Development apparatus for an electrostatographic printing machine

Claim 1

An electrophotographic printing machine of the type having a photoconductive member, means for charging the photoconductive member to a substantially uniform charge potential, and an exposure mechanism for projecting a light image corresponding to the original document being reproduced onto the charged photoconductive member to record thereon an electrostatic latent image thereof, wherein the improvement includes: a developer housing defining an open ended chamber for storing charged particles; magnetic field producing means mounted internally of said developer housing and positioned closely adjacent to the photoconductive member, said magnetic field producing means forming a brush-like array of charged particles extending outwardly from the open end of the chamber of said developer housing in brushing contact with the electrostatic latent image recorded on the photoconductive member; at least one conductive plate having one end portion secured to said developer housing, said plate extending in an outwardly direction from the region of the brush-like array of charged particles extending from the open end of the chamber of said developer housing and being closely spaced from and substantially parallel to the photoconductive member; and means for electrically biasing said conductive plate to suppress the effects of local contrast enhancement during the development of the electrostatic latent image recorded on the photoconductive member.