Hitachi, Ltd.

Sakichi Ashida

Yukio Ito

Hiroshi Takeuchi

Kazuyuki Nagatsuma

Shigeru Jyomura

Etsuji Yamamoto

Mitsutaka Hikita

Mitsuru Ishii

Kunio Yamashita

Shigeru Jyo Mura

Hirosi Takeuchi

Sigeru Jyomura

An apparatus for and a method of non-destructively determining properties of a SAW substrate, in which first and second interdigital transducers are formed in a spaced relationship on a single common piezoelectric substrate, a blocking member is formed between said transducers on the substrate for preventing an acoustic wave signal from being transferred between said transducers via the common substrate, spacers are provided for supporting a to-be-determined SAW substrate above the common substrate with a spacing left between the SAW substrate and the fingers of transducers, the SAW substrate to be placed on the spacers is positioned with respect to the transducers so that co-directional mode coupling will, in operation, effectively take place between the SAW substrate and the transducers, adherence between the SAW substrate and the spacers is secured to enhance the co-directional mode coupling, an electric signal is applied to the first transducer for transferring, due to the co-directional mode coupling, an acoustic signal to the SAW substrate along the surface of which the acoustic signal will propagate and will be transferred, due to the co-directional mode coupling, to the second transducer, and the output of the second transducer is measured.

Apparatus for and method of determining properties of saw substrates

The piezoelectric resonator of this invention consists of a piezoelectric ceramic plate which is polarized in the direction of thickness over the entire plate, two split electrodes are formed on one main surface of the piezoelectric ceramic plate, and an electrode is formed on the entire main surface opposed to the above main surface on which are formed the split electrodes. When an operating voltage is supplied to the above two split electrodes, the piezoelectric ceramic plate between the two split electrodes and the other electrode undergoes resonance in a thickness dilatational mode with a phase difference of 180.degree..

Three electrode piezoelectric ceramic resonator

An ultrasonic probe includes a resonator made of a piezoelectric ceramic material which is obtained by subjecting a ceramic composition containing 44.7 to 46.3 mol % of PbO, 50.9 to 51.7 mol % of TiO.sub.2, 1.8 to 2.7 mol % of Sm.sub.2 O.sub.3 and 0.5 to 1.0 mol % of MnO.sub.2 to poling treatment in such a manner that the ceramic composition is applied with an electric field of 60 to 80 kV/cm at a temperature of 130.degree. to 160.degree. C.

Ultrasonic probe

A piezoelectric single crystal which has a composition represented by a general formula (Ba.sub.2-x Sr.sub.x)TiSi.sub.2 O.sub.8, the value x lying within a range of 0.25.ltoreq.x.ltoreq.1.2; and a surface acoustic wave element which is so constructed as to employ surface waves that propagate on a cut plane perpendicular to the Z-axis of the single crystal, or surface waves that propagate in a specified direction on a cut plane containing the X-axis of the single crystal. The piezoelectric single crystal and the surface acoustic wave element employing it have the merits that the electromechanical coupling factor of the surface acoustic waves is great and that the temperature coefficient of delay time of the surface acoustic waves is small.

Piezoelectric single crystal and surface acoustic wave element employing

Piezoelectric ceramics containing PbO and TiO.sub.2 as its principal constituents, and further containing 0.5 to 3.7 mol-% of Nd.sub.2 O.sub.3 and 0.2 to 1.5 mol-% of MnO.sub.2. Since the piezoelectric ceramics is low in the dielectric constant and is especially small in the temperature coefficient of the delay of surface acoustic waves, it is suitable for a surface acoustic wave device. Piezoelectric ceramics in which 0.3 to 3.3 mol-% of In.sub.2 O.sub.3 is further added to the above-mentioned composition has a still smaller temperature coefficient of the delay of surface acoustic waves, and it is also possible to make this coefficient zero.

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Fuchu, Japan

Sakichi Ashida