Abstract:
A method for in situ replacement of a cartridge for an electrophotographic printer includes providing a photoreceptive member enclosed in a housing where the housing includes a retractable shield. The housing and photoreceptive member is inserted into the printer and the shield is retracted.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Reference is made to commonly-assigned copending U.S. patent application Ser. No. ______ (Attorney Docket No. 96553/NAB), filed herewith, entitled APPARATUS FOR PREVENTING DAMAGE TO A PHOTOCONDUCTOR, by Pitas et al.; U.S. patent application Ser. No. 12/849,044, filed Aug. 3, 2010, entitled METHOD FOR PREVENTING DAMAGE TO A PHOTOCONDUCTOR, by Pitas et al.; and U.S. patent application Ser. No. 12/849,041, filed Aug. 3, 2010, entitled PREVENTING DAMAGE TO A PHOTOCONDUCTOR, by Pitas et al.; the disclosures of which are incorporated herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to electrophotography in general and in particular to a replacement cartridge for an electrophotographic printer. 
       BACKGROUND OF THE INVENTION 
       [0003]    Electrophotographic equipment utilizes sensitive components that must be routinely serviced by either dedicated service personnel or by the end user. Many of these components are easily damaged unless care is exercised during replacement. In some instances, it is considered imprudent to depend upon an individual exercising care as a step in carrying out this critical operation. This is especially important when the risk of error is high, and the cost and machine down-time associated with error is great. 
         [0004]    A primary component requiring frequent replacement within an electrophotographic print engine is the photoreceptive member. The function of the photoreceptor is to provide a means of developing an image and transferring that image to paper. The photoreceptor is coated with photosensitive material which is essential to operation of electrographic printers. The photosensitive material is easily scratched and can be damaged by exposure to ambient light if handled imprudently. This type of damage creates unacceptable image quality defects in the transferred image. 
         [0005]    In close proximity to the photoreceptive member are many components that support the imaging of the photoreceptor. These components can scratch or abrade the photoreceptive member during replacement. There is a need to eliminate the potential for damage to the photoreceptive member. 
       SUMMARY OF THE INVENTION 
       [0006]    Briefly, according to one aspect of the present invention a method for in situ replacement of a cartridge for an electrophotographic printer includes providing a photoreceptive member enclosed in a housing where the housing includes a retractable shield. The housing and photoreceptive member is inserted into the printer and the shield is retracted. 
         [0007]    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 
         [0008]      FIG. 1  is a cross-section of a replacement cartridge according to the present invention. 
           [0009]      FIG. 2  is a cross-section of a replacement cartridge in an electrophotographic printer with a protective mechanism. 
           [0010]      FIG. 3  is a cross-section of a replacement cartridge in an electrophotographic printer with a protective mechanism. 
           [0011]      FIG. 4  is a cross-section of a replacement cartridge in an electrophotographic printer with a protective mechanism. 
           [0012]      FIG. 5  is a cross-section of a replacement cartridge in an electrophotographic printer with a protective mechanism. 
       
    
    
     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 all components necessary to accomplish the task of printing an image on paper. A printer is comprised of various sub-assemblies which perform specific functions. 
         [0015]    An imaging module in the printer consists of components to enable printing of a single color image. Multiple 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 or laser. Toning unit  225 , comprising elements  226  and  227  is used to develop the latent image created by 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 imaging 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. Referring to  FIG. 2 , shown here with a change in form for this invention, a replacement cartridge  200  within imaging module  31  is created consisting of a photoreceptive member  111 , cleaning unit  230 , and charging subsystem  210 . The photoreceptor  206  may be rigid, or non-rigid, organic or non-organic and the form of the photoreceptive member  111 , although shown here in a circular format may be a photoreceptor belt path of any closed shape. These components are assembled into a cartridge and held in place with a plastic housing  233 . Further, a windup shield  240  is applied to the module, which serves to prevent damage to the photoreceptor  206 . The replacement cartridge slides into the electrophotographic printer using guides  232   a  and  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. 
         [0020]    Because of the proximity of subsystems that interface with module  31  and with replacement cartridge  200 , it is necessary to have large areas of the photoreceptive member  111  open during use. During insertion into the print engine, these open, unprotected areas can be damaged either mechanically or by light exposure. Therefore it is necessary to protect the photoreceptive member  111  from damage, either from extraneous light, fingerprints or mechanical scrapes. Many designs use paper as a protection means which is removed prior to insertion into the machine. From the time that paper is removed from a photoreceptive member  111 , and it is inserted into the machine, it is prone to damage. The windup shield  240  is attached to the replacement cartridge housing  233 , and protects from damage, the photoreceptor  206  during the installation process. The windup shield  240  stays in place when the replacement cartridge  200  is installed in the printer. Alternately, if desired the windup shield may be removed and discarded, as dictated by the particular design. 
         [0021]    The windup shield consists of housing  241  and shield  242 . The shield may be clear, translucent or opaque as dictated by the light sensitivity of components being protected. The shield may or may not rest on the entire surface of the photoreceptor  206 . When the cartridge is slid into position the shield  242  is retracted into housing  241  through rotary motion. The windup can be either by turning a manual crank  250  by the installer, or an alternate construction has a torsion spring arrangement and plunger, such that when the plunger is depressed, when the replacement cartridge  200  is installed, a preloaded torsion spring winds the shield  242  into the housing  241 . 
         [0022]    Active drive means may be incorporated. A particular advantage in the arrangement shown is that the action of the windup shield is in the same direction as the motion of the photoreceptive member  111 . The cleaner unit  230  and charger subsystem  210 , therefore have a similar interface during windup as to the photoreceptive member  111  during use. By winding the shield in a similar direction, the windup action may be delayed until the machine is started, with the photoreceptive member acting to help wind up the shield. Winding the shield  242  at the same speed as the photoreceptive member  111  eliminates relative motion between the shield and photoreceptor  206  which reduces scuffing the surface. Also, the photoreceptive member  111  may have a one way clutch incorporated such that the windup causes the photoreceptive member to turn. 
         [0023]      FIG. 3  shows an alternate arrangement, whereas the direction of motion of the rotary shield has been reversed. It may be preferable to reverse the direction of rotation of the windup shield, as determined by the details of a particular design. Also shown is drive  255  and gear  256 . This design as in the previous embodiment may be driven by manual crank  250 , a preloaded torsion spring a drive  255  and gear  256  or by other drive means. 
         [0024]      FIG. 4  shows that the windup shield  240  shown in  FIG. 2  has been replaced with a dual windup shield  245 . The dual windup shield  245  consists of dual shield  243  and housing  241 . The dual shield  243  arrangement has the advantage of allowing certain elements used in the cartridge to remain in contact with the photoreceptor  206  when installed in the replacement cartridge  200 , if required by the particular design. Drive means may be, either by manual crank  250 , torsion spring, drive  255  and gear  256  or by other drive means. For the dual shield arrangement, the rotation direction may be either clockwise or counterclockwise as dictated by the particular design. 
         [0025]    Referring now to  FIG. 5 , the dual shield  243  of  FIG. 4  has overlapping portions providing additional damage protection. Also shown is a rotation of the shield in the opposite direction to the device of  FIG. 4 . 
         [0026]    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 
       [0027]      31  print 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
 
 240  windup shield
 
 241  housing
 
 242  shield
 
 243  dual shield
 
 245  dual windup shield
 
 250  crank
 
 255  drive
 
 256  gear