Patent Publication Number: US-8118506-B2

Title: Idler roller assembly for printing apparatus

Description:
BACKGROUND 
     Disclosed is an idler roller assembly for use with a printing apparatus. 
     In a typical printing apparatus, media such as paper will be stored in a tray or trays. When printing occurs, typically the paper or media will be pulled from the tray and fed through a printing feed path. Typically the paper will be driven through the printing feed path by rollers assemblies, each of which may include a drive roller assembly and an idler roller assembly. Where the printer is an electrophotographic printer, the roller assemblies will drive the paper along the printing feed path to printing elements such as a photoreceptor, fuser, and the like. Where the printer is an ink jet printer, the roller assemblies will drive the paper along the printing feed path to printing elements such as an inkjet printhead, a print assembly, a pressure roll, and the like, and eventually to an output tray. 
     The idler roller assemblies are often made of a lightweight and low cost material, such as plastic. The idler roller assembly typically includes a shaft with one or a pair of idler rolling elements. The idler rolling elements are aligned with drive roller elements to form nips for driving the paper or other media. To ensure control of the media and to minimize wear of the drive roller elements, the idler rolling elements must maintain substantial parallelism to the shaft of the idler assembly. 
     SUMMARY 
     According to aspects of the embodiments, there is provided an idler roller assembly for a printing apparatus. The idler rolling assembly includes a shaft, at least one idler rolling element connected to the shaft, the at least one idler rolling element having an inner surface and an outer surface and being connected to the shaft at a substantially center portion of the idler rolling element, the at least one idler rolling element being cylindrically shaped and having an axis substantially parallel to an axis of the shaft, and at least one radial control movement element connected to the shaft, the at least one radial control movement element having a radius selected to leave a predetermined gap between an outer edge of the at least one radial control movement element and the inner surface of the idler rolling element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a schematic view of a printing apparatus. 
         FIG. 2  illustrates a diagram of an idler roller assembly. 
         FIG. 3  illustrates a diagram of an idler roller assembly. 
         FIG. 4  illustrates a diagram of an idler roller assembly. 
         FIG. 5  illustrates a diagram of an idler roller assembly. 
     
    
    
     DETAILED DESCRIPTION 
     While the present invention will be described in connection with preferred embodiments 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. 
     The embodiments include an idler roller assembly for a printing apparatus. The idler roller assembly includes a shaft, at least one idler rolling element connected to the shaft, the at least one idler rolling element having an inner surface and an outer surface and being connected to the shaft at a substantially center portion of the idler rolling element, the at least one idler rolling element being cylindrically shaped and having an axis substantially parallel to an axis of the shaft, and at least one radial control movement element connected to the shaft, the at least one radial control movement element having a radius selected to leave a predetermined gap between an outer edge of the at least one radial control movement element and the inner surface of the at least one idler rolling element. 
     The embodiments further include an idler roller assembly for a printing apparatus, which includes a shaft, a plurality of idler rolling elements connected to the shaft, the plurality of idler rolling elements each having an inner surface and an outer surface, the plurality of idler rolling elements having an axis substantially parallel to an axis of the shaft, and a plurality of radial control movement elements connected to the shaft, the plurality of radial control movement elements each having a radius selected to leave a predetermined gap between an outer edge of the radial control movement element and the inner surface of each of the plurality of idler rolling elements. 
     In as much as the art of electrophotographic printing is well known, the various elements employed in the  FIG. 1  printing machine will be shown schematically and their operation described briefly with reference thereto. Various other printing machines could also be used including an inkjet or other type of printer, and this is only an example of a particular printing machine that may be used with the invention. 
       FIG. 1  illustrates a printing apparatus  110 , also known as an image production apparatus, which may be an electrophotographic apparatus, in greater detail. The printing apparatus  110  includes media trays  112 , which store media such as paper for printing or copying. Any number of media trays  112  may be used. The media may be driven from the media trays  112  along a printing feed path by one or more roller assemblies, each of which may include a drive roller assembly  114  and an idler roller assembly  116 , to a photoreceptor  124  and a fuser  126 , for example. After printing, the media may exit from the printing apparatus through the assembly  128  and the printing exit tray  130 . 
     The printing apparatus  110  may also include a feed tray  132 . The feed tray  132  can feed media to be scanned into the printing apparatus  110 , where it may be scanned by scanning device  118 , for example. Scanning device  118  may be a duplex scanning device, such as full-width array bars or the like. Media from feed tray  132  does not follow the entire printing feed path, but instead may exit from the printing feed path at scanner feed path  120 , where it may be directed to the scanner output tray  122 , which may be formed as an integral part of a cover of the printing apparatus  110 . Thus, media to be scanned from the scanner feed tray  132  may not proceed to the photoreceptor  124  or to the fuser  126 . 
       FIG. 2  illustrates an idler roller assembly  210 , which may correspond to the idler roller assembly  116 , in greater detail. The idler roller assembly  210  may include a shaft  212 , and one or more idler rolling elements  214 . The idler rolling elements  214  are typically cylindrically shaped, and are connected to the shaft  212  at a substantially central portion of the idler rolling elements  214  in lengthwise direction. 
     When pressure is applied to the idler rolling element  214  at either end away from the lengthwise central portion, the idler rolling element is movable towards the shaft  212 , while the central portion is held a uniform distance from the shaft  212 , by a connection such as a snap-fit connection inside the idler rolling element  214 . For example, if pressure is put on the idler rolling element  214  in the location of and in the direction of arrow A, that portion of the idler rolling element  214  can move towards the shaft  212  in the direction of arrow A. Likewise, if pressure is put on the idler rolling element  214  in the location of and in the direction of arrow B, that portion of the idler rolling element  214  can move towards the shaft  212  in the direction of arrow B. This may result in the idler rolling element  214  becoming misaligned with the shaft  212 . The shape of the shaft  212  shown is just one possible shape. 
     The drive roller assembly  116  includes drive rolling elements that align with the rolling elements  214  to form a nip, through which the media is drawn. If one or more of the idler rolling elements  214  becomes substantially misaligned with the shaft  212 , it will cause undesirable wear on the drive rolling elements of the drive roller assembly  116 . 
     Accordingly, the present invention includes at least one radial movement control element  316  for controlling the movement of each idler rolling element  314  in a radial direction in a perpendicular direction towards the shaft  312 , as part of the idler rolling assembly  310 . The radial movement control element  316  may be attached to the shaft  312 , and may be formed from a same material as the shaft  312 , such as plastic or the like. The idler rolling elements  314  have an axis that is substantially parallel to an axis of the shaft  312 . 
     The radial movement control element  316  may be disposed adjacent to an inner end portion of each of the idler rolling elements  314  in a lengthwise direction towards a center of shaft  312 . Further, the radial movement control element  316  may be disposed at one end only of each idler rolling element  314 , or there may be a radial movement control element  316  disposed at each end of each idler rolling element  314 . 
     When the radial movement control element  316  is disposed at one end of each idler rolling element  314 , it may be advantageous to dispose the radial movement control element  316  adjacent to an inner end of each idler rolling element, towards a center of shaft  312 , and not on an end  318  of idler rolling element  314 . Such placement may be advantageous when assembling the idler roller assembly  310 , such that the radial movement control element  316  could be attached to or preformed with shaft  312  before sliding the idler rolling element  314  on the shaft  312 . 
     The radial movement control element  316  may have a predetermined diameter so as to leave a predetermined gap between an outer edge of the radial movement control element  316  and an inner edge of the idler rolling element  314 . The gap may be selected to limit an amount of movement of the idler rolling element  314  towards the radial movement control element  316 . This will keep the idler rolling element substantially parallel with the shaft  312 . 
     The radial movement control element  316  may have a predetermined diameter of approximately 14 mm, and the gap between the inner surface of the idler rolling element and the radial movement control element  316  may be approximately 1 mm. Any predetermined gap size could be used. 
     The radial movement control element  316  may be circular in shape. Alternatively, the radial movement control element  316  may be any shape that limits movement of the idler rolling element  314  by a substantially equal amount in all radial directions. For example, the radial movement control element  316  could be shaped to have arms extending radially outward from the shaft  312 , to leave a substantially equal gap between the end of each arm and an inner edge of the idler rolling element  314 . 
       FIG. 4  illustrates an idler roller assembly  410 , which includes a shaft  412 , idler rolling elements  414 , and radial movement control elements  416  having a gap  418  between an outer edge of the radial movement control element  416  and an inner edge of the idler rolling element  414 . In the  FIG. 4  embodiment, the radial movement control elements  416  are disposed at each end of each idler rolling element  414 , so that there are two radial movement control elements  416  for each idler rolling element  414 . 
       FIG. 5  illustrates an enlarged side view of an idler roller assembly  510 , which includes idler rolling elements  520  and  550 , and radial movement control element  530 . The radial movement control element  530  has a radius selected to leave the predetermined gap between the outer edge of the radial movement control element  530  and an inner edge of the idler rolling element  520 . 
     It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different embodiments. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.