Patent Publication Number: US-3878818-A

Title: Cleaning apparatus for dry fuser rolls

Description:
United States Patent [191 Thettu et al. I  
 1 1 CLEANING APPARATUS FOR DRY FUSER ROLLS [75] Inventors: Raghulinga R. Thettu, Webster;  
 Donald J. Quant, Rochester, both of NY.  
 [73] Assignee: Xerox Corporation, Stamford,  
 Conn.  
  22 Filed: Aug. 10, 1973 21 Appl. No.: 387,409  
 [52] US. Cl. 118/637; 118/104; 432/60 [51] Int. Cl G03g 13/00 [58] Field of Search 118/60, 101, 104, 202,  
 118/203, 70, 261, 637; 271/DIG. 2; 432/60, 228  
 [56] References Cited UNITED STATES PATENTS 1,933,837 1l/1933 Arnold 118/104 2,239,383 4/1941 Drewsen 118/70 2,937,390 5/1960 Bolton ct a1. 118/104 X 3,037,451 6/1962 Davis 118/261 3,175,923 3/1965 Lerner... 118/70 3,626,833 12/1971 Koch 95/89 R 3,634,077 1/1972 Sullivan 96/1.4 3,649,992 3/1972 Thettu 118/60 X 3,716,018 2/1973 Ohta et a1. 118/101 [451 Apr. 22, 1975 Primary- Evaminer-Mervin Stein Assistant Examiner-Leo Millstein [57] ABSTRACT Cleaning apparatus for a dry heated pressure fusing system in which a conformable roll having a sleeve made of a material selected from the group of fluoro carbon resins, silicone, or fluorosilicones contacts the dry fuser roll to receive both paper contamination and non-visual toner offset to maintain clean copy sheets fixed by the fusing system. Some paper contamination and toner is electrostatically attracted to the cleaning r011 by electrostatic attraction as well as surface forces. A cleaning pad is retractably positioned to scrub the dry fuser roll surface to loosen fine sizing particles in the paper and tiny toner particles so that they can be removed onto the sleeve. The contamination and toner offset are removed from the sleeve by a wiping member which may be non-tacky or tacky.  
 3 Claims, 3 Drawing Figures PATENTEUAPRZZIQIS sum 2 OF? FIG. 2  
 FIG. 3  
  1 CLEANING APPARATUS FOR DRY FUSER ROLLS This invention relates to an improved cleaning apparatus for use with a dry heated pressure fusing system in an electrostatic reproduction system to produce high quality copies free of toner background.-  
  It has been recognized that one of the preferred ways for fusing a powder image to a substrate is to bring the powder into direct contact with a hot surface. such as a heated roller. The roller surface may be dry. i.e.. no application of a liquid release agent to the surface of that roller as described for example. in U.S. Pat. Nos. 3.498.596. 3.539.16l and 3.666.247. Alternatively. the fuser roll surface may be wetted with a release agent such as silicone oil as described in U.S. Pat. Nos. 3.268.351 and 3.265.002. v  
  In the dry fusing system there is a tendency for the fuser roll to collect paper contamination and non-visual or minute toner particles which in turn cause a visual toner offset to build up on the fuser roll surface and be deposited as background on the copy sheets. It is particularly important to remove minute paper sizing particles and tiny toner particles which are normally difficult to remove from a dry heated fuser roll.  
  The present invention is an improved cleaning apparatus for cleaning dry fuser rolls to remove undesirable paper contaminants and non-visual toner particles. in the 2-5 micron range as well as visual toner offset.  
  lt is therefore the principle object of the present invention to improve heated pressure fusing roll devices.  
  It is a further object of the present invention to enable removal of fine paper contaminants and tiny toner particles from a dry heated fuser roll.  
  It is a further object of the present invention to prevent toner offset from the surface of the fuser roll onto copy sheets.  
  It is a further object of the present invention to improve copy quality of copy sheets fused by dry pressure heated fuser systems.  
  These as well as other objects of the invention and further features thereof will be better understood upon reference to the following detailed description of the invention to be read in connection with the drawings wherein:  
  FIG. 1 illustrates schematically a xerographic reproducing apparatus incorporating a heated pressure fuser roll apparatus constructed in accordance with the present invention.  
  FIG. 2 is an enlarged portion of FIG. 1 illustrating details of the invention. and  
  FIG. 3 is a view similar to FIG. 2 illustrating an alternative embodiment.  
  Referring now to the drawings. there is shown in FIG. 1 a preferred embodiment of the subject invention in a suitable environment such as an automatic xerographic reproducing machine. The automatic xerographic reproducing machine includes a xerographic plate or surface formed in the shape ofa drum. The plate has a photoconductive layer or light receiving surface on a conductive backing. journaled in a frame to rotate in the direction indicated by the arrow. The rotation will cause the plate surface to sequentially pass a series of xerographic processing stations. For the purpose of the present disclosure the several xerographie processing stations in the path of movement of the plate surface may be described functionally as follows:  
  A charging station A. at which a uniform electrostatic charge is deposited on the photoconductive plate:  
  An exposure station B. at which light or a radiation pattern of copies to be reproduced is projected onto the plate surface to dissipate the charge in the exposed areas thereof to thereby form alatent electrostatic image of the copies to be reproduced;  
  A developing station C. at which xerographic developing material. including toner particles having an electrostatic charge opposite that of the latent electrostatic image. is cascaded over the latent electrostatic image to form a toner powder image in configuration of the copy being reproduced;  
  A transfer station D. at which the toner powder image is clectrostatically transferred from the plate surface to a transfer material or a support surface; and  
  A drum cleaning and discharge station E. at which the plate surface is brushed to remove residual toner particles remaining thereon after image transfer and at which the plate is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.  
  The preceding description of the xerographic process is sufficient for an understanding of the instant invention. Further details may be had by reference to U.S. Pat. No. 3.578.859 filed July 3. 1969 and commonly assigned herewith.  
  At the fusing station F the fusing assembly 101 comprises a fuser roll 103 and pressure roll 105 through which the copy sheet to be fused is advanced through the nip formed by contact ofthe fuser roll and pressure roll. The copy sheet is stripped from the fuser roll 10 by stripper fingers 112. The fuser roll comprises a rotating member having an elastic compressible coating 132 made of silicone rubber or any suitable heat resistant compressible material as described for example in the aforementioned patents. The rotating member may be internally heated by a heat source 134 as described in U.S. Pat. No. 3.666.247 or externally heated as described in U.S. Pat. Nos. 3.498.586 and 3.538.16l The pressure roll comprises a rotating member which is covered with an elastic layer 142 or a slightly higher durometer and the fuser roll coating 132 as described in the aforementioned patents.  
  Referring specifically to HQ. 2 a cleaning roll apparatus 201 positioned to clean fuser roll 103 of paper contamination and non-visual as well as visual toner offset particles. Cleaning roll apparatus 201 includes a metal core member 203 which-is blanketed in a cylindrical roll 205 made ofa soft deformable material. Any suitable soft heat resistant material can be used. such as silicone rubber. Nomex. or Dacron trademarks of DuPont Corporation. Wilmington. Delaware. A sleeve 207 covers cylinder 205. Sleeve 207 is made of a suitable material which attracts by surface forces paper contamination and toner offset. Typical materials are fluoro carbon resins including fluoro ethylene propylene manufactured under the trademark of Teflon by DuPont Corporation. silicones and fluorosilicones. The silicones are moisture flooded as for example. General Electric RTVl l2 and Dow Company RTV733.  
  It has been found that paper contamination on the fuser roll 103 is clectrostatically attracted to sleeve 207 due to an opposite charge generated on the surface. lnitially. the fuser roll I03 drives pressure roll 105 generating static charges. When contamination builds up on the copysheet causes a decrease in the positivecharge thereby increasing the negative charge. Any loose &#39;paper fibers and/orbackground toner particles which are normally negative are attracted by the fuser roll surface which is positively induced. As a result the contaminationiand.toner particles collect on the fuser roll surfaceandare transferred tothe sleeve 207 by virtue -of the negatively induced charge thereon. The contami nation and toner particles are removed from the sleeve by -a wiper pad 210 which is made of Wool. Nomex or Dacron andcan be dry or slightly wet with silicone oil. Unfortunately. the tiny sizing particles in the paper and .minute toner particles range from about submicron to .l(-)= microns-stick to the dry heated fuser roll surface.  
 In accordance with the present invention a retractable scrubber-member 250 is positioned to loosen tiny contamination particles from the dry heated fusersurface. As best shown in H6. 2 scrubber member 250 includes a pad-portion 252 which is secured to a leaf spring portion.254 which urges pad portion 252 into a constant pressure contact with the fuser roll surface.  
 ,Pad portion 252 is made of any suitable heat resistant material. Typical materials are Nomex. Dacron. metallic&#39;libers and combinations thereof. By this structure a &#34;positivescrubbingaction is imported to the fuser roll surfaee&#39;freeing up the very minute paper sizing particles and toner particles enabling them to be removed onto the-sleeve 207. The scrubbermember&#39;is retractable from the fuscr roll during standby mode to prevent vsmudges generally caused by the contamination col- .lected on the pad portion surface. A suitable vibrating meansv (not shown) is connected to the sc rubber member toprevent radial scratching on the fuser roll surface and separation ofcontamination.  
 - An alternative embodiment shown in FIG. 3 in which pad portion 250 is replaced with an indexible stationary roll 260 which is made of a rigid substrate covered with a soft coarse deformable material such as Nomex or Dacron. I 7  
  While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment. it&#39;will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.  
 I What is claimed is:  
  1. An improved cleaning apparatus for dry heated pressure roll fusing systems in which paper contaminants and toner particles on the dry fusing roll surface are removed. the improvement comprising:  
 a cleaning roll member including a soft elastomeric blankethaving an outer sleeve positioned in contact with a fusing roll surface to attract paper contaminants and toner particles. and  
 wiping means positioned to contact said fusing roll surface to scrub-and loosen tiny paper contaminants and toner particles ranging in size from submic-ron to about 10 microns sticking on the dry fuser roll surface whereby said contaminants and toner particles can be removed onto said sleeve. said wiping means includes a pad member made of a heat resistant material urged into pressure contact with said fusing roll&#39; surface at a constant pressure. I I t I I .2. Apparatus according to claiml wherein said pad member is urged against the fusing roll surface by a spring member. I  
  3. Apparatus according to claim l wherein said pad member is retractable during standby mode of operation. 1