Patent Publication Number: US-11046097-B2

Title: Media retraction

Description:
BACKGROUND 
     A printer may use sheets of media from a stack. As a top sheet of the media is drawn or “picked” from the stack, a next-to-top sheet (or sheets) may be inadvertently drawn with the top sheet. If left uncleared, such next sheet(s) may result in a sheet misfeed during a subsequent pick cycle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating an example of a printing system. 
         FIG. 2  illustrates an example of a portion of a media transport assembly for a printing system. 
         FIG. 3  illustrates an example of a portion of a media retraction system. 
         FIG. 4  illustrates an example of a portion of the media retraction system of  FIG. 3 . 
         FIG. 5  is a cross-sectional view from the perspective of line  5 - 5  of  FIG. 4 . 
         FIG. 6  illustrates an example of a portion of a loadstop shaft of the media retraction system of  FIG. 3 . 
         FIG. 7  illustrates an example of a loadstop paddle of the media retraction system of  FIG. 3 . 
         FIGS. 8A, 8B, 8C, 8D, 8E  illustrate examples of positions of a media retraction system in retracting media. 
         FIGS. 9A, 9B, 9C  are flow diagrams illustrating an example of a method of retracting media in a printing system. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. 
       FIG. 1  illustrates an example of a printing system, such as inkjet printing system  10 . Inkjet printing system  10  includes a fluid ejection assembly, such as printhead assembly  12 , and a fluid supply assembly, such as printing fluid supply  14 . In the illustrated example, inkjet printing system  10  also includes a carriage assembly  16 , a print media transport assembly  18 , and an electronic controller  20 . 
     Printhead assembly  12  includes at least one printhead or fluid ejection device which ejects drops of printing fluid or other fluid through a plurality of orifices or nozzles  13 . In one example, the drops are directed toward a medium, such as print media  19 , so as to print onto print media  19  as printhead assembly  12  and print media  19  are moved relative to each other. Print media  19  includes, for example, any type of suitable sheet material, such as paper, card stock, transparencies, Mylar, fabric, and the like, packaging material, or other printable material. 
     Printing fluid supply  14  supplies printing fluid to printhead assembly  12 . In one example, printhead assembly  12  and printing fluid supply  14  are housed together in an inkjet or fluid-jet print cartridge or pen. In another example, printing fluid supply  14  is separate from printhead assembly  12  and supplies printing fluid to printhead assembly  12  through an interface connection, such as a supply tube. 
     Carriage assembly  16  positions printhead assembly  12  relative to print media transport assembly  18  and print media transport assembly  18  positions print media  19  relative to printhead assembly  12 . Thus, a print zone  17  is defined adjacent to nozzles  13  in an area between printhead assembly  12  and print media  19 . Print media transport assembly  18  may include, for example, a variety of guides, rollers, wheels, etc. for the handling and/or routing of print media  19  through inkjet printing system  10 , including transporting, guiding, and/or directing print media  19  to and/or away from print zone  17 . In one example, print media transport assembly  18  includes a media retraction system, as identified at  22 , for retracting misfed media within inkjet printing system  10 . 
     In one implementation, electronic controller  20  communicates with printhead assembly  12 , printing fluid supply  14 , carriage assembly  16 , and print media transport assembly  18 . Electronic controller  20  receives data  21  from a host system, such as a computer, and may include memory for temporarily storing data  21 . Data  21  represents, for example, a document and/or file to be printed. As such, data  21  forms a print job for inkjet printing system  10  and includes print job commands and/or command parameters. In one example, electronic controller  20  provides control of printhead assembly  12  including timing control for ejection of printing fluid drops from nozzles  13 . As such, electronic controller  20  defines a pattern of ejected printing fluid drops which form characters, symbols, and/or other graphics or images on print media  19 . Timing control and, therefore, the pattern of ejected printing fluid drops, is determined by the print job commands and/or command parameters. 
       FIG. 2  illustrates an example of a portion of a print media transport assembly, such as print media transport assembly  18  ( FIG. 1 ), for a printing system, such as inkjet printing system  10  ( FIG. 1 ). In one implementation, the print media transport assembly includes a chassis  40 , a media tray (input tray)  60  for supporting a media stack, a pick system  80 , including pick tires  82 , for drawing or “picking” a sheet of media from the media stack, and a media retraction system  100 , including loadstop levers or paddles  140 , for gathering and returning mis-picked or misfed media to the media stack. 
     In one implementation, media tray  60  is an upright tray having an incline or slope. In other implementations, media tray  60  may be horizontal or include other slopes. The media stack includes media, such as print media  19  ( FIG. 1 ), and, in one example, includes, but is not limited to, sheet paper. The media stack is defined as an amount of media disposed within media tray  60 . In one example, the printing system is a “top-in, front-out” printer, with media being loaded generally vertically in media tray  60  and being output through a front of the printing system after being fed through the printing system. 
     In the example illustrated in  FIG. 2 , media retraction system  100  includes two spaced loadstop paddles  140 . Loadstop paddles  140  may be disposed on a single axle or shaft supported within chassis  40 . While two loadstop paddles  140  are illustrated, more or fewer loadstop paddles  140  may be utilized. 
     As further described herein, loadstop paddles  140  move or transition between a plurality of positions including, for example, a non-obstructing position, a plurality of gathering or retracting positions, and an obstructing position. 
     In the non-obstructing position, loadstop paddles  140  are moved out of the media path, thereby allowing picked media to enter the media path. In one implementation, loadstop paddles  140  arrive at the non-obstructing position by, for example, rotating away from media tray  60  in a direction indicated by arrow  102  and rotating, in one example, under plate or surface  42  of chassis  40 . 
     In the gathering or retracting positions, loadstop paddles  140  are moved toward media tray  60  (i.e., toward the media stack) to “gather” or “retract” misfed media back into media tray  60 . In one implementation, loadstop paddles  140  move through the gathering or retracting positions by, for example, rotating toward media tray  60  in a direction indicated by arrow  104 . 
     In the obstructing position, loadstop paddles  140  are further moved toward media tray  60  (i.e., toward the media stack) and, in one example, fully extended into the media path to push the misfed media back into the media stack and, in one example, compress the media stack. In one implementation, loadstop paddles  140  arrive at the obstructing position by, for example, further rotating toward media tray  60  in the direction indicated by arrow  104 . In one implementation, loadstop paddles  140  remain in the obstructing position, and thereby prevent media from entering the media path, until a pick cycle is started. 
     In one implementation, movement of loadstop paddles  140  away from media tray  60  (for example in the direction indicated by arrow  102 ) may be in response to rotation of a supporting shaft in one direction, and movement of loadstop paddles  140  toward media tray  60  (for example in the direction indicated by arrow  104 ) may be in response to rotation of the supporting shaft in an opposite direction. 
       FIG. 3  illustrates an example of a portion of a media retraction system, such as media retraction system  100 , for a printing system, such as inkjet printing system  10  ( FIG. 1 ). In one example, media retraction system  100  includes a loadstop shaft  120  and, as described above, loadstop levers or paddles  140 . 
     In one example, loadstop shaft  120  includes an axis  122  and is mounted for rotation about axis  122  in, for example, chassis  40  ( FIG. 2 ). In one example, loadstop shaft  120  includes a lever arm  124  and gear teeth  126  which interact or mate with a cam surface or teeth to rotate or position loadstop shaft  120  and loadstop paddles  140 , as described below. 
     In one example, loadstop shaft  120  includes spaced pockets or channels  128  for loadstop paddles  140 . In one example, and as illustrated, one pocket or channel  128  is provided toward an end of loadstop shaft  120  to support one loadstop paddle  140  and another pocket or channel  128  is provided intermediate of the ends of loadstop shaft  120  to support another loadstop paddle  140 . In one example, respective pockets or channels  128  are defined by spaced supports or flanges  130  which extend from loadstop shaft  120 . In one implementation, supports or flanges  130  extend orthogonal or tangential to loadstop shaft  120  such that pockets or channels  128  are oriented orthogonal to and radially offset from axis  122  of loadstop shaft  120 . 
     As further described below, loadstop paddles  140  are supported within pockets or channels  128  for rotation with loadstop shaft  120  and are supported within pockets or channels  128  for sliding relative to loadstop shaft  120  including, more specifically, sliding relative to supports or flanges  130 , as indicated by double arrow  106 . In one example, loadstop paddles  140  include respective ends or tips  142  to contact and catch or gather media, as described below. In one example, tips  142  have a serrated surface to contact and catch a leading edge of the media. 
       FIGS. 4, 5, 6, 7  illustrate examples of a portion of media retraction system  100 , including a portion of loadstop shaft  120  with one pocket or channel  128  (of multiple pockets or channels  128 ) and a respective loadstop paddle  140  (of multiple loadstop paddles  140 ). In one example, pocket or channel  128  is defined or formed by spaced supports or flanges  130  extended orthogonal to axis  122  of loadstop shaft  120 . As such, spaced supports or flanges  130  define or form opposite sides of pocket or channel  128  such that pocket or channel  128  is open orthogonal to loadstop shaft  120 . In one example, and as further described below, loadstop paddle  140  slides within pocket or channel  128  relative to supports or flanges  130 , as indicated by double arrow  106 . 
     In one example, pocket or channel  128  and loadstop paddle  140  include mating features to retain and guide loadstop paddle  140  within pocket or channel  128 . In one implementation, the mating features include a slot  144  formed in a side of loadstop paddle  140 , and a post or tab  132  and a post or tab  134  both protruded from an adjacent side of pocket or channel  128  including, more specifically, an adjacent side of a corresponding support or flange  130  of pocket or channel  128 . As such, in one example, post or tab  132  and post or tab  134  both slide within slot  144  to retain and guide loadstop paddle  140  within pocket or channel  128 , as described below. 
     In one example, slot  144  is formed within or along an outer surface of a side of loadstop paddle  140  and open outward to the side of loadstop paddle  140 , and tab  132  and tab  134  are both extended or projected inward from an inner surface of a side of pocket or channel  128  including, more specifically, an inner surface or side of a corresponding support or flange  130  of pocket or channel  128 . In one example, slot  144  is formed within or along both sides of loadstop paddle  140 , and post or tab  132  and post or tab  134  are both extended or projected from both sides of pocket or channel  128  including, more specifically, both supports or flanges  130  of pocket or channel  128 . 
     In one implementation, slot  144  is a non-linear slot and includes a non-linear profile to impart or establish a non-linear path of loadstop paddle  140  relative to loadstop shaft  120  including, more specifically, relative to pocket or channel  128  of loadstop shaft  120 . As such, with contact of media, as described below, loadstop paddle  140  is slidable relative to and about axis  122  of loadstop shaft  120  so as to follow a curved, non-linear path, as represented by dashed line  107 . Thus, in one example, loadstop paddle  140  is constrained to an “engineered path” or “spline” that is similar to a curve with a floating pivot. 
     In one example, loadstop paddle  140  is biased to extend beyond supports or flanges  130  such that tip  142  of loadstop paddle  140  extends radially away from axis  122  of loadstop shaft  120 , in the direction indicated by arrow  108 . In one implementation, loadstop paddle  140  is biased by a spring  150  positioned between loadstop shaft  120  and loadstop paddle  140 . In one example, spring  150  is positioned between a post or protrusion  136  of shaft  120  and a post or protrusion  146  of loadstop paddle  140 . 
       FIGS. 8A, 8B, 8C, 8D, 8E  illustrate examples of states or positions of a media retraction system, such as media retraction system  100 , for catching or gathering a sheet of media and retracting or returning the sheet of media to a media stack. In one example, in addition to loadstop shaft  120  and loadstop paddles  140 , media retraction system  100  includes a cam gear member  160  to establish or achieve various states or positions of media retraction system, including, more specifically, various states or positions of loadstop shaft  120  and loadstop paddles  140  for catching or gathering a sheet of media and retracting or returning the sheet of media to a media stack, including before, during, and after catching or gathering the sheet of media and retracting or returning the sheet of media to the media stack. As described above, loadstop paddles  140  are slidably mounted within pockets or channels  128  and are biased in the direction indicated by arrow  108 . 
     In one implementation, cam gear member  160  includes teeth  162  around, for example, a periphery thereof for driving or rotating cam gear member  160 , and includes a series of cam surfaces  164  and gear teeth  166  for interacting with lever arm  124  and gear teeth  126  of loadstop shaft  120  ( FIG. 3 ). As such, rotation of cam gear member  160  imparts a sequence of different rotations of loadstop shaft  120  and movements of loadstop paddles  140  as supported by loadstop shaft  120 , including rotation of loadstop paddles  140 . 
     In one example, as illustrated in  FIG. 8A , loadstop shaft  120  is positioned (e.g., has been rotated) such that loadstop paddles  140  including, more specifically, tips  142  of loadstop paddles  140  are in the non-obstructing position (e.g., below plate or surface  42  of chassis  40  ( FIG. 2 )). As such, a first or top sheet of media from the media stack may be drawn or “picked” and loaded or “fed” into the media path by, for example, pick system  80  ( FIG. 2 ). 
     In one example, as the top sheet of media is “picked” from the media stack, a next-to-top sheet  62  (or multiple next-to-top sheets) may be drawn, at least partially, into the media path by, for example, frictional forces between the top sheet and next-to-top sheet  62 . In one example, next-to-top sheet  62  is supported at least partially by, or extended at least partially over, plate or surface  42  of chassis  40  ( FIG. 2 ). In the examples of  FIGS. 8A, 8B, 8C, 8D, 8E , next-to-top sheet  62  is only partially illustrated to permit illustration of media retraction system  100 . 
     In one example, as illustrated in  FIG. 8B , to initiate a sequence of media retraction system  100  in retracting next-to-top sheet  62  and returning next-to-top sheet  62  to the media stack, cam gear member  160  is rotated. In one example, as cam gear member  160  is rotated, as indicated by arrow  110 , gear teeth  166  of cam gear member  160  engage and mesh with gear teeth  126  of loadstop shaft  120  such that loadstop shaft  120  is rotated about axis  122 , as indicated by arrow  112 , and loadstop paddles  140  are rotated into the media path. In one implementation, cam gear member  160  is rotated in one direction (e.g., counter-clockwise in the orientation illustrated) such that loadstop shaft  120  (and loadstop paddles  140 ) is rotated in an opposite direction (e.g., clockwise in the orientation illustrated). 
     In one example, as loadstop paddles  140  are rotated into the media path, loadstop paddles  140  including, more specifically, tips  142  of loadstop paddles  140 , contact next-to-top sheet  62 , including a bottom surface and/or leading edge of next-to-top sheet  62 . In one example, as loadstop paddles  140  contact next-to-top sheet  62 , loadstop paddles  140  slide within pockets or channels  128  against the biasing force produced, for example, by spring  150  ( FIG. 4 ). As such, loadstop paddles  140  retract within pockets or channels  128 , as indicated by arrow  114 . In one example, sliding and retracting of loadstop paddles  140  within pockets or channels  128  helps to absorb energy of the contact of loadstop paddles  140  with next-to-top sheet  62  and minimize damage to next-to-top sheet  62  including, for example, damage to a leading edge of next-to-top sheet  62 . 
     In one example, as illustrated in  FIG. 8C , to continue the sequence of media retraction system  100  in retracting next-to-top sheet  62  and returning next-to-top sheet  62  to the media stack, cam gear member  160  is further rotated. In one example, as cam gear member  160  is further rotated, as indicated by arrow  110 , gear teeth  166  of cam gear member  160  continue to engage and mesh with gear teeth  126  of loadstop shaft  120  such that loadstop shaft  120  is further rotated about axis  122 , as indicated by arrow  112 . In one example, as loadstop shaft  120  is further rotated, loadstop paddles  140  including, more specifically, tips  142  of loadstop paddles  140  catch or contact the leading edge of next-to-top sheet  62 . In one example, as loadstop paddles  140  catch or contact the leading edge of next-to-top sheet  62 , loadstop paddles  140  continue to slide within pockets or channels  128  against the biasing force produced, for example, by spring  150  ( FIG. 4 ). As such, loadstop paddles  140  further retract within pockets or channels  128 , as indicated by arrow  114 . 
     In one example, as illustrated in  FIG. 8D , to continue the sequence of media retraction system  100  in retracting next-to-top sheet  62  and returning next-to-top sheet  62  to the media stack, cam gear member  160  is further rotated. In one example, as cam gear member  160  is further rotated, as indicated by arrow  110 , gear teeth  166  of cam gear member  160  continue to engage gear teeth  126  of loadstop shaft  120  such that loadstop shaft  120  is further rotated about axis  122 , as indicated by arrow  112 . In one example, as loadstop shaft  120  is further rotated, loadstop paddles  140  push next-to-top sheet  62  back into the media stack. In one example, as loadstop paddles  140  push next-to-top sheet  62  back into the media stack, loadstop paddles  140  slide within pockets or channels  128  as a result of the biasing force produced, for example, by spring  150 . As such, loadstop paddles extend from pockets or channels  128 , as indicated by arrow  116 . 
     In one example, as illustrated in  FIG. 8E , to finish the sequence of media retraction system  100  in retracting next-to-top sheet  62  and returning next-to-top sheet  62  to the media stack, cam gear member  160  is further rotated. In one example, as cam gear member  160  is further rotated, as indicated by arrow  110 , gear teeth  166  of cam gear member  160  continue to engage gear teeth  126  of loadstop shaft  120  such that loadstop shaft  120  is further rotated about axis  122 , as indicated by arrow  112 . In one example, as loadstop shaft  120  is further rotated, loadstop paddles  140  further push next-to-top sheet  62  back into the media stack. In one example, as loadstop paddles  140  further push next-to-top sheet  62  back into the media stack, loadstop paddles  140  continue to slide within pockets or channels  128  as a result of the biasing force produced, for example, by spring  150  ( FIG. 4 ). As such, loadstop paddles further extend from pockets or channels  128 , as indicated by arrow  116 . 
     In one example, after next-to-top sheet  62  is returned to the media stack, cam gear member  160  holds loadstop paddles  140  in a position to obstruct the media path and prevent media from entering the media path, until a subsequent pick cycle is started. In one example, prior to the subsequent pick cycle, cam gear member  160  is further rotated in the direction indicated by arrow  110  such that gear teeth  166  of cam gear member  160  no longer engage gear teeth  126  of loadstop shaft  120 . As such, loadstop shaft  120  rotates in a direction opposite the direction indicated by arrow  112  whereby loadstop paddles  140  are retracted to the non-obstructing position, as illustrated, for example, in  FIG. 8A . 
       FIGS. 9A, 9B, 9C  are flow diagrams illustrating an example of a method  200  of retracting media in a printing system, as illustrated, for example, in  FIGS. 8B, 8C, 8D, 8E . 
     In one example, as illustrated in  FIG. 9A , at  202 , method  200  includes rotating a loadstop shaft, such as loadstop shaft  120 , having a loadstop paddle supported thereon, such as loadstop paddle  140 , about an axis, such as axis  122 , as illustrated, for example, in  FIGS. 8B, 8C, 8D, 8E . 
     As such, at  204 , method  200  includes contacting media, such as next-to-top sheet  62 , with the loadstop paddle, such as loadstop paddle  140 , during the rotating, as illustrated, for example, in  FIGS. 8B, 8C, 8D, 8E . 
     As such, at  206 , method  200  includes sliding the loadstop paddle, such as loadstop paddle  140 , relative to and about the axis of the loadstop shaft, such as axis  122  of loadstop shaft  120 , with the contacting of the media, as illustrated, for example, in  FIGS. 8B, 8C, 8D, 8E . 
     In one example, as illustrated in  FIG. 9B , at  208 , with method  200 , rotating the loadstop shaft, for example, at  202 , includes rotating the loadstop shaft, such as loadstop shaft  120 , in a first direction, such as that indicated by arrow  112 , as illustrated, for example, in  FIGS. 8B, 8C . 
     As such, at  210 , with method  200 , sliding the loadstop paddle, for example, at  206 , includes sliding the loadstop paddle, such as loadstop paddle  140 , in a second direction opposite the first direction, such as that indicated by arrow  114 , against a biasing force acting on the loadstop paddle, as illustrated, for example, in  FIGS. 8B, 8C . 
     In one example, as illustrated in  FIG. 9C , at  212 , with method  200 , rotating the loadstop shaft, for example, at  202 , includes further rotating the loadstop shaft, such as loadstop shaft  120 , in the first direction, such as that indicated by arrow  112 , as illustrated, for example, in  FIGS. 8D, 8E . 
     As such, at  214 , with method  200 , sliding the loadstop paddle, for example, at  206 , further includes sliding the loadstop paddle, such as loadstop paddle  140 , in the first direction, such as that indicated by arrow  116 , by the biasing force acting on the loadstop paddle, as illustrated, for example, in  FIGS. 8D, 8E . 
     With a media retraction system as disclosed herein, an inadvertently “picked” or “fed” sheet of media from a media stack may be cleared from a media path by catching or gathering the sheet of media and retracting or returning the sheet of media to the media stack. By clearing such mis-picked or misfed media, a sheet misfeed during a next pick cycle may be avoided. 
     More specifically, with a media retraction system as disclosed herein, supporting the loadstop paddles such that the loadstop paddles slide and are biased relative to the loadstop shaft helps to absorb energy of the contact of the loadstop paddles with the sheet being retracted, thereby helping to minimize damage to the retracted sheet including, for example, a leading edge of the retracted sheet. 
     In addition, with a media retraction system as disclosed herein, supporting the loadstop paddles such that the loadstop paddles slide and are guided with a non-linear profile helps vary the position of the loadstop paddles relative to the sheet being retracted. For example, the non-linear profile helps to initially position the loadstop paddles, including, more specifically, the tips of the loadstop paddles, at an increased or inclined angle of contact to the sheet being retracted so as to better “catch” or gather the sheet being retracted (e.g.,  FIG. 8A ). In addition, as the loadstop paddles continue to gather the sheet being retracted, the non-linear profile helps to subsequently position the loadstop paddles, including, more specifically, the tips of the loadstop paddles, at an orthogonal angle of contact to the sheet being retracted (e.g., generally perpendicular to the leading edge of the sheet) so as to effectively transmit torque of the loadstop paddles without damaging the media (e.g.,  FIG. 8B ). In this regard, the non-linear profile may be “tuned” or “engineered” such that the torque associated with gathering mis-picked media may be more evenly distributed throughout the rotation of the loadstop paddles. The non-linear profile also permits the loadstop paddles to more easily slide within the supporting pockets or channels in the event the loadstop paddles start to bind when contacting the sheet being retracted. 
     Furthermore, with a media retraction system as disclosed herein, including a gear tooth interface or interaction between the cam gear member and the loadstop shaft helps to provide a rotationally constant speed relative to the mating surfaces such that torque of the cam gear member is more evenly distributed through the rotation of the cam gear member and more efficiently transmitted to the loadstop shaft. 
     Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein.