| 摘要 |
PURPOSE:To diagnose the normality of a detector easily and surely, by diagnosing the frequency characteristic of the detector by switching the AC signal of an AC signal generator connected serially between the detector and a digital converter of a detection signal. CONSTITUTION:A converter 20 converting the signal of an electromagnetism detector 3 into a digital signal, a measuring device 30 measuring the resistance of the detector 3, a diagnosing device 40 determining a frequency response from data of the converter 20 and comparing the same with a frequency response measured beforehand to diagnose the normality of the detector 3, and an AC voltage generator 50 arranged in series to the detector 3 by shifting a switch SW1 onto the side of a terminal T1 when the diagnosis is performed are provided. In a plasma control system thus constituted, the detector 3 is heated by a plasma discharge, and the frequency response thereof is varied according to the temperature dependency of the circuit constant Rs of the detector 3. By switching to the output of the generator 50 in this way, the inspection of the characteristic of the electromagnetism detector can be performed simply without taking it out of its set place in whatever place it is set. |
