Light pipe for accurate erasure of photoconductor charge

Claim 1

An electrophotographic copier machine wherein a photoreceptive surface is charged to receive an image within an image area of specified size, comprising: means upon which said photoreceptive surface is mounted for moving said surface in a continuous path; charge-generating means located along said path for producing a relatively uniform electrostatic charge on said surface; exposing means for directing light rays from an object to said surface to produce a variable discharge of said image area such that said image area is caused to bear an electrostatic image of said object; developing means to develop said electrostatic image by depositing developing material on said surface; transfer means to transfer the developed image to a copy-receiving medium; cleaning means to clean said surface of excess developing material to prepare said surface for producing a subsequent copy; first charge erase means located along said path between said charge-generating means and said developing means for removing charge on said surface between image areas, said first means comprising an array of light-emitting diodes; second charge erase means also located along said path between said charge-generating means and said developing means for removing charge along the edges of said surface outside said image area, said second means comprising an array of light-emitting diodes; and light channel means comprising a plurality of sheets of transparent material located between said array of light-emitting diodes (LED) and said surface, for allowing light rays to propagate freely in a first direction parallel to said surface from LED to LED within each one of said plurality of sheets, said sheets separated from each other by an air space to divide said array into groups of LEDs, said sheets having sides essentially normal to said surface so as to contain said light rays between said sides in a second direction normal to said first direction.