The toner (18) is fed from a hopper onto a revolving magnetic roller (15) which brings the toner into contact with the latent image on a carrier (1)(at 17).The thickness of toner carried by the roller (15) is limited by a blade (16) adjacent to the outflow from the hopper and a guide plate (14) which wraps around the roller (15). Even and full toner cover of the roller (15) for development is distributed but of the least depth possible
