| 摘要 |
PURPOSE:To obtain an image to be without a density change in a half tone and to be excellent in an evenness by superimposing an electric field to weaken an electric field in one part of a period to impress the electric field in a direction to cause a toner to transit and a part of the period to impress the electric field in a direction to separate-increase the toner from a photosensitive drum. CONSTITUTION:In a part of the period to impress the electric field in the direction causing the toner to transit from a developing sleeve 22 to a photosensitive drum 1, the excessive supply of the toner to an image part 5a is adjusted by weakening the electric field for mainly executing the transition of the toner, and inclination to react to electric lines of force from the image part 5a is given to the toner flying to a non-image part 5c. To the toner stuck to the photosensitive drum, in one part of the period to impress the electric field in the direction causing it to inverse-transit in a developing sleeve direction, by weakening the electric field, a gradation is made rich, a base fogging is made small, and the emphasis of an edge is properly executed. Thus, the image can be formed without changing the density in the half tone and with excellent in the evenness. |
