Browse Prior Art Database

Original Publication Date: 1980-Jun-30
Included in the Prior Art Database: 2004-Apr-02

Publishing Venue

Xerox Disclosure Journal


In a photocopying process using a photoreceptor with a photoconductive layer and an insulating layer overcoating, it is common to use separate corona generating devices for the sequential steps of pre-charging, simultaneous charge and exposure, and post-exposure shunting. These functions can be combined in a single corona device of the type shown in Figure 1. The photoreceptor 1, moving in the direction of the arrow, consists of a grounded conductive substrate 2, a photoconductive layer 3, and an insulating overcoating layer 4. Three coronas forming structures 5 (called dicorotrons) consist of conductive wires coated with glass. The three dicorotrons 5 are connected together and excited with an AC potential of 6.2 kV RMS at a frequency of 4 kHz. Conductive shields 6 may be biased at a DC potential appropriate to the type of photoconductor and its linear velocity with respect to the dicorotron device. As an example, the photoreceptor may be operated at a velocity of 10 inches per second with zero bias. For higher speeds, an increasingly negative bias is required. Exposure of the moving photoreceptor is made through the unshielded center section of the dicorotron device by means of an optical system represented by lens 7.