Patent Publication Number: US-2020299087-A1

Title: Sheet transport device, image reading device, and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2019-052037 filed Mar. 20, 2019. 
     BACKGROUND 
     (i) Technical Field 
     The present disclosure relates to sheet transport devices, image reading devices, and image forming apparatuses. 
     (ii) Related Art 
     Japanese Unexamined Patent Application Publication No. 11-222345 discloses a known automatic document feeding device including a feed tray on which a document is placed, a feeder that feeds the document on the feed tray to a transport path, a transport unit that guides the fed document to an image read position, an output unit that outputs the read document onto an output tray, and a controller that variably sets the output speed after the document reading process relative to the transport speed during the document reading process. In this automatic document feeding device, if the transport speed during the document reading process is within a predetermined range, the output speed after the document reading process is controlled to be equal to the transport speed during the document reading process. If the transport speed during the document reading process is outside the predetermined range, the output speed after the document reading process is controlled to be within the predetermined range. 
     SUMMARY 
     Aspects of non-limiting embodiments of the present disclosure relate to a sheet transport device, an image reading device, and an image forming apparatus that are capable of suppressing disorderly orientation of small-size sheets output on an output tray, as compared with a configuration not equipped with a regulating unit that regulates the output position of a sheet by rotating or moving a stopper thereof to a position where it is capable of colliding with the downstream edge of the sheet to be output in the output direction. 
     Aspects of certain non-limiting embodiments of the present disclosure address the above advantages and/or other advantages not described above. However, aspects of the non-limiting embodiments are not required to address the advantages described above, and aspects of the non-limiting embodiments of the present disclosure may not address advantages described above. 
     According to an aspect of the present disclosure, there is provided a sheet transport device including a sheet load tray on which a sheet is loaded, a side-edge positioning unit, and a regulating unit. The side-edge positioning unit comes into contact with a side edge of the sheet in a direction intersecting a sheet transport direction of the sheet loaded on the sheet load tray at an upper surface of the sheet load tray and that positions the side edge of the sheet to a normal position. The regulating unit is provided in a rotatable manner about a rotation shaft at a lower surface of the sheet load tray and regulates an output position of the sheet by rotating a stopper of the regulating unit to a position where the stopper is capable of colliding with a downstream edge of the sheet to be output in an output direction when the side-edge positioning unit moves to a position corresponding to a minimum width of the sheet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present disclosure will be described in detail based on the following figures, wherein: 
         FIG. 1  is a cross-sectional view schematically illustrating the internal configuration of an image forming apparatus; 
         FIG. 2  is a cross-sectional view illustrating the internal configuration of an image reading device; 
         FIG. 3  is a cross-sectional view schematically illustrating how sheets are transported in the image reading device; 
         FIG. 4  is a plan view schematically illustrating the configuration of side guides in a sheet load section; 
         FIG. 5  is a plan view schematically illustrating how a sheet is placed on the sheet load section; 
         FIGS. 6A and 6B  are cross-sectional views schematically illustrating the configuration and operation of a pressing mechanism,  FIG. 6A  being a cross-sectional view illustrating a pressing member in an accommodated state,  FIG. 6B  being a cross-sectional view illustrating the pressing member in a rotated state; 
         FIG. 7  is a cross-sectional view schematically illustrating how small-size sheets are output; 
         FIGS. 8A and 8B  are cross-sectional views schematically illustrating the configuration of a pressing mechanism according to a modification and operation performed on a sheet other than a small-size sheet; 
         FIGS. 9A and 9B  are cross-sectional views schematically illustrating the configuration of the pressing mechanism according to the modification and operation performed on a small-size sheet; 
         FIG. 10  is a cross-sectional view schematically illustrating how small-size sheets are output; 
         FIG. 11  is a cross-sectional view schematically illustrating how sheets other than small-size sheets are output; and 
         FIG. 12  illustrates how small-size sheets are transported and output to an output section in an image reading device according to a comparative example not equipped with a pressing mechanism. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure will be described in further detail below with reference to exemplary embodiments and specific examples. However, the present disclosure is not to be limited to these exemplary embodiments and specific examples. 
     Furthermore, in the following description with reference to the drawings, it should be noted that the drawings are schematic and that the dimensional ratios are different from the actual dimensional ratios. For providing an easier understanding, components other than those necessary for the description are omitted, where necessary. 
     First Exemplary Embodiment 
     1. Overall Configuration and Operation of Image Forming Apparatus 
       FIG. 1  is a cross-sectional view schematically illustrating the internal configuration of an image forming apparatus  1  according to a first exemplary embodiment.  FIG. 2  is a cross-sectional view illustrating the internal configuration of an image reading device  2 .  FIG. 3  is a cross-sectional view schematically illustrating how sheets are transported in the image reading device  2 . The overall configuration and the operation of the image forming apparatus  1  will be described below with reference to the drawings. 
     1.1. Overall Configuration 
     The image forming apparatus  1  includes an image reading device  2  that reads an image from a sheet and converts it into image data, an image forming unit  3  as an image recorder that prints the read image data onto paper as a recording medium, an operational information unit  4  as a user interface, and an image processor  5 . 
     The image reading device  2  includes a sheet load section  21 , an automatic sheet feeder  22 , and an image reader  23  as an example of an imaging unit. The automatic sheet feeder  22  transports the sheet S placed on the sheet load section  21  to a read position of the image reader  23 . An image read by an image sensor (not shown), such as a charge-coupled device (CCD) line sensor, of the image reader  23  is converted into image data as an electric signal. 
     The image forming unit  3  includes a paper feeding device  32 , exposure devices  33 , photoconductor units  34 , developing devices  35 , a transfer device  36 , and a fixing device  37 , and forms image information received from the image processor  5  as a toner image onto paper P fed from the paper feeding device  32 . 
     The operational information unit  4  as a user interface is disposed on the front surface of the image reading device  2 . The operational information unit  4  is constituted of a combination of, for example, a liquid crystal display panel, various control buttons, and a touchscreen. A user of the image forming apparatus  1  may input various settings and a command via the operational information unit  4  as an example of a receiving unit. Moreover, various types of information are displayed to the user of the image forming apparatus  1  via the liquid crystal display panel. 
     The image processor  5  generates image data from the image read by the image reading device  2  and from print information transmitted from an external apparatus (such as a personal computer). 
     1.2. Image Forming Unit 
     Paper P designated in a print job for each printing process is fed from the paper feeding device  32  to the image forming unit  3  in accordance with an image formation timing of the image forming unit  3 . 
     The photoconductor units  34  individually include photoconductor drums  341  that are provided parallel to one another above the paper feeding device  32  and that are rotationally driven. The developing devices  35  form yellow (Y), magenta (M), cyan (C), and black (K) toner images on the corresponding photoconductor drums  341  having electrostatic latent images formed thereon by the exposure devices  33 . 
     The toner images formed on the photoconductor drums  341  of the respective photoconductor units  34  are sequentially electrostatically transferred (first-transferred) onto an intermediate transfer belt  361  of the transfer device  36 , so that a superposed toner image constituted of toners of the respective colors is formed. The superposed toner image on the intermediate transfer belt  361  is collectively transferred by a second-transfer roller  362  onto the paper P transported from a pair of registration rollers  321  and guided by a transport guide. 
     In the fixing device  37 , a fixation nip FN (fixation region) is formed by a pressure contact area of a pair of heating module  371  and pressing module  372 . 
     The paper P having the toner image collectively transferred thereon by the transfer device  36  is transported to the fixation nip FN of the fixing device  37  via a transport guide  363  in a state where the toner image is not fixed on the paper P yet. Then, the pair of heating module  371  and pressing module  372  fixes the toner image onto the paper P in accordance with heating and pressing functions. 
     The paper P having the fixed toner image formed thereon is guided to a switch gate G 1  and is output from a first pair of output rollers  373  so as to be accommodated in a paper output tray TR 1  at the upper surface of the image forming apparatus  1 . If the paper P is to be inverted for duplex printing or is to be output with the image recorded face thereof facing upward, the transport direction of the paper P is switched toward a transport path  375  by the switch gate G 1 . 
     1.3. Image Reading Device 
     The image reading device  2  includes the sheet load section  21 , the automatic sheet feeder  22 , and the image reader  23 . The sheet load section  21  and the automatic sheet feeder  22  are connected to each other in an openable and closable manner above the image reader  23 . 
     The sheet load section  21  includes a sheet tray  212  on which one or more sheets S having images recorded thereon are placed. 
     The automatic sheet feeder  22  includes the nudger roller  221  that fetches the sheets S loaded on the sheet tray  212  sequentially from the top, and also includes a separator  224  constituted of a feed roller  222  and a retardation roller  223 . 
     In the separator  224 , the feed roller  222  and the retardation roller  223  form a pair that separates sheets S from each other, if multiple stacked sheets S are fed to a nip N, so as to transport the sheets S one-by-one to the image reader  23 . 
     In a transport path G, a takeaway roller  225  is disposed at a position downstream of the feed roller  222  in the transport direction of the sheet S. The takeaway roller  225  transports the sheet S fed by the feed roller  222  to a pre-registration roller  226 . 
     A registration roller  227  that adjusts the transport timing of the sheet S is disposed downstream of the pre-registration roller  226 . The pre-registration roller  226  corrects a skew of the sheet S by forming a loop in a state where the leading edge of the sheet S is in abutment with the registration roller  227  in a stopped state. The registration roller  227  is rotationally driven in accordance with a timing for starting a reading process. In a state where the loop of the sheet S is maintained by the transport roller  225  and the pre-registration roller  226 , the sheet S is pressed against a sheet passing surface PG 1  by a platen roller  228  so that the front face of the sheet S is read by the image reader  23 . 
     A sheet placement surface PG 2  that supports a sheet S placed thereon by an operator is disposed to the right of the sheet passing surface PG 1 . A sheet guide PG 3  is disposed between the sheet passing surface PG 1  and the sheet placement surface PG 2 . The sheet S passing over the sheet passing surface PG 1  is guided to the sheet guide PG 3  so as to be transported to a read sensor  232 . The sheet S whose front face is read by the image reader  23  is output by an output roller  229  to an output section  217  provided below the sheet load section  21 , while the rear face of the sheet S is read by the read sensor  232 . 
     An image reading sensor  231  that optically reads an image of a sheet S and converts it into an electric signal is provided below the sheet placement surface PG 2 . Specifically, the image reading sensor  231  reads an image from a sheet S passing over the sheet passing surface PG 1  or from a sheet S placed on the sheet placement surface PG 2 . The read image is converted into image data as an electric signal. 
     2. Configuration and Operation of Sheet Load Section 
       FIG. 4  is a plan view schematically illustrating the configuration of side guides  215  in the sheet load section  21 .  FIG. 5  is a plan view schematically illustrating how a sheet S is placed on the sheet load section  21 .  FIGS. 6A and 6B  are cross-sectional views schematically illustrating the configuration and operation of a pressing mechanism  240 . Specifically,  FIG. 6A  is a cross-sectional view illustrating a pressing member in an accommodated state, and  FIG. 6B  is a cross-sectional view illustrating the pressing member in a rotated state.  FIG. 7  is a cross-sectional view schematically illustrating how small-size sheets are output. The configuration and operation of the sheet load section  21  will be described below with reference to the drawings. 
     2.1. Configuration of Sheet Load Section 
     The sheet load section  21  has the sheet tray  212  as an example of a sheet load tray and is capable of holding sheets of various sizes, that is, sheets with different dimensions with respect to at least one of a sheet length corresponding to a distance in the sheet transport direction (see an arrow R in  FIG. 5 ) and a sheet width corresponding to a distance in the direction intersecting (orthogonal to) the sheet transport direction. 
     The pair of side guides  215  as an example of a side-edge positioning unit are disposed on a sheet placement surface  212   a  of the sheet tray  212  in a movable manner in the direction intersecting (orthogonal to) the sheet transport direction, such that a center registration method is employed in which the side edges in the sheet width direction are aligned in the width direction with reference to the side guides  215 . 
     As shown in  FIG. 4 , the side guides  215  face each other in the width direction of the sheet S and are connected to each other by a rack-and-pinion mechanism. In detail, with regard to each of the side guides  215 , a rack  215 B extending in the moving direction is integrated with a regulating section  215 A and is connected in engagement with a pinion  215 C rotatably disposed on the tray body  211 . According to this rack-and-pinion mechanism, one of the side guides  215  is moved in conformity to the size of the sheet S (see arrows in  FIG. 4 ), so that the pair of side guides  215  move in conjunction with each other to decrease or increase the distance therebetween. 
     As schematically shown in  FIG. 5 , when a maximum-size sheet Smx placed on the sheet tray  212  is changed to a minimum-size sheet Smn, the side guides  215  are moved in conformity to the size so that the sheet S is positioned in the width direction based on the center registration method. 
     2.2. Assembly Configuration of Pressing Mechanism with Respect to Sheet Tray 
       FIGS. 6A and 6B  illustrate an assembly configuration of a pressing mechanism  240  as an example of a regulating unit. When the side guides  215  move to positions corresponding to the minimum width of a sheet S, the pressing mechanism  240  operates to cause a stopper  241  thereof to regulate the output position of the sheet S by rotating to a position where it is capable of colliding with the downstream edge of the sheet S to be output in the output direction. 
     The pressing mechanism  240  has a rotation shaft  241   a  at one end thereof, and is constituted of the stopper  241  serving as a plate member extending in one direction, an integrally-formed protrusion  215 D extending downward (i.e., −Z direction) at the rack  215 B side of one of the side guides  215 , and an arm  241   b  protruding toward the rotation shaft  241   a  of the stopper  241 . The stopper  241  is rotatably supported by the tray body  211  via the rotation shaft  241   a.    
     As shown in  FIG. 6A , in a state where the protrusion  215 D provided on one of the side guides  215  is not in contact with the arm  241   b , that is, in a state where the side guides  215  are located at positions other than the positions corresponding to the minimum width of the sheet S, the stopper  241  is biased by a torsion spring TS attached to the rotation shaft  241   a  so as to be accommodated in a recess  211   a  provided in the tray body  211 . 
     Then, as shown in  FIG. 6B , when the side guides  215  move to the positions corresponding to the minimum width of the sheet S, the protrusion  215 D provided on one of the side guides  215  comes into contact with the arm  241   b  protruding from the stopper  241 . This causes the stopper  241  to rotate about the rotation shaft  241   a  (see an arrow R 2  in  FIG. 6B ) and to thus protrude to a position where the stopper  241  is capable of colliding with the downstream edge of the sheet S to be output in the output direction. 
     2.3. Function of Pressing Mechanism 
       FIG. 12  illustrates how small-size sheets are transported and output to the output section  217  in an image reading device  200  according to a comparative example not equipped with a pressing mechanism. 
     As an example of sheets S having the minimum width, business cards NC are placed on the sheet tray  212 . The side guides  215  are positioned at the opposite side edges of the business cards NC, and a reading process is commenced. The business cards NC on the sheet tray  212  are fed by the nudger roller  221  in a state where they are positioned in the width direction by the side guides  215 , and are transported one-by-one to the image reader  23 . 
     Each business card NC whose image is read by the image reader  23  is output by the output roller  229  to the output section  217  provided below the sheet load section  21 . Unlike a normal sheet, a business card NC has a smaller size but has a larger basis weight and higher rigidity than plain paper. In a case where business cards NC with a small sheet size (i.e., minimum size) and high rigidity are to be output by the output roller  229 , the trailing edge of each business card NC is output to a position, on the output section  217 , distant from the output roller  229 . In this case, as schematically shown in  FIG. 12 , the business cards NC tend to be output and stacked disorderly on the output section  217 , possibly altering the proper order of the business cards NC. 
       FIG. 7  illustrates how small-size sheets are transported and output to the output section  217  in the image reading device  2  according to this exemplary embodiment equipped with the pressing mechanism  240 . 
     When the business cards NC having the minimum width are placed on the sheet tray  212  of the sheet load section  21  and the side guides  215  are moved to the positions corresponding to the minimum width in accordance with the positions at the opposite side edges of the business cards NC, the stopper  241  rotates so as to protrude to the position where it collides with the leading edge of the sheet S to be output. When the reading process is commenced, the business cards NC on the sheet tray  212  are fed by the nudger roller  221  in a state where the business cards NC are positioned in the width direction by the side guides  215 , and are transported one-by-one to the image reader  23 . 
     Each business card NC whose image is read by the image reader  23  is output by the output roller  229  to the output section  217  provided below the sheet load section  21 . In this case, as shown in  FIG. 7 , the stopper  241  protrudes to the output trajectory of the business card NC at a position downstream of the output roller  229  in the sheet output direction and close to the output roller  229 , such that the business card NC collides with the stopper  241  before being stacked on the output section  217 . Accordingly, the business cards NC as small-size sheets may be output onto the output section  217  without the proper order thereof being altered, and disorderly orientation of output sheets may be suppressed. 
     Modification 
       FIGS. 8A and 8B  are cross-sectional views schematically illustrating the configuration of a pressing mechanism  250  according to a modification and operation performed on a sheet other than a small-size sheet.  FIGS. 9A and 9B  are cross-sectional views schematically illustrating the configuration of the pressing mechanism  250  according to the modification and operation performed on a small-size sheet.  FIG. 10  is a cross-sectional view schematically illustrating how small-size sheets are output.  FIG. 11  is a cross-sectional view schematically illustrating how sheets other than small-size sheets are output. 
     The pressing mechanism  250  according to this modification is provided at the lower surface of the tray body  211  in a movable manner in the sheet output direction. When the side guides  215  move to positions corresponding to the minimum width of a sheet S, the pressing mechanism  250  operates to cause a stopper  255  thereof to regulate the output position of the sheet S by moving to a position where it is capable of colliding with the downstream edge of the sheet S to be output in the output direction. 
       FIG. 8A  is a diagram for explaining the configuration of the pressing mechanism  250  and schematically illustrates the interior of the tray body  211  without showing the tray body  211  and the sheet tray  212 . 
     The pressing mechanism  250  includes a first pulley  251  integrated with the pinion  215 C of the rack-and-pinion mechanism of the side guides  215 , a second pulley  252  rotatably provided downstream of the sheet tray  212  in the sheet feeding direction, a belt member  253  wound between the first pulley  251  and the second pulley  252 , a retaining member  254  fixed to the belt member  253 , and the stopper  255  rotatably retained by the retaining member  254  via a rotation shaft  254   a  downstream in the output direction of the sheet S to be output. 
     With regard to the pressing mechanism  250 , when the side guides  215  move to decrease the distance therebetween in the width direction of the sheet S (see arrows R 1  in  FIG. 8A ), the pinion  215 C engaged with the racks  215 B rotates, thus causing the first pulley  251  integrated with the pinion  215 C to rotate (see an arrow R 2  in  FIG. 8A ). When the first pulley  251  rotates, the belt member  253  wound therearound moves within the rotational range of the first pulley  251  (see arrows R 3  in  FIG. 8A ), and the retaining member  254  fixed to the belt member  253  moves upstream in the sheet feeding direction together with the belt member  253 . 
     Consequently, when the side guides  215  move to the positions corresponding to the minimum width of the sheet S, the stopper  255  moves upstream in the output direction to a position where it is capable of colliding with the downstream edge of the sheet S to be output in the output direction, thereby regulating the output position of the sheet S. 
     With regard to the pressing mechanism  250 , when the side guides  215  move to increase the distance therebetween in the width direction of the sheet S (see arrows R 1  in  FIG. 9A ), the pinion  215 C engaged with the racks  215 B rotates, thus causing the first pulley  251  integrated with the pinion  215 C to rotate (see an arrow R 2  in  FIG. 9A ). When the first pulley  251  rotates, the belt member  253  wound therearound moves within the rotational range of the first pulley  251  (see arrows R 3  in  FIG. 9A ), and the retaining member  254  fixed to the belt member  253  moves downstream in the sheet feeding direction together with the belt member  253 . 
     Consequently, when the side guides  215  move to the positions corresponding to a width other than the minimum width of the sheet S, the stopper  255  moves downstream in the output direction to a position where it is capable of colliding with the downstream edge of the sheet S to be output in the output direction, thereby regulating the output position of the sheet S other than a minimum-size sheet. 
       FIG. 10  illustrates how business cards NC as minimum-size sheets are transported and output to the output section  217  in the image reading device  2  equipped with the pressing mechanism  250  according to the modification. 
     When the business cards NC having the minimum width are placed on the sheet tray  212  and the side guides  215  are moved to the positions corresponding to the minimum width in conformity to the minimum sheet width, the stopper  255  moves upstream in the output direction of the sheet S together with the movement of the belt member  253  so as to regulate the output position of the sheet S at a position where the stopper  255  is capable of colliding with the downstream edge of the sheet S to be output in the output direction. 
     When the reading process is commenced, the business cards NC on the sheet tray  212  are fed by the nudger roller  221  in a state where the business cards NC are positioned in the width direction by the side guides  215 , and are transported one-by-one to the image reader  23 . Each business card NC whose image is read by the image reader  23  is output by the output roller  229  to the output section  217  provided below the sheet load section  21 . 
     In this case, as shown in  FIG. 10 , the stopper  255  protrudes to the output trajectory of the business card NC at a position downstream of the output roller  229  in the sheet output direction and close to the output roller  229 , such that the business card NC collides with the stopper  255  before being stacked on the output section  217 . Accordingly, the business cards NC as small-size sheets may be output onto the output section  217  without the proper order thereof being altered, and disorderly orientation of output sheets may be suppressed. 
       FIG. 11  illustrates how sheets S other than minimum-size sheets are transported and output to the output section  217  in the image reading device  2  equipped with the pressing mechanism  250  according to the modification. 
     When sheets S other than minimum-size sheets are placed on the sheet tray  212  and the side guides  215  are moved in conformity to the positions corresponding to the sheet width, the stopper  255  moves downstream in the output direction of the sheet S together with the movement of the belt member  253  so as to regulate the output position of the sheet S at a position where the stopper  255  is capable of colliding with the downstream edge of the sheet S to be output in the output direction. 
     When the reading process is commenced, the sheets S on the sheet tray  212  are fed by the nudger roller  221  in a state where the sheets are positioned in the width direction by the side guides  215 , and are transported one-by-one to the image reader  23 . Each sheet S whose image is read by the image reader  23  is output by the output roller  229  to the output section  217  provided below the sheet load section  21 . 
     In this case, as shown in  FIG. 11 , the stopper  255  protrudes to the output trajectory of the sheet S at a position downstream of the output roller  229  in the sheet output direction and distant from the output roller  229 , such that the sheet S collides with the stopper  255  before being stacked on the output section  217 . Accordingly, sheets S other than small-size sheets may be stacked on the output section  217  in a state where disorderly orientation of output sheets are suppressed. 
     According to the sheet load section  21  according to this exemplary embodiment, when the side guides  215  move to the positions corresponding to the minimum width of a sheet S, the stopper  241  of the pressing mechanism  240  regulates the output position of the sheet S by rotating to a position where it is capable of colliding with the downstream edge of the sheet S to be output in the output direction. Furthermore, when the side guides  215  move to the position corresponding to the minimum width of a sheet S, the stopper  255  regulates the output position of the sheet S by moving to a position where it is capable of colliding with the downstream edge of the sheet S to be output in the output direction. Accordingly, disorderly orientation of small-size sheets output on the output tray may be suppressed, as compared with a configuration not equipped with a regulating unit that regulates the output position of a sheet by rotating or moving a stopper thereof to a position where it is capable of colliding with the downstream edge of the sheet to be output in the output direction. 
     The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments chosen and described in order to best explain the principles of the disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.