Security system and signal carrying member thereof
First Claim
1. A signal-carrying member for a security system comprising a core surrounded by means capable of transmitting an electrical signal, an electrically-insulating layer surrounding the core and said means capable of transmitting a signal, and a semi-conductive layer surrounding the insulating layer, the semi-conductive layer incorporating throughout semi-conductive fibres which protrude from the layer when the layer is pierced, the thickness of the insulating layer being substantially less than the length of such protruding fibres whereby piercing of the semi-conductive layer and the insulating layer by an object entering from outside and moving towards the core will cause semi-conductive fibres from the semi-conductive layer to form an electrical conductive path between the semi-conductive layer and said means capable of transmitting a signal.
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Accused Products
Abstract
A security system comprising a signal-carrying member and a detector for detecting a change in the resistance of the conductive path surrounding a core of the signal-carrying member. The conductive path comprises inner and outer layers of semi-conductive tape separated by an insulating layer but interconnected at one end. The semi-conductive tape of at least the outer layer is made of fibrous material such as carbon-leaded PTFE such that when a sharp object pierces the outer layer and the insulating layer, semi-conductive fibers are dragged from the outer layer into contact with the inner layer and form a conductive bridge between the layers.
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Citations
11 Claims
- 1. A signal-carrying member for a security system comprising a core surrounded by means capable of transmitting an electrical signal, an electrically-insulating layer surrounding the core and said means capable of transmitting a signal, and a semi-conductive layer surrounding the insulating layer, the semi-conductive layer incorporating throughout semi-conductive fibres which protrude from the layer when the layer is pierced, the thickness of the insulating layer being substantially less than the length of such protruding fibres whereby piercing of the semi-conductive layer and the insulating layer by an object entering from outside and moving towards the core will cause semi-conductive fibres from the semi-conductive layer to form an electrical conductive path between the semi-conductive layer and said means capable of transmitting a signal.
Specification