| 摘要 |
PROBLEM TO BE SOLVED: To improve the rounding of gradation by enhancing the contrast of an exposure image without modulating the strength of laser beam in multiple stages without making the beam diameter small and without generating ripples. SOLUTION: The surface of a photosensitive body is charged to the potential VH1 higher than the potential VH whereon toner is not made to adhere, and an exposure section to be exposed by the light beam of strength 1 and a non- exposure section are provided on a background section of an image section of gradation reproducing pixels. An image forming section of gradation reproducing pixels is exposed by pulse light of having an intensity of 2 higher than an intensity of 1. Although the intensity 2 has an excessively high laser power that lowers the photosensitive body surface potential lower than the surface potential VL suitable for making toner adhere when being exposed continuously, sections of making exposure off are combined together and pulse exposure is carried out to make the surface potential VL (C). The ratio between the non-exposure section and the exposure section is made smaller in compliance with the density by the background section of the image section of a highlight section (D), and the ratio is set as 0% in the vicinity of 0% (E). |
