Corona discharge apparatus

Claim 2

A corona-discharge apparatus for applying a substantially uniform electrostatic charge to a grounded photoconductive surface, comprising frame means, a plurality of at least three thin corona discharge wires clamped in said frame means and disposed above and substantially parallel to said photoconductive surface, and a plurality of resistors, each resistor being connected at one end to one single high voltage and at the other end to a group of said wires, wherein said discharge wires are in sufficiently close proximity to one another to provide a substantially uniform electrostatic discharge over said photoconductive surface.

Claim 3

Apparatus as claimed in claim 1 in which said thin wires are arranged in a plurality of symmetrical groups, the wires of each group being electrically connected to each other, and wherein each of said groups of interconnected wires is connected, via its respective resistor, to the voltage.

Claim 4

Apparatus as claimed in claim 2, comprising n parallel wires, of which the first and the nth wires are interconnected to form a first symmetrical group of wires, the second and (n-1)th wires are interconnected to form a second symmetrical group of wires, and so forth each pair of wires being connected to its respective resistor.

Claim 5

Apparatus as claimed in claim 3, in which n is an odd number, and the central wire is connected to a separate resistor.

Claim 6

Apparatus as claimed in claim 3, wherein said voltage drop is from 0.5 to 2 of the value of the discharge voltage.

Claim 7

Apparatus as claimed in claim 5, wherein said voltage drop is from 1 to 1.5 of the value of the discharge voltage.

Claim 8

Apparatus as claimed in claim 2, wherein the wires are substantially parallel to each other, in which the two outermost wires are connected together to form a pair and wherein all the other discharge wires are connected together to form a group of wires, and the pair of wires and the group of wires are connected via respective resistors to the voltage.

Claim 9

Apparatus as claimed in claim 2, wherein the resistors are all of the same value.

Claim 10

Apparatus as claimed in claim 1 comprising at least one group of thin wires connected together, which group is connected through a single resistor to the voltage and wherein the resistance value of said single resistor is equlvalent to that of the parallel combination it replaces if the wires in said group were not connected together.

Claim 11

Apparatus as claimed in claim 1, wherein the value of the resistors is such that the voltage drop across the resistors is at least 0.5 of the discharge voltage from said discharge element.

Claim 12

Apparatus as claimed in claim 1, wherein the value of the resistors are such that in operation of the apparatus the voltage drop across the resistors are of the same order of magnitude as the discharge voltage from said discharge elements.

Claim 13

Apparatus as claimed in claim 11, wherein said voltage drop across each resistor is from about 5,000 to about 10,000 volts.

Claim 14

Apparatus as claimed in claim 12, wherein said voltage drop is approximately 6,000 volts.

Claim 15

In a xerographic copying machine the combination comprising: a grounded photoconductive element and, in operative relation therewith, ii. a charging station for applying a substantially uniform electrostatic charge to the photoconductive element, said charging station comprising frame means and a plurality of at least three thin corona discharge wires clamped in said frame means, wherein said discharge wires are in sufficiently close proximity to one another to provide a substantiaLly uniform electrostatic discharge over said photoconductive surface, iii. an imaging station generating a latent charge image on the photoconductive element, iv. a developing station producing an image, v. a transfer station for transferring the image to a receiving material, the improvement comprising, in said charging station (ii), a plurality of resistors, each resistor being connected at one end to one single high voltage and at the other end to a group of said wires.

Claim 16

In a xerographic copying machine the combination comprising: a grounded photoconductive element and, in operative relation therewith, ii. a charging station for applying a substantially uniform electrostatic charge to the photoconductive element, said charging station comprising frame means and a plurality of at least three thin corona discharge wires clamped in said frame means, wherein said discharge wires are in sufficiently close proximity to one another to provide a substantiaLly uniform electrostatic discharge over said photoconductive surface, iii. an imaging station generating a latent charge image on the photoconductive element, iv. a developing station producing an image, v. a transfer station for transferring the image to a receiving material, the improvement comprising, in said charging station (ii), a plurality of resistors, each resistor being connected at one end to one single high voltage and at the other end to a group of said wires.

Claim 17

A corona-discharge apparatus for applying a substantially uniform electrostatic charge to a grounded photoconductive surface, comprising frame means, a plurality of at least three thin corona discharge wires clamped in said frame means and disposed above and substantially parallel to said photoconductive surface, and a plurality of resistors, each resistor being connected at one end to one single high voltage and at the other end to one of said wires, wherein said discharge wires are in sufficiently close proximity to one another to provide a substantially uniform electrostatic discharge over said photoconductive surface.

Claim 18

A corona-discharge apparatus for applying a substantially uniform electrostatic charge to a grounded photoconductive surface, comprising frame means, a plurality of at least three thin corona discharge wires clamped in said frame means and disposed above and substantially parallel to said photoconductive surface, and a plurality of resistors, each resistor being connected at one end to one single high voltage and at the other end to one of said wires, wherein said discharge wires are in sufficiently close proximity to one another to provide a substantially uniform electrostatic discharge over said photoconductive surface.

Claim 19

Apparatus as claimed in claim 15, wherein the value of the resistors are such that in operation of the apparatus the voltage drop across the resistors are of the same order of magnitude as the discharge voltage from said discharge elements.

Claim 20

Apparatus as claimed in claim 16, wherein said voltage drop across each resistor is from about 5,000 to about 10,000 volts.

Claim 21

Apparatus as claimed in claim 17, wherein said voltage drop is approximately 6,000 volts.

Claim 22

Apparatus as claimed in claim 15, wherein the value of the resistors is such that the voltage drop across the resistors is at least 0.5 of the discharge voltage from said discharge element.

Claim 23

In a xerographic copying machine the combination comprising: i. a grounded photoconductive element and, in operative relation therewith, ii. a charging station for applying a substantially uniform electrostatic charge to the photoconductive element, said charging station comprising frame means and a plurality of at least three thin corona discharge wires clamped in said frame means, wherein said discharge wires are in sufficiently close proximity to one another to provide a substantially uniform electrostatic discharge over said photoconductive surface. iii. an imaging station generating a latent charge image on the photoconductive element, iv. a developing station producing an image, v. a transfer station for transferring the image to a receiving material, the improvement comprising, in said charging station (ii), a plurality of resistors, each resistor being connected at one end to one single high voltage and at the other end to one of said wires.

Claim 24

In a xerographic copying machine the combination comprising: i. a grounded photoconductive element and, in operative relation therewith, ii. a charging station for applying a substantially uniform electrostatic charge to the photoconductive element, said charging station comprising frame means and a plurality of at least three thin corona discharge wires clamped in said frame means, wherein said discharge wires are in sufficiently close proximity to one another to provide a substantially uniform electrostatic discharge over said photoconductive surface. iii. an imaging station generating a latent charge image on the photoconductive element, iv. a developing station producing an image, v. a transfer station for transferring the image to a receiving material, the improvement comprising, in said charging station (ii), a plurality of resistors, each resistor being connected at one end to one single high voltage and at the other end to one of said wires.