JPH0828640B2 - Vertical crystal unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a vertical crystal unit covering a frequency range of around 1 MHz and a medium frequency band. In particular, it relates to the shape of the vibrator and the excitation electrode.

[Outline of Invention]

An object of the present invention is to provide a vertical crystal resonator having extremely small vibration leakage, that is, a small loss resistance R ₁ . Quartz is a physically and chemically stable substance. Therefore, a so-called crystal oscillator formed from this can obtain a oscillator having a low 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 energy of the vibrating section can be confined inside the vibrating section by devising and improving the shape of the supporting section of the vertical crystal unit in which the vibrating section and the supporting section are integrally formed by the etching method. That is, an object of the present invention is to obtain a vertical quartz oscillator having a small vibration leak. Further, the present invention is to provide an excitation electrode having a low loss resistance R ₁ .

[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 .

[Problems to be solved by the invention]

For this reason, the amplification degree of the amplifier has been increased, but there is a drawback that the current consumption increases, and in a severe case, when it is placed in a device, vibration leakage is large and oscillation is stopped. It was happening. Therefore, the present invention proposes a vertical crystal oscillator having a very small vibration leakage. That is, it provides a very small shape of vibration leakage. At the same time, the present invention provides an electrode arrangement with high excitation efficiency.

[Means for solving problems]

The present invention solves the above problem by the following method. That is, the crystal unit has one end surrounded by a mount part, both sides surrounded by an outer frame, and the other end surrounded by a frame, and the vibrator is supported by a bent part forming a support part and the bent part. A vertical crystal unit formed by an etching method and integrally formed by an etching method, wherein the bent portion surrounds the mount side of the vibrating portion and both sides thereof, and the base portion is connected to the frame. The frame is further connected to an outer frame, the width of the outer frame is constant, and the upper surface electrode arranged in the vibrating portion extends to the mount portion on the same plane through the bridge portion. The object of the present invention is achieved by arranging the lower surface electrode of (1) so as to extend through the bridge portion to the mount portion on the same plane. Next, the principle of the present invention will be described.

FIG. 1 is a simplified diagram for explaining the principle of the vertical quartz crystal resonator of the present invention. The vibrator 1 includes a vibrating part 2 and a supporting part 3
It can be considered that the support portion 3 is fixed under the condition that one end is fixed and the other end is supported. Also, the vibration part 2
Is represented by a length L ₁ , a width W ₁ , and a thickness T, and the supporting portion 3 has a length L ₂ ,
Expressed in width W _2, now, the vibration unit 2 of the vibrator 1 as indicated by an arrow A, when the displacement of the elongation, the support unit 3 generates a mode of bending inwardly as indicated by naturally arrow B. 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. The shape and size are determined by the strain energy of the vibrating part 2. That is, when the strain energy of the vibrating portion 2 is U _{1 and} the strain energy of the bending portion is U ₂ , U ₁ and U ₂ are represented by the following equations.

However, stress T ₂ , strain S ₂ , Young's modulus E, second moment of area I, displacement v, volume V ₁ , V ₂ , and coordinate x are shown. In addition, the relationship that does not suppress the vibration of the vertical crystal resonator is based on the equations (1) and (2).

U ₁ > U ₂ − (3) From this, the dimensions L ₂ and W _{2 of} the bent portion 5 are determined. For example, the dimension of the vibrating portion at the frequency of 1 MHz of the present invention is the length L ₁
= 2.6 mm, W ₁ = 80 μm, T = 160 μm, the dimensional ratio W ₂ / L ₂ of the bent part of the supporting part should 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. 1, 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 supporting portion 3, and the mode of the supporting portion 3 is converted into the bending mode, so that the mass of the mounting portion of the fixing portion, that is, the fixing portion, is infinitely large. If so, the energy of the supporting portion 3 does not leak. Similarly, energy leakage can be eliminated by making the support portion 3 having the condition of supporting the other end free. In other words, the present invention makes the vibration of the vibrating portion free by selecting the shape of the supporting portion 3 transmitted from the vibrating portion 2 into the bending mode, that is, the ratio of the width and the length of the bending portion. In addition, the object of the present invention is achieved by increasing the mass of the portion that is connected to the portion that is deformed in the bending mode and by making it freely rotatable.

Next, the excitation electrode where the loss resistance R ₁ is small will be described. As you can see from the coordinate system, the vertical crystal unit in Fig. 2 is Y
Displace in the axial direction. Therefore, an electric field application method in which a large amount of distortion in the Y-axis direction occurs may be considered. That is, due to the piezoelectricity of the crystal, electrical polarization in the X-axis, Y-axis, and Z-axis directions And Where ε ₁₁ and ε ₁₄ are piezoelectric constants, ε _xx , e _yy , e _yz ,
e _zx and e _xy represent distortion. As is clear from the equation (4), in order to cause the displacement in the Y-axis direction, an electric field may be applied so as to satisfy the first equation of the equation (4). That is, the electric field may be applied in the X-axis direction. In other words, the electrodes may be arranged on the surface perpendicular to the X axis.

More specifically, the upper surface electrode arranged in the vibrating portion extends to the mount portion on the same plane via the bridge portion, and the lower surface electrode of the vibrating portion extends to the mount portion on the same plane via the bridge portion. It is located there.

[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. Further, when the excitation electrode is provided on the surface perpendicular to the X axis, a vertical crystal unit having a small R ₁ can be obtained.

〔Example〕

Next, the results obtained by the present invention will be specifically described. FIG. 2 shows an embodiment of a vertical quartz oscillator according to the present invention. The oscillator 1 is composed of a vibrating portion 2 and a supporting portion 3 and is integrally formed by an etching method. Usually, it is configured with a cut angle that facilitates etching. Now, the electric axis of the crystal is X
Assuming that the axes are the Y axis, the mechanical axis is the Z axis, the optical axis is the Z axis, and the rotation angle around the Y axis is θ, then θ is determined according to the required specifications from 40 degrees to 70 degrees. At this time, the excitation electrodes are arranged on the upper and lower surfaces of the vibrating portion 2. That is, the upper surface electrode 8 and the lower surface electrode 9. Further, both electrodes 8 and 9 are provided to the mount portion 7 via the support portion 3 and fixed by the mount portion 7. From this, by applying an alternating voltage to the upper surface electrode 8 and the lower surface electrode 9, expansion and contraction movements are made in the longitudinal direction, but at the same time, the same vibration is made in the vertical direction, that is, in the direction of the bridge portion 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 bridge portion 4 direction is sufficiently free. Therefore, in the present invention, the bending portion of the supporting portion 3 is used. 5 is determined by the ratio of the length L and the width W. That is, if the frequency is about 1MHz and W / L is 0.16 or less,
Suppression of longitudinal vibration can be prevented. next,
The vibration leak is integrally formed from the vibration portion 2 to the bent portion 5 via the bridge portion 4 by an etching method, and the end portion thereof is connected to the frame 6. At this time, the bending portion 5 vibrates in the bending mode, but one end is connected to the frame 6,
Since the other end surrounds the vibrating portion 2 and has a structure capable of freely vibrating, that is, it vibrates with a boundary condition that one end is fixed and the other end is supported. Therefore, when the mass of the frame 6 is increased, energy can be trapped in the tip portion of the support portion 3, so that even if the mount portion 7 fixes the energy,
It is possible to obtain a vertical crystal unit with no vibration leakage.

〔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 and a vertical quartz oscillator with upper and lower excitation electrodes, 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.

Connect the bent part to the frame in the opposite direction to the mount part,
Further, since the frame has a mass effect, vibration leakage is reduced.

Since the excitation electrodes are arranged on the upper and lower surfaces of the vibrating portion, the electric field strength becomes constant, and the variation of the loss resistance R ₁ becomes small and at the same time becomes low.

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

[Brief description of drawings]

FIG. 1 is a simplified plan view for explaining the principle of the vertical crystal unit of the present invention. FIG. 2 is a plan view showing an embodiment of the vertical crystal unit geometry and excitation electrode arrangement of the present invention. 1 …… Vibrator 2 …… Vibration part 3 …… Supporting part 4 …… Bridge part 5 …… Bending part 6 …… Frame 7 …… Mounting part 8 …… Upper surface electrode 9 …… Lower surface electrode θ …… Cut angle X , Y, Z …… Crystal axis L ₁ …… Vibration part length W ₁ …… Vibration part width T …… thickness

Claims (1)

[Claims] 1. A crystal resonator, one end of which is surrounded by a mount portion, both sides of which are surrounded by an outer frame, and the other end of which is surrounded by a frame. The resonator includes a bent portion forming a support portion and a bent portion therebetween. Is a vertical crystal unit integrally formed by an etching method, wherein the bent portion surrounds the mount side of the vibrating portion and both sides thereof, and the base portion thereof is The frame is connected to a frame, the frame is further connected to an outer frame, the width of the outer frame is constant, and the upper surface electrode disposed in the vibrating portion extends to the mount portion on the same plane through the bridge portion. The vertical crystal unit is characterized in that the lower surface electrode of the vibrating portion is arranged to extend through the bridge portion to the mount portion on the same plane.