Method of stabilizing an electrostatic latent image

A method of stabilizing an electrostatic latent image in the process of forming an electrostatic latent image on a photosensitive medium comprising a conductive layer, an insulating layer which does not become conductive by imagewise exposure, and a photoconductive layer interposed between said conductive and insulating layers and which becomes conductive by imagewise exposure through at least two kinds of charging steps, one of which is for sensitizing the photosensitive medium to receive an image formation thereon, and the other of which is for forming a charge pattern in accordance with a light image, said method comprising the steps of measuring the dark region potential V.sub.D and the light region potential V.sub.L on the photosensitive medium, comparing the measurement values with a predetermined referential dark region potential V.sub.DR and a predetermined referential light region potential V.sub.LR, respectively, calculating the amount of control for each of the charging steps to be controlled, by control functions f(x,y) and g(x,y), in which the difference x=V.sub.DR -V.sub.D and y=V.sub.LR -V.sub.L are variables controlling the amount of charge in said each of the steps by the calculated amount of control when the amount of control does not exceed a predetermined value.

A method of stabilizing an electrostatic latent image in a process of forming an electrostatic latent image on a photosensitive medium comprising a conductive layer, an insulating layer which does not become conductive by imagewise exposure, and a photoconductive layer interposed between said conductive and insulating layers and which becomes conductive by imagewise exposure by plural process means, said method comprising the steps of:

• varying the setting conditions of two image forming process means to form sequential light and dark images on said photosensitive medium and measuring the surface potentials at the light and dark images;
• and then
• setting the amount of control for each of said two process means by control functions f(x,y) and g(x,y), in which x=V.sub.DR -V.sub.D and y=V.sub.LR -V.sub.L, said functions including a coefficient which is determined by the measured values of the surface potentials at the light and dark images and said setting conditions.