Developer housing design with improved sump mass variation latitude

Abstract

A developer system for developing an image in an electrophotographic printing machine, including: a developer housing having a toner sump containing developer material; a magnetic development member rotatably mounted in the housing for transferring toner particles to a latent image on the photoreceptive member in a development zone; a transport system for transporting developer material from the toner sump to the magnetic development member, the transport system includes: a mix/pump auger, disposed in a first auger channel, for mixing and circulating developer material along a first path within the first auger channel; a transport auger, adjacent to the mix/pump auger and disposed in a second auger channel, for circulating developer material along a second path within the second auger channel; a wall member disposed in between the mix/pump auger and the transport auger, the wall member having a first opening disposed near an inboard end of the housing and a second opening disposed near an outboard end of the housing, the first and second opening providing a recirculating path between the first and second paths; a pick up area define in the first path, the pick up area having a predefined developer material volume; and a third opening in the wall member, disposed adjacent to the pumping section associated with a pumping section of the mix/pump auger, for providing a spillway from the first path to the second path to allow excess developer material to be recirculated when the developer material volume of the pick up area is substantially full.