Abstract:
In one embodiment, a media slitter includes first and second rotary slitter blades and first and second pairs of rotatable media transport rollers positioned along opposite first and second sides of a media path. Each pair of transport rollers is configured to engage the print media simultaneously with the other pair of transport rollers and move the print media along the media path. A first one of the media transport rollers in each pair of transport rollers is positioned adjacent to and outboard from a corresponding one of the slitter blades on an axis of rotation common to the first transport rollers and the slitter blades.

Description:
BACKGROUND 
       [0001]    In some photo printers, the edges of the paper on which a photograph has been printed are trimmed as the photograph is discharged from the printer. For example, when printing 5″×7″ size photographs on 8″ wide photographic paper, a ½″ wide strip is trimmed from each edge of the paper. The star wheel discharge paper drive mechanism used in some inkjet photo printers, however, may not always have sufficient traction to securely drive the photographs along the discharge path if there are significant skewing forces acting on the paper, such as may occur when trimming the edges of the paper. 
     
    
     
       DRAWINGS 
         [0002]      FIG. 1  is a block diagram illustrating one embodiment of an inkjet printer. 
           [0003]      FIG. 2  is an elevation and partial section view illustrating one embodiment of a media path for an inkjet photo printer. 
           [0004]      FIGS. 3 and 4  are perspective views illustrating one embodiment of a print media slitter positioned along a printer&#39;s discharge path for trimming the edges from the print media. The media slitter is shown in a disabled position in  FIG. 3  and in the enabled position in  FIG. 4 . 
           [0005]      FIGS. 5 and 6  are more detailed perspective views of the slitter shown in  FIGS. 3 and 4  with the drive gears omitted to better illustrate some features of the slitter. 
           [0006]      FIG. 7  is a perspective view illustrating an alternative embodiment in which the media slitter is adjustable to vary the width of the edge trimmed from the print media. 
       
    
    
     DESCRIPTION 
       [0007]    Embodiments of the new media slitter were developed to improve traction and minimize skew forces on photographs as the edges of the photograph are trimmed while the photograph is discharged from a photo printer. Embodiments, however, are not necessarily limited to trimming photographs or to the discharge path in a printer. Thus, the embodiments shown in the figures and described below are examples. Other embodiments are possible and nothing in the following description should be construed to limit the scope of the disclosure, which is defined in the Claims. 
         [0008]      FIG. 1  is a block diagram illustrating an inkjet printer  10  that includes an array  12  of printheads  14 , an ink supply  16 , a print media transport system  18  and an electronic printer controller  20 . Printer  10  illustrates one example of an environment for implementing embodiments of the new media slitter. Printhead array  12  in  FIG. 1  represents generally one or more printheads  14  and the associated mechanical and electrical components for ejecting drops of ink or other marking material on to a sheet or continuous web of paper or other print media  22 . In operation, printer controller  20  selectively energizes the ink ejector elements in a printhead, or group of printheads, in the appropriate sequence to eject ink on to media  22  in a pattern corresponding to the desired printed image. 
         [0009]    Printhead array  12  and ink supply  16  may be housed together as a single unit or they may comprise separate units. Printhead array  12  may be a mostly stationary, larger unit (with or without supply  16 ) spanning the width of print media  22 . Alternatively, printhead array  12  may be a smaller unit that is scanned back and forth across the width of media  22  on a moveable carriage. Media transport system  18  advances print media  22  lengthwise past printhead array  12 . For a stationary printhead array  12 , media transport  18  may advance media  22  continuously past the array  12 . For a scanning printhead array  12 , media transport  18  may advance media  22  incrementally past array  12 , stopping as each swath is printed and then advancing media  22  for printing the next swath. Controller  20  may receive print data from a computer or other host device  24  and, when necessary, process that data into printer control information and image data. Controller  20  controls the movement of the operative components of media transport system  18 . And, as noted above, controller  20  is electrically connected to printhead array  12  to energize the printhead ejector elements to eject ink drops on to media  22 . By coordinating the relative position of array  12  and media  22  with the ejection of ink drops, controller  20  produces the desired image on media  22  according to the print data received from host device  24 . 
         [0010]      FIG. 2  is an elevation and partial section view illustrating an example media path  26  for an inkjet photo printer, such as printer  10  shown in  FIG. 1 , that includes a media edge slitter  28  according to an embodiment of the disclosure.  FIGS. 3 and 4  are perspective views illustrating media edge slitters  28  in more detail. (Only one edge slitter  28  is visible in  FIG. 1 .) Media edge slitters  28  are shown in a disabled position in  FIGS. 2 and 3 , out of media path  26 , and in the enabled position in  FIG. 4 , in media path  26 . Referring first to  FIG. 2 , photo paper or other print media  30  transported along media path  26  follows a semicircular path from an input zone  32  on path  26  through a print zone  34  to a discharge zone  36 . A set of first media transport rollers  38  and  40  form a nip  42  for gripping and moving print media  30  along media path  26  through input zone  32  to print zone  34 . Print zone  34  is depicted generally as including an ink cartridge or other printhead array  44  and a transport roller  46  bearing against an idler arm  48  to form a nip  50  that moves media  30  past printhead array  44  to discharge zone  36 . The side edges of print media  30  may be trimmed, as described in more detail below, at discharge zone  36  by engaging edge slitter  28 . The leading edge of print media  30  may be trimmed, or media  30  cut to desired lengths, by engaging a cross cut slitter  52 . Although cross cut slitter  52  is depicted as including a cutting wheel  54  and an anvil  56 , any suitable cutting mechanism may be used. 
         [0011]      FIGS. 5 and 6  are more detailed perspective views of media edge slitters  28  with the drive gears omitted to better illustrate some features of slitter  28 . Referring now to  FIGS. 3-6 , print media  30  is moved through discharge zone  36  on transport belts  58  driven by one or more in a set of drive drums  60 . A belt/drum drive for discharging media  30  is just one example of a suitable media transport configuration. Other configurations are possible. For example, a star wheel configuration might also be used. A media edge slitter  28  is positioned along each side of media path  26  in discharge zone  36 . Each edge slitter  28  includes a pair or rotary slitter blades  62  and  64  positioned with respect to one another such that print media  30  passing between each pair of blades  62  and  64  is slit, as shown in  FIGS. 4-6 . Each edge slitter  28  also includes a pair of transport rollers  66  and  68  positioned with respect to one another for engaging print media  30  at a nip  70  and advancing media  30  along path  26 . Each transport roller  66  is mounted to a shaft  72 . Shafts  72  define an axis of rotation  74  common to both shafts  72 . Alternatively, rollers  66  may be mounted to a single shaft (not shown) that extends fully across media path  26 . Each transport roller  68  is mounted to a shaft  76 . Shafts  76  define an axis of rotation  78  common to both shafts  76 . 
         [0012]    Each shaft  72  and  76  is mounted to a forked swing arm  80  through a bushing or other suitable bearing (not shown) that allows shafts  72 ,  76  to rotate freely relative to swing arm  80 . Shafts  72  are mounted to swing arm forks  82  and shafts  76  are mounted to swing arm forks  84 . Each rotary slitter blade  62  is mounted to a corresponding transport roller  66  and/or to a corresponding shaft  72  such that blades  62  rotate about axis of rotation  74 . Thus, axis  74  is common to blades  62 , rollers  66  and shafts  72 . Each rotary slitter blade  64  is mounted to a corresponding transport roller  68  and/or to a corresponding shaft  76  such that blades  64  rotate about axis of rotation  78 . Thus, axis of rotation  78  is common to blades  64 , rollers  68  and shafts  76 . Each shaft  76  is fitted with a gear  86  that engages a drive gear  88  on drum shaft  90  when each edge slitter  28  is in the enabled position shown in  FIG. 4 . Gears  86  and  88  are omitted from  FIGS. 5 and 6  to better illustrate other features of slitters  28 . A deflector  92  extending from swing arm  80  deflects each edge  94  that has been trimmed from print media  30  down away from media path  26 , into a waste bin (not shown) for example. 
         [0013]    When edge trimming is desired, edge slitters  28  are rotated down on swing arms  80  at the direction of controller  20  ( FIG. 1 ) before the leading edge of media  30  reaches slitters  28  from a disabled position out of media path  26 , shown in  FIG. 3 , to the enabled position in media path  26 , shown in  FIG. 4-6 . The use of a swing arm  80  to disable and enable slitters  28  allows slitter blades  62  and  64  and rollers  66  and  68  to remain fully engaged at nip  70  all times, thus avoiding the challenges encountered in opening and closing nip  70  on a stationary slitter (a slitter that is always in the media path). As shown in  FIG. 4 , each edge slitter gear  86  engages a drum gear  88  when edge slitters  28  are in the engaged position to drive edge slitter transport rollers  68  against rollers  66  at nip  70 . When edge trimming is no longer desired, and the trailing edge of media  30  has cleared slitters  28 , edge slitters  28  may be rotated back up to the disabled position out of media path  26 . 
         [0014]    Print media  30  moving through discharge zone  36  is pulled into and through nip  70  to advance media  30  along media path  26  as edges  94  are trimmed off media  30 . One or both transport rollers  66  and  68  may be formed with an elastomeric or other suitable friction enhancing surface to help grip print media  30  at nip  70 . Since both media edges  94  are engaged simultaneously at nips  70  and rollers  66  and  68  are rotating the same speed on the same axes of rotation  74  and  78 , there are few if any skew forces acting on media  30  as it passes through slitters  28 . Rollers  66  and  68  engaging media  30  drive the trimmed edges  94  forward into deflectors  92 . And, because rollers  66  and  68  engage print media  30  at edges  94 , at the outer margins where there has been no printing, there is little risk of rollers  66 ,  68  slipping at nip  70  or smearing ink. 
         [0015]    Although other configurations could be used, it is expected that in most applications gears  86 ,  88  and edge slitter transport rollers  66 ,  68  will be configured to advance media  30  at the same speed as transport belts  28 . Also, while two sharpened blades  62  and  64  are shown for each slitter  28 , other cutting mechanisms could be used. For example, it may be desirable in some applications to use only one sharpened blade bearing against a dull blade or a blunt rotary anvil to slit media  30 . 
         [0016]    In an alternative embodiment shown in  FIG. 7 , edge slitters  28  may be adjusted laterally along a shaft  96  mounting each pivot arm  80  to vary the width of edge  94  trimmed from media  30 , as indicated by arrow  98 . In  FIG. 7 , each slitter  28  is positioned outboard from the position shown in  FIG. 4  so that edge  94  trimmed from media  30  is narrower by about ½, for example. 
         [0017]    The present disclosure has been shown and described with reference to the foregoing exemplary embodiments. It is to be understood, however, that other forms, details and embodiments may be made without departing from the spirit and scope of the disclosure which is defined in the following claims.