| 摘要 |
PURPOSE:To improve reproductivity of half tone by detecting surface potential of the photosensitive body by exposing the photosensitive body with half tone reproduction energy of a multiple number of grades, comparing this with E-V characteristic, and detecting and compensating the variation in the sensitivity of the photosensitive body. CONSTITUTION:The surface potential of the photosensitive body 1 exposed by a first half tone reproduction energy, consisting of multiple number of grades of half tone reproduction energy, is detected 12. Because compensation is carried out mainly with an average value of the deviation with the E-V characteristic, either photosensitive body electrifying voltage related to the image density or light beam outputting energy is compensated and controlled at a first feedback. After compensating and controlling, the surface potential is detected 12 by exposing the photosensitive body 1 with second half tone reproduction energy, and if there is any deviation with the E-V characteristic, either one of the photosensitive body electrifying voltage related to the image density, the light beam outputting energy, or developing bias which was not compensated and controlled at the first feedback is further compensated and controlled at second feedback as an auxiliary compensation. Thus, a stable half tone reproduction can be carried out well. |
