Patents by Inventor John W. Blackmore

John W. Blackmore 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: 5107185
    Abstract: A passive, resonant starting circuit for an electrodeless HID lamp includes a starting coil that is shielded from stray capacitances that would otherwise result in detuning the resonant circuit and hence decreasing efficiency. The starting circuit further includes a capacitance coupled in series with the starting coil and another capacitance coupled in parallel with the coil. In a preferred embodiment, the starting coil is enclosed in a conductive cylindrical housing which functions as both a shield from external capacitances and the resonant capacitance in parallel with the starting coil. The housing has a lengthwise gap in order to prevent the housing from acting as a short circuit secondary with respect to the starting coil. A conductive disk is mounted to the ground end of the housing to increase shielding even further. The parallel resonant capacitance is determined by the length of the housing and the distance between the coil and the housing.
    Type: Grant
    Filed: June 24, 1990
    Date of Patent: April 21, 1992
    Assignee: General Electric Company
    Inventors: Sayed-Amr A. El-Hamamsy, John W. Blackmore