Canon Kabushiki Kaisha

Mitsunori Oshima

Junya Kobayashi

Masaki Inagaki

A power source device includes a rectifying portion, a switching portion to apply a voltage to a load, fully rectified by the rectifying portion, a detecting portion to detect a zero-cross point of the AC voltage, and a filter including a capacitor provided between the rectifying portion and the switching portion. A controller controls the switching portion so as to execute a discharge operation to discharge the capacitor before starting a switching operation from a stop state of the switching operation and so as to start the switching operation when the zero-cross point is detected by the detecting portion. An electric power outputted from the switching portion during the discharge operation is smaller than an electric power outputted from the switching portion during the switching operation.

Power source device and image forming apparatus

A power source device includes first FET of which a source is connected to LIVE phase, second FET of which a source is connected to a drain of the first FET, third FET of which a source is connected to NEUTRAL phase, fourth FET of which a source is connected to a drain of the third FET, first capacitor connected between the source and the drain of the first FET, second capacitor serially connected between the drain of the second FET and the drain of the fourth FET, third capacitor connected between the source and the drain of the third FET, fourth capacitor connected between the LIVE and NEUTRAL phases, a detector to detect potentials of the LIVE and NEUTRAL phases, a controller controls the FETs based on a detecting result by the detector, and an inductive load connected between the drains of the first and third FETs.

A power supply apparatus includes a transformer including a primary coil, a secondary coil, and an auxiliary coil; a switching element connected in series to the primary coil; a first rectifying/smoothing circuit including a first diode and a first capacitor and configured to rectify and smooth a voltage induced in the auxiliary coil; a second rectifying/smoothing circuit including a second diode and a second capacitor, connected in parallel with the first rectifying/smoothing circuit, and configured to rectify and smooth the voltage induced in the auxiliary coil; and a controller configured to control the switching element. The controller is configured to detect the voltage induced in the auxiliary coil based on an output voltage of the first rectifying/smoothing circuit. A responsiveness of the second diode is better than a responsiveness of the first diode.

Power supply apparatus and image forming apparatus

The power supply apparatus includes a control unit to control an operation of a first switching element based on a feedback voltage and a voltage of an auxiliary winding of a transformer detected by a voltage detection unit. In a state where the voltage detected by the voltage detection unit is equal to or more than a first threshold voltage, the control unit shifts to a first state where the first switching element is controlled so that the output voltage is to be a first output voltage based on the feedback voltage. In a state where the voltage detected by the voltage detection unit is less than a second threshold voltage smaller than the first threshold voltage, the control unit shifts to a second state where the first switching element is controlled so that the output voltage is to be a second output voltage smaller than the first output voltage.

Growing community of inventors

Suntou-gun, Japan

Mitsunori Oshima