Method of electrophotography

Claim 1

A method of electrophotography comprising the steps of preparing a photosensitive element including an electrode layer, a photoconductive layer and a transparent insulating layer, these layers being integrally provided in the order described; spplying first charges of one polarity to said insulating layer of said photsensitive element under the condition that an interface between said photoconductive and insulating layers is substantially filled with trapped charge carriers which have flowed through said photoconductive layer; applying second charges of a polarity opposite to said one polarity to said insulating layer simultaneously with projection of a light image to said element; then projecting a substantially uniform light thereto, thereby forming an electrostatic latent image on said insulating layer; and developing said latent image by use of a developing agent, characterized in that just before the step of the application of said second charges there is provided a further step of projecting a substantially uniform light to said photoconductive layer to release some of said charge carriers from the trapped condition, such that the released charge carriers can flow to said electrode layer during the application of said second charge to said insulating layer to control the potential of said latent image.

Claim 2

A method of electrophotography comprising the steps of preparing a photosensitive element including an electrode layer, a photoconductive layer and a transparent insulating layer, these layers being integrally provided in the order described; spplying first charges of one polarity to said insulating layer of said photsensitive element under the condition that an interface between said photoconductive and insulating layers is substantially filled with trapped charge carriers which have flowed through said photoconductive layer; applying second charges of a polarity opposite to said one polarity to said insulating layer simultaneously with projection of a light image to said element; then projecting a substantially uniform light thereto, thereby forming an electrostatic latent image on said insulating layer; and developing said latent image by use of a developing agent, characterized in that just before the step of the application of said second charges there is provided a further step of projecting a substantially uniform light to said photoconductive layer to release some of said charge carriers from the trapped condition, such that the released charge carriers can flow to said electrode layer during the application of said second charge to said insulating layer to control the potential of said latent image.

Claim 5

A method of electrophotography utilizing a photosensitive element which includes an electrode layer, a photoconductive layer, and a transparent insulating layer, these layers being integrally provided in the order described; comprising the steps of: applying first charges of one polarity to said insulating layer of said photosensitive element; waiting until the interface between said photoconductive and insulating layers has been filled with trapped charge carriers which have flowed through said photoconductive layer; exposing said photoconductive layer to a substantially uniform light irradiation to release a part of said charge carriers from the trapped condition; immediately thereafter applying second charges of the opposite polarity to said insulating layer simultaneously with the exposure of said photoconductive layer to a light image, thereby forming an electrostatic latent image on said insulating layer; and developing said latent image by a developing agent; whereby charge carriers released by said substantially uniform exposure can flow to said electrode layer during the application of said second charges to said insulating layer to control the potential of said latent image within a range fit for the development of said latent image.

Claim 6

A method of electrophotography utilizing a photosensitive element which includes an electrode layer, a photoconductive layer, and a transparent insulating layer, these layers being integrally provided in the order described; comprising the steps of: applying first charges of one polarity to said insulating layer of said photosensitive element; waiting until the interface between said photoconductive and insulating layers has been filled with trapped charge carriers which have flowed through said photoconductive layer; exposing said photoconductive layer to a substantially uniform light irradiation to release a part of said charge carriers from the trapped condition; immediately thereafter applying second charges of the opposite polarity to said insulating layer simultaneously with the exposure of said photoconductive layer to a light image, thereby forming an electrostatic latent image on said insulating layer; and developing said latent image by a developing agent; whereby charge carriers released by said substantially uniform exposure can flow to said electrode layer during the application of said second charges to said insulating layer to control the potential of said latent image within a range fit for the development of said latent image.