Abstract:
An image forming apparatus may include a photosensitive member, a developing device including a developing roller, pressing members configured to engage with the developing device and springs configured to urge the pressing members. In some examples, each of the pressing members may be configured to contact and move the developing device between various positions based on the urging of the springs. Additionally or alternatively, various ends of a contact surface of the developing roller configured to contact developer may be disposed relative to an axis line of the developing roller and pressing surfaces of the pressing members.

Description:
[0001]    This application is a continuation of U.S. application Ser. No. 14/275,138, filed May 12, 2014, which is a continuation of U.S. application Ser. No. 13/625,359, filed Sep. 24, 2012, issued as U.S. Pat. No. 8,761,636 on Jun. 24, 2014, which is a continuation of U.S. application Ser. No. 12/507,278, filed Jul. 22, 2009, issued as U.S. Pat. No. 8,311,451 on Nov. 13, 2012, entitled “Component Movement Mechanism for an Image Forming Apparatus,” which claims priority from Japanese Patent Application No. 2008-188513 filed on Jul. 22, 2008. The entire subject matter of the above noted applications is hereby incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    Aspects of the invention relate to an image forming apparatus and in particular to an image forming apparatus whose usability is enhanced. 
       BACKGROUND 
       [0003]    In a known image forming apparatus such as a laser printer, a plurality of developing devices each having a developing roller are detachably supported on a support tray and the support tray can be attached to and detached from the apparatus main body. The image forming apparatus enables a user to easily replace any developing device by removing the support tray from the apparatus main body. 
       SUMMARY 
       [0004]    Illustrative aspects of the invention provide an image forming apparatus that can improve usability thereof when a developing device is replaced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    In the accompanying drawings: 
           [0006]      FIG. 1  is a sectional view of an image forming apparatus according to an exemplary embodiment of the invention; 
           [0007]      FIGS. 2A to 2C  are drawings to describe a close position, in which  FIG. 2A  shows an external structure of a photosensitive unit and a developing unit,  FIG. 2B  is a partially enlarged view of  FIG. 2A , and  FIG. 2C  shows an internal structure of the photosensitive unit and the developing unit; 
           [0008]      FIGS. 3A to 3D  are drawings to describe a distant position, in which  FIG. 3A  shows the external structure of the photosensitive unit and the developing unit,  FIG. 3B  is a partial enlarged view of  FIG. 3A ,  FIG. 3C  shows the internal structure of the photosensitive unit and the developing unit, and  FIG. 3D  is an enlarged view of a lock engagement part; 
           [0009]      FIGS. 4A and 4B  are perspective views of a developing device, in which  FIG. 4A  shows a state where a cover member is at an exposure position, and  FIG. 4B  shows a state where the cover member is at a cover position; 
           [0010]      FIGS. 5A to 5C  are drawings to describe a function of a cover member move mechanism; 
           [0011]      FIG. 6  is a drawing to show a state of replacing the photosensitive unit; 
           [0012]      FIG. 7  is a drawing to show a state of replacing the developing device; 
           [0013]      FIG. 8A  is a schematic drawing of the developing device where the cover member is at the cover position, and  FIG. 8B  shows a state where the developing device shown in  FIG. 8A  is grasped; and 
           [0014]      FIGS. 9A and 9B  are schematic drawings of a developing device according to a modified exemplary embodiment of the invention, in which  FIG. 9A  shows a state where the cover member is at the cover position, and  FIG. 9B  shows the state where the developing device shown in  FIG. 9A  is grasped. 
       
    
    
     DETAILED DESCRIPTION 
     &lt;General Overview&gt; 
       [0015]    In a configuration where the support tray supports the developing device with the developing roller exposed, when the user attaches or detaches the developing device to or from the support tray, or when the user attaches or detaches the support tray to or from the apparatus main body, a hand of the user, any other member, etc., may contact the developing roller. In such a case, a scratch may be made on the developing roller, or sebum of a hand, etc., may be put on the developing roller, and supply of developer to a photosensitive member may be affected. Further, there may be caused a problem of depositing developer on the developing roller on a hand, any other member, etc., and making the hand, the member, etc., dirty. 
         [0016]    Thus, the user handling the image forming apparatus needs to replace the developing device while taking care to avoid touching of a hand or any other member on the developing roller. However, it is not convenient for the user. 
         [0017]    Therefore, illustrative aspects of the invention provide an image forming apparatus that can enhance usability thereof when a developing device is replaced. 
         [0018]    According to one illustrative aspect of the invention, there is provided an image forming apparatus comprising: an apparatus main body; a photosensitive member; a plurality of developing devices each comprising a developing roller that supplies developer to the photosensitive member; a support member, which detachably supports the plurality of developing devices, and which is able to be drawn out from the apparatus main body; and a developing device move mechanism that moves each of the developing devices to a close position where the developing roller is brought close to the photosensitive member and a distant position where the developing roller is brought away from the photosensitive member rather than at the close position, wherein each of the developing devices comprises a cover member that is movable between a cover position and an exposure position, the cover member covering the developing roller at the cover position, and the cover member exposing the developing roller at the exposure position, and wherein the image forming apparatus further comprises a cover member move mechanism that moves the cover member, the cover member move mechanism moving the cover member from the cover position to the exposure position in association with movement of the developing roller from the distant position to the close position by the developing device move mechanism, and the cover member move mechanism moving the cover member from the exposure position to the cover position in association with movement of the developing roller from the close position to the distant position by the developing device move mechanism. 
         [0019]    According to another illustrative aspect of the invention, there is provided an image forming apparatus comprising: a photosensitive member; a developing device comprising: a developing roller that supplies developer to the photosensitive member; and a cover member that is movable between a cover position and an exposure position, the cover member covering the developing roller at the cover position, and the cover member exposing the developing roller at the exposure position; a developing device move mechanism that moves the developing device to a close position where the developing roller is brought close to the photosensitive member and a distant position where the developing roller is brought away from the photosensitive member rather than at the close position; and a cover member move mechanism that moves the cover member, the cover member move mechanism moving the cover member from the cover position to the exposure position in association with movement of the developing roller from the distant position to the close position by the developing device move mechanism, and the cover member move mechanism moving the cover member from the exposure position to the cover position in association with movement of the developing roller from the close position to the distant position by the developing device move mechanism. 
         [0020]    According to the illustrative aspects of the invention, when the developing roller is at the distant position where it is made possible to draw out the support member from the apparatus main body, the cover member provided on the developing device is at the cover position covering the developing roller. Thus, when the user draws out the support member or when the user places the drawn-out support member, the user, any other member, etc., can be prevented from coming in contact with the developing roller. When the user detaches the developing device from the support member, the cover member is also at the cover position, so that the user, any other member, etc., can be prevented from coming in contact with the developing roller. Accordingly, it becomes unnecessary for the user handling the image forming apparatus to take care to avoid touching of a hand or any other member on the developing roller and the developing device can be easily replaced. 
         [0021]    Further, movement of the developing roller between the distant position and the close position and movement of the cover member between the cover position and the exposure position are associated with each other. Thus, in a single step, while the developing roller is brought close to the photosensitive member, the cover member can be opened and the developing roller can be exposed and while the developing roller is brought away from the photosensitive member, the cover member can be closed and the developing roller can be covered. Accordingly, operation when the developing device is replaced can be simplified and the time required for replacing the developing device (the time until image formation is made possible) can be shortened. 
         [0022]    According to the image forming apparatus of the invention, when the user draws out or places the support member or when the user attaches or detaches the developing device, the user, any other member, etc., can be prevented from coming in contact with the developing roller, so that the usability when the developing device is replaced can be enhanced. 
       Exemplary Embodiments 
       [0023]    Exemplary embodiments of the invention will now be described with reference to the drawings. 
       (Color Multifunction Device) 
       [0024]    As shown in  FIG. 1 , a color multifunction device  1  (one example of an image forming apparatus) includes a main body case  2  (one example of an apparatus main body) and a flat bed scanner  3  that is provided on the top of the main body case  2 . The color multifunction device  1  includes a feeder unit  4  for feeding a sheet P and an image forming unit  5  for forming an image on the fed sheet P in the main body case  2 . 
         [0025]    Incidentally, in the following description, the directions are those based on the user using the color multifunction device. That is, in  FIG. 1 , the right of the plane of the figure is “back,” the left of the plane of the figure is “front,” the front of the plane of the figure is “left,” and the back of the plane of the figure is “right.” The up and down direction of the plane of the figure is “up and down” direction. 
         [0026]    A front cover  2 A that can rotate back and forth with a lower part as a support is provided on the front of the main body case  2 . An upper cover  2 B that can rotate up and down with a back part as a support is provided at an upper part of the main body case  2 . The top face of the upper cover  2 B serves as a sheet discharge tray  2 C for storing sheets P discharged from the main body case  2 . 
         [0027]    The flat bed scanner  3  is a document reader having a known configuration and generates image data by applying light to a document and reading an image at the copying time. 
         [0028]    The feeder unit  4  is provided at the bottom of the main body case  2  and includes a sheet feed cassette  4 A detachably placed in the main body case  2  and a sheet feed mechanism  4 B for feeding a sheet P from the sheet feed cassette  4 A to the image forming unit  5 . In the feeder unit  4 , sheets P in the sheet feed cassette  4 A are fed one sheet at a time by the sheet feed mechanism  4 B to the upper image forming unit  5  (between an intermediate transfer belt  51  and a secondary transfer roller  53 ). 
         [0029]    The upper image forming unit  5  includes an exposure unit  20 , a photosensitive unit  30 , a developing unit  40 , a transfer unit  50 , and a fixing unit  60 . 
         [0030]    The exposure unit  20  is placed above the feeder unit  4  and includes a known laser emission unit, a known polygon mirror, a plurality of known lenses, a plurality of known reflecting mirrors (not shown), etc. In the exposure unit  20 , laser light emitted from the laser emission unit corresponding to each color is reflected on the polygon mirror and the reflecting mirror and passes through the lenses and then is scanned at high speed over the surface of a photosensitive drum  32 . 
         [0031]    The photosensitive unit  30  is placed above the exposure unit  20  (between the developing unit  40  and the transfer unit  50 ) and includes four photosensitive drums  32  (one example of a photosensitive member) placed in parallel in the back and forth direction and chargers  33  provided in a one-to-one correspondence with the photosensitive drums  32 . 
         [0032]    The detailed configuration of a photosensitive support frame  31  will be described later. 
         [0033]    The developing unit  40  is placed between the exposure unit  20  and the photosensitive unit  30  and includes a support member  41  and four developing devices  42 . 
         [0034]    The support member  41  includes a developing device support frame  41 A forming an outer frame and developing device holders  41 B for detachably supporting the developing devices  42 . The developing device support frame  41 A can be drawn out from the main body case  2  (see  FIG. 7 ). Each developing device holder  41 B can be swung relative to the developing device support frame  41 A as a support shaft  43  is supported rotatably on each wall in the right-left direction of the developing device support frame  41 A. 
         [0035]    Each of the developing devices  42  includes a developing roller  42 A for supplying developer to the photosensitive drums  32 , a supply roller  42 B, and a developer accommodation unit  42 D for accommodating the developer in a developing device case  42 C as an example of developing device main body forming an outer frame. Incidentally, toner is one example of the developer. The developing roller  42 A is placed above the developer accommodation unit  42 D in a state in which the developing device  42  is attached to the support member  41  (developing device holder  41 B). The developing devices  42  differ only in the color of the developer accommodated in the developer accommodation unit  42 D and are of the same configuration. 
         [0036]    In each developing device  42 , the developer in the developer accommodation unit  42 D is supplied by an agitator (reference numeral omitted) to the supply roller  42 B and further is supplied from the supply roller  42 B to the developing roller  42 A and is carried thereon. 
         [0037]    The detailed configuration of the developing unit  40  will be described later. 
         [0038]    The transfer unit  50  is placed above the photosensitive unit  30  and includes an intermediate transfer belt  51 , four primary transfer rollers  52 , a secondary transfer roller  53 , a driving roller  54 , a driven roller  55 , and a cleaning unit  56 . 
         [0039]    The intermediate transfer belt  51  is an endless belt and is stretched between the driving roller  54  and the driven roller  55  placed in parallel at a distance from each other in the back and forth direction. The photosensitive drums  32  are opposed to and in contact with the lower part of the outer peripheral surface of the intermediate transfer belt  51 , and the secondary transfer roller  53  is opposed to and in contact with the back of the outer peripheral surface. 
         [0040]    The primary transfer rollers  52  are in contact with the inner peripheral surface of the intermediate transfer belt  51  and are opposed to the photosensitive drums  32  so as to sandwich the intermediate transfer belt  51  between the primary transfer rollers  52  and the photosensitive drums  32 . The secondary transfer roller  53  is opposed to the driving roller  54  so as to sandwich the intermediate transfer belt  51  therebetween. At the transferring time, a transfer bias is applied to the primary transfer roller  52  and the secondary transfer roller  53 . 
         [0041]    The cleaning unit  56  is placed above the front of the intermediate transfer belt  51  and removes the remaining developer on the intermediate transfer belt  51  with a cleaning roller  57  and stores the developer in a developer storage unit  58 . 
         [0042]    The fixing unit  60  is placed above the back of the transfer unit  50  (above the secondary transfer roller  53  and the driving roller  54 ) and includes a heating roller  61  having a known configuration and a pressing roller  62  opposed to the heating roller  61  for pressing the heating roller  61 . 
         [0043]    In the image forming unit  5 , first the surface of each photosensitive drum  32  is uniformly charged by each charger  33  and then is exposed to laser light emitted from the exposure unit  20 . Accordingly, the potential of the exposed portion lowers and an electrostatic latent image is formed on each photosensitive drum  32  based on image data. 
         [0044]    Next, when the developing roller  42 A and the photosensitive drum  32  are opposed to and come in contact with each other, the developer carried on the developing roller  42 A is supplied to the electrostatic latent image formed on the photosensitive drum  32 . Accordingly, the developer is selectively carried on the photosensitive drum  32  and the electrostatic latent image is visualized to form a developer image. 
         [0045]    The developer images formed on the photosensitive drums  32  are transferred onto the intermediate transfer belt  51  as they are superposed in order by the action of the primary transfer rollers  52  to which a transfer bias is applied. When a sheet P supplied to the image forming unit  5  passes through the nip between the intermediate transfer belt  51  the secondary transfer roller  53 , the developer images of colors transferred onto the intermediate transfer belt  51  are transferred onto the sheet P by the action of the secondary transfer roller  53  to which a transfer bias is applied. 
         [0046]    The sheet P with the developer image transferred thereon is conveyed to the fixing unit  60  and passes through the nip between the heating roller  61  and the pressing roller  62 , whereby the developer image is thermally fixed. The sheet P with the developer image thermally fixed thereon is discharged from the main body case  2  to the outside by the discharge roller  6  and is stored on the sheet discharge tray  2 C. 
       (Photosensitive Support Frame) 
       [0047]    Next, the detailed configuration of the photosensitive support frame  31  will be discussed with reference to  FIGS. 2A to 3D . 
         [0048]    As shown in  FIG. 2C , the photosensitive support frame  31  is formed like a frame with the top and the bottom opened and has side plates (reference numeral not shown and only one side plate shown) opposed in the right-left direction for supporting the photosensitive drums  32  and the chargers  33 . As shown in  FIGS. 2A and 2B , the photosensitive support frame  31  is formed with four grooves  34  and four abutment parts  35  with equal spacing corresponding to the photosensitive drums  32  in a lower part of the inner face of the side plates opposed in the right-left direction. 
         [0049]    The groove  34  is formed of a wall  34 A shaped like U letter (inverse U shaped) projecting toward the inside in the right-left direction from the side plates opposed in the right-left direction and dented toward the top from the bottom. The groove  34  is a portion for engaging the developing device  42  (a roller shaft  140  of the developing roller  42 A) and guiding a movement of the developing device  42  moving between the close position shown in  FIGS. 2A to 2C  and the distant position shown in  FIGS. 3A to 3D  and also positioning the developing device  42  relative to the photosensitive drum  32 . 
         [0050]    The abutment part  35  is formed integrally with the wall  34 A forming the groove  34  and extends toward the front from the front end portion of the wall  34 A, the lower end of the inner face of the side plates opposed in the right-left direction. The abutment part  35  and a cover member operation part  104  (described later) are one example of a cover member move mechanism. 
       (Developing Unit) 
       [0051]    Next, the detailed configuration of the developing unit  40  will be discussed. 
         [0052]    The developing unit  40  further includes an operation bar  80  (one example of a developing device move mechanism) shown in  FIG. 2A  and a lock member  110  in addition to the above-mentioned support member  41  and developing devices  42 . The configuration of each component (part), etc., will be discussed below in detail: 
         [0053]    As shown in  FIG. 2C , the support member  41  includes the developing device support frame  41 A and the developing device holder  41 B supported swingably relative to the developing device support frame  41 A. 
         [0054]    The developing device support frame  41 A is formed substantially like a box with the top opened. As shown in  FIG. 3B , the developing device support frame  41 A is formed with four through holes  41 C each of an oblong shape at an upper part of each wall in the right-left direction. As shown in  FIG. 3A , on the outer face of each wall in the right-left direction of the developing device support frame  41 A, a pair of guides  44  and  45  extending in the back and forth direction is provided at a lower part, and a roller  46  is provided at the back ends of the guides  44  and  45 . 
         [0055]    Provided in the main body case  2  are a guide  121  extending along the guide  45 , a stopper  122  formed at the back end of the guide  121  for regulating a backward movement of the roller  46 , and a roller  123  placed above the front end of the guide  121 . 
         [0056]    The developing device holder  41 B is formed with an operation part  41 D projecting from the through hole  41 C toward the outside in the right-left direction, as shown in  FIGS. 2B and 2C . The operation part  41 D is a portion for swinging the developing device holder  41 B relative to the developing device support frame  41 A as the operation part  41 D is moved substantially up and down in the through hole  41 C of an oblong shape with the operation bar  80  (described later). 
         [0057]    The operation bar  80  is a member for moving each developing device  42  between the close position shown in  FIGS. 2A to 2C  and the distant position shown in  FIGS. 3A to 3D . As shown in  FIGS. 2A and 2B , the operation bar  80  is provided on the outer face of each wall in the right-left direction of the developing device support frame  41 A and includes a bar main body  81  and four inclination members  82 . 
         [0058]    The bar main body  81  is a rod-like member extending in the back and forth direction and is supported movably in the back and forth direction relative to the developing device support frame  41 A. The bar main body  81  on both left and right sides is joined at the front of the developing device support frame  41 A can move in one piece in the back and forth direction. An unlock part  83  having a lower end projecting downward from the bar main body  81  is provided at the back end of the bar main body  81 . 
         [0059]    The inclination members  82  are provided above the bar main body  81  with spacing to allow them to engage the operation parts  41 D and have each an upper face falling from the front to the back to form an inclining face (reference numeral omitted). The substantial front half of the inclination face is formed of a tilt member  82 A that can tilt up and down with the back end as the center. The tilt member  82 A is urged upward from below by a spring  82 B. 
         [0060]    The function of the operation bar  80  will be discussed. 
         [0061]    At the image forming time, the operation part  41 D of each developing device holder  41 B and the corresponding inclination member  82  of the operation bar  80  engage each other, as shown in  FIGS. 2A to 2C . Specifically, the operation part  41 D of each developing device holder  41 B is placed on the tilt member  82 A of the corresponding inclination member  82  and is urged upward by the spring  82 B. Accordingly, the developing device  42  attached to each developing device holder  41 B is urged toward the photosensitive drum  32 . Thus, the developing roller  42 A is brought close to the photosensitive drums  32 . 
         [0062]    At the replacing time, etc., of the photosensitive unit  30  or the developing device  42  (described later), the operation bar  80  is pulled toward the front as shown in  FIGS. 3A to 3C . Then, the engagement of the operation part  41 D of each developing device holder  41 B and the corresponding inclination member  82  of the operation bar  80  is released. 
         [0063]    Specifically, as the operation bar  80  is pulled toward the front, the bar main body  81  moves forward relative to the developing device support frame  41 A and thus each inclination member  82  provided above the bar main body  81  also moves forward from the lower part of the operation part  41 D of the corresponding developing device holder  41 B. Accordingly, nothing supports the operation part  41 D from the lower part. Thus, each developing device holder  41 B (developing device  42 ) swings downward under its own weight and the developing roller  42 A moves to the distant position from the photosensitive drum  32  from the close position. 
         [0064]    Conversely, to move the developing device  42  from the distant position to the close position, the operation bar  80  is pushed backward as shown in  FIGS. 2A to 2C . Then, the bar main body  81  moves backward relative to the developing device support frame  41 A and thus each inclination member  82  also moves backward. At this time, each operation part  41 D is placed on the tilt member  82 A along the inclination face of the corresponding inclination member  82  and is urged upward by the spring  82 B. Accordingly, the developing device  42  attached to each developing device holder  41 B is urged toward the photosensitive drum  32 . Thus, the developing roller  42 A moves to the close position. 
         [0065]    A movement of the developing device  42  is guided as the roller shaft  140  (described later) engages the groove  34  provided on the photosensitive support frame  31 . The developing roller  42 A is positioned relative to the photosensitive drum  32  as the roller shaft  140  engages the groove  34  particularly when the developing device  42  is at the close position. That is, the roller shaft  140  functions as a cover member abutment part. 
         [0066]    The lock member  110  is provided at the back of the developing device support frame  41 A as shown in  FIG. 2A ,  FIG. 3A , etc. The lock member  110  includes a rod-like member  111  that can swing back and forth with the lower end as the center, a hook  112  formed at the lower end of the rod-like member  111 , a spring  113  for urging the upper end of the rod-like member  111  in a direction away from the developing device support frame  41 A (backward), and a holding member  114  for holding the top of the rod-like member  111  and preventing the rod-like member  111  from dropping off from the developing device support frame  41 A. 
         [0067]    The lock member  110  disables a movement of the developing unit  40  relative to the main body case  2  as a claw of the hook  112  engages a lock engagement part  2 D (see  FIG. 3D ) provided in the main body case  2  in a state shown in  FIGS. 2A to 2C  in which the developing unit  40  is placed in the main body case  2  and the operation bar  80  is pushed backward. 
         [0068]    In contrast, in a state shown in  FIGS. 3A to 3D  in which the operation bar  80  is pulled forward, the unlock part  83  engages the upper end of the rod-like member  111  and swings the upper end of the rod-like member  111  forward, so that the engagement of the claw of the hook  112  and the lock engagement part  2 D (see  FIG. 3D ) is released. Accordingly, the developing unit  40  is enabled to move (be drawn) relative to the main body case  2  (see  FIG. 7 ). 
         [0069]    The developing device  42  includes the developing roller  42 A, the supply roller  42 B, and the developer accommodation unit  42 D in the developing device case  42 C. The developing device  42  further includes a cover member  100 , a grip  130 , and the roller shaft  140  as an example of a cover member abutment unit. 
         [0070]    The cover member  100  is a member for protecting the developing roller  42 A and can move between a cover position for covering the developing roller  42 A (see  FIG. 4B ) and an exposure position for exposing the developing roller  42 A (see  FIG. 4A ). More particularly, the cover member  100  is made up of a cover  101  substantially shaped like a circular ark on a side view for protecting the developing roller  42 A and an arm  102  substantially shaped like letter L on a side view formed integrally with the cover  101  at both ends in the right-left direction of the cover  101 . 
         [0071]    The arm  102  has one end portion rotatably attached to the developing device case  42 C through a rotation shaft  103  below the roller shaft  140 . Accordingly, the cover  101  (cover member  100 ) can move between the cover position and the exposure position as the cover  101  (cover member  100 ) rotates along the circumferential direction of the developing roller  42 A through the rotation shaft  103  relative to the developing device case  42 C. The arm  102  (cover member  100 ) is urged to the cover position at all times by an urging member  102 A. 
         [0072]    The arm  102  includes the cover member operation part  104  projecting to the outside in the right-left direction (axial direction of the developing roller  42 A) in a bend portion substantially shaped like letter L. The cover member operation part  104  and the abutment part  35  mentioned above configures the cover member move mechanism. The function of the cover member move mechanism (the abutment part  35  and the cover member operation part  104 ) will be described later. 
         [0073]    The grip  130  is a part grasped by the user when the user attaches the developing device  42  to the support member  41 . The grip  130  is shaped substantially like letter U on a plan view and has both end portions rotatably supported on the cover member  100  (opposite end portion of the arm  102 ) through a support part  131 . The grip  130  is urged against the cover member  100  (cover  101 ) at all times according to a known configuration using an urging member, etc. To grasp the developing device  42 , the user rotates the grip  130  upward (see  FIG. 7 ). 
         [0074]    A recess part (reference numeral omitted) to form a gap between the grip  130  and the cover member  100  (cover  101 ) is provided at the front end of the grip  130 . Thus, the user can easily rotate the grip  130  by hooking a finger, a nail, etc., in the gap (recess part). 
         [0075]    The roller shaft  140  is a shaft of the developing roller  42 A projecting from both left and right side faces of the developing device case  42 C to the outside in the right-left direction. When the cover member  100  moves from the exposure position to the cover position, the cover member  100  abuts the roller shaft  140 . A movement of the cover member  100  is regulated as the cover member  100  abuts the roller shaft  140 . 
       (Cover Member Move Mechanism) 
       [0076]    Next, the function of the cover member move mechanism (the abutment part  35  and the cover member operation part  104 ) will be discussed.  FIGS. 5A to 5C  are drawings to describe the function of the cover member move mechanism. 
         [0077]    As shown in  FIGS. 3C and 5A , when the developing device  42  is at the distant position, the cover member  100  urged against the cover position at all times is at the cover position covering the developing roller  42 A. As the operation bar  80  is pushed backward, the developing device holder  41 B (developing device  42 ) swings upward with the support shaft  43  as the center from the distant position to the close position as shown in  FIGS. 5B and 5C . 
         [0078]    At this time, the upward swinging force of the developing device holder  41 B (developing device  42 ) causes the cover member operation part  104  first to abut the back end of the abutment part  35  and further to move forward along the lower face of the abutment part  35 . Accordingly, the cover member  100  including the cover member operation part  104  rotates clockwise (in the arrow direction) in  FIGS. 5A to 5C  relatively to the developing device case  42 C. Thus, when the developing device  42  shown in  FIG. 5C  reaches the close position, the cover member  100  moves from the cover position completely to the exposure position. 
         [0079]    In contrast, as shown in  FIGS. 2C and 5C , when the developing device  42  is at the close position, the cover member  100  is at the exposure position exposing the developing roller  42 A to bring the photosensitive drum  32  and the developing roller  42 A close to each other. As the operation bar  80  is pulled forward, the developing device holder  41 B (developing device  42 ) swings downward with the support shaft  43  as the center from the close position to the distant position as shown in  FIGS. 5B and 5A . 
         [0080]    At this time, the cover member operation part  104  moves backward along the lower face of the abutment part  35  from the front end side of the abutment part  35  by the downward swinging force of the developing device holder  41 B (developing device  42 ) and the action of the urging member  102 A urging the cover member  100  against the cover position at all times. Accordingly, the cover member  100  including the cover member operation part  104  rotates counterclockwise in  FIGS. 5A to 5C  relatively to the developing device case  42 C. Thus, when the developing device  42  shown in  FIG. 5A  reaches the distant position, the cover member  100  moves from the exposure position to the cover position. 
         [0081]    As described above, the cover member move mechanism (the abutment part  35  and the cover member operation part  104 ) can move the cover member  100  from the cover position to the exposure position in association with movement of the developing roller  42 A from the distant position to the close position with the operation bar  80  and can move the cover member  100  from the exposure position to the cover position in association with movement of the developing roller  42 A from the close position to the distant position. 
       (Operation of Multifunction Device) 
       [0082]    Next, the operation of the color multifunction device  1 , specifically the operation when the photosensitive unit  30  or the developing device  42  is replaced will be discussed.  FIG. 6  is a drawing to show a state at the replacing time of the photosensitive unit and  FIG. 7  is a drawing to show a state at the replacing time of the developing device. 
         [0083]    As shown in  FIG. 6 , first the user rotates the upper cover  2 B upward and opens it and next rotates the front cover  2 A forward and opens it, thereby exposing the photosensitive unit  30  and the developing unit  40 . 
         [0084]    To replace the photosensitive unit  30 , the user raises a handle  31 H provided on the front of the photosensitive support frame  31  and pulls the handle  31 H forward. Then, a roller  31 R provided at the back end of the photosensitive support frame  31  is put on a guide  125  from a stopper  124  provided in the main body case  2  and rolls on the guide  125 , whereby the photosensitive unit  30  moves forward. Finally, the user removes the photosensitive unit  30  from the main body case  2  and places a new photosensitive unit  30  in the main body case  2 . The photosensitive unit  30  can be thus replaced. 
         [0085]    To replace the developing device  42 , first the user pulls the operation bar  80  forward for moving each developing device  42  from the close position to the distant position. At this time, the cover member  100  moves from the exposure position to the cover position in association with movement of each developing device  42  from the close position to the distant position. Then, as shown in  FIG. 7 , the user more strongly pulls the operation bar  80  forward. Accordingly, the roller  46  shown in  FIG. 2A , etc., rolls on the guide  121  and while the guide  44  rolls the roller  123 , the developing unit  40  (support member  41 ) is drawn out from the main body case  2 . 
         [0086]    The user rotates the grip  130  upward, grasps it, removes the developing device  42  from the developing device holder  41 B, and attaches a new developing device  42  to the developing device holder  41 B and then places the developing unit  40  in the main body case  2 . Then, the user pushes the operation bar  80  backward for moving each developing device  42  from the distant position to the close position. At this time, the cover member  100  moves from the cover position to the exposure position in association with movement of each developing device  42  from the distant position to the close position. The developing device  42  can be thus replaced. 
         [0087]    Last, the user rotates the front cover  2 A upward, closes it, rotates the upper cover  2 B downward, and closes it. Replacing the photosensitive unit  30  or the developing device  42  is now complete. 
       (Developing Device) 
       [0088]    Next, a desirable configuration of the developing device  42  will be discussed. 
         [0089]    As shown in  FIG. 8A , the developing device  42  of the exemplary embodiment includes the developing roller  42 A for supplying developer to the photosensitive drum  32 , the cover member  100  that can move between the cover position and the exposure position as it rotates along the circumferential direction of the developing roller  42 A through the rotation shaft  103  relative to the developing device case  42 C, the grip  130  supported on the cover member  100  through the support part  131 , and the roller shaft  140  that the cover member  100  abuts when the cover member  100  moves from the exposure position to the cover position. 
         [0090]    The cover member  100  can rotate between the cover position indicated by the solid line and the exposure position indicated by the chain line with the rotation shaft  103  as the center. The cover member  100  abuts the roller shaft  140 , whereby a movement of the cover member  100  in a direction toward the cover position from the exposure position (counterclockwise in  FIGS. 8A and 8B ) is regulated. 
         [0091]    In the developing device  42 , as shown in  FIG. 8B , it is desirable that the rotation shaft  103  should be placed on the move direction side to the cover position from the exposure position of the cover member  100  from a plane PL connecting center of gravity G of the developing device  42  and the support part  131  viewed from the axial direction of the developing roller  42 A, namely, at the left of the plane PL in  FIG. 8B . 
         [0092]    In the above-described developing device  42 , when the user grasps the grip  130  and lifts up the developing device  42 , an upward force F 1  acts on the support part  131  as shown in  FIG. 8B . At this time, the rotation shaft  103  is positioned at the left of the plane PL and the cover member  100  abuts the roller shaft  140  and thus a counterclockwise force F 2  acts on the cover member  100 . The force F 2  is a force moving the cover member  100  to the cover position (a force attempting to close the cover member  100 ) and thus can suppress opening the cover member  100  when the developing device  42  is lifted up and can prevent the user, any other member, etc., from coming in contact with the developing roller. 
         [0093]    According to the exemplary embodiments of the invention, the cover member  100  provided on the developing device  42  is at the cover position in a state in which the support member  41  can be drawn out from the main body case  2 , namely, when the developing roller  42 A is at the distant position. Thus, the user, any other member, etc., can be prevented from coming in contact with the developing roller when the user draws out or places the support member  41 . 
         [0094]    When the developing device  42  is detached from the support member  41  (developing device holder  41 B), the cover member  100  is also at the cover position, so that the user, any other member, etc., can be prevented from coming in contact with the developing roller. 
         [0095]    Thus, it becomes unnecessary for the user handling the color multifunction device  1  to take care to avoid touching of a hand or any other member on the developing roller  42 A, so that usability when the user replaces the developing device can be enhanced. 
         [0096]    Movement of the developing roller  42 A between the distant position and the close position and movement of the cover member  100  between the cover position and the exposure position are associated with each other. Thus, in a single step, while the developing roller  42 A is brought close to the photosensitive drum  32 , the cover member  100  can be opened and the developing roller  42 A can be exposed. Likewise, in a single step, while the developing roller  42 A is brought away from the photosensitive drum  32 , the cover member  100  can be closed and the developing roller  42 A can be protected. Accordingly, operation when the developing device  42  is replaced can be simplified and the time required for replacing the developing device  42 , namely, the time until image formation is made possible can be shortened, so that usability when the user replaces the developing device (operating comfortability) can be enhanced. 
         [0097]    The developing roller  42 A is placed above the developer accommodation unit  42 D in a state in which the developing device  42  is attached to the support member  41 . Thus, if no cover member is provided, the developing roller is exposed upward and thus the possibility that the user, any other member, etc., may come in contact with the developing roller when the user grasps the developing device increases. In the exemplary embodiment, the apparatus has the cover member  100  and when the support member  41  and the developing device  42  are detached, the developing roller  42 A is protected, so that the user, any other member, etc., can be prevented from coming in contact with the developing roller  42 A. That is, the invention is particularly effective for the configuration wherein the developing roller is placed at an upper part in a state in which the developing device is attached to the support member. 
         [0098]    The grip  130  is provided on the cover member  100  in the configuration wherein the developing roller  42 A is placed above the developer accommodation unit  42 D. Thus, while the user, any other member, etc., is prevented from coming in contact with the developing roller  42 A, the user can easily grasp the developing device  42 . 
         [0099]    Since the cover member move mechanism is made up of the projecting cover member operation part  104  provided for the cover member  100  and the abutment part  35  that the cover member operation part  104  abuts, provided on the photosensitive support frame  31 , the cover member  100  can be moved between the cover position and the exposure position in association with the operation bar  80  (developing device move mechanism) according to the simple configuration. 
         [0100]    The photosensitive support frame  31  includes the grooves  34  engaging the developing device  42  (roller shaft  140 ) and the abutment part  35  is formed integrally with the wall  34 A forming the groove  34 . Accordingly, a movement of the developing device  42  can be well guided by the groove  34  and the position of the developing device  42  (developing roller  42 A) relative to the photosensitive drum  32  can also be determined with constant accuracy. The groove  34  and the abutment part  35  are formed integrally, so that the abutment part  35  can be easily formed and the position accuracy of the abutment part  35  relative to the developing device  42  (cover member  100 ) can be enhanced. 
         [0101]    Since the cover member operation part  104  projects toward the outside in the axial direction of the developing roller  42 A, when the cover member operation part  104  moves, it can be prevented from interfering with the photosensitive drum  32 . 
       Modification to the Exemplary Embodiments 
       [0102]    While the present invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims 
         [0103]    In the above-described exemplary embodiment, the cover member move mechanism made up of the abutment part  35  provided on the photosensitive support frame  31  and the projecting cover member operation part  104  is illustrated, but the invention is not limited thereto. For example, in a configuration including a developing device move mechanism for allowing a developing device to move from a distant position to a close position by placing a support member in an apparatus main body, a member for guiding the support member provided in the apparatus main body may include an abutment part for abutting a cover member operation part and moving a cover member from a cover position to an exposure position. According to the configuration, the cover member can be moved from the cover position to the exposure position simply by placing the support member in the apparatus main body. That is, the operation bar  80  can be omitted. The cover member may move between the cover position and the exposure position under control in association with movement of the developing device between the distant position and the close position. 
         [0104]    In the above-described exemplary embodiment, the configuration wherein the abutment part  35  is formed integrally with the groove  34  is shown, but the invention is not limited thereto. For example, the groove  34  and the abutment part  35  may be formed separately. The dimensions of the groove and the abutment part in the right-left direction may be the same or may be different. 
         [0105]    In the above-described exemplary embodiment, the operation bar  80  made up of the bar main body  81  and the inclination members  82  is shown as an example of the developing device move mechanism, but the invention is not limited thereto. For example, the developing device move mechanism may be made up of an urging member for urging a developing device holder against a photosensitive member and an operation bar formed with a step on a lower face. According to the configuration, for example, as the operation bar moves back and forth, a recess part formed on the operation bar and an operation part projected from the developing device holder engage each other, whereby a developing device moves to a close position; the engagement of the recess part and the operation part is released, whereby the developing device moves to a distant position. As another example, a mode can also be adopted wherein as the operation bar moves back and forth, a convex part formed on the operation bar and an operation part engage each other, whereby a developing device moves to a distant position; the engagement of the convex part and the operation part is released, whereby the developing device moves to a close position. 
         [0106]    In the above-described exemplary embodiment, the support member  41  including the developing device support frame  41 A and the developing device holder  41 B is illustrated, but the invention is not limited thereto. For example, the support member may be a support member for directly supporting a developing device with no developing device holder. In the above-described exemplary embodiment, the developing device holder  41 B can swing relative to the developing device support frame  41 A, but the invention is not limited thereto. For example, the developing device holder may be made slidable relative to the developing device support frame. 
         [0107]    The desirable configuration of the developing device  42  shown in the above-described exemplary embodiment is not limited to the configuration shown in  FIGS. 8A and 8B . For example, like a developing device  242  shown in  FIGS. 9A and 9B , the shape of an arm  202  (side shape of a cover member  200 ) connecting a rotation shaft  203  of the cover member  200  and a support part  231  of a grip  230  may be different from the side shape of a cover member  100  described above. That is, the configuration of the developing device and the shapes of the components are not limited if the positional relationship among the rotation shaft, the support part, and the center of gravity satisfies the condition mentioned above. 
         [0108]    A cover member abutment part for abutting when the cover member  200  moves from an exposure position (see the chain line in  FIG. 9A ) to a cover position (see the solid line in  FIG. 9A ) is not limited to the roller shaft  140  mentioned above. For example, the cover member abutment part may be a projection part  240  projecting from a side face of a developing device case  242 C toward the outside. The position where the cover member abutment part is provided not limited if the positional relationship among the rotation shaft, the support part, and the center of gravity satisfies the condition mentioned above. 
         [0109]    In the above-described exemplary embodiment, the cover member  100  can move between the cover position and the exposure position as it rotates along the circumferential direction of the developing roller  42 A through the rotation shaft  103  relative to the developing device case  42 C, but the invention is not limited thereto. For example, the cover member  100  may be able to move between the cover position and the exposure position as it slides relative to a developing device main body. 
         [0110]    In the above-described exemplary embodiment, the configuration wherein the grip  130  is provided on the cover member  100  is shown, but the invention is not limited thereto. For example, a configuration wherein the grip is provided on the developing device main body may be adopted. No grip may be provided. To provide the grip, the configuration and the shape of the grip are not limited if the configuration and the shape allow the user to grasp the grip when attaching the developing device to the support member. 
         [0111]    In the above-described exemplary embodiment, the developing device  42  including the developing roller  42 A, the supply roller  42 B, and the developer accommodation unit  42 D is illustrated, but the invention is not limited thereto. For example, the developing device may have a configuration wherein the portion including the developing roller and the supply roller and the portion including the developer accommodation unit (developer accommodation unit) can be separated. 
         [0112]    In the above-described exemplary embodiment, the photosensitive drum  32  is illustrated as an example of photosensitive member, but the invention is not limited thereto. For example, the photosensitive member may be a photosensitive belt. 
         [0113]    In the above-described exemplary embodiment, the configuration wherein the photosensitive unit  30  and the developing unit  40  are drawn out to the front of the main body case  2  is shown, but the invention is not limited thereto. For example, the configuration may be a configuration wherein the photosensitive unit and the developing unit are drawn out from the left or the right of the apparatus main body. 
         [0114]    In the above-described exemplary embodiment, the invention is applied to the image forming apparatus (color multifunction device  1 ) including the developing device  42  having the developing roller  42 A placed above the developer accommodation unit  42 D by way of example, but the invention is not limited to the example. That is, the invention can also be applied to an image forming apparatus including a developing device having a developing roller placed below a developer accommodation unit. 
         [0115]    In the above-described exemplary embodiment, the color multifunction device  1  is shown as an example of image forming apparatus, but the invention is not limited to the example. That is, the invention can also be applied to a color copier, a color printer not including the flat bed scanner  3  (document reader), and the like. The image forming apparatus of the invention is not limited to an apparatus for exposing a photosensitive member to laser light and may be an apparatus for exposing a photosensitive member to light emitted from an LED (light emitting diode), an EL (electroluminescent) device, a phosphor, etc., for example. 
         [0116]    In the invention, the expression “the developing roller is brought close to the photosensitive member” is not limited to the case where the developing roller and the photosensitive member are in contact with each other and also contains the case where the developing roller and the photosensitive member are not in contact with each other although they are near to each other so long as it is possible to develop the photosensitive member using the developing roller. That is, the invention can be applied to both an image forming apparatus of a contact developing system and an image forming apparatus of a non-contact developing system.