| 摘要 |
PURPOSE:To improve the reliability of a seismograph by providing a control part having a counting circuit which receives and integrates an on-off signal from the switching means of a detection part and a level deciding circuit which decides earthquake motion of different level from the output of the counting circuit. CONSTITUTION:When the switch 11 of the detection part A is turned off by earthquake motion, the counting circuit 21 of the control part B increases in counted value every time the switch 11 changes from an on state to an off state and its counted value is outputted to a D/A converting circuit 22 and a level deciding circuit 23. The circuit 22 converts the counted value into an analog signal SA, which is fed back to the electromagnet 12 of the detector A. The signal SA, on the other hand, is used as an analog measurement output to drive external equipment. The signal SA increases with the counted value of the circuit 21 on every operation of the switch 11 to turn on the switch 11, so the magnetic field produced by the electromagnet 12 increases, and consequently the switch 11 does not turn off unless larger earthquake motion is inputted to the detection part A. The output of the circuit 21 led to the circuit 23, on the other hand, is compared with a preset earthquake decision level and a level decision signal SL is outputted when said output exceeds the set value. |
