METAL STATE DETECTOR AND METAL STATE DETECTING METHOD

摘要

The state of a metal is detected precisely through simple circuitry. The metal state detector comprises a detection coil (L) arranged such that the inductance varies depending on the state of a metal, an oscillation circuit (2) which causes a phase shift in an oscillation wave depending on the variation in inductance of the detection coil (L), and a detection circuit (3) for measuring the phase shift of the oscillation wave by accumulating the phase shift. The detection circuit (3) performs oscillation wave counting processing for counting the number of oscillation waves outputted from the oscillation circuit (2) and judging whether the count reached a predetermined number N or not, and measures the accumulated phase shift of the oscillation wave based on the time required for counting the oscillation waves.