To provide an ultrasonic transmitter/receiver suitable for sanitary or the like by employing a diaphragm having or including a curved surface at the part touching an ultrasonic oscillator thereby improving the signal/noise ratio (S/N).
When an ultrasonic excitation signal is fed to a transmitting section 6, an ultrasonic oscillator 62 oscillates and the oscillation is transmitted through a diaphragm 61 into a fluid to be measured. The ultrasonic wave propagates through the fluid to be measured while being subjected to phase variation due to Karman's vortex and arrives at a receiving section 7 where a diaphragm 71 is oscillated and the oscillation is transmitted to an ultrasonic oscillator 72. Number of Karman's vortex being generated can be determined by detecting the phase variation from the output ultrasonic signal by means of a detector and thereby the flow rate can be determined. Since the diaphragm 61, 71 has a curved surface touching the oscillator 62, 72, the transmitting ultrasonic wave advances in the direction of normal at each point on the curved surface. Consequently, the ultrasonic wave arriving at the diaphragm 71 is reflected but the reflected wave scarcely interfere with the transmitting wave.
NOGUCHI MASANORI
INOUE TAKATSUNE
FUJITA AKIO
