JP3336605B2 - Angular velocity sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor for use in an automobile navigation system and attitude control, and more particularly to a vibration type angular velocity sensor capable of detecting a rotational angular velocity of two axes. is there.

[0002]

2. Description of the Related Art Conventionally, various vibration-type angular velocity sensors utilizing the fact that when a vibrating body is rotated to generate a new vibration in accordance with the rotational angular velocity due to Coriolis force are known. As a device capable of detecting a rotational angular velocity, for example, there is a vibration angular velocity meter disclosed in JP-A-7-190782.

In this gyro, a weight is supported by four beams arranged at 90-degree intervals on the same plane. When this weight is excited in a direction perpendicular to the plane on which the beam is placed, and a rotational movement occurs around the axis of the beam, the vibration based on the Coriolis force occurs in the direction of the excitation vibration and in the direction perpendicular to the rotation axis. Is detected, the angular velocity can be determined by detecting this. Further, since the four beams are arranged on two axes orthogonal to each other, it is possible to detect a rotational angular velocity around these two axes.

[0004]

However, in this angular velocity sensor, it is essential to have a piezoelectric effect in three directions perpendicular to each other in order to integrally form the weight and the beam with a piezoelectric crystal. It is difficult to find crystals satisfying the above.

Further, the vibration due to the Coriolis force occurs perpendicularly to the exciting direction of the weight, but the four beams fix the weight firmly in the direction perpendicular to the exciting direction, and the vibration caused by the Coriolis force. Rather less likely to occur. Therefore, there is a possibility that sufficient detection sensitivity cannot be obtained.

[0006]

SUMMARY OF THE INVENTION The angular velocity sensor of the present invention has been made in view of such a problem, and has been developed in consideration of XYZ.
In a three-dimensional coordinate space, a base fixed to an object whose angular velocity is to be detected, a first vibrating piece and a second vibrating piece projecting away from this base in the direction of + Y, a first vibrating piece and a second vibrating piece. A vibrator having a weight connected to the vibrating piece via a connecting piece, and a weight of the vibrator being Y
Exciting means for exciting the first vibrating piece and the second vibrating piece so as to vibrate in the directions; X-direction vibration based on Coriolis force generated when the excited weight rotates about the Z axis; Detecting means for detecting a Z-direction vibration based on the Coriolis force generated when the weight portion rotated about the X-axis, and rotating about the Z-axis based on the X-direction vibration detected by the detecting means And an angular velocity calculating means for calculating the angular velocity of rotation about the X axis based on the Z-direction vibration detected by the detecting means.

When the first and second vibrating bars are excited, for example, in mutually opposite phases in the X direction, the weight connected to the two vibrating bars via the connecting piece vibrates in the Y direction. Therefore, when the vibrator rotates around the Z axis, the weight portion vibrates in the X direction due to the Coriolis force, and when the vibrator rotates around the X axis, the weight portion vibrates in the Z direction due to the Coriolis force. On the other hand, the first and second vibrating reeds that support the weight portion protrude from the base in the + Y direction, that is, since they are in a cantilevered form by the base, the leading ends of the first and second vibrating reeds. The portion is swingable with respect to forces in the X and Z directions. Therefore, the vibrations of the weight in the X and Z directions are efficiently transmitted to the first and second vibrating bars. The detecting means detects the vibration in the X direction or the Z direction, and the angular velocity calculating means can calculate the angular velocity based on the detection result of the detecting means.

When a quartz crystal Z plate is used as the vibrator, the X- or Z-direction vibration of the vibrating reed can be easily detected by appropriately arranging the detecting electrodes on the vibrating reed.

The vibrator has a third vibrating reed projecting coaxially with the first vibrating reed from the base in the -Y direction, and a fourth vibrating reed protruding from the base coaxially with the second vibrating reed in the -Y direction. And the third
A second weight portion connected to the vibrating piece and the fourth vibrating piece via a connecting piece, respectively, wherein the exciting means is configured to vibrate not only the weight portion but also the second weight portion so that the second weight portion vibrates in a reverse phase in the Y direction. 1
It is desirable to excite the fourth resonator element.

With this configuration, the center of gravity of the vibrator does not move when excited, and leakage of the excited vibration from the base to the object to be detected is reduced.

[0011]

FIG. 1 is a perspective view showing a vibrator of an angular velocity sensor according to an embodiment of the present invention. The vibrator 1 is arranged along the XY plane in the illustrated XYZ three-dimensional space coordinates. The vibrator 1 includes a vibrator base (base) 2 extending in the X-axis direction and a + Y
And the third vibrating piece 7 and the second vibrating piece 6 extending from the vibrator base 2 coaxially with the first vibrating piece 5 and the second vibrating piece 6 in the -Y direction. 4
A vibration piece 8 is provided. The dimensions of the first to fourth vibrating bars are all the same. Each vibrating bar is provided with an excitation electrode for exciting the vibrating bar in the X direction and a detection electrode for detecting both the X-direction vibration and the Z-direction vibration of the vibrating bar. The arrangement of the excitation electrodes and the detection electrodes will be described later.

A support rod 1 is provided on both sides of the vibrator base 2 in the X direction.
The fixing plates 3 and 4 are connected via 6, 17;
Since the fixed plates 3 and 4 are directly or indirectly fixed to the object whose rotational angular velocity is to be detected, the vibrator 1 is supported in a floating state with respect to the object to be detected.

A weight 12 is connected to the distal ends of the first vibrating piece 5 and the second vibrating piece 6 via connecting pieces 10 and 11. Each of the connecting pieces 10 and 11 has a V-shape bent at substantially the center, and the bent portion protrudes outward in the X direction. Since the first and second vibrating bars 5 and 6 and the weight portion 12 are connected in this manner, the first and second vibrating bars 5 and 6 have the same frequency in the X direction and are opposite to each other like a tuning fork. When excited in a phase, the weight 12 vibrates in the Y direction at the same frequency as the excitation frequency.

Similarly, the third vibrating piece 7 and the fourth vibrating piece 8
A weight portion 15 is connected to the tip of the pair via V-shaped connecting pieces 13 and 14, and the third and fourth vibrating pieces 7 and 8 are excited in the X direction at the same frequency and in mutually opposite phases. Then, the weight portion 15 vibrates in the Y direction at the same frequency as the excitation frequency.

The vibrator 1 configured as described above is integrally formed of a single crystal substrate of quartz.

Here, the crystal axis of quartz will be briefly described. Natural quartz is generally a columnar crystal, and the longitudinal central axis of the columnar crystal, that is, the <0001> crystal axis is Z
An axis or optical axis is defined, and a line passing through the Z axis and perpendicular to each surface of the columnar crystal is defined as a Y axis or a mechanical axis. A line passing through the Z axis and orthogonal to the vertical ridge line of the columnar crystal is defined as an X axis or an electric axis.

The single crystal substrate used for the vibrator 1 is Z
This is a substrate called a plate, and is a single crystal substrate cut out in a plane perpendicular or substantially perpendicular to the Z axis. Therefore, in the present embodiment, the Z axis of the crystal orientation and the vibrator 1
Coincides with the above-described Z axis indicating the disposition direction of. In addition, there are three sets of the X axis and the Y axis of the crystal which are orthogonal to each other, and one of the sets matches the X axis and the Y axis indicating the arrangement direction of the vibrator 1 on the drawing. The vibrator 1
Uses a Z plate of artificial quartz having the same crystal structure as natural quartz.

FIG. 2 shows the arrangement of detection electrodes for detecting vibrations in the Z direction provided on the first to fourth vibrating bars 5 to 8, respectively.
FIG. 3 is a diagram showing connections between electrodes. The first shown in FIG.
The vibrating bar 5 and the second vibrating bar 6 are sectional views taken along the line IIa-IIa in FIG. 1, and the third vibrating bar 7 and the fourth vibrating bar 8 are sectional views taken along the line IIb-IIb in FIG. The first vibrating reed 5 has the detecting electrodes 21a to 21d, and the second vibrating reed 6 has the detecting electrodes 22a to 22d.
To 22d, the detection electrodes 23a to 23d
However, detection electrodes 24a to 24d are provided on the fourth vibrating reed 8, respectively, and all the detecting electrodes are arranged at the corners of the vibrating reed as shown in the figure.

As for the detecting electrodes, those which oppose each other in each vibrating piece are connected to each other.
Or 26. That is, the detection electrodes 21a, 21b, 22a, 22b, 23a, 23
b, 24a, 24b are connected to the output terminal 25, and the detection electrodes 21c, 21d, 22c, 22d, 23c, 23d,
24c and 24d are connected to the output terminal 25.

FIG. 3 shows a detection electrode provided on each of the first to fourth vibrating bars 5 to 8 for detecting vibration in the X direction, and X
It is a figure which shows the arrangement | positioning of the excitation electrode which excites in a direction, and the connection between each electrode. The first vibrating reed 5 and the second vibrating reed 6 shown in FIG. 3 are sectional views taken along the line IIIa-IIIa of FIG.
The vibrating bar 7 and the fourth vibrating bar 8 correspond to IIIb-III in FIG.
It is b sectional drawing. Excitation electrodes 31a to 3
1c and the detecting electrodes 31d to 31f, the second vibrating piece 6 has the exciting electrodes 32a to 32c and the detecting electrodes 32d to 32f, and the third vibrating piece 7 has the exciting electrodes 33a to 33c and the detecting electrode 33.
d to 33f are provided on the fourth vibrating reed 8 by the excitation electrodes 34a to 34f.
c and detection electrodes 34d to 34f are provided as shown in the drawing. That is, the outer three electrodes (side surfaces and upper and lower surfaces) of each resonator element are excitation electrodes, and the inner three electrodes (side surfaces and upper and lower surfaces) are detection electrodes.

Excitation electrodes 31b, 31c, 32a, 33
b, 33c, 34a are connected to one input terminal 37 of the excitation signal, and the excitation electrodes 31a, 32b, 32c, 33a, 3a
4b and 34c are connected to the other input terminal 38 of the excitation signal. The detection electrodes 31e, 31f, 32e, 3
2f, 33d, 34d are connected to the output terminal 35, and the detection electrodes 31d, 32d, 33e, 33f, 34e, 34f
Are connected to the output terminal 36.

FIG. 4 shows an excitation circuit 50, a detection circuit 60 and an angular velocity calculation circuit 70 used in the angular velocity sensor of the present embodiment. The excitation circuit 50 forms excitation means together with the excitation electrodes provided on the vibrating bars 5 to 8, and the detection circuit 60 forms detection means together with the detection electrodes provided on the vibrating bars 5 to 8.

The excitation circuit 50 comprises an oscillation circuit 51. The oscillation circuit 51 outputs a pulse wave having a predetermined amplitude and a predetermined repetition frequency as an excitation signal between the output terminals 37 and 38, and outputs a 90-degree phase with the output signal. Is a circuit that outputs the shifted signal as a detection signal of the synchronous detection circuits 607 and 608. When the excitation signal generated by the oscillating circuit 51 is applied to the input terminals 37 and 38 shown in FIG. 3, a change in the electric field in the X direction occurs in a portion surrounded by the excitation electrode of each vibrating element, and the portion is formed of quartz. It expands and contracts in the Y direction in synchronization with the excitation signal due to the inverse piezoelectric effect.

For example, the portion of the first vibrating reed 5 surrounded by the excitation electrodes 31a to 31c expands and contracts in the Y direction (in FIG. 3, the direction perpendicular to the paper). On the other hand, no force for expanding and contracting in the Y direction is applied to the opposite portion, that is, the portion surrounded by the detection electrodes 31d to 31f. As a result, strain stress is generated inside the resonator element, and the first resonator element 5
Swings in the X direction. Similarly, the second vibrating bars 6 to 8 also swing in the X direction in synchronization with the excitation signal. When the excitation electrodes are connected as in the present embodiment, the first vibrating reed 5 and the second vibrating reed 6 are in opposite phases to each other, and the third vibrating reed 7 and the fourth
The vibrating bar 8 is in the opposite phase to the first vibrating bar 5 and the third vibrating bar 5
The resonator element 8 is excited in the same phase.

That is, when the first vibrating bar 5 bends in the -X direction, the second vibrating bar 6 is in the + X direction, the third vibrating bar 7 is in the -X direction, and the fourth vibrating bar 8 is When the first vibrating reed 5 bends in the + X direction, on the contrary, the second vibrating reed 6 moves in the −X direction and the third vibrating reed 7
Are bent in the direction of + X, and the fourth vibrating piece 8 is bent in the direction of -X. Here, the former state is referred to as a first bent state, and the latter state is referred to as a second bent state.

The first bending state, that is, the first vibrating reed 5 to 5
When all the fourth vibrating bars 8 are bent inward, the weight portion 12 is pushed out in the + Y direction, and the weight portion 15 is pushed out in the -Y direction. The second bent state, that is, the first
In a state where all of the vibrating bars 5 to the fourth vibrating bars 8 are bent outward, the weight portion 12 is oriented in the −Y direction, and the weight portion 15 is positioned in the + direction.
Each is drawn in the direction of Y. Therefore, when an excitation signal is applied to the excitation electrode of each vibrating reed, the weights 12 and 15 vibrate in the Y direction at an excitation frequency in opposite phases.

When the vibrator 1 rotates at an angular velocity Ω around the X axis in this excited state, F = 2 mV is applied to the weights 12 and 15.
A Coriolis force F represented by × Ω is generated in the Z direction. Here, m is the mass of the weight, and V is the vibration speed of the weight. The weights 12 and 15 are generated by the Coriolis force.
Vibrate in opposite phases at the excitation frequency. That is, when the weight portion 12 swings in the + Z direction, the weight portion 15 swings in the -Z direction. The vibration in the Z direction is caused by the connecting pieces 10, 1,
The vibration is efficiently transmitted to the first to fourth vibrating bars 5 to 8 via 1, 13, and 14. Therefore, the first vibrating reed 5 and the second
The vibrating bar 6 has the same phase, the third vibrating bar 7 and the fourth vibrating bar 8 have the same phase, and the first vibrating bar 5 and the third vibrating bar 7 have the opposite phases.
Vibrates in the direction. The phase is shifted from the excitation signal by 90 degrees, which is derived from the above-described equation of the Coriolis force F.

When the vibrator 1 rotates around the Z axis at an angular velocity Ω, a Coriolis force F expressed by F = 2 mV × Ω is generated in the weights 12 and 15 in the X direction, and the weights 12 and 15 Vibrate in opposite phases. That is, the weight 1
When 2 swings in the + X direction, the weight 15 swings in the -X direction. The vibration in the X direction is also caused by the connecting pieces 10, 11, 1
The first vibrating bar 5 and the second vibrating bar 6 are efficiently transmitted to the first vibrating bar 5 to the fourth vibrating bar 8 via the third and 14th, and the third vibrating bar 7 and the fourth vibrating bar 8 are in phase. The first vibrating reed 5 and the third vibrating reed 7 vibrate in the X direction in opposite phases, respectively. The phase of this vibration is also shifted by 90 degrees from the excitation signal.

The X-direction vibration and the Z-direction vibration of the resonator element based on the Coriolis force have amplitudes of Z
It changes so as to increase as the angular velocity around the axis and the angular velocity around the X axis increase. Therefore, by detecting these vibration amplitudes, the angular velocity around the Z axis and the angular velocity around the X axis can be obtained.

Next, the operation of detecting the X-direction vibration and the Z-direction vibration based on the Coriolis force of the vibrating reed will be described together with the detection electrodes shown in FIGS. 2 and 3 and the detection circuit shown in FIG.

The detection circuit 60 includes current-voltage conversion circuits 601 and 602 for X-direction vibration detection, a differential amplifier circuit 605, a synchronous detection circuit 607, an amplification offset removal circuit 609, and Z
It includes current-voltage conversion circuits 603 and 604 for detecting directional vibration, a differential amplification circuit 606, a synchronous detection circuit 608, and an amplification offset removal circuit 610.

First, the vibration in the Z direction will be described using the first vibrating piece 5 as an example. When the first resonator element 5 bends in the + Z direction due to vibration, the upper half of the resonator element 5 contracts in the Y direction, and the lower half extends in the Y direction. Due to the piezoelectric effect of quartz, Y
When contracted in the direction, dielectric polarization occurs in the X direction, and when extended in the Y direction, dielectric polarization occurs in the opposite X direction. Since the strength of dielectric polarization depends on the magnitude of expansion and contraction, it appears strongly on the upper or lower surface, and becomes weaker toward the middle. Therefore, the dielectric polarization appears concentrated at the four corners of the resonator element 5,
Each detection electrode 21 provided at a corner by this dielectric polarization
Positive or negative charges are collected at a to 21d. Detection electrode 21
a and 21b have the same polarity, and the detection electrodes 21c and 21d
Have opposite polarities. When the resonator element 5 swings downward, a polarity completely opposite to that described above appears based on the same principle.

When the above-described X-direction excitation is performed, the first
As described above, the phase of the Z-direction vibration based on the Coriolis force of the vibrating bars 5 to the fourth vibrating bars 8 is the same as that of the first vibrating bars 5, the second vibrating bars 6 are in phase, and the third vibrating bars 7 and 4 The vibrating reed has a reversed phase. The wiring between the detection electrodes shown in FIG. 2 is made in consideration of this phase relationship, and the electrodes in which electric charges of the same polarity collect with respect to bending in the Z direction are collectively connected to output terminals 25 and 26, respectively. are doing.

The current-voltage conversion circuits 603 and 604, which are circuits for the Z-direction vibration of the detection circuit 60, and the differential amplifier circuit 60
6. Synchronous detection circuit 608, amplification offset removal circuit 61
0 detects the amount of change in the total charge in each detection electrode of each vibrating bar generated in this way, and outputs a voltage signal corresponding to the vibration amplitude of the vibrating bar to the output terminal 612.

The current-voltage conversion circuits 603 and 604 are circuits for converting the amount of change in charge at the excitation electrode into a voltage value, and a general charge amplifier using an operational amplifier can be used. The differential amplifier circuit 606 is a circuit that receives the output signals of the current-voltage conversion circuits 603 and 604 and amplifies the potential difference between the two signals. The amplitude of the output signal is the vibration of the vibrating pieces 5 to 8 in the Z direction. Corresponds to amplitude.

The synchronous detection circuit 608 is a differential amplification circuit 606
After performing synchronous detection using a pulse signal having a phase shift of 90 degrees with respect to the excitation signal from the oscillation circuit 51 using the AC voltage signal output from the oscillator circuit 51 as a detection signal, integration processing is performed. This is a circuit in which an integration circuit is added to a detection circuit. FIG. 5 is a waveform diagram showing the synchronous detection at this time.

The amplification offset removing circuit 610 is a circuit for removing an offset component based on the characteristics of the vibrator, the vibration method, and the like, and is provided as necessary.

Next, detection of vibration in the X direction will be described. In the X direction, the excitation vibration and the vibration to be detected based on the Coriolis force are combined. Therefore, it is necessary to separate the detected vibration from the excitation vibration, which will be described later. First, the principle of detecting the X-direction vibration will be described using the first vibrating piece 5 as an example.

When the first vibrating bar 5 bends in the + X direction due to vibration, half of the + X side of the vibrating bar 5 contracts in the Y direction, and −
The half on the X side extends in the Y direction. Due to the piezoelectric effect of quartz,
Contraction in the Y direction causes dielectric polarization in the X direction, and extension in the Y direction causes dielectric polarization in the opposite X direction. As a result of such dielectric polarization, the side electrodes 31d and the upper and lower electrodes 31d are formed.
A potential difference is generated between e and 31f, and positive or negative charges are collected. When the resonator element 5 bends in the -X direction, an opposite polarity appears based on the same principle.

When the above-described X-direction excitation is performed, the phase of the X-direction vibration based on the Coriolis force of the first vibrating piece 5 to the fourth vibrating piece 8 is, as described above, the phase of the first vibrating piece 5.
On the other hand, the second vibrating reed 6 has the same phase, the third vibrating reed 7 and the fourth
The vibrating reed 8 has a reversed phase. Further, the phases of the X-direction excitation vibration are opposite to those of the first vibrating piece 5, that of the second vibrating piece 6, that of the third vibrating piece 7, and that of the fourth vibrating piece 8 are opposite.

The wiring between the detection electrodes shown in FIG. 3 is made in consideration of this phase relationship. For the vibration in the X direction based on the Coriolis force, the electrodes having the same polarity are collected together. It is connected to output terminals 35 and 36.

This connection between the electrodes simultaneously cancels out the electric charge generated directly on the X-direction detection electrode based on the excitation vibration. For example, the detection electrode 33e
And 34e, the charges due to the X-direction vibration based on the Coriolis force have the same polarity, and the charges due to the excitation vibration have different polarities. Therefore, if both electrodes are connected as in the present embodiment, the X-direction vibration based on the Coriolis force is added, and the X-direction vibration based on the excitation vibration cancels each other. Since the other detection electrodes are also connected in this manner, a signal indicating only the X-direction vibration based on the Coriolis force appears on the output terminals 35 and 36 as a whole.

The signal indicating the X-direction vibration based on the Coriolis force obtained in this manner is supplied to the current-voltage conversion circuits 601 and 602, which are the circuits for the Z-direction vibration of the detection circuit 60, the differential amplifier circuit 605, and the synchronous amplifier. The detection circuit 607 and the amplification offset removal circuit 609 perform the same processing as the detection processing of the Z-direction vibration, and a voltage signal corresponding to the X-direction vibration amplitude based on the Coriolis force of the resonator element appears at the output terminal 611.

The voltage signals corresponding to the X-direction vibration amplitude and the Z-direction vibration amplitude based on the Coriolis force of the resonator element processed by the detection circuit 60 are output from the output terminal 611, respectively.
And 612 to the angular velocity calculation circuit 70.

The angular velocity calculation circuit 70 calculates the Coriolis force in the X direction from the signal of the output terminal 611, and calculates the rotational angular velocity Ωz of the vibrator 1 about the Z axis from the above-described relational expression between the angular velocity and the Coriolis force. calculate. Further, the Coriolis force in the Z direction is obtained from the signal of the output terminal 612, and the rotational angular velocity Ωx of the vibrator 1 around the X axis is calculated from the relational expression between the angular velocity and the Coriolis force.

In this embodiment, the vibrator 1 is cut out from a Z plate of quartz, which is a piezoelectric crystal material. However, a vibrator made of a non-piezoelectric material such as metal may be used. In that case, instead of the excitation electrode and the detection electrode,
For example, an excitation diaphragm and a vibration detection plate in which PZT is sandwiched between two electrodes are used.

FIG. 6 is a plan view showing a vibrator applied to the second embodiment of the present invention. The vibrator 60 has an XYZ
In three-dimensional space coordinates, a vibrator base (base) 2 extending in the X-axis direction, a first vibrating piece 5 and a second vibrating piece 6 extending from the vibrator base 2 in the + Y direction, -Y coaxially with the first vibrating piece 5 and the second vibrating piece 6, respectively.
A third vibrating piece 7 and a fourth vibrating piece 8 extending in the directions of. The support base 16 is provided on both sides of the vibrator base 2 in the X direction.
The fixing plates 3 and 4 are connected to each other via the reference numeral 17. First
The weight portion 12 is connected to the distal ends of the vibrating bar 5 and the second vibrating bar 6 via connecting bars 61 and 62, and to the distal ends of the third vibrating bar 7 and the fourth vibrating bar 8 via connecting bars 63 and 64. The weight part 15 is connected. Connecting pieces 61 to 64
Are the excitation pieces 6 extending from the weights 12 and 15 in the X direction.
1a to 64a.

The vibrator 60 thus configured is made of a non-piezoelectric material, for example, a stainless steel material, and the excitation elements 61a to 64a of the connecting pieces are provided with a piezoelectric element for vibrating the excitation element in the Y direction. Each of the first to fourth vibrating bars 5 to 8 is provided with a piezoelectric element for detecting X-direction vibration and Z-direction vibration of the vibrating bar.

The vibrator 60 includes excitation pieces 61a to 64a
To excite the weights 12 and 15 in the Y direction. When the vibrator 60 rotates around the X axis in this state, the first
As in the embodiment, the weight portions 12 and 15 vibrate in the Z direction due to the Coriolis force, and the vibration is transmitted to the vibrating pieces 5 to 8 and, when rotated about the Z axis, the vibrating pieces 5 to 8 vibrate in the X direction. . Therefore, the angular velocity around the X axis and the angular velocity around the Z axis can be obtained by detecting the Z-direction vibration and the X-direction vibration of each resonator element.

According to the angular velocity sensor using the vibrator 60, the excitation is performed by the connecting piece, and the X-direction vibration and the Z-direction vibration by the Coriolis force are detected by the vibrating piece. Vibration is not included, and it is easy to detect only vibration due to Coriolis force.

However, in the case of the vibrator 60, even if the vibrator itself is constituted by a quartz Z plate, excitation in the Y direction and detection of the X-direction vibration and the Z-direction vibration utilize the piezoelectric effect of the vibrator itself. You can't do that.

In the vibrators 1 and 60 of the first and second embodiments described above, the vibrating reed and the weight portion are provided symmetrically about the X axis passing through the vibrator base. This suppresses the movement of the center of gravity due to the excitation by exciting the two weight portions configured as described above in phases opposite to each other.
This is to prevent vibration leakage due to the movement of the center of gravity. Therefore, conversely, if the vibration leakage can be ignored or the vibration leakage can be suppressed by another method, only the vibrating piece and the weight portion on one side may be used. For example, a vibrator having a structure in which the third vibrating piece 7, the fourth vibrating piece 8, the connecting pieces 13, 14, and the weight 15 are removed from the vibrator 1 may be used.

[0053]

As described above, according to the angular velocity sensor of the present invention, it is possible to detect the rotational angular velocity around two rotational axes orthogonal to each other with high sensitivity with a single vibrator.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a vibrator of an angular velocity sensor according to an embodiment of the present invention.

FIG. 2 is a view showing the arrangement of detection electrodes for detecting vibrations in the Z direction provided on first to fourth vibrating pieces 5 to 8, and connections between the electrodes.

FIG. 3 is a diagram showing an arrangement of detection electrodes for detecting vibration in the X direction and excitation electrodes for exciting in the X direction, provided on the first to fourth vibrating pieces 5 to 8, and a connection between the electrodes;

FIG. 4 is a circuit diagram showing an excitation circuit 50, a detection circuit 60, and an angular velocity calculation circuit 70 used in the angular velocity sensor of the embodiment.

FIG. 5 is a diagram for explaining signal detection processing in a detection circuit 60;

FIG. 6 is a plan view showing a vibrator used in a second embodiment of the present invention.

[Explanation of symbols]

1, 60: vibrator, 2: vibrator base, 3, 4: fixed plate,
5: first vibrating bar, 6: second vibrating bar, 7: third vibrating bar, 8
... the fourth vibrating reed, 10, 11, 13, 14, 61 to 64 ...
Connecting pieces, 12, 15, weight parts, 50, excitation circuit, 60,
Detection circuit, 70: angular velocity calculation circuit.

Claims (2)

(57) [Claims] 1. A base fixed to an object whose angular velocity is to be detected in an XYZ three-dimensional coordinate space, and +
A first vibrating reed and a second protruding piece protruding apart from each other in the direction of Y;
A vibrator comprising: a vibrating reed; and a weight portion connected to the first vibrating reed and the second vibrating reed via a connecting piece, respectively; and the first vibrating portion vibrates in the Y direction.
Exciting means for exciting the vibrating piece and the second vibrating piece; X-direction vibration based on Coriolis force generated when the excited weight portion rotates about the Z-axis; Detecting means for detecting a Z-direction vibration based on the Coriolis force generated when rotating about an axis; and calculating an angular velocity of rotation about the Z-axis based on the X-direction vibration detected by the detecting means. An angular velocity calculating means for calculating an angular velocity of rotation about the X axis based on the Z-direction vibration detected by the detecting means. 2. The vibrator includes a third vibrating reed protruding from the base in the direction of -Y coaxially with the first vibrating reed, and a vibrator extending in the direction of -Y coaxially with the second vibrating reed from the base. A protruding fourth vibrating reed, and a second weight portion connected to the third vibrating reed and the fourth vibrating reed via a connecting piece, respectively, wherein the excitation unit includes the weight portion and the second weight portion. The angular velocity sensor according to claim 1, wherein the first to fourth vibrating pieces are excited so as to vibrate in opposite phases in the Y direction.