JPS6334645B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coupled tuning fork type crystal resonator, and in particular to an electrode shape near the tip of a tuning fork arm.

Traditionally, electronic wristwatches have used tuning fork crystal oscillators that use +5°X-cut bending vibration.

This is because this resonator has a parabolic frequency-temperature characteristic at room temperature, which is advantageous in terms of time accuracy. Another advantage is that it consumes less energy due to its low frequency. However, even if this oscillator is used, 1
The error in the moon is about 20 seconds.

Therefore, in order to further improve the accuracy and at the same time realize a long-life electronic wristwatch, we
A coupled tuning fork crystal resonator with the following frequency-temperature characteristics was realized. Regarding coupled tuning fork type crystal resonators, see Japanese Patent Application No. 53-23903, Japanese Patent Application Laid-open No. 53-149499,
It is described in detail in Japanese Patent Application No. 149500/1983.

The coupled tuning fork type crystal resonator according to the present invention uses the first harmonic of bending vibration as the main vibration and the fundamental vibration of torsional vibration as the sub-vibration. FIG. 1 shows the external appearance of this coupled tuning fork type crystal resonator. 1
is a vibrator, 2 is a support lead, 3 is solder, and 4 is a plug. The X-axis is an electric axis, the Y'-axis is a mechanical axis rotated around the electric axis, and the Z'-axis is an optical axis rotated around the electric axis. As shown in Figure 1, the tuning fork arm is oriented in the Y' axis direction.

The resonant frequency of the first harmonic F1 of bending vibration is f _F ,
Let f _T be the resonant frequency of the fundamental vibration T0 of torsional vibration. The difference between f _F and f _T is defined as △f = f _F - f _T. The frequency-temperature characteristics of the coupled tuning fork crystal resonator are determined by Δf. △f is a specific value △
When f ₀ , third-order temperature characteristics are obtained at room temperature. When mass producing coupled tuning fork type crystal resonators, the problem is that f _F and f _T vary due to the unavoidable variations in external dimensions due to mass production, and as a result, △f varies, and ultimately the frequency This is because the temperature characteristics vary. Further, as in the case of a single mode vibrator, there is also the problem that the resonant frequency of the main vibration deviates from a predetermined value. Therefore, in order to mass produce coupled tuning fork type crystal resonators, it is essential to adjust the frequency temperature characteristics and the resonance frequency of the main vibration.

The present invention adjusts the frequency temperature characteristics and sets f _F to the design value.
The purpose is to adjust to f _F0 .

FIG. 2 shows the distribution of the X-direction displacement U _X of F1 and the torsion angle τ about the center line of the tuning fork arm of T0. A, B, C, D, and E on the horizontal axis are A, B, C, D, and E in Figure 1.
Corresponds to positions B, C, D, and E.

Since position D is the vibration node of F1, if a metal film is deposited at position D or the deposited film is cut out with a laser beam, f _F changes only slightly, but f _F decreases greatly, or rise significantly.

Let this adjustment be P or P'. This situation is illustrated in FIGS. 3 and 4. FIG. 3 corresponds to the case where a metal film is deposited, and FIG. 4 corresponds to the case where the metal film is cut out with a laser beam. In FIGS. 3 and 4, the initial state 5 shifts to an intermediate state 6 by performing adjustment P or P', and in this intermediate state Δf is driven to the optimum value Δf ₀ . In intermediate state 6, f _F is not driven to the design value f ₀ .

Therefore, from intermediate state 6, by some method, △
We must drive f _F to f _F0 while maintaining f at △f ₀ . There is also a method of simply depositing a metal film between E and D in Figures 1 and 2, or simply cutting out the deposited film with a laser beam, but in this method, △f increases while driving f _F to f _F0 . It will change and △f will no longer be ₀ .

FIG. 5 shows a specific example of the electrode shape near the tip of the tuning fork arm of the coupled tuning fork type crystal resonator according to the present invention.

E and D in the figure correspond to E and D in FIGS. 1 and 2. Reference numeral 8 denotes an electrode film formed on node D of F1, which is the part where adjustments P and P' in FIGS. 3 and 4 are performed.

8 is named the Δf adjustment electrode. Reference numeral 9 is an inverted triangular electrode for driving f F to f _F0 while maintaining _Δf at Δf ₀ , and is named the f _F adjustment electrode. 9
If a metal film is further deposited on the inverted triangular part of
While △f is maintained at △f ₀ , f _F can be driven to f _F0 . Alternatively, f F can be driven to f _F0 while maintaining Δf at Δf ₀ by cutting out the metal film in the inverted triangular part 9 with a _laser beam.

This adjustment is shown as Q and Q' in FIGS. 3 and 4. 7 is finally △f and f _F are each △
f ₀ , shows the state of being driven to f _F0 .

Now, the reason why an inverted triangular shape such as 9 is adopted as the f _F adjustment electrode will be explained. In this specification, a shape with a missing lower apex as shown in FIG. 6 will also be referred to as an inverted triangle. E and D as shown in Figure 2
Between , the change in U _X is large, but the change in τ is small. Further, the displacement caused by τ is smaller closer to the center of the tuning fork arm, and larger at the end of the tuning fork arm. _U

10, 11,
When a metal film is deposited with a width of 12 and 13, the amount of change Δf _F and Δf _T in f _F and f _T changes as shown in FIG.

Therefore, if a metal film is deposited with a width of 12, f _F and f _T
The amount of decrease becomes equal. In other words, there is a width over which the metal film is deposited such that f _F and f _T decrease by the same amount. If the position of the portion 14 to be vapor-deposited is changed, there is a width at which Δf _F and Δf _T are equal. As the position approaches D, U _X decreases rapidly, and therefore the width in which △f _F and △f _T become equal becomes smaller. As it approaches E _{, since U} Therefore, the f _F adjustment electrode is shaped like an inverted triangle.

In addition, 10', 11', 12', 13' in FIG.
This corresponds to the case where a metal film is deposited with widths 10, 11, 12, and 13 in FIG. Also, △f _F and △f _T are
This is the difference from the frequency when no metal film is deposited.

For the above reasons, even if the f _F adjustment electrode is cut out with a laser beam, f _F and f _T can be increased by the same amount.

In order to adjust Δf and f _F , the Δf adjustment can be performed by vapor deposition, and the f _F adjustment can also be performed by a laser beam. Similarly, △f adjustment is performed using a laser beam, and f _F
Adjustment can also be carried out by vapor deposition.

In order to increase the amount of adjustment when adjusting with a laser beam, deposit or plate a thick metal film on either or both of the △f adjustment electrode and _fF adjustment electrode in advance. It is effective if you leave it on.

Node D of F1 exists at a portion approximately 0.2 from the tip, assuming the length of the tuning fork arm to be 1. Therefore, it is necessary to provide the Δf adjustment electrode 8 in a region of 0.1 to 0.4 from the tip of the tuning fork arm, and the f _F adjustment electrode in a region of 0 to 0.2.

Further, it is necessary to attach the Δf adjustment electrode and the f _F adjustment electrode to the front and back of the tuning fork arm. The reason for this is explained below. FIG. 9 shows variations in temperature characteristics due to manufacturing variations, with the vertical axis representing the change in f _F (Δ) between 0° C. and 40° C., and Δf representing the horizontal axis. The black dots indicate △ relative to △f.

When a metal film is deposited on the Δf adjustment electrode on the -Z' plane of the vibrator exhibiting the characteristic at point 16, the temperature characteristic changes as shown by arrow 18. When a similar operation is performed on the +Z' plane, the temperature characteristics change as shown by arrow 19. −Z′ plane and +
When a metal film is deposited on the Δf adjustment electrodes on both sides of the Z' plane, the temperature characteristics change as shown by arrow 20.

Only the −Z′ plane of the resonator exhibiting the characteristic of point 17, +
When the same operation is performed on only the Z' plane, and on both the +Z' plane and the -Z' plane, the temperature characteristics change as shown by arrows 21, 22, and 23. If a metal film is deposited only on the △f adjustment electrode on one side, △ will be extremely small for the vibrator at point 16 and the vibrator at point 17.
becomes different. However, if a metal film is deposited on the Δf adjustment electrodes on both sides, the Δf of the two vibrators becomes Δf ₀ and becomes very small, as shown by arrows 20 and 23. This is a great advantage because the temperature characteristics can be adjusted by controlling Δf during mass production.

Also, when cutting off the metal film of the △f adjustment electrode that has been added in advance with a laser beam, if the metal films on both sides are cut off, the temperature characteristics of the resonator will be △f ₀
The desired third-order temperature characteristics can be obtained.

f _F adjustment electrodes must also be provided on both sides of the tuning fork arm, and metal films must be deposited on both sides, or the electrodes on both sides must be cut out. This means that unless such operations are performed on both sides, f _F will remain unchanged while △f remains △f ₀ .
Even if it is suppressed to f _F0 , the temperature characteristics will deviate. In other words, the value of △f obtained by the third-order temperature characteristic is no longer △f ₀ . Therefore, both the Δf adjustment electrode and the f _F adjustment electrode must be provided on both sides of the tuning fork arm, and adjustment operations must be performed on both sides.

As mentioned above, by providing the △f adjustment electrode and the f _F adjustment electrode on both sides of the tip of the tuning fork arm, it becomes possible to adjust f _F and △f of the coupled tuning fork type crystal resonator, which improves mass production. can be improved.

By using the coupled tuning fork type crystal oscillator of the present invention in an electronic wristwatch, it is possible to achieve longer life and higher precision.

[Brief explanation of the drawing]

FIG. 1 shows the appearance of a conventional coupled tuning fork type crystal resonator. Figure 2 shows the displacement distribution of F1 and T0.
FIG. 3 shows a method for adjusting Δf and f _F by vapor deposition. FIG. 4 shows a method of adjusting Δf and f _F using a laser. Figure 5 shows the △f provided at the tip of the tuning fork arm.
The adjustment electrode 8 and the _fF adjustment electrode 9 are shown. FIG. 6 shows an inverted triangle of the f _F adjustment electrode. Figure 7 shows
This figure shows a metal film deposited in a thin strip. FIG. 8 shows Δf _F and Δf _T corresponding to FIG. FIG. 9 shows the difference in temperature characteristics when a metal film is deposited on one side and both sides of a tuning fork arm. 1...Coupled tuning fork crystal resonator, 2...Support lead, 3...Solder, 4...Plug, 5...Initial state, 6...Intermediate state, 7...Final state, 8...△
f adjustment electrode, 9...f _F adjustment electrode, 10,1
1, 12, 13...indicates the width of the metal film deposited in a band shape. 14...Metal film deposited in a band shape, 1
0', 11', 12', 13'...10, 1 in Figure 7
Corresponds to 1, 12, and 13. 16...△ for △f of one oscillator, 17...other, 18, 21
……−Change in temperature characteristics when a metal film is deposited on the Z′ plane. 19, 22...Change in temperature characteristics when a metal film is deposited on the +Z' plane. 20, 23...Changes in temperature characteristics when a metal film is deposited on the +Z' and -Z' planes. 24...△f adjustment electrode, 25...f _F adjustment electrode.

Claims (1)

[Claims] 1. In a coupled tuning fork type crystal resonator in which the fundamental vibration of torsional vibration is combined with the first harmonic of bending vibration, when the length of the tuning fork arm is 1, the distance from the tip of the tuning fork arm to 0 to
In the 0.2 part, there is a substantially inverted triangular shape with a wide tip side of the tuning fork that simultaneously adjusts the bending vibration frequency f _F and the torsional vibration frequency f _T without changing the frequency difference △f between the bending vibration frequency f _F and the torsional vibration f _T. A coupled tuning fork type crystal resonator characterized in that a metal film weight is provided, and the metal film weight is provided on both sides of the tuning fork arm. 2. In a coupled tuning fork crystal resonator in which the fundamental vibration of torsional vibration is combined with the first harmonic of bending vibration, when the length of the tuning fork arm is 1, from the tip of the tuning fork arm
A rectangular metal film weight for adjusting the frequency difference △f between the bending vibration frequency f _F and the torsional vibration frequency f _T is provided in the 0.1 to 0.4 portion, and a rectangular metal film weight is provided in the 0 to 0.4 portion from the tip of the tuning fork arm.
A substantially inverted triangular metal membrane weight with a wide tuning fork tip side for adjusting the bending vibration frequency f _F and torsional vibration frequency f _T without changing the frequency difference △f is provided in the 0.2 part, and a metal membrane weight having a substantially inverted triangular shape with a wide tuning fork tip side is provided. A coupled tuning fork type crystal resonator characterized in that triangular metal film weights are provided on both sides of the tuning fork arm.