Agfa-gevaert Ag

Agfa Gevaert Nv

Agfa-gevaert Aktiengesellscaft

Erik Moisar

Sieghart Klotzer

Willy Joseph Vanassche

Herman Alberik Pattyn

Harald Von Rintelen

Otto Lapp

Manfred Becker

Erwin Ranz

Bruno Mucke

Angela Slabik

Friedrich Granzer

Erhard Palm

Detlev Von Bock

Surface-sensitized silver halide grains having a core/shell structure show improved properties.

Photographic silver halide emulsion

A photographic material with at least one light-sensitive silver halide emulsion is disclosed. The emulsion has been prepared by carrying out the precipitation of the silver halide in the presence of certain imidazoles.

Light-sensitive photographic material

Direct positive silver halide emulsions are provided which contain fogged silver halide grains the said grains being heterodisperse and containing silver iodide in an amount of more than 10 mole % and at most 20 mole % relative to the total amount of silver halide. The emulsions have increased sensitivity and reduced gradation which is suitable for continuous tone reproduction.

Direct-positive emulsion containing fogged, silver halide grains of

Photographic silver halide emulsions with increased sensitivity are obtained by exposing the silver halide emulsions to an ionizing radiation during preparation, the exposure being terminated before the grains reach their final size.

Exposure of silver halide emulsions during formation

An improvement in the stability of a direct positive emulsion layer in photographic material is obtained by the inclusion of a compound which provides in the image-wise exposed and developed direct positive emulsion layer a greater difference between the density of the image in the unexposed parts of the layer and the density in the exposed parts. The compound provides in the emulsion a characteristic curve related to a density value at maximum density which is at least twice the analogous density value at minimum density.

Direct-positive photographic material

Direct positive silver halide emulsions are provided which contain fogged silver halide grains with a layered grain structure wherein the external shell of the silver halide grains comprise up to 20 mole % of silver iodide based on the silver halide of the shell. The emulsions show improved sensitivity and produce images of improved maximum density.

Direct positive silver halide elements

Direct positive silver halide emulsions are provided which contain fogged homodisperse silver halide grains having a silver iodide content of more than 10 mole % and at most 20 mole % relative to the total amount of silver halide. These emulsions have higher sensitivity than corresponding fogged emulsions with less silver iodide content.

Direct positive emulsions containing fogged, monodispersed silver halide

A photographic material for producing direct-positive photographic images with at least one silver halide emulsion layer containing unfogged heterodisperse silver halide grains with a core which consists predominantly of silver bromide and a localised phase with a high silver chloride content of at least 20 mols-%, the total concentration of silver chloride, based on the total silver halide content of the grain, is less than 30 mols-%, and at least 10% by weight of the silver halide grains have a diameter which deviates by at least 40% from the average grain diameter in which the silver halide grains are not or only slightly chemically sensitised on the surface.

Photographic emulsion containing unfogged, heterodisperse layered silver

Equidensity images can be produced by imagewise exposure and photographic processing of a photographic material containing at least two silver salt emulsions which may be arranged in one layer as a mixture or in two layers, wherein one silver salt emulsion is a fogged direct positive emulsion and the other is a negative emulsion.

Photographic material containing fogged, direct positive silver halide

A direct-positive photographic material for producing images by fogging development wherein the photographic material contains an unfogged silver halide emulsion layer. The silver halide grains in the unfogged emulsion have a layered grain structure wherein there is a first phase in which is localized a relatively high silver chloride content of at least 20 mol percent based on the total silver halide content of the grain. A second phase contains from less silver chloride than the first phase down to no silver chloride and the total silver chloride in the grain does not exceed 30 mol percent. The physical position of the first phase in the grain is not critical. The emulsion is either not chemically sensitized or only slightly sensitized. The photographic material and its use includes both producing black and white and colored photographic images and has high sensitivity to light and by fogging development yields pure image whites.

Growing community of inventors

Cologne, Germany

Erik Moisar