Patents by Inventor Lawrence D. Forsythe

Lawrence D. Forsythe 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).

  • Dimmer function for EL displays
    Patent number: 7307645
    Abstract: A control circuit to vary the intensity of an electro luminescent display. The circuit is connected between a power source and a display and comprises a pair of conductors to be connected to the display for applying a voltage from a voltage generator. A switch controls application of the voltage from the generator to the conductors. A gating circuit connects selectively one or other of the conductors to the voltage source. A controller operates upon the switch to vary the duty cycle and upon the gating circuit to alternate periodically the relative polarity of the conductors. The voltage source includes an inductor and the switch controls current flow through said inductor.
    Type: Grant
    Filed: July 22, 2004
    Date of Patent: December 11, 2007
    Assignee: Psion Teklogix Inc.
    Inventor: Lawrence D. Forsythe