Patent Publication Number: US-11396437-B2

Title: Sheet feeding apparatus and image forming apparatus

Description:
BACKGROUND 
     Field 
     The present disclosure relates to a sheet feeding apparatus that feeds a sheet and an image forming apparatus including the sheet feeding apparatus. 
     Description of the Related Art 
     Conventionally, there is an image forming apparatus that includes a sheet feeding apparatus that feeds a sheet to an image forming unit, and an image is formed on the sheet. This type of image forming apparatus is widespread. 
     As the sheet feeding apparatus, there is a type of sheet feeding apparatus that includes a sheet drawer serving as a sheet storage unit. The sheet drawer is removably inserted in a main body of an image forming apparatus, and a sheet stacking board on which sheets are stacked is disposed inside the sheet drawer. The sheet stacking board is pivoted to keep the height of the stacked sheets substantially uniform, and a feeding member, such as a feeding roller, feeds a sheet to an image forming unit. 
     Japanese Patent Application Laid-Open No. 2010-64845 discusses a configuration in which a friction plate that comes into contact with a sheet is disposed at a sheet stacking board as a separation unit. 
     In Japanese Patent Application Laid-Open No. 2010-64845, a frictional force that is exerted by bringing the lowermost sheet of a sheet bundle stacked on the sheet stacking board into contact with the friction plate prevents simultaneous feeding (overlap feeding) of a plurality of sheets by the feeding member. 
     However, in the configuration in which the separation unit is disposed at the sheet stacking board, the following matter is raised. When a plurality of sheets (a sheet bundle) is stacked on the sheet stacking board, the sheet bundle cannot be stacked at a desired position because the sheet bundle is caught on the separation unit due to contact between the lowermost sheet of the sheet bundle and the separation unit. If the sheet bundle cannot be stacked at the desired position, a feeding error may occur during sheet feeding. 
     SUMMARY 
     The present disclosure is directed to a sheet feeding apparatus and an image forming apparatus that reliably feed a sheet even in a case where a separation unit is disposed at a sheet stacking board. 
     According to an aspect of the present disclosure, a sheet feeding apparatus includes a stacking member on which sheets are to be stacked, a feeding member configured to feed the sheets stacked on the stacking member, and a moving device configured to move the stacking member between a first position where the feeding member and the sheets stacked on the stacking member are in contact with each other, and a second position where the feeding member and the sheets stacked on the stacking member are not in contact with each other, wherein the stacking member includes a separation unit and an opening portion, wherein the separation unit is disposed at a position facing the feeding member and configured to separate the sheets, and the opening portion is disposed upstream from the separation unit in a sheet feeding direction of feeding by the feeding member, wherein the moving device includes a slope portion having a slope along which the sheets are guided toward the separation unit, wherein, in a state where the stacking member is at the first position, the slope portion is disposed at a position lower than the separation unit in a vertical direction, and wherein, in a state where the stacking member is at the second position, the slope portion is disposed to protrude via the opening portion to be higher than a stacking surface of the stacking member. 
     Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional diagram illustrating an image forming apparatus according to a first exemplary embodiment. 
         FIG. 2  is a perspective diagram illustrating a configuration of a sheet feeding apparatus according to the first exemplary embodiment. 
         FIG. 3  is a cross-sectional diagram illustrating a configuration of the sheet feeding apparatus according to the first exemplary embodiment. 
         FIG. 4  is an enlarged diagram illustrating a part including a slope of the sheet feeding apparatus according to the first exemplary embodiment. 
         FIG. 5  is a cross-sectional diagram illustrating a configuration of the sheet feeding apparatus according to the first exemplary embodiment. 
         FIG. 6  is a cross-sectional diagram illustrating a configuration of a sheet feeding apparatus according to a second exemplary embodiment. 
         FIG. 7A  is an enlarged diagram illustrating a part including a slope of the sheet feeding apparatus according to the second exemplary embodiment.  FIG. 7B  is an enlarged diagram illustrating the part including the slope of the sheet feeding apparatus according to the second exemplary embodiment as viewed from the back side. 
         FIG. 8  is a cross-sectional diagram illustrating a configuration of the sheet feeding apparatus according to the second exemplary embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Some embodiments of the present disclosure will be described in detail below as examples, with reference to the drawings. However, characteristics such as sizes, materials, shapes, and relative positions of components to be described in each of the embodiments may be appropriately modified depending on a configuration and various conditions of an apparatus to which the present disclosure is applied. In other words, these characteristics are not intended to limit the scope of the present disclosure to the following embodiments. 
     [Overall Configuration] 
     An image forming apparatus including a sheet feeding apparatus according to a first exemplary embodiment of the present disclosure will be described with reference to  FIGS. 1 to 4 . An overall configuration of the image forming apparatus, a configuration of the sheet feeding apparatus, and effects of a slope portion will be described in this order. Here, as an example of the image forming apparatus, a laser beam printer will be described. In the laser beam printer, toner images of colors each on a corresponding one of photosensitive drums are sequentially transferred to a belt, and the toner images transferred on the belt are collectively transferred to a recording material. 
     (Overall Configuration of Image Forming Apparatus) 
     An overall configuration of the image forming apparatus will be described with reference to  FIG. 1 .  FIG. 1  is a schematic cross-sectional diagram illustrating the image forming apparatus. In the present exemplary embodiment, an image forming apparatus  101  includes a sheet feeding apparatus  200 . The sheet feeding apparatus may be, for example, a feeding deck that stores a large number of sheets, as an optional apparatus that can be attached on the image forming apparatus  101 . 
     A sheet S stored inside a sheet drawer  201  is fed by a feeding roller  202  that is a feeding member that rotates in a clockwise direction in  FIG. 1 . The fed sheet S is sent to a conveyance nip area which is formed by a conveyance roller  250  and a conveyance opposed roller  252 . The sheet S is then sent to a transfer nip area which is formed by an in-belt roller  105  and a transfer roller  122  with an intermediate transfer belt  130  interposed between the in-belt roller  105  and the transfer roller  122 . 
     Photosensitive drums  111 ,  112 ,  113 , and  114 , each of which is an image bearing member included in a corresponding one of image forming units, rotate in a counterclockwise direction in  FIG. 1 . In each of the image forming units, an electrostatic latent image is formed on an outer peripheral surface of the photosensitive drum by a laser beam emitted from a laser scanner  120 , and the electrostatic latent image is developed by a development roller, so that a toner image is formed. The toner image formed on the photosensitive drum is primary transferred to the intermediate transfer belt  130 . In a case where a color image is formed, color toner images of yellow, magenta, cyan, and black are developed on the photosensitive drums  111 ,  112 ,  113 , and  114 , and the toner images thus formed on the respective photosensitive drums are sequentially transferred to the intermediate transfer belt  130 . Subsequently, the toner images formed on the intermediate transfer belt  130  are secondary transferred to the sheet S sent to the nip portion between the in-belt roller  105  and the transfer roller  122 . 
     The sheet S to which the toner images have been transferred is sent to a nip portion between a fixing film  107  and a pressure roller  108 , and the toner images are fixed to the sheet S by application of heat and pressure at the nip portion. The sheet S to which the toner images are fixed is discharged by discharge rollers  109  and  110 . 
     (Configuration of Sheet Feeding Apparatus) 
     The sheet feeding apparatus will be described with reference to  FIG. 2 .  FIG. 2  is a perspective diagram illustrating a configuration of the sheet feeding apparatus  200 . 
     In the sheet feeding apparatus according to the present exemplary embodiment, a system using a separation roller is employed as a sheet feeding system. The feeding roller  202  that is a feeding member is supported by a holder  205  that is a holding member. The holder  205  is vertically pivotable around the center of a feed roller  203  that is a conveyance member. The sheet drawer  201  is a storage device removably inserted in the sheet feeding apparatus  200  and capable of storing a plurality of sheets S. The sheet drawer  201  includes a sheet stacking board  206  that is a stacking member on which a plurality of sheets (a sheet bundle) can be stacked, and the sheets S are stacked on the sheet stacking board  206 . 
     In the sheet feeding apparatus  200 , the feeding roller  202  can abut on the uppermost surface of the stacked sheets S. Further, a torque limiter (not illustrated) is disposed at the central axis of a separation roller  204  that is a separation member. The feeding roller  202  and the feed roller  203  are rotated by receiving a driving force transmitted from a drive source (not illustrated). 
     The feeding roller  202  rotates to feed the uppermost sheet S. In a case where only one sheet S is fed by the rotation, a large rotation torque is applied to the separation roller  204  via the sheet S at a nip portion formed by the separation roller  204  and the feed roller  203 , and consequently, the torque limiter disengages. Therefore, the separation roller  204  rotates by following the sheet S being conveyed. In a case where the two or more sheets S are fed by the feeding roller  202 , only a frictional force between the two or more sheets S is transmitted to the separation roller  204 , and consequently, the torque limiter does not disengage. As a result, the separation roller  204  does not rotate. Accordingly, the sheet(s) S except for the sheet S on the feed roller  203  side is stopped. In this way, the separation roller  204  can reliably separate and feed the sheets S one by one. 
     The sheet drawer  201  includes a drawer frame  207 , and the sheet stacking board  206  that is a pivotable support member attached to the drawer frame  207  to support the sheets S. The sheet drawer  201  further includes a lift arm  208  that pivots the sheet stacking board  206 . The sheet drawer  201  is inserted into the image forming apparatus  101  from the front side of the image forming apparatus  101 . 
     The sheet stacking board  206  is supported by the drawer frame  207  to be pivotable around a pivot shaft  213 . The lift arm  208  that is a pivot member that pivots the sheet stacking board  206  is supported by the drawer frame  207  and pivots around a lift arm bearing  211 . One end of the lift arm  208  is engaged with the lift arm bearing  211 , and the other end is fixed to a lift arm drive gear  209 . Here, the lift arm  208  and the lift arm bearing  211  form a moving device that moves the sheet stacking board  206 . 
     An interface gear  218  disposed on the sheet drawer  201  is in engagement with the lift arm drive gear  209 . Inserting the sheet drawer  201  into a main body of the image forming apparatus  101  causes the interface gear  218  on the sheet drawer  201  to come into engagement with an interface gear  217  on the apparatus main body, which brings a drive system into an engagement state. In this state, the lift arm  208  pivots around the lift arm bearing  211  by receiving a driving force transmitted from a drive source (not illustrated) disposed inside the main body of the image forming apparatus  101 , and consequently, the sheet stacking board  206  is pivoted to a position for allowing the uppermost surface of the sheets S to be fed. Here, when the sheet stacking board  206  is at a position where the sheets S stacked on the sheet stacking board  206  and the feeding roller  202  are in contact with each other, this position is referred to as a first position. Further, when the sheet stacking board  206  is at a position where the sheets S stacked on the sheet stacking board  206  and the feeding roller  202  are not in contact with each other, this position is referred to as a second position. 
     A plurality of conveyance rollers  250  and a plurality of conveyance opposed rollers  252  are disposed in a sheet width direction that is a direction intersecting a sheet conveyance direction as illustrated in  FIG. 2 . Specifically, the conveyance rollers  250  are a conveyance roller  250   a , a conveyance roller  250   b , a conveyance roller  250   c , and a conveyance roller  250   d . The conveyance opposed rollers  252  are a conveyance opposed roller  252   a , a conveyance opposed roller  252   b , a conveyance opposed roller  252   c , and a conveyance opposed roller  252   d.    
     The sheet drawer  201  includes a drawer grip  212  that is a gripping portion that can be gripped by a user. When the user holds and draws the drawer grip  212  in a frontward direction of the main body of the image forming apparatus  101 , the interface gear  218  on the drawer frame  207  and the interface gear  217  on the apparatus main body are released from engagement. As a result, the sheet stacking board  206  falls to the lower end. In the present exemplary embodiment, the second position is a position where the sheet stacking board  206  is at the lower end in a vertical direction (a substantially vertical direction that is substantially orthogonal to a horizontal direction). Then, the user further draws the sheet drawer  201  to the outside of the main body of the image forming apparatus  101 , and can stack the sheets S. 
     The sheet drawer  201  includes a separation pad  220  that is a separation unit, on the sheet stacking board  206 . The separation pad  220  is disposed on the downstream-end side of the sheet stacking board  206 . The sheet drawer  201  further includes a slope portion  221  at a position immediately upstream from the separation pad  220 . The slope portion  221  is disposed at the lift arm  208 . 
     The slope portion  221  will be described with reference to  FIGS. 3 to 5 .  FIG. 3  is a cross-sectional diagram illustrating the sheet drawer  201  in a state where the sheet stacking board  206  is at the second position.  FIG. 4  is an enlarged perspective diagram illustrating a part including the slope portion  221 . The separation pad  220  is disposed at a position facing the feeding roller  202 , and protrudes to be higher than a sheet stacking surface of the sheet stacking board  206 . The sheet stacking board  206  has an opening portion  206   a . The slope portion  221  disposed at the lift arm  208  protrudes to be higher than the sheet stacking surface, via the opening portion  206   a . The slope portion  221  and the separation pad  220  are in such a relationship that the apex of the slope portion  221  is at a position higher than the separation pad  220  in a height direction. 
     An inclined surface  221   a  and atop surface  221   b  of the slope portion  221  protrude from the opening portion  206   a  of the sheet stacking board  206 . Further, the top surface  221   b  is at a position higher than the top surface of the separation pad  220  in the substantially vertical direction. The inclined surface  221   a  (a slope) is configured (used) to gradually rise from the upstream side to the downstream side in a sheet insertion direction A to guide a sheet inserted in the sheet insertion direction A to the separation pad  220 . 
     When the sheet S is inserted in the sheet insertion direction A from the front side of the main body of the image forming apparatus  101 , the leading edge of the sheet S is guided to the top surface of the separation pad  220  by the inclined surface  221   a  and the top surface  221   b , without being caught on the separation pad  220 . Therefore, during stacking of a sheet bundle on the sheet stacking board  206 , the sheet bundle can be prevented from being caught on the separation pad  220 , which occurs when the lowermost sheet of the sheet bundle and the separation pad  220  are brought into contact with each other, and therefore the sheet bundle can be stacked at a desired position. 
       FIG. 5  is a diagram illustrating a state where the sheet stacking board  206  is pivoted by the lift arm  208  to the position for allowing the sheet S to be fed. As illustrated in  FIG. 5 , the slope portion  221  is between a pressing portion of the lift arm  208  and the lift arm bearing  211 . The sheet stacking board  206  is at the first position while being supported by the pressing portion pressing the sheet stacking board  206 . At the first position, the top surface  221   b  of the slope portion  221  does not protrude to be higher than the sheet stacking board  206 , and in the present exemplary embodiment, the top surface  221   b  of the slope portion  221  is inside the opening portion  206   a.    
     In other words, the slope portion  221  is at a position lower than the top surface of the separation pad  220  in the substantially vertical direction. As a result, the lowermost sheet S of the stacked sheets S is reliably in contact with the separation pad  220 , and therefore overlap feeding can be prevented by a frictional force of the separation pad  220 . 
     If the slope portion  221  is disposed at the sheet stacking board  206 , the lowermost sheet S can be raised by the slope portion  221 . This leads to unstable contact between the lowermost sheet S and the separation pad  220 , and consequently, overlap feeding of sheets may occur. 
     As described above, according to the present exemplary embodiment, the leading edge of the sheet S is not caught on the separation pad  220  when the sheet S is inserted into the sheet drawer  201 . The leading edge of the sheet S can be therefore prevented from being caught, and the sheet S can be smoothly inserted. 
     Further, in the state where the sheet stacking board  206  is pivoted by the lift arm  208  to the position for allowing the sheet S to be fed, the slope portion  221  retracts from the top surface of the separation pad  220  in the substantially vertical direction. As a result, the lowermost sheet S can be reliably brought into contact with the separation pad  220  without coming into contact with the slope portion  221 , and therefore overlap feeding can be prevented. 
     In the present exemplary embodiment, the lift arm  208  is provided with the slope portion  221  as a separate component. However, the present disclosure is not limited to such a configuration, and is also applicable to a configuration in which a slope shape is directly formed on the lift arm  208 . 
     In the first exemplary embodiment, the slope portion  221  is fixed to the lift arm  208 . In a second exemplary embodiment, a slope portion is provided at a lift arm and supported to be slidable with respect to a sheet stacking board. Configurations similar to those of the first exemplary embodiment will be provided with the same reference numerals as those of the first exemplary embodiment and described. 
     An image forming apparatus including a sheet feeding apparatus according to the second exemplary embodiment will be described with reference to  FIGS. 6 to 8 .  FIG. 6  is a diagram illustrating a state where a sheet drawer  301  is drawn to the outside of the main body of an image forming apparatus  101 , and the sheet stacking board  306  is lowered to the lower end without being pivoted (a second position).  FIG. 7A  is an enlarged diagram illustrating a part including a slope portion  321 , and  FIG. 7B  is an enlarged diagram illustrating the part in  FIG. 7A , as viewed from the back side of the main body. 
     The slope portion  321  includes a fixed portion  321   a  and an inclined portion  321   b . The fixed portion  321   a  is fixed to a lift arm  308 , and the inclined portion  321   b  is disposed to be pivotable around a pivot shaft  321   c , with respect to a bearing  321   d . The inclined portion  321   b  includes an inclined surface  321   e , a top surface  321   f , and a slide portion  321   g , and is supported to be slidable with respect to an opening portion  306   a  of the sheet stacking board  306  by the slide portion  321   g.    
     A separation unit  320  is disposed at a position facing a feeding roller  302  of the sheet stacking board  306 , and has a convex shape to be higher than a sheet stacking surface. The slope portion  321  is disposed at the lift arm  308 . The inclined surface  321   e  and the top surface  321   f  of the slope portion  321  protrude from the opening portion  306   a  of the sheet stacking board  306 , and further, the top surface  32  if is at a position higher than the top surface of the separation unit  320  in a substantially vertical direction. When a sheet S is inserted from the front side of the main body of the image forming apparatus  101  in an arrow-B direction, the leading edge of the sheet S is guided to the top surface of the separation unit  320  by the inclined surface  321   e  and the top surface  321   f , without being caught on the separation unit  320 . 
       FIG. 8  is a diagram illustrating a state where the sheet stacking board  306  is pivoted by the lift arm  308  to a position for allowing the sheet S to be fed (a first position). The slope portion  321  slides toward the upstream side in a feeding direction, in the opening portion  306   a . The top surface  321   f  of the slope portion  321  which has moved toward the upstream side in the feeding direction is at a position lower than the top surface of the separation unit  320  in the substantially vertical direction. Accordingly, the lowermost sheet S of the stacked sheets S easily comes in contact with the separation unit  320 , and therefore occurrence of overlap feeding can be prevented by a frictional force of the separation unit  320 . 
     As described above, according to the present exemplary embodiment, as with the first exemplary embodiment, the leading edge of the sheet S is not caught on the separation unit  320  when the sheet S is inserted into the sheet drawer  301 . Therefore, the leading edge of the sheet S can be prevented from being caught, and the sheet S can be smoothly inserted. Further, in the state where the sheet stacking board  306  is pivoted by the lift arm  308  to the position for allowing the sheet S to be fed, the slope portion  321  retracts from the top surface of the separation unit  320  in the substantially vertical direction. As a result, the lowermost sheet S can be reliably brought in contact with the separation unit  320 , and therefore overlap feeding can be prevented. 
     Embodiment(s) of the present disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may include one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random access memory (RAM), a read-only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure 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. 2019-102859, filed May 31, 2019, which is hereby incorporated by reference herein in its entirety.