| 摘要 |
PROBLEM TO BE SOLVED: To detect the rotational speed of a body in a medium or a flowing speed of a liquid flowing, in a tube. SOLUTION: When an input signal, with a carrier frequency (F<SB>0</SB>), is impressed on a transducer of thickness vibration mode comprising a 1st electrode 2 and a 2nd electrode 3, the water being in contact with a bottom of an ultrasonic composite body composed of a piezoelectric substrate 1, the transducer of thickness vibration mode, and an interdigital transducer 4, is irradiated with longitudinal waves from the inter digital transducer 4. If the longitudinal waves are reflected by the rotating body 7 in the water, a reflection wave, having a reflection angleα, is transformed into a delayed electrical signal, having a Doppler transition frequency (F) by the interdigital transducer 4. The rotational speed (S) of the rotating body 7 is calculated from the difference (F-F<SB>0</SB>) of the carrier frequency (F<SB>0</SB>) and the Doppler transition frequency (F). COPYRIGHT: (C)2004,JPO |
