Abstract:
An apparatus for removing residual particles from an imaging surface, including a cleaning blade having an edge adapted to remove the residual particles from the imaging surface; an electrode array, coacting with the cleaning blade, for removing residual toner particles in a direction of movement away from the edge of the cleaning blade; and a wave generator for generating a traveling wave pattern for moving residual particles in the direction of movement.

Description:
BACKGROUND OF THE INVENTION 
     Cross reference is made to the following application filed concurrently herewith: U.S. Ser. No. 09/722,925 entitled “Toner Dispensing Apparatus Employing A Traveling Wave Transport Grid” by Bruce E. Thayer et al. 
    
    
     This invention relates generally to an electrostatographic printer and copier, and more particularly concerns a cleaning apparatus. 
     Blade cleaning of photoreceptors (i.e. imaging surfaces or photoconductors) is basically a simple and economical concept that has reliability concerns. Random failures justify the reluctance to include blade cleaners in higher volume machines without, or even with, some back-up cleaning element. Alternative cleaning devices, including magnetic, insulative and electrostatic brush assemblies are invariably installed as the primary cleaning element in higher volume machine applications. Use of devices exhibiting predictive or deterministic failure modes also facilitate identification and resolution of cleaning problems rising from other sources. Manifestations of deterministic cleaning failures include, but are not limited to, photoreceptor filming and cometing. (Cometing is where material, including toner particles, become impacted onto the photoreceptor and adhere with such force that they cannot be removed by the shearing or scraping action of the cleaning element.) 
     Toner cleaned by the tip of a cleaning blade often piles up on top of the blade and the supporting blade holder. This is often not a problem if the architectural location of the cleaner allows gravity to pull the toner pile down the blade surface. For architectural locations where gravity cannot cause the toner to flow easily across the blade surface toner can build up to the point where an active means is required to maintain toner flow away from the blade tip. These could include thumpers, stirrers, augers, paddlewheels or brushes. These devices can easily take up more space and cost more than the cleaning blade itself. 
     Therefore, there is a need to reduce cost of these devices and more importantly to reduce the space required to mount these devices. 
     SUMMARY OF THE INVENTION 
     Briefly stated, and in accordance with one aspect of the present invention, there is provided an apparatus for removing residual particles from an imaging surface, including a cleaning blade having an edge adapted to remove the residual particles from the imaging surface; an electrode array, coacting with said cleaning blade, for removing residual toner particles in a direction of movement away from the edge of said cleaning blade; and a wave generator for generating a traveling wave pattern for moving residual particles in said direction of movement. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features of the present invention will become apparent as the following description proceeds and upon reference to the drawings, in which: 
     FIG. 1 is a schematic illustration of a printing apparatus incorporating the inventive features of the present invention; 
     FIGS. 2 and 5 show a schematic elevational views of cleaning blade apparatuses of the present invention; 
     FIGS. 3 and 4 are top views of a portion of the flexible transport grid of the present invention. 
    
    
     While the present invention will be described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
     For a general understanding of an electrophotographic printer or copier in which the present invention may be incorporated, reference is made to FIG. 1 which depicts schematically the various components thereof. Hereinafter, like reference numerals will be employed throughout to designate identical elements. Although the electrostatic brush cleaner with a secondary cleaner apparatus of the present invention is particularly well adapted for use in an electrophotographic printing machine, it should become evident from the following discussion, that it is equally well suited for use in other applications and is not necessarily limited to the particular embodiments shown herein. 
     Referring now to the drawings, the various processing stations employed in the reproduction machine illustrated in FIG. 1 will be described briefly hereinafter. It will no doubt be appreciated that the various processing elements also find advantageous use in electrophotographic printing applications from an electronically stored original, and with appropriate modifications, to an ion projection device which deposits ions in image configuration on a charge retentive surface. 
     A reproduction machine, in which the present invention finds advantageous use, has a photoreceptor belt  10 , having a photoconductive (or imaging) surface  11 . The photoreceptor belt  10  moves in the direction of arrow  12  to advance successive portions of belt  10  sequentially through the various processing stations disposed about the path of movement thereof. Belt  10  is entrained about a stripping roller  14 , a tension roller  16 , and a drive roller  20 . Drive roller  20  is coupled to a motor  21  by suitable means such as a belt drive. Belt  10  is maintained in tension by a pair of springs (not shown) resiliently urging tension roller  16  against belt  10  with the desired spring force. Both stripping roller  14  and tension roller  16  are rotatably mounted. These rollers are idlers which rotate freely as belt  10  moves in the direction of arrow  12 . 
     With continued reference to FIG. 1, initially a portion of belt  10  passes through charging station A. At charging station A, a corona device  22  charges a portion of the photoreceptor belt  10  to a relatively high, substantially uniform potential, either positive or negative. At exposure station B, an original document is positioned face down on a transparent platen  30  for illumination with flash lamps  32 . Light rays reflected from the original document are reflected through a lens  33  and projected onto the charged portion of the photoreceptor belt  10  to selectively dissipate the charge thereon. This records an electrostatic latent image on the belt which corresponds to the informational area contained within the original document. 
     Alternatively, a laser may be provided to imagewise discharge the photoreceptor belt in accordance with stored electronic information. Thereafter, belt  10  advances the electrostatic latent image to development station C. At development station C, one of at least two developer housings  34  and  36  is brought into contact with belt  10  for the purpose of developing the electrostatic latent image. Housings  34  and  36  may be moved into and out of developing position with corresponding cams  38  and  40 , which are selectively driven by motor  21 . Developer housings  34  and  36  support a developing system such as magnetic brush rolls  42  and  44 , which provides a rotating magnetic member to advance developer mix (i.e. carrier beads and toner) into contact with the electrostatic latent image. The electrostatic latent image attracts toner particles from the carrier beads, thereby forming toner powder images on the photoreceptor belt  10 . If two colors of developer material are not required, the second developer housing may be omitted. The photoreceptor belt  10  then advances the developed latent image to transfer station D. 
     At transfer station D, a sheet of support material such as paper copy sheets is advanced into contact with the developed latent images on belt  10 . A corona generating device  46  charges the copy sheet to the proper potential so that it becomes tacked to the photoreceptor belt  10  and the toner powder image is attracted from the photoreceptor belt  10  to the sheet. 
     After transfer, a corona generator  48  charges the copy sheet to an opposite polarity to detach the copy sheet from belt  10 , whereupon the sheet is stripped from belt  10  at stripping roller  14 . Sheets of support material  49  are advanced to transfer station D from supply tray  50 . Sheets are fed from tray  50  with sheet feeder  52 , and advanced to transfer station D along conveyor  56 . After transfer, the sheet continues to move in the direction of arrow  60  to fusing station E. Fusing station E includes a fuser assembly, indicated generally by the reference numeral  70 , which permanently affixes the transferred toner powder images to the sheets. Preferably, the fuser assembly  70  includes a heated fuser roller  72  adapted to be pressure engaged with a backup roller  74  with the toner powder images contacting the fuser roller  72 . 
     In this manner, the toner powder image is permanently affixed to the sheet, and such sheets are directed via a chute  62  to an output tray  80  or finisher. Residual particles, remaining on the photoreceptor belt  10  after each copy is made, may be removed at cleaning station F. The cleaning apparatus of the present invention is represented by the reference numeral  92 . (See FIGS. 2-4 for more detailed views of the present invention.) Removed residual particles may be stored for disposal. A machine controller  96  is preferably a known programmable controller or combination of controllers, which conventionally control all the machine steps and functions described above. 
     The controller  96  is responsive to a variety of sensing devices to enhance control of the machine, and also provides connection of diagnostic operations to a user interface (not shown) where required. 
     As thus described, a reproduction machine in accordance with the present invention may be any of several well known devices. Variations may be expected in specific electrophotographic processing, paper handling and control arrangements without affecting the present invention. However, it is believed that the foregoing description is sufficient for purposes of the present application to illustrate the general operation of an electrophotographic printing machine which exemplifies one type of apparatus employing the present invention therein. 
     Reference is now made to FIGS. 2-5 where the showings are for the purpose of illustrating a preferred embodiment of the invention and not for limiting the same. 
     Referring to FIG. 2 which shows an example of how an elastomer cleaning blade  130  is mounted in a cleaner housing  125 . The path of the toner cleaned from the photoreceptor belt  10  is down the length of the blade and into a transport auger  500 . Because of the angular orientation of the cleaning blade  130  and the poor flow properties of some toners, this example represents a condition where toner flow through the cleaner housing could be of concern. 
     Cleaning blade  130  has a flexible circuit board  210  on a surface of the cleaning blade  130 . Flexible circuit board  210  has a finely spaced electrode array  200  thereon as shown in FIGS. 3 and 4. The typical spacing between electrodes is between  75  and  100  microns. The electrode array  200  has a four phase grid structure consisting of electrodes  202 ,  204 ,  206 , and  208  having a power source and a wave generator  300  operatively connected thereto in the manner shown in order to supply the proper waveform in the appropriate electrode. The traveling wave is generated by alternating voltages of three or more phases applied to the linear array of electrodes placed about the outer periphery of the conveyor. A force F for moving the toner about the conveyor is equal to QEt where Q is the charge on the toner and Et is the tangential field supplied by a multi-phase AC voltage applied to the array of electrodes. 
     Applicants have found that toner cleaned by the tip of a cleaning blade often piles up on top of the blade and the supporting blade holder. This is often not a problem if the architectural location of the cleaner allows gravity to pull the toner pile down the blade surface. However, in many other architectural locations gravity does not assist toner flow and toner transport becomes a problem. The present invention utilizes an electrode array or transport grid in which toner is transported by travelling electric fields from the blade tip to the end of the grid. Where a transport auger  500  at the termination of the transport grid  200 . A waste container (not shown) is located behind the blade to collect the waste. 
     The grid could extend much further to a remote waste container. The grid could also extend back to the developer housing to enable toner reclaim. The blade cleaner shown in FIG. 2 could be positioned at other architectural locations (the photoreceptor belt and blade tipped to the left or right) and still provide good toner transport. Also shown in FIG. 2 is a second transport grid  220  mounted to the right hand side of the entrance hopper into the transport auger. This second transport grid aids toner flow into the auger and prevents toner bridging across the opening to the auger. 
     For some architectural locations of the cleaner (see FIG. 5.) the second transport grid may need to be extended across the housing wall opposite to the cleaning blade and the transport grid on the blade could be eliminated. 
     All of these configurations result in reliable toner flow away from the cleaning blade tip and minimize cleaner subsystem volume. An additional advantage can be gained if the transport grid is extended along the housing at the toner inlet  230  to the cleaner as shown in FIG.  5 . The transport grid can now decrease the amount of toner emissions from the cleaner by capturing and transporting toner clouds and toner droppings back into the cleaner housing. Because of the close spacing of the transport grid to the photoreceptor belt at the toner inlet  230 , toner trying to escape from the housing is more likely to contact the traveling wave grid and be transported back into the cleaner housing. 
     It is, therefore, apparent that there has been provided in accordance with the present invention, a cleaning system that fully satisfies the aims and advantages hereinbefore set forth. While this invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.