Having Duty Cycle Patents (Class 219/718)
  • Patent number: 5314664
    Abstract: The flow-injection system includes a microwave oven having a flow-through reactor having a flow-through conduit located in windings around a conduit carrier for absorbing microwaves. The windings extend through the radiation cavity of the microwave oven only with a part of their length and transversely to the radiation direction. The microwave oven includes programmable adjusting means for the heating power and the heating period. Thus, in connection with a reduction flow-through reactor and an atomic absorption spectrometer, a determination of hydride formers and mercury in a material sample is possible, independently of the valence state.
    Type: Grant
    Filed: April 1, 1992
    Date of Patent: May 24, 1994
    Assignee: Bodenseewerk Perkin-Elmer GmbH
    Inventors: Michael Sperling, Dimiter L. Tsalev
  • Patent number: 5286939
    Abstract: A microwave sourced heat exchanger in an inverted, truncated frusta-pyramidal or frusta-conical shaped configuration. A heat conductive medium is carried within microwave transparent pipes toward a microwave source having one or more magnetrons along a split path of increasing parameter. The magnetrons sequentially operate in a cyclic pattern such that the respective magnetrons do not operate when their respective operating temperatures exceed their respective maximum safe operating temperatures. The sequential use of multiple magnetrons increases the efficiency and operating life of the magnetrons. The geometrical design of the microwave heat exchanger allows the heat conductive medium anywhere in the conduit to be directly exposed to microwaves. Further, the geometry of the microwave heat exchanger induces a thermal siphon when the heat conductive medium within is exposed to a microwave source placed at the exchanger's broader base.
    Type: Grant
    Filed: September 29, 1992
    Date of Patent: February 15, 1994
    Inventor: William A. Martin
  • Patent number: 5286938
    Abstract: A high frequency heating apparatus such as microwave ovens includes an inverter circuit having a switching element and converting a commercial ac power supply to a high frequency power supply by controlling "on" and "off" periods of the switching element, a magnetron driven by the inverter circuit, a counter cumulatively counting an operating period of time and a deenergization period of time of the magnetron, and a compensator for compensating an "on" period of the switching element based on a count value of the counter so that an input power to the inverter circuit is rendered constant.
    Type: Grant
    Filed: June 17, 1991
    Date of Patent: February 15, 1994
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tamotsu Takei, Hisao Karino