Tokyo Shibaura Denki Kabushiki Kaisha

Tokyo Shibaura Electric Co., Ltd.

Kabushiki Kaisha Toshiba

Sadao Matsumura

Hitoshi Hirano

Sadao Takahashi

Hitoshi Suzuki

Yasuo Ebata

Katsuyoshi Fukuta

Syoichi Washizuka

Jisaburo Ushizawa

A surface acoustic wave device has been developed, such as a surface acoustic wave filter in which a plurality of electroacoustic interdigital electrodes are formed, as thin films made principally of aluminum, on the surface of a Li.sub.2 B.sub.4 O.sub.7 single crystal substrate and a surface acoustic wave resonator, in which a plurality of electroacoustic interdigital electrodes and grating reflectors for reflecting the surface acoustic wave are formed, as thin films made principally of aluminum, on the surface of a Li.sub.2 B.sub.4 O.sub.7 single crystal substrate. Here, a cut angle, at which the substrate is cut from the Li.sub.2 B.sub.4 O.sub.7 single crystal, and the propagation direction of the surface acoustic wave are so set that, when the Eulerian angle representation is (90.degree..+-..lambda., 90.degree..+-..mu., 90.degree..+-..theta.), .lambda.=38.degree. to 52.degree., .mu.=0.degree. to 5.degree. and .theta.=0.degree. to 10.degree., whereby the TCD of the surface acoustic wave device is below .+-.5 ppm/.degree.C. and coupling coefficient K.sup.2 is about 1.0%, and the propagation speed suffers almost no angular dependence.

Surface acoustic wave device

A method for controlling the shape of a single crystal. The weight of a single crystal pulled by the Czochralski method is detected, to obtain a weight signal W. The weight signal W is differentiated over time, to obtain a differential signal dW/dt. Using the differential signal dW/dt, (A.multidot.dW/dt+B).theta. is computed, to obtain an operation signal f. A and B are parameters which are determined by predetermined manufacturing conditions of the Czochralski method, and .theta. is a preset growing angle of the single crystal. The operation signal f is integrated over time, to obtain an integral signal F. The integral signal F and the differential signal dW/dt are compared to obtain a deviation signal. The heating power supplied to the crucible is controlled by use of the deviation signal, to keep the growing angle of the single crystal constant.

Method and apparatus for controlling shape of single crystal

A surface acoustic wave device having a lithium tatraborate single crystal substrate is proposed. An electro-mechanical coupling coefficient K.sup.2 of the substrate is about 1% so as to obtain a surface acoustic wave having sufficient practical energy. When cut angles of the substrate and a propagation direction of the surface acoustic wave are expressed by Eulerian angles (90+.lambda., 90.degree., 90.degree.), a thickness t of an electrode formed on the substrate falls within a region bounded by a dotted curve and an alternate long and short dash curve in FIG. 8. The dotted curve and the alternate long and short dash curve indicate the experimental relationship between the cut angle .lambda. and the thickness t when the TCD is set at 5 and -5 ppm/.degree.C., respectively. When the film thickness t is set within the above-mentioned range, the absolute value of the TCD is set at 5 ppm/.degree.C. or less. When the cut angle .lambda. is 25.degree., the TCD of the substrate becomes zero. Therefore, using the substrate having the above cut angle, the TCD becomes zero or almost zero in the electrode region and nonelectrode region of the surface of the substrate.

Temperature compensated surface acoustic wave device

A device for detecting infrared rays using the pyroelectric effect, namely a pyroelectric detector, and methods for manufacturing the pyroelectric detector, are disclosed. The pyroelectric detector comprises a pyroelectric material, an electrode for receiving infrared rays placed on one face of the pyroelectric material, a shield electrode placed at the other face of the pyroelectric material, a substrate made of a semiconductor or conductive material which is fastened to the shield electrode, the substrate having a hole corresponding in position to the position of the infrared receiving electrode and a stand to which the substrate is fastened. The method for manufacturing the pyroelectric detector comprises the steps of forming a shield electrode at one face of a pyroelectric wafer, making holes in a substrate, fastening the substrate to the shield electrode, grinding the other of the wafer, forming electrodes on the other face of the wafer for receiving infrared rays, the position of the electrodes corresponding to the position of the holes, and dicing the pyroelectric material between the holes to form a single pyroelectric detector.

Pyroelectric detector and method for manufacturing the same

An elastic surface wave device includes a transducer having an elastic surface wave propagated in the direction of 75 to 133 degrees to a Y-axis on an X-cut lithium tantalate (LiTaO.sub.3) substrate.

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Inagi, Japan

Sadao Matsumura