Abstract: A process cartridge includes a main cartridge configured to be attachable to an apparatus body of an image forming apparatus, and a sub cartridge configured to be attachable to the main cartridge, wherein the main cartridge includes a moving member configured to be capable of moving between a first position for preventing, by the moving member contacting the apparatus body, the main cartridge from entering the inside of the apparatus body and a second position for allowing the main cartridge to enter the inside of the apparatus body, and a regulation member capable of moving between a regulation position for locking the moving member at the first position and an allowable position for allowing the moving member to move to the second position, and wherein the regulation member moves to the allowable position by attaching the sub cartridge to the main cartridge.

Abstract: An image forming device includes a developing device unit including a plurality of developing devices, and a plurality of sloping members disposed in one-to-one correspondence with the plurality of developing devices. Each developing device includes a developing roller defining an axis line and a developer accommodating chamber. Each developing device is movable in a first direction perpendicular to the axis line. Each sloping member has a sloped surface and a biasing member biasing the sloped surface upward in the first direction. Each sloping member is movable between a first position where the developing device is placed on the sloped surface and a second position where the developing device is disengaged from the sloped surface in a predetermined direction different from the first direction.

Abstract: A main cartridge attachable and detachable to and from an apparatus body of an image forming apparatus for forming an image on a recording medium is provided. The main cartridge include a process device configured to act on a photosensitive member, a grip portion configured to be held by a user, and an attachment unit to attach a sub cartridge containing developer along the longitudinal direction of the main cartridge. In the longitudinal direction, the center position of the grip portion is disposed at the upstream side in the attachment direction of the sub cartridge from the center position of the main cartridge.

Abstract: An image forming apparatus is provided. An image forming apparatus includes: a drum cartridge having a photosensitive drum; a developing cartridge configured to be movably attached to the drum cartridge, the developing cartridge having: a developing roller; a bearing member; and a developing drive input member; and a spacing member for pressing against a predetermined portion of the developing cartridge and moving the developing cartridge such that the developing roller is spaced apart from the photosensitive drum, wherein the drum cartridge has an abutment portion with which the bearing member is brought into abutment, and wherein a straight line which connects the abutment portion with a center of a rotational axis of the developing drive input member extends substantially in the same direction as a connecting or disconnecting direction of the developing roller to or from the photosensitive drum.

Abstract: A developing unit usable with an image forming apparatus includes a first frame to support a photoconductive medium, a second frame to support a developing member to apply a developer to the photoconductive medium, the second frame movable between a first position in which the photoconductive medium is at a developing gap from the developing member, and a second position in which the photoconductive medium is away from the developing member by a distance exceeding the developing gap, and a positioning unit to move the second frame from a current position in accordance with mounting and demounting of the developing unit to and from the image forming apparatus.

Abstract: A developing apparatus includes an organic photo conductor, an OPC frame part to support the organic photo conductor, a developing roller to develop a latent image formed on the organic photo conductor by supplying a developer, a developing roller frame part to support the developing roller, a developer storing part to store the developer and provided with a supplying opening through which the developer is supplied to the developing roller, a spacer removably interposed between the OPC frame part and the developing roller frame part and spacing the OPC frame part from the developing roller frame part such that the organic photo conductor and the developing roller do not contact each other, a leakage preventer removably attached to and sealing the supplying opening, and a connecting part to connect the spacer with the leakage preventer. Thus, the spacer and the leakage preventer are capable of being removed simultaneously.

Abstract: A process unit includes a photosensitive unit, a developer unit, a first urging member, and a second urging member. The first urging member urges the developer unit with a first urging force when the developer unit is in a contact position where a developing member contacts a photosensitive drum. The first urging member urges the developer unit with a second urging force greater than the first urging force when the developer unit is in a separated position where the developing member is separated from the photosensitive drum. The second urging member urges the developer unit with a third urging force smaller than the first urging force when the developer unit is in the contact position. The second urging member urges the developer unit with a fourth urging force smaller than the third urging force when the developer unit is moved from the separated position to the contact position.

Abstract: An electrophotographic image forming apparatus includes an electrophotographic photosensitive drum and a developing cartridge. The developing cartridge is detachably mountable to a main assembly of the apparatus. A cartridge supporting member is movable, while detachably mounting the developing cartridge, between an inside position that is inside of the main assembly of the apparatus to mount the developing cartridge to the main assembly of the apparatus, and an outside position that is outside of the main assembly of the apparatus to remove the developing cartridge from the main assembly of the apparatus. When the cartridge supporting member detachably supports a plurality of such developing cartridges, and when the cartridge supporting member is moved from the outside position to the inside position, force receiving portions of the developing cartridges are contacted to force applying portions of the apparatus at different points of time.

Abstract: An image forming apparatus includes: an image carrier; a latent-image forming device; a developing device; a latent-image forming device contacting/separating mechanism; and a developing device contacting/separating mechanism, and the latent-image forming device contacting/separating mechanism allows the latent-image forming device to be movable to the latent-image forming device contacting position in a state where the developing device is moved to the developing device contacting position.

Abstract: A color electrophotographic image forming apparatus includes cartridge mounting portions for dismountably mounting cartridges and an intermediary transfer member onto which developed images formed on electrophotographic photosensitive drums are transferred. The apparatus also includes an image forming unit comprising the cartridge mounting portions and the intermediary transfer member. The unit is movable between a transfer position for transferring, onto a sheet, the developed images transferred onto the intermediary transfer member from the drums, a cartridge mounting and dismounting position for mounting and dismounting the cartridges relative to the cartridge mounting portions, and an intermediary transfer member mounting and dismounting position for mounting and dismounting the intermediary transfer member relative to a main assembly.

Abstract: In one embodiment there is provided a toner cartridge retaining clip. The retaining clip has a first end configured to engage a portion of a contact end cap of a toner cartridge, a second end configured to engage a portion of a toner hopper of the toner cartridge, and a body portion connecting the first end to the second end. The body portion has an abutting surface configured to abut a toner sensor contact on the toner cartridge. When the first end is securely engaged to the portion of the contact end cap, and the second end is securely engaged to the portion of the toner hopper, the first end and the second end exert opposing pressures on the toner cartridge to secure the contact end cap to the toner hopper.

Abstract: An image forming apparatus includes a detaching and pressing mechanism for releasing developing rollers of developer cartridges mounted in a drum unit from photosensitive drums and pressing the developing rollers on the photosensitive drums. The detaching and pressing mechanism includes a pair of translation cam members, intermediate members provided on the translation cam members, cam holders for holding the translation cam members in such a manner as to be linearly movable in an anteroposterior direction, and a synchronous movement mechanism for allowing the pair of translation cam members to linearly move in synchronization.

Abstract: An image forming device includes a main body, a support unit, a driving unit, a developer cartridge, a moving member, a transmitting member, and a detection member. The support unit can be pulled out from the main body in a removing direction. The developer cartridge is detachably mounted in the support unit and has a driving member. The driving member is driven by the driving unit when the developer cartridge is mounted in the support unit. The moving member moves when the driving member is driven by the driving unit. The transmitting member is provided to the support unit and is rotatable about a rotational axis which extends perpendicular to the removing direction and a longitudinal direction of a photosensitive member. When the moving member contacts the transmitting member, the transmitting member rotates. The detection member detects a rotation of the transmitting member.

Abstract: An image forming apparatus and an image forming method are provided that realize both the use of a decolorizing toner and a non-decolorizing toner and miniaturization of the apparatus.

Abstract: An electrophotographic image forming apparatus for forming an image on a recording material, includes an electrophotographic photosensitive drum; a cartridge including a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, the cartridge containing a developer for effecting development and including a force receiving portion, wherein the cartridge is mounted to a main assembly of the electrophotographic image forming apparatus; and an urging member for urging the cartridge; wherein by mounting the cartridge, the force receiving portion receives a force from the urging member to urge the developing roller to the electrophotographic photosensitive drum.

Abstract: A color electrophotographic image forming apparatus for forming a color image on a recording material, the apparatus includes an image forming unit rotatable relative to a main assembly of the color electrophotographic image forming apparatus, the image forming unit including a plurality of mounting portions for demountably mounting cartridges each provided with a developing member for developing an electrostatic latent image formed on an electrophotographic photosensitive member drum with a developer, and a transfer member for transferring the developed image on the recording material, wherein the image forming unit is rotatable between a transfer position for transferring the developed image from the transfer member onto the recording material and a mounting and demounting position, different from the transfer position, for mounting and dismounting the cartridge relative to the mounting portion in a state in which cartridges containing different color developers are mounted to the mounting portion; and a gr

Abstract: An electrophotographic photosensitive drum unit includes (a) a cylinder having a photosensitive layer at an outer periphery thereof, and (b) a drum flange provided at one end of the cylinder. The drum flange includes (i) a plurality of projections provided inside the drum flange and projected radially inwardly of the drum flange with a space between projections diametrically around the drum flange, and (ii) a recess provided at a position radially outside of an innermost portion of the projections.

Abstract: An image-forming device which may include a casing and a developing unit that is detachably mounted in the casing and formed with a first opening. The developer unit may have a developer carrying member carrying a developer, wherein the developing unit includes one end. The image-forming device may also include a first shutter configured to open and close the first opening and a developer cartridge that is configured to be detachably mounted in the casing, accommodate the developer, and is formed with a second opening. The second opening may be in alignment with the first opening when the developing unit and the developer cartridge are mounted in the casing. The image-forming device may also include a second shutter configured to open and close the second opening. The image-forming device may also include an alignment member between the developing unit and the developer cartridge.

Abstract: A process cartridge comprises an electrophotographic photosensitive drum, a drum unit, and a developing roller. The apparatus further comprises a developer supplying roller, and a developer accommodating portion accommodating the developer. A developing unit is swingably coupled with the drum unit and supporting the developing roller, the developer supplying roller, and the developer accommodating portion. A first-end developing-device spacing member is provided rotatably about an axis of a shaft at a first end portion of the developing unit to limit rotation of the developing unit relative to the drum unit to maintain spacing between the developing roller and the electrophotographic photosensitive drum. A second-end developing-device spacing member is provided rotatably about an axis of a shaft at a second end portion of the developing unit to limit rotation of the developing unit relative to the drum unit to maintain spacing between the developing roller and the electrophotographic photosensitive drum.

Abstract: In a single-body type imaging unit including a toner bottle provided with a drive shaft, and a print unit provided with a drive shaft, the toner bottle and the print unit are coupled to each other via an elastic member.

Abstract: A process cartridge usable with an image forming apparatus includes a developing member, a photosensitive medium to face the developing member, a pair of supporting plates to rotatably support the developing member and the photosensitive medium; a center moving member rotatably disposed on the supporting plate, the center moving member having a first position in which the photosensitive medium contacts the developing member and a second position in which the photosensitive medium is spaced apart from the developing member; and a separation restraining member formed so that when the center moving member locates at the second position, the separation restraining member restrains the center moving member from moving from the second position.

Abstract: A process cartridge includes: a drum cartridge including a photoconductor; a development cartridge configured to be detachably attached to the drum cartridge and including a developer carrying member for supplying developer to the photoconductor; a locking member provided on the drum cartridge and configured to be switchable between a locking position in which the development cartridge attached to the drum cartridge is in a locked state and restrained from being moved in a removing direction in which the development cartridge is removed from the drum cartridge and a lifting position in which the locked state is released and the development cartridge is movable in the removing direction, and a retaining member configured to retain the development cartridge which has been moved from the locked state in the removing direction by switching the locking member from the locking position to the lifting position.

Abstract: An image forming apparatus includes an information rewrite unit that rewrites information stored in a storage if an empty detector detects that a toner container is empty and the toner container is at least allowed to be released, and then if the empty detector detects that the toner container is not empty.

Abstract: An image forming apparatus includes a container storage that is installed on a toner container and stores first information relating to a use amount of a toner in the toner container and stores second information relating to a use amount of an image holding portion, which is a component not including the toner container and including at least an image holding body from among components installed in a cartridge; a housing storage that stores at least the second information and remains in the housing when the cartridge is removed from a housing; and an information write unit that writes the second information stored in the housing storage into the container storage if the first information stored in the container storage indicates that the toner in the toner container is unused and the second information stored in the container storage indicates that the image holding portion is used.

Abstract: There is provided a retaining clip apparatus and method for securing a toner feeder gear housing to a toner hopper of a toner printer cartridge. The apparatus comprises a first end configured to engage a protruding edge of the toner hopper. The apparatus further comprises a second end having a first surface configured to engage a portion of the toner feeder gear housing and having a second surface configured to engage a portion of the top cover housing, such that the second end is positioned within a space between the top cover housing and the toner feeder gear housing. The apparatus further comprises an elongated body portion connecting the first end to the second end.

Abstract: An image forming apparatus includes an apparatus body, a drum unit which holds photosensitive drums in parallel, a developing cartridge which is detachably mounted in the drum unit, a translation member which is provided in the apparatus body to be movable linearly, a shaft which is provided on the tandem photosensitive drum unit for each developing cartridge; and a pivoting member which is rotatably supported by the shaft. The pivoting member includes an abutting portion which is provided on one side to abut the translation member, a pressing portion which is provided on the other side, and is configured to press a predetermined portion of the developing cartridge in a direction in which the developing roller is separated from the photosensitive drum; and a spring portion which applies a biasing force in a direction in which the pressing portion is separated from the predetermined portion.

Abstract: An electrophotographic imaging unit includes a photoconductor housing, a developer housing, and a support. The photoconductor housing is configured to rotatably support a photoconductor drum. The developer housing is configured to accommodate developer and a developer roller. The support is configured to rotatably support the developer roller at opposite ends thereof. The photoconductor housing and the developer housing are hinged together at one side, and movable relative to each other at another side to open and close the imaging unit to sandwiched the support between the photoconductor housing and the developer housing when the imaging unit is closed.

Abstract: An electrophotographic image forming apparatus for forming an image on a recording medium includes an apparatus body having an endless belt incorporated therein configured to transfer toner images formed on a plurality of image bearing members to the recording medium, and a supporting member configured to support the plurality of image bearing members and to be slidable between inner and outer positions of the apparatus body along the arranged direction of the plurality of image bearing members, wherein when the supporting member slides between the inner and outer positions of the apparatus body while at least one of the plurality of image bearing members is in contact with the belt, a force is applied to the belt to rotate the belt along the moving direction of the supporting member.

Abstract: An electrophotographic image forming apparatus for forming an image on a transfer member, includes a main assembly of the electrophotographic image forming apparatus which is provided with a transfer member for transferring a developer image onto the transfer member; a supporting member movable between an inside position which is for supporting an electrophotographic photosensitive member on which the developer image is to be formed and which is inside the main assembly, and an outside position which is outside the main assembly; and a contacting and spacing member movable between a first position for spacing the electrophotographic photosensitive member from the transfer member in the state that the supporting member is in the inside position, and a second position for contacting the electrophotographic photosensitive member to the transfer member, the contacting and spacing member being provided in the supporting member.

Abstract: An image forming device has a main casing and a cartridge accommodating portion in which a combined unit of first and second cartridges can be loaded. The first cartridge includes a pressing member movable between a first position in which the second cartridge is removed from the first cartridge and a second position in which the second cartridge is combined with the first cartridge. A moving member supported on the main casing is movable between a third position in which the combined unit is unloaded from the main casing and a fourth position in which the combined unit is loaded in the main casing. The pressing member disposed in the second position presses the moving member to move to the fourth position. A determination unit does not start image forming operations until a position detector provided on the main casing detects that the moving member is in the fourth position.

Abstract: A developing device includes a developing unit having a developing frame defining therein a developing chamber and a developing roller rotatably disposed in the developing chamber, and a developing agent unit including a developing agent container that accommodates therein a developing agent, and an agitator disposed in the developing agent container and rotatable about a rotation axis in a rotational direction to agitate the developing agent. The developing agent container includes an arcuate bottom wall whose center of radius of a curvature is coincident with the rotation axis, and an arcuate protruding wall protruding from the bottom wall toward the developing chamber and positioned downstream of the bottom wall in the rotational direction. The protruding wall is formed with an opening providing a fluid communication between an interior of the developing agent container and the developing chamber. The opening has a downstream end in the rotational direction in an operational state.

Abstract: An aspect of the present invention provides an image forming unit including: a development unit that includes a development member; a photosensitive unit that includes a photosensitive member; a transfer unit that is disposed to face the photosensitive member; and an elastic member that is attached to the transfer unit and the development unit and urges the development unit toward the transfer unit to align the development unit and the photosensitive member with each other.

Abstract: An image forming apparatus includes: a photoreceptor unit having a photoreceptor drum on which an electrostatic latent image is formed; a developing unit for developing the electrostatic latent image formed on the photoreceptor drum; a developing unit supporting shaft for rotatably supporting the developing unit; a pressing lever for pushing and rotating the developing unit to press the developing unit against the photoreceptor unit; a rotatable pressing lever shaft for supporting the pressing lever; and a holding member for holding the developing unit supporting shaft and the pressing lever shaft to maintain a fixed distance between the developing unit supporting shaft and the pressing lever shaft.

Abstract: A developing unit detachably mountable in a photosensitive member unit including a photosensitive member on which an electrostatic latent image is formable, a pressing member, and a positioning portion includes: a developing unit frame; a developing roller; and a directing portion. The developing roller is rotatably supported to the developing unit frame, and configured to supply developing agent to the electrostatic latent image formed on the photosensitive member. The directing portion is fixed to the developing unit frame for directing the developing unit frame to a predetermined orientation and for fixing a position of the developer unit frame. The directing portion includes: a pressed portion configured to receive a pressure force from the pressing member for moving the developing roller toward the photosensitive member; and a positioned portion abuttable on the positioning portion for positioning the developing unit relative to the photosensitive member unit.

Abstract: A developing cartridge includes a photosensitive body, a developing unit which is disposed in parallel with the photosensitive body to develop the photosensitive body by toner, a cleaning unit to clean waste toner attached to the photosensitive body, a charging unit to charge the photosensitive body, and a supporting casing which comprises an accommodating main body having a first opening through which at least two components of the photosensitive body, the developing unit, the cleaning unit and the charging unit can pass in common, and a supporting unit to support the components accommodated inside the accommodating main body.

Abstract: A color electrophotographic image forming apparatus detachably mounts cartridges and includes a support supporting a cartridge, movable between inside and outside positions, an outer wall having an opening through which the support passes through when moving between the inside and outside positions, and a guide supporting the support to linearly move between the inside and outside positions so that when the support is in the outside position, the guide supports the support so that a downstream side thereof is pivotable downwardly about an upstream side of the support with respect to a movement direction to the outside position from the inside position. In this state, the cartridge is mounted to the support from above the support and is dismounted upwardly of the support.

Abstract: An image forming apparatus includes: an image carrier; a latent-image forming device; a developing device; a latent-image forming device contacting/separating mechanism; and a developing device contacting/separating mechanism, and the latent-image forming device contacting/separating mechanism allows the latent-image forming device to be movable to the latent-image forming device contacting position in a state where the developing device is moved to the developing device contacting position.

Abstract: A process cartridge includes a photosensitive drum, a charging unit, a developing unit, and a cleaning unit, arranged opposite to each other along a rotating direction of the photosensitive drum in an enclosure that has an opening opposite to a developing roller of the developing unit. An extended line connecting a tangent line to an outer circumference of the developing roller and a wall of a first end of the enclosure in an axial direction of the developing roller does not intersect with a wall of a second end of the enclosure.

Abstract: An image forming apparatus forms an image on a recording material, and detachably mounts which process cartridges having photosensitive drums. The apparatus includes a main assembly, a rotatable openable member, a belt receiving an image or carrying the recording material, supporting members supporting the process cartridges at different levels and movable between drum-contacting and retracted positions, and a connecting member moving the supporting member when the openable member moves to position the supporting member at the drum-contacting position when the openable member is closed, and position the supporting member at the retracted position when the openable member is opened, and including a shaft whose axis crosses the openable member rotational axis, first connecting portions rotatably connected with respective supporting members, and a second connecting portion engaging the openable member and fixed to the shaft closer to the openable member than the first connecting portions are fixed to the shaft.

Abstract: An image forming apparatus has a body frame and a slide frame. The slide frame is configured to be pulled out from the body frame along a sliding direction. A plurality of image forming cartridges is detachably mounted on the slide frame. A plurality of electrode members is mounted on the slide frame and aligned along the sliding direction so as to correspond to the image forming cartridges. A body-side contact portion of each of the electrode members is electrically connected to the body frame. A cartridge-side contact portion of the electrode member is electrically connected to the image forming cartridge. The image forming cartridge is connected to the body via the corresponding electrode member when the slide frame mounting the image forming cartridges is inserted to the body frame.

Abstract: A process unit includes a drum frame supporting a photoconductor drum and a development frame supporting a development roller. The development cartridge is swingably supported by the drum frame at a coupling joint provided at a first side of the development frame and a support portion provided at a second side of the development frame. A center of rotation of the development roller is located in a position shifted from a line segment connecting a center of rotation of the coupling joint and a center of rotation of the photoconductor drum to an upstream side with respect to a direction of rotation of the coupling joint as viewed in an axial direction of the development roller, such that the development roller is pressed against the photoconductor drum by the action of the rotatory force received by the coupling joint.

Abstract: A process cartridge is detachably mountable to a main assembly of an electrophotographic image forming apparatus. The process cartridge includes a photosensitive member unit having a photosensitive drum, a developer carrying member for developing an electrostatic latent image formed on the photosensitive drum with a developer, and a toner accommodating unit having a developer accommodating portion accommodating the developer to be used for development of the electrostatic latent image. A movable frame supports the developer carrying member, and an urging member is provided for urging the movable frame in a direction in which the developer carrying member approaches the photosensitive drum. A space maintaining member, is also provided for maintaining a state in which a distance between the photosensitive drum and the developer carrying member is larger than that in an image formation.

Abstract: An image forming apparatus for forming an image on a recording material includes a main assembly; a movable member movable, while supporting a cartridge including at least one of an image bearing member on which a latent image is to be formed and developing means for developing with a developer the latent image formed on the image bearing member, between an outside position in which the cartridge is located outside the main assembly and an inside position in which the cartridge is located inside the main assembly; and a cartridge displacing member for displacing the cartridge with respect to the movable member in a demounting direction in which the cartridge is demountable from the movable member in a state in which the movable member is located at the outside position.

Abstract: A guide surface of an attachment guide for a cartridge attached to a position nearest to a scanner has, in the vicinity of an inlet of the attachment guide, a portion oriented so as to be away from a guide surface of a guide unit for another cartridge from the upstream toward the downstream side in the direction in which the cartridges are attached.

Abstract: Provided is a configuration in which a scanner is mounted to a cartridge door via an elastic member, and the scanner is positioned relative to a frame that can be mounted to and demounted from an apparatus main body and that supports an intermediate transfer member and a photosensitive member using an urging force of the elastic member.

Abstract: An image forming apparatus includes plural developing devices, plural toner cartridges, and plural sub-hoppers that receive toners stored in the respective toner cartridges and supply the toners to the respective developing devices. The plural sub-hoppers are coupled by a coupling member. The coupled plural sub-hoppers are detachably held between the toner cartridges and the developing devices.

Abstract: An image forming apparatus is provided. An image forming apparatus includes: a drum cartridge having a photosensitive drum; a developing cartridge configured to be movably attached to the drum cartridge, the developing cartridge having: a developing roller; a bearing member; and a developing drive input member; and a spacing member for pressing against a predetermined portion of the developing cartridge and moving the developing cartridge such that the developing roller is spaced apart from the photosensitive drum, wherein the drum cartridge has an abutment portion with which the bearing member is brought into abutment, and wherein a straight line which connects the abutment portion with a center of a rotational axis of the developing drive input member extends substantially in the same direction as a connecting or disconnecting direction of the developing roller to or from the photosensitive drum.

Abstract: A printing device includes a receiving unit receiving image data, a printing unit transferring printing agent onto a sheet so as to form an image according to the image data received, a printing ratio determining unit determining, based upon the image data, a printing ratio that is a ratio of an area to be filled with the printing agent on the sheet to a whole area of the sheet, a first determining unit determining whether the printing ratio determined is equal to or more than a first predetermined value that is a printing ratio at less than which the sheet is classified into a recyclable sheet when the printing agent is transferred onto the sheet, and a control unit controlling the printing unit to transfer the printing agent onto the sheet depending on the determination by the first determining unit.

Abstract: An image forming apparatus may include an apparatus body, and a photosensitive-member unit slidably attached to the apparatus body and retaining a plurality of photosensitive members. The apparatus body includes side wall portions opposing each other with a unit receiving section sandwiched therebetween, and a plurality of apparatus-body-side electrode members provided on the side wall portions, and each urged inward in an opposing direction of the side wall portions. The photosensitive-member unit includes a plurality of unit-side electrode members each protruding outward in the opposite direction and a guide path comprising a flat surface formed in a flat shape so that each of the apparatus-body-side electrode members slidably contacts to the flat surface during attachment of the photosensitive-member unit with respect to the unit receiving section, and that each of the apparatus-body-side electrode members slidably contacted maintains a constant inward and outward position in the opposite direction.

Abstract: A developing unit and image formation device in which a developer carrier is reliably pressed towards and separated from an image carrier is described. A separation and pressing mechanism is provided for separating and pressing the developer carriers of developing cartridges installed in a drum unit onto image carriers. This separation and pressing mechanism has a pair of direct cam members. Each direct cam member has a release action portion that engages with the releasing projection of a developing cartridge when the developer carrier is to be separated from the image carrier. Each direct cam member may also have a pressing action portion that engages with the pressing projection of the developing cartridges when the developer carrier is to be pressed onto the image carrier.