Browse Prior Art Database

Original Publication Date: 1982-Aug-31
Included in the Prior Art Database: 2004-Apr-04

Publishing Venue

Xerox Disclosure Journal


In an electrophotographic printing machine, it is frequently desirable to utilize a combined processing unit for developing the electrostatic latent image and cleaning residual particles therefrom. As shown in Figure 1, processing unit 18 is depicted in the cleaning mode. As illustrated thereat, a cylindrical magnet 50 having a plurality of magnetic poles about the circumferential surface thereof is disposed interiorly of a non-magnetic conductive tubular member 52. The interior circumferential surface of tube 52 is spaced from the exterior circumferential surface of magnet 50. Tube 52 is mounted rotatably and coupled to a drive motor. Magnet 50 is coupled to an indexing motor. Tube 52 rotates in the direction of arrow 54 and is positioned closely adjacent to the photoconductive surface of drum 10. Gap 56, located between the exterior circumferential surface of tube 52 and the photoconductive surface, depicts both the cleaning zone and development zone. The indexing motor is controlled to rotate magnet 50 so as to position a pole opposed from the photoconductive surface in the region of gap 56. In this way, there is a strong magnetic field during the cleaning mode of operation. This strong magnetic field creates a stiff brush of material which enhances cleaning. Voltage source 53 is connected to tube 52 and applies an electrical biasing field thereto. Preferably, tube 52 is electrically biased to a voltage level exceeding that of the latent image during the cleaning mode of operation. Housing 60 stores a supply of developer material. The developer material is attracted to the surface of tube 52. The developer material comprises magnetic carrier granules having toner particles adhering thereto. As tube 52 rotates in the direction of arrow 54, a strong magnetic field in conjunction with the electrical biasing applied thereto attracts residual toner particles adhering to the surface of drum 10.