Patents by Inventor Lowell Sherman Pelfrey

Lowell Sherman Pelfrey 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).

  • Let-ball detectors
    Patent number: 4081798
    Abstract: Electric currents induced by a magnetic field being moved in relation to a fixed coil, by a vertical displacement of the net cable/tennis net, enables a referee to detect the occurrence of a "let-ball.
    Type: Grant
    Filed: March 14, 1977
    Date of Patent: March 28, 1978
    Inventor: Lowell Sherman Pelfrey