| 摘要 |
PURPOSE:To eliminate countermeasures taken against external noises, simplify construction and measure with higher accuracy by measuring stress of a magnetic material by converting it into an oscillation frequency of a rectangular wave form oscillation circuit. CONSTITUTION:A sensing section 1a is connected between the inversion input terminal 7 and output terminal 9 of a differential amplifier 6, and a circuit with a sensing section 1b and resistance R1 in series is connected between a non-inversion input terminal 8 and output terminal 9, and, further, R1 is connected between the terminal 7 and an earth terminal, and R2 between the terminal 8 and the earth terminal, Zenor diodes D1 and D2 reversely connected between the terminal 9 and the earth terminal to form a rectangular form wave oscillation circuit. When the tensile stress in a magnetic material 5 varies, the inductances of the sensing sections 1a and 1b change relatively, and the change is sensed and grasped as a change in oscillation frequency of the oscillation circuit, and the stress in the magnetic material 5 is sensed. |
