| 摘要 |
<p>PURPOSE:To provide a vibration speed detecting type earthquake sensor which is never erroneously operated by electromagnetic noise and can be manufactured at low cost. CONSTITUTION:A pendulum shaft 1 having a free supporting point 2 is suspended, a control plate 6 with a slit and a brake board 7 are mounted thereon, a light emitting element 3 and a light receiving element 4 are arranged opposite to each other on the central upper and lower positions of the slit, the displacement of the control plate 6 caused by a pendulum motion by earthquake is trapped by the light receiving element to output a signal, and the control circuit of a safety device is controlled according to this signal. Since the magnitude of an earthquake estimated to cause a damage is detected by a so-called mechanical movement for trapping the displacement of the control plate late 6 by the light receiving element 4, it is never influenced by electromagnetic noise. Consequently, there is no possibility of erroneous operation, and this device can be manufactured at low cost because no electromagnetic coil is used.</p> |
