Document Type and Number:
Japanese Patent JPS6363906
Kind Code:
B2
Abstract:
PURPOSE:To prevent contrast lowering and ground staining, by detecting photoconductor potential after primary charging to compare it to a reference value, and controlling secondary charging in accordance with this result in 2-color copying electrophotography. CONSTITUTION:Drum-shaped photoconductor 1 is uniformly exposed, e.g. to red light from light source 21, simultaneously uniformly charged with primary charger 2, then reversely charged with secondary charger 3, exposed to colored light 22 original image to form negative and positive electrostatic latent images in accordance with its black area and red area, and developed with a black toner in developing unit 23, and with a red toner in developing unit 24. Surface potential of photoconductor 1 is detected with electrometer 43 after primary charging, and compared with a reference value with comparator 45 to make proper charging by controlling power supply 47 of secondary charger 3 with driver 46 in accordance with this result. Output of comparator 45 is memorized with memory 48 in order to control power supply 50 of primary charger 2 with driver 49 in accordance with the memorized potential of memory 48. A value measured with electrometer 44 is compared to a reference value in comparator 51 to control power supply 53 to an exposing unit and an exposure quantity 22 with driver 52.
Application Number:
JP9962979A
Publication Date:
December 08, 1988
Filing Date:
August 04, 1979
Export Citation:
International Classes:
G03G15/01; G03G13/01