Patent Publication Number: US-10324413-B2

Title: Image forming apparatus having a portion to prevent a process cartridge from being inserted when the process cartridge is in a particular state

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an image forming apparatus using an electrophotographic process, a process cartridge, and an apparatus main body for an image forming apparatus. 
     Description of the Related Art 
     A conventional process cartridge is known in which a photosensitive drum and a process means for forming a developer image on the photosensitive drum are integrated as a cartridge. The process cartridge can be attached to and detached from the apparatus main body of an image forming apparatus. The cartridge system enables the user to maintain the image forming apparatus by himself, without a servicemen. 
     When an electrostatic latent image is developed on a photosensitive drum, a contact development system is sometimes used in which developer is supplied to the photosensitive drum by bringing a development roller into contact with the photosensitive drum. In the contact development system, since the development roller and the photosensitive drum need to be brought into contact with each other, the development roller is biased with respect to the photosensitive drum. 
     However, where the state of contact of the development roller with the photosensitive drum is maintained for a long time, the development roller can be deformed, or a toner interposed between the development roller and the photosensitive drum can be damaged. As a result, image defects can occur. For this reason, the feature of separating the development roller and photosensitive drum from each other when no image is formed is widely used in process cartridges. 
     For example, a configuration has been suggested in which a process cartridge is mounted in the rotation axis direction of a photosensitive drum from an insertion port provided in an apparatus main body (Japanese Patent Application Publication No. 2008-9295 (JP 2008-9295 A)). In this invention, the development roller is withdrawn from the photosensitive drum in conjunction with the operation of pulling out the process cartridge from the apparatus main body. Further, the development roller is brought into contact with the photosensitive drum in conjunction with the operation of inserting the process cartridge into the apparatus main body of the image forming apparatus. 
     Further, an image forming apparatus has been suggested which is provided with a door for opening and closing the insert ion port for inserting a process cartridge into the apparatus main body, and by closing the door after the process cartridge has been inserted into the apparatus main body, the development roller and photosensitive drum are brought into contact or separated in conjunction with the operation of closing the door (JP 2005-49525 A). 
     However, in the invention disclosed in JP 2008-9295 A, the separated development roller is brought close to the photosensitive drum in the course of inserting the process cartridge into the insertion port. Therefore, the insertion port of the apparatus main body needs to have a shape that allows to pass therethrough both the process cartridge in a state in which the development roller and photosensitive drum are brought close to each other and the process cartridge in a state in which the development roller and photosensitive drum are separated from each other. 
     In this case, a clearance is present between the process cartridge and insertion port when the process cartridge passes through the insertion port. As a result, the process cartridge can be inserted into the insertion port in a wrong mounting posture, or the posture of the process cartridge can be unstable during the attachment/detachment operation of the process cartridge. As a result, the important components, such as the photosensitive drum, can come into contact with the apparatus main body and these important components can be damaged. 
     Meanwhile, in the invention disclosed in JP 2005-49525 A, a part is needed for bringing the development roller and photosensitive drum into contact with each other or separating them from each other in conjunction with the operation of closing the door. Therefore, the number of parts used in the image forming apparatus is increased, and the production cost of the image forming apparatus rises. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an objective of the present invention to provide a technique for separating the photosensitive drum and development roller from each other in conjunction with the operation of mounting the process cartridge on the image forming apparatus, without damaging the important components of the process cartridge. 
     Another object of the present invention is to provide an image forming apparatus in which a process cartridge is configured to be attachable to and detachable from an apparatus main body, the process cartridge having a configuration in which a first frame that supports an image bearing member bearing a developer image and a second frame that supports a developer bearing member supplying developer to the image bearing member are supported rotatably and the image bearing member and the developer bearing member can be brought into contact with each other and separated from each other, wherein 
     the apparatus main body has: 
     an insertion port through which the process cartridge cannot pass when the image bearing member and the developer bearing member are separated from each other and through which the process cartridge can pass when the image bearing member and the developer bearing member are in contact with each other; and 
     a guide that guides one of the first frame and the second frame when the process cartridge is inserted into the insertion port, 
     the image forming apparatus having a separation mechanism that separates the image bearing member and the developer bearing member from each other when the process cartridge is further inserted after the other of the first frame and the second frame has passed through the insertion port. 
     Another object of the present invention is to provide a process cartridge attachable to and detachable from an apparatus main body of an image forming apparatus, the process cartridge comprising: 
     a first frame that supports an image bearing member bearing a developer image; 
     a second frame that supports a developer bearing member supplying developer to the image bearing member and that is connected to the first frame to be rotatable with respect to the first frame; and 
     a portion-to-be-contacted that is provided at one of the first frame and the second frame, 
     the process cartridge being configured such that the image bearing member and the developer bearing member can come into contact with each other and be separated from each other, wherein 
     the process cartridge is mounted on the apparatus main body by insertion from an insertion port that is provided at the apparatus main body and that blocks the passage of the process cartridge when the image bearing member and the developer bearing member are separated from each other and allows the process cartridge to pass when the image bearing member and the developer bearing member are in contact with each other; and 
     the other one of the first frame and the second frame is guided by a guide provided at the apparatus main body when the process cartridge is inserted into the insertion port, and 
     when the process cartridge is further inserted into the apparatus main body after the one of the first frame and the second frame has passed through the insertion port, the portion-to-be-contacted comes into contact with a contact port ion provided at the apparatus ma in body, thereby separating the image bearing member and the developer bearing member from each other. 
     Another object of the present invention is to provide an apparatus main body of an image forming apparatus, the apparatus main body being configured such that a process cartridge can be attached to and detached from the apparatus main body, the process cartridge having a configuration in which a first frame that supports an image bearing member bearing a developer image and a second frame that supports a developer bearing member supplying developer to the image bearing member are supported rotatably and the image bearing member and the developer bearing member can be brought into contact with each other and separated from each other, the apparatus main body comprising: 
     an insertion port that blocks the passage of the process cartridge when the image bearing member and the developer bearing member are separated from each other and allows the process cartridge to pass when the image bearing member and the developer bearing member are in contact with each other; 
     a guide that guides one of the first frame and the second frame when the process cartridge is inserted into the insertion port; and 
     a contact portion that separates the image bearing member and the developer bearing member from each other by contact with a portion-to-be-contacted provided at the other of the first frame and the second frame when the process cartridge is further inserted after the other of the first frame and the second frame has passed through the insertion port. 
     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 cross-sectional view of the image forming apparatus according to an embodiment; 
         FIG. 2  is a schematic cross-sectional view of the process cartridge in a contact state; 
         FIG. 3  is a schematic external appearance view of the process cartridge according to the embodiment; 
         FIG. 4  is a schematic external appearance view illustrating an insertion port provided in the apparatus main body of the image forming apparatus; 
         FIG. 5  is a schematic perspective view illustrating a separation lever provided at the apparatus main body; 
         FIGS. 6A to 6D  are schematic diagrams illustrating the operation of mounting the process cartridge; and 
         FIGS. 7A to 7C  are schematic diagrams illustrating the mechanism performing the operation of mounting the process cartridge. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     An embodiment of the present invention is described hereinbelow with reference to the drawings. Dimensions, materials, shapes, and mutual arrangement of constituent components described in the embodiment could be changed, as appropriate, according to the configuration and various conditions relating to the apparatus using the invention, and the scope of the invention is not intended to be limited to the below-described embodiment. 
     The embodiment of the present invention is explained hereinbelow in detail with reference to the drawings. 
     &lt;Configuration of Image Forming Apparatus&gt; 
     Initially, the entire configuration of an image forming apparatus  100  is explained with reference to  FIG. 1 .  FIG. 1  is a schematic cross-sectional view of an apparatus main body  101  of the image forming apparatus  100  and a cartridge  70 . As depicted in  FIG. 1 , in the image forming apparatus  100 , four detachable cartridges  70  ( 70 Y,  70 M,  70 C,  70 K) are provided together inside the apparatus main body  101  at an angle with respect to the horizontal direction. The configuration and operation of the cartridges  70  ( 70 Y to  70 K) are substantially the same, except that the colors of images formed on a recording medium S are different. For this reason, in the comprehensive explanation hereinbelow, indexes Y, M, C, K are omitted, unless specific distinction is required. 
     In the cartridge  70 , process means such as photosensitive drums  1  (image bearing members) which are electrophotographic photosensitive drums, charging rollers  2 , cleaning members  6 , and development rollers  25  (developer bearing members) are arranged integrally. The charging rollers  2 , the cleaning members  6 , and the development rollers  25  are disposed on the periphery of the photosensitive drums  1 . In the present embodiment, the rotation center axes of the photosensitive drums  1  and the rotation center axes of the development rollers  25  are parallel to each other. 
     The charging rollers  2  ( 2 Y,  2 M,  2 C,  2 K) charge uniformly the surface of the photosensitive drums  1  ( 1 Y,  1 M,  1 C,  1 K). The development rollers  25  ( 25 Y,  25 M,  25 C,  25 K) develop the electrostatic latent image, which has been formed on the photosensitive drums  1 , with toners. Then, the cleaning members  6  ( 6 Y,  6 M,  6 C,  6 K) remove the toners remaining on the photosensitive drums  1  after the toner images (developer images) on the photosensitive drums  1  have been transferred onto the recording medium S. Further, a scanner unit  3  which performs selective exposure of the photosensitive drums  1  on the basis of image information and serves for forming the electrostatic latent images on the photosensitive drums  1  is provided below the cartridge  70 . 
     A cassette  99  accommodating the recording medium S is mounted in the lower portion of the apparatus main body  101 . Provided also is a recording medium transport means for transporting the recording medium S past a secondary transfer roller  59  or a fixing unit  74  to the upper side of the apparatus main body  101 . More specifically, provided are a feed roller  54  that separates and feeds one by one the recording medium S located inside the cassette  99 , a transport roller pair  76  that transports the recording medium S which has been fed, and a resist roller pair  55  for synchronizing the recording medium S with the electrostatic latent image to be formed on the photosensitive drums  1 . 
     Further, an intermediate transfer unit  5  serving as an intermediate transfer means for transferring the toner images formed on the photosensitive drums  1  to the recording medium S is provided above the cartridge  70 . The intermediate transfer unit  5  has primary transfer rollers  58  ( 58 Y,  58 M,  58 C,  58 K) provided opposite the photosensitive drums  1 , an opposing roller  69  provided opposite the secondary transfer roller  59 , a driver roller  56 , and a driven roller  57 . A transfer belt  9  is stretched over the driver roller  56 , the driven roller  57 , the primary transfer rollers  58 , and the opposing roller  69 . 
     The transfer belt  9  circulates while being in contact with all of the photosensitive drums  1 , and the toner images formed on the photosensitive drums  1  are primary transferred to the transfer belt  9  as a result of voltage application to the primary transfer rollers  58 . Where a voltage is applied to the opposing roller  69  disposed on the inner side of the transfer belt  9  and the secondary transfer roller  59 , the toner images which have been primary transferred to the transfer belt  9  are transferred to the recording medium S. 
     When an image is formed on the recording medium S, the photosensitive drums  1  rotate and the rotating photosensitive drums  1  are uniformly charged by the charging rollers  2 . The charged photosensitive drums  1  are then selectively exposed by the scanner unit  3 . As a result, an electrostatic latent images are formed on the photosensitive drum  1 . The electrostatic latent images formed on the photosensitive drums  1  are developed with the development rollers  25 , thereby forming toner images of respective colors on each of the photosensitive drums  1 . 
     Synchronously with the formation of the toner images, the resist roller pair  55  transports the recording medium S to the secondary transfer position at which the opposing roller  69  and the secondary transfer roller  59  come into contact with each other, with the transfer belt  9  being interposed therebetween. As a result of transfer bias voltage application to the secondary transfer roller  59 , the color toner images on the transfer belt  9  are successively secondary transferred to the recording medium S. As a result, a color toner image is formed on the recording medium S. The recording medium S on which the color toner image has been formed is heated and pressurized by the fixing unit  74 , thereby fixing the color toner image to the recording medium S. The recording medium S with the toner image fixed thereto is then released by a release roller  72  to a release unit  75 . The fixing unit  74  is disposed in the upper portion of the apparatus main body  101 . 
     &lt;Process Cartridge&gt; 
     The cartridge  70  is explained hereinbelow with reference to  FIG. 2 .  FIG. 2  is a schematic cross-sectional view of the cartridge  70  in a state of image formation. The cartridge  70  is constituted by a cleaning unit D having a photosensitive drum  1  and serving as a cleaning device which is also a drum unit, and a development unit G having the development roller  25  as a development cartridge (development means). The drum unit is a unit having the photosensitive drum  1  (image bearing member), and the cleaning unit is a unit having the photosensitive drum  1  (image bearing member) and the cleaning means for cleaning the photosensitive drum  1 . The development unit is a unit having the development means for developing the photosensitive drum  1  (image bearing member). 
     The cleaning unit D is provided with the photosensitive drum  1  which is configured to be rotatable, the charging roller  2 , the cleaning member  6 , and a cleaning frame  20  (first frame) supporting those members. The development unit  4  is provided with the development roller  25  which is configured to be rotatable and a development frame  18  (second frame) supporting the development roller. 
     As mentioned hereinabove, the charging roller  2  and the cleaning member  6  are disposed on the periphery of the photosensitive drum  1 . The cleaning member  6  is constituted by an elastic member  7  formed from a rubber blade and a cleaning support member  8 . 
     The elastic member  7  is provided such that the distal end thereof is in contact with the surface of the photosensitive drum  1  in the direction opposite to the rotation direction of the photosensitive drum  1 . The removed matter, such as the residual toner, which has been removed by the cleaning member  6  from the surface of the photosensitive drum  1  falls into a removed toner chamber  20   c  serving as a housing section and is housed therein. Further, a scooping sheet  20   d  preventing the leakage of the removed toner in the removed toner chamber  20   c  is in contact with the photosensitive drum  1 . Where drive power of a main body drive motor (not depicted in the figure), which is a driver source, is transmitted to the cleaning unit D, the photosensitive drum  1  is rotationally driven in response to the image forming operation. The charging roller  2  is rotationally mounted on the cleaning frame  20  through a charging roller bearing  28 , pressed by a pressing member  46  towards the photosensitive drum  1 , and rotationally driven by the photosensitive drum  1 . 
     A toner feed roller  34  rotating in contact with the development roller  25 , and a development blade  35  for controlling the layer thickness of the toner carried on the development roller  25  are disposed on the circumference of the development roller  25  of the development unit G. A leak preventing sheet  29  is arranged for preventing the toner from leaking from the development frame  31  which is in contact with the development roller  25 . A toner housing chamber  18   e  of the development frame  18  is provided with a toner transport member  36  for stirring the toner housed therein and transporting the toner to the toner feed roller  34 . 
     The development unit G is joined (connected) to the cleaning unit D to be rotatable about a mating shaft  24  fixedly supported on the cleaning frame  20  of the cleaning unit D. The development unit G is also biased in the direction C in  FIG. 2  by a tension force of a compressed spring  23 . Therefore, when an image is formed by the process cartridge  70 , the development unit G rotates about the mating shaft  24 , and the photosensitive drum  1  and the development roller  25  are in contact with each other. 
     The development frame  18  of the development unit G is also provided with a pressure surface  18   d  (section to be contacted), and the apparatus main body  101  is provided with a separation lever  12  (contact section) (see  FIG. 5 ). When no image is formed, the separation lever  12  moves in the direction B in  FIG. 2 , while pushing the pressure surface  18   d , thereby rotating the development unit G about the mating shaft  24  in the direction A in  FIG. 2  and separating the photosensitive drum  1  and the development roller  25 . In other words, in the cartridge  70 , the photosensitive drum  1  and the development roller  25  can come into contact with each other and separate from each other. In the present embodiment, the mechanism having the separation lever  12  and the pressure surface  18   d  is assumed to be a separation mechanism. The separation mechanism can apply (application is possible) a force to the development frame  18  such as to separate the development roller  25  and the photosensitive drum  1 . 
     With such a configuration of the cartridge  70 , when an image is formed on the recording medium S, the development roller  25  and the photosensitive drum  1  are in contact with each other and the toner is supplied from the development roller  25  to the photosensitive drum  1 . As a result, as mentioned hereinabove, the electrostatic latent image formed on the photosensitive drum  1  is developed. Meanwhile, when no image is formed on the recording medium S, the development roller  25  and the photosensitive drum  1  are separated from each other. As a result, the development roller  25  can be prevented from deformation, and the toner interposed between the development roller  25  and the photosensitive drum  1  can be prevented from damage. 
     &lt;Attachment/Detachment of Cartridge to/from Image Forming Apparatus Main Body&gt; 
     The operation of attaching/detaching the cartridge to/from the apparatus main body  101  is explained hereinbelow with reference to  FIG. 1  and  FIGS. 3-6 .  FIG. 1  is a schematic cross-sectional view of the image forming apparatus of the present embodiment.  FIG. 3  is a schematic external appearance view illustrating the state in which the cartridge  70  is mounted in the insertion port of the apparatus main body  101  of the image forming apparatus.  FIG. 4  is a schematic external appearance view illustrating the insertion port provided in the apparatus main body of the image forming apparatus.  FIG. 5  is a schematic perspective view illustrating the separation lever provided at the apparatus main body.  FIGS. 6A to 6D  are schematic diagrams illustrating the operation of mounting the process cartridge.  FIGS. 3 and 4  show only components relating to the cartridges  70 M and  70 K adjacent to the cartridge  70 C, but the case in which three cartridges are arranged is not limiting. 
     As mentioned hereinabove, the cartridge  70  is configured to be attachable to and detachable from the apparatus main body  101 . The apparatus main body  101  is also provided with a door (not depicted in the figure). The opening of the door exposes the cover  14 , an upper attachment/detachment guide  15  that guides an upper attachment/detachment guided member  21  when the cartridge is attached and detached, and a lower attachment/detachment guide  16  that guides a lower attachment/detachment guided member  22  when the cartridge  70  is attached and detached, as depicted in  FIG. 3 . Provided herein are the upper attachment/detachment guide  15  and the lower attachment/detachment guide  16  that guide the configuration that guides the cleaning frame  20  in the insertion direction (H direction). The upper attachment/detachment guide  15  and the lower attachment/detachment guide  16  are mounted on the front cover  14 . An insertion opening  17  (insertion port) which is an opening for mounting the cartridge  70  inside the apparatus main body  101  is formed in the front cover  14 . 
     The upper attachment/detachment guide  15  is in the concave shape opened in the downward direction, and the lower attachment/detachment guide  16  is in the concave shape opened in the upward direction. The upper attachment/detachment guided member  21  is guided by the upper attachment/detachment guide  15 , and the lower attachment/detachment guided member  22  is guided by the lower attachment/detachment guide  16 , thereby guiding the cartridge  70  when the cartridge  70  is inserted into the apparatus main body  101 . Further, the upper attachment/detachment guide  15  and the lower attachment/detachment guide  16  align the cleaning frame  20  in the direction perpendicular to the insertion direction (H direction). As depicted in  FIG. 3 , the upper attachment/detachment guided member  21  and the lower attachment/detachment guided member  22  are provided at the cleaning unit D. The upper attachment/detachment guided member  21  is shaped to protrude upward, and the lower attachment/detachment guided member  22  is shaped to protrude downward. 
     &lt;Mounting of the Cartridge&gt; 
     When the cartridge  70  is mounted on the apparatus main body  101 , the upper attachment/detachment guided member  21  of the cartridge  70  is placed along the upper attachment/detachment guide  15  of the apparatus main body  101 , and the lower attachment/detachment guided member  22  is placed along the lower attachment/detachment guide  16 . Then, the cartridge  70  is inserted in the axial direction (rotation center axis direction) (H direction) of the photosensitive drum  1 . Further, the present embodiment is not configured to include a partition member between the adjacent cartridges  70 . As a result, the spacing between the adjacent cartridges  70  can be reduced and the apparatus main body  101  can be miniaturized. 
     With the configuration in which no partition members are provided in the apparatus main body  101 , a state can occur in which the upper attachment/detachment guided member  21  is not mounted along the upper attachment/detachment guide  15 , and the lower attachment/detachment guided member  22  is not mounted along the lower attachment/detachment guide  16 . Therefore, in such a case, the cartridge  70  is not introduced into the insertion opening  17  in a correct mounting posture, or the posture of the cartridge  70  cannot be stabilized during the attachment/detachment operation. As a result, in the worst-case scenario, an important component such as the photosensitive drum  1  comes into contact with the apparatus main body  101 , and the important component can be damaged. 
     Accordingly, in the present embodiment, as depicted in  FIGS. 3 and 4 , the insertion opening  17  is shaped correspondingly to the outer shape of the cartridge  70  in a state in which the development roller  25  and the photosensitive drum  1  are in contact with each other. The outer shape of the cartridge  70 , as referred to herein, is the outer shape of the cartridge  70  as viewed from the direction perpendicular to the insertion direction (H direction). As a result, the insertion opening  17  prevents the passage of the cartridge  70  in a state in which the photosensitive drum  1  and the development roller  25  are separated from each other and allows the passage of the cartridge  70  in a state in which the photosensitive drum  1  and the development roller  25  are in contact with each other. Thus, in the configuration of the present embodiment, the cartridge  70  is inserted into the insertion opening  17  in a state in which the photosensitive drum  1  and the development roller  25  are in contact with each other. Further, since the insertion opening  17  is shaped correspondingly to the outer shape of the cartridge  70  in a state in which the development roller  25  and the photosensitive drum  1  are in contact with each other, it can be seen that the cartridge  70  is more likely to be introduced in the insertion opening  17  in a correct mounting posture. 
     Further, in the present embodiment, as depicted in  FIG. 3 , partition sections  14   a  ( 14   a C,  14   a K) extending from the upper attachment/detachment guide  15  side to the lower attachment/detachment guide  16  side are provided at the front cover  14 . The partition sections  14   a  are provided between the adjacent insertion openings  17  ( 17 M to  17 K in  FIG. 4 ). The partition section  14   a  has a regulation surface  14   b  ( 14   b C) and a regulation surface  14   c  ( 14   c C). Since the partition sections  14   a  are provided in the present embodiment, the insertion opening  17 C is shaped along the outer shape of the cartridge  70 C. As a result, the upper attachment/detachment guided member  21 C of the cartridge  70 C is easily placed along the upper attachment/detachment guide  15 C of the apparatus main body  101 , and the lower attachment/detachment guided member  22 C is easily placed along the lower attachment/detachment guide  16 C. 
     Further, as a result of providing the partition section  14   a C and the partition section  14   a K, a surface-to-be-regulated  20   a C of the cleaning frame  20 C comes into contact with the regulation surface  14   c C of the partition section  14   a K when the cartridge  70 C is inserted into the apparatus main body  101  in a wrong posture. Further, a surface-to-be-regulated  18   a C of the development frame  18 C comes into contact with the regulation surface  14   b C of the partition section  14   a C. As a result, the cartridge  70  can be prevented from being inserted into the apparatus main body  101  in a wrong posture. The state in which the upper attachment/detachment guided member  21  is placed along the lower attachment/detachment guide  15 , and the lower attachment/detachment guided member  22  is placed along the lower attachment/detachment guide  16  will be referred to hereinbelow as the attachment/detachment posture of the cartridge  70 . 
     &lt;Operation of Separating Photosensitive Drum and Development Roller which is Performed in Conjunction with Cartridge Mounting Operation&gt; 
     As depicted in  FIG. 5 , in the present embodiment, the separation lever  12  is provided at the apparatus main body  101  of the image forming apparatus  100 . In a state in which the insertion of the cartridge  70 C into the insertion opening  17  in the correct posture has been started, as depicted in  FIG. 3  (the state C of the cartridge  70  in  FIG. 3 ), as the cartridge  70  is inserted, the separation lever  12 C is disposed at a position J overlapping the pressure surface  18   d K. 
     As depicted in  FIG. 5 , the separation lever  12  is provided downstream in the mounting direction of the cartridge  70 . The separation lever  12  is also attached to a bottom plate  68  in the apparatus main body  101  such as to be rotatable about a rotation center  12   a . When the cartridge  70  is inserted into the apparatus main body  101 , the separation lever  12  is fixed at a contact position rotated in the direction of arrow E in  FIG. 5  by a cam mechanism (not depicted in the figure). As a result, as will be described hereinbelow, where the cartridge  70  is inserted into the apparatus main body  101 , a pressure section  12   b  (inclined surface) in the separation lever  12  is in contact with the pressure surface  18   d  of the development frame  18  in the course of insertion of the cartridge  70  ( FIGS. 6A to 6D ). In the present embodiment, the pressure section  12   b  is an inclined surface inclined with respect to the insertion direction of the cartridge (H direction). The pressure surface  18   d  is also an inclined surface inclined with respect to the insertion direction of the cartridge (H direction). 
     Where the cartridge  70  is further inserted into the apparatus main body  101  in a state in which the pressure section  12   b  is in contact with the pressure surface  18   d , the pressure surface  18   d  in the development frame  18  is pushed by the pressure section  12   b  in the separation lever  12 , thereby separating the development roller  25  and the photosensitive drum  1  from each other. More specifically, as a result of the pressure surface  18   d  being pushed by the pressure section  12   b , the development frame  18  rotates with respect to the cleaning frame  20 , and the development roller  25  and the photosensitive drum  1  are separated from each other, as in the cartridge  70 M and the cartridge  70 C depicted in  FIG. 3 . In this case, a mechanism that has the development frame  18  and the separation lever  12  provided at the apparatus main body  101  and separates the development roller  25  from the photosensitive drum  1  is referred to as a separation mechanism. 
     To ensure smooth separation of the development roller  25  and the photosensitive drum  1  from each other, the pressure section  12   b  of the separation lever  12  is shaped to be inclined with respect to the mounting direction (H direction) of the cartridge  70 , as depicted in  FIG. 5 . Further, the pressure surface  18   d  of the development frame  18  is also shaped to be inclined with respect to the mounting direction (H direction) of the cartridge  70 . Meanwhile, in a state in which the separation lever  12  is fixed in a non-contact position which is a position rotated in the direction F in  FIG. 5 , the pressure applied by the pressure section  12   b  to the pressure surface  18   d  is released, as depicted in  FIG. 2 . As a result, the development roller  25  and the photosensitive drum  1  are brought into contact with each other by a tension force (urging force) of the compressed spring  23  (urging member), and an image can be formed. 
     As described hereinabove, when an image forming operation is not performed, it is preferred that the development roller  25  and the photosensitive drum  1  be separated from each other. Therefore, when the cartridge  70  is mounted on the apparatus main body  101 , it is preferred that the development roller  25  and the photosensitive drum  1  assume a separated state at a point of time when the mounting of the cartridge  70  on the apparatus main body  101  has ended. Thus, in the present embodiment, the development roller  25  and the photosensitive drum  1  are separated from each other in conjunction with the operation of inserting the cartridge  70 , in which the development roller  25  is in contact with the photosensitive drum  1 , into the apparatus main body  101 . 
     In a state in which the development roller  25  and the photosensitive drum  1  are separated from each other, the front cover  14  and the development frame  18  overlap in a region I, when viewed from the insertion direction of the cartridges  70 M,  70 K depicted in  FIG. 3 . In other words, the overlapping of the separation lever  12  and the pressure surfaces  18   d M,  18   b K, when viewed from the insertion direction of the cartridges  70 M,  70 K, is canceled. Further, in the present embodiment, the separation of the development roller  25  and the photosensitive drum  1  is started after the upstream end surface  18   b  of the development frame  18  in the insertion direction (H direction) of the cartridge  70  has passed the partition section  14   a  of the front cover ( FIGS. 6A to 6D ). 
     The series of operations of mounting the cartridge  70  on the apparatus main body  101  is explained hereinbelow with reference to  FIGS. 6A to 6D . In a state in which the insertion of the cartridge  70  into the apparatus main body  101  has started, as depicted in  FIG. 6A , the pressure surface  18   d  in the cartridge  70  is not in contact with the separation lever  12  in the apparatus main body  101 . Since a gap L 1  between the surface-to-be-regulated  18   a  in the development frame  18  and the regulation surface  14   b  in the front cover  14  is small, the cartridge  70  is easily inserted in the correct mounting posture, as indicated hereinabove. Where the cartridge  70  is further inserted into the apparatus main body  101  from the state depicted in  FIG. 6A , the pressure surface  18   d  comes into contact with the separation lever  12 , as depicted in  FIG. 6B . At this time, in the insertion direction (H direction), the upstream end surface  18   b  of the development frame  18  is positioned downstream of the partition section  14   a  in the front cover  14 . 
     Further, in the present embodiment, a side member  26  and a side member  27  are provided at two ends of the development frame  18  in the insertion direction (H direction). Where the cartridge  70  is further inserted in the H direction from the state depicted in  FIG. 6B , the pressure surface  18   d  is brought into contact and pressed against the separation lever  12 , as depicted in  FIG. 6C . The pressure surface  18   d  of the development frame  18  slides along the separation lever  12 . As a result, the development unit G rotates in the direction of arrow B in  FIGS. 6A to 6D , and the development roller  25  and the photosensitive drum  1  are separated from each other. 
     At this time, the upstream end surface  18   b  is positioned downstream, in the H direction, of the partition section  14   a  of the front cover  14 . In other words, in the present embodiment, the photosensitive drum  1  and the development roller  25  are separated from each other by further inserting the cartridge  70  into the apparatus main body  101  after the development unit G has passed through the insertion opening  17 . Further, since the development unit G rotates with respect to the cleaning unit D, part of the upstream end surface  18   b  and the partition section  14   a  overlap when viewed in the insertion direction (H direction) of the cartridge  70  (L 2 ). Where the cartridge  70  is further inserted in the H direction from the state depicted in  FIG. 6C , the mounting of the cartridge  70  on the apparatus main body  101  is completed. In this case, as depicted in  FIG. 6D , the pressure surface  18   d  is further pushed by the separation lever  12 , thereby further separating the development roller  25  from the photosensitive drum  1 . As a result, the overlap width L 3  of the part of the upstream end surface  18   b  and the partition section  14   a  increases by comparison with L 2 , when viewed in the insertion direction (H direction) of the cartridge  70 . 
     &lt;Removal of Cartridge&gt; 
     Meanwhile, when the cartridge  70  is removed from the apparatus main body  101 , the cartridge  70  is pulled out in the direction opposite to the insertion direction (H direction) of the cartridge  70 . Where the pull-out of the cartridge  70  from the apparatus main body  101  is started, the pressure surface  18   d  slides along the separation lever  12 , and the development roller  25  gets closer to the photosensitive drum  1 . At a timing at which the upstream end surface  18   b  in the development frame  18  passes through the insertion opening  17 , the development roller  25  comes into contact with the photosensitive drum  1 . In other words, contrary to the case in which the cartridge  70  is inserted, the development roller  25  and the photosensitive drum  1  approach each other in conjunction with the operation of pulling the cartridge  70  out of the apparatus main body  101 . In a state in which the upstream end surface  18   b  passes through the insertion opening  17 , the development roller  25  and the photosensitive drum  1  come into contact with each other. 
     &lt;Mechanism of Cartridge Mounting Operation&gt; 
     The mechanism realized when the cartridge  70  is mounted on the apparatus main body  101  is explained hereinbelow.  FIGS. 7A to 7C  are schematic diagrams illustrating the mechanism realized when the cartridge  70  is mounted on the apparatus main body  101 . In the left drawings in  FIGS. 7A to 7C , the operation of inserting the cartridge  70  is viewed from above the image forming apparatus  100 , and in the right drawings, the operation of inserting the cartridge  70  is viewed from the insertion direction of the cartridge  70 . When the insertion of the cartridge  70  into the apparatus main body  101  is started, the state depicted in  FIG. 7A  is assumed. In this state, the pressure surface  18   d  in the development frame  18  is not yet in contact with the separation lever  12  provided at the apparatus main body  101 . 
     Where the cartridge  70  is further inserted into the apparatus main body  101  from the state depicted in  FIG. 7A , the pressure surface  18   d  comes into contact with the separation lever  12  at a timing at which the upstream end surface  18   b  of the development frame  18  passes through the insertion opening  17 , as depicted in  FIG. 7B . Where the cartridge  70  is further inserted into the apparatus main body  101  from the state depicted in  FIG. 7B , the pressure surface  18   d  is pushed by the separation lever  12 , as depicted in  FIG. 7C . As a result of the pressure surface  18   d  provided at the development frame  18  being pushed by the separation lever  12 , the development frame  18  rotates with respect to the cleaning frame  20  and the development roller  25  separates from the photosensitive drum  1 . 
     As described hereinabove, in the present embodiment, the apparatus main body of the image forming apparatus is provided with the insertion port such that the process cartridge cannot pass therethrough when the image bearing member and the developer bearing member are separated from the each other and such that the process cartridge can pass therethrough when the image bearing member and the developer bearing member are in contact with each other. The image bearing member and the developer bearing member are separated from each other by the separation mechanism, which is provided at the apparatus main body, in conjunction with the operation of further inserting the process cartridge after the first frame or second frame in the process cartridge has passed through the insertion port. 
     As a result of the image bearing member and developer bearing member being separated when the process cartridge in inserted into the apparatus main body, the toner interposed between the development roller and the photosensitive drum is prevented from damage and the development roller is prevented from deformation. Further, since the insertion port is in the shape described hereinabove, it can be seen that the cartridge is easily introduced into the insertion port in the correct mounting posture. The important components of the process cartridge are prevented from damage, and the photosensitive drum and development roller can be separated in conjunction with the operation of mounting the process cartridge on the image forming apparatus. 
     Further, in the present embodiment, the insertion port has a shape corresponding to the shape of the process cartridge, as viewed from the direction in which the process cartridge is inserted, in a state in which the image bearing member and developer bearing member are in contact with each other. As a result, the effect of introducing the cartridge into the insertion port in the correct mounting posture can be further enhanced. 
     Further, in the present embodiment, the configuration is described in which the process cartridge is attached/detached to/from the apparatus main body in a state in which the door of the apparatus main body is opened, but the attachment/detachment of the process cartridge may be also performed in conjunction with the operation of closing the door. 
     Further, in the present embodiment, the cleaning frame is guided by a guide provided at the apparatus main body, and the development frame rotates with respect to the cleaning frame. However, the cleaning frame is not necessarily required to be guided by the guide. For example, the configuration may be used in which the development frame is guided by the guide, and the cleaning frame rotates with respect to the development frame. In another possible configuration, one of the cleaning frame and development frame is guided by the guide and the other of the cleaning frame and development frame rotates. 
     Further, in the present embodiment, the pressure surface is provided at the development frame, but such a configuration is not limiting. The pressure surface may be provided, for example, at the cleaning frame. 
     Further, in the present embodiment, the cartridge is guided in the insertion direction as a result of the cleaning frame being guided in the cartridge insertion direction by the upper attachment/detachment guide and lower attachment/detachment guide. However, it is not always necessary that the cleaning frame be guided. For example, the cartridge may be guided in the cartridge insertion direction by guiding the development frame. 
     Further, in the present embodiment, a portion in the separation lever pushing the pressure surface is inclined with respect to the insertion direction of the cartridge, and the portion of the pressure surface pushed by the separation lever is inclined with respect to the insertion direction of the cartridge. However, such a configuration is not necessarily limiting. For example, the inclined surface may be provided at either one of the portion of the separation lever that pushes the pressure surface and the portion of the pressure surface that is pushed by the separation cover. 
     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. 2015-039588, filed Feb. 27, 2015 which is hereby incorporated by reference herein in its entirety.