Method of increasing the image exposure and developing sensitivity of magneto-electric printing system

Claim 1

In an electrostatic printing method of the type wherein a uniform electrostatic charge is applied to a photoconductive layer, the charged layer is uniformly toned with magnetic toner particles, and the toned layer is subjected simultaneously to both a light image exposure to which the layer is sensitive and to a sub-threshold magnetic field, whereby to selectively remove magnetic toner particles from the light exposed portions of the layer, the improvement of: applying simultaneously with both the application of said magnetic field and said image exposure a flood light exposure to the toned layer, whereby to enhance the sensitivity of selective magnetic toner particle removal from said layer by speeding up the image formation on said layer.

Claim 9

A method of forming an image on a surface of a recording element comprising a photoconductive layer, said method comprising, in combination, the steps of: applying a substantially uniform electrostatic charge to tone it, applying magnetic toner particles to said charged surface to tone it, applying a magnetic field adjacent to said surface, said magnetic field being of a strength insufficient to remove said magnetic toner particles from said surface in darkness, but positioned to remove said magnetic toner particles from said surface adjacent light-struck portions of said photoconductive layer, when said photoconductive layer is exposed, exposing said photoconductive layer, while in said magnetic field, with an exposure of the image to be formed to increase the photoconductivity of said photoconductive layer, to reduce the electrostatic attraction between the exposed portions of said photoconductive layer and certain of said magnetic toner particles thereat, and to remove said certain magnetic toner particles from said surface by said magnetic field, whereby the remaining magnetic toner particles on said surface form said image, and directing separate light of substantially uniform intensity onto said toned surface during said exposing step and while in said magnetic field, to flood said toned surface with light, whereby to speed up the forming of said image on said surface.

Claim 10

A method of forming an image on a surface of a recording element comprising a photoconductive layer, said method comprising, in combination, the steps of: applying a substantially uniform electrostatic charge to tone it, applying magnetic toner particles to said charged surface to tone it, applying a magnetic field adjacent to said surface, said magnetic field being of a strength insufficient to remove said magnetic toner particles from said surface in darkness, but positioned to remove said magnetic toner particles from said surface adjacent light-struck portions of said photoconductive layer, when said photoconductive layer is exposed, exposing said photoconductive layer, while in said magnetic field, with an exposure of the image to be formed to increase the photoconductivity of said photoconductive layer, to reduce the electrostatic attraction between the exposed portions of said photoconductive layer and certain of said magnetic toner particles thereat, and to remove said certain magnetic toner particles from said surface by said magnetic field, whereby the remaining magnetic toner particles on said surface form said image, and directing separate light of substantially uniform intensity onto said toned surface during said exposing step and while in said magnetic field, to flood said toned surface with light, whereby to speed up the forming of said image on said surface.