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.

An image forming apparatus and a method of reducing image banding of the image forming apparatus is provided. The image forming apparatus includes: a photoconductor unit on which an electrostatic latent image is formed; and a conveying unit configured to convey printing medium at a first conveying velocity toward the photoconductor unit, and configured to convey the printing medium at a second conveying velocity that is lower than the first conveying velocity when the printing medium approaches the photoconductor unit.

An image-forming apparatus contains an image-forming portion, a first conveying portion that is arranged at an upstream side of the image-forming portion along a sheet conveying direction, a second conveying portion that is arranged at an upstream side of the first conveying portion along the sheet conveying direction and a control portion. The control portion controls the first conveying portion to move a pair of registration rollers along a direction that is orthogonal to the sheet conveying direction while the pair of registration rollers nips the sheet when conveying the sheet to the image-forming portion. The control portion controls the second conveying portion to move one of the pair of conveying rollers along the direction that is orthogonal to the sheet conveying direction while the pair of conveying rollers does not nip the sheet.

An image forming apparatus includes an image bearing member, an image forming portion, an endless belt, a plurality of stretching rollers including an inner roller, an outer roller, a position changing mechanism capable of changing a position of the inner roller to a first position and a second position positioned downstream of the first position with respect to a rotational direction of the endless belt, a feeding member, a feeding member driving portion, and a controller. A feeding start timing of a recording material by the feeding member depends on the position of the inner roller during transfer of a toner image onto the recording material.

The image forming apparatus includes a control unit for converting image information into an image signal and output the image signal with reference to a timing signal, a sheet feeding control unit for feeding a recording material, an image forming unit for forming the image on a photosensitive drum based on the image signal output from the control unit, a transmission unit for transmitting a length of the image corresponding to a length of an output period of the image signal, an automatic sheet length detection mechanism for acquiring a length of the recording material in a conveyance direction thereof, and an image control unit for controlling a time interval at which the timing signal is output based on the size of the image and the size of the recording material.

An image forming apparatus includes an image bearing member and transfer and control units. The transfer unit and image bearing member form a nip portion where a recording material receives a toner image. The control unit controls image formation based on a timing when a recording material leading edge is detected. To perform sheet conveyance, the control unit changes a first recording material conveyance speed to a second speed before a fed first recording material leading edge is detected. Before the first recording material leading edge reaches the nip portion, the control unit changes the first recording material conveyance speed to a first speed, slower than the second speed, based on when the fed first recording material leading edge is detected. The control unit obtains a timing for the image formation to the image bearing member based on when the conveyance speed is changed from the faster to slower speed.

An image forming apparatus, in which a method of positional adjustment performed in image forming, includes an image bearer, a transfer device to transfer an image formed on the image bearer onto a recording medium having a first side and a second side, a recording medium conveying path along which the recording medium travels to the transfer device, a first detector and a second detector to detect positional information of the recording medium on or near the recording medium conveying path, in which the first detector being disposed closer to the transfer device than the second detector to the transfer device in a sheet conveying direction on the recording medium conveying path, and an adjuster to adjust a position of the image based on at least one of former positional information obtained by the first detector and current positional information obtained by the second detector.

Provided is an image forming apparatus including an image carrier, a transfer unit, a driver, a hardware processor, an adjustment mechanism, and a speed detector. The hardware processor sets a command value. The hardware processor performs a constant-torque control based on a constant-speed drive torque detected in a constant-speed control. In the constant-torque control, the hardware processor performs a feedback control to set a reference value to an average speed of the driver during passage of a first sheet and calculate a difference from an average speed during passage of a subsequent sheet so as to derive the command value. The hardware processor determines whether a load torque increase, its factor, and/or its influence exceeds a threshold, and forcibly sets the reference value to a speed detected while a pressure between the transfer unit and the image carrier is reduced by the adjustment mechanism from the pressure during image transfer.

An image forming apparatus includes a transfer belt, a medium conveyer, a controller, a transfer unit, and a first detector. The medium conveyer conveys a recording medium at a medium conveying speed. The controller sets the medium conveying speed to a first speed corresponding to a belt conveying speed in a first period, to a second speed lower than the first speed in a second period, to a third speed higher than the second speed and different from the first speed in a third period, and to the first speed in a fourth period. The transfer unit transfers the conveyed developer image onto the conveyed recording medium. The first detector performs detection of the recording medium in the first or second period. The controller sets a length of the third period on the basis of a result of the detection performed by the first detector.

A sheet feeding device includes a feeding roller pair, a detecting portion, a first changing portion, a second changing portion, and a controller for controlling the first changing portion and the second changing portion. The controller starts a first feeding operation for feeding a sheet toward the obliquely feeding roller pair in a nipping state of the feeding roller pair and then starts a second feeding operation for feeding the sheet for abutting a side end of the sheet against the reference member in the nipping state of the obliquely feeding roller pair. The controller changes, after the first feeding operation is started and before the second feeding operation is started, a start timing of the second feeding operation on the basis of a detection result of a position of the side end of the sheet detected by the detecting portion.