Patent Publication Number: US-10322896-B2

Title: Sheet supporting apparatus and image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a sheet supporting apparatus configured to support a sheet, and an image forming apparatus equipped with the sheet supporting apparatus. 
     Description of the Related Art 
     Generally, an image forming apparatus such as a printer is equipped with a sheet feed cassette storing sheets, a manual sheet feeding portion configured to feed a manually fed sheet, and a sheet conveyance path through which the sheet fed from the manual sheet feeding portion is conveyed. The sheet conveyance path is arranged above the sheet feed cassette. Japanese Unexamined Patent Application Publication No. 2013-180864 proposes an image forming apparatus designed such that if a sheet is jammed in the sheet conveyance path, the sheet feed cassette is drawn out, and a conveyance guide member constituting a portion of the sheet conveyance path is drawn out, to ensure a wide space for performing jam removal processing. 
     Since a conveyance guide member is arranged above the sheet feed cassette within the apparatus body, visibility of the conveyance guide member is poor. Therefore, Japanese Unexamined Patent Application Publication No. 2006-69732 proposes an image forming apparatus equipped with a release lever configured to release a lock of the conveyance guide member with respect to the apparatus body. If a user operates the release lever, the lock of the conveyance guide member is released and the sheet conveyance path is opened. 
     However, the release lever disclosed in the above-mentioned Japanese Unexamined Patent Application Publication No. 2006-69732 is configured such that it can be operated when the sheet feed cassette is attached to the apparatus body. Therefore, if the release lever is operated by the user when the sheet feed cassette is attached to the apparatus body, there was a risk of the conveyance guide member falling onto the sheet feed cassette and causing damage to the conveyance guide member or the sheet feed cassette. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a sheet supporting apparatus includes an apparatus body, a sheet supporting portion attached detachably with respect to the apparatus body, and configured to support a sheet, a conveyance guide supported movably with respect to the apparatus body between a guide position where the conveyance guide guides the sheet being conveyed above the sheet supporting portion attached to the apparatus body and a lowered position that is positioned lower than the guide position, a retention portion supported movably with respect to the apparatus body between a retaining position where the retention portion retains the conveyance guide at the guide position and an allowing position where the retention portion allows the conveyance guide to move from the guide position to the lowered position, and a regulation mechanism configured to regulate a movement of the retention portion to the allowing position from the retaining position in a state where the sheet supporting portion is attached to the apparatus body and configured to allow the retention portion to move to the allowing position from the retaining position in a state where the sheet supporting portion is removed from the apparatus body. 
     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 entire schematic diagram illustrating a printer according to a present embodiment. 
         FIG. 2  is a perspective view illustrating a configuration of a sheet feeding unit. 
         FIG. 3  is a perspective view illustrating a cassette. 
         FIG. 4  is a cross-sectional view illustrating a state in which the cassette is drawn out from a printer body. 
         FIG. 5  is a cross-sectional view illustrating a lower conveyance guide moved to a lowered position. 
         FIG. 6A  is a cross-sectional view illustrating a state in which a locking member is positioned at a second locking position. 
         FIG. 6B  is a cross-sectional view illustrating a state in which the locking member is moved to a second releasing position. 
         FIG. 6C  is a cross-sectional view illustrating a state in which a release lever is moved to a first releasing position. 
         FIG. 7A  is a cross-sectional view illustrating a state in which the cassette is drawn out from the printer body. 
         FIG. 7B  is a cross-sectional view illustrating a state in which a pressing surface and a protruding portion are abutted against one another. 
         FIG. 7C  is a cross-sectional view illustrating a state in which the locking member is positioned at the second locking position by a regulating surface. 
         FIG. 8  is an entire schematic diagram illustrating a printer of a modified example of the embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     General Arrangement 
     First, an embodiment of the present invention will be described. A printer  10  serving as an image forming apparatus is a laser beam printer adopting an electro-photographic system configured to form a monochromatic toner image. As illustrated in  FIG. 1 , the printer  10  includes a sheet feeding unit  30  configured to feed supported sheets, and an image forming unit  40  configured to form an image on the sheet being fed. The printer  10  further includes a fixing unit  44  configured to fix the image being transferred to the sheet, a sheet discharge portion  60  capable of discharging sheets onto a sheet discharge tray  62 , and a manual sheet feeding portion  36  capable of feeding the manually fed sheet. 
     If an instruction to form an image is output to the printer  10 , an image forming process by the image forming unit  40  is started, based on image information entered from an external computer and the like connected to the printer  10 . The image forming unit  40  includes a process cartridge  41 , a laser scanner  42 , and a transfer roller  43 . The process cartridge  41  is configured of a photosensitive drum  45  and a process unit acting on the photosensitive drum  45  which are formed as an integrated cartridge, and the process cartridge is attached in a detachable manner to a printer body  10 A serving as an apparatus body. 
     The laser scanner  42  irradiates a laser beam toward the photosensitive drum  45  based on the entered image information. The photosensitive drum  45  is charged in advance by a charging unit not shown, and when the laser beam is irradiated on the photosensitive drum  45 , an electrostatic latent image is formed on the photosensitive drum  45 . Thereafter, the electrostatic latent image is developed by a developing unit not shown, and a monochromatic toner image is formed on the photosensitive drum  45 . 
     In parallel with the image forming process, a sheet S stored in a cassette  31  serving as a sheet supporting portion of the sheet feeding unit  30  is fed by a pickup roller  32 . A sheet supporting plate  33  capable of being lifted and lowered is provided on the cassette  31 , and in a state where the sheets are fed, the sheet S supported on the sheet supporting plate  33  contacts the pickup roller  32 . The sheet S fed by the pickup roller  32  is separated one sheet at a time by a separation roller pair  32   a , and conveyed to a transfer conveyance path  51  toward a registration roller pair  20 . Only one cassette  31  is provided in the present embodiment, but it is possible to provide a plurality of cassettes capable of supporting different sized sheets, so that sheets can be fed from a plurality of cassettes according to the selected sheet size. 
     Further, it is possible to feed a sheet S from the manual sheet feeding portion  36 , instead of feeding the sheet S from the sheet feeding unit  30 . The manual sheet feeding portion  36  includes a manual feed tray  34  configured to support a sheet S, and a feed roller  35  configured to feed the sheet S supported on the manual feed tray  34 . The sheet S fed by the feed roller  35  is guided along a manual feed conveyance path  37  to the registration roller pair  20 . 
     A toner image on the photosensitive drum  45  is transferred by electrostatic load bias applied on the transfer roller  43  on a first side, i.e., upper surface, of a sheet S subjected to skew feed correction by the registration roller pair  20  and conveyed at a predetermined conveyance timing. The sheet S on which a toner image has been transferred is subjected to predetermined heat and pressure by a heating roller  46  and a pressure roller  47  of the fixing unit  44 , by which the toner is melted and fixed. The sheet S having passed through the fixing unit  44  is conveyed by a conveyance roller pair  58  to a discharge conveyance path  53 , and discharged through a sheet discharge roller pair  61  to the sheet discharge tray  62 . 
     If images are to be formed on both sides of the sheet S, a guide member  56  pivots downward, and the sheet S is guided to a reverse conveyance path  55 . The sheet S guided to the reverse conveyance path  55  is switched back by a reverse conveyance roller pair  57 , and conveyed to a duplex conveyance path  54 . The sheet S conveyed through the duplex conveyance path  54  is conveyed again to the transfer conveyance path  51  by a plurality of conveyance roller pairs. Then, an image is formed to a second side, i.e., rear side, of the sheet S by the image forming unit  40  in a manner similar to the first side, and discharged to the sheet discharge tray  62 . 
     Sheet Feeding Unit 
     As illustrated in  FIGS. 2 and 3 , the sheet feeding unit  30  serving as a sheet supporting apparatus includes left and right cassette guides  90 L and  90 R provided as a part of the printer body  10 A, and a lower conveyance guide  80  constituting a portion of the manual feed conveyance path  37 . Further, the sheet feeding unit  30  includes a second retention portion  75 R described later (refer to  FIG. 4 ), and a regulation mechanism  100 . 
     In the following description, the members having reference numbers followed by the letter “L” or “R” are a pair of members, each of which is disposed on the left or the right side in a width direction orthogonal to the sheet conveyance direction, and if one of the pair of members is described, the description of the other one of the pair of members may be omitted or not shown in the drawings. 
     The cassette guides  90 L and  90 R are arranged on an outer side in the width direction of the cassette  31  attached to the printer body  10 A, and guide grooves  91 L and  91 R and cassette guide grooves  93 L and  93 R are formed on inner sides in the width direction of the cassette guides  90 L and  90 R respectively. First rails  38 L and  38 R are formed on both sides in the width direction of a frame  31   a  of the cassette  31 , and in a state where the first rails  38 L and  38 R are engaged with the cassette guide grooves  93 L and  93 R serving as a guide portion, the cassette  31  is guided in an attachment/detachment direction, which is approximately a horizontal direction. 
     Further, a second rail  39  is formed on one side of the frame  31   a  in the width direction. The second rail includes a regulating surface  39   a  extending in an attachment direction of the cassette  31 , and a pressing surface  39   b  disposed in an inclined manner with respect to the regulating surface  39   a  from a downstream end of the regulating surface  39   a  in the attachment direction. That is, the pressing surface  39   b  is extended in a direction inclined with respect to the attachment direction of the cassette  31 . 
     Meanwhile, as illustrated in  FIGS. 2 and 4 , the manual feed conveyance path  37  is composed of an upper conveyance guide  70 , and the lower conveyance guide  80  serving as the conveyance guide opposed to the upper conveyance guide  70 . The lower conveyance guide  80  includes projected portions  83 L and  83 R provided upstream in the attachment direction and projected portions  84 L and  84 R provided downstream in the attachment direction, which are projected from both sides in the width direction. The projected portions  83 L and  83 R are respectively engaged with the guide grooves  91 L and  91 R formed on the cassette guides  90 L and  90 R. The cassette guides  90 L and  90 R respectively pivotably support link members  92 L and  92 R, and the projected portions  84 L and  84 R are supported by a leading end portion of the link members  92 L and  92 R. 
     That is, as illustrated in  FIGS. 4 and 5 , the lower conveyance guide  80  is guided between a guide position (refer to  FIG. 4 ) and a lowered position (refer to  FIG. 5 ) with respect to the cassette guides  90 L and  90 R through the guide grooves  91 L and  91 R and the link members  92 L and  92 R. The guide position is a position where the lower conveyance guide  80  constitutes a part of the manual feed conveyance path  37  above the cassette  31  which is attached to the printer body  10 A and guides the sheet S fed from the manual sheet feeding portion  36 . The lowered position is positioned lower than the guide position, and it is a position where the lower conveyance guide  80  interferes with the cassette  31  if the cassette is attached to the printer body  10 A but does not contact the cassette  31  if the cassette is drawn out from the printer body  10 A. 
     The upper conveyance guide  70  supports the conveyance rollers  71  and  72  in a rotatable manner, and further supports a first retention portion  74 R and a second retention portion  75 R. The lower conveyance guide  80  rotatably supports driven rollers  81  and  82  that are respectively driven to rotate by the conveyance rollers  71  and  72 . The first retention portion  74 R is capable of retaining a projected portion  84 R of the lower conveyance guide  80  positioned at the guide position. The second retention portion  75 R serving as a retention portion is pivotable between a retaining position where the second retention portion  75 R retains a projected portion  83 R of the lower conveyance guide  80  positioned at the guide position, and an allowing position where the second retention portion  75 R allows the lower conveyance guide  80  to move to the lowered position so as to release the retained state of the projected portion  83 R. 
     That is, the lower conveyance guide  80  is retained at the guide position by the first retention portion  74 R, and the second retention portion  75 R positioned at the retaining position. Then, if the second retention portion  75 R pivots from the retaining position to the allowing position, the lower conveyance guide  80  drops by its own weight while being guided by the guide grooves  91 L and  91 R and the link members  92 L and  92 R, and moves to the lowered position. 
     Therefore, if a sheet is jammed in the manual feed conveyance path  37 , at first, the cassette  31  is drawn out. Thereafter, a user operates a release lever  95  of the regulation mechanism  100  described later provided on the cassette guide  90 R, by which the second retention portion  75 R pivots from the retaining position to the allowing position. Thereby, the lower conveyance guide  80  is moved from the guide position to the lowered position, and a space is formed within the sheet feeding unit  30  to perform a jam removal processing, according to which the jam removal processing can be facilitated. 
     Regulation Mechanism 
     Next, the regulation mechanism  100 , which is a main part of the present invention, will be described. The regulation mechanism  100  includes, as illustrated in  FIG. 2 , the release lever  95  slidable in the attachment/detachment direction of the cassette  31  with respect to the cassette guide  90 R serving as the support member, and a locking member  94  pivotably supported on the cassette guide  90 R. 
     The release lever  95  serving as a first lock portion can be moved in sliding motion between a first locking position where the release lever  95  locks the second retention portion  75 R at the retaining position and a first releasing position where the release lever  95  releases the lock of the second retention portion  75 R and the release lever  95 . That is, if the user presses the release lever  95  in an arrow direction illustrated in FIG. from the first locking position to the first releasing position, the second retention portion  75 R is configured to pivot from the retaining position to the allowing position. The release lever  95  and the second retention portion  75 R can be connected directly to be interlocked with one another, or the release lever  95  and the second retention portion  75 R can be connected indirectly with a different member intervened therebetween. According to the present embodiment, the release lever  95  presses the second retention portion  75 R to the retaining position by the release lever  95  being returned to the first locking position, but it is also possible to provide an urging member that urges the release lever  95  to the first locking position or the second retention portion  75 R to the retaining position. 
     The locking member  94  serving as a second lock portion is supported pivotably around a pivot shaft  94   a  with respect to the cassette guide  90 R, as illustrated in  FIGS. 2, 6 and 7 , and a protruding portion  94   b  protruding toward an inner side in the width direction is formed on the locking member  94 . An arc-shaped long hole  101  is formed around the pivot shaft  94   a  on the cassette guide  90 R, and the protruding portion  94   b  of the locking member  94  passes through the long hole  101  and extends toward a middle of the sheet feeding unit  30  in the width direction. The locking member  94  is restricted from moving between the second locking position and the second releasing position by the engagement of the long hole  101  and the protruding portion  94   b . That is, the locking member  94  pivots in up-down directions intersecting the attachment/detachment direction of the cassette  31 . 
     The locking member  94  positioned at the upper second locking position locks the release lever  95  to the first locking position. Therefore, in a state where the locking member  94  is positioned at the second locking position, the release lever  95  cannot be moved from the first locking position to the first releasing position. Further, the locking member  94  positioned at the lower second releasing position releases the lock of the release lever  95  and the locking member  94 . The protruding portion  94   b  of the locking member  94  is arranged to be able to contact the second rail  39  serving as a regulation portion provided on the cassette  31 . 
     Next, with reference to  FIGS. 6 and 7 , the movement of the locking member  94  interlocked with the attachment and detachment operation of the cassette  31  will be described. As illustrated in  FIG. 7A , in a state where the cassette  31  is drawn out from the cassette guide  90 R, the second rail  39  and the protruding portion  94   b  are not in contact with each other. In this state, the locking member  94  is positioned at the lower second releasing position by its own weight, and as illustrated in  FIGS. 6B and 6C , the release lever  95  can be pressed and operated. 
     Then, if the cassette  31  is moved toward the cassette guide  90 R for attachment, as illustrated in  FIG. 7B , at first, the pressing surface  39   b  of the second rail  39  comes into contact with the protruding portion  94   b , and the protruding portion  94   b  moves gradually upward along the long hole  101  by the pressing surface  39   b . Then, as illustrated in  FIG. 7C , if the protruding portion  94   b  moves onto the regulating surface  39   a  from the pressing surface  39   b , the locking member  94  will be positioned at the second locking position. At this time, the locking member  94  locks the release lever  95  to the first locking position as illustrated in  FIG. 6A , so that the user cannot press and move the release lever  95  to the first releasing position. Further, the regulating surface  39   a  is extended in the attachment direction of the cassette  31 , and retains the locking member  94  to the first locking position until the cassette  31  is completely attached to the printer body  10 A. 
     As described, in the state where the cassette  31  is attached and during attachment and detachment of the cassette  31 , the release lever  95  cannot be moved to the first releasing position, so that the second retention portion  75 R will not move to the allowing position. Therefore, the lower conveyance guide  80  is securely retained at the guide position by the second retention portion  75 R, and the lower conveyance guide  80  is prevented from falling toward the cassette  31  positioned below the lower conveyance guide  80 . Therefore, it becomes possible to prevent the cassette  31  and the lower conveyance guide from being in contact with one another, and causing damage to the cassette  31  or the lower conveyance guide  80 . 
     Further, in a state where the cassette  31  is removed from the printer body  10 A, the locking member  94  moves to the second releasing position by its own weight, and the release lever  95  can be moved in sliding motion from the first locking position to the first releasing position. Then, if the user serving as an operator presses the release lever  95  to the first locking position, the second retention portion  75 R is moved from the retaining position to the allowing position so as to allow the lower conveyance guide  80  to move to the lowered position, according to which jam removal processing can be facilitated. 
     According to the present embodiment, the lower conveyance guide  80  is moved toward the lowered position by its own weight as a result of releasing the retention of the lower conveyance guide  80  by the second retention portion  75 R, but the configuration is not restricted thereto, and a configuration can be adopted where the lower conveyance guide  80  is moved toward the lowered position using an elastic member and the like. 
     According to the present embodiment, a configuration is adopted where the lower conveyance guide  80  is guided by guide grooves  91 R and  91 L and link members  92 R and  92 L provided on the cassette guides  90 R and  90 L, in order to create a wide space for performing the jam removal processing from the viewpoint of usability. However, the present embodiment is not restricted to such configuration, and any configuration can be adopted as long as the lower conveyance guide  80  can be moved. 
     According further to the present embodiment, the release lever  95  and the locking member  94  are supported by the cassette guide  90 R, and the guide groove  91 R and the cassette guide groove  93 R are formed on the same cassette guide  90 R. The operation of the release lever  95  can be restricted more reliably by determining the relationship of the respective members with respect to the cassette guide  90 R formed as a single component, but the present embodiment is not restricted to such configuration. 
     According further to the present embodiment, the release lever  95  is provided on an upstream surface  102  of the cassette guide  90 R in the attachment direction of the cassette  31 , as illustrated in  FIG. 2 , to adopt a configuration that ensures a long area of movement of the release lever  95 , but the release lever  95  can be arranged at any position. 
     According further to the present embodiment, the first rails  38 L and  38 R and the second rail  39  are configured as separate members, but they can be configured integrally. 
     Furthermore, the directions of movement of the second retention portion  75 R, the release lever  95  and the locking member  94  are not restricted, they can be moved in sliding motion or pivoting motion, and any configuration can be adopted as long as the movement of the second retention portion  75 R is restricted in an interlocked manner with the second rail  39  provided on the cassette  31 . 
     The present embodiment adopts a configuration where the movement of the lower conveyance guide  80  constituting the manual feed conveyance path  37  is restricted, but the configuration is not restricted thereto. For example, as according to a printer  110  of a modified example illustrated in  FIG. 8 , the present invention can be adopted in a configuration that regulates movement of a lower conveyance guide  180  constituting the duplex conveyance path  54  through which the sheet to which an image has been formed by the image forming unit  40  is guided again to the image forming unit  40 . 
     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. 2016-242427, filed Dec. 14, 2016, which is hereby incorporated by reference wherein in its entirety.