Toner dispensing method

Abstract

In a method of operating electrostatic reproducing apparatus, developer made of a predetermined ratio of toner and carrier is continuously fed from a reservoir directly to a rotating developing sleeve for transfer to a photosensitive drum to continuously develop electrostatic latent images on the drum. Since some toner in the developer is consumed during image development, fresh toner from a source of supply is continuously dispensed by a movable roller (or endless belt) having toner-carrying recesses on the surface thereof to the reservoir so as to maintain the predetermined ratio of toner and carrier. Used developer containing unconsumed toner is continuously removed from the developing sleeve and a first portion of it is returned directly to the reservoir for re-use, whereas another portion of it is directed past the movable member so as to electrostatically dislodge toner from the roller or belt recesses and facilitate its entry into the reservoir. The roller or belt can be operated at a constant minimum rate of speed based on an estimate of toner consumption or can be operated in response to a measured toner/carrier ratio at a variable rate of speed higher than the minimum.