SEMICONDUCTOR LASER DRIVING CIRCUIT AND SEMICONDUCTOR LASER DRIVING CURRENT CONTROLLING METHOD

摘要

PURPOSE: To obtain a latent image electric potential in proportion to gradation by a method wherein the working minimum latent image electric potential and the work ing maximum latent image electric potential are selected within the range of a straight line change part of a characteristic curve of light amount vs latent image electric potential. ;CONSTITUTION: A working minimum latent image electric potential V₁ formed when laser beams of a working minimum light amount P₁ are applied to a photosensitive drum and a working maximum latent image electric potential V₂ formed when a working maximum light amount P₂ is applied are selected within the range of a straight line change part of a characteristic curve of light amount vs latent image electric potential which is higher than a development bias level VG. A surface electric potential of a photosensitive drum is detected to control the working minimum light amount P₁ and the working maximum light amount P₂ so that the working minimum latent image electric potential and the working maximum latent image electric potential can be kept V₁, V₂ selected, respectively. Thus, even when an image signal of an intermediate gradation is given as a laser beam strength modulation signal, a latent image electric potential having a higher gradation characteristic can be obtained.;COPYRIGHT: (C)1994,JPO