Abstract:
A shield may be provided over a printer developer roll, adjacent to a doctor blade, to reduce toner dusting and toner accumulations. The shield may slightly conform to the curvature of the developer roll in some embodiments. As a result, toner accumulations on surfaces which the customer must touch may be reduced.

Description:
BACKGROUND 
       [0001]    This relates generally to reducing dusting of components proximate to a developer roll. 
         [0002]    In some cases, printer components may be covered with a layer of toner dust. This toner dust originates from a variety of sources. Users noticing the accumulation of toner dust may believe that the equipment is not operating correctly. 
         [0003]    Toner particles on the developer roll surface are sensitive to airflow magnitude and direction. If the airflow pushing force on toner particles exceeds the toner particles&#39; electrostatic binding force to the developer roll, then the toner particles become airborne from the developer roll&#39;s surface. This phenomenon may be referred to as toner dusting, toner spray, or toner accumulation. 
         [0004]    Historically, toner formulations and their corresponding electrostatic parameters were optimized for resistance to airflow dispersal. If the operating space allowed for additional optimization, then print quality and general electrophotographic performance may then be addressed. 
         [0005]    In many cases, the customer must remove and replace various components within the printer. In addition, the customer may be called on to clear paper jams or to perform printer maintenance. In the course of doing these activities, toner accumulation results in considerable messiness. Customers become frustrated with stray toner accumulations, because toner transfers to their clothes, documents, and the office environment. 
         [0006]    In addition, print quality defects may be correlated to toner dusting or accumulation. Print quality defects such as background, light print, and large toner leaks may be caused by toner dusting. In addition, paper jams may be increased due to paper treeing, folded paper corners, and dirty paper corners. 
         [0007]    Thus, it would be desirable to reduce the toner accumulation or dusting within printers. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a toner shield and developer roll in accordance with one embodiment of the present invention; 
           [0009]      FIG. 2  is a cross-sectional view taken generally along the line  2 - 2  in  FIG. 1  in accordance with one embodiment of the present invention; 
           [0010]      FIG. 3  is an end view taken from the left end of the embodiment shown in  FIG. 1  in accordance with one embodiment of the present invention; 
           [0011]      FIG. 4  is a partial, exploded, perspective view of the left side of one embodiment of the present invention; 
           [0012]      FIG. 5  is a partial, perspective view from the left side of the embodiment shown in  FIG. 1  in accordance with one embodiment of the present invention; 
           [0013]      FIG. 6  is a partial, exploded, perspective view of the right side of one embodiment of the present invention; 
           [0014]      FIG. 7  is a partial, perspective view from the right side of the embodiment shown in  FIG. 1  in accordance with one embodiment of the present invention; and 
           [0015]      FIG. 8  is a depiction of a printer in accordance with one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Referring to  FIG. 1 , a toner shield  20  may be positioned on a developer roller  12  to reduce toner dusting as the developer roll rotates. The developer roll  12  rotation causes rotation against a doctor blade  28 . As a result, toner dusting may occur on the doctor blade  28 , as well as other surfaces. 
         [0017]    Referring to  FIG. 2 , the shield  20  conforms to or circumferentially follows the curvature of the roll  12  to reduce the tendency of toner particles to accumulate and to be blown about the printer environment. Most directly, the shield  20  shields the doctor blade  28  from toner accumulations. 
         [0018]    In some embodiments of the present invention, the shield  20  may be secured to upstanding tabs on other printer components. Easy installation may be achieved by securing one arm  16  to a tab and then snapping the snap connector  36  on the other arm  24  to another upstanding tab to quickly, releasably secure the shield  20  to the printer. 
         [0019]    The shield  20  includes a pair of lengthwise extending ribs  22  and  26 . These ribs may be useful in strengthening the lengthwise extent of the shield  20 . Without the ribs the shield strength may be too weak and it might bow into or away from the developer roll  12 . The angles chosen for the ribs  22  and  26 , in some embodiments, allow easy tooling for manufacturing the shields. The molding tool may be pulled away from the shield, parallel to the flanges, so that the ribs assist in the molding process. Geometry constraints may arise from the photoconductor drum location and the cartridge top shutter. 
         [0020]    The arm  16  may have an extension  21  ( FIG. 3 ) and a radially, inwardly directed extension  30 . The extension  30  covers a printer contact  32  on the developer roll  12 . The shield extension&#39;s geometry may create a space for the electrical contact to attach to the developer roll  12 . If the contact  32  were uncovered, some of the developer roll&#39;s surface may cause increased toner spray. Thus, by covering the contact  32 , toner spray can be reduced. 
         [0021]    At the end of the developer roll, a gap G ( FIG. 2 ) smaller than 1 millimeter may exist between the developer roll and the shield  20  in some embodiments. Another extension  23  covers the developer roll  12  end area proximate the gap G, above the developer shaft  14 , and this extension  23  may contact the developer roll  12  bearing (not shown). This small extension  23  may block another airflow path between the developer roll  12  and the shield  20  via the gap G. 
         [0022]    Referring to  FIGS. 4 and 5 , in accordance with one embodiment, the arm  16  and its holes  34  and  35  may be used to secure the shield  20  to other printer components such as a printer housing or a developer tube  108 . To this end, an anchor  42  may extend upwardly from the tube  108  of the printer  50  ( FIG. 8 ). The anchor  42  may have through holes  44 . The parallel pins  102  and  106  of a U-shaped upstop  38  may pass through the through the holes  44  in the anchor and the through holes  34  and  35  in the arm  16 . The upstop  38  is secured by spring catches  104  on each pin  102 ,  106 . Thus, a snap connection may be established. 
         [0023]    An anchor  48 , shown in  FIGS. 6 and 7 , extending from the developer tube  108 , may be engaged in a friction or press fit with the arm  24 . In such case, a male/female securement may occur. The upstop  114  is U-shaped and includes a pair of extending, parallel pins  120  and  122 . The pins  120 ,  122  engage the openings  116  and  118  in the anchor  48  in a press fit. The body of the U-shaped upstop  114  includes an opening  112  and an upper edge  113 . 
         [0024]    The arm  24  includes an outwardly directed tapered pin  130 . The latch  36  includes a spring arm portion  122  punctuated in a downwardly extending catch  110 . Thus, when the shield  20  is pressed into the upstop  114 , the pin  130  engages and passes through the opening  112  in the upstop  114  at the same time the latch  36  latches on the upper edge  113  of the upstop  114 . It does this because of the tapered leading edge  111  of the catch  110  which springs the leaf spring arm portion  122  upwardly so that the catch  110  then may spring back down and secure on the outside side of the upstop  114  after the catch  110  moves past the edge  113 . 
         [0025]    In this position, better shown in  FIG. 7 , the pins  120  and  122  engage the anchor  48  in a press fit connection. At the same time, the pin  130  extends through the upstop  114  and onto the anchor  48 . The catch  110  is latched over the upper edge  113  of the upstop  114 . Thus, the upstop  114  is latched onto the anchor  48  by the pin  130  and the pins  122  and  120 , which sandwich the anchor  48 . As a result, the shield  20  may be readily removed from and secured to the rest of the printer housing. 
         [0026]    Referring now to  FIG. 8 , the major components of a laser printer are shown in diagrammatic view, in which the laser printer is generally designated by the reference numeral  50 . A removable and replaceable electrophotographic (EP) process cartridge is provided, generally designated by the reference numeral  70 . This process cartridge  70  includes a new toner supply, photoconductive (PC) drum  72 , developer roll  12 , and a doctor blade  82 . The EP process cartridge can contain enough toner for up to 25,000 prints, although smaller sized process cartridges also are available that can only print up to 7,500 prints. 
         [0027]    Laser printer  50  also includes a charge rollers  74  and a transfer roller  76 . The preferred charge rollers  74  have an operating life time of at least 250,000 prints, and perhaps as many as 300,000 prints. In a preferred laser printer manufactured by Lexmark International Inc., the charge roller is replaced as part of a maintenance kit, which also includes a new fuser  40  and paper path rollers. The preferred laser printer will provide a message to the user when a “maintenance count” reaches 250,000 (representing 250,000 prints) by displaying a message on the operator panel for the user to see that it is time to have a maintenance kit installed. 
         [0028]    Major portions of the paper pathway  45  for the laser printer  50  are also illustrated in  FIG. 8  which allows paper to be supplied from a paper tray (not shown) or from a manually-fed paper input. As the paper (or other type of print media) approaches the print engine, the pathways merge at a final input roller set  60 , and the paper pathway continues at  75  until the paper reaches the photoconductive drum  72  at the print engine stage. 
         [0029]    After the paper has had toner applied at the photoconductive drum and transfer roller nip, the paper continues along a pathway  48  to a fuser  40 , which includes a hot roller  84  and a backup roller  86 . As the paper exits the fuser, the paper pathway can be diverted in different directions, for example, along a pathway  58 , or along a pathway  51  through rollers  54  and  52 . A laser/top shutter  90  may also be provided. 
         [0030]    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. 
         [0031]    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.