| 摘要 |
PURPOSE:To remove the factors of malfunction by comparing a detection output with respective reference power source potentials by both a crest value detector and a noise detector. CONSTITUTION:The detection output inputted to a terminal 6 is compared with a crest value and the VREF1 of a reference power source 8 for crest value comparison and adjusted to the values. When the bias voltage of a bias power source 14 for a DC amplifier is adjusted and a current begins to flow to the diode 33 of the output circuit of a differential amplifier composed to transistors(TR) 25 and 26 in the presence of an input electric field having a certain value, currents begin to flow to TRs 28 and 21 at the same time. A current, therefore, begings to flow to a resistance 46 and the voltage at the input terminal of a TR 20, i.e. reference power terminal 12 of a comparator constituting a noise detector drops. Consequently, a comparing voltage for noise detection drops and noises are made difficult to detect, thereby precluding malfunction.
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