| 摘要 |
PURPOSE:To obtain specified copying density irrespectively of the change in copying magification by providing a generator for developing bias voltage which increases the developing bias voltage in accordance with an increase in magnification. CONSTITUTION:The image of an original 3 is formed on a photoreceptor 1 with an optical device 2, and is developed 4. The developing device 4 contains a magnetic roll 11 for development, and the roll 11 is so contituted as to be applied with specified voltage from a generator 12 for developing bias voltage. The generator 12 is constituted of a control part 13 which receives 3 kinds of variable power signals A, B, C; 1.3, 1.0, 0.85 times, and transmits bias voltage control signals, an oscillation control part 14 which receives the bias voltage control signals from the part 13, and a high voltage generating part 15 which receives the signals from the part 14 and transmits a output to the roll 11. The part 14 consists of oscillating and stabilizing circuits and applies the developing bias signals of 350, 200, 80V to the roll 11 when the signals of variable powers according to the variable power signals A, B, C applied to said part. |
