System for measuring toner concentration

摘要

A toner maintenance system for an electrophotographic developer unit, including a sump (40) for storing a quantity of developer material comprised of carrier and toner material; a first member (41) for transporting a mixture of developer material and toner particles from the sump (40), the first member (41) having a voltage applied thereto; a metering blade (47), positioned closely adjacent to the first member (41) to maintain the compressed pile height of the developer material on first member (41) at a desired level; and a sensor device (R3) for measuring the current between the first member (41) and the metering blade (47), and generating a signal indicative thereof.