Silver halide grain, silver halide emulsion and preparation method thereof
AssigneeKonica Corporation
InventorsNaoko Furusawa, Masako Kuramoto, Kazuyoshi Ichikawa, Haruhiko Masutomi
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Abstract
A silver halide grain is disclosed, having one or more chemical sensitization clusters, and a largest size of the clusters being not less than 1.2 nm and less than 4.0 nm in diameter. A silver halide emulsion containing silver halide grains, as above-described and a preparation method are also disclosed.
Claims7
A silver halide emulsion comprising silver halide grains, wherein at least 50% of the total number of the grains is accounted for by silver halide grains each having one or more chemical sensitization clusters, a largest size of the clusters being not less than 1.2 nm and less than 4.0 nm.
A method for preparing a silver halide emulsion comprising the steps of
- forming a silver halide grain emulsion by mixing an aqueous silver salt solution and aqueous halide solution, and
- chemically ripening the silver halide emulsion with a chemical sensitizer,
- wherein, in the step of chemical ripening, the rate of chemical ripening being so controlled that the following requirement is satisfied,
- 1.24.times.10.sup.2 .ltoreq..epsilon.1.53.times.10.sup.7
- wherein .epsilon. is a relative aggregation rate constant represented by the following equation,
- .epsilon.=N.multidot.k/(2.multidot.ks)
- wherein N is an addition amount of the chemical sensitizer in number per .mu.m.sup.2 of the grain surface;
- k is an aggregation rate constant in .mu.m.sup.2 /min.;
- and ks is a reaction rate constant of the chemical sensitizer in min..sup.-1.
Dependencies are inferred from the claim text.