Photoconductive layer deposited on TV tube - is uniformly charged so that subsequently applied charged particles are repelled to fill up pin holes, dust particles etc. (BE 16.8.77)

摘要

A slightly conductive coating (2) is applied to the surface (1) of a c.r.t. and covered with a layer of the photoconductive material (3). This is uniformly charged. At any conductive blemishes e.g a dust particle (4), or a pinhole in the layer (3) the charge leaks away through the first coating (2). A developer containing the same photoconductive material similarly charged is then applied. The charged particles are repelled from the charged areas and driven towards the blemishes, where they adhere. The method may be extended to deal also with non-conductive blemishes, though these are rarer. The surface is charged and exposed to light. The charge remains only on the non-conductive blemishes, which then accept a developer containing the photoconductive material, as before.