Patent Publication Number: US-7215905-B2

Title: Image forming apparatus and process cartridge

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an image forming apparatus for forming the image using electrophotographic method, and a process cartridge used for the image forming apparatus. 
   2. Description of the Related Art 
   Conventionally, there have been well known an image forming apparatuses for forming the image using electrophotographic method. 
   For example, in JP-A-9-141972, an image forming apparatus having four image carriers (photosensitive members) arranged in the vertical direction is disclosed (see pages 4 through 9 and FIGS. 1 and 2). In the image forming apparatus disclosed in JP-A-9-141972, a sheet conveying belt is provided in contact with the four image carriers, and the sheet is conveyed by the sheet conveying belt to make contact with each image carrier successively, so that the image for each print color is transferred onto the sheet. Also, in this image forming apparatus, the sheet conveying belt is supported inside a front lid, and the entire conveyance path on which the sheet is conveyed is exposed to the user by opening the front lid, whereby a removal process for removing a sheet jam is simply performed. 
   The above document, JP-A-141972, has a corresponding U.S. patent application, in which the patent number thereof is U.S. Pat. No. 5,787,324. 
   SUMMARY OF THE INVENTION 
   However, in the configuration described above, the user can easily touch the image carriers by opening the front lid, resulting in a problem that the image carrier is prone to be contaminated or damaged. 
   It is therefore an object of the invention is to provide an image forming apparatus and a process cartridge in which the image carrier is prevented from being touched by the user. 
   In order to achieve the object, according to a first aspect of the invention, there is provided an image forming apparatus including: an image carrier that carries a developer image formed by developing an electrostatic latent image with a developer; a processing device configured to act on the image carrier; a frame member disposed to be movable with respect to the image carrier, the frame member supporting the processing device; a main frame formed with an opening portion facing the image carrier; a lid member disposed to be movable between an opened position in which the opening portion is opened and a closed position in which the opening portion is closed: and a moving mechanism configured to move the frame member, in conjunction with an operation of the lid member, between a first position in which the processing device acts on the image carrier and a second position in which the frame member covers a part of the image carrier. 
   According to a second aspect of the invention, there is provided a process cartridge mounted on an image forming apparatus, the process cartridge including: an image carrier that carries a developer image formed by developing an electrostatic latent image with a developer; a processing device configured to act on the image carrier: a frame member that support the process device and disposed to be movable between a first position in which the processing device acts on the image carrier and a second position in which different from the first position; and a holding mechanism that holds the frame member at the second position in a state where the process cartridge is detached from the image forming apparatus. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the present invention will become more fully apparent from the following detailed description taken with the accompanying drawings, in which: 
       FIG. 1  is a schematic side cross-sectional view of a color laser printer according to an embodiment of the present invention; 
       FIG. 2  is a schematic side cross-sectional view of the color laser printer in a state where a closing door is opened up to a position of 15 degrees; 
       FIG. 3  is a schematic side cross-sectional view of the color laser printer in a state where the closing door is opened up to a position of 45 degrees; 
       FIG. 4  is a schematic side cross-sectional view of the color laser printer in a state where the closing door is opened up to a position of 75 degrees; 
       FIG. 5  is an explanatory view for explaining a power transmission structure from the closing door to the frame member; 
       FIG. 6  is a perspective view of a process cartridge; and 
       FIG. 7  is an explanatory view of a grip for the process cartridge. 
       FIG. 8  is an explanatory view of either mounting or demounting the process cartridge. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the accompanying drawings, a description will be given in detail of a preferred embodiment of the invention. 
     FIG. 1  is a schematic side cross-sectional view for explaining an internal constitution of a color laser printer  1  as an image forming apparatus according to an embodiment of the invention. 
   As shown in  FIG. 1 , the color laser printer  1  corresponds to a so-called tandem type, and includes a sheet feeding portion  4  for supplying a sheet P one by one with a sheet feeding roller  2  and a conveying roller  3 , a sheet conveying belt  10 , looped over a drive roller  6  and a follower roller  8 , for conveying the sheet P supplied from the sheet feeding portion  4  in the vertical upper direction, four process cartridges  20 K,  20 Y,  20 M and  20 C and four laser scanner units  50 K,  50 Y,  50 M and  50 C for forming the toner image corresponding to each print color of black (K), yellow (Y), magenta (M) and cyan (C) on the sheet P conveyed by the sheet conveying belt  10 , a fixing unit  62  for fixing the toner image transferred onto the sheet P and exhausting the sheet to a sheet exhausting portion  60 , a main frame  64  for storing each unit or portion to form an appearance of the printer, and a lid member  66  for opening or closing an opening portion  64   a  provided on a front face of the main frame  64  (on the right side in  FIG. 1 ). 
   Each process cartridge  20 K,  20 Y,  20 M and  20 C includes a photosensitive drum  22 K,  22 Y,  22 M and  22 C, a charger  30 K,  30 Y,  30 M and  30 C, and a developing unit  40 K,  40 Y,  40 M and  40 C. 
   The photosensitive drum  22 K,  22 Y,  22 M and  22 C is a drum type electrophotographic photosensitive body in which an organic photoconductive layer (OPC photosensitive member) is coated on the outer circumferential face of a drum main body made of aluminum. And the photosensitive drum  22 K,  22 Y,  22 M and  22 C has its central axis (axis perpendicular to the sheet face in  FIG. 1 ) borne by the developing unit  40 K,  40 Y,  40 M and  40 C, and driven for rotation in the arrow direction (counterclockwise in FIG.  1 ) by a drive motor, not shown. 
   Each charger  30 K,  30 Y,  30 M and  30 C is supported, with a certain gap apart, by a frame member  32 K,  32 Y,  32 M and  32 C provided to be rotatable, independently of the photosensitive drum  22 K,  22 Y,  22 M and  22 C, around the central axis of the photosensitive drum  22 K,  22 Y,  22 M and  22 C as the rotation axis, so as to be out of contact with the photosensitive drum  22 K,  22 Y,  22 M and  22 C. This charger  30 K,  30 Y,  30 M and  30 C is a so-called Scorotron type for positive charging to produce a corona discharge from the charging wire made of tungsten, and constituted to positively charge uniformly the surface of the photosensitive drum  22 K,  22 Y,  22 M and  22 C. 
   Each developing unit  40 K,  40 Y,  40 M and  40 C comprises a developing roller  42 K,  42 Y,  42 M and  42 C supplying the toner onto the photosensitive drum  22 K,  22 Y,  22 M and  22 C, and a supply roller  44 K,  44 Y,  44 M and  44 C supplying the toner to the developing roller  42 K,  42 Y,  42 M and  42 C. 
   Each laser scanner unit  50 K,  50 Y,  50 M and  50 C directs a laser beam L onto the photosensitive drum  22 K,  22 Y,  22 M and  22 C of the corresponding process cartridge  20 K,  20 Y,  20 M and  20 C, and scans the laser beam L along a direction of the rotation axis of the photosensitive drum  22 K,  22 Y,  22 M and  22 C. 
   Hereinafter, a basic operation of the color laser printer  1  will be briefly described below. 
   In the process cartridge  20 K,  20 Y,  20 M and  20 C, the surface of the photosensitive drum  22 K,  22 Y,  22 M and  22 C is positively charged uniformly by the charger  30 K,  30 Y,  30 M and  30 C, along with the rotation of the photosensitive drum  22 K,  22 Y,  22 M and  22 C, and exposed by fast scanning of laser beam L from the laser scanner unit  50 K,  50 Y,  50 M and  50 C to form an electrostatic latent image corresponding to each print color. 
   Then, when the positively charged toner carried on the developing roller  42 K,  42 Y,  42 M and  42 C is opposed to and makes contact with the photosensitive drum  22 K,  22 Y,  22 M and  22 C, with the rotation of the developing roller  42 K,  42 Y,  42 M and  42 C, the toner is supplied to the electrostatic latent image formed on the surface of the photosensitive drum  22 K,  22 Y,  22 M and  22 C, namely, an exposure portion exposed to laser beam L and having lower potential on the uniformly, positively charged surface of the photosensitive drum  22 K,  22 Y,  22 M and  22 C, and selectively carried to form the toner image. 
   On the other hand, the sheet P is supplied from the sheet feeding portion  4  between the conveying roller  3  and the sheet conveying belt  10 , conveyed in an upper direction by the sheet conveying belt  10 , and exhausted via the fixing unit  62  into the sheet exhausting portion  60 , as indicated by the arrow A. 
   And the toner image formed on the surface of the photosensitive drum  22 K,  22 Y,  22 M and  22 C is successively transferred onto the sheet P conveyed by the sheet conveying belt  10 . Herein, the toner image for each color is formed with a slight time difference according to the moving speed of the sheet conveying belt  10  and the distance between the photosensitive drums  22 K,  22 Y,  22 M and  22 C, and thereby transferred onto the sheet P and superposed thereon to form a color image. 
   Lastly, the toner image transferred onto the sheet P is fixed on the sheet P by the fixing unit  62 . Then, the sheet P is exhausted into the sheet exhausting portion  60 . 
   In the color laser printer  1 , a process cartridge  20 K,  20 Y,  20 M and  20 C is mounted or demounted via an opening portion  64   a  in a state where the lid member  66  is opened. 
   That is, in the color laser printer  1 , the lid member  66  is opened or closed by rotation around a rotation axis  66   a  parallel to the rotation axis of the photosensitive drum  22 K,  22 Y,  22 M and  22 C. Furthermore, the drive roller  6  and the follower roller  8  are supported inside the lid member  66 . Therefore, if the lid member  66  is opened, the sheet conveying belt  10  is moved integrally with the lid member  66 ,  80  that the process cartridge  20 K,  20 Y,  20 M and  20 C is exposed to the opening portion  64   a.    
   However, since the process cartridge  20 K,  20 Y,  20 M and  20 C is exposed to the opening portion  64   a  in the way described above, the user may touch the photosensitive drum  22 K,  22 Y,  22 H and  22 C. 
   Thus, in the color laser printer  1 , the frame member  32 K,  32 Y,  32 M and  32 C in the process cartridge  20 K,  20 Y,  20 M and  20 C is moved from a first position where the charger  30 K,  30 Y,  30 M and  30 C charges the photosensitive drum  22 K,  22 Y,  22 M and  22 C to a second position of covering a part of the opening portion  64   a  in the photosensitive drum  22 K,  22 Y,  22 M and  22 C in conjunction with an opening or closing operation of the lid member  66 , as shown in  FIGS. 1 through 4 . 
   More specifically, while the lid member  66  is opened from a closed position (at this time, the angle of the lid member  66  is defined as 0 degree) as indicated in  FIG. 1  to a position of 15 degrees (half-opened position) as indicated in  FIG. 2 , the frame member  32 K,  32 Y,  32 M and  32 C is held at the position as indicated in  FIG. 1 . 
   And when the lid member  66  is further opened from the position of 15 degrees as indicated in  FIG. 2 , the frame member  32 K,  32 Y,  32 M and  32 C starts the movement from a first position to a second position in conjunction with the lid member  66 . In a state where the lid member  66  is opened at a position of 75 degrees (full opened position) as indicated in  FIG. 4 , the frame member  32 K,  32 Y,  32 M and  32 C is located between the first position and the second position. 
   As described above, the frame member  32 K,  32 Y,  32 M and  32 C is rotated about 90 degrees around the rotation axis of the photosensitive drum  22 K,  22 Y,  22 M and  22 C in conjunction with an operation of the lid member  66  to move from the closed position to the opened position. 
   Hereinafter, a structure for operating the lid member  66  and the frame member  32 K,  32 Y,  32 M and  32 C in conjunction will be described. 
   As shown in  FIG. 5 , a frame gear  34 K,  34 Y,  34 M and  34 C having the central axis identical to the rotation axis of the frame member  32 K,  32 Y,  32 M and  32 C is secured in the frame member  32 K,  32 Y,  32 M and  32 C of the process cartridge  20 K,  20 Y,  20 M and  20 C. 
   A door gear  68  having the central axis identical to the rotation axis  66   a  of the lid member  66  is secured in the lid member  66 . Herein, the door gear  68  is partially formed with the teeth in the circumferential direction, and does not mesh with an intervening gear  70  ( FIG. 5 ), while the lid member  66  is positioned from 0 to 15 degrees, and meshes with the intervening gear  70  ( FIG. 6 ) when the lid member  66  is opened beyond 15 degrees. 
   The main frame  64  is provided with the intervening gear  70  axially supported rotatably around the rotation axis parallel to the rotation axis  66   a  of the lid member  66  at a lower end position of the opening portion  64   a , and that can mesh with the door gear  68 . 
   A long slide member  72  is provided at an edge position of the opening portion  64   a.    
   The slide member  72  is formed with long holes  72   a  and  72   b  at two upper and lower positions, in which the guide shafts  78   a  and  78   b  secured to the main frame  64  are inserted into the long holes  72   a  and  72   b . Therefore, the slide member  72  is slidable on the main frame  64  up and down in the vertical direction. 
   An upper end of the slide member  72  is connected via a spring  80  to the main frame  64 , and always pulled in the upper direction. A movable upper range of the slide member  72  is restricted by a stopper  82  of the main frame  64 . 
   The slide member  72  is formed on the straight line with the rack gears  74 K,  74 Y,  74 M and  74 C meshing with the frame gears  34 K,  34 Y,  34 M and  34 C provided in the frame members  32 K,  32 Y,  32 M and  32 C in the process cartridges  20 K,  20 Y,  20 M and  20 C, respectively, as well as a rack gear  76  meshing with the intervening gear  70  at a lower end position of the opening portion  64   a , and the notch portions  79 K,  79 Y,  79 M and  79 C which are as large as to allow the frame gear  34 K,  34 Y,  34 H or  34 C to pass (particularly when the process cartridge  20 K,  20 Y,  20 M or  20 C is mounted or demounted). 
   With such structure, in a process of opening the lid member  66  from the closed state to the open state, the door gear,  68  and the intervening gear  70  are not meshed, so that the slide member  72  is directly contacted with the stopper  82 , and the frame member  32 K,  32 Y,  32 M and  32 C of the process cartridge  2 . 0 K,  20 Y,  20 M and  20 C are kept at the first position and not displaced, while the lid member  66  is opened from the closed position up to a position of 15 degrees, as shown in  FIG. 5 . 
   When the lid member  66  is opened to the position of 15 degrees, the door gear  68  and the intervening gear  70  are meshed. Therefore, when the lid member  66  is further opened, the slide member  72  is moved downwards against a bias of the sprint  80  with the rotation of the intervening gear  70 . Whereby, the frame gears  34 K,  34 Y,  34 M and  34 C are rotated, so that the frame members  32 K,  32 Y,  32 M and  32 C are displaced toward the second position. 
   When the lid member  66  is further opened, the rack gear  74 K,  74 Y,  74 M and  74 C of the slide member  72  and the frame gear  74 K,  34 Y,  34 M and  34 C are not meshed, so that the frame gear  34 K,  34 Y,  34 M and  34 C is opposed to the notch portion  79 K,  79 Y,  79 M and  79 C, as shown in  FIG. 6 . Herein, the process cartridge  20 K,  20 Y,  20 M and  20 C is provided with a spring  36 K,  36 Y,  36 M and  36 C for holding the frame member  32 K,  32 Y,  32 M and  32 C at the second position through a shaft  23 K,  23 Y,  23 M and  23 C of the photosensitive drum  22 K,  22 Y,  22 M and  22 C, as shown in  FIG. 7 . The spring  36 K,  36 Y,  36 M and  36 C has one end contacted with a stopper portion (not shown) provided in a supporting member  24 K,  24 Y,  24 M and  24 C (secured to the developing unit  40 K,  40 Y,  40 M and  40 C) for rotatably supporting the shaft  23 K,  23 Y,  23 M and  23 C of the photosensitive drum  22 K,  22 Y,  22 H and  22 C. The other end of the spring  36 K,  36 Y,  36 M and  36 C is contacted with a stopper portion (not shown) provided in the frame member  32 K,  32 Y,  32 M and  32 C. Whereby, the frame member  32 K,  32 Y,  32 M and  32 C is urged in a direction from the first position to the second position by the spring  36 K,  36 Y,  36 M and  36 C. The supporting member  24 K,  24 Y,  24 M and  24 C is formed with a protruding portion  25 K,  25 Y,  25 M and  25 C that is contacted with the lower face of the frame member  32 K,  32 Y,  32 M and  32 C, whereby the frame member  32 K,  32 Y,  32 M and  32 C is positioned. Therefore, even when the frame gear  34 K,  34 Y,  34 M and  34 C and the rack gear  74 K,  74 Y,  74 M and  74 C are not meshed, the frame member  32 K,  32 Y,  32 M and  32 C is kept at the second position, because the lower face is contacted with the protruding portion  25  owing to a bias force of the spring  36 K,  36 Y,  36 M and  36 C. The frame member  32 K,  32 Y,  32 M and  32 C is rotatable only between the first position and the second position, and kept at the second position, because the lower face of the frame member  32 K,  32 Y,  32 M and  32 C is contacted with the protruding portion  25 K,  25 Y,  25 M and  25 C by being urged in one direction by the spring  36 K,  36 Y,  36 M and  36 C and, as previously described. 
   The process cartridge  20 K,  20 Y,  20 M and  20 C can be mounted or demounted in a state of  FIG. 6 . Herein, a grip (concave portion in this embodiment)  38 K,  38 Y,  38 M and  38 C for allowing the user to hold the process cartridge  20 K,  20 Y,  20 M and  20 C in mounting or demounting is formed on the outer face of the frame member  32 K,  32 Y,  32 N and  32 C, whereby the process cartridge  20 K,  20 Y,  20 M and  20 C can be easily mounted or demounted, as shown in  FIG. 8 . 
   In a state where the lid member  66  is at the closed position, the slide member  72  is pulled upwards by the spring  80 , exerting a closing force on the lid member  66 , but the lid member  66  is kept open even when the user does not hold the lid member  66 , because a gravitational force on the lid member  66  and the members (drive roller  6 , follower roller  8 , sheet conveying belt  10 ) borne on this lid member  66  is greater than the closing force. 
   On the other hand, in a process of closing the lid member  66 , the slide member  72  is moved upwards in conjunction with an operation of closing the lid member  66 . When the rack gear  74 K,  74 Y,  74 M and  74 C of the slide member  72  meshes with the frame gear  34 K,  34 Y,  34 M and  34 C, the frame member  32 K,  32 Y,  32 M and  32 C starts to be moved from the second position to the first position. 
   Thereafter, when the lid member  66  is at the position of 15 degrees, the door gear  68  and the intervening gear  70  are not meshed. Therefore, the slide member  72  is pulled upwards by the spring  80  and moved, and stopped at the position against the stopper  82 . Accordingly, the frame gear  34 K,  34 Y,  34 M and  34 C is rotated by the rack gear  74 K,  74 Y,  74 M and  74 C of the slide member  72 , so that the frame member  32 K,  32 Y,  32 M and  32 C is moved to the first position. 
   In the color laser printer  1  of the embodiment, each photosensitive drum  22 K,  22 Y,  22 M and  22 C functions as the image carrier, each charger  30 K,  30 Y,  36 M and  30 C functions as the processing device, the main frame  64  functions as the main frame, and the lid member  66  functions as the closing member. Each frame gear  34 K,  34 Y,  34 M and  34 C functions as the engaged portion, the slide member  72  functions as the engaging member, and the frame gears  34 K,  34 Y,  34 M and  34 C, the door gear  68 , the intervening gear  70  and the slide member  72  function as the moving mechanism. The sheet conveying belt  10  functions as the transfer unit, and each spring  36 K,  36 Y,  36 M and  36 C, each protruding portion  25 K,  25 Y,  25 M and  25 C (also called the direct contact portion), and the lower face (contacted portion) of each frame member  32 K,  32 Y,  32 M and  32 C function as the holding mechanism. 
   As described above, in the color laser printer  1  of the embodiment, it is possible to prevent the user from touching the photosensitive drum  22 K,  22 Y,  22 M and  22 C in a state where the lid member  66  is opened. In the color laser printer  1 , no dedicated parts for covering the photosensitive drums  22 K,  22 Y,  22 M and  22 C are not employed, whereby the printer  1  is reduced in size and cost. 
   In the color laser printer  1 , the frame member  32 K,  32 Y,  32 M and  32 C are rotated around the central axis of the photosensitive drum  22 K,  22 Y,  22 M and  22 C as the rotation axis, whereby the distance between the charger  30 K,  30 Y,  30 N,  30 C and the photosensitive drum  22 K,  22 Y,  22 M,  22 C is kept constant, irrespective of the position of the frame member  32 K,  32 Y,  32 M and  32 C. Therefore, even if the first position is more or less changed due to a variation in the movement amount of the frame member  32 K,  32 Y,  32 M and  32 C, the charger  30 K,  30 Y,  30 M and  30 C is normally operated on the photosensitive drum  22 K,  22 Y,  22 M and  22 C. 
   In the color laser printer  1 , since the charger  30 K,  30 Y,  30 M and  30 C is provided on the photosensitive drum  22 K,  22 Y,  22 M and  22 C without contact, the surface of the photosensitive drum  22 K,  22 Y,  22 M and  22 C is not damaged by movement of the charger  30 K,  30 Y,  30 M and  30 C. 
   In the color laser printer  1 , the frame member  32 K,  32 Y,  32 M and  32 C is not moved from the first position to the second position, until the lid member  66  is opened to some extent from the closed position, whereby the frame member  32 K,  32 Y,  32 M and  32 C is out of contact with the sheet conveying belt  10 . 
   Particularly, in the color laser printer  1 , since the rotation axis  66   a  of the lid member  66  is parallel to the rotation axes of the photosensitive drums  22 K,  22 Y,  22 M and  22 C, the photosensitive drums  22 K,  22 Y,  22 M and  22 C are effectively protected. That is, when a closing door (transverse closing door) rotatable around the rotation axis perpendicular to the rotation axis of the photosensitive drum  22 K,  22 Y,  22 M and  22 C is employed instead of the lid member  66 , the distance between the photosensitive drum  22 K,  22 Y,  22 M and  22 C and the sheet conveying belt  10  is longer on the side apart from the rotation axis of the closing door, in which the photosensitive drum is touched by the user, but the distance between the photosensitive drum  22 K,  22 Y,  22 M and  22 C and the sheet conveying belt  10  is shorter on the side nearer to the rotation axis of the closing door, in which the frame member  32 K,  32 Y,  32 M and  32 C is not moved to the second position. 
   In the color laser printer  1 , since the grip  38 R,  38 Y,  38 M and  38 C is formed on the outer face of the frame member  32 K,  32 Y,  32 M and  32 C, the user can easily mount or demount the process cartridge, and be effectively prevented from touching the photosensitive drum  22 K,  22 Y,  22 M and  22 C. In addition, since the grip  38 K,  38 Y,  38 M and  38 C is concave portion formed the outer face of the frame member  32 K,  32 Y,  32 M and  32 C, there is no excess bulge, contributing to the reduction in the size of the color laser printer  1 . Even in a state where the process cartridge  20 K,  20 Y,  20 M and  20 C is singly provided, the frame member  32 K,  32 Y,  32 M and  32 C is kept at the second position, facilitating the mounting or demounting operation. 
   In this color laser printer  1 , since four process cartridges  20 K,  20 Y,  20 M and  20 C are disposed in parallel to face the opening portion  64   a , a desired process cartridge  20 K,  20 Y,  20 M and  20 C is easily mounted or demounted. Moreover, since the entire conveyance path for the sheet P is exposed to the user, a sheet removal operation for removing the sheet is easily performed, when there is a sheet jam. 
   In addition, the process cartridge  20 K,  20 Y,  20 M and  20 C for use in the color laser printer  1  has a reduced thickness in the up and down direction, when the frame member  32 K,  32 Y,  32 N and  32 C is moved from the first position to the second position. That is, when the frame member  32 K,  32 Y,  32 M and  32 C is at the first position, the charger  30 K,  30 Y,  30 M and  30 C is disposed not to overlap the photosensitive drum  22 K,  22 Y,  22 M and  22 C in the direction where the process cartridge  20 K,  20 Y,  20 M and  20 C is mounted or demounted. On the other hand, when the frame member  32 K,  32 Y,  32 M and  32 C is at the second position, the charger  30 K,  30 Y,  30 M and  30 C is disposed to overlap the photosensitive drum  22 K,  22 Y,  22 M and  22 C in the direction where the process cartridge  20 K,  20 Y,  20 M and  20 C is mounted or demounted. Therefore, the thickness of the process cartridge  20 K,  20 Y,  20 M and  20 C in a direction orthogonal to the direction where the process cartridge  20 K,  20 Y,  20 M and  20 C is mounted or demounted is reduced in performing the mounting or demounting operation. Accordingly, even when the process cartridge  20 K,  20 Y,  20 M and  20 C is disposed in proximity within the printer  1 , the process cartridge  20 K,  20 Y,  20 M and  20 C is easily mounted or demounted. As a result, the color laser printer  1  is effectively made smaller. 
   Although one embodiment of the invention has been described above, the present invention may be implemented in various forms. 
   For example, the color laser printer  1  of the embodiment, four frame members  32 K,  32 Y,  32 N and  32 C are moved at the same time in conjunction with an opening or closing operation of the lid member  66 . Alternatively, four frame members  32 K,  32 Y,  32 M and  32 C may start to be moved at different timings. More specifically, the frame member  32 K,  32 Y,  32 M and  32 C nearer to the rotation axis  66   a  of the lid member  66  may start to be moved later, along with an opening operation of the lid member  66  from the closed position to the opened position. The above described configuration is easily realized by changing the position of the rack gear  74 K,  74 Y,  74 M and  74 C in the slide member  72 . 
   Also, for example, the frame member  32 K,  32 Y,  32 M and  32 C nearer to the rotation axis  66   a  of the lid member  66  may have a smaller amount of movement relative to the amount of movement of the lid member  66 . The above configuration is easily realized by increasing the diameter of the frame gear  34 K,  34 Y,  34 M and  34 C nearer to the rotation axis  66   a  of the lid member  66 . 
   Although in the embodiment described above, the invention is applied to the color laser printer  1 , the invention may be also applied to the color facsimile apparatus or the color copying machine. 
   According to the image forming apparatus of the present invention, the image carrier is prevented from being touched by the user while the opening portion of the main frame is opened. Particularly, because the image carrier is protected by moving the processing device, the apparatus has a smaller size and lower cost than when any specific part for protecting the image carrier is provided. 
   According to another aspect of the present invention, the image forming apparatus is characterized in that the moving mechanism moves the frame member from the second position to the first position in conjunction with an operation of the lid member to move from the opened position to the closed position. Whereby, the processing device is restored to the position acting on the image carrier by a closing operation of the lid member. 
   According to another aspect of the present invention, the frame member may be moved in conjunction with an opening or closing operation of the lid member. 
   For example, the moving mechanism may include an engaged portion provided on the frame member, and an engaging member provided engageably with the engaged portion to move in conjunction with an opening or closing operation of the lid member, in which the frame member is moved by performing the opening or closing operation of the lid member in a state where the engaging member engages the engaged portion. With this configuration, the frame member is mechanically linked with the lid member and moved. 
   According to another aspect of the present invention, the frame member may be rotated around a rotation axis as the center of rotation. With this configuration, the frame member is moved in a simple structure. 
   Particularly, the image carrier may be formed in the shape of drum (cylinder), and the frame member is rotated around a central axis of the image carrier as the rotation axis. Thereby, the processing device is moved in a least area, which is advantageous for making the apparatus smaller. In addition, with this configuration, since the distance between the processing device and the image carrier is kept constant at any time, the processing device can be act on the image carrier under the fixed conditions without strictly controlling the position of the processing device in the rotational direction. 
   According to another aspect of the present invention, a transfer unit may further be included, the transfer unit for transferring a developer image on the image carrier to the transfer medium, the transfer unit being borne on the lid member. With this configuration, since the transfer unit is moved along with the lid members when the lid member performs an opening operation, the image carrier is directly exposed to the opening portion side. However, in the image forming apparatus of the invention, a part of the image carrier on the side of the opening portion is covered by movement of the frame member, whereby the image carrier is prevented from being exposed to the opening portion side. 
   According to another aspect of the present invention, the processing device may be configured to act on the image carrier out of contact with the image carrier. With this configuration, when the processing device is moved, the image carrier is prevented from being damaged by the processing device. 
   According to another aspect of the present invention, the moving mechanism may be configured to start to move the frame member from the first position to the second position at the time when the lid member is moved from the closed position to a specified half-opened position between the closed position and the opened position, With this configuration, the frame member or the processing device is prevented from contacting with the lid member or a member moving together with the lid member that exists on the movement path of the frame member or the processing device when the frame member is moved from the first position to the second-position. 
   For example, the lid member may be configured to be opened or closed around a rotation axis parallel to the rotation axis of the image carrier. That is, when the lid member is opened or closed around a rotation axis perpendicular to the rotation axis of the image carrier, a portion of the image carrier far away from the rotation axis of the lid member is exposed to the opening portion side, along with an opening operation of the lid member, but a portion of the image carrier closer to the rotation axis of the lid member has a shorter distance to the lid member or the member moving together with the lid member, resulting in a problem that the frame member is not moved. 
   According to another aspect of the present invention, a plurality of image carriers and a plurality of processing devices may further be included, the image carriers and the processing devices acting on the image carriers, in which the moving mechanism moves each frame member supporting each of the processing device and provided movably on each of the image carriers in conjunction with an operation of the lid member. With this configuration, the plurality of image carriers are protected by the opening operation of the common lid member. 
   According to another aspect of the present invention, an image carrier, a processing device acting on the image carrier, and a frame member supporting the processing device and provided movably on the image carrier, in which a process cartridge is provided detachably via the opening portion in the image forming apparatus, may further be included. With this configuration, the image carrier is prevented from being touched by the user in mounting or demounting the process cartridge. 
   For example, the image forming apparatus may further include a grip for detaching the process cartridge from the image forming apparatus, the grip provided on the frame member supporting the processing device of the process cartridge. Thereby, the process cartridge is easily mounted or demounted. In addition, the image carrier is prevented from being touched by the user. 
   Further, the image forming apparatus may be configured so that the process cartridge includes a holding mechanism for holding the frame member at the second position in a state where the process cartridge is removed from the image forming apparatus. Thereby, the process cartridge is easily mounted on the image forming apparatus. 
   In addition, the image forming apparatus may be configured so that the processing device is disposed not to overlap the image carrier in a direction of detaching the process cartridge at the first position and to overlap the image carrier in the direction of detaching the process cartridge at the second position. Thereby, the thickness of the process cartridge in a direction orthogonal to the direction of mounting or demounting is reduced at the time of mounting or demounting the process cartridge. As a result, the process cartridge is easily mounted or demounted. Also, it is possible to contribute to smaller size of the image forming apparatus. 
   Further, the image forming apparatus may be configured so that a process cartridge mounted on an image forming apparatus is provided, and including an image carrier for carrying a developer image formed by developing an electrostatic latent image with a developer, a frame member for supporting processing device acting on the image carrier, the frame member being provided movably on the image carrier between a first position where the processing device acts on the image carrier and a second position different from the first position, and holding mechanism for holding the frame member at the second position. With this configuration, the processing device operates as a protective member for covering a protection subject portion on the image carrier while it is unnecessary to act on the image carrier. 
   The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiment was chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.