| 摘要 |
<p>PROBLEM TO BE SOLVED: To increase a detection distance, and to detect the quality of a metal and change of an abnormal state by a noncontact method, by adding a tuning capacitor to a bridge circuit, and synchronizing the circuit in the state of brought in contact with or close to a test object. SOLUTION: When a tuning capacitor 8 is added to the bridge circuit of a metal sensor comprising a sensor coil 3 and synchronized with a frequency (f) of an oscillator 1, a Q value (capacity) of the bridge circuit is increased, and an output voltage of a sensor circuit is increased by Q times, and simultaneously selectivity is improved by Q times. Then, when the sensor is brought in contact with or close to a test object (metal), an impedance of the sensor is changed by the influence of an eddy current and a tuning point is moved, therefore the sensor is synchronized with the test object by synchronizing it again in this state. Thus, the sensor has an extreme high Q value only to the test object, and even a slight state change of the test object can be converted into a detection voltage. As a result, analysis of discrimination, flaw, damage, fatigue, abnormal quality or the like of the metal can be executed.</p> |
