JP3336730B2 - 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 used for an automobile or the like.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional angular velocity sensor for detecting angular velocity about two axes. This angular velocity sensor 1 is composed of H-shaped vibrating bodies 2A and 2B fixed to one support rod 3 orthogonally to each other.
A piezoelectric element 4 for excitation is attached to the side surface of
An excitation piezoelectric element 5 is attached to a side surface of the vibrating body 2B. A detection piezoelectric element 6 is attached to one side surface of the support rod 3, and a detection piezoelectric element 7 is attached to a surface perpendicular to this surface.

An AC voltage is applied to the piezoelectric element 4 for excitation of the vibrating body 2A to vibrate the piezoelectric element 4 for excitation in the X-axis direction. Thus, the vibrating body 2A causes the tuning fork to vibrate. In this state, for example, when an angular velocity is applied around the Z axis of the angular velocity sensor 1 , Coriolis force is generated in a direction (Y axis direction) orthogonal to both the rotation axis direction (Z axis direction) and the vibration direction (X axis direction). Working, the force is applied to the detecting piezoelectric element 6 attached to the support rod 3, and the piezoelectric element 6 generates distortion. By detecting the electric signal having the magnitude of the distortion, the angular velocity around the Z axis can be detected. Also, when the exciting piezoelectric element 5 of the vibrating body 2B vibrates in the Y-axis direction and an angular velocity is applied around the X-axis of the sensor 1 , Coriolis force is generated in the Z-axis direction. In addition to the piezoelectric element 6 for use, the piezoelectric element 6 generates distortion. By detecting an electric signal having the magnitude of this distortion, an angular velocity around the X axis can be detected. Thereby, the angular velocities around two axes, around the X axis and around the Z axis, are detected.

[0004]

However, the vibrating bodies 2A and 2B and the support rod 3 are formed by machining, have a complicated structure, and are assembled by welding, screwing or the like. It was very difficult to manufacture the sensor 1 in the first place.

Further, the conventional angular velocity sensor having an H-shaped vibrating body is inevitably increased in size due to machining. Therefore, it is extremely difficult to simultaneously form the piezoelectric elements 6 and 7 on two perpendicular surfaces of the support rod 3 by using the semiconductor fine processing technology to reduce the size of the angular velocity sensor. ,
There is a problem that it is extremely difficult to reduce the size of the H-shaped angular velocity sensor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a highly accurate and extremely small angular velocity sensor capable of detecting angular velocity in two axial directions without requiring complicated assembly work. Is to do.

[0007]

The present invention has the following configuration to solve the above-mentioned problems. That is,
In the angular velocity sensor according to the present invention, a first vibrator vibrating in the Y-axis direction of the X-axis and the Y-axis orthogonal to each other in the plane of the sensor substrate is formed on the sensor substrate. ,
A second vibrator which vibrates in the X-axis direction, Oyo the X-axis
And perpendicular to the surface of the sensor substrate.
A third vibration body that vibrates in the Z-axis direction, and a vibration exciter that vibrates the first vibration body in the Y-axis direction ;
Of the second vibrating body by the angular velocity about the Z axis
A first vibration detector that detects the magnitude of the vibration in the X-axis direction, and a second vibration detector that detects the magnitude of the vibration in the Z-axis direction of the third vibrating body due to the angular velocity around the X axis . And a vibration detector.

[0008]

The vibration exciter of the first vibrating body is driven to vibrate the first vibrating body in the Y-axis direction. Of the sensor substrate in this state
When an angular velocity is applied around the Z-axis , the Z-axis direction and the first
Coriolis force acts in the X-axis direction that is orthogonal to the vibration direction of the vibrating body, and the vibration in the direction of the Coriolis force is applied to the second vibrating body, and the second vibrating body vibrates in the direction of the Coriolis force.
Then, when an angular velocity about the X-axis is applied, Oyo the X-axis direction
And a Coriolis force acts in the Z-axis direction orthogonal to the vibration direction of the first vibrating body, and a vibration in the direction of the Coriolis force is applied to the third vibrating body, and the third vibrating body vibrates in the direction of the Coriolis force. I do. The magnitude of vibration of the second vibrating body is measured by a first vibration detector, the angular velocity around the Z axis is detected, and the magnitude of vibration of a third vibrating body is measured by a second vibration detector. By measuring, the angular velocity around the X axis is detected.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an angular velocity sensor according to the present embodiment. In this embodiment, an angular velocity sensor 20 for detecting an angular velocity about two axes is formed by utilizing the technology of semiconductor microfabrication of silicon. In FIG. 1, an upper substrate 13 made of polysilicon or the like is supported by a support frame 12 made of an oxide film or the like via a gap 8 on a sensor substrate 11 made of a square silicon material or the like. A first vibrating body 10 is formed on the upper substrate 13. The first vibrating body 10 has a first rotation axis direction (for example, a Z-axis direction) of the sensor substrate 11 and the first vibration body. The direction (X) orthogonal to the vibration direction (Y-axis direction) of the body 10
A second vibrating body 16 that vibrates in the axial direction) and has the same resonance frequency as the first vibrating body 10, and a second rotational axis direction different from the first rotational axis direction (Z-axis direction). (For example, in the X-axis direction) and in the direction (Z-axis direction) orthogonal to the vibration direction (Y-axis direction) of the first vibrating body 10, and the first vibrating body 10
A third vibrating body 17 having the same resonance frequency as 10 is formed by a semiconductor fine processing technique.

At the left and right edge portions of the upper substrate 13, a comb-shaped electrode 9A having a plurality of indentations projecting inward is fixedly arranged, and the first electrode 9A at a position facing the comb-shaped electrode 9A is fixed.
On the vibrating body 10 side, a movable comb-shaped electrode 9B meshing with the comb-shaped electrode 9A is arranged via a gap, and the comb-shaped electrodes 9A and 9B function as a vibration exciter 14 of the first vibrating body 10. ing. When an AC voltage is applied to the comb-shaped electrodes 9A and 9B, the first vibrating body 10 is configured to vibrate in the Y-axis direction by electrostatic force generated in the comb-shaped electrodes 9A and 9B. By using such a comb-shaped electrode, an element formed on a Si substrate can be vibrated with a relatively large amplitude, and the sensitivity as an angular velocity sensor can be improved.

Further, on both sides of the second vibrating body 16 (in the front-back direction of the paper surface of FIG. 1A), a movable comb-shaped electrode 19B is provided on the second vibrating body 16 to face the comb-shaped electrode 19B. The comb-shaped electrode 19A is provided on the side of the first vibrating body 10 where the
The comb electrodes 19A and 19B are arranged with a gap therebetween so as to mesh with B, and function as a first vibration detector 15 for detecting the magnitude of vibration of the second vibrating body 16.

Further, as shown in FIG.
A conductive electrode 18 doped with, for example, boron or phosphorus is provided below the third vibrator 17 via a gap 21.
The conductive electrode 18 functions as a second vibration detector 22 for detecting the magnitude of vibration of the third vibrating body 17 in the Z-axis direction. The second vibration detector 22 detects the magnitude of the vibration in the Z-axis direction of the third vibrator by measuring the change in the capacitance between the third vibrator 17 and the conductive electrode 18. Things.

Further, a necessary number of conductor patterns are formed at appropriate positions on the sensor substrate 11 and the upper substrate 13, and an alternating current is supplied to the comb-shaped electrodes 9 A and 9 B from a driving unit such as a power supply (not shown) by the conductor patterns. Is applied. Further, the comb-shaped electrodes 19A and 19B, the third vibrating body 17 and the conductive electrode 18 are also connected to external pads (not shown) via conductor patterns, and detection signals of each vibrating body are taken out via these conductor patterns. It has become.

Next, the operation of detecting the angular velocity of the angular velocity sensor 20 of the present embodiment will be described with reference to FIGS. First, an AC voltage is applied to the comb-shaped electrodes 9A and 9B by driving a driving unit (not shown), and the first vibrating body 10 is moved in the Y-axis direction (horizontal direction on the paper surface of FIG. 1A) by electrostatic attraction. Vibrate. In this state, if an angular velocity is applied around the Z axis of the sensor substrate 11 ,
As shown in FIG. 2, a direction (X) that is orthogonal to both the rotation axis (Z axis) direction and the vibration direction (Y axis direction) of the first vibrating body 10
(Axial direction), a Coriolis force is generated, and a vibration in the direction of the Coriolis force is applied to the second vibrating body 16.
Vibrates in the axial direction. The second vibrator by this Coriolis force
The magnitude of the vibration in the X-axis direction of 16 is measured as a change in capacitance by the comb-shaped electrodes 19A and 19B of the first vibration detector 15,
An angular velocity around the Z axis is detected.

When an angular velocity is applied around the X-axis, FIG.
As it is shown in the rotating shaft (X-axis) direction and the first vibrator
Coriolis force is generated in a direction (Z-axis direction) that is orthogonal to both the vibration directions (Y-axis direction) of 10, and a vibration in the direction of the Coriolis force is applied to the third vibrating body 17. Vibrates in the Z-axis direction. The magnitude of the vibration in the Z-axis direction of the Coriolis force due to the third vibrator 17, as shown in (b) of FIG. 1, taken as a change in capacitance between the third vibrator 17 and the electrode 18, The capacitance change is measured by the second vibration detector 22, and the angular velocity around the X axis is detected from the measured value. Thus, the angular velocity sensor 20 of the present embodiment detects angular velocities about two axes, that is, an angular velocity about the X axis and an angular velocity about the Z axis.

According to the present embodiment, the angular velocity sensor around two axes is formed on the sensor substrate by utilizing the semiconductor fine processing technology.
There is no need to perform a troublesome assembling operation such as welding or screwing as in the case of manufacturing .

Further, since the angular velocity sensor of this embodiment does not require machining as in the prior art and is manufactured by utilizing the semiconductor fine processing technology, it is very small, the cost is low, and the mass productivity is excellent. I have.

The present invention is not limited to the above embodiment, but can take various embodiments. For example, in the above-described embodiment, the vibration detection of the second vibrating body 16 and the third vibrating body 17 is detected by measuring the capacitance.
A piezoelectric film may be formed at the base of the beams of the vibrators 16 and 17 and a detection method utilizing the piezoelectric effect may be used. Any method capable of measuring the magnitude of vibration of the vibrator may be used. Absent.

In the above embodiment, the three vibrating members 10,
Although the shapes 16 and 17 are fixed at both ends, the shapes may be all cantilevered, some may be cantilevered, and the rest may be fixed at both ends.

Further, in the above embodiment, the rotation axis of the sensor substrate is set to two orthogonal axes of the X axis and the Z axis, but the rotation axis may be set to two axes of the cross axis. In this case, since the detection in the axial direction is separated as compared with the conventional example, there is no mixed vibration, the detection sensitivity and the detection accuracy are significantly improved, and the detection performance is improved. Before Kifu body 10, the vibrating body 16, although the vibration member 17 vibrates at the same resonance frequency, three resonant frequencies of the vibrator, respectively, may be shifted slightly.

[0021]

According to the present invention, by using a semiconductor microfabrication technology, since the structure which forms the angular velocity sensor about two axes in the sensor substrate, as in the prior art, making the vibration of H shape
It is not necessary to perform troublesome assembling work such as welding or screwing as in the case of performing.

Further, since the angular velocity sensor of the present invention is manufactured by utilizing the semiconductor fine processing technology without the need for mechanical processing as in the prior art, it is ultra-compact, inexpensive, and excellent in mass productivity. .

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of an angular velocity detection operation when the angular velocity sensor is rotated around a Z axis as a rotation axis in the embodiment.

FIG. 3 is an explanatory diagram of an angular velocity detecting operation when the angular velocity sensor according to the present embodiment is rotated around the X axis as a rotation axis.

FIG. 4 is an explanatory diagram of a conventional angular velocity sensor that detects angular velocity around two axes.

[Explanation of symbols]

 10 First vibrator 14 Vibration exciter for first vibrator 15 First vibration detector 16 Second vibrator 17 Third vibrator 22 Second vibration detector

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoho Hasegawa 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Inside Murata Manufacturing Co., Ltd. (72) Katsuhiko Tanaka 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto In Murata Manufacturing Co., Ltd. (56) References JP-A-5-248875 (JP, A) JP-A-2-129513 (JP, A) JP-A-2-198315 (JP, A) JP-A-5-333038 (JP, A) JP-A-5-248772 (JP, A) JP-A-5-312576 (JP, A) JP-A-6-281665 (JP, A) JP-A-5-248874 (JP, A) 58-221109 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01P 9/04 G01C 19/56

Claims (1)

(57) [Claims] To 1. A sensor substrate, orthogonal sensor substrate surface
A first vibrating body that vibrates in the Y-axis direction of the X-axis and the Y-axis is formed, and the first vibrating body includes the X-axis direction.
A second vibrating body that vibrates in a direction, and a third vibrating body that vibrates in a Z-axis direction perpendicular to the X axis and the Y axis and perpendicular to the surface of the sensor substrate. , The first vibrating body
A vibration exciter to vibrate in the Y-axis direction, the Z Jikukai
X-axis direction of the second vibrating body due to angular velocity applied to the
A first vibration detector for detecting a magnitude of vibration of direction, the
Wherein said by the angular velocity according to the X-axis third vibrator
An angular velocity sensor provided with a second vibration detector for detecting the magnitude of vibration in the Z-axis direction .