Abstract: A stepping motor driving apparatus includes a stepping motor having a rotor, a driving unit configured to drive the stepping motor, and a rotation position detection unit configured to detect a rotation angle of the rotor. A control unit calculates a magnetic pole position of the stepping motor based on a first detection result and a second detection result. The stepping motor rotates by a predetermined step in one rotation direction from an initial position and thereafter rotates by the predetermined step in the other rotation direction so that the stepping motor is in a first held state. The first detection result is detected in the first held state. The stepping motor rotates by the predetermined step in the other rotation direction from the initial position and thereafter rotates by the predetermined step in the one rotation direction so that the stepping motor is in a second held state.

Abstract: A CPU for controlling a first motor for rotating and driving a photoconductive drum and a second motor for rotating and driving an intermediate transfer belt determines the rotation speed of the photoconductive drum at the time of image formation on the basis of information on a load torque of the second motor detected when the second motor is driven at a predetermined rotation speed and the rotation speed of the first motor is gradually changed in a state where no high voltage is applied to a primary transfer roller and information on a load torque of the second motor detected when the second motor is driven at a predetermined rotation speed and the rotation speed of the first motor is gradually changed in a state where a high voltage is applied to the primary transfer roller.

Abstract: A CPU for controlling a first motor for rotating and driving a photoconductive drum and a second motor for rotating and driving an intermediate transfer belt determines the rotation speed of the photoconductive drum at the time of image formation on the basis of information on a load torque of the second motor detected when the second motor is driven at a predetermined rotation speed and the rotation speed of the first motor is gradually changed in a state where no high voltage is applied to a primary transfer roller and information on a load torque of the second motor detected when the second motor is driven at a predetermined rotation speed and the rotation speed of the first motor is gradually changed in a state where a high voltage is applied to the primary transfer roller.

Abstract: The stepping motor driving apparatus includes a stepping motor, a motor driver which drives the stepping motor, and an encoder which detects a rotation angle of a rotor of the stepping motor. A CPU of the stepping motor driving apparatus outputs a signal which controls the motor driver and calculates a magnetic pole position based on the rotation angle detected by the encoder. The CPU calculates the magnetic pole position based on a first detection value and a second detection value. The first detection value is a value detected by the encoder in a state where the stepping motor is rotated in a clockwise direction and held hereafter.

Abstract: A developing unit develops a latent image with a developing agent. A supply unit supplies, to the developing unit, a developing alternating current bias voltage with a waveform having a pulse period during which a rectangular wave is output and a blank period during which no rectangular wave is output. An input signal generation unit generates, as an input signal be supplied to a primary side of a transforming unit that forms the developing alternating current bias voltage, an input signal obtained by adding an additional pulse smaller in width than the rectangular wave in the pulse period at a timing to transit from the pulse period to the blank period.

Abstract: A voltage conversion unit converts alternating current voltage generated by an alternating current voltage generation unit into a predetermined output voltage. An adjustment unit monitors the output voltage and adjusts a driving pattern for driving the alternating current voltage generation unit in accordance with a waveform distortion generated in a rectangular wave of the output voltage. The driving pattern is a pattern having, in a half cycle of the rectangular wave of the alternating current voltage, a first ON period during which the alternating current voltage is applied to the voltage conversion unit, an OFF period during which the alternating current voltage is not applied to the voltage conversion unit, and a second ON period during which the alternating current voltage is applied to the voltage conversion unit. The adjustment unit adjusts a ratio of the first ON period, the OFF period, and the second ON.

Abstract: A motor controlling apparatus, including: a detector configured to detect a rotation speed of a rotary member rotated by a motor; a first determining portion configured to determine a first control value based on a difference between a target speed and the rotation speed; a second determining portion configured to determine a second control value based on an amount of change in the first control value; and a motor controlling portion configured to control the motor based on the second control value.

Abstract: An image forming apparatus includes a developing device configured to perform development and a voltage generation circuit configured to apply a developing bias voltage to the developing device. Here, the voltage generation circuit includes a transformer configured to generate an alternating voltage to be applied as the developing bias voltage on a secondary winding; a capacitor that is connected to a first end of a primary winding of the transformer; a first voltage generating unit that is connected to a second end of the primary winding and is configured to generate a first voltage; a second voltage generating unit that is connected to the first end via the capacitor and is configured to generate a second voltage; and a controller configured to perform control so as to store an electric charge in the capacitor with the first voltage and the second voltage before the alternating voltage is generated.

Abstract: An image forming apparatus includes a charging device to electrically charge a photosensitive member, an exposure unit to expose the charged photosensitive member to light, a development device to develop, with a developer, a latent image formed on the photosensitive member by the exposure unit, and a development bias voltage generating circuit to apply a development bias voltage to the development device. The development bias voltage generating circuit includes a transformer, a capacitor connected to one end of the transformer, first-fourth switching elements, a power source to supply a voltage to the first and third switching elements, and a control unit to control an on and off action of the first to fourth switching elements and independently control the voltages applied by the power source to the first and third switching elements.

Abstract: An image forming apparatus has a charging unit which charges an image carrier by applying a voltage to a charging member arranged to be in contact with the image carrier. The image forming apparatus includes an alternating voltage applying unit which generates an alternating voltage, a first voltage detection unit which detects a positive peak voltage of the alternating voltage, a second voltage detection unit which detects a negative peak voltage of the alternating voltage, a voltage amplitude determination unit which determines an amplitude value of the alternating voltage based on the positive peak voltage detected, and an alternating voltage control unit which outputs a signal which changes an output from the alternating voltage applying unit.

Abstract: A developing unit develops a latent image with a developing agent. A supply unit supplies, to the developing unit, a developing alternating current bias voltage with a waveform having a pulse period during which a rectangular wave is output and a blank period during which no rectangular wave is output. An input signal generation unit generates, as an input signal be supplied to a primary side of a transforming unit that forms the developing alternating current bias voltage, an input signal obtained by adding an additional pulse smaller in width than the rectangular wave in the pulse period at a timing to transit from the pulse period to the blank period.

Abstract: A voltage conversion unit converts alternating current voltage generated by an alternating current voltage generation unit into a predetermined output voltage. An adjustment unit monitors the output voltage and adjusts a driving pattern for driving the alternating current voltage generation unit in accordance with a waveform distortion generated in a rectangular wave of the output voltage. The driving pattern is a pattern having, in a half cycle of the rectangular wave of the alternating current voltage, a first ON period during which the alternating current voltage is applied to the voltage conversion unit, an OFF period during which the alternating current voltage is not applied to the voltage conversion unit, and a second ON period during which the alternating current voltage is applied to the voltage conversion unit. The adjustment unit adjusts a ratio of the first ON period, the OFF period, and the second ON.

Abstract: An image forming apparatus includes a developing device configured to perform development and a voltage generation circuit configured to apply a developing bias voltage to the developing device. Here, the voltage generation circuit includes a transformer configured to generate an alternating voltage to be applied as the developing bias voltage on a secondary winding; a capacitor that is connected to a first end of a primary winding of the transformer; a first voltage generating unit that is connected to a second end of the primary winding and is configured to generate a first voltage; a second voltage generating unit that is connected to the first end via the capacitor and is configured to generate a second voltage; and a controller configured to perform control so as to store an electric charge in the capacitor with the first voltage and the second voltage before the alternating voltage is generated.

Abstract: An image forming apparatus has a charging unit which charges an image carrier by applying a voltage to a charging member arranged to be in contact with the image carrier. The image forming apparatus includes an alternating voltage applying unit which generates an alternating voltage, a first voltage detection unit which detects a positive peak voltage of the alternating voltage, a second voltage detection unit which detects a negative peak voltage of the alternating voltage, a voltage amplitude determination unit which determines an amplitude value of the alternating voltage based on the positive peak voltage detected, and an alternating voltage control unit which outputs a signal which changes an output from the alternating voltage applying unit.

Abstract: An image forming apparatus includes a charging device to electrically charge a photosensitive member, an exposure unit to expose the charged photosensitive member to light, a development device to develop, with a developer, a latent image formed on the photosensitive member by the exposure unit, and a development bias voltage generating circuit to apply a development bias voltage to the development device. The development bias voltage generating circuit includes a transformer, a capacitor connected to one end of the transformer, first-fourth switching elements, a power source to supply a voltage to the first and third switching elements, and a control unit to control an on and off action of the first to fourth switching elements and independently control the voltages applied by the power source to the first and third switching elements.