Patents by Inventor Gerald J. Dunstan

Gerald J. Dunstan 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: 4972137
    Abstract: A particle counter, of the type utilizing a Coulter(R) type aperature and a suction flow path downstream from the aperture, has a pair of electrodes on both sides of the aperture. A current is provided from the downstream electrode to the upstream electrode and pulses in the resulting voltage across the aperture are monitored to detect the passage of blood cells through the aperture. A grounded electrode is placed in the downstream flow path at a position near the package panel to isolate the cell counter from external electrical noise signals. An isolated high input inpedance amplifier is coupled to provide the monitored voltage to an inserted electrode positioned between the downstream aperture electrode and the grounded panel electrode. Because the inserted electrode and downstream electrode are then at the same voltage, no current flows through that portion of the flow path.
    Type: Grant
    Filed: May 31, 1989
    Date of Patent: November 20, 1990
    Assignee: Coulter Electronics, Inc.
    Inventors: Gerald J. Dunstan, Ian D. Gilbert