Apparatus and method for sensing an object within a monitored zone
First Claim
Patent Images
1. A sensor module comprising:
- a sensor operative to sense a condition of a monitored zone and provide a sensor signal having an electrical characteristic which varies as a function of the sensed condition;
a first circuit operative to perform a first transfer function operation on the sensor signal and provide a first signal having a characteristic that varies as a function of the sensor signal;
a second circuit operative to perform a second transfer function operation on the sensor signal and provide a second signal having a characteristic that varies as a function of the sensor signal;
a comparator operative to compare the first and second signals and provide a comparator output signal having a characteristic that varies between at least two conditions as a function of the first and second signals; and
a third circuit operative to determine an indication of the number of transitions between the at least two conditions of the comparator output signal, said third circuit operative to determine a change in the condition of monitored zone indicative of the presence or absence of an object within the monitored zone based on the indication of the number of transitions between the at least two conditions of the comparator output signal.
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Abstract
An apparatus for detecting the presence or absence of an object within a monitor zone includes a sensor (12) operative to sense a condition of the monitored zone (Z) and provide a sensor signal indicative thereof. The sensor signal is processed, preferably according to two different transfer functions, to provide first and second signals that vary based on the sensor signal. A comparator (46) provides a comparator signal that varies as a function of the first and second signals. Additional circuitry (58) is operative to provide an indication of the presence or absence of an object within the monitored zone (Z) as based on the comparator signal.
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Citations
26 Claims
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1. A sensor module comprising:
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a sensor operative to sense a condition of a monitored zone and provide a sensor signal having an electrical characteristic which varies as a function of the sensed condition; a first circuit operative to perform a first transfer function operation on the sensor signal and provide a first signal having a characteristic that varies as a function of the sensor signal; a second circuit operative to perform a second transfer function operation on the sensor signal and provide a second signal having a characteristic that varies as a function of the sensor signal; a comparator operative to compare the first and second signals and provide a comparator output signal having a characteristic that varies between at least two conditions as a function of the first and second signals; and a third circuit operative to determine an indication of the number of transitions between the at least two conditions of the comparator output signal, said third circuit operative to determine a change in the condition of monitored zone indicative of the presence or absence of an object within the monitored zone based on the indication of the number of transitions between the at least two conditions of the comparator output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A sensing apparatus comprising:
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a sensor operative to sense a condition of a monitored zone and provide a sensor signal indicative thereof; means for processing said sensor signal to provide first and second signals, each of said first and second signals having a characteristic that varies differently as a function of the sensor signal; a comparator operative to compare the first and second signals and to provide a comparator signal which varies between at least two conditions as a function of the first and second signals; and circuitry responsive to said comparator signal and operative to provide a signal indicative of the presence or absence of an object within the monitored zone based on detecting transitions between said at least two conditions of the comparator signal. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A method for detecting the presence or absence of an object within a monitored zone, said method comprising the steps of:
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sensing a condition of the monitored zone; providing a sensor signal indicative of the sensed condition; performing transfer function operations on the sensor signal to provide first and second processed signals; comparing the first and second processed signals to provide a comparison signal having a characteristic that varies between at least two conditions as a function of the first and second processed signals; detecting transitions between the at least two conditions of the comparison signal; and providing an indication of the presence or absence of the object within the monitored zone as a function of the detected transitions. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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Specification