Patent Publication Number: US-11662675-B2

Title: Image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an image forming apparatus for forming an image on a recording material. 
     Description of the Related Art 
     In electrophotographic image forming apparatuses, such as copying machines, multifunction machines, and laser beam printers, a toner image formed on a photosensitive member such as a photosensitive drum is transferred to a recording material by a transfer member such as a transfer roller. The photosensitive member and other members arranged in a circumference of the photosensitive member for carrying out the electrophotographic process, such as a developing unit or a charging unit, are configured as a process cartridge that can be integrally attached to and detached from an apparatus body of the image forming apparatus. The user can easily attach or detach the process cartridge when carrying out maintenance operations, such as replacing the process cartridge or removing jammed sheets. 
     When the transfer member is in contact with the photosensitive member when attaching and detaching the process cartridge, the force applied from the transfer member to the photosensitive member may deteriorate operability during attachment or detachment. Japanese Patent Application Laid-Open Publication No. H04-66963 discloses a printer provided with a front cover that can be opened and closed with respect to a printer body and an opening/closing lever for unlocking the front cover from the printer body, wherein by operating the opening/closing lever, a part of the opening/closing lever causes the transfer roller to separate from the photosensitive drum within the printer body. 
     According to the document mentioned above, a configuration has been adopted in which the opening/closing lever presses a shaft of the transfer roller directly. However, in a case where the front cover and the transfer roller are arranged distantly due to arrangement limitations, if the opening/closing lever disclosed in the above document is arranged on both sides of the transfer roller in the axial direction, space for moving the opening/closing lever will be required on both sides in the axial direction of the transfer roller, which leads to increased size of the image forming apparatus. Thus, a configuration is awaited in which a mechanism for moving the transfer member in accordance with a movement of the opening/closing member can be arranged in a space-saving manner. 
     SUMMARY OF THE INVENTION 
     The present invention provides an image forming apparatus provided with a space-saving configuration by which a transfer member can be moved in accordance with a movement of an opening/closing member. 
     According to an aspect of the invention, an image bearing member configured to bear an image, an apparatus body including a transfer member configured to transfer the image borne on the image bearing member to a recording material, the transfer member being movable between a first position in which the transfer member is in contact with the image bearing member and a second position in which the transfer member is separated from the image bearing member, and an opening/closing member arranged on a side portion of the apparatus body on a first side in a first direction and movable between an open position and a closed position with respect to the apparatus body, the first direction being a direction orthogonal to a rotational axis direction of the image bearing member, wherein the apparatus body further includes a movement mechanism configured to move the transfer member in accordance with a movement of the opening/closing member, and wherein the movement mechanism includes a first movable member configured to move toward the first side in the first direction in accordance with the movement of the opening/closing member from a closed position to an open position, the first movable member being configured to move a first end portion of the transfer member from the first position to the second position during a movement of the first movable member toward the first side in the first direction, the first movable member being provided on a first side, on which the first end portion is provided, in the rotational axis direction, and a second movable member configured to move in a second direction along the rotational axis direction in accordance with the movement of the first movable member toward the first side in the first direction, the second movable member being configured to move a second end portion of the transfer member from the first position to the second position during a movement of the second movable member in the second direction, the second end portion being provided on a second side opposite from the first side in the rotational axis direction. 
     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 a schematic view of an image forming apparatus according to a first embodiment. 
         FIG.  2    is a perspective view of a transfer roller according to the first embodiment. 
         FIG.  3    is a cross-sectional view of a transfer roller and a photosensitive drum according to the first embodiment. 
         FIG.  4    is a schematic view of a separation mechanism in a first state according to the first embodiment. 
         FIG.  5    is a schematic view of the separation mechanism in a second state according to the first embodiment. 
         FIG.  6    is a view illustrating an area including a first bearing and a separation lever according to the first embodiment. 
         FIG.  7    is a view illustrating an area including the first bearing and the separation lever according to the first embodiment. 
         FIG.  8    is a perspective view illustrating a part of a separation rod according to the first embodiment. 
         FIGS.  9 A and  9 B  are each an illustration of a part of the separation lever and the separation rod according to the first embodiment. 
         FIGS.  10 A and  10 B  are each an illustration of a part of a second bearing and the separation rod according to the first embodiment. 
         FIG.  11    is a schematic view illustrating a separation mechanism in a first state according to a second embodiment. 
         FIG.  12    is a schematic view illustrating the separation mechanism in a second state according to the second embodiment. 
         FIG.  13    is a schematic view illustrating the separation mechanism in a third state according to the second embodiment. 
         FIG.  14    is a view illustrating a part of the separation mechanism in the first state according to the second embodiment. 
         FIG.  15    is a view illustrating a part of the separation mechanism in the second state according to the second embodiment. 
         FIG.  16    is a view illustrating a part of the separation mechanism in the third state according to the second embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereafter, embodiments according to the present disclosure will be described with reference to the drawings. 
     In the following description and drawings, a perpendicular direction, i.e., gravity direction, in a state in which the image forming apparatus is installed on a horizontal plane is referred to as a Z direction or vertical direction. A rotational axis direction of an image bearing member, i.e., electrophotographic photosensitive member, of the image forming apparatus is referred to as a Y direction. A direction intersecting Y and Z directions is referred to as an X direction. The X, Y, and Z directions are preferably mutually intersecting directions perpendicularly to each other. Further, regarding structures, shapes, and arrangements of attachable/detachable members in the image forming apparatus are described by referring to the X, Y, and Z directions based on a state in which the components are assembled to the image forming apparatus, unless denoted otherwise. 
     First Embodiment 
     Image Forming Apparatus 
       FIG.  1    is a schematic view illustrating a cross-sectional structure of an image forming apparatus  1  according to a first embodiment. The image forming apparatus  1  according to the present embodiment is an electrophotographic printer that forms an image on a recording material S through an electrophotographic process based on an image information received from an external device connected via a network and an execution command for forming an image. Various sheets can be used as the recording material S, including paper such as normal paper and thick paper, plastic films, cloth, coated paper and other sheet materials subjected to surface treatment, sheet materials having special shapes such as envelopes and index paper, and other various types of sheets having different sizes and made of different materials. 
     The image forming apparatus  1  includes a drum-type electrophotographic photosensitive member, hereinafter referred to as photosensitive drum  8 , serving as an image bearing member. The photosensitive drum  8  is configured by disposing a photosensitive material such as organic photoconductor (OPC), amorphous selenium, and amorphous silicon on a cylindrical drum base body made for example of aluminum or nickel. The photosensitive drum  8  is supported by an apparatus body  1 A of the image forming apparatus  1  in a manner rotatable about a rotational axis extending in the Y direction and driven to rotate at a predetermined speed by a driving source. In the circumference of the photosensitive drum  8  are arranged a charging member  80 , a developing member  81 , and a transfer roller  9  serving as a transfer member, in the named order in a rotational direction of the photosensitive drum  8 . Above the photosensitive drum  8  is arranged a scanner unit  7  serving as an exposing unit. 
     The photosensitive drum  8 , the charging member  80 , and the developing member  81  constitute a process cartridge  6  that can be integrally attached to and detached from the apparatus body  1 A. A door member  13  serving as an opening/closing member that can be opened and closed with respect to the apparatus body  1 A is disposed on one side of the process cartridge  6  in the X direction. By opening the door member  13 , attachment and detachment of the process cartridge  6  to and from the apparatus body  1 A is allowed from one side in the X direction (i.e., from a downstream side in a first direction described below). 
     The apparatus body  1 A refers to a part of the image forming apparatus  1  excluding the process cartridge  6  and the door member  13 , and for example, it includes a metal plate constituting the frame body of the image forming apparatus  1 . In the image forming apparatus  1 , the one side of the X direction in which the door member  13  is provided is a front side (a side portion) of the image forming apparatus  1 , and the opposite side is the rear side of the image forming apparatus  1 . 
     The image forming apparatus  1  further includes a sheet feed cassette  2 , a feed roller  3 , a conveyance roller pair  4 , a registration roller pair  5 , a fixing unit  10 , a sheet discharge roller pair  11 , and a sheet discharge tray  12 , in the named order along a main conveyance path  1 P of the recording material S. The main conveyance path  1 P is a conveyance path, i.e., conveyance space, through which the recording material S is conveyed within the image forming apparatus  1  during image forming operation, and denotes a conveyance path, or conveyance space, leading to the sheet discharge roller pair  11  from the sheet feed cassette  2  accommodating the recording material S. 
     The sheet feed cassette  2  is arranged below the process cartridge  6 . The registration roller pair  5 , the photosensitive drum  8 , the transfer roller  9 , and the fixing unit  10  are arranged along a portion of the main conveyance path  1 P extending approximately in the X direction between the process cartridge  6  and the sheet feed cassette  2  in the Z direction. The sheet discharge tray  12  serving as a supporting portion on which the recording material S having an image formed thereon is supported is provided on an upper surface portion of the apparatus body  1 A, positioned above the process cartridge  6  and the scanner unit  7 . 
     The sheet feed cassette  2  accommodates the recording material S in a stacked state. The feed roller  3 , the conveyance roller pair  4 , the registration roller pair  5 , the fixing unit  10 , and the sheet discharge roller pair  11  constitute a conveyance system in which the recording material S is conveyed within the image forming apparatus  1 . The fixing unit  10  also functions as a fixing portion for fixing the image transferred to the recording material S by the transfer roller  9 . 
     The image forming apparatus  1  according to the present embodiment adopts a conveyance path configuration in which the main conveyance path  1 P of the recording material S forms an approximately S-shaped curve when viewed in the Y direction, which is the rotational axis direction of the photosensitive drum  8 . That is, when viewed in the Y direction, the recording material S is fed to one side in a horizontal direction, i.e., the X direction, from the sheet feed cassette  2 , and has an image transferred and fixed thereto while being conveyed on the main conveyance path  1 P to the other side in the horizontal direction, i.e., the X direction, above the sheet feed cassette  2 . Then, the recording material S is discharged to one side in the horizontal direction, i.e., the X direction, by the sheet discharge roller pair  11 , and stacked on the sheet discharge tray  12  provided on the upper surface portion of the apparatus body  1 A. 
     The process cartridge  6  is attached to an attachment space between the main conveyance path  1 P and the sheet discharge tray  12 , specifically between the main conveyance path  1 P and the scanner unit  7 , in the Z direction within the apparatus body  1 A. By opening the door member  13  to one side in the X direction, the attachment space is opened to one side in the X direction with respect to the external space of the image forming apparatus  1  and the process cartridge  6  is exposed when viewed from one side in the X direction. In this state, the user can access the process cartridge  6  from one side in the X direction to perform attachment and detachment operations. 
     Image Forming Operation 
     An image forming operation by the image forming apparatus  1  will be described. At first, the photosensitive drum  8  is driven to rotate, and the surface of the photosensitive drum  8  is charged to predetermined polarity and predetermined potential by the charging member  80 . The scanner unit  7  performs an exposing process based on the image information received from an external device to the charged surface of the photosensitive drum  8 , and the charge in the exposed portion is eliminated, by which an electrostatic latent image is formed on the surface of the photosensitive drum  8 . The electrostatic latent image is developed using developer containing toner by the developing member  81  and visualized as a toner image. The toner image borne on the photosensitive drum  8  is transferred by the transfer roller  9  to the recording material S. The transfer roller  9  is urged toward the photosensitive drum  8 , and a transfer nip portion N 1  is formed between the transfer roller  9  and the photosensitive drum  8 . That is, the transfer roller  9  forms the transfer nip portion N 1  with the image bearing member and performs a transfer operation of transferring the image from the photosensitive drum  8  to the recording material S at the transfer nip portion N 1 . 
     The recording material S is fed one sheet at a time by the feed roller  3  from the sheet feed cassette  2  and conveyed via the conveyance roller pair  4  to the registration roller pair  5 . After performing skew correction of the recording material S, the registration roller pair  5  conveys the recording material S to the transfer nip portion N 1  at a timing synchronized with the forming of toner image by the process cartridge  6 . 
     The recording material S on which the toner image has been transferred by passing the transfer nip portion N 1  is subjected to a fixing process of toner image by the fixing unit  10 . The fixing unit  10  adopts a thermal fixing system including a fixing roller and a pressure roller that nip and press the recording material S, and a heater such as a halogen lamp or an induction heating mechanism for heating the toner image via the fixing roller. The toner image is heated, pressed and softened while passing through the nip portion between the fixing roller and the pressure roller, and thereafter cooled and hardened, by which the image fixed to the recording material S is obtained. The recording material S having passed through the fixing unit  10  is discharged by the sheet discharge roller pair  11  from the apparatus body  1 A and stacked on the sheet discharge tray  12 . 
     When forming images on both sides of the recording material S, the recording material S having an image formed on a first side by passing through the transfer nip portion N 1  and the fixing unit  10  is subjected to switch back by the sheet discharge roller pair  11  and sent to a reconveyance path  1 R below the main conveyance path  1 P. The recording material S having reached the registration roller pair  5  is passed through the transfer nip portion N 1  and the fixing unit  10  again, by which an image is formed to a second side, before being discharged by the sheet discharge roller pair  11 . 
     Separation Mechanism of Transfer Roller 
     Next, a separation mechanism  90  for having the transfer roller  9  contact and separate from the photosensitive drum  8  will be described.  FIG.  2    is a perspective view of the transfer roller  9 .  FIG.  3    is a cross-sectional view in which the photosensitive drum  8  and the transfer roller  9  are cut by a plane perpendicular to the X direction. 
     As illustrated in  FIGS.  2  and  3   , the transfer roller  9  includes a shaft portion  9   b  extending in the Y direction, and a tubular roller body  9   a  that is supported by the shaft portion  9   b . One end portion, which is referred to as a first end portion  9   b   1  hereinafter, of the shaft portion  9   b  on one side (i.e., first side) in the Y direction is supported rotatably by a first bearing  21 . The other end portion, which is referred to as a second end portion  9   b   2  hereinafter, of the shaft portion  9   b  on the other side (i.e., second side) in the Y direction is supported rotatably by a second bearing  22 . The first bearing  21  and the second bearing  22  are respectively supported movably in the Z direction by bearing supporting portions of the apparatus body  1 A. 
     The first bearing  21  and the second bearing  22  are respectively urged by a spring  31  and a spring  32  serving as pressing portions, i.e., urging members, for pressing the transfer nip portion N 1  in a direction in which the rotational axis of the transfer roller  9  approaches the rotational axis of the photosensitive drum  8 . In a state where the transfer roller  9  is positioned at a contact position described below, an outer circumference surface of the roller body  9   a  is set to be in pressure contact with the photosensitive drum  8  by a predetermined pressurizing force by the urging force of the springs  31  and  32 . Further, the first bearing  21  and the second bearing  22  respectively have boss shapes  21   a  and  22   a.    
       FIGS.  4  and  5    are schematic views illustrating the separation mechanism  90  serving as a movement mechanism according to the present embodiment.  FIG.  4    illustrates a state in which the door member  13  is at a closed position and the transfer roller  9  is at a contact state, which is hereinafter referred to as a first state of the separation mechanism  90 .  FIG.  5    illustrates a state where the door member  13  is at an opened position and the transfer roller  9  is at a separation state, which is hereinafter referred to as a second state of the separation mechanism  90 . The contact state of the transfer roller  9  is a state in which the transfer roller  9  is in pressure contact by a predetermined pressurizing force with the photosensitive drum  8 , and the separation state of the transfer roller  9  is a state in which the transfer roller  9  is separated from the photosensitive drum  8 . In other words,  FIG.  4    illustrates a state of the image forming apparatus  1  in which the transfer roller  9  is at a first position, also referred to as a contact position, in contact with the photosensitive drum  8 , and  FIG.  5    illustrates a state of the image forming apparatus  1  in which the transfer roller  9  is at a second position, also referred to as a separation position, separated from the photosensitive drum  8 . 
     As described above, the separation mechanism  90  is configured to move the transfer roller  9  from the contact position to the separation position along with the opening operation of the door member  13 . Further, the separation mechanism  90  according to the present embodiment moves the transfer roller  9  from the separation position to the contact position along with the closing operation of the door member  13 . 
     As illustrated in  FIG.  4   , the separation mechanism  90  includes a separation lever  41  serving as a first movable member, i.e., first separation member, a separation rod  42  serving as a second movable member, i.e., second separation member, and a link unit  43 . The boss shapes  21   a  and  22   a  ( FIG.  2   ) which are projections formed on the first bearing  21  and the second bearing  22  of the transfer roller  9  also function as a part of the separation mechanism  90 . The separation lever  41  is connected via the link unit  43  to the door member  13  and is also connected to the first bearing  21  of the transfer roller  9 . The separation rod  42  is connected to the separation lever  41  and is also connected to the second bearing  22  of the transfer roller  9 . 
     In the separation mechanism  90 , the separation lever  41  and the link unit  43  are arranged on one side (i.e., first side) in the Y direction with respect to the space in which the process cartridge  6  and the main conveyance path  1 P are arranged in the image forming apparatus  1 . Specifically, the separation lever  41  and the link unit  43  are positioned on an outer side and on one side in the Y direction with respect to an image forming area of the photosensitive drum  8  in the Y direction, which is a maximum area of a main scanning direction in which the scanner unit  7  can form an electrostatic latent image, for example. That is, the separation lever  41  is connected to the door member  13  through an outside in the Y direction with respect to the main conveyance path  1 P of the recording material S. Further, at least a part of the separation lever  41  and the link unit  43  is overlapped with the registration roller pair  5  and a conveyance guide g 1  ( FIG.  1   ) that forms the main conveyance path  1 P of the recording material S via the transfer nip portion N 1  when viewed in the Y direction. Further, the separation rod  42  is arranged within a space below the main conveyance path  1 P and above the sheet feed cassette  2 , specifically above the reconveyance path  1 R. That is, the separation rod  42  is arranged below the conveyance guide g 1  that guides a lower surface of the recording material S being conveyed toward the transfer nip portion N 1 . 
     The door member  13  includes a rotation shaft  13   a  (refer also to  FIG.  1   ), disposed at a lower edge portion thereof, that is rotatably supported by a bearing portion of the apparatus body  1 A, the door member capable of being opened and closed with respect to the apparatus body  1 A by pivoting about a rotational axis extending in the Y direction passing through the rotation shaft  13   a . An outer surface  13   b  of the door member  13  is an exterior that constitutes one side surface of the image forming apparatus  1  in the X direction. As illustrated in  FIGS.  1  and  4   , a position in which the outer surface  13   b  of the door member  13  is approximately perpendicular is referred to as a closed position of the door member  13 . As illustrated in  FIG.  5   , a position in which the door member  13  is pivoted from the closed position to one side in the X direction is referred to as an open position of the door member  13 . In the present embodiment, the door member  13  is configured to pivot approximately 90 degrees from the closed position to the open position. 
     The separation lever  41  is supported by the apparatus body  1 A and is capable of moving in parallel, i.e., slide movement, in a D 1  direction and a D 2  direction that are orthogonal to the Y direction, which is the rotational axis direction of the transfer roller  9 . The D 1  direction is a direction along the X direction, and it is a direction along a direction in which the door member  13  moves from the closed position toward the open position. The D 2  direction is a direction along the X direction, and it is a direction along a direction in which the door member  13  moves from the open position toward the closed position. The D 1  and D 2  directions are a first direction of the present embodiment. The D 1  direction is a direction toward a first side in the first direction according to the present embodiment, and the D 2  direction is a direction opposite to the D 1  direction, i.e., a direction toward a second side opposite to the first side in the first direction. 
     The separation rod  42  is a member that is supported by the apparatus body  1 A and that is elongated in the Y direction, which is the rotational axis direction of the transfer roller  9 , and the separation rod  42  is capable of moving in parallel, i.e., slide movement, in a D 3  direction and a D 4  direction along the Y direction. The D 3  direction is a direction along the Y direction and directed from the first bearing  21  toward the second bearing  22 . The D 4  direction is a direction along the Y direction and directed from the second bearing  22  toward the first bearing  21 . The D 3  and D 4  directions are a second direction of the present embodiment. The D 3  direction is a direction toward one side in the second direction of the present embodiment, and the D 4  direction is a direction opposite to the D 3  direction, i.e., a direction toward another side opposite to the one side in the second direction. 
     The link unit  43  connects the door member  13  and the separation lever  41 , and the link unit  43  is configured to move the separation lever  41  in the D 1  direction in accordance with an opening operation of the door member  13 , and to move the separation lever  41  in the D 2  direction in accordance with a closing operation of the door member  13 . The link unit  43  according to the present embodiment includes three members, which are a first link  43   a , a second link  43   b , and a third link  43   c . The first link  43   a  is attached to the door member  13  and connected pivotably to the second link  43   b . The second link  43   b  includes a boss b 1  on the D 2  direction side with respect to the coupling portion with the first link  43   a , and the second link  43   b  is connected to the third link  43   c  by having the boss b 1  serving as the projection portion engage with a long hole c 1  of the third link  43   c . The third link  43   c  includes the long hole c 1  at the end portion on the D 1  direction side, and the third link  43   c  is connected to the separation lever  41  at the end portion on the D 2  direction side. 
     When the door member  13  moves from the closed position ( FIG.  4   ) to the open position ( FIG.  5   ), the first link  43   a  pivots together with the door member  13 , and the second link  43   b  moves in the D 1  direction by being pulled by the first link  43   a . By having the boss b 1  of the second link  43   b  engage with the end portion on the D 1  direction side of the long hole c 1  of the third link  43   c , the third link  43   c  is also moved in the D 1  direction. By the movement of the third link  43   c  in the D 1  direction, the separation lever  41  moves in the D 1  direction. 
     When the door member  13  moves from the open position ( FIG.  5   ) to the closed position ( FIG.  4   ), the first link  43   a  pivots together with the door member  13 , and the second link  43   b  is pushed back by the first link  43   a  to move in the D 2  direction. Since the boss b 1  of the second link  43   b  moves in the D 2  direction inside the long hole c 1  of the third link  43   c , the third link  43   c  will not receive force in the D 2  direction from the second link  43   b . The third link  43   c  moves in the D 2  direction in accordance with the closing operation of the door member  13  by having the end portion in the D 1  direction pushed by the first link  43   a  or the door member  13  in the D 2  direction. Alternatively, an urging member such as a spring that urges the third link  43   c  in the D 2  direction can be arranged, and the third link  43   c  can move in the D 2  direction by the urging force of the urging member in accordance with the closing operation of the door member  13 . 
     As described, by the separation lever  41  moving in the D 1  direction or the D 2  direction along with the opening and closing operation of the door member  13 , a separation operation or a contact operation of the transfer roller  9  as described hereafter is performed. 
     Movement of First Bearing 
     Next, a movement of the first bearing  21  of the transfer roller  9  in accordance with the opening and closing operation of the door member  13  will be described with reference to  FIGS.  6  and  7   .  FIGS.  6  and  7    illustrate an area including the first bearing  21  and the separation lever  41  are viewed in the Y direction, wherein  FIG.  6    corresponds to a state in which the transfer roller  9  is in the contact position, and  FIG.  7    corresponds to a state in which the transfer roller  9  is in the separation position. 
     As illustrated in  FIGS.  6  and  7   , the separation lever  41  includes an inclined surface portion  41   a  and a lock portion  41   b , and a boss  41   c  which is a connecting portion connected to an end portion of the link unit  43 . The inclined surface portion  41   a , i.e., first inclined surface, and the lock portion  41   b  can contact a boss shape  21   a , i.e., first contact portion, of the first bearing  21  from above. The inclined surface portion  41   a  is an inclined surface inclined upward toward the downstream side in the D 1  direction when viewed in the Y direction. That is, the inclined surface portion  41   a  is inclined toward an upstream side, i.e., D 2  direction, in the direction of movement of the separation lever  41  in accordance with the opening operation of the door member  13  in a direction, i.e., third direction, in which the rotational axis of the transfer roller  9  is separated from the rotational axis of the photosensitive drum  8 . The inclined surface portion  41   a  of the separation lever  41  and the boss shape  21   a  of the first bearing  21  function as a first cam portion which is a translation cam (i.e., linear motion cam) that converts a movement of the separation lever  41  in the D 1  direction accompanying the opening of the door member  13  to a movement in a downward direction which is a direction separating the transfer roller  9  from the photosensitive drum  8 . Alternately, a first inclined surface whose normal direction is opposite to that of the inclined surface portion  41   a  of the present embodiment can be provided on the first bearing  21 , and a boss-shaped first contact portion that comes into contact with the first inclined surface can be provided on the separation lever  41 . 
     The lock portion  41   b  is a surface that extends in the D 2  direction at an approximately fixed height from an end portion at the D 2  direction side of the inclined surface portion  41   a , that is, a lower end portion of the inclined surface portion  41   a . The height of the lock portion  41   b  corresponds to a height of an upper surface of the boss shape  21   a  in a state where the first bearing  21  is at a position corresponding to the separation position of the transfer roller  9 . The end portion at the D 1  direction side of the inclined surface portion  41   a  extends to a position higher than the upper surface of the boss shape  21   a  corresponding to the contact position of the transfer roller  9 . The movement of the first bearing  21  to the D 1  and D 2  directions is regulated. 
     As described, in a state where the door member  13  is at the closed position, the separation lever  41  is positioned at the D 2  direction side within the movement range. In this state, as illustrated in  FIG.  6   , the transfer roller  9  is in pressure contact with the photosensitive drum  8  by the urging force of the spring  31  mentioned above in a state where the inclined surface portion  41   a  of the separation lever  41  is separated upward from the boss shape  21   a  of the first bearing  21 . 
     When the door member  13  is being opened, the separation lever  41  moves in the D 1  direction in accordance with a movement of the door member  13 . The separation lever  41  moves while pressing the boss shape  21   a  of the first bearing  21  downward by the inclined surface portion  41   a , thereby moving the first bearing  21  downward, that is, moving the transfer roller  9  in the direction separating from the photosensitive drum  8 . Then, before the separation lever  41  reaches a position corresponding to the open position of the door member  13 , the boss shape  21   a  slips beneath the lock portion  41   b , and the first bearing  21  is retained at a position corresponding to the separation position of the transfer roller  9 . That is, the separation lever  41  serving as a first movable member moves in the D 1  direction, i.e., toward the first side in the first direction, along with the opening operation of the door member  13 , by which the first end portion  9   b   1  of the transfer roller  9  is moved from the contact position to the separation position. 
     Meanwhile, when the door member  13  is closed, the separation lever  41  moves in the D 2  direction in accordance with a movement of the door member  13 . In this state, after the lock portion  41   b  is released from the boss shape  21   a , the first bearing  21  is gradually moved upward while maintaining contact between the boss shape  21   a  and the inclined surface portion  41   a . When the transfer roller  9  comes into contact with the photosensitive drum  8 , the movement of the first bearing  21  is stopped. The first bearing  21  will be retained at a position corresponding to the contact position of the transfer roller  9  by the urging force of the spring  31 . 
     As described, the separation lever  41  is configured to move in the X direction orthogonal to the rotational axis of the transfer roller  9  by receiving force from the door member  13  via the link unit  43 . Then, the separation lever  41  moves the first bearing  21  provided at one end portion of the transfer roller  9  to the position corresponding to the separation position and to the position corresponding to the contact position of the transfer roller  9  in accordance with the opening and closing operation of the door member  13 . 
     Movement of Second Bearing 
     Next, the movement of the second bearing  22  of the transfer roller  9  in accordance with the opening and closing operation of the door member  13  will be described with reference to  FIGS.  8  to  10   .  FIG.  8    is a perspective view illustrating a part of the D 3  direction side, that is, the separation lever  41  side, of the separation rod  42 .  FIGS.  9 A and  9 B  illustrate the separation lever  41  and the separation rod  42  viewed from an upward direction, wherein  FIG.  9 A  corresponds to a state in which the transfer roller  9  is at the contact position and  FIG.  9 B  corresponds to a state in which the transfer roller  9  is at the separation position.  FIGS.  10 A and  10 B  illustrate the separation rod  42  and the second bearing  22  viewed from the door member  13  side in the X direction, wherein  FIG.  10 A  corresponds to a state in which the transfer roller  9  is at the contact position and  FIG.  10 B  corresponds to a state in which the transfer roller  9  is at the separation position. 
     As illustrated in  FIG.  8   , the separation rod  42  includes an engagement portion  42   a  at the end portion on the D 4  direction side, and the engagement portion  42   a  is engaged with a groove portion  41   d  of the separation lever  41  illustrated in  FIG.  9 A . When viewed from above, the groove portion  41   d  is inclined in the D 4  direction side toward the downstream side in the D 1  direction. In other words, the groove portion  41   d  includes an inclined surface  41   d   1 , i.e., second inclined surface, that is inclined toward one side in a sliding direction of the separation rod  42  toward the direction of movement of the separation lever  41  when the door member  13  is opened. The inclined surface  41   d   1  slides against the engagement portion  42   a , i.e., second contact portion, and presses the separation rod  42  in the D 3  direction when the door member  13  is being opened. The movement of the separation rod  42  to the D 1  and D 2  directions is regulated. The groove portion  41   d  of the separation lever  41  and the engagement portion  42   a  of the separation rod  42  function as a second cam portion, which is a translation cam that converts the movement of the separation lever  41  in the D 1  direction and the D 2  direction into the movement of the separation rod  42  in the D 3  direction and the D 4  direction. Alternatively, a second inclined surface having a normal direction opposite to that of the inclined surface  41   d   1  according to the present embodiment can be provided on the separation rod  42 , and an engagement portion, i.e., second contact portion, that comes into contact with the second inclined surface can be provided on the separation lever  41 . 
     As illustrated in  FIG.  10 A , the separation rod  42  includes an inclined surface portion  42   b  and a lock portion  42   c . When viewed in the X direction, the inclined surface portion  42   b  is an inclined surface, i.e., third inclined surface, that is inclined upward toward the downstream side in the D 3  direction. That is, the inclined surface portion  42   b  is inclined toward a side in which the transfer roller  9  is moved away from the photosensitive drum  8  toward the upstream side, i.e., the D 4  direction, in the moving direction of the separation rod  42  in accordance with the opening operation of the door member  13 . The inclined surface portion  42   b  of the separation rod  42  and a boss shape  22   a , i.e., third contact portion, of the second bearing  22  function as a third cam portion, which is a translation cam that converts the movement of the separation rod  42  in the D 3  direction accompanying the opening of the door member  13  to a downward movement of separating the transfer roller  9  from the photosensitive drum  8 . Alternatively, a third inclined surface having a normal direction opposite to that of the inclined surface portion  42   b  according to the present embodiment can be provided on the second bearing  22 , and a third contact portion such as a boss shape that comes into contact with the third inclined surface can be provided on the separation rod  42 . 
     A height of the lock portion  42   c  corresponds to the separation position of the transfer roller  9 . The lock portion  42   c  is a surface that extends in the D 4  direction at an approximately fixed height from an end portion at the D 4  direction side of the inclined surface portion  42   b , that is, a lower end portion of the inclined surface portion  42   b . The end portion at the D 3  direction side of the inclined surface portion  42   b  extends to a position higher than the upper surface of the boss shape  22   a  corresponding to the contact position of the transfer roller  9 . The movement of the second bearing  22  to the D 3  and D 4  directions is regulated. 
     As described, when the door member  13  is at the closed position, the separation lever  41  is positioned at the D 2  direction side position within the movement range. In that state, as illustrated in  FIG.  9 A , the separation rod  42  is positioned at the D 4  direction side position within the movement range. Then, as illustrated in  FIG.  10 A , in a state where the inclined surface portion  42   b  of the separation rod  42  is separated upward from the boss shape  22   a  of the second bearing  22 , the transfer roller  9  is in pressure contact with the photosensitive drum  8  by the urging force of the spring  32  mentioned above. 
     When the door member  13  is opened, the separation lever  41  moves in the D 1  direction in accordance with the door member  13 , as illustrated in  FIG.  9 B . In that state, the engagement portion  42   a  is guided along the groove portion  41   d  of the separation lever  41 , and the separation rod  42  moves in the D 3  direction ( FIG.  9 A  to  FIG.  9 B ). The separation rod  42  moves while pushing down the boss shape  22   a  of the second bearing  22  by the inclined surface portion  42   b , and moves the second bearing  22  downward, that is, in a direction separating the transfer roller  9  from the photosensitive drum  8 . Then, before the separation rod  42  reaches a position corresponding to the open position of the door member  13 , the boss shape  22   a  slips beneath the lock portion  42   c , and the second bearing  22  is retained at a position corresponding to the separation position of the transfer roller  9 . That is, the separation rod  42  serving as a second movable member moves in the D 3  direction, i.e., toward one side in the second direction, along with the movement of the separation lever  41  in the D 1  direction, i.e., toward the first side in the first direction, when the door member  13  is opened, by which the second end portion  9   b   2  of the transfer roller  9  is moved from the contact position to the separation position. 
     Meanwhile, when the door member  13  is closed, the separation lever  41  moves in the D 2  direction in accordance with a movement of the door member  13 . The engagement portion  42   a  is guided along the groove portion  41   d  of the separation lever  41 , and the separation rod  42  is moved in the D 4  direction ( FIG.  9 B  to  FIG.  9 A ). After the lock portion  42   c  is released from the boss shape  22   a , the second bearing  22  is gradually moved upward while maintaining contact between the boss shape  22   a  and the inclined surface portion  42   b . When the transfer roller  9  comes into contact with the photosensitive drum  8 , the movement of the second bearing  22  is stopped. The second bearing  22  will be retained at a position corresponding to the contact position of the transfer roller  9  by the urging force of the spring  32 . 
     As described, the separation rod  42  moves in a direction approximately parallel to the rotational axis of the transfer roller  9 , by which a part of an operation force for opening the door member  13  is transmitted via the separation rod  42  to a side opposite from the link unit  43  and the separation lever  41  in the Y direction. Thereby, the second bearing  22  on the side opposite from the first bearing  21  moved by the separation lever  41  is moved using the operation force of the door member  13 , and the transfer roller  9  can be separated from the photosensitive drum  8  while having the first bearing  21  and the second bearing  22  cooperate with each other. 
     Since a configuration in which the separation rod  42  that is elongated in the Y direction (i.e., a thin and narrow member extending in the Y direction) moves in the direction along the Y direction to transmit the above-mentioned operation force, torsional force and bending force is not easily applied on the separation rod  42 . There is no need to use a metal material having a high strength or to increase the cross-sectional area on the assumption that torsional force or bending force will act on the separation rod  42 , so that a strength required of the separation rod  42  can be ensured while realizing lower cost and saving space. 
     The height of the lock portion  42   c  of the separation rod  42  is determined to correspond to the height of the lock portion  41   b  of the separation lever  41  with the height of the rotational axis of the transfer roller  9  set as reference. That is, in a state where the lock portions  41   b  and  42   c  of the separation lever  41  and the separation rod  42  are in contact with the boss shapes  21   a  and  22   a  of the first bearing  21  and the second bearing  22 , the rotational axis of the transfer roller  9  is in parallel with the rotational axis of the photosensitive drum  8 . 
     Further, inclination angles of the inclined surface portions  41   a  and  42   b  of the separation lever  41  and the separation rod  42  may preferably be set so that the moving velocities of the first bearing  21  and the second bearing  22  in the Z direction in accordance with the opening and closing of the door member  13  are equal. Thereby, the transfer roller  9  separates from the photosensitive drum  8  while maintaining a posture parallel to the photosensitive drum  8  in accordance with the opening operation of the door member  13 . For example, if the inclination angle of the separation lever  41  with respect to the X direction of the groove portion  41   d  is 45 degrees, the ratio of the moving velocity of the separation lever  41  in the D 1  direction to the moving velocity of the separation rod  42  in the D 2  direction accompanying the opening operation of the door member  13  is one to one. In this case, if the inclination angles of the inclined surface portions  41   a  and  42   b  with respect to the horizontal plane are set equal, the first bearing  21  and the second bearing  22  will move downward at the same speed. 
     Summary of Present Embodiment 
     As described, according to the present embodiment, the transfer roller  9  is separated from the photosensitive drum  8  by the separation lever  41  moving in the D 1  direction accompanying the opening operation of the door member  13  and the separation rod  42  moving in the D 3  direction accompanying the movement of the separation lever  41  in the D 1  direction. Thereby, after performing the opening operation of the door member  13 , the process cartridge  6  can be detached or attached without having to perform a special operation for separating the transfer roller  9 , which contributes to improving usability. Further according to the present embodiment, the first end portion of the transfer roller  9  is moved by the separation lever  41  connected to the door member  13 , and the second end portion of the transfer roller  9  is moved by the separation rod  42  connected to the separation lever  41 . Thereby, the separation mechanism  90  for moving both end portions of the transfer roller  9  accompanying the opening operation of the door member  13  can be realized by a space-saving configuration. 
     Further, the space opposite to the separation lever  41  and the link unit  43  in the Y direction within the apparatus body  1 A can be utilized effectively as a space for arranging components other than the separation mechanism  90 . For example, a motor or a drive transmission mechanism for driving the photosensitive drum  8  or the registration roller pair  5  can be arranged in a space opposite to the separation lever  41  and the link unit  43  in the Y direction within the apparatus body  1 A. 
     The present embodiment adopts a configuration in which the link unit  43  is composed of three members ( 43   a ,  43   b , and  43   c ), but a link unit can be composed of one member, for example, as long as it moves the separation lever  41  in the D 1  direction or the D 2  direction in accordance with the opening and closing operation of the door member  13 . Further, the separation lever  41  can be extended in the X direction to be directly connected to the door member  13 . 
     Second Embodiment 
     Next, an image forming apparatus according to a second embodiment will be described with reference to  FIGS.  11  to  16   . Hereafter, elements that have substantially the same configurations and functions as those in the first embodiment are denoted with the same reference numerals as the first embodiment, and descriptions thereof are omitted. 
       FIGS.  11  and  12    are schematic views illustrating a separation mechanism  90  serving as a movement mechanism according to the present embodiment.  FIG.  11    illustrates a contact state in which the transfer roller  9  is positioned at a first position, i.e., contact position.  FIG.  12    illustrates a separation state in which the transfer roller  9  is positioned at the second position, i.e., separation position. 
     In the first embodiment, a configuration has been illustrated in which the transfer roller  9  is not only moved in accordance with the opening operation of the door member  13  but the transfer roller  9  is also moved in accordance with the closing operation of the door member  13 . In contrast, according to the present embodiment, the transfer roller  9  maintains a separation position even when the door member  13  is closed in a state where the transfer roller  9  is positioned at the separation position, and thereafter, the transfer roller  9  is moved from the separation position to the contact position by the driving force of the driving source. 
     As illustrated in  FIG.  11   , a third link  43   d  which is one of the link members constituting a link unit  43  according to the present embodiment includes a long hole c 2  of a long round or oval shape that extends in the D 1  direction and serves as an engagement portion with the separation lever  41 . The boss  41   c  of the separation lever  41  is engaged with the long hole c 2 . 
     Further, a driving gear  44  that serves as a driving unit for driving the separation mechanism  90  after the door member  13  has been closed is arranged below the separation lever  41 . A rack portion  41   e  ( FIG.  14   ) that extends in the D 1  direction is provided on the separation lever  41 , and the driving gear  44  is meshed with the rack portion  41   e . The driving gear  44  is driven by a motor  51  provided on the apparatus body  1 A and moves the separation lever  41  in the D 2  direction. 
     Separation Operation of Transfer Roller 
     An operation of moving the transfer roller  9  from the contact position to the separation position along with the opening operation of the door member  13  will be described with reference to  FIGS.  14  to  16   .  FIGS.  14  to  16    are views illustrating an area including the separation lever  41  and the driving gear  44  in the Y direction.  FIG.  14    illustrates a state in which the door member  13  is at a closed position and the transfer roller  9  is at a contact position.  FIG.  15    illustrates a state where the door member  13  is at an open position.  FIG.  16    illustrates a state immediately after closing of the door member  13  in which the transfer roller  9  is positioned at the separation position. 
     When the door member  13  is opened, similar to the first embodiment, the separation lever  41  is moved in the D 1  direction in accordance with the opening operation of the door member  13  by the link unit  43  ( FIGS.  11  and  12   ). However, in the present embodiment, the long hole c 2  of the separation lever  41  is engaged with the boss  41   c  of the third link  43   d  of the link unit  43  ( FIG.  14   ). Therefore, when the end portion on the D 2  direction side of the long hole c 2  comes into contact with the boss  41   c , the movement of the separation lever  41  in the D 1  direction is started. 
     As illustrated in  FIG.  15   , while the door member  13  moves to the open position, the inclined surface portion  41   a  of the separation lever  41  pushes down the boss shape  21   a  of the first bearing  21 , and the position of the first bearing  21  is determined by the lock portion  41   b . During this operation, the rack portion  41   e  of the separation lever  41  meshes with the driving gear  44 . Along with the movement of the separation lever  41  in the D 1  direction, the separation rod  42  moves in the D 3  direction, the inclined surface portion  42   b  pushes down the boss shape  22   a  of the second bearing  22 , and the position of the second bearing  22  is determined by the lock portion  42   c  ( FIG.  10 A  to  FIG.  10 B ). Thereby, in a state where the door member  13  is at the open position, the transfer roller  9  is positioned at the separation position. 
     When the door member  13  is closed, the third link  43   d  of the link unit  43  is moved in the D 2  direction in accordance with the closing operation of the door member  13  ( FIG.  13   ). However, at a point of time where the door member  13  has reached the closed position, the boss  41   c  of the separation lever  41  is not engaged with either end portions of the long hole c 2  of the third link  43   d , and the separation lever  41  maintains the same position as where it was positioned before the door member  13  has been closed. Therefore, at this point of time, neither the first bearing  21  nor the second bearing  22  has moved from the position where they were positioned before the closing of the door member  13 , and the transfer roller  9  is maintained at the separation position. 
     That is, the separation mechanism  90  of the present embodiment is configured such that the separation lever  41  is moved in the D 1  direction in accordance with the door member  13  via the link unit  43  only during the opening operation among the opening and closing operations of the door member  13 . 
     Contact Operation of Transfer Roller 
     Next, an operation to move the transfer roller  9  from the separation position to the contact position will be described. As illustrated in  FIG.  16   , when the door member  13  is closed in a state where the transfer roller  9  is at the separation position, the driving gear  44  is driven to rotate in a counterclockwise direction in the drawing. Then, the separation lever  41  is driven by the driving gear  44  and moves in the D 2  direction. In this state, the boss  41   c  of the separation lever  41  moves inside the long hole c 2  of the third link  43   d  in the D 2  direction. 
     By the movement of the separation lever  41  in the D 2  direction, the lock portion  41   b  is disengaged from the boss shape  21   a  of the first bearing  21 , and the first bearing  21  moves upward by the urging force of the spring  31 . Further, along with the movement of the separation lever  41  in the D 2  direction, similar to the first embodiment, the separation rod  42  moves in the D 4  direction and the lock portion  42   c  is disengaged from the boss shape  22   a  of the second bearing  22 , and the second bearing  22  moves upward by the urging force of the spring  32  ( FIG.  10 B  to  FIG.  10 A ). Thereby, the movement of the transfer roller  9  from the separation position to the contact position is completed. Further, the length and the position of the rack portion  41   e  is set so that drive transmission from the driving gear  44  to the separation lever  41  is automatically cutoff when the rack portion  41   e  of the separation lever  41  is disengaged from the driving gear  44  after the transfer roller  9  has moved to the contact position. 
     As described, according to the present embodiment, at a point of time when the door member  13  is closed, the transfer roller  9  is positioned at the separation position. Therefore, the transfer roller  9  can be positioned at the separation state during shipping, thereby reducing the demerit of having the photosensitive drum  8  and the transfer roller  9  be in pressure contact with each other for a long time, which may cause deformation of the transfer roller  9  or adhesion of components of the transfer roller  9  to the photosensitive drum  8 . 
     Further according to the present embodiment, a contact timing of the transfer roller  9  and the photosensitive drum  8  can be determined arbitrarily by controlling the operation of the driving gear  44 . The image forming apparatus  1  includes a controller  50  that controls the motor  51  ( FIGS.  14  to  16   ). The controller  50  includes a storage unit that stores control programs for controlling the image forming apparatus  1 , and a processor for reading the control programs from the storage unit and executing the same. The controller  50  is electrically connected with an opening/closing sensor  52  whose detection signal switches according to the opening/closing of the door member  13 , and the controller  50  is connected via a network to communicate with an external device. 
     In order to control a contact timing of the transfer roller  9  and the photosensitive drum  8 , for example, a clutch is interposed between the motor  51  and the driving gear  44 , and the clutch is operated by the controller  50  to enable transmission of drive from the motor  51  to the driving gear  44  to be engaged and disengaged. An electromagnetic clutch operated based on a command signal of the controller  50  or an engaging clutch driven by a solenoid that is operated by a command signal from the controller  50  can be used as the clutch. 
     Based on the detection signal of the opening/closing sensor  52 , the controller  50  instructs to start driving of the process cartridge  6  and start the image forming operation in a state where an execution command to form an image is received from the external device in a state where the door member  13  is closed. In this state, the controller  50  can set the driving of the driving gear  44  to be started at a delayed timing from the starting of drive of the process cartridge  6 . 
     For example, a case is assumed in which the user opens the door member  13 , replaces the process cartridge  6  and closes the door member  13 , and thereafter, enters an execution command of image forming from the external device to the image forming apparatus  1 . In that case, at a point of time when the controller  50  detects that the door member  13  has been closed based on the detection signal of the opening/closing sensor  52 , the driving gear  44  is not driven by the motor  51 , and the transfer roller  9  is retained at the separation position. Thereafter, in a state in which the execution command for image forming is entered, the controller  50  drives the process cartridge  6  while maintaining the separation state of the transfer roller  9 . Thereafter, after the position of the process cartridge  6  is stabilized, the clutch is engaged to drive the driving gear  44  by the motor  51 , and the transfer roller  9  comes into contact with the photosensitive drum  8 . Thereby, the risk of having the transfer roller  9  come into pressure contact with the photosensitive drum  8  while the process cartridge  6  is displaced from the attachment position and causing the process cartridge  6  to be in an incomplete attachment state can be prevented reliably. The motor can also function as a driving source for driving the photosensitive drum  8  of the process cartridge  6 . 
     Other Example 
     In the first and second embodiments, the transfer roller  9  is moved to the separation position by the separation lever  41  or the separation rod  42  pushing down the first bearing  21  and the second bearing  22  retaining the transfer roller  9 . Alternately, a configuration in which the transfer roller  9  is moved to the separation position by the separation lever  41  or the separation rod  42  directly pressing the roller shaft of the transfer roller  9  can be adopted. 
     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. 2021-030499, filed on Feb. 26, 2021, which is hereby incorporated by reference herein in its entirety.