Abstract:
The fuser roller and heater rollers of the fusing system can become contaminated with ink and other foreign material when pre-printed materials are run through them. The contamination can create regions of cold spots, which in turn results in poor fusing. Other image defects may result. According the various aspects of the invention, a heater roller cleaner, method and apparatus are provided for applying an array of differential pressure generating areas to a heater roller surface in a fuser assembly while rotating the heater roller surface.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This is a 111A application of U.S. Provisional Application Ser. No. 60/537,271, filed Jan. 16, 2004, entitled “HEATER ROLLER CLEANER, METHOD, AND APPARATUS FOR A FUSER ASSEMBLY” by Kurt E. Jones, et al. 

   BACKGROUND OF THE INVENTION 
   The fuser roller and heater rollers of the fusing system can become contaminated with ink and other foreign material when pre-printed materials are run through them. The contamination can create regions of cold spots, which in turn results in poor fusing. Other image defects may result. 
   SUMMARY OF THE INVENTION 
   According the various aspects of the invention, a heater roller cleaner, method and apparatus are provided for applying an array of differential pressure generating areas to a heater roller surface in a fuser assembly while rotating the heater roller surface. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  presents a schematic view of an electrographic apparatus according to an aspect of the invention. 
       FIG. 2  presents a schematic detailed view of a fuser assembly according to an aspect of the invention. 
       FIG. 3  presents a heater roller and array of differential pressure generating areas according to an aspect of the invention. 
       FIG. 4  presents a cleaning surface according to an aspect of the invention. 
       FIG. 5  presents a schematic view of a fuser cleaning assembly according to an aspect of the invention. 
       FIG. 6  presents a cleaning surface according to a further aspect of the invention. 
       FIG. 7  presents a cylindrical brush according to an aspect of the invention. 
       FIG. 8  presents an end view of the  FIG. 7  cylindrical brush. 
       FIG. 9  presents a perspective view of a fuser cleaning assembly according to an aspect of the invention. 
       FIG. 10  presents a top view of a separator according to an aspect of the invention. 
       FIG. 11  presents a side view of the  FIG. 10  separator. 
       FIG. 12  presents an end view of  FIG. 11 . 
       FIG. 13  presents a cross-sectional view of a brush bristle/channel according to an aspect of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Various aspects of the invention are presented in  FIGS. 1-13 , which are not drawn to any particular scale, and wherein like components in the numerous views are numbered alike. Referring now to  FIG. 1 , a typical electrographic apparatus or machine  10  (e.g. copier, duplicator, printer) of the kind that has an endless photoconductor member  11  which moves through a closed loop past a charging station  12 , an exposure or input station  13 , a developing station  14 , a transfer station  15 , and an erase section  16 . A copy medium (e.g. a sheet S of paper) is fed from a supply (not shown) through transfer station  15  where a toner image on the film  11  is transferred onto the paper S. The paper S is then fed between a fuser roller  21  and a pressure roller  22  in a fuser assembly  20  according to the invention in order to fix the toner image on the paper S before the paper exits the machine. Although described in relation to an electrophotographic embodiment, the invention is equally applicable to other electrographic apparatus and processes, for example ionography, without limitation. 
   Referring now to  FIG. 2 , an end view is presented of a typical fuser assembly  20  which might be found in the electrophotographic machine  10  of  FIG. 1 . As illustrated, the fuser assembly  20  comprises a frame or housing  25  in which pressure roller  22 , fuser roller  21 , and one or more heating rollers  23  are rotatably mounted. As will be understood in the art, a motor (not shown) mounted on the housing  25  rotates pressure roller  22  which, in turn, rotates fuser roller  21  and the heater rollers  23  through the frictional contact therebetween. Fuser roller  21  is heated by heating rollers  23  so that when the sheet of paper S or the like passes through the nip between rollers  21 ,  22 , the heat and pressure exerted thereby will cause the toner carried on S to become fused on the paper. The heating rollers  23  may be heated in various ways, for example by a heat lamp disposed inside each roller  23 . 
   A wick roller assembly  24  may be positioned within the housing  25  and includes a wick roller  24   a  for applying a “release” oil directly onto fuser roller  21 . This oil helps to prevent “offset”, i.e. prevents toner from sticking to the fuser roller  21 . Excess oil along with residual toner, paper dust, etc., may build-up on the fuser roller and be transferred to and contaminate heater rollers  23 . 
   To remove these contaminants, a fuser cleaning assembly  30  is provided within fuser housing  25  which includes a web  31  of material which contacts the heater rollers  23  to “wipe” and remove the contaminants therefrom as the copying operation is being carried out. As is known in the art, web  31  may be comprised of any flexible, cleaning material which is capable of removing the contaminants from the heater rollers upon contact (e.g. cloth-like material composed of Nomexg® polyarimide fiber available from E. I. Dupont and de Nemours, &amp; Co.) without damaging the heater rollers  23 . The cleaning material  31  is wound onto a supply roller  32  and passes over a roller  33  and onto take-up roller  34 . The roller  33  holds material in contact with both of heater rollers  23  when assembly  30  is in its operable position within fuser housing  25 . The supply roller  32 , heater roller cleaner  110 , and take-up roller  34  are mounted on a frame  35  using suitable bearings. The fuser cleaning assembly may be removable from the machine on a slide, as described in U.S. Pat. No. 6,631,251. 
   Referring now to  FIG. 3 , a method of cleaning the heater roller  23  in the fuser assembly  20 , comprising applying an array  100  of differential pressure generating areas  101  to a heater roller surface  102  in the fuser assembly  20  while rotating the heater roller surface  102 . The differential pressure generating areas  101  preferably generate a greater pressure in corresponding areas of the heater roller surface  102  than in adjacent areas. Referring now to  FIG. 4 , the method may comprise contacting the heater roller surface  102  with a cleaning surface  104  comprising the array  100  of the differential pressure generating areas  101 . The array  100  of differential pressure generating areas  101  may be pressed against the heater roller surface  102 . Referring now to  FIG. 5 , the cleaning surface  104  may comprise the web  31  and the web  31  contacts and may be pressed against the heater roller surface  102 . The web  31  may be passed along the heater roller surface  102  over the array  100  of differential pressure generating areas  101 . The method may also comprise separating the web from the array  100  of differential pressure generating areas  101  with a separator  108  that may be disposed on the downstream side. 
   The array  100  of differential pressure generating areas  101  may comprise 5 to 200 points of contact per square inch. Other ranges are contemplated in the practice of the invention, such as 10 to 100 points of contact per square inch and 40 to 100 points of contact per square inch. The differential pressure generating areas  101  are preferably discontinuous and discrete. 
   The cleaning surface  104  may be the web  31  having an appropriately textured surface. The web  31  may have an abrasive surface. 
   Preferably, a textured surface is placed beneath the web  31  and presses the web  31  against the heater roller surface  102 . Molded and tooled surfaces are suitable in the practice of the invention. Elastomers, plastics and metals are all suitable materials. A knurled surface or woven screen surface may be implemented. A 60-150 grit surface may be implemented with grit particles bonded to a backing material with an adhesive having suitable heat resistance. A resilient surface, as provided by an elastomer or brush bristle for example, may be advantageous. A width  124  of contact between the cleaning surface and the heater roller surface  102  may be on the order of 0.12 inch to 0.30 inch, although the invention is not so limited. Variations evident in light of the description provided herein are innumerable. 
   The array  100  of differential pressure generating areas  101  may be ordered or random. Consideration may be given for moving the array  100 , for example parallel to the heater roller surface  102  axis of rotation in order to ensure that cleaning is applied to the entire heater roller surface  102 . This may be particularly desired if the array  100  is ordered since a patterned removal of contamination may result. 
   The web  31  serves a cleaning function in addition to cleaning the heater roller surface  102  by preventing build-up of contaminates in the array  100  of pressure generating areas  101 . However, the web  31  need not be implemented in the practice of the invention. An alternate cleaning mechanism for cleaning the array  100  of pressure generating areas  101  such as a beater bar and/or vacuum cleaner may serve the same purpose. For example, the array  100  of pressure generating areas  101  may be a rotating brush and may be cleaned by a beater bar and/or vacuum cleaner. 
   With reference to  FIGS. 5 and 6 , and according to a further aspect of the invention, a heater roller cleaner  110  is provided with the array  100  of differential pressure generating areas  101  applicable to the heater roller surface  102 . The heater roller cleaner  104  may be a cylindrical brush comprising metal and/or plastic bristles. Brush bristles provide resilience that is advantageous particularly when the brush is pressed against the heater roller surface  102 . The interference between the brush and the heater roller  23  may be on the order of 0.003 inch to 0.02 inch, inclusive. According to a preferred embodiment, a brush  112  is fully composed of metal bristles  114  only, such as brass, arranged in a helix along a longitudinal axis  116  of the brush  112  and attached to a shaft  118 , as shown in  FIGS. 7 and 8 . Shaft  118  may be steel or other material suitable in the practice of the invention. The brush is believed to develop a scrubbing action on the heater roller surface  102 . 
   In a certain embodiment, the shaft  118  is stainless steel with a ⅜″ outside diameter and is about 15 inches long. The brush has a 1¼ inch outside diameter brush face. The bristles are composed of 0.003 inch diameter brass wire. Bristles  120  of this brush are crimped in a galvanized channel  122 , as shown in  FIG. 13 , and the channel  122  (with the bristles  120  crimped to it) is wound in a helix along the shaft  118 , and tack welded to the shaft  118  at both ends. A suitable brush is available from The Industrial Brush Company Inc., of Fairfield, N.J., U.S.A. (“#2 galvanized close wound 0.003 level brass”). In this embodiment, the heater roller  23  is 5052 aluminum having a 1.5 inch outside diameter and a hard anodized outer coating. The width  124  of contact between the brush/web and heater roller surface  102  is on the order of 0.22 inches. 
   Referring to  FIG. 9 , a perspective view of a fuser cleaning assembly  30  adapted for use with the fuser assembly  20  of  FIG. 2  and the brush  112  of  FIGS. 7 and 8  is presented (the brush  112  replaces the roller  33 ). The separator  108  is implemented. The web  31  is not shown for the sake of clarity, and the web take-up roller  34  is in a full condition, and the web-supply roller  32  is in an empty condition (just prior to replacement, for example). In the  FIG. 9  embodiment, the brush  112  comprises brass bristles, and is incremented with the web  31  every 275 prints. Experiments have demonstrated that the heater roller surfaces  102  are maintained in a suitably clean state for 750,000 prints as compared to 100,000 prints for the prior art system, which implemented a cylindrical elastomeric tensioner roller with a smooth surface in place of the brush  112 . 
   The dimensions of the brush  112  determine, in part, the rate at which it and the web  31  are incremented. As the brush  112  is rotated, the rows of bristles  114  in contact with the heater roller surface  102  advance parallel to the longitudinal axis  116  due to their helical arrangement around the shaft  118 . Selection of an appropriate rate at which the brush  112  and web  31  are incremented, and thus the rotation rate, ensures that the entire heater roller surface  102  is sufficiently cleaned, and prevents an unacceptable patterned removal of contamination. The rate at which the brush  112  and web  31  are incremented is best determined by experimentation. 
   Top, side, and end views of the separator  108  of  FIG. 9  are presented in  FIGS. 10 ,  11 , and  12 , respectively. The separator  108  of  FIGS. 9-12  is formed from a suitably stiff material such as stainless steel 0.03 inch thick so as to resist a pulling force in the direction of web travel. 
   Although the invention has been described and illustrated with reference to specific illustrative embodiments thereof, it is not intended that the invention be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the true scope and spirit of the invention as defined by the claims that follow. It is therefore intended to include within the invention all such variations and modifications as fall within the scope of the appended claims and equivalents thereof. 
   PARTS LIST 
   
       
       S sheet 
         10  electrographic apparatus or machine 
         11  photoconductor member 
         12  charging station 
         13  exposure or input station 
         14  developing station 
         15  transfer station 
         16  erase section 
         20  fuser assembly 
         21  a fuser roller 
         22  pressure roller 
         23  heater rollers 
         24  wick roller assembly 
         24   a  wick roller 
         25  frame or housing 
         30  fuser cleaning assembly 
         31  web 
         32  supply roller 
         33  roller 
         34  take-up roller 
         35  frame 
         100  array 
         101  differential pressure generating areas 
         102  heater roller surface 
         104  cleaning surface 
         108  separator 
         110  heater roller cleaner 
         112  brush 
         114  metal bristles 
         116  longitudinal axis 
         118  shaft 
         120  bristles 
         122  channel 
         124  width