Patents by Inventor John D. Duff

John D. Duff 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: 6043639
    Abstract: There is provided a detector for detecting conductive contaminants entrained in an airflow. The detector comprises first and second electrically conductive meshes mounted in a spaced apart relationship to provide an operational gap. Each of the meshes is sized to provide a relatively large surface for substantially intersecting the airflow and is sufficiently porous so as not to substantially attenuate the airflow. The meshes form part of an energizable electric circuit wherein the operational gap constitutes a discontinuity of the circuit. The detector includes a capacitor connected in parallel to the portion of the circuit containing the operational gap for releasing a charge stored in the capacitor through the circuit discontinuity when one of the conductive contaminants simultaneously contacts the first and second meshes. The detector further provides for indication of a discharge of the capacitor and thereby the presence of one of the airborne conductive contaminants entrained in the airflow.
    Type: Grant
    Filed: December 1, 1997
    Date of Patent: March 28, 2000
    Assignee: Celestica International Inc.
    Inventors: Peter Arrowsmith, John D. Duff