Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1988-05-09
1989-09-26
Budd, Mark O.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
310312, 310324, 310326, 310351, 310365, 310366, 310369, H01L 4108
Patent
active
048703133
ABSTRACT:
For the purpose of utilizing the characteristic in a vibration energy entrapping mode of a higher order symmetric or asymmetric mode vibration generated when a piezoelectric resonator is excited, there are provided a portion having a cutoff frequency f.sub.2 about an energy entrapping portion having a cutoff frequency f.sub.1 for strongly exciting a higher order symmetric or asymmetric mode vibration and at least one energy absorbing portion having a cutoff frequency f.sub.3 (at least f.sub.1 and f.sub.3 <f.sub.2). The size of the energy entrapping portion (electrode), amount of plateback (f.sub.2 -f.sub.1)/f.sub.2, the substrate thickness and a gap between the energy entrapping portion and the energy absorbing portion are selected such that the vibration energy of the overtone vibration whose orders are equal to or higher than the n-th overtone is substantially entrapped in a portion near the periphery of the energy entrapping portion, while the vibration energy of overtone vibrations of (n-2)th order or lower order including the fundamental vibration is caused to spread over the entire body of the substrate.
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Hirama Kouichi
Shouzi Tomokazu
Tanaka Yoshiaki
Budd Mark O.
Toyo Communication Equipment Co., Ltd.
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