Electrophotographic two-colour copier

摘要

An electrophotographic two-colour copier has a nonmagnetic sleeve for feeding magnetic toner to latent, electrostatic images on a photoconductor and for developing the images in one or both development sections for the two colours. It is possible by means of the so-called counter-electrode effect to obtain two-colour copies in which the so-called edge effect is completely or substantially eliminated. In different embodiments, a number of ribs and grooves are constructed on the external circumferential surface of the nonmagnetic sleeve. The crest faces of these ribs reduce the effective spacing between the nonmagnetic sleeve and the surface of the photoconductor. This reduction in the spacing is advantageous with reference to increasing the counter-electrode effect. At the same time, the grooves form devices for conveying an adequate amount of toner past the doctor blade in the developer device, whereas so far the conveyance of an adequate amount of toner past a doctor blade has represented a difficulty because the previously mentioned spacing from the nonmagnetic sleeve to the photoconductor was shortened.