Time domain capacitive field detector

  • US 5,730,165 A
  • Filed: 12/26/1995
  • Issued: 03/24/1998
  • Est. Priority Date: 12/26/1995
  • Status: Expired due to Term
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First Claim
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1. Apparatus for measuring the capacitance to ground of a plate, the plate electrically connected to the ground by a shunting conductor that is not a part of the apparatus, the shunting conductor substantially conducting electrical current pulses having durations greater than a first predetermined value, the shunting conductor substantially not conducting current pulses having durations less than a second predetermined value, the apparatus comprising:

  • a source of DC current charging the plate;

    a source of a voltage pulse having a duration less than the second predetermined value;

    a discharging switch having an open state and a closed state, the discharging switch moving from its open to its closed state responsive to the voltage pulse, the discharging switch connecting the plate to a charge measuring means when in the closed state, the discharging switch otherwise not connecting the plate to the charge measuring means.

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