JPH02132913A - Vertical crystal resonator - Google Patents

Abstract

PURPOSE:To obtain a vertical crystal resonator with high electric field efficiency and small loss resistance and small frequency variation by rotating a Z plate by -2 degree to +4 degree as considering X-axis to be an axis of rotation, and further, arranging an axis of excitation on an etched surface so as to have an electric field component in X-axis. CONSTITUTION:Because the vertical crystal resonator is formed into a desired shape, and its shape is complicated, it is formed by chemical etching. Therefore, an exciting electrode is formed on the etched surface. Since this vibrator moves in the direction of Y-axis in its coordinate system, the exciting electrodes 9, 10 are arranged on a plane almost perpendicular to X-axis. Thus, the electric field efficiency is made high, and the loss resistance is made remarkably small. Besides, since the Z plate to form this vibrator selects -2 deg. to +4 deg. of the cut angle theta of X-axis rotation in the coordinate system, top point temperature becomes -10 deg.C to +60 deg.C as shown in a figure. Accordingly, the vibrator of the specially small frequency variation in this range of the top point temperature can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vertical crystal resonator whose frequency covers a medium frequency band around 1 MHz. In particular, it concerns the shape of the vibrator, the cut angle, and the excitation electrode.

[Summary of the Invention] The present invention has very little vibration leakage and low R. The purpose of this invention is to provide a small, compact vertical crystal resonator.

Quartz is a physically and chemically very stable substance, and therefore, a so-called crystal resonator formed from it can have a low loss resistance and a high Q value. However, such excellent characteristics can only be obtained by designing a vibrator shape with minimal vibration leakage. In the present invention, the energy of the vibrating part can be confined within the vibrating part by devising and improving the shape of the supporting part of a vertical quartz crystal resonator in which the vibrating part and the supporting part are integrally formed by an etching method.

As a result, a vertical crystal resonator with a small loss resistance R1 and a high Q value can be obtained. Furthermore, by devising and improving the method of arranging the excitation electrodes, a vibrator with even lower R1 can be obtained. Furthermore, the invention consists in obtaining a cut angle that gives a zero temperature coefficient.

[Prior art 1] In a conventional vertical crystal resonator in which the vibrating part and the support part are integrally formed by etching, the width of the frame of the support part is uniform;
Moreover, since they are formed in the same direction and mounted at their ends, the energy of the vibrating part is transmitted to the mount part, causing vibration leakage. For this purpose, the loss resistance R,
It was not possible to obtain a small vertical crystal oscillator. [Problems to be Solved by the Invention] To address this problem, efforts have been made to increase the intensification degree of the intensifier, but this has drawbacks such as increased current consumption, and in severe cases, when placed in equipment, This caused a major problem in that vibration leakage was large and oscillation stopped. Therefore, the present invention proposes a vertical crystal resonator with extremely small vibration leakage. In other words, it provides a shape with very little vibration leakage. At the same time, although the vertical crystal resonator shape of the present invention has a more complicated shape than conventional ones, the cut angle that gives a zero c quality coefficient is also provided for the resonator of this shape. Furthermore, the present invention provides an electrode arrangement with high excitation efficiency. [Means for Solving the Problems] FIG. 1 is a plan view of an embodiment of the vertical crystal resonator of the present invention.
Figure 2 is a simplified plan view for explaining the principle of the vertical crystal oscillator shown in Figure 1. In Fig. 2, the vibrator consists of a vibrating part 2 and a support part 3, and the support part 3 can be considered to be fixed under the boundary condition of being supported at both ends. W1 and thickness T, and the support portion 3 has a length La. Expressed by the width W2, if the vibrating part 2 of the vibrator l undergoes an elongated displacement as shown by arrow A, then
The bent portion of the support portion 3 naturally generates a bending mode inward as shown by arrow B. Here, the portion where the bending mode occurs is shown as a bending portion 5. Conversely, if the vibrating part 2 contracts, the supporting part 3
The bending part 5 generates a bending mode in the outer part 11. In other words, in this defense, by converting the displacement in the width direction of the vibrating part 2 into the bending mode of the support part 3, the degree of freedom of the vibration can be increased. I try not to suppress it. In reality, there are dimensions that do not suppress vibration. The shape and dimensions are determined by the strain energy of the vibrating part 2. That is, if the strain energy of the vibrating part 2 is Ul and the strain energy of the bending part is U2, then U. ．． U. is expressed by the following equation.

However, stress T2. Strain Sz. Young's modulus E, second moment of area 1・■, displacement V, body immersion V. ．． V. , indicates the coordinate X. Also, the relationship that does not suppress the vibration of the vertical crystal oscillator is expressed by equation (1).
, (2), the following relationship holds. 01>U2-(3) From this, the dimension L2. of the bent portion 5. W2 is determined. For example, the dimensions of the vibrating part when the frequency of the present invention is 31 1 MHz are length L+ = 2.6 mm. W1=80um. T=16
When the thickness is 0um, the dimensional ratio of the bent portion of the support portion W2/L. It is sufficient if it is below 0.161',l. By determining the dimensions in this manner, a vertical crystal resonator with low loss resistance and a high Q value can be obtained. Next, we will discuss vibration leakage. As can be seen from the simplified diagram in FIG. 2, the vibrating energy of the vibrating part 2 is transmitted to the support part 3 via the bridge part 4. Therefore, it is only necessary to reduce the energy loss in the support part 3, and since the mode of the support part 3 is converted to a bending mode, if the masses of the support parts at both ends are substantially infinitely large, the bending The energy in the portion 5 will not leak up to the mount portion 8. In other words, the present invention has a shape that converts the bending mode of the support part 3 transmitted from the vibrating part 2, that is, the ratio W2/L of the width W2 and the length 2.
By selecting 2, the vibration of the vibrating part is made free, and the mass of the supporting part, which has the boundary condition of being supported at both ends connected to the bending mode part, is infinitely increased.
This achieves the objectives of the invention. Next, the frequency temperature characteristics will be described. In Figure 2, length L1 is thickness T and width W.
, when it is very large, it becomes the same as that of a conventional vertical crystal oscillator, and the frequency f1 at that time is expressed by the following equation.

However, ρ is the density of the crystal, S',2 is the elastic conformance, and m is the order of vibration. However, as in the present invention, L+ and T are much larger than W, and L1
When there is not much difference between T and T, the vibration in the longitudinal direction and the thickness T
Directional vibrations combine. Therefore, if the frequency when combined is f, it is expressed by the following equation. However, f2 is a frequency determined by the thickness T. or.
Km is the coupling coefficient. Therefore, using equation (5), the relationship between the dimensions and the frequency 1 degree coefficient with respect to the cut angle is calculated. From this, a cut angle that provides a zero temperature coefficient can be obtained. Next, loss resistance R. Let's talk about the excitation electrode that has a small value. As can be seen from the coordinate system, the vertical crystal oscillator in Figure 1 is Y? Displaced in the direction. Therefore, it is better to consider an electric field application method that generates more distortion in the Y-axis direction. That is, due to the piezoelectricity of the crystal, electric polarization in the X-axis, Y-axis, and Z-axis directions is caused by P. ．． P. P
．． Then, P m = Eth e xx+ E +ze yy+
L +4e yxP y ” F+z@e xx+ t
2ae XITp. =o
-(6) However, El1. εIzu, ε14, ε25, ε2
6 is piezoelectric constant + ewx+ eyy, e■, e1, em
y represents distortion. As is clear from equation (6), in order to cause displacement in the Y-axis direction, it is sufficient to apply an electric field so as to satisfy the first equation of equation (6). In other words, in a plane almost perpendicular to the X axis! Just place the poles. Since the vertical quartz crystal resonator of the present invention has a complicated shape, it is molded by chemical etching. Therefore, excited electrical holes are formed on the etched surface. [For use] As described above, the present invention comprises a vibrating section and a supporting section.
By improving the shape and dimensions of the support part of the vertical crystal resonator formed by the etching method, loss resistance is reduced.
Moreover, a vertical crystal resonator having a high Q value can be obtained. At the same time, by analyzing the vibration mode of the support part, a vertical crystal resonator with small vibration leakage can be obtained. Furthermore, in the present invention, the primary temperature coefficient becomes zero at room temperature due to the retraction of the cut angle, and a vertical crystal resonator with small frequency change can be obtained.
Furthermore, by providing an excitation electrode on a plane perpendicular to the X-axis, a vertical crystal resonator with a small R1 can be obtained.

[Example] Next, the results obtained in the present invention will be specifically described. 1st
The figure shows an embodiment of a vertical crystal resonator according to the present invention, in which a resonator 1 is constructed from a vibrating section 2 and a support section 3 via a blanking section 4, and is integrally formed by an etching method. Incidentally, the support section 3 consists of a bent section 5, a hole 7, a frame 6, and a mount section 8. The vibrating section 2 expands and contracts in the longitudinal direction by driving an external electric field, that is, by applying an alternating voltage to the excitation electrodes 9 and 10. It also vibrates in the same direction. At this time, first, in order to freely excite the vibration in the longitudinal direction of the vibrating part 2, it is important to make the vibration in the bridge part 4 direction sufficiently free. hole 7 so that 5 can vibrate sufficiently freely.
is provided. Also, depending on the ratio of the length of the bent portion 5 to the width W (not shown), for example, the frequency may be approximately IMH.
In the case of z, if the side ratio W/L is 0.16 or less, the suppression of longitudinal vibration can be made sufficiently small. Next, regarding vibration leakage, the vibrator 1 is integrally formed from the vibrating part 2 to the bending part 5 via the bridge part 4 by an etching method, and in order to make the vibration of the bending part 5 sufficiently free, holes are formed. 7 is provided. Further, both ends of the hole 7 are connected to the frame 6 and extend to the mount section 8. Therefore, the vibration of the vibrating part 2 in the direction of the bridge part 4 is converted into a bending mode, and since it is connected to the frame 6 through both ends of the hole and extends to the mount part, it can be fixed by the mount part 8. However, a vertical crystal resonator with no vibration leakage can be obtained. Further, the electrode arrangement is such that excitation electrodes 9 and 10 are provided on the vibrating section 2, and the excitation electrode 9 is further connected to the electrode 12 on the outer frame 6 through at least the surface of the bending section 5 and extends to the mount section 8. It is arranged as follows. On the other hand, excitation electrode 1
0 is similarly connected to the electric field 11 on the outer frame 6 through at least the surface of the bent part 5, and is connected to the mount part 8.
It extends to. Therefore, vibration can be sustained by applying an alternating voltage between both electrodes. FIG. 3 shows the coordinate system of the vertical crystal resonator of the present invention. Also, as is clear from Figure 2, the dimensions of the vibrating part of the vertical crystal resonator are length, width W, and thickness T, so from formula (5), the cut angle θ and the dimension ratio T/L ．． The first-order temperature coefficient α and the second-order temperature coefficient β are calculated as a function of 6. In the calculations of the present invention, they were obtained at an arbitrary temperature of 20°C. Therefore, the peak temperature at this time (Tp
) is calculated from the following formula. Figure 4 shows the dimension ratio T/L. The relationship between the cut angle θ of the X-axis rotation and the apex temperature fTp in the coordinate system of the vibrator shown in FIG. 3 when =0.062 is shown. When the cut angle θ is -2°, Tp is -10'C, and as θ increases, Tp also increases. When θ is 0°, Tp is about 2l°C, and when θ=4°, Tp is 60°C. In this way, Tp can be freely changed by changing the cut angle θ, and can be selected according to the required specifications. The present invention provides a cut angle θ such that Tp is -10°C to +60°C. That is, θ may be set to -2 degrees to +4 degrees. Therefore, a vertical crystal resonator with particularly small frequency change within the range of -10°C to +60°C can be obtained.

[Effect of the invention 1 As described above, the present invention achieves the following by proposing a vertical crystal resonator with a new shape in a vertical crystal resonator in which the vibrating part and the support part are integrally formed by an etching method. It has a remarkable effect. ■By improving the shape and dimensions of the support part, vibration can be made free, resulting in lower loss resistance.

■Since there is a hole between the bending part and the frame, the vibrating part can vibrate freely, and at the same time, the energy of the bending part is not transmitted to the frame, eliminating vibration leakage and fixing it with the mount part. However, a resonator with a small R can be obtained.

■Since the excitation electrode is provided on a plane roughly perpendicular to the X axis, the electric field efficiency is good and a small R can be obtained. ■There is a zero wettability coefficient depending on the selection of the Kasoto angle θ, so
Frequency changes become smaller over a wide temperature range.

■Since it is mounted on one side, it is easy to manufacture and can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the vertical crystal resonator shape and excitation electrode arrangement of the present invention. FIG. 2 is a simplified plan view for explaining the principle of the vertical crystal resonator of the present invention. Fig. 3 shows a mounting system for analyzing the frequency-temperature characteristics of the vertical crystal resonator of the present invention. Figure 4 shows the peak temperature and cut angle θ of the vertical crystal resonator of the present invention.
Indicates the relationship between l ・ 2 ・ 3 ・ 4 ・ 5 ・ 6 ・ 7 ・ 8 ・ 9, lO ・ 11. 12.L. L.・W. W.・L～VTX. Y. Z - Vibrator, vibrating part, support part, bent part of bridge part, frame hole mount part, excitation electrode, length of TL pole bent part, width of bent part, length of vibrating part, length of vibrating part. Width/thickness: electric axis, Isoshi axis, optical axis

Claims (1)

[Claims] A vertical crystal resonator in which the vibrating part and the supporting part are integrally formed by etching, and the vibrating part is connected to the bending part through the bridge part, and further connected to the frame through both ends of the hole. At the same time, in the one extending to the mount part, the Z plate is rotated -2 degrees to +4 degrees with the X axis as the rotation axis, and further, the excitation axis has an electric field component in the X axis direction.
A vertical crystal resonator characterized by being provided on an etched surface.