JP2002243450A - Angular velocity sensor, acceleration sensor and angular velocity/acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular velocity sensor having a simple structure and capable of detecting angular velocity with high sensitivity. SOLUTION: In the angular velocity sensor 10, a weight attaching part 13a and a weight 14 are combined at the central region of a vibrator 12 to form a superposed part consisting of the weight attaching part 13a and the weight 14 and four vibration generation members 15a-15d are integrally provided to four arm parts 13c1-13c4 in order to vibrate the superposed part through four torsion spring arts 13b1-13b4 and four arm parts 13c1-13c4 while four vibration detection members 16a-16d are integrally provided to four torsion spring parts 13a and 14 in order to detect the Coriolis force applied to the superposed part consisting of the weight attaching part 13a and the weight 14 when angular velocity is applied to calculate the angular velocity. The respective outputs of four vibration detection members 16a-16d are combined to perform addition and subtraction to detect the angular velocities in X-axis and Y-axis directions.

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 Coriolis force generated by an angular velocity applied to a weight of a vibrator to obtain an angular velocity, and a force due to acceleration applied to a weight of a vibrator. And an acceleration sensor for obtaining acceleration.

[0002]

2. Description of the Related Art In recent years, the use of airbags for safety and GPS devices for car navigation has been increasing in automobiles. In order to operate the airbag, an acceleration sensor capable of measuring an impact at the time of an accident is required, and an angular velocity sensor such as a gyro is required for the GPS device. In order to operate these acceleration sensors and angular velocity sensors more accurately, it is indispensable to further improve the performance and to manufacture them at a lower cost so that they can be mounted on all types of vehicles. Acceleration sensors are used not only for automobiles but also for impact detection of precision electronic equipment.Angle velocity sensors are used to detect camera shake in video cameras, ships, missiles,
It is also used for attitude control of robots, etc., and has a wide range of applications.

[0003] These acceleration sensors and angular velocity sensors are:
2. Description of the Related Art Technology development by processing a Si (silicon) substrate using a micromachine technology is actively performed. Further, these acceleration sensors and angular velocity sensors can use the manufacturing equipment used for semiconductors and can perform batch processing collectively, thereby improving production efficiency and reducing costs. Further, Si
Since the substrate is used, the sensor and the IC circuit
There is also an advantage that it can be formed on a substrate.
These studies are described, for example, in Journal of Precision Engineering Vol. 62.
No. 1.1996, “Current Status of Micromachining and New Trends” (authored by Masayoshi Esashi).

Here, as a conventional example of an acceleration sensor manufactured by the micromachine technology, a report example of “Sensor / Micromachine and Application System Symposium” (May 2000; IEEJ) is shown in FIGS. 11 and 12 (A). , (B).

FIG. 11 is an exploded perspective view showing a conventional acceleration sensor in an exploded manner, and FIG. 12 is a view for explaining the operation of the conventional acceleration sensor. FIG. 11A shows an X-axis direction (Y-axis direction). (B) is a diagram showing the operation in the Z-axis direction.

A conventional acceleration sensor 100 shown in FIG.
Has been developed by Masayoshi Tohoku Osashi et al. The acceleration sensor 100 has a lower glass 101,
An SiO substrate 102 in which a weight portion 102a formed in a central portion is suspended by an X-shaped Si beam beam 102b, and an upper glass 103 are laminated in three layers from the bottom in this order.

Here, X, Y,
Six Al electrodes 101a for detecting acceleration in the Z-axis direction
And a field through electrode 101b. A weight portion 102a is swingably suspended by a X-shaped Si beam beam 102b at a central portion in the SiO substrate 102. At this time, the X-shaped Si beam beam 102b is hollowed out so as to be displaceable.
The Si electrode 102c is located near the V-shaped Si beam beam 102b.
Is filmed. The upper glass 103 is for sealing the inside.

The conventional acceleration sensor 100 is configured such that the weight portion 1 in the SiO substrate 102 is
When an acceleration is applied to 02a, the interelectrode capacitance (= capacity between the Al electrode 101a and the Si electrode 102c) changes, and the acceleration is obtained from the capacitance difference generated there. On the other hand, as shown in FIG. 12A, the weight portion 102a is displaced in the Fx direction (or the Fy direction) via the X-shaped Si beam beam 102b, and in FIG. As shown in FIG.
Since it is displaced in the Fz direction via the i-beam 102b,
It functions as a three-axis acceleration sensor.

[0009]

The conventional acceleration sensor 100 described above can be miniaturized because the SiO substrate 102 is manufactured by the micromachine technology, but the displacement of the weight portion 102a due to external force is small.
Difficult to increase sensitivity. For this reason, it is necessary to use the capacitance change as the acceleration detecting means.
01 and the SiO substrate 102 must be separately provided with electrodes, and furthermore, an upper glass 103 for sealing is further provided.
Therefore, there is a problem that the structure of the acceleration sensor 100 is complicated, and the man-hours required for manufacturing the acceleration sensor 100 are large.

Further, the conventional acceleration sensor 100 is only for acceleration detection, and if it is configured to detect angular velocity, the structure becomes more complicated.

Therefore, a two-axis angular velocity sensor capable of detecting angular velocity at low cost and high sensitivity by a relatively simple structure is provided. Similarly, a three-axis angular velocity sensor capable of detecting acceleration at low cost and high sensitivity is provided. There is a need for an axial acceleration sensor. Further, there is a demand for an angular velocity / acceleration sensor that can detect angular velocity and acceleration at low cost and with high sensitivity.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a first invention is directed to a fixing member serving as a base, and a three-dimensional orthogonal coordinate space provided at a central portion in the fixing member. XYZ axes are temporarily set, and a weight portion is provided so that the center of gravity is substantially located on the Z axis passing through the intersection of the three axes, and a total of four torsion springs of two pairs opposing each other from above the weight portion. Extending outwardly substantially symmetrically with respect to the X-axis and the Y-axis and substantially parallel to the X-axis, and a total of four from each of the four distal end portions of the four torsion spring portions. Of the four arm portions extend outward substantially in parallel to the Y axis substantially symmetrically with respect to the Y axis and the X axis, and further, each extended end portion of the four arm portions is fixed to the fixing member. Vibrators fixed to the opposing side surfaces of the When the angular velocity is applied to the four torsional spring portions and the four arm portions, the four vibrating members provided integrally with the four arm portions are used to vibrate the portion through the four torsion spring portions and the four arm portions. In order to detect the Coriolis force applied to the weight portion and obtain the angular velocity, the four torsion spring portions are provided with four vibration detection members integrally provided, respectively, and when the angular velocity is detected, the four vibration detection members are provided. The angular velocity sensor is characterized in that the vibration generating member is driven, and the outputs of the four vibration detecting members are combined to perform addition and subtraction, thereby detecting the angular velocities in the X-axis direction and the Y-axis direction.

According to a second aspect of the present invention, a fixed member serving as a base and an XYZ axis of a three-dimensional orthogonal coordinate space are temporarily set at a central portion in the fixed member, and a Z-axis whose center of gravity passes through an intersection of the three axes. A weight portion is provided so as to be located substantially above, and a total of four torsion spring portions in two pairs facing each other from above the weight portion are substantially symmetric with respect to the X axis and the Y axis, and A total of four arms are extended from the respective distal end portions of the four torsion springs extending substantially parallel outward.
And extending outwardly in a direction substantially parallel to the axis and the X-axis and substantially parallel to the Y-axis. And four vibration detectors provided integrally with the four torsion springs to detect the force applied to the weight when acceleration is applied and to obtain the acceleration. And an acceleration sensor for detecting the acceleration in the X-axis direction, the Y-axis direction, and the Z-axis direction by combining and adding and subtracting the outputs of the four vibration detection members.

According to a third aspect of the present invention, a fixed member serving as a base and an XYZ axis of a three-dimensional orthogonal coordinate space are temporarily set at a central portion in the fixed member, and a Z-axis whose center of gravity passes through an intersection of the three axes. A weight portion is provided so as to be located substantially above, and a total of four torsion spring portions in two pairs facing each other from above the weight portion are substantially symmetric with respect to the X axis and the Y axis, and A total of four arms are extended from the respective distal end portions of the four torsion springs extending substantially parallel outward.
And extending outwardly in a direction substantially parallel to the axis and the X-axis and substantially parallel to the Y-axis. In order to vibrate the weight portion via the four torsion spring portions and the four arm portions by applying a voltage having a substantially constant period to the vibrators respectively fixed to the four arm portions, Four vibration generating members provided integrally with each other,
To determine the angular velocity by detecting the Coriolis force applied to the weight when the angular velocity is applied, and to determine the acceleration by detecting the force applied to the weight when the acceleration is applied,
Four vibration detecting members provided integrally with the four torsion spring portions, and DC change generating means for obtaining a DC change from each output of the four vibration detecting members, When detecting the angular velocities in a state where the four vibration generating members are driven, the outputs of the four vibration detecting members are combined and added and subtracted to detect the angular velocities in the X-axis direction and the Y-axis direction. On the other hand, when detecting acceleration while driving the four vibration generating members, the DC
An angular velocity / acceleration sensor characterized by detecting accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction by combining and subtracting the outputs of the change generation means.

In a fourth aspect of the present invention, a fixed member serving as a base and an XYZ axis of a three-dimensional orthogonal coordinate space are temporarily set at a central portion in the fixed member, and a Z-axis whose center of gravity passes through an intersection of the three axes. A weight portion is provided so as to be located substantially above, and a total of four torsion spring portions in two pairs facing each other from above the weight portion are substantially symmetric with respect to the X axis and the Y axis, and A total of four arms are extended from the respective distal end portions of the four torsion springs extending substantially parallel outward.
And extending outwardly in a direction substantially parallel to the axis and the X-axis and substantially parallel to the Y-axis. In order to vibrate the weight portion via the four torsion spring portions and the four arm portions by applying a voltage having a substantially constant period to the vibrators respectively fixed to the four arm portions, Four vibration generating members provided integrally with each other,
To determine the angular velocity by detecting the Coriolis force applied to the weight when the angular velocity is applied, and to determine the acceleration by detecting the force applied to the weight when the acceleration is applied,
Four vibration detecting members provided integrally with the four torsion spring portions, the four vibration generating members are driven when detecting angular velocity, and the four vibration generating members are non-driven when detecting acceleration. Switching means for driving, and detecting the angular velocity in the X-axis direction and the Y-axis direction by combining and subtracting the outputs of the four vibration detection members, or An angular velocity / acceleration sensor that detects acceleration in the direction and the Z-axis direction.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an angular velocity sensor, an acceleration sensor and an angular velocity / acceleration sensor according to the present invention will be described below in detail in the order of items with reference to FIGS.

<Angular Velocity Sensor> FIG. 1 is a perspective view showing an angular velocity sensor according to the present invention. FIG. 2 is a diagram showing four torsional screws formed on the vibration member when the Si substrate is used for the vibration member shown in FIG. FIG. 3 is an enlarged cross-sectional view showing a vibration generating member and a vibration detecting member formed on the resilient portion and the four arm portions, respectively. FIG. 3 shows a case where a piezoelectric crystal material substrate is used for the vibration member shown in FIG. FIG. 4 is an enlarged cross-sectional view of a vibration generating member and a vibration detecting member formed on the four torsion spring portions and the four arm portions formed on the vibration member. In this angular velocity sensor, it is a figure which was shown typically in order to explain operation of a vibrator, and (A) shows X-axis direction component CF of Coriolis force CF in a weight fixed to a vibration member.
(B) shows a state in which the Y-axis direction component CFy of the Coriolis force CF is applied to a weight fixed to the vibration member, and FIG. 5 shows an angular velocity sensor according to a modification of the present invention. It is the perspective view shown.

As shown in FIG. 1, in the angular velocity sensor 10 according to the present invention, the fixing member 11 serving as a base is formed in a substantially rectangular parallelepiped shape using a rigid material, and is fixed to the side surfaces facing each other. A concave portion 11c is formed inside by hollowing out the space between the portions 11a and 11b. Here, the XYZ of the three-dimensional orthogonal coordinate space is added to the central portion in the fixed member 11.
A description will be given below by temporarily setting the axes.

A vibrator 12 is swingably mounted on the side fixing portions 11a and 11b of the fixing member 11 facing each other.

The above-described vibrator 12 has a weight mounting portion 13a formed in a substantially rectangular shape at the center of a vibration member 13 using a thin Si substrate (Si wafer).
a, a substantially rectangular weight 14 is integrally fixed to the back surface of the a.
The side enters the recess 11 c of the fixing member 11. At this time, the weight of the weight mounting portion 13a and the weight 14 is combined so that the center of gravity G is the intersection of three axes (hereinafter referred to as the origin) O.
Are provided so as to be located substantially on a Z-axis passing through, and the Z-axis corresponds to the direction of gravity.

When the central portion of the weight mounting portion 13a of the vibration member 13 is set at the origin O, the vibrators 12 are opposed to each other from the weight mounting portion 13a of the vibration member 13 (the portion above the weight portion). Then, two pairs of a total of four torsion spring portions 13b1 to 13b4 extend outward substantially symmetrically with respect to the X axis and the Y axis and substantially parallel to the X axis, respectively.
And a total of four arm portions 13c1 to 13c from each of the extending distal end portions of the four torsion spring portions 13b1 to 13b4.
4 extend outwardly substantially symmetrically with respect to the Y-axis and the X-axis and substantially parallel to the Y-axis, and furthermore, each extended end portion of the four arm portions 13c1 to 13c4 is fixed to the fixing member 1.
1, the side fixing portions 11a, 1 substantially parallel to the X-axis.
1b.

At this time, among the four torsion spring portions 13b1 to 13b4 formed on the vibration member 13, the torsion spring portion 1
The pair of 3b1 and the torsion spring portion 13b3
a) and the torsion spring portion 1
The pair of the 3b2 and the torsion spring portion 13b4 is also the weight mounting portion 13.
The pair (13b1, 13b3) and (13b2, 13b4) of the torsion spring portions are provided symmetrically with respect to the X axis through a. On the other hand, of the four arm portions 13c1 to 13c4 formed on the vibration member 13, the pair of the arm portion 13c1 and the arm portion 13c2 is symmetric with respect to the X axis, and the pair of the arm portion 13c3 and the arm portion 13c4 is also Symmetry with respect to the X axis, each pair of arms (13c1, 13c2), (13c3, 13c4)
These are provided symmetrically with respect to the Y axis.

Further, four torsion spring portions 13b1 to 13b4 formed on the vibration member 13 and four arm portions 13c1
13c4 intersect in an L-shape, and both portions are narrow, thin, and elastically displaceable.

With this arrangement, when a force acts in a certain direction, the weight of the weight mounting portion 13a and the weight 14 formed on the vibration member 13 has four torsion springs 1 above.
Since the connection is made by 3b1 to 13b4, a moment acts around the center of gravity G of the weight portion combining the weight mounting portion 13a and the weight 14 with the fulcrum as the fulcrum axis, and the weight 14 tilts in the direction of the force. At that time, the four torsion spring portions 13b1
13b4 and the four arm portions 13c1 to 13c4 are configured to bend.

At this time, the position of the center of gravity G of the weight portion, which is the combination of the weight mounting portion 13a and the weight 14, is set on the Z axis by four torsion spring portions 13b1 to 13b4 and four arm portions 13c.
If the shape of the weight 14 is designed so as to be set at a lower position apart from 1 to 13c4, the weight 14 can be further inclined.

Next, a weight 14 is fixed to the back surface of the weight mounting portion 13a of the vibration member 13, and the swingable vibrator 1
The case where 2 is used as an angular velocity sensor will be described.

First, four vibration generating members 1 are provided on the four arm portions 13c1 to 13c4 formed on the vibration member 13.
5a to 15d are integrally formed with a film, and four torsion spring portions 13b formed on the vibrating member 13.
Four vibration detecting members 16a to 16b are provided on 1 to 13b4.
d are each integrally formed with a film.

As shown in FIG. 2A, the vibration generating members 15a to 15d and the vibration detecting members 16a to 16d are composed of an insulating film, a lower electrode, , A piezoelectric film and an upper electrode are laminated in this order, and all the upper and lower electrodes and the piezoelectric material can be made of the same material. There is a manufacturing advantage that can be performed.

Although a thin Si substrate is used for the vibration member 13 in the above-described embodiment, a piezoelectric crystal material substrate such as quartz or langasite is used for the vibration member 13 instead of the thin Si substrate. In this case, as shown in an enlarged manner in FIG. 3A, the vibration generating members 15a to 15d and the vibration detecting members 16a to 16d have an upper electrode and a lower electrode on the upper and lower surfaces of the piezoelectric crystal material substrate. What is necessary is just to apply a film directly to each.

Next, the angular velocity sensor 10 having the above structure
Can be obtained by measuring a Coriolis force CF generated when an angular velocity is applied to a rotating or vibrating object. The Coriolis force CF is expressed as CF = −2 mΩV (where m: mass of the oscillator 12, Ω: angular velocity, V: speed of the oscillator 12).

The weight mounting portion 13a of the vibration member 13
In order to vibrate the weight 14 fixed to the back surface of the oscillating member, a sine wave voltage in the same direction is applied to all of the vibration generating members 15a to 15d via the upper and lower electrodes. Vibrates up and down through. At this time,
The frequency of the applied sine wave must be lower than the resonance frequency of the structure. Further, if the vibrator 12 is vibrated at the resonance frequency, a large vibration displacement can be obtained with a small driving voltage. If a voltage is applied to the upper and lower electrodes of the vibration generating members 15a to 15d in the opposite phase by any two pairs, the weight 14 does not vibrate vertically but rotationally vibrates like a well-known optical deflector. A driving method may be used.

Next, consider a case where an angular velocity is applied when the weight 14 fixed to the back surface of the weight mounting portion 13a of the vibration member 13 is vibrating up and down. As described above, the four torsion spring portions 13b1 to 13b formed on the vibrating member 13
Assuming that a direction parallel to b4 is an X-axis direction and a direction orthogonal to the four torsion spring portions 13b1 to 13b4 is a Y-axis direction, first, when an angular velocity is applied around the X-axis, FIG.
As schematically shown in (A), the X-axis direction component CFx of the Coriolis force CF generated by the angular velocity is equal to the weight mounting portion 13.
a and the weight 14 work in the X-axis direction with respect to the center of gravity G of the weight portion. Since the upper portion of the weight portion is supported by the four torsion spring portions 13b1 to 13b4, this portion is As a fulcrum, the X-axis direction component CFx of the Coriolis force CF gives a rotational moment to the center of gravity G of the weight portion. As a result, the right torsion spring portions (13b1, 13b2) on the right side in the figure are bent upward, and the torsion spring portions (13b3, 13b4) on the left side in the figure are bent downward. At this time, the four torsion spring portions 13b1
13b4, vibration detecting members 16a to
In the piezoelectric film 16d, voltages corresponding to the amounts of bending of the four torsion spring portions 13b1 to 13b4 are generated by the piezoelectric inverse electrostriction effect. In this case, four torsion spring portions 13b1
Detecting members 16a to 16a generated from the flexures to 13b4 to 13b4
6d are output to 16a, 16b, 16c and 16 respectively.
Assuming that d, the piezo output generated by the X-axis direction component CFx of the Coriolis force CF is CFx = {(16a + 16b)-(16c + 16d)}.
Can be requested.

Similarly, when an angular velocity is applied around the Y-axis, as shown schematically in FIG. 4B, the Y-axis direction component CFy of the Coriolis force CF generated by the angular velocity is equal to the weight mounting portion 13a. 14, and acts in the Y-axis direction with respect to the center of gravity G of the weight portion, but since the upper portion of the weight portion is supported by four torsion spring portions 13b1 to 13b4,
Using this portion as a fulcrum, the Y-axis direction component C of the Coriolis force CF
Fy gives a moment of rotation to the center of gravity G of the weight 14.
As a result, the torsion spring portions 13b1 and 13b3 bend downward, and the torsion spring portions 13b2 and 13b4 bend upward.
In this case, the piezo output of the vibration detecting members 16a to 16d generated from the bending of the four torsion spring portions 13b1 to 13b4 by the Y-axis component CFy of the Coriolis force CF is CFy = ｛(16a + 16c) − (16b + 16d).値, and this value is converted into an angular velocity to obtain an angular velocity Ωy around the Y axis.
Can be requested.

As described above, the angular velocity sensor 10 of the present invention described above independently detects the piezo outputs generated by the bending of the four torsion spring portions 13b1 to 13b4, and adds and subtracts the respective piezo output values. The angular velocity of the shaft can be detected with high sensitivity.

In the above-described embodiment of the angular velocity sensor 10 of the present invention, the weight mounting portion 13a formed at the center portion of the vibration member 13 and the weight 14 fixed to the back surface thereof are formed in a substantially rectangular shape. The shape of the weighted portion is not limited to a substantially rectangular shape. Even if the weighted portion is circular, two pairs of the torsion spring portions 13b1 are opposed to each other from above the weighted portion. ~ 13b4 can be formed.

The angular velocity sensor 10 according to the present invention having the above configuration.
Is a weight attachment portion 13 formed at a central portion of the vibration member 13.
Since the vibrator 12 is formed to be swingable by fixing the weight 14 to the back surface of the substrate a, the vibration member 13 can be a semiconductor Si substrate or a piezoelectric crystal material substrate. Can be manufactured.

Next, an angular velocity sensor 20 according to a modification of the present invention will be described.
Will be briefly described with reference to FIG.

As shown in FIG. 5, the angular velocity sensor 20 of the modified example of the present invention has a vibrator whose shape is substantially the same as the vibrator of the angular velocity sensor 10 of the present invention described above with reference to FIG. However, here, both the fixed portion and the vibrator are integrally formed by a micromachine technique using a single crystal Si material or the like.

That is, the angular velocity sensor 20 of the modified example of the present invention
A frame 21 having a substantially rectangular external shape is formed by using a single crystal Si material or the like, and a fixed frame 21a is formed in a square shape along the outer peripheral portion of the frame 21;
The surrounding area inside is cut off. Here, the frame 21
The XYZ axes of the three-dimensional orthogonal coordinate space are temporarily set at the central part in the following description.

Further, two arms are separated from the side fixing portions 21a1 and 21a2 facing each other on the inner side of the fixing frame portion 21a, respectively, so that a total of four arm portions 21b1-2 are formed.
1b4 extends inward along the Y axis,
The four torsion spring portions 21c1 to 21c4 are extended inward along the X axis from the extended end portions of the four arm portions 21b1 to 21b4, and the four torsion spring portions 21c1 are provided. A heavy weight portion 21d is integrally supported on the extended distal end portion of the base member 21c4. At this time, the four arm portions 21b1 to 21b4 and the four torsion spring portions 21c
The weight portion 21d is supported so that the center of gravity G of the weight portion 21d is located lower than 1 to 21c4. Therefore, the frame 2
The weight portion 21d is located at a central portion inside 1 and the center of gravity G of the weight portion 21d is on the Z axis. Also, four arm portions 21b1 to 21b4 and four torsion spring portions 21c1
21c4 are formed in an L-shape and each pair of arm portions (21b1, 21b2), (21b3, 21b).
4) are symmetrically provided facing each other about the X axis, and each pair of torsion spring portions (21c1, 21c)
3) and (21c2, 21c4) are symmetrically provided facing each other about the Y axis via the weight 21d. Further, in order to displace the weight portion 21d in the X-axis, Y-axis, and Z-axis directions, four arm portions 21b1 to 21b4 and 4
The torsion spring portions 21c1 to 21c4 are narrow, thin and elastically displaceable.

The four arms 21b1 to 21b4 integrally formed in the frame 21 and the four torsion springs 21
The vibrator is constituted by c1 to 21c4 and the weight 21d. Furthermore, on the four arm portions 21b1 to 21b4,
The vibration generating member 2 having the same structure as that shown in FIG.
2a to 22d are respectively applied with a film, and the four torsion spring portions 21c1 to 21c4 are also provided on FIG.
(A) Vibration detecting members 23a to 23 having the same structure as shown in FIG.
3d are each provided with a film.

The angular velocity sensor 20 according to the modified example of the present invention having the above configuration can detect angular velocity with high sensitivity by the same operation as the angular velocity sensor 10 of the present invention described above, and all the components are integrally formed. Therefore, although the cost is expensive, the dimensional accuracy can be accurately determined,
A highly reliable angular velocity sensor 20 can be provided.

<Acceleration Sensor> FIG. 6 is a perspective view showing an acceleration sensor according to the present invention, and FIG. 7 is a view schematically showing the operation of a vibrator in the acceleration sensor according to the present invention. (A) shows a state in which the X-axis direction component Fx of the force F due to acceleration is applied to the weight fixed to the vibration member, and (B) shows the state in which the Y-axis direction component Fy of the force F due to acceleration is added to the weight fixed to the vibration member. FIG. 8C shows a state in which a Z-axis direction component Fz of a force F due to acceleration is applied to a weight fixed to a vibration member, and FIG. 8 shows an acceleration sensor according to a modification of the present invention. FIG.

As shown in FIG. 6, the acceleration sensor 30 according to the present invention has the same basic structure as the angular velocity sensor 10 according to the present invention described above with reference to FIG. In this configuration, the vibration generating members 15a to 15d formed on the four arm portions 13c1 to 13c4 formed on the vibration member 13 of the vibrator 12 are omitted, and for convenience of explanation, the constituent members described above are used. The same components as those described above are denoted by the same reference numerals and will be described.

Accordingly, in the acceleration sensor 30 according to the present invention, the vibration detecting members 16a to 1b are provided on the four torsion spring portions 13b1 to 13b4 formed on the vibrating member 13 of the vibrator 12.
Only 6d is coated. At this time, the vibration detecting member 16
a to 16d may be connected to the four torsion spring portions 13b1 to 13b4 and extended on the four arm portions 13c1 to 13c4 to form a film. In this case, a larger detection output is obtained. Is possible.

Next, the acceleration sensor 30 having the above structure
When acceleration is applied to the weight 14 fixed to the back surface of the weight mounting portion 13a of the vibration member 13, the force acting thereon is F: F = mα (where m: mass of the vibrator 12, α: acceleration) Therefore, the acceleration can be obtained by measuring the force F.

At this time, as in the case of the angular velocity sensor 10, the four torsion spring portions 13b1 to 13b1 formed on the vibration member 13 are used.
A direction parallel to 3b4 is defined as an X-axis direction, a direction orthogonal to the four torsion spring portions 13b1 to 13b4 is defined as a Y-axis direction, and a vertical direction of the vibrator 12 is defined as a Z-axis direction.

First, when acceleration is applied in the X-axis direction,
As schematically shown in FIG. 6A, the X-axis direction component Fx of the force F generated by the acceleration acts in the X-axis direction with respect to the center of gravity G of the weight portion including the weight mounting portion 13a and the weight 14. However, four torsion springs 13b1 are located above the weight.
13b4, as in the case of the angular velocity sensor 10, a rotational moment acts on the center of gravity G of the weight portion using this portion as a fulcrum, and the torsion spring portion (13b
1, 13b2) flexes upward, and the torsion spring portions (13b3, 13b4) on the left side in the figure flex downward. At this time, the piezoelectric films of the vibration detecting members 16a to 16d respectively formed on the four torsion spring portions 13b1 to 13b4 are bent by the piezoelectric torsion effect of the four torsion spring portions 13b1 to 13b4. , Respectively. In this case, 4
The output of the vibration detecting members 16a to 16d generated from the bending of the torsion spring portions 13b1 to 13b4 is 16
Assuming that a, 16b, 16c, and 16d, the piezo output generated by the X-axis component Fx of the force F is given by Fx = {(16a + 16b)-(16c + 16d)}. αx
Can be requested.

When acceleration is applied in the Y-axis direction,
As schematically shown in FIG. 6B, the Y-axis direction component Fy of the force F generated by the acceleration acts in the Y-axis direction with respect to the center G of the weight of the weight mounting portion 13a and the weight 14. However, four torsion springs 13b1 are located above the weight.
13b4, a rotational moment acts on the center of gravity G of the weight portion with this portion as a fulcrum, as in the case of the angular velocity sensor 10, and the torsion spring portions 13b1, 13b3
Is bent downward, and the torsion spring portions 13b2, 13b4 are bent upward. In this case, the piezo outputs of the vibration detection members 16a to 16d generated from the bending of the four torsion spring portions 13b1 to 13b4 due to the Y-axis component Fy of the force F are as follows: Fy = {(16a + 16c)-(16b + 16d)} This value is converted into an acceleration to obtain an acceleration αy in the Y-axis direction.
Can be requested.

Further, when acceleration is applied in the Z-axis direction, as schematically shown in a cross section in FIG. 6C, the Z-axis direction component Fz of the force F generated by the acceleration is applied to the weight mounting portion 13a. By acting in the Z-axis direction with respect to the center of gravity G of the weight unit together with the weight 14, the weight unit moves upward (or downward). At this time, the four torsion spring portions 13b1-1
3b4 all bend upward (or downward). in this case,
Four torsion spring portions 13 are generated by the Z-axis component Fz of the force F.
Vibration detecting member 16a generated from bending of b1 to 13b4
The piezo output of .about.16d is expressed as: Fz = (16a + 16b + 16c + 16d).
Can be requested.

As described above, the above-described acceleration sensor 30 of the present invention independently detects the piezo outputs generated by the bending of the four torsion spring portions 13b1 to 13b4, and adds or subtracts the piezo outputs to obtain the three piezo output values. The acceleration of the shaft can be detected with high sensitivity.

Next, an acceleration sensor 40 according to a modification of the present invention will be described.
Will be briefly described with reference to FIG.

As shown in FIG. 8, the acceleration sensor 40 of the modified example of the present invention has the same basic structure as the angular velocity sensor 20 of the modified example of the present invention described above with reference to FIG. In this acceleration sensor 40, the four arms 21
Vibration generating members 22a-2 formed on films b1-21b4
Since 2d is omitted, the same reference numerals are given and only the illustration is given.

<Angular Velocity / Acceleration Sensor> FIG. 9 is a block diagram for explaining an angular velocity / acceleration sensor according to the present invention, and FIG. FIG. 9 is a diagram for explaining an operation of detecting acceleration in a state where is applied.

The angular velocity / acceleration combined sensor 50 according to the present invention shown in FIG. 9 is a structure of the angular velocity sensor 10 according to the present invention described above with reference to FIG. 1 or a modification of the present invention described with reference to FIG. The configuration is such that the angular velocity and the acceleration can be detected by applying the structure of the angular velocity sensor 20 of the example as it is.

In the following description, the case where the angular velocity sensor 10 according to the present invention described above is used as the angular velocity / acceleration combined sensor 50 according to the present invention will be described with reference to FIG. FIG. 9 shows vibration detection members 23a to 23d in the case where the angular velocity sensor 20 of the modification is used.
Is shown in parentheses and the description is omitted.

In the angular velocity / acceleration combined sensor 50 described above, the angular velocity and the acceleration are detected in the state where the sine waves in the same direction are applied to the vibration generating members 15a to 15d, respectively. When a sine wave is applied to the vibration member 13, the weight 14 fixed to the back surface of the weight mounting portion 13 a of the vibration member 13 vibrates up and down, so that the vibration detection members 16 a formed on the four torsion spring portions 13 b 1 to 13 b 4 respectively. The piezoelectric film of ~ 16d is 4
Voltages corresponding to the amount of bending of the torsion spring portions 13b1 to 13b4 are generated.

Here, when detecting the angular velocity, as described above, the outputs of the vibration detecting members 16a to 16d generated by the flexure of the four torsion springs 13b1 to 13b4 are output to 16a, 16b, and 16b, respectively. 16c and 16d,
The piezo output generated by the X-axis component CFx of the Coriolis force CF is CFx = {(16a + 16b) − (16c + 16d)}, while the piezo output generated by the Y-axis component CFy of the Coriolis force CF is CFy = ｛. (16a + 16c) − (16b + 16d)｝, so that the values of CFx and CFy are converted into angular velocities and X
The angular velocities Ωx and Ωy around the axes Y and Y can be obtained.

Next, when the acceleration is detected, as shown in FIG. 9, the subtractors 51A to 51D serve as DC change generating means for obtaining DC changes from the respective outputs of the vibration detecting members 16a to 16d. 51D, HPFs (high-pass filters) 52A to 52D, and phase adjusters 53A to 53D
And have added.

Here, as shown in FIG. 10, when a sine wave is applied to the vibration generating members 15a to 15d, the output of the vibration detecting members 16a to 16d obtains an angular velocity component due to the generation of the Coriolis force due to the angular velocity. Thereafter, when an acceleration is applied to the weight portion including the weight attachment portion 13a and the weight 14, the angular velocity component is displaced in a DC (direct current) due to the generation of the force due to the acceleration, and the DC change becomes the acceleration component. Things.

Therefore, based on the above-described operation principle, as shown in FIG. 9, the outputs of the vibration detecting members 16a to 16d are output to the subtracters 51A to 51D and the HPF (high-pass filter) 5.
2A to 52D. And HPF52A
５２52D to extract the angular velocity component, and this HPF 52A
The vibration detecting members 16a to 16d input the respective outputs of .about.52D to the subtracters 51A to 51D by the phase adjusters 53A to 53D.
Phase adjustment for each output from. Thereafter, in the subtracters 51A to 51D, the respective outputs from the vibration detecting members 16a to 16d input here and the phase adjusters 53A to 53D.
By subtracting each output from the 3D, the D when the angular velocity component is displaced in a DC (direct current) due to the generation of the force due to the acceleration.
The C variations 51a to 51d are obtained.

Thereafter, each D from the subtracters 51A to 51D is output.
Acceleration speeds in the X-axis direction, the Y-axis direction, and the Z-axis direction are detected by adding and subtracting the C variations 51a to 51d in combination with the adder / subtractor 54. That is, the adder / subtractor 54 calculates the DC change DCx in the X-axis direction, the DC change DCy in the Y-axis direction, and the DC change DCz in the Z-axis direction from the following equations.

DCx = {(51a + 51b) − (51c + 51d)} DCy = {(51a + 51c) − (51b + 51d)} DCz = (51a + 51b + 51c + 51d) Then, the obtained DCx, DCy, and DCz values are acceleration-converted to the X-axis. Acceleration αx in the direction, acceleration α in the Y-axis direction
The acceleration αz in the y- and Z-axis directions can be obtained.

The above-described angular velocity / acceleration combined sensor 50 of the present invention particularly includes a DC change generation means for obtaining a DC change from each output of the four vibration detecting members 16a to 16d for detecting acceleration. Only when the four vibration generating members 15a to 15d are driven, the angular velocity and the acceleration can be detected together.

Next, a modification of the angular velocity / acceleration sensor according to the present invention will be briefly described. In the case of this modification, the angular velocity sensors 10 and 2 previously shown in FIGS.
0 and the technical ideas of the acceleration sensors 30 and 40 previously shown in FIGS. 6 and 7.

That is, the angular velocity sensors 10 and 20 shown in FIGS. 1 and 5 have four arms (13c1 to 13c).
4), four vibration generating members (15a to 15d) and (22a to 2b) film-coated on (21b1 to 21b4), respectively.
When 2d) is driven, it functions as the angular velocity sensors 10 and 20, and functions as four vibration generating members (15a to 15d),
3A and 3B are equivalent to the acceleration sensors 30 and 40 at the time of non-driving without driving (22a to 22d).
As shown in (B), the vibration generating members (15a to 15a)
d), (22a to 22d) By providing a switching means (switch) SW for switching between angular velocity detection and acceleration detection between the upper electrode and the lower electrode, the same structure can be used as an angular velocity / acceleration combined sensor. It is also possible to use.

[0067]

According to the angular velocity sensor, acceleration sensor and combined angular velocity / acceleration sensor of the present invention described in detail above, according to the angular velocity sensor of the first aspect, in particular, a voltage of a substantially constant period is applied to the vibrator to apply a voltage to the vibrator. In order to vibrate the weight formed at the central portion through the four torsion springs and the four arms, four vibration generating members integrally provided on the four arms, respectively, and an angular velocity In order to detect the Coriolis force applied to the weight when applied, and to obtain the angular velocity, four torsion springs are provided with four vibration detecting members integrally provided, respectively. By adding and subtracting the outputs of the vibration detection members in combination, the angular velocities in the X-axis direction and the Y-axis direction can be detected with high sensitivity.
Moreover, the structure is very simple, and it can be manufactured by a normal semiconductor manufacturing process, so that the cost can be reduced.

According to the acceleration sensor of the second aspect, particularly, when the weight formed at the central portion of the vibrator is swingably supported via the four torsion springs and the four arms. In order to obtain the acceleration by detecting the force applied to the weight portion when the acceleration is applied, the four torsion spring portions are provided with four vibration detecting members integrally provided, respectively. By adding and subtracting the outputs of the respective vibration detecting members, the acceleration in the X-axis direction, the Y-axis direction, and the Z-axis direction can be detected with high sensitivity. Since it can be manufactured by a manufacturing process, cost reduction is also possible.

According to a third aspect of the present invention, the structure of the angular velocity sensor according to the first aspect is applied, and in particular, a DC signal is output from each output of the four vibration detecting members for detecting the acceleration. DC to find the change
By simply adding the change generation means, it is possible to detect both the angular velocity and the acceleration while driving the four vibration generating members.

Further, according to the angular velocity / acceleration combined sensor according to the fourth aspect, the structure of the angular velocity sensor according to the first aspect is applied. Further, when the angular velocity is detected, the four vibration generating members are driven while the acceleration is detected. Since the switching means for non-driving the four vibration generating members at the time of detection is provided, the same effects as those of the first aspect can be obtained, and a convenient angular velocity / acceleration sensor can be provided.

[Brief description of the drawings]

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

FIG. 2 illustrates a vibration generating member and a vibration film formed on four torsion spring portions and four arm portions formed on the vibration member when a Si substrate is used as the vibration member illustrated in FIG. It is sectional drawing which expanded and showed the detection member.

FIG. 3 is a diagram illustrating a vibration generating member in which a piezoelectric crystal material substrate is used as the vibration member shown in FIG. 1, and a film is formed on each of four torsion springs and four arms formed on the vibration member; FIG. 3 is an enlarged cross-sectional view of a vibration detection member.

FIG. 4 is a diagram schematically illustrating an operation of a vibrator in the angular velocity sensor according to the present invention.

FIG. 5 is a perspective view showing an angular velocity sensor according to a modification of the present invention.

FIG. 6 is a perspective view showing an acceleration sensor according to the present invention.

FIG. 7 is a diagram schematically illustrating an operation of a vibrator in the acceleration sensor according to the present invention.

FIG. 8 is a perspective view showing an acceleration sensor according to a modification of the present invention.

FIG. 9 is a block diagram illustrating an angular velocity / acceleration combined sensor according to the present invention.

FIG. 10 is a diagram for explaining an operation of detecting acceleration while applying a sine wave to the vibration generating member in the angular velocity / acceleration combined sensor according to the present invention.

FIG. 11 is an exploded perspective view showing a conventional acceleration sensor in an exploded manner.

FIG. 12 is a diagram for explaining the operation of a conventional acceleration sensor.

[Explanation of symbols]

10: angular velocity sensor of the present invention, 11: fixing member, 11
a, 11b: side surface fixing portion, 11c: concave portion, 12: vibrator, 13: vibrating member, 13a: weight mounting portion, 13b1
13b4... Four torsion springs, 13c1 to 13c4.
Four arms, 15a to 15d: vibration generating member, 16
a to 16d: vibration detection member, 20: angular velocity sensor of a modified example of the present invention, 21: frame body, 21a: fixed frame portion, 21a
1, 21a2: Side fixing portion, 21b1 to 21b4, 4 arm portions, 21c1 to 21c4, 4 torsion spring portions, 22a to 22d, vibration generating members, 23a to 23d,
Vibration detection member, 30: Acceleration sensor of the present invention, 40: Acceleration sensor of a modification of the present invention, 50: Angular velocity / acceleration combined sensor, 51A to 51D: Subtractor, 52A to 52D ...
HPF (high-pass filter), 53A to 53D: phase adjuster, 54: adder / subtractor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 41/08 H01L 41/08 Z

Claims (4)

[Claims] 1. A fixed member serving as a base, and an XY in a three-dimensional rectangular coordinate space at a central portion in the fixed member.
A Z-axis is temporarily set, and a weight portion is provided so that the center of gravity is substantially located on the Z-axis passing through the intersection of the three axes. A total of four torsion spring portions are provided in two pairs facing each other from above the weight portion. Extend outwardly substantially symmetrically with respect to the X-axis and the Y-axis and substantially parallel to the X-axis, and a total of four from each of the extended tip portions of the four torsion spring portions. The arm portions extend outwardly substantially symmetrically with respect to the Y-axis and the X-axis and substantially parallel to the Y-axis, respectively. Further, each of the extended end portions of the four arm portions is connected to the fixing member. Vibrators fixed to the opposing side surfaces, and the four vibrators for applying a voltage having a substantially constant period to vibrate the weight portion through the four torsion spring portions and the four arm portions. 4 provided integrally with each arm
And four vibration detecting members provided integrally with the four torsion spring portions, respectively, in order to detect the Coriolis force applied to the weight portion when the angular velocity is applied and to obtain the angular speed. And driving the four vibration generating members when detecting the angular velocity,
An angular velocity sensor for detecting the angular velocity in the X-axis direction and the Y-axis direction by adding and subtracting the outputs of the four vibration detection members in combination. 2. A fixed member serving as a base, and XY in a three-dimensional orthogonal coordinate space provided at a central portion in the fixed member.
A Z-axis is temporarily set, and a weight portion is provided so that the center of gravity is substantially located on the Z-axis passing through the intersection of the three axes. A total of four torsion spring portions are provided in two pairs facing each other from above the weight portion. Extend outwardly substantially symmetrically with respect to the X-axis and the Y-axis and substantially parallel to the X-axis, and a total of four from each of the extended tip portions of the four torsion spring portions. The arm portions extend outwardly substantially symmetrically with respect to the Y-axis and the X-axis and substantially parallel to the Y-axis, respectively. Further, each of the extended end portions of the four arm portions is connected to the fixing member. Vibrators respectively fixed to opposing side surfaces, and four torsional spring portions provided integrally with the four torsion spring portions to detect acceleration applied to the weight portion when acceleration is applied and to obtain acceleration. And a combination of the outputs of the four vibration detecting members. By subtraction, the acceleration sensor and detects the acceleration in the X-axis direction and the Y-axis direction and Z axis direction. 3. A fixed member serving as a base, and XY in a three-dimensional orthogonal coordinate space at a central portion in the fixed member.
A Z-axis is temporarily set, and a weight portion is provided so that the center of gravity is substantially located on the Z-axis passing through the intersection of the three axes. A total of four torsion spring portions are provided in two pairs facing each other from above the weight portion. Extend outwardly substantially symmetrically with respect to the X-axis and the Y-axis and substantially parallel to the X-axis, and a total of four from each of the extended tip portions of the four torsion spring portions. The arm portions extend outwardly substantially symmetrically with respect to the Y-axis and the X-axis and substantially parallel to the Y-axis, respectively. Further, each of the extended end portions of the four arm portions is connected to the fixing member. Vibrators fixed to the opposing side surfaces, and the four vibrators for applying a voltage having a substantially constant period to vibrate the weight portion through the four torsion spring portions and the four arm portions. 4 provided integrally with each arm
In order to obtain the angular velocity by detecting the Coriolis force applied to the weight portion when the angular velocity is applied, and to obtain the acceleration by detecting the force applied to the weight portion when the acceleration is applied,
Four vibration detecting members provided integrally with the four torsion spring portions, and DC change generating means for obtaining a DC change from each output of the four vibration detecting members, When the angular velocities are detected while the four vibration generating members are driven, the angular velocities in the X-axis direction and the Y-axis direction are detected by adding and subtracting the outputs of the four vibration detecting members in combination. On the other hand, when the acceleration is detected in a state where the four vibration generating members are driven, by adding and subtracting the outputs of the DC change generation means in combination,
An angular velocity / acceleration sensor for detecting accelerations in an X-axis direction, a Y-axis direction, and a Z-axis direction. 4. A fixed member serving as a base, and an XY in a three-dimensional orthogonal coordinate space at a central portion in the fixed member.
A Z-axis is temporarily set, and a weight portion is provided so that the center of gravity is substantially located on the Z-axis passing through the intersection of the three axes. A total of four torsion spring portions are provided in two pairs facing each other from above the weight portion. Extend outwardly substantially symmetrically with respect to the X-axis and the Y-axis and substantially parallel to the X-axis, and a total of four from each of the extended tip portions of the four torsion spring portions. The arm portions extend outwardly substantially symmetrically with respect to the Y-axis and the X-axis and substantially parallel to the Y-axis, respectively. Further, each of the extended end portions of the four arm portions is connected to the fixing member. Vibrators fixed to the opposing side surfaces, and the four vibrators for applying a voltage having a substantially constant period to vibrate the weight portion through the four torsion spring portions and the four arm portions. 4 provided integrally with each arm
In order to obtain the angular velocity by detecting the Coriolis force applied to the weight portion when the angular velocity is applied, and to obtain the acceleration by detecting the force applied to the weight portion when the acceleration is applied,
Four vibration detecting members provided integrally with the four torsion spring portions, and the four vibration generating members are driven when detecting the angular velocity,
Switching means for non-driving the four vibration generating members at the time of detecting the acceleration, by adding and subtracting the outputs of the four vibration detecting members in combination to obtain angular velocities in the X-axis direction and the Y-axis direction; To detect
Alternatively, the angular velocity / acceleration combined sensor detects accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction.