| 摘要 |
<p>PROBLEM TO BE SOLVED: To specify the magnetic pole of a magnet in an object to be measured and detect the object in fail-safe by providing such a means to applying a constant magnetic field in a predetermined range which can lower the impedance of a saturable magnetic body in the sensor part. SOLUTION: A sensor part 10 is formed by winding a primary coil 12 and a secondary coil 13 around a saturable magnetic body such as an amorphous core 11. An a.c. power supply 14 is connected to the coil 12 through a resistance R, and further a d.c. power supply 15 is connected thereto in series. The power supply 15 is used as a means to apply a constant magnetic field with specified area to the core 11 in advance so that the impedance of the core 11 may be lowered Then the direction of the constant magnetic field for the core 11 is determined in advance to set the magnetic operation point in correspondence with the counter magnetic pole of the magnet to be detected, so that the magnetic pole as well as the position of the magnet can be specified and detected. In addition, when the object to be measured is close to the magnet, the output is generated at high level, and when the object to be measured does not exist, the output is generated at low level, thereby obtaining fail-safe.</p> |
