Method for reducing short time-scale reciprocity failure effects of a microencapsulated acrylate system

Claim 1

A method for reducing short time-scale reciprocity failure effects of a photosensitive imaging sheet, wherein: said photosensitive imaging sheet comprises a substrate having a layer of microcapsules coated on one surface thereof, said microcapsules having an outer phase transmissive to exposure light containing an internal phase of an acrylate monomer, photoinitiator, and color former; said imaging sheet obeying reciprocity within a range of exposure times t having a lower limit of about 10 -2 seconds, such that the required exposure energy for a given exposure density is a constant value E c such that tI=E c , and wherein said imaging sheet exhibits short time-scale reciprocity failure below said range such that tI>E c whereby greater energy E' is required to expose said image sheet at exposure times below said range than within said range; the method comprising the steps of: image-wise exposing a portion of said microcapsules of said imaging sheet for a time period t 1 to exposure light of an intensity I; following exposure, providing a recovery period of a time t r1 for said exposed microcapsules; image-wise exposing a portion of said microcapsules of said imaging sheet for a time period t 2 to exposure light of an intensity I; following exposure, providing a recovery period of a time t r2 for said exposed microcapsules; and repeating said exposure and recovery steps n times to form a latent image; said time periods t 1 , t 2 , . . . t n being selected such that E'>(t 1 +t 2 + . . . +t n )I≧E c , and such that (t 1 +t 2 + . . . +t n ) is less than about 10 -2 seconds.

Claim 2

A method for reducing short time-scale reciprocity failure effects of a photosensitive imaging sheet, wherein: said photosensitive imaging sheet comprises a substrate having a layer of microcapsules coated on one surface thereof, said microcapsules having an outer phase transmissive to exposure light containing an internal phase of an acrylate monomer, photoinitiator, and color former; said imaging sheet obeying reciprocity within a range of exposure times t having a lower limit of about 10 -2 seconds, such that the required exposure energy for a given exposure density is a constant value E c such that tI=E c , and wherein said imaging sheet exhibits short time-scale reciprocity failure below said range such that tI>E c whereby greater energy E' is required to expose said image sheet at exposure times below said range than within said range; the method comprising the steps of: image-wise exposing a portion of said microcapsules of said imaging sheet for a time period t 1 to exposure light of an intensity I; following exposure, providing a recovery period of a time t r1 for said exposed microcapsules; image-wise exposing a portion of said microcapsules of said imaging sheet for a time period t 2 to exposure light of an intensity I; following exposure, providing a recovery period of a time t r2 for said exposed microcapsules; and repeating said exposure and recovery steps n times to form a latent image; said time periods t 1 , t 2 , . . . t n being selected such that E'>(t 1 +t 2 + . . . +t n )I≧E c , and such that (t 1 +t 2 + . . . +t n ) is less than about 10 -2 seconds.

Claim 12

A method for reducing short time-scale reciprocity failure effects of a photosensitive imaging sheet, wherein: said photosensitive imaging sheet comprises a substrate having a layer of microcapsules coated on one surface thereof, said microcapsules having an outer phase transmissive to exposure light containing an internal phase of an acrylate monomer, photoinitiator, and color former; said imaging sheet obeying reciprocity within a range of exposure times t having a lower limit of about 10 -2 seconds, such that the required exposure energy for a given exposure density is a constant value E c such that tI=E c , and wherein said imaging sheet exhibits short time-scale reciprocity failure below said range such that tI>E c whereby greater energy E' is required to expose said image sheet at exposure times below said range than within said range; the method comprising the steps of: (a) image-wise signalling at least one acousto-optic modulator wherein said acousto-optic modulators independently control one of three lasers wherein said lasers are blue, green and red; (b) exposing said microcapsules in the pixels of a scanline of said imaging sheet for a time period t 1 to exposure light from said lasers of an intensity I; (c) following exposure, providing a recovery period of a time t r1 for said exposed microcapsules; (d) exposing said microcapsules in said pixels of said scanline for a time period t 2 to exposure light from said lasers of an intensity I; (e) following exposure, providing a recovery period of a time t r2 for said exposed microcapsules; (f) repeating said exposure and recovery steps n times to form a latent image on said scanline; said time periods t 1 , t 2 , . . . t n being selected such that E'>(t 1 +t 2 + . . . +t n )I≧E c , and such that (t 1 +t 2 + . . . +t n ) is less than about 10 -2 seconds; (g) advancing said imaging sheet and repeating steps (b) through (f) to form a latent image on a next succeeding scanline; (h) repeating step (g) to completely expose said imaging sheet; and (i) applying pressure to said imaging sheet such that a full color image is formed.

Claim 13

A method for reducing short time-scale reciprocity failure effects of a photosensitive imaging sheet, wherein: said photosensitive imaging sheet comprises a substrate having a layer of microcapsules coated on one surface thereof, said microcapsules having an outer phase transmissive to exposure light containing an internal phase of an acrylate monomer, photoinitiator, and color former; said imaging sheet obeying reciprocity within a range of exposure times t having a lower limit of about 10 -2 seconds, such that the required exposure energy for a given exposure density is a constant value E c such that tI=E c , and wherein said imaging sheet exhibits short time-scale reciprocity failure below said range such that tI>E c whereby greater energy E' is required to expose said image sheet at exposure times below said range than within said range; the method comprising the steps of: (a) image-wise signalling at least one acousto-optic modulator wherein said acousto-optic modulators independently control one of three lasers wherein said lasers are blue, green and red; (b) exposing said microcapsules in the pixels of a scanline of said imaging sheet for a time period t 1 to exposure light from said lasers of an intensity I; (c) following exposure, providing a recovery period of a time t r1 for said exposed microcapsules; (d) exposing said microcapsules in said pixels of said scanline for a time period t 2 to exposure light from said lasers of an intensity I; (e) following exposure, providing a recovery period of a time t r2 for said exposed microcapsules; (f) repeating said exposure and recovery steps n times to form a latent image on said scanline; said time periods t 1 , t 2 , . . . t n being selected such that E'>(t 1 +t 2 + . . . +t n )I≧E c , and such that (t 1 +t 2 + . . . +t n ) is less than about 10 -2 seconds; (g) advancing said imaging sheet and repeating steps (b) through (f) to form a latent image on a next succeeding scanline; (h) repeating step (g) to completely expose said imaging sheet; and (i) applying pressure to said imaging sheet such that a full color image is formed.