Abstract:
An apparatus applies release agent to a printhead face to prevent ink from wetting the surface of the printhead face. The release agent is applied by an applicator that is coupled to a release agent supply by a wicking member. The applicator can be integrated into a wiper for the printhead to enable release agent application and printhead facing wiping to occur at approximately the same time.

Description:
TECHNICAL FIELD 
     This disclosure relates generally to inkjet printers and, in particular, to inkjet printers having automated cleaning systems. 
     BACKGROUND 
     In general, inkjet printers include at least one printhead that ejects drops of liquid ink directly onto recording media or onto a surface of an intermediate image receiving member for transfer to recording media. The intermediate image receiving member in an indirect inkjet printer can be a rotating metal drum or endless belt. In a direct printer, the recording media can be in sheet or continuous web form. A phase change inkjet printer employs phase change inks that are solid at ambient temperature, but transition to a liquid phase at an elevated temperature. Once the melted ink is ejected onto recording media or the surface of an intermediate image receiving member, the ink droplets quickly solidify to form an ink image. 
     Printers typically conduct various maintenance operations to ensure proper operation of the inkjets in each printhead. One known maintenance operation removes particles or other contaminants that may interfere with printing operations from each printhead in a printer. During such a cleaning maintenance operation, the printheads purge ink through some or all of the inkjets in the printhead. The purged ink flows from the apertures of the inkjets that are located in a faceplate of each printhead onto the faceplate. The ink rolls downwardly under the effect of gravity to an ink drip bib mounted at the lower edge of the faceplate or onto a flexure chute mounted on a maintenance station. The drip bib or flexure chute is configured to collect the liquid ink and direct the ink into an ink receptacle. In some printers, one or more wipers are manipulated to contact the faceplate of each printhead and wipe the purged ink toward the drip bib to facilitate the collection and removal of the purged ink. 
     Some of the purged ink may remain on the printhead. Other sources of ink on the printhead include ink that may drool from inkjets during printing of certain frequencies or ink that may drip from other components. Inkjet printheads are typically coated with a hydrophobic material to maintain a low surface energy on the printhead face to enable ink on a printhead to run off the printhead face. However, over time the hydrophobic coating on the printheads wears off and the surface energy of the printhead face increases. The increased surface energy can result in ink adhering to the printhead during printing and maintenance operations and can reduce the pressure at which ink flows from the inkjets onto the printhead and can cause inkjets in the printhead to malfunction or clog, potentially resulting in print defects. Thus, improved surface coating of printheads is desirable. 
     SUMMARY 
     An apparatus for applying release agent to a printhead face has been developed. The apparatus comprises an applicator mounted to a support member, a container configured to store a volume of release agent, a wicking member, and an actuator. The wicking member has a first end and a second end, the first end being submerged in the volume of release agent within the container and the second end being fluidly connected to the applicator to deliver release agent by capillary action from the container to the applicator. The actuator is operatively connected to the support member and configured to move the support member to contact a printhead face with the applicator to apply release agent to the printhead face as the applicator moves past the printhead face. 
     In another embodiment a method of applying a fluid to a printhead face has been developed. The method comprises submerging a first end of a wicking member in release agent stored in a container, delivering the release agent by capillary action to an applicator that is operatively connected to a second end of the wicking member and that is mounted on a support member, and operating an actuator operatively connected to the support member to contact and apply release agent to a printhead face with the applicator. 
     In a yet another embodiment a printer that applies release agent to a printhead has been developed. The printer includes a printhead having a plurality of inkjet ejectors that eject ink through a plurality of apertures in a printhead face, an applicator mounted on a support member, a container configured to store a volume of release agent, a wicking member, and an actuator. The wicking member has a first end and a second end, the first end being submerged in the release agent in the container and the second end being fluidly connected to the applicator to enable the wicking member to deliver release agent by capillary action from the container to the applicator. The actuator is operatively connected to the support member and configured to move the support member to contact the printhead face with the applicator to apply release agent to the printhead face as the applicator moves past the printhead face. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a printhead maintenance station. 
         FIG. 2  is a top view of the printhead maintenance station of  FIG. 1 . 
         FIG. 3  is a side view of another printhead maintenance station. 
     
    
    
     DETAILED DESCRIPTION 
     For a general understanding of the present embodiments, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate like elements. As used herein, the terms “printer,” “printing device” or “imaging device” generally refer to a device that produces an image with one or more colorants on print media and may encompass any such apparatus, such as a digital copier, bookmaking machine, facsimile machine, multi-function machine, etc. which generates printed images for any purpose. 
     The term “printhead” as used herein refers to a component in the printer that is configured with inkjet ejectors to eject ink drops onto an image receiving surface. A typical printhead includes a plurality of inkjet ejectors that eject ink drops of one or more ink colors onto the image receiving surface in response to firing signals that operate actuators in the inkjet ejectors. The inkjets are arranged in an array of one or more rows and columns. In some embodiments, the inkjets are arranged in staggered diagonal rows across a face of the printhead. Various printer embodiments include one or more printheads that form ink images on an image receiving surface. Some printer embodiments include a plurality of printheads arranged in a print zone. An image receiving surface, such as a print medium or the surface of an intermediate member that carries an ink image, moves past the printheads in a process direction through the print zone. The inkjets in the printheads eject ink drops in rows in a cross-process direction, which is perpendicular to the process direction across the image receiving surface. 
     Phase change ink printers use phase change ink, also referred to as a solid ink, which has a solid state at room temperature but melts into a liquid at a higher operating temperature. The liquid ink drops are printed onto an image receiving member or a media sheet. As described in more detail below, both direct and indirect printers apply a coating of release agent to selected components in the printer to prevent phase change ink from adhering to the printer components instead of the print medium. 
       FIG. 1  and  FIG. 2  illustrate a maintenance station  100  for a printhead  180 . The maintenance station  100  includes a wiper mount  140 , a support member  144 , an actuator  136 , a release agent container  104 , a wicking member  116 , and a release agent applicator  124 . The release agent container  104  is mounted to the wiper mount  140  and is configured to hold a volume of release agent  108 . In one practical embodiment the release agent is silicone oil, although other suitable release agents can be used in other embodiments. The release agent container  104  can be open to air, or the container  104  can be closed to prevent the container from spilling the release agent  108  during transport of the maintenance station  100 . In one embodiment the release agent container  104  is sized to store enough release agent for the expected life of the printer in which the maintenance station  100  is installed. In other embodiments the release agent container can be configured to be refilled during the life of the printer. 
     The wicking member  116  includes a first end  118  and a second end  120 . The first end  118  is submerged in the volume of release agent  108  inside the release agent container  104  while the second end  120  is operatively connected to the release agent applicator  124 . The wicking member  116  is formed of a porous material to enable the wicking member  116  to deliver release agent by capillary action from the container  104  to the release agent applicator  124 . In one embodiment the wicking member is made of wool, though in other embodiments polypropylene, cotton, fiberglass, or any other suitable material can be used. The wicking member  116  is surrounded by a plastic tube  112 , which prevents release agent from dripping from the wicking member  116  onto other components in the printer or maintenance station  100 . The tube  112  can be formed of rigid plastic material to enable the tube  112  to retain the wicking member  116  in a fixed position between the first end  118  and the second end  120 , or the tube can be formed of flexible plastic material to enable the tube and wicking member to move in relation to the container and applicator. In other embodiments, the flexible tube can be formed of rubber, latex, steel, or another suitable material. 
     The release agent applicator  124  is mounted above the support member  144  in the embodiment of  FIG. 1 , and, as shown in  FIG. 2 , is configured to extend across a length of a face  184  on the printhead  180 . The release agent applicator  124  is configured to contact the printhead face  184  to apply release agent  108  to the printhead face  184  as the maintenance station  100  wipes the printhead face  184 . The release agent applicator  124  is formed of a porous material to enable the release agent  108  to wet the entire applicator  124  evenly. In one embodiment the release agent applicator  124  and wicking member  116  are formed of a single piece of material, although in other embodiments the applicator and wicking member can be formed of different materials or two or more distinct pieces of the same material. 
     The support member  144  includes a wiper  148  on a first end of the support member  144  configured to contact the printhead face  184  to wipe a plurality of apertures in the printhead face  184 . In the embodiment of  FIG. 1 , the wiper  148  is positioned directly below the release agent applicator  124  to enable the release agent applicator  124  to follow the wiper  148  as the wiper  148  wipes downwardly on the printhead face  184 . On a second end, the support member  144  is fixedly connected to and configured to move with the wiper mount  140 . 
     The actuator  136  is operatively connected to the wiper mount  140  and is configured to move the wiper mount  140  toward and away from the printhead  180 . The support member  144 , wiper  148 , container  104 , tube  112 , wicking member  116 , and release agent applicator  124  move in response to the wiper mount  140  moving to enable the wiper  148  and applicator  124  to move into contact with the printhead face  184 . The actuator  136  can be any suitable linear or rotational actuator, for example, an electric stepping motor or a pneumatic piston. 
     In operation, the printer in which the maintenance station  100  is installed initiates a maintenance cycle. The printhead  180  docks with the maintenance station  100  and the printhead begins a purge by applying a low pressure to an ink reservoir that is fluidly coupled to the inkjet ejectors. This low pressure causes the ejectors to release ink at low pressure onto the printhead face  184 . The majority of the purged ink flows down the printhead face  184 , onto a drip bib  188 , and into an ink receptacle (not shown). In other embodiments a flexure chute mounted to the maintenance station is used in place of a drip bib to direct the purged ink into the ink receptacle. The flexure chute is configured to contact a lower portion of the printhead face to channel the purged ink into an ink receptacle mounted to the maintenance station. The maintenance station  100  is configured to wipe the remaining ink off the printhead face  184  with the wiper  148  and apply release agent with the applicator  124  as the maintenance station  100  wipes the printhead face  184 . 
     To wipe the remaining ink off the printhead face  184 , the actuator  136  extends to push the wiper mount  140 , support member  144 , wiper  148 , release agent container  104 , tube  112 , wicking member  116 , and release agent applicator  124  toward the printhead face  148  until the wiper  148  and applicator  124  contact a top portion of the printhead face  184 . The actuator  136  can retract and extend a plurality of times to dab the printhead face  184  with the wiper  148  to heat the wiper  148  to a predetermined temperature and enable the wiper  148  to wipe the printhead face  184  without ink solidifying on the wiper  148 . 
     The maintenance station  100  is then translated downwardly by a second actuator  160  while the wiper  148  is in contact with the printhead face  184  to wipe the printhead face  184  with the wiper  148  and release agent applicator  124 . As the maintenance station  100  moves downwardly, the wiper  148  urges any ink remaining on the printhead face  184  toward the drip bib  188 , or in other embodiments, flexure chute, and into the ink receptacle. The release agent applicator  124  follows the wiper  148  and applies a thin coating of release agent to the printhead face  124  to ensure that the surface energy on the printhead face  184  remains low, reducing the likelihood of ink flowing from inkjets when the inkjets are not printing or excess ink drooling from the inkjets during printing. Furthermore, application of the release agent to the printhead face  184  reduces abrasion on the printhead face  184  from subsequently wiping the printhead  180 . 
       FIG. 3  depicts another embodiment of a maintenance station  200  for a printhead  280 . The maintenance station  200  includes a wiper mount  240 , a support member  244 , an actuator  236 , a release agent container  204 , a wicking member  216 , and a release agent applicator  224 . The release agent container  204  is fixedly mounted to the wiper mount  240  and is configured to hold a volume of release agent  208 , which, in one embodiment, is silicone oil. The release agent container  204  can be open to air, or the container  204  can be closed to prevent the container from spilling the release agent  208  during transport of the maintenance station  200 . 
     The wicking member  216  includes a first end  218  and a second end  220 . The first end  218  is submerged in the volume of release agent  208  inside the release agent container  204  while the second end is operatively connected to the release agent applicator  224 . The wicking member  216  is formed of a porous material to enable the wicking member  216  to deliver release agent by capillary action from the release agent container  204  to the release agent applicator  224 . The wicking member  216  is surrounded by a plastic tube  212 , which prevents the release agent from dripping from the wicking member  216  onto other components in the printer or maintenance station  200 . 
     The release agent applicator  224  is mounted below the support member  244  in the embodiment of  FIG. 3 , and is configured to extend across a length of the printhead face  284 . The release agent applicator  224  is configured to contact the face  284  of the printhead  280  to apply release agent  208  to the printhead face  284  as the maintenance station  200  wipes the printhead face  284 . The release agent applicator  224  is formed of a porous material to enable the release agent  208  to wet the entire applicator  224  evenly. 
     The support member  244  includes a wiper  248  on a first end of the support member  244  that is configured to contact the printhead face  284  to wipe a plurality of apertures in the printhead face  284  containing inkjet ejectors. In the embodiment of  FIG. 3 , the wiper  248  is positioned directly above the release agent applicator  224  to enable the wiper  248  to follow the release agent applicator  224  as the applicator  224  and wiper  248  wipe downwardly on the printhead face  284 . On a second end, the support member  244  is fixedly connected to and configured to move with the wiper mount  240 . 
     The actuator  236  is operatively connected to the wiper mount and is configured to move the wiper mount  240  toward and away from the printhead  280 . The support member  244 , wiper  248 , container  204 , tube  212 , wicking member  216 , and release agent applicator  224  move in response to the wiper mount  240  moving to enable the wiper  248  and applicator  224  to move into contact with the printhead face  284 . The actuator  236  can be any suitable linear or rotational actuator, for example, an electric stepping motor or a pneumatic piston. 
     In operation, the printer in which the maintenance station  200  is installed initiates a maintenance cycle. The printhead  280  docks with the maintenance station  200  and begins a purge, activating the inkjet ejectors in the printhead face  284  to release ink at a low pressure. The majority of the purged ink flows down the printhead face  284 , onto a drip bib  288 , and into an ink receptacle (not shown). Ink remaining on the printhead face  284  after the purge is wiped off the face by the maintenance station  200 . 
     To wipe the remaining ink off the printhead face  284 , the actuator  236  extends to push the wiper mount  240 , support member  244 , wiper  248 , release agent container  204 , tube  212 , wicking member  216 , and release agent applicator  224  toward the printhead face  284  until the wiper  248  and applicator  224  contact a top portion of the printhead face  284 . The actuator  236  can retract and extend a plurality of times to dab the printhead face  284  with the wiper  248  to heat the wiper  248  to a predetermined temperature and enable the wiper  248  to wipe the printhead face  284  without ink solidifying on the wiper  248 . 
     The maintenance station  200  is then translated downwardly by a second actuator  260  while the wiper  248  is in contact with the printhead face  284  to wipe the printhead face  284  with the wiper  248  and release agent applicator  224 . As the maintenance station  200  moves downwardly, the applicator  224  applies release agent to the printhead face  284 . The wiper  248  follows the applicator  224 , urging any ink remaining on the printhead face  284  toward the drip bib  288  and into the ink receptacle, while also spreading the release agent across the printhead face  284 . The thin coating of release agent left on the printhead face  284  ensures that the surface energy on the printhead face  284  remains low, reducing the likelihood of ink flowing from inkjets when the inkjets are not printing or excess ink drooling from the inkjets during printing. Furthermore, the release agent reduces wear on the printhead face  284  caused by contact with the wiper  248 . 
     It will be appreciated that variations of the above-disclosed and other features, and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art, which are also intended to be encompassed by the following claims.