Patents by Inventor Leonardus F. P. Warmerdam

Leonardus F. P. Warmerdam 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).

  • Ballast circuit for operating a lamp
    Patent number: 6420911
    Abstract: A ballast circuit for operating a lamp provided with a voltage-current converter, the ballast circuit having a differential amplifier provided with a first input terminal for connection to a reference voltage source for generating a reference voltage, a second input terminal for connection of a reference resistor, and an output. A first current generator supplies a first current to the reference resistor. A current amplifier generates a second current and is provided with an input coupled to the output of the differential amplifier. The differential amplifier is provided with a low-pass filter. The current amplifier on the one hand and the current generator and the reference resistor on the other hand exclusively comprise mutually separate components. The ballast circuit is in addition provided with a current control circuit coupled to the current amplifier and to the current generator for influencing the first current dependent upon the second current.
    Type: Grant
    Filed: August 29, 1996
    Date of Patent: July 16, 2002
    Assignee: Koninklijke Philips Electronics N.V.
    Inventors: Leonardus F. P. Warmerdam, Hendrik Boezen