JPH01212013A - Longitudinal crystal vibrator - Google Patents

Abstract

PURPOSE:To decrease the leakage of vibration by allowing a bent part connected from a vibration part to surround the vibration part of a vibrator, connecting the bent part to a frame opposite to the mount side and arranging an excitation electrode onto the vertical face of the vibration part. CONSTITUTION:The bent part 5 is formed incorporatedly by the etching method from the vibration part 2 via a bridge part 4 and its end is connected for a frame 6. In this case, the bent part 5 is vibrated by the bending mode, but since the bent part is structured in such way that the one end is connected to the frame G and the other end surrounds the vibration part 2 so as to be vibrated freely, that is, the bent part is vibrated with the boundary condition that one end is fixed and the other is supported. Since the energy is confined in the tip of the support part 3 by increasing the mass or the frame 6, the longitudinal crystal vibrator without leakage of vibration is obtained regardless of the fixing at the mount part 7.

Description

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

[Summary of the invention]

An object of the present invention is to provide a vertical crystal resonator with very little vibration leakage, that is, with a low loss resistance R3. 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 small vibration leakage. By devising and improving the shape of the support section of the crystal resonator, the energy of the vibrating section can be confined within the vibrating section. That is, an object of the present invention is to obtain a vertical crystal resonator with small vibration leakage. A further object of the present invention is to provide an excitation electrode with a reduced loss resistance R.

[Conventional technology]

In conventional vertical crystal oscillators, 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. Therefore, the loss resistance RI
It was not possible to obtain a small vertical crystal oscillator.

[Problem that the invention seeks to solve]

This has been dealt with by increasing the amplification degree of the amplifier, but this has drawbacks such as increased current consumption, and in severe cases, when placed in equipment, there is a big problem of vibration leakage and oscillation stopping. was occurring. Therefore, the present invention proposes a vertical crystal resonator with extremely small vibration leakage. That is, it provides a shape with very little vibration leakage. At the same time, the present invention provides an electrode arrangement with high excitation efficiency.

[Means for solving problems]

FIG. 1 is a simplified diagram for explaining the principle of the vertical crystal resonator of the present invention. The vibrator 1 consists of a vibrating part 2 and a support part 3, and the support part 3 can be considered to be fixed under the condition that one end is fixed and the other end is supported. Also, if the vibrating part 2 is represented by length L++ width W + and thickness T, and the support part 3 is represented by length + width W2, then the vibrating part 2 of the vibrator 1 is now as shown by arrow A. , when the support part 3 undergoes an elongation displacement, naturally a bending mode occurs inward as shown by arrow B.

Here, the part where the bending mode occurs is shown as a bending part 5. Conversely, when the vibrating part 2 contracts, the bending part 5 of the support part 3 generates a bending mode outward. That is, in the present invention, by converting the displacement of the vibrating part 2 in the width direction into the bending mode of the support part 3, the degree of freedom of vibration is not suppressed. In reality, there are dimensions that do not suppress vibrations. This shape and dimension is determined by the strain energy of the vibrating section 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+ and Uz are the following formula %. However, stress 'rz + strain 321 Young's modulus E, moment of inertia of area ■, displacement V9 volume V1. V! + indicates coordinate X.

In addition, the relationship that does not suppress the vibration of the vertical crystal oscillator is expressed by equation (11,
+21, the following relationship holds true.

U, > U, -+31 From this, the dimensions Lx and Wx of the bent portion 5 are determined.

For example, the dimensions of the vibrating part when the frequency of the present invention is IMHz are length L + '= 2.661111. W + =
When 80' μm and T=160 um, the dimension ratio Wi/Lx of the bent portion of the support portion should be 0.16 or less. By determining the dimensions in this way, the loss resistance is small.
Moreover, a vertical crystal resonator with a high Q value can be obtained.

Next, we will discuss vibration leakage. As can be seen from the simplified diagram in FIG. Therefore, the support part 3
It is better to reduce the energy loss at the support part 3.
Since the mode is converted into a bending mode, if the mass of the part where the fixed part is mounted at one end, that is, the mass of the fixed part is infinitely large, the energy of the support part 3 will not leak.

Similarly, energy leakage can be eliminated by making the support part 3 free, which has the condition of supporting the other end. In other words, in the present invention, the support part 3 transmitted from the vibrating part 2
By selecting the shape that converts to the bending mode, that is, the ratio of the width and length of the bending part, the vibration of the vibrating part can be made free,
In addition, the object of the present invention is achieved by increasing the mass of the portion that connects to the portion that undergoes bending mode deformation and making it rotatable.

Next, we will discuss the excitation electrode with a small loss resistance R1.
Displaced in the axial direction. Therefore, an electric field application method that generates a large amount of distortion in the Y-axis direction may be considered. That is, due to the piezoelectricity of the crystal, the Y axis, the Y axis.

If the electric polarization in the Z-axis direction is lP, ,P, ,P, then PX
= gth eX, -εII 6 yv” 'g'+48 F
! P,=−ε! Segx 2εzh e 1IyP,
= O-+41 However, ε, ε are piezoelectric constants, εll+ eyy+
e, □ eIX+ eXF represents distortion. Formula (4
), 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 (4).

That is, it is sufficient if the electric field is applied in the X-axis direction. In other words, the electrodes may be arranged on a plane perpendicular to the Y axis.

[Effect]

In this way, the present invention is composed of 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, the 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 quartz crystal resonator with small vibration leakage can be obtained. Furthermore, Y
If an excitation electrode is provided on a plane perpendicular to the axis, a vertical crystal resonator with a small R1 can be obtained.

〔Example〕

Next, the results obtained with the present invention will be specifically described. Second
The figure shows an embodiment of a vertical quartz crystal resonator according to the present invention, and the resonator 1 is composed of a vibrating section 2 and a support section 3, which are integrally formed by an etching method.

It is usually constructed with a cut angle that is easy to etch.

Now, if the electric axis of the crystal is the Y axis, the mechanical axis is the Y axis, and the optical axis is the Y axis, and the rotation angle around the Y axis is θ, θ is 40 degrees to 70 degrees.
It can be determined from among the degrees according to the required specifications. At this time, the excitation electrodes are arranged on the upper and lower surfaces of the vibrating section 2. That is, the upper surface electrode 8 and the lower surface electrode 9. Further, the picture electrode 8.9 is connected to the support part 3.
It is provided up to the mount part 7 via the mount part 7, and is fixed by the mount part 7. Therefore, by applying an alternating voltage to the upper surface electrode 8 and the lower surface electrode 9, an expansion and contraction movement is performed in the longitudinal direction, but at the same time, a similar vibration is also generated 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 part 2, it is important to make the vibration in the bridge part 4 direction sufficiently free. It is determined by the ratio of the length and width W of 5. That is, when the frequency is IMHz, if W/L is 0.16 or less,
Zero-order, which can prevent the suppression of longitudinal vibrations,
The vibration leakage is integrally formed from the vibrating part 2 to the bending part 5 via the bridge part 4 by an etching method, and the end thereof is formed by etching.

It is connected to frame 6. At this time, the bending part 5 vibrates in a bending mode, but one end is connected to the frame 6, and the other end surrounds the vibrating part 2 so that it can freely vibrate, so one end is fixed and the other end is connected to the frame 6. It vibrates with the boundary condition of support. Therefore, if the mass of the frame 6 is increased (then the energy can be confined in the tip of the support part 3, even if it is fixed with the mounting part 7, a vertical crystal resonator with no vibration leakage can be obtained).

[Effects of the Invention] As described above, the present invention has been achieved by proposing a vertical crystal resonator with a new shape and upper and lower excitation electrodes in a vertical crystal resonator in which the vibrating part and the supporting part are integrally formed by an etching method. , has the following remarkable effects.

■ By improving the shape and dimensions of the support part, vibration can be made free, so loss resistance is reduced.

■ Since the bent part is connected to the frame in the opposite direction to the mount part, and the frame has a mass effect, vibration leakage is reduced.

(2) Since the excitation electrodes are arranged on both the upper and lower sides of the vibrating section, the electric field strength becomes constant, and the variation in loss resistance R becomes smaller and lower at the same time.

■ Since it is mounted on one side, manufacturing is easy and miniaturization is possible.

[Brief explanation of the drawing]

FIG. 1 is a simplified plan view for explaining the principle of the vertical crystal resonator of the present invention. FIG. 2 is a plan view showing an embodiment of the vertical crystal resonator shape and excitation electrode arrangement of the present invention. l... Vibrator 2... Vibrating part 3... Supporting part 4... Bridge part 5... Bent part 6... ...Frame 7...Mount part 8...Top electrode 9...Bottom electrode θ...Cut angle x, y, z...Crystal axis, ... Length W of the vibrating section, ... Radiation T of the vibrating section... Thickness or more Applicant Seiko Electronic Components Co., Ltd. Agent Seiko Electronics Co., Ltd. Head Office January! ! Ri Eho floor plan Figure 1 unfinished - 171'! ,, second concave plane concavity of luster example

Claims (1)

[Claims] In a vertical crystal resonator in which the vibrating part and the support part are integrally formed by etching, the bent part connected from the vibrating part surrounds the vibrating part of the vibrator, and the bent part is connected to the frame opposite to the mount side. A vertical crystal resonator, characterized in that the excitation electrodes are arranged on the upper and lower surfaces of the vibrating section.