Film for duplicating silver images in radiographic films
AssigneeEastman Kodak Company
InventorsRalph W. Jones, Catherine C. Wideman, Paul W. Twombly
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Abstract
A film is disclosed for duplicating a silver image in a radiographic film. A single monodispersed fogged direct-positive emulsion layer is employed. To extend exposure latitude the emulsion layer contains micro-crystalline particles of a dye that competes with the fogged direct positive grains of the emulsion layer for absorption of exposing radiation and can be decolorized during photographic processing.
Claims13
A radiographic duplicating film for duplicating a silver image in a radiographic taking film, the radiographic duplicating film being comprised of
- a transparent film support,
- a direct-positive imaging unit exhibiting an average contrast of from -0.8 to -1.2 over an exposure range measured from a density of 0.5 to a density of 2.5, and
- a protective overcoat free of microcrystaline dye particles,
- wherein the direct-positive imaging unit consists of a single, direct-positive emulsion layer and contains
- (a) surface fogged silver halide grains for recording exposure to electromagnetic radiation that has in part passed through the radiographic taking film and has been in part absorbed by the silver image within the radiographic taking film
- (1) having a mean grain equivalent circular diameter in the range of from 0.20 to 0.70 .mu.m,
- (2) exhibiting a coefficient of variation of grain equivalent circular diameter of less than 20 percent,
- (3) coated at a silver coverage of from 2.0 to 3.5 g/m.sup.2, and
- (4) containing at least 50 mole percent bromide and less than 3 mole percent iodide, based on silver, any remaining halide being chloride, and
- (b) microcrystalline particles
- (1) consisting essentially of a dye capable of absorbing a portion of the electromagnetic radiation received from the radiographic taking film and capable of being decolorized during photographic processing,
- (2) having a mean equivalent circular diameter of less than 1 .mu.m and
- (3) coated at a coverage of from 10 to 50 percent by weight, based on the weight of silver forming the surface fogged silver halide grains.
A radiographic duplicating film for duplicating a silver image in a radiographic taking film comprised of
- a blue tinted transparent film support,
- a direct-positive imaging unit exhibiting an average contrast of from -0.8 to -1.2 over an exposure range measured from a density of 0.5 to a density of 2.5 and capable of producing a maximum density of at least 3.0, and
- a protective overcoat,
- wherein the direct-positive imaging unit consists of a single, direct-positive emulsion layer and contains
- (a) surface fogged silver halide grains for recording exposure to electromagnetic radiation that has in part passed through the radiographic taking film and been in part absorbed by the silver image within the radiographic taking film
- (1) having a mean grain equivalent circular diameter in the range of from 0.30 to 0.50 .mu.m,
- (2) exhibiting a coefficient of variation of grain equivalent circular diameter of less than 20 percent,
- (3) coated at a silver coverage of from 2.2 to 3.0 g/m.sup.2, and
- (4) containing at least 65 mole percent bromide and less than 1 mole percent iodide, based on silver, any remaining halide being chloride, and
- (b) microcrystalline particles
- (1) consisting essentially of a dye capable of absorbing a portion of the electromagnetic radiation received from the radiographic taking film and capable of being decolorized during photographic processing,
- (2) having a mean equivalent circular diameter equal to or less than the equivalent circular diameter of the fogged silver halide grains and
- (3) coated at a coverage of from 10 to 25 percent by weight, based on the weight of silver forming the surface fogged silver halide grains.
Dependencies are inferred from the claim text.