Sanyo Electric Co., Ltd.

Other

Yasutaka Shimizu

Kosuke Takeuchi

Kenichi Shibata

Yasumi Kobayashi

Yasuhiro Hirao

Kuniyuki Matsui

Yusuke Takahashi

Tateo Kondo

Masayuki Fujita

Yuji Hamada

Masami Ikeda

Takeshi Sano

Takanori Fujii

Toshiharu Tanaka

The invention provides a surface acoustic wave device which has a thin film formed on a surface of a substrate adapted to excite longitudinal wave-type surface acoustic waves, longitudinal wave-type quasi surface acoustic waves or longitudinal wave-type surface skimming bulk waves to thereby give an increased electromechanical coupling coefficient and at the same time minimize the temperature coefficient of delay time. For example, in a surface acoustic wave device having an aluminum thin film formed on a surface of a lithium tantalate substrate, the direction of propagation of longitudinal wave-type quasi surface acoustic waves is (40 deg to 90 deg, 40 deg to 90 deg, 0 deg to 60 deg) as expressed in Eulerian angles and within a range equivalent thereto, and the product of wave number of longitudinal wave-type quasi surface acoustic waves and the thickness of the thin film is at least 1.0, preferably in the range of 1.3 to 2.0. The device provided exhibits higher performance than in the paior art.

Surface acoustic wave device

In a resonator-type surface acoustic wave filter comprising a lithium tantalate substrate, lithium niobate substrate or lithium tetraborate substrate having a cut plane of high velocity, the direction of propagation of surface acoustic waves is set within the range of (40 deg to 90 deg, 40 deg to 90 deg, 0 deg to 60 deg) as expressed in Eulerian angles, and the capacitance Cos of the series resonators and the capacitance Cop of the parallel resonators are set within a predetermined range formulated with the center frequency taken as a parameter. Optimum ranges of the required design parameters are thus clarified to assure the resonator-type surface acoustic wave filter of higher performance.

Surface acoustic wave filter with optimized parallel and series

In a resonator-type surface acoustic wave filter comprising a lithium tantalate substrate, lithium niobate substrate or lithium tetraborate substrate having a cut plane of high velocity, the direction of propagation of surface acoustic waves is set within the range of (40 deg to 90 deg, 40 deg to 90 deg, 0 deg to 60 deg) as expressed in Eulerian angles, and the frequency difference .increment.f between the resonance frequency frs of series resonators and the resonance frequency frp of parallel resonators is set within a predetermined range formulated with the center frequency, the capacitance Cos of the series resonators and the capacitance Cop of the parallel resonators taken as parameters. Optimum ranges of the required design parameters are thus clarified to assure the resonator-type surface acoustic wave filter of higher performance.

Surface acoustic wave filter with range of a frequency difference

Organic electroluminescent elements capable of operating at a low driving voltage, leading to saving of electric power and operating cost for a driving circuit. In an organic electroluminescent element in which a hole transport layer and a luminous layer are formed between a hole injecting electrode layer and an electron injecting electrode layer which are oppositely arranged in a pair and in which the hole transport layer is overlaid on the hole injecting electrode layer, the hole transport layer is doped with a hole injection material at least at a region near the interface between the hole transport layer and a hole injecting electrode. The hole injection material has an ionization potential which is lower than that of the material of the hole transport layer and higher than that of the material of the hole injecting electrode layer.

Organic electroluminescent elements

Growing community of inventors

Hirakata, Japan

Kosuke Takeuchi