Hidekazu Tai

Vibration-type viscometer using a triangular bimorph transducer: measurement of high viscosity by low-frequency operation

For the measurement of very high viscosity, we attempted to use a cantilever-type viscosity sensor using a triangular bimorph with a needle. Thus, the frequency-phase characteristics of the sensor in each viscosity were investigated at a low frequency range by changing the length of the triangular bimorph. As a result, it was clarified that we could develop a viscosity sensor with high sensitivity for very high viscosities up to 100,000 mm2/s(=cSt), using frequencies below 100 Hz.

Measurement of Concentration in Particle Suspensions Using a Converged Ultrasonic Impulse with a Broad Frequency Bandwidth

As a method to measure the concentration and acoustical properties of fine particle suspensions, we proposed a new procedure using ultrasonic attenuation, which is based on the attenuation of ultrasonic waves passing through a liquid specimen. In order to carry out the experiment, we used a focused ultrasonic impulse with a broad frequency bandwidth using a plano-concave transducer instead of a continuous wave as is utilized in the conventional method. As specimens, we used some substances composed of fine particles, the acoustic properties or sizes of which differ. As a result, it was revealed that the particle concentration and acoustical properties could be instantaneously measured easily from the attenuation information in the frequency spectrum of ultrasonic pulses. It was also clarified that the plano-concave transducer had more useful features for the measurements than polyvinylidene fluoride (PVDF) transducers.

Broadband Transducer for Diagnostics Using a Plano-Concave Ultrasonic Transducer Driven by Chirp Wave

In order to obtain tomographic images with high resolution by ultrasonic diagnostic equipment, a broadband transducer that enables one to widely change the center frequency and bandwidth of the radiation ultrasonic pulse using only a probe is investigated in this study. As it is generally difficult to widely change the frequency and bandwidth, we examined the possibility of using a plano-concave ultrasonic transducer and the chirp wave as its excitation pulse. As a result, it was clarified that the center frequency and bandwidth could be controlled freely over a wide frequency range in comparison with the conventional method by using the plano-concave transducer and the chirp wave modulated by amplitude.

Vibroviscometer using a triangular bimorph transducer

A new vibroviscometer is proposed, and it was fabricated in order to prove its feasibility. The viscometer consists of a triangular bimorph transducer and a circular thin plate. The bimorph transducer consists of two piezoelectric plates and a metal shim plate, and the shim plate is sandwiched in between the piezoelectric plates so that two pairs of piezoelectric–metal‐plate (unimorph) transducers can be used separately as driving and detecting transducers. The circular plate is adhered on the acute tip of the triangular transducer at a right angle to the transducer surface. As the measurement procedure, only the circular plate driven by one unimorph transducer is immersed in the liquid and the output of the other unimorph transducer is monitored to be compared with the driving signal. It was found that the difference in the electrical phase between the driving and the monitored signals appears to be in proportion to the viscosity of liquids and that the difference remarkably appears at the range of the a...

Linear Array Probe Using Biconcave Transducers

Recently, ultrasonic transducers with high resolution have been required in the field of ultrasonic diagnosis. The biconcave transducer treated in this paper will be suitable for this purpose, because this transducer has the features of focusing and damping effects, in the case of the radiation of ultrasonic pulse waves. These features are expected to lead to high lateral and time resolutions for the detection of a small object. We try to fabricate a probe of the linear array type using the biconcave transducers for ultrasonic diagnostic equipment, then some of its characteristics are investigated to determine whether this probe is suitable for the detection of a small object by the pulse echo method.