Abstract:
In one embodiment, a component for dispensing a fluid includes: a plurality of fluid ejection orifices arrayed in a plane; and an elongated bumper extending along one side of the array generally in a plane intersecting the plane of the array and the bumper having a protruding exterior surface that includes a first part inclining away from the array and a contiguous second part inclining back toward the array.

Description:
BACKGROUND 
     The operation of inkjet printers sometimes results in unwanted excess ink accumulating on the printhead(s) in areas around the ink ejection orifices. Such ink accumulation may interfere with accurate ink drop ejection or otherwise adversely affect print quality. Servicing to remove excess ink from a printhead often involves wiping the orifice plate and adjacent areas with a flexible blade or other suitable wiper. The wiper moves back and forth across the orifice plate and adjacent areas, removing excess ink to areas away from the orifice plate. Wiper servicing, however, can leave waste ink accumulations at the perimeter of the wiper path still in close proximity to the print zone. After extended use this waste ink may build-up in sufficient quantity to droop or dislodge onto or otherwise contact the print media, resulting poor quality printed output. 
    
    
     
       DRAWINGS 
         FIG. 1  is a perspective view illustrating an inkjet printer, according to one embodiment of the disclosure. 
         FIGS. 2 and 3  are perspective views illustrating the printhead assembly from the printer shown in  FIG. 1 , according to one embodiment of the disclosure. 
         FIG. 4  is a detail, exploded view showing the wiper bumper on the printhead assembly of  FIGS. 2 and 3 . 
         FIG. 5  is a detail view (not exploded) showing the wiper bumper on the printhead assembly of  FIGS. 2 and 3 . 
         FIG. 6  is a detail partial section view showing the wiper bumper on the printhead assembly of  FIGS. 2 and 3 . 
         FIG. 7  is a detail partial section view showing a second embodiment of a wiper bumper for a printhead assembly such as the one shown in  FIGS. 2 and 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the disclosure were developed in an effort to remove waste ink from the wiper during wiper servicing of an inkjet printhead and to keep the unwanted waste ink away from the print zone. Embodiments will be described with reference to an inkjet printhead assembly that holds replaceable ink containers. Embodiments of the disclosure, however, are not limited to such printhead assemblies, but might also be implemented in other types of printhead assemblies or ink cartridges, specifically including but not limited to ink cartridges in which the printhead assembly and the ink container are integrated into a single unit/cartridge. The use of inkjet technology for dispensing fluids other than ink is growing. Embodiments of the disclosure are also not limited to inkjet printer components, but might also be implemented in other types of fluid dispensing components. The example embodiments shown in the Figures and described below, therefore, illustrate but do not limit the scope of the disclosure. 
     As used in this document, “bumper” means something configured to bump or be bumped. Any directional terms such as “up” and “down”, “left” and “right”, “top” and “bottom”, etc., are used with reference to the orientation of the component being described as shown in the applicable figure(s). Such components, however, may be oriented differently from that shown and, therefore, directional terms are used for illustration only and do not limit the scope of the disclosure. 
       FIG. 1  illustrates an inkjet printer  10  implementing one embodiment of the disclosure. In an operating inkjet printer  10 , sheets of paper or other print media are fed from a feed tray  12 , through a print zone  14 , to an output tray  16 . Inside a printer housing  18 , a guide rod  20  mounted to a chassis  22  supports a reciprocating carriage  24 . Carriage  24  carries a printhead assembly  26  back and forth on guide rod  20  through print zone  14 . Replaceable ink containers  30  and  32  are mounted in printhead assembly  26 . A printer motor operating under the direction of an electronic controller (not shown) within housing  18  moves carriage  24  and printhead assembly  26  back and forth through print zone  14  and into and out of a service station  28 . Service station  28  includes a wiper sled  34  that carries flexible wipers  36  and  38  back and forth across the face of printhead assembly  26 . A service station  28  might also include capping and purging functions to prevent or clear clogged ink ejection orifices. 
       FIGS. 2 and 3  are perspective views showing in more detail printhead assembly  26  without ink containers  30  and  32 . Referring to  FIGS. 2 and 3 , printhead assembly  26  includes a printhead  40  mounted in a body  42  of assembly  26 . Printhead  40  is mounted to body  42  so that it will be located immediately adjacent to print zone  14  when printhead assembly  26  is mounted in carriage  24  in printer  10 , as shown in  FIG. 1 . For the printer configuration shown in  FIG. 1 , printhead  40  is mounted at the bottom of assembly  26 . Body  42  defines a bay  44  for holding one or more removable/replaceable ink containers, such as ink containers  30  and  32  shown in  FIG. 1 . Printhead  40  includes an orifice plate  46  with multiple arrays  48  of tiny ink ejection orifices  50 . (Individual orifices  50  may be seen in  FIGS. 4-7 .) 
     In the embodiment shown, each array  48  is a single row of orifices  50 . Also in the embodiment shown, printhead assembly  26  includes two orifice plates  46 , each corresponding to a printhead  40  associated with each ink container  30  and  32 . In one such dual printhead configuration, ink container  30  might contain three different colored inks, typically cyan, magenta and yellow, and ink container  32  might contain a single colored ink, typically black. Each printhead  40  may be constructed separately as a discrete die or the two printheads  40  may be constructed as an integral unit on a single die. Other configurations are possible. For example, orifice rows  50  could be staggered and a separate container used for each color ink. 
     In a thermal inkjet printer, firing resistors formed on an integrated circuit chip as part of each printhead  40  are positioned behind orifice plate  46 . A flexible circuit  52  carries electrical traces from external contact pads  54  to the firing resistors. When printhead assembly  26  is installed in printer  10  ( FIG. 1 ), printhead assembly  26  is electrically connected to the printer controller through contact pads  54 . In operation, the printer controller selectively energizes the firing resistors through the signal traces in flexible circuit  52  to eject drops of ink through orifices  50 . In a piezoelectric inkjet printer, piezoelectric firing elements are used instead of thermal resistors to eject ink drops. 
     Referring now also to the detail views of  FIGS. 4-6 , orifice plates  46  generally define a face  56  along the bottom of printhead assembly  26 . As noted above, each printhead  40  and, correspondingly, each orifice plate  46  is mounted to assembly body  42 . Part of body  42  will typically extend around orifice plates  46  as part of face  56 . Also, orifice plates  46  may be positioned adjacent to those portions of flex circuit  52  that extend along the bottom of assembly  26 , as shown in  FIG. 3 , and/or recessed slightly into body  42 . Face  56 , therefore, may not be perfectly flat or smooth. Thus, face  56  defines a generally planar surface extending along orifice plates  46 . (For clarity due to the small size of orifice plates  46  in the perspective views of  FIGS. 4 and 5 , only one row of orifices  50  on each orifice plate  46  is shown.) 
     A wiper bumper  58  extends across one side  60  of body  42  at one end of face  56 . Side  60  is generally perpendicular to face  56 . Although side  60  may intersect face  56  at other angles, more or less than 90°, the problem of handling waste ink is more difficult when side  60  and face  56  intersect one another at a relatively sharp corner, as is quite common. A contoured rail  61  across the end  62  of face  56  may be used to help protect the edge of flex circuit  52  and to provide a smooth transition for wiper  36  ( FIG. 6 ) between face  56  and bumper  58 . Waste ink removed from wiper  36  may accumulate in a cavity  62  immediately above bumper  58  away from face  56  and, accordingly, away from print zone  14  when printhead assembly  26  is installed in printer  10  ( FIG. 1 ). In the absence of bumper  58  and cavity  62 , waste ink would tend to accumulate on face  60  near its intersection with face  56 . Waste ink accumulated in this area on face  60 , which is very close to the print zone, is more likely to dislodge and fall into the print zone than waste ink accumulated either in cavity  62  or on the upper face  72  of bumper  58 . 
     Bumper  58  may be a separate part affixed to assembly body  42 , as shown in  FIGS. 4-6 , or bumper  58  may be formed as an integral part of assembly body  42 . In the embodiment shown in  FIGS. 4-6 , bumper  58  is properly positioned in body  42 , for example, by means of a key  64  projecting from the back side of bumper  58  and a mating keyway  66  in body  42 . The use of a mating key/keyway or other suitable assembly structure also helps maintain bumper  58  in the proper position throughout the numerous wiping operations that occur over the life of printhead assembly  26 . Exterior surface  68  on bumper  58  includes a lower part  70  that inclines up and away from face  56 , an upper part  72  that inclines up and back in toward face  56 , ending at cavity  62 , and an apex part  74  joining lower part  70  and upper part  72 . 
     It is desirable to size and shape bumper  58  so that: (1) inclining exterior surface lower part  70  moderates the otherwise abrupt edge at the end of face  56  as wiper  36  moves to the left in  FIG. 6 , smoothing the transition from the wiped surfaces on face  56  to subdue ink flicking off left-side wiper face  76 ; (2) apex part  74  intercepts wiper  36  low enough when wiper  36  is moving to the right in  FIG. 6  to remove wiped ink that accumulates on right-side wiper face  78  (which is ink wiped from face  56  as wiper  36  moves left to right in  FIG. 6 ); and (3) ink accumulating on bumper  58  moves up along inclined exterior surface upper part  72  toward cavity  62  as wiper  36  repeatedly bumps bumper  58 . For example, for a wiper  36  that extends about 4 mm above face  56 , typical in some inkjet printer service stations, it is expected that a bumper  58  2-4 mm high (the direction perpendicular to the plane of face  56 ), protruding 1-4 mm from side  60  at apex part  74  between 45° inclining parts  70  and  72  will subdue ink flicking, remove ink accumulating on wiper face  76 , and move that ink toward cavity  62 . 
     The location and shape of the print media is usually well controlled by feed/pinch rollers so that it remains flat as it enters the print zone and begins to pass under face  56 , but may not remain flat at the end of the print zone opposite the pinch rollers. (The print media passes under face  56  moving from right to left in FIGS.  2  and  4 - 7 .) The pinch rollers contact dry media just upstream from the print zone while at the other end of the print zone the printed media may be heavily wetted with ink and can swell and cockle (undulating wrinkles). Additionally, the shape and location of the wetted print media at the end of the print zone opposite the pinch rollers is more difficult to control. Thus, it is more likely the print media will contact any waste ink which, in the absence of bumper  58 , could accumulate along the lower edge of side  60 . Bumper  58  helps prevent waste ink from accumulating along the lower edge of side  60 . The action of wiper  76  on bumper surface parts  70  and  74  helps keep ink from accumulating on those surfaces, reducing the risk of waste ink contacting print media in the print zone. 
     In the embodiment shown in  FIGS. 4-6 , apex part  74  transitions over a short distance between lower part  70  and upper part  72  to form a bulbous bumper  58  in which lower part  70  and upper part  72  are about the same length and incline at about the same angle. Other configurations are possible. For example, in an alternative embodiment shown in  FIG. 7 , the apex part  74  of bumper  58  extends for a long distance, about the same as the length of each inclined part  70  and  72 , to isolate waste ink further from the print zone. Ribs  80  along the top of bumper  58  may be used to strengthen bumper  58 . Also in the embodiment shown in  FIG. 7 , bumper  58  is formed as an integral part of assembly body  42 , and cavity  62  is recessed down into body  42  below the top surface of bumper  58  to increase the volume of space available away from the pint zone to hold waste ink. For another example, it may be desirable in some embodiments to provide a more abrupt apex (part  74 ) for scraping ink from wiper  76 . 
     The present disclosure has been shown and described with reference to the foregoing example embodiments. It is to be understood, however, that other forms, details and embodiments may be made without departing from the spirit and scope of the disclosure which is defined in the following claims.