| 摘要 |
<p>PURPOSE: To notify a user that the sensitivity adjustment has been changed and to prevent false measurement by providing a switching means for selecting either a voltage signal for detecting the amount of displacement or a reference voltage signal. CONSTITUTION: An AC voltage is applied from an excitation part 30 to the primary coil of a differential transformer 10 and the amount of displacement of an object to be measured is converted to a voltage signal by the transformer 10. The voltage signal is outputted to an operation amplification part (for measurement) 12 and an operation amplification part (for detecting sensitivity change) 14 from output terminals A and B. A voltage signal (VA+VB) becomes an AC voltage with a constant amplitude regardless of the amount of displacement of the object to be measured and a voltage (reference voltage) with a constant amplitude is outputted from an amplification part 14. An input signal switching part (switching means) 16 selects either of voltage signals from amplification parts 12 and 14 based on a control signal from a control part 24 and outputs it to a detection rectification part 18. The control part 24 compares the output value of the amplification part 14 with a value at the time of starting the measurement and shows a warning on a display 28 when there is at least a specific change.</p> |
