Abstract:
A printing system includes a printhead, a movable transport surface opposite the printhead and configured to transport a print medium relative to the printhead, and a cleaning medium in contact with the transport surface while at least one of the cleaning medium and the transport surface are moved relative to one another.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS  
       [0001]    The present continuation application claims priority under 35 U.S.C. § 120 from co-pending U.S. patent application Ser. No. 09/584,019 filed on May 30, 2000 by Wesley B. Roche et al., and entitled “Cleaning Medium for Ink-Jet Hard Copy Apparatus”, the full disclosure of which is hereby incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates generally to ink-jet printing and, more specifically to a method and mechanism for cleaning a belt used in the transport of print media through a printing zone.  
           [0003]    The art of ink-jet technology is relatively well developed. Commercial products such as computer printers, graphics plotters, copiers, and facsimile machines employ ink-jet technology for producing hard copy. The basics of this technology are disclosed, for example, in various articles in the  Hewlett - Packard Journal , Vol. 36, No. 5 (May 1985), Vol. 39, No. 4 (August 1988), Vol.  39 , No. 5 (October 1988), Vol. 43, No. 4 (August 1992), Vol. 43, No. 6 (December 1992) and Vol. 45, No. 1 (February 1994) editions. Ink-jet devices are also described by W. J. Lloyd and H. T. Taub in  Output Hardcopy [sic] Devices , chapter 13 (Ed. R. C. Durbeck and S. Sherr, Academic Press, San Diego, 1988).  
           [0004]    [0004]FIG. 1 (Prior Art) is a schematic depiction of an ink-jet hard copy apparatus  10 . A writing instrument  12  is provided with a printhead  14  having drop generators including nozzles for ejecting ink droplets onto an adjacently positioned print medium, e.g., a sheet of paper  16 , in the apparatus&#39; printing zone  34 . An endless-loop belt  32  is one type of known manner printing zone input-output paper transport. A motor  33  having a drive shaft  30  is used to drive a gear train  35  coupled to a belt pulley  38  mounted on an fixed axle  39 . A biased idler wheel  40  provides appropriate tensioning of the belt  32 . The belt rides over a platen  36  in the print zone  34 ; the platen is described in detail hereinafter, but is associated with a known manner vacuum induction system  37 . The paper sheet  16  is picked from an input supply (not shown) and its leading edge  54  is delivered to a guide  50 ,  52  where a pinch wheel  42  in contact with the belt  32  takes over and acts to transport the paper sheet  16  through the printing zone  34  (the paper path is represented by arrow  31 ). Downstream of the printing zone  34 , an output roller  44  in contact with the belt  32  receives the leading edge  54  of the paper sheet  16  and continues the paper transport until the trailing edge  55  of the now printed page is released. The carriage scanning axis is conventionally designated the x-axis, the print media transit axis is designated the y-axis, and the printhead firing direction is designated the z-axis. For convenience in describing the art and the present invention, all types of ink-jet hard copy apparatus are sometimes hereinafter referred to as “printers;” all types, sizes, and compositions of print media—including non-traditional printing media such as polymeric transparencies, cloth fabric, mylar, and the like—are also referred to simply as “paper;” all compositions of colorants are sometimes referred to as “ink;” and all embodiments of an ink-jet writing instruments are simply referred to as a “pen;” no limitation on the scope of the invention is intended nor should any be implied.  
           [0005]    During printing operations, ink deposits or aerosol mixtures of ink and paper dust collect on the belt and platen. Once on the belt, ink begins transferring onto subsequent sheets as well as internal components of the print mechanism. This can cause print defects and unattractive splotches on the reverse side of the print. Thus, there is a need for paper transport belt cleaning mechanisms.  
         SUMMARY OF THE INVENTION  
         [0006]    In one basic aspect, the present invention provides a cleaning medium for feeding through an ink-jet apparatus print zone to clean a paper transport belt, including: an absorbent material layer having a surface for frictional contact with the belt such that friction between the absorbent material layer and the belt scrubs ink from the belt and ink is absorbed into the material layer.  
           [0007]    In another basic aspect, the present invention provides method for cleaning an ink-jet paper, endless loop, transport belt including the steps of: feeding a cleaning medium from an input into a print zone wherein the cleaning medium is in surface-to-surface contact with the belt; passing the cleaning medium through the print zone such that the belt is in contact thereagainst; absorbing ink from the belt into the cleaning medium; and releasing the cleaning medium from the print zone.  
           [0008]    In another basic aspect, the present invention provides ink-jet hard copy system including: an endless loop belt for conveying media from an input through a printing zone to an output; an ink-jet writing instrument positioned for depositing ink in the printing zone; a feed device for guiding media from the input to the belt and for selectively holding a sheet of media in the printing zone irrespective of movement of the belt; and at least one cleaning medium associated with the feed device for selectively scrubbing the belt.  
           [0009]    In another basic aspect, the present invention provides cleaning medium for cleaning a transport apparatus for sheet material, including: a cleaning material construct having at least one surface for contact with components of the sheet transport device wherein the construct is fed into the sheet transport device in like manner as the sheet material.  
           [0010]    Some advantages of the present invention are:  
           [0011]    it dissolves ink and absorbs ink from the belt and other components in the paper path that can be contaminated;  
           [0012]    it scrubs the belt of contaminants that can affect its functionality;  
           [0013]    it requires no additional mechanisms to be incorporated into the hard copy apparatus;  
           [0014]    it assists in removing contaminants from the platen surface below the belt; and  
           [0015]    disposability makes the invention a low cost; reliable solution.  
           [0016]    The foregoing summary and list of advantages is not intended by the inventors to be an inclusive list of all the aspects, objects, advantages and features of the present invention nor should any limitation on the scope of the invention be implied therefrom. This Summary is provided in accordance with the mandate of 37 C.F.R. 1.73 and M.P.E.P. 608.01(d) merely to apprise the public, and more especially those interested in the particular art to which the invention relates, of the nature of the invention in order to be of assistance in aiding ready understanding of the patent in future searches. Other objects, features and advantages of the present invention will become apparent upon consideration of the following explanation and the accompanying drawings, in which like reference designations represent like features throughout the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 (Prior Art) is a schematic illustration of an ink-jet hard copy apparatus.  
         [0018]    [0018]FIG. 2 is a schematic illustration of a cross-section of a cleaning medium in accordance with the present invention.  
         [0019]    [0019]FIG. 3 is a schematic illustration in accordance with the present invention demonstrating the cleaning medium of FIG. 2 in an input tray of a hard copy apparatus.  
         [0020]    [0020]FIG. 4 is a schematic illustration of the present invention with the cleaning medium in a printing zone of the hard copy apparatus as shown in FIG. 3 during belt and platen cleaning.  
         [0021]    [0021]FIG. 5 is a schematic illustration of the present invention with the cleaning medium in an output tray of the hard copy apparatus as shown in FIGS. 3 and 4.  
         [0022]    [0022]FIG. 6 is a sectional view of another embodiment of the cleaning medium of FIG. 2. 
     
    
       [0023]    The drawings referred to in this specification should be understood as not being drawn to scale except if specifically noted.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    Reference is made now in detail to a specific embodiment of the present invention, which illustrates the best mode presently contemplated by the inventors for practicing the invention. Alternative embodiments are also briefly described as applicable. The implementation, shown in conjunction with an ink-jet printer, is for convenience in explaining the present invention and no limitation on the scope of the invention is intended by the inventors nor should any be implied.  
         [0025]    To clean a paper transport belt  32  as shown in FIG. 1, or a like state-of-the art, belt transport ink-jet printer  10 , both wet and dried ink deposits need to be loosened, then removed from the belt and the printer environment.  
         [0026]    [0026]FIG. 2 depicts a preferred embodiment of a two-piece, disposable, cleaning medium  201  in accordance with the present invention. An absorbent material layer  202  will be used to scrub the belt  32 . While a dry absorbent material layer  202  can be employed, the effectiveness of the cleaning process is markedly improved if the absorbent material layer  202  has an outer surface  202 ′, with a solvent or solvent solution associated with the ink formula used in the pen  12 . Exemplary materials for the absorbent material layer  202  that have been found suitable to an ink-jet printer environment are cellulose-based fabric (such as used in commercially available shop towels), lint-free Chem-Wipes™, thermal-bonded non-woven textiles and absorbent lint-free papers. For water-based ink formulations, an exemplary solvent solution may be water, de-ionized water, or a hydro-solution using a surfactant such as tergitol-S-5, or alkaline (sodium bicarbonate) or potassium hydroxide (KOH) or using an active solvent such as polyethylene glycol (PEG) or isopropanol (IPA). The solvent solution formation can be tailored empirically for any specific implementation.  
         [0027]    A backing layer  203  secured to the absorbent material layer  202  may be used if the absorbent material layer is not sufficiently rigid; a polymer film has been found to provide sufficient added stiffness. The backing sheet  203  should have a stiffness suitable for ensuring that no paper jam occurs. Thermal-bonding, mechanical bonding, or the use of a material-compatible, known adhesive can be employed for mounting the absorbent material layer  202  with the backing layer  203 .  
         [0028]    If the pen  12  is a stationary instrument, such as a page wide array, the overall thickness of the cleaning medium  201  must be such that it can pass through the printing zone  34  without contacting the printhead  14 . Otherwise, a mechanism for lifting the array should be provided. If the pen  12  is a scanning type, it is parked in its service station (not shown) during the belt cleaning cycle.  
         [0029]    When belt cleaning is necessary—for example, when the end-user notices ink markings on the back of a print—the cleaning medium  201  is loaded and run through the paper path  31  of the apparatus as demonstrated in FIGS. 3, 4 and  5 . The cleaning medium  201  is loaded into the input tray  301  by the end-user, either as the only sheet in the input tray or in any special media tray provided by the apparatus manufacturer for single sheet feed cycles (often provided so that special media, such as transparencies, can be run through a printing cycle without unloading the standard paper tray with the absorbent material layer  202  oriented to come into contact with the belt  32  outer surface. A pick mechanism  303  is engaged to transfer the leading edge  204  of the cleaning medium  201  into a nip between two feed rollers  304 ,  305  upstream of the print zone  34 , at least one of the feed rollers is actively driven by a motor (not shown) such that the two feed rollers engage the cleaning medium  201  and drive it along the paper path  31  and into the print zone as illustrated by FIG. 4. Once the cleaning medium  201  is thus loaded in the print zone  34 , the feed rollers  304 ,  305  are stopped—or at least substantially slowed—so that the cleaning medium  201  is substantially held stationary in the print zone  34  by the normal force (arrows  401 ,  402 ) of the feed rollers while the belt  32  continues to be driven by the belt drive wheels  38 ,  40 . This causes a wiping action between the cleaning medium  201  absorbent material layer  202 (FIG. 2 only) and the belt  32  outer surface. The solvent, when employed, rehydrates ink deposits on the belt  32 . Moreover, as the belt  32  is porous, it has been found that the solvent can penetrate the belt and rehydrates any ink deposits on the subjacent platen  36 . The added abrasion between the belt outer surface and the absorbent material layer  202  by fully stopping the cleaning medium in the print zone  34  improves the cleaning of the belt  32 .  
         [0030]    It has been found that indexing the cleaning medium  201  in steps  201  in steps through the print zone  34  so that a clean portion of the cleaning medium  201  is brought into contact with the belt  32  for incremental belt advance, for each semi-rotation or full rotation cycle, or for multiple rotations improves the scrubbing results. In other words, the cleaning medium  201  advance into the print zone  34  is first stopped with just a region adjacent to the leading edge  204  in contact with the belt  32 ; scrubbing is permitted for a predetermined time or distance; then, the cleaning medium is again advanced another predetermined distance into the print zone  34  and stopped again; then, the stepping proceeds such that a fresh region of the cleaning medium  201  is sequentially brought into contact with an even cleaner belt surface. To ensure full belt cleaning, the cleaning medium  201  width should be at least as great as the width of the belt  32 .  
         [0031]    A known-manner output or platen heater (not shown) can be used to dry the cleaning medium  201  before transporting it to an output tray, preventing the solvent from being transferred onto output transport components or into the output tray. Such heating will also ensure the belt  32  is dried before the next printing cycle begins.  
         [0032]    Note also that the cleaning medium  201  can be segregated into alternating solvent soaked regions and dry regions for sequential contact with the belt  32  surface during the cleaning cycle.  
         [0033]    Some solvents will be more aggressive when heated. Therefore, it is advantageous to incorporate heat transfer from the platen  36  to the cleaning medium  201  via the intermediate belt  32 .  
         [0034]    As shown in FIG. 5, after a predetermined time, or number of steps, the trailing edge  205  of the cleaning medium  201  is released by the feed rollers  304 ,  305 . The belt  32  delivers the used cleaning medium  201  to an output tray  306  where it can be removed and properly disposed of by the end-user.  
         [0035]    The foregoing description of the preferred embodiment of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. For example, a known manner solvent dispensing subsystem can be incorporated in the hard copy apparatus and used. The cleaning medium may be fed from a replaceable roll rather than being in sheet form. The belt  32  may be the type having a friction surface rather than be a vacuum belt. The vacuum, however, will improve scrubbing as the absorbent layer  202  will be pulsed more tightly against the belt&#39;s outer surface in the print zone  34 . This can also be achieved with no vacuum by using a pinch force over the platen.  
         [0036]    Similarly, any process steps described might be interchangeable with other steps in order to achieve the same result. The embodiment was chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents. Reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather means “one or more.” Moreover, no element, component, nor method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the following claims. No claim element herein is to be construed under the provisions of 35 U.S.C. Sec. 112, sixth paragraph, unless the element is expressly recited using the phrase “means for . . . .”