JPH05243890A - Crystal oscillator for sc cut - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an SC-cut crystal unit having a small crystal impedance and capable of oscillating with low power consumption. [Structure] SC cut of a plane of the crystal of quartz which is orthogonal to the Y-axis and rotated about 33 ° about the X-axis and further rotated about 22 ° about the ZZ'-axis from this rotated position. In the two-time rotating crystal unit, the end face in the ZZ'-axis direction of the crystal piece is obliquely cut parallel to the plane formed by the XX 'axis and the Z axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SC cut crystal oscillator having excellent crystal impedance characteristics.

[0002]

2. Description of the Related Art Generally, a crystal oscillator exhibits a unique vibration characteristic according to a cutting angle with respect to a crystal axis. For example, the number M
The AT-cut crystal resonator most commonly used at frequencies of Hz to tens of MHz exhibits a cubic curve-shaped temperature characteristic having an inflection point near 25 ° C. By the way, as a reference oscillator required to have a frequency with high stability in measuring equipment, wireless equipment, etc., for example, an oven-controlled oscillator is used. In this constant temperature oven type oscillator, the crystal oscillator is housed in a constant temperature oven heated to a constant temperature of about 80 ° C. to eliminate the frequency change due to the temperature characteristic of the crystal oscillator and stabilize the crystal oscillator. An SC-cut crystal oscillator is known as a crystal oscillator suitable for such an oscillator. This S
As shown in FIG. 4, the C-cut crystal unit 1 rotates about 33 ° about the X axis on the plane perpendicular to the Y axis of the crystal of the crystal, and about about ZZ ′ axis from this rotated position. 22
For example, a strip is cut out from the surface rotated by °. However, this SC-cut crystal unit has better thermal shock characteristics than AT-cut crystal unit at 80 ℃.
It exhibits a zero temperature coefficient at a relatively high temperature around and a high Q value can be obtained. Such characteristics are extremely desirable characteristics for a crystal oscillator with high stability, which is stored in a constant temperature bath heated to a constant temperature of about 80 ° C. and used. Therefore, for example, one of the 34th FCS (FREQ. CONTROL SYMPOSIUM) abstracts held in May 1980
Various reports have been made as disclosed on pages 87 to 193 as fundamental mode SC-cut resonators.

With the recent trend toward miniaturization and low power consumption of electronic equipment, it is desired that the crystal oscillator used in this kind of electronic equipment also operates with low power consumption. On the other hand, in order to reduce power consumption in a crystal oscillator using a crystal oscillator, it is extremely effective to use a crystal oscillator having a low crystal impedance (hereinafter referred to as CI). Conventionally, in the AT-cut crystal unit that is most often used in the frequency band of several MHz to ten and several MHz, the vertical and horizontal dimensions of the strip-shaped crystal piece are optimized to reduce the CI, or the vibration energy of the plate surface is adjusted. Convex processing for obliquely cutting the peripheral edge of the plate surface to confine it in the central portion, bevel processing for forming the plate surface into a convex lens shape, and the like are performed. However, it is impossible to apply the technique used for the AT-cut crystal unit to the SC-cut crystal unit as it is because the vibration modes are different from each other, and the SC-cut crystal unit has good CI with low CI. The thing of the characteristic was desired.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a low-CI SC cut crystal oscillator suitable for an oscillator capable of operating with low power consumption. To do.

[0005]

According to the present invention, a plane perpendicular to the Y axis of a crystal of quartz is rotated about 33 degrees about the X axis, and further about 22 degrees about the ZZ 'axis from this rotated position. An SC-cut double-rotation crystal unit cut out from a surface rotated by °, characterized in that the end face in the ZZ'-axis direction of the crystal piece was obliquely cut parallel to the plane formed by the XX'-axis and the Z-axis. It is what

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the perspective view of the crystal blank shown in FIG. In the figure, 11 is an SC-cut crystal piece. The crystal piece 11 has a surface orthogonal to the Y axis of the crystal of the crystal and the center of the X axis is about 3
It is an SC-cut crystal piece that is rotated by 3 °, for example, 33 ° 30 ′ counterclockwise, and is further rotated about 22 °, for example, 22 ° 30 ′ counterclockwise about the ZZ ′ axis, and is rotated twice. The crystal piece 11 has an end face in the ZZ'-axis direction, which is obliquely cut in parallel with a plane formed by the XX'-axis and the Z-axis. When the crystal piece 11 is used as a crystal oscillator, a conductive metal such as aluminum or silver is vapor-deposited on the front and back main surfaces to form an excitation electrode made of a metal thin film, and the excitation electrode is used for an oscillation circuit or the like. I am trying to connect and use it.

A 5.0 mm × 2.5 mm rectangular SC-cut crystal piece with a fundamental resonance frequency of 16.9 M
For each 20 Hz sample, Z
One in which the end portion in the Z'-axis direction is cut at a right angle to the main surface, and the other in which the end surface in the ZZ'-axis direction according to the present invention is cut obliquely in parallel to the plane formed by the XX 'axis and the Z axis. The properties were measured. As a result, the conventional one had an average CI value of 56.3Ω and a standard deviation of 4.2. On the other hand, in the sample according to the present invention, the average CI value is 38.1.
Ω, standard deviation was 1.2. Therefore, according to the present invention, the CI value is as small as about 2/3 of that of the conventional one,
Moreover, it is possible to obtain an SC-cut crystal unit with a small standard deviation and a small variation in characteristics.

[0008]

As described in detail above, according to the present invention, C
It is possible to provide a SC-cut crystal resonator which has a small I and is suitable for an oscillator that can operate with low power consumption and has a small variation in characteristics.

[0009]

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a cutting angle of a crystal unit of the present invention.

[Explanation of symbols]

 11 crystal pieces

Claims (1)

[Claims] 1. A plane perpendicular to the Y axis of a quartz crystal is rotated about the X axis by about 33 °, and Z is rotated from this rotated position.
SC cut out from the surface rotated about 22 ° around the axis
In a cut double-turn crystal unit, an SC-cut crystal unit in which an end face of the crystal piece in the ZZ'-axis direction is cut obliquely in parallel to a plane formed by the XX'-axis and the Z-axis.