Abstract: An electrostatic copier has a travelling endless carrier on the photoconductive surface of which an electrostatic image pattern can be formed. Toner particles are electrostatically attracted to this pattern so as to form a visible image on the surface and are thereupon transferred to an image carrier. The photosensitive surface is then cleaned of residual toner particles in preparation for the next image formation. For the cleaning operation a mechanical wiper is in contact with the photosensitive surface and wipes the residual toner particles off the same; most of these particles adhere to the wiper and are then dislodged from their positions on the same and thereupon accelerated through space toward a container by the action of an electric field which is established intermediate the wiper and the container.