| 摘要 |
<p>PURPOSE: To remove artificial signals due to movements of a patient from desired signals by providing a zone filter which can be selectively made to function. CONSTITUTION: A zone filter which can be selectively made to function in order to remove artificial signals by movements from desired signals, is provided. That is, a device to detect signals by movements, judges whether effects due to movements exist or not by checking the amplitude of an input AC signal and a change of the frequency. When the effects due to movements do not exist, the zone filter is tuned to the pulse conforming to the determination of a normal oximeter algorithm. Also, when signals due to movements exist, the operation of an AGC device is stopped, and a gain level is fixed, and the zone filter is constituted of a feedback loop, and since the output of the zone filter is an approx. sine wave shape, the output of the frequency detector to determine the output frequency of the zone filter, passes through a low zone loop filter, and directly tunes the zone filter. Therefore, when signals due to movements exist, the zone filter can be kept tuned to the pulse, and the filter can selectively remove signals due to movements during an operation by following a change of the pulse.</p> |
