| 摘要 |
A security enclosure is formed from layers of flexible material. Two layers 17 of semiconductive fibres 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 so that if the enclosure is pierced, fibres from one layer will be forced into contact with fibres from the other layer. This will change the combined resistance of the layers and can be detected by a monitoring circuit. A further layer 18 may be provided which carries a semiconductive line. Any interruption of the line by unauthorised opening of the enclosure changes the resistance of the line and this may also be detected by a monitoring circuit. <IMAGE> |
