Displacement sensing system
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Abstract
A displacement sensing system including an oscillator circuit having a characteristic frequency which varies as a function of a magnetic field in the vicinity thereof, an element whose position relative to the oscillator circuit is varied by a displacement, the element being operative to vary the magnetic field in the vicinity of the oscillator circuit as a function of the displacement and circuitry for sensing a change of frequency of the oscillator circuit over time (delta f/delta t) and for providing an output indication when the change in frequency of the oscillator circuit over time exceeds a threshold.
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Citations
197 Claims
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1-146. -146. (canceled)
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147. Security apparatus comprising:
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at least one displacement sensor associated with an object, said at least one displacement sensor sensing a distance of displacement;
at least one time duration sensor for sensing a duration of time said distance of displacement exceeds at least a first predetermined distance, indicative of a possible security violation; and
at least one alarm actuator operative to provide a security violation alarm in response to said duration of time exceeding at least a first predetermined duration. - View Dependent Claims (148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170)
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171. Security apparatus comprising:
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at least one displacement sensor associated with an object, said at least one displacement sensor sensing a distance of displacement;
at least one time duration sensor for sensing a duration of time said distance of displacement exceeds at least a first predetermined distance, indicative of a possible security violation; and
at least one alarm actuator operative to provide a security violation alarm when said distance of displacement exceeds said first predetermined distance for at least a first predetermined duration and is followed, within a predetermined time window, by another distance of displacement which exceeds at least a second predetermined distance for at least a second predetermined duration. - View Dependent Claims (172, 173, 174, 175)
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176. Security apparatus comprising:
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at least one displacement sensor associated with an object, said at least one displacement sensor sensing a distance of displacement; and
at least one time duration sensor for sensing a duration of time said distance of displacement exceeds at least a predetermined distance, indicative of a possible security violation, and wherein said sensor provides an output indication. - View Dependent Claims (177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194)
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195. Security apparatus comprising:
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at least one displacement sensor associated with an object, said at least one displacement sensor sensing a distance of displacement;
at least one time duration sensor for sensing a plurality of time durations during which said distance of displacement exceeds a corresponding plurality of predetermined distances, each of said plurality of predetermined distances being associated with a respective one of a plurality of predetermined durations, indicative of a possible security violation; and
at least one alarm actuator operative to provide a security violation alarm when at least one of said plurality of time durations exceeds a corresponding one of said plurality of predetermined durations. - View Dependent Claims (196, 197)
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Specification