| 摘要 |
PURPOSE:To miniaturize a unit and reduce its cost by dispensing with a step-up transformer through amplifying an output from an oscillating circuit by means of an amplification circuit. CONSTITUTION:A high-tension power unit used in a copying machine is constituted by connection of a voltage of 800-1500V high-voltage DC power E1 via resistance R1 with a collector of high withstand voltage transistor (hereinafter referred to as Tr) Q1 forming an amplification circuit. Also, an oscillating circuit 1 is connected with a base of this TrQ1, while a TrQ1 emitter is earthed via resistance R2. In this manner, the output of the oscillating circuit 1 is detected at the TrQ1 collector as an output amplified in the ratio of about R1/R2 and said output is coupled to an output of DC developing bias circuit 3 via bias resistance R3 by a coupling capacitor C1 so as to be applied from an output terminal P2 to a developing roller.
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