Ricoh Company, Ltd.

Tsunehide Takahashi

Hideo Kikuchi

Naoki Sato

Eiichi Katoh

Koichi Asakura

Hitoshi Hoshi

A first switching unit and a second switching unit are connected in series to an electric power load. A voltage supply unit, which is connected between the first switching unit and the second switching unit, supplies a voltage to the second switching unit. A determining unit determines an occurrence of a malfunction in at least one of the first switching unit and the second switching unit.

Power control device and image forming apparatus

A controller for controlling a bias power source associated with, for example, a developing unit of an electrophotographic copier such that a bias voltage to be applied to the developing unit for the adjustment of image density is variable in level. The controller includes a central processing unit in which a timer/event counter is built in for delivering a trigger pulse signal to trigger the power source. In order to produce a bias voltage associated with a desired density level, the trigger pulse signal is subjected to pulse width modulation control at a period which is far shorter than an output time consant of the power source.

Bias power source controller for an image forming apparatus

A high-tension power supply applicable to an electrophotographic image recorder switches a DC voltage, boosts the switched DC voltage by a transformer, and outputs a high DC or AC voltage through a high-voltage side and a low-voltage side terminal which are connected to a secondary winding of the transformer. A diode or diodes are connected between the low-voltage side terminal and a ground terminal. An ammeter may be connected between the low-voltage side and ground terminals to measure an output current of the power supply.

Growing community of inventors

Tokyo, Japan

Tsunehide Takahashi