| 摘要 |
PROBLEM TO BE SOLVED: To stabilize a surface potential regardless of the change of dielectric layer film thickness and the characteristic fluctuation of an electrifying member, to output a high-definition image for a long time, and also to prolong the lives of an image carrier and an electrifying means by estimating the dielectric layer film thickness and the resistant value of the electrifying member by means of the electrifying member corresponding to the plural kinds of dielectric constant areas of the image carrier and controlling electrifying impressed voltage. SOLUTION: A photoreceptor 1 is constituted of first and second dielectric constant areas 1Ea, and 1Eb whose dielectric constants are different each other in a longitudinal shaft direction, and first and second electrifying rollers 2A and 2B are disposed to be brought into contact with each other with prescribed pressure respectively corresponding to the areas 1Ea and 1Eb. An electrifying bias impressing power source 3 with respect to first and second rollers 2A and 2B has first and second power source parts 3a and 3b, and an arithmetic unit 3c. The dielectric layer film thickness of the photoreceptor 1 and the resistant values of the rollers 2A and 2B are found from the characteristic of the impressed voltage and the current at each area, and the electrifying impressed voltage or the current value for obtaining the desired surface potential of the photoreceptor is decided. |
