Patents by Inventor David R. Hearn

David R. Hearn 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: 4958365
    Abstract: A medical imaging device employs a plurality of triggered plasma cathode flash X-ray sources, each of which has an axially extending round anode rod, a cathode, and a trigger electrode. The application of a trigger pulse between the electrode and the cathode produces a burst of plasma near the cathode, the plasma containing electrons that are accelerated toward and impact the anode in a region termed the "focal spot" for producing X-rays when a voltage source applies a predetermined voltage between the cathode and anode. According to the invention, a non-conducting surface interconnects the electrode with a cathode or a conductor held at the same potential as the cathode, the application of a trigger pulse to the electrode causing flashover across said surface for producing the burst of plasma.
    Type: Grant
    Filed: June 5, 1989
    Date of Patent: September 18, 1990
    Assignee: Elscint Ltd.
    Inventors: A. Robert Sohval, Gerald Cooperstein, Shyke A. Goldstein, David R. Hearn
  • Patent number: 4592079
    Abstract: A medical imaging device employs a plurality of triggered plasma cathode flash X-ray sources, each of which has an axially extending round anode rod, a cathode, and a trigger electrode. The application of a trigger pulse between the electrode and the cathode produces a burst of plasma near the cathode, the plasma containing electrons that are accelerated toward and impact the anode in a region termed the "focal spot" for producing X-rays when a voltage source applies a predetermined voltage between the cathode and anode. According to the invention, a non-conducting surface interconnects the electrode with a cathode or a conductor held at the same potential as the cathode, the application of a trigger pulse to the electrode causing flashover across said surface for producing the burst of plasma.
    Type: Grant
    Filed: October 21, 1981
    Date of Patent: May 27, 1986
    Assignee: Elscint Ltd.
    Inventors: A. Robert Sohval, Gerald Cooperstein, Shyke A. Goldstein, David R. Hearn
  • Patent number: 4570106
    Abstract: A plasma electron source has an apertured cathode, and a housing for defining a cavity behind the aperture. A trigger electrode, in communication with the cavity, is responsive to a short-duration trigger pulse for establishing plasma in the cavity. The plasma is sustained in the cavity subsequent to the termination of the trigger pulse by a bias circuit, which biases the cavity at a relatively low voltage with respect to the cathode for a period of time much longer than the duration of the trigger pulse.
    Type: Grant
    Filed: March 20, 1984
    Date of Patent: February 11, 1986
    Assignee: Elscint, Inc.
    Inventors: A. Robert Sohval, Gerald Cooperstein, David Fleischer, Shyke A. Goldstein, David R. Hearn
  • Patent number: 4458180
    Abstract: A plasma electron source has an apertured cathode, and a housing for defining a cavity behind the aperture. A trigger electrode, in communication with the cavity, is responsive to a short-duration trigger pulse for establishing plasma in the cavity. The plasma is sustained in the cavity subsequent to the termination of the trigger pulse by a bias circuit, which biases the cavity at a relatively low voltage with respect to the cathode for a period of time much longer than the duration of the trigger pulse.
    Type: Grant
    Filed: February 18, 1982
    Date of Patent: July 3, 1984
    Assignee: Elscint Ltd.
    Inventors: A. Robert Sohval, Gerald Cooperstein, David Fleischer, Shyke A. Goldstein, David R. Hearn