| 摘要 |
PROBLEM TO BE SOLVED: To keep the electrostatic charge potential of a photosensitive body constant and to obtain stable image quality by electrostatically charging an image carrier by a prescribed current value and forming a reference pattern when the reference pattern is formed. SOLUTION: When the reference pattern is formed on a photosensitive drum 1 in the case of a toner replenishment control action for controlling the replenishment action of toner from the toner hopper 3 of a developing device 2, the drum 1 is electrostatically charged not by an electrostatic charge roller but by a transfer roller 5. That means, since the reference pattern is formed by electrostatically charging the drum 1 by using the roller 5 controlled to be a constant current when the concentration of the toner is controlled, it can be formed regardless of environmental change or secular change on a condition that the surface potential of the photosensitive body is always kept constant. Therefore, the proper density of a copied image can be obtained and surface staining and the attachment of carrier are not caused. |
