| 摘要 |
1,261,357. Immobility alarms. NATIONAL RESEARCH DEVELOPMENT CORP. 22 Oct., 1969 [31 Oct., 1968], No. 51738/68. Heading A5R. [Also in Division G1] An apnoea alarm system for indicating when a baby's breathing has ceased, comprises an air mattress (1), Fig. 1, (not shown) divided into a plurality of compartments (2) and means for detecting differential changes in compression between different compartments, which means are connected to apparatus adapted to automatically actuate an alarm-operating switch in the abscence of a compression of the mattress after a preset time period from an immediately preceding detected compression. The compartments (2) each have an outlet duct (3) leading to a chamber 4 containing a thermistor 6. The thermistor is fed with a constant current, and the voltage changes across it are monitored and trigger a capacitor discharge switch (19), Fig. 4 (not shown) across a capacitor (15) which is fed with a constant charging current. Should breathing fail, the discharge switch (19) is not activated and the capacitor charges above a pre-set voltage and actuates alarms &c (18).
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