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RESISTANCE MEASURING APPARATUS

  • US 20090322358A1
  • Filed: 06/17/2009
  • Published: 12/31/2009
  • Est. Priority Date: 06/30/2008
  • Status: Active Grant
First Claim
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1. A resistance measuring apparatus comprising:

  • a voltage injecting unit that injects a testing AC signal into a measured circuit by applying an AC voltage to an injection coil;

    a current measuring unit that detects and measures an AC current, which is flowing in the measured circuit due to injection of the testing AC signal, using a detection coil; and

    a processing unit that calculates a resistance value of the measured circuit based on a voltage value of the injected testing AC signal and a measured value of the AC current,wherein the voltage injecting unit generates a stepped wave whose amplitude changes in synchronization with a reference clock and applies a signal based on the stepped wave as the AC voltage,the resistance measuring apparatus further includes a reference signal generating unit that synchronizes a binary signal with a same period as the AC voltage to the reference clock and outputs the binary signal as a reference signal, andthe current measuring unit converts a current flowing in the detection coil due to the injection of the testing AC signal to a voltage signal, carries out synchronous detection on the voltage signal using the reference signal, and measures a current value of the AC current based on a signal obtained by the synchronous detection.

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