Abstract:
Rollers or drums of a printer may be separated to prevent damage from continued contact, for example, during shipping. In some embodiments, operation of at least one of the rollers or drums during normal printer operation de-activates the separator. For example, the separator may rotate from a first position, in which it maintains a separation, to a second inactive position where the separator allows the two components to contact for a normal operation.

Description:
BACKGROUND  
       [0001]     This invention relates generally to printers and, specifically, to devices for separating the rollers thereof prior to actual use.  
         [0002]     Generally, in electrophotographic printers it is desirable to separate various rollers and drums. For example, some rollers and drums will chemically attack other rollers and drums when maintained in unmoved contact for long periods of time, especially at higher temperature and humidity conditions. This chemical attack may result in defects in a printed page. In other cases, one roller may end up being softer than another roller and may develop flat spots over time.  
         [0003]     The time period involved for such damage varies with the chemistry and environment but may sometimes be on the order of six to eight weeks. Frequently, the shipping and shelf life of a product prior to application and use at the end customer exceeds this period. Moreover, the uncontrolled temperatures during shipment can accelerate the chemical reaction.  
         [0004]     To avoid these types of problems, electrophotographic products are generally shipped with various rollers separated from each other with customer removable separating devices. Those devices may be made of plastic, paper, or other materials. During the unpacking and set up of the product, the customer is instructed to remove these separating devices and dispose of or recycle them. The product will not function correctly if these devices are not removed.  
         [0005]     One place where such a separator may be utilized is between a charge roll and a photoconductor drum. Generally, in use, the charge roll is spring loaded against the photoconductor drum. A removable separating device fits on each end of the charge roll, holding it away from the drum. The two ends of the separator are connected by a handle or strap to make sure that both ends are removed by the customer.  
         [0006]     Thus, there is a need for better ways to maintain the separation between various rollers and drums prior to actual use of electrophotographic devices. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a cross-sectional depiction of one embodiment of an electrophotographic printer;  
         [0008]      FIG. 2  is an enlarged, cross-sectional view of one embodiment of the present invention prior to use; and  
         [0009]      FIG. 3  is an enlarged, cross-sectional view corresponding to  FIG. 2  in the ready to use configuration in accordance with one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0010]     Referring now to the drawings and, more particularly, to  FIG. 1 , there is shown one embodiment of an electro-photographic device  10  in which embodiments of the present invention may be applied. Of course the present invention is in no way limited to any specific printer design and may be applicable to a variety of different printer arrangements.  
         [0011]     The device  10  includes laser print heads  12 ,  14 ,  16 , and  18 , a black toner cartridge  20 , a magenta toner cartridge  22 , a cyan toner cartridge  24 , a yellow toner cartridge  26 , photoconductive drums  28 ,  30 ,  32 , and  34 , an intermediate transfer belt  36 , and a controller  37 . In one embodiment, the controller may be a combination of application specific integrated circuits, microprocessors, and firmware suited to the tasks of printing documents.  
         [0012]     Each of the laser print heads  12 ,  14 ,  16 , and  18  projects a respective laser beam  38 ,  40 ,  42 , and  44  off a respective one of the polygonal mirrors  46 ,  48 ,  50 , and  52 . As each of the polygonal mirrors  46 ,  48 ,  50 , and  52  rotates, it scans a respective one of the reflected beams  38 ,  40 ,  42 , and  44  in a scan direction, perpendicular to the plane of  FIG. 1 , across a respective one of the photoconductive drums  28 ,  30 ,  32 , and  34 .  
         [0013]     Each of the photoconductive drums  28 ,  30 ,  32 , and  34  may be negatively charged, for example, to approximately −1000 volts, and is subsequently discharged to a lower level, such as approximately −300 volts, in the areas of the peripheral surface that are impinged by a respective one of the laser beams  38 ,  40 ,  42 , and  44 .  
         [0014]     During each scan of a laser beam across the photoconductive drum, each photoconductive drum  28 ,  30 ,  32 , and  34  is continuously rotated, for example, in a clockwise direction, in a process direction indicated by the arrow  54 . The scanning of the laser beams  38 ,  40 ,  42 , and  44  across the peripheral surface of the photoconductive drums is cyclically repeated, thereby discharging the areas of the peripheral surfaces on which the laser beams impinge.  
         [0015]     The toner in each of the toner cartridges  20 ,  22 ,  24 , and  26  is negatively charged and is transported upon the surface of a developer roll  80  and biased, for example, to approximately −600 volts. Thus, when the toner for the cartridges  20 ,  22 ,  24 , and  26  is brought into contact with the respective one of the photoconductive drums  28 ,  30 ,  32 , and  34 , the toner is attracted to and adheres to the portions of the peripheral surfaces of the drums that have been discharged to the lower voltage, say −300 volts, by the laser beams.  
         [0016]     As the belt  36  rotates in the direction indicated by the arrow  56 , the toner from each of the drums  28 ,  30 ,  32 , and  34  is transferred to the outside surface of the belt  36 . As a print medium, such as paper, travels along the path  58 , the toner is transferred to the surface of the print medium and nip  62 .  
         [0017]     Referring to  FIG. 2 , a fixed roller, such as a photoconductive drum  28 , may rotate in the direction R. Prior to application and use, the drum  28  may be held in a separated position from a charge roll  25 , for example. A separator  200  is responsible for maintaining the charge roll  25  and the drum  28  in a fixed spacing. While an embodiment is illustrated involving the maintenance of a separation between a fixed roller, such a photoconductive drum, and a spring loaded roller, such as a charge roll  25 , other rollers and drums may use separators  200  as well.  
         [0018]     The separator  200  may have a closed complex shape, including a first end  204 , which rests against the drum  28 . The first end  204  may be finger shaped and may be connected to a convex portion  210 . The convex portion  210  has a larger radius of curvature than charge roll  25 . A second convex portion  212  has a smaller radius of curvature than charge roll  25 . The distance from the center of the axle  215  about which the separator rotates to the surface of portion  210  is larger than the radius of charge roll  25 , and the distance from the center of the axle  215  to the surface of portion  212  is smaller than the radius of charge roll  25 .  
         [0019]     A handle  206  couples the portions  204  and  212 . The handle  206  includes an upstanding section coupled to a U-shaped portion  214  which journals the axle  215  of the charge roll  25  in one embodiment.  
         [0020]     In use, the spring  208  biases the charge roll  25  against the photoconductive drum  28 . Prior to use, for example during shipping, the drum  28  and the roll  25  may be separated by the separator  200 . The separation is achieved by the larger radius of the portion  210 , held in position by the finger-shaped first end  204 .  
         [0021]     When the printer is operated, the photoconductive drum  28  rotates in the direction of the arrow R. This rotation of the drum  28  causes clockwise rotation of the separator  200  to the position shown in  FIG. 3 . In other words, the rotation of the drum  28  causes the portion  210  to act like a roller and to rotate approximately 90° to the position shown in  FIG. 3 .  
         [0022]     The rotation of the separator  200  ends when the portion  212  is juxtaposed from the drum  28 . Due to its smaller radius of curvature, the portion  212  ends up being spaced away from the drum  28 . The rotation of the separator  200  in the direction indicated by the arrow S is arrested by the stop  202 . In this position, a spring  208  presses the charge roll  25  against the drum  28 .  
         [0023]     In some embodiments, the separation is automatically eliminated at the right time—the time when the printer is being operated. As a result, there is no need for the user to be forced to remember to remove, not only one separator, but both separators between each pair of separated components.  
         [0024]     While it typically may not be necessary, if for any reason it is thereafter desired to re-separate the drum  28  and roll  25 , all that needs to be done is to rotate the handle portion  206  back to the position shown in  FIG. 2 , immediately reestablishing the desired separation. For example, this re-separation may be done before shipment or storage.  
         [0025]     In some embodiments of the present invention, a separator may be less expensive than conventional separators. Moreover, the separator may be easily snapped onto the shaft of the moveable roller. Also, in some cases, no customer action or intervention is required. Likewise, nothing need be discarded and the separator is available for future use if ever needed. In some embodiments, the friction between the U-shaped portion  214  of the separator  200  and the axle  215  of the spring loaded roll  25  may be sufficient to maintain the separator in the position shown in  FIG. 3  without moving, rattling, or shaking.  
         [0026]     In some embodiments, two separators can be used on each of two opposed ends of two rollers or drums to be separated.  
         [0027]     References throughout this specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation encompassed within the present invention. Thus, appearances of the phrase “one embodiment” or “in an embodiment” are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be instituted in other suitable forms other than the particular embodiment illustrated and all such forms may be encompassed within the claims of the present application.  
         [0028]     While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.