| 摘要 |
PROBLEM TO BE SOLVED: To provide a pulse wave detector difficult to generate noise due to body movement. SOLUTION: An ultrasonic wave A is oscillated from a transmitter 11 and an ultrasonic wave B propagated in a body including an artery 2 is received by a receiver 21. When a pulse wave does not exist in the part of the artery 2 propagating the ultrasonic wave A (a), the ultrasonic wave A is propagated to the receiver 21 without being attenuated. When the pulse wave 3 exists (b), the oscillated ultrasonic wave A is remarkably attenuated at the part of the pulse wave 3 and propagated to the receiver 21. In this embodiment, an ultrasonic wave varying in attenuation factor depending on the presence/absence of the pulse wave 3 is received by the receiver 21 to detect the pulse wave from the variation of the amplitude of the received ultrasonic wave. In addition, even when the pulse wave 2 moves to the side of a body surface 1 by body movement E (c), an ultrasonic wave D received by the receiver 21 varies in a phase and frequency compared with the oscillated ultrasonic wave A but a bloodstream quantity never varies, thereby the amplitude never varies and consequently the ultrasonic D never becomes noise in this device detecting an amplitude.
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