JP2004248237A - Tuning fork type crystal resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grooved tuning fork type crystal resonator, of which the problem that a tuning fork arm is easily destroyed due to vibration and shocks, etc. due to problems in the mechanical strength of the tuning fork arm, since the thickness of a groove of the tuning fork arm is small, and since it is about half of the thickness near the outer side of the tuning fork arm, is solved and which is small in size, of high performance, high in shock resistance and low in price. <P>SOLUTION: The tuning fork arms 2, 3 of the tuning fork type crystal resonator 1 have grooves 6 to 13, whose shapes of cross sections in thickness directions are almost V-shaped along longitudinal directions of front surfaces and rear surfaces. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a new-shaped tuning-fork type crystal resonator that realizes miniaturization, high performance, impact resistance, and low cost.
[0002]
[Prior art]
Tuning fork-type quartz resonators are used in large quantities as time and frequency reference sources for watches, clocks, computers, mobile phones, home appliances, AV equipment, OA equipment, and the like. Such a conventional tuning-fork type crystal resonator will be described below with reference to the drawings.
[0003]
4 (a) is a plan view, FIG. 4 (b) is a sectional view taken along the line BB ', and FIG. 5 is a tuning fork arm portion of a conventional grooved tuning fork type crystal resonator. FIG.
[0004]
4 (a) and 4 (b), a tuning fork type crystal resonator 60 includes a left tuning fork arm 61, a right tuning fork arm 62 and a base 63 connecting the two arms, and a tuning fork surrounded by the two arms and the base. It is composed of a part 64. The X, Y, and Z axes represent crystal axes of quartz.
[0005]
The side electrodes 65 and 66 provided on the side surface of the left tuning fork arm 61 are connected to have the same potential as the plane electrodes 71 and 72 provided on the front and back surfaces of the right tuning fork arm 62. Similarly, the side electrodes 69 and 70 provided on the side surface of the right tuning fork arm 62 are connected to have the same potential as the plane electrodes 67 and 68 provided on the front and back surfaces of the left tuning fork arm 61 (see FIG. 4). The connecting portion is not shown, and the same applies to FIGS.
[0006]
When an AC voltage is applied to the tuning fork arm through the electrode, an electric field as indicated by an arrow is generated. The direction of the component of the electric field in the X-axis direction is reversed inside the crystal. As a result, each tuning fork arm expands and contracts on the left and right sides of the neutral line, and the left and right tuning fork arms perform bending vibration in opposite phases in the X-axis direction.
[0007]
2. Description of the Related Art In recent years, with the spread of small portable devices represented by mobile phones, there is a strong demand for downsizing, high performance, impact resistance, and low cost of tuning fork type crystal units. To realize this, a grooved tuning-fork type crystal resonator shown in FIG. 5 has been proposed. This is achieved by providing grooves 75 and 76 along the longitudinal direction of the front and back surfaces of the left tuning fork arm portion 73 and grooves 77 and 78 along the longitudinal direction of the front and back surfaces of the right tuning fork arm portion 74. Formed with side electrodes 79, 80, side electrodes 83, 84 on the right tuning fork arm, and left groove electrodes 81, 82 and right groove electrodes 85, 86 corresponding to plane electrodes in the groove of each tuning fork arm. It is. The connection of each electrode is performed in the same manner as in the type of FIG.
[0008]
When an AC voltage is applied to the tuning-fork arm through such a grooved tuning-fork type quartz vibrator through an electrode, a vertical electric field is generated between the side electrode and the groove electrode as indicated by an arrow. This electric field is the electric field itself generated in the X-axis direction. Therefore, compared with the type shown in FIG. 4, the electromechanical conversion efficiency is improved, and a small tuning-fork type crystal resonator having a good CI value and Q value can be obtained (for example, see Patent Documents 1 and 2). .
[0009]
The tuning-fork type quartz vibrator is made by a photolithography technique and a chemical etching technique. As an example, for a typical frequency of a tuning fork type of 32.768 Khz, the dimensions of the type shown in FIG. 4 are 3.5 mm in overall length, 0.75 mm in overall width, 0.1 mm in thickness, and 2.5 mm in length of the tuning fork arm. The grooved tuning fork type has a total length of 2.2 mm, a total width of 0.56 mm, a thickness of 0.2 mm, a tuning fork arm length of 1.6 mm, and a tuning fork arm width of 0.1 mm with respect to the tuning fork arm width of 0.25 mm. And miniaturized. The groove has a groove width of 0.07 mm, a groove length of 1.3 mm, and a groove depth of 0.05 mm. Incidentally, 400 grooved tuning-fork type crystal units are manufactured from one crystal wafer.
[0010]
[Patent Document 1]
JP-A-52-61985 (pages 7-8, FIG. 4)
[Patent Document 2]
JP-A-2002-76827 (page 6-7, FIG. 2)
[0011]
[Problems to be solved by the invention]
However, in the conventional grooved tuning-fork type quartz resonator, the groove has a rectangular cross-sectional shape, so that the thickness of the groove portion of the tuning-fork arm portion is about half the thickness of the outer portion. The area of the thin portion occupies about 60% of the entire area of the tuning fork arm. For this reason, there is a problem in mechanical strength of the tuning fork arm portion, and there has been a problem that the groove portion on the base side of the tuning fork is damaged in the short direction when subjected to disturbance such as impact or vibration. Further, there is also a problem that the cost cannot be reduced due to the complicated processing steps for forming the grooves.
[0012]
An object of the present invention is to solve the above-mentioned problems, and to provide a tuning-fork type crystal resonator that is optimal for miniaturization, high performance, impact resistance, and low cost.
[0013]
[Means for Solving the Problems]
A tuning-fork type quartz resonator according to the present invention for achieving the above object has the following features.
[0014]
The tuning-fork type crystal resonator according to the invention according to claim 1 is a tuning-fork type crystal resonator, wherein the vibrator has a cross-sectional shape in a thickness direction of the tuning fork arm along a longitudinal direction of a front surface and a back surface of the tuning fork arm. It has a substantially V-shaped groove.
[0015]
The substantially V-shaped groove of the tuning-fork type quartz resonator according to the second aspect has two positions on the front surface and the back surface of the tuning-fork arm portion, respectively.
[0016]
A substantially V-shaped groove of the tuning-fork type crystal resonator according to claim 3 is provided on one of the front surface and the back surface of the tuning-fork arm portion and two on the other surface. It is.
[0017]
The substantially V-shaped groove of the tuning-fork type quartz resonator according to the fourth aspect is characterized in that it has one groove on each of the front and back surfaces of the tuning-fork arm.
[0018]
The width dimension of the substantially V-shaped groove of the tuning fork arm portion in the width direction of the tuning fork arm portion of the tuning fork type quartz resonator according to claim 5 is smaller than the width dimension of the tuning fork fork portion.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A and 1B show a tuning-fork type crystal resonator according to a first embodiment of the present invention, wherein FIG. 1A is a plan view, FIG. 1B is a sectional view taken along the line AA ′, and FIG. FIG. 3 is a sectional view of a tuning fork arm of a tuning fork type crystal resonator according to a third embodiment of the present invention, and FIG. 3 is a sectional view of a tuning fork arm of a tuning fork type crystal resonator according to a third embodiment of the present invention.
[0020]
In the first embodiment shown in FIGS. 1A and 1B, a tuning fork crystal unit 1 includes a left tuning fork arm 2, a right tuning fork arm 3, a base 4 for connecting two arms, and two arms. And a tuning fork portion 5 surrounded by a base portion. The X, Y, and Z axes represent crystal axes of quartz.
[0021]
The front and back surfaces of the left tuning fork arm 2 have grooves 6, 7, 8 and 9 having a substantially V-shaped cross section in the arm thickness direction along the longitudinal direction. Similarly, the front and back surfaces of the right tuning fork arm 3 have substantially V-shaped grooves 10, 11, 12, and 13. That is, there are two substantially V-shaped grooves on each of the front and back surfaces of each tuning fork arm portion, and are formed symmetrically with respect to the center line of the width and thickness. The width w of these grooves is smaller than the width W of the tuning fork.
[0022]
The side electrodes 14, 15 provided on the side surface of the left tuning fork arm portion 2 are substantially V-shaped grooves 10, 11 on the surface of the right tuning fork arm portion 3, the groove electrode 20 provided on a plane portion therebetween, and the substantially V-shaped groove on the back surface. It is connected so that it may become the same potential as the mold grooves 12 and 13 and the groove electrode 21 provided in the plane part between them.
[0023]
Similarly, the side electrodes 16, 17 of the right tuning fork arm 3 are substantially V-shaped grooves 6, 7 on the surface of the left tuning fork arm 2, a groove electrode 18 provided on a plane portion therebetween, and a substantially V-shaped groove 8 on the back surface. , 9 and a groove electrode 19 provided in a plane portion therebetween.
[0024]
When an AC voltage is applied to the tuning fork arm through the electrode, as shown by the arrows, between the side electrodes 14 and 15 of the left arm 2 and the groove electrodes 18 and 19, and between the side electrodes 16 and 17 of the right arm 3 and the groove electrode. A vertical electric field is generated between 20 and 21. These electric fields are the electric fields generated in the X-axis direction as in the case of the grooved tuning fork type. As a result, the electromechanical conversion efficiency was improved, and a small tuning-fork type crystal resonator having good CI value and Q value was obtained.
[0025]
In addition, because of the substantially V-shaped groove, the thin portion of the tuning fork arm portion is reduced, the mechanical strength of the tuning fork arm portion is improved, damage due to impact or vibration is eliminated, and impact resistance is greatly improved. Was improved. Further, since the V-shaped groove processing and the tuning fork shape processing can be performed at the same time, the process is simplified and the cost can be reduced.
[0026]
In the second embodiment shown in FIG. 2, the front and back surfaces of the left tuning fork arm 22 have grooves 23, 24, and 25 having a substantially V-shaped cross section in the arm thickness direction along the longitudinal direction. are doing. Similarly, the front and back surfaces of the right tuning fork arm portion 26 have, along the longitudinal direction, grooves 27, 28, and 29 having a substantially V-shaped cross section in the arm thickness direction. These grooves may be two places on the front surface and one place on the back surface. One groove is formed at the center of the tuning fork arm, and two grooves are formed symmetrically with respect to the center line of the tuning fork arm.
[0027]
The side electrodes 37 and 30 provided on the side surface of the left tuning fork arm 22 are connected to have the same potential as the groove electrodes 35 and 36 provided on the right tuning fork arm 26. Similarly, the side electrodes 33 and 34 provided on the side surface of the right tuning fork arm 26 are connected to have the same potential as the groove electrodes 31 and 32 provided on the left tuning fork arm 22. Thereby, a vertical electric field can be generated as indicated by the arrow.
[0028]
In the third embodiment shown in FIG. 3, the left tuning fork arm 38 has substantially V-shaped grooves 40 and 41 at the center of the front and back surfaces thereof. At the center of the front and back surfaces, approximately V-shaped grooves 42 and 43 are provided at one place.
[0029]
The side electrodes 44 and 45 provided on the side surface of the left tuning fork arm 38 are connected to have the same potential as the groove electrodes 50 and 51 provided on the right tuning fork arm 39. Similarly, side electrodes 46 and 47 provided on the side surface of the right tuning fork arm 39 are connected to have the same potential as groove electrodes 48 and 49 provided on the left tuning fork arm 38. Thereby, a vertical electric field can be generated as indicated by the arrow. The width of the substantially V-shaped groove in the second and third embodiments is also made smaller than the width of the tuning fork.
[0030]
Also in these second and third embodiments, a vertical electric field is obtained and the mechanical strength of the tuning fork arm is improved.
[0031]
【The invention's effect】
As described above, according to the present invention, in the tuning-fork type crystal resonator, the resonator has a substantially V-shaped cross-sectional shape in the thickness direction of the tuning-fork arm along the longitudinal direction of the front surface and the back surface of the tuning-fork arm. By providing the grooves described above, a vertical electric field is obtained, the mechanical strength of the tuning fork arm is improved, and the processing step is simplified. As a result, a compact, high-performance, high-impact-resistance, low-cost tuning-fork type crystal resonator can be realized, and the effect of the present invention is extremely large.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of a tuning-fork type crystal resonator of the present invention, wherein (a) is a plan view and (b) is a cross-sectional view.
FIG. 2 is a cross-sectional view of a tuning-fork arm portion showing a tuning-fork type crystal resonator according to a second embodiment of the present invention.
FIG. 3 is a sectional view of a tuning-fork arm portion showing a tuning-fork type crystal resonator according to a third embodiment of the present invention.
4A and 4B show a conventional tuning-fork type crystal resonator, wherein FIG. 4A is a plan view and FIG. 4B is a cross-sectional view.
FIG. 5 is a cross-sectional view of a tuning fork arm showing a conventional grooved tuning fork type crystal resonator.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 tuning fork type crystal resonator 2 left tuning fork arm 3 right tuning fork arm 4 base 5 tuning fork fork 6, 7, 8, 9, 10, 11, 12, 13 substantially V-shaped grooves 23, 24, 25, 27; 28, 29 Substantially V-shaped grooves 40, 41, 42, 43 Substantially V-shaped grooves 14, 15, 16, 17 Side electrodes 37, 30, 33, 34 Side electrodes 44, 45, 46, 47 Side electrodes 18, 19 , 20, 21 Groove electrodes 31, 32, 35, 36 Groove electrodes 48, 49, 50, 51 Groove electrodes

Claims (5)

In the tuning fork type crystal resonator, the resonator has a groove having a substantially V-shaped cross section in the thickness direction of the tuning fork arm along the longitudinal direction of the front surface and the back surface of the tuning fork arm. Tuning fork type crystal oscillator. The tuning-fork type crystal resonator according to claim 1, wherein the substantially V-shaped groove has two positions on each of a front surface and a back surface of the tuning-fork arm portion. 2. The tuning-fork type crystal resonator according to claim 1, wherein one of the substantially V-shaped grooves is provided on one of the front surface and the back surface of the tuning fork arm portion and two of the grooves are provided on the other surface. . 2. The tuning-fork type crystal resonator according to claim 1, wherein the substantially V-shaped groove is provided at one position on each of the front surface and the back surface of the tuning-fork arm portion. The tuning-fork type crystal resonator according to claim 1, wherein a width of the substantially V-shaped groove in a width direction of the tuning-fork arm portion is narrower than a width of the tuning-fork fork portion.

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