| 摘要 |
PURPOSE:To make an apparatus inexpensive by detecting a slight amount of magnetism by using a magnetism measuring method utilizing magnetic saturation, a position detecting method and conversion from an analog signals to a digital signal. CONSTITUTION:A material for wood member 1 having an adhesive layer 2 mixed with permanent magnetic powder is passed through a detecting head 3. The output of the head 3 is amplified by a tuning amplifier 5, and is further phase-compared with a reference signal in a phase detector 6, from which the error signal voltage corresponding to a phase difference is generated. The error signal voltage is integrated in an integrating circuit 9, after which it is converted to a digital signal by a comparator COMPR. This output is used as a control signal for driving a relay etc. |
