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US 4,901,569 AGranted
Motion sensors
AssigneeKeystone Electronics Company Limited
InventorMing-Wah Lui
Life of this patent
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Abstract
A motion sensor comprising a permanent magnet suspended in pendulum fashion at one end of a length of cord string so as to be capable of swinging freely within an electrical coil when the motion sensor is moved. The movement of the magnet induces an emf in the coil which can be detected by simple electronic circuitry. The motion sensor is extremely simple but yet highly effective to detect both shock movement or a gentle motion.
Claims6
A motion sensor comprising:
- (i) a hollow reel of non-magnetic material having an upper end and a lower end,
- (ii) a length of wire wound around said reel to form an electrical coil,
- (iii) support means extending across said upper end of said reel,
- (iv) flexible but substantially inextensible hanger means having an upper end attached to said support means and having a lower end hanging down within said hollow reel,
- (v) a permanent magnet attached to said lower end and suspended within the hollow reel and movable in pendulum fashion relative the support means,
- (vi) detecting means linked to said coil for detecting voltages induced in said coil by pendulum movement of said magnet within said reel when motion is imparted to said motion sensor, and
- (vii) an outer cylindrical housing closed at one end and open at the other end and enclosing said reel, said reel being wedged into said open end of said housing to secure it within said housing.
4 more elements
Dependencies are inferred from the claim text.