Abstract:
An apparatus for mounting a cylindrical photoreceptor (206) includes a gudgeon (241) attached to a photoconductor; a stationary mount (242) attached to the photoconductor ; and wherein a diameter of the stationary mount matches a diameter of the photoconductor.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Reference is made to commonly-assigned copending U.S. patent application Ser. No. ______ (Attorney Docket No. 96606/NAB), filed herewith, entitled METHOD FOR MOUNTING A PHOTOCONDUCTOR, by Pitas et al.; the disclosure of which is incorporated herein. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to electrophotography in general and in particular to an apparatus for mounting a photoconductor in an electrophotographic apparatus. 
       BACKGROUND OF THE INVENTION 
       [0003]    The electrophotographic process is used as a means of creating an image on paper or other suitable printing media. The electrophotographic process uses various components assembled into a print engine to enable printing. In order for those components to function correctly they must be mounted within the printer precisely and rigidly. The more precisely the components are mounted, the less correction is necessary for an accurate, well focused image placement on paper. Some components need to be replaced as part of normal operations. During this process, they must be positioned in a proper functional orientation. There is, therefore, a need to accurately locate components relative to a photoreceptive cartridge in a manner which minimizes necessary image registration correction. There is also a need for the process to be repeatable, and which minimizes variation when assemblies are interchanged. 
       SUMMARY OF THE INVENTION 
       [0004]    Briefly, according to one aspect of the present invention an apparatus for mounting a cylindrical photoreceptor includes a gudgeon attached to a photoconductor; a stationary mount attached to the photoconductor; and wherein a diameter of the stationary mount matches a diameter of the photoconductor. 
         [0005]    The invention and its objects and advantages will become more apparent in the detailed description of the preferred embodiment presented below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a cross-section of a replacement cartridge according to the present invention. 
           [0007]      FIG. 2  is a cross-section of a replacement cartridge in an electrophotographic printer. 
           [0008]      FIG. 3  is a perspective view of a replacement cartridge being assembled to a framework. 
           [0009]      FIG. 4  is a detailed view of one end of a photoreceptor member. 
           [0010]      FIG. 5  is a detailed view of an alternate construction of one end of a photoreceptor member. 
           [0011]      FIG. 6  is a detailed view of an alternate construction of one end of a photoreceptor member. 
           [0012]      FIG. 7  is a detailed view of an alternate construction of one end of a photoreceptor member. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The present invention will be directed in particular to elements forming part of, or in cooperation more directly with the apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. 
         [0014]    An electrophotographic printer includes components necessary to print an image on paper. The printer is comprised of various sub-assemblies which perform specific functions. 
         [0015]    An imaging module in the printer consists of components to print a single color image. Multiple imaging modules may be assembled to enable the printing of multiple color images.  FIG. 1  shows details of a typical printing module  31 , which may be assembled with other imaging modules to enable printing multiple colors. 
         [0016]    Primary charging subsystem  210  uniformly electrostatically charges photoreceptor  206  of photoreceptive member  111 , shown in the form of an imaging cylinder. Charging subsystem  210  may include a grid  213  having a selected voltage, or may be in the form of a roller with conductive properties. 
         [0017]    Additional necessary components provided for control may be assembled around the various process elements of the respective printing modules. Meter  211  measures the uniform electrostatic charge provided by charging subsystem  210 , and meter  212  measures the post-exposure surface potential within a patch area of a latent image formed from time to time in a non-image area on photoreceptor  206 . 
         [0018]    Image writer  220  is used to expose photoreceptor  206  and may be a light emitting diode (LED) array or other similar mechanisms. Toning unit  225 , comprising elements  226  and  227  is used to develop the latent image created by image writer  220  on photoreceptor  206 . Cleaning unit  230  removes residual toner from photoreceptor  206  after transfer of the image to a secondary receiver. Other meters and components may be included. 
         [0019]    Within the printing module  31 , periodic replacement of critical components is necessary to ensure proper function. It may be desired to cluster multiple components to enable simultaneous replacement. 
         [0020]    Referring to  FIG. 2 , a replacement cartridge  200  consists of a photoreceptive member  111 , cleaning unit  230 , and charging subsystem  210 . These components are assembled into a cartridge and held in place with a plastic housing  233 . The replacement cartridge slides into the electrophotographic printer with guides  232   a,    232   b.  Guides  232   a  and  232   b  are attached to the printer and help mount and align the replacement cartridge in the proper position. 
         [0021]    Referring now to  FIG. 3  the replacement cartridge is shown oriented to a framework  250  of the printer. The framework  250  is designed to accommodate many subsystems which all depend on the precision of framework features for proper alignment. Within the framework are components that align to the replacement cartridge  200 , whose spacing to the photoreceptor  206  is critical. 
         [0022]    Referring now to  FIG. 4  a photoreceptive member  111  is shown consisting of photoreceptor  206  and gudgeon  241 . The photoreceptor may be a coated rigid tube or may be a rigid tube with a photoreceptor sleeve affixed. The photoreceptive member  111  rotates having gudgeon  241  turning in stationary mount  242 . The stationary mount is fixed to the plastic housing  233  shown in  FIG. 2 . 
         [0023]    The stationary mount  242  is made with a precisely controlled inner and outer diameter. Suitable materials are chosen to enable low torque and long bearing surface life. The gudgeon  241  has precisely controlled bearing surface and outer diameter. The photoreceptor has precisely controlled inner diameter, which the gudgeon  241  presses into, and precisely controlled outer diameter. The construction is designed to provide precise spacing “B” between the outside of the stationary mount  242  and the photoreceptor  206 . If materials with similar thermal expansion characteristics are chosen the spacing change is minimal with temperature change. 
         [0024]    An image writer  220  is maintained at a certain distance from the photoreceptor  206  with critical spacing feature  248 . The spacing feature  248  is precisely located to the image writer  220 , such that the overall spacing C between the writer and photoreceptor  206  is precisely controlled. A similar approach can be used for the toning unit  225 , cleaning unit  230 , charging subsystem  210  and other features requiring precise location. The means of accurate, well controlled spacing between the photoreceptor surface and electrophotographic elements ensure a well focused image and proper function of the electrophotographic printer. 
         [0025]    Because many of the subsystems are not part of the replacement cartridge  200 , it is necessary to retract them from engagement with the stationary mount  242  prior to replacing the cartridge. It is convenient to make the outer diameter of the stationary mount similar in diameter to the photoreceptor to limit the refraction distance needed for clearance to spacing feature  248 . For some systems this may not be a factor so a more appropriate diameter according to the particular design may be chosen. 
         [0026]    Referring now to  FIG. 5  an alternate construction to the device of  FIG. 4  is shown. In this case the stationary mount has been replaced with a large bearing.  FIG. 6  shows another construction showing a small bearing  243  pressed within a spacing ring. 
         [0027]    Referring now to  FIG. 7  is shown an alternate construction which limits error in spacing caused by clearance between the stationary mount  242  and the gudgeon  241 . A preferred low cost construction is to use a non-rolling element bearing for the stationary mount  242 . Manufacturing tolerance of the stationary mount and gudgeon require designed in clearance to ensure assemble ability. In addition, dissimilar materials are subject to thermal expansion and for plastic construction. Moisture absorption is a factor, which require additional consideration. The actual running clearance will vary from the design clearance by the part size and by the thermal and moisture absorption factors. The deviation between actual and design clearance from assembly to assembly creates variation in spacing between photoreceptor  206  and image writer  220 . 
         [0028]      FIG. 7  shows a means to decrease the variation between assemblies. Stationary mount  242  and gudgeon  241  have been modified with mating tapers. Adjustable collar  244  is used to adjust the relative axial position of the stationary mount to minimize clearance between the gudgeon  241  and stationary mount  242 . If the same materials are used for gudgeon and stationary mount, thermal and moisture absorption are not a concern. The adjustable collar  244  can be on a screw thread which is tightened and backed off slightly to allow minimal running clearances. If dissimilar materials are used, or compensation to zero running clearance is desired for systems with similar material selection, a spring  245  is used between adjustable collar  244  and stationary mount  242 . The addition of a spring  245  allows running at no clearance and also allows axial expansion to compensate for thermal and moisture absorption when dissimilar materials are used. 
         [0029]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention. 
       PARTS LIST 
       [0000]    
       
           31  printing module 
           111  photoreceptive member 
           200  replacement cartridge 
           206  photoreceptor 
           210  charging subsystem 
           211  meter 
           212  meter 
           213  grid 
           220  image writer 
           225  toning unit 
           226  element 
           227  element 
           230  cleaning unit 
           232   a  guide 
           232   b  guide 
           233  plastic housing 
           241  gudgeon 
           242  stationary mount 
           243  small bearing 
           244  adjustable collar 
           245  spring 
           248  spacing feature 
           250  framework