Kabushiki Kaisha Seikosha

Seikosha Co., Ltd.

Hirofumi Yanagi

Hitoshi Ikeno

Mitsuyuki Sugita

Tetsuro Konno

Nakanobu Moritani

Isamu Hoshino

An overtone crystal oscillator includes a crystal vibrator, a CMOS circuit connected in parallel to the crystal vibrator, and two load capacitors connected to the input and output of the CMOS circuit, respectively. The capacitors have respective capacitances C.sub.g and C.sub.d determined to satisfy at least one of following two conditions wherein the first condition is that an oscillation starting resistance R.sub.KN of a desired N-th overtone is sufficiently larger than an effective resistance R.sub.QN of the crystal vibrator of the N-th overtone, the oscillation starting resistance being expressed as:

Overtone crystal oscillator

A driving electrode on a surface of the piezoelectric vibrator in accordance with the present invention has a blank which is narrow at the center portion and wide at the right and left portions on the Z axis. And the driving electrode is the shape easy to operate in the fundamental main vibration, and hard to operate in the spurious vibration. Thus the piezoelectric vibrator operates efficiently in the fundamental main vibration.

Electrode configuration for thickness-shear mode piezoelectric vibrator

A thickness-shear mode piezo-electric vibrator comprises a piezo-electric crystal operable in the thickness-shear mode, driving electrodes formed on opposed surfaces of the crystal, and an addition mass formed on at least one of the driving electrodes and positioned on the nodal line of a 3-fold harmonic vibration so that the frequency f.sub.o of the fundamental main vibration and the frequency f.sub.3s of the 3-fold harmonic vibration always satisfy the following relation within the practical application ranges of temperature and load capacitance; ##EQU1## thereby effectively eliminating or preventing the 'abnormal frequency phenomenon' which would otherwise occur due to the 3-fold harmonic vibrations.

Thickness-shear piezo-electric vibrator with additional mass for mode

A quartz oscillator comprises a quartz blank having electrode films deposited on opposite parallel faces thereof. Holding wires which are parallel to the quartz blank extend along and spaced slightly from the opposite faces of the blank and are locally soldered to the quartz blank. The holding wires extend beyond the edge of the quartz blank and are secured to a holding substrate provided with electrical connections. The quartz oscillator is prepared by positioning a quartz blank and a holding substrate in a supporting frame, opposite faces of the quartz blank and holding substrate being provided at selected positions with solder parts. The holding wires are then positioned along opposite faces of the quartz blank and holding substrate and the solder parts are temporarily fused by radiant heat to bond the holding wires to the quartz blank and the holding substrate.

Process for preparing quartz oscillator

A method of adjusting the frequency and temperature coefficient of a GT cut quartz oscillator comprises starting with a blank of approximately the frequency desired. An electrode film is deposited on the front and rear faces of the blank. The side ratio between a longer side and a shorter side is adjusted to obtain a zero temperature coefficient. Thereafter portions of the electrode film along the longer sides of the oscillator are removed to reduce the area of the electrode film so as to obtain the desired frequency without changing the side ratio and thus without disturbing the zero temperature coefficient.

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Tokyo, Japan

Hirofumi Yanagi