Browse Prior Art Database

Original Publication Date: 1977-Feb-28
Included in the Prior Art Database: 2004-Mar-29

Publishing Venue

Xerox Disclosure Journal


In an electrophotographic printing machine, the bias on the developer rolls and the concentration of toner particles within the developer mix may be controlled. One type of control system employs a disc 22 having different density reference samples 38, 40 and 42. Before scan lamps 26 illuminate the original document, one of the reference den-sity samples is irradiated, The light image is projected through lens 18 and filter 20 onto charged photoconductive surface 12 in the non-image area thereof. The light image discharges the charged photoconductive surface recording a sample electrostatic latent image thereon. The potential of the sample electrostatic latent image recorded on photo-conductive surface 12 is detected by probe 28, i.e., a suitable electrometer disposed adjacent to photoconductive surface 12 between exposure station B and development sta-tion C. The electrical output signal from probe 28 is