JPS6364926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a crystal resonator for an electronic wristwatch.

[Conventional technology]

Currently, bending vibrating crystal tuning forks are the mainstream time standard crystal oscillators for electronic wristwatches.

However, recently, attention has begun to be paid to increasing the accuracy of electronic wristwatches, and efforts are being made to create a crystal oscillator for wristwatches that can guarantee accuracy within a few seconds per year.

A conventional bent crystal tuning fork for electronic wristwatches is shown in FIG. In this figure, the X, Y, and Z axes are quartz crystal axes, respectively.

The vibrating arms 1 and 2 of the tuning fork are provided along the Y' axis,
The main surface of the tuning fork shape is the Z′ cut surface.

Further, in the vibration mode, the vibrating arms 1 and 2 perform bending vibration in the direction of the arrow.

The accuracy of watches using this bent crystal tuning fork is determined by the following points: frequency temperature characteristics, frequency changes over time, stability, etc.
It is unsuitable as a high-precision time standard oscillator whose limit is a monthly difference of several seconds.

On the other hand, the AT cut crystal oscillator has various characteristics that are an order of magnitude better than the bent type, making it possible to create highly accurate clocks with yearly differences of just a few seconds.

Figure 2 shows an AT-cut crystal oscillator for general communications. 3 is an AT-cut crystal; 4 and 4' are excitation electrodes; and 5 and 5' are supporting springs each having a clip-shaped tip for supporting the AT-cut crystal 3.

[Problem to be solved by the invention]

However, when the AT-cut crystal for communications is miniaturized for use in wristwatches, its various properties are greatly affected by the support, making it extremely difficult to maintain its original properties. Therefore, the current situation is that wristwatches have not been sufficiently miniaturized while maintaining their original characteristics for use in wristwatches.

The object of the present invention is to provide an ultra-compact crystal oscillator that eliminates the above-mentioned drawbacks and can realize a high-precision electronic wristwatch with an annual difference of several seconds, which is impossible to achieve with a bent crystal tuning fork.

[Means to solve the problem]

The gist of the present invention to achieve the above object is to provide an AT-cut tuning fork crystal resonator consisting of a vibrating arm and a base, with at least two
A side electrode of the terminal is formed, and an electrode for connection to the outside is led out to the electrode lead part through the front side of the Z' cut face on one side and the back side of the Z' cut face on the other hand, It is characterized by connecting the connecting electrode and the electrode lead part on the side.

〔Example〕

The present invention will be described below with reference to the drawings.

Figure 3 shows the direction in which the AT cut crystal is cut from the rough crystal, and is cut at approximately 35 degrees from the Z axis. Figure 4 is a diagram showing the vibration mode of an AT-cut crystal, which performs thickness-shear vibration along the X-axis as indicated by the arrow.

FIG. 5 is a diagram showing the method of cutting the AT-cut crystal tuning fork of the present invention, in which a slit 6 is provided along the X axis, and then the slits are cut in the manner of 7, 7', 7'', etc.
It is possible to obtain AT-cut crystal tuning forks 8, 8', 8'', etc. whose main surface has a Z'-cut surface.

FIG. 6b shows an AT cut crystal tuning fork processed by the above method. Note that FIG. 6a is a diagram of the principle of vibration. (The same applies to FIG. 7a.) The AT-cut crystal tuning fork is constructed such that the Z' cut surface is the main plane and the Y' cut surface is the side surface. In the figure, 9 and 10 are vibrating arms, and the vibrating arms 9 and 10 are connected by a base. 11,
Excitation electrodes 11', 12, and 12' are formed on the Y' cut surface of the AT cut crystal tuning fork, and are excited by two terminals as shown in FIG. 6a. Therefore, the electrodes 12 and 12' formed in the groove are connected to each other at the bottom of the groove, and are connected to the electrode lead part 14 at one end on the lower side of the base via the surface side of the Z' cut surface. Electrode 1 formed on one side of the crystal tuning fork
1' is connected to the electrode 11 through the back side of the Z' cut surface, and the electrode lead 13 is connected below the electrode 11.
conducts to. With this configuration, when an oscillating voltage is applied to the electrode leads 13 and 14, 1 in Fig. 6a.
Electric fields shown at 5 and 16 are generated, and the vibrating arms 9 and 10
performs thickness shear vibration as indicated by the arrow in Figure 6b.
AT cut crystal tuning fork can be realized.

FIG. 7 is a diagram showing another electrode structure for vibrating an AT-cut crystal tuning fork.

It is an AT-cut crystal tuning fork whose main plane is the Z'-cut surface where the vibrating arms 23 and 24 are connected at the base, and the electrode 29 connected at the bottom of the groove, the electrode 27 formed on one side, and the It is formed by three terminals of the electrode 28 formed on the side surface. When a necessary vibration voltage is applied to these three terminals, electric fields shown by arrows 33 and 34 are generated, and the vibrating arms 23 and 2
4 performs thickness shear vibration shown by the arrow in FIG. 7b.

〔Effect of the invention〕

As explained above, according to the present invention, since the AT-cut crystal tuning fork is supported below the base and the vibrating arms are free, the influence of the support on the vibration characteristics is eliminated. Therefore, the original high precision characteristics of the AT cut vibrator can be maintained, and since the frequency is determined by the thickness in the Y'-axis direction, ultra-miniaturization can be easily realized.

In addition, since a large number of tuning forks can be obtained from one AT cut wafer, productivity is improved, and the present invention is extremely effective as a crystal resonator for high-precision electronic wristwatches.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the cutting direction of a bent crystal tuning fork, Figure 2 is a front view showing an AT cut crystal for communication, Figure 3 is a perspective view showing the cutting direction of an AT cut crystal, and Figure 4 is an AT cut crystal. FIG. 5 is a perspective view showing a method of cutting the AT-cut crystal tuning fork of the present invention; FIGS. 6 and 7 show specific examples of the AT-cut crystal tuning fork of the present invention; In each case, a is a cross-sectional view, and b is a plan view. 8,8',8''...AT cut crystal tuning fork, 9,1
0, 23, 24...AT cut crystal tuning fork vibrating arm, 11, 11', 12, 12', 29, 28, 2
7... Electrode, 15, 16, 33, 34... Electric field.

Claims (1)

[Claims] 1. In an AT-cut tuning fork type crystal resonator, each vibrating arm consists of a vibrating arm whose main surface is a Z′-cut surface tilted at an angle of about 35 degrees to the Z-axis and a slit formed in the X-axis direction, and a base connecting the vibrating arms. Form side electrodes with at least two terminals on the Y' cut surface, which is the side surface of the
It is led out to the electrode lead part through the front side of the Z' cut surface, and led out to the electrode lead part through the back side of the Z' cut face, and the connection electrode is connected to the lower side of the base part. 1. An AT-cut tuning fork type crystal resonator, characterized in that the electrode lead portion and the electrode lead portion are connected to each other.