80 is shown in FIG. 18. The lamella roller 80 has a shaft 85 that extends in the conveying direction X during use. The shaft 85 is provided with a number of lamellas 86. Each of the lamellas is shaped as a circular disk. The disks are spaced apart along the conveying direction X. The (outer) lamellas may have a reduced diameter towards the ends. The lamellas 86 prevent fluid from being forced out of the wiper medium 72. Pressure on the wiper medium 72 is applied only locally at the lamellas 86, not in the areas between them. This prevents contaminated wiper fluid from being forced out of the wiper medium 72.

[0055] FIG. 17 shows the mounting of the take-up roller 81 for the second roll 82. The take-up roller 81 extends through the second roll 82. On the right side, the take-up roller 81 is provided with a gear 109 for rotating the roll 82. The gear 109 is driven by a motor wheel 108. On the left side in the conveying direction X, the second roll 82 is confined by a flange 107. It will be understood that a similar flange may be provided between the second roll 82 and the gear 109. The flange 107 is fixed to the take-up roller 81 by a locking mechanism 110. The locking mechanism 110 is arranged to interact with a release mechanism 120 provided on the housing part 93. The housing parts 92, 93 form a housing 90 that encloses the rolls 73, 82.

[0056] The locking mechanism 110 is shown in FIGS. 19-21. The locking mechanism 110 includes a cylindrical body 111. The body 111 is provided with a flange member 114 near one of its ends. The flange member 114 extends perpendicular to the main axis of the body 111. The locking mechanism 110 includes a click mechanism formed by a locking protrusion 118 attached to a hinge plate 113. The hinge plate 113 allows the locking protrusion 118 to move toward and away from the main axis of the body 111. The hinge plate 113 is formed in the wall of the body 111 by an internal recess. In the neutral position of the hinge plate 113, the locking protrusion 118 extends radially beyond the body 111. A similar locking protrusion 118 with the hinge plate 113 is provided on the opposite side of the body 111. Between the flange members 114, recesses 117 are provided, through which the free ends of the hinge plates 113 extend beyond the flange members 114 opposite the conveying direction X. A ring-shaped opening 115 is provided between these free ends to receive the end of the take-up roller 81. A rotation handle 116 is provided on the flange members 114 at the level of this ring. The rotation handle 116 is shaped so that it can be easily engaged to rotate the locking mechanism 110. As shown in FIG. 21 , the flange 107 has a central opening into which the cylindrical body 111 fits. The flange members 114 are wider and cannot pass through the central opening. On the opposite side of the flange 107, a fixing protrusion 119 extends beyond the radius of the body 111, so that the flange 107 is fixed between the fixing protrusion 119 and the flange members 114. The fixing protrusion 119 is provided on each of these hinge plates 112, which is configured to pivot inward when the cylindrical body 111 moves through the central opening of the flange 107. The fixing projections 119 and the locking projections 118 are provided with angled portions to help press the hinge plates 112, 113 inward. On the side facing the flange member 114, the fixing projections 119 and the locking projections 118 are provided with flat abutment surfaces that act as stops.

[0057] 22 shows the locking mechanism 110 engaged with the take-up roller 81. The take-up roller 81 has a hollow cylindrical roller body 98, with an opening 99 formed in a position corresponding to the locking projection 118 of the locking mechanism 110. The cylindrical body 111 of the locking mechanism 110 is inserted into the roller body 98 through the flange 107. The cylindrical body 111 rotates so that the locking projection 118 is positioned in the opening 99. The hinge plate 113 then resumes its rest position, driving the locking projection 119 through the opening 99, thereby securing the locking mechanism to the take-up roller 81.

[0058] The locking mechanism 110 can be released from the take-up roller 81 by a release mechanism 120. The release mechanism 120 is secured to the housing part 93 by a clamp 112. The release mechanism 120 includes an elastically deformable ring 121 having opposing pressure members 123. Each pressure member 123 is provided with a finger grip 124 for easy engagement by an operator. In their rest positions, the pressure members 123, as well as the free ends of the hinge plates 113, face each other. A rotation handle 116 can be used to rotate the locking mechanism 110 in the correct orientation relative to the release mechanism 120. When the pressure members are moved toward each other, the hinge plates 113 are forced inward, which moves the locking projections 118 out of the openings 99 in the take-up roller 81, allowing the locking mechanism 110 to slide off the take-up roller 81. This allows the second roll 82 on the take-up roller 81 to be removed and an unused roll to be loaded.

[0059] While specific embodiments of the present invention have been illustrated and described herein, those skilled in the art will recognize that various alternative and / or equivalent implementations exist. It should be understood that the exemplary embodiment or exemplary embodiments are examples only and are not intended to be limiting in any way in scope, applicability, or configuration. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, and it should be understood that various changes can be made in the function and arrangement of elements described in the exemplary embodiments without departing from the scope as set forth in the appended claims and their legal equivalents. In general, this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

[0060] In this document, the terms "comprises," "comprising," "includes," "including," "including," "containing," "having," and any variations thereof are intended to be understood in an inclusive (i.e., non-exclusive) sense, and it is understood that the processes, methods, devices, apparatuses, or systems described herein are not limited to those features or portions or elements or steps that are enumerated, but may include other elements, features, portions, or steps that are not expressly enumerated or that are inherent to such processes, methods, articles, or apparatuses. Furthermore, as used herein, the terms "a" and "an" are understood to mean one or more, unless expressly stated otherwise. Furthermore, the terms "first," "second," "third," etc. are used merely as labels, and are not intended to impose or establish numerical requirements on a particular ranking of the importance of those objects.

[0061] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications which would be obvious to those skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A printer (1), a printhead array (5) defining a printing area on a print medium support surface, the printhead array (5) being configured to at least partially form an image on the print medium on the print medium support surface in the printing area, the print medium support surface extending in a transport direction (X), the print medium being movable relative to the printhead array (5) in a lateral direction (Y) perpendicular to the transport direction (X); a printhead maintenance unit (20) mounted on a drive assembly (30) for moving the printhead maintenance unit (20) relative to the printhead array (5) to at least partially clean the printhead array (5); In a first mode, the printhead maintenance unit is movable in the lateral direction over the print medium support surface to at least partially clean the printhead array.

2. 2. The printer (1) of claim 1, wherein in the second mode, the print head maintenance unit (20) is positioned in a rest position adjacent to and to the side of the print area in the lateral direction (Y).

3. 3. The printer (1) according to claim 1 or 2, wherein an operating range (W) in which the print head maintenance unit (20) moves in the first mode overlaps with the printing range, and the printing range overlaps with the print medium support surface when viewed from a height direction (Z) perpendicular to the transport direction (X) and the lateral direction (Y).

4. 4. The printer (1) according to claim 1, wherein the drive assembly (30) comprises a support for movably supporting the print head maintenance unit (20) as it moves in the first mode, the support extending in the lateral direction (Y) on the print head support surface, preferably across at least the width of the printing range in the lateral direction (Y).

5. 5. A printer (1) according to claim 1, wherein the maintenance unit (20) comprises at least one wiper unit (70), the wiper unit (70) holding a wiper medium (72) so that the wiper medium (72) moves over the surface of the printhead array (5) when the maintenance unit (20) moves in the first mode.

6. 6. The printer (1) of claim 5, wherein the printhead maintenance unit (20) further comprises a wetter (22) configured to supply a wetting fluid to the wiping medium (72) held by the at least one wiper unit (70).

7. 7. The method of claim 6, wherein the wetter (22) extends as a beam with a wetting fluid channel in the conveying direction (X), so that a plurality of wiping media (72) of a plurality of wiper units (70) can be supplied via the wetting fluid channel.

8. 8. The printer (1) according to any one of claims 5 to 7, wherein the support comprises a gear rack (31), and the print head maintenance unit (20) is provided with a first drive wheel (26) that engages with the gear rack (31), such that driving of the first drive wheel (26) moves the print head maintenance unit (20) in the lateral direction (Y).

9. 9. The printer (1) according to claim 8, wherein the gear rack (31) a first gear rack segment disposed adjacent to and beside the print medium support surface when viewed in a height direction (Z) perpendicular to the transport direction (X) and the lateral direction (Y); a second gear rack segment extending above the print medium support surface when viewed in the height direction (Z).

10. 10. The printer (1) according to claim 8 or 9, wherein the gear rack (31) comprises a first gear segment comprising a raised rack section (32) above a lower rack section (35) in a height direction (Z) perpendicular to the conveying direction (X) and the lateral direction (Y), and the first drive wheel (26) is connected to the wetter (22), so that: - when the first drive wheel (26) is in the raised rack section (32), the wetter (22) is at a raised level (P1) above the at least one wiper unit (70); - When the first drive wheel (26) is in the lower rack section (35), the wetter (22) is in a lower level (P2) for supplying wetting fluid to the wetter medium (72) of the at least one wiper unit (70).

11. 11. The printer (1) of any one of claims 6 to 10, wherein the drive assembly (30) further comprises a cam mechanism (51) connected to the first drive wheel (26) and the wetter (22), such that when the first drive wheel (26) travels parallel to the lateral direction (Y), the cam mechanism (51) moves the wetter (22) in the lateral direction (Y) from a remote position to engage the wetter medium (72) of the at least one wiper unit (70).

12. 12. The printer (1) of claim 11, wherein at least one upward movement limiter (41) is disposed along the gear rack (31) to prevent the first drive wheel (26) from disengaging from the gear rack (31).

13. 13. The printer (1) according to claim 11 or 12, wherein the cam mechanism (51) is provided with a curved cam surface segment, preferably in the form of a protrusion (44), which applies a reaction force (F) to the first drive wheel (26) when the cam mechanism (51) is at and / or near the missing tooth section (33). ｗ ) to prevent said first drive wheel (26) from disengaging from said gear rack (31).

14. A method for maintaining the performance of a printhead array (5) disposed on a print medium support surface, comprising: - moving the print medium in a transport direction (X) along the printhead array (5); - in a non-cleaning mode, disposing a print head maintenance unit (20) laterally of the print medium support surface in a lateral direction (Y) perpendicular to the transport direction (X), - in a cleaning mode, moving the printhead maintenance unit (20) along the printhead array (5) in the lateral direction (Y) over the print medium support surface.

15. 15. The method of claim 14, wherein moving the printhead maintenance unit (20) moves at least through an entire print range defined by the printhead array (5).

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