| 摘要 |
<p>PURPOSE:To increase the precision in detection of a magnetic field and the reliability, to obtain excellent sensitivity to detect a magnet and the like, and thereby to protect a magnetic recording carrier in an electronic computer room and the like, by coupling a transmission coil and a reception coil magnetically to form a detecting element. CONSTITUTION:A reception coil 6 is fitted with a magnetic core 7 formed ribbon-like of an amorphous magnetic material and is provided in a state of magnetic coupling with a transmission coil 5, so as to form a detecting element 56. When a bias magnetic field generated by a magnet M acts on the element, harmonic components of even-numbered order for a received frequency (f) appear in the coil 6, and these components are extracted through BPF10, 11 of 2f, 3f respectively and compared with each other by a comparator 12. An output obtained through comparison is displayed 13.</p> |
