摘要 |
A toner maintenance system for an electrophotographic developer unit, including a sump for storing a quantity of developer material a sump for storing a quantity of developer material comprised of toner material; a first member for transporting a mixture of developer material and toner particles from the sump, a viewing window, in communication with toner material, in the sump; an optical sensor, device for measuring reflected light off the viewing window and toner material, and generating a signal indicative thereof. A toner concentration controller is adapted to receive a signal from the sensor and to generate an "Add Toner" signal to replenish toner in the sump.
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