Importance

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Abstract

The invention provides a vibration sensing device which is used in safety and security equipment. Such devices comprise a main inertia mass on a support assembly to form an electrical switch which in turn is part of an electrical monitoring circuit. The support assembly includes at least two stationary space-apart electrically conductive and mutually electrically insulated supports. The invention provides more than one main inertia mass and an additional inertia mass supported by at least a pair of main inertia masses. On sensing vibration all the inertia masses will resonate, the provision of the additional inertia mass increasing the number of electrical paths through which current can flow. For example, if there are first and second main inertia masses and an additional inertia mass, a signal, in addition to being transmitted across one main inertia mass from one support to the other can also be delivered from one support, through the first main mass, the additional inertia mass and the second main mass to the other support. There are thus four electrical paths where before without the additional inertia mass there were two.

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First Claim