JPH11325911A - Angular speed sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a short angular speed sensor for detecting rotational angle speed with high precision by reducing leakage of vibration and zero-point drift due to temperature fluctuation. SOLUTION: An excitation electrode is formed on a branch surface of a branch part A2. A detection electrode is formed on branch surface of branch parts A3 and A4. The formation position of the branch parts A3 and A4 is the antinode position of the branch part A1 at bending vibration in a tertiary mode. The excitation electrode is applied with AC voltage E for stretching vibration of the branch part A2 with amplitude in Y-axis direction. With the stretching vibration, the branch part A1 is brought to bending vibration, with amplitude in Y-axis direction, parallel to X-Y plane and the branch parts A3 and A4 is forced reciprocating movement in Y-axis direction parallel to the X-Y plane. When a vibrator element A rotates around a Z-axis, Coriolis force makes the branch parts A3 and A4 bending-vibrate with X-axis direction component, with a voltage signal es corresponding to the Coriolis force obtained from the detection electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to flexural vibration of a vibrator vibrating along a predetermined direction, for example, a vibrator element vibrating parallel to the Y-axis on an XY plane of orthogonal coordinates. The present invention relates to an angular velocity sensor that detects a rotational angular velocity by converting the angular velocity into a rotational angular velocity.

[0002]

2. Description of the Related Art A vibrator vibrating along a predetermined direction,
For example, when the vibrator vibrating along the X axis in the orthogonal coordinate axis plane (XY plane) rotates around the Y axis, the Coriolis force of the vibrator in the Z axis direction (perpendicular to the XY plane) Occurs. Since this Coriolis force is determined in proportion to the magnitude of the angular velocity, if the Coriolis force is directly measured as the amount of deflection displacement of the vibrator, directly by the piezoelectric effect of the piezoelectric element, capacitance change, etc. The magnitude of the rotational angular velocity acting around the Y axis of the child can be obtained. For this reason,
2. Description of the Related Art A vibrating vibrator is mounted on a vehicle, an aircraft, or the like as an angular velocity detecting element, and its running or flight trajectory is recorded, and yaw rate generated at the time of turning is detected.
Further, the angular velocity detecting element is mounted on a robot, and is applied to attitude control and the like.

FIG. 9 is a diagram showing a main part of a conventional angular velocity sensor using quartz. 9A is a plan view, FIG.
FIG. 9B is a diagram of FIG. 9A viewed from the E direction. In the figure, reference numeral 1 denotes a tuning-fork type vibrator element (quartz plate);
2-4 is an electrode plate for excitation, 3-1 to 3-4 are electrode plates for detecting angular velocity, and the electrode plates 2-1 to 2-4 for excitation are used as components of the excitation electrode 2 to detect angular velocity. Electrode plate 3-1
３−3-4 are constituent elements of the detection electrode 3. The excitation electrode plates 2-1 to 2-4 are connected to one leg 1-
1, electrode plates 3-1 to 3-3 for detection
-4 are formed on the left and right surfaces of the other leg portion 1-2 of the vibrator element 1. The legs 1-1 and 1-2 are connected to the legs 1
Spindle 1 having axis L parallel to -1 and 1-2
-3, the legs 1-1 and 1-2 and the main shaft 1
-3 is located on a common plane.

[0004] In this angular velocity sensor, FIG.
As shown in FIG. 2, the excitation electrode plates 2-1 and 2-3 are commonly connected to the terminal P1, and the excitation electrode plates 2-2 and 2 are connected.
-4 are commonly connected to a terminal P2.
2, an AC voltage (excitation vibration signal) e is applied.
For this reason, at one time, an electric field is generated in the middle leg 1-1 as shown by an arrow in FIG. 9B, and then an electric field in the opposite direction is generated. The leg 1-1 vibrates left and right (flexural vibration) in conjunction with the other leg 1-2.

Here, the vibration direction of the legs 1-1 and 1-2 is the X-axis direction, and the direction in the plane of the drawing perpendicular to the X-axis direction, that is, the direction of the axis L of the main shaft 1-3 is the Y-axis direction. This XY
When the direction orthogonal to the plane (the direction perpendicular to the plate surface of the transducer element 1) is the Z-axis direction, when the rotational angular velocity acts around the Y axis, that is, when the transducer element 1 rotates about the Y axis, Then, a vibration component in the Z-axis direction is generated by the Coriolis force, and the vibrator element 1 vibrates obliquely (bending vibration) with respect to the paper surface with the Z-axis direction component. Since the magnitude of the vibration component in the Z-axis direction is proportional to the Coriolis force, the other leg 1-2 of the vibrator element 1 has a magnitude proportional to the angular velocity in the direction of vibration due to the piezoelectric effect. The corresponding pole charge is generated.

As a result, the detection electrode plates 3-1 and 3-
4 is connected to a terminal P3 which is connected in common with an electrode plate 3 for detection.
An electric charge is generated between the terminal P4 connecting the terminals 2 and 3-3 in common, and a voltage signal es corresponding to the Coriolis force is obtained. From the magnitude of the voltage signal es, the magnitude of the rotational angular velocity acting around the Y axis can be known. The voltage signal es is basically obtained as a sine curve, and since the phase of the waveform of the voltage signal es changes according to the direction of rotation, the waveform of the voltage signal es and the waveform of the excitation vibration signal e (excitation waveform ), The direction of the rotational angular velocity can be known based on the lead and lag of the phase.

The amplitude of the excitation vibration signal e applied between the terminals P1 and P2 is kept constant by a temperature compensating circuit (not shown) even if the various constants and the vibration mode of the element change due to a temperature change. The amplitude is kept. Further, in response to the excitation vibration signal e applied between the terminals P1 and P2, the terminals P3 and P
4 is extremely small.

[0008]

However, X-Y
It is desirable that an excitation vibration is generated in a direction parallel to the plane and in the X-axis direction. However, in such a conventional angular velocity sensor, the element structure becomes asymmetric or the excitation electrode plate 2-
The arrangement of the elements 1 to 2-4 must be asymmetrical with respect to the vibration plane. As a result, the vibrator element 1 including the excitation electrode 2 and the detection electrode 3 (hereinafter, collectively referred to as a vibrator) is A phenomenon of tilting and vibrating with respect to the axial direction occurs.

That is, there is no problem as long as the element structures are well-balanced and the excitation electrode plates 2-1 to 2-4 are symmetrically arranged as shown in FIG. As a result, the electric field becomes asymmetric, and the vibrating direction of the vibrator is shifted by θ ° with respect to the X-axis direction as shown in FIG. Also, it is known that this deviation in the vibration direction (rotation of the excitation phase) is transmitted to the leg 1-2 where the detection electrode 3 is located, and also fluctuates due to a temperature change. The occurrence of a charge in the Z-axis direction component on the detection side electrode due to this phenomenon even in the stationary state is called “vibration leakage”. The charge generated by this "leak of vibration" fluctuates due to external factors such as temperature changes.
The amount of charge generated in the Z-axis direction of the vibrator changes regardless of the Coriolis force, and an error occurs in the detected rotational angular velocity.

FIG. 1 shows a situation where an error occurs in the rotational angular velocity.
1 will be described. Now, as an ideal state, it is assumed that the vibrator is vibrating in the X-axis direction (see FIG. 11A). In this case, the vibrator sets its amplitude to W1 and X
Vibrating in the axial direction (θ = 0 °). At this time, when the rotational angular velocity ω1 acts clockwise on the Y-axis of the vibrator, the Coriolis force F1 in the Z-axis direction of the vibrator is generated by the rotational angular velocity ω1.
Occurs. Therefore, the vibrator vibrates while changing the phase from the X axis by θ1.
A voltage e _s1 proportional to 1 is generated and can be detected as the rotational angular velocity ω1.

On the other hand, as shown in FIG.
If the excitation phase has already been rotated by θ °, due to vibration leakage (ie, if the vibrator is vibrating at θ1 with respect to the X-axis direction with its amplitude being W1), the detection electrode 3 If the null voltage e _sN has already been generated and the clockwise rotation angular velocity ω1 acts on the vibrator around the Y axis as described above, the voltage e _s2 (= e _s1 co is proportional to the Coriolis force F1)
s (θ1)) is added, and it looks as if a larger angular velocity has occurred. Also, the amount of vibration leakage
Since the modulus of elasticity and dimensions of the structure change due to temperature changes, its vibration mode changes, and it has temperature dependence.
As a result, _esN is not determined, so that the detection voltage becomes unstable and accurate measurement cannot be performed.

In the conventional angular velocity sensor, the Y axis is set in the height direction based on the vibration mode and the Coriolis force generation mechanism.
The rotational angular velocity acting around the axis is detected. That is, in order to detect the Coriolis force, the conventional angular velocity sensor needs to be used while standing in the Y-axis direction, and becomes large in the height direction, and cannot be miniaturized (thinned).

In addition, in the conventional angular velocity sensor, since the frequency temperature characteristics (temperature characteristics) of the excitation side and the detection side are different, the frequency difference between the excitation side frequency f _XT and the detection side frequency f _ZT at each temperature is the temperature. , The degree of coupling fluctuates,
As a result, the Q value changes, so that a change in the detected charge amount (a change in sensitivity) occurs, which is one of the causes of the zero point drift. That is, when the angular velocity sensor is stationary and there is no zero point drift, the displayed measurement position has a predetermined reference value (see FIG. 12). That is, with the reference value as a starting point, for example, the display value increases in a right rotation, and decreases in a left rotation. This reference value is called a zero point. Zero point drift refers to a phenomenon in which the voltage at the zero point fluctuates due to external disturbance (disturbance due to an external factor) such as a temperature change despite the stationary state. FIG. 13 is an equivalent circuit of a piezoelectric vibration type angular velocity sensor (hereinafter, referred to as PVG). In order to improve the sensitivity of PVG, the excitation side frequency fx and the detection side frequency f
It is desirable that z be equal. However, as fx approaches fz, a degeneration phenomenon of the vibration mode occurs, and the original (in principle) measurement becomes impossible.

Therefore, to the extent that there is no influence of the degeneration phenomenon,
It is set to isolate two frequencies and separate the two modes. Therefore, the two modes are set with a frequency difference (ΔF = | fx−fz |). By the way, it is known that the magnitude of ΔF affects the degree of coupling between the two modes, and this changes the Q value and changes the sensitivity. Although the value of ΔF is a value adjusted at a specific temperature (for example, normal temperature), the fact that the fluctuation of ΔF also occurs due to a temperature change will be described based on the difference in temperature between the two vibration modes.

A conventional angular velocity sensor (bend x) shown in FIG.
In both the excitation and the bending z detection, the vibration mode is bending vibration, but the temperature characteristics are different due to the properties of the material. FIG.
An example is shown below. In the figure, Tx is the temperature characteristic on the excitation side, Tz is the temperature characteristic on the detection side, and the two modes are set to be separated by ΔF ₀ at room temperature (RT).
In this case, the peak temperature T _0t (T _0x ,
Since T _0z ) does not match, the value of ΔF fluctuates with temperature fluctuation in the two modes. Therefore, the change in ΔF due to the temperature change causes the output to fluctuate despite the fact that the rotational angular velocity is not acting, and it is as if the rotational angular velocity is acting. Due to the zero point drift due to the temperature fluctuation, the detection voltage becomes unstable, and accurate measurement cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to reduce the leakage of vibration (rotation of the excitation phase), the zero point drift due to temperature fluctuation, and the rotation. An object of the present invention is to provide a thin angular velocity sensor in a height direction capable of detecting an angular velocity with high accuracy.

[0017]

In order to achieve such an object, a first invention (an invention according to claim 1) comprises a first branch portion whose both ends are supported and fixed, and a first branch portion. A second branch extending from a branch surface at a substantially central portion of the branch in a direction perpendicular to the branch surface and having its tip supported and fixed; and between one end of the first branch and the center. And a third branch and a fourth branch extending from a branch surface between the other end and the center in a direction parallel to the longitudinal direction of the second branch. A transducer element having a direction parallel to the longitudinal direction of the X-axis direction, a direction parallel to the longitudinal direction of the second branch portion as a Y-axis direction, and a direction parallel to a direction orthogonal to the XY plane as a Z-axis direction. And an excitation electrode formed on a branch surface of the second branch portion, the second branch portion is subjected to expansion and contraction vibration in the Y-axis direction by receiving an AC voltage, and the excited expansion and contraction vibration is generated. Therefore, the first branch portion is bent and vibrated with an amplitude in the Y-axis direction in parallel with the XY plane, and the third and fourth branch portions are further bent by the bending vibration in the Y-axis direction in parallel with the XY plane. An excitation structure that repeatedly moves in the direction
When the third branch and the fourth branch are repeatedly moved in the Y-axis direction parallel to the XY plane by the detection electrodes formed on the branch surfaces of the branch and the fourth branch. When the transducer element rotates around the Z axis, the third branch and the fourth
And a detection structure for taking out charges generated by bending vibration caused by an X-axis direction component caused by inertia. According to the present invention, when an AC voltage is applied to the excitation electrode, the second branch portion expands and contracts in the Y-axis direction, and the first branch portion moves in the Y-axis direction parallel to the XY plane due to the expansion and contraction vibration. Bending vibration occurs with an amplitude.
And the fourth branch portion repeatedly move in the Y-axis direction in parallel with the XY plane. In this state, when a rotational angular velocity acts about the Z axis, Coriolis force acts in the X axis direction orthogonal to the Y axis, and as a result, the third branch and the fourth branch have components in the X axis direction. It bends and vibrates. Then, the electric charge generated by the bending vibration is extracted from the detection electrode, and the magnitude of the rotational angular velocity acting around the Z axis is detected based on the amount of the extracted electric charge.

According to the second invention (the invention according to claim 2), the first branch portion whose both ends are supported and fixed, and the branch surface substantially at the center of the first branch portion are orthogonal to the branch surface. Second and third extending in one direction and the other direction and having their tips supported and fixed.
And a branch surface between one end and the center of the first branch and a branch surface between the other end and the center of the first branch are parallel to the longitudinal direction of the second and third branches. A fourth branch and a fifth branch extending in the direction, the direction parallel to the longitudinal direction of the first branch is defined as the X-axis direction, and the direction parallel to the longitudinal direction of the second and third branches. A vibrator element having a direction parallel to the Y-axis direction and a direction parallel to the direction orthogonal to the XY plane, the second branch portion and the third branch portion;
The second branch and the third branch are stretched and vibrated in the Y-axis direction by the application of an AC voltage by the excitation electrode formed on the branch surface of the branch. Is vibrated with amplitude in the Y-axis direction parallel to the XY plane, and the fourth vibration and the fifth branch are further repeated in the Y-axis direction parallel to the XY plane by the bending vibration. The fourth branch portion and the fifth branch portion are formed by the excitation structure to be moved and the detection electrodes formed on the branch surfaces of the fourth branch portion and the fifth branch portion.
When the vibrator element is rotated around the Z-axis while the vibrating element vibrates with an amplitude in the Y-axis direction parallel to the XY plane, the fourth and fifth bifurcations have inertia. And a detection structure for taking out charges generated by the bending vibration caused by the X-axis direction component caused by the above. According to this invention, when an AC voltage is applied to the excitation electrode, the second and third
Vibrates in the Y-axis direction, and the first vibrator bends and vibrates with amplitude in the Y-axis direction in parallel with the XY plane by the vibrating vibration. The branch portion 5 repeatedly moves in the Y-axis direction parallel to the XY plane. In this state, when a rotational angular velocity acts around the Z-axis, Coriolis force acts in the X-axis direction orthogonal to the Y-axis. As a result, the fourth branch and the fifth branch have an X-axis component. It bends and vibrates. Then, the electric charge generated by the bending vibration is extracted from the detection electrode, and the magnitude of the rotational angular velocity acting around the Z axis is detected based on the amount of the extracted electric charge.

The third invention (the invention according to claim 3) is characterized in that the first branch portion whose both ends are supported and fixed, and the branch surface substantially at the center of the first branch portion are orthogonal to the branch surface. Second and third extending in one direction and the other direction and having their tips supported and fixed.
A fourth branch extending in one direction and the other direction parallel to the longitudinal direction of the second and third branches from a branch surface between one end and the center of the first branch. A second branch from the branch surface between the branch and the fifth branch and the other end and the center of the first branch;
A sixth branch and a seventh branch extending in one direction and the other direction parallel to the longitudinal direction of the third branch, wherein the direction parallel to the longitudinal direction of the first branch is the X-axis direction. A vibrator element having a direction parallel to the longitudinal direction of the second and third branch portions as the Y-axis direction and a direction parallel to the direction orthogonal to the XY plane as the Z-axis direction; An AC voltage is applied to the second branch and the third branch in the Y-axis direction by the excitation electrode formed on the branch surface of the third branch, and the second branch and the third branch are stretched and vibrated in the Y-axis direction. The first branch is bent and vibrated with an amplitude in the Y-axis direction in parallel to the XY plane, and the fourth vibration, the fifth branch, the sixth branch, and the seventh branch are further caused by the bending vibration.
And an excitation structure for repetitively moving the branches in the Y-axis direction parallel to the XY plane, and formed on the branch surfaces of the fourth, fifth, sixth, and seventh branches. When the fourth branch, the fifth branch, the sixth branch, and the seventh branch are repeatedly moved in the Y-axis direction in parallel with the XY plane by the detected detection electrode, When the slave element rotates around the Z axis, the fourth
, A fifth branch, a sixth branch, and a seventh branch are provided with a detection structure for extracting electric charge generated by bending vibration due to an X-axis direction component generated by inertia. According to this invention, when an AC voltage is applied to the excitation electrode, the second and third branches vibrate and contract in the Y-axis direction. Bending vibration occurs with amplitude in the axial direction.
X, the fifth branch, the sixth branch and the seventh branch are X
-Repeatedly move in the Y axis direction parallel to the Y plane. In this state, when a rotational angular velocity acts around the Z axis, Coriolis force acts in the X axis direction orthogonal to the Y axis, and as a result, the fourth, fifth, and sixth branches are formed. And the seventh branch portion bends and vibrates with the component in the X-axis direction. Then, the electric charge generated by the bending vibration is extracted from the detection electrode, and the magnitude of the rotational angular velocity acting around the Z axis is detected based on the amount of the extracted electric charge.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. [Basic Principle: First Invention] FIG. 1A is a diagram for explaining the basic principle of the present invention. In the figure, A is a vibrator element, the material of which is metal, ceramics, single crystal, etc.
Any of them may be used, but here, the explanation will be made using a quartz plate. The vibrator element A includes a first branch A1, a second branch A2, a third branch A3, and a fourth branch A4. Both ends of the first branch A1 are supported and fixed. Second branch A
Numeral 2 extends from a branch surface at a substantially central portion of the first branch portion A1 in a direction orthogonal to the branch surface, and the tip thereof is supported and fixed. The third branch A3 extends in a direction parallel to the longitudinal direction of the second branch A2 from a branch surface between one end and the center of the first branch A1. The fourth branch A4 extends from a branch surface between the other end of the first branch A1 and the central portion in a direction parallel to the longitudinal direction of the second branch A2. The branches A1 to A4 are located on a common plane.

In the vibrator element A, the first branch A
1 is the X-axis direction, the second branch portion A2
Is defined as a Y-axis direction, and a direction parallel to a direction orthogonal to the XY plane is defined as a Z-axis direction. FIG.
In FIG. 1A, the third branch A3 and the fourth branch A4 extend toward the second branch A2, but as shown in FIG. 1B, the second branch A2 is It may be configured to extend to the opposite side.

With respect to the vibrator element A thus configured, the opposing branch surfaces A21 and A2 of the second branch portion A2 are provided.
An excitation electrode (not shown) is formed on 22. The left and right branch surfaces A31 and A32, the front and back branch surfaces A33 and A34, and the fourth branch portion A4 of the third branch portion A3.
The detection electrodes (not shown) are formed on the left and right branch surfaces A41 and A42 and the front and back branch surfaces A43 and A44. Then, an AC voltage (excitation vibration signal) e is applied to the excitation electrode formed on the second branch portion A2 to cause the second branch portion A2 to expand and contract in the Y-axis direction. Due to the excited stretching vibration, the first branch portion A1 bends and vibrates in the third mode (third bending mode) with an amplitude in the Y-axis direction parallel to the XY plane.

In this case, the formation position of the third branch portion A3 and the fourth branch portion A4 is the antinode position in bending vibration of the first branch portion A1 in the third mode. That is, nodes at the time of bending vibration of the first branch A1 in the third mode are N1,
If N2, one end of the first branch A1 and the node N1
Is the first antinode position H1 and the first branch A1
The center position between the other end of the first and the node N2 is the second antinode position H2.
A third branch A3 is formed at the first antinode position H1, and a fourth branch A4 is formed at the second antinode position H2. Specifically, when the branch A1 is vibrated in the tertiary mode, when the length of the first branch A1 is set to “1”, almost one end of the first branch A1 is moved. The third branch A3 may be formed at the position of "0.2", and the fourth branch A4 may be formed at the position of approximately "0.8". Also, when A1 is vibrating in the odd mode, the "antinode" portion of the vibration vibrates in phase, so that A3 and A4 may be formed in this portion, but the large amplitude can be obtained in the tertiary mode. The third mode is described below.

When the first branch portion A1 bends and vibrates in the third mode with an amplitude in the Y-axis direction parallel to the XY plane,
And the fourth branch A4 are formed at the antinode positions H1 and H2 of the first branch A1, and thus repeatedly move in the Y-axis direction parallel to the XY plane.

Here, when the vibrator element A rotates around the Z-axis, a vibration component in the X-axis direction is generated in the vibrator element A by Coriolis force, and the third branch A3 and the fourth branch A4
Undergoes bending vibration with an X-axis direction component. Due to the bending vibration caused by the X-axis direction component, charges are generated in the third branch portion A3 and the fourth branch portion A4 in a form proportional to the rotational angular velocity and in a form in which the phase varies depending on the rotation direction. A voltage signal es corresponding to the Coriolis force is obtained from the detection electrode. From the magnitude of the voltage signal es, the magnitude of the rotational angular velocity acting around the Z axis can be known. Further, by comparing the phase of the waveform of the voltage signal es with the phase of the waveform of the excitation vibration signal e, it is possible to know the direction of the rotational angular velocity based on the lead and lag of the phase.

According to this basic principle, the first branch portion A1 is driven by providing an excitation electrode on the second branch portion A2, that is, by causing the second branch portion A2 to expand and contract in the Y-axis direction. The bending vibration of the first branch portion A1 is caused by the bending vibration in the Y-axis direction in parallel with the XY plane.
Of the third branch A3 and the fourth branch A4 are induced in the Y-axis direction parallel to the XY plane of the third branch A3 and the fourth branch A4. Is a vibration having only a component in the Y-axis direction that is purely parallel to the XY plane. Compared with a conventional angular velocity sensor in which the excitation electrode 2 is provided on the leg 1-1 shown in FIG. Vibration leakage (rotation of the excitation phase) can be reduced.

In this case, FIG. 4 shows the temperature characteristic Ty on the excitation side.
And the temperature characteristic Tx on the detection side, the temperature characteristic apex temperature T _0t (T _0y , T _0x ) of the two modes and the two-dimensional curve 2
Since the order coefficients match, ΔF is constant even if there is a temperature fluctuation, and since there is no output fluctuation, zero point drift due to temperature fluctuation is prevented. Excellent) angular velocity sensor can be obtained.

In this case, since the Z axis of the transducer element A is set in the height direction and the rotational angular velocity acting around the Z axis is detected, the thickness in the height direction can be reduced. .

[Application Example 1: Second Invention] According to the basic principle described above, only one branch is driven. On the other hand, in the application example 1, as shown in FIG. 2A, two branches are driven. That is, as transducer element B, branches B1, B2 corresponding to branches A1, A2, A3, A4 in FIG.
Branch portions B3 are provided in addition to 2, B4 and B5. in this case,
The branch portion B2 extends from a plate surface at a substantially central portion of the branch portion B1 in one direction perpendicular to the plate surface, and its tip is supported and fixed, whereas the branch portion B3 is substantially at the center of the branch portion B1. The portion extends from the plate surface of the portion in the other direction perpendicular to the plate surface, and its tip is supported and fixed. An excitation electrode is also formed on the branch B3 in the same manner as the branch B2, and the branches B2 and B3 are reversed in the Y-axis direction (when the branch B2 expands, the branch B3 contracts. (Alternately so that the opposite occurs). In FIG. 2A, the branch portions B4 and B5 extend to the branch portion B2 side, but may have a configuration extending to the branch portion B3 side as shown in FIG. 2B.

[Application example 2: Third invention] Application example 1 described above
In this example, two branches were used for detection. On the other hand, application example 2
Then, as shown in FIG. 3, there are four detection branches.
That is, as the vibrator element C, the branch B in FIG.
Branches C1, C corresponding to 1, B2, B3, B4, B5
Branches C5 and C7 are provided in addition to 2, C4, C4 and C6. In this case, the branches C4 and C6 are connected to the branches C2 and C3.
While extending in one direction parallel to the longitudinal direction of
The branches C5 and C7 extend in the other direction parallel to the longitudinal direction of the branches C2 and C3. Then, the branch portions C5 and C7
Similarly, the detection electrodes are formed in the same manner as the branch portions C4 and C6.

[Embodiment 1] FIG. 5 is a view showing a main part of an angular velocity sensor manufactured based on the above-described basic principle (FIG. 1A). FIG. 5A is a plan view and FIG. (B) is the figure which looked at the figure (a) from the back side.

In FIG. 5, reference numeral 4 denotes a vibrator element (quartz plate), 4-1 denotes a first branch, 4-2 denotes a second branch, and 4-
3 is a third branch, 4-4 is a fourth branch, and 4-5 is an outer frame. The first branch 4-1 has both ends 4-1a, 4-1b.
Is connected to the outer frame 4-5. The second branch portion 4-2 extends from the branch surface 4-1d of the approximately central portion 4-1c of the first branch portion 4-1 in a direction orthogonal to the branch surface 4-1d.
2a is connected to the outer frame 4-5.

The third branch 4-3 is a branch surface 4-1 between one end 4-1a and the center 4-1c of the first branch 4-1.
d extends in a direction parallel to the longitudinal direction of the second branch portion 4-2. The fourth branch 4-4 is a branch surface 4-1d between the other end 4-1b and the center 4-1c of the first branch 4-1.
Extends in a direction parallel to the longitudinal direction of the second branch portion 4-2. In this case, the direction parallel to the longitudinal direction of the first branch 4-1 is the X-axis direction, the direction parallel to the longitudinal direction of the second branch 4-2 is the Y-axis direction, and is orthogonal to the XY plane. A direction parallel to the direction is defined as a Z-axis direction.

With respect to the vibrator element 4 configured as described above, the left and right branch surfaces 4-2 of the second branch portion 4-2 facing each other.
Excitation electrodes 5 (5-1, 5-2) are formed on b and 4-2c. That is, the branch surface 4-2 of the second branch portion 4-2.
b, an excitation electrode plate 5-1 is formed on a branch surface 4-2c opposed to the branch surface 4-2b.

The electrode plates 6-1 and 6-2 for detection are provided on the left and right branch surfaces 4-3a and 4-3b facing the third branch portion 4-3, and the front and back branch surfaces 4-3c and 4-3c. The detection electrode plates 6-3 and 6-4 are formed in 4-3d. In addition, electrode plates 7-1 and 7-2 for detection are provided on the left and right branch surfaces 4-4a and 4-4b facing the fourth branch portion 4-4, respectively.
Electrode plates 7 for detection are provided on the front and back branch surfaces 4-4c and 4-4d.
-3 and 7-4.

FIG. 6 is a connection diagram showing the connection relationship of each electrode in FIG. 5 for easy understanding, and is a diagram showing the connection relationship of each electrode in a sectional view taken along the line II in FIG. 5 (a). . That is, in this angular velocity sensor, the excitation electrode plate 5-1 is connected to the terminal T1, and the excitation electrode plate 5-1 is connected to the terminal T1.
-2 is connected to the terminal T2. The detection electrode plates 6-1 and 6-2, 7-1 and 7-2 are commonly connected to the terminal T3, and the detection electrode plates 6-3, 6-4, 7-3 and 7 are connected.
-4 is commonly connected to the terminal T4.

Although the thickness of the electrode pattern is increased in FIG. 5 in order to show how the lead electrodes are routed in the vibrator element 4, a thin film is actually formed by sputtering or vapor deposition. However, when a material such as a constant elastic metal (for example, Elinvar) is used, a piezoelectric ceramic plate processed into a thin piece may be attached.

The formation positions of the third branch portion 4-3 and the fourth branch portion 4-4 are antinode positions for the first branch portion A1 in bending vibration in the third mode. That is, when vibrating in the third mode, when the length of the first branch 4-1 is set to “1”, one end 4-1 of the first branch 4-1 is set.
The third branch portion 4-3 is formed at a position approximately "0.2" from the position a, and the fourth branch portion 4-4 is formed at a position approximately "0.8".

[Detection Operation] An AC voltage (excitation vibration signal) e is applied between the terminals T1 and T2. 6 between the electrode plates 5-1 and 5-2 of the excitation electrode 5 when there is.
An electric field is generated as indicated by an arrow inside, and then an electric field in the opposite direction is generated, so that the second branch portion 4-2 expands and contracts in the Y-axis direction. The first branch portion 4-1 is generated by the stretching vibration.
Vibrates in the tertiary mode (third bending mode) with amplitude in the Y-axis direction parallel to the XY plane. The third branch portion 4-3 and the fourth branch portion 4-4 repeatedly move in the Y-axis direction in parallel with the XY plane by the bending vibration in the third mode.

When the vibrator element 4 rotates around the Z axis, a vibrating component in the X-axis direction is generated in the vibrator element 4 by Coriolis force, and the third branch 4-3 and the fourth branch Part 4
-4 undergoes bending vibration with the X-axis direction component. Due to the bending vibration due to the X-axis direction component, the third branch portion 4-3 and the fourth branch portion 4-4 change the electrode plate (6) in such a manner that the phase varies in the direction of rotation with a magnitude proportional to the rotational angular velocity. -1),
(6-2)-(6-3), (6-4), (7-1),
A corresponding charge is generated between (7-2)-(7-3) and (7-4). Thereby, the electrode plates 6-1 and 6
−2, 7-1 and 7-2 are commonly connected to terminal T3 and electrode plates 6-3, 6-4, 7-3 and 7-4 are commonly connected to terminal T4. A corresponding voltage signal es is obtained.

From the magnitude of the voltage signal es, the magnitude of the rotational angular velocity acting around the Y axis can be known. Further, by comparing the phase of the waveform of the voltage signal es with the phase of the waveform of the excitation vibration signal e, it is possible to know the direction of the rotational angular velocity based on the lead and lag of the phase.

[Embodiment 2] FIG. 7 shows an application example 2 described above.
4A and 4B are diagrams illustrating a main part of an angular velocity sensor manufactured based on (FIG. 3), wherein FIG. 3A is a plan view and FIG. 3B is a diagram of FIG.

In FIG. 7, 8 is a vibrator element (quartz plate), 8-1 is a first branch, 8-2 is a second branch, and 8-
3 is a third branch, 8-4 is a fourth branch, 8-5 is a fifth branch, 8-6 is a sixth branch, 8-7 is a seventh branch, 8-
8 is an outer frame. The first branch 8-1 has both ends 8-1.
a, 8-1b are connected to the outer frame 8-8. The second branch portion 8-2 extends from the branch surface 8-1d of the substantially central portion 8-1c of the first branch portion 8-1 in one direction perpendicular to the branch surface 8-1d, and has a tip 8-2a. Is connected to the outer frame 8-8. The third branch portion 8-3 is substantially the center portion 8-1 of the first branch portion 8-1.
c extends in the other direction perpendicular to the branch surface 8-1e from the branch surface 8-1e, and a tip 8-3a thereof is connected to the outer frame 8-8.

The fourth branch 8-4 is a branch surface 8-1 between one end 8-1a and the center 8-1c of the first branch 8-1.
d extends in one direction parallel to the longitudinal direction of the second branch portion 8-2 and the third branch portion 8-3. The sixth branch 8-6 includes the other end 8-1b and the center 8-1c of the first branch 8-1.
And extends in one direction parallel to the longitudinal direction of the second branch portion 8-2 and the third branch portion 8-3 from the branch surface 8-1d.

The fifth branch 8-5 is a branch surface 8-1 between one end 8-1a and the center 8-1c of the first branch 8-1.
e extends in the other direction parallel to the longitudinal direction of the second branch portion 8-2 and the third branch portion 8-3. The seventh branch 8-7 includes the other end 8-1b and the center 8-1c of the first branch 8-1.
And extends in the other direction parallel to the longitudinal direction of the second branch portion 8-2 and the third branch portion 8-3 from the branch surface 8-1e. In this case, the direction parallel to the longitudinal direction of the first branch portion 8-1 is X
An axial direction, a direction parallel to the longitudinal direction of the second branch portion 8-2 and the third branch portion 8-3 is a Y-axis direction, and a direction parallel to a direction orthogonal to the XY plane is a Z-axis direction. .

With respect to the vibrator element 8 configured as described above, the left and right branch surfaces 8-2 of the second branch portion 8-2 facing each other.
Excitation electrodes 9 (9-1, 9-2) are formed on b and 8-2c. That is, the branch surface 8-2 of the second branch portion 8-2
An electrode plate 9-1 for excitation is formed at b, and an electrode plate 9-2 for excitation is formed at a branch surface 8-2c opposed to the branch surface 8-2b. Also, the left and right branch surfaces 8-
Excitation electrodes 10 (10-1, 10-
2) is formed. That is, the electrode plate 10-1 for excitation is provided on the branch surface 8-3b of the third branch portion 8-3.
Electrode plate 10-2 for excitation is provided on branch surface 8-3c facing 3b.
Is formed.

The left and right branch surfaces 8-4a and 8-4b of the fourth branch portion 8-4 oppose each other.
And 11-2 are replaced with front and back branch surfaces 8-4c and 8-4d.
Are formed with detection electrode plates 11-3 and 11-4. Moreover, the left and right branch surfaces 8- of the fifth branch portion 8-5 facing each other.
5a and 8-5b have electrode plates 13-1 and 1 for detection.
3-2, the detection electrode plates 13-3 and 13-4 are formed on the front and back branch surfaces 8-5c and 8-4d.

The left and right branch surfaces 8-6a and 8-6b of the sixth branch portion 8-6 oppose each other.
And 12-2 are replaced with front and back branch surfaces 8-6c and 8-6d.
Are formed with detection electrode plates 12-3 and 12-4. Further, the left and right branch surfaces 8- of the seventh branch portion 8-7 facing each other.
7a and 8-7b have electrode plates 14-1 and 1 for detection.
4-2, detection electrode plates 14-3 and 14-4 are formed on the front and back branch surfaces 8-7c and 8-7d.

FIG. 8 is a connection diagram showing the connection relationship of each electrode in FIG. 6 for easy understanding. FIG. 8A shows FIG.
FIG. 8A is a diagram showing a connection relationship of each electrode in a cross-sectional view taken along the line II-II in FIG. 8A, and FIG.
FIG. 3 is a diagram showing a connection relationship of each electrode in a sectional view taken along a line III.

That is, in this angular velocity sensor, the excitation electrode plate 9-1 is connected to the terminal T1, 9-2 is connected to the terminal T2, and 1
0-1 is connected to T3 and 10-2 is connected to T4. Here, T1 and T3, and T2 and T4 have the same polarity, and are connected outside the element due to wiring to form two terminals.

The detection electrode plates 11-1 and 11-
2, 12-1, 12-2, 13-3, 13-4, 14-
Reference numerals 3 and 14-4 are commonly connected to the terminal T5, and are connected to the detection electrode plates 11-3, 11-4, 12-3, 12-4 and 13-.
1, 13-2, 14-1, and 14-2 are commonly connected and form two terminals as a terminal T6.

In FIG. 7, the thickness of the electrode pattern is increased in order to show how the lead electrodes are routed in the vibrator element 8, but a thin film is actually formed by sputtering or vapor deposition. However, when a material such as a constant elastic metal (for example, Elinvar) is used, a piezoelectric ceramic plate processed into a thin piece may be attached.

The positions where the fourth branch portion 8-4 and the sixth branch portion 8-6 are formed are antinode positions at the time of bending vibration of the first branch portion 8-1 in the third mode. . That is, the first
When the length of the first branch 8-1 is set to "1" when the branch 8-1 is vibrated in the tertiary mode, one end 8-1 of the first branch 8-1 A fourth branch portion 8-4 is formed at a position approximately "0.2" from 1a, and a sixth branch portion 8-6 is formed at a position approximately "0.8".

The position where the fifth branch portion 8-5 and the seventh branch portion 8-7 are formed is the antinode position of the first branch portion 8-1 at the time of bending vibration in the third mode. . That is, the first
When the length of the first branch 8-1 is set to "1" when the branch 8-1 is vibrated in the tertiary mode, one end 8-1 of the first branch 8-1 is vibrated. A fifth branch portion 8-5 is formed at a position approximately "0.2" from 1a, and a seventh branch portion 8-7 is formed at a position approximately "0.8".

[Detection Operation] An AC voltage (excitation vibration signal) e is applied between the terminals T1 and T2 and between the terminals T3 and T4. Thereby, the electrode plates 9-1 and 9 of the excitation electrode 9 are formed.
-2 and the electrode plates 10-1 and 10 of the excitation electrode 10
In some cases, an electric field is generated as shown by the arrows in FIGS. 8A and 8B, and then an electric field in the opposite direction is generated. The second and third branches 8-3 are in the opposite phase (the branches 8-3 contract when the branches 8-2 expand, and then alternately so as to be in the opposite direction), and expand and contract in the Y-axis direction. I do. Due to the stretching vibration, the first branch portion 8-1 bends and vibrates in the tertiary mode (third bending mode) with an amplitude in the Y-axis direction parallel to the XY plane. The fourth branch portion 8-4, the fifth branch portion 8-5, and the sixth branch portion are caused by the bending vibration in the third mode.
The branch portion 8-6 and the seventh branch portion 8-7 repeatedly move in the Y-axis direction in parallel with the XY plane.

Here, when the vibrator element 8 rotates around the Z-axis, a vibration component in the X-axis direction is generated in the vibrator element 8 by Coriolis force, and the fourth branch portion 8-4 and the fifth branch portion are formed. Part 8-
5, the sixth branch portion 8-6 and the seventh branch portion 8-7 vibrate flexibly with an X-axis direction component. Due to the bending vibration having the X-axis direction component, the fourth branch portion 8-4 and the fifth branch portion 8-
5, the electrode plates (11-1) and (11-2) are provided on the sixth branch portion 8-6 and the seventh branch portion 8-7 in such a manner that the phase varies depending on the rotation direction with a magnitude proportional to the rotational angular velocity. ) And (11-
3), (11-4), (12-1), (12-2) and (12-3), (12-4), (13-1), (13-
2) and (13-3), (13-4), (14-1),
A corresponding charge is generated between (14-2), (14-3), and (14-4).

Thus, the electrode plates 11-1, 11-2,
12-1, 12-2, 13-3, 13-4, 14-3,
14-4 and a terminal T5 commonly connected to the electrode plate 11-3;
11-4, 12-3, 12-4, 13-1, 13-2,
An AC voltage signal es corresponding to the Coriolis force is obtained between the terminal T6 and the terminal T6 to which the terminals 14-1 and 14-2 are commonly connected.

From the magnitude of the voltage signal es, the magnitude of the rotational angular velocity acting around the Z axis can be known. Further, by comparing the phase of the waveform of the voltage signal es with the phase of the waveform of the excitation vibration signal e, it is possible to know the direction of the rotational angular velocity based on the lead and lag of the phase.

[0059]

As apparent from the above description, according to the present invention, as represented by the first invention, the first branch is expanded and contracted in the Y-axis direction to thereby provide the first branch. Part is vibrated with amplitude in the Y-axis direction parallel to the XY plane, and the bending vibration of the first branch part causes the Y-axis of the third branch part and the fourth branch part to be parallel to the XY plane. Since the repetitive movement in the direction is induced, the X-axis component of the induced vibration of the third branch and the fourth branch is extremely small, and the null voltage on the detection side is reduced in the state where the rotational movement does not act. Infinitely zero, that is, leakage of vibration (excitation phase rotation)
And the rotational angular velocity can be detected with high accuracy. Further, according to the present invention, the temperature characteristic on the excitation side and the temperature characteristic on the detection side have the same T _0t of the apex temperature characteristic of the two vibration modes and the quadratic coefficient of the quadratic curve. Even if there is a fluctuation, ΔF is constant, and there is no output fluctuation. Therefore, zero point drift due to temperature fluctuation is prevented, and as a result, an angular velocity sensor with excellent temperature characteristics (excellent in temperature change) can be obtained. . Further, according to the present invention, the Z-axis of the vibrator element is set to the height direction, and the rotational angular velocity acting around the Z-axis is detected, so that the thickness in the height direction can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a basic principle (first invention) of the present invention.

FIG. 2 is a diagram illustrating an application example 1 (second invention) of the present invention.

FIG. 3 is a diagram illustrating an application example 2 (third invention) of the present invention.

FIG. 4 is a diagram showing a temperature characteristic Ty on an excitation side and a temperature characteristic Tx on a detection side in the present invention.

FIG. 5 is a diagram showing a main part (Embodiment 1) of the angular velocity sensor manufactured based on the basic principle.

FIG. 6 is a connection diagram showing a connection relationship of each electrode in FIG. 5 for easy understanding.

FIG. 7 is a diagram illustrating a main part (Embodiment 2) of an angular velocity sensor manufactured based on Application Example 3.

FIG. 8 is a connection diagram showing the connection relationship of each electrode in FIG. 7 for easy understanding.

FIG. 9 is a diagram showing a main part of a conventional angular velocity sensor.

FIG. 10 is a diagram illustrating rotation of an excitation phase in the angular velocity sensor.

FIG. 11 is a diagram illustrating a situation where an error occurs in a rotational angular velocity detected when the excitation phase rotates by θ ゜ in the angular velocity sensor.

FIG. 12 is a diagram illustrating an example of a measured value indicating an output of a sensor.

FIG. 13 is a diagram showing an equivalent circuit of a piezoelectric vibration type angular velocity sensor.

FIG. 14 is a diagram showing a temperature characteristic Tx on an excitation side and a temperature characteristic Tz on a detection side of a conventional angular velocity sensor.

[Explanation of symbols]

A: transducer element, A1: first branch, A2: second branch, A3: third branch, A4: fourth branch, B: transducer element, B1: first branch Part, B2: second branch, B3: third branch, B4: fourth branch, B5: fifth branch, C ...
Transducer element, C1 first branch, C2 second branch, C
Reference numeral 3 denotes a third branch, C4 denotes a fourth branch, C5 denotes a fifth branch, C6 denotes a sixth branch, C7 denotes a seventh branch, 4 denotes a vibrator element (quartz plate), 4-1 first branch, 4-2 second branch, 4-3 third branch, 4-4 fourth branch, 5
(5-1, 5-2) ... excitation electrode, 6 (6-1 to 6-)
4), 7 (7-1 to 7-4): detection electrode, 8: vibrator element (quartz plate), 8-1: first branch, 8-2: second branch, 8-3 ... 3rd branch, 8-4 ... 4th branch, 8-5
... the fifth branch, 8-6 ... the sixth branch, 8-7 ... the seventh branch, 9 (9-1, 9-2), 10 (10-1, 10-)
2) Excitation electrodes, 11 (11-1 to 11-4), 12
(12-1 to 12-4), 13 (13-1 to 13-
4), 14 (14-1 to 14-4) ... detection electrodes.

Claims (3)

[Claims] 1. A first branch portion having both ends supported and fixed, and a first branch portion extending from a branch surface at a substantially central portion in a direction orthogonal to the branch surface, and a leading end fixedly supported. A second branch and a branch surface between one end and the center of the first branch and a branch between the other end and the center are parallel to the longitudinal direction of the second branch. A third branch and a fourth branch extending in a direction parallel to the X-axis direction and a direction parallel to the longitudinal direction of the first branch. An AC voltage is applied by a vibrator element having a direction parallel to the Y-axis direction and a Z-axis direction parallel to a direction orthogonal to the XY plane, and an excitation electrode formed on a branch surface of the second branch portion. In response, the second branch portion is caused to expand and contract in the Y-axis direction, and the excited expansion vibration causes the first branch portion to have an amplitude in the Y-axis direction parallel to the XY plane. An excitation structure that causes the third branch and the fourth branch to be repeatedly moved in the Y-axis direction in parallel with the XY plane by the bending vibration; The third branch portion and the fourth branch portion are formed by the detection electrodes formed on the branch surfaces of the branch portions X-.
When the vibrator element rotates around the Z-axis while repeatedly moving in the Y-axis direction in parallel with the Y-plane, the third and fourth branches are caused by inertia in the X-axis direction. A detection structure for taking out charges generated by bending vibration caused by the angular velocity sensor. 2. A first branch portion whose both ends are supported and fixed, and a first branch portion extends from a branch surface at a substantially central portion in one direction and another direction orthogonal to the branch surface, and has a tip end. The second and third branches, which are supported and fixed, and the second and third branches from one end and the center of the first branch and from the branch between the other end and the center of the first branch. A fourth branch and a fifth branch extending in a direction parallel to the longitudinal direction of the third branch, wherein a direction parallel to the longitudinal direction of the first branch is an X-axis direction; 2, the direction parallel to the longitudinal direction of the third branch portion is the Y-axis direction,
An AC voltage is applied by a vibrator element having a Z-axis direction parallel to a direction orthogonal to the XY plane, and excitation electrodes formed on the branch surfaces of the second branch and the third branch. Then, the second branch and the third branch are caused to stretch and vibrate in the Y-axis direction, and the excited stretch vibration causes the first branch to swing in the Y-axis direction parallel to the XY plane. And the fourth branch portion and the fifth branch portion are further moved by X.
The fourth branch and the fifth branch are formed by an excitation structure that is repeatedly moved in the Y-axis direction in parallel with the Y plane, and a detection electrode formed on a branch surface of the fourth branch and the fifth branch. Branch is X-
When the vibrator element rotates around the Z-axis while repeatedly moving in the Y-axis direction in parallel with the Y-plane, the fourth and fifth branches have an X-axis component generated by inertia. A detection structure for taking out charges generated by bending vibration caused by the angular velocity sensor. 3. A first branch portion whose both ends are supported and fixed, and a first branch portion extends from a branch surface at a substantially central portion in one direction and another direction orthogonal to the branch surface, and has a tip end. The second and third branches supported and fixed, and a branch surface between one end and the center of the first branch is parallel to the longitudinal direction of the second and third branches. Fourth extending in one direction and the other
And a fifth branch, and a direction parallel to the longitudinal direction of the second and third branches from a branch surface between the other end and the center of the first branch. A sixth branch and a seventh branch extending in the other direction, wherein a direction parallel to a longitudinal direction of the first branch is an X-axis direction, and a longitudinal direction of the second and third branches is A transducer element having a direction parallel to the Y-axis direction and a direction parallel to the direction orthogonal to the XY plane being a Z-axis direction; and a vibrator element formed on a branch surface of the second branch portion and the third branch portion. The second branch portion and the third branch portion are caused to expand and contract in the Y-axis direction by receiving an AC voltage from the excitation electrode, and the first branch portion is moved in the XY plane by the excited expansion and contraction vibration. And the fourth, fifth, sixth and seventh branches are further caused by the bending vibration with an amplitude in the Y-axis direction in parallel to An excitation structure for repeatedly moving in the Y-axis direction in parallel with the XY plane; and detection formed on the branch surfaces of the fourth, fifth, sixth, and seventh branches. The electrodes cause the fourth, fifth, sixth and seventh branches to be XY.
When the vibrator element rotates around the Z-axis while repeatedly moving in the Y-axis direction parallel to the plane, the fourth branch, the fifth branch, the sixth branch, and the seventh branch are rotated. A detection structure for taking out charges generated by bending vibration caused by an X-axis direction component caused by inertia.