JP2002111434A - Quartz vibrator of larmor vibration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quartz vibrator of Larmor vibration enabling to suppress unnecessary vibrations, enabling to obtain a stable vibration mode with suppressing an increasing of equivalent resistance even if the size is downsized and also fitting for mass production. SOLUTION: In the quartz vibrator, outline vibrations around boundary of a small vibration part 27 with reference to vibration nodes 31a-31d at four corners of each vibration part 27 are occurred by inputting electric field to make adjacent small exciting electrodes 26 be opposite in polarity along with forming more than one vibration part 27 having roughly same shape as the electrodes 26 by arranging a plurality of square shaped electrodes 26 in the cross direction on both sides of a square shaped vibration board 21 which is cut from a quartz ore.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal resonator that performs contour vibration (lame vibration), and more particularly to a Lame vibration crystal resonator in which a diaphragm that performs contour vibration is formed by a plurality of small vibrating portions. It is.

[0002]

2. Description of the Related Art At present, a thickness shear vibration mode is one of the most widely used vibration modes of a quartz oscillator in a frequency range of several MHz to several tens of MHz. In order to realize this thickness-shear vibration, the quartz substrate is cut at an AT cut angle inclined by about 35 ° 15 ′ from the Z axis, using the X axis of the quartz crystal as the rotation axis, and the portion to be a vibrating part is formed in a predetermined shape. Has been processed. The crystal resonator manufactured in this manner is generally called an AT-cut thickness-sliding crystal resonator. This AT-cut thickness-sliding crystal resonator has excellent frequency-temperature characteristics such that frequency fluctuation is small over a wide temperature range.

[0003] On the other hand, several quartz oscillators (Lame oscillation quartz oscillators) accompanied by contour oscillation (Lame oscillation) have been devised or put into practical use. This Lame vibrating crystal resonator is 36 ° to 42 ° with the Y axis directed to the Z axis with the X axis as the center.
LQ2T cut quartz substrate cut out on the XY ′ plane composed of the Y ′ axis inclined in the range described above is used. This LQ
The 2T cut quartz substrate is easily processed into a predetermined shape to obtain characteristics as calculated theoretically, and has excellent mass productivity.

As shown in FIG. 7, the lame vibrating crystal resonator 1 supports a vibrating plate 2 composed of a vibrating part having a minimum configuration formed by processing a quartz substrate cut from the above-described rough quartz, and the vibrating plate 2. It comprises a support leg 3 and a support portion 5 on which electrode terminals 4a and 4b are provided. FIG. 7A is a plan view seen from a surface based on the electrode terminal 4a, and FIG.
FIG. 7B is a plan view seen from the surface based on the electrode terminal 4b, and corresponds to the back surface side of FIG.
Indicates the cross-sectional shape of the Lame vibrating crystal resonator 1. The vibration plate 2 is a thin square plate-like piece. When the vibration frequency is set to, for example, 10 MHz, one side is formed to be about 240 μm.
Two corner portions (2b, 2d) of the diaphragm 2 are connected to both support legs 3, and are connected to a support portion 5 on which electrode terminals 4a, 4b are formed. A pair of excitation electrodes 6 are formed on the front and back surfaces of the diaphragm 2, and are electrically connected to the respective electrode terminals 4a and 4b provided on the support portion 5. Electric fields having different polarities are applied to the excitation electrodes 6 on the front and back sides, and the Lame vibration is caused by the four nodes 2 a to 2 d of the diaphragm 2.
Is performed on the basis of

FIG. 7 shows a crystal oscillator of the lowest vibration mode in which one vibrating portion is formed for one vibration plate 2. The Lame vibrating crystal oscillator 11 shown in FIG. It has a tertiary vibration mode in which three small vibration parts 13a to 13c are arranged in a line on a rectangular vibration plate 12. As described above, by increasing the order of vibration, a crystal resonator having high vibration accuracy and low equivalent resistance can be obtained (1).
EM Symposium, May 18, 995, "Lame Mode Quartz Crystal Formed by Etching").

The diaphragms 2 and 12 shown in FIGS.
Are supported at the vibration nodes 2a to 2d and 12a to 12d so that the equivalent resistance value does not increase and the Q value does not decrease. Further, in the case of the above-mentioned lame vibrating crystal resonator 11, the small vibrating portions 13a to 13c are square in shape with nodes at four corners, and perform lame vibration when the ratio of the lengths of adjacent sides is one.

[0007]

However, in the thickness-shear vibrating crystal resonator most frequently used in the frequency range of several MHz to several tens of MHz, unnecessary vibrations other than the required vibration frequency range are required. (Spurious) is generated, and the equivalent surface resistance is deteriorated due to the reduction of the vibration surface as the element is downsized.

On the other hand, the vibration frequency f of the LQ2T cut crystal resonator is represented by f (MHz) = 2400 / a, where a (μm) is the length of one side of the vibrating portion.
It depends only on the width of the diaphragm, the thickness does not affect the vibration frequency. On the other hand, it is known that the equivalent resistance decreases as the thickness of the diaphragm decreases. However, there is a limit to thin processing in view of processing accuracy and strength.

If instead of the above-described thickness-shear vibrating crystal resonator, the lame-vibrating crystal vibrators 1 and 11 as shown in FIGS. 7 and 8 are used, the occurrence of spurious components may be reduced due to the structural difference. Are known. However, when the element is downsized, the diaphragms 2 and 12 cannot be sufficiently widened, so that the equivalent resistance cannot be significantly improved. Also,
In Lame vibration, precise machining accuracy is required in order to obtain high-precision and stable oscillation characteristics.
The mass production of the Lame vibrating crystal resonator having the vibration frequency characteristic of z to several tens of MHz has been hardly performed.

[0010] Some Lame vibrating quartz resonators have a 1 × n vibrating plate in which vibrating portions are connected in a line in the vertical direction. However, sufficient vibration energy is obtained at a frequency around 10 MHz. However, there was a limit in reducing the equivalent resistance value. From this, 1 × as shown in FIG.
A Lame vibrating crystal resonator having three or more diaphragms has not been manufactured.

Therefore, an object of the present invention is to provide a stable vibration mode without generating spurious components and suppressing an increase in equivalent resistance even when the size is reduced, and which is suitable for mass production. It is to provide a crystal oscillator.

[0012]

In order to solve the above-mentioned problems, a Lame vibrating crystal resonator according to claim 1 of the present invention comprises:
In a quartz crystal resonator in which four corners of a rectangular diaphragm having excitation electrodes formed on both sides are vibration nodes and Lame oscillation occurs, the excitation electrodes are arranged in a plurality of square-shaped small excitation electrodes in the vertical and horizontal directions. And the electric field applied to the adjacent small excitation electrode has a reverse polarity.

According to the present invention, since a plurality of square-shaped small excitation electrodes are formed on the diaphragm, mass production of a high-order Lame vibrating crystal resonator having a small equivalent resistance becomes easy.
In addition, by applying an electric field of opposite polarity alternately to adjacent small excitation electrodes, the influence of electric fields of different polarities adjacent to each other even on a diaphragm with no contour as a crystal at the center of the array. Therefore, the vibration of the contour does not decrease. Therefore, the difference in vibration between the outer peripheral portion and the central portion of the diaphragm is small, and uniform vibration characteristics can be obtained. Further, by forming a plurality of small vibrating portions having a basic vibration frequency in a plane in the vertical and horizontal directions, a large vibrating surface can be obtained as a whole, and the equivalent resistance can be reduced.

According to a second aspect of the present invention, in the lame vibrating crystal resonator according to the first aspect, the vibrating plate comprises an odd number of small vibrating portions arranged in the vertical and horizontal directions.

According to the present invention, since the odd number of small vibrating portions formed on the diaphragm are arranged in the vertical and horizontal directions, the distortion of the entire diaphragm is vertically and horizontally symmetrical, and the center of gravity shifts during vibration. Disappears. Further, there is no vibration energy leaking out of the diaphragm, so that the equivalent resistance is reduced.

According to a third aspect of the present invention, there is provided the lame vibrating crystal resonator according to the first or second aspect, wherein the diaphragm surface immediately below the small excitation electrode is formed with individual small vibrating portions having nodes at four corners. This is characterized in that a contour vibration is obtained at a boundary side where the small vibration portions are adjacent to each other.

According to the present invention, the small excitation electrodes having the same shape as the small excitation electrodes are continuously formed by uniformly arranging the small excitation electrodes of the same shape on the both sides of the diaphragm. For this reason, continuity between the nodes at the four corners of each small vibrating portion is ensured, and accurate contour vibration can be obtained at the boundary side where the small vibrating portions are adjacent to each other.

According to a fourth aspect of the present invention, in the Lame vibrating crystal resonator according to the first or second aspect, the voltage applied between the small excitation electrodes is supplied from the vicinity of the four corner nodes of the small vibration part. And

According to the present invention, since the adjacent small excitation electrodes have opposite polarities, the small excitation electrodes having the same polarity are obliquely arranged. Therefore, if the wiring pattern is formed through the four corner nodes of the small vibrating portion formed below each small excitation electrode, conduction can be made at the shortest distance. Therefore, it is possible to minimize the extra capacitance of the capacitor other than the small excitation electrode portion and obtain a high-quality vibration mode with little noise.

According to a fifth aspect of the present invention, in the lame vibrating crystal resonator according to the first or second aspect, each of the small excitation electrodes is
It is characterized in that each small vibrating part is formed in a plane with an area ratio of 70% or more.

According to the present invention, each small vibration portion is defined by a size corresponding to the area of the small excitation electrodes arranged and formed. By making the small excitation electrode as large as possible, the boundary of the adjacent small vibrating part in the direction of the electric field becomes clear, and a large amplitude vibration can be generated even in the small vibrating part near the center without a contour as quartz. , The equivalent resistance can also be reduced. Conversely, if the electrode area is 50% or less, the boundary condition between adjacent small vibrating parts is not clear, and it is difficult to generate Lame vibration. For this reason, in order to provide continuity between the respective small vibrating parts, it is preferable to arrange the small excitation electrodes without gaps, but it is necessary to provide gaps for forming insulation and wiring patterns. Each small excitation electrode
By forming a plane with an area ratio of 70% or more with respect to each small vibrating portion, insulation and wiring can be performed, and large amplitude Lame vibration can be generated, so that the equivalent resistance value can be reduced. .

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a Lame vibrating crystal resonator according to the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 are plan views of a Lame vibrating crystal resonator according to a first embodiment of the present invention, in which a vibrating plate includes small vibrating portions arranged in a 3 × 3 array. FIG. 3 is a side view of the Lame vibrating crystal resonator. FIGS. 4 and 5 are operation diagrams showing the vibration mode of the small vibrating portion constituting the Lame vibrating crystal resonator, FIG. 5 is an operation diagram showing the vibration mode of the entire diaphragm in the first embodiment, and FIG. 6 is the present invention. FIG. 8 is an operation diagram showing a vibration mode in a second embodiment having a diaphragm composed of small vibrating portions in a 5 × 5 array.

According to the vibration mode, the quartz crystal is cut at a predetermined inclination from the crystal axes of the X-axis (electric axis), Y-axis (mechanical axis), and Z-axis (optical axis) of the quartz crystal. The substrate is punched into various shapes to form a crystal resonator having a specific vibration mode.

The Lame vibrating crystal resonator according to the present invention is formed of a crystal substrate having a certain crystal orientation from the quartz crystal. In particular, when the Y-axis is directed to the Z-axis around the X-axis,
A quartz substrate cut out on an XY ′ plane consisting of a Y ′ axis inclined at a range of 2 °, and this quartz substrate is further cut by X
The LQ2T cut quartz substrate cut out by rotating 45 ° in the Y ′ plane is suitable for a Lame vibrating quartz resonator having stable vibration characteristics.

As shown in FIGS. 1 to 3, the shape of the diaphragm 21 is a rectangular diaphragm 21 having vibration nodes 22a, 22b, 22c, and 22d at four corners, and the four nodes 22a to 22a.
Support legs 23a, 23b, 23c, 23d supporting 2d
And a support portion 24 integrally formed by punching the support legs 23a to 23d. The support portion 24 has a pair of electrode terminals 25a and 25b. Sign 1
Reference numeral 9 denotes a punched void portion, which is provided at four places along each side of the diaphragm 21.

A plurality of small excitation electrodes 26 as shown in the enlarged view of FIG. Then, the individual small excitation electrodes 26 arranged as described above become individual small vibration parts 27. The Lame vibrating crystal resonator 20 in the present embodiment is a configuration example when assuming a vibration frequency in a 10 MHz band that is often used as a basic frequency of a portable electronic device. FIG. 1 is a plan view as viewed from a surface on which a wiring pattern extending from the electrode terminal 25a is formed, and FIG. 2 is a plan view as viewed from a surface on which a wiring pattern extending from the electrode terminal 25b is formed. FIG. 2 shows the shape and arrangement of the lame vibrating crystal resonator 20 of FIG. 1 when viewed from the front. FIG. 3 shows a cross-sectional shape along the line AA in FIGS. (Hereinafter, FIG. 1 is referred to as a front surface and FIG. 2 is referred to as a back surface.) The basic small vibration portion 27 has 24 sides L3 and L4.
The vibration plate 21 is a square having a size of 0 μm, and the diaphragm 21 has a size (L
1, L2 is a square of 720 μm). The small excitation electrodes 26 are formed on the front and back surfaces of the vibration plate 21 serving as the small vibration part 27. Therefore, the nodes of vibration are the four corners 31a to 31d of each small vibration part 27 and the four corners 2 of the entire diaphragm 21.
2a to 22d are set.

An electric field is applied to the small excitation electrodes 26 provided on the front and back surfaces of the small vibrating portions 27 via conduction paths 27a and 27b extending from electrode terminals 25a and 25b having different polarities. The addition of these electric fields is set so that adjacent small vibrating portions 27 on the same plane generate electric fields of opposite polarities. For example, a diaphragm 2 having a 3 × 3 arrangement
In 1, the electric field supplied from the electrode terminal 25a is
The small excitation electrode (A1,
C1, E1, G1, I1) and the small excitation electrodes (B2, D2, F2, H2) on the back side of FIG. On the other hand, the electric field supplied from the electrode terminal 25b is transmitted through the small excitation electrodes (A2, C2, E2, G2, I2) on the back side of FIG. It is supplied to the small excitation electrodes (B1, D1, F1, H1).
As described above, the pattern is formed such that the electric field of the adjacent small excitation electrode always has the opposite polarity at each side of the small excitation electrode. Distortions such as alternate swelling or denting of the border sides between the portions 27 occur. This allows
Obtain the desired vibration frequency. When forming the wiring patterns 28 and 29 between the small excitation electrodes 26 and between the front and rear surfaces, the shortest distance is selected and formed so as to minimize the capacitance of the capacitor due to the wiring pattern. Since the small excitation electrodes 26 having the same polarity are arranged at oblique positions, they form a star-shaped connection pattern via the nodes of the small vibration part 27. As described above, since the vibration frequency f of the Lame vibrating crystal resonator of the present invention is determined by the lengths L3 and L4 of one side of each small vibrating portion 27, it is assumed that L3 and L4 = a (μm). , F (MH
z) = 2400 / a. For this reason, the diaphragm 2
Although there is no relation between the number arranged in one and the vibration frequency, the effect of reducing the equivalent resistance appears by widening the surface of the whole vibrating portion, and the characteristics of the crystal resonator are improved.

If the area where the small excitation electrode 26 is formed is 50% or more of the entire small vibrating portion 27, the equivalent resistance value will be practically no problem, but if it is 70% or more, the equivalent resistance is significantly reduced. The effect can be expected. However, each small excitation electrode 26
Since a gap for forming insulation and a wiring pattern must be secured between them, it is desirable to form the gap at 80 to 90%.

The supporting legs 23a to 23d are
At the same time as supporting the four nodes 22a to 22d, and at the same time, forming a conduction path for conducting the electric charges from the electrode terminals 25a and 25b to the small excitation electrode 26 of each small vibrating portion 27. Is done.

The diaphragm 21 is formed integrally with the support 24 via the support legs 23a to 23d. This support leg 2
By performing the steps 3a to 23d at the four corners of the diaphragm 21 which are the nodal points, good oscillation characteristics can be obtained without obstructing the vibration, but the vibration is supported at the nodes of the small vibrating parts 27 of the diaphragm. However, oscillation characteristics that are practically no problem are obtained.

FIG. 4 schematically shows the vibration mode of each of the small vibrating sections 27. As shown in FIG. As the vibration phenomenon, the electrode part 2
By applying an electric field from 5a, 25b to the sides 32a to 32d of the small vibrating portion 27 via the support legs 23a to 23d, the sides 32a to 32d are represented by dotted lines in the drawing with reference to the vibration nodes 31a to 31d. It bends as shown in (a) and (b). By repeating such operations (a) and (b) continuously, a vibration having a constant cycle can be obtained. In order to obtain an accurate and stable vibration phenomenon, each of the nodes 31 a to 31 a
It is desirable to design the vibration width of 1d to be zero.

When the above vibrations are combined, a vibration form as shown in FIG. 5 is obtained. As described above, the opposing sides bulge outward or dent inward based on the nodes 31a to 31d at the four corners of each small vibrating section 27, and propagate to the sides of the adjacent small vibrating sections 27, A higher-order vibration mode is obtained as the whole diaphragm 21. Since the oscillation frequency at this time depends on the length of one side of each small vibrating portion 27, the vibration plate 21
Although the vibration frequency as a whole does not change, the equivalent resistance value decreases as the vibration surface increases.

In the above-mentioned Lame vibrating crystal resonator 20,
An ideal design example for obtaining a vibration frequency of 10 MHz is based on FIG.
3, L4 = 240 μm, the arrangement of the small vibrating parts 27 is 3 ×
3 and the lengths L1 and L2 of one side of the diaphragm 21 =
720 μm, area ratio of small vibrating part 27 and small excitation electrode 26 =
10: 9.

FIG. 6 shows a second embodiment of the Lame vibrating crystal resonator according to the present invention. The number of small vibrating portions 27 formed on the diaphragm 21 is increased in the vertical and horizontal directions to form a 5 × 5 structure. It was done. The quartz oscillator in this configuration example also has
It is assumed that a vibration frequency of 10 MHz, which is the same as that of a crystal resonator having a × 3 configuration, is assumed. The length of one side of each small vibration part 27 is 240 μm, and the length of one side of the diaphragm is 1200 μm.
Becomes As described above, by increasing the number of the small vibrating portions 27 formed on a single diaphragm, the equivalent resistance value can be further reduced as compared with the Lame vibrating crystal resonator having the 3 × 3 configuration.

The frequency characteristics of the lame vibrating quartz crystal resonator having the 5 × 5 configuration were examined.
A resonance phenomenon at 870 MHz was confirmed. The equivalent resistance R1 at this time is 4.7 kΩ. In addition, for the 1 × 5 configuration of the lame vibrating crystal resonator manufactured at the same time,
Since the equivalent resistance value has increased so that the resonance phenomenon cannot be confirmed, the effect of reducing the equivalent resistance of the Lame vibrating crystal resonator of the present example was confirmed. Since the crystal unit used in this measurement was in the prototype stage, the above values were obtained. However, the error range of the oscillation frequency was ± 10 ppm, and the equivalent resistance was 10%.
It can be reduced to about 0Ω.

As described above, the effect of reducing the equivalent resistance can be expected as the number of the small vibrating portions 27 is increased. In the case of a crystal resonator having a vibration frequency around ten and several MHz as in the present invention, a configuration of about 5 × 5 is appropriate in consideration of the package size. In the case of designing a crystal resonator having a higher vibration frequency, the length of one side of the small vibrating portion 27 is reduced, so that a higher-order Lame vibration crystal resonator can be manufactured. Therefore, productivity is improved as well as miniaturization.

The Lame vibrating crystal resonator as shown in the above embodiment is formed by punching a flat vibrating piece cut out of a rough quartz crystal to form supporting legs and a vibrating plate of a predetermined shape. For this formation, a chemical etching or a cutting method using a powder beam is used.

In this embodiment, the small vibrating portion 27 is 3 ×
Although an example of an odd square array configuration such as 3, 5 × 5 is shown,
An odd rectangular array such as 3 × 5 may be used. If the arrangement is odd in both the vertical and horizontal directions, one small vibrating portion is always located at the center of the diaphragm, so that the vibration balance as a whole as a whole becomes good. Further, depending on the size and oscillation accuracy of the crystal resonator package, an even square arrangement such as 2 × 2 or 4 × 4 or a rectangular arrangement such as 2 × 3 or 3 × 4 is also possible. However, in order to perform accurate rame vibration, the shape of each small vibration part 27 which is a component is square,
Each contour vibration form must be uniform.

[0039]

As described above, in the conventional crystal oscillator of the thickness-shear vibration system, spurious vibration accompanied by the vibration of the contour is generated together with the vibration in the thickness direction, so that a pure vibration characteristic can be obtained. However, the use of the Lame vibrating crystal resonator of the contour vibration system as in the Lame vibrating crystal resonator of the present invention resulted in less spurious generation and stable oscillation characteristics.

The small vibrating section 27 is 3 × 3 or 5 ×
Since a plurality of arrays were formed on the same surface as in No. 5, the vibration surface was widened, and an effect of reducing the equivalent resistance was achieved.

Further, since the design of the Lame vibrating quartz resonator is easier than that of other vibrating mode quartz resonators, it is possible to mass-produce a stable product without any man-hours.

[Brief description of the drawings]

FIG. 1 is a plan view of a front side of a Lame vibrating crystal resonator according to a first embodiment of the present invention.

FIG. 2 is a plan view of the back surface of the Lame vibrating crystal resonator when viewed from the front side.

FIG. 3 is a cross-sectional view taken along line AA of the Lame vibrating crystal resonator in FIGS. 1 and 2;

FIG. 4 is an operation diagram showing a vibration mode of each small vibrating portion constituting the above-mentioned Lame vibrating crystal resonator.

FIG. 5 is an operation diagram showing a vibration mode of the entire diaphragm of the Lame vibrating crystal resonator.

FIG. 6 is an operation diagram showing a vibration mode in a second embodiment of the Lame vibrating crystal resonator according to the present invention.

FIG. 7 is a plan view of a conventional Lame vibrating crystal resonator.

FIG. 8 is a plan view of the above-mentioned other Lame vibrating crystal resonator.

[Explanation of symbols]

 21 diaphragm 26 small excitation electrode 27 small vibration part 31a-31d node

Continuation of the front page (72) Inventor Hiromoto Yuki 2-1-1-11 Fujimigaoka, Nirasaki-shi, Yamanashi F-term in River Eletech Corporation (reference) 5J108 AA01 BB02 CC04 CC10 CC11 DD03 FF04

Claims (5)

[Claims] 1. A quartz vibrator in which four corners of a rectangular vibration plate having excitation electrodes formed on both surfaces thereof vibrate as lame vibrations at four corners, wherein the excitation electrode is formed by vertically and horizontally extending a small excitation electrode having a square shape. Wherein the electric field applied to the adjacent small excitation electrodes has an opposite polarity. 2. The Lame vibrating crystal resonator according to claim 1, wherein the vibrating plate comprises an odd number of small vibrating portions arranged in the vertical and horizontal directions. 3. A vibration plate immediately below the small excitation electrode is formed as an individual small vibrating portion having nodes at four corners, and the small vibrating portion obtains a contour vibration at a boundary side adjacent to each other. The lame vibrating crystal resonator according to claim 1 or 2, wherein: 4. The Lame vibrating crystal resonator according to claim 1, wherein a voltage applied between the small excitation electrodes is supplied from the vicinity of four corner nodes of the small vibration part. 5. The crystal oscillator according to claim 1, wherein each of said small excitation electrodes is formed in a plane with an area ratio of 70% or more with respect to each of said small vibration parts.