Patents by Inventor David R. Matherly

David R. Matherly 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: 4463399
    Abstract: An electric circuit for energizing an intrinsically safe pilot light having a cluster of light emitting diodes arranged in a pattern and visible through a lense cap located in a hazardous area. The pilot light has terminals connected through the circuit that includes a rectifying bridge and a current regulator to the diodes to optimize the light output of the diodes and make the pilot light insensitive to the polarity of an A.C. or D.C. intrinsically safe electrical supply to the pilot light and limiting the current to the diodes to a constant value in event one or more of the diodes is destroyed or shorted. A pair of printed circuit boards are spaced by a plurality of conductive supports with one of the boards mounted on a base of the pilot light and carrying the rectifier and current limiting components which are connected to the terminals.
    Type: Grant
    Filed: July 19, 1982
    Date of Patent: July 31, 1984
    Assignee: Square D Company
    Inventors: David R. Matherly, Horace O. Sue