| 摘要 |
<p>PURPOSE: To miniaturize a magnetic-substance detection apparatus which detects whether a magnetic substance as a member to be detected exists or not in a detection position inside a nonmagnetic substance irrespective of whether a product is large or small. CONSTITUTION: A magnetic 12 of which magnetic path changes depending on whether a magnetic substance exists or not is provided inside a case 11, and a magnetic sensor 15 is provided in a position which can detect a change in the magnetic path. Then, e.g. when the operation of a gas meter is to be detected, a detection face 10a is put to a position corresponding to an iron film plate 30 on a nonmagnetic-substance-film lid 20. Thereby, when the film plate 30 is away from the detection face 10a, a magnetic path which mostly passes the magnetic sensor 15 is formed, magnetism which is comparatively strong is sensed by the magnetic sensor 15, and it is detected that the film plate 30 does not exists in a prescribed detection position. On the other hand, when the film plate 30 is brought close to the detection face 10a, a magnetic path which hardly passes the magnetic sensor 15 is formed, magnetism which is comparatively weak is sensed by the magnetic sensor 15, and it is detected that the film plate 30 exists in the prescribed detection position.</p> |
