PROCESS AND APPARATUS FOR FORMING ELECTROSTATIC CHARGE PATTERNS

摘要

A method for producing an electrostatic charge pattern on an insulating charge-receiving member comprising the steps of : (1) depositing an electron-image or ion-image, resulting from the image-wise exposure to ionizing radiation of a means or medium capable of emitting photoelectrons, onto an electrically insulative layer of a multilayer screen consisting of an array of apertures and comprising at least a conductive screen layer and an adjacent insulative screen layer, said depositing resulting in the formation of an electrical double layer charge on opposite surfaces of the insulative layer, which double layer charge produces fringing fields within the apertures, (2) positioning the multilayer screen with its image-wise charged insulative screen layer in front of a chargereceiving material and projecting under the influence of a propulsion field charged particles of the same charge sign as the charged particles deposited on the outerside of the insulative screen layer towards the conductive screen layer, whereby by the presence of the propulsion field and said fringing fields acting as blocking fields charged particles are image-wise received on said chargereceiving material. The method is especially useful in X-ray recording using an ionizable X-ray absorbing gas as photo-electron-emitting medium.