| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-sensitivity, high-accuracy rotation sensor dispensing with drilling work. SOLUTION: This rotation sensor uses an MI(magnetic impedance) element having impedance varying with an external magnetic field. A magnetometric sensor 150 having a magnetism sensing element (amorphous magnetic body) comprising the MI element is disposed outside a compressor casing 1. A permanent magnet 7 is embedded in a peripheral part of a swash plate 6 that is a rotating body. The magnet 7 and the sensor 150 are disposed so that the two can confront each other at a point of time while the plate 6 makes a turn. The sensing element of the sensor 150, since it is the high-sensitivity MI element, can detect a faint fluctuation in the magnetic field caused by the rotation of the rotating body even from outside the casing 1. Accordingly, it is not necessary to drill up the casing 1 as in the past. The working point of the MI sensor can be kept constant at all times by a negative feedback circuit. This makes it possible to detect the rotation with high sensitivity and high accuracy.
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