Patent Publication Number: US-10324415-B2

Title: Developing cartridge and drum cartridge configuration for mounting to an image forming apparatus having an electric contact

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application No. 2017-090454 filed Apr. 28, 2017. The entire content of the priority application is incorporated herein by reference. 
     TECHNICAL FIELD 
     The disclosure relates to an image forming apparatus. 
     BACKGROUND 
     There is an electrophotographic image forming apparatus known in the prior art such as a laser printer and LED printer. The image forming apparatus includes a developing cartridge, which has a developing roller for supplying a developing agent. 
     The developing cartridge in the art is attached to a drum cartridge, which includes a photosensitive drum. In a state where the photosensitive drum is attached to the drum cartridge, the photosensitive drum and the developing roller contact with each other, and accordingly, the drum cartridge attached to the developing cartridge is attached to the image forming apparatus. 
     SUMMARY 
     Further, there is a developing cartridge known in the prior art that includes a storage medium. The storage medium is an IC chip, for example. The storage medium has an electric contact surface, which contacts with a terminal portion of the image forming apparatus. During detachment of the developing cartridge from the image forming apparatus, the electric contact surface rubs against a portion of the image forming apparatus. 
     The object of the disclosure is to reduce rubbing of the electric contact surface in the image forming apparatus that uses the developing cartridge having the electric contact surface. 
     According to one aspect, an image forming apparatus including a developing cartridge, a drum cartridge, electric contact, and a frame. The developing cartridge includes a casing, a storage medium, and a holder. The developing roller is rotatable about a first rotating axis extending in a first direction. The casing is configured to accommodate a developing agent and having one end portion in a second direction where the developing roller is positioned. The storage medium has an electric contact surface. The holder is positioned at one end portion of the casing in the first direction, and holds the electric contact surface. The holder has a first outer surface, a second outer surface, and a resilient member. The first outer surface is positioned at one side of the holder in a third direction crossing the electric contact surface, and holds the electric contact surface. The second outer surface is positioned at another side of the holder in the third direction, and is positioned away from the first outer surface in the third direction. The resilient member is positioned between the first outer surface and the second outer surface, and is configured to be compressed and expanded in the third direction. The drum cartridge includes a photosensitive drum rotatable about a second rotating axis extending in the first direction. The electric contact is configured to be in contact with the electric contact surface. The developing cartridge is attachable to the frame in a state where the developing cartridge is attached to the drum cartridge. The frame has a first guide surface configured to guide at least a part of the first outer surface, and is configured to contact with at least a part of the first outer surface during attachment of the developing cartridge to the frame. The first guide surface has a first contact surface positioned opposite to the developing roller in the second direction with respect to the electric contact surface. The holder is movable relative to the frame from a first position to a second position during detachment of the developing cartridge from the frame. In a state where the holder is positioned at the first position, the resilient member has a first length in the third direction and the electric contact surface is in contact with the electric contact. In a state where the holder is positioned at the second position, the resilient member has a second length in the third direction longer than the first length and the electric contact surface is in contact with the electric contact. In a state where the holder moves from the first position to the second position, the holder pivots about a part of the first outer surface in a state where the holder is in contact with the first contact surface of the first guide surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The particular features and advantages of the disclosure will become apparent from the following description taken in connection with the accompanying drawings, in which: 
         FIG. 1  is a conceptual view of an image forming apparatus according to an embodiment; 
         FIG. 2  is a perspective view of a process cartridge according to the embodiment; 
         FIG. 3  is a perspective view of a developing cartridge according to the embodiment; 
         FIG. 4  is a perspective view of a drum cartridge according to the embodiment; 
         FIG. 5  illustrates a cross-section of a drum cartridge supporting portion taken adjacent to one of slots according to the embodiment; 
         FIG. 6  is a cross-sectional view of a first guide surface and a second guide surface according to the embodiment; 
         FIG. 7  is a plan view of the first guide surface and the second guide surface; 
         FIG. 8  illustrates detaching process of the process cartridge in which the process cartridge is detached from the drum cartridge supporting portion; 
         FIG. 9  illustrates detaching process of the process cartridge in which the process cartridge is detached from the drum cartridge supporting portion; 
         FIG. 10  is an enlarged view of a holder according to the embodiment and an adjacent area of the holder; 
         FIG. 11  illustrates detaching process of the process cartridge in which the process cartridge is detached from the drum cartridge supporting portion; and 
         FIG. 12  is an enlarged view of the holder and an adjacent area of the holder. 
     
    
    
     DETAILED DESCRIPTION 
     An image forming apparatus  100  according to an embodiment will be described while referring to the accompanying drawings wherein like parts and components are designated by the same reference numerals to avoid duplicating description. 
     &lt;1. Configuration of Image Forming Apparatus&gt; 
       FIG. 1  is a conceptual view of the image forming apparatus  100 . A laser printer and an LED printer are examples of the image forming apparatus  100 . 
     The image forming apparatus  100  has four process cartridges  10  and a drum cartridge holder  90 . The process cartridge  10  includes a developing cartridge  1  and a drum cartridge  2 . The developing cartridge  1  is attached to the drum cartridge  2 . The four developing cartridges  1  accommodate developing agents having different colors from each other, such as cyan, magenta, yellow, and black. It is noted that the number of developing cartridges may be from one to three, or more than four. The drum cartridge holder  90  is a frame to which the process cartridge  10  is attached. The drum cartridge holder  90  includes four slots  91 . Each process cartridge  10  is attached to each slot  91 . The image forming apparatus  100  forms images on printing faces of printing sheets by the developing agents (toner, for example) supplied from each developing cartridge  1  in the four process cartridges  10 . 
     Each of the four developing cartridges  1  has an IC chip  51 . The IC chip  51  is a storage medium, which information can be read out from and written in. The image forming apparatus  100  includes a control unit  80 . In a state where the process cartridge  10  is attached to the slot  91  of the drum cartridge holder  90 , the IC chip  51  of each developing cartridge  1  and the control unit  80  are electrically connected. The control unit  80  is configured of a circuit board. The control unit  80  includes a processor such as a CPU and several types of memories. The control unit  80  executes processes in the image forming apparatus  100  with the processor working in accordance with programs. 
     &lt;2. Process Cartridge&gt; 
     &lt;2.1 Developing Cartridge&gt; 
       FIG. 2  is a perspective view of the process cartridge  10 . As described above, the process cartridge  10  includes the developing cartridge  1  and the drum cartridge  2 . The developing cartridge  1  is attachable to and detachable from the drum cartridge  2 . The user of the image forming apparatus  100  can exchange only one of the developing cartridge  1  and the drum cartridge  2  for a new cartridge. Accordingly, each product life of the developing cartridge  1  and the drum cartridge  2  can be consumed efficiently. 
       FIG. 3  is a perspective view of the developing cartridge  1 .  FIG. 3  indicates an exploded view of a part of the developing cartridge  1 . As illustrated in  FIG. 3 , the developing cartridge  1  includes a casing  11 , an agitator  20 , a developing roller  30 , a gear portion  40 , and an IC chip assembly  50 . 
     The casing  11  is a housing configured to accommodate a developing agent. The casing  11  extends in one direction. Hereinafter, in a state where the developing cartridge  1  is attached to the image forming apparatus  100 , the direction in which the casing  11  extends will be referred to as “first direction.” The direction crossing (preferably, perpendicular to) the first direction will be referred to as “second direction.” In a state where the developing cartridge  1  is attached to the image forming apparatus  100 , the developing roller  30  is positioned at one end portion of the casing  11  in the second direction. The second direction is also the attaching and detaching direction of the process cartridge  10  relative to the slot  91  of the drum cartridge holder  90  of the image forming apparatus  100 . The direction crossing (preferably, perpendicular to) both of the first and second directions will be referred to as “third direction.” Here, in a state where the developing cartridge  1  is attached to the image forming apparatus  100 , the third direction crosses an electric contact surface  511  of the IC chip  51 , which will be described later. 
     The casing  11  therein has an accommodating chamber  13 . The developing agent is accommodated in the accommodating chamber  13 . The casing  11  has an opening  14 . The opening  14  is positioned at an end portion of the casing  11  in an attaching direction, in which the developing cartridge  1  is attached to the drum cartridge  2 . The accommodating chamber  13  and the external space of the casing  11  are communicated through the opening  14 . 
     The agitator  20  includes an agitator shaft  21  and an agitator blade  22 . The agitator shaft  21  extends in the first direction. The agitator blade  22  expands radially outward from the agitator shaft  21 . The agitator blade  22  and a part of the agitator shaft  21  are positioned inside of the accommodating chamber  13 . The gear portion  40  includes an agitator gear that is connected to one end portion of the agitator shaft  21  in the first direction. The agitator shaft  21  and the agitator blade  22  is rotatable together with the agitator gear. When the agitator blade  22  rotates, the developing agent in the accommodating chamber  13  is agitated. 
     The developing roller  30  is rotatable about a rotating axis (first rotating axis) extending in the first direction. The developing roller  30  is positioned at the opening  14  of the casing  11 . The developing roller  30  includes a developing roller body  31  and developing roller shaft  32 . The developing roller body  31  is a cylindrical member extending in the first direction. The developing roller body  31  is made from material such as rubber having resiliency. The developing roller shaft  32  is made from material such as metal or resin that has electrical conductivity. The developing roller body  31  is fixed to the developing roller shaft  32  so that the developing roller body  31  cannot rotate relative to the developing roller shaft  32 . 
     The gear portion  40  includes a developing roller gear, and an end portion of the developing roller shaft  32  in the first direction is fixed to the developing roller gear so that the end portion of the developing roller shaft  32  cannot rotate relative to the developing roller gear. When the developing roller gear rotates, the developing roller shaft  32  rotates so as to rotate the developing roller body  31  together with the developing roller shaft  32 . 
     It is noted that the developing roller shaft  32  may not penetrate the developing roller body  31  in the first direction. For example, the developing roller  30  may include a pair of developing roller shafts  32  each extending in the first direction from each end portion of the developing roller body  31 . 
     Further, the developing cartridge  1  includes a supply roller, not illustrated. The supply roller is positioned between the developing roller  30  and the accommodating chamber  13 . The supply roller is rotatable about a rotating axis extending in the first direction. When the developing cartridge  1  receives drive force, the developing agent is supplied to the outer peripheral surface of the developing roller  30  through the supply roller from the accommodating chamber  13  of the casing  11 . Simultaneously, the developing agent is electrically charged by the triboelectric charging between the supply roller and the developing roller  30 . Meanwhile, the developing roller shaft  32  of the developing roller  30  is electrically biased. Accordingly, the developing agent is attracted to the outer peripheral surface of the developing roller body  31  by the electrostatic force exerted between the developing roller shaft  32  and the developing agent. 
     The developing cartridge  1  further includes a thickness-regulating blade, not illustrated. The thickness-regulating blade regulates the thickness of the developing agent supplied on the outer peripheral surface of the developing roller body  31  to a constant thickness. Subsequently, the developing agent is supplied to a photosensitive drum  72  in the drum cartridge  2 , which will be described later, from the outer peripheral surface of the developing roller body  31 . The developing agent moves from the developing roller body  31  to the photosensitive drum  72  on the basis of the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum  72 . Accordingly, the electrostatic latent image is converted into a visible image on the outer peripheral surface of the photosensitive drum  72 . 
     The gear portion  40  is positioned at a first end face  12 , which is one end face in the first direction of the casing  11 . The gear portion  40  includes a coupling  41 , a gear cover  45 , and a plurality of gears including the agitator gear and the developing roller gear described above. The gear cover  45  is fixed to the first end face  12  of the casing  11  by screws, for example. At least part of the plurality of gears is positioned between the first end face  12  and the gear cover  45 . The coupling  41  is exposed from the gear cover  45 . The image forming apparatus  100  has a driving shaft, and in a state where the process cartridge  10  is attached to the image forming apparatus  100 , the driving shaft of the image forming apparatus  100  is connected to the coupling  41 . The rotation of the driving shaft is transmitted via the coupling  41  to the plurality of gears, including the agitator gear and the developing roller gear. 
     The developing cartridge  1  further includes holder cover  47 . The holder cover  47  is fixed to the gear cover  45 . The holder cover  47  is positioned opposite to the casing  11  with respect to the gear cover  45  in the first direction. 
     The plurality of gears of the gear portion  40  may be gears transmitting rotating force by engagements of teeth. Alternatively, the plurality of gears may be gears transmitting rotating force by friction between the gears. 
     The IC chip assembly  50  includes an IC chip  51  that is a storage medium and a holder  52  that supports the IC chip  51 . The IC chip  51  includes four electric contact surfaces  511 . The electric contact surface  511  is made from metal having electric conductivity. Further, the IC chip  51  can store various types of information about the developing cartridge  1 . It is noted that the number of the electric contact surface  511  of the IC chip  51  may be from one to three, or more than four. 
     The holder  52  has a first outer surface  52 A and a second outer surface  52 B. The first outer surface  52 A is positioned at one end portion in the third direction of the holder  52 . The second outer surface  52 B is positioned at the other end portion in the third direction of the holder  52 . The first outer surface  52 A is movable in the third direction relative to the second outer surface  52 B. 
     Specifically, the holder  52  includes a first holder member  521 , a second holder member  522 , and a coil spring  523  positioned between the first holder member  521  and the second holder member  522 . The first holder member  521  is made from resin, for example. The first holder member  521  has the first outer surface  52 A. The IC chip  51  is fixed to a supporting surface  520  of the first outer surface  52 A. The second holder member  522  has the second outer surface  52 B. In the assembled state of the holder  52 , the first outer surface  52 A and the second outer surface  52 B are separated from each other in the third direction. 
     The coil spring  523  is a resilient member configured to be compressed and expanded in the third direction. The coil spring  523  is positioned between the first outer surface  52 A and the second outer surface  52 B in the third direction. The coil spring  523  may be directly connected to the first outer surface  52 A and the second outer surface  52 B, or may be indirectly connected to the first outer surface  52 A and the second outer surface  52 B through a connecting member. The length of the coil spring  523  in the third direction changes at least between a first length and a second length longer than the first length. In the embodiment, the length of the coil spring  523  in the third direction changes between the first length, the second length, a third length, and a fourth length, where the third length is longer than the second length and the fourth length is longer than the third length. The distance between the first outer surface  52 A and the second outer surface  52 B in the third direction in a state where the coil spring  523  has the second length is longer than the distance between the first outer surface  52 A and the second outer surface  52 B in the third direction in a state where the coil spring  523  has the first length. The first length is shorter than the natural length of the coil spring  523 . 
     The second holder member  522  includes a spring holder  522 A having a cylindrical shape. The spring holder  522 A protrudes from the main body of the second holder member  522  in the third direction. The coil spring  523  is inserted in the spring holder  522 A. Inside of the spring holder  522 A, a protrusion having a cylindrical shape, not illustrated, is positioned. The protrusion is inserted radially inside of the coil spring  523 . Accordingly, the coil spring  523  is supported by both of the outer peripheral surface of the protrusion and the inner peripheral surface of the spring holder  522 A. 
     The second holder member  522  includes a first claw portion  522 B and a second claw portion  522 C. Each of the first claw portion  522 B and the second claw portion  522 C protrudes in a direction crossing the third direction. On the other hand, the first holder member  521  includes a first opening  521 A. The first claw portion  522 B is inserted in the first opening  521 A. The first holder member  521  also has a second opening, not illustrated, into which the second claw portion  522 C is inserted. 
     In a state where the coil spring  523  has the fourth length, the first claw portion  522 B contacts with the first holder member  521  at the edge of the first opening  521 A adjacent to the second outer surface  52 B. In a state where the coil spring  523  has the fourth length, the second claw portion  522 C contacts with the first holder member  521  at the edge of the second opening adjacent to the second outer surface  52 B. Accordingly, the length of the coil spring  523  in the third direction is prevented from being longer than the fourth length. Further, the first holder member  521  is prevented from being detached from the second holder member  522 . On the other hand, in a state where the coil spring  523  is the first, second and third lengths, the first claw portion  522 B and the second claw portion  522 C are separated from the first holder member  521 . 
     The IC chip  51  is fixed to the supporting surface  520  of the first outer surface  52 A of the first holder member  521 . That is, in a state where the first holder member  521  moves relative to the second holder member  522  in the third direction, the electric contact surface  511  moves in the third direction. It is noted that the IC chip  51  is fixed to a portion recessed from the first outer surface  52 A toward the second holder member  522  in the third direction. 
     The first holder member  521  includes a boss  53 A, a boss  53 B, and a boss  53 C. Each of the boss  53 A and the boss  53 B extends toward the gear cover  45  from a surface of the first holder member  521  in the first direction. The surface of the holder member  521  faces the gear cover  45 . The gear cover  45  has a through-hole  45 A and a through-hole  45 B. Each of the through-hole  45 A and the through-hole  45 B penetrates the gear cover  45  in the first direction. The boss  53 A is inserted in the through-hole  45 A. The boss  53 B is inserted in the through-hole  45 B. 
     The boss  53 C extends toward the holder cover  47  from another surface of the first holder member  521  in the first direction. Another surface of the first holder member  521  faces the holder cover  47 . On the other hand, the holder cover  47  has a through-hole  47 A. The through-hole  47 A penetrates the holder cover  47  in the first direction. The boss  53 C is inserted in the through-hole  47 A. 
     The length (internal dimension) of the through-hole  47 A in the second direction is greater than the length (external dimension) of the boss  53 C in the second direction. The length (internal dimension) of the through-hole  45 A in the second direction is greater than the length (external dimension) of the boss  53 A in the second direction. Further, the length (internal dimension) of the through-hole  45 B in the second direction is greater than the length (external dimension) of the boss  53 B in the second direction. Accordingly, the holder  52  is movable together with the boss  53 A, the boss  53 B, and the boss  53 C in the second direction relative to the gear cover  45  and the holder cover  47 . When the holder  52  moves in the second direction, the IC chip  51  having the electric contact surface  511  moves together with the holder  52  in the second direction. 
     The length (internal dimension) of the through-hole  47 A in the third direction is greater than the length (external dimension) of the boss  53 C in the third direction. The length (internal dimension) of the through-hole  45 A in the third direction is greater than the length (external dimension) of the boss  53 A in the third direction. Further, the length (internal dimension) of the through-hole  45 B in the third direction is greater than the length (external dimension) of the boss  53 B in the third direction. Accordingly, the holder  52  is movable together with the boss  53 A, the boss  53 B, and the boss  53 C in the third direction relative to the gear cover  45  and the holder cover  47 . When the holder  52  moves in the third direction, the IC chip  51  having the electric contact surface  511  moves together with the holder  52  in the third direction. 
     It is noted that the gear cover  45  may have, in lieu of the through-hole  45 A, a recessed portion to which the boss  53 A can be inserted. The gear cover  45  may have, in lieu of the through-hole  45 B, a recessed portion to which the boss  53 B can be inserted. The gear cover  45  may have, in lieu of the gear cover  45 C, a recessed portion to which the boss  53 C can be inserted. Further, the gear cover  45  may have a boss and the first holder member  521  may have a through hole or recessed portion to which the boss can be inserted. The holder cover  47  may have a boss and the first holder member  521  may have a through hole or recessed portion to which the boss can be inserted. 
     That is, one of the holder  52  and the housing that is configured of the casing  11 , the gear cover  45 , and the holder cover  47  may have a boss, and the other one of the holder  52  and the housing may have a through-hole or recessed portion to which the boss is inserted. 
     &lt;2.2 Drum Cartridge&gt; 
       FIG. 4  is a perspective view of the drum cartridge  2 . The drum cartridge  2  has a developing cartridge supporting portion  71  that can support the developing cartridge  1 . A photosensitive drum  72  is positioned at the developing cartridge supporting portion  71 . The photosensitive drum  72  is rotatable about a rotating axis (second rotating axis) extending in the first direction. In a state where the developing cartridge  1  is attached to the drum cartridge  2 , the developing roller  30  of the developing cartridge  1  contacts with the photosensitive drum  72 . The drum cartridge  2  to which the developing cartridge  1  is attached is attached to the drum cartridge holder  90  (see,  FIG. 1 ) of the image forming apparatus  100 . 
     A supporting plate  731  is positioned at the developing cartridge supporting portion  71 A that is one end surface of the developing cartridge supporting portion  71  in the first direction. In a state where the developing cartridge  1  is attached to the drum cartridge  2 , the supporting plate  731  is at a position where the second outer surface  52 B of the holder  52  faces the supporting plate  731  in the third direction. The supporting plate  731  has a surface extending in each of the first and second directions, and a protruding portion  73  is positioned at the surface. The protruding portion  73  protrudes toward the holder  52  from the surface of the supporting plate  731  in the third direction. The protruding portion  73  has a substantially square pyramid shape gradually converging toward the holder  52  in the third direction. 
     On the other hand, the second holder member  522  of the IC chip assembly  50  has a recess  522 D in the second outer surface  52 B (see,  FIGS. 8-12 ). The recess  522 D forms a substantially square pyramid shape gradually converging toward the first holder member  521  from the second outer surface  52 B in the third direction. In a state where the developing cartridge  1  is attached to the drum cartridge  2 , the protruding portion  73  of the drum cartridge  2  is fitted in the recess  522 D of the second holder member  522 . Accordingly, the second outer surface  52 B of the second holder member  522  and the supporting plate  731  are in contact with each other. That is, the supporting plate  731  and the protruding portion  73  serve as a holder supporting portion that supports the holder  52  of the IC chip assembly  50 . 
     Incidentally, the length of the recess  522 D in the second direction is longer than the length of the protruding portion  73  in the second direction. Accordingly, even in a state where the developing cartridge  1  is attached to the drum cartridge  2 , the second outer surface  52 B of the holder  52  is movable relative to the supporting plate  731  and the protruding portion  73  in the second direction. Accordingly, the holder  52  can be rotated during the detaching operation of the process cartridge  10 , described later. 
     &lt;3. Drum Cartridge Holder&gt; 
     The drum cartridge holder  90  of the image forming apparatus  100  has four slots  91 .  FIG. 5  illustrates a cross-section of the drum cartridge holder  90  taken adjacent to one of the slots  91 .  FIG. 6  is a cross-sectional view of the first guide surface  92  and the second guide surface  93 .  FIG. 7  is a plan view of the first guide surface  92  and the second guide surface  93 . 
     The drum cartridge holder  90  has a first guide surface  92  and a second guide surface  93 . The slot  91  has an inserting opening into which the process cartridge  10  is inserted, and the first guide surface  92  and the second guide surface  93  are positioned in the inserting opening. The first guide surface  92  and the second guide surface  93  face each other in the third direction. The first guide surface  92  is positioned spaced apart from the second guide surface  93  in the third direction. In a state where the process cartridge  10  is inserted in the slot  91 , the IC chip assembly  50  is inserted between the first guide surface  92  and the second guide surface  93 . 
     The first guide surface  92  is a portion that contacts at least part of the first outer surface  52 A of the holder  52 . The first guide surface  92  is configured to guide the first outer surface  52 A during detachment or attachment of the process cartridge  10  with respect to the drum cartridge holder  90 . The first guide surface  92  supports the electric connector  81  that is made from metal and is configured to contact with the electric contact surface  511  of the IC chip  51 . The electric connector  81  is an electric contact protruding toward the second guide surface  93  from the surface of the first guide surface  92  in the third direction. The first guide surface  92  has a first protruding portion  921  and a second protruding portion  922  that are arrayed in the second direction. The electric connector  81  is positioned between the first protruding portion  921  and the second protruding portion  922  in the second direction. The first protruding portion  921  is positioned closer to the inserting opening in the second direction than the electric connector  81  is to the inserting opening. Each of the first protruding portion  921  and the second protruding portion  922  protrudes further toward the second guide surface  93  than the electric connector  81  protrudes in the third direction. 
     The second guide surface  93  is a member that contacts with at least part of the supporting plate  731 . The second guide surface  93  is configured to guide the supporting plate  731  during detachment or attachment of the process cartridge  10  with respect to the drum cartridge holder  90 . The second guide surface  93  has a first guide plate  931  and a second guide plate  932 . The first guide plate  931  is inclined with respect to the second direction so that the first guide plate  931  is inclined toward the first guide surface  92  in the inserting direction of the process cartridge  10  from the inserting opening. The first guide plate  931  guides the supporting plate  731  in a direction in which the supporting plate  731  approaches to the electric connector  81  during attachment of the process cartridge  10  with respect to the drum cartridge holder  90 . The second guide plate  932  is positioned along the second direction. The second guide plate  932  guides the supporting plate  731  in the inserting direction that is positioned closer to the electric connector  81  by the first guide plate  931 . 
     As illustrated by dashed lines in  FIG. 5 , the image forming apparatus  100  includes a transfer belt  82  and transfer rollers  83  each of which is positioned in each of the slots  91 . The transfer belt  82  is positioned at an end portion opposite to the inserting opening of each slot  91 . The transfer roller  83  is positioned at the end portion opposite to the inserting opening of each slot  91 . The transfer roller  83  is positioned opposite to the photosensitive drum  72  with respect to the transfer belt  82 . In a state where the process cartridge  10  is attached to the slot  91 , the outer peripheral surface of the photosensitive drum  72  and the transfer belt  82  contact with each other. Printing sheets pass between the photosensitive drum  72  and the transfer belt  82 . The transfer bias is exerted on the transfer roller  83 . Accordingly, the developing agent adhering to the outer peripheral surface of the photosensitive drum  72  is transferred to the printing sheet. 
     As illustrated in  FIG. 7 , the first guide surface  92  has a first surface  923  and a second surface  924 . The first surface  923  is positioned at one side of the electric contact surface  511  in the first direction. The first surface  923  is an inclined surface inclined such that the first surface  923  is closer to the second guide surface  93  as being farther from the electric contact surface  511 . The second surface  924  is positioned at the other side of the electric contact surface  511  in the electric contact surface  511 . The second surface  924  is an inclined surface inclined such that the second surface  924  is closer to the second guide surface  93  as being farther from the electric contact surface  511 . 
     The first outer surface  52 A of the holder  52  contacts with the first surface  923  or the second surface  924  during attachment of the process cartridge  10  with respect to the drum cartridge holder  90 . Accordingly, the holder  52  is guided by the first surface  923  or the second surface  924  so as to be inserted in the drum cartridge holder  90 . As a result, the holder  52  is fixed in position in the first direction. Accordingly, the electric contact surface  511  can firmly contact with the electric connector  81 . Further, the holder  52  is accurately positioned in the first direction and thus a movement of the holder  52  is smooth during detachment of the process cartridge  10  from the drum cartridge holder  90 . 
     &lt;4. Detaching Process of Process Cartridge&gt; 
       FIGS. 8, 9, and 11  illustrate the detaching process of the process cartridge  10  in which the process cartridge  10  is detached from the drum cartridge holder  90 .  FIG. 10  is an enlarged view of  FIG. 9  illustrating the holder  52  and an adjacent area of the holder  52 .  FIG. 12  is an enlarged view of  FIG. 11  illustrating the holder  52  and an adjacent area of the holder  52 . 
       FIG. 8  illustrates the process cartridge  10  before being detached from the drum cartridge holder  90 . Before the process cartridge  10  is detached from the drum cartridge holder  90 , the photosensitive drum  72  is in contact with the transfer belt  82 . In that state, the position of the holder  52  with respect to the drum cartridge holder  90  is defined as the first position. In a state where the holder  52  is positioned at the first position, the holder  52  is interposed by the first guide surface  92  and the second guide surface  93  in the third direction, and the electric contact surface  511  of the IC chip  51  contacts with the electric connector  81 . Further, in a state where the holder  52  is positioned at the first position, the length of the coil spring  523  in the third direction is the first length. 
     As illustrated in  FIG. 9 , during detachment of the process cartridge  10  from the drum cartridge holder  90 , the drum cartridge  2  moves in a direction separating away from the transfer belt  82 . Accordingly, the photosensitive drum  72  separates from the transfer belt  82 , and the second outer surface  52 B of the holder  52  also moves in a direction separating from the transfer belt  82 . Meanwhile, the first outer surface  52 A of the holder  52  contacts with the first protruding portion  921  of the first guide surface  92 . Accordingly, a movement of the first outer surface  52 A in the second direction is restricted. 
     As illustrated in  FIG. 10 , the first protruding portion  921  has a first contact surface  921 A. In a state where the process cartridge  10  is attached to the drum cartridge holder  90 , the first contact surface  921 A and the developing roller  30  are positioned opposite to each other with respect to the electric connector  81  in the second direction. Further, the first contact surface  921 A is positioned between the first surface  923  and the second surface  924  in the first direction. On the other hand, the first outer surface  52 A of the holder  52  has a second contact surface  52 C. The second contact surface  52 C is positioned opposite to the developing roller  30  with respect to the electric contact surface  511  in the second direction. 
     The second contact surface  52 C contacts with the first contact surface  921 A. Accordingly, the holder  52  pivots about the contacting portion of the first protruding portion  921  and the first outer surface  52 A. That is, in a state where the second contact surface  52 C contacts with the first contact surface  921 A, the holder  52  pivots about the second contact surface  52 C. As a result, the position of the holder  52  with respect to the drum cartridge holder  90  moves from the first position to the second position. Here, the first position is illustrated in  FIG. 8  and the second position is illustrated in  FIGS. 9 and 10 . 
     The electric connector  81  is configured to be compressed and expanded with respect to the first guide surface  92  in the third direction. In a state where the holder  52  is at the second position, the electric connector  81  protrudes further toward the electric contact surface  511  than in a state where the holder  52  is at the first position. Accordingly, the electric contact surface  511  contacts with the electric connector  81  in a state where the holder  52  is positioned at the second position. Further, the length of the coil spring  523  in the third direction is the second length that is longer than the first length in a state where the holder  52  is positioned at the second position. 
     Accordingly, in a state where the holder  52  moves to the second position from the first position, a movement of the first outer surface  52 A in the second direction is restricted by the first protruding portion  921 . Accordingly, a movement of the electric contact surface  511  in the second direction relative to the electric connector  81  is restricted. As a result, rubbing of the electric contact surface  511  against the electric connector  81  is suppressed. The pressing force exerted on the electric connector  81  by the electric contact surface  511  is gradually reduced since the coil spring  523  is expanded from the first length to the second length. 
     As explained above, the holder  52  can move in the second and third directions relative to the casing  11 , the gear cover  45 , and the holder cover  47 . In other words, the holder  52  has at least two degrees of freedom where the holder  52  can move in the second and third directions. Accordingly, the holder  52  can easily pivot in a state where the holder  52  moves from the first position to the second position. 
     Subsequently, the holder  52  moves from the second position to the third position. Here, the second position is illustrated in  FIGS. 9 and 10  and the third position is illustrated in  FIGS. 11 and 12 . Accordingly, the electric contact surface  511  separates from the electric connector  81 . The distance between the photosensitive drum  72  and the transfer belt  82  in a state where the holder  52  is positioned at the third position is longer than the distance in a state where the holder  52  is positioned at the second position. Further, in a state where the holder is positioned at the third position, the length of the coil spring  523  in the third direction is the third length that is longer than the second length. 
     As illustrated in  FIG. 12 , the second contact surface  52 C is an inclined surface inclined with respect to the second and third directions. In a state where the holder  52  moves from the second position to the third position, the second contact surface  52 C moves along the first contact surface  921 A in a state where the second contact surface  52 C contacts with the first contact surface  921 A. Accordingly, the holder  52  can be moved smoothly relative to the first guide surface  92 . As a result, the electric contact surface  511  can be separated from the electric connector  81  and rubbing of the electric contact surface  511  against the electric connector  81  is suppressed. 
     Subsequently, in a state where the process cartridge  10  is completely detached from the drum cartridge supporting portion  90 , the first outer surface  52 A of the holder  52  separates from the first guide surface  92 . Further, the supporting plate  731  of the drum cartridge  2  separates from the second guide surface  93 . Accordingly, the length of the coil spring  523  in the third direction becomes the fourth length that is longer than the third length. 
     &lt;5. Modification&gt; 
     The embodiment of the disclosure is explained above, and the disclosure is not limited to the above embodiment. 
     In the embodiment, the coil spring  523  is used as a resilient member. Alternatively, a leaf spring, torsion spring or other springs may be used instead of the coil spring  523 . 
     In the embodiment, the IC chip having the electric contact surface is fixed to the outer surface of the holder. Alternatively, only the electric contact surface contacting the electric connector may be fixed to the outer surface of the holder, and the portion of the IC chip other than the electric contact surface may be positioned at other parts of the developing cartridge. 
     Further, the details of parts or members configuring the image forming apparatus may be different from the shapes illustrated in each figure of the disclosure. Further, each component in the embodiment or the modification may be suitably combined, if not inconsistent with each other.