Kabushiki Kaisha Suwa Seikosha

Seiko Epson Corporation

Eishi Momosaki

Michiaki Takagi

Shigeru Kogure

Minoru Inoue

Shigeo Kanna

Kikuo Oguchi

Yoshinori Ikusaka

Ogata Toshiaki

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

Saw device

An oscillator circuit for simultaneously outputting two frequency signals comprises a single resonator vibrating in two modes at different frequencies, an amplitude modulating circuit for modulating one of said two frequencies with a third frequency, a feedback circuit receiving the output of the amplitude modulating circuit, a detector demodulating the amplitude modulated signal, the demodulated signal being the third frequency used to modulate the output of the resonator. The two frequencies of the resonator are close together in value and the third frequency signal is the difference in frequency of the two resonator outputs. Circuit outputs are one resonator frequency and the difference frequency.

Crystal oscillator producing two frequencies by means of amplitude

A miniaturized face-shear mode quartz crystal vibrator and method of manufacture is provided. The vibrator is formed from a Y-cut quartz crystal plate less than 500 .mu.m thick which has been rotated between 45.degree. to 55.degree. about the X-axis. A plurality of vibrators are formed by depositing a thin metallic film on the two opposed planar surfaces of the plate, selectively etching portions of the metallic films and dissolving the uncoated portions of the plate. The metallic films become the vibrator electrode.

Face-shear mode quartz crystal vibrators and method of manufacture

A mode coupled tuning fork type quartz crystal vibrator utilizing two different vibrational modes is provided. The vibrator includes at least one electrode on each tuning fork arm for adjusting the resonant frequency of the main vibration and an electrode for adjusting the frequency-temperature characteristic of the vibrator. The main vibration is in the flexural mode (F.sub.1) and the sub-vibration is in the torsional mode (T.sub.0). The resonant frequency of the first overtone in the flextural mode is designated by f.sub.F and the resonant frequency of the fundamental vibration in the torsional mode is denoted by f.sub.T. The difference between f.sub.F and f.sub.T defined as .DELTA.f=f.sub.F -f.sub.T determines the frequency-temperature characteristics of the mode coupled vibrator. The electrodes for adjusting f.sub.F are substantially triangular in shape and the electrodes for adjusting f.sub.T are substantially rectangular in shape. These electrodes are disposed at positions near the top of each tuning fork arm and on both principal surfaces of the vibrators. The resonant frequencies are adjusted by removing a portion of electrode material or adding a strip of metal to the electrode. Preselected oscillation frequency and frequency-temperature characteristics in the form of a cubic curve at ambient temperatures are obtained by first adjusting .DELTA.f to a preselected value .DELTA.f.sub.O and then adjusting f.sub.F to a preselected value f.sub.F0 at the same time maintaining .DELTA.f at the value .DELTA.f.sub.0.

Mode coupled tuning fork type quartz crystal vibrator and method of

A tuning fork type quartz crystal vibrator has electrodes formed on its surfaces with the electrodes being divided into separated portions along the length of the tuning fork arms such that opposite electric fields and charges are juxtaposed in the same arm. Dividing the electrode at a location along the tuning fork arms where strains induced during vibration reverse direction, enhances the ability to induce vibrations. A low resonant resistance and high capacity ratio are provided for an overtone frequency of flexual vibrations.

Electrode for tuning fork type quartz crystal vibrator

Cutting a quartz tuning fork crystal vibrator at a preferred angle and with a thickness which establishes a close coupled relationship between the flexural and torsional modes of vibration of the arms or tines produces a vibrator having a highly favorable cubic frequency temperature characteristic at predetermined frequencies. Weight added to the ends of the vibrating tines reduces the frequency of both flexural and torsional vibration, whereas weight added at nodal points in the flexural vibration primarily reduces only the torsional vibrational mode. Accordingly, a wide range of frequency adjustments is possible. Deviations from the desired crystal operating frequency due to manufacturing variances are adjustable by sequential weight modifications while the desirable cubic temperature characteristic is retained. High accuracy over a wide temperature range permits operation in oscillator circuits at relatively low frequencies and with attendant low power consumption. Close coupling between vibrational modes occurs when the difference between the flexural and torsional frequencies is .ltoreq.0.15 of the flexural frequency. The principles for dimensioning the crystal, and adjusting thickness and weight, are applicable to both fundamental and overtone frequencies.

Coupled mode tuning fork type quartz crystal vibrator

Quartz crystal vibrators of small size which vibrate in the shear mode consist essentially of a vibrating portion and a support portion, both of which lie in the same plane. As a consequence, they are readily manufactured on a production basis and can be shaped so as to minimize the effect of variation in ambient temperature.

Growing community of inventors

Suwa, Japan

Eishi Momosaki