Lift off electrode

Claim 2

In an electrostatographic reproducing device including a reproducing surface having a photoconductive layer supported upon a substrate, means for applying an electric field across said layer, comprising first and second electrodes arranged on either side of said layer, one of said electrodes being a roller electrode having a defined circumference and applying said field across said layer by continuously contacting said layer over a major portion of a predetermined arc portion of said roller circumference, potential means for providing said roller electrode with a graded potential over said predetermined arc portion of said roller circumference said graded potential having the characteristic of potential levels relative to said surface at points proximate air gaps formed at the point of initial and final contact of said predetermined arc position of said roller circumference with said reproducing surface, said potential levels insufficient to cause electrical breakdown over said air gaps, and high potential levels intermediate said points over the area of contact between said arc position and said surface.

Claim 3

The combination of claim 1 wherein said roller includes a plurality of conductive elements distributed about the circumference of said roller, a plurality of sliding contacts each adapted to be conductively coupled to a conductive element positioned in contact therewith, said sliding contacts fixedly mounted within said roller, said potential means supplying said potential levels over the plurality of sliding contacts, said sliding contacts defining an area corresponding to said predetermined arc portion.

Claim 4

The combination of claim 2 wherein said roller includes an inner layer including said conductive elements and a pressure deformable outer layer urged into contact with said reproducing surface layer with sufficient pressure to provide a substantially flat contact between said outer layer and said reproducing surface and to reduce the distance between said conductive elements and said reproducing surface.

Claim 5

In an electrostatographic reproducing device including a reproducing surface having a photoconductive layer supported on a substrate, means for applying an electric field across said layer, comprising first and second electrodes arranged on either side of said layer, one of said elEctrodes being at least partially transparent, said first electrode being a roller electrode having a defined circumference and applying said field across said layer by continually contacting said layer over a major portion of a predetermined arc portion of said roller circumference, potential means for providing said roller electrode with a potential over said predetermined arc portion of said roller circumference, said potential means providing a plurality of potential levels, means applying each of said potential levels to separated portions of said predetermined arc portion of said roller circumference to form a graded potential over said predetermined arc portion, said graded potential having the characteristic of low potential levels relative to said surface at points proximate air gaps formed at the point of initial and final contact of said predetermined arc position of said roller circumference with said reproducing surface, said potential levels insufficient to cause electrical breakdown over said air gaps, and high potential levels intermediate said points over the area of contact between said arc position and said surface, and means for exposing said layer portion during said contact to a source of illumination through said transparent electrode.

Claim 6

In an electrostatographic reproducing device including a reproducing surface having a photoconductive layer supported on a substrate, means for applying an electric field across said layer, comprising first and second electrodes arranged on either side of said layer, one of said elEctrodes being at least partially transparent, said first electrode being a roller electrode having a defined circumference and applying said field across said layer by continually contacting said layer over a major portion of a predetermined arc portion of said roller circumference, potential means for providing said roller electrode with a potential over said predetermined arc portion of said roller circumference, said potential means providing a plurality of potential levels, means applying each of said potential levels to separated portions of said predetermined arc portion of said roller circumference to form a graded potential over said predetermined arc portion, said graded potential having the characteristic of low potential levels relative to said surface at points proximate air gaps formed at the point of initial and final contact of said predetermined arc position of said roller circumference with said reproducing surface, said potential levels insufficient to cause electrical breakdown over said air gaps, and high potential levels intermediate said points over the area of contact between said arc position and said surface, and means for exposing said layer portion during said contact to a source of illumination through said transparent electrode.

Claim 7

The combination of claim 4 wherein said second electrode comprises said substrate in a drum shape, said layer coating the exterior of said drum, said drum circumference including a charging station, exposure station, development station, transfer station, and cleaning station, said first electrode contacting said layer at said charging station.

Claim 8

The combination of claim 4 wherein said roller includes a plurality of conductive elements distributed about the circumference of said roller, a plurality of sliding contacts each adapted to be conductively coupled to a conductive element positioned in contact therewith, said sliding contacts fixedly mounted within said roller, said potential means supplying said potential levels over the plurality of sliding contacts, said sliding contacts defining an area corresponding to said predetermined arc portion.

Claim 9

The combination of claim 4 wherein said roller includes an inner layer including said conductive elements and pressure deformable outer layer urged into contact with said reproducing surface layer with sufficient pressure to provide a substantially flat contact between said outer layer and said reproducing surface and to reduce the distance between said conductive elements and said reproducing surface.

Claim 10

In an electrostatographic reproducing device including a reproducing surface having a layer of finely divided electrically photosensitive particles dispersed in a substantially insulating liquid carrier supported upon a substrate, means for applying an electric field across said layer, comprising first and second electrodes arranged on either side of said layer, one of said electrodes being at least partially transparent, said first electrode being a roller electrode having a defined circumference and applying said field across said layer by continually contacting said layer over a major portion of a predetermined arc portion of said roller circumference, potential means for providing said roller electrode with a potential over said predetermined arc portion of said roller circumference, said potential means providing a plurality of potential levels, means applying each of said potential levels to separated portions of said predetermined arc portion of said roller circumference to form a graded potential over said predetermined arc portion, said graded potential having the characteristic of low potential levels relative to said surface at points proximate air gaps formed at the point of initial and final contact of said predetermined arc position of said roller circumference with said reproducing surface, said potential levels insufficient to cause electrical breakdown over said air gaps, and high potential levels intermediate said points over the area of contact bEtween said arc position and said surface, and means for exposing said layer portion during said contact to a source of illumination in image configuration through said transparent electrode, whereby an image is formed.

Claim 11

In an electrostatographic reproducing device including a reproducing surface having a layer of finely divided electrically photosensitive particles dispersed in a substantially insulating liquid carrier supported upon a substrate, means for applying an electric field across said layer, comprising first and second electrodes arranged on either side of said layer, one of said electrodes being at least partially transparent, said first electrode being a roller electrode having a defined circumference and applying said field across said layer by continually contacting said layer over a major portion of a predetermined arc portion of said roller circumference, potential means for providing said roller electrode with a potential over said predetermined arc portion of said roller circumference, said potential means providing a plurality of potential levels, means applying each of said potential levels to separated portions of said predetermined arc portion of said roller circumference to form a graded potential over said predetermined arc portion, said graded potential having the characteristic of low potential levels relative to said surface at points proximate air gaps formed at the point of initial and final contact of said predetermined arc position of said roller circumference with said reproducing surface, said potential levels insufficient to cause electrical breakdown over said air gaps, and high potential levels intermediate said points over the area of contact bEtween said arc position and said surface, and means for exposing said layer portion during said contact to a source of illumination in image configuration through said transparent electrode, whereby an image is formed.

Claim 12

The combination of claim 8 wherein said source of illumination is a light source positioned opposite said substrate, said substrate is formed of a transparent material, and said exposure means includes means for projecting an image to be reproduced toward said transparent substrate, for exposing said photosensitive particles to said image.

Claim 13

The combination of claim 9 wherein said roller includes a plurality of conductive elements distributed about the circumference of said roller, a plurality of sliding contacts each adapted to be conductively coupled to a conductive element positioned in contact therewith, said sliding contacts fixedly mounted within said roller, said potential means supplying said potential levels over the plurality of sliding contacts, said sliding contacts defining an area corresponding to said predetermined arc portion.

Claim 14

The combination of claim 10 wherein said roller includes an inner layer including said conductive elements and a pressure deformable outer layer urged into contact with said reproducing surface layer with sufficient pressure to provide a substantially flat contact between said outer layer and said reproducing surface and to reduce the distance between said conductive elements and said reproducing surface.