| 摘要 |
PROBLEM TO BE SOLVED: To form a high quality image even in the case of controlling development bias voltage by providing an image density control part which controls the development bias voltage and a toner supply bias voltage. SOLUTION: A development bias voltage control part 29 is connected to a development bias voltage supply power source 12 and a toner supply bias voltage supply power source 26, and, further, the image density control part 28 is connected to a development bias voltage control part 27 and a toner supply bias voltage control part 29. By manually inputting data through a console panel, the image density control part 28 changes the output voltages of the development bias voltage supply power source 12 and toner supply bias voltage supply power source 26 and thus can change image density in seven levels. At this time, the output-voltage difference between the development bias voltage supply power source 12 and the toner supply bias voltage power source 26 is controlled to a specific voltage difference. |
