Sheet stripping from imaging surface

Claim 2

In an electrostatographic copying apparatus, wherein an image is transferred from an imaging surface means to a copy sheet which is placed in intimate contact with said imaging surface means and moved together with said imaging surface means in a given movement direction at a transfer station, and wherein the copy sheet is then stripped from said imaging surface means at a sripping area, the improvement wherein: said imaging surface means has a first curvature in said movement direction at said stripping area for said stripping of said copy sheet from said imaging surface means, and wherein said imaging surface means has a second curvature at said stripping area transverse said movement direction and transverse said first curvature forming a slight crown height to said imaging surface means and to said copy sheet thereon transverse said movement direction for substantially increasing the reliability of said stripping of said copy sheet from said imaging surface means.

Claim 3

The apparatus of claim 1, wherein said imaging surface means is substantially cylindrical to provide said first curvature of said imaging surface means, and wherein said second curvature is provided by a slight smooth crown on said cylindrical surface.

Claim 4

The apparatus of claim 1, wherein said imaging surface means is a slightly convex cylinder.

Claim 5

The apparatus of claim 2, wherein said imaging surface means is a slightly convex cylinder.

Claim 6

The apparatus of claim 1, wherein said imaging surface means comprises a flexible belt and wherein said first and second curvatures are both provided by running said belt over a supporting roller at said transfer station, wherein said supporting roller has a generally cylindrical surface configuration but with a smooth slightly crowned non-cylindrical curvature therein, and wherein said belt conforms to said crowned configuration of said supporting roller.

Claim 7

The apparatus of claim 5, wherein said belt comprises a flexible photoreceptor.

Claim 8

The apparatus of claim 1, wherein said transfer station includes a biased transfer roller urged against said imaging surface, and wherein said biased transfer roller has a generally cylindrical configuration but with a slight non-cylindrical crown therein corresponding to, but opposite from, said second curvature in said imaging surface means to provide uniform conformation of said bias transfer roller surface to said imaging surface means at said transfer station.

Claim 9

The apparatus of claim 5, wherein said transfer station includes a biased transfer roller urged against said imaging surface, and wherein said biased transfer roller has a generally cylindrical configuration but with a slight non-cylindrical crown therein corresponding to, but opposite from, said second curvature in said imaging surface means to provide uniform conformation of said bias transfer roller surface to said imaging surface means at said transfer station.

Claim 10

The apparatus of claim 1, wherein said first curvature is circular and said second curvature is a single continuous curve curving smoothly across said imaging surface means, and said second curvature has a minimum curvature radii which is greater than the maximum curvature radii of said first curvature.

Claim 11

The apparatus of claim 1, wherein said second curvature has a maximum crown height of less than 1/100 of the transverse dimension of said imaging surface means.

Claim 12

The apparatus of claim 1, wherein said second curvature has a crown height of approximately 1/500th of the transverse dimension of said imaging surface means.

Claim 13

The apparatus of claim 2, wherein said second curvature has a maximum crown height of less than 1/100 of the transverse dimension of said imaging surface means.

Claim 14

The apparatus of claim 1, further including nonplanar sheet guide means for pre-forming a curve in said copy sheet corresponding to said second curvature prior to said copy sheet being placed in contact with said imaging surface.

Claim 15

In an electrostatographic copying apparatus, wherein an image is transferred from an imaging surface means to a copy sheet which is placed in intimate contact with said imaging surface means in a given movement direction at a transfer station, wherein said imaging surface means comprises a flexible photoreceptor belt, and wherein the copy sheet is then stripped from said imaging surface means at a stripping area where said photoreceptor belt is partially wrapped around a generally cylindrical supporting roller transverse said movement direction, the improvement wherein: said imaging surface means has a curvature in said movement direction at said stripping area for said stripping of said copy sheet from said imaging surface means provided by said partial wrapping of said photoreceptor belt around said generally cylindrical supporting roller; and wherein said supporting roller has a generally cylindrical outer surface with the radius of said outer surface varying along the axis of rotation of said supporting roller at said stripping area.

Claim 16

In an electrostatographic copying apparatus, wherein an image is transferred from an imaging surface means to a copy sheet which is placed in intimate contact with said imaging surface means in a given movement direction at a transfer station, wherein said imaging surface means comprises a flexible photoreceptor belt, and wherein the copy sheet is then stripped from said imaging surface means at a stripping area where said photoreceptor belt is partially wrapped around a generally cylindrical supporting roller transverse said movement direction, the improvement wherein: said imaging surface means has a curvature in said movement direction at said stripping area for said stripping of said copy sheet from said imaging surface means provided by said partial wrapping of said photoreceptor belt around said generally cylindrical supporting roller; and wherein said supporting roller has a generally cylindrical outer surface with the radius of said outer surface varying along the axis of rotation of said supporting roller at said stripping area.

Claim 17

In an electrostatographic copying method wherein an image is transferred from a moving flexible belt imaging surface to a copy sheet which is placed in intimate contact with said imaging surface and moved together with said imaging surface in a given movement direction, and wherein the copy sheet is then stripped from said imaging surface at a stripping area, the improvement comprising: curving said imaging surface at said stripping area with a first curvature in said movement direction for stripping the copy sheet from said imaging surface, and simultaneously curving said imaging surface with a second curvature, supperimposed on said first curvature, transverse said movement direction and transverse said first curvature for increasing the reliability of said stripping of the copy sheet from said imaging surface, wherein said first and second curvatures are both formed by partially wrapping said belt around a supporting roller at said stripping area.

Claim 18

In an electrostatographic copying method wherein an image is transferred from a moving flexible belt imaging surface to a copy sheet which is placed in intimate contact with said imaging surface and moved together with said imaging surface in a given movement direction, and wherein the copy sheet is then stripped from said imaging surface at a stripping area, the improvement comprising: curving said imaging surface at said stripping area with a first curvature in said movement direction for stripping the copy sheet from said imaging surface, and simultaneously curving said imaging surface with a second curvature, supperimposed on said first curvature, transverse said movement direction and transverse said first curvature for increasing the reliability of said stripping of the copy sheet from said imaging surface, wherein said first and second curvatures are both formed by partially wrapping said belt around a supporting roller at said stripping area.

Claim 19

The method of claim 15, wherein said first curvature is circular.

Claim 20

The method of claim 16, wherein said second curvature is a single continuous curve in said imaging surface having a minimum curvature radius which is greater than the maximum curvature radius of said first curvature.

Claim 21

The method of claim 15, further including curving a copy sheet with a curve corresponding to said second curvature prior to said copy sheet being placed in contact with said imaging surface.

Claim 22

In an electrostatographic copying method wherein an image is transferred from an imaging surface to a copy sheet which is placed in intimate contact with the imaging surface and moved together with the imaging surface in a given movement direction, and wherein the copy sheet is then stripped from the imaging surface at a stripping area after the image is transferred, the improvement comprising: curving said moving copy sheet at said stripping area with a first curvature in said movement direction for said stripping of said copy sheet from said imaging surface, and simultaneously curving said moving copy sheet with a slight second curvature, superimposed on said first curvature, transverse said movement direction and transverse said first curvature for increasing the reliability of said stripping of the copy sheet from said imaging surface.

Claim 23

In an electrostatographic copying method wherein an image is transferred from an imaging surface to a copy sheet which is placed in intimate contact with the imaging surface and moved together with the imaging surface in a given movement direction, and wherein the copy sheet is then stripped from the imaging surface at a stripping area after the image is transferred, the improvement comprising: curving said moving copy sheet at said stripping area with a first curvature in said movement direction for said stripping of said copy sheet from said imaging surface, and simultaneously curving said moving copy sheet with a slight second curvature, superimposed on said first curvature, transverse said movement direction and transverse said first curvature for increasing the reliability of said stripping of the copy sheet from said imaging surface.

Claim 24

The method of claim 19, wherein said first curvature of said copy sheet is produced by moving said copy sheet over a substantially cylindrical curve in said imaging surface at said stripping area, and wherein said second curvature is produced by said first curvature being curved slightly non-cylindrically.

Claim 25

The method of claim 19, wherein said copy sheet is curved in said second curvature to a crown height of less than 1/100 of the transverse dimensions of said imaging surface.