Corona charger configuration

Claim 2

In an electrostatic copying machine having an exposure system for subjecting the surface of a photoconductor to an image of an original to be reproduced over a generally rectangular illuminated area, the light intensity of which falls off at the edges and corners of said area and having means for positioning the photoconductive surface adjacent to a charging station, charging apparatus comprising means at said charging station for producing a generally rectangular corona discharge field pattern, and means for so modifying said field pattern adjacent to the periphery thereof as to compensate for said fall off in light intensity over said illuminated area to cause said machine to produce a copy having contrast throughout corresponding to the contrast in the original.

Claim 3

Apparatus as in claim 1 in which said modifying means reduces the effect of said field adjacent to said periphery.

Claim 4

Apparatus as in claim 2 in which said modifying means is a conductive plate formed with an opening therein and means mounting said plate between said field pattern producing means and a surface positioned adjacent to said charging station.

Claim 5

Apparatus as in claim 3 in which said opening has a generally oval configuration.

Claim 6

Apparatus as in claim 4 in which said surface moves relative to said charging apparatus and in which the major axis of said opening extends at right angles to the direction of relative movement between said surface and said apparatus.

Claim 7

Apparatus as in claim 1 in which said field producing means comprises a plurality of corona wires, means mounting said wires in spaced parallel relationship and respective grounded conductive plates disposed in the spaces between said wires.

Claim 8

Apparatus as in claim 6 in which the upper edges of said plates are slightly below said corona wires.

Claim 9

Apparatus as in claim 7 in which said photoconductive surface moves relative to said discharge station and in which said wires and said plates are disposed generally perpendicularly to the direction of relative movement between said surface and said station.

Claim 10

Apparatus as in claim 8 in which the upper edges of said plates are about one-sixteenth of an inch below said wires.

Claim 11

In an electrostatic copying machine having an exposure system for subjecting the surface of a photoconductor to an image of an original to be reproduced over a generally rectangular illuminated area, the light intensity of which falls off at the edges and corners of said area and having means for moving the photoconductive surface along a path past a charging station, charging apparatus comprising a plurality of corona wires adapted to be energized to produce a charging field, means mounting said wires in spaced relationship at said charging station with the lengths thereof extending across said path, field distributing plates disposed in the spaces between said wires, said plates having upper edges spaced slightly below said wires, a field shaping plate Means having a generally centrally located opening therein for modifying said field adjacent to the periphery thereof so as to compensate for said fall off in light intensity to cause said machine to produce a copy having contrast throughout corresponding to the contrast of the original, and means mounting said plate between said wires and said path.

Claim 12

In an electrostatic copying machine having an exposure system for subjecting the surface of a photoconductor to an image of an original to be reproduced over a generally rectangular illuminated area, the light intensity of which falls off at the edges and corners of said area and having means for moving the photoconductive surface along a path past a charging station, charging apparatus comprising a plurality of corona wires adapted to be energized to produce a charging field, means mounting said wires in spaced relationship at said charging station with the lengths thereof extending across said path, field distributing plates disposed in the spaces between said wires, said plates having upper edges spaced slightly below said wires, a field shaping plate Means having a generally centrally located opening therein for modifying said field adjacent to the periphery thereof so as to compensate for said fall off in light intensity to cause said machine to produce a copy having contrast throughout corresponding to the contrast of the original, and means mounting said plate between said wires and said path.

Claim 13

Apparatus as in claim 10 in which said opening is generally oval and in which the major axis thereof is generally perpendicular to the path.