IMAGE REVERSAL DEVELOPMENT METHOD AND APPARATUS

摘要

A method of and apparatus for effecting image reversal development in electrophotography. Liquid toner is introduced into a chamber containing a latent-image carrying photoconductive surface of an electrophotographic member and a metal plate arranged parallel spaced apart defining two boundaries of the chamber. A high d.c. bias is applied across the chamber having a value and polarity sufficient to raise the background areas of the latent image to a high charge potential and to reduce the remaining highest charged areas of said latent image to zero. The intermediately charged areas are reversed in polarity but the relative magnitude of their charges is maintained. The toner used has polarity opposite of the bias polarity. When the toning is completed, the bias polarity is reversed on completion of toning to drive particles still floating in the liquid toner to the plate clearing the suspending medium. The image obtained is the reverse of the "original" latent image. Apparatus is provided to practise the method described.