JP3303379B2 - 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 of a moving body.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show a generally known angular velocity sensor. In FIG. 6, the piezoelectric elements 5a and 5b for excitation are opposed to one opposing side of the vibrator 4 having a square prism, and the piezoelectric elements 6a and 6b for detection are opposing to the other opposing side. Affixed facing each other.
When the vibrator 4 is vibrated by the excitation piezoelectric elements 5a and 5b and the vibrator 4 rotates around the Z axis in this state, Coriolis force is generated in a direction perpendicular to the excitation direction. The resultant force of this Coriolis force and the force in the excitation direction is the detection piezoelectric elements 6a and 6b.
, One of the detecting piezoelectric elements 6a and 6b is extended and the other is contracted. The detecting piezoelectric elements 6a, 6b
Is output as an angular velocity detection signal.

FIG. 5 shows the structure of Japanese Patent Application Laid-Open No. 61-141141.
Those disclosed in 23 JP, quadrangular prism vibrator 4 and the fixed portion 14a, and 14b are formed by using a semiconductor microfabrication technology in the semiconductor substrate 3 such as silicon, the fixed portion 14
a, 14b is attached on a table 13 such as a glass material, the vibrator 4 is in a state had floating so as to be freely vibrating. An electrode component 15 including a vibration exciter and an electrode component 16 including a vibration detector are arranged near the vibrator 4. These electrode parts 15 and 16 are formed by forming a semiconductor substrate into a shape as shown in the figure, and affixing respective electrodes (not shown) orthogonally to a surface facing the vibrator 4.

[0004] In the conventional example of FIG. 6, exciting the piezoelectric element 5
The piezoelectric elements a and 5b and the detecting piezoelectric elements 6a and 6b perform vibration excitation and angular velocity detection by using a change in voltage. However, in the conventional example of FIG. Vibration excitation and angular velocity detection are performed using the change in capacitance.
The operation of detecting the angular velocity is performed according to the same principle as in FIG .

[0005]

However, in the case of the angular velocity sensor shown in FIG. 6, high precision processing is difficult because it is manufactured by machining, and the vibrator 4 cannot be formed into a square prism with high dimensional accuracy, In many cases, the piezoelectric elements 5 and 6 were attached with their positions shifted. In such a case, if an excitation signal is applied to the vibrator 4 even in a stationary state, the voltage of the detecting piezoelectric elements 6a and 6b does not become zero, and a leak output is detected. There is a problem that the / N ratio is reduced. Such leakage output is reduced,
In order to manufacture a high-sensitivity, low-drift angular velocity sensor, the vibrator must be machined with high precision and precise assembly adjustments must be made. It became something. In addition, since this angular velocity sensor is manufactured by machining, there has been a problem that miniaturization is difficult due to restrictions on assembly technology.

Further, in the case of the angular velocity sensor shown in FIG. 5, since it is manufactured using a semiconductor fine processing technique, it is much smaller than that shown in FIG. 6, and is manufactured with high dimensional accuracy and high accuracy. However, there were the following problems. That is, in this angular velocity sensor, the electrode of the electrode component 15 as the vibration exciter and the electrode of the electrode component 16 as the vibration detector are orthogonal to each other, and each electrode of these electrode components 15 and 16 faces the vibrator 4. Because it must be arranged
The electrode parts 15, 16 and the vibrator 4 have a three-dimensional shape, and it has been difficult to manufacture these electrode parts 15, 16 and the vibrator 4 at one time by a semiconductor processing technique.

Therefore, after the electrode parts 15 and 16 are formed in separate steps, the electrode parts 15 and 16 are arranged so that the electrodes are orthogonal to each other.
A troublesome assembling operation of disposing the devices 16 and 16 near the vibrator 4 was required in the final step. Therefore, there has been a problem that the mass productivity is low and the cost is high.

Further, in this prior art example, on pedestal 13, since the mounting of each portion 4,14,15,16 formed as described above, miniaturization of the entire sensor is difficult, and for this reason
Further miniaturization by a new sensor structure has been desired.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a small-sized and high-precision angular velocity sensor which is excellent in mass productivity.

[0010]

The present invention is configured as follows to achieve the above object. In other words, the
Angular velocity sensor 1 of the invention includes a first beam and a second beam fixed at both ends are formed to cross at right angles to the base plate, the cross fixing portion of the first beam and the second beam oscillation child is provided on at least one side of the first beam and the second beam perpendicular to the substrate the beam
A vibration exciter that excites the vibrator by vibrating in a direction is provided, and at least the other side of the first beam and the second beam is provided with a base of the beam due to Coriolis force applied to the vibrator by angular velocity.
A vibration detector for detecting vibration in a direction perpendicular to the plate is provided.

According to a second aspect of the present invention, there is provided the angular velocity sensor according to the first aspect.
In the apparatus having the configuration of the present invention, the vibration exciter is used for beam exchange.
They are provided on both sides of the difference fixing part,
AC excitation signal with 180 degree phase difference for dynamic exciter
To apply a beam to the beam provided with the vibration exciter,
It is characterized by vibrating in the secondary mode with a point
I do.

According to a third aspect of the present invention, there is provided the angular velocity sensor according to the first aspect.
In the apparatus having the configuration of the present invention, the vibration exciter is used for beam exchange.
They are provided on both sides of the difference fixing part,
Vibration excitation by applying AC excitation signal of the same phase to the dynamic exciter
In the primary mode with the beam provided with the vessel as the fulcrum at both ends
It is characterized by vibrating.

The angular velocity sensor according to a fourth aspect of the present invention is the above-described angular velocity sensor.
Is provided with the configuration of the second or third invention, and
Excitation of the beam and beam
It has a configuration that also has the function of detecting vibration.
You.

According to a fifth aspect of the present invention, there is provided the angular velocity sensor according to the first to fourth aspects.
4. The apparatus according to claim 4, wherein
The feature is that a piezoelectric element is used as the exciter.
I do.

[0015]

The first beam and the second beam are formed at right angles to each other, and the vibrator is provided at the cross-fixed portion. Therefore, one of the beams provided with the vibration exciter is connected to the vibration exciter. The vibrator vibrates in the direction perpendicular to the substrate by the excitation signal, and in this state, for example, when it rotates around an axis orthogonal to both beams, Coriolis force is generated in the vibrator, and the vibrator vibrates in this force direction. The vibration is transmitted to the beam provided with the vibration detector, and the vibration is detected by the vibration detector and output as an angular velocity signal.

Further , the vibration exciter is sandwiched between the intersection fixing portions of the beams.
For those provided on both sides of the surface, the vibration exciter
AC excitation signal with 180 degree phase difference
This causes the beam to oscillate in the second mode and
The beam is excited in first-order mode by applying the excitation signal
Move.

Further, a vibration exciter and a vibration detector are provided.
By using a piezoelectric element of the same configuration
An angular velocity sensor having one as a rotation axis can be used.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of an embodiment of an angular velocity sensor according to the present invention.

In FIG. 1, a semiconductor substrate 3 such as silicon
, Square holes C, D, E, and F are opened, and a first beam 1 and a second beam 2 having the same length are formed in an orthogonal state. On the back side of the cross fixing portion 18 of both the beams 1 and 2, as shown in FIG. (B), the vibrator 4 is formed to protrude. The mounting portion of the vibrator 4 in contact with the intersection fixing portion 18 is
Intersecting fixed part 18 indicated by beam width of first beam 1 and second beam 2
The size is almost the same as the area of.

Vibration exciters 5a and 5b are arranged on both side surfaces of the first beam 1 around the intersection fixing portion 18, and vibration detectors 6a and 6b are arranged on both side surfaces of the second beam 2. Has been established. These vibration exciters 5a and 5b and vibration detector 6
The piezoelectric elements a and 6b are formed as piezoelectric elements having a zinc oxide thin film 8 interposed between the electrodes 7a and 7b. A base 3a is formed on the outer peripheral side of the back surface of the substrate 3 higher than the vibrator 4, and serves as a support for the angular velocity sensor.

FIG. 3 shows a manufacturing process of the angular velocity sensor according to the present embodiment having the above configuration. In the left column of FIG.
1. The manufacturing process of the AA cross section of FIG.
The manufacturing process of the cross section is shown. First, on both surfaces of the semiconductor substrate 3 such as a silicon wafer, as shown in FIG. 3 (a), a silicon oxide film 9 is formed by thermal oxidation or the like. Then, the four positions of the portions forming a vibration exciter 5 or vibration detector 6, as shown in FIG. (B), a zinc oxide thin film 8 as a piezoelectric thin film on an electrode 7a, the thin film 8 The electrodes 8b are respectively formed on the upper portions by sputtering or the like.

Next, as shown in FIG. 2C, a resist 17 is applied as a mask on the surface of the substrate 3 on which the piezoelectric elements 5a, 5b, 6a and 6b are disposed, and as shown in FIG. as such, to remove only the depth h corresponding holes C by dry etching, D, E, a portion corresponding to F to the thickness of the beam 1 and 2. Next, the resist 17 is removed, and a protective film 10 such as silicon oxide is formed on the surface of the substrate 3 by a plasma CVD process or the like as shown in FIG. The silicon oxide 9 is left as a mask necessary for forming the base 3a, and the silicon oxide 9 is removed by etching. Next, the remaining portion of the dry etching is anisotropically etched from the back surface of the substrate 3 with an etching solution such as potassium hydroxide or the like , and the vibrator 4, the base 3a, Beams 1 and 2 are formed.

This embodiment is configured as described above .
Next, the operation of detecting the angular velocity will be described with reference to FIG. When an excitation signal as an AC voltage having a phase difference of 180 ° is applied to each of the vibration exciters 5a and 5b, the first beam 1
Is a direction perpendicular to the semiconductor substrate 3 as indicated by G and G 'in FIG.
The vibrator 4 vibrates in the axial direction of the beam 1 at the lower end side of the vibrator 4 with the intersection fixing portion 18 as a fulcrum.

In this state, the angular velocity sensor is mounted on the substrate surface.
When it rotates around the Z axis which is a rotation axis perpendicular to the
Then, a Coriolis force is generated in a direction perpendicular to the excitation direction, and the lower end of the vibrator 4 vibrates in the direction of the Coriolis force . This vibration is transmitted to the second beam 2, and the beam 2 crosses and is fixed in the direction perpendicular to the substrate indicated by H and H 'as shown in FIG.
It vibrates in the secondary mode with the part 18 as a node . This vibration produces distortion opposite to each other in each of the piezoelectric thin film 8 of the vibration detector 6a and 6b provided on the beam 2, the output resulting voltage difference between the vibration detector 6a and 6b as a detection signal of the angular velocity Is done.

According to this embodiment, each part of the angular velocity sensor, that is, the vibrator 4, the vibration exciter 5, the vibration detector 6
The beams 1, 2 and the like can all be formed using semiconductor fine processing technology. Therefore, the angular velocity sensor can be formed with high precision and a small size. Also, as in the conventional example, the electrode component 1
Since it is not necessary to assemble and attach the substrates 5 and 16 to the semiconductor substrate 3, the operation is labor-saving and suitable for mass production. Therefore, cost reduction is achieved.

Further, since the vibration exciter 5 and the vibration detector 6 are arranged at positions separated from each other in a right angle direction, the vibration exciter 5
Drift generated in the vibration detector 6 due to the excitation
The Coriolis force acting on the vibrator 4 is suppressed by other influences such as drift and noise, as compared with a conventional vibration exciter 5 and a vibration detector 6 which are disposed on the same vibrator 4. Therefore, the angular velocity signal can be detected with high accuracy.

Furthermore, since the detection of the angular velocity is performed by using the vibration detector 6a and 6b Tonoden pressure difference, the vibration detector 6a by the temperature change, the influence of the 6b is canceled even if the change in temperature occurs Therefore, the temperature is compensated, and the temperature is not adversely affected.

In the above embodiment, an example was described in which a secondary mode AC signal was applied to the vibration exciter 5, but the first beam 1
As shown at J and J 'in FIG. 4, both ends of the beam 1 are used as fulcrums.
Excitation signals having the same phase may be applied to the vibration exciters 5a and 5b so as to vibrate in the primary mode in a direction perpendicular to the substrate . In this case, the vibrator 4 moves up and down in the primary mode. In this state, when the beam 1 is set as the Y axis of the rotation axis and the angular velocity sensor is rotated around the Y axis, the vibrator 4 moves in the direction of the second beam 2. A Coriolis force is generated, and the beam 2 expands and contracts, and the vibration detectors 6a and 6
It is generated voltage difference between the b. And it outputs the voltage difference as a detection signal of the angular velocity around the Y axis.

Further , the vibration exciters 5a and 5b are
Is provided, the vibrator 4 is excited by the vibration exciters 5a and 5b of the second beam 2 , and the angular velocity around the X axis is set on the first beam 1. in the same manner as described above corner by detecting the vibration detector 6a, 6b to be
Speed can be detected.

The first beam 1 and the second beam 2 have the same structure.
Forming the piezoelectric element 5a, provided 5b, 6a, and 6b, by having both the functions of the respectively vibration exciter vibration detector, the detection of the angular velocity about the Y-axis and X-axis simultaneously.

The present invention is not limited to the above embodiments, but can take various embodiments. For example, in the above embodiment, the first beam 1 and the second beam 2 are formed in the same size, but may be formed in different sizes. Further, although a silicon material is used as the semiconductor substrate 3, another single crystal substrate such as a quartz crystal may be used.

Further, the shapes of the vibrator 4 and the base 3a can be changed according to the specifications.

Further, the piezoelectric elements 5a, 5b, 6a, 6b
Was formed using the zinc oxide thin film 8, but other materials,
For example, it may be formed using a ceramic piezoelectric material.

[0034]

According to the present invention, the first beam and the second vibrator intersection fixing part is provided beam, a substrate a beam provided with a front Kihari the vibration exciter and the vibration detector perpendicular And perpendicular to
Because it was configured to vibrate , using the semiconductor fine processing technology ,
The whole of each part such as each beam, vibrator, vibration exciter, vibration detector and the like can be formed. Therefore, the angular velocity sensor of the present invention can be miniaturized with high accuracy.

In addition, since there is no complicated assembling work as in the prior art, and all are formed in a semiconductor fine processing step, mass production is achieved and cost is reduced.

Furthermore, the vibration exciter and the vibration detector for respectively disposed on another beam 1 or beam 2 Re <br/>, conventional same vibrator vibration exciter and the vibration detector as Since the Coriolis force acting on the vibrator can be detected separately from other influences such as drift and noise, the S / N ratio of the angular velocity signal can be increased .

[Brief description of the drawings]

FIG. 1 shows an embodiment of an angular velocity sensor according to the present invention ,
(A) is a plan view, (b) is an AA cross-sectional view .

FIG. 2 shows a secondary mode of the angular velocity sensor in the embodiment of FIG .
A dynamic Sakusetsu explanatory view showing the excitation of the de.

3 is an explanatory view showing the manufacturing process of the angular velocity sensor shown in the embodiment of FIG.

4 is a dynamic Sakusetsu explanatory view showing the excitation of the primary mode of the angular velocity sensor according to the embodiment of FIG.

FIG. 5 is an explanatory view showing a conventional example of an angular velocity sensor provided on a semiconductor substrate.

FIG. 6 is an explanatory view showing a conventional example of an angular velocity sensor using a square prism vibrator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st beam 2 2nd beam 3 Substrate 4 Vibrator 5a, 5b Vibration exciter 6a, 6b Vibration detector 18 Cross fixing part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01P 9/04 G01C 19/56

Claims (5)

(57) [Claims] 1. A a first beam and a second beam at both ends fixed to the base plate is formed to intersect at right angles, the transducer is provided at the intersection fixing portion of the first beam and the second beam A vibration exciter that excites the beam in a direction perpendicular to the substrate and vibrates the vibrator is provided on at least one side of the first beam and the second beam. At least the other side of the beam is perpendicular to the beam substrate due to Coriolis force applied to the vibrator by angular velocity
That vibration detector for detecting vibration of the direction are provided
Characteristic angular velocity sensor. 2. A vibration exciter is provided on both sides of a cross-fixed portion of a beam.
Provided on each surface, and 180
Vibration excitation by applying an AC excitation signal with a phase difference of degrees
Mode with the beam provided with the vessel as the node at the intersection fixed part
2. The angular velocity sensor according to claim 1, wherein
Sensor. 3. A vibration exciter is provided on both sides of a cross-fixed portion of a beam.
Are provided on the surface, respectively.
By applying an AC excitation signal, the beam provided with the vibration exciter is
It is characterized by vibrating in the primary mode with its both ends as fulcrums.
The angular velocity sensor according to claim 1, wherein 4. A vibration exciter and a vibration detector, respectively.
Specially, it has both functions of beam excitation and beam vibration detection.
The corner according to claim 1 or claim 2 or claim 3 as a feature.
Speed sensor. 5. Use of a piezoelectric element as a vibration exciter
The method according to any one of claims 1 to 4, wherein
On-board angular velocity sensor.