Radiation imagery chemistry: process – composition – or product th – Post imaging processing – Developing
Reexamination Certificate
2002-05-20
2003-11-18
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Post imaging processing
Developing
Reexamination Certificate
active
06649331
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a novel developer composition for photographic color negative films and to a method of development that provide rapid development and production of high quality color display images.
BACKGROUND OF THE INVENTION
Production of photographic color images from light sensitive silver halide materials basically consists of two processes. First, color negative images are generated by light exposure and processing of camera speed, light sensitive films, that are sometimes called “originating” elements because the images are originated therein by the film user (that is, “picture taker”). These negative images are then used to generate positive images in light sensitive materials. These latter materials are sometimes known as “display” elements and the resulting images may be known as “prints” when coated on reflective supports or “films” when coated on nonreflective supports.
The light sensitive materials are processed in automated processing machines through several steps and processing solutions to provide the display images or prints. Traditionally, this service has required a day or more. In recent years, customers have wanted faster service, and in some locations, the time to deliver this service has been reduced to within an hour. Reducing the processing time to within a few minutes is the ultimate desire. To do this, each step must be shortened.
The photographic films processed in the practice of this invention are multilayer color elements having at least two color records. Such films typically contain dye image-forming units (or color records) sensitive to each of the three primary regions of the visible spectrum. Each unit can comprise a single silver halide emulsion layer or multiple emulsion layers sensitive to a given region of the spectrum. 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 elements can also contain other conventional layers such as filter layers, interlayers, subbing layers, overcoats and other layers readily apparent to one skilled in the art. A magnetic backing can be used as well as conventional supports. Preferably, transparent supports are employed in the films as are well known in the art. The layers of the photographic films can have known binder materials, including various types of gelatins and other colloidal materials (or mixtures thereof).
Color negative films generally have little or no silver chloride in their emulsions, and have silver bromide as the predominant silver halide. More typically, the emulsions are silver bromoiodide emulsions with silver iodide levels up to several mol percent. Such films have required these types of emulsions because emulsions containing high silver chloride have generally had insufficient light sensitivity to be used as camera speed materials although they have the advantage of being rapidly processed without major changes to the color developer solution.
To shorten the processing time, specifically the color development time, of films containing silver bromoiodide emulsions, more active color developer solutions are needed. Various attempts have been made to increase color developer activity by increasing the pH, increasing the color developing agent concentration, decreasing the halide ion concentration, or increasing temperature. However, when these changes are made, the stability of the solution and the photographic image quality are often diminished.
For example, when the development temperature is increased from the conventional 37.8° C., and the color developer solution is held (or used) in the processing tanks for extended periods of times, silver bromoiodide elements processed with such solutions often exhibit unacceptably high density in the unexposed areas of the elements, that is, unacceptably high Dmin.
U.S. Pat. No. 5,344,750 (Fujimoto et al) describes a method for processing films containing silver iodobromide emulsions that is allegedly rapid, including color development for 40-90 seconds. The potential problems of low sensitivity and high fog in rapidly developed films is asserted to be overcome by using a color development temperature and an amount of color developing agent and bromide ion in the color developer that are determined by certain mathematical relationships. That is, the amount of color developing agent and bromide ion are considered to be related, and the development temperature and bromide ion concentration are related, both relationships being expressed in mathematical equations.
It has been found, however, that even when the relationships described in U.S. Pat. No. 5,344,750 are followed and color negative films are color developed in short times (less than 90 seconds), the color balance of the three color records cannot be maintained through a useful exposure range. By “color balance” is meant the display image, produced from a neutral exposure of a color negative image, will have a neutral color rendition throughout the useful exposure range. The color record imbalance is caused by the difficulty of getting sufficient development in the red-sensitive color record next to the support without forcing the topmost blue-sensitive color record to be overdeveloped, resulting in high fog, contrast or Dmax. This color imbalance in the color records of a multilayer photographic color film cannot be corrected using conventional optical printing of the color negative onto a color display element. Thus, very short development times of the color negative films cannot readily provide negative images in the “originating” color negative film capable of providing display images having acceptable tone scale and color reproduction.
U.S. Pat. No. 5,455,146 (Nishikawa et al) describes a method for forming color images in photographic elements containing silver iodobromide emulsions that is allegedly rapid and includes color development for 30-90 seconds. The potential problems of gamma imbalance are asserted to be overcome by controlling the morphology of the light sensitive silver halide emulsion grains, the thickness and swell rate of the photographic film, and the ratio of 2-equivalent color couplers to total couplers in the red-sensitive silver halide emulsion layer. However, the methods described in this patent require a color negative film to be specifically constructed with the noted features to correct gamma imbalance, but they do not correct the color imbalance produced by rapidly developing commercially available color negative films that do not have the noted features. In other words, the method of gamma correction requires a specific film and cannot be applied to any film on the market.
Although the described processes are said to have lowered the processing times for color negative photographic films, a problem that remains is to provide a processing composition and method that will further shorten the processing time for commercially available silver bromoiodidecolor negative photographic films while producing a color image of excellent quality and avoiding the color imbalances that can occur in rapid processing of such films.
SUMMARY OF THE INVENTION
The present invention provides a novel developing solution for silver bromoiodide photographic color negative films with comprises:
(a) a color developing agent;
(b) sulfite ion in a concentration of about 0.025 to 0.25 mols per liter of solution;
(c) a water soluble pyrrolidone polymer in a concentration of about 1.0 to 10.0 grams per liter of solution; and
(d) said solution having a pH in the range of about 9 to 12 and containing no bromide ion or less than about 0.06 mols of bromide ion per liter of solution.
The present invention also provides a novel method for developing an imagewise exposed silver bromoiodide photographic color negative film which comprises treating said film with the above-defined developing solution for a period of about 20 to 90 seconds at a temperature from about 40 to 66° C. The developed film is of such excellent image quality that the method of the inventi
Arcus Robert A.
Bacel Peter N.
Weldy John A.
Eastman Kodak Company
Le Hoa Van
Nixon & Peabody LLP
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