Electrophotographic receiver sheet pickup method and apparatus

Claim 2

The copying apparatus in accordance with claim 1 wherein said element comprises a metallic core, a thick layer of a generally pliable conducting material formed on and encircling said core and a thin layer of an electrically insulating material formed on and covering said pliable layer.

Claim 3

The copying apparatus in accordance with claim 1 wherein said platen means comprises at least a pair of tandemly arranged rollers, one of which effectively transfers said powder image to said receiver sheet and the other continuously strips said receiver sheet from said facing surface.

Claim 4

In an electrophotographic copying apparatus comprising an electrically conductive vacuum Member for engaging one surface of a sheet of photoconductive material and retaining said sheet thereon with with one edge of said sheet extending beyond the corresponding edge of said vacuum member, the other surface of said sheet bearing a powder image for transfer to a receiver sheet positioned in contact with said other surface, the improvement comprising: a rotatable roller having an electrically conductive core and a layer of insulating material encircling said core, said roller engaging said one edge and being movable relative to and in contact with said receiver sheet; a source of electrical potential connected between said vacuum member and said core for establishing an electrostatic field therebetween; and means for moving one of said vacuum member and said roller relative to the other during persistence of said field, whereby said powder image will be transferred to said receiver sheet and the latter will be stripped progressively from said sheet of photoconductive material.

Claim 5

In an electrophotographic copying apparatus comprising an electrically conductive vacuum member for engaging one surface of a sheet of photoconductive material and retaining said sheet thereon, the other surface of said sheet of photoconductive material bearing a powder image for transfer to a receiver sheet positioned in contact with said image bearing surface, the improvement comprising: a pair of tandemly arranged rollers, each of which comprises an electrically conductive core and a layer of electrically insulating material surrounding said core for urging said receiver sheet toward and into intimate contact with said image bearing surface; a source of potential connected between the core of each of said rollers and said vacuum member for establishing an electrostatic field therebetween; and means for rotating said rollers in synchronism during persistence of said fields, whereby said receiver sheet is attracted to one of said rollers for movement thereby and, at the same time, said powder image transfers to said receiver sheet at said other roller.

Claim 6

The copying apparatus in accordance with claim 6 wherein each of said first and second rollers comprises a metallic core, a thick layer of gelatin encircling said core, and a thin layer of an electrically insulating material formed on and covering said layer of gelatin.

Claim 7

In an electrophotographic copying apparatus comprising an electrically conductive and rotatable drum having a layer of photoconductive material on at least a portion of its peripheral surface, the facing surface of said layer bearing a powder image for transfer to a receiver sheet, the improvement comprising: a first roller having an electrically conductive core and an electrically insulating material surrounding said core and urged toward said drum for cooperating with said drum to move said receiver sheet therebetween and to hold it against said facing surface; a second roller arranged in tandem relationship to said first roller and having an electrically conductive core and an electrically insulating material surrounding said core, said second roller being urged toward and cooperating with said drum for engaging said receiver sheet to strip it from said facing surface with said image for movement in a designated path; a source of potential connected between the core of each of said rollers and said drum, at least during the time said receiver sheet is being moved by said rollers and drum, for establishing an electrostatic field of different strength between each of said rollers and said drum; and means for rotating said rollers in synchronism during persistence of said fields, whereby said first roller effects transfer of said powder image to said receiver sheet and said second roller effects sequential stripping of said receiver sheet with said powder image from said facing surface.