Agfa Gevaert Nv

Peter Verrept

Ann L Verbeeck

Freddy Henderickx

Hieronymus Andriessen

Frank Louwet

Johan August Loccufier

Paul R Callant

Dirk Vandenbroucke

Koenraad Caron

Jan Cuypers

Nadia Vermant

A light-sensitive silver halide photographic emulsion has been described, said emulsion comprising a colloidally stabilizing binder and {100} tabular silver halide grains containing at least 50 mole % of silver chloride, wherein at least 70% by number of all grains is provided by said tabular grains, exhibiting an average aspect ratio of at least 5 and an average equivalent circular grain diameter of at least 0.3 .mu.m, wherein said tabular grains have an average thickness of less than 0.25 .mu.m for at least 75% by number of all tabular grains. In order to prepare said emulsion a method has been disclosed comprising performing at least three distinct precipitation steps in an aqueous medium in a reaction vessel, followed by desalting by means of washing after flocculation or by means of ultrafiltration, wherein said three distinct precipitation steps consist of a nucleation step followed by a first and a second growth step, said method being further characterized by introducing in the said reaction vessel, after the first growth step, of a block-copolymer according to the formula (I) as described in the detailed description and in the claims.

Light-sensitive emulsion having (100) tabular grains rich in silver

A method has been described for preparing a light-sensitive silver halide photographic emulsion comprising performing at least three distinct precipitation steps in an aqueous medium into a reaction vessel, followed by desalting by means of flocculation and washing or by means of ultrafiltration, said emulsion comprising a colloidally stabilizing binder and {100} tabular silver halide grains containing at least 50 mole % of silver chloride, wherein at least 60% by number of all grains is provided by said tabular grains, and wherein said tabular grains exhibit an average aspect ratio of at least 2, an average thickness of at most 0.25 .mu.m with a variation coefficient of at most 0.25, and an average equivalent circular crystal diameter of 0.3 .mu.m or more with a variation coefficient of at most 0.20;

Method for preparing a light-sensitive emulsion having (100) tabular

An image-forming system for radiological imaging is described consisting of an intensifying screen comprising on a support at least one layer of a green-light emitting phosphor and, in operative association therewith, a prehardened light-sensitive photographic silver halide film material, comprising a support and on both sides thereof one or more hydrophilic colloid layers having monodisperse cubic silver chloroiodide grains with a mean crystal diameter of from 0.40 .mu.m up to 0.65 .mu.m or {111} tabular silver chloroiodide grains having an aspect ratio of from 5 to 20 and a tabularity from 20 to 200; wherein said grains have been spectrally sensitized in the green wavelength range and have been coated in a total amount of silver per sq.m. of from 6 g up to 8 g, expressed as an equivalent amount of silver nitrate per sq.m.; wherein in the image-forming system silver chloroiodide grains have been chemically sensitized with one or more selenide compound(s) generating silver selenide.

System and method for radiological image formation

A method has been found of preparing a silver halide emulsion comprising silver chlorobromoiodide or silver chloroiodide tabular grains with at least 75 mole % of chloride and from 0.1 up to 3 mole % of iodide, based on silver, further having {111} crystal faces, an average aspect ratio of at least 2:1, with at least 50%, more preferable at least 75% and still more preferable more than 90% of the total projected area of all grains being provided by said tabular grains and with a variation coefficient on sphere equivalent diameter (SED) of said grains being lower than 0.30, more preferably lower than 0.25 and most preferable from 0.05 up to at most 0.15, said method comprising the steps of

Method of preparing {111} tabular silver chloro(bromo)iodide crystals

A method has been described for preparing a gelatinous emulsion having grains rich in silver choride, wherein at least 70%, and more preferred 90%, of the total projected area of all grains is provided by {111} tabular grains having an average aspect ratio of more than 2:1, an average equivalent circular diameter of at least 0.3 .mu.m and an average thickness of from 0.05 to 0.25 .mu.m , wherein a percent variation on average equivalent circular diameter of said tabular grains is 30% or less and wherein a percent variation on average thickness of said tabular grains is 20% or less and wherein said tabular grains are present in percent numerical amounts of at least 90%, said method comprising following steps:

Method for preparing tabular grains rich in silver chloride with reduced

An image-forming system for radiological imaging is disclosed said system consisting of an intensifying screen comprising on a support at least one layer of a green-light emitting phosphor and, in operative association therewith, a prehardened light-sensitive photographic silver halide film material, comprising a support and on both sides thereof one or more hydrophilic colloid layers, said layers being hardened to such an extent that their swelling degree is reduced to less than 200% after immersing said material for 2 minutes in demineralised water of 35.degree. C.; further comprising in at least one of said hydrophilic layers chemically ripened, monodisperse essentially cubic silver chloroiodide grains having a mean crystal diameter of from 0.40 mm up to 0.65 mm; wherein said grains have been spectrally sensitised in the wavelength range between 520 and 580 nm, have a maximum absorption between 540 and 500 nm and have been coated in a total amount of silver per sq.m. of from 6 g up to 8 g, wherein said amount is expressed as an equivalent amount of silver nitrate per sq.m.; said image-forming system being characterised in that said silver chloroiodide grains have been doped with a complex ion compound satisfying the formula

A radiographic screen/film combination or system has been provided comprising a duplitized film sandwiched between a pair of supporting or self-supporting X-ray intensifying screens, characterized in that i) said pair of supported or self-supporting X-ray intensifying screens essentially consists of luminescent phosphor particles emitting at least 50% and more preferably at least 80% of their emitted radiation in the wavelength range shorter than 380 nm, as e.g. a niobium and gadolinium doped, monoclinic M, yttriumtantalate (MYT) phosphor corresponding to formula I

Radiographic UV/blue intensifying screen-film combination

A method has been disclosed of processing an image-wise exposed light-sensitive black-and-white silver halide photographic material comprising a support coated on one or both sides thereof with hydrophilic layers, wherein at least one of said layers comprises one or more emulsions having tabular silver halide crystals rich in silver chloride, said method comprising the steps of developing, fixing, rinsing and drying, further characterized in that said developing step proceeds in a black-and-white developer comprising one or more organic compounds inhibiting development, more preferably one or more benzotriazole compounds, and in that said developer is substantially free from bromide ions in favor of a low fog level, a high speed and a sufficiently high covering power of the developed tabular grains.

Processing of a light-sensitive silver halide photographic material

A method is disclosed of preparing of a photographic silver halide emulsion comprising precipitating in one or more precipitation steps in a reaction vessel, followed by desalting by means of flocculation and washing or by means of ultrafiltration, said emulsion comprising gelatin as a binder and {100} tabular silver halide grains containing at least 50 mole % of chloride, wherein at least 40% by number of all grains is provided by said tabular grains, and wherein said tabular grains exhibit an average aspect ratio of at least 2, an average thickness of at most 0.5 .mu.m, and an average equivalent circular crystal diameter of 0.3 .mu.m or more, characterized in that during said precipitation step(s) said gelatin binder present in said reaction vessel is substantially free of calcium ions and is oxidized to a degree in order to have a methionine content of at most 4000 ppm.

Method for the preparation of an improved photographic tabular emulsion

A method is disclosed for the preparation of tabular silver halide emulsion grains rich in chloride and showing (100) parallel major and an average aspect ratio of at least 2.0 in silica sol as protective colloid binder. Important parameters are the addition modalities of the silica sol and the ratio of its amount to the amount of a costabilizing onium compound.

Preparation method for (100) tabular silver halide grains rich in

A light-sensitive silver bromide or silver bromoiodide emulsion is provided, comprising silver bromide or silver bromoiodide tabular triangular grains, said tabular triangular grains having an average grain thickness of less than 0.3 .mu.m, an average crystal diameter of at least 0.6 .mu.m; an average aspect ratio of at least 2:1; a variation coefficient of less than 40%, said grains accounting for a total projective area of at least 30%; characterized in that the thickness ratio of triangular tabular grains to hexagonal tabular grains is from 1.3 to 0.7.

Growing community of inventors

Avelgem, Belgium

Peter Verrept