US 5,314,793 AGranted

Multicolor photographic elements exhibiting an enhanced speed-granularity relationship

AssigneeEastman Kodak Company

InventorsElizabeth P. Chang, James A. Friday

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Abstract

Multicolor photographic elements are disclosed containing at least three dye image forming layer units. An enhancement of the speed-granularity relationship of a dye image is obtained when the corresponding dye image forming layer unit contains at least three superimposed emulsion layers. The two emulsion layers farther from the support contain silver bromoiodide emulsions, with the emulsion layer nearest the support containing a silver bromide or bromoiodide emulsion of up to 60 percent the iodide as a proportion of silver of the next overlying of the emulsion layers. The three emulsion layers each differ in speed from the next adjacent of the emulsion layers, with the fastest of the emulsion layers being located nearest the source of exposing radiation and being at least one half stop faster than the next adjacent layer and the slowest of the emulsion layers being located farthest from the source of exposing radiation and being at least one stop slower than the next adjacent layer. The three emulsions layers are each tabular grain emulsion layers with tabularities of greater than 25. At least the two emulsion layers nearest the source of exposing radiation tabular grains that contain a speed enhancing locally increased iodide content.

Claims12

Dependent claims

A multicolor photographic element comprised of a support and at least three dye image forming layer units each containing an image dye or dye precursor capable of forming a dye image of a different hue,

characterized in that at least one of the dye image forming layer units capable of forming a visible dye image contains at least three superimposed radiation sensitive emulsion layers in which
a first emulsion layer located farthest from the support of the three emulsion layers contains silver bromoiodide grains of from 1 to 20 mole percent iodide, based on silver,
a second emulsion layer at least one half stop slower in speed than the first emulsion layer is located between the first emulsion layer and the support and contains silver bromoiodide grains of from 1 to 20 mole percent iodide, and
a third emulsion layer at least at least one stop slower in speed than the second emulsion layer is located between the second emulsion layer and the support and contains silver bromide or bromoiodide grains of up to 60 percent the average iodide content of the second emulsion layer,
greater than 50 percent of the total projected area of the grains of each of the first, second and third emulsion layers being accounted for by tabular grains having a thickness of less than 0.3 .mu.m and average tabularity of greater than 25, tabularity (T) being defined as
T=ECD/t.sup.2
where
ECD is the average equivalent circular diameter of the tabular grains in .mu.m and
t is the average thickness in .mu.m of the tabular grains,
tabular grains of at least the first and second emulsion layers containing a non-uniform iodide distribution, the tabular grains being comprised of a central portion and a laterally offset higher iodide portion, the tabular grains being capable of producing, when exposed to 325 nm electromagnetic radiation of 6.degree. K., a stimulated fluorescent emission at 575 nm that is at least one third the intensity of an identically stimulated fluorescent emission maximum within the wavelength range of from 490 to 560 nm, and
the tabular grains of the third emulsion layer contain less than 20 percent of the iodide content of tabular grains of the second emulsion layer.

8 more elements

A multicolor photographic element comprised of a support, a yellow dye image forming blue recording layer unit, a magenta dye image forming green recording layer unit, and a cyan dye image forming red recording layer unit,

characterized in that the magenta dye image forming green recording layer unit contains at least three superimposed magenta dye forming coupler containing green sensitized emulsion layers in which
a first emulsion layer located farthest from the support of the three emulsion layers contains silver bromoiodide grains of from 3 to 20 mole percent iodide, based on silver,
a second emulsion layer from one to two stops slower in speed than the first emulsion layer is located between the first emulsion layer and the support and contains silver bromoiodide grains of from 3 to 20 mole percent iodide, and
a third emulsion layer form one and one half to three stops slower in speed than the second emulsion layer is located between the second emulsion layer and the support and contains silver bromide or silver bromoiodide grains of less than 20 percent the average iodide content of the second emulsion layer,
greater than 70 percent of the total projected area of the grains of each of the first, second and third emulsion layers being accounted for by tabular grains having a thickness of less than 0.3 .mu.m and average tabularity of greater than 25, tabularity (T) being defined as
T=ECD/t.sup.2
where
ECD is the average equivalent circular diameter of the tabular grains in .mu.m and
t is the average thickness in .mu.m of the tabular grains, and
tabular grains of at least the first and second emulsion layers containing a non-uniform iodide distribution, the tabular grains being comprised of a central portion and a laterally offset higher iodide portion, the tabular grains being capable of producing, when exposed to 325 nm electromagnetic radiation at 6.degree. K., a stimulated fluorescent emission at 575 nm that is at least one third the intensity of an identically stimulated fluorescent emission maximum within the wavelength range of from 490 to 560 nm

7 more elements

Dependencies are inferred from the claim text.