Patents by Inventor Derald E. Martin

Derald E. Martin 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).

  • Door lock with indicator
    Patent number: 4490999
    Abstract: A self-contained door lock with an indicating device visible on the inside surface of a door that can be provided as an adaptor for existing door locks or manufactured as part of the original door lock. The indicating device automatically gives a visible indication at the lock location as to whether the door lock is locked or unlocked. The indicating device automatically works in coordination with the door lock mechanism.
    Type: Grant
    Filed: September 27, 1982
    Date of Patent: January 1, 1985
    Inventors: Nial K. Castle, Derald E. Martin, Ralph D. Martin