Method of electrophotographically manufacturing a luminescent screen for

Abstract

The method of electrophotographically manufacturing a luminescent screen on a substrate of a color CRT, according to the present invention, includes the steps of forming a photoreceptor by sequentially coating the substrate to form a conductive layer and an overcoating of a photoconductive layer, establishing an electrostatic charge on the photoconductive layer, and exposing selected areas of the photoconductive layer to visible light to affect the charge thereon. Then the photoconductive layer is developed by the application of suitable triboelectrically charged, dry-powdered screen structure materials. The improved process provides at least one wear-resistant, conductive contact patch on a peripheral portion of a surface of the substrate. The contact patch has a first portion which underlies at least one of the layers of the photoreceptor and is in electrical contact with the conductive layer, and a second portion which extends from the photoreceptor. The contact patch is utilized during the manufacturing process to electrically ground the conductive layer during charging of the photoconductive layer. The contact patch also is utilized to measure the charge on the photoconductive layer during the developing process. Additionally, the contact patch provides an electrical contact, in the finished tube, between an aluminized layer on the screen and at least one support for a shadow mask.