Browse Prior Art Database

Original Publication Date: 1981-Dec-31
Included in the Prior Art Database: 2004-Apr-02

Publishing Venue

Xerox Disclosure Journal


In an electrophotographic printing machine, the developer material comprises toner particles adhering triboelectrically to carrier granules. During development, the toner particles are attracted from the carrier granules to the latent image forming a toner powder image. Thus, toner particles are being continually depleted from the supply of developer material. In order to maintain the desired level of copy quality, the toner particle concentration within the developer material must be maintained substantially constant. Hereinbefore, a control system monitored the level of toner particle concentration within the developer material and actuated a toner particle dispenser to furnish additional toner particles in response to an error signal indicating that the level of toner particles was beneath a predetermined value. However, a system of this type had no anticipatory characteristics. The control system depicted in the drawing has anticipatory characteristics. As shown therein, an exposure meter 10 is disposed in optical cavity 12 to sense the intensity of the light rays reflected from original document 14. The electrical output signal from exposure meter 10 is compared with a reference signal by comparator 16. The error signal from comparator 16 is transmitted to multiplier 18. Multiplier 18 also receives a signal from the copier 20 indicating the number of copies to be made. Multiplier 18 combines the signal from the copier with that from comparator 16 in a suitable algorithm to produce an output signal which is transmitted to the feed forward controller 22. The output from the feed forward controller 22 is an input to comparator 24. A photodiode 26 is positioned closely adjacent to photoconductive belt 28. A sample toner particle image is formed on photoconductive belt 28. Light rays reflected from the sample toner powder image are detected by photodiode 26. The output signal from photodiode 26 is transmitted to comparator 30.