| 摘要 |
PURPOSE:To increase the degree of detection accuracy, by a method wherein magnetic flux is concentrated on a point in the longitudinal direction of an iron core, and the displacement amount of the iron core is detected according to the difference between the detected values of coils facing to each other. CONSTITUTION:An AC voltage is applied to each of primary coils 151-154 from a constant-frequency constant-level oscillator 17 so that the ends of cores 111 and 113 are magnetized to the same polarity while the ends of cors 112 and 114 are magnetized to the opposite polarity at the same point of time. Similarly, secondary coils 161 and 163 generate voltages with the same polarity, and coils 162 and 164 also generate voltages with the same polarity. The output voltages of the secondary coils 161-164 are applied to rectifiers and band-pass filters 181-184, together with amplifiers 191-194 respectively. The outputs of the amplifiers 191 and 192 are applied to the positive input terminals of differential amplifiers 201 and 202 respectively, while the outputs of the amplifiers 193 and 194 are applied to the negative input terminals thereof respectively. The output of the differential amplifier 201 or 202 obtained according to the displacement of a core axis 21 is fed to a microcomputer MPU through the amplifier 201 or 212 and an A/D converter ADx or ADy, and an average value of the displacement amounts is displayed as at CD. Thereby, the degree of displacement detection accuracy is increased. |
