JP3307130B2 - 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 detecting an angular velocity.

[0002]

2. Description of the Related Art FIG. 3 shows an angular velocity sensor 1 composed of a vibrating gyro. This angular velocity sensor 1
Is for detecting angular velocities around the z-axis and the x-axis. The planar vibrator 3 and the comb-shaped movable electrodes 10 and 11 are formed on a fixed substrate 21 such as silicon using a semiconductor micromachining technique. The fixed electrodes 12 and 13 are provided so as to mesh with the movable electrodes 10 and 11, respectively, and the support beams 8 and the like for supporting the planar vibrator 3 are formed.
Further, a lower electrode 16 is formed so as to face the plane vibrator 3.

One end of the support beam 8 supports the plane vibrator 3 and the other end thereof is bent and formed in a serpentine shape (U-shape) to form a fixed end. orthogonal 2 in y direction
It is possible to vibrate in the direction. Further, the plane vibrator 3
When an AC voltage is applied to the moving electrode 11 or the fixed electrode 13, the electrostatic force between the moving electrode 11 and the fixed electrode 13 causes
Excitation is performed in the y direction in the same plane as the plane vibrator 3.

In the angular velocity sensor 1 having the above-described structure, when the plane vibrator 3 is excited in the y-direction and rotated about the x-axis, a direction orthogonal to the rotation axis direction and the excitation direction, here the plane vibrator 3 Generates a Coriolis force in the z direction orthogonal to the plane of the plane vibrator 3.
Vibrates in the z direction. The magnitude of the amplitude of the vibration is detected in accordance with the change in the capacitance between the planar vibrator 3 and the lower electrode 16, and the magnitude of the rotational angular velocity around the x-axis is detected based on the change in the capacitance. I do. When the plane vibrator 3 rotates around the z axis, Coriolis force is generated in the x direction, and the plane vibrator 3 vibrates in the x direction in the same plane as the plane vibrator 3. The magnitude of the amplitude of the vibration is detected in accordance with the change in the capacitance between the movable electrode 10 and the fixed electrode 12, and the magnitude of the rotational angular velocity about the z-axis is detected.

[0005]

By the way, here,
In order to increase the detection sensitivity of the rotational angular velocity by vibrating the plane vibrator 3 in the x and z directions with a large amplitude due to the Coriolis force, the vibration in the y direction which is the excitation direction of the plane vibrator 3 is increased. The resonance frequency is adjusted so that the resonance frequencies of the vibrations in the x-direction and the z-direction of the planar vibrator 3 coincide with each other.

However, the x, y, z of the planar vibrator 3
Since the resonance frequencies of the vibrations in the directions are formed to be the same, when the Coriolis force in the z-direction and the x-direction due to the rotation about the x-axis and the rotation about the z-axis is applied to the planar vibrator 3, FIG. As shown, the moving electrode 10 for detecting the angular velocity around the z-axis vibrates in the x-direction due to rotation around the z-axis, and also vibrates in the z-direction due to rotation around the x-axis.
Due to the vibration in the z direction, the movable electrode 10 is displaced in the z direction with respect to the fixed electrode 12, and the electrode area where the movable electrode 10 and the fixed electrode 12 face each other is reduced. There is a problem that the electrode area effective for detecting the capacitance between the electrodes decreases, the change in the capacitance decreases accordingly, and the sensitivity in detecting the angular velocity around the z-axis decreases.

A moving electrode for exciting the plane vibrator 3
11 also oscillates in the z direction by rotation about the x axis, the area of the electrode facing the fixed electrode 13 decreases as described above, and the amplitude of the voltage applied to the movable electrode 11 or the fixed electrode 13 increases. There is a problem that the plane vibrator 3 is not excited.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an angular velocity sensor capable of detecting both angular velocities around two different axes with high sensitivity.

[0009]

In order to achieve the above object, the present invention is configured as follows. That is, in the angular velocity sensor according to the present invention, the weight vibrator is connected to the inside of the frame via the connection beam, and a plane vibrator is formed by a combined body of the frame and the weight vibrator. Are supported so as to be able to vibrate in the X and Y directions of the X and Y two-dimensional planes via supporting beams, and a first moving comb is provided in one of the X and Y directions from the outer end of the frame. X, Y
A second fixed comb-shaped electrode protruding from the other side of the first fixed comb-shaped electrode; And a second fixed comb electrode that fits with the moving comb electrode at a distance, and a vertical moving electrode is provided on the weight vibrator, and the weight vibrating body is spaced from the vertical moving electrode. A fixed opposing electrode is provided on the opposing side of the interposition, and a pair of the first moving comb electrode and the first fixed comb electrode is configured to excite the planar vibrator in one of X and Y directions by electrostatic force. A pair of a second movable comb electrode and a second fixed comb electrode is arranged in the other direction of X and Y corresponding to a change in angular velocity of rotation about a Z axis perpendicular to the X and Y planes. Configured as a Z-axis angular velocity detection electrode for detecting vibration amplitude,
A pair of the vertical movement side electrode and the fixed counter electrode is a plane axis angular velocity detection electrode for detecting the vibration amplitude in the Z axis direction of the weight vibrating body corresponding to the angular velocity change of rotation about the other X and Y axis. It is characterized by having been constituted as.

Further, according to the present invention, a servo mechanism is connected to the Z-axis angular velocity detecting electrode, and the frame is formed of a right-angled quadrilateral. Is provided, and a second movable comb electrode is provided on the other two opposite sides orthogonal to the above, and the plane vibrator is fixed by a doubly supported beam that can be vibrated in the X direction and the Y direction. Adjusted so that the resonance frequency of the X-direction vibration of the plane vibrator, the resonance frequency of the Y-direction vibration of the plane vibrator, and the resonance frequency of the Z-direction vibration of the weight vibrator are substantially fixed to the substrate. The feature is that it is done.

[0011]

In the present invention having the above-mentioned structure, the plane vibrator is excited and vibrated in the Y direction, for example, by the electrostatic force between the first movable comb electrode and the first fixed comb electrode which are the excitation electrodes. When rotated about the X axis, only the weight vibrator of the planar vibrator vibrates largely in the Z direction due to the Coriolis force in the Z direction, and the frame of the planar vibrator and the first and second moving comb teeth The electrode hardly moves in the Z direction. The magnitude of the vibration amplitude of the weight vibrator is detected in accordance with the change in capacitance, and the angular velocity around the X axis is detected based on the change in capacitance.

Further, when the Z-axis is rotated around the Z-axis, the plane vibrator and the first and second movable comb electrodes tend to vibrate in the X direction due to the Coriolis force in the X direction. Then, for example, the servo mechanism detects the vibration in the X direction and feeds back the voltage in a direction to cancel the vibration in the X direction to apply the voltage to the second moving comb electrode or the second fixed electrode which is the angular velocity detection electrode around the Z axis. Applied to the comb electrode. For this reason, the first and second movable comb electrodes and the plane vibrator hardly vibrate in the X direction. A voltage applied from the servo mechanism to the Z-axis angular velocity detection electrode is detected in accordance with a change in capacitance, and an angular velocity about the Z-axis is detected based on the voltage.

As described above, the vibrations in the X direction and the Z direction are separated, and even if Coriolis forces in the X direction and the Z direction are simultaneously applied to the plane vibrator, the second electrode, which is the angular velocity detection electrode around the Z axis, is used.
The moving comb electrode does not shift in the Z direction with respect to the second fixed comb electrode, and the angular velocity around the Z axis is detected with high sensitivity. Also, the first movable comb electrode, which is the excitation electrode, does not shift in the Z direction with respect to the first fixed comb electrode, and the plane vibrator always excites in the Y direction with a stable amplitude.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same reference numerals are given to the same parts as those in the conventional example, and the detailed description thereof will be omitted.

FIG. 1 shows an angular velocity sensor 1 according to this embodiment. The angular velocity sensor 1 includes a planar vibrator 3 and
Moving electrodes 11A and 11B that are first moving comb electrodes, fixed electrodes 13A and 13B that are first fixed comb electrodes,
The movable electrodes 10A and 10B as the movable comb electrodes, the fixed electrodes 12A and 12B as the second fixed comb electrodes, the servo mechanism 18, the detector 19, the support beam 8, and the lower electrode 16 It is configured to have.

The plane vibrating body 3 characteristic of this embodiment is not a single flat plate as in the prior art, but a rectangular
And a weight vibrator 5 and a connection beam 4, and the weight vibrator 5 is connected to the inside of the frame 6 via the connection beam 4. Planar vibrator 3 which is such a combined body
At the resonance frequency of the excitation vibration in the y direction, the resonance frequency of the vibration in the x direction of the plane vibrator 3 orthogonal to the y direction, and the vibration of the weight oscillator 5 in the z direction orthogonal to both the y and x directions. The resonance frequency is adjusted so as to be substantially equal to the resonance frequency. By this adjustment, the weight oscillator 5
And the frame body 6 have resonance frequencies different from each other in vibration in the z direction.

As described above, the resonance frequency in the x, y, and z orthogonal directions of the plane vibrator 3 is adjusted, so that when the plane vibrator 3 is excited in the y direction, it rotates around the x axis. When the Coriolis force is generated in the z direction, the weight vibrator 5 vibrates largely in the z direction, and the frame 6 hardly vibrates in the z direction.

The weight vibrating body 5 has a function as a vertical moving side electrode in addition to functioning as a vibrating body, and a lower electrode which is a fixed opposing electrode opposed to the bottom side of the weight vibrating body 5 with an interval therebetween. 16 are provided. By detecting a change in the capacitance between the weight vibrator 5 and the lower electrode 16, the magnitude of the rotational angular velocity about the x-axis and the like are detected as in the related art.

Moving electrodes 11A and 11B serving as excitation electrodes are respectively provided at outer ends of two opposite sides of the frame body 6 in the y direction, and fixed electrodes 21 facing the two sides are provided on the fixed substrate 21 side. Fixed electrodes 13A, 13A, which are fitted with moving electrodes 11A, 11B with an interval
13B is formed. Further, movable electrodes 10A and 10B serving as z-axis angular velocity detecting electrodes are respectively provided at outer ends of the other two opposite sides of the frame body 6 so as to protrude in the x direction, and a fixed substrate 21 facing the other two sides is provided. On the side, fixed electrodes 12A and 12B are formed to be fitted to the respective moving electrodes 10A and 10B with an interval therebetween.
The frame 6 is supported by a support beam 8 which is a doubly supported beam. One end of the support beam 8 supports the frame 6, and the other end is bent in a claw shape (U-shape). Fixed board 21
It is fixed to. Due to the bent shape of the support beam 8,
The plane vibrator 3 can vibrate in two directions orthogonal to the x and y directions.

The servo mechanism 18 incorporates feedback voltage applying means 22A and 22B. The feedback voltage applying means 22A, 22B and the input terminals 23A, 23B of the servo mechanism 18 are connected to the corresponding positions of the fixed electrodes 12A, 12B, respectively, which are the electrodes for detecting the angular velocity around the z-axis. The servo mechanism 18 includes moving electrodes 10A and 10B and fixed electrodes 12A and 12B.
When the capacitance between the movable electrodes 10A and 10B is detected to change in the x direction with the moving electrodes 10A and 10B trying to vibrate in the x direction together with the plane vibrator 3 subjected to the Coriolis force in the x direction, feedback voltage applying means 22A and 22B are driven, and the voltage applying means 22A and 22B hold the moving electrodes 10A and 10B at a fixed position with respect to the x direction, that is, the moving electrodes 10A and 10B.
A feedback voltage is applied to the fixed electrodes 12A and 12B in a direction to cancel the x-direction vibration of A and 10B. Also, the detection unit
19 is a feedback voltage applying means 22A of the servo mechanism 18,
22B, the feedback voltage applying means 22
A feedback voltage applied from A, 22B to fixed electrodes 12A, 12B is detected as a signal of a change in capacitance between fixed electrodes 12A, 12B and moving electrodes 10A, 10B, and the magnitude of the rotational angular velocity about the z-axis is detected. Detect.

In the angular velocity sensor 1 having the above structure, the plane vibrator 3 is excited in the y direction in the same plane as the plane vibrator 3 by the electrostatic force between the movable electrodes 11A and 11B, which are excitation electrodes, and the fixed electrodes 13A and 13B. Then, when rotated about the x-axis, only the weight vibrating body 5 of the plane vibrating body 3 vibrates largely in the z direction due to the Coriolis force in the z direction, and the gap between the bottom electrode of the weight vibrating body 5 and the lower electrode 16 is generated. The magnitude of the rotational angular velocity about the x-axis is detected based on the change in the capacitance. At this time, the frame 6 and the movable electrodes 10A, 10B, 11A, and 11B hardly vibrate in the z direction because the resonance frequency of the vibration in the z direction between the frame 6 and the weight vibrator 5 is different.

When the plane vibrator 3 rotates about the z-axis, the plane vibrator 3 tries to vibrate in the x direction together with the movable electrodes 10A, 10B, 11A, 11B in the same plane as the plane vibrator 3. Then, the feedback voltage applying means 22 of the servo mechanism 18
A and 22B are driven to apply a feedback voltage to the fixed electrodes 12A and 12B in a direction to cancel the vibration of the movable electrodes 10A and 10B in the x direction, and the movable electrodes 10A and 10B are held at a fixed position in the x direction. You. That is, the plane vibrator 3 and the movable electrodes 10A, 10B, 11A, 11B do not vibrate in the x direction.
The detection unit 19 detects the feedback voltage, and detects the magnitude of the rotational angular velocity around the z-axis based on the feedback voltage.

As described above, the vibrations caused by the Coriolis force in the z direction and the x direction are detected separately by the weight vibrator 5 and the frame 6 of the plane vibrator 3. Even if Coriolis forces in the x direction are applied simultaneously, the angular velocity sensor 1 accurately detects both the angular velocity around the x axis and the angular velocity around the z axis. Further, when a Coriolis force in the z direction is applied to the plane vibrator 3, only the weight vibrator 5 vibrates, and the movable electrodes 11A and 11B, which are excitation electrodes, do not vibrate in the z direction integrally with the frame 6. , Moving electrodes 11A, 11B
Are not displaced with respect to the fixed electrodes 13A and 13B, and the plane vibrating body 3 always performs excitation vibration with a stable vibration amplitude.

According to this embodiment, the plane vibrator 3 is
Of the plane vibrator 3 in the y direction, the resonance frequency of the plane vibrator 3 in the x direction, and the resonance frequency of the weight vibrator 5 in the z direction. Since the resonance frequency of the vibration was adjusted to match, when the plane vibrator 3 rotates around the x-axis, only the weight vibrator 5 vibrates in the z direction, and the weight vibrator 5 and the frame 6 in the z direction. Since the resonance frequencies of the vibrations are different, the frame 6 hardly vibrates in the z direction. That is, the movable electrodes 10A and 10B, which are the angular velocity detecting electrodes around the z axis, do not shift in the z direction with respect to the fixed electrodes 12A and 12B. 10B and fixed electrode 12A,
The effective electrode area for detecting the change in the capacitance between the electrodes 12B does not decrease, and the rotational angular velocity around the z-axis can be detected with high sensitivity by effectively utilizing the entire surface of the electrode.

The moving electrode which is an excitation electrode as described above
11A and 11B are not displaced in the z direction with respect to the fixed electrodes 13A and 13B, and the plane vibrator 3 is always stable with the amplitude of the voltage applied to the moving electrodes 11A and 11B or the fixed electrodes 13A and 13B. It can be excited and vibrated.

As described above, the angular velocity sensor 1 capable of detecting both the angular velocities around the z-axis and the x-axis with high sensitivity can be manufactured with a simple configuration.

Furthermore, since the servo mechanism 18 is provided, even when the Coriolis force of the plane vibrating body 3 in the x direction is applied, the plane vibrating body 3 does not actually vibrate in the x direction, and the Coriolis force is strongly applied. Since the fixed electrodes 12A and 12B and the movable electrodes 10A and 10B do not come into contact with each other when they are touched and a change in capacitance due to Coriolis force cannot be detected, the angular velocity detection area of the angular velocity sensor 1 can be widened. It is possible to take.

Note that the present invention is not limited to the above-described embodiment, but can adopt various embodiments. For example, in the above-described embodiment, the fixed end side of the support beam 8 is bent in a claw shape. However, as shown in FIG. The beam 8 may have any shape as long as the plane vibrator 3 can vibrate in two directions orthogonal to the x direction and the y direction, and is not limited to the shapes shown in FIGS. 1 and 2.

Further, in the above embodiment, the weight vibrator 5 is connected to the inside of the frame 6 by the connecting beam 4 which is a doubly supported beam, but may be a cantilevered beam as shown in FIG. In the above embodiment, the moving electrodes are provided on both sides of the frame body 6 facing each other.
Although 10A and 10B or 11A and 11B are provided, a moving electrode may be provided on only one of the sides.

Further, in the above embodiment, the weight vibrating body 5 functions not only as a vibrating body but also as a vertical moving side electrode. However, the weight vibrating body 5 may be provided with a separate vertical moving side electrode. Good.

[0031]

According to the present invention, since the plane vibrator is a combined body in which the weight vibrator is connected to the inside of the frame via the connecting beam, the Coriolis force in the Z direction is applied to the plane vibrator. Then, the weight vibrator at the center vibrates largely in the Z direction, and the frame at the end hardly vibrates in the Z direction. From this, Z
A second movable comb electrode serving as an angular velocity detecting electrode around the axis and a first movable comb electrode serving as an excitation electrode for exciting a plane vibrator in the Y direction, for example, are second and first fixed comb electrodes. Does not shift in the Z direction. That is, even if the Coriolis force in the X direction due to the rotation around the Z axis and the Coriolis force in the Z direction due to the rotation around the X axis are simultaneously applied to the plane vibrating body, the change in the capacitance between the Z-axis angular velocity detecting electrodes is not affected. The effective electrode area for detection does not decrease, and the angular velocity around the Z-axis can be detected with good sensitivity by effectively using the entire surface of the electrode.

As described above, even when the Z-direction Coriolis force is applied to the planar vibrator, the first movable comb electrode of the excitation electrode is moved in the Z direction with respect to the first fixed comb electrode facing the same. Since there is no displacement, the effective electrode area for generating the excitation vibration does not decrease, and the plane vibrator always stably generates the excitation vibration with the amplitude of the vibration corresponding to the voltage applied to the excitation electrode. It can be carried out.

From the above, an angular velocity sensor capable of detecting the angular velocity of rotation about two different axes with high sensitivity can be manufactured.

Further, in a configuration in which a servo mechanism is provided on the Z-axis angular velocity detecting electrode, even if Coriolis force in the X direction is applied to the planar vibrating body, the second movable comb electrode is actually in the X direction. Does not vibrate. From this, even if the Coriolis force in the X direction is strongly applied to the planar vibrator, the second moving comb electrode contacts the opposing second fixed comb electrode to reduce the change in capacitance due to the Coriolis force. It is no longer impossible to detect, and the angular velocity detection area of the angular velocity sensor can be widened.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an angular velocity sensor according to the present embodiment.

FIG. 2 is an explanatory diagram showing another embodiment according to the present invention.

FIG. 3 is an explanatory diagram showing a conventional example.

FIG. 4 is an explanatory diagram showing a vibration operation by a Coriolis force in the moving electrode of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Angular velocity sensor 3 Planar vibrator 4 Connecting beam 5 Weight vibrator 6 Frame 8 Doubly supported beam 10A, 10B, 11A, 11B Moving electrode 12A, 12B, 13A, 13B Fixed electrode 16 Lower electrode 18 Servo mechanism 21 Fixed substrate

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tomohase Hasegawa 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Inside Murata Manufacturing Co., Ltd. (72) Kenichi Atsuchi 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Inside Murata Manufacturing Co., Ltd. (72) Inventor Katsuhiko Tanaka 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Prefecture Inside Murata Manufacturing Co., Ltd. (56) References JP-A-5-248872 (JP, A) JP-A-6 -123631 (JP, A) JP-A-6-123632 (JP, A) JP-A-5-312576 (JP, A) JP-A-6-281665 (JP, A) (58) Fields investigated (Int. . ^7, DB name) G01C 19/56 G01P 9/04

Claims (5)

(57) [Claims] A weight vibrator is connected to the inside of a frame via a connecting beam to form a planar vibrator by a combined body of the frame and the weight vibrator, and the planar vibrator has a support beam on a fixed substrate. Vibration in the X and Y directions of a two-dimensional X, Y plane is supported through the frame, and X, Y
A first movable comb electrode is protruded in one direction toward the first side, and a second movable comb electrode is protruded in the other direction toward X and Y, and the first movable comb electrode is spaced from the first movable comb electrode on the fixed substrate side. A first fixed interdigital electrode fitted through the first fixed interdigital electrode, and a second fixed interdigital electrode fitted into the second moving interdigital electrode via an interval. Is provided with a vertical moving side electrode, and a fixed counter electrode is provided on the side opposite to the vertical moving side electrode with an interval, and the set of the first moving comb electrode and the first fixed comb electrode is a plane. The vibrating body is configured as an excitation electrode that vibrates in one of the X and Y directions by electrostatic force, and a pair of a second moving comb electrode and a second fixed comb electrode is formed around a Z axis perpendicular to the X and Y planes. Around the Z axis for detecting the vibration amplitude in the other direction of the X and Y corresponding to the angular velocity change of rotation A pair of the vertical moving side electrode and the fixed counter electrode is configured as a speed detecting electrode, and detects a vibration amplitude in the Z axis direction of the weight vibrating body corresponding to a change in the angular velocity of rotation about the other axis in the X and Y directions. Angular velocity sensor configured as an angular velocity detection electrode around a plane axis. 2. The angular velocity sensor according to claim 1, wherein a servo mechanism is connected to the Z-axis angular velocity detection electrode. 3. The frame is formed of a right-angled quadrilateral. At least two opposing sides of the rectangular frame are provided with first moving comb electrodes, and the other two opposing orthogonal sides are second moving comb teeth. 3. The angular velocity sensor according to claim 1, further comprising an electrode. 4. The angular velocity sensor according to claim 1, wherein the plane vibrator is fixed to the fixed substrate by a double-supported beam that is capable of vibrating in the X and Y directions. 5. The resonance frequency of the X-direction vibration of the plane vibrator, the resonance frequency of the Y-direction vibration of the plane vibrator, and the resonance frequency of the Z-direction vibration of the weight vibrator are adjusted to be substantially the same. The angular velocity sensor according to claim 1, claim 2, claim 3, or claim 4.