Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application claims the benefit of provisional patent application Ser. No. 61/031,972, filed Feb. 27, 2008 titled “PRINTHEAD SERVICING SYSTEM AND METHOD” which application is incorporated by reference herein as if reproduced in full below. 
    
    
     BACKGROUND 
     An inkjet printing system may include a printhead and an ink supply which supplies liquid ink to the printhead. The printhead ejects drops of the ink through a plurality of nozzles or orifices and toward a print medium, such as a sheet of paper, so as to print onto the print medium. Typically, the orifices are arranged in one or more arrays such that properly sequenced ejection of ink from the orifices causes characters or other images to be printed upon the print medium as the printhead and the print medium are moved relative to each other. 
     During use and/or non-use of the printhead, it is possible for the orifices to become clogged with ink and/or for bubbles of air to be trapped within the printhead in such a manner as to interfere with proper operation of the printhead. In addition, it is desirable to prevent ink from drying in the orifices when the printhead is not in use, and to clear out soft viscous plugs of ink which may form in the orifices when the printhead is not in use. 
     For these and other reasons, a need exists for the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating one embodiment of an inkjet printing system according to an embodiment of the present invention. 
         FIG. 2  is a schematic cross-sectional view illustrating one embodiment of a portion of an inkjet printing system according to an embodiment of the present invention. 
         FIG. 3  is a schematic bottom perspective view illustrating one embodiment of a portion of an inkjet printing system according to an embodiment of the present invention. 
         FIG. 4  is a top perspective view illustrating one embodiment of a porous material of a servicing system for an inkjet printing system according to an embodiment of the present invention. 
         FIG. 5  is a bottom perspective view illustrating one embodiment of a porous material of a servicing system for an inkjet printing system according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
       FIG. 1  illustrates one embodiment of an inkjet printing system  10  according to embodiments of the present invention. Inkjet printing system  10  includes an inkjet printhead assembly  12 , an ink supply assembly  14 , a carriage assembly  16 , a print media transport assembly  18 , a service station assembly  20 , and an electronic controller  22 . 
     Inkjet printhead assembly  12  includes one or more printheads which eject drops of ink through a plurality of nozzles or orifices  13  and toward an embodiment of media, such as print medium  19 , so as to print onto print medium  19 . Print medium  19  is any type of suitable sheet material, such as paper, card stock, transparencies, Mylar, cloth, and the like. Typically, orifices  13  are arranged in one or more columns or arrays such that properly sequenced ejection of ink from orifices  13  causes characters, symbols, and/or other graphics or images to be printed upon print medium  19  as inkjet printhead assembly  12  and print medium  19  are moved relative to each other. 
     Ink supply assembly  14  supplies ink to inkjet printhead assembly  12  and includes a reservoir  15  for storing ink. As such, ink flows from reservoir  15  to inkjet printhead assembly  12 . In one embodiment, inkjet printhead assembly  12  and ink supply assembly  14  are housed together in an inkjet cartridge or pen. In another embodiment, ink supply assembly  14  is separate from inkjet printhead assembly  12  and supplies ink to inkjet printhead assembly  12  through an interface connection, such as a supply tube. In either embodiment, reservoir  15  of ink supply assembly  14  may be removed, replaced, and/or refilled. 
     Carriage assembly  16  positions inkjet printhead assembly  12  relative to print media transport assembly  18  and print media transport assembly  18  positions print medium  19  relative to inkjet printhead assembly  12 . Thus, a print zone  17  is defined adjacent to orifices  13  in an area between inkjet printhead assembly  12  and print medium  19 . 
     In one embodiment, inkjet printhead assembly  12  is a scanning type printhead assembly such that carriage assembly  16  moves inkjet printhead assembly  12  relative to print media transport assembly  18  and print medium  19  during printing on print medium  19 . In another embodiment, inkjet printhead assembly  12  is a non-scanning type printhead assembly such that carriage assembly  16  fixes inkjet printhead assembly  12  at a prescribed position relative to print media transport assembly  18  during printing on print medium  19  as print media transport assembly  18  advances print medium  19  past the prescribed position. 
     To maintain a functionality of inkjet printhead assembly  12  and, more specifically, orifices  13  of inkjet printhead assembly  12 , service station assembly  20  provides for spitting, wiping, capping, and/or priming of inkjet print assembly  12 . In one embodiment, service station assembly  20  includes a rubber blade or wiper which is periodically passed over inkjet printhead assembly  12  to wipe and clean orifices  13  of excess ink. In one embodiment, service station assembly  20  includes a cap which covers inkjet printhead assembly  12  to protect orifices  13  from drying out during periods of non-use. In one embodiment, service station assembly  20  includes a spittoon into which inkjet printhead assembly  12  ejects ink to insure that reservoir  15  maintains an appropriate level of pressure and fluidity and that orifices  13  do not clog or weep. 
     Electronic controller  22  communicates with inkjet printhead assembly  12 , carriage assembly  16 , print media transport assembly  18 , and service station assembly  20 . Electronic controller  22  receives data  23  from a host system, such as a computer, and includes memory for temporarily storing data  23 . Typically, data  23  is sent to inkjet printing system  10  along an electronic, infrared, optical or other information transfer path. Data  23  represents, for example, a document and/or file to be printed. As such, data  23  forms a print job for inkjet printing system  10  and includes one or more print job commands and/or command parameters. 
     In one embodiment, electronic controller  22  provides control of inkjet printhead assembly  12  including timing control for ejection of ink drops from orifices  13 . As such, electronic controller  22  defines a pattern of ejected ink drops which form characters, symbols, and/or other graphics or images on print medium  19 . Timing control and, therefore, the pattern of ejected ink drops, is determined by the print job commands and/or command parameters. 
       FIGS. 2 and 3  illustrate a portion of an inkjet printhead assembly  120 , as one embodiment of inkjet printhead assembly  12 , and a portion of a service station assembly  220 , as one embodiment of service station assembly  20 . In one embodiment, inkjet printhead assembly  120  is an inkjet print cartridge or pen, and includes a printhead  130  and one or more reservoirs or compartments  140  for storing and supplying ink (or fluid) to printhead  130 . In one embodiment, compartments  140  include a first ink compartment  141  for storing and supplying a first color ink to printhead  130 , and a second ink compartment  142  for storing and supplying a second color ink to printhead  130 . In one exemplary embodiment, ink compartment  141  stores and supplies black ink to printhead  130 , and ink compartment  142  stores and supplies a color ink other than black ink, for example, yellow ink, to printhead  130 . 
     In one embodiment, printhead  130  has a face  132  and includes a plurality of nozzles or orifices  134  formed in face  132 . In one embodiment, nozzles or orifices  134  are arranged in one or more columns  150  of orifices  134 . In one exemplary embodiment, printhead  130  includes a first column  151  of orifices  134 , and a second column  152  of orifices  134 . In one embodiment, first column  151  of orifices  134  communicates with first ink compartment  141  so as to eject a first color ink from printhead  130 , and second column  152  of orifices  134  communicates with second ink compartment  142  so as to eject a second color ink from printhead  130 . 
     In one embodiment, service station assembly  220  provides a system for capping and priming of printhead  130 . As such, service station assembly  220  helps to prevent ink from drying in nozzles or orifices  134  when printhead  130  is not in use, and assists in removing air bubbles trapped in nozzles or orifices  134  and clearing out soft viscous plugs of ink which may form in nozzles or orifices  134  when printhead  130  is not in use. 
     In one embodiment, service station assembly  220  includes a cap  230 , a porous material  240 , and a vacuum  250 . In one embodiment, cap  230  includes a base  232  and a perimeter wall  234  extending from base  232 . In one embodiment, cap  230  mates with printhead  130  such that perimeter wall  234  surrounds printhead  130  and forms a seal with face  132  of printhead  130 . 
     In one embodiment, base  232  of cap  230  includes a vacuum port  236 . In one embodiment, vacuum port  236  communicates with vacuum  250  via a vacuum tube  252 . In one embodiment, one end of vacuum tube  252  is communicated with vacuum port  236  and an opposite end of vacuum tube  252  is communicated with vacuum  250  such that vacuum pressure generated by vacuum  250  is communicated with cap  230 . As such, vacuum pressure of vacuum  250  is applied to printhead  130  through vacuum tube  252  and cap  230  when printhead  130  mates with cap  230 . In one embodiment, as described below, vacuum pressure within cap  230  draws ink (or fluid) from printhead  130  for servicing of printhead  130  when printhead  130  mates with cap  230 . 
     In one embodiment, as illustrated in  FIG. 2 , porous material  240  is provided in cap  230 . In one embodiment, porous material  240 , absorbs ink (or fluid) from printhead  130  and forms a filter for ink (or fluid) from printhead  130 . In one embodiment, porous material  240  is formed of an open-cell plastic. In one exemplary embodiment, porous material  240  has a pore volume of approximately 25 percent. In one exemplary embodiment, porous material  240  is a polyethylene foam or other functionally similar material. 
     As illustrated in the embodiment of  FIG. 2 , porous material  240  has a first side  241  and a second side  242 . Second side  242  of porous material  240  is opposite first side  241  and, in one embodiment, oriented substantially parallel with first side  241 . In one embodiment, porous material  240  is positioned in base  232  of cap  230  such that second side  242  of porous material  240  faces and/or contacts base  232 . As such, first side  241  of porous material  240  faces or is oriented toward face  132  of printhead  130  when printhead  130  mates with cap  230 . 
     In one embodiment, as illustrated in  FIGS. 2 ,  3 ,  4 , and  5 , first side  241  of porous material  240  has a stepped or raised profile, and second side  242  of porous material  240  includes a recessed area. The stepped or raised profile of first side  241  of porous material  240  reduces a distance between porous material  240  and face  132  of printhead  130  when printhead  130  mates with cap  230 , and the recessed area of second side  242  of porous material  240  provides an area or areas of reduced thickness of porous material  240 . By providing an area or areas of reduced thickness of porous material  240 , the recessed area of second side  242  provides an area or areas of reduced resistance and, therefore, increased pressure from vacuum  250 . As such, the recessed area of second side  242  provides a distributed pressure profile which varies throughout porous material  240  and, therefore, cap  230 . 
     In one embodiment, the recessed area of second side  242  of porous material  240  is formed by a recess  244  in porous material  240 . In one embodiment, recess  244  communicates with vacuum port  236  of cap  230  when porous material  240  is positioned in base  232  of cap  230 . By forming recess  244  in porous material  240 , recess  244  provides an area or areas of reduced thickness of porous material  240  and, therefore, reduced resistance to vacuum pressure generated by vacuum  250 . Thus, recess  244  provides an area or areas for increased application of pressure to porous material  240  and, therefore, cap  230  from vacuum  250 . Accordingly, the area or areas of increased application of pressure to porous material  240  may be applied to printhead  130  when printhead  130  mates with cap  230 . 
     In one embodiment, recess  244  is a T-shaped recess  260 . As such, T-shaped recess  260  includes a base portion  261  and a cross portion  262  oriented substantially perpendicularly to base portion  261 . In one embodiment, T-shaped recess  260  has a substantially uniform depth, and extends less than a full length of porous material  240 . In one embodiment, T-shaped recess  260  is oriented such that base portion  261  is oriented substantially parallel with columns  150  of orifices  134 , and cross portion  262  is oriented substantially perpendicular to columns  150  of orifices  134 . 
     In one embodiment, as illustrated in  FIGS. 2 and 3 , ink compartment  141  storing and supplying black ink to printhead  130  communicates with a first end of printhead  130 , and ink compartment  142  storing and supplying color ink other than black ink to printhead  130  communicates with a second end of printhead  130  opposite the first end. In one embodiment, flow of ink from ink compartment  141  to printhead  130  is illustrated by line  143 . 
     In one exemplary embodiment, ink within ink compartment  141  is a black pigment-based ink, and ink within ink compartment  142  is a yellow dye-based ink. Under certain conditions, pigment of the ink within ink compartment  141  may settle within ink compartment  141  (as illustrated by  144  in  FIG. 2 ) thereby producing a higher pigment concentration ink at the first end of printhead  130  (as illustrated by  145  in  FIG. 2 ). As such, the higher pigment concentration ink, when mixed with the dye-based ink from ink compartment  142 , may from sludge at the first end of printhead  130  (as illustrated by  135  in  FIG. 3 ) and within cap  230  adjacent the first end of printhead  130 . 
     In one embodiment, as illustrated in  FIG. 3 , cross portion  262  of T-shaped recess  260  is provided at an end of porous material  240  adjacent or corresponding to the first end of printhead  130 . As such, T-shaped recess  260  provides an area of reduced resistance and increased application of pressure from vacuum  250  at the first end of printhead  130 . Accordingly, T-shaped recess  260  provides for increased application of pressure to the first end of printhead  130  and, therefore, ink compartment  141  when printhead  130  mates with cap  230 . Thus, T-shaped recess  260  improves flow of the more viscous sludge and higher pigment concentration ink which may be develop at the first end of printhead  130 . 
     By providing recess  244  in porous material  240  of the shape and configuration illustrated and described herein, recess  244  helps to improve and regulate ink (or fluid) flow from printhead  130  while priming, and aids in balancing and distributing pressure within cap  230  and porous material  240  while priming. As such, recess  244  helps to achieve a predetermined flow pressure within cap  230  and porous material  240  to help reduce sludge formation on printhead  130  and within cap  230 . 
     Although illustrated and described as being a T-shaped recess, it is within the scope of the present invention for recess  244  in porous material  240  to be of other shapes and/or configurations. 
     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.

Technology Category: b