JPH0831764B2 - Electrode structure of vertical crystal unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a vertical crystal unit that covers a medium frequency band having a frequency of about 3 MHz. In particular, it relates to the shape of the vibrator and the arrangement of the excitation electrodes.

[Outline of Invention]

An object of the present invention is to provide a small-sized vertical crystal resonator having extremely small vibration leakage and small R ₁ . The crystal is physical,
Since it is a chemically very stable substance, a so-called crystal oscillator formed from this can obtain an oscillator having a small loss resistance and a high Q value. However, such excellent characteristics can be obtained only after designing a vibrator shape with small vibration leakage. In the present invention, the vibration part and the support part are integrally formed by an etching method, and the shape of the support part of the vertical quartz oscillator is devised and improved. It can be confined inside the vibrating part. As a result, it is possible to obtain a vertical crystal resonator having a small loss resistance R ₁ and a high Q value even at a high frequency. Therefore, the present invention is to provide an excitation electrode having a small loss resistance R ₁ and good electric field efficiency.

[Conventional technology]

In the conventional vertical crystal unit in which the vibrating portion and the supporting portion are integrally formed by the etching method, the width of the frame of the supporting portion is uniform and formed in the same direction, and the vibrating portion is mounted at the end. Energy was transmitted to the mount, causing vibration leakage. Therefore, it was not possible to obtain a vertical crystal unit having a small loss resistance R ₁ .
At the same time, R ₁ at the third harmonic vibration could not be reduced for the above reason.

[Problems to be Solved by the Invention]

For this reason, measures have been taken to increase the amplification of the amplifier, but there is a drawback in that the current consumption increases, and when it is severe, when installed in equipment, vibration leakage is large and oscillation is a major problem. Was occurring. Therefore, the present invention proposes a vertical crystal resonator having a very small vibration leakage. That is, it provides a very small shape of vibration leakage. At the same time, another object is to provide an excitation electrode having a small vibration leakage and a high excitation efficiency.

[Means for solving the problem]

FIGS. 1 (a) and 1 (b) are one embodiment showing the plane of the vertical crystal unit of the present invention, and FIG. 2 is a simplified plane for explaining the principle of the vertical crystal unit of FIG. It is a figure. In FIG. 2, the vibrator 1 includes a vibrating portion 2 and a supporting portion 3, and the supporting portion 3 can be considered to be fixed under the boundary condition of supporting both ends. The vibrating part 2 has a length L ₁ , a width W ₁ , and a thickness T.
When the support portion 3 is represented by a length L ₂ and a width W ₂ , the vibrating portion 2 of the vibrator 1 is now displaced by elongation as shown by an arrow A, and inside the vibrating portion 2, an arrow mark is formed. As indicated by B, the support portion 3 vibrates so as to be displaced in the arrow direction. That is, it vibrates in the third harmonic mode. Therefore, at this time, the bending portion of the support portion 3 naturally causes a bending mode to the outside as shown by the arrow C. Here, a portion where the bending mode occurs is indicated by a bent portion 5. On the contrary, when the vibrating portion 2 contracts, the bending portion 5 of the supporting portion 3 generates a bending mode to the outside. That is, in the present invention, the displacement of the vibration section 2 in the width direction is converted into the bending mode of the support section 3 so that the degree of freedom of the vibration is not suppressed. And, in reality, there is a dimension that does not suppress vibration. This shape size is determined by the strain energy of the vibrating portion 2. That is, the strain energy of the vibration part 2
U ₁ and U ₂ are represented by the following equations, where U ₁ and the strain energy of the bent portion are U ₂ .

However, stress T ₂ , strain S ₂ , Young's modulus E, moment of inertia of area I, displacement v, volumes V ₁ , V ₂ , and coordinates x are shown. In addition, the relationship that does not suppress the vibration of the vertical crystal unit is expressed by the equations (1) and (2).
Therefore, the following relation holds.

U ₁ > U _2- (3) From this, the dimensions L ₂ and W _{2 of} the bent portion 5 are determined. For example, the dimensions of the vibrating portion when the fundamental oscillation frequency of the third harmonic of the present invention is 1 MHz are length L ₁ = 2.6 mm, W ₁ = 80 μm, T = 160 μm.
When m, the dimension W ₂ / L ₂ of the bent portion of the supporting portion may be 0.16 or less. By determining the dimensions in this way, it is possible to obtain a vertical crystal resonator having a low loss resistance and a high Q value. Next, vibration leakage will be described. As can be seen from the simplified diagram of FIG. 2, the vibration energy of the vibration part 2 is transmitted to the support part 3 via the bridge part 4. Therefore, it suffices to reduce the energy loss in the support portion 3, and the mode of the support portion 3 is converted to the bending mode. Therefore, if the mass of the support portions at both ends is substantially infinitely large, the bending of the support portion 3 is performed. The energy of the part 5 does not leak to the mount part 8. In other words, the present invention relates to the vibrating section 2
By selecting the shape that is converted to the bending mode of the support portion 3 transmitted from the body, that is, by selecting the ratio W ₂ / L ₂ of the width W ₂ and the length L ₂ , the vibration of the vibrating portion is made free and the bending portion is The object of the present invention is achieved by infinitely increasing the mass of the supporting part having the boundary condition of supporting both ends to be connected.

[Action]

As described above, according to the present invention, by improving the shape and size of the supporting portion of the vertical crystal resonator formed by the etching method, which is composed of the vibrating portion and the supporting portion, the loss resistance is small and the high Q value is high. It is possible to obtain a vertical crystal oscillator having the same. At the same time, by analyzing the vibration mode of the support portion, a vertical crystal resonator with small vibration leakage can be obtained. Furthermore, by devising and improving the arrangement of the excitation electrodes, it is possible to easily induce third harmonic vibration and obtain a higher frequency.

〔Example〕

Next, the results obtained by the present invention will be specifically described. FIGS. 1 (a) and 1 (b) are one embodiment of the vertical quartz crystal resonator of the present invention. FIG. 1 (a) is a front view and FIG. 1 (b) is a bottom view. The vibrator 1 is composed of a vibrating portion 2 and a supporting portion 3 via a bridge portion 4, and is integrally formed by an etching method. The support portion 3 is composed of a bent portion 5, a hole 7, a frame 6 and a mount portion 8. The vibrating section 2 is driven by an electric field from the outside, that is, it expands and contracts in the longitudinal direction by the excitation electrodes 9 and 10, but at the same time, it also vibrates in the vertical direction, that is, in the direction of the bridge section 4. . At this time, first, in order to freely excite the vibration in the longitudinal direction of the vibrating portion 2, it is important that the vibration in the direction of the bridge portion 4 be sufficiently free. Therefore, in the present invention, the bending of the supporting portion 3 is performed. A hole 7 is provided so that the part 5 can freely vibrate. Also, the length L and width W of the bent portion 5 (not shown)
For example, when the frequency is about 3MHz, the side ratio W /
If L is 0.16 or less, the suppression of longitudinal vibration can be made sufficiently small. Next, for vibration leak,
The vibrator 1 includes a bending portion 5 from a vibration portion 2 via a bridge portion 4.
The hole 7 is formed integrally with the bent portion 5 by an etching method and is provided with a hole 7 in order to allow the bending portion 5 to freely vibrate. Further, both ends of the hole 7 are connected to the frame 6 and extend to the mount portion 8. Therefore, the vibration of the vibrating portion 2 in the direction of the bridge portion 4 is converted into the bending mode, and the hole 7
Since it is connected to the frame 6 through both ends and extends to the mount portion, even if it is fixed by the mount portion 8, a vertical crystal oscillator having no vibration leak can be obtained. Next, a method of exciting a third harmonic, which is a feature of the present invention, will be described. As shown in FIG. 2, the third harmonic vibration is represented by a displacement that extends outward and a displacement that contracts inward. Therefore, the excitation electrodes may be arranged so that the displacements shown by the arrows A and B occur. From this, as shown in FIGS. 1 (a) and 1 (b), the excitation electrodes 9 and 10 are divided into different electrodes and are divided into 3 by the vibration 2, so that the adjacent electrodes are applied with voltages of different polarities. Can be configured as. As a result, the third harmonic vibration can be easily induced. Further, the connection electrodes 13 and 14 for connecting the three divided electrodes of the same polarity are provided on the same plane. Further, the excitation electrodes 9 and 10 arranged in the vibrating portion 2 extend from the bent portion through the bridge portion through the frame to the mount portion, and the electrodes from the bridge portion 4 to the frame 6 are arranged on the entire surface. Has been done.

〔The invention's effect〕

As described above, the present invention provides a vertical crystal unit in which a vibrating portion and a supporting portion are integrally formed by an etching method,
By proposing a new shape of the vertical crystal oscillator and an electrode arrangement that easily excites the third harmonic vibration, the following remarkable effects are obtained.

By improving the shape and size of the supporting portion, it is possible to freely vibrate, so that the loss resistance is reduced.

Since a hole is provided between the bending part and the frame, the vibration of the vibrating part can be freely made, and at the same time, the energy of the bending part is not transmitted to the frame, so there is no vibration leakage and it can be fixed by the mount part. Also, a small R ₁ oscillator is obtained.

The vibrating portion is divided into three, and the adjacent electrodes are configured so that voltages of different polarities are applied, so
Higher frequencies can be obtained by easily inducing second harmonic vibration.

Since it is mounted on one side, it is easy to manufacture and can be downsized.

[Brief description of drawings]

FIGS. 1 (a) and 1 (b) are one embodiment showing the vertical crystal unit geometry and electrode arrangement of the present invention. FIG. 1 (a) is a front view and FIG. 1 (b) is a bottom view. FIG. 2 is a simplified plan view for explaining the principle of the vertical crystal unit of the present invention. 1 …… Vibrator 2 …… Vibrating part 3 …… Supporting part 4 …… Bridge part 5 …… Bending part 6 …… Frame 7 …… Hole 8 …… Mounting part 9,10 …… Excitation electrodes 11,12 …… Electrodes L, L ₂ …… Bend length W, W ₂ …… Bend width L ₁ …… Vibration length W ₁ …… Vibration width T …… Thickness

Claims (1)

[Claims] 1. A vibrating portion and a supporting portion are integrally formed by an etching method, the vibrating portion is connected to each bending portion through a pair of bridge portions, and each bending portion is connected through both ends of a hole. In a vertical quartz oscillator connected to one end of a frame and the other end of each frame extending to the same mount portion, the excitation electrode provided in the vibrating portion is divided into three, and adjacent electrodes are provided. Are configured so that voltages of different polarities are applied, connection electrodes for connecting the same poles of the three divisions are provided on the same plane of the vibrating portion, and the excitation electrode is connected to the frame from the bent portion through the pair of bridge portions. An electrode structure for a vertical crystal resonator, wherein the electrodes extend through the same mount portion and the electrodes from the bridge portion to the frame are arranged on the entire surface.