| 摘要 |
PURPOSE:To suppress cost required by a high voltage power source to the minimum by providing a bias voltage switching and supply circuit which successively switches and supplies a bias voltage outputted from the high voltage power source to a developing means which performs development out of plural developing means. CONSTITUTION:A sequence control part 13 is provided with a microcomputer and executes the on/off control of the high voltage power source 11 and the switching and control of the bias voltage for the respective developing units 4-7 by using a power relay array 12. Every time the color of toner is specified, the power source 11 is made in an on-state and the bias voltage outputted from the power source 11 is supplied to the developing unit of the specified color by switching with the aid of a unit switching signal in accordance with the specified color so that only the connection of the power source 11 and the developing unit storing the toner of the specified color may be ON. Thus, the number of high voltage power sources necessary for the plural developing means is only the minimum, and the cost required by the high voltage power source is reduced. |
