| 摘要 |
<p>PROBLEM TO BE SOLVED: To achieve high resolution by forming a magnetic circuit via an object to be detected at a magnetic element for applying fixed magnetic field, by causing a great Barkhausen jump by changing the magnetic field due to the behavior of the object to be detected, and by taking out a pulse signal. SOLUTION: Flux from a permanent magnet 41 for constituting a magnetic circuit formation member 4 passes through a detection part 4A. When a tooth 10 of the gear of the object to be detected reaches the detection part 4A, the strength of a magnetic field is changed due to the recesses and projections. When the tooth 10 of the gear approaches the detection part 4, the flux is concentrated to the detection part 4A, an external magnetic field to a magnetic element 1 is reduced, and the soft layer of the magnetic element 1 is magnetized oppositely to a hard layer for setting. On the other hand, when the tooth 10 of the gear leaves the detection part 4, the flux is not concentrated, the external magnetic field to the magnetic element 1 is increased, the magnetic field is reversed, the magnetic field in the same direction as the hard layer is added, and a great Barkhausen jump is generated when critical strength is exceeded, thus generating a pulse voltage in a detection coil 2 and achieving detection regardless of the speed of the tooth 10 of the gear.</p> |
