| 摘要 |
PURPOSE:To detect acceleration which is larger than a specific value and has a frequency within a specific band by detecting the displacement of a body which is supported in a displaceable state corresponding to the acceleration to be detected when the body is displaced by more than the specific value. CONSTITUTION:When an arm (body) 4 receives a force of acceleration and a projection part 4a is displaced by more than the specific value, the arm 4 blocks a slit 14a to cut off light from a light emitting element 16 to a photodetecting element 17. For the purpose, variation in the output signal of the element 17 is detected to detect whether the arm 4 is displaced by more than the specific quantity or not, thereby detecting acceleration which is larger than the specific value. At this time, the arm 4 vibrates according to the acceleration frequency and the output signal of the element 17 pulsates. The width of pulses is wide when the acceleration frequency is low and narrow when high, so the pulse width of the output signal of the element 17 is measured to measure the acceleration frequency. Then it is decided whether the pulse frequency is an object of detection or not, and acceleration which is larger than the specific frequency and has a frequency within the specific band is detected.
|
