Patent Publication Number: US-11385591-B2

Title: Developing cartridge including holder movably supporting electrical contact surface

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a Continuation of U.S. patent application Ser. No. 17/028,189, filed Sep. 22, 2020, which is a Continuation of U.S. patent application Ser. No. 16/737,395, filed Jan. 8, 2020, which is a Continuation of U.S. patent application Ser. No. 16/225,706, filed Dec. 19, 2018, which claims priority from Japanese Patent Application No. 2018-030236 filed Feb. 23, 2018 and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the disclosed applications. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a developing cartridge. 
     BACKGROUND 
     Conventionally, electrophotographic image-forming apparatuses such as laser printers and LED printers are well-known. Such image-forming apparatuses include developing cartridges. Each developing cartridge includes a developing roller for supplying a developing agent. 
     According to the conventional image-forming apparatus, a developing cartridge is attachable to a corresponding drum cartridge including a photosensitive drum. When the developing cartridge is attached to the corresponding drum cartridge, a developing roller of the developing cartridge comes into contact with the photosensitive drum. The drum cartridge having the developing cartridge attached thereto is then attached to the image-forming apparatus. 
     SUMMARY 
     There are also known developing cartridges each including a memory and an electrical contact surface. The memory may be an integrated circuit (IC) chip, for example. When a drum cartridge to which such a developing cartridge is attached is attached to an image-forming apparatus, the electrical contact surface is in contact with an electrical terminal provided in the image-forming apparatus. However, the electrical contact surface may be rubbed against a part of the image-forming apparatus during attachment and detachment of the drum cartridge (including the developing cartridge) relative to the image-forming apparatus. 
     In view of the foregoing, it is an object of the present disclosure to provide a developing cartridge capable of reducing rubbing of an electrical contact surface. 
     In order to attain the above and other objects, according to one aspect, the present disclosure provides a developing cartridge including a housing, a developing roller, a memory, a holder, and a relay component. The housing is configured to accommodate developing agent therein and extends in a first direction. The developing roller is rotatable about a first axis extending in the first direction. The developing roller is positioned at one end portion of the housing in a second direction. The memory is held at the housing. The holder holds an electrical contact surface. The holder is movable relative to the housing in at least one of the second direction and a third direction crossing the first direction and the second direction, the third direction crossing the electrical contact surface. The relay component electrically connects the memory to the electrical contact surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a conceptual diagram of an image-forming apparatus to which a developing cartridge according to an embodiment is attachable; 
         FIG. 2  is a perspective view of a process cartridge including the developing cartridge according to the embodiment and a drum cartridge; 
         FIG. 3  is a perspective view of the developing cartridge according to the embodiment; 
         FIG. 4  is a perspective view of the developing cartridge according to the embodiment without a gear cover, a holder cover, and a memory cover; 
         FIG. 5  is an exploded perspective view of a holder of the developing cartridge according to the embodiment; 
         FIG. 6  is a cross-sectional view of the holder of the developing cartridge according to the embodiment taken along a plane orthogonal to a first direction, wherein a coil spring of the holder is in a first state; 
         FIG. 7  is a cross-sectional view of the holder of the developing cartridge according to the embodiment taken along the plane orthogonal to the first direction, wherein the coil spring of the holder is in a second state; 
         FIG. 8  is a perspective view of the drum cartridge to which the developing cartridge according to the embodiment is attachable; 
         FIG. 9  is a perspective view of a developing cartridge according to a first modification to the embodiment; 
         FIG. 10  is a perspective view of a developing cartridge according to a second modification to the embodiment; 
         FIG. 11  is a perspective view of a developing cartridge according to a third modification to the embodiment; and 
         FIG. 12  is a perspective view of a developing cartridge according to a fourth modification to the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, one embodiment of the disclosure will be described while referring to  FIGS. 1 through 8 . 
     In the following description, referring to  FIG. 2 , the term “first direction” refers to a direction in which a casing  10  of a developing cartridge  1  of the embodiment extends in a state where a process cartridge  3  is attached to an image-forming apparatus  100 . The term “second direction” refers to a direction in which an agitator  20  and a developing roller  30  of the developing cartridge  1  are arranged. The term “third direction” refers to a direction crossing electrical contact surfaces  71  of the developing cartridge  1 . The first direction and the second direction cross each other (preferably, orthogonal to each other). The second direction and the third direction cross each other (preferably, orthogonal to each other). The third direction and the first direction cross each other (preferably, orthogonal to each other). 
     1. Configuration of Image-Forming Apparatus 
       FIG. 1  is a conceptual diagram of the image-forming apparatus  100 . The image-forming apparatus  100  according to the embodiment is an electrophotographic-type printer. For example, the image-forming apparatus  100  may be a laser printer or an LED printer. 
     The image-forming apparatus  100  includes four process cartridges  3 . Each of the four process cartridges  3  includes a developing cartridge  1  and a drum cartridge  2 . Each developing cartridge  1  is attachable to a corresponding one of the drum cartridges  2 . The four developing cartridges  1  store respective developing agents of different colors such as cyan, magenta, yellow, and black. 
     The image-forming apparatus  100  includes four cartridge holders  110 . Each of the process cartridges  3  is attachable to and detachable from a corresponding one of the cartridge holders  110 . The image-forming apparatus  100  is configured to form images on recording surfaces of sheets using the developing agents, such as toner, supplied from the developing cartridges  1 . The number of the process cartridges  3  attachable to the image-forming apparatus  100  may be one, two or three, or may be five or more. 
     Each of the four developing cartridges  1  includes a memory  51 . The memory  51  is a storage medium capable of reading and writing information. The image-forming apparatus  100  also includes a controller  120 . When the process cartridges  3  are attached to the corresponding cartridge holders  110 , the memory  51  of each developing cartridge  1  is electrically connected to the controller  120 . The controller  120  may be a circuit board, for example. The controller  120  includes a processor such as a central processing unit (CPU), and various memories. The controller  120  is configured to execute various processes for the image-forming apparatus  100  as the processor operates according to programs stored in the memories. 
     2. Process Cartridge 
       FIG. 2  is a perspective view of the process cartridge  3 . As described above, the process cartridge  3  includes the developing cartridge  1  and the drum cartridge  2 . The developing cartridge  1  is attachable to and detachable from the drum cartridge  2 . 
     2-1. Developing Cartridge 
       FIG. 3  is a perspective view of the developing cartridge  1 .  FIG. 4  is a perspective view of the developing cartridge  1  without a gear cover  42 , a holder  60 , a holder cover  64 , and a memory cover  81  (described later). As illustrated in  FIGS. 3 and 4 , the developing cartridge  1  includes the casing  10 , the agitator  20 , the developing roller  30 , a gear unit  40 , a main board  50 , the holder  60 , the electrical contact surfaces  71 , and a harness  80 . 
     The casing  10  is configured to store a developing agent. The casing  10  extends in the first direction. The casing  10  has a first outer surface  11  and a second outer surface  12  spaced away from each other in the first direction. The casing  10  extends in the first direction between the first outer surface  11  and the second outer surface  12 . That is, the first outer surface  11  is at one end portion of the casing  10  in the first direction, while the second outer surface  12  is at another end portion of the casing  10  in the first direction. The gear unit  40  and the holder  60  are positioned at the first outer surface  11 . A storage chamber  13  is defined inside the casing  10  for storing the developing agent therein. 
     The casing  10  has an opening  14 . The opening  14  is positioned at one end portion of the casing  10  in the second direction. The opening  14  provides communication between the storage chamber  13  and the outside of the casing  10 . The casing  10  also includes a handle  15 . The handle  15  is positioned on an outer surface of another end portion of the casing  10  in the second direction. 
     The agitator  20  includes an agitator shaft  21  and a blade  22 . The agitator shaft  21  extends in the first direction and defines a rotation axis X 2  (second axis) extending in the first direction. The blade  22  extends from the agitator shaft  21  toward an inner surface of the casing  10 . The blade  22  and part of the agitator shaft  21  are positioned within the storage chamber  13  of the casing  10 . One end portion of the agitator shaft  21  in the first direction is fixed to an agitator gear belonging to the gear unit  40 . The agitator shaft  21  is incapable of rotating relative to the agitator gear. In accordance with rotation of the agitator gear, the agitator shaft  21  and the blade  22  are rotatable about the rotation axis X 2  (second axis) extending in the first direction. The rotation of the blade  22  can agitate the developing agent stored in the storage chamber  13 . 
     The developing roller  30  is positioned at the opening  14  of the casing  10 . That is, the developing roller  30  is positioned at the one end portion of the casing  10  in the second direction. The developing roller  30  is rotatable about a rotation axis X 1  (first axis) extending in the first direction. The developing roller  30  according to this embodiment includes a roller body  31  and a roller shaft  32 . The roller body  31  is a hollow-cylindrical member extending in the first direction. The roller body  31  is made from an elastic rubber, for example. The roller shaft  32  is a solid-cylindrical member penetrating the roller body  31  in the first direction. The roller shaft  32  is made from metal or electrically conductive resin. 
     The roller body  31  is fixed to the roller shaft  32  so as not to rotate relative to the roller shaft  32 . One end portion of the roller shaft  32  in the first direction is fixed to a developing-roller gear belonging to the gear unit  40 . The roller shaft  32  is thus incapable of rotating relative to the developing-roller gear. As the developing-roller gear rotates, the roller shaft  32  also rotates, causing the roller body  31  to rotate together with the roller shaft  32 . 
     Note that the roller shaft  32  does not necessarily penetrate through the roller body  31  in the first direction. For example, the roller shaft  32  may be configured as a pair of roller shafts extending in the first direction. In this case, one of the roller shafts may be provided at one end of the roller body  31  in the first direction, while the other roller shaft may be provided at another end of the roller body  31  in the first direction. 
     The developing cartridge  1  also includes a supply roller (not illustrated). The supply roller is positioned between the developing roller  30  and the storage chamber  13 . The supply roller is rotatable about a rotation axis extending in the first direction. Upon receipt of a driving force into the developing cartridge  1 , the developing agent in the storage chamber  13  is supplied therefrom to an outer peripheral surface of the developing roller  30  through the supply roller. While being supplied from the supply roller to the developing roller  30 , the developing agent is triboelectrically charged between the supply roller and the developing roller  30 . Since a bias voltage is applied to the roller shaft  32  of the developing roller  30 , the developing agent is attracted to an outer peripheral surface of the roller body  31  by an electrostatic force between the roller shaft  32  and the developing agent. 
     The developing cartridge  1  also includes a thickness-regulating blade  33 . The thickness-regulating blade  33  is configured to level the developing agent supplied onto the outer peripheral surface of the roller body  31  into a uniform thickness. The developing agent on the outer peripheral surface of the roller body  31  is then supplied to a corresponding photosensitive drum  92  (described later) of the drum cartridge  2 . At this time, the developing agent moves from the roller body  31  to the photosensitive drum  92  based on an electrostatic latent image formed on an outer peripheral surface of the photosensitive drum  92 . The electrostatic latent image is thus developed into a visible toner image on the outer peripheral surface of the photosensitive drum  92 . 
     The gear unit  40  is positioned at the first outer surface  11  of the casing  10 . The gear unit  40  includes: a plurality of gears including the agitator gear and the developing-roller gear described above; a coupling  41 ; and the gear cover  42 . Together with the casing  10 , the gear cover  42  constitutes a housing of the developing cartridge  1 . The gear cover  42  is fixed to the first outer surface  11  of the casing  10  with screws, for example. At least part of the plurality of gears is positioned between the first outer surface  11  and the gear cover  42 . That is, at least part of the plurality of gears is covered by the gear cover  42 . The coupling  41  is exposed to the outside of the gear cover  42 . When the process cartridge  3  is attached to the image-forming apparatus  100 , a drive shaft of the image-forming apparatus  100  is connected to the coupling  41 . Hence, as the drive shaft rotates, the rotation of the drive shaft is transmitted, through the coupling  41 , to the plurality of gears including the agitator gear and developing-roller gear. 
     The plurality of gears of the gear unit  40  may transmit torque by meshing engagement between gear teeth or by frictional force between neighboring gears. 
     The main board  50  is a circuit board held by the casing  10 . The main board  50  includes the memory  51 . The memory  51  is a storage medium capable of storing various information on the developing cartridge  1 . For example, an IC chip may be employed as the memory  51 . In this embodiment, the main board  50  is positioned on the outer surface of the other end of the casing  10  in the second direction. Specifically, the main board  50  is positioned between the handle  15  and the one end portion of the casing  10  in the first direction (i.e., the first outer surface  11 ). The main board  50  is fixed to the outer surface of the casing  10  with an adhesive, for example. 
     The holder  60  is positioned at the one end portion of the casing  10  in the first direction.  FIG. 5  is an exploded perspective view of the holder  60 .  FIGS. 6 and 7  are cross-sectional views of the holder  60  taken along a plane perpendicular to the first direction. As illustrated in  FIGS. 5 to 7 , the holder  60  includes a first holder member  61 , a second holder member  62 , and a coil spring  63 . 
     The first holder member  61  includes a first-holder outer surface  610 . The second holder member  62  includes a second-holder outer surface  620 . In an assembled state of the holder  60 , the first-holder outer surface  610  and the second-holder outer surface  620  are spaced away from each other in the third direction. The first-holder outer surface  610  (first end) is located at one end portion of the holder  60  in the third direction. The second-holder outer surface  620  (second end) is located at another end portion of the holder  60  in the third direction. 
     The coil spring  63  is a resilient member configured to expand and contract in the third direction. The coil spring  63  connects the first holder member  61  to the second holder member  62 . The coil spring  63  is positioned between the first-holder outer surface  610  and the second-holder outer surface  620  in the third direction. The coil spring  63  may be connected to each of the first-holder outer surface  610  and the second-holder outer surface  620  either directly or indirectly through other members. The coil spring  63  is configured to expand and contract in the third direction between a first state (illustrated in  FIG. 6 ) and a second state (illustrated in  FIG. 7 ). 
     The coil spring  63  has a length in the third direction in the first state (hereinafter referred to as “first length”) that is longer than a length of the coil spring  63  in the third direction in the second state (hereinafter referred to as “second length”). A distance between the first-holder outer surface  610  and the second-holder outer surface  620  in the third direction when the coil spring  63  has the first length (in the first state) is greater than a distance between the first-holder outer surface  610  and the second-holder outer surface  620  in the third direction when the coil spring  63  has the second length (in the second state). At least, the second length is shorter than a natural length of the coil spring  63 . 
     The first holder member  61  includes a protrusion  615 . The protrusion  615  protrudes from an inner surface of the first holder member  61  facing the second holder member  62  in the third direction. The protrusion  615  protrudes toward the second holder member  62  (inward) in the third direction. 
     The second holder member  62  includes a spring holder  623  of a hollow-cylindrical shape. The spring holder  623  protrudes from an inner surface of the second holder member  62  facing the first holder member  61  in the third direction. The spring holder  623  protrudes toward the first holder member  61  (outward) in the third direction. The second holder member  62  also includes a columnar-shaped protrusion  625  positioned inside the spring holder  623 . Part of the coil spring  63  is inserted in the spring holder  623 . Specifically, one end portion of the coil spring  63  in the third direction is received by the protrusion  615 , while another end portion of the coil spring  63  in the third direction is received by the protrusion  625  within the spring holder  623 . With this structure, the first holder member  61  (first-holder outer surface  610 ) is movable relative to the second holder member  62  (second-holder outer surface  620 ) in the third direction. 
     The second holder member  62  includes a first claw  621  and a second claw  622 . The first claw  621  and the second claw  622  extend from the inner surface of the second holder member  62  toward the first holder member  61  in the third direction. Each of the first claw  621  and the second claw  622  has a distal end portion protruding in a direction crossing the third direction. Specifically, the distal end portion of the first claw  621  protrudes outward in the third direction, while the distal end portion of the second claw  622  protrudes inward in the third direction (toward the gear cover  42 ). The first holder member  61  includes a first opening  611  and a second opening (not illustrated). The distal end portion of the first claw  621  is inserted into the first opening  611 . The distal end portion of the second claw  622  is inserted into the non-illustrated second opening. 
     When the coil spring  63  is in the first state, the distal end portion of the first claw  621  is in contact with the first holder member  61  at an edge of the first opening  611  closest to the second-holder outer surface  620  in the third direction. Likewise, when the coil spring  63  is in the first state, the distal end portion of the second claw  622  is in contact with the first holder member  61  at an edge of the second opening closest to the second-holder outer surface  620  in the third direction. This contact between the second holder member  62  (first claw  621  and second claw  622 ) and the first holder member  61  (first opening  611  and second opening) prevents the coil spring  63  from expanding more than the first state in the third direction. Further, this structure prevents the first holder member  61  and the second holder member  62  from disengaging from each other. When the coil spring  63  is in the second state, the distal end portion of the first claw  621  is separated from the edge of the first opening  611  closest to the second-holder outer surface  620  in the third direction. Likewise, when the coil spring  63  is in the second state, the distal end portion of the second claw  622  is separated from the edge of the second opening closest to the second-holder outer surface  620  in the third direction. 
     Instead of the first opening  611 , a recess or a step may be provided in the first holder member  61  to contact the first claw  621 . Instead of the second opening, a recess or a step may be provided in the first holder member  61  to contact the second claw  622 . Alternatively, claws may be provided in the first holder member  61 , while openings, recesses, or steps may be provided in the second holder member  62 . 
     As illustrated in  FIG. 3 , the developing cartridge  1  also includes the holder cover  64 . The holder cover  64  is positioned at the one end portion of the casing  10  in the first direction. Specifically, the holder cover  64  is positioned opposite to the casing  10  with respect to the gear cover  42  in the first direction. The holder cover  64  is fixed to an outer end face of the gear cover  42  in the first direction. The holder cover  64  covers at least part of the holder  60 . 
     Specifically, with regard to the holder  60 , the first holder member  61  includes a first boss  612 , a second boss  613 , and a third boss  614 . The first boss  612  is provided on a surface of the first holder member  61  facing the holder cover  64  in the first direction. The first boss  612  extends toward the holder cover  64  in the first direction. The second boss  613  and the third boss  614  are provided on a surface of the first holder member  61  facing the gear cover  42  in the first direction. The second boss  613  and the third boss  614  extend toward the gear cover  42  in the first direction. 
     The holder cover  64  includes a first through-hole  641 . The first through-hole  641  penetrates through an outer end wall of the holder cover  64  in the first direction. The first boss  612  of the first holder member  61  is inserted into the first through-hole  641 . 
     The gear cover  42  includes a second through-hole and a third through-hole (both not illustrated). The second through-hole and the third through-hole penetrate through an outer end wall of the gear cover  42  in the first direction. The second boss  613  of the first holder member  61  is inserted into the second through-hole. The third boss  614  of the first holder member  61  is inserted into the third through-hole. 
     The first through-hole  641  has a dimension (internal dimension) D 2  in the second direction that is greater than a dimension (external dimension) D 1  of the first boss  612  in the second direction. The second through-hole has a dimension (internal dimension) in the second direction that is greater than a dimension (external dimension) of the second boss  613  in the second direction. The third through-hole has a dimension (internal dimension) in the second direction that is greater than a dimension (external dimension) of the third boss  614  in the second direction. With this structure, the holder  60  is movable relative to the gear cover  42  and the holder cover  64  in the second direction, together with the first boss  612 , the second boss  613  and the third boss  614 . As the holder  60  moves in the second direction, the electrical contact surfaces  71  (described later) also move together with the holder  60  in the second direction. 
     The first through-hole  641  has a dimension (internal dimension) in the third direction that is greater than a dimension (external dimension) of the first boss  612  in the third direction. The second through-hole has a dimension (internal dimension) in the third direction that is greater than a dimension (external dimension) of the second boss  613  in the third direction. The third through-hole has a dimension (internal dimension) in the third direction that is greater than a dimension (external dimension) of the third boss  614  in the third direction. With this structure, the holder  60  is movable relative to the gear cover  42  and the holder cover  64  in the third direction, together with the first boss  612 , the second boss  613  and the third boss  614 . As the holder  60  moves in the third direction, the electrical contact surfaces  71  (described later) also move together with the holder  60  in the third direction. 
     Incidentally, the holder cover  64  may include a first recess, instead of the first through-hole  641 , for receiving the first boss  612  in the first recess. The gear cover  42  may include a second recess, instead of the second through-hole, for receiving the second boss  613  in the second recess. The gear cover  42  may include a third recess, instead of the third through-hole, for receiving the third boss  614  in the third recess. Alternatively, the holder cover  64  may include a boss, while the first holder member  61  may include a through-hole or a recess in which the boss of the holder cover  64  is inserted. The gear cover  42  may include bosses, while the first holder member  61  may include through-holes or recesses in which the bosses are inserted. 
     That is, either one of the holder  60  and the housing (configured of the casing  10 , the gear cover  42  and the holder cover  64 ) may include bosses, while the other one of the holder  60  and the housing may include through-holes or recesses in which the bosses are inserted. 
     The electrical contact surfaces  71  are electrically-conductive surfaces held by the holder  60 . The electrical contact surfaces  71  are positioned at the first-holder outer surface  610  of the first holder member  61 . Specifically, the electrical contact surfaces  71  are positioned in a recess formed on the first-holder outer surface  610 . The electrical contact surfaces  71  are fixed to the first-holder outer surface  610  directly or indirectly through other member(s). As the holder  60  moves relative to the casing  10 , the electrical contact surfaces  71  also move together with the holder  60  relative to the casing  10 . As the first holder member  61  moves relative to the second holder member  62  in the third direction, the electrical contact surfaces  71  also move together with the first holder member  61  relative to the second holder member  62  in the third direction. 
     In the present embodiment, four of the electrical contact surfaces  71  are held by the first-holder outer surface  610 . Each of the electrical contact surfaces  71  is made from an electrically-conductive metal. The number of electrical contact surfaces  71  held by the holder  60  may be one, two, or three, or may be five or more. 
     The harness  80  is a flexible and deformable relay component including a plurality of electrically conductive wires. As illustrated in  FIG. 4 , the harness  80  has one end portion connected to the main board  50 . The harness  80  extends from the main board  50  in the first direction along the outer surface of the other end portion of the casing  10  in the second direction. The harness  80  extends inside the gear cover  42  and extends into the holder  60 , whereby another end portion of the harness  80  is connected to the respective electrical contact surfaces  71 . The memory  51  of the main board  50  is thus electrically connected to the electrical contact surfaces  71  through the electrically conductive wires included in the harness  80 . 
     The developing cartridge  1  according to the embodiment also includes the memory cover  81 . The memory cover  81  is fixed to the outer surface of the other end of the casing  10  in the second direction with, for example, screws or an adhesive. As illustrated in  FIGS. 3 and 4 , the main board  50  and at least part of the harness  80  are covered by the memory cover  81 . That is, the main board  50  and at least part of the harness  80  are mounted between the memory cover  81  and the outer surface of the other end of the casing  10  in the second direction. This structure can prevent the user from touching the main board  50  and the harness  80 . 
     As described above, in the developing cartridge  1 , the electrical contact surfaces  71  are held by the holder  60 , while the memory  51  of the main board  50  is not held by the holder  60  but by the casing  10 . The configuration of the embodiment can provide freedom in design of the holder  60  irrespective of the shape and size of the memory  51 , thereby contributing to easy downsizing of the holder  60 . 
     2-2. Drum Cartridge 
       FIG. 8  is a perspective view of the drum cartridge  2 . As illustrated in  FIG. 8 , the drum cartridge  2  includes a developing-cartridge holder  91  and the photosensitive drum  92 . The developing cartridge  1  is attachable to and detachable from the developing-cartridge holder  91 . The photosensitive drum  92  is rotatable about a rotation axis X 3  extending in the first direction. The photosensitive drum  92  is positioned at one end portion of the drum cartridge  2  in the second direction. In a state where the developing cartridge  1  is attached to the developing-cartridge holder  91 , the outer peripheral surface of the developing roller  30  is in contact with the outer peripheral surface of the photosensitive drum  92 . 
     The developing-cartridge holder  91  includes a holding plate  93 . The holding plate  93  is positioned at one end portion of the developing-cartridge holder  91  in the first direction. In a state where the developing cartridge  1  is attached to the drum cartridge  2 , the second-holder outer surface  620  of the holder  60  faces the holding plate  93  in the third direction. As illustrated in  FIG. 8 , the holding plate  93  includes a holding surface  931  and a protrusion  932 . The holding surface  931  extends in the first direction and the second direction. The protrusion  932  protrudes in the third direction from the holding surface  931  toward the holder  60  of the developing cartridge  1  attached to the developing-cartridge holder  91 . The protrusion  932  according to this embodiment has a substantially square pyramid shape that is tapered as extending away from the holding surface  931 . 
     As illustrated in  FIGS. 6 and 7 , the second holder member  62  includes a recess  624  formed in the second-holder outer surface  620 . The recess  624  has a substantially square pyramid shape that is tapered toward the first holder member  61 . When the developing cartridge  1  is attached to the drum cartridge  2 , the protrusion  932  of the holding plate  93  is fitted into the recess  624  of the second holder member  62 , and the holding plate  93  comes into contact with the second-holder outer surface  620 . The holder  60  is thus supported relative to the drum cartridge  2 . 
     The image-forming apparatus  100  includes a main-body terminal (not illustrated). The main-body terminal is made from electrically conductive metal. When the process cartridge  3  configured of the developing cartridge  1  and the drum cartridge  2  is attached to the image-forming apparatus  100 , the holder  60  is sandwiched between the main-body terminal and the holding plate  93 , and the electrical contact surfaces  71  are in contact with the main-body terminal. The controller  120  of the image-forming apparatus  100  is thus electrically connected to the memory  51  of the main board  50  through the main-body terminal, the electrical contact surfaces  71 , and the harness  80 . The controller  120  is allowed to retrieve and write information from and on the memory  51 . 
     While the process cartridge  3  is attached to or detached from the image-forming apparatus  100 , the holder  60  is movable in the second direction and/or the third direction relative to the casing  10 , the gear cover  42 , and the holder cover  64 . That is, the position of the electrical contact surfaces  71  can be varied in the second direction and/or the third direction according to the shape of the cartridge holder  110 . As a result, the electrical contact surfaces  71  are less likely to be rubbed against members of the image-forming apparatus  100 . 
     When the process cartridge  3  is attached to the image-forming apparatus  100 , the coil spring  63  changes into the second state from the first state. That is, the length of the coil spring  63  in the third direction becomes the second length shorter than the first length. Since the coil spring  63  is compressed in the second state, friction of the electrical contact surfaces  71  against the main-body terminal can be reduced. Moreover, since the electrical contact surfaces  71  are pressed against the main-body terminal due to a restoring force of the compressed coil spring  63 , electrical connection between the main-body terminal and the electrical contact surfaces  71  can be stabilized. 
     The dimension of the recess  624  in the second direction (depth) is greater than the dimension of the protrusion  932  in the second direction. Therefore, even in a state where the developing cartridge  1  is attached to the drum cartridge  2 , the second-holder outer surface  620  is movable relative to the holding plate  93  in the second direction. When the process cartridge  3  is detached from the image-forming apparatus  100 , the holder  60  is caused to move from a first position to a second position in the second direction. More specifically, the holder  60  is caused to pivot in the second direction about the main-body terminal during detachment of the process cartridge  3 . In the meantime, the first boss  612  moves in the second direction inside the first through-hole  641  of the holder cover  64 ; the second boss  613  moves in the second direction inside the second through-hole of the gear cover  42 ; and the third boss  614  moves in the second direction inside the third through-hole of the gear cover  42 . In this manner, pivoting of the holder  60  about the main-body terminal can mitigate rubbing of the electrical contact surfaces  71  against the main-body terminal during detachment of the process cartridge  3  from the image-forming apparatus  100 . 
     3. Modifications 
     It would be apparent to those skilled in the art that the embodiment described above is merely an example of the present disclosure and modifications and variations may be made therein without departing from the spirit of the disclosure. Hereinafter, various modifications and variations of the embodiment will be described focusing on differences from the embodiment. 
     3-1. First Modification 
       FIG. 9  is a perspective view of a developing cartridge  1 A according to a first modification to the embodiment. In  FIG. 9 , the gear cover  42 , the holder  60 , the holder cover  64 , and the memory cover  81  are not illustrated. The developing cartridge  1 A of the first modification includes a main board  50 A including the memory  51 , and a harness  80 A connecting the main board  50 A to the electrical contact surfaces  71 . Similarly to the embodiment described above, the main board  50 A including the memory  51  is positioned on the outer surface of the other end of the casing  10  in the second direction. However, the main board  50 A is arranged on the outer surface at a position between the handle  15  and the other end of the casing  10  in the first direction. The main board  50 A is fixed to the outer surface of the casing  10  with an adhesive, for example. With this structure of the first modification as well, since the memory  51  (main board  50 A) is not mounted in the holder  60 , the holder  60  can be made compact easily. 
     Incidentally, the length of the harness  80  of the embodiment can be made shorter than the length of the harness  80 A of the first modification. Hence, arrangement of the main board  50  of the embodiment between the handle  15  and the one end portion of the casing  10  in the first direction is preferable, compared to the arrangement of the main board  50 A of the first modification. 
     3-2. Second Modification 
       FIG. 10  is a perspective view of a developing cartridge  1 B according to a second modification to the embodiment. In  FIG. 10 , the gear cover  42 , the holder  60 , the holder cover  64 , and the memory cover  81  are not illustrated. The developing cartridge  1 B of the second modification includes a main board  50 B including the memory  51 , and a harness  80 B connecting the main board  50 B to the electrical contact surfaces  71 . Similarly to the embodiment described above, the main board  50 B including the memory  51  is positioned on the outer surface of the other end of the casing  10  in the second direction. However, in the second modification, the main board  50 B is arranged on the outer surface at a position between one end and another end of the handle  15  in the first direction. The main board  50 B is fixed to the outer surface of the casing  10  with an adhesive, for example. With this structure of the second modification as well, the holder  60  can be made compact easily, since the memory  51  (main board  50 B) is not mounted in the holder  60 . 
     Incidentally, the length of the harness  80  of the embodiment can be made shorter than the length of the harness  80 B of the second modification. Hence, arrangement of the main board  50  of the embodiment between the handle  15  and the one end portion of the casing  10  in the first direction is preferable, compared to the arrangement of the main board  50 B of the second modification. 
     3-3. Third Modification 
       FIG. 11  is a perspective view of a developing cartridge  1 C according to a third modification to the embodiment. In  FIG. 11 , the gear cover  42 , the holder  60 , and the holder cover  64  are indicated by phantom lines. The developing cartridge  1 C of the third modification includes a main board  50 C including the memory  51 , and a harness  80 C connecting the main board  50 C to the electrical contact surfaces  71 . In the third modification, the main board  50 C including the memory  51  is positioned between the casing  10  and the gear cover  42 . Specifically, the main board  50 C is positioned on an inner surface of the gear cover  42 . The main board  50 C is fixed to the inner surface of the gear cover  42  with an adhesive, for example. With this structure as well, the holder  60  can be made compact easily, since the memory  51  (main board  50 C) is not mounted in the holder  60 . Moreover, in the third modification, the main board  50 C is not exposed to the outside of the developing cartridge  1 C. Hence, the user is prevented from touching the memory  51 . 
     3-4. Fourth Modification 
       FIG. 12  is a perspective view of a developing cartridge  1 D according to a fourth modification to the embodiment. In  FIG. 12 , the gear cover  42 , the holder  60 , and the holder cover  64  are not illustrated.  FIG. 12  depicts a state where a panel of the casing  10  is opened, the panel being positioned at one side of the casing  10  in the third direction. 
     The developing cartridge  1 D of the fourth modification includes a main board  50 D including the memory  51 , and a harness  80 D connecting the main board  50 D to the electrical contact surfaces  71 . In the fourth modification, the main board  50 D including the memory  51  is positioned on an inner surface of the casing  10 . The main board  50  is fixed to the inner surface of the casing  10  with an adhesive, for example. With this structure as well, the holder  60  can be made compact easily, since the memory  51  (main board  50 D) is not mounted in the holder  60 . Moreover, the main board  50 D is not exposed to the outside of the developing cartridge  1 D. Hence, the user is prevented from touching the memory  51 . 
     Specifically, in the fourth modification, the inner surface of the casing  10  includes a first inner surface  16 D and a second inner surface  17 D. The second inner surface  17 D is farther away from the rotation axis X 2  (second axis) of the agitator  20  than the first inner surface  16 D is from the rotation axis X 2 . The main board  50  is positioned on the second inner surface  17 . Thus, the movement of the blade  22  of the agitator  20  is less likely to be restricted by the main board  50 D. Preferably, the main board  50 D is positioned outside the rotational locus of the blade  22 . However, the main board  50 D may be positioned inside the rotational locus of the blade  22 , provided that the blade  22  is elastically deformable. 
     Alternatively, the inner surface of the casing  10  may be formed with a recess. The main board  50 D may be disposed in the recess. With this structure, the movement of the blade  22  of the agitator  20  is less likely to be restricted by the main board  50 D. 
     3-5. Other Modifications 
     In the embodiment described above, the developing cartridge  1  is attachable to a corresponding drum cartridge  2  including one photosensitive drum  2 . Alternatively, the developing cartridge of the disclosure may be attachable to a drum unit including a plurality of photosensitive drums. Still alternatively, the developing cartridge of the disclosure may be directly attachable to an image-forming apparatus. 
     In the embodiment described above, the coil spring  63  is used as an urging member. Alternatively, the urging member of the disclosure may be another type of urging member such as a leaf spring or a torsion spring, instead of the coil spring. 
     In the embodiment described above, the harness  80  is used as a relay component including the plurality of electrically conductive wires bundled together. Alternatively, a plurality of electrically conductive wires that are not bundled together may be used as the relay component, instead of the harness. Still alternatively, another board may be provided between the main board  50  and the electrical contact surfaces  71 . 
     The detailed structure of the developing cartridge of the disclosure may have shapes different from those shapes illustrated in the attached drawings. Further, the parts and components described in the embodiment and modifications thereto may be combined appropriately, as long as no contradiction is invoked. 
     &lt;Remarks&gt; 
     The developing cartridges  1 ,  1 A,  1 B,  1 C and  1 D are an example of a developing cartridge. The casing  10  and gear cover  42  are an example of a housing. The developing roller  12  is an example of a developing roller. The rotation axis X 1  is an example of a first axis. The memory  51  is an example of a memory. The holder  60  is an example of a holder. The electrical contact surfaces  71  are an example of an electrical contact surface. The harnesses  80 ,  80 A,  80 B,  80 C and  80 D are an example of a relay component. The first-holder outer surface  610  is an example of a first end portion. The second-holder outer surface  620  is an example of a second end portion. The casing  10  is an example of a casing. The holder cover  64  is an example of a holder cover. The gear cover  42  is an example of a gear cover. The handle  15  is an example of a handle. The first inner surface  16 D is an example of a first inner surface. The second inner surface  17 D is an example of a second inner surface. The agitator  20  is an example of an agitator. The agitator shaft  21  is an example of an agitator shaft. The blade  22  is an example of a blade. The rotation axis X 2  is an example of a second axis. The memory cover  81  is an example of a memory cover.