JP3350382B2 - Piezoelectric vibrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator used for an angular velocity sensor.

[0002]

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

The applicant of the present invention has disclosed a drive-side vibrating section comprising two drive-oscillating branches on which drive electrodes are formed, one input-side intermediate holding branch on which drive-input electrodes are formed, and two drive-side vibrating sections on which detection electrodes are formed. A piezoelectric vibrating body in which a detecting vibrating portion including a detecting vibrating branch and one output side intermediate holding branch on which a detection output electrode is formed are integrally disposed on a pair of opposed end faces of the central coupling base 2, respectively; Suggested.

[0004] Such a piezoelectric vibrator is used by being mounted on a base to facilitate mounting when actually mounting.

The base is formed on its surface with a wiring pattern for electrically connecting and mechanically connecting the drive input electrode and the detection output electrode formed on the input / output intermediate holding branch. I was In addition, on the surface of the base, for example, a portion for achieving the above-mentioned electrical connection, at least a projection portion, for example, a conductive member, for securing a vibrable space between the driving vibration branch, the detection vibration branch and the base. A sex spacer was interposed.

That is, in the above-mentioned piezoelectric vibrating body, the piezoelectric substrate is mounted on the base by two-point support at the center in the width direction and near both ends in the longitudinal direction. That is, it is held using the input side middle holding branch and the output side middle holding branch.

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

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

For example, in the fluttering vibration, two driving-side vibrating branches vibrate alternately in a direction perpendicular to the plane of the piezoelectric substrate with an amplitude proportional to the rotational angular velocity.

This fluttering leg vibration is transmitted to the detecting vibrating branch of the detecting vibrating section, 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.

Conventionally, the intermediate holding branch for input / output has a reduced width dimension, the rigidity of the torsion of the intermediate holding branch for input / output has been reduced, and the dimension in the width direction of the intermediate coupling base has been increased. The rigidity of the joint base was improved.

This is because the input and output side intermediate holding branches are fixed to the base at both ends at two points, so that a torsional vibration is generated at the joint with the base and the mechanical resonance sharpness (Q
Value) to prevent the output sensitivity from lowering.

In order to control the fluttering vibration of the detecting vibrating section so as not to directly propagate and influence the fundamental tuning fork vibration of the driving side vibrating section, the vibration of each vibrating section (basic tuning fork vibration, It is important to set the natural resonance frequency of the foot vibration. For example, the frequency difference between the natural resonance frequencies of both vibrating parts △
f is set to 200 to 300 Hz, for example, 250 Hz.

In order to make such a frequency difference a predetermined value, the natural resonance frequency of each vibrating section may be adjusted.
More specifically, the end surface of the tip of the vibrating branch of one vibrating portion is polished and removed to substantially reduce the mass of the vibrating branch. The control of the natural resonance frequency is only one adjustment to increase the frequency.For example, if the frequency adjustment is performed only for the drive vibration unit that sets the high natural resonance frequency, the frequency difference can be widened. Alternatively, if the frequency adjustment is performed only for the detection vibrating part for which the natural resonance frequency is set low, the frequency difference can be reduced.

[0015]

However, in the above-described piezoelectric vibrator, the mechanical connection between the piezoelectric vibrating element and the base is performed by a two-point support structure in which the two intermediate holding branches are provided at the distal ends. Basically, the intermediate holding branches are twisted, and there is a limit to strength and a structure such as electrode wiring even if the width of the intermediate branches is reduced in size, so that a decrease in the Q value is inevitable.

In the relationship between the driving-side vibrating section and the detecting-side vibrating section having the above-described structure, although the above-described control of the resonance frequency is important, interference between the driving vibration branch and the detection vibration branch actually occurs, and the fundamental tuning fork is generated. Spurious vibration other than vibration occurs. This spurious vibration occurs near the fundamental tuning fork vibration,
It was difficult to cope with the basic vibration and the spurious vibration, and it was very difficult to control the spurious vibration.

Further, in such a two-point support structure, stress is generated in the intermediate holding branch portion due to the difference in the coefficient of thermal expansion of the conductive spacer portion for joining the piezoelectric vibrator and the base portion, and the piezoelectric vibration It causes body warpage and lowers reliability. In addition, the warpage lowers the temperature characteristics.

The present invention has been proposed in view of the above-mentioned problems, and has as its object to suppress warpage of a vibrating body due to a difference in coefficient of thermal expansion, and to reduce spurious noise generated in a driving vibrating section. An object of the present invention is to provide a piezoelectric vibrating body that can effectively suppress vibration and improve output sensitivity.

[0019]

According to the present invention, a driving vibration portion comprising an even number of driving vibration branches on which driving electrodes are formed is provided on one opposing side surface of a rectangular coupling base, and on the other side surface,
In a piezoelectric vibrating body in which a detection vibrating portion including an even number of detection side vibration branches on which detection electrodes are formed is disposed, a holding branch is disposed so as to straddle between the even number of detection side vibration branches, and The piezoelectric vibrator has a branch formed with a drive input electrode connected to the drive electrode and a detection output electrode connected to the detection electrode.

The holding branch straddles a position that is a node portion of the predetermined vibration of the vibration branch on the detection side.

[0021]

According to the present invention, the holding branch is formed on the detection vibrating portion, and the driving vibrating portion is constituted only by the driving vibrating branch on which the driving electrode is formed. The holding branches are formed between the detection vibration branches so as to be orthogonal to the longitudinal direction of the detection vibration branches.

Thus, the predetermined vibration generated in the drive vibration portion is only in the vicinity of the connection between the drive vibration branch and the drive branch of the coupling base, and there is nothing near the coupling base sandwiched between the drive vibration branches. Therefore, spurious vibration that disturbs the predetermined vibration can be effectively suppressed.

Further, by forming the holding branches only on the detecting vibrating portion, for example, when the supporting members are supported at two points or at a plurality of supporting points, they are generated due to a difference in thermal expansion coefficient between the piezoelectric vibrating body and the adhesive. Warpage can be suppressed, and reliability and temperature characteristics are improved.

Further, the holding branch can be firmly fixed without hindering the detected vibration by the holding branch arranged at the node of the predetermined detected vibration generated in the detected vibration branch, and the mechanical resonance on the detected vibration side is achieved. The sharpness Q is improved.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is an external perspective view of the front side of the piezoelectric vibrating body of the present invention, and FIG. 2 is a perspective view of the rear 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 vibration unit of the piezoelectric vibrator. FIG. 5 is a schematic view showing a structure for holding the piezoelectric vibrator.

The piezoelectric vibrating body 1 of the present invention has a driving vibrating section 1A.
And a detection vibration unit 1B and a coupling base 2.

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 the quartz. In addition, a piezoelectric ceramic substrate polarized in a predetermined direction can be exemplified.

On one side of a pair of opposing side surfaces of the coupling base 2, a drive vibration section 1A is integrally disposed, and on the other side, a detection vibration section 1B is integrally disposed.

The driving vibration section 1A mainly comprises two driving vibration branches 3, 4, and the driving vibration branches 3, 4 extend in the same direction.

The detection vibration section 1B mainly comprises two detection vibration branches 5, 6, and a holding branch 7, and the two detection vibration branches 5,
6, extends in the direction opposite to the direction in which the vibrating branches 3 and 4 of the vibrating portion 1A extend. The holding branch 7 is disposed between the detection vibration branches 5 and 6 so as to be orthogonal to the detection vibration branches 5 and 6, and is fixed to the base through the lower surface at the center of the holding branch 7.

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

The holding branch 7 is arranged at a position that becomes a node of the detection vibration generated in the detection electrode, and the length of the vibration branch or the holding branch is adjusted so that the center of the holding branch 7 is the center of gravity of the entire piezoelectric vibrating body 1. The width can be designed.

The vibrating branch 3, which becomes the driving vibrating section 1A,
4. Various predetermined electrodes and conductive films are formed on the main surface and / or side surface of the vibration branches 5 and 6 serving as the detection vibration unit, the holding branch 7 and the coupling base 2, respectively. In addition, this predetermined electrode and conductor film are:
For example, it is formed by a thin film technique such as vapor deposition of chromium, Au, or the like, or sputtering.

First, in the driving vibration section 1A, driving electrodes 31 to 34, 41 to 44 for converting a predetermined driving signal into vibration are formed on each of four surfaces of the two vibration branches 3, 4. Drive input electrodes 71 and 72 are extended to both main surfaces of the holding branch 7 via wire bondings 71a and 72a.

Next, in the detecting vibrating section 1B, the two vibrating branches 5 and 6 have detecting electrodes 51 to 54 and 61 to 64 for converting a fluttering vibration or the like corresponding to the angular velocity into a detection signal.
Are formed. More specifically, two detection electrodes 51 and 52 are formed on one main surface of the vibrating branch 5 in parallel with a predetermined interval in the longitudinal direction of the vibrating branch 5. On the surface, two detection electrodes 61 and 62 are formed side by side in parallel with a predetermined interval in the longitudinal direction of the vibration branch 6, and similarly, two detection electrodes 61 and 62 are also formed on the other main surface of the vibration branch 5 and 6. The detection electrodes 53, 54 and 63, 64 are formed side by side in parallel. In addition, both main surfaces of the holding branch 7 are provided with a driving vibration unit 1A.
And drive input electrodes 71 and 72 extended from the detection vibration branches 5 and 6 via wire bonding 71a and 72a, and detection output electrodes 73 to 78 extended from the detection vibration branches 5 and 6.

For example, on the front side shown in FIG.
Detection electrodes 51, 52, 61, 62 on detection vibration branches 5, 6
Drive input electrode 71 and detection output electrode 7
3 and 74 are formed, and on the back side appearing in FIG.
Detection electrodes 53, 54, 63, 64 on detection vibration branches 5, 6
Are provided on the holding branch 7 by the drive input electrode 72 and the detection output electrode 7.
5, 76 are formed. The detection output electrode 77 is formed on the side surface of the holding branch 7 to connect the detection output electrodes 73 and 75 of the same potential, and the detection output electrode 78 is connected to the detection output electrodes 74 and 76 of the same potential. ing.

The driving vibration branches 3, 4 of the driving vibration section 1A
In order to connect the drive electrodes 31, 33, 42, 44 of the holding branch 7 and the drive input electrodes 71 of the holding branch 7, the conductive films 21, 35 are routed to the wire bonding 71 a and the tip or base of the coupling base 2, the vibrating branches 3, 4. , 36 are formed,
In order to connect the drive electrodes 32, 34, 41, 43 to the drive input electrodes 72, the conductor films 22, 45, 46 are formed around the wire bonding 72 a and the tip or base of the coupling base 2, the vibrating branches 3, 4. ing.

The detection electrode 52 on one main surface of the detection vibrating section 1B is connected to the detection output electrode 73 via the routing conductor 23a on the holding branch 7, and the detection electrode 6 on the other main surface.
Reference numeral 4 is connected to the detection output electrode 76 via the routing conductor 23b on the holding branch 7.

Further, the detection vibration branch 5 of the detection vibration unit 1B,
6, the detection electrodes 51 to 54 and 61 to 64
Leading conductor film 24 at the tip or base of vibrating branch 5, 6
29 are formed. For example, the detection electrodes 52 connected to the detection output electrodes 73 are the routing conductors 25, 27, 29.
Are connected to the detection electrodes 53, 62 and 63, and the detection electrode 64 connected to the detection output electrode 76 is connected to the lead conductor 2
4, 26, 28 are connected to detection electrodes 51, 54, 61.

As a result, the drive electrode 3 of the drive vibration section 1A
3 to 41, 41 to 44 and the drive input electrodes 71, 72 are connected as shown in FIG. 3, and the detection electrodes 51 to 54, 61 to 64 of the detection vibrator 1B, and the detection input electrodes 73 formed on both main surfaces. , 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 vibrating section 1A is supplied to the driving vibrating section 1A as indicated by the solid arrow in FIG. A tuning fork vibration mode is generated as indicated by the middle dotted arrow. Note that this tuning fork vibration is not transmitted to the detection 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 vibrating portion 1B shown in FIG. At that moment, a fluttering foot vibration is generated as indicated by a dotted arrow in the figure.

Further, as described above, between the detection electrodes 51 and 52, between 53 and 54, and between the detection electrodes 51 and 52, which are juxtaposed on the main surfaces of the vibrating branches 5 and 6 of the detection vibrating section 1B so as to face each other. 6
2 and between 63 and 64, a predetermined electric field is generated due to the relationship between the fluttering vibration and the polarization direction (orientation) of the piezoelectric substrate,
A potential difference occurs.

This potential is applied to the detection output electrodes 73 (75, 77) and 74 (76, 78) formed on the holding branches.
(Detection signal).

The detection signals obtained from the detection electrodes 73 and 74 are processed by an external circuit including an amplifier (op-amp).

As shown in FIG. 5, the piezoelectric vibrating body 1 having such a structure has a spacer member 1 made of a conductive adhesive formed on a part of a case for accommodating the piezoelectric vibrating body 1, for example, a base 10.
1. That is, the mechanical holding of the piezoelectric vibrator 1 is supported at one point of the holding branch 7.

As described above, according to the present invention, the piezoelectric vibrator 1
Is formed on the side of the detection vibrating portion 1 </ b> B, and does not extend from the side surface of the coupling base 2.

As a result, since the tuning fork signal from the driving vibration unit 1A does not transmit to the detection vibration unit 1B via the coupling base 2, unnecessary vibration does not occur for predetermined vibration such as spurious vibration. .

Further, the holding branch 7 has two detection vibration branches 5 and 6.
Because it is located between the positions corresponding to the nodes of the detection vibration of
There is no adverse effect on the detected vibration.

Further, since the holding branch 7 can support the base 10 at a single point, the difference in the thermal expansion coefficient between the base and the piezoelectric vibrating body due to the two-point support as in the prior art. The generated warpage of the piezoelectric vibrator can be suppressed, and the reliability and the temperature characteristics are improved.

The driving vibration section 1A includes driving vibration branches 3, 4
Only spur vibration, other spurious vibrations generated by the reinforcement branch, etc. can be suppressed, and the holding branch on the detection vibration side can be firmly fixed so as not to hinder the detection vibration, thereby improving output sensitivity. Can be.

In the embodiment described above, the driving vibration branches 3 and 4 are
And the number of the detection vibration branches 5 and 6 is two.
Oscillating branches may be formed in the book.

[0054]

According to the present invention, since the input holding branch is disposed so as to straddle the detection vibration branch on the detection vibration side and is held at this portion, vibration caused by a difference in thermal expansion coefficient is obtained. It is to control body warpage.

Further, from the driving vibration section to the detection vibration section side,
Since only the predetermined vibration is stably propagated, the piezoelectric vibrator can effectively suppress spurious vibration and improve output sensitivity.

[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 1A constituting a piezoelectric vibrator.

FIG. 4 is a schematic diagram illustrating an electrical connection state of a detection-side vibrating portion 1B constituting a piezoelectric vibrator.

FIG. 5 is an explanatory view showing a state in which the piezoelectric vibrator is fixed to a base.

[Explanation of symbols]

 1 ... Piezoelectric vibrator 1A ... Driving side vibrating part 1B ... Detecting side vibrating part 2 ... Coupling Base part 3, 4,..., Vibrating branch of drive side vibrating part 5, 6,..., Vibrating branch of detection side vibrating part 7,. , 41-44 drive electrode 51-54, 61-64 detection electrode 10 base 11 spacer member

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01C 19/56 G01P 9/04 H01L 41/08 H03H 9/00

Claims (2)

(57) [Claims] 1. A driving vibration section comprising an even number of driving vibrating branches having driving electrodes formed on one opposing side face of a rectangular coupling base, and an even number detecting section having a detecting electrode formed on the other side face. In a piezoelectric vibrating body in which a detection vibrating portion composed of a side vibrating branch is disposed, a holding branch is disposed so as to straddle between the even-numbered detecting vibrating branches, and a drive is connected to the driving electrode on the holding branch. A piezoelectric vibrator, wherein a detection output electrode connected to the input electrode and the detection electrode is formed. 2. The piezoelectric vibrating body according to claim 1, wherein the holding branch is disposed so as to straddle a position serving as a node of a predetermined vibration of the detection-side vibration branch.