JPH0894363A - Vibrator and yaw rate sensor using it - Google Patents

Abstract

PURPOSE: To simplify the adjustment of resonance frequencies of the excitation vibration and detecting vibration of a vibrator. CONSTITUTION: A yaw rate sensor 10 is provided with a vibrator 12 fixed to and supported by a fixed body 14. The vibrator 12 is provided with a vibrating piece 18 positioned at the center of the vibrator 12, exciters 20 and 22 respectively stuck to both end faces of the piece 18 at both ends, and detectors 24 and 26 respectively stuck to the exciters 20 and 22. The exciters 20 and 22 set the left-side vibrating piece section 18a and right-side vibrating piece section 18b of the piece 18 to steady vibrating states in the longitudinal direction along x-axis. When a rotational angular velocity acts on the vibrator 12 around z-axis, a Coriolis force is generated along y-axis. By using the Coriolis force, therefore, the sections 18a and 18b are caused to generate slipping vibrations, namely, transversal vibrations which are different from the longitudinal vibrations along y-axis and the detectors 24 and 26 detect the shear vibrations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrator having a resonator element capable of causing longitudinal vibration and a yaw rate sensor using the vibrator.

[0002]

2. Description of the Related Art When a vibrating reed that is in a vibrating state rotates about an axis orthogonal to the direction of vibration, Coriolis force acts on the vibrating reed due to the angular velocity of rotation. Since the Coriolis force is determined depending on the angular velocity, the Coriolis force is indirectly measured as the bending displacement amount of the vibrating element or directly measured by the piezoelectric effect of the piezoelectric element to obtain the angular velocity of the vibrating element. be able to. For this reason, a vibrating reed is mounted on a vehicle or the like to detect a yaw rate generated when the vehicle turns and to record a traveling locus of the vehicle.

As an example of such a vibrator, in Japanese Patent Publication No. 4-504617, a vibrator in which a pair of vibrating reeds is arranged in a tuning fork type is proposed, and in Kaikaihei 1-81514, an H-shaped vibrator is proposed. Has been done. Then, in each of these vibrators, the vibrating piece is placed in an excited state of lateral vibration in a predetermined axis, for example, the x-axis direction, and the z-axis orthogonal to the xy plane in which the lateral vibration occurs has a yaw rate. It is used as an axis. Therefore, when the vibrating piece of the vibrator rotates about the yaw rate axis, the Coriolis force causes lateral vibration in the y-axis direction on the vibrating piece, and the yaw rate is detected from the vibrating state of the lateral vibration.

In the vibrators proposed in these publications, the following techniques have been proposed in order to improve the detection sensitivity of the Coriolis force. For example, Japanese Patent Publication No. 4-50461
In 7, it is proposed to perform mass adjustment so that the resonance frequency of lateral vibration in the x-axis direction of the vibrating piece to be excited and the resonance frequency of lateral vibration in the y-axis direction of the vibrating piece to be detected match. Has been done. Then, as a method of adjusting the mass, in the actual Kaihei 1-81514, each vibration piece is integrally provided with an adjustment weight through a constricted portion, and each adjustment weight is measured while measuring the resonance frequency of each vibration piece. Techniques for melting and removing have been proposed. The reason why it is necessary to match the resonance frequencies in the respective directions between the vibrating element to be excited and the vibrating element to be detected is as follows.

When a Coriolis force due to an angular velocity is applied in the y-axis direction to a resonator element that is excited to laterally vibrate in the x-axis direction, the motion of the resonator element causes lateral vibration in a single direction (x-axis direction). To change to rotary motion. At this time, the vibrating piece causes a rotational movement with its free end bent. When this rotational motion is decomposed into a vector of the x-axis and a vector of the y-axis orthogonal thereto, the rotational motion is divided into excitation vibration which is lateral vibration in the x-axis direction and detection vibration which is lateral vibration in the y-axis direction. In order to increase the detection sensitivity of the Coriolis force, it is effective to increase the amplitude of the lateral vibration as the detected vibration as much as possible to increase the bending displacement amount of the vibrating piece. Therefore, the resonance frequency of the lateral vibration as the detected vibration may be matched with the resonance frequency of the lateral vibration as the excited vibration so that the amplitude of the detected vibration due to the Coriolis force becomes the maximum amplitude.

[0006]

However, in the method of adjusting the mass as described above, the measurement of the resonance frequency and the melting and removing process of the specific portion must be performed in parallel. In addition, the mass removed by melting cannot be measured. Therefore, the adjustment work is complicated.

Moreover, when there are two or more vibrating pieces, generally, each vibrating piece has a resonance frequency fxi in the x-axis direction (subscript i means the vibrating piece) and a resonance frequency fyi in the y-axis direction.
And these four or more resonant frequencies are related to each other. Therefore, in the conventional technique, it is difficult to adjust the resonance frequency, because it is necessary to independently adjust the resonance frequency of the excitation vibration and the resonance frequency of the detection vibration. That is,
The resonance frequency fxi in the x-axis direction and the resonance frequency fyi in the y-axis direction of each vibrating piece, and four or more of these resonance frequencies change intricately with each other, so adjustment of the resonance frequency is not easy and requires a high degree of skill. There was a problem.

The present invention has been made to solve the above problems, and an object thereof is to simplify the work of adjusting the resonance frequency of excitation vibration and the resonance frequency of detection vibration in a vibrator. Another object is to improve the detection sensitivity of a yaw rate sensor using a vibrator whose frequency has been adjusted.

[0009]

[Means for Solving the Problems] The means adopted by the vibrator according to claim 1 for achieving the above object is as follows.
A vibrating element capable of longitudinal vibration in one direction and laterally vibrating in the other direction orthogonal to the one direction, and excitation in the vibrating element as vibration in one of the longitudinal vibration and the lateral vibration as excitation vibration. The gist of the present invention is to include excitation means for causing the vibration piece and detection means for detecting a vibration state of a vibration different from the excitation vibration among the longitudinal vibration and the lateral vibration in the vibrating piece.

Further, the means adopted by the yaw rate sensor according to claim 2 is provided with the vibrator according to claim 1 arranged such that both the one direction and the other direction are orthogonal to the yaw rate axis. Excitation means for exciting the longitudinal vibration as excitation vibration, detecting means for detecting the vibration state of the lateral vibration in the vibrating piece, and calculating means for calculating the yaw rate based on the vibration state detected by the detecting means. The point is to have and.

[0011]

The vibrator according to claim 1 having the above structure,
The resonance frequency of the longitudinal vibration of the vibrating element is determined depending on the length of the vibrator as a whole in the longitudinal vibration direction because the vibration is the longitudinal vibration. And the vertical vibration of the vibrating piece is
Since lateral vibration is a different kind of vibration, it has no effect on the vibration state when the vibrating piece vibrates laterally. That is, the lateral vibration of the resonator element is not affected by the longitudinal vibration of the resonator element. Then, the resonance frequency of the lateral vibration of the resonator element is determined depending on the width of the entire vibrator along the lateral vibration direction.

Accordingly, the work of matching or approximating the resonance frequency of the longitudinal vibration and the resonance frequency of the transverse vibration of the vibrating piece is performed by the length of the vibrator as a whole in the longitudinal vibration direction and the width in the transverse vibration direction. Adjustment is enough.

In the vibrator according to the present invention, either the longitudinal vibration or the transverse vibration is excited as the excitation vibration in the vibrating piece. Then, since the vibrating piece is placed in the state of steady longitudinal vibration or lateral vibration, it is possible to generate Coriolis force due to the rotation of the vibrator. Therefore, the Coriolis force can cause lateral vibration or longitudinal vibration in the vibrating piece in a direction orthogonal to the above-described excited vibration.

Here, how the resonance frequency is adjusted will be described using an ideal model. The vertical vibration of the vibrating element can be approximated to the vertical vibration of a straight rod having a uniform cross section (length × width = a × b). The resonance frequency fx of the vertical vibration of the rod is expressed by the following formula.

Fx = (λ / 2π · l) √ (E / ρ) ...

Here, λ is a dimensionless coefficient determined by boundary conditions and vibration modes, E is a longitudinal elastic coefficient, ρ is density, and l is
Is the length of the bar. Since the longitudinal elastic modulus E and the density ρ are values that are naturally determined by specifying the material of the resonator element,
The only variable in the formula is l.

On the other hand, the lateral vibration of the vibrating element can be approximated to that of a beam having a straight uniform cross section (length × width = a × b). Then, the resonance frequency fy of the lateral vibration of this beam is expressed by the following formula.

Fy = (λ ² / 2π · l ² ) √ (E · I / A · ρ) ...

Where λ is a dimensionless coefficient determined by boundary conditions and vibration modes, E is the longitudinal elastic modulus, I is the second moment of area, A is the cross-sectional area, ρ is the density, and l is the beam length. . If the exciting force that causes this lateral vibration is applied from the side of the beam, the second moment of area I is a · b ³ /
Since the cross-sectional area A is 12, the equation can be transformed into an equation.

[0020] ^{fy = (λ 2 / 2π ·} l 2) √ (E · (a · b 3/12) / (a · b) · ρ) = (λ 2 / 2π · l 2) √ (E · b ^{2/12 · ρ) = (} λ 2 · b / 2π · l 2) √ (E / 12 · ρ) ...

Even in this equation, since the longitudinal elastic modulus E and the density ρ are values that are naturally determined by specifying the material of the resonator element, the variables in the equation are b and l.

Therefore, first, by defining l, the resonance frequency fx of the longitudinal vibration of the resonator element is defined from the equation, and then the lateral width b of the resonator element is adjusted, so that only the resonance frequency fy of the lateral vibration is independently determined. It can be changed so that fx = fy. Therefore, when the Coriolis force acts on the vibrating piece to cause either lateral vibration or vertical vibration, the vibrating piece resonates with the vibration due to the Coriolis force and causes lateral vibration or longitudinal vibration with a large amplitude. . Therefore, it is possible to increase the amount of bending displacement of the vibrating element due to lateral vibration or vertical vibration. Then, by detecting the induced vibration state of the lateral vibration or the longitudinal vibration with the detector, it becomes possible to increase the detection sensitivity of the Coriolis force.

In this case, the lateral width b of the vibrating element can be adjusted by performing appropriate machining such as cutting and polishing, or by performing thin film forming processing such as vapor deposition, sputtering and CVD. And good and bad adjustment is
This can be confirmed by measuring the lateral width of the vibrating piece.

The vibrating element constituting the vibrator is not particularly limited in terms of material as long as it can cause longitudinal vibration. For example, in addition to various metals such as stainless steel, iron-nickel alloys and constant elastic alloys, quartz, PZ
The resonator element can be formed using a dielectric such as T, a semiconductor such as silicon, a powder sintered body, a crystal body, or a ceramic.

As for the excitation means for vibrating the vibrating element (either longitudinal vibration or transverse vibration), an appropriate structure may be selected in consideration of the material of the vibrating element. For example, if the resonator element is formed of a crystal such as metal, crystal, or semiconductor, glass, ceramic, or the like, a piezoelectric element such as a piezo element (PZT) is used, and the resonator element is formed by the inverse piezoelectric effect of the element. Just vibrate. Further, if the vibrating piece is formed by using a material having a piezoelectric effect such as a crystal body such as a crystal or a semiconductor or a ceramic, it is possible to vibrate the vibrating piece by an inverse piezoelectric effect of the vibrating piece itself by using an electrode. Good. On the other hand, as for the detection means for detecting the vibration state of the vibration caused in the vibrating element, the detection is performed by the piezoelectric effect such as a piezoelectric element such as a piezo element (PZT) or the piezoelectric effect through an electrode, or the change of the induced magnetic force or the capacitance charge. Can be taken.

In the yaw rate sensor according to a second aspect of the present invention, when the vibrator according to the first aspect is arranged, the vibrating direction of the longitudinal vibration and the vibrating direction of the lateral vibration of the vibrating element are orthogonal to the yaw rate axis. Then, the vibrating element is placed in a state of constant longitudinal vibration by the excitation means. For this reason, when the vibrating piece rotates around the yaw rate axis, Coriolis force is generated, so that the Coriolis force causes lateral vibration in the vibrating piece. The vibration state of the induced lateral vibration is detected by the detecting means of the vibrator, and based on the detection signal, the yaw rate sensor according to claim 2 calculates the yaw rate by the calculating means. By the way, since the resonance frequency fy of the lateral vibration of the vibrating piece matches the resonance frequency fx of the longitudinal vibration, when the vibrating piece causes the lateral vibration caused by the Coriolis force, the vibrating piece becomes larger due to resonance. Lateral vibration occurs at the amplitude, and the amount of flexural displacement increases. Therefore,
The Coriolis force and eventually the yaw rate can be detected with high sensitivity.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the yaw rate sensor according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of a yaw rate sensor 10 of the embodiment. As shown, the yaw rate sensor 10 includes a vibrator 12 fixed to and supported by a pair of fixed bodies 14. Oscillator 12
Is a vibrating piece 18 located at the center of the vibrating piece 18, which is supported by the support body 16 on the fixed body 14, exciters 20 and 22 adhered to the end faces of both ends of the vibrating piece 18, and a detector adhered to the exciter. 24 and 26 are provided.

The vibrating reed 18 is made of a so-called Elanbar material plate which is an iron-nickel-chromium alloy and has a constant elasticity. Then, the vibrating piece 18 is welded to the support body 16, or the fixed body 14 and the support body 16 are welded.
The vibrator 12 is formed by integrally forming the vibrating piece 18 and the vibrating piece 18.
Are fixed and supported by the support body 16 on the fixed body 14.

The exciters 20 and 22 are piezo elements which are piezoelectric elements, and receive application of an AC voltage from an excitation circuit 30 which will be described later to expand and contract, and extend vertically along the x-axis in the illustrated three-dimensional orthogonal coordinate axes. Cause vibration. And exciter 2
0 and 22 are the vibrating bars 1 as shown by the white arrows in the figure.
8 is excited by this longitudinal vibration. The way in which the resonator element 18 is excited by the exciters 20 and 22 will be described later.

The detectors 24 and 26 are piezoelectric elements, which are also piezoelectric elements, and generate an electric signal of an AC voltage according to expansion and contraction of the piezoelectric elements. That is, as shown in FIG. 2, which is a plan view of the vibrator 12, the detectors 24 and 26 have the left vibrating piece portion 18a and the right vibrating piece portion 18b when the vibrating piece 18 is divided along the y axis. When is horizontally vibrated along the y-axis direction, it expands and contracts with the vibration. Then, the detectors 24 and 26 generate an AC voltage electric signal corresponding to the amplitude of lateral vibration in the y-axis direction of the left vibration piece 18a and the right vibration piece 18b, which is the degree of expansion and contraction of each detection element. , Caused by the piezoelectric effect. Detector 24,2
The electric signals of the AC voltage obtained from 6 are output to the detection balance adjusting circuit 38, which will be described later.

Next, the circuit configuration of the yaw rate sensor 10 will be described. Exciter 20 in oscillator 12,
Each of 22 is connected to the excitation circuit 30, and each of the detectors 24 and 26 is connected to the detection side circuit 37.

The detection side circuit 37 is the detector 2 of the vibrator 12.
A detection balance adjusting circuit 38 for adjusting the phase of the electric signal (AC voltage) generated by the piezoelectric effect from 4, 26.
An amplification circuit 40 for amplifying the output level of the electric signal adjusted by the detection balance adjustment circuit 38, and a synchronous detection circuit 42 for rectifying the negative portion of the electric signal which is an AC voltage to invert it to a positive voltage. An integrating circuit 44 for converting the positive voltage electric signal into a rectified voltage electric signal, and an amplification output circuit 46 for amplifying the output level of the rectified voltage electric signal.
Composed of and.

From the excitation circuit 30, the exciter 20 and the exciter 22 receive an AC voltage having a frequency matching the resonance frequency fx of the longitudinal vibration of the left vibrating bar portion 18a and the right vibrating bar portion 18b in the x-axis direction. Are applied 180 degrees out of phase. Therefore, the exciter 20 and the exciter 22 are such that the exciter 22 extends in the + x direction when the exciter 20 extends in the −x direction, and the exciter 22 moves in the −x direction when the exciter 20 contracts in the + x direction. So that it contracts in the opposite direction along the x-axis direction due to the inverse piezoelectric effect. As a result, the left side vibrating piece portion 18a of the vibrating piece 18 and the right vibrating piece portion 1
8b longitudinally vibrates in the x-axis direction at the frequency of the resonance frequency fx, and the longitudinal vibration directions of both vibrating bar portions are opposite.

The longitudinal vibration can be approximated to that of a rod having a uniform cross section because the vibrator 12 is fixedly supported by the fixed body 14 at the center of the vibrating piece 18. That is, the left vibrating piece 1
8a, the right-side vibrating bar portion 18b has a vibration node at the center of the vibrating bar 18, and the length l of the vibrator 12 as a whole in the x-axis direction.
Longitudinal vibration that causes x (see FIG. 2) to be a half wavelength is generated. Then, the resonance frequency fx at this time is defined by the length lx (see FIG. 2) in the x-axis direction of the entire vibrator 12, excluding constants such as the elastic coefficient.

Thus, the left vibrating bar portion 1 of the vibrating bar 18 is
When the rotational angular velocity ω acts on the yaw rate sensor 10 around the z axis orthogonal to the xy plane while the vertical vibration piece 8a and the right vibration piece portion 18b continue vertical vibration in the x axis direction, the left vibration piece The portion 18a and the right-side vibrating piece portion 18b receive the Coriolis force F represented by the following mathematical formula along the y-axis. That is,
In this yaw rate sensor 10, the z axis shown in FIG. 1 is the yaw rate axis.

F = 2 mV · ω

Here, m is the mass of the left vibrating bar portion 18a and the right vibrating bar portion 18b, and V is the rotational speed of each vibrating bar portion.

Therefore, as shown by the chain double-dashed line in FIG. 2, the left vibrating bar portion 18a and the right vibrating bar portion 18b generate lateral vibration and sliding vibration along the y axis by the Coriolis force F. Wake up. Moreover, since the vibration directions of the longitudinal vibration are opposite in the left and right vibrating bars, the vibration directions of the sliding vibration are also opposite.

In this sliding vibration, the vibrator 12 is the vibrating piece 1.
Since it is fixedly supported by the fixed body 14 at the center of 8, the longitudinal vibration of the beam having a uniform cross section can be approximated. That is, the left vibrating bar portion 18a and the right vibrating bar portion 18b have the width twy of the vibrator 12 (see FIG. 2) and the thickness t of the vibrator 12 as a whole.
(Refer to FIG. 1) and a resonance frequency fy defined by a constant such as an elastic coefficient, the slip vibration occurs in the opposite direction. Note that this thickness t
Is set to a predetermined value, the resonance frequency f of this sliding vibration is
y is defined by the width wy of the vibrator 12 in the y-axis direction.

When the left vibrating bar portion 18a and the right vibrating bar portion 18b receive the Coriolis force F and undergo a sliding vibration (lateral vibration) along the y-axis in this way, the detectors 24 and 26 are affected by this vibration. Along with the expansion and contraction, the piezoelectric effect of each element produces an electric signal of a voltage corresponding to the expansion and contraction of each element. This electrical signal is
Since the expansion and contraction of each element are reflected, the electric signal is an alternating current signal, and when the expansion and contraction is large, the electric signal has a large output level. At this time, the detectors 24 and 26 expand and contract so that the directions of expansion and contraction thereof are opposite to each other.
Therefore, the electric signals generated by the detectors 24 and 26 are as shown in FIG.
As shown in, the AC voltages are 180 degrees out of phase with each other.

The electric signals obtained from the detectors 24 and 26 of the left and right vibrating bars are input to the detection balance adjusting circuit 38. In this detection balance adjusting circuit 38, the phases of the electric signals from the respective detectors are made uniform. To be The amplifier circuit 40 amplifies the output level of the electric signal. In the synchronous detection circuit 42, the electric signal, which is an AC voltage, is detected in synchronization with the reference signal of the excitation circuit 30 to be a positive voltage electric signal. In the integrating circuit 44, the electric signal converted into a positive voltage becomes an electric signal of a rectified voltage. The electrical signal of the rectified voltage is amplified and output circuit 46.
Is amplified and output. In other words, Coriolis force F
An electric signal that reflects the vibration state of the sliding vibration of the vibrating reed 18 along the y-axis is obtained as a linear output signal via the detection balance adjustment circuit 38 of the detection side circuit 37 and the like. This output signal becomes a yaw rate signal that represents the direction and the magnitude of the rotational angular velocity ω when the yaw rate sensor 10 rotates about the z axis. Therefore, if the yaw rate sensor 10 is mounted on a vehicle, the turning direction of the vehicle and its size per unit time can be detected.

By the way, the yaw rate sensor 1 of this embodiment
In No. 0, the oscillator 12 was formed as follows.
That is, first, the constants such as the elastic coefficient of the elanbar material used for the resonator element 18, the exciter 20, the detector 24, and the like, and the vibrator 1 are used.
2 Based on the overall length 1x in the x-axis direction, the resonance frequency fx when the left vibration piece 18a and the right vibration piece 18b vertically vibrates was determined. Subsequently, the width wy in the y-axis direction of the vibrator 12 as a whole was adjusted by a method such as cutting to independently change only the resonance frequency fy of the sliding vibration (lateral vibration), and fx = fy was set. In this way, only the resonance frequency fy of the sliding vibration can be independently changed because the left vibration piece 1
This is because the vibrations of the vibration piece 8a on the right side and the vibration piece on the right side 18b are different kinds of vibrations such as longitudinal vibration and lateral vibration.

As described above, in the yaw rate sensor 10 of this embodiment, when the left vibrating bar portion 18a and the right vibrating bar portion 18b are excited to vibrate them, the vibrating bar portions are placed in a steady vibration state. The excited vibration of was defined as the longitudinal vibration, and the detected vibration caused by the Coriolis force was defined as the sliding vibration (transverse vibration), which is a vibration different from the longitudinal vibration. Moreover,
In the yaw rate sensor 10 of this embodiment, the vibrator 12 including the vibrating piece 18 made of an elanbar material, the exciter 20 which is a piezoelectric element, the detector 24, etc., has an overall x-axis direction length lx and a y-axis direction. The size of the width wy is specified at the design stage to form the vibrator 12, and then the width w in the y-axis direction is set.
The resonance frequency fx of the longitudinal vibration and the resonance frequency fy of the lateral vibration can be made to coincide with each other only by adjusting y. In this case, the y-axis direction width wy and the thickness t can be easily adjusted by performing a thin film forming process such as vapor deposition, sputtering, and CVD.

Therefore, the yaw rate sensor 10 of this embodiment is
According to the above, the vibrating piece 18 that is an excited vibration in the vibrator 12
In adjusting the resonance frequency fx of the vertical vibration and the resonance frequency fy of the detected vibration that is the slipping vibration (transverse vibration), adjustment of the y-axis direction width wy that is easy to measure is only necessary. As a result, according to the yaw rate sensor 10 of the present embodiment, it is possible to simplify the work of adjusting the resonance frequency of the excitation vibration and the resonance frequency of the detection vibration.

In this case, the resonance frequency fx of the longitudinal vibration and the sliding vibration (transverse vibration) are obtained even if the vibrator 12 is formed according to the length lx in the x-axis direction and the width wy in the y-axis direction determined at the design stage.
The resonance frequency fy of 1 has a certain degree of agreement. Therefore, it is sufficient to slightly adjust the width wy in the y-axis direction, and in some cases, the adjustment is not necessary.

Further, in the yaw rate sensor 10 of the present embodiment, the resonance frequency fx of the longitudinal vibration of the vibrating reed 18, which is the excitation vibration in the vibrator 12, and the resonance frequency fy of the sliding vibration (transverse vibration), which is the detected vibration, are matched. . For this reason, when the vibrating piece 18 causes a sliding vibration, a resonance phenomenon of vibration is brought about, the amplitude of the sliding vibration can be increased, and the bending displacement amount of the vibrating piece can be increased. Therefore, according to the yaw rate sensor 10 of the present embodiment, the yaw rate detection sensitivity can be improved.

Further, in the yaw rate sensor 10 of this embodiment, the left vibrating piece portion 18a of the vibrating piece 18 and the right vibrating piece portion 1 are provided.
The direction of longitudinal vibration in 8b was reversed, and the direction of sliding vibration caused in the left and right vibrating bars by the Coriolis force was also reversed. Therefore, in the yaw rate sensor 10, a disturbance that is not based on rotation around the z-axis, such as a lateral acceleration that acts on a vehicle equipped with the yaw rate sensor 10 due to a road surface gradient or the like, is indicated by a dotted line in FIG. , The left vibration piece 18a and the right vibration piece 18b
And are superimposed on the electric signals of the detectors 24 and 26 in opposite directions. Therefore, according to the yaw rate sensor 10 of the present embodiment, it is possible to cancel these disturbances and further improve the yaw rate detection sensitivity.

Next, another embodiment (second embodiment) according to the present invention will be described. In the second embodiment, the manner of supporting the yaw rate sensor 10 and the vibrator described above and the installation position of the detector for detecting vibration are different. In the following description, the same components as those of the yaw rate sensor 10 will be designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 4, which is a schematic perspective view, the yaw rate sensor 50 of the second embodiment has a vibrator 52 fixed and supported by a pair of fixed bodies 54 above and below the vibrator 52. The vibrator 52 includes a vibrating piece 58 located in the center of the vibrating piece 58, which is supported by a supporting body 56 on a fixed body 54, exciters 20 and 22 adhered to the end faces of both ends of the vibrating piece 58, and the vibrating piece 58. The detectors 54a and 54b and the detectors 57a and 57b bonded to the lower surface are provided. Then, in the yaw rate sensor 50, the vibrating piece 58 is formed by the exciters 20 and 22.
Is excited by longitudinal vibration in the x-axis direction, and the z-axis that is parallel to the upper and lower surfaces of the vibrating piece 58 and is orthogonal to the x-axis is the yaw rate axis.

The vibrating piece 58 formed by the exciters 20 and 22.
The state of excitation is the same as that of the yaw rate sensor 10.
Further, the detectors 54a and 54b and the detectors 57a and 57
Reference numeral b denotes a piezo element which is a piezoelectric element, and is the same as the yaw rate sensor 10 in that it produces an electric signal of an AC voltage according to expansion and contraction of the piezoelectric element.

Therefore, the yaw rate sensor 5 of the second embodiment is
At 0, the left and right vibrating bars 58 that sandwich the support 56
a, the right-side vibrating piece 58b is placed in a longitudinal vibration state in the x-axis direction, and when the rotational angular velocity ω acts around the z-axis, the left-side vibrating piece 58a and the right-side vibrating piece 58b are side views. As shown in FIG. 5, lateral vibration is caused along the y-axis direction. Then, the lateral vibration is detected by the detectors 54a and 54b and the detectors 57a and 57b to obtain the yaw rate.

On the other hand, even in the yaw rate sensor 50 of the second embodiment, the resonance frequency fx when the vibrating piece 58 vertically vibrates and the resonance frequency fy of lateral vibration are the vibrator 5
2 The total length 1x in the x-axis direction and the thickness ty in the y-axis direction of the vibrator 52 are adjusted. The x-axis direction length lx and the y-axis direction thickness ty of the vibrator 12 in the figure are exaggerated, and the ratios thereof do not reflect the actual dimensional ratio.

That is, the yaw rate sensor 5 of the second embodiment.
In the case of 0, the length 52 of the vibrator 52 as a whole in the x-axis direction and the thickness ty of the vibrator 52 in the y-axis direction are specified at the design stage to form the vibrator 52, and the resonance frequency fx of the longitudinal vibration is specified. To do. After that, the resonance frequency fy of the lateral vibration can be changed independently by adjusting the thickness ty of the vibrator 52 in the y-axis direction. Therefore, the resonance frequency fx of the longitudinal vibration and the resonance frequency fy of the lateral vibration can be changed.
Can be matched.

Therefore, the yaw rate sensor 50 of the present embodiment.
According to the above, according to
In adjusting the resonance frequency fx of the longitudinal vibration and the resonance frequency fy of the lateral vibration that is the detected vibration, it is only necessary to adjust the y-axis direction thickness ty, which is easy to measure. As a result, the yaw rate sensor 50 of the present embodiment can also simplify the work of adjusting the resonance frequency of the excitation vibration and the resonance frequency of the detection vibration.

Further, even in the yaw rate sensor 50 of this embodiment, a resonance phenomenon of vibration is brought about when the vibrating bar 58 causes lateral vibration by matching the resonance frequencies, and the yaw rate detection sensitivity can be improved. .

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment and can be implemented in various modes without departing from the scope of the present invention. Of course.

For example, in the present embodiment, the longitudinal vibration is excited in the vibrating piece to detect the lateral vibration, but the invention is not limited to this. That is, it is also possible to configure the vibrating element to excite lateral vibration (slip vibration) and detect longitudinal vibration.

Further, in this embodiment, the yaw rate sensor 1
Although a light alloy having 0 as an elanbar material was used, the present invention is not limited to this. That is, the vibrator 1 of the yaw rate sensor 10
The vibrating element 18 in 2 can be formed by etching a plate material (quartz substrate) of quartz which is a single crystal body. In this case, since the quartz crystal itself has a piezoelectric effect, the electrodes that constantly vibrate vertically in the x-axis direction and the electrodes for detecting lateral vibration may be formed in appropriate patterns.

Further, the yaw rate sensor 10 of the first embodiment.
In FIG. 1, the detector for detecting the lateral vibration caused in the vibrating piece 18 is attached to the side surface 19 of the vibrating piece 18 as shown in FIG.
It can also be provided in a and 19b. Further, in the yaw rate sensor 10 and the yaw rate sensor 50, the vibrating piece 18
Alternatively, the vibrating piece 58 has the left and right vibrating piece portions, but the vibrating piece may be configured to have one vibrating piece portion.

[0060]

As described in detail above, in the vibrator according to the first aspect of the invention, the vibrating piece of the vibrator is placed in a state of constant longitudinal vibration by the exciting means, and the longitudinal vibration is a lateral vibration which is a heterogeneous vibration. Vibration is detected and detected by the detecting means. Alternatively, the vibrating element is placed in a state of constant lateral vibration, and the longitudinal vibration, which is a vibration different from the lateral vibration, is detected and detected. Then, the resonance frequency of the longitudinal vibration that depends on the length of the entire vibrator along the longitudinal vibration direction, and the resonance frequency of the lateral vibration that depends on the width of the entire vibrator along the lateral vibration direction, It is possible to make them match by adjusting the length of the whole vibrator and the width of the whole vibrator. As a result, the vibrator according to the first aspect does not require complicated mass adjustment such as melting removal, so that the adjustment work of the resonance frequency of the excitation vibration and the resonance frequency of the detection vibration can be simplified.

In the yaw rate sensor according to the second aspect, it is possible to generate the Coriolis force due to the rotation of the vibrator by making the yaw rate axis orthogonal to the vibration directions of the longitudinal vibration and the lateral vibration of the vibrating element. And Then, the Coriolis force can cause lateral vibration in the resonator element. Therefore, since the resonator according to claim 1 has already adjusted the resonance frequency of the longitudinal vibration that is the excited vibration and the resonance frequency of the lateral vibration that is the detected vibration, the yaw rate sensor according to the claim 2 is characterized in that When it is caused, it is possible to resonate with the longitudinal vibration and to laterally vibrate with a large amplitude. As a result, according to the yaw rate sensor of the second aspect, it is possible to improve the yaw rate detection sensitivity by increasing the flexural displacement amount of the vibrating element due to the lateral vibration.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a yaw rate sensor 10 according to a first embodiment of the invention.

FIG. 2 is a plan view of a vibrator 12 in the yaw rate sensor 10.

FIG. 3 is an explanatory diagram illustrating a state of an output obtained from the yaw rate sensor 10.

FIG. 4 is a schematic configuration diagram of a main part of a yaw rate sensor 50 according to a second embodiment.

5 is a side view of a vibrator 52 in the yaw rate sensor 50. FIG.

[Explanation of symbols]

 10 ... Yaw rate sensor 12 ... Oscillator 14 ... Fixed body 18 ... Vibrating piece 18a ... Left vibrating piece part 18b ... Right vibrating piece part 20, 22 ... Exciter 24, 26 ... Detector 30 ... Excitation circuit 37 ... Detection side Circuit 38 ... Detection balance adjusting circuit 40 ... Amplification circuit 42 ... Synchronous detection circuit 44 ... Integrating circuit 46 ... Amplification output circuit 50 ... Yaw rate sensor 52 ... Vibrator 54 ... Fixed body 54a, 54b ... Exciter 57a, 57b ... Detector 58 Vibrating piece 58a ... Left vibrating piece 88b ... Right vibrating piece

Claims (2)

[Claims] 1. A vibrating element capable of longitudinal vibration in one direction and laterally vibrating in the other direction orthogonal to the one direction; and vibration in any one of the longitudinal vibration and the lateral vibration as excitation vibration. A vibrator, comprising: an exciting unit that excites the vibrating piece; and a detecting unit that detects a vibration state of a vibration different from the excited vibration among the longitudinal vibration and the lateral vibration in the vibrating piece. 2. A yaw rate sensor using the vibrator according to claim 1, wherein the vibrator according to claim 1 is arranged such that both the one direction and the other direction are orthogonal to a yaw rate axis, Excitation means for exciting the longitudinal vibration as excitation vibration in the vibrating piece, detection means for detecting a vibration state of the lateral vibration in the vibrating piece, and yaw rate calculation based on the vibration state detected by the detecting means. A yaw rate sensor, comprising: