Improved wiper system for cleaning inkjet printheads in inkjet printers

Abstract

A wiper configuration allows a single wiper to clean a printhead bezel in a printer without requiring solvent to prepare the printhead bezel. The wiper configuration includes a wiper having a hooked end, a mounting rod, and a reinforcement rod. The wiper has two flanges that form a recess that receives the mounting rod, allowing the wiper to be mounted to the mounting rod without the use of threaded components or other fasteners. A pivot axis in the mounting component is positioned at a predetermined distance, approximately ten times the radius of the inside curvature of the hooked end, from the wiper's hooked end.

Description

[0001] Inkjet printers have one or more printheads that eject drops of liquid material, commonly referred to as ink, onto a substrate or previously ejected drops of material. Each printhead contains a plurality of inkjets, typically arranged in an array. Each inkjet has a nozzle that communicates with an opening in an aperture of the printhead to allow one or more drops of material to be ejected from the inkjet and through the opening with which the inkjet nozzle communicates in the aperture. The inkjets can be implemented in a variety of different configurations known to those skilled in the art. Some well-known configurations utilize piezoelectric and thermal ejectors in the inkjets.

[0002] Some of the ink ejected from the inkjets sticks to the aperture and can collect dust and other debris. If the ink and debris are not removed from the aperture, the residual ink and debris can block one or more openings in the aperture. Printhead cleaning is typically performed within a service station mounted inside the printer chassis so that the printhead and the service station can be moved relative to each other for cleaning. In some service stations, an applicator wipes the printhead apertures with a non-volatile solvent to liquefy the residual ink. Then, a pair of wipers moves across the aperture. The first wiper helps spread the solvent across the aperture and loosen the debris from the aperture.The second wiper separates the residual ink and debris from the aperture and moves the residual ink, debris, and solvent into a debris container.

[0003] However, these maintenance stations suffer from a number of limitations. First, they require a supply of non-volatile solvent and an applicator to wipe the aperture with the solvent. The applicator and solvent increase the cost of the printer. In addition, an actuator and mechanical linkages are required to move the applicator. Another limitation is the need for a pair of wipers, each of which provides a different function. This can cause one wiper to wear out more quickly. To simplify maintenance station repair, when one wiper needs replacing, both wipers are replaced. This wastes a portion of the wiper's lifespan and increases the cost of maintaining the printer.

[0004] Another type of printhead wiping system is disclosed in US Patent Number 8,591,001. This system includes a pair of wipers operated to clean different sections of the same printhead. One wiper is raised to engage a printhead aperture at a first location, and then the wiper is moved across a portion of the printhead to wipe a portion of the nozzle openings in the aperture. The wiper is then moved out of engagement with the aperture, and the other wiper is raised into engagement with the aperture at a second location. The other wiper is then moved across a different portion of the printhead to wipe a different portion of the nozzle openings in the aperture. The wiper is then lowered, and the printhead is returned to normal printing operation.The limitations of this type of printhead wiping system include difficulty in adjusting the position of the wiper ends as the wipers wear, the difficulty in maintaining the wiper settings, and the complicated manner of mounting the wipers to support components in the wiping system.

[0005] Publication CN 2 485 134 Y relates to a residual ink wiping device for wiping the surface of a nozzle of an inkjet head, in particular a wiping device capable of preventing the adhesion of residual ink to the side surface of the inkjet head.

[0006] Publication JP 2015 - 33 784 A discloses a liquid jet device that can suppress deterioration of the performance of a wiper and absorb liquid adhering to the wiper by an absorption material.

[0007] Publication US 2003 / 0081054 A1 discloses a curved wiper blade system for an inkjet printing mechanism to remove ink residues from an inkjet printhead installed in the printing mechanism.

[0008] What is needed is a maintenance station that enables efficient cleaning of printheads in an inkjet printer without the need for solvent application or complicated mounting of wipers in the cleaning system.

[0009] A printhead wiping system that enables efficient cleaning of printheads in the printer without the use of solvents and with simplified wiper assembly, includes a wiper having a body terminating in a hook-shaped end, a pair of flanges extending from the wiper body and separated from each other by a predetermined distance, each flange having a bent end to form a C-shaped opening between the flanges, and a pointed end positioned on the wiper body at an end opposite the hook-shaped end and adjacent to one of the flanges, a mounting member positioned within the C-shaped opening between the flanges, the mounting member having a length along its longitudinal axis that is longer than a length of the wiper body along its longitudinal axis, a mechanism operatively connected to the mounting member,to move the hooked end of the wiper body into and out of engagement with a bezel of a printhead, and a translation mechanism to move the hooked end of the wiper body along the bezel of the printhead to wipe at least a portion of the bezel.

[0010] A single wiper that can efficiently clean printheads in an inkjet printer without a solvent and allows simplified wiper assembly includes a wiper body terminating in a hook-shaped end and a pair of flanges extending from the wiper body separated from each other by a predetermined distance, each flange having a bent end to form a C-shaped opening between the flanges.

[0011] The above aspects and other features of a printhead wiping system that efficiently cleans printheads in the printer without solvent are explained in the following description, in conjunction with the accompanying drawings. Fig. 1 is a perspective view of one end of a wiper assembly configured to clean the aperture of one or more printheads in an inkjet printer. Fig. 2A is a perspective view of a wiper assembly having a wiper, a mounting member, and a reinforcement member. Fig. 2B is a cross-sectional view of a wiper assembly shown in Fig. 2A after it has been assembled. Fig. 3 represents the hook-shaped end of the wiper 1 Fig. 1 that remains in contact with a surface while the wiper moves over the surface. Fig. 4A, Fig. 4B and Fig. 4C illustrate a rotating mechanism associated with the wiper assembly of Fig. 2A is operatively connected to lower and raise the wiper with respect to a printhead aperture. Fig. Figure 5 illustrates the relationship between a pivot member and the hook-shaped end of the wiper assembly shown in Fig. 2A is shown. Fig. 6 is a perspective view of a printhead wiper assembly including the rotating mechanism of Fig. 4A to 4C and a pair of wiper assemblies located in Fig. 2A. Fig. 7 is an exploded view of the translation mechanism in the printhead wiper assembly of Fig. 6.

[0012] For a general understanding of the present embodiments, reference is made to the drawings. Throughout the drawings, similar reference numerals have been used to identify similar elements.

[0013] Fig. 1 illustrates a wiper assembly 100 that can clean a portion of a single printhead or a plurality of printheads. The printheads extend in a cross-process direction across a print zone in an inkjet printer. The wiper configuration 100 includes a wiper 104, a mounting member 108, and, in some embodiments, a reinforcement member 112. The wiper 104 has a pair of flanges 116 and a wiper body 120 terminating in a hooked end 124. As used herein, a hooked end means the terminal end of the bent portion of a substantially J-shaped wiper. The mounting member 108 is a substantially rectangular member that is longer along its longitudinal axis than the longitudinal axis of the wiper 104. At each end of the mounting member 108 is a U-shaped slot 128.

[0014] Fig. 2A shows a wiper assembly 100 that includes the reinforcement member 112. The reinforcement member 112 is added to the mounting rod 108 to increase the rigidity of the mounting rod 108 and the wiper 104 when the longitudinal length of the wiper 104 is approximately five times or more greater than the height of the wiper 104. For longitudinal lengths shorter than approximately five times the height of the wiper 104, the reinforcement member 112 is not required. The reinforcement member 112 may be formed integrally with the mounting member 108. Alternatively, as in Fig. 2A, the reinforcement member 112 may be manufactured separately and mounted to the mounting member 108 using threaded members 132 that are passed through mounting holes 136 in the mounting rod 108 and then threaded into threaded holes 140 in the reinforcement member 112. The mounting holes 136 are countersunk to allow the head of the threaded member to be flush with the surface of the mounting member 108. The reinforcement member 112 has approximately the same length as the wiper 104 along its longitudinal axis. This length allows access to the U-shaped slot 128 of the mounting member 108 to connect the mounting member 108 to the actuator 204, as explained below.

[0015] The wiper 104 is made of a somewhat flexible material that can bend as the actuator rotates the wiper into the aperture of a print head.

[0016] Such materials include urethanes, such as polyether urethanes, silicones, and other similar polymer materials. In one embodiment, the wiper is made of a thermoplastic polyurethane, such as 60 Shore A thermoplastic polyurethane. The durometer of the material is in the range of approximately 50 to 70 Shore A, and in most embodiments, in the range of approximately 55 to 65 Shore A. The material is sufficiently tough to retain the arc in the hooked end 124 while the wiper is moved along the aperture of a printhead. As in Fig. 3, this resilience allows the hooked end 124 to be the only portion of the wiper 104 that remains engaged with the printhead aperture while the wiper moves in the direction indicated by the arrow. The curved portion of the hooked end 124 allows the wiper to capture the liquid droplets 280 removed from the aperture by the hooked end 124 and direct the liquid along the surface of the body 120 of the wiper 104 to a pointed end 150 on the wiper 104 ( Fig. 2B). The pointed end 150 directs the collected fluid from the body 120 of the wiper 104 into a dirt container positioned near the pointed end 150.

[0017] The cross-section of the wiper blade, which is Fig. 2B, is the same along the entire length of the wiper. The design of the wiper incorporates features that enable positioning and locking of the wiper around the mounting component 108 as well as providing reliable cleaning of printhead apertures. As a consequence, an extrusion manufacturing process can be used to manufacture the wiper 104. Extruding the wiper 104 significantly reduces manufacturing costs and is very versatile because different lengths of wiper blades can be cut from a single extrusion to provide wipers ranging in length from a few millimeters to more than a meter. Extruding a wiper is much simpler than known wiper manufacturing methods that involve cutting wipers from polymer sheets or molding or overmolding wipers onto metal supports.

[0018] To mount the wiper 104 to the mounting member 108, the flanges 116 are configured to form a C-shaped opening. This opening is manipulated to fit the mounting member 108 within the opening between the flanges 116 to allow the end of the wiper 104 to be positioned in a consistent location. A cross-sectional view of the wiper 104 mounted around the mounting member 108 is shown in Fig. 2B. The unattached ends of the flanges 116 bend around the top and bottom of the mounting member 108 to help secure the wiper 104 around the mounting member 108. The wiper is flexible enough to allow the flanges 116 to stretch to receive the mounting member 108, and once the mounting member 108 is received in the clearance between the flanges 116, they return to their original positions to secure the wiper 104 around the mounting member 108. Configuring the flanges in this manner allows the wiper to be mounted to the mounting member 108 without requiring installation tools, machining holes in the mounting member, or special tools for manipulating fasteners to hold the wiper to the mounting rod.

[0019] A wiper rotation mechanism 400 is in Fig. 4A. As shown in this figure, a mounting lock 208 has two lower openings that receive threaded components 212B that mate with threaded openings in the bracket 200 to secure the mounting lock 208 to the bracket 200. The upper opening in the mounting lock 208 receives a threaded component 212A that is threaded through the mounting slot 128 ( Fig. 1) and into a threaded hole in bracket 200. Mounting component 108 sandwiches mounting lock 208 and bracket 200, and threaded component 212A secures mounting component 108 to bracket 200.

[0020] A cross-sectional view of the rotating mechanism 400 is shown in Fig. 4B. The housing 224 abuts an actuator housing 216 that covers the actuator 2014. Drive 220 of the actuator 204 has an extension 222 that mates with an opening in member 228, which is secured to the bracket 200 with a pin 230. Bracket 200 includes a pivot opening 232 that aligns with an opening 234 in the actuator housing 224 ( Fig. 4A), such that a pivot member 236 is inserted into the aligned openings to enable bracket 200 to rotate pivot member 236 with respect to housing 224. This configuration allows actuator 204 to rotate drive 220, which pushes on extension 222 and bracket 200 to rotate bracket 200 clockwise and rotate wiper end 124 away from its upper position shown in Fig. 4C. The actuator 204 reverses the drive 220 to retract the extension 222 and the bracket 200 to rotate the bracket 200 counterclockwise and pivot the wiper end 124 away from its floor or base position to its upper position, as shown in Fig. 4C. As shown in Fig. 4C, rotation of the bracket 200 moves the wiper end 124 through a vertical distance of 7.2 mm and through an arc of 19.5 degrees, although other dimensions and geometries may be used. A cover 240 covers the housing 224, the bracket 200, and an end portion of the mounting rod 108 ( Fig. 4A). Actuator 204 is operatively connected to a controller 284 that operates actuator 204 in rotating mechanisms 400 in a printhead wiping assembly 600, as described below, to clean printheads in a printer. As used in this document, "mechanism" means one or more components configured to perform a function. A mechanism may include more than one mechanism cooperatively assembled to perform the function.

[0021] As in Fig. 5, the bracket 200 and the mounting member 108, which is secured to the bracket by the lock 208, rotate about the pivot member 236 to rotate the wiper 104 toward and away from the bezel 162, as indicated by the curved arrow R with two heads in Fig. 5. The distance ED extending from the edge of the hooked end 124 to the center of the pivot member 236 is approximately ten times the radius r of the inner curvature of the hooked end 124. This distance allows the wiper body 120 to deflect sufficiently so that only the tip of the hooked end 124 remains in engagement with the bezel 162 without flattening the tip of the end 124. The reinforcement member 112 helps maintain the stability of the mounting member 108 within the recess between the flanges 116 when the wiper length is approximately five times or more greater than the height of the wiper, as previously stated. Thus, the component 108 and the wiper 104 do not distort while the actuator 204 rotates the wiper 104 into the aperture 162, or while the wiper is moved along the aperture 162 to wipe the aperture, as explained in more detail below. Fig. 5 also illustrates a threaded member 244 that rotates bidirectionally to adjust the vertical position of the mounting rod 108 and wiper 104. As the member 244 rotates, it moves the actuator housing 224 vertically relative to support 248 to change the vertical position of the wiper end 124.

[0022] The liquid drops 280, which in Fig. 3 are ink drops that have been rinsed from the printhead or printheads before the actuator 204 rotates the wiper 104 into engagement with the aperture 162. Flushing is typically achieved by applying hydraulic pressure to the ink reservoir within a printhead to force ink through the printhead's inkjets and out through the nozzle openings in the aperture. This flushed ink acts as a solvent on the aperture to liquefy the residual ink and provide a carrier for the debris on the aperture. The configuration of the wiper as presented above allows the hooked end of the wiper to collect the flushed ink, residual ink, and debris and direct them to the pointed end 150 so that they can be removed from the printhead.

[0023] A printhead wiper assembly 600 is in Fig. 6. The assembly 600 includes two wiper assemblies 100A, 100B, each wiper assembly having a rotating mechanism 400 at each end. The rotating mechanisms 400, operatively connected to the wiper assembly 100B as described above, rotate the wiper assembly 100B such that clockwise rotation of the wiper assembly 100B lowers the wiper end 124 and counterclockwise rotation raises the wiper end 124. The rotating mechanisms 400, operatively connected to the wiper assembly 100A as described above, rotate the wiper assembly 100A such that counterclockwise rotation of the wiper assembly 100B lowers the wiper end 124 and clockwise rotation raises the wiper end 124. To move an engaging wiper end 124 in the process direction along the aperture of a printhead, the rotating mechanism 400 includes a frame 612 at each end of the mechanism. Fig. 4A, it is shown in more detail that the frame 612 is mounted by threaded components 624 within a bracket 620. The bracket 620 is mounted to the rotating mechanism by threaded components 628 that extend through the flange 632 formed as part of the bracket 620 to engage threaded holes in the mechanism 400.

[0024] With reference to Fig. 6, the assembly 600 also includes an actuator 608 at each end of the wiper assemblies 100a and 100b, although only one actuator 608 is shown in the view of Fig. 6. The actuator 608, which translates the wiper assemblies 100A and 100B, is shown in more detail in Fig. 7. The actuator 608 is operatively connected to the controller 284 so that the controller can operate the actuator to translate the wiper ends 124 along the apertures of printheads. A transmission component 652 connects the drive 646 of the actuator 608 to a gear box 656. The gear box 656 is protected within a semi-cylindrical cover 660 to which a frame shield 616 is mounted. Frame supports 644 are mounted to the frame 640 with fasteners 648 to help ensure that the frame 640 is horizontal. Guide 618 is secured to the support member 674 and frame 640 by fasteners 668. A similar assembly of another actuator and frame at the other end of the printhead wiper assembly 600 is also provided.When assembled, each end of wiper assembly 100B is positioned so that brackets 620 slide along guides 618 at each end, and the guides force the racks 612 in the rotating mechanisms 400 at each end to remain engaged with gears 656 within semi-cylindrical covers 660. The bidirectional rotation of drives 646 by actuators 608 translates rack 612 and wiper assembly 100B, which is connected to rack 612, along a linear path. The ends of wiper assembly 100A are similarly configured.

[0025] Once the printhead wiper assembly 600 is assembled and installed in a printer, the controller 284 is operatively connected to the actuators 608 in the printhead wiper assembly and the actuators 204 in the rotating mechanisms 400 at each end of the wiper assemblies 100A and 100B. The controller 284 is configured with programmed instructions or instructions remotely transmitted to the printer stored in a memory operatively connected to the controller. The controller 284 executes the programmed instructions to operate the actuators 204 in the rotating mechanisms 400 of the wiper assemblies 100A and 100B to rotate the wiper ends 124 to their ground position, as shown in Fig. 4c. When the assembly is positioned opposite one or more printheads, the controller 284 operates the actuators 204 at each end of both rotating mechanisms 400 to rotate the wiper ends 124 to a first position close to, but not touching, the printhead aperture. For example, the wiper end may be positioned approximately 1 mm from the aperture. Controller 284 then operates the actuators 608 to rotate the gears 656 and translate the carriages 612 at one end of each wiper assembly. This movement moves the wiper end 124 close to the aperture across the printhead to move rinsed ink drops away from the aperture while translating the wiper end 124 across the aperture.Once the wiper assembly reaches the end of its translation path, the controller 284 operates the actuators 608 to move the wiper end 124 back to the position at which it began translating the wiper end. There, the controller 284 operates the actuators 204 in the assembly containing the wiper end 124 that is near the aperture so that the wiper end 124 engages the aperture. The controller 284 then operates the actuators 608 again to translate the wiper ends 124 across the aperture and complete cleaning the aperture while the wiper end engages the aperture during this movement. The controller then operates the actuators 204 in the rotating mechanisms 400 to return the wiper ends 124 of the engaging wiper assembly to the base position shown in FIG. Fig. 4C shown.

[0026] The printhead wiper assembly described above presents several advantages over previously known printhead wiping systems. First, it does not require a solvent or solvent applicator. This factor simplifies the wiper assembly and eliminates the need for two wipers to perform two different solvent-related functions. The wiper described above can be mounted to the mounting component without the need for special tools or fasteners. Furthermore, the vertical position of the wiper can be adjusted simply by turning a threaded component, and the adjustment remains stable thereafter.

Claims

[1] Wiper (104), comprising: a wiper body (120) terminating in a hook-shaped end (124); a pair of flanges (116) extending from the wiper body (120) separated from each other by a predetermined distance, each flange (116) having a bent end to form a C-shaped opening between the flanges. [2] The wiper (104) of claim 1, further comprising: a pointed end (150) positioned on the wiper body (120) at an end opposite the hook-shaped end (124) and adjacent to one of the flanges (116). [3] Printhead wiper assembly (600) comprising: a wiper (104) having a body (120) terminating in a hook-shaped end (124), a pair of flanges (116) extending from the wiper body (120) and separated from each other by a predetermined distance, each flange having a bent end to form a C-shaped opening between the flanges (116), and a pointed end (150) positioned on the wiper body (120) at an end opposite the hook-shaped end (124) and adjacent to one of the flanges (116); a mounting member (108) positioned within the C-shaped opening between the flanges (116), the mounting member (108) having a length along its longitudinal axis that is longer than a length of the wiper body (120) along its longitudinal axis; a mechanism (400) operatively connected to the mounting member (108) for moving the hooked end (124) of the wiper body (120) into and out of engagement with a bezel (162) of a printhead; and a translation mechanism (608) for moving the hooked end (124) of the wiper body (120) along the aperture (162) of the printhead to wipe at least a portion of the aperture (162). [4] The printhead wiper assembly (600) of claim 3, further comprising: a reinforcing member (112) extending from the mounting member (108) between the bent ends of the flanges (116). [5] The printhead wiper assembly (600) of claim 4, wherein the reinforcement member (112) is mounted to the mounting member (108) with at least one threaded member (132), a head of the at least one threaded member (132) being adjacent to the wiper body (120). [6] The printhead wiper assembly (600) of claim 3, wherein the mechanism (400) that moves the hooked end (124) of the wiper body (120) into and out of engagement with the aperture (162) of the printhead is a first rotating mechanism. [7] The printhead wiper assembly (600) of claim 6, wherein the first rotating mechanism further comprises: a bracket (200) operatively connected to the mounting member (108), the bracket (200) being positioned over a pivot member (236); and at least one actuator (204) operatively connected to the mount (200), the at least one actuator (204) being configured to rotate the mount (200) about the pivot member (236) to rotate the mounting member (108) and the wiper (104) to engage and disengage the printhead aperture (162) from the wiper (104). [8] The printhead wiper assembly (600) of claim 7, further comprising: a controller (284) configured to operate the at least one actuator (204) in the first rotating mechanism to rotate the wiper (104) between a first position and a second position, and to operate the at least one actuator (204) in the translating mechanism (608) to move the wiper (104) across the aperture (162) of the printhead when the wiper (104) is at the second position. [9] The printhead wiper assembly (600) of claim 8, further comprising: another wiper having a wiper body terminating in a hook-shaped end, a pair of flanges extending from the other wiper body and separated from each other by a predetermined distance, each flange of the other wiper having a bent end to form a C-shaped opening between the flanges, and a pointed end positioned at an end opposite the hook-shaped end and adjacent to one of the flanges; another mounting member positioned within the C-shaped opening of the other wiper between the flanges, the mounting member having a length along its longitudinal axis that is longer than a length of the wiper body along its longitudinal axis; a second rotating mechanism operatively connected to the other mounting member, the second rotating mechanism having at least one other actuator configured to rotate the other wiper between the first position and the second position to bring the hooked end of the other wiper body into and out of engagement with the aperture of the printhead; and wherein the controller is further configured to: Operating the at least one actuator in the first rotating mechanism to rotate the wiper to the first position; Operating the at least one actuator in the second rotating mechanism to rotate the other wiper to the second position; Operating the at least one actuator in the translation mechanism to reverse the movement of the other wiper across the aperture of the printhead when the other wiper is in the second position. [10] The printhead wiper assembly (600) of claim 8, wherein the hooked end (124) of the wiper (104) is close to the aperture (162) when the wiper (104) is in the second position, but the hooked end (124) does not engage the aperture (162).

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