Abstract: An image forming apparatus includes: an image bearing member configured to rotate; an image forming unit configured to form an image on the image bearing member; a detection unit configured to detect a test image formed on the image bearing member by the image forming unit; a controller configured to control a magnification of an image to be formed by the image forming unit based on a detection result of the test image by the detection unit.

Abstract: An image forming apparatus includes a motor, a first coupling, an attachable/detachable unit, a detector, a phase determiner, and a controller. The motor rotates a rotary member through the first coupling and the attachable/detachable unit. The controller includes a first control mode and includes a second control mode. In the second control mode, in a case where a rotor load torque applied value is greater than a first predetermined value and a rotor rotational speed value is greater than a second predetermined value, the controller switches from the second control mode to the first control mode.

Abstract: An image forming apparatus includes a motor, a first coupling, an attachable/detachable unit, a detector, a phase determiner, and a controller. The motor rotates a rotary member through the first coupling and the attachable/detachable unit. The controller includes a first control mode and includes a second control mode. in the second mode, in a case where a rotor load torque applied value is greater than a first predetermined value and a rotor rotational speed value is greater than a second predetermined value, the controller switches from the second control mode to the first control mode.

Abstract: An image forming apparatus includes: an image carrying unit; a unit-to-be-moved; a pulse motor; a moving mechanism including a rotatable member provided with a member-to-be-detected; a detecting portion; an executing portion; and a controller for causing the executing portion to execute a first stop mode on the basis of detection of the detecting portion when the unit-to-be-moved is changed in position from the second or third position to the first position and to execute a second stop mode on the basis of a pulse number of a driving signal when the unit-to-be-moved is changed in position from the first or third position to the second position and when the unit-to-be-moved is changed in position from the first or second position to the third position, and for making the change at least between the second and third positions by only unidirectional rotation of the pulse motor.

Abstract: A bearing, for supporting a rotation shaft of a rotatable member, capable of being supported by a supporting portion provided with an engaging hole engageable with the bearing includes positioning projections having contact surfaces and bearing projections having sliding surfaces on which an outer peripheral surface of the rotation shaft slides. The positioning projections project from different positions so that between adjacent positioning projections, an outer peripheral surface of the bearing and the inner wall surface of the engaging hole form a gap therebetween. The bearing projections project from different positions so that between adjacent bearing projections, an inner peripheral surface of the bearing and an outer peripheral surface of the rotation shaft form a gap therebetween. With respect to a circumferential direction of the rotation shaft, the positioning projections and the bearing projections are provided at positions different from each other.

Abstract: A bearing, for supporting a rotation shaft of a rotatable member, capable of being supported by a supporting portion provided with an engaging hole engageable with the bearing includes positioning projections having contact surfaces and bearing projections having sliding surfaces on which an outer peripheral surface of the rotation shaft slides. The positioning projections project from different positions so that between adjacent positioning projections, an outer peripheral surface of the bearing and the inner wall surface of the engaging hole form a gap therebetween. The bearing projections project from different positions so that between adjacent bearing projections, an inner peripheral surface of the bearing and an outer peripheral surface of the rotation shaft form a gap therebetween. With respect to a circumferential direction of the rotation shaft, the positioning projections and the bearing projections are provided at positions different from each other.

Abstract: An image forming apparatus includes a detection unit configured to detect a test pattern formed on an image carrier by image forming units; and an adjustment unit configured to control the image forming units to form the test pattern, and adjust relative positions of images based on a detection result of the test pattern. The adjustment unit is further configured to control the image forming units to form the test pattern after the image forming units have formed on the image carrier an image to be transferred to a sheet with a basis weight less than a threshold, and before the image forming units form on the image carrier an image to be transferred to a sheet with a basis weight greater than the threshold.

Abstract: An image forming apparatus includes: an image carrying unit; a unit-to-be-moved; a pulse motor; a moving mechanism including a rotatable member provided with a member-to-be-detected; a detecting portion; an executing portion; and a controller for causing the executing portion to execute a first stop mode on the basis of detection of the detecting portion when the unit-to-be-moved is changed in position from the second or third position to the first position and to execute a second stop mode on the basis of a pulse number of a driving signal when the unit-to-be-moved is changed in position from the first or third position to the second position and when the unit-to-be-moved is changed in position from the first or second position to the third position, and for making the change at least between the second and third positions by only unidirectional rotation of the pulse motor.

Abstract: An image forming apparatus includes: an image carrying unit; a unit-to-be-moved; a pulse motor; a moving mechanism including a rotatable member provided with a member-to-be-detected; a detecting portion; an executing portion; and a controller for causing the executing portion to execute a first stop mode on the basis of detection of the detecting portion when the unit-to-be-moved is changed in position from the second or third position to the first position and to execute a second stop mode on the basis of a pulse number of a driving signal when the unit-to-be-moved is changed in position from the first or third position to the second position and when the unit-to-be-moved is changed in position from the first or second position to the third position, and for making the change at least between the second and third positions by only unidirectional rotation of the pulse motor.

Abstract: An image forming apparatus is designed to be capable of easily suppressing a variation of an inclination of a sensor relative to an endless belt and capable of high accuracy and stabilized sensing operation. The image forming apparatus includes a belt unit having an endless belt supported to be rotatable in a circumferential direction, an image forming unit for forming an image on the belt unit, and an optical sensor for detecting light projected onto the endless belt. The image forming apparatus further includes a sensor supporting member for supporting the sensor, and a positioning portion including, as a unit, a first positioning portion for positioning the belt unit by being contacted by the belt unit and a second positioning portion positioning the sensor supporting member by being contacted by the sensor supporting member.

Abstract: An image forming apparatus includes: a detection unit configured to detect a test pattern formed on an image carrier by image forming units; and an adjustment unit configured to control the image forming units to form the test pattern, and adjust relative positions of images based on a detection result of the test pattern. The adjustment unit is further configured to control the image forming units to form the test pattern after the image forming units has formed on the image carrier an image to be transferred to a sheet with a basis weight smaller than a threshold, and before the image forming units form on the image carrier an image to be transferred to a sheet with a basis weight larger than the threshold.

Abstract: An image forming apparatus includes a transfer portion transferring a toner image to a sheet, and a sheet guide portion guiding the sheet to the transfer portion. The sheet guide portion includes a resin member and a conductive member. The conductive member is provided to be in contact with the sheet to which the toner image is being transferred by the transfer portion and on a surface of the resin member so as to be grounded through the resin member, and has a volume resistivity which is lower than that of the resin member.

Abstract: An image forming apparatus includes a determiner for determining whether to execute a first image formation in an acquisition mode, in which an image forming operation is carried out using an acquired timing, or a second image formation in a non-acquisition mode, in which the image forming operation is carried out using exposure timing acquired in a previous acquisition mode. The determiner makes the determination on the basis of a current output of a temperature sensor and a previous output of the temperature sensor. When the determiner determines the execution of the first image formation, driving speeds of a first driver and a second driver are set, before the execution of the operation in the acquisition mode, on the basis of the current output of the temperature sensor, and the operation in the acquisition mode and the image formation are carried out using the driving speeds currently set.

Abstract: An image forming apparatus including a determiner for determining whether to execute a first image formation for acquiring mode, and an image forming operation is carried out using the acquired timing acquired or a second image formation in non-acquiring mode, and the image forming operation is carried out using exposure timing acquired by a previous acquisition mode. The determiner makes the determination on the basis of a current output of a temperature sensor and a previous output of the temperature sensor. When the determiner determines the execution of the first image formation, driving speeds of a first driver and a second driver are set, before the execution of the operation in the acquisition mode, on the basis of the current output of the temperature sensor, and the operations in the acquisition mode and the image formation are carried out using the driving speeds currently set.

Abstract: To provide an image forming apparatus capable of easily suppressing a variation of an inclination of a sensor relative to an endless belt and the capable of high accuracy and stabilized sensing operation. An image forming apparatus (100) includes a belt unit (200) having an endless belt supported to be rotatable in a circumferential direction (R), an image forming unit (1Y, 1M, 1C, 1Bk) for forming an image on the belt unit, and an optical sensor (31) for detecting light projected onto the endless belt. The image forming apparatus further comprises a sensor supporting member (32) for supporting the sensor, and a positioning portion (400, 500) including, as a unit, a first positioning portion (400a, 500a) for positioning the belt unit by being contacted by the belt unit and a second positioning portion (401a, 501a, 501b) positioning the sensor supporting member by being contacted by the sensor supporting member.

Abstract: An image forming apparatus includes a transfer portion transferring a toner image to a sheet, a sheet guide portion guiding the sheet to the transfer portion. The sheet guide portion includes a resin member made of resin and a conductive member provided to be in contact with the sheet to which the toner image is being transferred by the transfer portion and on a surface of the resin member so as to be earthed through the resin member, and having a volume resistivity which is lower than that of the resin member.

Abstract: An image forming apparatus includes: an image carrying unit; a unit-to-be-moved; a pulse motor; a moving mechanism including a rotatable member provided with a member-to-be-detected; a detecting portion; an executing portion; and a controller for causing the executing portion to execute a first stop mode on the basis of detection of the detecting portion when the unit-to-be-moved is changed in position from the second or third position to the first position and to execute a second stop mode on the basis of a pulse number of a driving signal when the unit-to-be-moved is changed in position from the first or third position to the second position and when the unit-to-be-moved is changed in position from the first or second position to the third position, and for making the change at least between the second and third positions by only unidirectional rotation of the pulse motor.

Abstract: A developer supply apparatus includes a buffer portion for storing a developer supplied from a developer container, a feeding device for feeding the developer, stored in the buffer portion, toward a developing device, and a pair of light transmitting members which permit light transmission for detecting the developer in the buffer portion. In addition, a vibrating device vibrates the pair of light transmitting members in an optical axis direction.

Abstract: A developer supply apparatus includes a buffer portion for storing a developer supplied from a developer container; a feeding device for feeding the developer, stored in the buffer portion, toward a developing device; a pair of light transmitting members, which permit light transmission, for detecting the developer in the buffer portion; and a vibrating device for vibrating the pair of light transmitting members in an optical axis direction.