| Project/Area Number |
10555110
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
電子デバイス・機器工学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
YAMADA Ken Dept. of Elec. Commn. Eng., Tohoku University, Assoc. Professor, 大学院・工学研究科, 助教授 (80134021)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Kiyoshi Dept. of Elec. Commn. Eng., Tohoku University, Assoc. Professor, 大学院・工学研究科, 教授 (00005365)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥7,600,000 (Direct Cost: ¥7,600,000)
Fiscal Year 1999: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1998: ¥4,300,000 (Direct Cost: ¥4,300,000)
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| Keywords | ultrasound transducer / composite material / broadband / Bessel beam / nondiffracting beam / high resolution / conical / functionally-graded material |
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| Research Abstract |
The purpose of this research project is to develop a new type of ultrasound transducer that has a high resolution capability in both axial and lateral directions. The results obtained in this project are as follows :
(1) A new equivalent network has been devised for thickness vibration modes in piezoelectric plates in which the piezoelectric parameter is graded. The network has the same style as that derived for a uniform plate, however, the values of the two transformer ratios and the capacitances are all frequency dependent.
(2) The performance of functionally-graded ultrasound transducers has been studied theoretically using the equivalent network model. The transfer functions and impulse responses have clearly shown the effectiveness of the functionally-graded plates for generation of a short ultrasonic pulse.
(3) A limited-diffraction-beam transducer of weighted conical type has been designed and fabricated using a piezoelectric composite with varying fraction of the ceramic volume in the thickness direction. The transducer has been fabricated using the "dice-and-fill" technique with a tapered blade. The volume fraction of ceramic has been varied from 77% to 23%. Apodization in the poling process has been employed to facilitate the fabrication.
(4) The performance of the transducer has been tested in water. It has been confirmed that an almost uniform -6 dB beamwidth of 〜8 wavelengths has been obtained in the axial range of 〜100 mm using a transducer 17.5 mm in diameter and 173° in conical angle operating at 3.1 MHz. It has also been shown by a spike-pulse excitation that the transducer has the frequency bandwidth wider than that of a conventional transducer.
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