2007 Fiscal Year Final Research Report Summary
DEVELOPMENT OF NEW ULTRASONIC SENSORS UTILIZING EVANESCENT ACOUSTIC FIELDS
| Project/Area Number |
18560324
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electron device/Electronic equipment
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| Research Institution | Tohoku Gakuin University |
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Principal Investigator |
YAMADA KEN Tohoku Gakuin University, DEPARTMENT OF ELECTRONIC ENGINEERING, PROFESSOR (80134021)
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| Co-Investigator(Kenkyū-buntansha) |
HOSHIMIYA TSUTOMU TOHOKU GAKUIN UNIVERSITY, DEPARTMENT OF ELECTRONIC ENGINEERING, PROFESSOR (40118336)
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| Project Period (FY) |
2006 – 2007
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| Keywords | measurement system / functional device / electronic devices / ultrasonic sensor / evanescent wave / energy-trapping / air-film damning |
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| Research Abstract |
1. Proximity sensing through the air-film damping effect caused by a longitudinal-mode piezoelectric vibrator has been studied. The vibrator is composed of a thin bar cut out from a 140° rotated Y-cut LiNbO_3 wafer having a glass plate on one end. The glass plate is approached to an acrylic plate served as a test object. It has been found for the vibrator operating at the first resonant frequency of 80.9 kHz that the Q-value decreases markedly from 8,000 to 1,000 in the range where the vibrator-to-object distance d is less than 0.5 mm.
2. For the case of operation at the second mode having two nodal lines, the initial Q-value decreases to 3, 500. However, the vibrator can be supported more steadily than that in the case of the first mode operation. From these results, it has been confirmed that the proposed system utilizing the air-film damping effect can be applied for a proximity sensor.
3. Trapped-energy mode thickness vibrators have been fabricated and applied for liquid level sensor
… More
s. When the surrounding region of the trapped-energy-mode vibrators, where the vibration energy decays exponentially with distance, is immersed in a liquid, the electric conductance G varies depending on the immersion depth. The experiments carried out using a thickness-extensional-mode vibrator operating at the resonance frequency of 2.01 MHz have shown that the G-value varies almost linearly with the immersion depth. It has also been found that the use of thickness-shear-mode vibrators is effective for liquids having high viscosity.
4. Equivalent network representation has been derived for length-extensional vibration modes in a side-plated piezoelectric bar with a varying parameter along it. The network model is applicable to the simulation of the operation of vibrators that have a special electrode form devised for suppressing overtone modes. The model is also effective for modeling the operation of interdigital transducers (IDTs) for excitation and detection of surface acoustic waves (SAWs). Less
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