JPH0156565B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a vibration mode in which several vibration modes are combined.
This invention relates to a method for adjusting the frequency of a so-called coupled resonator.

An object of the present invention is to provide a coupled resonator with excellent frequency-temperature characteristics (hereinafter referred to as temperature characteristics). There are many consumer devices that require resonators with excellent temperature characteristics, and AT-cut crystal resonators have been used in these products. However, recently, various consumer devices have become smaller, and accordingly, there has been a demand for smaller AT-cut crystal resonators, but this type of resonator has a lot of spurious vibration. The current situation is that miniaturization is difficult. In particular, when an AT-cut crystal resonator is used as a wristwatch resonator, it must be made considerably smaller, and when compared with a tuning fork-type bent crystal resonator, it is not at all satisfactory in terms of size. Therefore, recently, a method of forming resonators using photolithography, which applies IC technology, has been applied to the manufacture of resonators, and as a result, it has become possible to provide extremely small resonators.
For example, there are GT cut crystal resonators with excellent temperature characteristics that allow the resonator to be extremely thin, and bend-torsion crystal resonators (hereinafter referred to as FT crystal resonators) that combine bending mode vibration and torsional mode vibration. Applications have made it possible to create very small products. but,
These GT-cut and FT-cut crystal resonators utilize the combination of two vibration modes, ie, main vibration and sub-vibration, to obtain good temperature characteristics. Therefore, the temperature characteristics are almost determined by the difference between the resonance frequencies of the main vibration and the sub-vibration. Theoretically, it is known how much difference in resonance frequency should be set to provide excellent temperature characteristics, but in reality, it is difficult to maintain a constant difference due to manufacturing variations, and this is the cause of variations in temperature characteristics. It was hot. Therefore, the present invention provides a resonance frequency and temperature characteristic adjustment method that reduces variations in temperature characteristics when adjusting the resonance frequency of the main vibration to the reference frequency f ₀ .

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

Figure 1 shows an example of the shape and electrodes of a coupled resonator.
This is an example of a GT cut crystal resonator in which a vibrating part and two supporting parts arranged on both sides of the vibrating part are integrally formed. A shows a plan view and B shows a side view. Electrodes 2 and 3 are arranged on the front and back surfaces of the crystal 1, and the vibrator can be easily excited by applying an alternating voltage to both electrodes. Also, the resonance frequencies of the two modes are determined by the width W and the length L. If the resonance frequency of the main vibration due to the width W is f _W and the resonance frequency of the sub vibration due to the length L is f ₁ , then the following There is a relationship.

f _W ∝1/W f _L ∝1/L (1) Furthermore, the temperature characteristics are approximately determined by the difference f _W −f _L between both resonance frequencies.

FIG. 2 shows a top view A and a side view B of an embodiment of the GT cut crystal resonator mounted on the support base 4. FIG. A crystal resonator 5 is arranged on the support base 4, and the ends 8 and 9 of the resonator are fixed by adhesive or soldering. Excitation electrodes 6 and 7 are arranged on the front and back surfaces of the crystal.

Figure 3 shows an example of the temperature characteristics of a GT cut crystal resonator formed by photolithography, and the temperature characteristics vary depending on the strength of the bond. When the coupling between the main vibration and the sub-vibration is weak, that is, when δ=f _W −f _L is large, as shown by straight line a, and when the coupling is strong,
That is, when δ is small, the line becomes like a straight line b. At this time, the absolute value of the first-order temperature coefficient α is approximately 2.5×
10 ^-6 /℃, which is large and does not provide satisfactory temperature characteristics. However, when δ is the optimum value, the line becomes like a straight line c, showing good temperature characteristics. Coupled oscillators that are generally manufactured exhibit such variable tweeter temperature characteristics. In other words, as shown in straight line a, the first-order temperature coefficient α has a negative value of about -2.5×10 ^-6 /°C;
On the other hand, as shown in straight line b, α is approximately +2.5×10 ^-6 /℃
It shows a wide variety of temperature characteristics, including those with a positive value of , and those where α is almost zero, as shown by the straight line c. Also, α of the oscillator after formation is −2.5
It is within the range of ×10 ^-6 /°C to +2.5 ^{× 10 -6} /°C.
The fact that α is positive, negative, or almost zero is defined as follows.

(1) The fact that the first-order temperature coefficient α is almost zero means that α
is within ±1.0×10 ^-7 /℃.

(2) The first-order temperature coefficient α is positive, which means that α>
It refers to something that is at 1.0×10 ^-7 /℃.

(3) The first-order temperature coefficient α is negative, which means that α is α<
-1.0×10 ^-7 /°C.

Figure 4 shows an example in which weights 10 and 11 are attached to a GT-cut crystal resonator by plating, and the weights 10 and 11 are attached symmetrically to the ends of the resonator in the width W direction and at approximately the center position in the length direction. Weight 10.1 with a thickness of 1.0μ to 2.0μ
1 is placed.

FIG. 5 shows the change in the primary temperature coefficient α with respect to the amount of the weights scattered when the weights 10 and 11 of FIG. 4 are scattered by a laser. That is, as the amount of weight scattering increases, the primary temperature coefficient α moves to the positive side.

FIG. 6 shows an example in which weights 12, 13, 14, and 15 are arranged by plating at the four corners of a GT cut crystal resonator.

Figure 7 shows the weights 12, 13, 14, 1 in Figure 6.
5 shows the relationship between the first-order temperature coefficient α and the amount of the weight scattered when the weight is scattered by a laser. As the amount of weight scattering increases, the primary temperature coefficient α moves to the negative side.

As can be seen from these facts, in the case of the weight shown in Fig. 4, by scattering the weight, the primary temperature coefficient α becomes positive, and in the case of the weight arrangement shown in Fig. 6, the primary temperature coefficient α becomes positive. By scattering the weight, the primary temperature coefficient α moves to the negative side. That is, the weights 10, 11 in FIG. 4 and the weights 12, 13, 14, in FIG.
When the weight is placed between 15 and 15, it can be predicted that the primary temperature coefficient α will not change at all.

Figure 8 shows another example of the weight arrangement of the GT cut crystal resonator, with weight 10 in Figure 4 and weight 1 in Figure 6.
2 is a plan view in which weights 16 and 19 are arranged between weights 2 and 15, and weights 17 and 18 are arranged between weight 11 and weights 13 and 14.

Figure 9 shows the weights 16, 17, 18, 1 in Figure 8.
The relationship between the first-order temperature coefficient α and the amount of weight scattering when 9 is scattered by a laser is shown, and it can be seen that the first-order temperature coefficient α does not change due to the weight scattering.

Figure 10 shows weights 10 and 11 in Figure 4, weights 12, 13, 14, and 15 in Figure 6, and weight 1 in Figure 8.
Figure 4 shows the change in the resonance frequency of the main vibration with respect to the amount of weight scattering when 6, 17, 18, and 19 are respectively scattered by a laser.
This corresponds to the cases shown in FIGS. 8 and 6. It can be seen that in any case, the resonance frequency of the main vibration increases depending on the amount of scattering of the weight.

FIG. 11 shows an embodiment of the weight arrangement of the GT cut crystal resonator of the present invention, in which weights 10, 11, 1
2, 13, 14, 15, 16, 17, 18, 19
is located.

Next, the resonance frequency adjustment and temperature characteristic adjustment method of the present invention will be specifically explained.

The GT cut crystal resonator shown in FIG. 11 is formed by photography and then designed to have the following characteristics.

(1) The resonant frequency of the main vibration has a value lower than the reference frequency f ₀ to be matched. (Usually 1000ppm~
(2000ppm lower)
This can be easily obtained by selecting the weight plating thickness. Next, this vibrator is placed at a certain arbitrary temperature, this temperature is read with a thermometer such as a thermistor, and this temperature is set as _t1 . At this time, the resonance frequency f ₁ of the main vibration is measured. Furthermore, the vibrator is placed at any other temperature, and the temperature _t2 at this time is read in the same manner as above. At this time, the resonance frequency f ₂ of the main vibration is measured. The primary temperature coefficient α is determined from the following equation using the temperatures t ₁ and t ₂ and the resonance frequencies f ₁ and f ₂ .

α=f ₂ −f ₁ /t ₂ −t ₁ (Hz/°C) (2) Also, when rewritten using the reference frequency f ₀ to be adjusted, it becomes as follows.

α=f ₂ -f ₁ /f ₀ 1/t ₂ -t ₁ (1/℃) ......(3) Figure 12 shows this situation, and the straight line g is the line of the present invention when α is negative. This is an example. The temperature t ₀ is the temperature at which the resonance frequency of the main vibration is adjusted to the reference frequency f ₀ . At temperature t ₀ , the main resonance frequency f
is lower than the reference frequency f ₀ . Therefore,
There are three methods described above for adjusting the resonance frequency f of the main vibration to the reference frequency f ₀ by scattering a weight using a laser. However, in this case, since α is negative, α can be further reduced by adopting a method in which α moves to the positive side. That is, this is a method in which the weights 10 and 11 shown in FIG. 11 are scattered with a laser. Straight lines h and i in FIG. 12 show changes in temperature characteristics when the resonance frequency f of the straight line g is adjusted to the reference frequency f ₀ by scattering the weights 10 and 11 with a laser. As it approaches the standard frequency f ₀ , α approaches zero (straight line h), and when adjusted to the standard frequency f ₀ , α becomes almost zero (straight line i).

FIG. 13 shows an example of the temperature characteristics of the present invention obtained in this manner. The straight line j is the temperature characteristic after the resonator is formed, α≒-1.5×10 ^-6 /℃, and the straight line k is the temperature characteristic when the main resonance frequency f is adjusted to the reference frequency f ₀ , α≒-3× It can be seen that the temperature is considerably small at 10 ^-7 /°C, indicating good temperature characteristics.
In exactly the same way, when α is positive, α can be brought closer to zero by adopting a method in which α moves to the negative side when adjusting the main resonance frequency f to the reference frequency f ₀ . That is, the weights 12,1 in FIG.
This method uses a laser to scatter the weights at at least one of the locations No. 3, 14, and 15. Also, when α is almost zero, there is no need to change α, so there is a method in which α does not change when the resonance frequency f is adjusted to the reference frequency f ₀ , that is, the weights 16 and 1 in FIG.
It is sufficient to employ a method of scattering the weights at at least one of 7, 18, and 19 with a laser.

The present invention has been described in detail above, but the gist of the means and steps for realizing the intended frequency adjustment can be summarized as follows.

The main vibration and sub-vibration are combined, and the main vibration is
A coupled vibrator consisting of a substantially rectangular vibrating part with sub-vibration in the long side direction, and four corners 12 to 15 of the vibrating part
and an end portion 1 approximately at the center of the vibrating portion in the length L direction.
0, 11, and a total of 10 locations 16 to 19 between the four corners and the substantially central end, a step of providing weights by selective plating means, and then a step of forming the outer shape of the vibrator by etching. In the coupled resonator, the resonant frequency of the main vibration of the formed resonator is controlled in the plating step and the etching step so that it is 1000 to 2000 ppm lower than the reference frequency f ₀ to be matched. The primary temperature coefficient α of the resonator is: (1) When α is almost zero, −1.0×10 ^-7 /℃≦α≦1.0×10 ^-7 /℃ (2) When α is positive, α＞ 1.0×10 ^-7 /°C (3) Negative α is defined as α<-1.0×10 ^-7 /°C. a step of placing the vibrator at a certain arbitrary first temperature t ₁ and measuring the first resonant frequency f ₁ at that time; then placing the vibrator at a certain arbitrary second temperature f ₂ ; Second resonant frequency f ₂ at that time
, a step of determining the first-order temperature coefficient α from the relationship between these (t ₁ , f ₁ , t ₂ , f ₂ ), and then, if the first-order temperature coefficient α of the obtained result is positive, the vibration A step of irradiating and scattering a laser beam on at least one weight at the four corners 12 to 15 of the child to raise the resonance frequency of the main vibration and match it to the reference frequency f ₀ , the first-order temperature coefficient α of the obtained result is negative. If there is, the ends 10, 1 approximately in the center of the vibrating part of the vibrator in the long side direction.
Irradiate and scatter a laser beam on at least one of the weights of 1 to increase the resonance frequency of the main vibration to the reference frequency f ₀
If the first-order temperature coefficient α of the obtained result is almost zero, there is It is characterized by a step of irradiating and scattering a laser beam on at least one of the weights Nos. 16 to 19 to raise the resonant frequency of the main vibration and match it to the reference frequency _f0 , thereby reducing the coupled vibration. Optimal temperature characteristics before child frequency adjustment,
In addition, design a vibrator to obtain the optimum resonance frequency of the main vibration, measure the resonance frequencies f ₁ and f ₂ of the main vibration at arbitrary temperatures t ₁ and t ₂ , and calculate the primary temperature coefficient α from these values.
Further, to provide a GT cut crystal resonator with excellent temperature characteristics in which the primary temperature coefficient α is almost zero by laser f tuning and the resonance frequency of the main vibration is tuned to f ₀ . was completed. This has made it possible, for example, to realize high-precision wristwatches. In addition, this method measures the temperature characteristics of each vibrator one by one, and then adjusts the primary temperature coefficient.
The defective rate due to temperature characteristics was significantly reduced. Therefore, it has become possible to reduce costs.

Although the present invention has been explained using a GT-cut crystal resonator, it goes without saying that the concept of the present invention can be applied to other coupled resonators, such as an FT-cut crystal resonator.

[Brief explanation of drawings]

Figure 1 shows an example of the shape and electrodes of a coupled resonator.
This is an example of a GT cut crystal resonator. A is a plan view,
B shows a side view. FIG. 2 shows an example of a GT-cut crystal resonator mounted on a support, and shows a plan view A and a side view B. FIG. 3 is a graph showing an example of the temperature characteristics of a GT cut crystal resonator formed by photolithography. Figure 4 shows
FIG. 2 is a plan view showing an example in which a weight is attached to a GT cut crystal resonator by plating. FIG. 5 is a graph showing the change in the primary temperature coefficient α with respect to the amount of the weight scattered when the weight shown in FIG. 4 is scattered by a laser. FIG. 6 is a plan view showing an example in which weights are attached to the four corners of a GT cut crystal resonator by plating. FIG. 7 is a graph showing the relationship between the first-order temperature coefficient α and the amount of the weight scattered when the weight shown in FIG. 6 is scattered by a laser. FIG. 8 is a plan view showing another example of the weight arrangement of the GT cut crystal resonator. Figure 9 shows the first temperature coefficient α for the amount of weight scattering when the weight in Figure 8 is scattered by a laser.
It is a graph showing the relationship between Figure 10 shows the fourth
Weights 10 and 11 in the figure, weights 12 and 13 in Figure 6,
14, 15, weights 16, 17, 18, 1 in Figure 8
9 is a graph showing the change in the resonance frequency of the main vibration with respect to the amount of weight scattering when each of the weights is scattered by a laser, and the straight lines d, e, and f are respectively shown in FIGS. 4 and 8.
This corresponds to the case shown in FIG. Figure 11 shows
FIG. 2 is a plan view showing an embodiment of the weight arrangement of the GT cut crystal resonator of the present invention. The straight line g in FIG. 12 is a graph showing the relationship between the main resonance frequency and the temperature of an oscillator with a negative first-order temperature coefficient α, and the straight line h
and i indicate the change in temperature characteristics when the resonant frequency is adjusted to the reference frequency f ₀ . FIG. 13 is a graph showing an example of temperature characteristics obtained by the present invention. 10-19... Weight.

Claims (1)

[Scope of Claims] 1 A coupled vibrator consisting of a substantially rectangular vibrating section in which a main vibration and a sub-vibration are coupled, with the main vibration in the direction of the short side and the sub-vibration in the direction of the long side; 1
5, approximately central ends 10 and 11 in the length L direction of the vibrating section, and 16 to 19 between the four corners and the approximately central end, at a total of 10 locations by selective plating means. The process of providing a weight, then the process of forming the external shape of the vibrator by etching, so that the resonant frequency of the main vibration of the formed vibrator is 1000 to 2000 ppm lower than the standard frequency f ₀ to be matched. In the coupled resonator controlled by the plating process and the etching process, the primary temperature coefficient α of the formed resonator is: (1) When α is almost zero, it is −1.0×10 ^-7 /℃≦α≦ 1.0×10 ^-7 /℃ (2) Positive α is defined as α＞1.0×10 ⁻⁷ /℃ (3) Negative α is defined as α＜−1.0×10 ⁻⁷ /℃. The process of placing this vibrator at an arbitrary first temperature t ₁ and measuring the first resonant frequency f 1 at that time, then placing the vibrator at an arbitrary second temperature t ₂ and measuring the first resonant frequency f ₁ at that time. _{Step of} measuring _the second resonant frequency _{f 2} when If the coefficient α is positive, a step of irradiating and scattering a laser beam on the weight at at least one of the four corners 12 to 15 of the vibrator to raise the resonance frequency of the main vibration and match it to the reference frequency f ₀ ; If the primary temperature coefficient α as a result of
Irradiate and scatter a laser beam on at least one of the weights of 1 to increase the resonance frequency of the main vibration to the reference frequency f ₀
If the first-order temperature coefficient α of the obtained result is almost zero, there is 1. A method for manufacturing a coupled resonator, comprising a step of irradiating and scattering a laser beam on at least one weight of Nos. 16 to 19 to raise the resonance frequency of the main vibration to match the reference frequency f ₀ .