Abstract: An image forming apparatus that is capable of reducing velocity fluctuation due to variation of friction torque between an image bearing member and an intermediate transfer medium depending on a toner image. An exposure unit forms a latent image on the image bearing member rotated by a first drive unit. A development unit develops the latent image to form a toner image. A primary transfer unit transfers the toner image to an intermediate transfer medium rotated by a second drive unit. A secondary transfer unit transfers the toner image to a sheet. A control unit controls the drive units so that a peripheral velocity difference between the image bearing member and the intermediate transfer medium becomes a first value at starting, and controls so that the peripheral velocity difference becomes a second value larger than the first value when minute toner reaches the position of the primary transfer unit.

Abstract: An image forming apparatus that is capable of reducing velocity fluctuation due to variation of friction torque between an image bearing member and an intermediate transfer medium depending on a toner image. An exposure unit forms a latent image on the image bearing member rotated by a first drive unit. A development unit develops the latent image to form a toner image. A primary transfer unit transfers the toner image to an intermediate transfer medium rotated by a second drive unit. A secondary transfer unit transfers the toner image to a sheet. A control unit controls the drive units so that a peripheral velocity difference between the image bearing member and the intermediate transfer medium becomes a first value at starting, and controls so that the peripheral velocity difference becomes a second value larger than the first value when minute toner reaches the position of the primary transfer unit.

Abstract: An image forming apparatus that is capable of reducing velocity fluctuation due to variation of friction torque between an image bearing member and an intermediate transfer medium depending on a toner image. An exposure unit forms a latent image on the image bearing member rotated by a first drive unit. A development unit develops the latent image to form a toner image. A primary transfer unit transfers the toner image to an intermediate transfer medium rotated by a second drive unit. A secondary transfer unit transfers the toner image to a sheet. A control unit controls the drive units so that a peripheral velocity difference between the image bearing member and the intermediate transfer medium becomes a first value at starting, and controls so that the peripheral velocity difference becomes a second value larger than the first value when minute toner reaches the position of the primary transfer unit.

Abstract: An image forming apparatus includes a first image forming means for forming a toner image on a first photosensitive drum, a first motor configured to rotationally drive the first photosensitive drum, a second image forming means for forming a toner image on a second photosensitive drum having an outer diameter larger than that of the first photosensitive drum, and a second motor configured to rotationally drive the second photosensitive drum. The first motor is a DC motor, and the second motor is a stepping motor.

Abstract: An image forming apparatus capable of achieving improved image quality even when image formation is performed using a plurality of types of drive sources different in characteristics. Image forming units for colors form toner images of the respective colors on respective photosensitive drums each of which is driven by a DC motor for rotation. Encoder sensors detect information on the rotational speed of the photosensitive drums. An image forming unit for black forms a black toner image on a photosensitive drum having an outer diameter larger than that of the photosensitive drums for colors, which is driven by a stepper motor for rotation. An intermediate transfer belt transfers toner images formed on the respective photosensitive drums to a sheet. A motor controller controls a drive frequency of the stepper motor based on information on the rotational speed of the photosensitive drum for black.

Abstract: An image forming apparatus that is capable of reducing velocity fluctuation due to variation of friction torque between a photosensitive drum and an intermediate transfer medium depending on a toner image. An exposure unit forms a latent image on an image bearing member rotated by a first drive unit. A development unit develops the latent image to form a toner image. A primarily transfer unit transfers the toner image to an intermediate transfer medium rotated by a second drive unit. A secondary transfer unit transfers the toner image to a sheet. A control unit controls the drive units so that a peripheral velocity difference between the image bearing member and the intermediate transfer medium becomes a first value at starting, and controls so that the peripheral velocity difference becomes a second value larger than the first value when minute toner reaches the position of the primarily transfer unit.

Abstract: A drive apparatus for a stepping motor, including: a current detecting portion which detects a current value of phase current flowing through a phase winding; a constant-current-controlling portion which constant-current-controls the phase current flowing through the phase winding based on a detection result of the current detecting portion; a zero crossing detecting portion which detects a zero cross of the phase current based on the detection result of the current detecting portion; a phase difference detecting portion which detects a phase difference between the edge of a drive control pulse signal for the stepping motor and the zero cross detected by the zero crossing detecting portion; and a control device which causes the constant-current-controlling portion to perform constant-current control with a current value according to the phase difference detected by the phase difference detecting portion.

Abstract: A fixing apparatus capable of performing, even by a short brake, brake assist by which a sheet is stopped at a position where the sheet is visible. Upon occurrence of a wrap jam, brake control for a drive motor and brake assist control are performed. In the brake assist control, a pressing process is performed based on the number of assist operation pulses, which is set in advance. When an edge of a home position sensor signal is detected, a process for stopping the pressing process is carried out, whereby a pressing unit assumes a maximum pressing position.

Abstract: An image forming apparatus capable of achieving improved image quality even when image formation is performed using a plurality of types of drive sources different in characteristics. Image forming units for colors form toner images of the respective colors on respective photosensitive drums each of which is driven by a DC motor for rotation. Encoder sensors detect information on the rotational speed of the photosensitive drums. An image forming unit for black forms a black toner image on a photosensitive drum having an outer diameter larger than that of the photosensitive drums for colors, which is driven by a stepper motor for rotation. An intermediate transfer belt transfers toner images formed on the respective photosensitive drums to a sheet. A motor controller controls a drive frequency of the stepper motor based on information on the rotational speed of the photosensitive drum for black.

Abstract: An image forming apparatus includes a first image forming means for forming a toner image on a first photosensitive drum, a first motor configured to rotationally drive the first photosensitive drum, a second image forming means for forming a toner image on a second photosensitive drum having an outer diameter larger than that of the first photosensitive drum, and a second motor configured to rotationally drive the second photosensitive drum. The first motor is a DC motor, and the second motor is a stepping motor.

Abstract: A drive apparatus for a stepping motor, including: a current detecting portion which detects a current value of phase current flowing through a phase winding; a constant-current-controlling portion which constant-current-controls the phase current flowing through the phase winding based on a detection result of the current detecting portion; a zero crossing detecting portion which detects a zero cross of the phase current based on the detection result of the current detecting portion; a phase difference detecting portion which detects a phase difference between the edge of a drive control pulse signal for the stepping motor and the zero cross detected by the zero crossing detecting portion; and a control device which causes the constant-current-controlling portion to perform constant-current control with a current value according to the phase difference detected by the phase difference detecting portion.

Abstract: A fixing apparatus capable of performing, even by a short brake, brake assist by which a sheet is stopped at a position where the sheet is visible. Upon occurrence of a wrap jam, brake control for a drive motor and brake assist control are performed. In the brake assist control, a pressing process is performed based on the number of assist operation pulses, which is set in advance. When an edge of a home position sensor signal is detected, a process for stopping the pressing process is carried out, whereby a pressing unit assumes a maximum pressing position.

Abstract: An image forming apparatus forms an image by laser beams from a plurality of lasers. The image forming apparatus includes a light amount control circuit that detects displacement in a sub-scanning direction of the main scanning line of a laser beam from the predetermined laser, from a reference position. The apparatus decides an allotted amount of light for each of the plurality of lasers in accordance with the detected displacement and controls to drive each of the plurality of lasers in accordance with the decided allotted amount of light for each laser.

Abstract: An image forming apparatus forms an image by laser beams from a plurality of lasers. The image forming apparatus includes a light amount control circuit that detects displacement in a sub-scanning direction of the main scanning line of a laser beam from the predetermined laser, from a reference position. The apparatus decides an allotted amount of light for each of the plurality of lasers in accordance with the detected displacement and controls to drive each of the plurality of lasers in accordance with the decided allotted amount of light for each laser.

Abstract: In an image formation method of an image formation apparatus for correcting uneven image formation on the basis of vibration property information corresponding to an operation sequence in image formation, vibration property information corresponding to a plurality of operation sequences are stored in a storage device. The uneven image formation is corrected on the basis of vibration property information corresponding to an operation sequence selected from the storage device. Vibration property information generated by driving a movable member is measured when the selected operation sequence is being executed while correcting the uneven image formation. It is determined whether the measured vibration property information is similar to the vibration property information selected from the storage device. The vibration property information stored in the storage device is rewrite-controlled in accordance with the measurement result or the determination result.

Abstract: An image forming apparatus forms an image by laser beams from a plurality of lasers. The image forming apparatus includes a light amount control circuit that detects displacement in a sub-scanning direction of the main scanning line of a laser beam from the predetermined laser, from a reference position. The apparatus decides an allotted amount of light for each of the plurality of lasers in accordance with the detected displacement and controls to drive each of the plurality of lasers in accordance with the decided allotted amount of light for each laser.

Abstract: An image forming apparatus forms an image by laser beams from a plurality of lasers. The image forming apparatus includes a light amount control circuit that detects displacement in a sub-scanning direction of the main scanning line of a laser beam from the predetermined laser, from a reference position. The apparatus decides an allotted amount of light for each of the plurality of lasers in accordance with the detected displacement and controls to drive each of the plurality of lasers in accordance with the decided allotted amount of light for each laser.

Abstract: In an image formation method of an image formation apparatus for correcting uneven image formation on the basis of vibration property information corresponding to an operation sequence in image formation, vibration property information corresponding to a plurality of operation sequences are stored in a storage device. The uneven image formation is corrected on the basis of vibration property information corresponding to an operation sequence selected from the storage device. Vibration property information generated by driving a movable member is measured when the selected operation sequence is being executed while correcting the uneven image formation. It is determined whether the measured vibration property information is similar to the vibration property information selected from the storage device. The vibration property information stored in the storage device is rewrite-controlled in accordance with the measurement result or the determination result.

Abstract: The invention provides a fixing apparatus including a coil for generating a magnetic field; a heating medium having an electroconductive layer which generates heat by an eddy current by the magnetic field generated by the coil, and adapted to fix an unfixed toner image borne on a recording material by heat; a temperature detecting member for detecting the temperature of the heating medium; a semiconductor switch element for executing an on-off current supply to the coil; and a capacitor connected electrically parallel to the coil; wherein the capacitor executes charging and discharging, and an on-period from the semiconductor switch element to the coil is controlled according to the output of the temperature detecting member.

Abstract: A switching power supply unit is capable of performing zero-voltage switching in the entire load region to reduce switching loss and noise and improve the voltage transmission efficiency. The switching power supply unit has a main switching device, and an auxiliary switching device for controlling resonance so as to prevent power loss accompanying a switching action of the main switching device. A control circuit varies the OFF period, during which the main switching device and the auxiliary switching device are OFF simultaneously, according to power consumption by a load on an apparatus in which the switching power supply unit is installed.