JP4020010B2 - Piezoelectric vibrating piece, piezoelectric device using the piezoelectric vibrating piece, mobile phone device using the piezoelectric device, and electronic equipment using the piezoelectric device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric vibrating piece, a piezoelectric device in which the piezoelectric vibrating piece is accommodated in a package, and a mobile phone and an electronic apparatus using the piezoelectric device.
[0002]
[Prior art]
Quartz containing a piezoelectric vibrating piece in a package for small information devices such as HDDs (hard disk drives), mobile computers, and IC cards, and mobile communication devices such as mobile phones, car phones, and paging systems. Piezoelectric devices such as vibrators and crystal oscillators are widely used.
FIG. 8 is a schematic plan view showing a known configuration example of a piezoelectric vibrating piece used in such a piezoelectric device (see Patent Document 1). FIG. 9 is an end view taken along line AA of FIG.
[0003]
In FIG. 8, the piezoelectric vibrating reed 1 is formed by etching from a quartz wafer made of, for example, a quartz crystal into a tuning fork shape as shown in the figure.
That is, the piezoelectric vibrating piece 1 is configured by a tuning fork type crystal piece including a base portion 5 and a pair of vibrating arms 6 and 7 extending in parallel from the base portion 5.
[0004]
The base portion 5 of the piezoelectric vibrating piece 1 is fixed to an electrode portion on the package side (not shown). As understood with reference to FIGS. 8 and 9, grooves 4 and 5 extending in the length direction are formed on the front and back surfaces of the vibrating arms 6 and 7. A driving electrode (not shown) is formed in the grooves 4 and 5. Notches 5a and 5b are provided on the outer edges in the width direction near the ends of the base 51 on the vibrating arms 6 and 7 side.
[0005]
Such a piezoelectric vibrating piece 1 is formed from the package side by fixing a portion of an extraction electrode (not shown) provided on the base 51 to a package-side electrode (not shown) with a conductive adhesive or the like. A driving voltage is applied to the driving electrodes formed in the groove portions 4 and 5 through the respective extraction electrodes.
As a result, the vibrating arms 6 and 7 bend and vibrate as indicated by the arrows in FIG. 8 with the distal ends 6a and 7a approaching and separating from each other. By taking out the vibration frequency based on such vibration, it is used for various signals such as a clock signal for control.
[0006]
[Patent Document 1]
JP 2002-261575 A
[0007]
[Problems to be solved by the invention]
When the piezoelectric vibrating reed 1 having such a structure is flexibly vibrated as indicated by an arrow in FIG. 8, a strain distribution is generated as shown in FIG.
That is, FIG. 10 is an analysis diagram simulating the distortion that occurs when the piezoelectric vibrating piece 1 undergoes flexural vibration, and the regions are shown in the order of the signs a, b, and c from the larger distortion. That is, the region a has the largest distortion, and the region c has the smallest distortion.
[0008]
According to FIG. 10, there is a region with a large strain in the vibrating arms 6 and 7 that vibrate and vibrate. Therefore, providing a driving electrode in the groove provided in this region causes energy for driving to the region with a large strain. Since it can supply, it is preferable.
However, according to FIG. 10, it can be understood that there is a region in which a large distortion is generated in the base portion of the vibrating arms 6 and 7 close to the crotch portion 8 between the vibrating arm 6 and the vibrating arm 7. Therefore, when the piezoelectric vibrating reed 1 or a piezoelectric device (not shown) that accommodates the piezoelectric vibrating reed 1 is dropped and receives an impact from the outside, the vibrating arms 6 and 7 are displaced, and the vibrating arm A large stress acts on the base regions 6 and 7, and the groove portions 4 and 5 described in FIGS. 8 and 9 provided in this region may be damaged if the wall portions on both sides sandwiching the groove bottom portion are thin. There is a problem that there is.
[0009]
INDUSTRIAL APPLICABILITY The present invention uses a piezoelectric vibrating piece that is excellent in impact resistance, can improve vibration efficiency, and can suppress a CI (crystal impedance) value, a piezoelectric device that accommodates the piezoelectric vibrating piece in a package, and a piezoelectric device An object is to provide a mobile phone and an electronic device.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, the entire body is formed of a piezoelectric material, and includes a base portion for fixing and a plurality of vibrating arms extending in parallel from the base portion. A piezoelectric vibrating piece in which an extending groove is formed, wherein the groove provided in each vibrating arm is extended in a length direction toward the base so as to reach the vibrating arm side end of the base. have been, the wall thickness of the wall portion which is formed in the groove bottom on both sides of the groove, the towards the region of the root portion is a base end portion of each of the vibration arms that is adapted gradually increases, the The wall thickness of the base region is set to be thicker than the wall thickness in other regions, and the end of the groove portion is in the region where the outer shape of each groove portion enters the base portion. It is oriented and gradually widens toward the end of the groove In so that, by the piezoelectric vibrating piece being formed is achieved.
According to the configuration of the first aspect of the invention, the groove portion has the wall thickness of the wall portion provided on both sides of the groove bottom portion corresponding to the region where the distortion increases when the plurality of vibrating arms of the piezoelectric vibrating piece flexurally vibrate. For this reason, not only during flexural vibration but also when an impact is applied from the outside, a region where stress is concentrated is structurally strengthened, so that impact resistance is improved. For this reason, even if each vibrating arm and the groove are lengthened so that the vibrating arm is greatly shaken during flexural vibration, there is no fear of breakage. Alternatively, in order to vibrate in the same manner as in the prior art, a small drive voltage is sufficient, so that a piezoelectric vibrating piece with a low CI value can be realized.
Thus, according to the present invention, it is possible to exert the effects of being excellent in impact resistance, improving the vibration efficiency, and suppressing the CI value.
Furthermore, since the thickness of the wall portion is increased particularly at the base portion which is the base end portion of each vibrating arm, the portion where stress is most concentrated has a particularly strong structure.
Moreover, the groove is extended until it reaches the base. This groove is a region where a drive electrode is formed, and a drive electrode can be formed in a base region where a drive electrode has not been conventionally formed. It is possible to efficiently supply energy for vibration to a region where the distortion is large.
Furthermore, the outer shape of each of the groove portions can be formed in the base region so that the vibration region can be formed corresponding to the strain distribution in the base portion by having the end portion facing inward. In addition, the outer shape of each groove is gradually widened toward the end of the groove, so that such a region can be used positively in response to a large distortion region spreading in a planar shape at the base. A place to be vibrated can be formed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show an embodiment of a piezoelectric device of the present invention. FIG. 1 is a schematic plan view thereof, and FIG. 2 is a schematic cross-sectional view taken along the line BB of FIG.
1 and 2, the piezoelectric device 30 shows an example in which a crystal resonator is configured. The piezoelectric device 30 houses a piezoelectric vibrating piece 32 in a package 36. FIG. The package 36 is formed, for example, by laminating a plurality of substrates formed by molding an aluminum oxide ceramic green sheet as an insulating material, and then sintering. Each of the plurality of substrates is formed with a predetermined hole on the inner side thereof, so that a predetermined internal space S2 is formed on the inner side when stacked.
This internal space S2 is a housing space for housing the piezoelectric vibrating piece.
That is, as shown in FIG. 2, in this embodiment, the package 36 is formed by, for example, stacking the first laminated substrate 52 and the second laminated substrate 53 from below.
[0018]
In the vicinity of the left end portion in the figure in the internal space S2 of the package 36, the first laminated substrate 52 that is exposed to the internal space S2 and constitutes the inner bottom portion is, for example, an electrode formed by nickel plating and gold plating on tungsten metallization Portions 31, 31 are provided.
The electrode portions 31 are connected to the outside to supply a driving voltage. Conductive adhesives 43, 43 are applied on the electrode portions 31, 31, and the base 51 of the piezoelectric vibrating piece 32 is placed on the conductive adhesives 43, 43. 43 are hardened. In addition, as the conductive adhesives 43 and 43, a synthetic resin agent as an adhesive component exhibiting a bonding force and containing conductive particles such as fine silver particles can be used. A system-based or polyimide-based conductive adhesive or the like can be used.
The base 51 may be formed with notches or recesses such as the notches 5a and 5b described in FIG.
[0019]
A lid body 39 is joined to the open upper end of the package 36 by using a brazing material 33 to be sealed. Preferably, the lid 39 is sealed and fixed to the package 36, and then, as shown in FIG. 2, the laser beam L2 is irradiated from the outside onto the metal coating portion (not shown) of the piezoelectric vibrating piece 32, and the mass In order to adjust the frequency by the reduction method, it is made of a material that transmits light, particularly, thin glass.
As a glass material suitable for the lid 39, for example, borosilicate glass is used, for example, as a thin glass manufactured by the downdraw method.
[0020]
The piezoelectric vibrating piece 32 is formed by etching a crystal. In the case of the present embodiment, the piezoelectric vibrating piece 32 is particularly enlarged and shown in FIG. It is made into a shape. 4 is a cross-sectional end view taken along the line CC of FIG. In FIG. 3, the piezoelectric vibrating piece 32 is formed by wet etching a crystal wafer cut from a single crystal of crystal so that the X axis is an electric axis, the Y ′ axis is a mechanical axis, and the Z ′ axis is an optical axis. Yes. The piezoelectric vibrating piece 32 includes a base portion 51 fixed to the package 36 side, and a pair of vibrating arms 34 and 35 extending in parallel in a bifurcated manner toward the upper side in the figure with the base portion 51 as a base end. A so-called tuning fork-type piezoelectric vibrating piece, which is entirely shaped like a tuning fork, is used.
[0021]
As shown in FIG. 3, grooves 56 and 57 extending in the length direction are provided on the front and back surfaces of the vibrating arms 34 and 35 of the piezoelectric vibrating piece 32, respectively.
The vibrating arm 34 is provided with grooves 56 and 56 on the front surface and the back surface, respectively, and the vibrating arm 35 is provided with grooves 57 and 57 on the front surface and the back surface, respectively. Yes. These grooves can be formed, for example, by etching the quartz wafer to form the outer shape of the piezoelectric vibrating piece 32 and then half-etching the vibrating arm portion.
[0022]
As shown in FIG. 4, the vibrating arm 34 is formed with a portion 21 that forms the bottom of the groove portion, and wall portions that stand on both sides of the portion 21. As shown in FIG. 3, the structure of the vibrating arm 34 is vertically symmetrical with respect to the center in the thickness direction. For this reason, with respect to the portion 21 located at the center in the thickness direction, the wall portions 22 and 22 are formed on the upper side, and the wall portions 22 and 22 are formed on the lower side as well. The vibrating arm 35 has the same structure as the vibrating arm 34, and the wall portions 23, 23 are formed on the upper side and the wall portions 23, 23 are also formed on the lower side with respect to the portion 21 located at the center in the thickness direction. .
[0023]
Further, in FIG. 3, extraction electrodes 58 and 59 are formed near both ends in the width direction of the base 51 of the piezoelectric vibrating piece 32. The respective extraction electrodes 58 and 59 are similarly formed on the back surface of the base 51 of the piezoelectric vibrating piece 32.
These lead electrodes 58 and 59 are portions connected to the package-side electrode portions 31 and 31 shown in FIG. 1 by the conductive adhesives 43 and 43 as described above. The extraction electrodes 58 and 59 are connected to excitation electrodes 63 and 64 (shown only in FIG. 4), which are driving electrodes provided in the grooves 56 and 57 of the vibrating arms 34 and 35, for example.
[0024]
That is, as shown in FIG. 4, electrodes are formed in the grooves 56 and 57 of the vibrating arms 34 and 35. Specifically, excitation electrodes 63 and 63 are formed in the grooves 56 and 56 of the vibrating arm 34, and excitation electrodes 64 and 64 that are paired with the excitation electrodes 64 and 64 are formed on both sides of the vibrating arm 34 (side surfaces). electrode). On the other hand, excitation electrodes 64, 64 are formed in the groove portions 57, 57 of the vibrating arm 35, and excitation electrodes 63, 63 are formed on both sides of the vibrating arm 35 (a side electrode). As a result, an electric field can be efficiently formed inside the piezoelectric material because the distance between the electrode formed in the groove and the pair of side electrodes is a short distance that separates the wall of the groove.
Here, the structures of these electrodes are the same on the front and back surfaces, ie, the upper surface and the lower surface in FIG. The upper surface excitation electrodes 63 and 64 in FIG. 4 are front surface electrodes, and the lower surface excitation electrodes 63 and 64 are rear surface electrodes.
[0025]
Next, the characteristic structure of the grooves 56 and 57 of this embodiment will be described in detail. FIG. 5 shows a simulation of the distribution state of a region where distortion occurs in the piezoelectric vibrating piece 32 when the vibrating arms 34 and 35 flexurally vibrate so that the tips 34a and 35a approach and separate from each other as indicated by arrows. The regions are shown in the order of greater distortion in the order of symbols a, b, and c. That is, the region a has the largest distortion, and the region c has the smallest distortion.
According to FIG. 5, with respect to the vibrating arms 34 and 35, the a region and the b region are spread over the range of L <b> 1 from the location of the root portion R <b> 1 toward the distal ends 34 a and 35 a. Further, in addition to the range of L1, the a region and the b region are also distributed at the end of the base 51 on the vibrating arm side. Including this range, the range of L2 is a region with large distortion.
[0026]
Therefore, as shown in FIG. 3, in this embodiment, the wall portions 22, 22, 23, 23 of the groove portions 56, 57 of the vibrating arms 34, 35 are made thicker than other portions. It is configured. In addition, preferably, the thickness of these wall portions is gradually increased toward the root portion R1 of the vibrating arms 34 and 35 so as to conform to the distribution mode of the strain distribution region of FIG. Has been.
[0027]
For this reason, not only when the vibrating arms 34 and 35 are flexibly vibrated, but also when an impact is applied from the outside, the region where the stress is concentrated is structurally strengthened, so that the impact resistance is improved. For this reason, even if each vibrating arm and the groove are lengthened so that the vibrating arm is greatly shaken during flexural vibration, there is no fear of breakage. Furthermore, for example, in order to vibrate in the same manner as in the prior art, a small driving voltage is sufficient, so that a piezoelectric vibrating piece with a low CI value can be realized.
In particular, in the base portion R1 which is the base end portion of each vibrating arm 34, 35, the thickness of the above-described wall portions 22, 22, 23, 23 is increased, so that a portion where stress is most concentrated has a particularly strong structure.
[0028]
Further, as shown in FIG. 3, the base portions are formed so that the groove portions 56 and 57 provided in the respective vibrating arms 34 and 35 are extended in the length direction toward the base portion 51 and include the range of L2 described above. It is extended to 51 vibrating arm side end portions (hereinafter referred to as “end region”). For this reason, since the drive electrode can be formed in the region of the base 51 where the drive electrode has not been formed conventionally, the region where distortion is increased while using the region that has not been used conventionally. It is possible to efficiently supply energy for vibration.
[0029]
The outer shapes of the grooves 56 and 57 are such that the ends 26 and 27 are inward in the region of the base 51.
That is, as shown in FIG. 5, in the end region of the base portion 51, a region having a large distortion is distributed in a curved line, and the end portion 26, 27 is formed inwardly. As a result, a region with a large distortion can be utilized as efficiently as possible.
Further, the outer shapes of the grooves 56 and 57 are gradually widened by the enlarged diameter portions 24 and 25 toward the ends 26 and 27 of the grooves. For this reason, in the edge part area | region of the base 51, the location which vibrates using such an area | region actively can be formed corresponding to the area | region where the distortion expand | swelled planarly.
[0030]
FIG. 6 shows an embodiment of the present invention in which when the piezoelectric device employing the above-described groove structure of the piezoelectric vibrating piece 32 is dropped from a position having a height of 1.5 m, the piezoelectric vibrating piece 32 at the time of collision with a floor or the like. It is a graph which shows the result of having measured the force concerning the base part of each vibrating arm.
As shown in the figure, the force applied to the joint portion is reduced by about 40% compared to the conventional piezoelectric device.
[0031]
FIG. 7 is a diagram illustrating a schematic configuration of a digital mobile phone device as an example of an electronic apparatus using the piezoelectric device according to the above-described embodiment of the present invention.
In the figure, a microphone 308 for receiving the voice of the sender and a speaker 309 for setting the received content as voice output are provided, and further, an integrated circuit or the like as a control unit connected to the modulation / demodulation unit of the transmission / reception signal. A controller (CPU) 301 is provided.
The controller 301 is an information input / output unit 302 including an LCD as an image display unit and operation keys for inputting information in addition to modulation and demodulation of transmission / reception signals, and a memory which is an information storage unit including a RAM, a ROM, etc. 303 is controlled. For this reason, the piezoelectric device 30 is attached to the controller 301, and the output frequency is used as a clock signal suitable for the control content by a predetermined frequency dividing circuit (not shown) built in the controller 301. Has been. The piezoelectric device 30 attached to the controller 301 may not be a single piezoelectric device 30 but may be an oscillator that combines the piezoelectric device 30 and a predetermined frequency dividing circuit.
[0032]
The controller 301 is further connected to a temperature compensated crystal oscillator (TCXO) 305, and the temperature compensated crystal oscillator 305 is connected to the transmission unit 307 and the reception unit 306. As a result, even if the basic clock from the controller 301 fluctuates when the environmental temperature changes, it is corrected by the temperature compensated crystal oscillator 305 and supplied to the transmission unit 307 and the reception unit 306.
In this way, by using the piezoelectric device 30 according to the above-described embodiment in an electronic device such as the digital mobile phone device 300, the CI mobile phone device 300 that can suppress the CI value and has high reliability is provided. Obtainable.
[0033]
The present invention is not limited to the above-described embodiment. Each configuration of each embodiment can be appropriately combined or omitted, and can be combined with other configurations not shown.
In addition, the present invention can be applied to all piezoelectric devices as long as the piezoelectric vibrating piece is accommodated in the package, regardless of the name of the crystal resonator, the crystal oscillator, or the like.
Further, in the above-described embodiment, a box-shaped material using a crystal material is used for the package. The present invention can be applied to any package or case with any case.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing an embodiment of a piezoelectric device of the present invention.
FIG. 2 is a schematic sectional view taken along line BB in FIG.
3 is an enlarged schematic plan view of the piezoelectric vibrating piece of FIG. 1. FIG.
4 is a cross-sectional end view taken along the line CC of FIG. 3;
5 is a diagram showing a distribution of strain regions in bending vibration of the piezoelectric vibrating piece in FIG. 1. FIG.
FIG. 6 is a graph comparing impact resistance of a conventional piezoelectric device and a piezoelectric device according to an embodiment of the present invention.
FIG. 7 is a diagram showing a schematic configuration of a digital mobile phone device as an example of an electronic apparatus using a piezoelectric device according to an embodiment of the present invention.
FIG. 8 is a schematic plan view showing a conventional piezoelectric device.
FIG. 9 is an end view taken along line AA in FIG. 8;
10 is a diagram showing a distribution of strain regions in flexural vibration of the piezoelectric vibrating piece in FIG. 8. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 30 ... Piezoelectric device, 32 ... Piezoelectric vibrating piece, 34, 35 ... Vibrating arm, 56, 57 ... Groove part, 63, 64 ... Excitation electrode (electrode for driving)

Claims (4)

A piezoelectric vibrating piece that is formed entirely of a piezoelectric material and includes a base for fixing and a plurality of vibrating arms extending in parallel from the base, and a groove extending in the length direction is formed in each vibrating arm. ,
The groove portion provided in each vibration arm is extended in the length direction toward the base portion so as to reach the vibration arm side end portion of the base portion, and is formed on both sides of the groove bottom portion of the groove portion. that the wall thickness of the wall portion, said at is the fact to increase gradually towards the region of the root portion is a base end portion of each of the vibration arms, in the wall thickness of the rest area of the region of the root portion It is designed to be thicker than the wall thickness,
In addition, the outer shape of each of the groove portions is formed so that the end portion of the groove portion is inward and gradually widens toward the end portion of the groove portion in the region entering the base portion. A piezoelectric vibrating piece. A piezoelectric device containing a piezoelectric vibrating piece in a case or package,
The piezoelectric vibrating piece is
A piezoelectric vibrating piece that is formed entirely of a piezoelectric material and includes a base for fixing and a plurality of vibrating arms extending in parallel from the base, and a groove extending in the length direction is formed in each vibrating arm. ,
The groove portion provided in each vibration arm is extended in the length direction toward the base portion so as to reach the vibration arm side end portion of the base portion, and is formed on both sides of the groove bottom portion of the groove portion. that the wall thickness of the wall portion, said at is the fact to increase gradually towards the region of the root portion is a base end portion of each of the vibration arms, in the wall thickness of the rest area of the region of the root portion It is designed to be thicker than the wall thickness,
In addition, the outer shape of each of the groove portions is formed so that the end portion of the groove portion is inward and gradually widens toward the end portion of the groove portion in the region entering the base portion. A piezoelectric device. A mobile phone device using a piezoelectric device containing a piezoelectric vibrating piece in a package,
The piezoelectric vibrating piece is
A piezoelectric vibrating piece that is formed entirely of a piezoelectric material and includes a base for fixing and a plurality of vibrating arms extending in parallel from the base, and a groove extending in the length direction is formed in each vibrating arm. ,
The groove portion provided in each vibration arm is extended in the length direction toward the base portion so as to reach the vibration arm side end portion of the base portion, and is formed on both sides of the groove bottom portion of the groove portion. that the wall thickness of the wall portion, said at is the fact to increase gradually towards the region of the root portion is a base end portion of each of the vibration arms, in the wall thickness of the rest area of the region of the root portion It is designed to be thicker than the wall thickness,
And, in the region where the outer shape of each groove portion enters the base portion, the piezoelectric device is formed so that the end portion of the groove portion is inward and gradually becomes wider toward the end portion of the groove portion. A cellular phone device characterized in that a clock signal for control is obtained. An electronic device using a piezoelectric device containing a piezoelectric vibrating piece in a package,
The piezoelectric vibrating piece is
A piezoelectric vibrating piece that is formed entirely of a piezoelectric material and includes a base for fixing and a plurality of vibrating arms extending in parallel from the base, and a groove extending in the length direction is formed in each vibrating arm. ,
The groove portion provided in each vibration arm is extended in the length direction toward the base portion so as to reach the vibration arm side end portion of the base portion, and is formed on both sides of the groove bottom portion of the groove portion. that the wall thickness of the wall portion, said at is the fact to increase gradually towards the region of the root portion is a base end portion of each of the vibration arms, in the wall thickness of the rest area of the region of the root portion It is designed to be thicker than the wall thickness,
And, in the region where the outer shape of each groove portion enters the base portion, the piezoelectric device is formed so that the end portion of the groove portion is inward and gradually becomes wider toward the end portion of the groove portion. An electronic device characterized in that a clock signal for control is obtained.

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