Direct positive type silver halide photosensitive material
AssigneeFuji Photo Film Co., Ltd.
InventorsTerumi Matsuda, Shoji Ishiguro, Shigenori Moriuchi, Yoshiaki Suzuki
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Abstract
A high contrast, chemically fogged direct positive type silver halide photosensitive material is described containing at least one ammine complex salt selected from those including cobalt, nickel, ruthenium or chromium, by which the contrast in the lower optical density region is improved while retaining superior Dmax and sensitivity.
Claims17
A direct positive type silver halide photosensitive material for obtaining a high contrast image in the highlight portions thereof, said image comprised substantially of only silver prepared by:
- (a) chemically fogging silver halide grains, and
- (b) subsequent to said fogging, adding at least one metal ammine complex salt in an amount of 10.sup.-5 to 10.sup.-2 mol per mol of silver wherein the metal component is selected from the group consisting of cobalt, nickel, ruthenium and chromium.
A process for preparing a direct positive type silver halide emulsion for obtaining a high contrast image in the highlight portions thereof, said image comprised substantially of only silver comprising:
- (1) chemically fogging silver halide grains containing at least 40 mol% silver chloride;
- (2) adsorbing a sensitizing organic dye onto the surfaces of the chemically fogged grains;
- and
- (3) subsequent to said fogging step, adding at least one member selected from the group consisting of metal ammine complex salts of cobalt, nickel, ruthenium and chromium in an amount of 10.sup.-5 to 10.sup.-2 mol per mole of silver halide.
A process for forming a silver image of high contrast in the highlight portions thereof, comprising:
- preparing a high contrast, chemically fogged direct positive type silver halide photosensitive material by chemically fogging silver halide grains and subsequent to said fogging, adding at least one metal ammine complex salt in an amount of 10.sup.-5 to 10.sup.-2 mol per mol of silver selected from the group consisting of cobalt, nickel, lithium, and chromium;
- and
- imagewise exposing said high contrast, chemically fogged direct positive type silver halide photosensitive material;
- and
- developing said material to form a silver image said image being comprised substantially of only silver.
Dependencies are inferred from the claim text.