Patents by Inventor Henry T. Gruber

Henry T. Gruber 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).

  • Multiple frequency digital eddy current inspection system
    Patent number: 4207520
    Abstract: An apparatus for inspecting for cracks under installed fasteners and the like using a multiple frequency digital eddy current system. A computer with a plurality of digital arrays generate drive signals which are converted to analog and applied to the test coil, a second set of digital arrays generate balance signals, are adjusted in amplitude and phase and drive signals so that the output of the test coil is zero in a test specimen, output signals from a work piece are processed in the computer giving phase-sensitive crack detection.
    Type: Grant
    Filed: April 6, 1978
    Date of Patent: June 10, 1980
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: John H. Flora, Henry T. Gruber