Patents by Inventor Gerald A. Denhardt

Gerald A. Denhardt 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).

  • Piezoelectric vibrational and acoustic alert for a personal communication device
    Patent number: 6259188
    Abstract: An alert apparatus for a personal communication device includes a mechanically prestressed piezoelectric wafer positioned within the personal communication device and an alternating voltage input line coupled at two points of the wafer where polarity is recognized. The alert apparatus also includes a variable frequency device coupled to the alternating voltage input line, operative to switch the alternating voltage on the alternating voltage input line at least between an alternating voltage having a first frequency and an alternating voltage having a second frequency. The first frequency is preferably sufficiently high so as to cause the wafer to vibrate at a resulting frequency that produces a sound perceptible by a human ear, and the second frequency is preferably sufficiently low so as to cause the wafer to vibrate at a resulting frequency that produces a vibration readily felt by a holder of the personal communication device.
    Type: Grant
    Filed: August 31, 1999
    Date of Patent: July 10, 2001
    Assignee: Projects Unlimited, Inc.
    Inventors: Stanley E. Woodard, Richard F. Hellbaum, Robert H. Daugherty, Raymond C. Scholz, Bruce D. Little, Robert L. Fox, Gerald A. Denhardt, SeGon Jang, Rizza Balein