Seiko Epson Corporation

Rutgers, The State University of New Jersey

Seikon Epson Corporation

Shigeo Kanna

Takashi Yamazaki

Keigo Iizawa

Akihito Uetake

Masako Tanaka

Yook-Kong Yong

Michiaki Takagi

Eishi Momosaki

Makoto Eguchi

Mihir S Patel

A surface acoustic wave device includes: a quartz substrate; and at least a single-type IDT electrode provided on a surface of the quartz substrate for exciting a Rayleigh surface acoustic wave in the upper limit mode of the surface acoustic wave stop band with the following relationships satisfied;

Surface acoustic wave device and electronic apparatus

An angular velocity sensor includes a protrusion protruding in a Y'-axis direction and extending in an X-axis direction on a main surface of a rotated Y cut quartz plate, and an excitation electrode and a detection electrode formed on the main surface adjacent to this protrusion. This excitation electrode excites thickness-shear vibration in the X-axis direction on the quartz substrate, exiting vibration on the protrusion. Then, the protrusion is bent and displaced due to Coriolis force acting in a direction orthogonal to the vibration of the protrusion corresponding to a rotation around an Y&#x2032; axis. This displacement at the protrusion is applied to the quartz substrate as stress. The detection electrode detects change of this stress, thereby angular speed added to the angular velocity sensor is detected.

Piezoelectric vibration angular velocity sensor

To provide a transducer that can detect the rotation of the transducer with high degree of accuracy, a transducer includes a pair of oscillating reeds extending in the Y-direction to generate a first oscillation to generate a Coriolis force corresponding to the rotation of the transducer, a beam extending in the X-direction and connected to the pair of oscillating reeds, a first detecting unit provided on the beam to detect deformation of the beam due to a second oscillation of the pair of oscillating reeds caused by the Coriolis force, a base member to support the beam, a first connecting device to connect one end of the beam and the base member, and a second connecting device to connect the other end of the beam and the base member.

Transducer, electronic equipment, and method of adjusting frequency of transducer

The invention miniaturizes a surface acoustic wave device on which a plurality of surface acoustic wave elements are disposed and connected together in parallel on a plate, and provides a good temperature characteristic in a wide temperature range. A surface acoustic wave device according to the invention includes a plurality of surface acoustic wave elements disposed on a main surface of a quartz plate cut out with a Euler angle at (0&#xb0;, 113&#xb0; to 135&#xb0;, +/&#x2212;(40 to 49)&#xb0;). Surface acoustic waves have propagation directions '&#x3c8;' which are different each other. When the Euler angle is set at (0&#xb0;, &#x3b8;, &#x3c8;), it is possible to reduce differences in each propagation direction by setting each propagation angle so as to satisfy a formula: &#x3c8;=0.3295&#x3b8;+3.3318&#xb0;+/&#x2212;1.125&#xb0;. This makes it possible to decrease the angle among the surface acoustic wave elements, and thereby miniaturizes the surface acoustic wave elements.

Surface acoustic wave device and method of adjusting a temperature characteristic of the same

The invention provides an in-plane rotational ST-cut SAW resonator that is formed of an in-plane rotational ST-cut crystal plate having Eulerian angles of (0&#xb0;, 113&#xb0; to 135&#xb0;, and &#xb1;(40&#xb0; to 49&#xb0;)). The in-plane rotational ST-cut SAW resonator can include an interdigital transducer (IDT) electrode for exciting a Rayleigh wave on the main surface. The ratio Lt/Pt of the electrode width Lt and the interelectrode pitch Pt of the IDT electrode is 0.5 or more and 0.65 or less. Accordingly, a reduction in the fluctuation in resonance frequency relative to the variations in an IDT electrode of a surface acoustic wave device by using the in-plane rotated ST-cut crystal plate around the Z'-axis can be achieved.

Surface acoustic wave device and communications apparatus using the same

The invention provides a method for adjusting the temperature-dependent property of a surface acoustic wave device is provided,, The method is appropriate for a temperature-dependent property that is expressed by a cubic function of a surface acoustic wave device using an in-plane rotated ST cut quartz crystal plate. The invention therefore provides a method for adjusting the temperature-dependent property of a surface acoustic wave device using an in-plane rotated ST cut quartz crystal plate having Euler angles of (0&deg;, 113-135&deg;, &plusmn;(40-49&deg;)). The range of Euler angles is defined so that the temperature-dependent property of the surface acoustic wave device, using an in-plane rotated ST cut quartz crystal plate having the temperature-dependent property expressed by a cubic function, has an extreme value within the temperature range of &minus;40 to &plus;85&deg; C., and the temperature-dependent property is rotated about the inflection point to minimize the frequency fluctuation within the operational temperature range by using appropriate regions.

Method for adjusting the temperature-dependent property of a surface acoustic wave device and a surface acoustic device

The invention provides a surface acoustic wave device which uses an in-plane rotated ST cut quartz crystal plate around the Z&prime;-axis, and which has a large reflection coefficient of the Rayleigh wave. Comb teeth-like IDT electrodes are provided and reflectors to trap the Rayleigh wave are provided on both sides of the IDT electrodes on the principal surface of the in-plane rotated ST cut quartz crystal plate. The electrode width and pitch at the IDT electrodes are defined as L , P , the width and pitch of short-circuit electrodes at the reflectors as L , P , and the thickness of the IDT electrodes and the short-circuit electrodes side as H and H . If the electrode widths and pitches are set up so that either or both of L /P and L /P become 0.32&plusmn;0.1, this enables maximizing the reflection coefficient and achieving the miniaturization of device itself by reducing the number of the short-circuit electrodes.

Surface acoustic wave device

A high-precision surface acoustic wave (SAW) device improves the frequency-temperature characteristics of a conventional surface acoustic wave device several-fold. In this high-precision surface acoustic wave device, two one-port SAW resonators, or two two-port SAW resonators, alternatively, two one-port-resonator-type, two-port-resonator-type or transversal-type filters are placed in parallel with each other. Further, these resonators or filters are excited and are elastically coupled to each other in such a way as to be in an oblique symmetry mode. Moreover, the frequency-temperature characteristics of the two elements are made to differ from each other. Furthermore, a flat frequency-temperature characteristic, which cannot be realized by a single element, is realized by being synthesized from the frequency-temperature characteristics of the two elements.

Surface acoustic wave device and method for designing same using

A motor control apparatus is provided which is capable of preventing large, accidental switching surges and suppressing switching surges that hamper efforts to improve the efficiency of PWM control inverters. The motor control apparatus has a PWM control inverter and axial position detector 3 that detects the position of the rotary axis of motor 14. Gate drive circuit 1 of the PWM control inverter comprises decoder circuit 4, correction gate circuit 5, and logical AND circuit 6. The correction gate circuit 5 sets a time difference at the change point for PWM signals and at the change point for commutation signals.

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Suwa, Japan

Shigeo Kanna