Patent Publication Number: US-7210761-B2

Title: Wiper apparatus and method for cleaning a printhead

Description:
BACKGROUND 
   Printing devices, such as and inkjet printer, typically contain at least one wiper apparatus for cleaning one or more printheads of ink cartridges. The printhead fires ink through a plurality of nozzles in the nozzle plate of the printhead and a wiper of the wiper apparatus wipes the plurality of nozzles between print jobs to prevent the nozzles from clogging. 
   In some printer devices each printhead has a separate nozzle plate and each nozzle plate has a separate wiper apparatus for wiping the nozzle plate to prevent cross-contamination of inks and to reduce the incidence of clogging. The use of separate nozzle plates and wiper apparatuses to prevent ink clogging can be very costly. In other printer devices two adjacent wipers of one or more wiper apparatus, are used to clean adjacent nozzles of a single nozzle plate. In some applications cross-contamination of inks along adjacent wipers causes increased clogging of the nozzles which is undesirable. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The example embodiments of the present invention can be understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Also, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       FIG. 1  is a perspective view of an inkjet printer showing one form of a service station according to an embodiment of the invention; 
       FIG. 2A  is a perspective view of the wiper apparatus shown in the service station of  FIG. 1  according to an embodiment of the invention; 
       FIG. 2B  is a perspective view of a wiper apparatus that can be located in the service station of  FIG. 1  according to an embodiment of the invention; 
       FIG. 3  is a side elevation view of the wiper apparatus of  FIG. 2A  and  FIG. 2B  according to an embodiment of the invention; 
       FIG. 4  is a cross-sectional view of a printhead and a front elevation view of the wiper apparatus of  FIG. 2A  and  FIG. 2B  with the wiper apparatus in contact with the printhead during wiping according to an embodiment of the invention; 
       FIG. 5  is a cross-sectional view of a printhead and a front elevation view of the wiper apparatus in contact with the printhead during wiping according to an embodiment of the invention; 
       FIG. 6  is a cross-sectional view of the wiper apparatus in contact with the printhead taken along the lines  6 — 6  of  FIG. 5  according to an embodiment of the invention; 
       FIG. 7  is a perspective view of the wiper apparatus of  FIG. 6  according to an embodiment of the invention; 
       FIG. 8  is a cross-sectional view of the wiper apparatus in contact with the printhead of  FIG. 1  according to an embodiment of the invention; 
       FIG. 9  is a perspective view of the wiper apparatus of  FIG. 8  according to an embodiment of the invention; 
       FIG. 10A  is a cross-sectional view of a wiper apparatus in contact with the printhead of  FIG. 1  according to an embodiment of the invention; 
       FIG. 10B  is a cross-sectional view of a wiper apparatus in contact with the printhead of  FIG. 1  according to an embodiment of the invention; 
       FIG. 11  is a cross-sectional view of a wiper apparatus in contact with the printhead of  FIG. 1  according to an embodiment of the invention; 
       FIG. 12  is a perspective view of a wiper apparatus according to an embodiment of the invention; 
       FIG. 13  is a side elevation view of the wiper apparatus of  FIG. 12  wiping a printhead along a first direction of wipe according to an embodiment of the invention; 
       FIG. 14  is a side elevation view of the wiper apparatus of  FIG. 12  wiping a printhead along a second direction of wipe according to an embodiment of the invention; and 
       FIG. 15  is a cross-sectional view of the wiper apparatus in contact with the printhead taken along the lines  15 — 15  of  FIG. 14  according to an embodiment of the invention. 
   

   DETAILED DESCRIPTION 
     FIG. 1  illustrates an example embodiment of the present invention in the environment of a printer device, for example, inkjet printer  100 . A variety of ink-jet printers are commercially available and can include, for example, portable printing units, copiers, facsimile machines, plotters video printers, and cameras, to name a few. While the concepts of the present invention are illustrated with respect to inkjet printer  100  for convenience, the concepts can also apply to the various ink-jet printer types. 
   In operating the ink jet printer  100 , sheets of print media are fed into the ink jet printer  100  through feed tray  102 . The print media is moved through the print zone  104 , typically by motor-driven rollers (not shown) inside the enclosure  106 . After an image is printed on the print media, the print media exits the enclosure  106  onto output tray  107  or its equivalent. 
   Inside the enclosure  106 , a guide rod  108  is mounted to chassis  110  to support a reciprocating carriage  112  which travels in two directions along a single axis, along the print zone  104 . A printer motor driven by a controller (not shown) propels the reciprocating carriage  112  along the guide rod  108 . The reciprocating carriage  112  is also propelled along guide rod  108  into a servicing station  114  where the printheads  116  and  118  of ink cartridges  122  and  124 , commonly known as pens, are each wiped by a wiper apparatus  130  and  132 , respectively. The printheads  116 ,  118  of ink cartridge  122 ,  124  travel back and forth along the guide rod  108  shooting drops of ink onto the print media as it moves. To clean and protect the printhead, typically a service station can perform a variety of functions including capping and purging or priming to prevent or clear up clogging. 
   Ink cartridges  122  and  124  can each contain two or more inks, each having a distinct ink composition, for example, ink compositions of different color. For example, the ink can include, but is not limited to, dye-based inks, pigment based inks, thermoplastic inks, composite inks having dye and pigment characteristics, and combinations thereof. Ink cartridge  122  contains a first ink  126  and a second ink  127 , and ink cartridge  124  contains a third ink  128  and a fourth ink  129 . For example, printhead  116  can dispense a black pigment-based ink and a cyan pigment-based ink which are contained in ink cartridge  122 , and printhead  118  can dispense a magenta pigment based ink and a yellow pigment based ink that are contained in ink cartridge  124 . Many combinations of ink compositions and color are possible within a single printhead, such as printheads  116 ,  118 . 
     FIG. 2A  is a perspective view of wiper apparatus  130  of  FIG. 1  that cleans printhead  116  between print jobs to remove ink residue and other debris. Wiper apparatus  130  includes wiper base  202  and a first wiper  204  and a second wiper  206  which extend from wiper base  202 . In accordance with an embodiment of the present invention, first wiper  204  and second wiper  206  each have a capillary passageway  250  and  252 , respectively, which draw inks  126 ,  127  ( FIG. 1 ) away from the printhead  116  (in phantom) during wiping, the details of which will be further described below. Although several aspects of the present invention are described with respect to the wiper apparatus  130  of  FIG. 2A , wiper apparatus  130  can include a single wiper, for example first wiper  204  or second wiper  206 , rather than both wipers  204 ,  206 , in alternative embodiments. 
   The first wiper  204  and second wiper  206  can be positioned substantially orthogonal to the nozzle plate  210  of printhead  116  (in phantom) above the wiper apparatus  130 . Nozzle plate  210  has a plurality of very small nozzles  212  (in phantom) through which the first ink  126  and the second ink  127  residing in printhead  116  are fired. The arrangement of nozzles  212  in  FIG. 2A  includes a first nozzle array  220  that is a two-column linear array, and a second nozzle array  222  that is a two-column linear array. Many alternative nozzle arrangements, including but not limited to, three-column or more linear arrays and random, rather than linear, nozzle arrays, for example, are also possible. The first nozzle array  220  fires drops of the first ink  126  ( FIG. 1 ) and the second nozzle array  222  fires drops of the second ink  127  ( FIG. 1 ), both of which are contained in ink cartridge  122 . The first ink  126  and the second ink  127  may be different compositions as described above. The number of nozzles  212  per unit area of the nozzle plate  210  dedicated to each ink is the nozzle density, and can contribute to the resolution of images printed. Clogs in the printhead  116  can be cleared by periodically firing ink through the plurality of nozzles  212  in a process known as spitting. Wiper apparatus  130  cleans the nozzle plate  210  of printhead  116  to remove ink residue and other debris that collects on the nozzle plate  210 . 
   Still referring to  FIG. 2A , both the first wiper  204  and the second wiper  206  have leading contact surfaces,  232 ,  262 , that face outwards along the leading sides  233  and  263 , respectively, and trailing contact surfaces  234 ,  264 , that face inward and opposite each other along trailing sides  235  and  265 , respectively. The leading contact surfaces  232 ,  262 , and the trailing contact surfaces  234 ,  264 , are the exterior, outer layer portions of the wipers that contact the printhead  116 , and can be at least one of many contour shapes, for example, rounded, angled, sharp-edged, etc. As the wiper apparatus  130  moves during wiping in the direction of wipe indicated by arrow  230 , and away from the home position of service station  114  ( FIG. 1 ) the plurality of nozzles  212  of nozzle plate  210  are initially wiped by leading contact surface  232  of first wiper  204  and subsequently wiped by trailing contact surface  234  of second wiper  206 . In alternative embodiments, wiper apparatus  130  is bidirectional and can also wipe in direction  260 , opposite direction  230 . As the wiper apparatus  130  moves in direction  260 , the plurality of nozzles  212  are first contacted by the leading contact surface  262  of second wiper  206  and subsequently wiped by the trailing contact surface  264  of first wiper  204 . To return to the home position in service station  114 , the wiper apparatus  130  moves across the printhead  116  parallel to the two-column linear arrays  220 ,  222  in direction  260  to complete a second wipe of the nozzle plate  210 . In embodiments having a single wiper, for example, a first wiper  204  or a second wiper  206 , the wiper apparatus  130  moves in two directions to complete one wipe of the nozzle plate  210 . For example, as the wiper apparatus  130  having a wiper  204  moves in direction  230  away from the home position of service station  114  ( FIG. 1 ), the plurality of nozzles  212  are initially wiped by leading contact surface  232 . The wiper apparatus  130  then moves in direction  260  and the nozzles  212  are contacted by the trailing contact surface  264  as the wiper apparatus  130  returns to the home position. 
   As mentioned above, when the first and second wipers  204 ,  206  pass across the printhead  116 , the capillary passageways  250 ,  252  draw ink away from the nozzle plate  210  by capillary forces to prevent or substantially prevent ink mixing on the wiper surfaces which are in contact with the plurality of nozzles  212  of the nozzle plate  210 . The capillary passageways  250 ,  252  define a first tip  282  and a second tip  284  of first wiper  204 , and a third tip  286  and a fourth tip  288  of second wiper  206 , respectively. The width of each capillary passageway  250  and  252 , i.e. the distance of separation between the first tip  282  and the second tip  284 , and the distance between the third tip  286  and the fourth tip  288 , respectively, can be any width that enables capillary flow of a liquid, for example, the inks  126 ,  127 , into the capillary passageways  250 ,  252 . The size of the capillary passageways  250 ,  252  which allow capillary flow can depend upon the surface tension of the particular inks used, the type of material that is used to make the wipers  204 ,  206 , as well as other factors known by those of ordinary skill in the art. In some embodiments, the width of the capillary passageways  250 ,  252  can be about 0.5 millimeters or less. 
   The length of each of the capillary passageways  250 ,  252  can also vary and the length of each capillary passageway  250 ,  252  is greater than their respective widths. In  FIG. 2A  capillary passageway  250  extends from the leading side  233  to the trailing side  263  of first wiper  204 , and capillary passageway  252  extends from the leading side  235  to the trailing side  265  of second wiper  206 . In alternative embodiments, the length of each capillary passageway  250 ,  252  can be one of several distances between the leading side  233  and the trailing side  263  of first wiper  204 , and the leading side  235  and the trailing side  265  of second wiper  206 , respectively. Therefore, the length of the capillary passageway can be greater than the width, and in some embodiments the length is at least about four times greater than the width. 
   The capillary passageways  250 ,  252  of  FIG. 2A  intersect leading contact surfaces  232 ,  262  and trailing contact surfaces  264 ,  234 , respectively, although it is not necessary that the capillary passageways intersect these surfaces. For example, it is possible that inks  126 ,  127  which accumulate along the wipers  204 ,  206  can wick along a capillary passageway that intersects at least one of the leading contact surfaces  232 ,  262  and the trailing contact surfaces  264 ,  234 , and alternatively, into capillary passageways that do not intersect either of the leading contact surfaces  232 ,  262  and trailing contact surfaces  264 ,  234 . The inks  126 ,  127  come into contact with one another as they are drawn away from the nozzle plate  212  and along capillary passageways  250 ,  252  of wipers  204  and  206 , respectively. 
   Each of the capillary passageways  250 ,  252  of  FIG. 2A  are substantially straight passageways oriented along an axis that intersects the leading contact surfaces  232 ,  262  and the trailing contact surfaces  264 ,  234  of first and second wipers  204 ,  206 , respectively. The length of capillary passageways  250 ,  252  extends along an axis that is parallel or substantially parallel to the directions of wipe  230 ,  260 ; however, in alternative embodiments of the present invention, the capillary passageways  250 ,  252  can be oriented along one of many axes that intersect the leading contact surfaces  232 ,  262  and trailing contact surfaces  264 ,  234 . In addition, capillary passageways  250 ,  252  can extend along the same or different axes. In alternative embodiments, the longitudinal contour of the capillary passageways  250 ,  252  can be non-linear. For example, the capillary passageways  250 ,  252  may have one or more curvatures along their respective lengths. 
   The depth of each capillary passageway  250 ,  252  can vary, and the depth can extend from the top of first and second wipers  204 ,  206  to one of many vertical distances up to the overall vertical height of each of the first and second wipers  204 ,  206  as will be described in further detail below. The width of the capillary passageways  250 ,  252  can be constant along the depth of the capillary passageways. 
   Still referring to  FIG. 2A , the first wiper  204  and the second wiper  206  are positioned such that during wiping, the first tip  282  and third tip  286  come into contact with the first nozzle array  220  and the second tip  284  and the fourth tip  288  come into contact with the second nozzle array  222 . The capillary passageways  250 ,  252  pass along a separation zone  221  between the first nozzle array  220  and the second nozzle array  222 . In this arrangement, the capillary passageways  250 ,  252  pass between the first and second nozzle arrays,  220 ,  222 , and the wiping action draws the first ink  126  from the first nozzle array  220  and the second ink  127  from the second nozzle array  222  toward each other. The first ink  126  and the second ink  127  are wicked into the capillary passageways  250 ,  252  by capillary forces which cause the first and second inks  126 ,  127  to adhere to the surface of the wipers  204 ,  206  and the surfaces which define the capillary passageways  250 ,  252 . In the same manner described above with respect to wiping apparatus  130 , the wiper apparatus  132  ( FIG. 1 ) includes capillary passageways which allow third ink  128  and fourth in  129  to be drawn away from the printhead  118  ( FIG. 1 ) and toward the wiper apparatus  132 . 
   As mentioned above, the depth dimensions of the capillary passageways  250 ,  252  can vary and may extend from the top of the first and second wipers  204 ,  206 , to the wiper base  202 , respectively. In  FIG. 2A  the capillary passageway  250  extends from the top of the first wiper  204  to a depth indicated by distance a 1 , and capillary passageway  252  extends from the top of the second wiper  206  to a depth indicated by distance a 2 . Distances a 1  and a 2  can be different or equal. The first tip  282  and the second tip  284  are integrated portions of a single blade, that is, the first wiper  204 ; and the third tip  286  and the fourth tip  288  are integrated portions of a single blade, that is, the second wiper  206 . In alternative embodiments (not shown), the first tip  282  and the second tip  284  can be completely separated by the capillary passageway  250  so that the first tip  282  is a portion of a first blade and the second tip is a portion of a second blade of the first wiper  204 , and the third tip is a portion of a third blade and the fourth tip is a portion of a fourth blade of second wiper  206 . 
   Inks  126  and  127 , if chemically reactive, can readily solidify when drawn into capillary passageways  250 ,  252 , however, the solidification can facilitate easier cleaning of the first and second wipers  204 ,  206 . For example, capillary passageways  250 ,  252  which extend a distance a 1  and a 2 , respectively, may become completely filled with mixed inks which may be reacted inks and may be dried inks. However, the first wiper  204  and the second wiper  206  can be cleaned, for example, by a scraper (not shown) that deflects the first and second wipers  204 ,  206  through dimensional interference between the wiper apparatus  130  and the scraper. Thus, for example, the first wiper  204  can be cleaned by a scraper that deflects the first tip  282  and the second tip  284  upon contact through dimensional interference, and thereby easily dislodging mixed inks collected in capillary passageway  250 . Once cleared, capillary passageway  250  is ready to collect additional inks  126 ,  127  in a subsequent wiping stroke. The volume of ink  126 ,  127 , that can be drawn by capillary passageways  250  and  252  can be determined, in part, by the depth of the capillary passageways, the extent to which the capillary passageways  250 ,  252  can be cleaned, as well as other factors known to one of ordinary skill in the art. For example, capillary passageways  250  and  252  can have additional capillary pathways (not shown) that branch outward from the capillary passageways  250 ,  252  ( FIG. 2A ), to form capillary passageways having a tree-like structure. Regardless of the amount of inks  126 ,  127  that are drawn into the capillary passageways  250 ,  252  upon initial wiping, the amount of ink  126 ,  127  that can be drawn into the capillary passageways  250 ,  252  upon subsequent wiping, may depend upon the amount of ink that can reasonably be removed when the wiper is cleaned via scraping or otherwise. 
     FIG. 2B  is a perspective view of a wiper apparatus  290  according to another embodiment of the present invention, which can be used to clean printhead  116  ( FIG. 1 ). Details regarding the operation of the wiper apparatus  290  as it pertains to cleaning a printhead, for example, printhead  116 , is consistent with that described above with regard to wiper apparatus  130  of  FIG. 2A . Wiper apparatus  290  includes wiper base  202  and a first wiper  291  and a second wiper  292  which extend from the wiper base  202 . The first wiper  291  and the second wiper  292  each have at least one capillary passageway,  293 ,  294 , respectively, formed therein to prevent or substantially prevent ink mixing of the two or more inks fired from an ink cartridge, for example ink cartridge  122  ( FIG. 1 ). Both the first wiper  291  and the second wiper  292  have leading contact surfaces,  295 ,  296 , that face outwards along the leading sides  297  and  298 , respectively, and trailing contact surfaces  301 ,  302 , that face inward and opposite each other along the trailing sides  303  and  304 , respectively. 
   The leading contact surfaces  295 ,  296 , and the trailing contact surfaces  301 ,  302 , are the exterior, outer layer portions of the wipers that contact the printhead  116 , and can be one of many contour shapes, for example, rounded, angled, sharp-edged, etc. Capillary passageway  293  of first wiper  291  extends along an axis that intersects the leading contact surface  295  and the trailing contact surface  301  of the first wiper  291  to define a first tip  306  and a second tip  308  of first wiper  291 . Capillary passageway  294  of second wiper  292  also extends along an axis that intersects the leading contact surface  296  and the trailing contact surface  301  of the second wiper  292  to define a third tip  310  and a fourth tip  312  of second wiper  292 . The capillary passageways  293 ,  294  extend into wipers  291 ,  292  along both the leading sides  297 ,  298  and the trailing sides  303 ,  304  in a webbed capillary passageway arrangement. The inks  126 ,  127  can flow into each of these webbed capillary passageways  293  and  294  to prevent or substantially prevent ink mixing along the wiper surfaces which are in contact with the purality of the nozzles  212 . 
   The capillary passageways  293 ,  294  of  FIG. 2B  intersect leading contact surfaces  295 ,  296  and trailing contact surfaces  301 ,  302 , respectively, however, in some embodiments, capillary passageway  293  can extend along a portion of the axis that intersects the leading contact surface  295  and trailing contact surface  301 , and capillary passageway  294  can extend along a portion of the axis that intersects the leading contact surface  296  and the trailing contact surface  302 . That is, the capillary passageways  293 ,  294  may intersect at least one of the leading contact surfaces  295 ,  296 , and the trailing contact surfaces  301 ,  302 , respectively. In alternative embodiments, the capillary passageways  293 ,  294  may not intersect any of the leading contact surfaces  295 ,  296  and trailing contact surfaces  301 ,  302 . As described above, with respect to capillary passageways  250 ,  252  of wiper apparatus  130  in  FIG. 2A , the capillary passageways  293 ,  294  can extend along an axis that is parallel or substantially parallel to the directions of wipe  230 ,  260 , and in some embodiments of the present invention, the capillary passageways  293 ,  294  can extend along one of many axes that intersect the leading contact surfaces  295 ,  296  and trailing contact surfaces  301 ,  302 . In addition, capillary passageways  293 ,  294  can each extend along an axis that is the same or different. 
   Referring to  FIG. 3  a side elevation view of wiper apparatus  130  reveals the contours of the first and second wipers  204 ,  206  according to another embodiment of the invention. The vertical positioning of the wiper apparatus  130  under the printhead  116  results in interference between the nozzle plate  210  and the wipers  204  and  206 , which causes the wipers  204 ,  206  to deflect in order to draw and squeegee ink for cleaning. The vertical interference between the nozzle plate  210  and the wipers  204  and  206  can be, for example, at least about 1 millimeter, and in some embodiments the interference is greater than about 2 millimeters. 
   The leading contact surfaces  232  and  262  are rounded and the trailing contact surfaces  264  and  234  are angular, having a cornered edge, to facilitate improved cleaning of the nozzle plate  210 . The rounded leading contact surfaces  232 ,  262  pull ink out of the plurality of nozzles  212  to wet the nozzle plate  210  and to help prevent scratching of the printhead  116  by the first and second wipers  204 ,  206 . The ink can also act as a solvent to dissolve dried ink residue accumulated on the nozzle plate  210 . The angular contour of trailing contact surfaces  264 ,  234  squeegees the ink, paper fibers, and other debris as pressure is applied on the nozzle plate due to the dimensional interference between the wiper apparatus  130  and the nozzle plate  210 . 
     FIG. 4  is a cross-sectional view of printhead  116  and is provided for reference to more detailed features of the printhead. Ink  126  and ink  127  are dispensed through tapered openings  402  and  404  of printhead  116  and through a plurality of nozzles  212  formed through nozzle plate  210  of die  406 . Upon exiting the tapered openings  402  and  404 , inks  126  and  127  flow into fluidic chambers  420 ,  422  and circulate around barrier geometry  410  that is heated by underlying heating elements (not shown). Thin film layer  412  contains electrical circuitry logic to control the firing of the ink  126  and  127  through the plurality of nozzles  212 . 
   As described above with respect to  FIG. 2A , the wiper  204  passes below the plane in which the plurality of nozzles  212  are formed. The capillary passageway  250  passes between the first nozzle array  220  and the second nozzle array  222  and draws ink  126  away from the nozzle plate  210  while preventing, or substantially preventing, ink  126  from wicking across the first wiper  204  from the first nozzle array  220  to the second tip  284  and to the second nozzle array  222 . The capillary passageway  250  also draws ink  127  away from the nozzle plate  210  while preventing, or substantially preventing, ink  127  from wicking across the first wiper  204  from the second nozzle array  222  to the first tip  282  and to the first nozzle array  220 . Thus, capillary passageway  252  passes between the first nozzle array  220  and the second nozzle array  222  and draws inks  126  and  127  away from the nozzle plate  210  while preventing, or substantially preventing, cross-contamination of inks  126  and  127 . The capillary passageway  250  is shown terminating at a location  430  of wiper  204 , however, the capillary passageway can have a depth along any vertical distance of the wiper, as describe above with respect to  FIG. 2A . 
   Turning to  FIG. 5  is a partial cross-sectional view of a printhead  116  as it is contacted by wiper apparatus  500  in accordance with another embodiment of the present invention. First wiper  504  has a first tip  506  and a second tip  508  which are oriented at an angle with respect to each other to separate the flow of the first ink  126  and the second ink  127  from one another during wiping on the same nozzle plate  210 . Inks  126 ,  127  which exit the printhead  116  through a plurality of nozzles  212  in nozzle plate  210  are pushed in outward directions toward the edges of the orifice plate  210 . 
   A cross-section of wiper apparatus  500  taken along lines  6 — 6  of  FIG. 5  is illustrated in  FIG. 6 . The first wiper  504  and the second wiper  604  perform a “snowplow” unidirectional wipe along nozzle plate  210  of printhead  116 . The first tip  506  and the second tip  508  of first wiper  504  and the third tip  606  and the fourth tip  608  of second wiper  604  are each oriented at an angle with respect to the direction of wipe  230 . The first tip  506  lies along axis  603  and oriented along an angle α 1  relative to the direction of wipe  230 . The second tip  508  lies along the axis  605  and oriented along an angle α 2  relative to the direction of wipe  230 . The third tip  606  lies along the axis  607  and oriented along an angle α 3  relative to the direction of wipe  230 . The fourth tip  608  lies along the axis  609  and oriented along an angle α 4  relative to the direction of wipe  230 . As wiper apparatus  500  moves in the direction of wipe  230 , the first tip  506  of first wiper  504  wipes the nozzle plate  210  in a direction that is substantially perpendicular to a first axis  603 , the second tip  508  of first wiper  504  wipes the nozzle plate in a direction that is substantially perpendicular to the second axis  605 , the third wiper  606  of second wiper  604  wipes the nozzle plate in a direction that is substantially perpendicular to the third axis  607 , and the fourth wiper  608  of second wiper  604  wipes the nozzle plate in a direction that is substantially perpendicular to the fourth axis  609 . The first axis  603 , the second axis  605 , the third axis  607  and the fourth axis  609  can each be distinct from one another. The angles α 1 , α 2 , α 3 , α 4  can each be greater than about 90 degrees relative to the axis of wipe  230 . In some embodiments of the present invention, the angles α 1 , α 2 , α 3 , α 4  can be greater than about 90 degrees and less than about 180 degrees, and yet in other embodiments, they can range from about 120 degrees to about 150 degrees. The combined angle between the first tip  506  and the second tip  508  of wiper  504  can be at least about 180 degrees, and the combined angle between the third tip  606  and the fourth tip  608  of second wiper  604  can be at least about 180 degrees. The angles α 1 , α 2 , α 3 , α 4  can be substantially equal to one another, or the angles may be different from each other, or some angles may be substantially equal and some may be different than the others. 
     FIG. 7  is a perspective view of wiper apparatus  500  described above with reference to  FIG. 5  and  FIG. 6 . Leading contact surfaces  704  and  706  of the first tip  506  and the second tip  508 , respectively, of the first wiper  504  can be rounded, and the trailing contact surfaces  708  and  710  of the third tip  606  and the fourth tip  608 , respectively, of second wiper  604  can be angled. Therefore, when the wiper apparatus  500  makes a unidirectional wipe in the direction  230 , the rounded contour of contact surfaces  704 ,  706  of the first and second tips  506 ,  508  draws ink out of the plurality of nozzles  212  ( FIG. 6 ) to wet the nozzle plate  210  ( FIG. 6 ). The angular contour of the trailing contact surfaces  708  and  710  of the third tip and fourth tip  606 ,  608 , respectively, squeegee the inks  126 ,  127 , ( FIG. 1 ). Referring to  FIG. 7  the first tip  506  and the second tip  508  of the first wiper  504  are integrated portions of two separate and distinct wiper blades mounted on wiper base  702 . However, in alternative embodiments, the first tip  506  and the second tip  508  of first wiper  504  can be separated portions of a single wiper blade mounted on the wiper base  702  (not shown). Likewise, the third tip  606  and the fourth tip  608  of the second wiper  604  can be integrated portions of separate and distinct wiper blades, as illustrated in  FIG. 7 , however, the tips  606 ,  608  can also be separated portions of a single wiper blade (not shown). The flexibility, movement and wiping performance of wiper apparatus  500  may be enhanced when the first wiper  504  and the second wiper  604  have tips that are at least partially separated, i.e. when the first tip  506  is separated from second tip  508 , and third tip  606  is separated from fourth tip  608 . 
   In an alternative embodiment of the invention, the wiper apparatuses described above can also include cheek wipers. Wiper apparatus  802  of  FIG. 8  and  FIG. 9  include cheek wipers  804  and  806  which function to remove residual ink that collects on nozzle plate  210  and the printhead  116  and which cannot be contacted by the reach of the first wiper  504  and the second wiper  604 . In  FIG. 8 , the cross-sectional view of wiper apparatus  802  in contact with the printhead  116  shows that the left cheek wiper  804  can extend a lateral distance b 4  beyond the first tip  506  of first wiper  504  and a lateral distance b 3  beyond the third tip  606  of the second wiper  604 . Also, the right cheek wiper  806  can extend a lateral distance b 2  beyond the second tip  508  of first wiper  504  and a lateral distance b 4  beyond the fourth tip  608  of second wiper  604 . The distances b 1 , b 2 , b 3  and b 4  can be equal or unequal to one another. For example, first wiper  504  and second wiper  604  are shown in alignment relative to one another, although the positioning of the left cheek wiper  804  relative to the first wiper  504  and second wiper  604 , i.e. distance b 1  and distance b 3 , can be different. Also, the placement of the right cheek  806  wiper need not be symmetrical to the placement of the left cheek wiper  804 . 
   In the embodiment shown in  FIG. 8  for example, cheek wipers  804  and  806  extend beyond the printhead die  406  to ensure that all residual ink outside the reach of first wiper  504  and the second wiper  604  that is collected on the printhead  116  can be wiped. In some embodiments, the cheek wipers  804 ,  806  can reach as far as a location between the nozzle plate  210  and the outer edge of printhead die  406 , as well as distances closer to the first wiper  504  and second wiper  604 . The cheek wipers  804 ,  806  are sized and positioned such that they can overlap the wiping path of the first and second wipers  504 ,  604 , in addition to extending beyond the cheek wipers. In addition, the cheek wipers  804 ,  806  can be located between the first and second wipers  504 ,  604 , as shown in  FIG. 8 , however in alternative embodiments (not shown), cheek wipers  804 ,  806  can be located behind both the first and second wipers  504 ,  604 . 
   A perspective schematic of the wiper apparatus  802  of  FIG. 8  is illustrated in  FIG. 9 . In one embodiment, first tip  506  and second tip  508  have leading contact surfaces  704  and  706 , respectively, which have a rounded contour to allow the tips  506 ,  508  to pull ink from nozzles  212  to wet the nozzle plate  210 , as described above with respect to wiper apparatus  130  in  FIG. 3 . Cheek wipers  804  and  806  have leading contact surfaces  904  and  906 , respectively, which are rounded surfaces, however, the leading contact surfaces  904  and  906  can also have angular surfaces. Third tip  606  and fourth tip  608  may have a leading contact surface  708  and  710 , respectively, which are angular to squeegee the ink and debris that has collected on nozzle plate  210 . Although the contour of the wiper tips  506 ,  508 ,  606 ,  608  and cheek wipers  804 ,  806 , can improve wiping performance in particular printer devices the specific contour arrangement is not critical and alternative embodiments are possible. 
   Turning to  FIG. 10A  is a cross-sectional view of a wiper apparatus  1002  used, for example, in cleaning a printhead  116  of inkjet printer  100  ( FIG. 1 ), in accordance with another embodiment of the present invention. Wiper apparatus  1002  includes a wiper base (not shown), and a first wiper  1004  that leads a second wiper  1006  during wiping in the direction of wipe  230 . The leading contact surface  1005  of the first wiper  1004  and the leading contact surface  1007  of the second wiper  1006  are misaligned with respect to one another. The leading contact surface  1005  lies along the first axis  1020  and the leading contact surface  1007  of the second wiper  1006  lies along the second axis  1022 , the first axis  1020  being distinct from the second axis  1022 . The first wiper  1004  and the second wiper  1006  are substantially parallel to one another, and the first wiper  1004  and the second wiper  1006  are substantially perpendicular to the direction of wipe  230 . However, it is not necessary that the first and second wipers  1004 ,  1006  be substantially parallel to one another or perpendicular to the direction of wipe as will be further described below. 
   Still referring to  FIG. 10A  nozzle plate  210  has a first nozzle array  220  to dispense a first ink  126  ( FIG. 1 ) and a second nozzle array  222  to dispense a second ink  127  ( FIG. 1 ), and wiper apparatus  1002  is oriented so that the first wiper  1004  contacts the first nozzle array  220  and the second wiper  1006  contacts the second nozzle array  222  during wiping. The first wiper  1004  does not extend a distance sufficient to contact the second nozzle array  222  during wiping and the second wiper  1006  does not contact the first nozzle array  220  during wiping. The plurality of nozzles  220  that lie along an axis that is perpendicular to the direction of wipe  230 , for example, first axis  1020 , are consecutively contacted by the first wiper  1004  and the second wiper  1006  during wiping. As the first wiper  1004  wipes the first nozzle array  220  along axis  1020 , the adjacent nozzles  212  of the second nozzle array  222  which lie along the same axis  1020  are not contacted by the first wiper  1004 , and as the second wiper  1006  wipes the second nozzle array  222  along axis  1022 , the adjacent nozzles  212  of the first nozzle array  220  along axis  1020  are not contacted by the second wiper  1006 . Thus, the discontinuity and misalignment between the leading contact surface  1005  of the first wiper  1004  and the leading contact surface  1007  of the second wiper  1006  can prevent mixing of the inks  126 ,  127  as the wipers  1004 ,  1006  contact the nozzle plate  210 . The first and second wipers  1004 ,  1006  can be spaced apart, and in alternative embodiments (not shown), they can be touching or overlapping. 
   In an alternative embodiment of the present invention, the first wiper  1004  and the second wiper  1006  can extend from separate wiper bases that move independently in the direction of wipe. For example, the leading contact surface  1005  of the first wiper  1004  and the second contact surface  1007  of the second wiper  1006  can be aligned along the same axis  1020  when the wiper apparatus  1002  is in the home position prior to wipe, and the leading contact surfaces  1005 ,  1007  can be moved independently to become misaligned during wiping. 
   In  FIG. 10A  the first wiper  1004  and the second wiper  1006  are sized so that the separation zone  221  of the nozzle plate  210  is contacted by the first wiper  1004  or the second wiper  1006 , or both, although it is not necessary that any portion of the separation zone  221  be contacted by the wipers  1004  and  1006 . In alternative embodiments the first wiper  1004  and the second wiper  1006  can be sized to be overlapping, so that at least a portion of the separation zone  221  is contacted by both the first wiper  1004  and the second wiper  1006 . 
   In another embodiment of the present invention, wiper apparatus  1002  includes a third wiper  1008  that follows the second wiper  2006  and a fourth wiper  1010  that follows the third wiper  2008  during wiping in the direction of wipe  230 . The third wiper  1008  does not contact the second nozzle array  222  during wiping and the fourth wiper  1010  does not contact the first nozzle array  220  during wiping. The leading contact surface  1009  of the third wiper  1008  which lies along the third axis  1024  and the leading contact surface  1011  of the fourth wiper  1010  which lies along the fourth axis  1026 , are misaligned with respect to one another. The first, second, third and fourth wipers  1004 ,  1006 ,  1008 ,  1010  are substantially parallel to one another and are substantially perpendicular to the direction of wipe  230 , however, as mentioned above, it is not necessary that the wipers be substantially parallel to one another or perpendicular to the direction of wipe  230 . 
   In some embodiments of the invention, wiper apparatus  1002  can include cheek wipers (not shown) which can follow any of the first, second, third and fourth wipers  1004 ,  1006 ,  1008 , and  1010  as described above with respect to wiper apparatus  802  of  FIG. 8 . 
   The wiper apparatus  1002  of  FIG. 10A  has four wipers arranged in two columns that wipe along the first nozzle array  220  and the second nozzle array  222 , although, in alternative embodiments, wiper apparatus  1002  can have additional wipers arranged to wipe two or more nozzles arrays. 
     FIG. 10B  is a cross-sectional view of wiper apparatus  1050  wiping a nozzle plate  1090  that has three nozzle arrays  1094 ,  1096 ,  1098 , according to another embodiment of the invention. For example, printhead  116  ( FIG. 1 ) can contain three or more inks which can be distinct from one another. In one embodiment, the wiper apparatus  1050  includes first wiper  1056  that wipes the first nozzle array  1094 , a second wiper  1064  that wipes the second nozzle array  1096 , and a third wiper  1060  that wipes the third nozzle array  1098 , during wiping. First and second wipers,  1056 ,  1064  which wipe adjacent nozzle arrays,  1094 ,  1096  are misaligned. Likewise, second and third wipers,  1064 ,  1060  which wipe adjacent nozzle arrays  1096 ,  1098  are misaligned. Specifically, the leading contact surface  1057  of the first wiper  1056  that lies along axis  1058  and the leading contact surface  1065  of second wiper  1064  that lies along axis  1066  are misaligned. In this arrangement, the nozzles  212  that lie along axis  1058  of the first nozzle array  1094  and the second nozzle array  1096 , are wiped consecutively. Likewise, the nozzles  212  that lie along axis  1062  of the third nozzle array  1098  and along axis  1066  of the second nozzle array  1096 , are wiped consecutively. The alignment of the leading contact surface  1057  of the first wiper  1056  along the first axis  1058  can be the same or different than the leading contact surface  1061  of third wiper  1060  along the third axis  1062  during wiping. 
   In another embodiment of the invention, wiper apparatus  1050  can also include a forth wiper  1068  that wipes the second nozzle array  1096 , a fifth wiper  1072  that wipes the first nozzle array  1094 , and a sixth wiper  1076  that wipes the third nozzle array  1098 . As would be known by one skilled in the art, many alternative embodiments of wiper apparatus are possible. The wiper apparatus can have additional wipers to wipe additional nozzle arrays for dispensing several different inks. As described in the examples above, the leading contact surfaces of the wipers that are directly adjacent to one another are misaligned so that adjacent nozzle arrays are wiped consecutively rather than simultaneously. 
   Wiper apparatus  1102  of  FIG. 11 , in accordance with another embodiment, includes a first wiper  1120  that has a first tip  1110  and a second tip  1112  which are oriented at an angle relative to each other and relative to the direction of wipe  230 . The first tip  1110  is oriented along first axis  1111  at an angle β 1  relative to the direction of wipe  230  and the second tip  1112  is oriented along a second axis  1113  at an angle β 2  relative to the direction of wipe  230 . Angles β 1  and β 2  are greater than about 90 degrees to direct ink residue and debris associated with the first and second array of nozzles  220 ,  222 , in divergent directions to reduce the incidence of ink mixing. Angles β 1 , and β 2  can range from greater than about 90 degrees to about 180 degrees, and in some embodiments, β 1  and β 2  can range from about 120 degrees to about 150 degrees. 
   Wiper apparatus  1102  can also include a second wiper  1130  having a third tip  1114  and a fourth tip  1116  so that the third tip  1114  contacts the first nozzle array  220  and the fourth tip  1116  contacts the second nozzle array  222  and the third tip  1114  follows the second tip  1112  and leads the fourth tip  1116  during wiping in the direction of wipe  230 . In  FIG. 11 , the third tip  1114  and the fourth tip  1116  of second wiper  1130  are oriented at an angle relative to each other and relative to the direction of wipe  230 . The third tip  1114  is oriented along third axis  1115  at an angle β 3  relative to the direction of wipe  230  and the fourth tip  1116  is oriented along a fourth axis  1117  at an angle β 4  relative to the direction of wipe  230 . Angles β 3  and β 4  can range from greater than about 90 degrees to about 180 degrees, and in some embodiments, β 3  and β 4  can range from about 120 degrees to about 150 degrees. In the various embodiments relating to a wiper apparatus having angled wiper tips that are staggered, ink mixing can be prevented where two distinct inks are fired through the same orifice plate. 
     FIG. 12  is a perspective view of a wiper apparatus  1202  that can be used in inkjet printer  100  ( FIG. 1 ) according to another embodiment of the present invention. Wiper apparatus  1202  has a wiper head  1212  and stem  1214  mounted on wiper base  1216  can be moved in directions  230  and  260  for bidirectional wiping. The wiper head  1212  has a first pair of tips  1204  and a second pair of tips  1206  which lie in two distinct planes. The first pair of tips  1204  includes first tip  1222  and second tip  1224  which are oriented at a first angle φ 1  with respect to each other, and the second pair of tips  1206  includes third tip  1226  and fourth tip  1228  which are oriented at a second angle φ 2  with respect to each another. The angled orientation, for example, the “v-shaped” orientation of the first tip and the second tip direct ink residue and debris from the first and second array of nozzles  220 ,  222 , in divergent directions during wiping in direction  230 , to reduce the incidence of ink mixing. The angled orientation, for example, the “v-shaped” orientation of the third tip and the fourth tip direct ink residue and debris from the first and second array of nozzles  220 ,  222 , in divergent directions during wiping in direction  260 , to reduce the incidence of ink mixing. The cross-section of the wiper head through all four tips, is a tetragon. In the wiper head  1212  of  FIG. 12 , the first pair of tips contact the second pair of tips since the angle φ 1  between the first tip and the second tip is equal to the angle φ 2  between the third tip and the fourth tip. However, it is not necessary the angle which separates the first and second tips be equal to the angle which separates the third and fourth tips. 
   The wiper apparatus  1202  can include a cavity  1220  between the first pair of tips  1204  and the second pair of tips  1206 , however, the presence of a cavity  1220  is not necessary. The cavity  1220  can serve as a reservoir to collect ink and debris that is wiped from the printhead  116 , and cavity  1220  can also connect with an opening  1236  in the wiper base  1216  for drainage of the ink and debris below or beyond the wiper apparatus  1202 . In another embodiment, wiper head  1212  can include openings  1232  and  1234  to allow the ink and debris that collects in cavity  1220  to exit the wiper head  1212 . 
   In  FIG. 13 , is a side elevation view of wiper apparatus  1202  as it moves in direction  230 , away from the home position ( FIG. 1 ) and comes into contact with the printhead  116 . The dimensional interference between wiper apparatus  1202  and the printhead  116  causes the wiper stem  1214  to bend into the printhead  116  such that the first pair of tips  1204  mates with nozzle plate  210  for wiping. The first pair of tips  1204  and the second pair of tips  1206  of wiper head  1212  are separated by an angle δ. Therefore, when the first pair of tips  1204  is in contact with nozzle plate  210 , the second pair of tips  1206  is angled away and below the plane of printhead  210 . The angle δ between the first pair of tips  1204  and the second pair of tips  1206  is greater than about 180 degrees. 
   Stem  1214  can be designed to improve the ease and reliability of which the wiper head  1212  contacts the printhead  116 . For example, stem  1214  has a smaller cross-section than the wiper head  1212  for improved flexibility. The size and geometry of stem  1214 , and the material which makes up the stem  1214 , as well as other factors, can have bearing on the ability of the wiper head  1212  to make contact with the nozzle plate  210 . 
   Once the wiper apparatus  1202  clears the printhead  116 , the wiper apparatus can be moved in a second direction  260 , opposite direction  230  as illustrated in the side elevation view of  FIG. 14 . As the wiper head  1212  comes into contact with the printhead  116  while moving in second direction  260 , the stem  1214  bends so that the second pair of wiper tips  1206  mates with the nozzle plate  210  while the first pair of wiper tips  1204  is angled away from the printhead  116  and is not engaged in wiping. 
     FIG. 15  is a cross-sectional view taken along lines  15 — 15  of  FIG. 14 . The cross-section of the wiper apparatus along a plane near the surface of the nozzle plate  210  of printhead  116  shows the first tip  1226  and the second tip  1228  of the wiper apparatus  1202  engage the printhead  116  a “v-shaped” orientation. 
   In any of the above embodiments of the present invention, the wipers can be made of a resilient material which can include but is not limited to, elastomer, plastic, rubber, for example, EPDM rubber, silicone rubber, or any comparable material know in the art. In alternative embodiments, the stem  1214  can be substantially rigid and swiveled, at the base  1216 , for example, in at least two directions as the wiper apparatus  1202  moves in the first direction of wipe  230  and the second direction of wipe  260 . 
   It should be understood that the foregoing description is only illustrative of the invention. Various alternative and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.