Kabushiki Kaisha Seikosha

Seikosha Co., Ltd.

Hitoshi Ikeno

Mitsuyuki Sugita

Hirofumi Yanagi

Tetsuro Konno

Nakanobu Moritani

Isamu Hoshino

Hirobumi Yanagi

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 shell of a hermetically sealed package has a through hole and a circuit board is inserted and fixed hermetically into the through hole, and a can is fixed hermetically to the shell. The circuit board consists of a sealed part which is sealed hermetically by the hermetically sealed package, a fixed part to which the shell is fixed, and a projecting part which projects out from the hermetically sealed package. As the circuit pattern extends from the sealed part through the fixed part to the projecting part, it is not necessary to use terminal pins and instead a large number of external lead electrodes are taken out from the hermetically sealed package. An integrated-circuit chip or the like which is sealed by the hermetically sealed package can be shielded from electromagnetic influence by the metallic shell and the metallic can.

Hermetically sealed package

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 thickness-shear mode quartz oscillator characterized in that an addition mass fitted to a driving electrode of the oscillator for the purpose of adjusting its oscillation frequency has a non-circular shape or the fitting position thereof is deviated from the center of a quartz slice, or both in combination. Such addition mass provides different piezoelectric effects and effects of addition of the mass between the fundamental main vibration and harmonic vibrations and eliminates or restricts a 'frequency abnormal phenomenon'. Consequently, even when driven by a C-MOS type integrated circuit not having a frequency selection circuit in its oscillation loop, the thickness-shear mode quartz oscillator exhibits stable frequency-temperature characteristics.

Thickness-shear mode quartz oscillator with an added non-circular mass

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 device for polishing plano-convex lenses, quartz oscillators and the like comprises a lapping dish having a concave spherical surface and mounted for oscillating and rotary movement. The material to be polished is held by a suction rotary chuck which applies the material to be polished against the lapping dish with a selected pressure. Separate motors are provided for rotating and oscillating the lapping dish and for rotating the material to be polished.

Polishing device

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.

Growing community of inventors

Tokyo, Japan

Hitoshi Ikeno