Contact charging system for uniformly charging a charge retentive surface

摘要

A contact charging system uniformly charges a photoconductive surface by the use of a resistive belt surrounding and moved by two rollers and in contact with the photoconductive surface. The roller at the pre-nip area is grounded while that at the post-nip area is kept at a desired high potential. Alternatively, a pair of shoes are used for contact charging a photoconductive surface with one of the shoes being grounded and the other being biased to a desired DC potential by a biasing source. A resistive film is in contact with the pair of shoes with both the film and shoes being in contact with the photoconductive surface. Also, a blade is used to uniformly charge a photoconductive surface with one portion of the blade being grounded and another portion being biased to a desired DC potential. The blade is in direct contact with the photoconductive surface. This charging system tailors the electric field so that air breakdown only occurs at the post-nip area.