Patents by Inventor Keith H. Stephen

Keith H. Stephen has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5536625
    Abstract: This invention provides an accelerator for peracid bleaches used for bleaching silver halide photographic elements. The accelerator is a complex of ferric (Fe III) ion and a 2-pyridinecarboxylic acid or a 2,6-pyridinecarboxylic acid. The accelerator may be contained in the bleaching solution, a solution preceding the bleaching solution or in the photographic elements themselves.
    Type: Grant
    Filed: March 20, 1995
    Date of Patent: July 16, 1996
    Assignee: Eastman Kodak Company
    Inventors: John M. Buchanan, Stuart T. Gordon, Keith H. Stephen, Richard P. Szajewski, Sidney J. Bertucci
  • Patent number: 5460924
    Abstract: This invention provides an accelerator for peracid bleaches used for bleaching silver halide photographic elements. The accelerator is a complex of ferric (Fe III) ion and a 2-pyridinecarboxylic acid or a 2,6-pyridinecarboxylic acid. The accelerator may be contained in the bleaching solution, a solution preceding the bleaching solution or in the photographic elements themselves.
    Type: Grant
    Filed: April 20, 1994
    Date of Patent: October 24, 1995
    Assignee: Eastman Kodak Company
    Inventors: John M. Buchanan, Stuart T. Gordon, Keith H. Stephen, Richard P. Szajewski, Sidney J. Bertucci
  • Patent number: 5434035
    Abstract: A method of treating a seasoned fixing solution comprising desilvering a fixing solution containing a chelating compound represented by Formula IMOOC(CH.sub.2)m(X)p((CH.sub.2).sub.n COOM).sub.q (I)where X is N, or C--OH;n and m are independently 0, 1, or 2;if X is N then p is 0 or 1 and q is 1 or 2;if X is C-OH then p is 0, 1 or 2 and q is 1 or 2; andM is a cationic counterion; andfurther containing a carryover amount of a bleaching agent which is a complex of ferric ion and a tridentate or a tetradentate ligand.
    Type: Grant
    Filed: December 29, 1993
    Date of Patent: July 18, 1995
    Assignee: Eastman Kodak Company
    Inventors: Mary E. Craver, Manuel A. Santos-Rosario, Keith H. Stephen
  • Patent number: 5334491
    Abstract: Bleach compositions and methods that are improvements over those provided by Fyson, U.S. Pat. No. 4,294,914, are disclosed. A highly preferred bleach composition of this invention (a) has the ferric complex of methyliminodiacetic acid as a bleaching agent, and additionally comprises (b) at least 0.9 mole of acetic acid per liter, (c) from about 15 to about 35 grams per liter of potassium bromide; and (d) has a pH of from about 2.5 to about 4.0.This invention includes the discovery of a synergistic bleaching coaction of a bleach (i) comprising an alkyliminodiacetic acid such as methyliminodiacetic acid, and (ii) which has a pH of from about 3.5 to about 4.5 , and (iii) in which the amount of ferric iron is from about 2 to about 16 grams per liter. This coaction between iron levels and pH was previously unknown and was unexpected.Bleach formulations of this invention can be used in the processing of color photographic materials, such as film.
    Type: Grant
    Filed: September 22, 1993
    Date of Patent: August 2, 1994
    Assignee: Eastman Kodak Company
    Inventors: David G. Foster, Keith H. Stephen, Mary E. Craver
  • Patent number: 5061608
    Abstract: An environmentally advantageous photographic bleaching solution for use in the color processing of photographic elements comprises (1) as a bleaching agent, a potassium salt of a ferric complex of an aminopolycarobxylic acid, (2) as an agent which functions to convert silver to silver halide, a potassium halide, and (3) as an agent which functions to inhibit bleach induced dye formation, a water-soluble aliphatic carboxylic acid. The bleaching solution is especially useful in the processing of photographic elements containing a low pKa, high-activity, yellow-dye-forming coupler in that it serves to effectively avoid the undesirable increase in blue D.sub.min that can occur in such elements as a result of bleach induced dye formation.
    Type: Grant
    Filed: April 19, 1991
    Date of Patent: October 29, 1991
    Assignee: Eastman Kodak Company
    Inventors: David G. Foster, Keith H. Stephen
  • Patent number: 4933266
    Abstract: Bleaching and bleach-fixing solutions, especially useful in the processing of a photographic color material, contain a bleaching agent comprising a ferric complex of propylenediaminetetraacetic acid and a hydroxy-substituted chelating agent present in an amount sufficient to reduce the formation of ferric propylenediaminetetraacetic acid precipitates. The solutions do not generate unacceptable stain or adversely affect leuco cyan dye recovery or process cleanliness.
    Type: Grant
    Filed: March 1, 1988
    Date of Patent: June 12, 1990
    Assignee: Eastman Kodak Company
    Inventors: Keith H. Stephen, Carol J. MacDonald
  • Patent number: 4256826
    Abstract: A bleach-fix sheet for use in color photographic processes comprises a support having thereon a bleaching agent, a fixing agent and a hardened hydrophilic binder. In a preferred embodiment, the bleach-fix sheet is useful to bleach and fix a retained image in a color image diffusion transfer unit.
    Type: Grant
    Filed: August 14, 1978
    Date of Patent: March 17, 1981
    Assignee: Eastman Kodak Company
    Inventors: Gerhard Popp, Patrick H. Saturno, Keith H. Stephen