Abstract: The image forming apparatus includes a drum cartridge having a photosensitive drum and a drum drive input member; a developing cartridge configured to be movably mounted to the drum cartridge, the developing cartridge comprising a developing roller disposed so as to face the photosensitive drum and a developing drive input member; a drum drive transmission member configured to engage with the drum drive input member and configured to transmit drum driving force to the drum drive input member while permitting a positional gap of the drum drive input member within a predetermined range; and a developing drive transmission member configured to engage with the developing drive input member and configured to transmit developing driving force to the developing drive input member while permitting a positional gap of the developing drive input member within a predetermined range.

Abstract: An image forming apparatus, having a first photosensitive drum, a first developing roller, a first shifting member movable between a contacting position and a separating position, a motor, a first joint, a first clutch operable in one of a transmittable condition and a discontinuing condition, a first shifting cam rotatable between a first position, in which the first shifting cam locates the first shifting member at the contacting position, and a second position, in which the first shifting cam locates the first shifting member at the separating position, and a first switching cam rotatable between a third position, in which the first switching cam places the first clutch in the transmittable condition, and a fourth position, in which the first switching cam places the first clutch in the discontinuing condition, alongside the first shifting cam rotating between the first position and the second position, is provided.

Abstract: The image forming apparatus includes a drum cartridge having a photosensitive drum and a drum drive input member; a developing cartridge configured to be movably mounted to the drum cartridge, the developing cartridge comprising a developing roller disposed so as to face the photosensitive drum and a developing drive input member; a drum drive transmission member configured to engage with the drum drive input member and configured to transmit drum driving force to the drum drive input member while permitting a positional gap of the drum drive input member within a predetermined range; and a developing drive transmission member configured to engage with the developing drive input member and configured to transmit developing driving force to the developing drive input member while permitting a positional gap of the developing drive input member within a predetermined range.

Abstract: An image-forming apparatus includes a motor, a photosensitive drum, a developing roller, and a separation mechanism for moving the developing roller relative to the photosensitive drum. The separation mechanism includes: an end cam rotatable in a rotational direction; and a cam follower movable in accordance with a rotation of the end cam. The end cam includes a first surface, a second surface, a first sloped surface connecting the second surface to the first surface, and a second sloped surface connecting the first surface to the second surface in the rotational direction. The second sloped surface includes: a steep slope surface connected to the second surface; and a gentle slope surface connecting the first surface to the steep slope surface. The gentle slope surface slopes relative to the first surface by an angle smaller than an angle by which the steep slope surface slopes relative to the first surface.

Abstract: An image forming apparatus, having a motor, a first photosensitive drum, a second photosensitive drum, a first developing roller, a second developing roller, a first cam, a second cam, a first clutch, a second clutch, a first phase sensor, and a controller, is provided. On condition that a triggering condition is satisfied, the controller starts the motor to operate, place the first clutch in a transmittable condition to cause the first developing roller to move for a first separated position, and place the second clutch in a discontinuing condition; and place the second clutch in the transmittable condition to cause the second developing roller to move to the second separated position in one of cases where a predetermined period since the first clutch is placed in the transmittable condition elapses and where the controller receives the separation signal from the first phase sensor before the predetermined period elapses.

Abstract: An image forming apparatus includes a housing, a drawer, a photosensitive member rotatably supported by the drawer, a first roller rotatably supported by the drawer, a second roller, an urging member disposed at the housing for urging the second roller toward the first roller, and a positioner. The drawer is movable between a housed position at which the drawer is housed in the housing, and a shifted position at which the drawer is shifted from the housed position toward an exterior of the housing. The second roller is rotatably supported by the housing, disposed to face the first roller, and movable relative to the first roller. The second roller and the first roller pinch a sheet therebetween and transport the sheet toward the photosensitive member. The positioner is disposed at the drawer and positions the second roller relative to the first roller when the drawer is at the housed position.

Abstract: An image forming apparatus includes a black image forming portion, a color image forming portion, an intermediary transfer member, a transfer portion, and an executing portion capable of executing an operation in a color mode in which a color image is formed using the color image forming portion and the black image forming portion and an operation in a monochromatic mode in which a monochromatic image is formed using only the black image forming portion. The executing portion is capable of forming the monochromatic image in the operation in the monochromatic mode under application of a voltage to the black developing device. The voltage is applied under a voltage condition such that a line width is broader than a line width under a voltage condition inputted to the black developing device when the operation in the color mode is executed.

Abstract: An image forming apparatus includes an output shaft including a columnar part and a D cut part connected to the columnar part and having a D section, and an electromagnetic clutch including a cylindrical member fitted to the output shaft. The image forming apparatus further includes a key member. The key member includes a conductive member. When the D cut part of the output shaft is employed as an insertion tip side and the output shaft has been inserted to the cylindrical member from one side in an axial direction, the key member is configured to fill a space between the sectional circular part of the inner peripheral surface of the cylindrical member and the D cut part of the output shaft.

Abstract: An image forming apparatus performs a first preparation operation in a full color mode when power is supplied. The apparatus performs, when an image formation request is inputted after the first preparation operation completes, a second preparation operation in a designated color mode in accordance with the image formation request. When an image formation request is inputted during the first preparation operation, the apparatus skips the second preparation operation and performs image formation after the first preparation operation completes.

Abstract: An image forming apparatus includes a developing cartridge, a photosensitive drum, a lever, and an electrical connector. The developing cartridge includes a developing roller rotatable about a first axis extending in a first direction, a memory storing information related to the developing cartridge, and an electrical contact electrically connected to the memory. The photosensitive drum is rotatable about a second axis extending in the first direction. The lever moves the developing cartridge between a first position where a surface of the developing roller contacts a surface of the photosensitive drum and a second position where the surface of the developing roller separates from the surface of the photosensitive drum. The electrical connector contacts the electrical contact in the second position of the developing cartridge, and separates from the electrical contact in the first position of the developing cartridge.

Abstract: A developing cartridge has a casing accommodating toner therein; a developing roller rotatable about a first axis extending an axial direction; a cam electrically connected to the developing roller and rotatable about a second axis extending the axial direction from a first position to a second position, the cam being positioned at a third position distant from the casing by a first distance in the axial direction at the first position, and the cam being positioned at a fourth position distant from the casing by a second distance at the second position in the axial direction, the second distance being greater than the first distance; and a gear rotatable about the second axis, the gear engaging with the cam in a case where the cam is at the first position, and the gear disengaging from the cam in a case where the cam is at the second position.

Abstract: A rotary arm restricts the rotation of a first sun gear or a second sun gear according to forward/reverse rotation drive of sheet discharge rollers. As a result, a rotating direction of a transmission gear coupled to the sheet discharge rollers is switched. If ?1A denotes a pressure angle of gear teeth of a gear portion of the first sun gear and ?2A denotes a pressure angle of gear teeth of a first planetary gear, a relationship of ?2A+0.5°??1A??2A+1.5° is satisfied.

Abstract: An electrophotographic image forming apparatus includes a driving device including a first gear and a second gear, a power transmitter configured to transfer a rotational force applied in one direction from the motor to the first and second gears; a cam configured to set the power transmitter to one of a release mode in which the motor is disconnected from the first and second gears, a first connection mode in which one of the first and second gears is connected to the motor, and a second connection mode in which the other of the first and second gears is connected to the motor; and a clutch configured to selectively transfer the rotational force applied in the one direction from the motor to the cam.

Abstract: A developer cartridge includes a first gear having a first engagement part provided along a circumferential surface of the first gear, and a first trigger protruding from the circumferential surface. The developer cartridge also has a second gear having a small diameter gear part configured to be engaged to the first engagement part, a large diameter gear part rotatable together with the small diameter gear part, and a second trigger configured to contact and rotate the first gear. The large diameter gear part is configured to receive a driving force and rotate to move from a first position at which the large diameter gear part can rotate relative to the second trigger to a second position at which the large diameter gear part rotates together with the second trigger. The second trigger is configured to rotate together with the large diameter gear part to contact the first trigger.

Abstract: An image-forming apparatus includes a first photosensitive member, a second photosensitive member, an exposure unit, a first developing unit and a second developing unit. The first developing unit includes a first developing roller, a first casing and a first thickness-regulating blade having a first base end and a first free end. The second developing unit includes a second developing roller, a second casing and a second thickness-regulating blade having a second base end and a second free end. The first thickness-regulating blade is disposed between the first developing roller and the exposure unit, or between the first developing roller and a first optical axis of the light to which the first photosensitive member is exposed. The first thickness-regulating blade extends from the first base end to the first free end in a following direction with respect to a moving direction of a peripheral surface of the first developing roller.

Abstract: The conveyance apparatus includes a first engaging portion of a first planetary gear unit and a second engaging portion of a second planetary gear unit, and a stopping member movable to a first stop position to stop a first engaged gear, and to a second stop position to stop a second engagement gear, in which a pivot fulcrum of the stopping member is arranged at an intersection between an extension line of a vector of a force that the first engaging portion receives from the first engaged portion under a state in which the stopping member is at the first stop position, and an extension line of a vector of a force that the second engaging portion receives from the second engaged portion under a state in which the stopping member is at the second stop position.

Abstract: A system in an embodiment includes an image forming apparatus, an erasing apparatus, a first apparatus, and a display unit. The image forming apparatus forms an image on a sheet using a decolorable color material. The erasing apparatus decolorizes an image. The first apparatus computes, from a reduction in the number of sheets achieved by a setting for image formation in the image forming apparatus, the amount of a reduction in environmental burdens achieved by use of the image forming apparatus and computes, from the number of sheets erased by the erasing apparatus, the amount of a reduction in environmental burdens achieved by use of the erasing apparatus. The display unit simultaneously displays the amount of the reduction in environmental burdens achieved by the image forming apparatus and the amount of the reduction in environmental burdens achieved by the erasing apparatus.

Abstract: According to an embodiment, an image elimination apparatus eliminates an image formed on a sheet. A sheet supply unit supplies the sheet on which the image is formed. A first reader reads the sheet supplied by the sheet supply unit. An image eliminator eliminates the image formed on the supplied sheet. A second reader reads the sheet passing through the image eliminator. A discharge unit stacks the sheet to be discharged. A controller causes the first reader to read the sheet at a first speed in order to judge whether the sheet is reusable or not based on the reading result of the first reader. The controller also causes the second reader to read the sheet at a second speed faster than the first speed in order to judge whether the image formed on the sheet has been eliminated or not based on the reading result of the second reader.

Abstract: An image forming apparatus includes: first and second photosensitive drums; first and second developing rollers each defining an axis in an axial direction; first and second driving-force inputting sections; first and second couplings; and a connecting mechanism. A driving force inputted to each coupling is transmitted to each developing roller via each driving-force inputting section when each coupling is connected to the corresponding driving-force inputting section. The connecting mechanism is movable between a first position and a second position to cause the first and second couplings to move in the axial direction such that the first and second couplings are connected or disconnected relative to the first and second driving-force inputting sections.

Abstract: A method and apparatus for measuring a voltage are disclosed. In an embodiment a method for controlling a supply voltage includes providing a first periodic signal by providing a reference voltage to an oscillator, providing a second periodic signal by providing the supply voltage (VOUT) of a voltage source to the oscillator, providing a first count by measuring first periods of the first periodic signal, providing a second count by measuring second periods of the second periodic signal and comparing the first count with the second count.

Abstract: An image forming apparatus may include first, second, third, and fourth photosensitive media; a first driving source to rotate the first photosensitive medium; a second driving source to rotate the second photosensitive medium; and a planetary gear train to receive rotational forces of the first and second driving sources so as to rotate the third photosensitive medium, wherein the fourth photosensitive medium is rotated by being linked with the third photosensitive medium.

Abstract: A driving device includes a first rotary shaft, a second rotary shaft, a drive-transmission device including a plurality of drive-transmission paths, a first output target rotary body, and a second output target rotary body. The plurality of drive-transmission paths selectively transmits a drive force from the first rotary shaft to the second rotary shaft via any one of the plurality of drive-transmission paths. The first output target rotary body is mounted on the first rotary shaft to receive the drive force from the first rotary shaft. The second output target rotary body is mounted on the second rotary shaft to receive the drive force from the second rotary shaft.

Abstract: An image-forming apparatus contains a control portion, a thermopile sensor, a temperature sensor, a fan, a heater, a guide plate temperature detection sensor, an external air temperature detection sensor, a fixing temperature detection sensor and the color sensor. The control portion calculates estimated sheet temperature of the conveying sheet using information such as guide plate temperature, external air temperature, fixing temperature and paper weight. The control portion controls the fan or the heater to drive so that sensor temperature of the thermopile sensor approaches the estimated sheet temperature of the sheet. The control portion controls the thermopile sensor to carry out a measurement of the temperature of the sheet when the sensor temperature falls within a set range in relation to the estimated sheet temperature.

Abstract: An image forming apparatus includes a latent image bearer that carries a latent image and a developer carrier including a developer carrying member that carries a developer on a surface thereof. The developer carrier conveys the developer to a developing position opposite to the latent image bearer by moving the developer carrying member so as to develop the latent image carried by the latent image bearer. In a startup operation after a stop operation performed during a developing operation by the developer carrier, the developer carrying member is rotated for a predetermined time while the latent image bearer is set in a stopped state before starting a rotation.

Abstract: A photosensitive-body cartridge includes a photosensitive body, a cleaning roller, a primary electrode and a guide. The photosensitive body is configured to rotate together with a first rotational shaft extending in a first direction. The cleaning roller is configured to rotate together with a second rotational shaft parallel to the first rotational shaft and opposes the photosensitive body in a second direction perpendicular to the first direction. The primary electrode contacts one end of the second rotational shaft and is configured to supply power inputted from an external electrode to the cleaning roller. The guide is configured to guide the primary electrode to move in a third direction perpendicular to the first direction and intersecting the second direction.

Abstract: A drive switching device includes a driving source and a switching unit. The driving source is rotationally driven in one direction. The switching unit is linked with the driving source such that a driving force therefrom is intermittently transmittable to the switching unit, and switches a transmission direction of the driving force from the driving source between a first direction and a second direction every time the switching unit is linked with the driving source.

Abstract: An image forming apparatus according to an embodiment includes an image forming unit configured to form an image on a sheet using a plurality of decolorable color toners, wherein the decolorable color toners each have a preset fixing temperature and a preset decoloring temperature higher than the corresponding preset fixing temperature. The image forming apparatus further comprises a fixing unit configured to heat and apply pressure to the sheet having the image formed thereon to fix the image on the sheet, and a fixing temperature controller configured to control a fixing temperature of the fixing unit to be higher than or equal to a highest temperature among each of the preset fixing temperatures and to be lower than each of the preset decoloring temperatures.

Abstract: An image forming apparatus according to an embodiment comprises a first image forming section configured to form an image on a recording medium with a non-erasable material, and a second image forming section configured to form an image on the recording medium with an erasable material. The image forming apparatus further comprises a control section configured to separate image data according to attributes of the image data into first image data to be printed on the recording medium in the first image forming section and second image data to be printed on the recording medium in the second image forming section.

Abstract: An image forming apparatus includes a main casing and a cartridge detachably mountable therein. The cartridge includes a photosensitive drum and a developing roller disposed to oppose each other. The main casing includes: a metal frame for supporting the cartridge; a lock member supported to the metal frame and movable about a first axis to allow or restrict movement of the photosensitive drum relative to the metal frame; and a contact-separation member supported to the metal frame and movable about a second axis to allow contact and separation of the developing roller relative to the photosensitive drum. The lock member and the contact-separation member are aligned in an orthogonal direction orthogonal to an axis of the photosensitive drum such that the first axis is not overlapped with the contact-separation member or the second axis is not overlapped with the lock member in an axial direction of the photosensitive drum.

Abstract: A torque transmission mechanism includes a cam member which is rotatably supported and is provided with a cam for pressing a joint member in an axial direction of a rotation shaft and bush which is fitted to the cam member. The bush has an engagement surface with which the cam of the cam member engages. Above mechanism rotates the cam member and moves the cam member along the bush, thereby moving the joint member between an advanced position in which the torque of a drive source is transmitted to a rotary member and a retracted position in which the transmission of the torque of the drive source to the rotary member is released. A rib to which the bush is fitted is formed on an end surface of the cam member existing at a side at which the cam member is fitted to the bush.

Abstract: A supporting mechanism supporting an electrophotographic photosensitive drum having a photosensitive layer formed through a dip-coating on a peripheral surface of a cylindrical member, said supporting mechanism includes a bearing member supporting the electrophotographic photosensitive drum while contacting such a portion of the photosensitive layer as is away from one axial end of the electrophotographic photosensitive drum which have taken a lower position in the dip-coating, toward an axially central part.

Abstract: First and second developing members are moved to a developing position from a retracted position respectively in the order of a first developing member and a second developing member, and image forming is started by adhering toner to a first photosensitive member and a second photosensitive member in this order, and a period in which the first developing member moves from the retracted position to the developing position is shorter than a period in which the second developing member moves from the retracted position to the developing position.

Abstract: A cartridge comprises a housing configured to hold a color erasable material which is erasable by heating to a color erasing temperature. The cartridge further comprises a temperature sensing unit configured to detect a temperature of the housing and a recording section configured to record the detected temperature of the housing.

Abstract: A toner replenishment mechanism includes a motor, a first ratchet mechanical unit, and a second ratchet mechanical unit. The motor includes a rotation shaft with a pinion. The first ratchet mechanical unit engages the pinion. The first ratchet mechanical unit transmits only rotary drive power in a forward direction by the pinion to a driven mechanism disposed at a first toner replenishment unit. The first toner replenishment unit replenishes a first developer unit with a first color toner. The second ratchet mechanical unit engages the pinion. The second ratchet mechanical unit transmits only rotary drive power in a reverse direction by the pinion to a driven mechanism disposed at a second toner replenishment unit. The second toner replenishment unit replenishes a second developer unit with a second color toner.

Abstract: A network architecture includes an edge network having provider edge nodes configured to form a core network service VPN logically between subscribing customer network sites and a core service network, the core service network providing a core network service, the core service network including a core network service node, and a plurality of customer network sites having customer edge nodes attached to associated provider edge nodes of the edge network, wherein each customer edge node is configured to import routes tagged with a core service specific route target, and wherein the core network service node is configured to import routes tagged with a core service specific customer route target.

Abstract: According to an embodiment, an image forming apparatus has a fixing unit which heats an image formed on a recording medium at a fixing temperature, to fix the image on the recording medium. When a heating temperature of the fixing unit becomes a temperature higher than the fixing temperature, the image forming apparatus switches image forming, from image forming by a first mode using a discolorable coloring material, to image forming by a second mode using a non-discolorable coloring material.

Abstract: An image forming apparatus includes a main body; at least one developer including an image carrier unit having an image carrier and a charged body charging the image carrier, a developing unit installed to swing at a predetermined angle with respect to the image carrier unit and having a developing roller, and a pressing member pressing the developing unit so that the developing roller comes in contact with the image carrier, and separably installed in the main body; a nip separation unit installed in the main body on one side of the developer to swing the developing unit so that the developing unit is in a position that is separated from the image carrier; and a control unit controlling the developer and the nip separation unit according to a print command.

Abstract: An image forming apparatus includes a translation cam having a cam surface configured to move a developing roller from a contact position contacting a photosensitive member to a retracted position retracted from the photosensitive member and further having a holding surface configured to hold the developing roller at the retracted position. The image forming apparatus further includes a first engaging portion. The translation cam includes a second engaging portion. The first engaging portion and the second engaging portion are configured to engage each other before a functioning surface of the translation cam is switched from the holding surface to the cam surface.

Abstract: The image forming apparatus detects a color deviation amount in a timing when a developing roller separates from or contacts a photosensitive drum to set a difference in peripheral velocities between the photosensitive drum and an intermediate transfer belt or a transfer material conveying belt based on the color deviation amount and information about the use degree of the intermediate transfer belt.

Abstract: An image forming apparatus includes a plurality of image bearing members; a belt for receiving toner images from the image bearing members and for transferring the toner image onto a transfer material; a controller for driving the image bearing members; and wherein the image forming apparatus is operable in a monochromatic mode in which the toner image is formed only on a predetermined one of the image bearing members, and no image is formed on the other image bearing member, wherein in a operation in the monochromatic mode, the controller starts to drive the plurality of image bearing members in synchronism with each other in a state that the other image bearing member is spaced from the belt, and the predetermined image bearing member is in contact with the belt.

Abstract: An image forming apparatus includes a rotation driving source, a black developing unit, a color developing unit, a first gear, a second gear, a development drive transmission mechanism and a switching mechanism. The development drive transmission mechanism includes a first intermediate gear and a second intermediate gear. The switching mechanism includes a linear cam member configured to move linearly and to move the first intermediate gear and the second intermediate gear such that: in the first mode, the first gear engages the first intermediate gear and the second gear engages the second intermediate gear; in the second mode, the first gear engages the first intermediate gear and the second gear is disengaged from the second intermediate gear; in the third mode, the first gear is disengaged from the first intermediate gear.

Abstract: An image forming device includes a photosensitive unit, a developing unit, and a positioning unit. The photosensitive unit is configured to support a photosensitive body. The developing unit includes a developer carrying body and a unit case. The positioning unit configured to adjust a positional relationship between the developer carrying body and the photosensitive body. The positioning unit includes a separating unit configured to separate the developer carrying body from the photosensitive body, and a high pressure unit configured to provide a high pressure contact between the developer carrying body and the photosensitive body. A pressure in the high pressure contact is higher than a pressure in a normal pressure contact. The normal pressure contact is such a pressure that the developer carrying body and the photosensitive body are held during a printing operation.

Abstract: A developing cartridge that maintains a pressing condition to press a developer carrier against the image carrier is described. The developing cartridge may include a coil spring that presses the developer carrier against the image carrier. The coil spring may include a handle that transmits a pressing force to the coil spring via the contacting member. By doing so, every time the developing cartridge is replaced, a new coil spring and handle can be provided for the color laser printer with the developing cartridge attached. Therefore, a constant pressure by the coil spring can be continuously maintained. Thus, a preferable pressure condition of the developer carrier against the image carrier can be continuously maintained.

Abstract: An image forming apparatus includes an image forming part to form an image with one of a color unerasable developer and a color erasable developer, and a control part to automatically select the color erasable developer when test printing is selected.

Abstract: The present application is directed to methods and devices for moving a cartridge between engaged and disengaged positions in an image forming device. The image forming device may include a bias control arm movable between first and second positions. When the bias control arm is in one of the first and second positions, a biasing force on the cartridge is reduced and the cartridge moves to the disengaged position. When the bias control arm is in the other of the first and second positions, a biasing force on the cartridge is increased and the cartridge is moved to the engaged position. In one embodiment, the bias control arm moves in a first direction, and the cartridge moves in a second direction different than the first direction.

Abstract: In the case where a peripheral velocity of photosensitive drums differs from a peripheral velocity of an intermediate transfer belt, the peripheral velocity of the intermediate transfer belt or the peripheral velocity of the photosensitive drums is corrected. The velocity of the intermediate transfer belt is transiently varied in an image forming operation. Accordingly, a plurality of tonner patch patterns including toner patches are formed on the intermediate transfer belt, and the difference in peripheral velocity between the intermediate transfer belt and the photosensitive drums is estimated based on a difference between the displacements in the tonner patch patterns.

Abstract: An image forming apparatus is provided. The image forming apparatus includes a source, voltage generator to generate a source voltage to provide developing units with a power-supply voltage, a second voltage generator to generate a developing bias voltage applied to a developing roller and a supply bias voltage applied to a supply roller upon receiving the source voltage generated by the source voltage generator, and a switching unit to selectively provide the developing units with different voltage levels generated by the second voltage generator. The apparatus includes a Zener diode installed at a common end, so that a deviation of the developing voltage applied to the developing device affected by a deviation of Zener diode components can be reduced, resulting in an increased color image quality and a reduction in production costs.

Abstract: An image-forming device includes image carrying members aligned in a first direction in a main casing, one of the image carrying members being for black color, and remaining ones of the image carrying members being for other colors; a developing members provided in one-to-one correspondence with the image carrying members, each of the developing members configured to contact a corresponding image carrying member, one of the developing members being for black color, and remaining ones of the developing members being for other colors r; and a first contact/separation member linearly movable in the first direction, the first contact/separation member being disposed on one side of the plurality of developing members. The first contact/separation member comprises an elongated shape in the first direction. The first contact/separation member comprises a separating surfaces configured to contact respective developing members to separate the developing member from the image carrying member.

Abstract: An image forming apparatus includes a plurality of developing devices to develop toners of different colors on an image carrier; a power supply to supply the plurality of developing devices with a first voltage to develop the toners on the image carrier; a switching unit to connect the power supply to one of the plurality of developing devices; and a voltage divider to supply some of the other developing devices that are not connected to the power supply with a second voltage to prevent toner development and to supply any other remaining developing device with a third voltage, an absolute value of which is less then an absolute value of the second voltage.

Abstract: An image forming apparatus for forming a color image on a recording material includes mounting means for detachably mounting a plurality of process cartridges each including a photosensitive drum and a developing roller. Movable members are provided that are actable on first and second clutches for switching between an operation state for transmitting the driving force to the developing rollers and a non-operation state not transmitting the driving force thereto. Also provided is a switching member for switching among a first mode for transmitting the driving force to the developing rollers of all of the process cartridges, a second mode for not transmitting the driving force to any one of the developing rollers, and a third mode for transmitting the driving force only to the developing roller of a black process cartridge.