Silver halide photographic emulsion
AssigneeKonica Corporation
InventorTomoyuki Nakayama
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Abstract
A silver halide photographic emulsion is disclosed, comprising silver halide grains containing a heavy metal ion and reduction sensitization nucleus within the grains, the grains having an overall average iodide content (I.sub.2) of 2 to 30 mol % and satisfying the following requirement, I.sub.1 <I.sub.2 where I.sub.1 represents an iodide content of an outermost surface layer of the grains.
Claims17
A silver halide photographic emulsion comprising silver halide grains containing a metal ion and reduction sensitization nucleus in an internal portion of the grains,
- said grains having an average iodide content (I.sub.2) of 2 to 30 mol % and satisfying the following requirement,
- I.sub.1 <I.sub.2
- wherein I.sub.1 represents an average iodide content of an outermost surface layer of the grains;
- and
- said metal ion is selected from the group consisting of In.sup.3+ and Pb.sup.2+.
A method of preparing a silver halide emulsion comprising the steps of:
- (i) forming silver halide grains by adding into a reaction vessel a water-soluble silver salt and water-soluble halide salt, or silver halide fine grains to form an emulsion and
- (ii) subjecting the emulsion formed to desalting to remove soluble salts,
- wherein, in the step of (i), a metal ion is introduced and the emulsion is reduction-sensitized by ripening the emulsion in the presence of a reducing agent or at a pH of 7.0 or more or pAg of 7.0 or less before 97% of the ultimate grain volume of said silver halide grains is reached, said silver halide grains having an average iodide content (I.sub.2) of 2 to 30 mol % and satisfying the following requirement,
- I.sub.1 <I.sub.2
- wherein I.sub.1 represents an average iodide content of an outermost surface layer of the grains;
- and said metal ion is selected from the group consisting of Pb.sup.2+ and In.sup.3+.
Dependencies are inferred from the claim text.