| 摘要 |
<p>Security apparatus (1), particularly for protecting the perimeters of sites, operable to indicate approaches, intrusions and the like, with high sensitivity and reliability, comprises a plurality of piezo-electric transducers (4) intended to be buried underground along the perimeter of the site to be protected, each piezo-electric transducer (4) comprising a cup-shape body (6) and a plate-like piezo-electric sensor (10) having a peripheral portion (11a) fixed to the cup-shape body (6).</p> |
