Patents by Inventor Robertus Antonius Johannes Keijser

Robertus Antonius Johannes Keijser 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).

  • Publication number: 20100026210
    Abstract: A driver (10) for driving a gas discharge lamp (L) comprises a current generator (1; 2) for generating a lamp current with a main lamp current component and, for arc-straightening purposes, a ripple current component. A controller (3) controls the current generator such as to set the ripple frequency (fR) and ripple amplitude (M). A memory (5) contains data defining a set point (SP) for the ripple frequency and ripple amplitude. A measuring device (4) provides at least one measuring signal indicative of arc curvature and arc stability. The controller is capable of operating in a ripple optimization mode in which the controller makes small adjustments to the ripple frequency and ripple amplitude to find improved arc-straightening, and, if such improvement is found, controls the current generator on the basis of the adjusted set point or otherwise resumes operation on the basis of the original set point (SP) in the memory (5).
    Type: Application
    Filed: February 11, 2008
    Publication date: February 4, 2010
    Inventors: Robertus Antonius Johannes Keijser, Jerzy Janczak, Ronald Edwin Lavooi, Bennie Simpelaar
  • Publication number: 20080231206
    Abstract: Method of driving a high-pressure gas discharge lamp during its steady-state operation, wherein a steady-state current signal is sent through the lamp for maintaining a discharge arc in the lamp, comprising the step of comparing the lamp conductivity response to a current step in said current signal with reference parameters; and in response to said comparison at least one of the following steps: stopping the current supply to the lamp, generating a signal indicating the end-of-life status of the lamp, changing the steady-state current through the lamp, changing the steady-state waveform of the current signal through the lamp, and generating a signal indicating the lamp type, wherein said current step is obtained by sending a current pulse which is superimposed on said steady-state current signal through the lamp.
    Type: Application
    Filed: January 18, 2005
    Publication date: September 25, 2008
    Inventors: Winston Donald Couwenberg, Robertus Antonius Johannes Keijser, Jacobus Marinus Maria Claassens, Bennie Izaak Pieter Simpelaar