Browse Prior Art Database

Original Publication Date: 1979-Dec-31
Included in the Prior Art Database: 2004-Apr-02

Publishing Venue

Xerox Disclosure Journal


In electrophotographic printing machines, an electrometer may be employed to measure the potential on the photoconductive member. The output from the electrometer is then set to a pulsed power supply which biases a magnetic brush developer roller to a potential such that the toner particles are attracted to the photoconductive member. The pulse duration is determined by the size of the test image and the photoconductive member's speed. In this manner, a test patch is developed on the photoconductive member. The test patch may have light rays directed thereto. The light reflected from the test patch is detected by a photosensor and provides an indication of the density of the toner particles adhering to the photoconductive member. This, in turn, provides a measurement of the concentration of toner particles within the developer mixture. The signal may be employed to actuate a toner dispenser for furnishing additional toner particles to the developer mixture so as to maintain the concentration at a desired level.