Copying system featuring alternate developing and cleaning of successive image areas on photoconductor

Abstract

Abstract Electrophotographic copying apparatus has charging, imaging, transferring, precleaning, and erasing facilities in a conventional sense but incorporates a combined developingcleaning unit that is operable to perform either function at the proper time during the copying sequence. A first version incorporates a photoconductor drum structure surrounded with the necessary electrophotographic elements including a single magnetic brush developer-cleaner unit, the drum structure preferably having an odd number of image areas, such as three. Another version incorporates a photoconductor belt also having provision for an odd number of image areas and movable past the stations. For single copy operation, alternate image positions are used for copying with cleaning occurring on the positions between. With the operator changing masters, this delay is not noticeable. With an automatic document feeder, the throughput rate is half of the continuous copy rate. For continuous copy, every image position is used and cleaning is suspended until the end of the run at which time a full cycle cleaning operation is initiated. If the run is long and the copy degrades, intermediate cleanup cycles can be included as often as necessary. Conveniently, a magnetic brush element forms a contacting surface for conveying toner onto the photoconductor surface during developing and away from the photoconductor surface during cleaning. Appropriate changes in biasing of the brush are made during operation.

Inventors

• 👤 Leon M Cooper

Bibliographic Details