| 摘要 |
PURPOSE:To reduce toner consumption by controlling turning on and off of light emitting elements in accordance with the region detected with a sensor at the time of preliminary scanning of a photosensitive drum for measuring an original density. CONSTITUTION:A photosensitive drum 1 is scanned preliminarily to detect the surface potential corresponding to a latent image on the drum 1 with a sensor 42 and the density of an original is measured. In this case, a large number of light emitting elements BL for blank exposure are controlled with a controller 44 and the elements corresponding to the region detected with the sensor 42 are turned off, and the elements BL corresponding to the other regions are turned on to illuminate the drum 1. As a result, a latent image is not formed on the area other than the necessary area, and toner consumption can be reduced at the time of detection of the image density. |
