In an electrophotographic apparatus, densities of toner images of a light reference mark and a dark reference mark are detected by a density sensor, and input voltages such as an illumination power source voltage and an electrostatic charge voltage are varied by small values on the basis of a difference...http://www.google.es/patents/US5250988?utm_source=gb-gplus-sharePatente US5250988 - Electrophotographic apparatus having image control means
Electrophotographic apparatus having image control means
