Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Identified radiation sensitive composition with color...
Reexamination Certificate
1998-04-24
2001-02-20
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Identified radiation sensitive composition with color...
C430S359000, C430S505000, C430S506000, C430S546000
Reexamination Certificate
active
06190847
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to color negative films intended to create images for scanning, electronic manipulation, and reconversion to a viewable form.
DEFINITION OF TERMS
The term “E” is used to indicate exposure in lux-seconds.
The term “gamma” is employed to indicate the incremental increase in image density (&Dgr;D) produced by a corresponding incremental increase in log exposure (&Dgr;log E) and indicates the maximum gamma measured over an exposure range extending between a first characteristic curve reference point lying at a density of 0.15 above minimum density and a second characteristic curve reference point separated from the first reference point by 0.9 log E.
The term “exposure latitude” indicates the exposure range of a characteristic curve segment over which instantaneous gamma (&Dgr;D/&Dgr;log E) differs from gamma, as defined above, by no more than 25 percent.
The term “coupler” indicates a compound that reacts with oxidized color developing agent to create or modify the hue of a dye chromophore.
In referring to blue, green and red recording dye image-forming layer units, the term “layer unit” indicates the hydrophilic colloid layer or layers that contain radiation-sensitive silver halide grains to capture exposing radiation and couplers that react upon development of the grains. The grains and couplers are usually in the same layer, but can be in adjacent layers.
The term “colored masking coupler” indicates a coupler that is initially colored and that loses its initial color during development upon reaction with oxidized color developing agent.
The term “substantially free of colored masking coupler” indicates a coating coverage of less than 0.09 millimole/m
2
of colored masking coupler in a dye image-forming layer unit.
The term “dye image-forming coupler” indicates a coupler that reacts with oxidized color developing agent to produce a dye image.
The term “absorption half-peak bandwidth” indicates the spectral range over which a dye exhibits an absorption equal to at least half of its peak absorption.
The term “development inhibitor releasing compound” or “DIR” indicates a compound that cleaves to release a development inhibitor during color development. As defined DIR's include couplers and other compounds that utilize anchimeric and timed releasing mechanisms.
The term “diffusion factor” in referring to development inhibitor releasing compounds indicates the extent of diffusion of the released development inhibitor. A higher diffusion factor indicates a higher extent of released inhibitor diffusion. DIR diffusion factors are quantified by the procedure described in the Diffusion Factor section of the Examples, below.
In referring to grains and emulsions containing two or more halides, the halides are named in order of ascending concentrations.
In referring to grains, “ECD” indicates mean equivalent circular diameter and, in describing tabular grains, “t” indicates mean tabular grain thickness.
References to blue, green and/or red spectral sensitizing dyes indicate dyes that absorb blue, green or red light and transfer absorbed photon energy to silver halide grains when adsorbed to their surfaces.
Research Disclosure is published by Kenneth Mason Publications, Ltd., Dudley House, 12 North St., Emsworth, Hampshire P010 7DQ, England.
BACKGROUND
Color negative photographic elements are conventionally formed with superimposed blue, green and red recording layer units coated on a support. The blue, green and red recording layer units contain radiation-sensitive silver halide emulsions that form a latent image in response to blue, green and red light, respectively. Additionally, the blue recording layer unit contains a yellow dye image-forming coupler, the green recording layer unit contains a magenta dye image-forming coupler, and the red recording layer unit contains a cyan dye image-forming coupler. Following imagewise exposure, the photographic elements are processed in a color developer, which contains a color developing agent that is oxidized while selectively reducing to silver latent image-bearing silver halide grains. The oxidized color developing agent then reacts with the dye image-forming coupler in the vicinity of the developed grains to produce an image dye. Yellow (blue-absorbing), magenta (green-absorbing) and cyan (red-absorbing) image dyes are formed in the blue, green and red recording layer units respectively. Subsequently the element is bleached (i.e., developed silver is converted back to silver halide) to eliminate neutral density attributable to developed silver and then fixed (i.e., silver halide is removed) to provide stability during subsequent room light handling.
When processing is conducted as noted above, negative dye images are produced. To produce a viewable positive dye image and hence to produce a visual approximation of the hues of the subject photographed, white light is typically passed through the color negative image to expose a second color photographic element having blue, green and red recording layer units as described above, usually coated on a white reflective support. The second element is commonly referred to as a color print element, and the process of exposing the color print element through the image-bearing color negative element is commonly referred to as printing. Processing of the color print element as described above produces a viewable positive image that approximates that of the subject originally photographed.
A problem with the accuracy of color reproduction delayed the commercial introduction of color negative elements. In color negative imaging two dye image-forming coupler containing elements are exposed and processed to arrive at a viewable positive image. The dye image-forming couplers each produce dyes that only approximate an absorption profile corresponding to that recorded by the silver halide grains. Since the color negative element cascades its color errors forward to the color print element, the cumulative error in the final print is unacceptably large, absent some form of color correction.
A commercially acceptable solution that remains in use today in the form of color slides is to subject a color photographic element having blue, green and red recording layer units to reversal processing. In reversal processing the film is first black-and-white processed to develop exposed silver halide grains imagewise without formation of a corresponding dye image. Thereafter, the remaining silver halide grains are rendered developable. Color development followed by bleaching and fixing produces a viewable color image corresponding to the subject photographed. The primary objections to this approach are (a) the more complicated processing required and (b) the absence of an opportunity to correct underexposures and overexposures, as is provided during exposure of a print element.
Commercial acceptance of color negative elements occurred after commercial introduction of the first color reversal films. The commercial solution to the problem of cascaded color error has been to place colored masking couplers in the color negative element at concentrations of greater than 0.12 (typically greater than 0.25) millimole/m
2
. Illustrations of colored masking couplers are provided by Research Disclosure, Vol. 389, September 1996, Item 38957, XII. Features applicable only to color negative, paragraphs (1) and (2). The colored masking couplers lose or change their color in areas in which grain development occurs producing a dye image that is a reversal of the unwanted absorption of the image dye. This has the effect of neutralizing unwanted spectral absorption by the image dyes by raising the neutral density of the processed color negative element. In practical applications this is not a difficulty, since increased neutral minimum densities are easily offset by increasing exposure levels when exposing the print element through the color negative element.
In color negative films in which silver coating coverages are significantly reduced it is in some instances difficult to obtain a
Brockler Frank R.
Buhr John D.
Buitano Lois A.
Giorgianni Edward J.
Gonzalez Maria J.
Baxter Janet
Eastman Kodak Company
Kluegel Arthur E.
Walke Amanda C.
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