Apparatus and method for selectively discharging the photoconductive surface of an electrostatic drum copier to facilitate the cleaning thereof

Claim 2

In a copying machine comprising a charging device, an exposure device, a development device, a transferring device for transferring the developed image to a transfer medium, a cleaning device and a discharging device disposed around a photoconductive drum in the foregoing order, the improvement comprising means for introducing a discharging light onto the photoconductive drum between the charging device and the development device, and shutter means for intercepting the discharging light for a length of time corresponding to the length of the transfer medium only after the transfer medium enters the body of the copying machine.

Claim 3

In a repetitive copying process used in a copying machine comprising the steps of charging a photoconductive member, posing the charged photoconductive member to an image to be copied to form a latent image, developing the latent image with a developer, transferring the developed image to a transfer medium, and cleaning the photoconductive member of residual developer and charge for the next cycle, the improvement comprising: continuously removing the charge placed on said photoconductive member during said charging step and interrupting the continuous charge removal only after a said transfer medium has entered the body of the copying machine, the length of said interruption being approximately the length of time required for said developed image to be transferred to said transfer medium during said transfer step whereby the latent image may be formed on said photoconductive member during said interruption so that said developer is placed on said photoconductive member only for a length of time approximately as long as the interruption, whereby developer is not placed on said photoconductive member whenever it is not necessary to transfer developer to the transfer medium so that residual developer on said photoconductive member is substantially removed during said cleaning step to thereby clean the photoconductive member for the next cycle of copying.

Claim 4

In a repetitive copying process used in a copying machine comprising the steps of charging a photoconductive member, posing the charged photoconductive member to an image to be copied to form a latent image, developing the latent image with a developer, transferring the developed image to a transfer medium, and cleaning the photoconductive member of residual developer and charge for the next cycle, the improvement comprising: continuously removing the charge placed on said photoconductive member during said charging step and interrupting the continuous charge removal only after a said transfer medium has entered the body of the copying machine, the length of said interruption being approximately the length of time required for said developed image to be transferred to said transfer medium during said transfer step whereby the latent image may be formed on said photoconductive member during said interruption so that said developer is placed on said photoconductive member only for a length of time approximately as long as the interruption, whereby developer is not placed on said photoconductive member whenever it is not necessary to transfer developer to the transfer medium so that residual developer on said photoconductive member is substantially removed during said cleaning step to thereby clean the photoconductive member for the next cycle of copying.

Claim 5

The improvement as in claim 2 where said charge is continuously removed by exposing said photoconductive member to light from a discharge lamp.

Claim 6

The improvement as in claim 2 where a discharge lamp is used in said cleaning step to remove said residual charge and where a portion of the light from said discharge means is used to effect said continuous charge removal.

Claim 7

The impovement as in claim 2, the length of said interrupting step is effected by sensing the length of time it takes for said transfer medium to pass a first predetermined point after it has entered the body of said copying machine.

Claim 8

The improvement as in claim 5 where said interrupting step is delayed a predetermined length of time by sensing the length of time it takes for said transfer medium to reach a second predetermined point subsequent to said first predetermined point.