Patents by Inventor Derek J. Cash

Derek J. Cash 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: 4001025
    Abstract: Silver halide crystals in photographic emulsions are sensitized by the addition of compounds to the emulsion which will form silver sulphide with the silver halide crystals at a fast reaction rate v, where v = k. [concentration of the sensitizer compound in the emulsion] and k, the rate constant for the sulphide formation under the digestion conditions is in the range of from 0.1 to 100 min.sup.-.sup.1, and preferably at 0.5 to 10 min.sup.-.sup.1, provided that the sensitizer compound will distribute itself over the silver halide crystal surfaces at a rate which is fast as compared with the reaction rate of the sensitizer compound with the silver halide crystals so that substantially every silver halide crystal has an amount of sensitizer compound adsorbed to its surface from the beginning of the reaction sufficient to give the emulsion good contrast but not sufficient to cause fog.
    Type: Grant
    Filed: October 10, 1974
    Date of Patent: January 4, 1977
    Assignee: Minnesota Mining and Manufacturing Company
    Inventor: Derek J. Cash