A transfer device includes a plurality of photoconductors, a belt, a plurality of primary transfer rollers and control circuitry. The plurality of primary transfer rollers is disposed for the plurality of photoconductors, respectively. The plurality of primary transfer rollers brings the belt into contact with or separate the belt from the plurality of photoconductors. The control circuitry causes at least one of the plurality of primary transfer rollers to press against a corresponding at least one of the plurality of photoconductors to shift a printing mode.

A sheet supplying apparatus includes an alignment member pivotable to an alignment location for blocking and aligning fore-ends of media contained on a loading table, and a transport-allowing location for allowing a medium picked up by a pickup member to be transported, a cam gear including a gear portion partially including a tooth-omitted portion, and a cam portion for switching the alignment member between the alignment location and the transport-allowing location at first and second rotating locations, a swing arm pivotable about a same axis as a rotation axis of a main gear, and first and second swing gears supported by the swing arm to interlock with the main gear, selectively interlocking with the gear portion according to a rotating direction of the main gear, and rotating the cam gear to the first and second rotating locations.

An image forming apparatus includes a plurality of image bearing members, a transfer unit including an intermediate transfer belt, a plurality of transferring members which sandwich the intermediate transfer belt between the plurality of image bearing members and themselves, a biasing member which biases each of the plurality of transferring members toward the plurality of image bearing members via the intermediate transfer belt, and a frame which supports the intermediate transfer belt, the plurality of transferring members, and the biasing member, and an apparatus main body which supports the plurality of image bearing members and the transfer unit. The apparatus main body includes a supporting portion which supports the transfer unit and a biasing force receiving portion of which a position is between the plurality of transferring members in a moving direction of the surface of the intermediate transfer belt and which is capable of supporting the transfer unit.

An image forming apparatus includes an intermediate transfer member, first and second transfer members, and a control unit. The control unit includes a first state where both the first and second transfer members are separated from the intermediate transfer member, a second state where the first transfer member contacts the intermediate transfer member and the second transfer member is separated from the intermediate transfer member, and a third state where both the first and second transfer members contact the intermediate transfer member. The control unit controls the driving member to move the moving unit, controls switch the first state to the second state and thereafter switch the second state to the third state. A rotation speed of the driving member when the second state is switched to the third state is lower than a rotation speed of the driving member when the first state is switched to the second state.

A cam driver includes a support, a cam, a motor, and a retracting torque applicator. The support supports an object. The cam moves the support. The motor rotates the cam and maintains a position of the cam. The retracting torque applicator applies torque to the cam in a direction to move the object away from a counter object that faces the object.

An image forming apparatus, having process units, a transfer unit, a motor, first through fourth cams, a color-linkage gear train, a monochrome-transmission gear train, and a color-transmission gear train, is provided. Each of the process units has a developing unit including a developing roller and a drum unit including a photosensitive drum. The color-linkage gear train rotates the first cam, the second cam, and the third cam in shifted phases. The monochrome-transmission gear train transmits a driving force from the motor to a monochrome clutch, which engages and disengages transmission of the driving force from the monochrome-transmission gear train to the fourth cam. The color-transmission gear train transmits the driving force from the motor to a color clutch, which engages and disengages transmission of the driving force from the color-transmission gear train to the color-linkage gear train.

An optical sensor irradiates a control toner image formed on an intermediate transfer belt with light and detects reflection light of the light. A controller executes an abnormality diagnosis mode in a case where change in the phase of a cam is not detected by a phase detection portion until an elapse of a predetermined time or more since a start of output of a driving signal for driving a separation mechanism. In execution of the abnormality diagnosis mode, the controller outputs the driving signal for driving the separation mechanism, and is capable of outputting information about an abnormality of the phase detection portion and information about an abnormality of the separation mechanism and/or a driving unit on a basis of a detection result of the optical sensor that is obtained in a case where the light is radiated from the optical sensor while the driving signal is output.

An image forming apparatus includes: an annular transfer belt to which an image is transferred; a transfer roller that transfers an image to a recording medium when the recording medium passes through a transfer area formed between the transfer roller and the transfer belt; a drive mechanism that causes the transfer roller to rotate; and a speed adjustment mechanism that adjusts a rotational speed of the transfer roller achieved by the drive mechanism in units of a cycle of the transfer roller, and switches between a first adjustment pattern and a second adjustment pattern to execute switched adjustment pattern in a cycle including a state in which the transfer roller transports the recording medium, the first adjustment pattern for adjusting the rotational speed of the transfer roller, the second adjustment pattern for adjusting the rotational speed of the transfer roller with a pattern different from the first adjustment pattern.

Provided is an image forming apparatus capable of reducing a downtime for switching between a monochrome image forming mode and a color image forming mode. In the image forming apparatus, images formed by a plurality of image forming stations are transferred in superimposition onto a transfer member. Further, the image forming apparatus controls image formation in each of a first mode of performing image formation using only an image forming station located at the most downstream position in a moving direction of the transfer member among the plurality of image forming stations, and a second mode of performing image formation using the plurality of image forming stations.

An image forming apparatus includes: an annular transfer belt to which an image is transferred; a transfer roller that transfers an image to a recording medium when the recording medium passes through a transfer area formed between the transfer roller and the transfer belt; a drive mechanism that causes the transfer roller to rotate; and a speed adjustment mechanism that adjusts a rotational speed of the transfer roller achieved by the drive mechanism in units of a cycle of the transfer roller, and switches between a first adjustment pattern and a second adjustment pattern to execute switched adjustment pattern in a cycle including a state in which the transfer roller transports the recording medium, the first adjustment pattern for adjusting the rotational speed of the transfer roller, the second adjustment pattern for adjusting the rotational speed of the transfer roller with a pattern different from the first adjustment pattern.