| 摘要 |
A security enclosure is formed from layers of flexible material. One layer (11;18) carries a flexible semiconductive line (10,13) arranged to extend over the whole area of the enclosure. Any interruption of the line by unauthorised opening of the enclosure changes the resistance of the line and so can be detected by a monitoring circuit. Further, two layers (17) of semiconductive fibres also cover the whole area of the enclosure and are separated by an insulating layer (16). The length of the fibres is greater than the thickness of the insulating layer (16) so that if the enclosure is pierced fibres from one layer (17) will be forced into contact with fibres from the other layer (17). This will change the combined resistance of the layers and this can also be detected by a monitoring circuit. The two measures can be used separately. |
