| 摘要 |
PURPOSE:To appropriately adjust image density by controlling grid bias so that it may transit while keeping a fixed potential difference between the grid bias and developing bias at the time of adjusting the developing bias. CONSTITUTION:The device is provided with a voltage control means 13 for controlling the grid bias so that it may transit while keeping the fixed potential difference between the grid bias and the developing bias at the time of adjusting the developing bias supplied to a developing device 4 from a voltage generation means 12 which generates the developing bias supplied to the developing device 4, the grid bias supplied to the control grid 2b of an electrostatic charging means and voltage supplied to the electrode part 2a of the electrostatic charging means by a bias adjusting means 14. Therefore, the grid bias transits while keeping the fixed potential difference between the grid bias and the developing bias when the developing bias is changed in order to adjust the image density. Thus, the image density is changed while image fogging is kept constant. |
