JP2000304543A - Angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make expectable of mass production effect with a simple constitution and relatively easily make the dimensional accuracy of a vibrator satisfactory. SOLUTION: An angular velocity sensor has piezoelectric element electrodes 2ab and 2ac arranged on the surface facing to a piezoelectric body 2aa, a piezoelectric element 2a with a square cross section and piezoelectric element electrodes 2bb and 2bc arranged on the facing surface of a piezoelectric body 2ba, piezoelectric element 2b with a square cross section and arranged in electrodes 3b, 3c and 3d integrated on the surface of base 3a and provided with a base element 3 with a square cross section and a vibrator 1 is constituted of nearly square column shape by stacking the base element 3 and the piezoelectric element 2a and 2b. Here, the piezoelectric element 2a and 2b are arranged on the base element 3 side by side in the short side direction and the piezoelectric electrodes 2ab and 2bb and the base element electrode 3d on one surface of the base element 3 are contacted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor used for detecting a camera shake of a video camera, detecting an operation in a virtual reality device, detecting a direction in a car navigation system, and the like.

[0002]

2. Description of the Related Art At present, as an angular velocity sensor for consumer use,
The most widespread type is one in which a rod-shaped vibrator is vibrated at a predetermined resonance frequency and an angular velocity is detected by detecting a Coriolis force generated by the influence of the angular velocity with a piezoelectric element or the like.

Conventionally, in such angular velocity sensors, a gyro-type angular velocity sensor having a structure in which a piezoelectric element is bonded to a triangular prism-shaped constant elastic metal vibrator or a structure in which electrodes are printed on a cylindrical piezoelectric ceramic has been put to practical use.

Conventionally, as a driving method, as shown in FIG. 5 (a) and FIG. 6 (a), an angular velocity sensor of a self-excited oscillation type driving circuit in which vibration is incorporated in a loop of a phase shift oscillation circuit is used. Was becoming common. In such an angular velocity sensor, self-excited vibration occurs at the resonance frequency of the vibrator.
A change in sensitivity due to temperature characteristics is small, and an angular velocity output with stable sensitivity can be obtained in a wide temperature range.

In the conventional angular velocity sensor shown in FIG. 5, an electrode 101a is provided on a side surface of a triangular prism-shaped constant elastic metal oscillator 100.
And a first piezoelectric element 101 comprising a piezoelectric body 101b and
A triangular prism-shaped vibrator 104 to which a second piezoelectric element 102 composed of an electrode 102a and a piezoelectric body 102b and a third piezoelectric element 103 composed of an electrode 103a and a piezoelectric body 103b is provided. This angular velocity sensor is connected to the amplifier 1 connected to the first piezoelectric element 101.
05, a phase shifter 106 connected to the amplifier 105, a differential amplifier 107 connected to the second piezoelectric element 102 and the third piezoelectric element 103, and a synchronous detector 108 connected to the differential amplifier 107. And a low-pass filter 109 connected to the synchronous detector 108.

At present, an angular velocity sensor using such a triangular prism-shaped vibrator 104 has the highest sensitivity and is in use today. However, since the structure such as the bonding of the piezoelectric element to the constant elastic metal sound piece and the support mechanism of the vibrator is complicated, it is difficult to achieve the mass production effect, and this tendency becomes more pronounced as the size is reduced.

On the other hand, the conventional angular velocity sensor shown in FIG. 6 has six electrodes 111, 112, 113, 11 printed on the side surfaces of a cylindrical piezoelectric ceramic (main body) 110.
4, 115, 116. The first to third electrodes 111, 112, and 113 are independent of each other, and the fourth electrode 114, the fifth electrode 115, and the sixth electrode 116 are connected to a common ground. The angular velocity sensor includes an amplifier 118 connected to the first electrode 111 and an amplifier 1
18, an adder 120 connected to the phase shifter 119, and second and third electrodes 112 and 1.
13 and the differential amplifier 12
1 and a synchronous detector 122 connected to the
And a low-pass filter 123 connected to

In the angular velocity sensor using the columnar piezoelectric ceramic vibrator 117, the vibrator 117 is vibrated by the first electrode 111, and the second and third electrodes 11 are vibrated.
2 and 113, the vibrator 11
7 and the Coriolis force generated in the vibrator 117 is detected by the second electrode 112 and the third electrode 113 at the same time.

Such a columnar piezoelectric ceramic vibrator 1
In the angular velocity sensor using No. 17, there is no problem associated with the bonding of the piezoelectric elements. However, since the electrodes are printed one by one on a curved surface, the effect of mass production cannot be expected. When the size is further reduced, it becomes difficult to ensure the accuracy of printing electrodes on the cylindrical piezoelectric ceramic vibrator and the curved surface.

Japanese Patent No. 2780643 discloses an angular velocity sensor including a vibrator 130 in which piezoelectric substrates 131 and 132 are stacked as shown in FIG.

Here, the vibrator 130 is formed on the first piezoelectric substrate 131, the second piezoelectric substrate 132, and the main surface of the first piezoelectric substrate 131 at intervals in the width direction thereof. Two divided electrodes 133 and 134 and a common electrode 135 formed on the main surface of the second piezoelectric substrate 132.
And a first piezoelectric substrate 131 and a second piezoelectric substrate 132
And a dummy electrode 136 formed between
It has a substantially columnar shape as a whole. Then, the first piezoelectric substrate 131 and the second piezoelectric substrate 132 are polarized so as to be polarized in directions opposite to each other in the thickness direction, as indicated by an arrow P in FIG.

The main surface of the vibrator 130 is obtained by applying a drive signal output from the oscillation circuit 137 between the two divided electrodes 133 and 134 and the common electrode 135 via the resistors 138 and 139. Bending vibration in the direction perpendicular to the direction. Then, at this time, the two divided electrodes 133,
Between 134, a signal corresponding to the rotational angular velocity is generated. The signal generated between the two divided electrodes 133 and 134 is supplied to the differential amplifier circuit 142 via the resistors 140 and 141.
And the rotational angular velocity is detected.

[0013]

As described above, an angular velocity sensor having a structure in which a piezoelectric element is bonded to a constant elastic metal vibrator has excellent sensitivity. However, since the structure is complicated, mass production in a manufacturing process is difficult. Difficult to produce an effect. In addition, as the miniaturization increases the accuracy of the supporting mechanism, the bonding accuracy of the piezoelectric element, and the effect of the bonding layer of the vibrator on the vibrator, the yield and cost increase due to the miniaturization are significant.

An angular velocity sensor having a structure using a columnar piezoelectric ceramic vibrator has a seemingly simple structure. However, as the size of the sensor is reduced, it becomes possible to manufacture a columnar ceramic (main body) with high accuracy. It becomes difficult to print the electrodes on a curved surface with high accuracy, and the mass production effect cannot be expected.

An angular velocity sensor in which a vibrator is constituted by a two-layered piezoelectric substrate is provided in a manufacturing process thereof.
It is necessary to polarize the entire piezoelectric substrate,
It takes time and effort. Also, to drive as a vibrator,
Electric power for driving the entire piezoelectric substrate is required, and it is desired to provide a vibrator that can be driven with low electric power.

Accordingly, the present invention has been proposed in view of the above-described conventional circumstances, and can be expected to achieve a mass-production effect with a simpler configuration. The dimensional accuracy can be satisfied relatively easily,
An object is to provide an angular velocity sensor having excellent detection sensitivity.

[0017]

In order to solve the above-mentioned problems, an angular velocity sensor according to the present invention includes a first piezoelectric member and a first piezoelectric member disposed on a surface of the first piezoelectric member facing the first piezoelectric member. A substantially plate-shaped first electrode comprising first and second piezoelectric element electrodes;
And a substantially plate-shaped second piezoelectric element comprising: a second piezoelectric element; and a third and a fourth piezoelectric element electrode disposed on a surface facing the second piezoelectric element. It has. Further, the angular velocity sensor includes a base element having a substantially rectangular cross section including a base and a base element electrode integrally arranged over at least two surfaces of the base. In the angular velocity sensor, the first and second piezoelectric elements and the base element are stacked to form a quadrangular prism-shaped vibrator. In this vibrator, a first piezoelectric element and a second piezoelectric element are arranged side by side in a short side direction on a base element, and the first and third piezoelectric element electrodes and the base element on one surface of the base element The electrodes are joined and laminated.

In the angular velocity sensor having such a configuration, the angular velocity is detected by applying a voltage between the second and fourth piezoelectric element electrodes and the base element electrode on the other surface which is not joined to the base element. A common-mode voltage is applied to the first and second piezoelectric elements to excite the vibrator, and the Coriolis force generated in the vibrator by the rotation is applied to the first and second piezoelectric elements.
Is detected by the piezoelectric element.

In the angular velocity sensor according to the present invention, the first and second piezoelectric elements having electrodes disposed on a pair of opposing surfaces are laminated on a base element having electrodes integrally formed on at least two surfaces, and are squared. A columnar vibrator is formed. By laminating the first and second piezoelectric elements on the base element, the first and third piezoelectric element electrodes are joined to the base element electrode on one surface of the base element. Then, the first and second piezoelectric elements are driven only by applying a voltage between the second and fourth piezoelectric element electrodes and the base element electrodes arranged on the other surface that is not joined to the base element. To vibrate the vibrator and simultaneously detect the Coriolis force.

The angular velocity sensor according to the present invention comprises:
Since it consists of a quadrangular prism-shaped vibrator with a structure in which a piezoelectric element and a base element are bonded together, it is manufactured without the need to attach a piezoelectric element to a constant elastic metal vibrator or print electrodes on a curved surface. You. Further, the vibrator is a process in which electrodes are formed by applying electrode plating to a wafer serving as a base material of a piezoelectric body and a wafer serving as a base material of a substrate, and then bonded, and then individually cut into a quadrangular prism shape. Can be manufactured.

Further, since the first and second piezoelectric elements for driving the vibrator have a substantially flat plate shape, the polarization processing is easy.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the following examples, and it goes without saying that the present invention can be arbitrarily changed without departing from the gist of the present invention.

FIGS. 1 to 3 show the basic structure of an example of an angular velocity sensor to which the present invention is applied. This angular velocity sensor includes a vibrator 1 that operates as a vibrating gyroscope.

This angular velocity sensor includes a first piezoelectric body 2a
a, a first piezoelectric element 2a having a substantially rectangular cross section, and a first piezoelectric element 2a comprising first and second piezoelectric element electrodes 2ab and 2ac arranged on the opposed surfaces of the first piezoelectric body 2aa. Body 2ba, and third and fourth piezoelectric element electrodes 2bb, 2b arranged on opposing surfaces of the second piezoelectric body 2ba
c) and a second piezoelectric element 2b having a substantially rectangular cross section. The angular velocity sensor includes a base 3a having a substantially rectangular cross section and a base element 3a and electrodes 3b, 3c, and 3d constituting base element electrodes that are integrally disposed on the surface of the base 3a. The base element 3 and the above-described first and second piezoelectric elements 2a and 2b are laminated to form a substantially quadrangular prism-shaped vibrator 1. In this vibrator 1, the first piezoelectric element 2a and the second piezoelectric element 2b are arranged side by side in the short side direction on the base element 3, and the first and third piezoelectric element electrodes 2ab and 2bb and the base element 3 and a base element electrode 3d on one surface are joined to form a laminated structure.

This angular velocity sensor applies a voltage between the second and fourth piezoelectric element electrodes and the electrode 3d on the other surface that is not joined to the base element 3, and applies a voltage to the first and second piezoelectric elements 2a. , 2b to excite the vibrator 1 and detect the angular velocity by detecting the Coriolis force generated in the vibrator 1 by the rotation by the first and second piezoelectric elements 2a, 2b.

The base element 3 comprises a base 3a, electrodes 3b, 3
c, 3d. The base element 3 includes electrodes 3b, 3c, and 3d integrally formed on the surface of the base 3a.
Is arranged.

The base 3a has a columnar shape with a substantially rectangular cross section. The base 3a is made up of the first and second piezoelectric elements 2
It is made of the same material as the piezoelectric material used for the piezoelectric bodies 2aa and 2ba of a and 2b. For example, PZT, which is a piezoelectric ceramic material, is used as the piezoelectric material.

The electrode 3d is connected to the piezoelectric element 2 on the base 3a.
a and 2b are electrodes arranged on the joint surface. That is, the electrode 3d is connected to the first and second piezoelectric elements 2a and 2b.
In a state where the base element 3 and the base element 3 are joined, they are electrically connected to the first piezoelectric element electrode 2ab of the first piezoelectric element 2a and the third piezoelectric element electrode 2bb of the second piezoelectric element 2b. Hereinafter, the electrode 3b is referred to as a bonding surface electrode 3d.

The electrodes 3c are electrodes arranged on each end face of the base 3a in the longitudinal direction. Hereinafter, the electrode 3c is referred to as an end face electrode 3c.

The electrode 3b is an electrode disposed on the surface of the base 3a opposite to the surface on which the bonding surface electrode 3d is disposed. Hereinafter, the electrode 3b is referred to as a back surface electrode 3b.

The electrodes 3b, 3c and 3d arranged on each surface of the base 3a are integrated with the electrodes on the adjacent surfaces. That is, the electrodes 3b, 3c, and 3d constitute an electrically integrated electrode. For example, the bonding surface electrode 3 d and the back surface electrode 3
b is electrically connected by the end face electrode 3c. Therefore, since the bonding surface electrode 3d is electrically connected to the piezoelectric element electrodes 2ab, 2bb of the piezoelectric elements 2a, 2b, the piezoelectric element electrodes 2ab, 2bb and the electrodes 3b, 3c, 3d acts as a common electrode as a result.

For example, the electrodes 3b, 3c, 3d
By performing electrode plating on a, it is formed integrally with the surface of the base 3a.

The first piezoelectric element 2a includes a first piezoelectric body 2a
a, and first and second piezoelectric element electrodes 2ab and 2ac disposed on respective surfaces thereof.

The first piezoelectric body 2aa has a plate shape with a substantially rectangular cross section made of a piezoelectric material. The first piezoelectric body 2aa is formed using the same material as the base 3a of the base element 3 described above, and is formed of, for example, PZT which is a piezoelectric ceramic material. This first piezoelectric body 2
aa is polarized.

The first piezoelectric element electrode 2ab is formed on one surface of the first piezoelectric element 2aa, and the second piezoelectric element 2ac
Is formed on the surface of the first piezoelectric body 2aa facing the first piezoelectric element electrode 2ab. The first piezoelectric element electrode 2ab is connected to the bonding surface electrode 3d of the base element 3 in a state where the first piezoelectric element 2a and the base element 3 are bonded.
Is electrically connected to That is, the first piezoelectric element electrode 2ab is electrically connected to the bonding surface electrode 3d,
An end face electrode 3c arranged on another surface of the base element 3,
Further, it is electrically connected to the back electrode 3b.

The second piezoelectric element 2b has the same configuration as the above-described first piezoelectric element 2a, and includes the second piezoelectric element 2ba and the third and fourth piezoelectric elements 2ba disposed on each surface thereof. The piezoelectric element electrodes 2bb and 2bc are provided.

The second piezoelectric body 2ba is made of a piezoelectric material and has a plate shape with a substantially rectangular cross section. The second piezoelectric element 2ba is formed of the first piezoelectric element 2aa and the base element 3 described above.
The substrate 3a is formed using the same material as the substrate 3a, for example, PZT which is a piezoelectric ceramic material. This second piezoelectric body 2ba is polarized.

The third piezoelectric element electrode 2bb is formed on one surface of the second piezoelectric body 2ba, and the fourth piezoelectric element 2bb
Is formed on the surface of the piezoelectric body 2ba facing the third piezoelectric element electrode 2bb. Further, the third piezoelectric element electrode 2
bb is electrically connected to the bonding surface electrode 3d of the base element 3 in a state where the second piezoelectric element 2b and the base element 3 are bonded. That is, the third piezoelectric element electrode 2
bb is the same as the above-described first piezoelectric element electrode 3ab,
By the electrical connection with the bonding surface electrode 3d, the end surface electrode 3c arranged on the other surface of the base element 3 and the back surface electrode 3b are electrically connected.

The first piezoelectric element 2 having such a configuration
a and the second piezoelectric element 2 b are arranged side by side in the short side direction on the vibrator 3, that is, have a configuration in which one piezoelectric element is divided in the longitudinal direction on the base element 3.

As described above, the vibrator 1 has the first and the second
Of the piezoelectric element 2a, 2b and the base element 3. Next, a manufacturing process of the vibrator 1 will be described with reference to FIG.

As shown in figure 4 (a), the respective wafer (piezoelectric wafer 2 _0, base wafer 3 ₀₎ is, for example, a substantially flat, the electrode plating process to each wafer, as a base After performing Ni plating, gold plating is performed as electrode plating. Plating on the substrate wafer 3 _0, the entire surface of each wafer, i.e. carried out for all faces. The electrode plating performed here is performed by the piezoelectric elements 2a,
2b and the base element 3 constitute each electrode.

The thickness of the piezoelectric wafer 2 _0, specifically, less than the thickness of the base wafer 3 _0, for example, the thickness of the piezoelectric wafer 2 ₀ 0.2 mm, the thickness of the substrate wafer 3 ₀ as 0.8mm I have.

For the polarization treatment of each of the piezoelectric elements 2a and 2b, gold plating is performed on a piezoelectric wafer having a thickness of 0.2 mm, and polarization is performed in a constant temperature bath at 120 ° C. under the conditions of 600 V and 30 minutes.

[0044] Then, as shown in FIG. 4 (a) (b), by laminating a piezoelectric wafer 2 ₀ and the base wafer 3 ₀ the electrode plated, are stacked. Here, the piezoelectric wafer 2 ₀ and the base wafer 3 _0, is subjected to pre-gold, while being a wafer of width 12 mm, and is bonded with a thermosetting resin adhesive.

FIG. 4 shows the laminated state.
Cut out individually in the direction of arrow AA in the middle (b) as a square prism. For example, when the cut-out, with respect to the electrode plating surface 2 _bc0 piezoelectric wafer 2 _0, and a slit having the same depth as the thickness of the piezoelectric wafer 2 _0, i.e., the slits only in the piezoelectric wafer 2 ₀ The first piezoelectric element 2a and the second piezoelectric element 2b are separated and molded.

By this individual cutting, (c) in FIG.
As shown in (1), a vibrator 1 having a substantially square column shape in cross section is obtained. That is, the first piezoelectric element 2a in which the piezoelectric element electrodes 2ab and 2ac are formed on the first piezoelectric element 2aa, and the second piezoelectric element 2b in which the piezoelectric element electrodes 2bb and 2bc are formed on the second piezoelectric element ba And the base element 3 on which the end face electrode 3c and the back face electrode 3b are formed.
A vibrator 1 is obtained in which a, 2b and the base element 3 are electrically connected at their joint surfaces.

For example, with regard to the end face electrode 3c and the back face electrode 3b formed on the base element 3, the wafers plated with electrodes are bonded and bonded by the above-described manufacturing process, and thereafter, only the cutting process is performed. It is formed integrally with the bonding surface electrode 3d electrically connected to each of the piezoelectric elements 2a, 2b, and thus can be easily formed.

The vibrator 1 is, for example, a vibrator having a sectional shape of 1.0 mm × 1.0 mm and a length of 12 mm. In the vibrator 1, the thickness of each of the piezoelectric elements 2 a and 2 b is smaller than the thickness of the base element 3.

[0049] Here, the piezoelectric wafer 2 ₀ and the substrate wafer 3 ₀
Can be easily processed by using the same material. Further, by reducing the thickness of the piezoelectric elements 2a and 2b, the polarization process is facilitated, and the low-voltage driving of the vibrator 1 is facilitated.

The angular velocity sensor includes an adder 4, an amplifier 5, a phase shifter 6, a differential amplifier, and a circuit for oscillating the vibrator 1 having the above structure and detecting Coriolis force. 7, a synchronous detector 8, and a low-pass filter 9.

More specifically, the angular velocity sensor comprises an adder 4
, The amplifier 5, the phase shifter 6, and the piezoelectric element electrodes 2ac, 2bc of the piezoelectric elements 2a, 2b constitute a vibration drive unit for vibrating the vibrator 1. The angular velocity sensor includes a differential amplifier 7, a synchronous detector 8 connected to the output of the adder 4, a low-pass filter 9, and a piezoelectric element 2.
A detection unit that detects the Coriolis force when the vibrator 1 vibrates is constituted by the piezoelectric element electrodes 2ac and 2bc of a and 2b.

A detailed description will be given along the flow of signals output from the first and second piezoelectric elements 2a and 2b. In the vibration drive section, the piezoelectric element electrodes 2a and 2b of the piezoelectric elements 2a and 2b
The outputs (S +, S−) of ac and 2bc are input to the adder 4, and the added value is taken by the adder 4. The output from the adder 4 is input to the amplifier 5, where the input signal is amplified. The phase of the output from the amplifier 5 is shifted by the phase shifter 6, and is output to each of the piezoelectric element electrodes 2ac and 2bc. The circuit forming the vibrator driving section constitutes a so-called phase-shift oscillation circuit, and thereby vibrates the vibrator 1 by self-excitation.

[0053] Here, each of the piezoelectric elements 2a, as the polarization direction of the 2b is shown in FIG. 3, is the direction of the arrow Z ₂ is a direction in which the respective piezoelectric elements 2a, a 2b and the base element 3 are laminated since, will be the piezoelectric elements 2a, 2b is expanded and contracted in the longitudinal direction, the vibrator 1 bending vibration in the direction of arrow Z ₁ shown in FIG. 2 is a longitudinal and vertical directions of the vibrator 1.

In the detecting section, the piezoelectric elements 2a,
2b from the piezoelectric element electrodes 2ac and 2bc (S +,
S-) are input to the differential amplifier 7, where the differential is obtained.

It is necessary to connect the first piezoelectric element electrode 2ab of the first piezoelectric element 2a and the first piezoelectric element electrode 2bb of the second piezoelectric element 2b to the midpoint reference potential. Is connected to the midpoint reference potential C, the piezoelectric element electrodes 2ab and 2bb are connected to the base element 3d.
Is connected to the midpoint reference potential C via the junction surface electrode 3b.

When the vibrator 1 is vibrating in the vibration direction, the angular velocity sensor detects the Coriolis force generated on the vibrator 1 by the rotation of the vibrator 1 by each of the piezoelectric elements 2a and 2b. These differentials are obtained by the differential amplifier 7. The output from the differential amplifier 7 is
The signal is input to the synchronous detector 8, where synchronous detection is performed.
At this time, in order to perform synchronous detection, the synchronous detector 8
The output from the adder 4 is supplied as a synchronization signal. Then, the output from the synchronous detector 8 is output as an angular velocity signal obtained by detecting the Coriolis force generated in the vibrator 1 via the low-pass filter 9.

With the above configuration, the angular velocity sensor has both a vibrator driving function and a function of detecting the vibration. Thereby, the angular velocity sensor can detect the angular velocity with high sensitivity by the function of detecting the Coriolis force generated by the rotation of the vibrator 1 while vibrating by the vibrator driving function.

Further, as described above, the piezoelectric elements 2a,
By making the thickness of the piezoelectric elements 2a and 2b smaller than the thickness of the base element 3 in the direction in which the base element 3 and the base element 3 are stacked, the polarization processing of the piezoelectric elements 2a and 2b can be facilitated. In addition, low-voltage driving of the vibrator 1 can be facilitated. Furthermore, as for the substrate, needless to say, there is no need for a polarization treatment, and the substrate is not limited to being formed of a piezoelectric material, so that the material can be freely selected.

Further, as described above, this angular velocity sensor has a structure in which the piezoelectric element and the base element are bonded to each other, and is configured as a quadrangular prism vibrator. Therefore, the angular velocity sensor has a very simple structure, thereby manufacturing a vibrator without requiring a step of bonding a piezoelectric element to a constant elastic metal vibrator or printing an electrode on a curved surface as in the related art. Make it possible. The vibrator is manufactured by a process in which electrodes are formed by applying electrode plating to a piezoelectric wafer or a base wafer, and then bonded, and then cut out as individual quadrangular prism vibrators. In addition, the structure can be miniaturized and the effect of mass production can be easily obtained. In addition, the angular velocity sensor can eliminate the imbalance of the vibrator due to the displacement of the bonding position of the piezoelectric element, and can reduce the influence on the characteristics.

In the case of having the piezoelectric elements 2a and 2b configured as described above, it is necessary to draw out the electrodes from the piezoelectric element electrodes 2ab and 2bb of the piezoelectric elements 2a and 2b. Since the back electrode 3b of the base element 3 serving as a common electrode of 2ab and 2bb can be pulled out to the midpoint reference potential, the piezoelectric element 2
Even when the a and 2b and the base element 3 are bonded to each other, a voltage can be applied to each of the piezoelectric elements 2a and 2b, and a signal for detecting an angular velocity can be extracted. Thus, the vibrator 1 has a simple structure.

Further, since the back electrode 3b can be pulled out to the midpoint reference electrode, the driving voltage can be applied with less influence on the vibration operation of the vibrator 1.

Further, by forming the piezoelectric bodies 2aa, 2ba constituting the piezoelectric elements 2a, 2b and the substrate 3a from the same material, for example, the thermal, acoustic or structural reliability of the vibrator 1 can be improved. Workability can be improved.

Also, it is considered that the technical difficulty increases with the miniaturization, and it is considered difficult to ensure the accuracy. However, since the vibrator 1 has a square pole shape, it is already necessary to process the head. Such problems can be solved by applying the established microfabrication technology. Therefore, high-precision dimensional accuracy can be obtained, so that the frequency adjustment of the vibrator can be simplified.

The angular velocity sensor has a very simple structure, and does not impair accuracy even if the size is reduced.
Mass production effects can be expected, cost performance is high, and high sensitivity is achieved. In addition, the cost reduction, miniaturization, and high sensitivity of the angular velocity sensor meet the demand for further miniaturization and high cost performance of video cameras, virtual reality devices, and the like.

In the angular velocity sensor, when the polarization direction is reversed, the sign of the output with respect to the rotation direction is reversed, but there is no problem in operation.

[0066]

According to the angular velocity sensor according to the present invention, the first and second piezoelectric elements having electrodes disposed on a pair of opposing surfaces include:
A square vibrator in which the first and third piezoelectric element electrodes are joined to the base element electrode on one side of the base element by laminating the base element on which at least two surfaces are provided with integrated electrodes is formed. Further, the first and second piezoelectric elements are only applied by applying a voltage between the second and fourth piezoelectric element electrodes and the base element electrode disposed on the other surface that is not joined to the base element. To drive the vibrator and simultaneously detect the Coriolis force.

Thus, the angular velocity sensor has a very simple structure. Therefore, the angular velocity sensor can be expected to be mass-produced without deteriorating the accuracy even if the size is reduced, and is an angular velocity sensor with high cost performance and high sensitivity.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of an angular velocity sensor to which the present invention is applied.

FIG. 2 is a perspective view showing a configuration of an angular velocity sensor.

FIG. 3 is a side view illustrating a configuration of an angular velocity sensor.

FIG. 4 is a view used to explain a manufacturing process of the vibrator of the angular velocity sensor.

FIG. 5 is a diagram showing an example of a conventional angular velocity sensor;
(A) is a figure which shows the whole structure of the said angular velocity sensor, (b) is a perspective view which shows the part of a vibrator, (c)
FIG. 4 is a cross-sectional view showing a cross section at a central portion of the vibrator.

6A and 6B are diagrams illustrating another example of a conventional angular velocity sensor, in which FIG. 6A is a diagram illustrating an entire configuration of the angular velocity sensor, and FIG. 6B is a perspective view illustrating a vibrator;
(C) is a cross-sectional view showing a cross section at the center of the vibrator.

FIG. 7 is a diagram showing another example of each of the conventional speed sensors different from FIGS. 5 and 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vibrator, 2a 1st piezoelectric element, 2aa 1st piezoelectric element, 2ab 1st piezoelectric element electrode, 2ac 2nd piezoelectric element electrode, 2b 2nd piezoelectric element, 2ba 2nd piezoelectric element, 2bb 3 piezoelectric element electrode, 2bc fourth piezoelectric element electrode, 3 base element, 3a base, 3b back electrode,
3c end face electrode, 3d junction face electrode

Claims (4)

[Claims] 1. A substantially plate-shaped first piezoelectric element comprising: a first piezoelectric element; and first and second piezoelectric element electrodes disposed on surfaces of the first piezoelectric element opposite to each other. A substantially plate-shaped second piezoelectric element including a second piezoelectric element, and third and fourth piezoelectric element electrodes disposed on surfaces of the second piezoelectric element opposite to each other; A substrate element having a substantially rectangular cross-section, comprising a substrate element electrode integrally disposed over at least two surfaces of the substrate; and a quadrangular prism-shaped vibrator formed by stacking the vibrator. The first piezoelectric element and the second piezoelectric element are arranged side by side in the short side direction on the base element, and the first and third piezoelectric element electrodes and the base element electrode on one surface of the base element Are bonded and laminated, and the detection of the angular velocity is performed by the second and fourth piezoelectric element electrodes. A voltage is applied between the base element and the base element electrode on the other surface that is not joined to the base element, and the first and second base elements are applied.
Applying an in-phase voltage to the piezoelectric element to excite the vibrator and detecting the Coriolis force generated in the vibrator by rotation by the first and second piezoelectric elements. . 2. The method according to claim 1, wherein the first piezoelectric body and the second piezoelectric body are made of the same piezoelectric material, and the base is made of the same piezoelectric material as the first and second piezoelectric bodies. The angular velocity sensor according to claim 1, wherein: 3. The base element electrode on the other surface, which is not bonded to the base element, is integrally formed from a longitudinal end surface of the base to a surface facing the bonding surface of the first and second piezoelectric elements. Wherein the detection of the angular velocity is performed by applying a voltage between the second and fourth piezoelectric element electrodes and the base element electrode on the surface facing the bonding surface. The angular velocity sensor according to claim 1. 4. The angular velocity sensor according to claim 1, wherein the thickness in the direction in which the first and second piezoelectric elements are stacked is smaller than the thickness in the direction in which the base elements are stacked.