| 摘要 |
<p>The anti-intrusion apparatus uses a plastic optical fibre in a curtain type structure to cover a passageway. In the closed position the fibre (1) winds across the opening between supports (2) on either side. The fibre curtain can be raised clear of the opening by pulling cables (5). The fibre supports are held on a column (103) which on one side is spring mounted (7). The fibre has a break with the ends (201,301) of the break nearly aligned. A light signal is transmitted through the fibre an in the undisturbed state provides a reference. An intrusion attempt stresses the fibre and moves the sprung column. This causes a deviation between the fibre ends and generates an alarm.</p> |
