Patent Publication Number: US-2023134086-A1

Title: Sheet transportation 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. 2021-179754 filed Nov. 2, 2021. 
     BACKGROUND 
     (i) Technical Field 
     The present invention relates to a sheet transportation device and an image forming apparatus. 
     (ii) Related Art 
     A sheet transportation device described in JP2020-190657A includes transport means that transports a sheet toward a predetermined position, a motor that drives the transport means, sheet detection means that detects the sheet on a sheet transport path toward the predetermined position via the transport means, torque detection means that detects load torque applied to the motor, and control means that executes speed control of changing a rotation speed of the motor according to a timing when the sheet detection means has detected the sheet during execution of a transport operation of transporting the sheet with the transport means. 
     SUMMARY 
     The sheet transportation device that transports a sheet member includes a plurality of transport rollers arranged with an interval from an upstream side to a downstream side in a transport direction of the sheet member. 
     For convenience of a machine layout, the transport direction of the sheet member is different in some cases between a first transport roller and a second transport roller arranged on the downstream side of the first transport roller in the transport direction of the sheet member. Specifically, the first transport roller transports the sheet member toward a first direction, and the second transport roller transports the sheet member toward a second direction different from the first direction in some cases. In such a case, a guide portion that guides the sheet member transported by the first transport roller toward the second transport roller is provided. 
     The guide portion guides the sheet member in a region pinched between a first line extending from a part of the first transport roller, in which the sheet member is pinched, in the first direction and a second line extending from a part of the second transport roller, in which the sheet member is pinched, in the second direction. In such a case, the transported sheet member receives a resistance from the guide portion. The resistance increases in some cases. 
     Aspects of non-limiting embodiments of the present disclosure relate to a sheet transportation device and an image forming apparatus that decrease a resistance received by a transported sheet member from a guide portion compared to a case where the transported sheet member passes through only a region pinched between a first line and a second line. 
     Aspects of certain non-limiting embodiments of the present disclosure overcome the above disadvantages and/or other disadvantages not described above. However, aspects of the non-limiting embodiments are not required to overcome the disadvantages described above, and aspects of the non-limiting embodiments of the present disclosure may not overcome any of the disadvantages described above. 
     According to an aspect of the present disclosure, there is provided that a sheet transportation device includes a first transport roller that transports a sheet member toward a first direction, a second transport roller that is arranged on a downstream side of the first transport roller in a transport direction of the sheet member and transports the sheet member in a second direction different from the first direction, and a guide portion that guides the sheet member by coming into contact with a leading end of the sheet member in a region on a second transport roller side with respect to a first line extending from a part of the first transport roller, in which the sheet member is pinched, in the first direction and on an opposite side to a first transport roller side with respect to a second line extending from a part of the second transport roller, in which the sheet member is pinched, in the second direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein: 
         FIG.  1    is a schematic configuration view showing an image forming apparatus according to an exemplary embodiment of the present disclosure; 
         FIG.  2    is a configuration view showing an image forming unit of the image forming apparatus according to the exemplary embodiment of the present disclosure; 
         FIG.  3    is a configuration view showing a transporting unit according to the exemplary embodiment of the present disclosure; 
         FIG.  4    is an enlarged configuration view showing the transporting unit according to the exemplary embodiment of the present disclosure; 
         FIGS.  5 A,  5 B,  5 C,  5 D,  5 E, and  5 F  are side views showing a sheet member transported by the transporting unit according to the exemplary embodiment of the present disclosure; 
         FIGS.  6 A,  6 B, and  6 C  are side views showing the sheet member transported by the transporting unit according to the exemplary embodiment of the present disclosure; 
         FIG.  7    is a view showing a graph comparing the transporting unit according to the exemplary embodiment of the present disclosure to a transporting unit according to a comparative embodiment of the exemplary embodiment; 
         FIG.  8    is a configuration view showing the transporting unit according to the comparative embodiment of the exemplary embodiment of the present disclosure; and 
         FIGS.  9 A,  9 B,  9 C,  9 D,  9 E, and  9 F  are side views showing the sheet member transported by the transporting unit according to the comparative embodiment with respect to the transporting unit according to the exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Examples of a sheet transportation device and an image forming apparatus according to an exemplary embodiment of the present disclosure will be described with reference to  FIGS.  1  to  9   . An arrow H shown in each drawing indicates a device up-down direction, which is a vertical direction, an arrow W indicates a device width direction, which is a horizontal direction, and an arrow D indicates a device depth direction, which is a horizontal direction. 
     Overall Configuration of Image Forming Apparatus 
     As shown in  FIG.  1   , an image forming apparatus  10  includes an image forming unit  12  that forms a toner image through an electrophotographic method and accommodating units  60  and  70  that accommodate a transporting unit  14  transporting a sheet member P along a transport path  16  and the sheet member P. 
     In the image forming apparatus  10  having the configuration, the sheet member P is accommodated by the accommodating units  60  and  70 , and the sheet member P accommodated in any one of the accommodating units  60  and  70  is transported along the transport path  16  by the transporting unit  14 . Further, a toner image formed by the image forming unit  12  is formed on the transported sheet member P, and the sheet member P on which the toner image is formed is discharged to the outside of an apparatus body  10   a.    
     Image Forming Unit  12   
     As shown in  FIG.  1   , the image forming unit  12  includes a plurality of toner image forming units  30  that form respective colors of toner images and a transfer unit  32  that transfers the toner images formed by the toner image forming units  30  to the sheet member P. Further, the image forming unit  12  includes a fixing device  34  that fixes the toner images, which are transferred to the sheet member P by the transfer unit  32 , to the sheet member P. 
     Toner Image Forming Unit  30   
     The plurality of toner image forming units  30  are included to form a toner image for each color. In the present exemplary embodiment, in total, four colors of yellow (Y), magenta (M), cyan (C), and black (K) toner image forming units  30  are provided. In the following description, in a case where it is not necessary to distinguish between yellow (Y), magenta (M), cyan (C), and black (K), Y, M, C, and K attached to the reference numerals are omitted. 
     As shown in  FIG.  2   , the toner image forming unit  30  having each color is basically configured the same except for a toner to be used and includes a rotating circular image holding body  40  and a charger  42  that charges the image holding body  40 . Further, the toner image forming unit  30  includes an exposure device  44  that irradiates the charged image holding body  40  with exposure light and forms an electrostatic latent image and a developing device  46  that develops the electrostatic latent image with a developer G containing a toner as a toner image. 
     Accordingly, the toner image forming unit  30  having each color forms an image having each color using each color of toner. 
     In addition, as shown in  FIG.  1   , the image holding body  40  having each color is in contact with a transfer belt  50  (details to be described later) that moves around. In a circumferential direction (see an arrow in  FIG.  1   ) of the transfer belt  50 , the yellow (Y), magenta (M), cyan (C), and black (K) toner image forming units  30  are arranged side by side in turn from an upstream side. 
     Transfer Unit  32   
     As shown in  FIG.  1   , the transfer unit  32  includes the transfer belt  50  and primary transfer rollers  52  each of which is arranged on an opposite side of the image holding body  40  having each color with the transfer belt  50  pinched therebetween and transfers a toner image formed on the image holding body  40  having each color to the transfer belt  50 . 
     In addition, the transfer unit  32  includes a winding roller  56  around which the transfer belt  50  is wound and a drive roller  58  around which the transfer belt  50  is wound and which transmits a rotational force to the transfer belt  50 . Accordingly, the transfer belt  50  moves around in an arrow direction in  FIG.  1   . 
     Further, the transfer unit  32  includes a secondary transfer roller  54  that is arranged on the opposite side of the winding roller  56  with the transfer belt  50  pinched therebetween and that transfers a toner image transferred to the transfer belt  50  to the sheet member P. A transfer nip NT where the toner image is transferred to the sheet member P is formed between the secondary transfer roller  54  and the transfer belt  50 . 
     In the configuration, in order of yellow (Y), magenta (M), cyan (C), and black (K), the toner image is primarily transferred to the transfer belt  50  by the primary transfer roller  52 . On the other hand, the toner image is transferred by the secondary transfer roller  54  from the transfer belt  50  to the sheet member P transported while being pinched between the transfer belt  50  and the secondary transfer roller  54 . Further, the sheet member P to which the toner image is transferred is transported toward the fixing device  34 . 
     Fixing Device  34   
     As shown in  FIG.  1   , the fixing device  34  is arranged on a downstream side of the transfer nip NT in a transport direction of the sheet member P. The fixing device  34  heats and pressurizes the toner image transferred to the sheet member P and fixes the toner image to the sheet member P. 
     Accommodating Units  60  and  70   
     As shown in  FIG.  1   , the accommodating units  60  and  70  are arranged at a lower portion inside the apparatus body  10   a , and the sheet members P can be stacked therein. Details of the accommodating units  60  and  70  will be described later. 
     Transporting Unit  14   
     As shown in  FIG.  1   , the transporting unit  14  transports the sheet member P accommodated in the accommodating units  60  and  70  along the transport path  16 . Details of the accommodating units  60  and  70  will be described later. 
     Others 
     As shown in  FIG.  1   , the image forming apparatus  10  includes a plurality of castors  110  that make the apparatus body  10   a  easily movable. The castors  110  are attached to four corners of a lower end of the apparatus body  10   a , respectively. 
     Major Portion Configuration 
     Next, the accommodating units  60  and  70  and the transporting unit  14  will be described. The transporting unit  14  is an example of the sheet transportation device. 
     Accommodating Units  60  and  70   
     As shown in  FIG.  3   , the accommodating units  60  and  70  are arranged in the device up-down direction. The accommodating unit  60  is arranged below the accommodating unit  70  and on one side (the left in  FIG.  3   ) in the device width direction. In the device up-down direction, a lower portion of the accommodating unit  60  overlaps upper portions of the castors  110 . 
     In the present exemplary embodiment, the accommodating unit  60  generally accommodates the A4 sheet member P, and the accommodating unit  70  generally accommodates the postcard-sized sheet member P. In the image forming apparatus  10 , the consumption of the A4 sheet member P is the largest. The number of sheets that can be accommodated in the accommodating unit  60  accommodating the sheet members P of which the consumption is the largest is larger than the number of sheets that can be accommodated in the accommodating unit  70 . In other words, the thickness of the accommodating unit  60  in the device up-down direction is larger than the thickness of the accommodating unit  70  in the device up-down direction. 
     Transporting Unit  14   
     As shown in  FIG.  1   , the transporting unit  14  includes an adjusting roller  24  that is arranged on the upstream side of the transfer nip NT in the transport direction of the sheet member P (hereinafter, simply referred to as a “sheet transport direction”) and adjusts a timing when the sheet member P is fed to the transfer nip NT. The transporting unit  14  further includes a discharge roller  26  that is arranged on the downstream side in the sheet transport direction and that discharges the sheet member P to which a toner image is fixed by the fixing device  34  to the outside of the apparatus body  10   a.    
     In addition, the transporting unit  14  includes a feeding roller  20   b  that feeds the sheet member P accommodated in the accommodating unit  70  to the transport path  16  and a prevention roller  22   b  that prevents double-feeding of the sheet members P fed by the feeding roller  20   b . The prevention roller  22   b  is an example of a third transport roller. 
     The transporting unit  14  further includes a transport roller  72  that is arranged between the prevention roller  22   b  and the adjusting roller  24  in the sheet transport direction and a guide plate  76  that guides the sheet member P transported by the prevention roller  22   b  toward the transport roller  72 . 
     In addition, as shown in  FIG.  3   , the transporting unit  14  includes a feeding roller  20   a  that feeds the sheet member P accommodated in the accommodating unit  60  to the transport path  16  and a prevention roller  22   a  that prevents double-feeding of the sheet members P fed by the feeding roller  20   a.    
     In addition, the transporting unit  14  further includes a transport roller  80  that is arranged between the prevention roller  22   a  and the transport roller  72  in the sheet transport direction and a guide plate  82  that guides the sheet member P transported by the prevention roller  22   a  toward the transport roller  80 . 
     The transporting unit  14  further includes a guide plate  86  and a guide plate  90  that guide the sheet member P transported by the transport roller  80  toward the transport roller  72  and a restricting unit  92 . 
     The transport path  16  is divided into two paths on the upstream side of the transport roller  72  in the sheet transport direction. One is a transport path  16   a  through which the sheet members P stacked on the accommodating unit  60  are transported, and the other is a transport path  16   b  through which the sheet members P stacked on the accommodating unit  70  are transported. 
     Transport Roller  72   
     The transport roller  72  has the device depth direction as an axial direction and is arranged above the accommodating unit  70  in the device up-down direction with a gap with respect to a side wall  11  of the apparatus body  10   a  as shown in  FIG.  3   . The transport roller  72  is arranged to transport the sheet member P in the device up-down direction and includes a pair of roller portions  72   a  and  72   b . The transport roller  72  is an example of a second transport roller, and the device up-down direction is an example of a second direction. 
     In addition, the roller portion  72   a  and the roller portion  72   b  are arranged in the device width direction, the roller portion  72   a  is arranged on a side wall  11  side, and the roller portion  72   b  is arranged on the opposite side of the side wall  11  with the roller portion  72   a  interposed therebetween. In the present exemplary embodiment, the roller portion  72   b  is driven, and the roller portion  72   a  is driven by the roller portion  72   b . The roller portion  72   b  is an example of one roller portion, and the roller portion  72   a  is an example of the other roller portion. 
     Feeding Roller  20   b , Prevention Roller  22   b , and Guide Plate  76   
     As shown in  FIG.  3   , the feeding roller  20   b  is arranged to be in contact with the uppermost sheet member P accommodated in the accommodating unit  70 , and the uppermost sheet member P is fed to the transport path  16   b.    
     The prevention roller  22   b  is arranged below the transport roller  72  and on one side (the right in  FIG.  3   ) of the transport roller  72  in the device width direction. The prevention roller  22   b  transports the sheet member P toward the device width direction. 
     The guide plate  76  is curved such that the opposite side of the transport path  16   b  is convex in a case of being viewed from the device depth direction. The guide plate  76  guides the sheet member P transported in the device width direction by the prevention roller  22   b  toward the transport roller  72  that transports the sheet member P in the device up-down direction. The guide plate  76  is an example of another guide portion. 
     Feeding Roller  20   a , Prevention Roller  22   a , and Guide Plate  82   
     As shown in  FIG.  3   , the feeding roller  20   a  is arranged to be in contact with the uppermost sheet member P accommodated in the accommodating unit  60 , and the uppermost sheet member P is fed to the transport path  16   a.    
     The prevention roller  22   a  is arranged below the transport roller  72  and on the one side (the right in  FIG.  3   ) of the transport roller  72  in the device width direction. The prevention roller  22   a  transports the sheet member P toward the device width direction. 
     The guide plate  82  is linear in a case of being viewed from the device depth direction and is inclined with respect to the device width direction such that one side in the device width direction is lower than the other side. The guide plate  82  guides the sheet member P transported in the device width direction by the prevention roller  22   a  toward the transport roller  80 . 
     Transport Roller  80 , Guide Plate  86 , Guide Plate  90 , and Restricting Unit  92   
     The transport roller  80  has the device depth direction as an axial direction and is arranged between the transport roller  72  and the prevention roller  22   a  in the device up-down direction and the device width direction as shown in  FIG.  3   . The transport roller  80  transports the sheet member P in a first direction in which one side in the device width direction is inclined with respect to the device width direction so as to be lower than the other side. The transport roller  80  is an example of a first transport roller. 
     Herein, a frictional force generated between the surface of the transport roller  80  and the sheet member P is lower than a frictional force generated between the surfaces of the prevention rollers  22   a  and  22   b  and the sheet member P in consideration of life. In other words, a force of transporting the sheet member P by the transport roller  80  is weaker than a force of transporting the prevention rollers  22   a  and  22   b . For this reason, for example, it is preferable that a resistance received by the sheet member P transported by the transport roller  80  is lower. 
     The guide plate  86  is linear in a case of being viewed from the device depth direction and is inclined with respect to the device width direction such that one side in the device width direction is lower than the other side. The guide plate  86  guides the sheet member P such that the sheet member P follows the first direction while supporting the back surface of the sheet member P transported in the first direction by the transport roller  80 . 
     The guide plate  90  is curved such that the other side in the device width direction is convex in a case of being viewed from the device depth direction. Herein, as shown in  FIG.  4   , a line extending from a part of the transport roller  80 , in which the sheet member P is pinched, in the first direction will be defined as a first line L1, and a line extending from a part of the transport roller  72 , in which the sheet member P is pinched, in the device up-down direction (second direction) will be defined as a second line L2. Then, the guide plate  90  is curved such that a side separating away from the second line L2 in the device width direction is convex in a case of being viewed from the device depth direction. In other words, the guide plate  90  is curved such that a transported sheet member P side is recessed is concave in a case of being viewed from the device depth direction. The guide plate  90  is an example of the guide portion, and further, a point P1 in the guide plate  90 , which is the farthest from the second line L2, is located on the downstream side in the sheet transport direction with respect to a point P2 where the guide plate  90  and the first line L1 intersect each other. 
     The guide plate  90  guides the sheet member P by coming into contact with a leading end of the sheet member P in a region (a region R1 in  FIG.  4   ) on a transport roller  72  side with respect to the first line L1 and on the opposite side to a side where the transport roller  80  is arranged with respect to the second line L2. In the present exemplary embodiment, an angle al formed by the first line L1 and the second line L2 is 132 [degrees]. 
     In addition, in a case of being viewed from the device depth direction, the guide plate  90  is arranged in a region where the transport roller  72  is arranged in the device width direction. In other words, in a case of being viewed from the axial direction of the transport roller  80 , the guide plate  90  is arranged in the region where the transport roller  72  is arranged in a direction perpendicular to the axial direction of the transport roller  80  and is parallel to a horizontal plane. Accordingly, in the region where the transport roller  72  is arranged in the device width direction, the guide plate  90  comes into contact with at least a part of the leading end of the sheet member P and guides the sheet member P such that the leading end of the sheet member P moves on a curved trajectory. In other words, the guide plate  90  comes into contact with at least a part of the leading end of the sheet member P and guides the sheet member P such that the leading end of the sheet member P moves on a smooth curved trajectory. 
     Specifically, as a moving direction of the leading end of the transported sheet member P changes from a direction inclined on one side with respect to the device up-down direction to a direction inclined on the other side with respect to the device up-down direction, the leading end of the sheet member P moves on a curved trajectory. 
     The restricting unit  92  is arranged on the opposite side to the guide plate  86  with the transport path  16   a  placed therebetween. Accordingly, the restricting unit  92  comes into contact with the front surface of the sheet member P that is transported while the leading end thereof is in contact with the guide plate  90  and restricts a transport position of the sheet member P. 
     Action 
     Next, action of the transporting unit  14  will be described. In particular, a process of transporting the sheet members P stacked in the accommodating unit  70  to the transport roller  72  and a process of transporting the sheet members P stacked in the accommodating unit  60  to the transport roller  72  will be described. The process of transporting the sheet members P stacked in the accommodating unit  60  to the transport roller  72  will be described in comparison to a transporting unit  214  according to a comparative embodiment. 
     Transport of Sheet Members P Stacked in Accommodating Unit  70   
     In the transporting unit  14 , the feeding roller  20   b  shown in  FIG.  3    feeds the uppermost sheet member P stacked in the accommodating unit  70  from the accommodating unit  70  toward the prevention roller  22   b . The prevention roller  22   b  receives the sheet member P from the feeding roller  20   b  and transports the sheet member. 
     As shown in  FIG.  6 A , the sheet member P transported by the prevention roller  22   b  is guided along a plate surface of the curved guide plate  76 . Further, as shown in  FIGS.  6 B and  6 C , the leading end of the sheet member P comes into contact with a roller surface of the roller portion  72   a  and is moved by the rotating roller portion  72   a . The sheet member P is transported while being pinched in the transport roller  72 . 
     Configuration of Transporting Unit  214   
     As shown in  FIG.  8   , the transporting unit  214  according to the comparative embodiment includes the transport roller  72 , the feeding roller  20   b , the prevention roller  22   b , and the guide plate  76 . Further, the transporting unit  214  includes the feeding roller  20   a , the prevention roller  22   a , the guide plate  82 , the transport roller  80 , the guide plate  86 , a guide plate  290 , and the restricting unit  92 . That is, the transporting unit  214  does not include the guide plate  90  compared to the transporting unit  14  and includes the guide plate  290 . 
     The guide plate  290  has a flat plate surface overlapping the second line L2 in a case of being viewed from the device depth direction and guides the sheet member P having the leading end in contact with the guide plate  290  toward the transport roller  72 . That is, the transporting unit  214  guides the sheet member P such that the sheet member P passes through a region (a region R2 in  FIG.  8   ) pinched between the first line L1 and the second line L2. The region R2 includes the first line L1 and the second line L2. 
     Transport of Sheet Members P Stacked in Accommodating Unit  60   
     In the transporting units  14  and  214 , the feeding roller  20   a  shown in  FIGS.  3  and  8    feeds the uppermost sheet member P stacked in the accommodating unit  60  from the accommodating unit  60  toward the prevention roller  22   a . The prevention roller  22   a  receives the sheet member P from the feeding roller  20   a  and transports the sheet member. 
     The prevention roller  22   a  transports the sheet member P in the device width direction. Further, the guide plate  82  inclined with respect to the device width direction supports the back surface of the sheet member P transported by the prevention roller  22   a  and guides the sheet member toward the transport roller  80 . In addition, the transport roller  80  receives the sheet member P guided by the guide plate  82  and transports the sheet member. 
     As shown in  FIGS.  5 A and  9 A , the sheet member P transported by the transport roller  80  has the back surface supported by the guide plate  86  and is transported while being inclined with respect to the device width direction. 
     Herein, as shown in  FIG.  9 B , in the transporting unit  214  according to the comparative embodiment, the leading end of the sheet member P transported while being inclined with respect to the device width direction comes into contact with the flat plate surface of the guide plate  290 . Further, as shown in  FIG.  9 C , as the leading end of the sheet member P moves on a linear trajectory along the plate surface of the guide plate  290 , the sheet member P is guided by the guide plate  290  toward the transport roller  72 . 
     Further, as shown in  FIG.  9 D , a sheet surface of a leading end portion of the sheet member P comes into contact with the plate surface of the guide plate  290 , and the sheet member P is guided by the guide plate  290  toward the transport roller  72 . The leading end of the sheet member P comes into contact with a pinched portion between the roller portion  72   a  and the roller portion  72   b , and the sheet member P is transported by the transport roller  72  as shown in  FIGS.  9 E and  9 F . 
     On the contrary, as shown in  FIG.  5 B , in the transporting unit  14  according to the exemplary embodiment, the leading end of the sheet member P transported while being inclined with respect to the device width direction comes into contact with the curved plate surface of the guide plate  90 . In addition, as shown in  FIG.  5 C , as the leading end of the sheet member P moves on a curved trajectory along the plate surface of the guide plate  90 , the sheet member P is guided by the guide plate  90  toward the transport roller  72 . In other words, as the leading end of the sheet member P moves on a smooth curved trajectory along the plate surface of the guide plate  90 , the sheet member P is guided by the guide plate  90  toward the transport roller  72 . 
     Further, as shown in  FIG.  5 D , as the leading end of the sheet member P moves on a curved trajectory along the plate surface of the guide plate  90 , the sheet member P is guided by the guide plate  90  toward the transport roller  72 . In addition, as shown in  FIGS.  5 E and  5 F , the leading end of the sheet member P comes into contact with a roller surface of the roller portion  72   b  and is moved by the rotating roller portion  72   b . The sheet member P is transported while being pinched in the transport roller  72 . 
     As shown in  FIG.  5 E , after the leading end of the sheet member P is separated away from the guide plate  90 , the guide plate  90  comes into contact with the sheet surface of the sheet member P and guides the sheet member P. 
     Analysis 
     Next, as for the transporting unit  14  and the transporting unit  214 , results obtained by analyzing a resistance received by the sheet member P, which is transported from the accommodating unit  60 , from the guide plates  90  and  290  using the finite element method will be described. 
     Analysis Specifications
         In the transporting unit  14  and the transporting unit  214 , the angle al formed by the first line L1 and the second line L2 is 132 [degrees] (see  FIG.  4   ).   In the transporting unit  14  and the transporting unit  214 , a distance M1 from an intersection Kl between the first line L1 and the second line L2 to an axis of the transport roller  72  in the second direction (vertical direction) is 73 [mm] (see  FIG.  4   ).   In the transporting unit  14  and the transporting unit  214 , a distance M2 from the intersection Kl between the first line L1 and the second line L2 to an axis of the transport roller  80  in the first direction is 42 [mm] (see  FIG.  4   ).   A maximum distance M3 between the curved plate surface of the guide plate  90  in the transporting unit  14  and the second line L2 in the device width direction is 12 [mm] (see  FIG.  4   ).   The bending R of the curved plate surface of the guide plate  90  in the transporting unit  14  is 62 [mm] (see  FIG.  4   ).   The plate surface of the guide plate  290  in the transporting unit  214  follows the device up-down direction (see  FIG.  8   ).       

     Specifications other than the specifications described above are the same specifications used for the transporting unit  14  and the transporting unit  214 . 
     Analysis Conditions 
     Analysis conditions such as the transport force of the transport roller  80  are the same conditions for the transporting unit  14  and the transporting unit  214 . 
     Analysis Results 
     Analysis results will be described using a graph in  FIG.  7   . The vertical axis of the graph shown in  FIG.  7    represents a resistance received by the transported sheet member P from the guide plate, and the horizontal axis of the graph represents elapsed time. A broken line in the graph indicates analysis results of the transporting unit  14 , and a solid line in the graph indicates analysis results of the transporting unit  214 . 
     In a case where the leading end of the sheet member P comes into contact with the guide plate  290  and the moving direction of the leading end abruptly changes in the transporting unit  214  as shown in  FIG.  9 B , a resistance received by the sheet member P increases as indicated by a part E1 in the graph. 
     Further, in a case where the leading end portion of the sheet member P comes into contact with the plate surface of the guide plate  290  and bends in the transporting unit  214  as shown in  FIG.  9 C , a resistance received by the sheet member P further increases and reaches a peak value as indicated by a part E2 in the graph. 
     In addition, in a case where the sheet surface of the leading end portion of the sheet member P comes into contact with the plate surface of the guide plate  290  in the transporting unit  214  as shown in  FIG.  9 D , a resistance received by the sheet member P decreases as indicated by a part E3 in the graph. 
     On the contrary, in a case where the leading end of the sheet member P comes into contact with the guide plate  90  and the moving direction of the leading end changes in the transporting unit  14  as shown in  FIG.  5 B , a resistance received by the sheet member P increases as indicated by a part F1 in the graph. 
     However, a distance M4 between a position where the leading end of the sheet member P comes into contact with the guide plate  90  and the axis of the transport roller  80  in the first direction is longer than a distance M5 between a position where the leading end of the sheet member P comes into contact with the guide plate  290  and the axis of the transport roller  80  in the first direction (see  FIG.  9 B ). 
     Further, in the transporting unit  14 , the leading end of the sheet member P that is in contact with the guide plate  90  moves in a direction separating away from the second line L2 (see  FIG.  4   ) extending in the device up-down direction. For this reason, the transporting unit  14  has a degree of a resistance increase smaller than the degree of the transporting unit  214 . 
     Further, in a case where the leading end of the sheet member P moves on a curved trajectory while being in contact with the curved surface of the guide plate  90  in the transporting unit  14  and the sheet member P warps as shown in  FIG.  5 C , a resistance gradually increases as indicated by a part F2 in the graph. 
     In addition, in a case where the leading end of the sheet member P moves on a curved trajectory while being in contact with the curved surface of the guide plate  90  in the transporting unit  14  and the sheet member P warps as shown in  FIGS.  5 D and  5 E , a resistance that has gradually increased reaches the peak as indicated by a part F3 in the graph. 
     However, as can be seen by comparing  FIGS.  5 A to  5 F  to  FIGS.  9 A to  9 F , the transporting unit  14  generally has a longer distance from a position where the sheet member P is pinched in the transport roller  80  to a position where the sheet member P comes into contact with the guide plates  90  and  290  than the distance of the transporting unit  214 . For this reason, as in the graph shown in  FIG.  7   , a peak resistance in the transporting unit  14  is lower than a peak in the transporting unit  214 . 
     Outline 
     As described above, a resistance received by the transported sheet member P from the guide plate  90  is lower in the transporting unit  14  than in the transporting unit  214  in which the sheet member P passes through only the region R2 pinched between the first line L1 and the second line L2. 
     In addition, in the transporting unit  14 , the guide plate  90  guides the sheet member P such that the leading end of the sheet member P moves on a curved trajectory having the convex side separating away from the second line L2 in the device width direction in a case of being viewed from the device depth direction. For this reason, compared to a case where the moving direction of the leading end of the sheet member P abruptly changes, an abrupt change in a resistance received by the sheet member P from the guide plate  90  is suppressed. 
     In addition, the guide plate  90  moves such that the leading end of the sheet member P moves on a curved trajectory in the region where the transport roller  72  is arranged in the device width direction in the transporting unit  14 . Accordingly, compared to a case where the leading end of the sheet member P moves outside a region where the transport roller  72  is provided in the device width direction, a range where the guide plate  90  and the transport roller  72  are provided in the device width direction is narrow. 
     In addition, in the transporting unit  14 , the guide plate  90  is curved such that the side separating away from the second line L2 in the device width direction is convex in a case of being viewed from the device depth direction. Accordingly, compared to a case where a bent portion is formed in the guide plate, an abrupt change in a resistance received by the sheet member P from the guide plate  90  is suppressed. 
     In addition, in the transporting unit  14 , the guide plate  90  is arranged in the region where the transport roller  72  is arranged in the device width direction. Compared to a case where the guide plate is arranged outside the region where the transport roller  72  is provided in the device width direction, the range where the guide plate  90  and the transport roller  72  are provided in the device width direction is narrow. 
     In addition, in the transporting unit  14 , the leading end of the sheet member P guided by the guide plate  76  comes into contact with the roller portion  72   a  (a solid line of  FIG.  6 B ). For this reason, compared to a case where the leading end of the sheet member P directly comes into contact with the pinched portion between the roller portion  72   a  and the roller portion  72   b  (a two-dot chain line of  FIG.  6 B ), a resistance received by the transported sheet member P from the guide plate  76  decreases as the bending R of the sheet member P increases. 
     In addition, compared to a case where the image forming apparatus  10  includes the transporting unit  214 , as a resistance received by the sheet member P from the guide plate  90  decreases, jamming of the sheet member P inside the apparatus body  10   a  is suppressed. 
     In addition, in the image forming apparatus  10 , the lower portion of the accommodating unit  60  overlaps the upper portions of the castors  110  in the device up-down direction. For this reason, compared to a case where the accommodating unit is arranged above the castors  110 , the height of the image forming apparatus  10  is lowered. 
     Although details of a certain exemplary embodiment of the present disclosure have been described, the present disclosure is not limited to such an exemplary embodiment, and it is clear for those skilled in the art that the present disclosure can take other various exemplary embodiments within the scope of the present disclosure. For example, although the transporting unit  14  is used in the image forming apparatus  10  adopting the electrophotographic method in the exemplary embodiment, for example, the transporting unit may be used in an image forming apparatus adopting an inkjet method. 
     In addition, the guide plate  90  moves such that the leading end of the sheet member P moves on a curved trajectory in the exemplary embodiment, but the leading end of the sheet member P may move in the region R1. For example, the leading end of the sheet member P may move linearly in the region R1. However, in this case, action achieved by moving the leading end on the curved trajectory is not achieved. 
     In addition, the guide plate  90  moves such that the leading end of the sheet member P moves on a curved trajectory in the region R2 in the exemplary embodiment, but the leading end of the sheet member P may move outside the region R2. However, in this case, action achieved by moving the leading end of the sheet member P in the region R2 is not achieved. 
     In addition, in the exemplary embodiment, the guide plate  90  that guides the leading end of the sheet member P is a plate-shaped member, but without being limited to the plate-shaped member, may be formed to have a curved surface with which the leading end of the sheet member P comes into contact. For example, a molded member in which the curved surface is formed may be used, curved rods may be arranged in the device depth direction, or a resin film may be bent in a curved shape. 
     In addition, the guide plate  76  that guides the leading end of the sheet member P is a plate-shaped member in the exemplary embodiment, but without being limited to the plate-shaped member, the sheet member P may be transported such that the leading end of the sheet member P comes into contact with the roller portion  72   b . For example, the molded member in which the curved surface is formed may be used, the curved rods may be arranged in the device depth direction, or the resin film may be bent in a curved shape. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.