Abstract: One aspect is an image forming apparatus including a motor that drives a first member, a second member, a movement member that moves between a first position where the first and second members contact and a second position where the first and second members are separated, and a controller that receives an instruction to start a print job for forming an image on a recording medium, and executes an initial operation for determining a phase of a rotor of the motor in a stopping state of the rotor based on current flowing through a coil of the motor by supplying current to the coil in the stopping state in a state where the movement member is located at the first position, to control the current supplied to the coil to rotate the rotor in the stopping state based on the phase determined in the initial operation.

Abstract: One aspect is an image forming apparatus including a motor that drives a first member, a second member, a movement member that moves between a first position where the first and second members contact and a second position where the first and second members are separated, and a controller that receives an instruction to start a print job for forming an image on a recording medium, and executes an initial operation for determining a phase of a rotor of the motor in a stopping state of the rotor based on current flowing through a coil of the motor by supplying current to the coil in the stopping state in a state where the movement member is located at the first position, to control the current supplied to the coil to rotate the rotor in the stopping state based on the phase determined in the initial operation.

Abstract: An apparatus to control a motor includes a detector that detects a driving current flowing through a motor winding, phase determiner that determines a motor rotor rotation phase based on the detected driving current, generator that generates an instructed phase, and controller. The controller includes a first mode where controlling the driving current flowing through the motor winding controls the motor based on a torque current component value such that a deviation between the generated instructed phase and the determined rotation phase is reduced, and a second mode in which a current of a predetermined magnitude controls the motor. The torque current component is expressed in a rotating coordinate system based on determined rotation phase. The generator generates, based on the rotation phase determined while executing second mode, the instructed phase in the first mode when a controlling driving current mode is switched from the second to the first mode.

Abstract: An apparatus to control a motor includes a detector that detects a driving current flowing through a motor winding, phase determiner that determines a motor rotor rotation phase based on the detected driving current, generator that generates an instructed phase, and controller. The controller includes a first mode where controlling the driving current flowing through the motor winding controls the motor based on a torque current component value such that a deviation between the generated instructed phase and the determined rotation phase is reduced, and a second mode in which a current of a predetermined magnitude controls the motor. The torque current component is expressed in a rotating coordinate system based on determined rotation phase. The generator generates, based on the rotation phase determined while executing second mode, the instructed phase in the first mode when a controlling driving current mode is switched from the second to the first mode.

Abstract: A PWM signal generation unit generates a PWM signal based on a driving voltage so that a midpoint of the longer period out of an H level period and an L level period in each PWM period matches a midpoint of the PWM period. FETs of a full bridge circuit (a driving circuit) are driven according to a PWM signal, and a driving current that corresponds to an A-phase is supplied to a stepping motor. A current detector detects a driving current flowing through an A-phase winding of the motor based on a voltage that is generated across a shunt resistor, at a fixed time point that is in each PWM period and in the H level or L level period that is at the center of the PWM period.

Abstract: A PWM signal generation unit generates a PWM signal based on a driving voltage so that a midpoint of the longer period out of an H level period and an L level period in each PWM period matches a midpoint of the PWM period. FETs of a full bridge circuit (a driving circuit) are driven according to a PWM signal, and a driving current that corresponds to an A-phase is supplied to a stepping motor. A current detector detects a driving current flowing through an A-phase winding of the motor based on a voltage that is generated across a shunt resistor, at a fixed time point that is in each PWM period and in the H level or L level period that is at the center of the PWM period.

Abstract: An image forming apparatus that suppresses occurrence of color shift in images transferred from image bearing members onto an intermediate transfer member. A surface of each of a first photosensitive drum and second photosensitive drums is charged. An exposure device, provided for each photosensitive drum, forms an electrostatic latent image by exposing an associated one of the charged photosensitive drums. A developing device, provided for each photosensitive drum, develops the electrostatic latent image with toner. An intermediate transfer belt friction-drives the photosensitive drums for rotation and has the developed images transferred thereon. Timing for exposing the second photosensitive drums is controlled based on a first surface distance from an exposure light irradiated position to a primary transfer position of the first photosensitive drum, and a second surface distance from an exposure light irradiated position of each second photosensitive drum to a primary transfer position thereof.

Abstract: An image forming apparatus includes an intermediate transfer member configured to rotate an image bearing member by contacting and operating the image bearing member, an image bearing member drive unit configured to drive the image bearing member, a control unit configured to output a torque instruction value to the image bearing member drive unit to control an assist torque generated by the image bearing member drive unit, and a measurement unit configured to measure a maximum speed and a minimum speed of the surface of the image bearing member, wherein the control unit controls the image bearing member drive unit using a new torque instruction value determined based on torque instruction values respectively corresponding to a maximum speed and a minimum speed when controlling the image bearing member drive unit so that the maximum speed and the minimum speed are included in a range.

Abstract: An image forming apparatus includes an intermediate transfer member configured to rotate an image bearing member by contacting and operating the image bearing member, an image bearing member drive unit configured to drive the image bearing member, a control unit configured to output a torque instruction value to the image bearing member drive unit to control an assist torque generated by the image bearing member drive unit, and a measurement unit configured to measure a maximum speed and a minimum speed of the surface of the image bearing member, wherein the control unit controls the image bearing member drive unit using a new torque instruction value determined based on torque instruction values respectively corresponding to a maximum speed and a minimum speed when controlling the image bearing member drive unit so that the maximum speed and the minimum speed are included in a range.

Abstract: An image forming apparatus includes an intermediate transfer member configured to rotate an image bearing member by contacting and operating the image bearing member to be driven, an image bearing member drive unit configured to drive the image bearing member by generating an assist torque for operating the image bearing member to be driven, an extraction unit configured to extract an image bearing member speed fluctuation component and an intermediate transfer member speed fluctuation component, and a control unit configured to output a torque instruction value to the image bearing member drive unit to control the assist torque generated by the image bearing member drive unit, wherein the control unit controls the assist torque generated by the image bearing member drive unit so that a difference between the image bearing member speed fluctuation component and the intermediate transfer member speed fluctuation component is within a predetermined range.

Abstract: An image forming apparatus that suppresses occurrence of color shift in images transferred from image bearing members onto an intermediate transfer member. A surface of each of a first photosensitive drum and second photosensitive drums is charged. An exposure device, provided for each photosensitive drum, forms an electrostatic latent image by exposing an associated one of the charged photosensitive drums. A developing device, provided for each photosensitive drum, develops the electrostatic latent image with toner. An intermediate transfer belt friction-drives the photosensitive drums for rotation and has the developed images transferred thereon. Timing for exposing the second photosensitive drums is controlled based on a first surface distance from an exposure light irradiated position to a primary transfer position of the first photosensitive drum, and a second surface distance from an exposure light irradiated position of each second photosensitive drum to a primary transfer position thereof.