Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Two or more radiation-sensitive layers containing other than...
Reexamination Certificate
2001-07-30
2002-11-12
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Two or more radiation-sensitive layers containing other than...
C430S523000, C430S558000, C430S557000, C430S552000, C430S553000, C430S546000
Reexamination Certificate
active
06479225
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to photographic silver halide print media and, in particular, to chromogenic sepia print media developed in standard rapid color process chemistry.
BACKGROUND OF THE INVENTION
Chromogenic print media are formulated with one or more light sensitive silver halide layers, typically on reflective support. Each light sensitive layer develops to a hue comprised of a mixture of dyes when processed in standard Red color development chemistry. This is accomplished by co-dispersing cyan, magenta, and yellow dye-forming couplers in such a manner that the mixture of dyes formed during development combine to give the desired hue. In the current invention the desired hue is sepia, a color ranging firm yellow-brown to orange-brown. Other hues of commercial interest may be achieved by changing the relative proportions of the couplers in the co-dispersion.
Chromogenic photographic elements are described in the prior art. For example, U.S. Pat. No. 5,362,616 of J. L. Edwards et al describes the combination of ortho-aryloxy aniline derived yellow couplers in combination with pyrazolotriazoles for chromogenic black and white media. European Application 0 600 377 A1 of J. L. Edwards describes the use of yellow couplers derived from ortho-methoxy anilines. U.S. Pat. No. 5,728,511 of T. Hirosawa et al discloses the use of pyrazolotriazoles magenta couplers in combination with yellow couplers derived from ortho-chloro anilines and the use of certain sensitizing dyes. U.S. Pat. No. 5,939,247 of T. Hirosawa et al also discloses pyrazolotriazoles in combination with yellow couplers derived from ortho-chloro anilines. U.S. Pat. No. 5,491,053 of G. N. Barber et al teaches the combinations of pyrazolones with ortho chloro anilines for chromogenic black and white media. U.S. Pat. No. 5,728,511 of T. Hirosawa et al describes the use of a certain class of formalin scavenger and a specific triazine compound. U.S. patent application Ser. No. 09/633,610 filed on Aug. 7, 2000 discloses a chromogenic black and white element which produces images having improved thermal and light stability. Japanese Kokai 10-31274 describes a chromogenic black and white media which meets certain hue specifications.
There is still a need, however, for a chromogenic sepia media which provides visually pleasing images and which is also stable to light and heat. The inventors herein have discovered that one problem with chromogenic sepia media relates to the Dmin of the paper support the photographic multilayer is coated on. Typical color photographic reflection support is tinted to create the perception of a bright White Dmin. This is undesirable for sepia images because of the harsh visual contrast between the white background and the brown image tones. It also creates a much larger challenge in balancing the couplers utilized to form the sepia image.
SUMMARY OF THE INVENTION
This invention provides a silver halide photographic element for forming a sepia image comprising a support and an image dye forming unit which contains a cyan dye forming coupler, a magenta dye forming coupler and a yellow dye forming coupler; wherein the support has CIELAB a* and b* values within the following ranges at L*>90:0<b*<6.0, 0<a*<1.0; and
wherein the image formed after exposure and development of the photographic element has CIELAB a* and b* values within the following ranges at each of the specified L* levels;
L* = 90
0 < a* < 4
0 < b* < 10
L* = 75
2 < a* < 12
8 < b* < 18
L* = 50
6 < a* < 25
10 < b* < 25
L* = 25
10 < a* < 30
10 < b* < 25
ADVANTAGEOUS EFFECT OF THE INVENTION
The invention provides a chromogenic sepia reflective photographic paper material that, when developed in standard RA color development chemistry, produces images having improved and more visually pleasing sepia image quality. The invention has numerous advantages over prior chromogenic sepia media. The inventive photographic element forms an excellent image over a wide range of exposure times for conventional and digital exposure devices. In a preferred embodiment the image formed by the inventive media exhibits much improved thermal and light stability, maintaining good Dmins after extended incubation to heat or light. The inventive media also preserves the color lightness reproduction previously described in U.S. Pat. No. 5,362,616 which enhances perceived image quality. The preferred structure of the inventive media has a single imaging layer that provides for improved sharpness and developability, and it contains yellow dye-forming couplers that are more suitably matched in reactivity to couplers of general formula MEGENTA-2. The photographic paper support of the invention has a Dmin which enhances the image quality by lowering the color contrast between the background and sepia image tones. These and other advantages will be apparent from the detailed description below.
DETAILED DESCRIPTION OF THE INVENTION
A chromogenic sepia photographic imaging element has at least one dye imaging unit comprising a light sensitive silver halide emulsion, a cyan dye-forming coupler, a magenta dye-forming coupler, and a yellow dye-forming coupler, and produces when developed a monochrome image. The red, green, and blue light absorbing (RGB) components of the hue can be plotted as individual photographic curves (Status A density vs. relative log exposure) according to standard trade practices. Each curve is referred to in the current invention as either the red, green., or blue “dye curve”. The red dye curve results primarily from the formation of cyan dye, the green dye curve primarily from the formation of magenta dye, and the blue dye curve primarily from the formation of yellow dye. The speed of each dye curve is the relative log exposure required to produce a Status A density of 0.8. Status A is the standard density unit used in the trade for reflection media. The preferred red, green, and blue dye curves of a sepia toned image do not overlap and do not have the same maximum densities (Dmax). In a single imaging layer, the speed of each dye curve depends in part on the relative reactivity of the co-dispersed couplers. The more reactive a coupler is relative to the other couplers in the co-dispersion, the greater the speed of its corresponding dye curve. When coupler reactivities are not matched, the dye curves do not align properly to form the desired hue at all densities.
The terms as used herein, “top”, “upper”, “emulsion side”, “imaging side” and “face” mean the side or towards the side of an imaging member bearing the imaging layers or developed image. The terms “bottom”. “lower side” and “back” mean the side or towards the side of the imaging member opposite from the side bearing the imaging layers or developed image. The term substrate as used herein refers to a support or base material that is the primary part of an imaging element such as paper, polyester, vinyl, synthetic paper, fabric, or other suitable material for the viewing of images. As used herein, the phrase “photographic element” is a material that utilizes photosensitive silver halide in the formation of images. The photographic elements are chromogenic sepia elements. Chromogenic sepia elements contain image dye-forming units sensitive to each of the three primary regions of the spectrum. Each unit can comprise a single emulsion layer or multiple emulsion layers sensitive to a given region of the spectrum. In one embodiment the image forming unit comprises three photosensitive layers. The layers of the element, including the layers of the image-forming units, can be arranged in various orders as known in the art. In an alternative format, the emulsions sensitive to each of the three primary regions of the spectrum can be disposed as a single segmented layer. The emulsions in this format are sensitized with a single color sensitizing and are substantially free of sensitizing dye of another color.
The silver halide photographic elements of the invention contain he appropriate amoun
Roberts Michael R.
Schroeder Kurt M.
Valvo David J.
Eastman Kodak Company
Letscher Geraldine
Meeks Roberts Sarah
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