| 摘要 |
A capacitance type motion detector adapted to monitor an infant or a person in bed to provide an alarm for apnea episodes. A conductive grid array is provided on a plastic film or the like and disposed adjacent the person to be monitored. A 50 kHz oscillator having a floating circuit ground and an output connected to an earth ground pumps the earth ground. A voltage follower preamplifier having a common circuit ground with the oscillator is connected to the grid array which picks up the 50 kHz signal. Motion, such as breathing, of the person being monitored varies the capacitance to earth ground of the grid array thereby modulating the 50 kHz signal. The modulation envelope is detected, amplified and applied to a comparator. An alarm circuit produces a first output indication for each detected motion and a second output for absence of motion for a selectable time period. The second output in an apnea monitor may produce an alarm to permit immediate attention to the person.
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