Patents by Inventor Schelte Heeringa

Schelte Heeringa 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).

  • Drive circuit for a flyback converter with switching transistors in bridge arrangement
    Patent number: 5412332
    Abstract: A flyback converter including a first (6) and a second (8) switching transistor, a first (10) and a second (12) rectifier diode, and a primary winding (14) of a transformer, which parts are connected in a bridge arrangement. The first switching transistor (6) receives its drive by positive feedback via a secondary winding (30), a coupling capacitor (36) and a series resistor (38, 40). Upon commutation of the voltage on the secondary winding (30) the first switching transistor (6) is turned off, a discharge diode (44) providing a discharge path for the coupling capacitor (36) in order to achieve that the first switching transistor (6) is turned on more rapidly in the next switching cycle. However, the discharge diode (44) limits the cut-off voltage on the control electrode of the first switching transistor (6), so that turning off proceeds comparatively slowly. This effect is eliminated by a voltage source (46, 48, 52) and a further switching transistor (54) which is turned on upon commutation.
    Type: Grant
    Filed: September 29, 1993
    Date of Patent: May 2, 1995
    Assignee: U. S. Philips Corporation
    Inventors: Schelte Heeringa, Geert J. Bosscha