| 摘要 |
PURPOSE:To effectively use a photosensitive body having an induction effect with a little image exposing quantity by controlling the degree of the induction effect of the photosensitiv body by means of a pre-exposure. CONSTITUTION:An electrifier 2 has a corona housing whose top wall is pened, and a pre-exposing device 8 carrying out the pre-exposure of the photosensitive body 1 with the light of a proper quantity through the opening part of the housing is provided. The pre-exposing device 8 can adjust its irradiating light quantity by a controller, etc. When pre-irradiation is carried out with the light of the proper quantity before an image exposure, the photosensitive body 1 is pre-set in a critical state where the attenuation of its surface potential is started. When th image exposure is carried out with a digital optical signal in this state, the attenuation of a potential is suddenly progressed by a small light quantity. Thus, the photosensitive body 1 having the induction effect is effectively used, excellent sensitivity with respect to the digital optical signal is obtained, and a sharp image can be formed. |
