RETRACTABLE PRINTHEAD WIPER FOR PRINTHEAD MAINTENANCE UNITS

Abstract

A printhead maintenance system for a printing machine having at least one printhead, the system includes a body, at least one guide track supporting the body for movement along the at least one guide track in proximity to the face of the printhead, and a drive mechanism in engagement with the body and operable to move the body along the guide track. A wiper blade is movably mounted on said body for movement between a retracted position in which the wiper blade cannot contact the face of the printhead and an operative position in which the wiper blade can contact the face of the printhead. A biasing mechanism is provided between the wiper blade and the body that is configured to bias the wiper blade to the operative position. The system includes a retraction mechanism that is operable to move the wiper blade to the retracted position upon movement of the body along the guide track.

Claims

1. A printhead maintenance system for a printing machine having at least one printhead, the system comprising: a body; at least one guide track supporting said body for movement along the at least one guide track in proximity to the face of the printhead; a drive mechanism in engagement with said body and operable to move the body along the at least one guide track; a wiper blade movably mounted on said body, said wiper blade moveable between a retracted position in which the wiper blade cannot contact the face of the printhead and an operative position in which the wiper blade can contact the face of the printhead; a biasing mechanism between said wiper blade and said body configured to bias said wiper blade to said operative position; and a retraction mechanism operable to move said wiper blade to said retracted position upon movement of said body along said at least one guide track.

2. The printhead maintenance system of claim 1, wherein said biasing mechanism includes: a blade mount rotatably mounted on said body, said blade mount carrying said wiper blade, said blade mount rotatable between a first position in which said wiper blade is in said retracted position, and a second position in which said wiper blade is in said operative position; and a biasing spring between said blade mount and said body configured to bias said blade mount to said second position.

3. The printhead maintenance system of claim 2, wherein said biasing mechanism includes: a mounting bracket mounted on said body; and an axle engaged to said mounting bracket and rotatably supporting said blade mount, wherein said biasing spring is a torsion spring mounted on said axle and having a first leg engaged to said blade mount and a second leg engaged to said mounting bracket.

4. The printhead maintenance system of claim 1, wherein said retraction mechanism includes: an elongated support bracket fixed to said at least one guide track such that the body is movable relative to said support bracket; a cam element fastened to said wiper blade and arranged to contact said support bracket to push said wiper blade to said retracted position upon movement of said body along said at least one guide track.

5. The printhead maintenance system of claim 4, wherein said support bracket defines a cut-out along the length thereof, said cut-out being substantially co-extensive with the length of the printhead.

6. The printhead maintenance system of claim 1, wherein said drive mechanism includes: an actuator connected to one end of said at least one guide track; and a drive element connected between said actuator and said body and operable to move said body along the at least one guided track by operation of said actuator.

7. The printhead maintenance system of claim 6, wherein: said actuator is a motor with a rotating output shaft; said drive element is a lead screw connected to said rotating output shaft for rotation therewith by operation of said motor; and said body includes a threaded nut fixed thereto and in threaded engagement with said lead screw so that rotation of said lead screw causes movement of said body along the at least one guided track.

8. The printhead maintenance system of claim 1, further comprising a frame structure mountable in the printing machine and fixed in relation to said body and said wiper blade, said frame structure, including said at least one guide track.

9. The printhead maintenance system of claim 8, wherein said frame structure includes: pair of mounting rails mountable in the printing machine; and a pair of spaced apart support plates, said at least one guide track connected at its opposite ends to a corresponding one of said support plates, and said drive mechanism connected between one of said support plates and said body.

10. The printhead maintenance system of claim 9, wherein said drive mechanism includes: an actuator connected to said one of said support plates; and a drive element connected between said actuator and said body and operable to move said body along the at least one guide track by operation of said actuator.

11. The printhead maintenance system of claim 1, wherein body includes a purge receptacle adjacent said wiper blade and configured for receiving liquids purged from the printhead.

12. A printhead maintenance system for a printing machine having at least two rows of printheads parallel and near each other along the length of the printheads, the system comprising: two wiper assemblies, one each associated with a corresponding row of printheads, each wiper assembly including; a body; at least one guide track supporting said body for movement along the at least one guide track in proximity to the face of the printhead; a drive mechanism in engagement with said body and operable to move the body along the at least one guide track; a wiper blade movably mounted on said body, said wiper blade moveable between a retracted position in which the wiper blade cannot contact the face of the printhead and an operative position in which the wiper blade can contact the face of the printhead; a biasing mechanism between said wiper blade and said body configured to bias said wiper blade to said operative position; and a retraction mechanism operable to move said wiper blade to said retracted position upon movement of said body along said at least one guide track.

13. The printhead maintenance system of claim 12, further comprising a frame structure mountable in the printing machine and fixed in relation to said body and said wiper blade of each of said two wiper assemblies, said frame structure, including said at least one guide track of each of said two wiper assemblies.

14. The printhead maintenance system of claim 13, wherein said frame structure includes: pair of mounting rails mountable in the printing machine; and for each of said two wiper assemblies, a pair of spaced apart support plates, said at least one guide track connected at its opposite ends to a corresponding one of said support plates, and said drive mechanism connected between one of said support plates and said body.

15. The printhead maintenance system of claim 14, wherein said drive mechanism includes: an actuator connected to said one of said support plates; and a drive element connected between said actuator and said body and operable to move said body along the at least one guide track by operation of said actuator.

16. The printhead maintenance system of claim 12, wherein said biasing mechanism for each of said two wiper assemblies includes: a blade mount rotatably mounted on said body, said blade mount carrying said wiper blade, said blade mount rotatable between a first position in which said wiper blade is in said retracted position, and a second position in which said wiper blade is in said operative position; and a biasing spring between said blade mount and said body configured to bias said blade mount to said second position.

17. The printhead maintenance system of claim 12, wherein said retraction mechanism for each of said two wiper assemblies includes: an elongated support bracket fixed to said at least one guide track such that the body is movable relative to said support bracket; a cam element fastened to said wiper blade and arranged to contact said support bracket to push said wiper blade to said retracted position upon movement of said body along said at least one guide track.

18. The printhead maintenance system of claim 1, wherein said drive mechanism of each of said two wiper assemblies includes: an actuator connected to one end of said at least one guide track; and a drive element connected between said actuator and said body and operable to move said body along the at least one guided track by operation of said actuator.

19. The printhead maintenance system of claim 18, wherein: said actuator is a motor with a rotating output shaft; said drive element is a lead screw connected to said rotating output shaft for rotation therewith by operation of said motor; and said body includes a threaded nut fixed thereto and in threaded engagement with said lead screw so that rotation of said lead screw causes movement of said body along the at least one guided track.

20. The printhead maintenance system of claim 12, wherein said body of each of said two wiper assemblies includes a purge receptacle adjacent said wiper blade and configured for receiving liquids purged from the printhead.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The foregoing aspects and other features of a system and method for wiping a printhead faceplate and an inkjet printer having a retractable wiper blade for faceplate cleaning are explained in the following description, taken in connection with the accompanying drawings.

[0017] FIG. 1 is a schematic drawing of an aqueous inkjet printer that prints ink images directly to a web of media and that attenuates evaporation of fast drying inks from the printheads of the printer.

[0018] FIG. 2 is a perspective view of a print bar with multiple printheads in a stitched configuration.

[0019] FIG. 3 is a perspective view of a maintenance system according to one embodiment of the present disclosure.

[0020] FIG. 4 is a top view of the maintenance system shown in FIG. 3.

[0021] FIG. 5 is a side view of the maintenance system shown in FIG. 3.

[0022] FIG. 6 is a cross-sectional view of the maintenance system shown in FIG. 3, with the cross-section taken along a guide rail of the system and with a retractable wiper in a first retracted position.

[0023] FIG. 7 is an enlarged view of the retractable wiper from the cross-sectional view of FIG. 6.

[0024] FIG. 8 is an enlarged cross-sectional view of the retractable wiper shown in FIG. 7, with the cross-section taken through the retractable wiper.

[0025] FIG. 9 is a cross-sectional view of the maintenance system shown in FIG. 3, with the cross-section taken along a drive element of the system and with the retractable wiper in the retracted position.

[0026] FIG. 10 is an enlarged view of the retractable wiper from FIG. 7 with the retractable wiper in a second intermediate extended position.

[0027] FIG. 11 is an enlarged view of the retractable wiper from FIG. 8 with the retractable wiper in the intermediate extended position.

[0028] FIG. 12 is a cross-sectional view of the maintenance system shown in FIG. 3, with the cross-section taken along a guide rail of the system and with a retractable wiper in the intermediate extended position.

[0029] FIG. 13 is a cross-sectional view of the maintenance system shown in FIG. 3, with the cross-section taken along a guide rail of the system and with a retractable wiper in a third extended operative position.

[0030] FIG. 14 are side and top view of the maintenance system of FIG. 3, with the retractable wiper in the retracted position.

[0031] FIG. 15 are side and top view of the maintenance system of FIG. 3, with the retractable wiper in the intermediate extended position.

[0032] FIG. 16 are side and top view of the maintenance system of FIG. 3, with the retractable wiper in the extended operative position.

DETAILED DESCRIPTION

[0033] For a general understanding of the environment for the inkjet printer and its operation as disclosed herein, reference is made to the drawings. In the drawings, like reference numerals designate like elements.

[0034] A maintenance assembly 10, shown in FIGS. 3-6, is configured to perform maintenance operations on the staggered printheads shown in FIG. 2. In particular, the assembly includes a first wiper assembly 12A arranged over the first row of printheads PH1, PH3, and a second wiper assembly 12B arranged over the second row of printheads PH2, PH4. The maintenance assembly can be configured to be removably mounted within the printing machine, such as the machine 110 described above, such as by mounting rails 13 configured to slide within corresponding brackets (not shown) in the printing machine. It is contemplated that the brackets that receive the mounting rails 13 are part of the overall printing machine maintenance assembly and are configured to be moved as necessary to orient the maintenance assembly 10 over a selected printhead or pair of printheads. It is understood that the printing machine is configured to hold the maintenance assembly 10 in a storage position apart from the printheads until a printhead maintenance procedure is requested. When maintenance is requested, the printing machine moves the mounting rails 13, and thus the entire maintenance assembly 10, to its operative position adjacent the face of the printheads being serviced.

[0035] The maintenance assembly 10 disclosed herein includes a frame structure 11 engaged between the mounting rails 13 and carrying two wiper assemblies 12A, 12B for simultaneously cleaning two printheads or rows of printheads. It should be understood that the maintenance assembly 10 can be modified to include only one wiper assembly depending on the maintenance need of the particular printing machine. The frame structure 11 includes support plates 14a, 14b that are engaged to the mounting rails. The support plates are configured to support a pair of guide tracks 16 for each pair of wiper assemblies, with the tracks extending between opposite support plates 14a, 14b. The support plate 14a for each wiper assembly supports an actuator 18, as part of a drive mechanism for the moving the wiper assembly along the guide tracks. In one embodiment the actuator is a stepper motor capable of incremental motion. The drive mechanism includes a drive element 17 extending between the actuator 18 at the support plate 14a and the opposite support plate 14b.

[0036] The frame structure 11 for the wiper assemblies includes a pair of support brackets 15, each extending between the support plates 14a, 14b for each wiper assembly. The support brackets 15 are arranged at the top of the wiper assemblies, between the wiper assemblies and the printheads when the maintenance assembly is in its operational position. The support brackets are also configured to flank the printhead when the maintenance assembly is in its operative position to perform maintenance on the printheads. In particular, when the maintenance assembly is in the operative position the printheads occupy the space between the two support brackets 15. The support brackets 15 each define an elongated cutout 15a that is essentially coextensive with the distance that the wiper assemblies must travel to clean one of the printheads PH1-PH4, or to clean a line of printheads, such as printheads PH1, PH3, or PH2, PH4.

[0037] Each wiper assembly 12A, 12B includes a body 21 that defines a purge receptacle 20 is sized and configured to receive the debris and ink expelled during operation of the purge system 124 (FIG. 1), as well as the debris scraped off the face of the printheads by the wiper assembly. The body 21 defines a pair of bearing mounts 22 at opposite ends of the body, as best seen in FIG. 4, 6. Each bearing mount includes a pair of spaced-apart bushings 23, each configured to receive a corresponding one of the guide tracks 16 extending therethrough. The bushings 23 allow the body 21 to slide smoothly from one end of the guide tracks at support 14a to the opposite end at support 14b.

[0038] The purge receptacle 20 is engaged to the actuator 18 through the drive element 17. In one embodiment, the drive element 17 is a threaded shaft or lead screw with external threads 17a configured to engage an internally threaded nut 28 fixed within the bearing mount 22. The end 17b of the drive element is engaged to the output shaft 18a of the actuator by an adaptor 18b. A pair of set screws 18c clamp the adaptor onto the two shafts. The opposite end of the drive element is rotatably supported in a support plate 14b. The actuator 18 can be a stepper motor configured to rotate the output shaft 18a, and thus the lead screw 17, in controllable amounts to precisely translate the purge receptacle 20. The threaded engagement between the nut 28 and the lead screw cases the nut, and thus the purge receptacle, to move along the length of the lead screw in a known manner. The drive element 17 propels the purge receptacle and the guide tracks 16 help stabilize the receptacle as it moves along the drive element.

[0039] In the illustrated embodiment, the body 21 of the purge receptacle 20 is supported by a pair of guide tracks 16. Other guide track configurations are contemplated, such as a single guide track that supports the body in conjunction with the drive element 17. In addition, in lieu of bushings 23 disposed in the bearing mount 22, the bearing mount can be formed of a low friction material with a pair of bores defined in the bearing mount to substitute for the separate bushings.

[0040] In one feature of the maintenance assembly 10, a retractable wiper 30 is associated with each purge receptacle 20. As shown in FIG. 6, the body 21 includes a wiper mounting region 25 immediately adjacent to one end of the receptacle 20. A mounting bracket 25 is associated with the bearing mount 22 and includes a base 25a with a pair of paced apart arms 25b, so that the mounting bracket is generally U-shaped. Referring to FIGS. 7-8 and 10, the retractable wiper 30 includes a blade 31 with a lip 31a that is configured to scrape debris and excess fluid from the surface of a printhead. The lip 31a is preferably formed of an elastomeric material capable of flexing under pressure without damaging the printhead. The blade 31 can be formed of the same elastomeric material or can incorporate a stiffer material, including a metal. The blade 31 is clamped within a blade mount 33 by a clamping plate 33a held by a pair of mounting bolts 34 (FIG. 10). The body 21 is configured and arranged on the guide tracks so that the purge receptacle 20 and the retractable wiper 30 are aligned with the printheads when the maintenance assembly is in its operative position to perform maintenance on the faces of the printheads.

[0041] An axle 35 extends through a bore 33b in the blade mount 33 and is anchored at the two arms 25b of the mounting bracket 25. The blade mount 33, and thus the wiper blade 31, is able to rotate about the axle 35 between a first stowed or retracted position shown in FIGS. 6-9 and a second intermediate extended position shown in FIGS. 10-13. The retractable wiper 30 is biased to the extended position by a torsion spring 36 mounted on the axle 35. One arm 36a of the torsion spring is engaged within a bore 37 defined in the blade munt 33, as shown in FIG. 8. The other arm 36b of the spring is engaged within a bore 38 defined in the mounting bracket 25. Thus, the arm 36b of the torsion spring acts as the anchor while the arm 36a is free to rotate about the axle 35, pulling the blade mount 33 and wiper blade 31 with it.

[0042] The retractable wiper 30 includes a retraction mechanism that automatically retracts the wiper blade 31 when the retractable wiper is a one end of the guide tracks 16, namely at the end engaged to the support plate 14a. The retraction mechanism includes a cam 40 affixed to the blade mount 33 by a bridge member 33a so that the cam is disposed outside one of the arms 25b of the mounting bracket 25, as shown in FIG. 7. The cam 40 includes a cam surface 40a that bears against the underside of the support bracket 15 immediately adjacent the cutout 15a. The cam 40 is arranged relative to the axle 35 and torsion spring 36 to operate against the spring when the cam 40 is pushed downward toward the wiper mounting region 24. Conversely, the torsion spring exerts a constant force to move or pivot the cam upward. In the position shown in FIG. 7, the support bracket 15 prevents the upward movement of the cam, and ultimately the upward rotation of the wiper blade 31, thereby maintaining the retractable wiper in its retracted position. However, when the cam 40 moves relative to the support bracket, the cam enters the cutout 15a, as shown in FIG. 10. In this position, the cam is no longer restrained by the support bracket and is thus free to move upward from the force of the torsion spring. Thus, the entire retractable wiper 30 is free to rotate upward so that the wiper blade 31 is in the operative position shown in FIGS. 10-13 in which the wiper can contact the face of the printhead. The retractable wiper 30 rotates until the bridge member 33a of the blade mount contacts the arm 25b of the bracket. The retraction mechanism is operable to retract the retractable wiper 30 when the body 21 is moved toward the support plate 14a and the cam 40 moves toward the cutout 15a until the cam surface 40a contacts the edge of the support bracket 15 at the cutout. Further movement of the body causes the support bracket to push against the cam surface to move the retractable wiper to its retracted position.

[0043] The retractable wiper 30 is moved from the retracted position of FIG. 7 to the extended position of FIG. 10, by operation of the actuator 18. In particular, rotation of the drive element 17 by the actuator interacts with the threaded nut 28 to move the body 21 longitudinally along the guide tracks 16. As the actuator continues to operate, the body 21 moves from one end of the cutout 15a to the opposite end of the cutout, as shown in FIG. 13. Thus, as shown in the sequence of FIGS. 14-16, the retractable blade 30 starts in is first retracted position, with the cam 40 held down by the support bracket 15, and then as the actuator drives the body 21 of the purge receptacle along the guide tracks, the retractable blade pivots upward into contact with the cutout 15a in the second intermediate extended position, and finally into contact with the printhead PH2 in the third extended position. The retractable blade remains in contact with the printhead PH2 as the body 21 of the purge receptacle continues to travel to the position shown in FIG. 16. It can be appreciated that the torsion spring 26 can have a spring force sufficient to constant pressure between the wiper blade 31, and particularly the lip 31a, and the face of the printhead PH2 as the wiper blade is drawn across the face of the printhead. It can further be appreciated that the amount of pivoting or rotation of the blade mount 33 is limited by contact with the arm 25b of the mounting bracket 25, with the amount of rotation calibrated so that the lip 31a contacts the printhead face at an optimum angle for cleaning the printhead.

[0044] When the retractable blade reaches the end of the cleaning stroke, the actuator is reversed, drawing the wiper assembly back to its starting retracted position. As the cam approaches the cutout 15a in the support bracket 15, the cam surface 40a contacts the support bracket, pushing the cam downward and rotating the blade mount 33 against the biasing force of the torsion spring 36. As the wiper blade 31 passes across the face of the printhead PH2, the debris and excess liquid is directed to the purge receptacle 20 for subsequent disposal.

[0045] In the illustrated embodiment, the wiper assemblies 12A, 12B are configured to operate in unison to clear the faces of staggered printheads PH1, PH2. The maintenance assembly 10 (FIG. 3) can then be shifted to align the two rows of wiper assemblies with the printheads PH3, PH4. Alternately, the wiper assemblies can be configured to travel across two printheads in a single stroke. In this alternative approach, the guide tracks 16 and drive element 17 would be lengthened to traverse printhead pair PH1, PH3 and PH2, PH4 (FIG. 2). It is further contemplated that the maintenance assembly 10 can be moved within the printing machine to other rows or pairs of rows of printheads in a multi-printhead machine, in a manner known in the art. The movement of the maintenance assembly between rows of printheads as well as the operation of the wiper assemblies 12A, 12B, and their associated actuators 18, can be controlled by a controller, such as the controller 180 (FIG. 1). The maintenance assembly is moved into its operative position prior to initiation of a purge cycle by the purge system 124 of the printing machine. Once the purge cycle is complete, the controller can activate the two wiper assemblies to complete the maintenance cycle for the particular printheads. The maintenance assembly 10 of the present disclosure can be integrated into a printing machine and operated to perform maintenance on printheads in a manner similar to that described in U.S. Pat. No. 8,529,015, which issued to the present applicant on Sep. 10, 2013, or in U.S. Pat. No. 8,366,237, which issued to applicant on Feb. 5, 2013, the disclosures of which are incorporated herein by reference.

[0046] The retractable wiper 30 of the present disclosure utilizes a biasing element to bias the wiper blade 31 into contact with the face of the printhead during a cleaning stroke. The wiper assemblies 12A, 12B are also configured to push the respective retractable wiper into the retracted position against the force of the biasing element when the wiper assemblies are in a purge position. In this position, the printheads are purged to drive excess liquid (ink) from the printhead into the purge receptacles 20. The wiper blade 31 is retracted to protect it from the heated liquid during the purge process. Once the purge process is complete, the actuator 18 drives the wiper assemblies across the printheads, with the wiper blade extending into contact with the printhead face.

[0047] In the illustrated embodiment, the biasing element is the torsion spring 36 that is configured to generate a torque to rotate the retractable wiper 30 to its extended, active position. In an alternative embodiment, the biasing element can be one or more compression springs disposed between the wiper mounting region 24 and the blade mount 33, with the compression springs biased to rotate the retractable wiper about the axle in the same manner as the torsion spring. Even in this configuration, the interaction between the cam 40 and the support bracket cutout 15a pushes the retractable wiper against the spring force to its retracted position.

[0048] It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems, applications or methods. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements may be subsequently made by those skilled in the art that are also intended to be encompassed by the following claims.