Abstract:
A device for sealing a magnetic roll to a developer housing includes a plastic retainer having side walls that are spring loaded with a felt seal adhesively positioned within the side walls. The spring loaded side walls of the plastic retainer help hold the felt seal in place and facilitates ease of installation onto the magnetic rolls.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This disclosure relates to a developer housing, and more particularly, to a seal for a magnetic developer housing.  
         [0002]     In the process of electrophotographic printing, a photoconductive member is uniformly charged and exposed to a light image of an original document. Exposure of the photoconductive member records an electrostatic latent image corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive surface, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles attracted from the carrier granules to form a toner powder image on the photoconductive member that corresponds to the informational areas contained within the original document. This toner powder image is subsequently transferred to a copy sheet and permanently affixed thereto in image configuration.  
         [0003]     In electrophotographic printing machines, magnetic rolls are frequently employed in the developing station and the cleaning station. Typically, the magnetic roll includes a stationary magnet having a rotating tube positioned concentrically thereabout. At the developer station, a developer material of magnetic carrier granules having toner particles adhering triboelectrically thereto is attracted to the tube by the magnetic field generated by the magnetic roll. The tube surface is usually roughened so that the frictional force between the developer material and the tube causes the developer material to rotate with the tube. The developer material is advanced by the tube to a position closely adjacent the electrostatic latent image recorded on the photoconductive member. At the cleaning station, a layer of carrier granules adheres to the tube and moves therewith. As the layer of carrier granules pass closely adjacent to the photoconductive member, residual toner particles are attracted to the layer of carrier granules and move therewith away from the photoconductive member. In this way, residual toner particles are cleaned from the photoconductive member. A copier employing a magnetic roll is shown in U.S. Pat. No. 4,823,102 issued Apr. 18, 1989 to Abraham Cherian et al.  
         [0004]     It is critical for performance of the printer that the developer housing in which the magnetic roll is supported is sealed with respect to the magnetic roll in order to prevent toner from escaping into the insides of the printer. This has been accomplished in the past, but with excessive cost. For example, rare earth magnetic seals have been used successfully, but they are too expensive. Felt seals have been used to seal the magnetic roll to the developer housing, however, they present installation, adhesive shelf life, component contamination from adhesives, ineffective adhesives and ineffective adhesive problems which allow the magnetic roll to spin in the seal out of position with respect to the photoconductive member.  
         [0005]     Obviously, there is still a need, in magnetic developer housings for an inexpensive magnetic roll seal.  
         [0006]     Accordingly, a device for sealing a magnetic roll to a developer housing is disclosed that answers the above-mentioned problem by including a plastic retainer having side walls that are spring loaded with a felt seal positioned within the said walls. The spring loaded side walls of the plastic retainer hold the felt seals in place to facilitate installation onto the magnetic rolls.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The foregoing and other features of this disclosure will be apparent and easily understood from a further reading of the specification, claims and by reference to the accompanying drawings in which like reference numerals refer to like elements and wherein:  
         [0008]      FIG. 1  is a schematic elevational view of a typical electrophotographic printing machine that includes a magnetic developer housing that employs an improved magnetic developer housing seal.  
         [0009]      FIG. 2  is an exploded, partial schematic isometric view depicting a magnetic roll, seal and developer housing cover plate; and  
         [0010]      FIG. 3  is a schematic side view showing a magnetic roll sealed to a face plate of a magnetic developer housing. 
     
    
       [0011]     While this disclosure will be described hereinafter 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  
       [0012]     For a general understanding of the features of the present disclosure, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to identify identical elements.  
         [0013]     Referring to  FIG. 1  of the drawings, an original document is positioned in a document handler  27  on a raster input scanner (RIS) indicated generally by reference numeral  28 . The RIS contains document illumination lamps, optics, a mechanical scanning drive and a charge couple device (CCD) array. The RIS captures the entire original document and converts it to a series of raster scan lines. This information is transmitted to an electronic subsystem (ESS) which controls a raster output scanner (ROS) described below.  
         [0014]      FIG. 1  schematically illustrates an electrophotographic printing machine which generally employs a photoconductive belt  10 . Preferably, the photoconductive belt  10  is made from photoconductive material coated on a ground layer, which, in turn, is coated on an anti-curl backing layer. Belt  10  moves in the direction of arrow  13  to advance successive portions sequentially through the various processing stations disposed about the path of movement thereof. Belt  10  is entrained about stripping roller  14 , tensioning roller  20  and drive roller  16 . As roller  16  rotates, it advances belt  10  in the direction of arrow  13 .  
         [0015]     Initially, a portion of the photoconductive surface passes through charging station A. At charging station A, a corona generating device indicated generally by the reference numeral  22  charges the photoconductive belt  10  to a relatively high, substantially uniform potential.  
         [0016]     At an exposure station, B, a controller or electronic subsystem (ESS), indicated generally by reference numeral  29 , receives the image signals representing the desired output image and processes these signals to convert them to a continuous tone or grayscale rendition of the image which is transmitted to a modulated output generator, for example the raster output scanner (ROS), indicated generally by reference numeral  30 . Preferably, ESS  29  is a self-contained, dedicated minicomputer. The image signals transmitted to ESS  29  may originate from a RIS as described above or from a computer, thereby enabling the electrophotographic printing machine to serve as a remotely located printer for one or more computers. Alternatively, the printer may serve as a dedicated printer for a high-speed computer. The signals from ESS  29 , corresponding to the continuous tone image desired to be reproduced by the printing machine, are transmitted to ROS  30 . ROS  30  includes a laser with rotating polygon mirror blocks. The ROS will expose the photoconductive belt to record an electrostatic latent image thereon corresponding to the continuous tone image received from ESS  29 . As an alternative, ROS  30  may employ a linear array of light emitting diodes (LEDs) arranged to illuminate the charged portion of photoconductive belt  10  on a raster-by-raster basis.  
         [0017]     After the electrostatic latent image has been recorded on photoconductive surface  12 , belt  10  advances the latent image to a magnetic development unit  38  that includes a housing  40  at station C, where toner is electrostatically attracted to the latent image using commonly known techniques. The latent image attracts toner particles from the carrier granules forming a toner powder image thereon.  
         [0018]     With continued reference to  FIG. 1 , after the electrostatic latent image is developed, the toner powder image present on belt  10  advances to transfer station D. A print sheet  48  is advanced to the transfer station D, by a sheet feeding apparatus,  50 . Preferably, sheet feeding apparatus  50  includes a nudger roll  51  which feeds the uppermost sheet of stack  54  to nip  55  formed by feed roll  52  and a retard roll  53 . Feed roll  52  rotates to advance the sheet from stack  54  into vertical transport  56 . Vertical transport  56  directs the advancing sheet  48  of support material into the registration transport  120  which, in turn, advances the sheet  48  past image transfer station D to receive an image from photoconductive belt  10  in a timed sequence so that the toner powder image formed thereon contacts the advancing sheet  48  at transfer station D. Transfer station D includes a corona generating device  58  which sprays ions onto the back side of sheet  48 . This attracts the toner powder image from photoconductive surface  12  to sheet  48 . The sheet is then detacked from the photoreceptor by corona generating device  59  which sprays oppositely charged ions onto the back side of sheet  48  to assist in removing the sheet from the photoreceptor. After transfer, sheet  48  continues to move in the direction of arrow  60  by way of belt transport  62 , which advances sheet  48  to fusing station F.  
         [0019]     Fusing station F includes a fuser assembly indicated generally by the reference numeral  70  which permanently affixes the transferred toner powder image to the copy sheet. Preferably, fuser assembly  70  includes a heated fuser roller  72  and a pressure roller  74  with the powder image on the copy sheet contacting fuser roller  72 . The pressure roller is cammed against the fuser roller to provide the necessary pressure to fix the toner powder image to the copy sheet. The fuser roll is internally heated by a quartz lamp (not shown). Release agent, stored in a reservoir (not shown), is pumped to a metering roll (not shown). A trim blade (not shown) trims off the excess release agent. The release agent transfers to a donor roll (not shown) and then to the fuser roll  72 .  
         [0020]     The sheet then passes through fuser  70  where the image is permanently fixed or fused to the sheet. After passing through fuser  70 , a gate  80  either allows the sheet to move directly via output  84  to a finisher of stacker, or deflects the sheet into the duplex path  100 , specifically, first into single sheet inverter  82  here. That is, if the sheet is either a simplex sheet or a completed duplex sheet having both side one and side two images formed thereon, the sheet will be conveyed via gate  80  directly to output  84 . However, if the sheet is being duplexed and is then only printed with a side one image, the gate  80  will be positioned to deflect that sheet into the inverter  82  and into the duplex loop path  100 , where that sheet will be inverted and then fed to acceleration nip  102  and belt transport  110 , for recirculation back through transport station D and fuser  70  for receiving and permanently fixing the side two image to the backside of that duplex sheet, before it exits via exit path  84 .  
         [0021]     After the print sheet is separated from photoconductive surface  12  of belt  10 , the residual toner/developer and paper fiber particles adhering to photoconductive surface  12  are removed therefrom at cleaning station E. Cleaning station E includes a rotatably mounted fibrous brush in contact with photoconductive surface  12  to disturb and remove paper fibers and a cleaning blade to remove the non-transferred toner particles. The blade may be configured in either a wiper or doctor position depending on the application. Subsequent to cleaning, a discharge lamp (not shown) floods photoconductive surface  12  with light to dissipate any residual electrostatic charge remaining thereon prior to the charging thereof for the next successive imaging cycle.  
         [0022]      FIG. 2  shows a partial, exploded isometric view of magnetic developer unit  38  that includes a faceplate  41  that is a portion of magnetic developer housing  40 . Faceplate  41  includes seal seats  42  that support spring loaded toner seal retainers  90 . A magnetic roll  45  fits into seal retainer  90  of magnetic developer housing  40  such that toner dispensed from the housing onto magnetic roll  45  will not escape through the ends of the magnetic developer housing. Seal retainers  90  are positioned at the ends of magnetic roll  45 . Heretofore, not only were there problems with installation of felt seal retainer onto the magnetic roll, but the felt seal retainers would sometimes have ineffective adhesives adhering them to a support and spinning of the magnetic roll would cause the seal retainer to spin out of positions, and thus allowing magnetic toner to escape into the interior of the printer and affecting copy quality and printer performance.  
         [0023]     Plastic toner retainer seal  90  that is used to prevent toner from escaping through the ends of magnetic roll  45  and to minimize installation of magnetic roll onto the toner retainer seal, as shown in  FIG. 3 , comprises a felt seal member  91  securely positioned within a plastic retainer  95  that retains felt seal  91  by spring action that is provided by the plastic retainer members  96 ,  97 ,  98  and  99 . Felt seal  51  is statically slopped into plastic retainer  55 . Side plastic springs  96 ,  97  and  98  prevent the seal  91  from lifting out of retainer  95 , and lip  99  on the upper end of retainer  95  prevents the seal from spinning out of position. The plastic retainer can be molded into any shape to fit any design parameter. A suitable adhesive could also be used to attach seal member  91  to plastic retainer  95 . It should be noted that the end of plastic retainer  91  has a vertical wall  99 , adapted such that, with the aid of the adhesive and the vertical wall, rotating of the seal member by magnetic roll  45  is restricted. In addition, along with the spring loaded sides of plastic retainer  95 , the adhesive and vertical wall allow for consistent and ease of insertion of the retainer  91  into developer housing  40  during assembly.  
         [0024]     It should now be understood that an improved, less expensive, spring loaded plastic toner seal retainer has been disclosed that prevents toner from escaping through the ends of magnetic rolls positioned to receive toner from a magnetic developer housing. A felt seal is retained within the plastic retainer by spring action that is provided by the plastic retainer.  
         [0025]     While the invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined herein.