| 摘要 |
PURPOSE:To display a stable detecting function without any unnecessary electromagnetic noise by providing a Faraday effect element which has the plane of deflection rotated according to the operating state of a magnetic field to a magnetic circuit which passed through a body to be detected. CONSTITUTION:When a tooth 14a of a gear 14 is not present on the detection surface of a detection part 11, the magnetic circuit is formed between permanent magnets 23 and 22 and a magnetic material plate 22 and a backward magnetic fields operates on the Faraday effect element 21, so that no magnetic field is established. On the other hand, when a tooth 14a is present between the magnet 24 and element 21 closely, a magnetic path is formed through the tooth 14a and a large magnetic field operates on the Faraday effect element 21. Consequently, the reflected light which is reflected by a total reflection coating 21a, transmitted through a deflection beam splitter 26, and detected by a photodetector 19 varies in intensity. Therefore, this operates as a rotating speed detector for the gear 14. |
