| 摘要 |
PURPOSE:To perform a safe and sure operation without requiring a power source under a difficult external condition such as explosive atmosphere or interfering radio wave by further connecting an optical fiber to a light emitting diode connected to an element formed by winding a detecting coil on a slender beam ferromagnetic body. CONSTITUTION:When a downward weak auxiliary magnetic field is given from an auxiliary magnet 7 arranged close to a slender beam ferromagnetic body 1a to the magnetic body 1a, and a main magnet 8 is approached in the arrowed direction (a) to give an upward strong magnetic field thereto, the magnetizing direction of the magnetic body 1a is reversed, a pulse voltage having a half- width of 15-20mus is generated in a coil 1b, and a light emitting diode 2 momentarily emits light. This light is guided to a photosensitive element 6 arranged in the environment free from interfering radio wave by an optical fiber 5, and converted into an electric signal. Since the constitutive member sealed by a case 3 receives no battery and constitutes one unit requiring no maintenance, the change of battery is not required, and the device has no possibility of inducing explosion even if it is set in explosive atmosphere. |
