Patents by Inventor Darrell T. Thompson

Darrell T. Thompson 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).

  • Control system for the electrolytic recovery of silver from photographic fixing solution
    Patent number: 4263108
    Abstract: Plating current in a silver-recovery process is controlled as a function of the cell voltage of the system taken in the absence of plating current, and held as a control determinant. The control is modified to produce certain characteristics at low silver concentration to further reduce sulfiding.
    Type: Grant
    Filed: March 27, 1980
    Date of Patent: April 21, 1981
    Assignee: Foresight Enterprises, Incorporated
    Inventors: Bernard J. Berg, Darrell T. Thompson
  • Method of testing photographic film using multicolor sensitometer
    Patent number: 4235537
    Abstract: The sensitivity of photographic materials is measured by a device that generates a controlled exposure of light of predetermined color characteristics. Color control is maintained by subjecting an electroluminescent light source to excitation by alternating current voltages at particular frequencies selected with reference to the light souce color response.
    Type: Grant
    Filed: January 26, 1978
    Date of Patent: November 25, 1980
    Inventor: Darrell T. Thompson