Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1997-11-17
1998-11-17
Dougherty, Thomas M.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
H03H 900
Patent
active
058380906
ABSTRACT:
An object of the present invention is to improve an SAW propagation velocity V, an electromechanical coupling coefficient (K.sup.2), and a delay time temperature coefficient (TCD) to achieve a high-frequency SAW device and power saving and size reduction of the device. An SAW device according to the present invention includes at least diamond as a substrate material, a c-axis oriented polycrystalline LiNbO.sub.3 layer, arranged on the diamond, an SiO.sub.2 layer arranged on the LiNbO.sub.3 layer, and an interdigital transducer and uses an SAW in an nth mode (n=0, 1, 2: wavelength: .lambda. .mu.m). When the thickness of the LiNbO.sub.3 layer is t.sub.1 (.mu.m), and the thickness of the SiO.sub.2 layer is t.sub.2 (.mu.m), kh.sub.1 =2.pi.(t.sub.1 /.lambda.) and kh.sub.2 =2.pi.(t.sub.2 /.lambda.) fall within predetermined ranges. In addition, the mode of the SAW is selected. With this arrangement, an SAW device having a propagation velocity (V) of 7,000 m/s or more, an electromechanical coupling coefficient (K.sup.2) of 2% or more, and a coefficient TCD of .+-.10 ppm/.degree.C. or less, which is the stability of the device frequency with respect to the temperature, can be provided.
REFERENCES:
patent: 4037176 (1977-07-01), Ono et al.
patent: 4501987 (1985-02-01), Mitsuya et al.
patent: 5446329 (1995-08-01), Nakahata et al.
patent: 5576589 (1996-11-01), Dreifus et al.
Fujii Satoshi
Higaki Kenjiro
Kitabayashi Hiroyuki
Nakahata Hideaki
Shikata Shin-ichi
Dougherty Thomas M.
Sumitomo Electric Industries Ltd.
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