| 摘要 |
<p>A sensor system for security purposes comprises a piezo-electric device (F) attached to a member (E) in the line of stress flux such that unauthorised movement of the member will result in deflection of the piezo-electric device and generation of an electrical output. The electrical output is passed to an electronic control circuit (H) which includes filter means (LPF) for separation of signals due to high-frequency events and is arranged to transmit a signal to an alarm.</p> |
