Color photographic element exhibiting increased red speed

Details Color photographic element exhibiting increased red speed Color photographic element exhibiting increased red speed

2000-10-17

2002-02-26

Letscher, Geraldine (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Radiation sensitive product

Two or more radiation-sensitive layers containing other than...

C430S505000, C430S507000, C430S510000, C430S567000, C430S383000

Reexamination Certificate

active

06350565

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to color photographic silver halide elements containing a non-light sensitive light reflecting 3-D silver halide emulsion layer below the most sensitive red light sensitive layer.
DEFINITION OF TERMS
The term “equivalent circular diameter” or “ECD” is employed to indicate the diameter of a circle having the same projected area as a silver halide grain.
The term “aspect ratio” designates the ratio of grain ECD to grain thickness (t).
The term “tabular grain” indicates a grain having two parallel crystal faces that are clearly larger than any remaining crystal face and having an aspect ratio of at least 5.
The term “3-D” indicates a grain that is not a tabular grain as defined above.
The term “tabular grain emulsion” refers to an emulsion in which tabular grains account for greater than 50 percent of total grain projected area.
The term “non-tabular grain emulsion” refers to an emulsion in which tabular grains account for greater than 50 percent of total grain projected area.
The term “small 3-D grain emulsion” refers to a tabular or non-tabular grain emulsion in which at least 20 mol % of the grains in the emulsion are 3-D grains having an ECD in the range of 0.1 to 0.8 &mgr;m.
The term “{111} tabular” in referring to grains and emulsions indicates those in which the tabular grains have parallel major crystal faces lying in {111} crystal planes.
The term “high bromide” in referring to grains and emulsions indicates that bromide is present in a concentration greater than 50 mole percent, based on total silver.
In referring to silver halide grains and emulsions containing two or more halides, the halides are named in order of ascending concentrations.
The terms “blue”, “green” and “red” indicate the portions of the visible spectrum lying, respectively, within the wavelength ranges of from 400 to 500 nm, 500 to 600 nm and 600 to 700 mn.
The term “minus blue” indicates the visible portion of the spectrum outside the blue portion of the spectrum—e.g., any spectral region in the range of from 500 to 700 nm.
The term “half peak absorption bandwidth” indicates the spectral region over which a dye exhibits an absorption equal to half its peak absorption.
The terms “front” and “back” indicate a position that is nearer or farther, respectively, than the support from the source of exposing radiation, with the support being on the back.
The terms “above” and “below” indicate a position nearer or farther, respectively, from the source of exposing radiation, with the support being on the bottom.
The term “subject” designates the person(s) and/or object(s) photographed.
The term “stop” in comparing photographic speeds indicates an exposure difference of 0.3 log E required to produce the same reference density, where E is exposure in lux-seconds.
The term relatively non-light sensitive when referring to the grains of an emulsion means that the emulsion exhibits no more than 10% of the sensitivity of any of the red-light sensitive layers, as measured by red toe speed.
The term “maximum gamma” is herein defined as the highest observed ratio of &Dgr;D/&Dgr;E, where &Dgr;D is the increase in density that occurs in response to an increase in exposure &Dgr;E.
BACKGROUND OF THE INVENTION
Photographic images that allow re-creation or approximation of the natural hues of a subject are conventionally captured on photographic film mounted in a camera. Camera speed films typically employ high bromide silver halide emulsions. Separate images of each of blue, green and red exposures are captured in blue, green and red recording layer units within the film. The blue recording layer unit contains chemically sensitized high bromide grains that may either rely on native blue sensitivity or are spectrally sensitized to the blue region of the spectrum with one or more blue absorbing spectral sensitizing dyes. The green recording layer unit contains chemically sensitized high bromide grains that are sensitized to the green region of the spectrum with one or more green absorbing spectral sensitizing dyes. The red recording layer unit contains chemically sensitized high bromide grains that are sensitized to the red region of the spectrum with one or more red absorbing spectral sensitizing dyes. Dye-forming couplers are typically included in the layer units to allow dye images of distinguishable hue to be formed upon color processing. When the photographic film is intended for reversal processing to produce a viewable color positive image or when the photographic film is intended for use in exposing a color paper, the blue, green and red recording layer units contain couplers that form blue absorbing (yellow), green absorbing (magenta), and red absorbing (cyan) image dyes, respectively. When the dye image information is intended to be retrieved from the photographic film by digital scanning, the dye images can be of any hue, provided they are distinguishable. The layer units in a camera speed film are coated so that exposing radiation is first received by a blue recording layer unit, then a green recording layer unit, and finally a red recording layer unit. When two or more layer units differing in speed are provided for recording in a single spectral region, the exposing radiation receiving coating sequence of the slower, but not the faster recording layer units, is sometimes varied.
The high bromide silver halide grains incorporated in the green and red (minus blue) recording layer units of camera speed films have significant blue sensitivity. Coating the blue recording layer unit over the minus blue recording layer units protects the latter from blue light contamination.
The components used to construct color photographic films are disclosed in
Research Disclosure
, Vol. 389, September 1996, Item 38957.
Research Disclosure
is published by Kenneth Mason Publications, Ltd., Dudley House, 12 North St., Emsworth, Hampshire P010 7DQ, England. The following topics of Item 38957 are particularly pertinent to the present invention:
I. Emulsion grains and their preparation (most particularly the last sentence of paragraph (1) of B. Grain morphology);
II. Vehicles, vehicle extenders, vehicle-like addenda and vehicle related addenda;
IV. Chemical sensitization;
V. Spectral sensitization and desensitization A. Sensitizing dyes;
X. Dye image formers and modifiers (except A. silver dye bleach);
XI. Layers and layer arrangements;
XII. Features applicable only to color negative;
XIII. Features applicable only to color positive (except C. Color positives derived from color negatives);
XV. Supports.
Sutton et al U.S. Pat. No. 5,300,413 discloses high bromide {111} tabular grain emulsions with grain dispersities and thicknesses controlled to facilitate red light reflection.
Bringley and Friday U.S. Pat. No. 5,998,114 discloses a color photographic element comprised of a transparent film support and, coated on the support, a red recording layer unit containing the radiation-sensitive silver halide grains in a plurality of emulsion layers with each emulsion layer located to receive exposing radiation prior to an underlying emulsion layer containing silver halide grains of higher sensitivity than the silver halide grains located in the underlying emulsion layer. The red light reflective layer is free of red absorbing dye and contains tabular silver halide grains having a thickness in the range of from 0.03 to 0.12 &mgr;m, an average aspect ratio of greater than 20, and a coating coverage of 0.5 to 1.25 g/m
2
, and formed of greater than 50 mole percent bromide, based on silver. The reflective layer is located in the red recording layer unit interposed between two emulsion layers.
Bringley and Friday U.S. Pat. No. 6,001,548 discloses a color photographic element comprised of a transparent film support and, coated on the support, a red recording layer unit containing the latent image forming silver halide grains in a plurality of emulsion layers with the latent image forming silver halide grains of maximum sensitivity being the first red recording emulsion lay

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