JPH1019575A - Piezoelectric vibrating body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrating body which can restrict warping of a vibrating body resulting from the difference of thermal expansion coefficients, effectively suppress spurious vibrations generated in a vibrating part on the driving side and improve output sensitivity. SOLUTION: A vibrating part 1A on the driving side having driving vibrating branches 3, 4 and a vibrating part 1B on the detecting side having detecting vibrating branches 5, 6 and an input.output holding branch 7 are formed integrally on the confronting faces of a coupling base part 2 respectively. Driving electrodes 31, 32, 41, 42 are respectively formed at the driving vibrating branches 3, 4 of the vibrating part 1A so as to generate a predetermined vibration of the tuning fork. Moreover, detecting electrodes 51, 52, 61, 62 are formed at the detecting vibrating branches 5, 6 of the vibrating part 1B to detect the vibration. A driving input electrode 71 and detecting output electrodes 73, 74 are also formed at the holding branch 7 of the vibrating part 1B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator, and more particularly, to a piezoelectric vibrator used for an angular velocity sensor for camera shake correction, car navigation of a car, attitude control of a moving body, and the like. .

[0002]

2. Description of the Related Art Conventionally, various angular velocity sensors have been proposed for use in camera shake correction, car navigation of vehicles, and attitude control of moving bodies.

Conventionally, as angular velocity sensors, those disclosed in US Pat. No. 4,524,619 and Japanese Patent Application Laid-Open No. 3-291517 have been known.
There has been proposed an angular velocity sensor having a piezoelectric vibrator using a tuning fork vibration mode in which a driving-side tuning-fork-shaped vibrating portion and a tuning-fork-shaped detecting-side vibrating portion are integrated, and a piezoelectric substrate has an H-shape as a whole. .

Further, the present applicant has disclosed a piezoelectric vibrating body which achieves mechanical holding of the piezoelectric vibrating body and electrical connection with an external processing circuit by an intermediate holding branch which is a vibration branch independent of each vibration. It was proposed (see FIGS. 7 and 8).

As shown in FIGS. 7 and 8, the piezoelectric vibrating body 1 includes a driving-side vibrating section 1A, a detecting-side vibrating section 1B, and a coupling base 2. As the piezoelectric vibrator 1, for example, a quartz substrate cut in a predetermined manner according to the crystal polarization axis of quartz can be exemplified.

A driving-side vibrating section 1A is provided on one side of a pair of opposed end faces of the coupling substrate 2, and a detecting-side vibrating section 1 is provided on the other side.
B are integrally arranged.

The driving-side vibrating portion 1A mainly includes two driving vibrating branches 3 and 4, an input holding branch 5, and two reinforcing branches 93 and 94, and the driving vibrating branches 3 and 4, the input holding branch 5, and the reinforcing branch. 93,
Reference numeral 94 extends from the coupling base 2 in the same direction.

The detection-side vibrating section 1B mainly comprises two detection vibrating branches 6, 7, an output holding branch 8, two reinforcing branches 96,
97, the detection oscillating branches 6, 7, the output holding branch 8, and the reinforcing branches 96, 97 extend in the opposite direction to the driving oscillating branches 3, 4, the input holding branch 5, and the reinforcing branches 93, 94. I have.

As shown in FIG. 9, a piezoelectric vibrating body having such a structure is provided on a part of a case for accommodating the piezoelectric vibrating body 1, for example, on a base 10 at a predetermined interval.
1, the input holding branch 5 and the output holding branch 8 are respectively arranged on the two conductive spacer members 11, and these are joined by a conductive adhesive. As a result, mechanical holding of the piezoelectric vibrating body 1 on the base 10 is achieved, and connection between predetermined circuit wiring on the surface of the base 10 and the drive input electrodes 52 and the detection output electrodes 82 is achieved.
The connection with the drive input electrode 51 and the detection output electrode 81 on one main surface side of the piezoelectric vibrating body 1 is performed by, for example, a wire bonding thin wire.

In such a piezoelectric vibrator, when a predetermined electric signal is applied to the drive input electrode of the drive side vibrating portion, a tuning fork vibration having a predetermined resonance frequency is generated. The predetermined electrical signal is given from an external circuit via, for example, a wiring pattern of the base and a drive input electrode of the drive-side vibration unit.

When a rotary motion (angular velocity) is applied to the piezoelectric vibrating body in a state where the driving vibration branch of the driving-side vibrating part is performing tuning fork vibration, Coriolis force acts on the tuning fork vibration, and the detection side is driven. A vibration different from the tuning fork vibration, for example, a fluttering vibration or a bending vibration is generated in the vibrating portion.

For example, in the fluttering vibration, two driving vibration branches vibrate alternately in the direction perpendicular to the plane of the piezoelectric substrate with an amplitude proportional to the rotational angular velocity. The fluttering leg vibration is transmitted to the detecting vibrating branch of the detecting side vibrating portion, and the detecting vibrating branch performs fluttering leg vibration. By converting the fluttering vibration into an electric signal by the detection electrode, a detection signal corresponding to a predetermined angular velocity can be extracted from the detection output electrode.

[0013]

However, in the above-described piezoelectric vibrating body, as shown in FIG.
Is mechanically joined to the base 10 at the two input holding branches 5 and the output holding branches 8 by using two-point support structures. The drive-side vibration unit 1A and the detection-side vibration unit Regarding the relationship 1B, the control of the resonance frequency is important, but in practice, a fundamental tuning fork vibration and a spurious vibration are also generated between the driving vibration branches 3 and 4 and the reinforcing branches 93 and 94 constituting the driving-side vibration section 1A. Would. This spurious vibration occurs near the fundamental tuning fork vibration, and it is difficult to make correspondence between the basic vibration and the spurious vibration, and it is very difficult to control the spurious vibration.

In such a two-point support structure, the difference in the coefficient of thermal expansion of the conductive spacer member 11 for joining the piezoelectric vibrator 1 and the base 10 or the piezoelectric vibrator 1 and the base Due to the difference in the coefficient of thermal expansion of 10, a stress is generated in the input holding branch 5 and the output holding branch 8, causing the piezoelectric vibrating body 1 to warp and reduce reliability.

Further, the temperature characteristic is degraded due to the warpage.

The present invention has been proposed in consideration of the above-mentioned problems, and has as its object to suppress warpage of a piezoelectric vibrator caused by a difference in coefficient of thermal expansion and to generate a piezoelectric vibrator in a driving-side vibrating section. An object of the present invention is to provide a piezoelectric vibrating body capable of effectively suppressing spurious vibrations and improving output sensitivity.

[0017]

According to the present invention, there is provided a piezoelectric vibrating body comprising:
A driving-side vibrating section having a driving vibrating branch and a detecting-side vibrating section having a detecting vibrating branch and an input / output holding branch are integrally formed on opposing surfaces of a coupling base, respectively, and the driving of the driving-side vibrating section is performed. A drive electrode for generating a predetermined tuning fork vibration is formed on the vibrating branch, and a detecting electrode for detecting vibration is formed on a detecting vibrating branch of the detecting vibrating section. A drive input electrode and a detection output electrode are formed on an input / output holding branch.

[0018]

According to the present invention, the input / output holding branch is formed on the detection-side vibrating section, and only the driving vibration branch is formed on the driving-side vibrating section. Is the vibration of only the driving vibration branch, and the spurious vibration caused by vibration other than the driving vibration branch such as the reinforcing branch is suppressed. In addition, since the detection-side vibrating portion is also firmly fixed by the input / output holding branches, the mechanical resonance sharpness Q of the detection-side vibrating portion is improved.

Further, since the input / output holding branch is formed only on the detection-side vibrating portion, the input / output holding branch is fixed to the base with solder or the like, so that the difference in the thermal expansion coefficient between the piezoelectric vibrating body and the base is caused. The generated warpage of the piezoelectric vibrator can be suppressed,
Reliability and temperature characteristics are improved.

[0020]

1 is an external perspective view of the front surface side of a piezoelectric vibrator according to the present invention, and FIG. 2 is a perspective view of the rear surface side thereof. FIG. 3 is a schematic diagram illustrating an electrical connection state of a drive-side vibration unit of the piezoelectric vibrator, and FIG. 4 is a schematic diagram illustrating an electrical connection state of a detection-side vibration unit of the piezoelectric vibrator. 7 and 8 will be described using the same reference numerals.

FIGS. 1 and 2 show a piezoelectric vibrating body 1 according to the present invention.
As shown in (1), the driving-side vibrating portion 1A, the detecting-side vibrating portion 1B, and the coupling base 2 are configured.

The piezoelectric vibrator 1 may be, for example, a quartz substrate cut in a predetermined manner, for example, a Z-cut according to the crystal polarization axis of quartz. In addition, a piezoelectric ceramic substrate polarized in a predetermined direction can be exemplified.

A drive-side vibrating portion 1A is formed integrally on one side of a pair of opposed end surfaces (hereinafter referred to as longitudinal end surfaces) of the coupling base 2, and a detecting-side vibrating portion 1B is formed integrally on the other side. ing.

The driving-side vibrating portion 1A mainly comprises two driving vibrating branches 3 and 4, and the driving vibrating branches 3 and 4 extend from the coupling base 2 in the same direction. The detection-side vibration unit 1B mainly includes two detection vibration branches 5 and 6, and an input / output holding branch 7,
The input / output holding branch 7 is formed so as to be sandwiched between the detection vibration branches 5 and 6, and the vibration branches 5 and 6 and the input / output holding branch 7 extend from the vibration branches 3 and 4 of the driving-side vibration unit 1 </ b> A. It extends in the opposite direction.

Here, the lengths and widths of the vibrating arms 3, 4 and 5, 6 are different so that the two vibrating parts 1A, 1B have different natural resonance frequencies.

The vibrating branch 3, which becomes the driving side vibrating portion 1A,
4. Oscillating branches 5 and 6 serving as detection-side vibrating sections, input / output holding branches 7
Various predetermined electrodes and conductive films are formed on the main surface and / or the side surface of the coupling base 2, respectively. The predetermined electrode and the conductor film are formed by a thin film technique such as vapor deposition or sputtering of chromium, Au, or the like.

That is, first, in the driving-side vibrating section 1A,
Driving electrodes 31 to 34, 41 to 4 for converting a predetermined driving signal into vibration are provided on each of the four surfaces of the two driving vibration branches 3, 4.
4 are formed. Drive input electrodes 71 and 72 are extended to both main surfaces of the input / output holding branch 7 via the coupling base 2.

Next, in the detecting side vibrating portion 1B, the two detecting vibrating branches 5 and 6 have detecting electrodes 51 to 54 and 61 for converting a fluttering vibration corresponding to the angular velocity into a detecting signal.
To 64 are formed. Specifically, on one main surface of the detection vibration branch 5, two detection electrodes 51 and 52 are formed in parallel with a predetermined interval in the length direction of the detection vibration branch 5, and the detection vibration branch 6 The two detection electrodes 6 on one main surface
1 and 62 are formed side by side in parallel in the longitudinal direction of the vibrating branch 6 at a predetermined interval.
Are also provided on the other main surface of the
Are formed in parallel. Also, the input / output holding branch 7
The drive input electrodes 71 and 72 extended from the drive-side vibrating section 1A via the coupling base 2 and the detection vibrating branches 5,
6, the detection output electrodes 73, 74, 75, 76 extended from
Are formed.

That is, the detection electrodes 51 of the detection vibration branches 5 and 6
Reference numerals 52, 61, and 62 denote drive input electrodes 7 of the input / output holding branches 7.
1. Formed on the same main surface as the detection output electrodes 73 and 74, and the detection electrodes 53, 54, 63 and 64 are formed on the same main surface as the drive input electrode 72 and the detection output electrodes 75 and 76 of the input / output holding branch 7. ing.

The driving vibration branch 3 of the driving vibration section 1A,
4 and the input / output holding branch 7
In order to connect the drive input electrode 71, the leading conductor film 2 is connected to the tip or base of the coupling base 2 and the drive vibration branches 3 and 4.
1, 35, 46 are formed, and in order to connect the drive input electrode 72 and the drive electrodes 32, 34, 41, 43,
At the tip or base of the coupling base 2, the driving vibration branches 3, 4,
The lead conductor films 22, 36, and 45 are formed.

The input / output holding branch 7 of the detection-side vibrating section 1B
The detection output electrodes 73 and 75 are connected by a routing conductor 77, and the coupling base 2 and the vibration branch are connected to connect the detection output electrodes 73 and 75 and the detection electrodes 51, 54, 61 and 64 of the vibration branches 5 and 6. Leading conductor films 24 are provided at the tips of 3 and 4.
a, 24b, 25a, 25b, and 55 are formed. The detection output electrodes 74 and 76 are connected by a routing conductor 78, and the detection electrodes 52 and 53 of the vibration branches 5 and 6 are connected to the detection output electrodes 74 and 76.
In order to connect with 62, 63, the connecting base 2, the vibrating branch 3,
4, the leading conductor films 23a, 23b, 26
a, 26b, 65 are formed.

As a result, the drive electrodes 31 to 34, 41 to 44 and the drive input electrodes 71, 72 of the drive side vibrating section 1A are connected as shown in FIG. 3, and the detection electrodes 51 to 54 of the detection side vibrator 1B are connected. , 61 to 64, the detection input electrode 73,
75, 74, and 76 are connected as shown in FIG.

In the piezoelectric vibrating body 1 having the above-described structure, by applying a driving AC voltage between the driving input electrodes 71 and 72, the driving-side vibrating portion 1A is supplied to the driving-side vibrating portion 1A again at the next moment as shown by the solid arrow in FIG. A tuning fork vibration mode occurs as indicated by a dashed arrow in the figure. Note that this tuning fork vibration is not transmitted to the detection-side vibration unit 1B having a different natural resonance frequency.

In this state, when a rotational angular velocity is applied to the entire piezoelectric vibrating body 1, Coriolis force acts, for example, on the detecting-side vibrating portion 1B shown in FIG. At that moment, a fluttering foot vibration is generated as indicated by a broken arrow in the figure.

As described above, the detection-side vibrating section 1B
Between the detection electrodes 51 and 52, between 53 and 54, 6
A predetermined electric field is generated between 1 and 62 and between 63 and 64 due to the relationship between the fluttering vibration and the polarization direction (orientation) of the piezoelectric substrate, and a potential difference is generated.

Then, this potential is extracted (detected signal) from the detection output electrodes 73, 75, 74, 76 formed on the input / output holding branch 7. Detection electrodes 73, 75,
The detection signals obtained from 74 and 76 are processed by an external circuit including an amplifier (op-amp).

In the piezoelectric vibrating body 1 having such a structure, as shown in FIG. 5, for example, a plurality of input / output holding branches 7 are provided on a part of a case for accommodating the piezoelectric vibrating body 1, for example, on a base 10. Is fixed with a conductive adhesive such as solder through the conductive spacer 11 and each input and output electrode is sealed with a can package or the like via a lead. As a result, the piezoelectric vibrator 1 is mechanically held, and is connected to an external circuit by a lead extending from the can package.

As shown in FIG. 6, for example, as shown in FIG. 6, the tip of the input / output holding branch 7 has a disc-shaped base 1.
0 is fixed with a conductive adhesive such as solder on the detection electrode 7.
In some cases, 3, 75, 74, and 76 may be electrically connected to wiring formed on the base 10 and fixed to the base 10. In this structure, the detection electrode can be connected together with the fixing of the piezoelectric vibrator 1 to the base 10. The piezoelectric vibrator 1 fixed to the base 10 is accommodated in a cylindrical container.

The wiring structure of the detection-side vibrating portion 1B, the structure of the detection electrode, and the structure of the lead conductor can be arbitrarily changed in consideration of the polarization of the piezoelectric substrate (in the crystal axis direction), the position of the output electrode, and the like. it can.

In the piezoelectric vibrating body of the present invention, a holding branch for holding and fixing the piezoelectric vibrating body, and an input / output holding branch in which an input / output electrode is formed by one holding branch are formed in the detection-side vibrating portion. Since only the driving vibration branch is formed in the vibrating portion, the vibration generated in the driving side vibration portion is only the vibration of the driving vibration branch, and the spurious vibration caused by the vibration other than the driving vibration branch such as the conventional reinforcing branch. Vibration can be suppressed. Also,
The detection-side vibrating part is also firmly fixed by the input / output holding branches, so that the decrease in the Q value due to the torsional vibration of the detection-side vibrating part is reduced, and the mechanical resonance sharpness Q of the detection-side vibrating part is improved. Gyro sensitivity is improved.

Further, since the input / output holding branch is formed only on the detection side vibrating portion, the input / output holding branch is fixed to the base with a plurality of conductive spacers, so that the coefficient of thermal expansion between the piezoelectric vibrator and the base is increased. The warpage of the piezoelectric vibrator caused by the difference can be suppressed, and the reliability and the temperature characteristics can be improved. In particular, in the case of the structure shown in FIG. 6, warpage of the piezoelectric vibrator can be prevented. Therefore, the characteristics (sensitivity) become stable over a wide temperature range.

Further, since the input / output holding branches are formed on the detection-side vibrating portion, the pitch between the driving-side branches can be freely changed, and the size and shape of the piezoelectric vibrator can be reduced. The difference between the natural frequencies of the drive-side vibrator and the drive-side vibrator can be set freely.

[0043]

According to the piezoelectric vibrating body of the present invention, warpage of the piezoelectric vibrating body caused by a difference in the coefficient of thermal expansion between the base and the piezoelectric vibrating body can be suppressed by a plurality of supports such as two-point support, and the reliability can be improved. Characteristics and temperature characteristics can be improved, and the drive side vibrating part becomes vibration of only the drive vibration branch, other spurious vibration generated by the reinforcement branch etc. can be suppressed, and the input / output holding branch on the detection vibration side is firmly fixed By doing
Output sensitivity can be improved.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a front surface side of a piezoelectric vibrating body of the present invention.

FIG. 2 is an external perspective view of the back surface side of the piezoelectric vibrating body of the present invention.

FIG. 3 is a schematic diagram illustrating an electrical connection state of a driving-side vibrating portion that forms a piezoelectric vibrator.

FIG. 4 is a schematic diagram illustrating an electrical connection state of a detection-side vibrating portion constituting the piezoelectric vibrator.

FIG. 5 is an explanatory view showing a state in which input / output holding branches of the piezoelectric vibrator are fixed to a base via conductive spacers.

FIG. 6 is an explanatory diagram showing a state in which the tip of an input / output holding branch of a piezoelectric vibrator is fixed to a base by soldering.

FIG. 7 is an external perspective view of a front surface side of a conventional piezoelectric vibrator.

FIG. 8 is an external perspective view of the back side of a conventional piezoelectric vibrator.

FIG. 9 is a sectional view taken along line XX of FIG. 8;

[Explanation of symbols]

 1 ... Piezoelectric vibrator 1A ... Driving side vibrating part 1B ... Detecting side vibrating part 2 ... Coupling Base part 3, 4,..., Drive vibration branch of drive side vibration part 5, 6,..., Detection vibration branch of detection side vibration part 7,. Branches 31-34, 41-44 ... drive electrodes 51-54, 61-64 ... detection electrodes 73, 74, 75, 76 ... detection output electrodes 71, 72 ... .... Drive input electrodes

Claims (1)

[Claims] A drive-side vibrating section having a drive-vibration branch and a detection-side vibrator having a detection-vibration branch and an input / output holding branch are integrally formed on opposing surfaces of a coupling base, respectively. A drive electrode for generating a predetermined tuning fork vibration is formed on a drive vibration branch of the side vibrating section, and a detection electrode for detecting vibration is formed on a detection vibration branch of the detection side vibrating section, and A piezoelectric vibrator, wherein a drive input electrode and a detection output electrode are formed on an input / output holding branch of a detection-side vibrator.