| 摘要 |
PURPOSE:To eliminate an electric shock and to facilitate the work of electric wiring by using a low-voltage circuit as the recording density regulation system of an operator's operation board and connecting it to a developing bias generator through an insulating coupler. CONSTITUTION:The output of the developing bias voltage generator 6 is applied to a developing bias electrode through a relay contact RAc, but fed back to a differential amplifier DFA after the voltage is divided through resistances R8 and R9. The difference between a reference voltage, i.e. the output of a constant voltage circuit 12 and the feedback voltage is applied to the generator 6 as a control signal. Once either one of phototransistors Tpr1-Tpr6 photodetects light to be conducted resistances Rj (j=10-15) is connected to the R9 is parallel, and to set the value of the voltage fed back to the amplifier DFA, so that the output voltage of the generator 6 is determined by the output of a photocoupler 5b. According to said combination, the developing bias voltage corresponding to the position of a slider 7 is applied to the bias electrode. |
