JPH11225040A - Sc-cut crystal vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent stress sensitivity characteristic with a paper- tablet type whose longer side size is 6 mm or below. SOLUTION: In the paper-tablet type SC-cut crystal vibrator that is segmented from a face of a crystal that is a face orthogonal to the Y axis of a crystal is turned by about 33 degrees and then turned by about 22 degrees around the Z axis from the turned face by about 33 degrees, the longer side of a crystal chip 11 is selected to be 100 deg.±10 deg. or 149 deg.±10 deg. from a direction of an XX' axis and the end in the long side direction is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SC-cut quartz-crystal vibrator which uses a small-sized quartz piece having a rectangular shape with a dimension of 6 mm or less in a long side direction and excellent vibration characteristics.

[0002]

2. Description of the Related Art Recently, attention has been paid to SC-cut quartz resonators having excellent performances such as stress sensitivity, thermal shock characteristics, and phase noise performance. As shown in FIG. 3, such an SC-cut quartz resonator rotates a plane orthogonal to the Y-axis of the crystal of the quartz crystal by about 33 ° about the X-axis, and further rotates the Z-axis from the rotated position. An electrode is formed on a crystal blank 1 cut out from a plane rotated by about 22 °.

The frequency and temperature characteristics of an SC-cut quartz resonator have a substantially cubic curve having an inflection point near 80 ° C. On the other hand, as a high-stability crystal oscillator, a thermostat-type crystal oscillator that is operated by heating to a constant temperature of about 80 ° C. is known.

[0004] Such an oscillator comprises a heater for heating,
A temperature control circuit for controlling the amount of heat generated by the heater to maintain a constant temperature of about 80 ° C., for example. On the other hand, SC-cut crystal units
When used as a thermostat type crystal oscillator because it has an inflection point near ℃, it will be used in the temperature range where the rate of change of the oscillation frequency with respect to temperature change is the least, and an extremely stable oscillation frequency can be obtained. it can.

[0005] In such a constant temperature oven type crystal oscillator,
In order to obtain high stability, a crystal resonator using a relatively large round plate-shaped crystal piece having a diameter of, for example, about 10 mm is used. Therefore, the overall shape of the oscillator is 40
It is a cube of about mm square, and the oscillator is remarkably large compared to components used in electronic devices other than the oscillator. Therefore, it has been desired to reduce the size of the crystal resonator and thereby the size of the oscillator.

By the way, such a highly stable crystal oscillator achieves a stability of about 0.0001 ppm to 0.00001 ppm. For this reason, a change in the attitude of the oscillator itself, a slight change in the oscillation frequency caused by an externally applied stress or the like, that is, a stress sensitivity characteristic also poses a serious problem. In particular, when a small-sized quartz crystal resonator is used, the stress sensitivity characteristic also deteriorates,
Since the frequency changes greatly due to the difference in attitude of the oscillator itself and a slight stress, there is a problem that a stable oscillation frequency cannot be maintained.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is an SC-cut quartz crystal resonator having a rectangular shape having a long side dimension of 6 mm or less and capable of obtaining good stress sensitivity characteristics. The purpose is to provide.

[0008]

A first aspect of the present invention is to set a plane orthogonal to the Y axis of a crystal of crystal to about 33 degrees around the X axis.
゜ rotate, and from this rotated position about 2
In a rectangular SC-cut crystal resonator cut out from a plane rotated by 2 °, the long side of the crystal piece is set at 1 mm from the XX ′ axis direction.
The angle is set to 00 ° ± 10 ° or 149 ° ± 10 °, and the end in the long side direction is held.

A second aspect of the present invention is characterized in that, in the first aspect, the dimension of the crystal piece in the long side direction is 6 mm or less, and the third aspect of the present invention is the one described in the first aspect. In the above, the crystal blank is characterized by being in the 11 MHz band of the fundamental wave. Claim 4 of the present invention is characterized in that, in the one according to claim 1, the crystal blank is housed in a cylindrical container, According to a fifth aspect of the present invention, in the first or second aspect, one end of a long side of the crystal piece is held.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to a perspective view of a crystal unit shown in FIG. In the figure, reference numeral 11 denotes a strip-shaped SC-cut crystal piece, which leads a pair of electrodes formed facing the plate surface to one end in the longitudinal direction. The lead-out ends of the electrodes of the quartz piece are fixed to the tips of the pair of terminals 13 implanted in the base 12 with a conductive adhesive, and are electrically connected.

The base 12 is covered with a cylindrical cover (not shown), and the opening edge of the cover is hermetically fitted to the base for sealing. This crystal blank 11
For example, as shown in FIG. 2, the surface of the artificial quartz crystal orthogonal to the Y-axis is rotated about 33 ° about the Z-axis, and S is rotated about 22 ° about the X-axis from this rotated position.
It was cut out from a C plate in a strip shape.

Here, in a remarkably small rectangular crystal piece having a shape of 1.6 mm × 5.1 mm, the longitudinal direction is X.
Eighteen kinds of samples were manufactured by in-plane rotation by 10 ° from the direction of the X ′ axis. The resonance frequency of the sample crystal piece is 11 MHz of the fundamental wave, and the excitation electrode formed facing the front and back plate surfaces of the crystal piece is led out to one end in the longitudinal direction, and the leading end performs cantilever support. I did it.

Then, in order to measure the stress sensitivity characteristics of each sample, the change in the resonance frequency when the other end in the longitudinal direction of the quartz piece was pressed was measured. FIG. 2 is a graph showing the measurement results of the stress sensitivity characteristics. As is clear from this graph, the stress sensitivity characteristic of the strip-shaped quartz piece changes substantially continuously in accordance with the in-plane rotation angle, and the longitudinal direction of the strip is about +100 ppb on the + side at 30 ° from the XX ′ axis. /
At N, 120 °, the maximum value is about −25 ppb / N on the negative side. Also, the longitudinal direction is 100 ° and 149 ° from the XX ′ axis.
At ゜, the stress sensitivity characteristic becomes minimum 0 because it crosses the origin.

Therefore, in order to minimize a frequency change due to an external stress or a posture difference, in the case of a strip-shaped SC-cut crystal piece having a remarkably small shape, the longitudinal direction is set at 100 ° ± 10 ° from the XX ′ axis. Or 149 ゜ ± 10 ゜,
Most preferably, the longitudinal direction of the crystal blank is 100
It is sufficient to set it to {149}.

In this way, the shape can be remarkably reduced in size as compared with a conventional SC-cut crystal unit.
For example, it can be stored in a cylindrical container having a diameter of about 3 mm and a length of about 8 mm. Therefore, when such a small crystal resonator is used, the stress sensitivity characteristics are good, and the overall size of the crystal oscillator can be significantly reduced.

[0015]

As described in detail above, according to the present invention,
A very small SC-cut crystal unit with a remarkable shape can be realized, the stress sensitivity characteristics are good, the frequency change due to external stress and posture difference can be minimized, and the resonance frequency is maintained at high stability. It is possible to provide an SC-cut crystal unit that can be used.

[Brief description of the drawings]

FIG. 1 is a perspective view of a crystal resonator according to an embodiment of the present invention with a cover removed.

FIG. 2 is a graph showing a relationship between a cutout angle of a crystal piece and stress sensitivity.

FIG. 3 is a diagram illustrating a cut-out angle of a crystal piece in an SC cut.

[Explanation of symbols]

 11 ··· Crystal blank 12 ··· Base 13 ··· Terminal

Claims (5)

[Claims] 1. A rectangular shape obtained by rotating a plane orthogonal to the Y-axis of a crystal of a quartz crystal by about 33 ° about the X-axis, and cutting the plane rotated about 22 ° about the Z-axis from the rotated position. In the SC-cut quartz crystal resonator, the long side of the crystal piece is set to 100 ° ± 10 ° or 149 ° ± 10 ° from the XX ′ axis direction, and the end in the long side direction is held. Crystal oscillator. 2. The apparatus according to claim 1, wherein the dimension of the crystal piece in the long side direction is 6 mm or less.
C-cut crystal oscillator. 3. The SC-cut crystal resonator according to claim 1, wherein the crystal blank has an 11 MHz band of a fundamental wave. 4. An SC-cut crystal resonator according to claim 1, wherein the crystal piece is housed in a cylindrical container. 5. An SC-cut crystal resonator according to claim 4, wherein one end of a long side of the crystal piece is held.