Abstract:
A method for cleaning a wiper in which a printhead cartridge having an integral wiper cleaning station is moved in opposite directions along a path of travel, whereby a stationary wiper is scraped across wiping surfaces of the cleaning station. The wiper does not contact the printhead cartridge when the wiper is positioned over parts of the cleaning station sandwiching a printhead on the printhead cartridge so that the wiper is out of contact with the cleaning station when printhead cartridge reverses direction.

Description:
RELATED APPLICATIONS 
     This application is related to patent application Ser. No. 09/472,716 by Fredrick Andrew Wolf et al., entitled “Wiper Debris Collector and Method of Using Same,” filed Dec. 23, 1999, and patent application Ser. No. 09/471,436 by Yinan Xu et al., entitled “Transaction Printing Device and Method of Using Same.” filed Dec. 23, 1999. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an inkjet printing system and method of maintenance. More particularly, the present invention relates to an inkjet printhead apparatus having a disposable integrated printhead and wiper cleaning station and method of wiping the printhead with a clean wiper for reliable printing operations. 
     BACKGROUND 
     A typical inkjet printing device generally include a traveling carriage unit for supporting one or more printheads in a desired orientation relative to a ink receiving surface. In this regard, as the carriage unit travels along a rectilinear path of travel adjacent to the ink-receiving surface, the printheads eject ink onto the ink-receiving surface to form desired indicia. 
     Such printheads typically have an orifice plate with a plurality of small nozzles for ejecting the ink toward the ink-receiving surface. Because of residue build up on and around these small nozzles or opening, many inkjet printing devices include a service station module that caps, wipes and catches spit ink droplets that facilitates keeping the printhead clean. A necessary operation in servicing such a printhead is to make certain that the wiper utilized to remove such residue is also cleaned periodically. 
     A prior solution for cleaning such a wiper included providing a wiper cleaning station within the service station module. In this regard, not only is a wiper cleaning station required but also special wiper cleaning fluids are necessary to clean the wiper. Thus, while such wiper cleaning stations are satisfactory for their intended purpose, the wiper cleaning station parts are nevertheless expected to last for the life of the printing device and add to the cost of operating the printer because of the special cleaning fluids that must be provided. 
     Therefore it would be highly desirable to have a new and improved inkjet printing device that does not require a wiper cleaning station that is expected to last the life of the printing device nor that requires any special cleaning fluids. 
     SUMMARY OF THE INVENTION 
     The present invention provides a disposable printhead cartridge including a cartridge body having a generally box-like shape with an integrally formed cleaning station that includes a raised front face portion. 
     The front face portion provides at least a pair of printhead wiper surfaces for engaging a wiper. A printhead and a pair of debris accumulating channels are sandwiched between the pair of printhead wiper surfaces such that the wiper engages the printhead to remove printhead debris that is deposited in the debris accumulating channels. When the printhead cartridge is exhausted of a supply of ink the cartridge and its integrally formed cleaning station is replaced with a new cartridge. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The above mentioned features of this invention and the manner of attaining them will become apparent, and the invention itself will be best understood by reference to the following description of the embodiment of the invention in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of an inkjet printing device which uses an exemplary disposable inkjet print cartridge with an integrated printhead and printhead wiper cleaning station which is constructed in accordance with the present invention; 
     FIG. 2 is an exemplary disposable print cartridge having an integrated inkjet printhead and printhead wiper station which may be used in the printing device of FIG. 1; 
     FIG. 3 is another exemplary disposable print cartridge having an integrated inkjet printhead and printhead wiper station which may be used in the printing device of FIG. 1; 
     FIG. 4 is a front face plan-view of the print cartridge of FIG. 2; 
     FIG. 5 is an enlarged diagrammatic fragmentary cross sectional view taken at the line  5 — 5  of FIG. 4; 
     FIG. 6 is an enlarged diagrammatic fragmentary cross sectional view taken at the line  6 — 6  of FIG. 4; 
     FIG. 7 is a greatly enlarge front face plan view of a printhead of the print cartridge of FIG. 2; 
     FIG. 8 is a greatly enlarged front face plan view similar to FIG. 7 of the printhead with portions removed for clarity of illustration; 
     FIG. 9 is a diagrammatic fragmentary cross sectional view taken at the line  5 — 5  of FIG. 8, and is shown greatly enlarged in comparison to the illustration of FIG. 8; and 
     FIG. 10 is a diagrammatic cross sectional view of a portion of the printhead, and during a stage of the manufacturing process, and is similar to the portion seen in FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings and more particularly to FIG. 1 thereof there is illustrated an inkjet printing device, such as a transaction printer  10  that is constructed in accordance to the present invention. The transaction printer  10  is utilized for printing receipts and the like in typical commercial transactions. In this regard, the transaction printer  10  is constructed for ease of use in a highly reliable manner requiring operator intervention only for the purpose of changing the consumables utilized in printing transaction receipts, such as a transaction receipt  12  illustrated in FIG.  1 . 
     Considering now the transaction printer  10  in greater detail with reference to FIG. 1, the printer  10  generally includes a base  14  for supporting therein a paper delivery system  18  and an ink delivery system  20 . The paper delivery system  18  moves a continuous roll of paper  22  through a print zone  24 , where ink is ejected onto the paper  22  from one or more disposable low profile inkjet printhead cartridges, such as a printhead cartridge  26  that forms part of the ink delivery system  20 . 
     As best seen in FIG. 1, the ink delivery system  20  includes a print engine  28  for controlling the movement of a carriage cartridge stall  30  that travels along a slide bar  32  in a rectilinear path of travel adjacent to the print zone  24 . The print engine  28  also controls the ejecting of ink from the cartridge  26  to facilitate the forming of transaction receipts. As the manner of controlling the movement of the carriage cartridge stall  30  and the manner of ejecting of ink from the cartridge  26  are well known to those skilled in the art of inkjet printing, the details of the print engine  28  will not be described hereinafter in greater detail. In a like manner, the paper delivery system  18  for moving the continuous roll of paper  22  through the print zone  24  is also well known to those skilled in the art of impact printers and thus, the paper delivery system  18  will not be described in greater detail. It should be noted that the cartridge stall  30  may accommodate either a single cartridge  26  for black ink printing or a pair of cartridges  26  for black and selected color printing. 
     Considering now the inkjet printhead cartridge  26  in greater detail with reference to FIG. 2, the inkjet printhead cartridge  26  generally includes a cartridge body  34  having a substantially hollow structure for holding a supply of ink. In this regard, supply of ink provided in the cartridge  26  is a fast drying pigment ink that is provided in either black or a user selected color, such as magenta, cyan or yellow for example. 
     As best seen in FIG. 2, the cartridge body  34  has a general box like structure that includes a rear wall  37 , a top wall  39 , a bottom wall  41 , a pair of side walls  43  and  44  respectively and a front wall  46 . Integrally formed to the front wall  46  and projecting outwardly therefrom is a front face portion  36  having a sloping top wall  71  terminating at a lower lip  65 . A lower portion of the front face portion  36  helps define an inkjet printhead wiper cleaning station  45  as will be described hereinafter in greater detail. An inkjet printhead  47  is mounted within a recessed channel area  42  on the front face portion  36  and is sandwiched between the wiper cleaning station  45 . 
     In order to help improve the reliable operation of the printhead  47 , the printing device  10  also includes a wiper assembly  38  and wiper  40 . The wiper assembly  38  is mounted to the paper delivery system  18  in such a manner to provide interference between the wiper  40  and the printhead cartridge  26 . In this regard the interference is also provided with the printhead  47  in order to remove any residue build up on and around a set of fine-dimensioned orifices  58  (FIG. 7) forming thereon. In this regard, the interference of the wiper  40  with the printhead  47  is set to about between 0.25 millimeters to about 0.75 millimeters. A more preferred setting is between about 0.35 millimeters to about 0.60 millimeters, while the most preferred setting is set to about 0.50 millimeters. The wiper cleaning station  45  defined by the front face portion  36  of the printhead cartridge  26  makes certain that the wiper  40  is cleaned of accumulated debris each time the wiper  40  and the printhead  47  move relative to one another. 
     The ink delivery system  20  further includes a sponge  48  that is carried within a chamber  50  defined by the hollow space within the interior of the cartridge body  34 . The sponge  48  is for holding the supply of ink within the interior of the cartridge body  34 . A standpipe (not shown) conveys the printing fluid from the chamber  50  to the printhead  47 . 
     Considering now the printhead  47  in greater detail with reference to FIG. 7, the printhead  47  generally includes a printed circuit  53  which electrically couples the printhead  47  via a set of circuit traces  54  and electrical contacts  56  with the print engine  28 . That is, the electrical contacts  56  individually make electrical contact with matching contacts on a flex circuit (not shown) to the carriage stall  30 , and provide for the electrical interface of the printhead  47  with the print engine  28 . Individual fine-dimension orifices, such as the orifices  58  of the printhead  47  eject fluid when appropriate control signals are applied to the contacts  56  by the print engine  28 . The fine-dimensioned orifices  58  are formed in a metallic plate member  62  that is adhesively attached to the floor of the recess area  42  of the underlying front face portion  36  of the printhead cartridge  26 . 
     In order to provide a fluid communication path between the chamber  50  and a fluid receiving cavity  64  formed in the front face portion  36  of the cartridge body  34 , a through hole  66  is formed between front face portion  36  and a portion of the plate member  62 . 
     Considering now the printhead cartridge  26  in greater detail, the printhead cartridge  26  generally includes an integrally form outwardly projecting tab  35  for facilitating the installation and removal of the printhead cartridge  26  from the carriage stall  30 . The tab  35  is disposed on the rear wall  37  of the cartridge body  34  adjacent to the top  39  of the cartridge body  34 . 
     A top bull feed lip  52  is integrally formed in the top wall  39  extends across substantially the entire width dimension W of the cartridge body  34  adjacent to the rear wall  37 . A bottom bull feed lip  60  is disposed adjacent the bottom of the rear wall  37  on the bottom wall  41  of the cartridge body  34 . The bottom bull feed lip  60  is about one half the width dimension of the top bull feed lip  52 . In this regard, the top bull feed lip  52  and the bottom bull feed lip  60  cooperate with a bull feeder (not shown) to facilitate the proper orientation of the cartridge body  34  for manufacturing assembly purposes. 
     The cartridge body  34  has integrally formed thereon a right side datum member  93  and left side datum member  95 . The datum members  93  and  95  are integrally formed on respective ones of the sides  43  and  44 . In this regard, the respective datum members  93  and  95  extend across substantially the entire longitudinal dimension D of the walls  43  and  44  respectively. The datum members  93  and  95  are provided on the cartridge body  34  to further help facilitate the manufacturing of the printhead cartridge  26  by cooperating with the bull feeder to provide proper orientation of the cartridge body  34  for assembly purposes. 
     The datum members  93  and  95  also help in the proper installation of the printhead cartridge  26  in the carriage stall  30 . In this regard, as best seen in FIG. 2, the datum members  93  and  95  each extend outwardly from the front face portion  36  of the cartridge  26  to space the front face portion  36  from the cartridge stall  30  when the cartridge  26  is installed in the stall  30 . This spacing distance is selected to help provide a proper spacing between the orifices  58  and the paper  22  for printing purposes. 
     Considering now the front face portion  36  in greater detail with reference to FIGS. 4-6, the front face portion  36  includes a pair of spaced apart flex clip clearing slots  31  and  33  respectively. The slots  31  and  33  have a generally rectangular shaped and are disposed on opposite sides of the printhead  47  adjacent the glass substrate  73 . The flex clip clearing slots  31  and  33  permit the printhead cartridge  26  to rest in the carriage stall  30  without interfering with the flex cable clips (not shown) disposed therein. 
     As best seen in FIG. 4, the elongated recess area  42  has a sufficient depth and width for receiving therein the printhead  47 . In this regard, when the printhead  47  is mounted within the recess  42 , the printhead  47  cooperates with a right sidewall  69  and a left sidewall  70  of the recess  42  to form a pair of debris accumulation channels  73  and  74  respectively. The channels  73  and  74  extend into a pair of recessed debris catchers or accumulative areas  77  and  79  respectively each having a generally rectangular box like shape. The debris catchers  77  and  79  are closed on one end and open into respective channels  73  and  74  to permit debris flowing and falling down the channels under the force of gravity to accumulate within the catchers  77  and  79 . A pair of dams  67  and  68  block the respective channels  73  and  74  for helping to direct channel residual ink into the catchers  77  and  79 . 
     The front face portion  36  further includes a pair of spaced sidewall members  81  and  83  that extend perpendicularly outwardly from the front wall  46 . The side wall members terminate in a pair of lips  85  and  87  respectively that are disposed adjacent to the recess  42 . In this regard, the lips are disposed in a horizontal plane parallel to the printhead  47  but at a slightly higher elevation for facilitating the cleaning of the wiper  40  as it first engages a side wall member, such as the side wall member  81  and then a lip, such as the lip  87 . As best seen in FIG. 2, the respective ones of the lips  85  and  87  have a sufficient width to provide a cleaning surface for engaging the cleaning surfaces of the wiper  40 . 
     Considering now the operation of the wiper cleaning station  45  in greater detail with reference to FIGS. 1-2, as the printhead cartridge  26  and wiper  40  are moved relative to one another in a first direction, the printhead cartridge  26  will engage a first cleaning surface of the wiper  40  with side wall  81 . As relative movement continues in this same first direction, the first cleaning surface of the wiper  40  is scraped along a second cleaning surface provided by the lip surface  87 . This scraping action permits any debris on the first cleaning surface of the wiper  40  to fall and flow down the sidewall  81  onto a lower right side plateau or wiper debris accumulation area  98 . From the lip surface  87 , the wiper  40  snaps into the channel  73  permitting any remaining wiper debris to fall freely down the channel  73  and into the debris accumulating catcher  77 . 
     Next, the wiper  40  travels across the orifices  58  of the printhead  47  to clean the orifices  58  with the cleaned wiping surface of the wiper  40 . After cleaning the orifices  58 , the wiper  40  snaps off of the printhead  47  entering the opposite channel  74  permitting any debris removed from the printhead  47  to fall freely down the channel  74  to be accumulated in the channel  74  and the debris accumulating catcher  79 . As relative movement continues in the first direction, the first cleaning surface of the wiper engages the wall  70  and then the lip surface  85 . This engagement and scraping action further cleans the first cleaning surface of the wiper allowing the debris to fall down the wall  70 , and the channel  74  for accumulation in the debris accumulating catcher  79 . After passing over the lip surface  85 , the wiper  40  snaps into the space opposite side wall  83  allowing any remaining debris to fall under the force of gravity onto the outside lower left plateau or wiper debris accumulation area  99 . 
     Considering further the operation of the cleaning station  45  with reference to FIGS. 1-2, as the printhead cartridge  26  and wiper  40  are moved relative to one another in a second or opposite direction than the first direction, the printhead cartridge  26  will engage a second cleaning surface of the wiper  40  with side wall  83 . As relative movement continues in this same second direction, the second cleaning surface of the wiper  40  is scraped along a second cleaning surface provided by the lip surface  87 . This scraping action permits any debris on the second cleaning surface of the wiper  40  to fall and flow down the sidewall  83  onto the lower plateau  99 . From the lip surface  87 , the wiper  40  snaps into the channel  74  permitting any remaining wiper debris to fall freely down the channel  74  and into the debris accumulating catcher  79 . 
     Next, the wiper  40  travels across the orifices  58  of the printhead  47  to clean the orifices  58  with the cleaned second wiping surface of the wiper  40 . After cleaning the orifices  58 , the wiper  40  snaps off of the printhead  47  entering the opposite channel  73  permitting any debris removed from the printhead  47  to fall freely down the channel  73  to be accumulated in the channel  73  and the debris accumulating catcher  77 . As relative movement continues in the first direction, the first cleaning surface of the wiper engages the wall  69  and then the lip surface  87 . This engagement and scraping action further cleans the second cleaning surface of the wiper  40  allowing the debris to fall down the wall  69 , and the channel  73  for accumulation in the debris accumulating catcher  77 . After passing over the lip surface  87 , the wiper  40  snaps into the space opposite side wall  81  allowing any remaining debris to fall under the force of gravity onto the outside plateau  98 . 
     The above described cleaning action of the first cleaning surface of the wiper  40  and the second cleaning surface of the wiper  40  is repeated until the ink supply of the printhead cartridge  26  is spent. At this time the printhead cartridge  26  is replaced resulting in a new wiper station being provided. It should also be appreciated by those skilled in the art that the cutout areas indicated generally at  55  and  57  on either side of the raised front face portion above plateaus  98  and  99  respectively allows the wiper to disengage from the printhead, which in-turn allow the linear translation of the printhead cartridge to be reversed without creating any substantial wiper wear. The cutout areas  55  and  57  also allow a centrally disposed service station to be placed in the printing device  10  thereby greatly reducing the overall width of the printing device  10 . 
     Considering now the manufacture of the fully integrated thermal (FIT) fluid jet architecture of the printhead  47  in greater detail with reference to FIGS. 7-10, the thermal inkjet printhead  47  includes a substrate  72  (FIGS.  9 - 10 ), which is most preferably formed as a plate of glass (i.e. an amorphous, generally non-conductive material). As seen in plan-view, the substrate  72  has a generally rectangular shape. Most preferably, the glass substrate is formed from an inexpensive type of soda/lime glass utilized in ordinary glass windows, which makes the printhead  47  very economical to manufacture. The printhead  47  is especially economical and inexpensive to manufacture when considered in comparison to printheads utilizing the conventional technologies that require a substrate of silicon or other crystalline semiconductor material. 
     On the glass substrate  72  is formed a thin-film structure  75  of plural layers. As will be further explained, during manufacturing of the printhead head  47 , the thin-film structure  75  is formed substantially of plural thin-film layers applied one after the other and atop of one another, and each of which entirely covers and is congruent with the plan-view shape of the substrate  72 . Again, this plan-view shape of the substrate  72  is seen in FIGS. 7 and 8. Once selected ones of these thin-film layers are formed on the substrate  72 , subsequent patterning and etching operations are used to define the contacts  56  and printed circuit  53 , for example, as is described hereinafter in greater detail. 
     The thin-film structure  75  includes a metallic heat sink and diffusion barrier thin-film layer  76  (FIGS. 5 and 6) which is applied upon the substrate  72 . The layer  76  covers the entire plan-view shape of the substrate  72 , and is preferably formed of chrome about 1 to 2 microns thick. Alternatively, the layer  76  may be formed of other metals and alloys. For example, the thin-film heat sink and diffusion barrier layer  76  may be formed of gold, palladium, or platinum, or of alloys of these or other metals. 
     Upon the metallic thin-film layer  76  is formed an insulator thin-film layer  78 . The insulator layer  78  is preferably formed of silicon oxide, and is about 1 to 2 microns thick. Again, this insulator layer  78  covers and is congruent with the entire plan-view shape of the substrate  72 . 
     Next, on the substrate  72  and on the insulator layer  76 , is formed a resistor thin-film layer  80 . The thin-film resistor layer  80  is preferably formed of tantalum, aluminum allow, and is preferably about 600 Angstroms thick. The resistor thin-film layer  80  is formed to cover and be congruent with the entire plan-view shape of the substrate  72 , but does not remain this extensive. That is, the resistor thin-film layer  80  is later patterned and etched back until it covers only an area congruent with the traces  54  of the printed circuit  53 , with each of the contacts  56 , and with each one of plural print resistor areas  82  (FIG. 9, and generally indicated with the arrowed number  82  on FIG.  8 ). 
     Over the unpatterned and unetched resistor layer  80  is next formed a metallic conductor thin-film layer  84 . The metallic conductor thin-film layer  84  is formed preferably of aluminum, and is about 0.5 microns thick. Again, this metallic conductor layer  84  is initially formed to cover and be congruent with the entire plan-view shape of the substrate  72 . However, the conductor layer  84  is also later patterned and etched back to cover only the area defining the traces  54  of the printed circuit  53 , and defining the contacts  56 . More particularly, the conductor layer  84  is first etched away at the location of the print resistors  82  so that a portion of the thin film resistor layer  60  spanning between traces  54  of the printed circuit  53  provides the only conduction path between these traces  54 . Later, the etching operation is carried further, removing both the conductive layer  64  and the underlying resistive layer  60  over the entire plan-view shape of the substrate  72 , except at the locations of the traces  54  and contact pads  56 . This etching operation leaves the traces  54  and the contact pads  56  standing in relief on the insulative layer  78 , as can be appreciated from viewing FIG.  9 . 
     Accordingly, an in view of the foregoing, it will be understood that during operation of the printhead  47  when a current is applied between two of the contacts  56  leading via traces  54  to opposite sides of one of the print resistors  62 , the current to and from the respective print resort  82  is carried in the traces of the printed circuit  53  by a combination of the conductor thin-film layer  84  and the underlying resistor thin-film layer  80 . Because the conductive layer  64  has a much lower resistance than the resistive layer  80 , most of this current will flow in the layer  84 . However, at the print resistor  82  itself, only the underlying resistor layer  80  is available to carry (the overlying conductive layer  64  having been locally etched away). The print resistors  82  are fine-dimension areas of the resistive layer  80 . Thus, the print resistors  82  can be caused to quickly dissipate energy, and to liberate heat. However, also as best seen in FIG. 7, and recalling that the metallic heat sink layer  76  cover substantially the entire plan-view shape of the substrate  72 , it will be understood that this heat sink layer  76  both underlies the resistors  82  to absorb heat from these resistors, and has a large area (i.e. essentially the entire plan-view area of the printhead  47 ) from which to dissipate excess heat. Thus, the printhead  47  during operation maintains a desirably low temperature, and can operate at firing repetition rates not hereto possible with conventional printheads using a glass substrate. 
     As FIG. 10 illustrates in fragmentary cross sectional view, a first manufacturing intermediate article  90  results from the above described manufacturing steps prior to the patterning and etching steps described above and prior to the formation of the through hole  66 . This first manufacturing intermediate article  90  includes the substrate  72 , and the thin-film layers  76 ,  78 ,  80 , and  84 , each of which substantially covers and is congruent with the entire plan-view shape of the substrate  72 . The first manufacturing intermediate article  90  is subjected to the patterning and etching processes described above to produce a second manufacturing intermediate article  92 , substantially as is seen in FIGS. 4 and 5. On the second manufacturing intermediate article  92  is formed a pair of passivating thin-film layers  86  (FIG. 9) and which is indicated on FIG. 6 in dash line. This passivating thin-film layer  86  includes a first sub-layer  88  of silicon nitride, followed by a second substrate layer  89  of silicon carbide. As seen in FIG. 9 fragmentarily, the completion of the printhead  47  requires only the adhesive attachment of the metallic plate member  44 , with the print orifices  58  in alignment with the print resistors  82 . 
     In view of the foregoing, those ordinarily skilled in the pertinent arts will understand that the thin-film structure  74  may be formed on the substrate  72  using a variety of techniques. In summary then, during one or more of the deposition processes, the work-piece that will become the first and second intermediate articles, and which will become the completed printhead  47 , may be subjected to radio frequency energy. Particularly during the formation of the passivating layers  88  and  89 , the second manufacturing intermediate article  92  is exposed to elevated temperatures and to radio frequency energy to assist in the deposition of the layers. During the exposure of the article  92  to radio frequency energy at elevated temperature, the metallic heat sink layer  76  serves as a diffusion barrier to prevent migration of sodium from the soda/lime glass substrate  72  into the other thin layer structures of the printhead  47 . Particularly, where the sodium is not prevented from migrating into the passivation layer  88 , the sodium could cause a lesion in the passivation layer at which this layer would not long withstand the cavitation occurring in the printing fluid each time a bubble collapse after an ink jet droplet ejection. However, because the heat sink layer  76  covers the entire plan-view shape of the printhead  47 , there is no place where sodium from the glass substrate  72  can migrate into the thin-film structures above the metallic heat sink layer  76 . Thus, contamination of the thin film structure  74  with sodium from the glass substrate  72  is prevented. 
     Referring now to FIG. 3, there is illustrated another printhead cartridge  126 , which is constructed in accordance with the present invention. The printhead cartridge  126  is substantially identical to printhead cartridge  26  except for the structure of the front face portion. In this regard, the printhead cartridge  126  includes a cartridge body  134  that is integrally connected to a raised front face portion  136 . The raised front face portion  136  is substantially identical to the front face portion  36  except for its sidewall-outside plateau interconnection. In this regard, the front face portion  136  includes a pair of sidewalls  181  and  183  respectively that extend upwardly from plateaus  198  and  199  respectively at an angle θ, where the angle θ is about 60 degrees. Each one of the sidewalls  181  and  183  terminate in a lip, such as a lip  185  and a lip  187  respectively. From the foregoing, it should be understood by those skilled in the art, that the wedge shaped sidewalls  181  and  183  commence engaging a tip portion of the wiper  40  first and then gradually engage the respective ones of the first cleaning surface and the second cleaning surface providing more of scraping action against such cleaning surfaces. 
     While particular embodiments of the present invention have been disclosed, it is to be understood that various different modifications are possible and are contemplated within the true spirit and scope of the appended claims. There is no intention, therefore, of limitations to the exact abstract or disclosure herein presented. In this regard, those skilled in the art will further appreciate that the present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof. Because the foregoing description of the present invention discloses only particularly a preferred exemplary embodiment of the invention, it is to be understood that other variations are recognized as being within the scope of the present invention. For example, although the glass substrate of the present invention was describes as having a rectangular shape in plan-view, it is contemplated that other plan-view shapes could be formed to carry out the invention as well. Accordingly, the present invention is not limited to the particular embodiment that has been described in detail herein. Rather, reference should be made to the appended claims to define the spirit and scope of the present invention.