| 摘要 |
PURPOSE:To decrease toner consumption by cutting down the range where light is turned off to the minimum in blank exposing means by turning off the light in a fractional part of the blank exposing means when electric potential of a photosensitive drum surface is measured. CONSTITUTION:An exposing unit 170, which has a fractionalized exposing part, consisting of a multiple number of LEDs which are placed along the surface of the photosensitive drum 131 in the axis direction, is provided. Then, when an optical system has been traveled forward for a specified distance from the image tip, the unit is started to travel backward, and automatic copying density adjustment AE is carried out. After traveling backward, only a part of the blank exposing unit 170's LEDs' light is turned off. Next, after delaying for the position deviation from the position of an image exposure 999 to an electric potential sensor 171, an AE measurement (sampling surface electric potential responding to an original density at a fixed cycle by the electric potential sensor) is started. Then after the delay from the image tip timing generating after traveling backward, the AE measurement is finished and all lights of the exposing unit 170 LED are turned off. |
