PURPOSE: To make it posible to form an image of good gradation with a simple process step by charging te surface of a phtoreceptor under different voltages of charging with plural charging means.
CONSTITUTION: The surface of drum type photoreceptor 1 provided with insulating layer has previous history, and the previous history of the surface of the photoreceptor 1 is erased by lamp 2 and AC destaticizer 23, thereafter the photoimage of original document on the document tray 3 is radiated. Simultaneously, in the corona discharger 21 whose openng front is provided with grid divided into two groups, control voltage VG1 is applied to the grid positioned upstream relative to th rotary direction of the photoreceptor 1 so as to charge the photoreceptor 1. Next, the control voltage lower than the voltage VG1 is applied to the grid positioned downstream, and subsequently, the photoimage is radiated and it is charged. Thereafter th whole surface exposure is made by the whole surface lamp 24, and the electrostatic latent image which can be developed and also whose range of brightness control can be extended is obtained on the surface of the photoreceptor 1.
KUROSAKI YASUHIDE
AOKI TAKAO
IWAMI NAOKI
