| 摘要 |
PURPOSE:To always keep the range of a picture erased by micro light sources composing a blank lamp constant irrespective of the various densities of the picture density of an original by varying the light quantity of the blank lamp according to the various densities of the picture density of the original. CONSTITUTION:The light quantity of the blank lamp 1 is varied according to the picture density data of a density sensor 2. For example, when the surface of a photosensitive drum 22 electrified to an electric potential V3 by an electrifying charger 23 is irradiated with light reflected from a low density original, and when the surface potential drops to a V2, the light quantity of the blank lamp 1 is reduced to minimize the surface potential drop caused by the blank lamp 1. Consequently, only the range D, which the parallel light beam of the blank lamp 1 face, of the surface of the photosensitive drum 22 can be set at a minimum potential V1 at which developer does not stick, by irradiating with the light of a copy lamp 32 reflected from the original and with the light of the blank lamp 1. Therefore, the range of the picture erased by the blank lamp 1 is always held constant irrespective of the various densities of the picture density of the original. |
