| 摘要 |
<p>A device for measuring heartbeats of a driver using a multiplicity of optical heartbeat sensors which are dispersed about the rim of steering wheel. Fluctuation (variance) in the period of a heartbeat signal is measured and compared with a reference value to decide the presence or absence of abnormality. The presence of abnormality is signaled by a visual indication and acoustic output. The reference value is set based on the value which was obtained from the actual heartbeat measurement of the driver in a reference value setting mode. The reference value is stored in a non-volatile read/write memory to be held even when the power is off. The difference in output levels of a light receiving element between when a light emitting element is energized and when it is deenergized, is checked for each heartbeat sensor to decide whether a heartbeat signal has been actually obtained therefrom. As a result of the decision, only those heartbeat sensors actually issuing the heartbeat signals are selectively utilized for making the measurement.</p> |
