Patent Publication Number: US-11040842-B2

Title: Sheet supporting apparatus and image forming apparatus

Description:
This application is a continuation of application Ser. No. 15/658,664, filed Jul. 25, 2017. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a sheet supporting apparatus for supporting sheets and an image forming apparatus including the sheet supporting apparatus. 
     Description of the Related Art 
     In general, image forming apparatuses, such as copying machines and printers, are provided with a sheet feeding cassette that stores sheets used to form images. Positions of the trailing edge and the side edges of the sheets, stored in the sheet feeding cassette, are regulated by regulation plates, which are supported such that the regulation plate can be moved with respect to the sheet feeding cassette. A user moves the regulation plate in accordance with a sheet size, sets sheets in the sheet feeding cassette, and attaches the sheet feeding cassette to an apparatus body. 
     Conventionally, Japanese Patent Application Publication No. H05-278869 proposes a sheet feeding cassette in which projections are formed at two corner portions of a regulation plate, and concave portions capable of engaging with one of the projections are formed in a cassette body. A user can move the regulation plate by turning the regulation plate to one direction to release the engagement between the one of the projections and one of the concave portions, and position the regulation plate by releasing the turn of the regulation plate to engage the one of the projections with another one of the concave portions. 
     In the sheet feeding cassette described in Japanese Patent Application Publication No. H05-278869, however, because the engagement between the projection and the concave portion may not be ensured or a user may perform a wrong operation, the regulation plate may be displaced from a proper position. The displacement of the regulation plate from the proper position causes reduction in print precision and occurrence of jam. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a sheet supporting apparatus includes a supporting portion configured to support a sheet, and a regulation unit configured to regulate a position of an edge of the sheet supported by the supporting portion, the regulation unit configured to be moved and positioned with respect to the supporting portion. The regulation unit includes a body portion, an engagement portion supported by the body portion, and configured to move between an engagement position at which the engagement portion engages with the supporting portion and a separation position at which the engagement portion is separated away from the supporting portion, and a regulation portion configured to position the engagement portion with respect to the body portion such that the engagement portion is retained at the engagement position. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an overall schematic diagram of a printer according to a first embodiment. 
         FIG. 2  is a plan view illustrating a feeding cassette. 
         FIG. 3  is an overall perspective view illustrating a trailing edge regulation plate. 
         FIG. 4A  is a perspective view illustrating an internal structure of the trailing edge regulation plate. 
         FIG. 4B  is a perspective view illustrating a lever portion and a first stopper. 
         FIG. 5A  is a side view illustrating the first stopper positioned at an engagement position. 
         FIG. 5B  is a side view illustrating the first stopper positioned at a separation position. 
         FIG. 6A  is a perspective view illustrating a state where the first stopper is not fixed with a screw. 
         FIG. 6B  is a perspective view illustrating a state where the first stopper is fixed with the screw. 
         FIG. 7A  is an overall perspective view illustrating a trailing edge regulation plate of a second embodiment. 
         FIG. 7B  is a rear perspective view illustrating a state where a spacer is attached. 
         FIG. 7C  is a front perspective view illustrating the state where the spacer is attached. 
         FIG. 8A  is an overall perspective view illustrating a trailing edge regulation plate of a third embodiment. 
         FIG. 8B  is a front perspective view illustrating a state where a lock lever is positioned at a first position. 
         FIG. 8C  is a front perspective view illustrating a state where the lock lever is positioned at a second position. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     First Embodiment 
     Overall Structure of Printer 
     First, a first embodiment of the present invention will be described. A printer  1  according to the first embodiment that serves as an image forming apparatus is an electrophotographic laser-beam printer. As illustrated in  FIG. 1 , the printer  1  includes a feeding cassette  2  provided such that the feeding cassette  2  can be inserted into and pulled out from a printer body  1 A, a feeding portion  3 , an image forming portion  6  that forms an image on a sheet fed by the feeding portion  3 , a fixing portion  8 , and a discharge roller pair  10 . 
     When an image forming instruction is outputted to the printer  1 , an image forming process by the image forming portion  6  is started, based on image information data inputted from, for example, an external computer connected to the printer  1  or an image reading apparatus optionally connected to the printer  1 . The image forming portion  6  includes a known cartridge  6   a  including a photosensitive drum  6   b , a charger, and a developing roller, a scanner unit  9 , and a transfer roller  7 . 
     The scanner unit  9  emits a laser beam to the photosensitive drum  6   b , based on inputted image information data. At this time, the photosensitive drum  6   b  has been charged in advance by the charger, and thus an electrostatic latent image is formed on the photosensitive drum  6   b  by the laser beam projected thereto. The electrostatic latent image is then developed by the developing roller, and a toner image is formed on the photosensitive drum  6   b.    
     Simultaneously with the above-described image forming process, a sheet that has been stuck on the feeding cassette  2  is fed by the feeding portion  3 . The feeding portion  3  includes a pickup roller  3   a  that feeds sheets, stuck on the feeding cassette  2 , and a feed roller  3   b  and a separation roller  3   c  that separate the sheets, one by one, fed by the pickup roller  3   a . The sheet fed by the feeding portion  3  is conveyed to a registration roller pair  5  by a conveyance roller  4 , and abuts a nip of the registration roller pair  5  that is in a stop state. The leading edge of the sheet then becomes parallel to the nip, and thus skew of the sheet is corrected. 
     The skew-corrected sheet is conveyed toward the transfer roller  7  by the registration roller pair  5 , in synchronization with an image formation by the image forming portion  6 . The transfer roller  7  is applied with transfer bias, and transfers the toner image formed on the photosensitive drum  6   b , onto the sheet. The sheet, on which the toner image is transferred by the transfer roller  7 , is then subjected to heat and pressure treatment by the fixing portion  8  constituted by a heating roller  8   a  and a pressure roller  8   b , and thus the toner image is fixed on the sheet. The sheet on which the toner image is fixed is then discharged to a discharge tray  11  by the discharge roller pair  10 . 
     Feeding Cassette 
     Next, with reference to  FIG. 2 , a configuration of the feeding cassette  2  that serves as a sheet supporting apparatus will be described. The feeding cassette  2  includes a cassette body  21  including a base plate  21   a , an intermediate plate  25  pivotally supported by the base plate  21   a , side edge regulation plates  22  and  23 , and a trailing edge regulation plate  24 . The side edge regulation plates  22  and  23  regulate the positions of the side edges of sheets that are stuck on the base plate  21   a  and the intermediate plate  25 , and the trailing edge regulation plate  24  regulates the position of the trailing edge of the sheets. 
     The side edge regulation plates  22  and  23  are supported such that the side edge regulation plates  22  and  23  can be moved in a width direction orthogonal to a sheet conveyance direction, and each have a rack-shaped portion which meshes with an interlocking gear  223 . Thus, the side edge regulation plates  22  and  23  are structured such that, when the side edge regulation plate  22  is moved, the side edge regulation plate  23  is also moved together with the side edge regulation plate  22 , with the aid of the interlocking gear  223  and the rack-shaped portions. The trailing edge regulation plate  24  is structured such that the trailing edge regulation plate  24  can be moved in the sheet conveyance direction and a direction opposite to the sheet conveyance direction (directions indicated by an arrow A) with the aid of a guide  21   b  formed in the base plate  21   a.    
     The intermediate plate  25  is supported such that a downstream side, in the sheet conveyance direction, of the intermediate plate  25  is swung on the shaft portions  21   c  and  21   c . When the downstream side of the intermediate plate  25  moves upward, a downstream side of the sheets stored in the feeding cassette  2  is pressed against the pickup roller  3   a . The intermediate plate  25  is formed not to prevent the movements of the side edge regulation plates  22  and  23  and the trailing edge regulation plate  24  in the whole locus of the swing of the intermediate plate  25 . 
     Structure of Trailing Edge Regulation Plate 
     Next, a structure of the trailing edge regulation plate  24  of the first embodiment will be described in detail with reference to  FIGS. 3 to 5 . As illustrated in  FIG. 3 , the trailing edge regulation plate  24  that serves as a regulation unit includes a box-shaped body portion  26 , a plate portion  28  capable of regulating the position of the trailing edge of the sheets that are stuck on the base plate  21   a , and a lever portion  27 . The plate portion  28  is structured such that the plate portion  28  can be slightly moved in the sheet conveyance direction, so that the plate portion  28  tolerates slight variations in sheet size produced in, for example, a cutting process. The base plate  21   a  that serves as a supporting portion of the feeding cassette  2  is provided with a plurality of positioning holes  29  at positions corresponding to standard sizes, such as A4 and B5. 
     As illustrated in  FIGS. 4A and 4B , a pivot shaft  27   a  of the lever portion  27 , a first stopper  31 , a second stopper  30  and the like are disposed inside the body portion  26 . The lever portion  27  that serves as an operation portion includes the pivot shaft  27   a  pivotally supported by the body portion  26 , a holding portion  27   b  integrated with the pivot shaft  27   a , a first pressing portion  27   c , and a second pressing portion  27   d . The first pressing portion  27   c  and the second pressing portion  27   d  are pivoted with the holding portion  27   b  by a user pivoting the holding portion  27   b.    
     In the present embodiment, the first stopper  31  is disposed corresponding to the first pressing portion  27   c , and the second stopper  30  is disposed corresponding to the second pressing portion  27   d . The structure of the first stopper  31  is substantially the same as that of the second stopper  30 , and thus the first stopper  31  will be mainly described. Here, the first stopper  31  is a stopper to position the trailing edge regulation plate  24  at a position corresponding to any one of the standard sizes, and the second stopper  30  is a stopper to position the trailing edge regulation plate  24  at a position corresponding to a non-standard size. In  FIG. 4B , the second stopper  30  is omitted. 
     As illustrated in  FIG. 4B , the first stopper  31  that serves as an engagement portion is elongated in a vertical direction, and includes an engagement pin  31   b  formed at a lower end of the first stopper  31  and a long hole  31   d  formed at a substantially central portion of the first stopper  31 . The long hole  31   d  is elongated in the vertical direction, and the pivot shaft  27   a  of the lever portion  27  passes through the long hole  31   d . The first stopper  31  can be moved vertically between an engagement position at which the engagement pin  31   b  engages with the positioning hole  29  and a separation position at which the engagement pin  31   b  is separated upward from the positioning hole  29 , in a range in which the long hole  31   d  can be moved with respect to the pivot shaft  27   a.    
     At an upper end of the first stopper  31 , a through hole  31   c  is formed at a position corresponding to a through hole  26   a  formed in the body portion  26 , as illustrated in  FIG. 4A . A female screw  26   b  is provided at a position corresponding to the through hole  26   a  of the body portion  26 , and thus the first stopper  31  can be fixed at the engagement position by passing a screw  33  (see  FIGS. 6A and 6B ) through the through hole  31   c  of the first stopper  31  and by fixing the screw  33  to the female screw  26   b . The screw  33  and the female screw  26   b  that serve as fixing components constitute a regulation portion  75  that can regulate movement of the first stopper  31  with respect to the body portion  26 . A coil spring  32  is provided in a contracted state between the first stopper  31  and the body portion  26  of the trailing edge regulation plate  24 , and thus the first stopper  31  is urged toward the engagement position by the coil spring  32  that serves as an urging portion. 
     In addition, the first stopper  31  also includes a pressed portion  31   a  in contact with the first pressing portion  27   c , as illustrated in  FIGS. 5A and 5B . The pressed portion  31   a  is formed in a downward-projecting mountain shape, and has inclined surfaces  61  and  62  on a downstream side and an upstream side, respectively, in the sheet conveyance direction. An end of the first pressing portion  27   c  is formed in a downward-concave valley shape, corresponding to the form of the pressed portion  31   a , and has inclined surfaces  71  and  72  on the downstream side and the upstream side, respectively, in the sheet conveyance direction. Here, a coil spring  42  is also provided in a contracted state between the second stopper  30  and the body portion  26  of the trailing edge regulation plate  24 , and the second stopper  30  also includes a pressed portion having the same shape as that of the pressed portion of the first stopper  31 . 
     Operation of Trailing Edge Regulation Plate 
     Next, the operation of the trailing edge regulation plate  24  will be described. In a case where a user sets sheets in the feeding cassette  2 , the user first places sheets, such as sheets with a predetermined size, on the base plate  21   a  and the intermediate plate  25 , and then positions the side edge regulation plates  22  and  23  by moving the side edge regulation plates  22  and  23  to the side edges of the sheets. In the present embodiment, the above-described predetermined size of the sheets is a standard size. 
     The user then operates the holding portion  27   b  and moves the trailing edge regulation plate  24 . In a state of the trailing edge regulation plate  24  before the user operates the trailing edge regulation plate  24 , the first stopper  31  and the second stopper  30  are urged toward the base plate  21   a  of the cassette body  21  by the urging force of the coil springs  32  and  42 . When the trailing edge regulation plate  24  is positioned at a position corresponding to the standard-size sheets, the trailing edge regulation plate  24  is positioned by the first stopper  31  engaging with the positioning hole  29 . When the trailing edge regulation plate  24  is not positioned at the position corresponding to the standard-size sheets, the trailing edge regulation plate  24  is positioned such that a plurality of teeth formed at an end of the second stopper  30  engage with a rack-shaped portion formed on the cassette body  21  of the feeding cassette  2 . 
     When the holding portion  27   b  is pivoted upstream or downstream in the sheet conveyance direction from a neutral position, the first pressing portion  27   c  and the second pressing portion  27   d , which are pivoted with the holding portion  27   b , are pivoted in a direction indicated by an arrow A 1  or a direction indicated by an arrow A 2 , as illustrated in  FIG. 5B . Then, the first pressing portion  27   c  presses against the inclined surfaces  61  and  62  of the pressed portion  31   a  of the first stopper  31  and the second pressing portion  27   d  presses against the pressed portion of the second stopper  30 . That is, the first pressing portion  27   c  and the second pressing portion  27   d  are formed so that the first pressing portion  27   c  and the second pressing portion  27   d  can lift the first stopper  31  and the second stopper  30  regardless of whether the holding portion  27   b  is pivoted to the upstream side or the downstream side in the sheet conveyance direction, from the neutral position. With this, the first stopper  31  and the second stopper  30  enter a state where the first stopper  31  and the second stopper  30  are separated upward from the base plate  21   a  of the cassette body  21  against the urging force of the coil springs  32  and  42 , and where the trailing edge regulation plate  24  can be moved. In this state, the user moves the trailing edge regulation plate  24  in the sheet conveyance direction or the opposite direction, and positions the trailing edge regulation plate at a position corresponding to the above-described predetermined-size sheets. 
     When the movement of the trailing edge regulation plate  24  is completed, the user returns the holding portion  27   b  to its original position and engages the engagement pin  31   b  of the first stopper  31  with the positioning hole  29 . That is, the first stopper  31  is positioned at the engagement position. With this, the trailing edge regulation plate  24  is positioned. 
     Commonly, when predetermined-size sheets are successively used, the trailing edge regulation plate  24  needs not to be moved. For that reason, it is preferable that the trailing edge regulation plate  24  is fixed not to be moved, when the sheet size is not changed, and that the fixed state of the trailing edge regulation plate  24  can be released only when the sheet size is changed. 
     In the present embodiment, the first stopper  31  positioned at the engagement position can be fixed to the female screw  26   b  of the body portion  26  with the screw  33 , as illustrated in  FIGS. 6A and 6B . More specifically, a user passes the screw  33  through the through hole  26   a  of the body portion  26 , and through the through hole  31   c  of the first stopper  31 . The user then screw-fits the screw  33  to the female screw  26   b , and thereby can fix the first stopper  31  to the body portion  26 , at the engagement position. That is, the first stopper  31  is positioned by the screw  33  with respect to the female screw  26   b  of the body portion  26  so that the first stopper  31  is retained at the engagement position. In this state, a user cannot move the holding portion  27   b , and thus the trailing edge regulation plate  24  is fixed. 
     Thus, since the positional displacement of the trailing edge regulation plate  24  can be prevented by reliably fixing the trailing edge regulation plate  24  with respect to the base plate  21   a  of the cassette body  21 , print precision can be improved and the occurrence of jam can be reduced. In addition, fixing the first stopper  31  with respect to the body portion  26  by the screw can achieve simplification, downsizing, and cost reduction of the sheet supporting apparatus, compared to a configuration in which a plurality of female screws are disposed at, for example, positions corresponding to standard sizes of sheets in the feeding cassette  2 . 
     In addition, when the sheet size is often changed, the trailing edge regulation plate  24  is used without the screw  33  that fixes the trailing edge regulation plate  24 . This can improve usability. 
     In addition, although the first stopper  31  is fixed at the engagement position with the screw  33  and the female screw  26   b  in the present embodiment, other fixing methods may be employed. For example, the first stopper  31  may be fixed to the body portion  26  with another fixing component, such as a snap ring. 
     Second Embodiment 
     Next, a second embodiment of the present invention will be described. In the second embodiment, the first stopper  31  of the first embodiment can be fixed by another configuration. Thus, the same component as that of the first embodiment is omitted in the drawings, or described with the same symbol given to the drawings. 
     As illustrated in  FIGS. 7A and 7B , a trailing edge regulation plate  124  includes a box-shaped body portion  126 , the plate portion  28 , the lever portion  27 , and a spacer  34  that serves as a regulation portion. The body portion  126  is provided with an insertion hole  126   a  formed in a portion of the body portion  126  opposite to the plate portion  28 , and the spacer  34  can be inserted into the insertion hole  126   a . The spacer  34  is formed in a snap-fit structure. In this structure, the spacer  34  can be held by the body portion  126  by a projection  34   a  of the spacer  34  engaging with the body portion  126 , and can be elastically deformed when pulled out. 
     Here, the first stopper  31  is positioned at the engagement position such that a predetermined gap SP is present between a top surface  131   d  of the first stopper  31  and a top plate  126   c  of the body portion  126 , and is moved from the engagement position toward the separation position so as to reduce the gap SP. When a user fixes the trailing edge regulation plate  124 , the user first positions the first stopper  31  at the engagement position and then inserts the spacer  34  into the insertion hole  126   a  of the body portion  126 . With this configuration, the above-described gap SP between the first stopper  31  and the body portion  126  is filled with the spacer  34 . 
     That is, the spacer  34  is placed in the gap SP, and thereby regulates the movement of the first stopper  31  from the engagement position to the separation position. Thus, because the first stopper  31  is fixed with respect to the body portion  126  so that the first stopper  31  is retained at the engagement position, and because the positional displacement of the trailing edge regulation plate  24  can be prevented, print precision can be improved and the occurrence of jam can be reduced. In addition, because the spacer  34  can be attached and detached without using any tool, fixing and releasing the trailing edge regulation plate  124  can be easily performed, and thus usability can be further improved. 
     The fixing of the trailing edge regulation plate with the spacer  34  in the present embodiment may be combined with the fixing of the trailing edge regulation plate with the screw  33  in the first embodiment, to achieve a configuration in which the trailing edge regulation plate can be fixed by using any method of spacer fixing and screw fixing. With this, usability can be improved. 
     Third Embodiment 
     Next, a third embodiment of the present invention will be described. In the third embodiment, the first stopper  31  of the first or the second embodiment can be fixed by another configuration. Thus, the same component as that of the first or the second embodiment is omitted in the drawings, or described with the same symbol given to the drawings. 
     As illustrated in  FIGS. 8A, 8B, and 8C , a lock lever  35  that serves as a moving member and a regulation portion is supported by the body portion  26  of a trailing edge regulation plate  224  such that the lock lever  35  can pivot on an axis extending in a vertical direction. The vertical direction serves as a second direction that is a moving direction of the first stopper  31 . Here, the trailing edge regulation plate  224  can be moved in the sheet conveyance direction that serves as a first direction orthogonal to the vertical direction. At the upper end of the lock lever  35 , a concave portion  35   a  is formed which can be accessed by using, for example, a tool. The lock lever  35  is pivoted between a first position illustrated in  FIG. 8B  and a second position illustrated in  FIG. 8C , by a user operating the concave portion  35   a . The lock lever  35  includes a lock portion  35   b  extending from a center of the shaft of the lock lever  35  toward a radial direction of the shaft. When the lock lever  35  is positioned at the first position, the lock portion  35   b  is positioned between the first stopper  31  and the top plate  26   c  of the body portion  26 . 
     When a user fixes the trailing edge regulation plate  224  with respect to the cassette body  21  (see  FIG. 2 ), the user positions the first stopper  31  at the engagement position and positions the lock lever  35  at the first position, as illustrated in  FIG. 8B . With this configuration, the lock portion  35   b  of the lock lever  35  enters the gap SP between the first stopper  31  and the top plate  26   c  of the body portion  26 . The lock portion  35   b  interfere with the first stopper  31  when the first stopper  31  moves from the engagement position toward the separation position, thus regulating the movement of the first stopper  31 . That is, the first stopper  31  is positioned with the lock portion  35   b  with respect to the body portion  26  so that the first stopper  31  is retained at the engagement position. 
     In order to move the trailing edge regulation plate  224  with respect to the cassette body  21 , a user operates the concave portion  35   a  through the through hole  26   a  (see  FIG. 8A ) of the body portion  26  to position the lock lever  35  at the second position, as illustrated in  FIG. 8C . With this configuration, the lock portion  35   b  of the lock lever  35  is separated away from the gap SP between the first stopper  31  and the top plate  26   c  of the body portion  26 , and allows the first stopper  31  to move from the engagement position to the separation position. 
     Thus, fixing and releasing of the trailing edge regulation plate  124  to and from the body portion  26  can be easily performed without providing any additional member. This improves usability. In addition, the form of the concave portion  35   a  may be modified as appropriate to pivot the lock lever  35  by using only a dedicated tool. With this configuration, specific and limited users can fix or release the trailing edge regulation plate  224 . 
     Although the present invention is applied, in any of the embodiments described above, to the trailing edge regulation plate that regulates the position of the trailing edge of the sheets, the present invention is not limited to this. For example, the present invention may be applied to the side edge regulation plates  22  and  23  that regulate the positions of the side edges of the sheets. 
     Also, although the description is made, in any of the embodiments describe above, for the case where the electrophotographic printer  1  is used, the present invention is not limited to this. For example, the present invention may also be applied to an ink-jet image forming apparatus that forms images on sheets by injecting ink from a nozzle. 
     Also, although the description is made, in any of the embodiments described above, for the configuration in which the first stopper  31  is locked at the engagement position, the present invention is not limited to this. For example, the first stopper  31  may be locked at a position between the engagement position and the separation position as long as the first stopper  31  is not pulled out of the positioning hole  29 . 
     OTHER EMBODIMENTS 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2016-152178, filed Aug. 2, 2016, which is hereby incorporated by reference herein in its entirety.