Electrostatic copier with coloured toner container - has facility for reversal development by controlling state of charge on toner at development point

摘要

An electrostatic copier is provided with a facility for reversal development and use of coloured toner. The coloured toner (42) is held in a supply container in an uncharged state. The outer cover (48) of the magnetic brush assembly (46) is made of a material with high specific volumetric resistance so that it does not retain a charge. It is electrically connected to the base (12) construction of the drum under the photosensitive material (16) carrying the latent image.