Konishiroku Photo Industry Co., Ltd.

Konica Corporation

Atsushi Kamitakahara

Keiji Ogi

Eiichi Sakamoto

Yasuo Tosaka

Toshiaki Takahashi

Noboru Itoh

Nariko Isozaki

A light-sensitive silver halide direct-positive photographic material which comprises a support and, provided thereon a light-sensitive direct-positive silver halide emulsion layer containing silver halide grains having an internal latent image and a core-shell structure comprising a core and at least one shell stratum either partly or entirely covering said core, the outermost stratum of said shell having been formed in the presence of a nitrogen-containing heterocyclic compound having a mercapto group therein.

Direct positive silver halide light-sensitive photographic material

In a light-sensitive direct posi silver halide color photographic material having photographic constituent layers comprising at least one silver halide emulsion layer containing latent image type silver halide grains not previously fogged, which is capable of giving a direct posi image by subjecting the whole surface to exposure or effecting surface development in the presence of a fogging agent, after image exposure, the improvement wherein said internal latent image type silver halide grains are composed of at least two groups of internal latent image type silver halide grains having average grain sizes different from each other, and at least one compound capable of releasing a development inhibiting substance or its precursor through the reaction with the oxidized product of a color developing agent is contained in at least one layer of said photographic constituent layers. According to the present invention, there can be obtained a direct posi color photographic material improved in processing stability, having smooth gradation and excellent image quality, in which the respective photographic performances of at least two groups of internal latent type silver halide grains having grains sizes different from each other are fully utilized.

Photographic material with two size population of silver halide grains

Disclosed is a method for preparing a light-sensitive cuprous halide emulsion which comprises reducing cupric ions by an ascorbic acid derivative represented by the general formula: ##STR1## wherein R is a hydrogen atom or a hydroxyl group, and n is an integer of 1 to 4, provided that R is a hydroxyl group when n is 1, or its alkali metal salt, in the presence of halogen ions.

Method for preparing a light-sensitive cuprous halide emulsion

Growing community of inventors

Hino, Japan

Atsushi Kamitakahara