JP2004361420A - Angular velocity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple structured angular velocity sensor for detecting the given three-dimensional periaxial angular rate. <P>SOLUTION: In this sensor, both a flexible substrate 110 and a fixed substrate 120 parallel with XY plane are installed in a sensor case 140. A vibrator 130 is jointed to bottom face of the flexible substrate 110. Electrodes F1-F5(where F3, F4 are respectively located on near side and opposite side of F5.) are formed on top face of the flexible substrate 110, while electrodes E1-E5(where E3, E4 are respectively located on near side and opposite side of E5.) are formed on bottom face of the flexible substrate 120. By adding antiphase AC signal between electrodes E3 and F3 and between electrodes E4 and F4, the vibrator 130 is vibrated in the Y-axial direction. In this status, Coriolis force Fx generates in the X-axial direction if periaxial angular velocity about Z-axis ωz affects this sensor. Thus the Coriolis force Fx is detected from the difference between capacitance value of a capacitive element consisting of electrodes E1 and F1 and that of a capacitive element consisting of electrodes E2 and F2 to calculate the angular velocity ωz. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an angular velocity sensor, and more particularly, to an angular velocity sensor that can detect an angular velocity about a predetermined axis in an XYZ three-dimensional coordinate system.

  2. Description of the Related Art In the automobile industry, the machine industry, and the like, a demand for a sensor capable of accurately detecting acceleration and angular velocity of a moving object is increasing. Generally, an object moving freely in a three-dimensional space is subjected to an acceleration in an arbitrary direction and an angular velocity in an arbitrary rotation direction. Therefore, in order to accurately grasp the motion of the object, it is necessary to independently detect the acceleration in each coordinate axis direction and the angular velocity around each coordinate axis in the XYZ three-dimensional coordinate system.

Conventionally, various types of multidimensional acceleration sensors have been proposed. For example, Patent Literature 1 below discloses an acceleration sensor that uses a resistance element formed on a semiconductor substrate and detects an applied acceleration in each coordinate axis direction. Patent Document 2 discloses a multi-axis acceleration sensor having a self-diagnosis function. Further, Patent Literature 3 discloses an acceleration sensor that uses a capacitance element or a piezoelectric element and detects an applied acceleration for each coordinate axis direction. Patent Literature 4 and Patent Literature 5 also disclose similar multiaxial acceleration sensors. Patent Literature 6 discloses a novel electrode arrangement in a similar multiaxial acceleration sensor, and Patent Literature 7 discloses a multiaxial acceleration sensor using another type of piezoelectric element. The feature of these acceleration sensors is that a plurality of resistance elements / capacitance elements / piezoelectric elements are arranged at predetermined positions on a flexible substrate, and a change in resistance value of the resistance element / capacity of the capacitance element The point is that the applied acceleration is detected based on the value change / the change in the voltage generated by the piezoelectric element. A weight is attached to the flexible substrate, and when an acceleration is applied, a force is applied to the weight, causing the flexible substrate to bend. If this deflection is detected based on the above-described change in the resistance value / capacitance value / generated charge, the axial components of the acceleration can be obtained.
International Publication No. WO88 / 08522 (U.S. Pat. Nos. 4,967,605 and 5,182,515) International Publication No. WO 91/10118 (US Pat. No. 5,295,386) International Publication No. WO92 / 17759 (U.S. Pat. No. 5,492,020) JP-A-4-148833 JP-A-4-249726 (U.S. Pat. No. 5,412,213) JP-A-5-118942 (U.S. Pat. No. 5,343,765) International Publication No. WO93 / 02342

  On the other hand, there is no literature on a multidimensional angular velocity sensor as far as the inventor of the present application knows. Generally, an angular velocity sensor is used to detect an angular velocity of a power shaft of a vehicle or the like, and has only a function of detecting an angular velocity around a specific one axis. When the rotational speed of the power shaft is to be obtained, it is sufficient to use a one-dimensional angular velocity sensor. However, in order to detect the angular velocity of a free-moving object in a three-dimensional space, it is necessary to independently detect the angular velocity around each of the X, Y, and Z axes in an XYZ three-dimensional coordinate system. . In order to detect the angular velocities around each of the X, Y, and Z axes using a conventionally used one-dimensional angular velocity sensor, three sets of these angular velocity sensors are prepared, and the angular velocities around each axis are measured. It must be mounted in a specific direction that can be detected. Therefore, the structure as a whole becomes complicated and the cost becomes high.

  An object of the present invention is to provide a novel angular velocity sensor having a relatively simple structure and capable of independently detecting an angular velocity about a predetermined axis in an XYZ three-dimensional coordinate system.

  The basic principle used in the present invention is that when an angular velocity ω around a first coordinate axis acts on a vibrator placed in an XYZ three-dimensional coordinate system, the vibrator is moved in the direction of a second coordinate axis. The principle is that when vibrated, a Coriolis force proportional to the magnitude of the angular velocity ω is generated in the third coordinate axis direction. In order to detect the angular velocity ω using this principle, means for vibrating the vibrator in a predetermined coordinate axis direction, and means for detecting displacement in the predetermined coordinate axis direction generated on the vibrator by the action of Coriolis force include: Will be needed. In addition, in order to detect all of the angular velocity ωx about the X axis, the angular velocity ωy about the Y axis, and the angular velocity ωz about the Z axis, means for vibrating the vibrator in three axial directions, And means for detecting the displacement of The present invention provides a sensor provided with such means, and has the following features.

(1) A first feature of the present invention is a multi-axis angular velocity sensor that detects an angular velocity around each coordinate axis in a three-dimensional coordinate system.
A vibrator with mass,
A sensor housing for housing the vibrator;
Connecting means for connecting the vibrator to the sensor housing with a degree of freedom such that the vibrator can be moved in each coordinate axis direction;
Excitation means for vibrating the vibrator in each coordinate axis direction,
Displacement detecting means for detecting displacement of the vibrator in each coordinate axis direction,
Is provided.

(2) A second feature of the present invention is a multi-axis angular velocity sensor having the above-described first feature,
An instruction is given to the excitation means to vibrate the vibrator in the direction of the first coordinate axis, and an instruction is given to the displacement detection means to detect a displacement of the vibrator in the direction of the second coordinate axis, and the detection is performed. A first detection operation for obtaining an angular velocity about a third coordinate axis based on the displacement obtained;
An instruction is given to the excitation means to vibrate the vibrator in the direction of the second coordinate axis, and an instruction is given to the displacement detection means to detect a displacement of the vibrator in the direction of the third coordinate axis. A second detection operation for obtaining an angular velocity about the first coordinate axis based on the displacement obtained;
An instruction is given to the excitation means to vibrate the vibrator in the third coordinate axis direction, and an instruction is given to the displacement detection means to detect the displacement of the vibrator in the first coordinate axis direction. A third detection operation for obtaining an angular velocity about the second coordinate axis based on the displacement obtained;
Is further provided.

(3) A third aspect of the present invention is a multi-axis angular velocity sensor having the above-mentioned second aspect,
An instruction is given to the excitation means so as not to vibrate the vibrator in any direction, and an instruction is given to the displacement detection means so as to detect the displacement of the vibrator in all of the first to third coordinate axis directions. And a fourth detection operation for obtaining acceleration acting in each coordinate axis direction based on the detected displacement is further performed by the control means.

(4) A fourth feature of the present invention is a multi-axis angular velocity sensor for detecting an angular velocity around each coordinate axis in a three-dimensional coordinate system,
A flexible substrate having flexibility,
A fixed substrate disposed so as to be opposed to the flexible substrate at a predetermined distance,
A vibrator fixed to the lower surface of the flexible substrate;
A sensor housing that supports the flexible substrate and the fixed substrate and houses the vibrator,
Excitation means for vibrating the vibrator in each coordinate axis direction,
Displacement detecting means for detecting displacement of the vibrator in each coordinate axis direction,
Is provided.

(5) A fifth feature of the present invention is a multi-axis angular velocity sensor that detects an angular velocity around each coordinate axis in a three-dimensional coordinate system.
A flexible substrate having flexibility,
A fixed substrate disposed so as to be opposed to the flexible substrate at a predetermined distance,
A vibrator fixed to the lower surface of the flexible substrate;
A sensor housing that supports the flexible substrate and the fixed substrate and houses the vibrator,
A plurality of lower electrodes formed on the upper surface of the flexible substrate;
A plurality of upper electrodes formed on the lower surface of the fixed substrate and arranged at positions facing each of the plurality of lower electrodes,
Means for vibrating the vibrator in each coordinate axis direction by supplying an alternating current signal between a predetermined lower electrode and upper electrode facing each other,
Means for detecting displacement in the direction of each coordinate axis of the vibrator by determining the capacitance between a predetermined lower electrode and upper electrode facing each other,
Is provided.

(6) A sixth feature of the present invention is a multiaxial angular velocity sensor having the fifth feature described above.
Define an XYZ three-dimensional coordinate system such that the X axis and the Y axis intersect on a plane parallel to the main surface of the flexible substrate,
The first lower electrode and the first upper electrode are arranged in a positive region on the X axis, the second lower electrode and the second upper electrode are arranged in a negative region on the X axis, and the third lower electrode and The third upper electrode is arranged in the positive region of the Y axis, the fourth lower electrode and the fourth upper electrode are arranged in the negative region of the Y axis, and the fifth lower electrode and the fifth upper electrode are arranged. It is arranged at a position corresponding to the origin.

(7) A seventh feature of the present invention is a multiaxial angular velocity sensor having the sixth feature described above.
In a state where an AC signal is supplied between the fifth lower electrode and the fifth upper electrode to cause the vibrator to vibrate in the Z-axis direction, a capacitance between the third lower electrode and the third upper electrode; A first detection operation of obtaining a difference between the capacitance between the fourth lower electrode and the fourth upper electrode, and detecting an angular velocity around the X axis based on the difference;
In a state where an alternating-current signal of opposite phase is supplied between the first lower electrode and the first upper electrode and between the second lower electrode and the second upper electrode to vibrate the vibrator in the X-axis direction, A second detection operation of obtaining a capacitance between the fifth lower electrode and the fifth upper electrode, and detecting an angular velocity around the Y axis based on the capacitance;
In a state where an AC signal of opposite phase is supplied between the third lower electrode and the third upper electrode and between the fourth lower electrode and the fourth upper electrode to vibrate the vibrator in the Y-axis direction, , The difference between the capacitance between the first lower electrode and the first upper electrode and the capacitance between the second lower electrode and the second upper electrode is determined. A third detection operation for detecting the angular velocity of
Is further provided.

(8) An eighth feature of the present invention is that in the multiaxial angular velocity sensor having each of the fifth to seventh features described above, the arrangement of the electrodes is changed. That is, an XYZ three-dimensional coordinate system in which the X axis and the Y axis intersect on a plane parallel to the main surface of the flexible substrate is defined,
A first lower electrode and a first upper electrode are arranged in a first quadrant area on the XY plane, a second lower electrode and a second upper electrode are arranged in a second quadrant area on the XY plane, Are arranged in the third quadrant region on the XY plane, the fourth lower electrode and the fourth upper electrode are arranged in the fourth quadrant region on the XY plane, The electrode and the fifth upper electrode are arranged at positions corresponding to the origin.

  (9) A ninth feature of the present invention is that, in the multiaxial angular velocity sensor having each of the fifth to eighth features described above, a means for arranging a piezoresistive element on a flexible substrate and detecting a capacitance Instead, means for detecting a change in the resistance value of these piezoresistive elements is provided, and the displacement of the vibrator in each coordinate axis direction is detected based on the change in the resistance value.

  (10) A tenth feature of the present invention is that, in the multiaxial angular velocity sensor having the above-described fifth to eighth features, a piezoelectric element is interposed between each of the upper electrode and each of the lower electrodes facing each other. By supplying an AC signal to the piezoelectric element, the vibrator is caused to vibrate in each coordinate axis direction, and by detecting the voltage generated by the piezoelectric element, the displacement of the vibrator in each coordinate axis direction is detected. This is to detect.

(11) An eleventh feature of the present invention is a multi-axis angular velocity sensor that detects an angular velocity around each coordinate axis in a three-dimensional coordinate system.
A plate-like piezoelectric element,
A plurality of upper electrodes formed on the upper surface of the piezoelectric element;
A plurality of lower electrodes formed on the lower surface of the piezoelectric element and arranged at positions facing the respective upper electrodes,
A flexible substrate fixed to the lower surface of the lower electrode and having flexibility;
A vibrator fixed to the lower surface of the flexible substrate;
A sensor housing that supports the flexible substrate and houses the vibrator,
Means for vibrating the vibrator in each coordinate axis direction by supplying an AC signal between a predetermined lower electrode and an upper electrode facing each other,
Means for detecting a displacement in each coordinate axis direction of the oscillator by measuring a voltage generated between a predetermined lower electrode and an upper electrode facing each other,
Is provided.

  (12) According to a twelfth feature of the present invention, in the multi-axis angular velocity sensor using the above-described piezoelectric element, the polarization characteristics of the piezoelectric element are partially inverted.

  (13) A thirteenth feature of the present invention is that a plurality of physically divided piezoelectric elements are used in the above-described multi-axis angular velocity sensor using the piezoelectric elements.

  (14) A fourteenth feature of the present invention is that, in each of the above-described multi-axis angular velocity sensors, one of the plurality of lower electrodes or the plurality of upper electrodes is constituted by a single electrode layer.

  (15) A fifteenth feature of the present invention is the multiaxial angular velocity sensor having the fourteenth feature described above, wherein the flexible substrate or the fixed substrate is formed of a conductive material, and the substrate itself is formed of a single electrode layer. It is intended to be used as.

(16) A sixteenth feature of the present invention is a multi-axis angular velocity sensor that detects an angular velocity around each coordinate axis in a three-dimensional coordinate system.
An oscillator made of a magnetic material arranged at the origin position of the coordinate system;
A sensor housing for housing the vibrator;
Connecting means for connecting the vibrator to the sensor housing with a degree of freedom such that the vibrator can be moved in each coordinate axis direction;
A first coil pair mounted on the sensor housing at positive and negative positions of a first coordinate axis of the coordinate system;
A second coil pair attached to the sensor housing at positive and negative positions of a second coordinate axis of the coordinate system;
A third coil pair attached to the sensor housing at positive and negative positions of a third coordinate axis of the coordinate system;
Exciting means for vibrating the vibrator in each coordinate axis direction by supplying a predetermined AC signal to each coil pair,
Displacement detection means for detecting a displacement of the vibrator in each coordinate axis direction based on a change in impedance of each coil pair,
Is provided.

(17) A seventeenth feature of the present invention is a multi-axis angular velocity sensor having the above-described sixteenth feature,
In a state where an AC signal is supplied to the first coil pair and the vibrator is vibrated in the first axial direction, a change in impedance of the second coil pair is obtained, and a third axis is determined based on the change in impedance. A first detection operation for detecting a peripheral angular velocity;
In a state where an AC signal is supplied to the second coil pair and the vibrator is vibrated in the third axial direction, a change in impedance of the third coil pair is obtained, and the first axis is determined based on the change in impedance. A second detection operation for detecting a peripheral angular velocity;
In a state where an AC signal is supplied to the third coil pair and the vibrator is vibrated in the third axial direction, a change in impedance of the first coil pair is obtained, and the second axis is determined based on the change in impedance. A third detection operation for detecting a peripheral angular velocity;
Is further provided.

(18) An eighteenth feature of the present invention is a multiaxial angular velocity sensor for detecting angular velocities around at least two coordinate axes in a three-dimensional coordinate system,
A vibrator with mass,
A sensor housing for housing the vibrator;
Connecting means for connecting the vibrator to the sensor housing with a degree of freedom such that the vibrator can be moved in each of three coordinate axis directions;
Exciting means for vibrating the vibrator in at least two coordinate axis directions;
Displacement detection means for detecting displacement of the vibrator in at least two coordinate axis directions;
Is provided.

(19) A nineteenth feature of the present invention is a multi-axis angular velocity sensor having the eighteenth feature described above.
An instruction is given to the excitation means to vibrate the vibrator in the direction of the first coordinate axis, and an instruction is given to the displacement detection means to detect a displacement of the vibrator in the direction of the second coordinate axis, and the detection is performed. A first detection operation for obtaining an angular velocity about a third coordinate axis based on the displacement obtained;
An instruction is given to the excitation means to vibrate the vibrator in the direction of the second coordinate axis, and an instruction is given to the displacement detection means to detect a displacement of the vibrator in the direction of the third coordinate axis. A second detection operation for obtaining an angular velocity about the first coordinate axis based on the displacement obtained;
Is further provided.

(20) A twentieth feature of the present invention is a multi-axis angular velocity sensor that detects angular velocity around two coordinate axes in a three-dimensional coordinate system,
A vibrator with mass,
A sensor housing for housing the vibrator;
Connecting means for connecting the vibrator to the sensor housing with a degree of freedom such that the vibrator can be moved in each of three coordinate axis directions;
Exciting means for vibrating the vibrator in a first coordinate axis direction;
Displacement detection means for detecting displacement of the vibrator in the second coordinate axis direction and the third coordinate axis direction;
And
Calculating an angular velocity around the third coordinate axis based on the displacement in the second coordinate axis direction detected by the displacement detection means;
The angular velocity about the second coordinate axis is obtained based on the displacement in the third coordinate axis direction detected by the displacement detecting means.

(21) A twenty-first feature of the present invention is a multi-axis angular velocity sensor for detecting angular velocities around two coordinate axes in a three-dimensional coordinate system,
A vibrator with mass,
A sensor housing for housing the vibrator;
Connecting means for connecting the vibrator to the sensor housing with a degree of freedom such that the vibrator can be moved in each of three coordinate axis directions;
Excitation means for vibrating the vibrator in a first coordinate axis direction and a second coordinate axis direction;
Displacement detection means for detecting a displacement of the vibrator in a third coordinate axis direction;
And
Calculating an angular velocity around the second coordinate axis based on the displacement in the third coordinate axis direction detected by the displacement detection means when the vibrator is vibrating in the first coordinate axis direction;
The angular velocity about the first coordinate axis is obtained based on the displacement in the third coordinate axis direction detected by the displacement detecting means when the vibrator vibrates in the second coordinate axis direction.

(22) A twenty-second feature of the present invention is a multi-axis angular velocity sensor that detects an angular velocity around each coordinate axis in a three-dimensional coordinate system,
A vibrator with mass,
A sensor housing for housing the vibrator;
Connecting means for connecting the vibrator to the sensor housing with a degree of freedom such that the vibrator can be moved in each of three coordinate axis directions;
Excitation means for vibrating the vibrator in a first coordinate axis direction and a second coordinate axis direction;
Displacement detection means for detecting a displacement of the vibrator in a second coordinate axis direction and a displacement in a third coordinate axis direction;
And
Calculating an angular velocity around the third coordinate axis based on the displacement in the second coordinate axis direction detected by the displacement detecting means when the vibrator is vibrating in the first coordinate axis direction;
Calculating an angular velocity around the second coordinate axis based on the displacement in the third coordinate axis direction detected by the displacement detection means when the vibrator is vibrating in the first coordinate axis direction;
The angular velocity about the first coordinate axis is obtained based on the displacement in the third coordinate axis direction detected by the displacement detecting means when the vibrator vibrates in the second coordinate axis direction.

<<<< Section 0 Basic Principles >>>
<0.1> Uniaxial angular velocity sensor

First, the principle of detection of angular velocity by a uniaxial angular velocity sensor, which is the basis of the multi-axis angular velocity sensor according to the present invention, will be briefly described. FIG. 1 is a diagram showing the basic principle of an angular velocity sensor disclosed on page 60 of the magazine "THE INVENTION", vol. 90, No. 3 (1993), supervised by the Japan Patent Office. Now, let us consider an XYZ three-dimensional coordinate system in which a prism-shaped vibrator 10 is prepared and X, Y, and Z axes are defined in the directions shown in the figure. In such a system, it is known that the following phenomenon occurs when the vibrator 10 performs a rotational motion at an angular velocity ω about the Z axis as a rotation axis. That is, when a vibration U that causes the vibrator 10 to reciprocate in the X-axis direction is applied, a Coriolis force F is generated in the Y-axis direction. In other words, when the vibrator 10 is rotated about the Z axis while the vibrator 10 is vibrated along the X axis in the drawing, a Coriolis force F is generated in the Y axis direction. This phenomenon is a mechanical phenomenon that has long been known as a Foucault pendulum, and the generated Coriolis force F is
F = 2m · v · ω
Is represented by Here, m is the mass of the vibrator 10, v is the instantaneous velocity of the vibration of the vibrator 10, and ω is the instantaneous angular velocity of the vibrator 10.

  The uniaxial angular velocity sensor disclosed in the aforementioned magazine detects the angular velocity ω using this phenomenon. That is, as shown in FIG. 1, a first piezoelectric element 11 is provided on a first surface of a prism-shaped vibrator 10, and a second piezoelectric element is provided on a second surface orthogonal to the first surface. 12 are respectively attached. As the piezoelectric elements 11 and 12, plate-like elements made of piezoelectric ceramics are used. The piezoelectric element 11 is used to apply the vibration U to the vibrator 10, and the piezoelectric element 12 is used to detect the generated Coriolis force F. That is, when an AC voltage is applied to the piezoelectric element 11, the piezoelectric element 11 repeatedly expands and contracts and vibrates in the X-axis direction. This vibration U is transmitted to the vibrator 10, and the vibrator 10 vibrates in the X-axis direction. As described above, when the vibrator 10 rotates at an angular velocity ω about the Z axis while the vibration U is applied to the vibrator 10, Coriolis force F is generated in the Y axis direction due to the above-described phenomenon. Since this Coriolis force F acts in the thickness direction of the piezoelectric element 12, a voltage V proportional to the Coriolis force F is generated on both surfaces of the piezoelectric element 12. Therefore, by measuring the voltage V, it becomes possible to detect the angular velocity ω.

<0.2> Multi-Axis Angular Velocity Sensor The above-described conventional angular velocity sensor is for detecting the angular velocity around the Z-axis, and cannot detect the angular velocity around the X-axis or the Y-axis. As shown in FIG. 2, according to the present invention, for a given object 20, each of an angular velocity ωx about the X axis, an angular velocity ωy about the Y axis, and an angular velocity ωz about the Z axis in the XYZ three-dimensional coordinate system is separately independent. It is intended to provide a multi-axis angular velocity sensor which can be detected by detecting the angular velocity. The basic principle will be described with reference to FIGS. Now, it is assumed that the vibrator 30 is placed at the origin position of the XYZ three-dimensional coordinate system. In order to detect the angular velocity ωx of the vibrator 30 around the X-axis, as shown in FIG. 3, when the vibrator 30 is given a vibration Uz in the Z-axis direction, the Coriolis force generated in the Y-axis direction What is necessary is just to measure Fy. The Coriolis force Fy has a value proportional to the angular velocity ωx. In order to detect the angular velocity ωy of the vibrator 30 around the Y-axis, as shown in FIG. 4, when the vibrator 30 is given a vibration Ux in the X-axis direction, it is generated in the Z-axis direction. What is necessary is just to measure the Coriolis force Fz. The Coriolis force Fz has a value proportional to the angular velocity ωy. Further, in order to detect the angular velocity ωz of the vibrator 30 about the Z-axis, as shown in FIG. 5, when the vibrator 30 is given a vibration Uy in the Y-axis direction, it is generated in the X-axis direction. What is necessary is just to measure the Coriolis force Fx. The Coriolis force Fx has a value proportional to the angular velocity ωz.

  After all, in order to detect the angular velocity for each axis in the XYZ three-dimensional coordinate system, a mechanism that vibrates the vibrator 30 in the X-axis direction, a mechanism that vibrates in the Y-axis direction, and a mechanism that vibrates in the Z-axis direction are required. , A mechanism for detecting the Coriolis force Fx in the X-axis direction acting on the vibrator 30, a mechanism for detecting the Coriolis force Fy in the Y-axis direction, and a mechanism for detecting the Coriolis force Fz in the Z-axis direction are required. .

<0.3> Vibration Mechanism / Detection Mechanism As described above, in the multi-axis angular velocity sensor according to the present invention, a mechanism for vibrating the vibrator in a specific coordinate axis direction includes a mechanism for vibrating the vibrator in a specific coordinate axis direction. A mechanism for detecting Coriolis force is required. The following mechanisms can be used as the vibration mechanism.

  (1) A mechanism using Coulomb force: a first electrode is formed on the vibrator side, and a second electrode is formed on the sensor housing side, and these pairs of electrodes are arranged to face each other. When charges of the same polarity are supplied to both electrodes, a repulsive force acts, and when charges of different polarities are supplied, a suction force acts. Therefore, if a repulsive force and a suction force are applied alternately between the two electrodes, the vibrator vibrates with respect to the sensor housing.

  (2) Mechanism using piezoelectric element: This is a mechanism used for the uniaxial angular velocity sensor shown in FIG. By supplying an AC voltage to the piezoelectric element 11, the vibrator 10 is vibrated.

  (3) Mechanism using electromagnetic force: A vibrator made of a magnetic material is used, a coil is arranged on the sensor housing side, and an electric current is applied to the coil to apply an electromagnetic force to vibrate the vibrator.

  On the other hand, the following mechanisms can be used as the mechanism for detecting the Coriolis force.

  (1) Mechanism using change in capacitance: a first electrode is formed on the vibrator side, and a second electrode is formed on the sensor housing side, and these pairs of electrodes are arranged to face each other. When the Coriolis force acts on the vibrator to cause displacement, the distance between the two electrodes changes, so that the capacitance value of the capacitance element formed by the two electrodes changes. By measuring the change in the capacitance value, the applied Coriolis force is detected.

  (2) Mechanism using piezoelectric element: This is a mechanism used for the uniaxial angular velocity sensor shown in FIG. When the Coriolis force F acts on the piezoelectric element 12, the piezoelectric element 12 generates a voltage proportional to the Coriolis force F. By measuring the generated voltage, the applied Coriolis force is detected.

  (3) A mechanism using a differential transformer: A vibrator made of a magnetic material is used, and a coil is arranged on the sensor housing side. When the Coriolis force acts on the vibrator and the displacement occurs, the distance between the vibrator and the coil changes, so that the inductance of the coil changes. By measuring the change in the inductance, the applied Coriolis force is detected.

  (4) A mechanism using a piezoresistive element: A substrate is provided so as to be bent by the action of Coriolis force. A piezoresistive element is formed on this substrate, and the bending generated on the substrate is detected as a change in the resistance value of the piezoresistive element. That is, the applied Coriolis force is detected by measuring the change in the resistance value.

  The basic principle of the multi-axis angular velocity sensor according to the present invention has been briefly described above. A specific example of a sensor having a simple structure that operates based on such a basic principle will be described in detail below.

<<<< Section 1 1st Example >>>
<1.1> Structure of Sensor According to First Embodiment First, a multiaxial angular velocity sensor according to a first embodiment of the present invention will be described. The first embodiment is a sensor using a mechanism utilizing Coulomb force as a vibration mechanism and using a mechanism utilizing change in capacitance as a detection mechanism.

  FIG. 6 is a side sectional view of the multi-axis angular velocity sensor according to the first embodiment. Each of the flexible substrate 110 and the fixed substrate 120 is a disk-shaped substrate, and is arranged in parallel with each other at a predetermined interval. A columnar vibrator 130 is fixed to the lower surface of the flexible substrate 110. The outer peripheral portion of the flexible substrate 110 and the outer peripheral portion of the fixed substrate 120 are both supported by the sensor housing 140. On the lower surface of the fixed substrate 120, five upper electrode layers E1 to E5 (only a part of which are shown in FIG. 6) are formed. A plurality of lower electrode layers F1 to F5 (only a part of which is shown) are formed. Here, the fixed substrate 120 has sufficient rigidity and does not bend, but the flexible substrate 110 has flexibility and functions as a so-called diaphragm. The vibrator 130 is made of a material having a sufficient weight to generate stable vibration. Here, for convenience of explanation, an XYZ three-dimensional coordinate system whose origin is the center of gravity O of the vibrator 130 is described here. I will consider it. That is, the X axis is defined in the right direction of the drawing, the Z axis is defined in the upward direction, and the Y axis is defined in the direction perpendicular to the plane of the drawing. FIG. 6 is a cross-sectional view of this sensor taken along the XZ plane. In this embodiment, the flexible substrate 110 and the fixed substrate 120 are both made of an insulating material. When these substrates are to be formed of a conductive material such as a metal, the respective electrode layers may be formed via an insulating film so that the electrode layers are not short-circuited.

  The shapes and arrangements of the lower electrode layers F1 to F5 are clearly shown in FIG. FIG. 7 is a top view of the flexible substrate 110, and clearly shows a state in which fan-shaped lower electrode layers F1 to F4 and a circular lower electrode layer F5 are arranged. On the other hand, the shapes and arrangements of the upper electrode layers E1 to E5 are clearly shown in FIG. FIG. 8 is a bottom view of the fixed substrate 120, and clearly shows a state in which fan-shaped upper electrode layers E1 to E4 and a circular upper electrode layer E5 are arranged. The upper electrode layers E1 to E5 and the lower electrode layers F1 to F5 have the same shape and are formed at positions facing each other. Therefore, a capacitance element is formed by the pair of opposing electrode layers, and a total of five sets of capacitance elements are formed. Here, these are referred to as capacitance elements C1 to C5, respectively. For example, an element formed by the upper electrode layer E1 and the lower electrode layer F1 is called a capacitance element C1.

<1.2> Vibration mechanism of vibrator Now, what kind of phenomenon occurs when a voltage is supplied between predetermined electrode layers of the sensor will be examined. First, consider a case where a predetermined voltage is applied between the electrode layers E1 and F1. For example, as shown in FIG. 9, when a voltage is supplied so that the electrode layer E1 side is positive and the F1 side is negative, an attractive force based on Coulomb force acts between both electrode layers. As described above, the flexible substrate 110 is a substrate having flexibility, and such a suction force causes bending. That is, as shown in FIG. 9, the flexible substrate 110 is mechanically deformed so that the distance between the electrode layers E1 and F1 to which the voltage is applied is reduced. When such mechanical deformation occurs in the flexible substrate 110, the vibrator 130 is displaced by ΔX in the positive direction of the X axis.

  Next, consider a case where a predetermined voltage is applied between the electrode layers E2 and F2. For example, as shown in FIG. 10, when a voltage is supplied so that the electrode layer E2 side is positive and the electrode F2 side is negative, an attractive force acts between them and the distance between the electrode layers E2 and F2 is reduced. The flexible substrate 110 is mechanically deformed. As a result, the transducer 130 is displaced by ΔX in the negative direction of the X axis. After all, if a voltage is applied between the electrode layers E1 and F1, the vibrator 130 is displaced in the positive direction of the X axis, and if a voltage is applied between the electrode layers E2 and F2, the vibrator 130 becomes negative in the X axis. In the direction of. Therefore, by alternately applying a voltage between the electrode layers E1 and F1 and applying a voltage between the electrode layers E2 and F2, the vibrator 130 can reciprocate in the X-axis direction.

  By the way, as shown in FIGS. 7 and 8, the above-mentioned electrode layers E1, F1, E2, F2 are electrode layers arranged on the X-axis. On the other hand, the electrode layers E3, F3, E4, and F4 are arranged on the Y axis. Therefore, if the voltage application between the electrode layers E3 and F3 and the voltage application between the electrode layers E4 and F4 are alternately performed, it is easy to reciprocate the vibrator 130 in the Y-axis direction. You can understand.

  Subsequently, a case where a predetermined voltage is applied between the electrode layers E5 and F5 will be considered. For example, as shown in FIG. 11, when a voltage is supplied such that the electrode layer E5 side is positive and the F5 side is negative, an attractive force acts between them and the distance between the electrode layers E5 and F5 is reduced. The flexible substrate 110 is mechanically deformed. Since both of the electrode layers E5 and F5 are located at the center of each substrate, the flexible substrate 110 is displaced such that it moves in parallel in the Z-axis direction without tilting. As a result, the transducer 130 is displaced by ΔZ in the positive direction of the Z axis. When the voltage application to both electrode layers E5 and F5 is stopped, the vibrator 130 returns to the original position (the position shown in FIG. 6). Therefore, if voltage is applied intermittently to both electrode layers E5 and F5, the oscillator 130 can be reciprocated in the Z-axis direction.

  As described above, by applying a voltage to a specific set of electrode layers at a specific timing, the vibrator 130 can be vibrated along the X axis, the Y axis, and the Z axis. In the above description, a positive voltage is applied to the upper electrode layers E1 to E5, and a negative voltage is applied to the lower electrode layers F1 to F5. Happens.

  Eventually, in order to cause the oscillator 130 to vibrate in the X-axis direction, a voltage V1 having a waveform as shown in FIG. 12 is supplied between the electrode layers E1 and F1, and a voltage V2 is applied to the electrode layers E2 and E2. What is necessary is just to supply between F2. When a voltage having such a waveform is supplied, a displacement ΔX as shown in FIG. 9 is generated in the vibrator 130 during the periods t1, t3, and t5, and is shown in FIG. 10 during the periods t2 and t4. Such a displacement −ΔX will occur. Similarly, in order to cause the vibrator 130 to vibrate in the Y-axis direction, a voltage V3 having a waveform as shown in FIG. 13 is supplied between the electrode layers E3 and F3, and a voltage V4 is applied to the electrode layer E4. , F4. In addition, in order to cause the vibration 130 to vibrate in the Z-axis direction, a voltage V5 having a waveform as shown in FIG. 14 may be supplied between the electrode layers E5 and F5. When the voltage V5 having such a waveform is supplied, a displacement ΔZ as shown in FIG. 11 occurs in the vibrator 130 during the periods t1, t3, and t5, and the vibrator 130 causes the flexible substrate 110 during the periods t2 and t4. 6 returns to the position shown in FIG. 6 (at this time, a displacement −ΔZ according to the inertial force is generated).

<1.3> Coriolis force detection mechanism
1.3.1 Coriolis Force Based on Angular Velocity ωx Around X-axis Next, a mechanism for detecting the Coriolis force acting on this sensor by using a change in capacitance will be described. First, a phenomenon when the angular velocity ωx around the X axis acts on this sensor will be considered. For example, when the object 20 shown in FIG. 2 is rotating around the X axis at an angular velocity ωx, if this sensor is mounted on the object 20, the angular velocity ωx Will work. By the way, as described with reference to FIG. 3, when a vibration Uz in the Z-axis direction is applied to the vibrator in a state where the angular velocity ωx about the X-axis is acting, a Coriolis force Fy is generated in the Y-axis direction. . Therefore, when a voltage V5 having a waveform as shown in FIG. 14 is supplied between the electrode layers E5 and F5 of the sensor and a vibration Uz in the Z-axis direction is applied to the vibrator 130, the Coriolis force in the Y-axis direction is obtained. Fy should occur.

  FIG. 15 is a side sectional view showing a state in which the flexible substrate 110 is mechanically deformed by the Coriolis force Fy. When the vibrator 130 is vibrated in the Z-axis direction while the entire sensor is rotating at an angular velocity ωx around the X-axis (the direction perpendicular to the paper of the drawing), a Coriolis force Fy is generated in the Y-axis direction. , A force for moving the vibrator 130 in the Y-axis direction is applied. By this force, the flexible substrate 110 is deformed as shown in the figure. Such deformation deformed in the Y-axis direction is not due to the Coulomb force between the electrode layers, but is due to the Coriolis force Fy. As for the applied voltage between the electrode layers, as described above, only the voltage V5 as shown in FIG. 14 is supplied between the electrode layers E5 and F5, and no voltage is supplied between the other electrode layers. Not. Here, since the generated Coriolis force Fy is proportional to the angular velocity ωx, if the value of the Coriolis force Fy can be measured, the angular velocity ωx can be detected.

  Therefore, the Coriolis force Fy is measured by the following method using the change in capacitance. Now, consider the distance between the upper electrode layers E1 to E5 and the lower electrode layers F1 to F5. Since the vibrator 130 is vibrating in the vertical direction in FIG. 15, the distance between both electrode layers is periodically reduced and expanded. Therefore, the capacitance values of the capacitance elements C1 to C5 (which are represented by the same reference numerals C1 to C5) each composed of the upper electrode layers E1 to E5 and the lower electrode layers F1 to F5 periodically increase or decrease. Will be repeated. However, due to the action of the Coriolis force Fy, the flexible substrate 110 is constantly deformed in the Y-axis direction, and the vibrator 130 vibrates up and down while maintaining such deformation. That is, the electrode spacing of the capacitor C3 is always smaller than the electrode spacing of the capacitor C4, and the relationship of C3> C4 is always maintained between the capacitance C3 and the capacitance C4. Since the difference ΔC34 between the capacitance values C3 and C4 depends on the degree of deviation in the Y-axis direction, the difference ΔC34 is an amount indicating the magnitude of the Coriolis force Fy. In other words, the greater the Coriolis force Fy, the greater the difference ΔC34.

  The procedure for detecting the angular velocity ωx about the X axis described above is summarized as follows. First, a voltage V5 having a waveform as shown in FIG. 14 is supplied between the electrode layers E5 and F5 to give a vibration Uz in the Z-axis direction to the vibrator 130. The difference ΔC34 is obtained. The difference ΔC34 thus obtained is a detected value of the obtained angular velocity ωx. The electrode layers E5 and F5 used to apply vibration and the electrode layers E3, F3, E4 and F4 used to measure the difference between the capacitance values are completely independent of each other electrically. There is no interference with the mechanism.

1.3.2 Coriolis force based on angular velocity ωy around Y axis Next, a phenomenon when angular velocity ωy around the Y axis acts on this sensor will be considered. As described with reference to FIG. 4, when the vibration Ux in the X-axis direction is applied to the vibrator while the angular velocity ωy around the Y-axis is acting, a Coriolis force Fz is generated in the Z-axis direction. Therefore, a voltage V1 and a voltage V2 having a waveform as shown in FIG. 12 are supplied between the electrode layers E1 and F1 and between the electrode layers E2 and F2 of the sensor, and the vibration Ux in the X-axis direction is applied to the vibrator 130. , A Coriolis force Fz should be generated in the Z-axis direction.

  FIG. 16 is a side sectional view showing a state in which the flexible substrate 110 is mechanically deformed by the Coriolis force Fz. When the vibrator 130 is vibrated in the X-axis direction while the entire sensor is rotating at an angular velocity ωy about the Y-axis (the direction perpendicular to the plane of the drawing), a Coriolis force Fz is generated in the Z-axis direction. , A force for moving the vibrator 130 in the Z-axis direction is applied. By this force, the flexible substrate 110 is deformed as shown in the figure. Such a deformation in the Z-axis direction is not due to the Coulomb force between the electrode layers but due to the Coriolis force Fz. As for the applied voltage between the electrode layers, as described above, only the voltages V1 and V2 as shown in FIG. 12 are supplied between the electrode layers E1, F1, E2 and F2, and between the other electrode layers. No voltage is supplied. Here, since the generated Coriolis force Fz is proportional to the angular velocity ωy, if the value of the Coriolis force Fz can be measured, the angular velocity ωy can be detected.

  The value of the Coriolis force Fz can be obtained based on the capacitance value C5 of the capacitance element C5 formed by the upper electrode layer E5 and the lower electrode layer F5. This is because if the Coriolis force Fz increases, the distance between the two electrode layers decreases and the capacitance value C5 increases. Conversely, if the Coriolis force Fz decreases, the distance between the two electrode layers increases and the capacitance value C5 decreases. Because it is obtained. Although the vibrator 130 vibrates in the X-axis direction, the vibration Ux has no influence on the measurement of the capacitance value C5. When the vibrator 130 is displaced in the positive or negative direction of the X axis, the upper electrode layer E5 and the lower electrode layer F5 become non-parallel, but the distance between the two electrode layers is partially reduced and partially reduced. As a whole, the vibration Ux does not affect the capacitance value C5.

  The procedure for detecting the angular velocity ωy about the Y axis described above is summarized as follows. First, a voltage V1 and a voltage V2 having a waveform as shown in FIG. 12 are supplied between the electrode layers E1, F1, E2, and F2 to give a vibration Ux in the X-axis direction to the vibrator 130, and the capacitive element at that time The capacitance value of C5 is determined. The capacitance value C5 obtained in this manner is a detected value of the angular velocity ωy to be obtained. Since the electrode layers E1, F1, E2, and F2 used to apply vibration and the electrode layers E5 and F5 used to measure the capacitance value are completely electrically independent, the vibration mechanism and the detection mechanism are not used. No interference occurs between the two.

1.3.3 Coriolis Force Based on Angular Velocity ωz Around the Z-axis Finally, consider the phenomenon when angular velocity ωz about the Z-axis acts on this sensor. As described with reference to FIG. 5, when the vibration Uy in the Y-axis direction is applied to the vibrator while the angular velocity ωz about the Z-axis is acting, a Coriolis force Fx is generated in the X-axis direction. Therefore, voltages V3 and V4 having waveforms as shown in FIG. 13 are supplied between the electrode layers E3 and F3 and between the electrode layers E4 and F4 of the sensor, and the vibration Uy in the Y-axis direction is applied to the vibrator 130. If given, a Coriolis force Fx should be generated in the X-axis direction.

  FIG. 17 is a side sectional view showing a state in which the flexible substrate 110 is mechanically deformed by the Coriolis force Fx. When the vibrator 130 is vibrated in the Y-axis direction (direction perpendicular to the paper surface) in a state where the entire sensor is rotating around the Z-axis at an angular velocity ωz, Coriolis force Fx is generated in the X-axis direction, A force for moving the child 130 in the X-axis direction is applied. By this force, the flexible substrate 110 is deformed as shown in the figure. Such a deformation that is biased in the X-axis direction is not due to the Coulomb force between the electrode layers, but is due to the Coriolis force Fx. Since this Coriolis force Fx is proportional to the angular velocity ωz, if the value of the Coriolis force Fx can be measured, the angular velocity ωz can be detected.

  This Coriolis force Fx can be measured using a change in capacitance, similarly to the Coriolis force Fy. That is, the above-described Coriolis force Fy can be obtained from the difference ΔC34 between the capacitance values C3 and C4, but the Coriolis force Fx can be obtained from the difference ΔC12 between the capacitance values C1 and C2, based on exactly the same principle. .

  The procedure for detecting the angular velocity ωz about the Z axis described above is summarized as follows. First, a voltage V3 and a voltage V4 having a waveform as shown in FIG. 13 are supplied between the electrode layers E3 and F3 and between the electrode layers E4 and F4 to apply a vibration Uy in the Y-axis direction to the vibrator 130. The difference ΔC12 between the capacitance values of the capacitance elements C1 and C2 is determined. The difference ΔC12 thus obtained is a detected value of the obtained angular velocity ωz. Since the electrode layers E3, F3, E4, and F4 used to apply vibration and the electrode layers E1, F1, E2, and F2 used to measure a difference in capacitance value are completely electrically independent, No interference occurs between the vibration mechanism and the detection mechanism.

<1.4> Coriolis Force Detection Circuit As described above, in the sensor according to the first embodiment, the angular velocity ωx about the X axis is detected by obtaining the difference ΔC34 between the capacitance values C3 and C4, and Y The angular velocity ωy about the axis is detected by obtaining a capacitance value C5, and the angular velocity ωz about the Z axis is detected by obtaining a difference ΔC12 between the capacitance values C1 and C2. Therefore, here, an example of a circuit suitable for measuring such a capacitance value or a difference between the capacitance values will be disclosed.

  FIG. 18 is an example of a circuit for measuring the capacitance value of the capacitance element C. The signal applied to input terminal T1 branches into two paths and passes through inverters 151 and 152. In the lower path, the signal passed through the inverter 152 passes through a delay circuit constituted by the resistor 153 and the capacitor C, and becomes one input signal of the exclusive OR circuit 154. In the upper path, the signal passed through the inverter 151 becomes the other input signal of the exclusive OR circuit 154 as it is. The logical output of the exclusive OR circuit 154 is provided to the output terminal T2. Here, the inverter 152 is an element provided for the purpose of giving sufficient driving capability to the delay circuit constituted by the resistor 153 and the capacitor C. The inverter 151 is an element provided for the purpose of making the upper and lower paths have the same conditions, and has the same operating characteristics as the inverter 152.

  In such a circuit, what signal is obtained at the output terminal T2 when an AC signal having a predetermined period is supplied to the input terminal T1 will be considered. FIG. 19 is a timing chart showing waveforms appearing in the respective parts when a rectangular AC signal having a half cycle f is supplied to the input terminal T1 (actually, a rectangular wave is rounded, but here, for convenience of explanation, , As a pure square wave). The waveform at the node N1, which is one input terminal of the exclusive OR circuit 154, is an inverted waveform that is delayed from the waveform given to the input terminal T1 by the time a required to pass through the inverter 151. On the other hand, the waveform at the node N2 which is the other input terminal of the exclusive OR circuit 154 is different from the waveform given to the input terminal T1 by the time a required to pass through the inverter 152, the resistance 153 and the capacitance element. An inverted waveform delayed by the total time (a + b) of the time b required to pass through the delay circuit constituted by C is obtained. As a result, the output waveform of the exclusive OR circuit 154 obtained at the output terminal T2 becomes a waveform having a pulse width b and a period f, as shown in FIG. Here, when the capacitance value of the capacitor C changes, the delay time b of the delay circuit formed by the resistor 153 and the capacitor C changes. Therefore, the obtained pulse width b is a value indicating the capacitance value of the capacitor C.

  FIG. 20 is an example of a circuit for measuring the difference ΔC between the capacitance values of the two capacitance elements C1 and C2. The signal applied to input terminal T3 branches into two paths and passes through inverters 161 and 162. In the upper path, the signal passing through the inverter 161 passes through a delay circuit constituted by the resistor 163 and the capacitor C1, and becomes one input signal of the exclusive OR circuit 165. In the lower path, the signal passing through the inverter 162 passes through a delay circuit constituted by the resistor 164 and the capacitor C2, and becomes the other input signal of the exclusive OR circuit 165. The logical output of the exclusive OR circuit 165 is provided to an output terminal T4. Here, the inverters 161 and 162 are elements provided for the purpose of giving sufficient driving capability to the delay circuit in the subsequent stage, and both have the same operation characteristics.

  In such a circuit, what signal is obtained at the output terminal T4 when an AC signal having a predetermined period is supplied to the input terminal T3 will be considered. As shown in FIG. 21, when a rectangular AC signal is supplied to the input terminal T3, the waveform at the node N3 which is one input terminal of the exclusive OR circuit 165 is an inverted waveform having a predetermined delay time d1. Similarly, the waveform at the other input terminal, node N4, is an inverted waveform having a predetermined delay time d2. As a result, the output waveform of the exclusive OR circuit 165 obtained at the output terminal T4 has a pulse width d as shown in the figure. Here, the pulse width d is a value corresponding to the difference between the delay times d1 and d2, and is a value corresponding to the difference ΔC between the capacitance values of the two capacitance elements C1 and C2. Thus, the difference ΔC in the capacitance value can be obtained as the pulse width d.

<1.5> Modification 1
In the sensor according to the first embodiment described above, the vibrator 130 is vibrated by applying a suction force based on the Coulomb force. For example, when the vibrator 130 is vibrated in the X-axis direction, as shown in FIG. 9, a first state in which charges of opposite polarities are supplied to the two electrode layers E1 and F1 to exert an attractive force, and As shown in FIG. 10, the second state in which charges of opposite polarities are supplied to both electrode layers E2 and F2 to apply a suction force may be alternately repeated. However, in order to further stabilize such vibration, it is preferable to apply a repulsive force together with a suction force. For example, as shown in FIG. 22, a positive charge is supplied to the upper electrode layer E1 and a negative charge is supplied to the lower electrode layer F1, so that a suction force is applied between the two electrode layers, and at the same time, the upper electrode When a negative charge is supplied to both the layer E2 and the lower electrode layer F2 (or a positive charge may be supplied to both), and a repulsive force is applied between both electrode layers, the vibrator 130 is moved in the positive direction of the X-axis. Can be performed more stably. The state shown in FIG. 9 and the state shown in FIG. 22 are the same in that a displacement ΔX is generated in the vibrator 130, but the former depends on a force acting on one place. The latter, on the other hand, relies on forces acting in two places, the latter being more stable than the former.

  Similarly, when the oscillator 130 is displaced by −ΔX in the negative direction of the X-axis as shown in FIG. 10, a positive charge is applied to the upper electrode layer E2 and the lower electrode is applied as shown in FIG. A negative charge is supplied to the layer F2 to apply an attractive force between the two electrode layers, and at the same time, a negative charge is supplied to both the upper electrode layer E1 and the lower electrode layer F1 (a positive charge is applied to both). May be supplied), and by applying a repulsive force between the two electrode layers, the operation can be further stabilized. After all, the first state shown in FIG. 22 and the second state shown in FIG. 23 are alternately repeated so that charges of a predetermined polarity are supplied to each electrode layer at a predetermined timing. Then, the vibrator 130 can be stably vibrated in the X-axis direction. The same applies to the case where the vibrator 130 is vibrated in the Y-axis direction.

  Next, a case where the vibrator 130 is vibrated in the Z-axis direction is considered. In the above-described embodiment, as shown in FIG. 11, a positive charge is supplied to the upper electrode layer E5 and a negative charge is supplied to the lower electrode layer F5 to apply a suction force between the two electrode layers. 6 and a neutral state in which no charge is supplied to any of the electrode layers, as shown in FIG. 6, are alternately repeated to generate the vibration Uz. In this case, the operation can be further stabilized by using the repulsive force between the two electrode layers. That is, as shown in FIG. 24, a positive charge is supplied to both the upper electrode layer E5 and the lower electrode layer F5 (a negative charge may be supplied to both), and a repulsive force acts between both electrode layers. Then, the vibrator 130 generates a displacement −ΔZ in the negative direction of the Z axis. Therefore, the first state shown in FIG. 11 and the second state shown in FIG. 24 are alternately repeated so that charges of a predetermined polarity are supplied to each electrode layer at a predetermined timing. Then, the vibrator 130 can be stably vibrated in the Z-axis direction.

  However, although it is easy to supply charges of opposite polarity to the pair of electrode layers facing each other, some measure is required to supply charges of the same polarity. That is, in order to supply charges of opposite polarity, a predetermined voltage may be applied between the two electrode layers, but such a method cannot be applied to supply charges of the same polarity. In order to solve this problem, a method in which each electrode layer has a two-layer structure via a dielectric can be used. FIG. 25 is a side sectional view of a sensor having such a structure. The lower electrode layers F1 to F5 are formed on the upper surface of the dielectric substrate 171. Between the dielectric substrate 171 and the flexible substrate 110, auxiliary electrode layers F1a to F5a are formed. The auxiliary electrode layers F1a to F5a have the same shape as the lower electrode layers F1 to F5, respectively, and are arranged at the same position. Similarly, upper electrode layers E1 to E5 are formed on the lower surface of dielectric substrate 172, and auxiliary electrode layers E1a to E5a are formed between dielectric substrate 172 and fixed substrate 120. The auxiliary electrode layers E1a to E5a have the same shape as the upper electrode layers E1 to E5, respectively, and are arranged at the same position.

  With such a two-layer structure, it is possible to freely apply a suction force and a repulsion force between specific electrode layers. This is illustrated by a specific example. FIG. 26 is a diagram in which only portions of each electrode layer and each dielectric substrate in the sensor shown in FIG. 25 are extracted and shown. For example, when it is desired to apply a suction force between the electrode layers E1 and F1, as shown in the figure, a voltage V may be applied between both electrode layers to supply charges of opposite polarity. On the other hand, when it is desired to apply a repulsive force between the electrode layers E2 and F2, a voltage V may be applied between the auxiliary substrates E2a and F2a and the electrode layers E2 and F2 as shown in the figure. . Since the voltage V is applied across the dielectric substrate 171, a negative charge is generated on the electrode layer F 2, and a positive charge is generated on the auxiliary electrode layer F 2 a. Similarly, the voltage V is applied across the dielectric substrate 172. Accordingly, a negative charge is generated in the electrode layer E2, and a positive charge is generated in the auxiliary electrode layer E2a. As a result, charges of the same polarity are supplied to both of the electrode layers E2 and F2, and a repulsive force can be applied between the two.

<1.6> Modification 2
The above-described modification 1 has a slightly more complex structure than the sensor shown in FIG. On the other hand, the second modification described here is a more simplified structure of the sensor shown in FIG. That is, in the sensor of the second modification, as shown in FIG. 27, a single common electrode layer E0 is formed instead of the upper electrode layers E1 to E5. The common electrode layer E0 is a disk-shaped electrode layer sized to face all of the lower electrode layers F1 to F5. As described above, even if one of the electrode layers is a single common electrode layer, if the common electrode layer side is always set to the reference potential, no problem occurs in the operation of the sensor. For example, when applying a voltage between specific electrode layers in order to apply vibration to the vibrator 130, the common electrode layer E0 side is grounded, and a voltage is supplied to a predetermined electrode layer among the lower electrode layers F1 to F5. do it. Similarly, when the Coriolis force is detected based on a change in the capacitance value, the capacitance elements C1 to C5 may be handled with the common electrode layer E0 side grounded.

  In this way, by replacing the five upper electrode layers E1 to E5 with a single common electrode layer E0, the mechanical structure of the sensor and the necessary wiring become simpler. If the fixed substrate 120 is made of a conductive material such as metal, the lower surface of the fixed substrate 120 can be used as the common electrode layer E0. There is no need to form the layer E0, and the structure is further simplified.

  The above is an example in which the upper electrode layers E1 to E5 are replaced with the common electrode layer E0. Conversely, the lower electrode layers F1 to F5 may be replaced with the common electrode layer F0.

<<<< Section 2 2nd Example >>>
<2.1> Structure of Sensor According to Second Embodiment Next, a multi-axis angular velocity sensor according to a second embodiment of the present invention will be described. This second embodiment is also similar to the sensor of the first embodiment described above in that a mechanism using Coulomb force is used as a vibration mechanism and a mechanism using change in capacitance is used as a detection mechanism. is there. However, the structure is formed by laminating a plurality of substrates, which is suitable for mass production.

  FIG. 28 is a side sectional view of the multi-axis angular velocity sensor according to the second embodiment. The main components of this sensor are a first substrate 210, a second substrate 220, and a third substrate 230. In this embodiment, the first substrate 210 is composed of a silicon substrate, the second substrate 220 and the third substrate 230 are composed of glass substrates, and the respective substrates are joined to each other by anodic bonding. . . The first substrate 210 is a substrate that plays a central role in this sensor, and FIG. 29 is a top view of the first substrate 210. As clearly shown in FIG. 29, the first substrate 210 is provided with L-shaped openings H1 to H4. Each of the openings H1 to H4 has a tapered shape such that the width increases as going to the lower surface. 29 is a sectional side view taken along section line 28-28 in FIG. 29, and FIG. 30 is a sectional side view taken along section line 30-30. FIG. 30 shows a tapered cross section of the openings H3 and H4. In FIG. 29, an inner square portion surrounded by four L-shaped openings H1 to H4 forms a vibrator 211, and an outer portion of the L-shaped openings H1 to H4 corresponds to the vibrator 211. Of the supporting frame 213 is formed. The vibrator 211 is connected to the support frame 213 at four points. These four connecting portions are the bridge portions 212. In other words, the vibrator 211 having a square shape is suspended by the bridge portion 212 at four positions. Moreover, as shown in FIG. 28 or FIG. 30, the bridging portion 212 is a plate-like member that is extremely thin compared to the original thickness of the first substrate 210, and has flexibility. For this reason, the vibrator 211 can move with a certain degree of freedom while being suspended by the bridge portion 212. On the upper surface of the vibrator 211, as shown in FIG. 29, five lower electrode layers G1 to G5 are formed. Like the lower electrode layers F1 to F5 in the sensor of the first embodiment, these lower electrode layers G1 to G5 have a function of generating vibration with respect to the vibrator 211 and a function of Coriolis acting on the vibrator 211. It will perform the function of detecting force.

  The second substrate 220 functions as a pedestal for supporting a peripheral portion of the first substrate 210. Therefore, a recess 221 is formed in a portion other than the periphery of the upper surface of the second substrate 220. Due to the formation of the recess 221, the vibrator 211 can maintain a suspended state without contacting the second substrate.

  The third substrate 230 functions as a lid that covers the upper surface of the first substrate 210. A bottom view of the third substrate 230 is shown in FIG. The lower surface of the third substrate 230 is cut except for a small peripheral portion, and the cut surface 231 is formed with the upper electrode layer G0. The upper electrode layer G0 has a square shape, and faces all of the lower electrode layers G1 to G5 as shown in the side sectional view of FIG. 28 or FIG. This lower electrode layer G0 corresponds to the common electrode layer E0 of the sensor shown in FIG. 27 shown as Modification 2 in the first embodiment described above.

  Such a sensor composed of three substrates is suitable for mass production. That is, each substrate may be separately subjected to mechanical processing (or chemical processing such as etching) to form an electrode layer and a wiring layer, and then joined and assembled. When a silicon substrate is used as the first substrate 210, the electrode layers G1 to G5 can be formed of a diffusion layer. Further, the electrode layer G0 may be formed by a vapor deposition layer of aluminum or the like. Thus, the electrode layer and the wiring layer can be formed by a general semiconductor planar process.

<2.2> Vibration mechanism of vibrator Now, at a predetermined timing, a predetermined timing is established between the five lower electrode layers G1 to G5 formed on the vibrator 211 and the upper electrode layer G0 opposed thereto. By supplying a voltage, a Coulomb force acts between both electrode layers, and as a result, the vibrator 211 can be vibrated in a predetermined direction, similarly to the sensor of the above-described first embodiment. . However, the arrangement of the electrode layers is slightly different between the sensor according to the second embodiment and the sensor according to the first embodiment. In the sensor of the first embodiment, as shown in FIG. 7, the electrode layers F1 and F2 are arranged on the X axis, and the electrode layers F3 and F4 are arranged on the Y axis. On the other hand, in the sensor according to the second embodiment described here, as shown in FIG. 29, none of the electrode layers G1 to G4 is arranged on the X axis or the Y axis. That is, the electrode layers G1 to G4 are arranged in the first to fourth quadrants on the XY plane, respectively. For this reason, the method of applying the voltage required to vibrate the vibrator 211 in a specific direction is slightly different from the above-described example. Hereinafter, this will be described in detail.

  To vibrate the vibrator 211 in the X-axis direction, the following is performed. Here, the potential of the upper electrode layer G0 is set to ground as a reference potential, and a predetermined voltage (for example, +5 V) with respect to this reference potential is applied to the lower electrode layers G1 to G5. First, if a voltage of +5 V is applied to both the lower electrode layers G1 and G4, an attractive force acts between the electrode layers G1 and G0 and between the electrode layers G4 and G0. As a result, the vibrator 211 enters a state in which a displacement ΔX is generated in the positive direction of the X axis. Next, the potentials of the lower electrode layers G1 and G4 are returned to the reference potential, and a voltage of +5 V is applied to both the lower electrode layers G2 and G3. Then, a suction force acts between the electrode layers G2 and G0 and between the electrode layers G3 and G0. As a result, the vibrator 211 enters a state where a displacement −ΔX is generated in the negative direction of the X axis. If a predetermined voltage is applied to each electrode layer at a predetermined timing so that these two states are alternately repeated, the vibrator 211 can be vibrated in the X-axis direction.

  The same applies to the case where the vibrator 211 is vibrated in the Y-axis direction. First, if a voltage of +5 V is applied to both the lower electrode layers G1 and G2, an attractive force acts between the electrode layers G1 and G0 and between the electrode layers G2 and G0. As a result, the vibrator 211 enters a state in which the displacement ΔY is generated in the positive direction of the Y axis. Next, the potentials of the lower electrode layers G1 and G2 are returned to the reference potential, and a voltage of +5 V is applied to both the lower electrode layers G3 and G4. Then, an attractive force acts between the electrode layers G3 and G0 and between the electrode layers G4 and G0. As a result, the vibrator 211 is in a state where a displacement −ΔY is generated in the negative direction of the Y axis. By applying a predetermined voltage to each electrode layer at a predetermined timing so that these two states are alternately repeated, the vibrator 211 can be vibrated in the Y-axis direction.

  Further, in order to vibrate the vibrator 211 in the Z-axis direction, the same method as that of the sensor of the first embodiment described above may be employed. That is, the operation of supplying +5 V to the lower electrode layer G5 or returning it to 0 V may be repeated.

<2.3> Coriolis Force Detection Mechanism In the sensor according to the second embodiment, the principle of detecting the Coriolis force acting on the vibrator 211 is the same as that of the sensor according to the first embodiment described above. It utilizes the change in capacitance. However, since there is a slight difference in the arrangement of the electrode layers, there is a slight difference in the combination of the capacitors used as the detection target. Hereinafter, this will be described in detail. Here, for convenience of description, five sets of capacitive elements formed by combining the lower electrode layers G1 to G5 and the upper electrode layer G0 are referred to as capacitive elements C1 to C5, respectively, and the capacitance values of these capacitive elements are also referred to. Also called C1 to C5.

  First, a method of detecting the Coriolis force Fx acting in the X-axis direction will be examined. According to the electrode layer arrangement shown in FIG. 29, when the Coriolis force Fx acts on the vibrator 211 in the positive direction of the X-axis, the electrode layer interval between the capacitive elements C1 and C4 is reduced, and the electrode layer interval between the capacitive elements C2 and C3 is reduced. Can easily be imagined to spread. Therefore, the capacitance values C1 and C4 increase, and the capacitance values C2 and C3 decrease. Thus, if a difference of (C1 + C4)-(C2 + C3) is obtained, this difference becomes a value corresponding to the Coriolis force Fx.

  Next, a method of detecting the Coriolis force Fy acting in the Y-axis direction will be examined. According to the electrode layer arrangement shown in FIG. 29, when the Coriolis force Fy acts on the vibrator 211 in the positive Y-axis direction, the electrode layer interval between the capacitive elements C1 and C2 is reduced, and the electrode layer interval between the capacitive elements C3 and C4 is reduced. Can easily be imagined to spread. Therefore, the capacitance values C1 and C2 increase, and the capacitance values C3 and C4 decrease. Therefore, if a difference of (C1 + C2)-(C3 + C4) is obtained, this difference becomes a value corresponding to the Coriolis force Fy.

  The method of detecting the Coriolis force Fz acting in the Z-axis direction is the same as the detection method of the sensor of the first embodiment described above. That is, the capacitance value C5 of the capacitance element C5 is a value indicating the Coriolis force Fz.

  In the sensor of this embodiment, the same electrode layer is used for both the vibration mechanism and the detection mechanism at the same time. It is necessary that the circuits to be detected do not interfere with each other.

<2.4> Modification 1
The sensor shown in FIG. 32 is a modification of the sensor according to the second embodiment shown in FIG. In this modification, a fourth substrate 240 is used in addition to the first substrate 210, the second substrate 220, and the third substrate 230. The fourth substrate 240 includes a vibrator 241 and a pedestal 242. The vibrator 241 is a square block as viewed from above, and the pedestal 242 is a frame shaped to surround the periphery. The vibrator 241 of the fourth substrate is joined to the vibrator 211 of the first substrate, and the vibrators 211 and 241 function as one vibrator as a whole. By adding the fourth substrate 240 in this manner, the mass of the vibrator can be increased, and detection with higher sensitivity can be performed. In this modification, five upper electrode layers G6 to G10 are provided as electrode layers facing the five lower electrode layers G1 to G5 instead of providing a common upper electrode layer G0.

<2.5> Modification 2
The sensor shown in FIG. 33 is another modification of the sensor according to the second embodiment shown in FIG. The substrate that functions as the center of this sensor is the flexible substrate 250. FIG. 34 is a top view of the flexible substrate 250. As shown by the broken line in the figure, an annular groove is formed on the lower surface of the flexible substrate 250, and the portion where the groove is formed has a small thickness and thus has flexibility ( This is shown as a flexible portion 252 in FIG. 33). Here, an inner portion surrounded by the annular flexible portion 252 is referred to as an action portion 251, and an outer portion of the flexible portion 252 is referred to as a fixing portion 253. A block-shaped vibrator 260 is fixed to the lower surface of the action section 251. The fixing portion 253 is supported by a pedestal 270, and the pedestal 270 is fixed to the base substrate 280. As a result, the vibrator 260 is suspended in the space surrounded by the pedestal 270. Since the thin flexible portion 252 has flexibility, the vibrator 260 can be displaced in this space with a certain degree of freedom. A cover substrate 290 is mounted on the upper part of the flexible substrate 250 so as to cover it while securing a predetermined space.

  As shown in FIG. 34, five lower electrode layers F1 to F5 are formed on the upper surface of the flexible substrate 250. These electrode layers have the same shape and the same arrangement as the lower electrode layers F1 to F5 in the sensor according to the first embodiment shown in FIG. On the lower surface of the lid substrate 290, a common upper electrode layer E0 facing all of the five lower electrode layers F1 to F5 is formed. Note that the operation of this sensor is the same as the operation of the sensor shown in FIG. 27, and a detailed description thereof will be omitted here.

<<<< Section 3 3rd Example >>>
<3.1> Structure of Sensor According to Third Embodiment Next, a multi-axis angular velocity sensor according to a third embodiment of the present invention will be described. The third embodiment is the same as the sensors of the first and second embodiments in that a mechanism utilizing Coulomb force is used as a vibration mechanism, but the detection mechanism is a piezoresistive. The feature is that a mechanism using an element is used.

  FIG. 35 is a side sectional view of the multi-axis angular velocity sensor according to the third embodiment. The main components of this sensor are a first substrate 310, a second substrate 320, a third substrate 330, and a fourth substrate 340. In this embodiment, the first substrate 310 and the third substrate 330 are formed of a silicon substrate, and the second substrate 320 and the fourth substrate 340 are formed of a glass substrate. The structure composed of such a four-layer substrate is substantially the same as the modification shown in FIG. 32 in the second embodiment. The first substrate 310 is a substrate that plays a central role in this sensor, and FIG. 36 is a top view of the first substrate 310. As shown by a broken line in the figure, an annular groove is formed on the lower surface of the first substrate 310, and the portion where the groove is formed is thin and flexible. (In FIG. 35, shown as flexible portion 312). Here, an inner portion surrounded by the annular flexible portion 312 is called an action portion 311, and an outer portion of the flexible portion 312 is called a fixing portion 313. The second substrate 320 includes a block-shaped vibrator 321 and a frame-shaped pedestal 322 surrounding the vibrator. The vibrator 321 is fixed to the bottom surface of the action section 311. The pedestal 322 is fixed to the bottom surface of the fixing portion 313.

  Third substrate 330 serves as a base substrate for supporting pedestal 322. Therefore, a recess 331 is formed in a portion other than the periphery of the upper surface of the third substrate 330. Due to the formation of the depression 331, the vibrator 321 is supported without contacting the third substrate 330. As a result, the vibrator 321 is suspended in the space surrounded by the pedestal 322. Since the thin flexible portion 312 of the first substrate 310 has flexibility, the vibrator 321 can be displaced in this space with a certain degree of freedom. In addition, a fourth substrate 340 is mounted on the first substrate 310 so as to cover it while securing a predetermined space.

  As shown in FIG. 36, five lower electrode layers F1 to F5 are formed on the upper surface of the first substrate 310. These electrode layers are equivalent to the lower electrode layers F1 to F5 in the sensor according to the first embodiment shown in FIG. However, as described later, a plurality of piezoresistors R are formed on the upper surface of the first substrate 310, and the shape of the lower electrode layers F1 to F4 avoids the region where these piezoresistors R are formed. Therefore, the shape of the lower electrode layers F1 to F4 in the sensor shown in FIG. 6 is slightly different. On the lower surface of the fourth substrate 340, a common upper electrode layer E0 facing all of the five lower electrode layers F1 to F5 is formed.

  The piezoresistive element R is an element formed by injecting an impurity into a predetermined position on the upper surface of the first substrate 310 made of silicon, and has a property that the electrical resistance changes by the action of mechanical stress. As shown in FIG. 36, there are four piezoresistive elements R along the X axis, four along the Y axis, and 45 with respect to the Y axis. A total of 12 are arranged along the oblique axis having an inclination of. Each of them is disposed at the thin flexible portion 312, and when the flexible portion 312 is bent by the displacement of the vibrator 321, the resistance value changes according to the bent. . Note that, in the side sectional view of FIG. 35, illustration of these piezoresistive elements R is omitted to avoid complication of the drawing. Here, as shown in FIG. 37, of the twelve resistance elements, four elements arranged along the X axis are called Rx1, Rx2, Rx3, and Rx4, and four elements arranged along the Y axis. Are referred to as Ry1, Ry2, Ry3, and Ry4, and the four arranged along the oblique axis are referred to as Rz1, Rz2, Rz3, and Rz4.

<3.2> Vibrator Vibration Mechanism In this sensor, the mechanism for vibrating the vibrator 321 in a predetermined axial direction is exactly the same as the sensor according to the first embodiment shown in FIG. The five lower electrode layers F1 to F5 shown in FIG. 36 are completely equivalent to the five lower electrode layers F1 to F5 shown in FIG. is there. Therefore, by applying a predetermined voltage at a predetermined timing between the five lower electrode layers F1 to F5 and the common upper electrode layer E0 opposed thereto, a Coulomb force acts between the two electrode layers. As a result, the vibrator 321 can be vibrated in any of the X, Y, and Z axes in the XYZ three-dimensional coordinate system.

<3.3> Coriolis Force Detection Mechanism A feature of the sensor according to the third embodiment is that the Coriolis force is detected using a piezoresistive element. This detection method will be described below. Now, consider a case where a Coriolis force Fx in the positive direction of the X-axis acts on the vibrator 321 as shown in FIG. 38 (to avoid complication of the figure, illustration of each electrode layer is omitted in this figure). Has been done). When the Coriolis force Fx acts, the flexible portion 312 of the first substrate 310 bends as shown in the figure. Such bending changes the resistance values of the four piezoresistive elements Rx1 to Rx4 arranged along the X axis. Specifically, the resistance values of the piezoresistive elements Rx1 and Rx3 increase (indicated by a memo code in the figure), and the resistance values of the piezoresistive elements Rx2 and Rx4 decrease (indicated by a memo code in the figure). . Moreover, the degree of the increase or decrease is proportional to the magnitude of the applied Coriolis force Fx. When the Coriolis force -Fx in the negative direction of the X-axis acts, the relationship between the increase and decrease is reversed. Therefore, by detecting a change in the resistance value of each of these piezoresistive elements, the applied Coriolis force Fx can be obtained.

  Actually, a bridge circuit as shown in FIG. 39 is formed by the four piezoresistive elements Rx1 to Rx4, and a predetermined voltage is supplied by the power supply 350. Then, the bridge voltage Vx is measured by the voltmeter 361. Here, in a reference state where the Coriolis force does not act (the state shown in FIG. 35), if the bridge circuit is set to be balanced (the bridge voltage Vx becomes zero), the measurement is performed by the voltmeter 361. The bridge voltage Vx indicates the Coriolis force Fx.

  On the other hand, when the Coriolis force Fy in the Y-axis direction acts, a similar change in resistance occurs in the four piezoresistive elements Ry1 to Ry4 arranged along the Y-axis. Therefore, if a bridge circuit as shown in FIG. 40 is formed by these four piezoresistive elements and a predetermined voltage is supplied by the power supply 350, the bridge voltage Vy measured by the voltmeter 362 reduces the Coriolis force Fy. Will show.

  Further, when the Coriolis force Fz in the Z-axis direction acts, the resistance values of the four piezoresistors Rz1 to Rz4 arranged along the oblique axis change. For example, when a Coriolis force acts in the positive direction of the Z-axis, the resistance values of the piezoresistive elements Rz1 and Rz4 decrease, and the resistance values of the piezoresistive elements Rz2 and Rz3 increase. Therefore, if a bridge circuit as shown in FIG. 41 is formed by these four piezoresistive elements and a predetermined voltage is supplied by the power supply 350, the bridge voltage Vz measured by the voltmeter 363 changes the Coriolis force Fz. Will show.

  As described above, when the Coriolis force is detected using the piezoresistive element, a mechanism for vibrating the vibrator 321 in a predetermined axial direction (using Coulomb force between the electrode layers) and a mechanism for detecting the Coriolis force Are completely independent mechanisms, and no mutual interference occurs.

<3.4> Modification Each lower electrode layer F1 to F4 in the above-described sensor is arranged on the X-axis and the Y-axis similarly to the sensor according to the above-described first embodiment. On the other hand, like the lower electrode layers G1 to G4 in the sensor according to the second embodiment shown in FIG. 29, they can be arranged in the first to fourth quadrants on the XY plane. The direction of the axis on which the four piezoresistive elements Rz1 to Rz4 are arranged may be arbitrary, and may be arranged along an axis parallel to the X axis or the Y axis.

<<<< Section 4 Fourth Example >>>
<4.1> Structure of Sensor According to Fourth Embodiment Here, a multi-axis angular velocity sensor according to a fourth embodiment of the present invention will be described. The fourth embodiment is a sensor using a mechanism using a piezoelectric element for both the vibration mechanism and the detection mechanism.

  FIG. 42 is a side sectional view of the multi-axis angular velocity sensor according to the fourth embodiment. This sensor has a structure very similar to that of the sensor according to the first embodiment shown in FIG. 6, and includes the following components. In other words, basically, the disk-shaped piezoelectric element 430 is interposed between the disk-shaped flexible substrate 410 and the disk-shaped fixed substrate 420. A cylindrical vibrator 440 is fixed to the lower surface of the flexible substrate 410. The outer peripheral portion of the flexible substrate 410 and the outer peripheral portion of the fixed substrate 420 are both supported by the sensor housing 450. Five upper electrode layers E1 to E5 (only a part thereof is shown in FIG. 42) are formed on the upper surface of the piezoelectric element 430, and similarly, five lower electrode layers F1 to F5 are formed on the lower surface. F5 (only a part of which is shown) is formed, the upper surfaces of the upper electrode layers E1 to E5 are fixed to the lower surface of the fixed substrate 420, and the lower surfaces of the lower electrode layers F1 to F5 are formed of a flexible substrate. 410 is fixed to the upper surface. Here, the fixed substrate 420 has sufficient rigidity and does not bend, but the flexible substrate 410 has flexibility and functions as a so-called diaphragm. Here, for convenience of explanation, an XYZ three-dimensional coordinate system with the center of gravity position O of the transducer 440 as the origin will be considered. That is, the X axis is defined in the right direction of the drawing, the Z axis is defined in the upward direction, and the Y axis is defined in the direction perpendicular to the plane of the drawing. FIG. 42 is a cross-sectional view of this sensor taken along the XZ plane. The shape and arrangement of the upper electrode layers E1 to E5 and the lower electrode layers F1 to F5 are exactly the same as those of the sensor of the first embodiment shown in FIG. 6 (see FIGS. 7 and 8). In this embodiment, both the flexible substrate 410 and the fixed substrate 420 are made of an insulating material. When it is desired to form these substrates from a conductive material such as a metal, an insulating film may be formed between these substrates and each electrode layer so that the electrode layers are not short-circuited.

  In general, a piezoelectric element has a first property that a voltage is generated in a predetermined direction inside a piezoelectric element when pressure is applied from the outside, and conversely, when a voltage is externally applied, a pressure is generated in a predetermined direction inside the piezoelectric element. And the second property that occurs. These two properties are two sides of the same coin. The direction in which the pressure / voltage is applied and the direction in which the voltage / pressure is generated are unique to each piezoelectric element, and such a directional property is referred to herein as a “polarization property”. I will. The piezoelectric element 430 used in the sensor of this embodiment is made of piezoelectric ceramics having polarization characteristics as shown in FIG. That is, from the viewpoint of the first property described above, as shown in FIG. 43 (a), when a force in the direction of elongation in the thickness direction is applied, a positive charge is applied to the upper electrode layer E side. Negative charges are generated on the lower electrode layer F side, respectively, and when a force in the direction of contraction in the thickness direction acts as shown in FIG. 43 (b), a negative charge is generated on the upper electrode layer E side. , And has a polarization characteristic such that positive charges are generated on the lower electrode layer F side. Conversely, from the viewpoint of the second property described above, as shown in FIG. 43 (a), a positive charge is supplied to the upper electrode layer E side and a negative charge is supplied to the lower electrode layer F side, respectively. Then, a force in the direction of elongation in the thickness direction is generated, and as shown in FIG. 43 (b), a negative charge is supplied to the upper electrode layer E side, and a positive charge is supplied to the lower electrode layer F side. For example, it has a polarization characteristic such that a force in a direction of contracting in the thickness direction is generated.

<4.2> Vibration mechanism of vibrator Now, what kind of phenomenon occurs when a charge having a predetermined polarity is supplied to a predetermined electrode layer of the sensor will be examined. When a negative charge is supplied to the electrode layer E1 and a positive charge is supplied to the electrode layer F1, a force in the direction of contraction in the thickness direction is generated in a part of the piezoelectric element sandwiched between the two electrode layers due to the property shown in FIG. 43 (b). I do. When a positive charge is supplied to the electrode layer E2 and a negative charge is supplied to the electrode layer F2, a force in the direction extending in the thickness direction is applied to a part of the piezoelectric element sandwiched between the two electrode layers due to the property shown in FIG. 43 (a). Occurs. As a result, the piezoelectric element 430 is deformed as shown in FIG. 44, and the vibrator 440 is displaced in the positive direction of the X axis. Here, when the polarity of the charge supplied to the electrode layers E1, F1, E2, and F2 is reversed, the expansion and contraction state of the piezoelectric element is also reversed, and the vibrator 440 is displaced in the negative direction of the X axis. If the polarity of the supplied charge is alternately reversed so that these two displacement states occur alternately, the vibrator 440 can be reciprocated in the X-axis direction. In other words, the vibration Ux in the X-axis direction can be given to the vibrator 440.

  Such charge supply can be realized by applying an AC signal between opposing electrode layers. That is, a first AC signal is applied between the electrode layers E1 and F1, and a second AC signal is applied between the electrode layers E2 and F2. If the signals having the same frequency and inverted phases are used as the first AC signal and the second AC signal, the vibrator 440 can be vibrated in the X-axis direction.

  The method of giving the vibration Uy in the Y-axis direction to the vibrator 440 is exactly the same. That is, a first AC signal may be applied between the electrode layers E3 and F3, and a second AC signal may be applied between the electrode layers E4 and F4.

  Next, a method of giving a vibration Uz in the Z-axis direction to the vibrator 440 will be considered. Now, when a negative charge is supplied to the electrode layer E5 and a positive charge is supplied to the electrode layer F5, due to the property shown in FIG. Occurs. As a result, the piezoelectric element 430 is deformed as shown in FIG. 45, and the vibrator 440 is displaced in the positive direction of the Z axis. Here, when the polarity of the charges supplied to the electrode layers E5 and F5 is reversed, the expansion and contraction state of the piezoelectric element is also reversed, and the vibrator 440 is displaced in the negative Z-axis direction. If the polarity of the supplied charge is alternately reversed so that these two displacement states occur alternately, the oscillator 440 can be reciprocated in the Z-axis direction. In other words, a vibration Uz in the Z-axis direction can be given to the vibrator 440. Such charge supply can be realized by applying an AC signal between the opposing electrode layers E5 and F5.

  As described above, if a predetermined AC signal is supplied to a specific set of electrode layers, the vibrator 430 can be vibrated along the X, Y, and Z axes.

<4.3> Mechanism of Detecting Coriolis Force Next, a method of detecting the Coriolis force acting in each axial direction in the sensor according to the fourth embodiment will be described. In order to save space, FIGS. 44 and 45 used in the description of the method of vibrating the vibrator will be used in the description of the method of detecting the Coriolis force.

  First, consider a case where a Coriolis force Fx in the X-axis direction acts on the vibrator 440 as shown in FIG. 44 (according to the principle shown in FIG. 5, such a measurement of the Coriolis force Fx Since the vibration is performed in the state where the vibration Uy in the Y-axis direction is given, the vibrator 440 vibrates in the direction perpendicular to the plane of the paper in FIG. 44. , And does not affect the measurement of the Coriolis force Fx in the X-axis direction). Due to the action of the Coriolis force Fx, the flexible substrate 410 that performs the function of a diaphragm is bent, and the right half of the piezoelectric element 430 has a contraction force in the thickness direction, and the left half has a force that extends in the thickness direction. Each will work. Even when the Coriolis force Fy in the Y-axis direction acts, the direction of the axis is 90. Just a shift will cause a similar phenomenon. Further, when a Coriolis force Fz in the Z-axis direction is applied, as shown in FIG. 45, the piezoelectric element 430 receives a force to shrink in the thickness direction as a whole.

  When the above-described pressure is applied to the piezoelectric element 430, charges having a predetermined polarity are generated in each electrode layer due to the properties shown in FIG. Therefore, by detecting the generated charges, the applied Coriolis force can be detected. Specifically, by applying wiring as shown in FIGS. 46 to 48 to each electrode layer, the applied Coriolis forces Fx, Fy, Fz can be detected. For example, the Coriolis force Fx in the X-axis direction can be detected as a voltage difference Vx generated between the terminal Tx1 and the terminal Tx2 as shown in FIG. The reason for this can be easily understood by considering the polarity of the charge generated in each electrode layer due to the bending as shown in FIG. That is, with respect to the electrode layers E2 and F2, since a part of the piezoelectric element 430 sandwiched between them receives a force extending in the thickness direction, as shown in FIG. 43 (a), the upper electrode layer E2 has Positive charges are generated, and negative charges are generated in the lower electrode layer F2. On the other hand, as for the electrode layers E1 and F1, since a part of the piezoelectric element 430 sandwiched between them receives a force of contracting in the thickness direction, as shown in FIG. 43 (b), the upper electrode layer E1 has A negative charge is generated in the lower electrode layer F1, and a positive charge is generated in the lower electrode layer F1. Therefore, if wiring as shown in FIG. 46 is provided, all positive charges are collected at the terminal Tx1, all negative charges are collected at the terminal Tx2, and the potential difference Vx between the two terminals indicates the Coriolis force Fx. Become. Similarly, the Coriolis force Fy in the Y-axis direction can be changed between the terminal Ty1 and the terminal Ty2 by wiring the upper electrode layers E3, E4 and the lower electrode layers F3, F4 as shown in FIG. Can be detected as the potential difference Vy. Further, the Coriolis force Fz in the Z-axis direction can be detected as a potential difference Vz generated between the terminal Tz1 and the terminal Tz2, as shown in FIG. The reason for this can be easily understood by considering the polarity of the charge generated in each electrode layer due to the bending as shown in FIG. That is, with respect to the electrode layers E5 and F5, since a part of the piezoelectric element 430 sandwiched between them receives a force for contracting in the thickness direction, as shown in FIG. 43 (b), the upper electrode layer E5 A negative charge is generated, and a positive charge is generated in the lower electrode layer F5. Therefore, as shown in FIG. 48, if wiring is provided so that positive charges are collected at the terminal Tz1 and negative charges are collected at the terminal Tz2, the potential difference Vz between the two terminals is reduced by the Coriolis force Fz in the Z-axis direction. Is shown.

<4.4> Detection of angular velocity The purpose of the multi-axis angular velocity sensor according to the present invention is to detect the angular velocity ω around the first axis, The object is to provide an axial vibration U and detect a Coriolis force F generated in the third axial direction at that time. As described above, in the sensor according to the fourth embodiment, by applying an AC signal between predetermined electrode layers, the vibrator 430 is moved along any one of the X, Y, and Z axes. Vibration can be performed, and the Coriolis forces Fx, Fy, Fz in the respective axial directions generated at that time can be detected as potential differences Vx, Vy, Vz, respectively. Therefore, according to the principle shown in FIGS. 3 to 5, it is possible to detect the angular velocity ω about any one of the X axis, the Y axis, and the Z axis.

  However, in the sensor according to this embodiment, a mechanism using a piezoelectric element is used for both the vibration mechanism and the detection mechanism. In other words, the same electrode layer may play a role of supplying charges for generating vibration (a role of a vibration mechanism), or may detect a charge generated by Coriolis force (a role of a detection mechanism). Role). It is relatively difficult to be able to play these two roles simultaneously with the same electrode layer. However, in this sensor, since the following roles are assigned to each electrode layer, two roles are not given to the same electrode layer at the same time.

  First, consider the operation of detecting the angular velocity ωx about the X axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fy generated in the Y-axis direction when the vibration Uz in the Z-axis direction is applied to the vibrator. In the sensor shown in FIG. 42, in order to apply vibration Uz to the vibrator 430, an AC signal may be supplied between the electrode layers E5 and F5. In order to detect the Coriolis force Fy acting on the vibrator 430, as shown in the circuit diagram of FIG. 47, the charges generated in the electrode layers E3, F3, E4, and F4 may be detected. The remaining electrode layers E1, F1, E2, F2 are not used in this detection operation.

  Next, let us consider an operation of detecting the angular velocity ωy around the Y axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fz generated in the Z-axis direction when the vibration Ux in the X-axis direction is applied to the vibrator. In the sensor shown in FIG. 42, in order to apply a vibration Ux to the vibrator 430, an AC signal whose phase is reversed may be supplied between the electrode layers E1 and F1 and between the electrode layers E2 and F2. In order to detect the Coriolis force Fz acting on the vibrator 430, as shown in the circuit diagram of FIG. 48, the charges generated in the electrode layers E5 and F5 may be detected. The remaining electrode layers E3, F3, E4, F4 are not used in this detection operation.

  Finally, let us consider an operation of detecting the angular velocity ωz about the Z axis based on the principle shown in FIG. In this case, when a vibration Uy in the Y-axis direction is given to the vibrator, it is necessary to detect the Coriolis force Fx generated in the X-axis direction. In the sensor shown in FIG. 42, in order to apply a vibration Uy to the vibrator 430, an AC signal whose phase is reversed may be supplied between the electrode layers E3 and F3 and between the electrode layers E4 and F4. Further, to detect the Coriolis force Fx acting on the vibrator 430, as shown in the circuit diagram of FIG. 46, it is sufficient to detect the charges generated in the electrode layers E1, F1, E2, F2. The remaining electrode layers E5 and F5 are not used in this detection operation.

  As described above, when any one of the angular velocities ωx, ωy, and ωz is detected using this sensor, it is understood that the roles of the respective electrode layers are conveniently shared, and the detection is performed without any trouble. However, since a plurality of angular velocities ωx, ωy, ωz cannot be detected at the same time, when detecting three angular velocities, it is necessary to perform time-division processing as described later and perform detection one by one in order. is there.

<4.5> Modification 1
According to the sensor according to the fourth embodiment, the Coriolis forces Fx, Fy, Fz in the XYZ three-dimensional coordinate system can be obtained as the potential differences Vx, Vy, Vz, respectively. Then, the angular velocity can be detected based on these potential differences. However, in order to detect these potential differences, it is necessary to perform wiring as shown in the circuit diagrams of FIGS. 46 to 48 for each electrode layer. In this wiring, the upper electrode layer and the lower electrode layer are disturbed. When mass-producing this sensor, the cost for the wiring cannot be ignored compared to the total cost of the product. In the first modification, the wiring is simplified and the manufacturing cost is reduced by partially changing the polarization characteristics of the piezoelectric element.

  Generally, it is possible to manufacture a piezoelectric element having arbitrary polarization characteristics by using current technology. For example, the piezoelectric element 430 used in the sensor according to the fourth embodiment described above has a polarization characteristic as shown in FIG. On the other hand, it is also possible to manufacture a piezoelectric element 460 having polarization characteristics as shown in FIG. That is, as shown in FIG. 49 (a), when a force in the direction of elongation in the thickness direction acts, a negative charge is applied to the upper electrode layer E side, and a positive charge is applied to the lower electrode layer F side. Conversely, as shown in FIG. 49 (b), when a force is applied in the direction of contraction in the thickness direction, a positive charge is applied to the upper electrode layer E and a negative charge is applied to the lower electrode layer F. Each of the charges has a polarization characteristic that is generated. Here, for convenience, the polarization characteristics as shown in FIG. 43 will be referred to as type I, and the polarization characteristics as shown in FIG. 49 will be referred to as type II. The signs of the charges generated on the upper surface and the lower surface of the piezoelectric element 430 having the type I polarization characteristic and the piezoelectric element 460 having the type II polarization characteristic are reversed. However, if the piezoelectric element 430 is turned upside down, it becomes the piezoelectric element 460. Therefore, both can be regarded as the same piezoelectric element when viewed as a single unit, and there is little meaning in distinguishing the two. However, it is also possible to provide a type I polarization characteristic to one part of one piezoelectric element and a type II polarization characteristic to another part. The modification described here is characterized in that the structure of the multi-axis angular velocity sensor is simplified by using a piezoelectric element subjected to such localized polarization processing.

  Now, consider a piezoelectric element 470 as shown in FIG. The piezoelectric element 470 is a disk-shaped element exactly the same as the piezoelectric element 430 used in the sensor shown in FIG. 42 described above. However, its polarization characteristics are different from those of the piezoelectric element 430. As described above, the piezoelectric element 430 is an element in which all portions have type I polarization characteristics. On the other hand, as shown in FIG. 50, the piezoelectric element 470 has either type I or type II polarization characteristics in the five regions A1 to A5. That is, the regions A2 and A4 exhibit the type I polarization characteristics, and the regions A1, A3 and A5 exhibit the type II polarization characteristics. Here, the regions A1 to A5 correspond to the regions where the upper electrode layers E1 to E5 or the lower electrode layers F1 to F5 are formed, respectively.

  In the sensor shown in FIG. 42, when a piezoelectric element 470 having a local polarization characteristic as shown in FIG. 50 is used instead of the piezoelectric element 430, the polarity of the electric charge generated in each electrode layer is different. Think about how it will change. Then, the polarity of the electric charge generated in the upper electrode layers E1, E3, E5 and the lower electrode layers F1, F3, F5 formed in the region having the type II polarization characteristic is changed to the sensor using the piezoelectric element 430. You can see that it is reversed. Therefore, if wirings as shown in FIGS. 51 to 53 are provided for each electrode layer, Coriolis forces Fx, Fy, and Fz can be obtained as potential differences Vx, Vy, and Vz, respectively. become. For example, as for the Coriolis force Fx in the X-axis direction, the polarity of the charges generated in the electrode layers E1 and F1 is reversed with respect to the above-described example, so that the wiring shown in FIG. 46 is replaced with the wiring shown in FIG. . Similarly, with respect to the Coriolis force Fy in the Y-axis direction, the polarity of the charges generated in the electrode layers E3 and F3 is reversed, so that the wiring shown in FIG. 47 is replaced with the wiring shown in FIG. Further, with respect to the Coriolis force Fz in the Z-axis direction, the polarity of the charges generated in the electrode layers E5 and F5 is reversed, so that the wiring shown in FIG. 48 is replaced with the wiring shown in FIG.

  When a piezoelectric element 470 having local polarization characteristics is used, the polarity of an AC signal applied to vibrate the vibrator 430 must be changed as necessary. That is, when the piezoelectric element 470 having the polarization characteristic distribution shown in FIG. 50 is used, the electrode layers E1 and F1 formed in the region A1 and the electrode layers E2 and F2 formed in the region A2 are different from each other. When an AC signal having the same phase is given, the vibrator 430 can be oscillated in the X-axis direction. It can be understood that the vibrator 430 can be vibrated in the Y-axis direction if an AC signal having the same phase is given to.

  In contrast to the wiring shown in FIGS. 46 to 48, the wiring shown in FIGS. 51 to 53 has a significant advantage in manufacturing an actual sensor. The feature of the wiring shown in FIGS. 51 to 53 is that even if Coriolis force in any direction of the X-axis, Y-axis, and Z-axis acts, the Coriolis force acts in the positive direction of each axis. If so, a positive charge is always generated on the upper electrode layer side, and a negative charge is generated on the lower electrode layer side. By using this feature, it is possible to simplify the wiring of the entire sensor. For example, consider a case where the terminals Tx2, Ty2, and Tz2 in FIGS. 51 to 53 are connected to the sensor housing 450 and set to a reference potential (earth). In this case, the five lower electrode layers F1 to F5 are electrically connected to each other. Also in this case, the potential difference Vx indicating the Coriolis force Fx in the X-axis direction is obtained as a voltage with respect to the ground of the terminal Tx1, the potential difference Vy indicating the Coriolis force Fy in the Y-axis direction is obtained as a voltage with respect to the ground of the terminal Ty1, Since the potential difference Vz indicating the Coriolis force Fz in the Z-axis direction is obtained as a voltage with respect to the ground of the terminal Tz1, this sensor operates without any trouble. Moreover, the wiring for the five lower electrode layers F1 to F5 only needs to be conducted to each other, so that a very simple wiring is sufficient.

<4.6> Modification 2
When the piezoelectric element 470 having local polarization characteristics is used as in the above-described first modification example, wiring for conducting the five lower electrode layers F1 to F5 becomes possible. As described above, if the lower electrode layers F1 to F5 can be made conductive, there is no need to dare to make these five electrode layers independent electrode layers. That is, as shown in the side sectional view of FIG. 54, only one common lower electrode layer F0 may be provided. The common lower electrode layer F0 is a single disk-shaped electrode layer, and is an electrode facing all of the five upper electrode layers E1 to E5.

<4.7> Modification 3
In order to further simplify the structure of Modification 2 described above, a flexible substrate 480 made of a conductive material (for example, metal) may be used instead of the flexible substrate 410. In this way, as shown in the side sectional view of FIG. 55, a structure in which the lower surface of the piezoelectric element 470 is directly joined to the upper surface of the flexible substrate 480 without using a special lower electrode layer F0 can be realized. . In this case, the flexible substrate 480 itself functions as the common lower electrode layer F0.

  Further, in the above-described Modifications 2 and 3, the lower electrode layer side is a common single electrode layer, but the upper electrode layer side may be a common single electrode layer.

<4.8> Other Modifications Although the above-described sensors all use a single physical piezoelectric element 430 or 470, they may be physically configured with a plurality of piezoelectric elements. For example, in FIG. 50, each of the regions A1 to A5 may be constituted by separate and independent piezoelectric elements, and a total of five piezoelectric elements may be used. As described above, how many piezoelectric elements are physically used is a matter which can be appropriately changed in design.

  In the above-described sensor, the outer peripheral portions of the flexible substrates 410 and 480 are supported by the sensor housing 450, but the flexible substrate does not necessarily need to be fixed to the sensor housing. For example, as shown in FIG. 56, a flexible substrate 490 having a slightly smaller diameter can be used instead of the flexible substrate 480, and the periphery of the flexible substrate 490 can be a free end.

<<<< Section 5 Fifth Example >>>
<5.1> Structure of Sensor According to Fifth Embodiment Here, a multi-axis angular velocity sensor according to a fifth embodiment of the present invention will be described. The fifth embodiment is also a sensor using a mechanism using a piezoelectric element for both the vibration mechanism and the detection mechanism, as in the fourth embodiment.

  FIG. 57 is a top view of the multi-axis angular velocity sensor according to the fifth embodiment. The flexible substrate 510 is a flexible disk-shaped substrate that functions as a so-called diaphragm, and a so-called donut-shaped piezoelectric element 520 is disposed on the flexible substrate 510. On the upper surface of the piezoelectric element 520, 16 upper electrode layers L1 to L16 each having the shape shown in the figure are formed at the positions shown in the figure. On the lower surface of the piezoelectric element 520, 16 lower electrode layers M1 to M16 (not shown in FIG. 57) each having exactly the same shape as each of the upper electrode layers L1 to L16 are provided. It is formed at a position facing each of L1 to L16. FIG. 58 is a side sectional view of this sensor (only the cross-sectional cut portions of each electrode layer are drawn for the sake of simplicity). As clearly shown in this figure, the donut-shaped piezoelectric element 520 has 16 upper electrode layers L1 to L16 (only L1 to L4 are shown in FIG. 58) and 16 upper electrode layers L1 to L4. (Only M1 to M4 are shown in FIG. 58) in a so-called sandwich state. The lower surfaces of the lower electrode layers M1 to M16 are fixed to the upper surface of the flexible substrate 510. On the other hand, a vibrator 550 is fixed to the lower surface of the flexible substrate 510, and a peripheral portion of the flexible substrate 510 is fixed and supported by a sensor housing 560. In this embodiment, the flexible substrate 510 is made of an insulating material. When the flexible substrate 510 is made of a conductive material such as a metal, an insulating film is formed on an upper surface of the flexible substrate 510 to prevent short circuit of the sixteen lower electrode layers M1 to M16.

  Here, for convenience of explanation, an XYZ three-dimensional coordinate system having the origin at the center position O of the flexible substrate 510 will be considered. That is, an X axis is defined in the right direction in FIG. 57, a Y axis is defined in the downward direction, and a Z axis is defined in a direction perpendicular to the plane of FIG. FIG. 58 is a cross-sectional view of this sensor taken along the XZ plane. The flexible substrate 10, the piezoelectric element 20, and the electrode layers L1 to L16 and M1 to M16 are all arranged in parallel to the XY plane. (In the fifth embodiment, the downward direction in the side sectional view is defined as the positive direction of the Z-axis for convenience of explanation). Further, as shown in FIG. 57, the X and Y axes and 45 on the XY plane. The W1 axis and the W2 axis are defined in the directions forming the angles of. Both the W1 axis and the W2 axis pass through the origin O. When such a coordinate system is defined, the upper electrode layers L1 to L4 and the lower electrode layers M1 to M4 are arranged in order from the negative direction of the X axis to the positive direction, and the upper electrode layers L5 to L8 and the lower electrode layers The layers M5 to M8 are arranged in order from the negative direction of the Y-axis to the positive direction. The upper electrode layers L13 to L16 and the lower electrode layers M13 to M16 are sequentially arranged from the negative direction to the positive direction of the W2 axis.

  Now, when an electrode layer is formed on each of the upper and lower surfaces of the piezoelectric element, and a predetermined voltage is applied between the pair of electrode layers, a predetermined pressure is generated inside the piezoelectric element, and conversely, a predetermined pressure is applied to the piezoelectric element. As described above, a predetermined voltage is generated between a pair of electrode layers when a force is applied. Therefore, each of the 16 upper electrode layers L1 to L16, the 16 lower electrode layers M1 to M16, and the 16 portions of the piezoelectric element 520 sandwiched between the 16 upper electrode layers L1 to L16 has 16 sets of localized elements. It is assumed that D1 to D16 are formed. For example, the localized element D1 is formed by the upper electrode layer L1, the lower electrode layer M1, and a part of the piezoelectric element 520 sandwiched therebetween. As a result, the 16 sets of localization elements D1 to D16 are arranged as shown in the top view of FIG.

  Here, as the piezoelectric element 520 in this sensor, a piezoelectric ceramic having polarization characteristics as shown in FIG. 60 is used. In other words, as shown in FIG. 60 (a), when a force extending in the direction extending along the XY plane acts, a positive charge is applied to the upper electrode layer L and a negative charge is applied to the lower electrode layer M. When a force in the direction of contraction along the XY plane is applied, as shown in FIG. 60 (b), a negative charge is applied to the upper electrode layer L side and the lower electrode layer M It has polarization characteristics such that positive charges are generated on the sides. Here, such a polarization characteristic is referred to as type III. Each of the 16 sets of localized elements D1 to D16 in this sensor has a piezoelectric element having type III polarization characteristics.

<5.2> Vibration Mechanism of Vibrator Subsequently, what kind of phenomenon occurs when a charge having a predetermined polarity is supplied to a predetermined electrode layer of the sensor will be examined. Now, consider a case where charges having polarities as shown in FIG. 61 are supplied to the respective electrode layers constituting the four localized elements D1 to D4 arranged on the X axis. That is, a positive charge is supplied to the electrode layers L1, M2, L3, and M4, and a negative charge is supplied to the electrode layers M1, L2, M3, and L4. Then, the localization elements D1 and D3 extend along the XY plane due to the properties shown in FIG. 60 (a). Conversely, the localized elements D2 and D4 shrink along the XY plane due to the properties shown in FIG. 60 (b). As a result, the flexible substrate 510 is deformed as shown in FIG. 61, and the vibrator 550 is displaced in the positive X-axis direction. Here, when the polarity of the charge supplied to each electrode layer is reversed, the expansion and contraction state of the piezoelectric element is also reversed, and the vibrator 550 is displaced in the negative X-axis direction. If the polarities of the supplied charges are alternately reversed so that the two displacement states occur alternately, the vibrator 550 can reciprocate in the X-axis direction. In other words, a vibration Ux in the X-axis direction can be given to the vibrator 550.

  Such charge supply can be realized by applying an AC signal between opposing electrode layers. That is, a first AC signal is applied between the electrode layers L1 and M1 and between the electrode layers L3 and M3, and a second AC signal is applied between the electrode layers L2 and M2 and between the electrode layers L4 and M4. If the signals having the same frequency and inverted phases are used as the first AC signal and the second AC signal, the vibrator 550 can be vibrated in the X-axis direction.

  The method of giving a vibration Uy in the Y-axis direction to the vibrator 550 is exactly the same. That is, a first AC signal is applied between the electrode layers L5 and M5 and between the electrode layers L7 and M7, and a second AC signal is applied between the electrode layers L6 and M6 and between the electrode layers L8 and M8. If the signals having the same frequency and inverted phases are used as the first AC signal and the second AC signal, the vibrator 550 can be vibrated in the Y-axis direction.

  Next, a method of giving a vibration Uz in the Z-axis direction to the vibrator 550 will be considered. Now, consider a case where charges having polarities as shown in FIG. 62 are supplied to the respective electrode layers constituting the four localized elements D9 to D12 arranged on the W1 axis. That is, a positive charge is supplied to the electrode layers L9, M10, M11, and L12, and a negative charge is supplied to the electrode layers M9, L10, L11, and M12. Then, the local elements D9 and D12 extend along the XY plane due to the properties shown in FIG. 60 (a). Conversely, the local elements D10 and D11 shrink along the XY plane due to the properties shown in FIG. 60 (b). As a result, the flexible substrate 510 is deformed as shown in FIG. 62, and the vibrator 550 is displaced in the positive Z-axis direction. Here, when the polarity of the charge supplied to each electrode layer is reversed, the expansion and contraction state of the piezoelectric element is also reversed, and the vibrator 550 is displaced in the negative Z-axis direction. If the polarities of the supplied charges are alternately reversed so that these two displacement states occur alternately, the vibrator 550 can be reciprocated in the Z-axis direction. In other words, a vibration Uz in the Z-axis direction can be given to the vibrator 550.

  Such charge supply can also be realized by applying an AC signal between opposing electrode layers. That is, a first AC signal is applied between the electrode layers L9 and M9 and between the electrode layers L12 and M12, and a second AC signal is applied between the electrode layers L10 and M10 and between the electrode layers L11 and M11. If the signals having the same frequency and inverted phases are used as the first AC signal and the second AC signal, the vibrator 550 can be vibrated in the Z-axis direction.

  As shown in FIG. 59, this sensor is further provided with four localized elements D13 to D16 along the W2 axis. Although these four localized elements are not always required, in this embodiment, they are provided for the purpose of further stabilizing the vibration operation in the Z-axis direction and further improving the detection accuracy of the Z-axis direction Coriolis force Fz described later. It is. These four localized elements D13 to D16 perform exactly the same functions as the above-described four localized elements D9 to D12. That is, if the same AC signal that is supplied to the localized elements D9 to D12 is supplied to the localized elements D13 to D16, the vibration operation in the Z-axis direction can be performed by the eight localized elements D9 to D16. As a result, a more stable vibration operation becomes possible.

  As described above, if a predetermined AC signal is supplied to a specific localized element, the vibrator 550 can be vibrated along the X, Y, and Z axes.

<5.3> Mechanism of Detecting Coriolis Force Next, a method of detecting the Coriolis force acting in each axial direction in the sensor according to the fifth embodiment will be described. In order to save space, FIGS. 61 and 62 used in the description of the method of vibrating the vibrator will be used in the description of the method of detecting the Coriolis force.

  First, consider a case where a Coriolis force Fx in the X-axis direction acts on the center of gravity G of the vibrator 550 as shown in FIG. 61 (according to the principle shown in FIG. Since the measurement is performed in a state in which the vibration Uy in the Y-axis direction is given, the vibrator 550 is vibrating in the direction perpendicular to the paper surface in FIG. 61. The vibration phenomenon does not affect the measurement of the Coriolis force Fx in the X-axis direction). Due to the action of the Coriolis force Fx, the flexible substrate 510 which functions as a diaphragm is bent, and the deformation as shown in FIG. 61 occurs. As a result, the localized elements D1 and D3 arranged along the X axis extend in the X axis direction, and the localized elements D2 and D4 similarly arranged along the X axis contract in the X axis direction. Since the piezoelectric element sandwiched between these electrode layers has a polarization characteristic as shown in FIG. 60, each of these electrode layers is provided with a symbol “+” or “−” surrounded by a small circle in FIG. A charge having the polarity shown is generated. Further, when the Coriolis force Fy in the Y-axis direction acts, electric charges having a predetermined polarity are similarly generated in each of the electrode layers constituting the localization elements D5 to D8 arranged along the Y-axis.

  Next, consider the case where a Coriolis force Fz in the Z-axis direction acts. In this case, the flexible substrate 510 performing the function of the diaphragm is deformed as shown in FIG. 62, and the localization elements D9 and D12 arranged along the W1 axis extend in the W1 axis direction, and similarly along the W1 axis. The localization elements D10 and D11 arranged in this manner shrink in the W1 axis direction. For this reason, charges having polarities as indicated by symbols “+” or “−” enclosed by a small circle in FIG. 62 are generated in each of the electrode layers constituting the localized elements D9 to D12. Similarly, electric charges having a predetermined polarity are generated in each of the electrode layers constituting the localization elements D13 to D16 arranged along the W2 axis.

  By utilizing such a phenomenon, the Coriolis forces Fx, Fy, and Fz can be detected by providing wirings as shown in FIGS. 63 to 65 for each electrode layer. For example, the Coriolis force Fy in the X-axis direction can be detected as a voltage difference Vx generated between the terminal Tx1 and the terminal Tx2, as shown in FIG. The reason for this can be easily understood by considering the polarity of the electric charge generated in each electrode layer due to the bending as shown in FIG. If wiring as shown in FIG. 63 is provided, all positive charges collect at the terminal Tx1, all negative charges collect at the terminal Tx2, and the potential difference Vx between both terminals indicates the Coriolis force Fx in the X-axis direction. become. In exactly the same way, the Coriolis force Fy in the Y-axis direction can be set between the terminal Ty1 and the terminal Ty2 by providing wiring as shown in FIG. 64 to each of the electrode layers constituting the localized elements D5 to D8. It can be detected as the potential difference Vy. In addition, the Coriolis force Fz in the Z-axis direction can be obtained by applying a wiring as shown in FIG. 65 to each of the electrode layers constituting the localized elements D9 to D16, by generating a voltage between the terminal Tz1 and the terminal Tz2. The difference can be detected as Vz. However, the localization elements D13 to D16 are not always necessary, and even if only the four localization elements D9 to D12 are used, the Coriolis force Fz in the Z-axis direction can be detected.

<5.4> Detection of Angular Velocity As described above, in the multi-axis angular velocity sensor according to the fifth embodiment, by applying an AC signal to a predetermined local element, the vibrator 550 is moved along the X axis and the Y axis. Vibration can be performed along any of the axis directions of the axis and the Z axis, and the Coriolis forces Fx, Fy, and Fz generated in each axis direction at that time can be detected as potential differences Vx, Vy, and Vz, respectively. . Therefore, according to the principle shown in FIGS. 3 to 5, it is possible to detect the angular velocity ω about any one of the X axis, the Y axis, and the Z axis.

  However, in the sensor according to the fifth embodiment, as in the sensor according to the fourth embodiment, a mechanism using a piezoelectric element (localized element) for both the vibration mechanism and the detection mechanism is used. I have. Therefore, the role sharing of each localized element in the detection operation of each angular velocity will be examined.

  First, consider the operation of detecting the angular velocity ωx about the X axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fy generated in the Y-axis direction when the vibration Uz in the Z-axis direction is applied to the vibrator. In order to apply the vibration Uz to the vibrator 550, an AC signal may be supplied to the localization elements D9 to D16 arranged on the W1 axis and the W2 axis. Further, in order to detect the Coriolis force Fy acting on the vibrator 550, the voltage generated in the localization elements D5 to D8 arranged on the Y axis may be detected. The remaining localized elements D1 to D4 are not used in this detection operation.

  Next, let us consider an operation of detecting the angular velocity ωy around the Y axis based on the principle shown in FIG. In this case, it is necessary to detect the Coriolis force Fz generated in the Z-axis direction when the vibration Ux in the X-axis direction is applied to the vibrator. In order to apply the vibration Ux to the vibrator 550, an AC signal may be supplied to the localization elements D1 to D4 arranged on the X axis. Further, in order to detect the Coriolis force Fz acting on the vibrator 550, it is only necessary to detect voltages generated in the localization elements D9 to D16 arranged on the W1 axis and the W2 axis. The remaining local elements D5 to D8 are not used in this detection operation.

  Finally, let us consider an operation of detecting the angular velocity ωz about the Z axis based on the principle shown in FIG. In this case, when a vibration Uy in the Y-axis direction is given to the vibrator, it is necessary to detect the Coriolis force Fx generated in the X-axis direction. In order to apply the vibration Uy to the vibrator 550, an AC signal may be supplied to the localization elements D5 to D8 arranged on the Y axis. Further, in order to detect the Coriolis force Fx acting on the vibrator 550, a voltage generated in the localization elements D1 to D4 arranged on the X axis may be detected. The remaining local elements D9 to D16 are not used in this detection operation.

  As described above, when any one of the angular velocities ωx, ωy, and ωz is detected using this sensor, it is understood that the roles of the localized elements are conveniently shared, and the detection is performed without any trouble. However, since a plurality of angular velocities ωx, ωy, ωz cannot be detected at the same time, when detecting three angular velocities, it is necessary to perform time-division processing as described later and perform detection one by one in order. is there.

<5.5> Modification 1
According to the sensor according to the fifth embodiment described above, the Coriolis forces Fx, Fy, Fz in the XYZ three-dimensional coordinate system can be obtained as the potential differences Vx, Vy, Vz, respectively. Then, the angular velocity can be detected based on these potential differences. However, in order to detect these potential differences, it is necessary to perform wiring as shown in the circuit diagrams of FIGS. 63 to 65 for each electrode layer. In this wiring, the upper electrode layer and the lower electrode layer are disturbed. When mass-producing this sensor, the cost for the wiring cannot be ignored compared to the total cost of the product. In the first modification, the wiring is simplified and the manufacturing cost is reduced by partially changing the polarization characteristics of the piezoelectric element.

  As described above, it is possible to manufacture a piezoelectric element having arbitrary polarization characteristics by using current technology. For example, the piezoelectric element 520 used in the sensor according to the fifth embodiment described above had a type III polarization characteristic as shown in FIG. On the other hand, it is also possible to manufacture a piezoelectric element 530 having a type IV polarization characteristic as shown in FIG. That is, as shown in FIG. 66 (a), when a force extending in the direction extending along the XY plane acts, a negative charge is applied to the upper electrode layer L and a positive charge is applied to the lower electrode layer M. When a force is applied in the direction of contraction along the XY plane as shown in FIG. 66 (b), a positive charge is applied to the upper electrode layer L side, and the lower electrode layer M It is possible to manufacture the piezoelectric element 530 having polarization characteristics such that negative charges are generated on the sides. It is also possible to provide a part of one piezoelectric element with a type III polarization characteristic and another part with a type IV polarization characteristic. The modification described here simplifies the structure of the sensor by using a piezoelectric element subjected to such localized polarization processing.

  Now, consider a piezoelectric element 540 as shown in FIG. This piezoelectric element 540 is a doughnut-shaped element exactly the same as the piezoelectric element 520 used in the sensor of FIG. 57 described above. However, its polarization characteristics are different from those of the piezoelectric element 520. As described above, the piezoelectric element 520 is an element in which all portions have type III polarization characteristics. On the other hand, as shown in FIG. 67, the piezoelectric element 540 has either type III or type IV polarization characteristics in each of the 16 regions. That is, in the regions of the localization elements D1, D3, D5, D7, D9, D12, D13, and D16, polarization characteristics of type III are exhibited, and the localization elements D2, D4, D6, D8, D10, D11, D14, and D15 The region (4) shows polarization characteristics of type IV (see FIGS. 59 and 67).

  When the piezoelectric element 540 having the polarization characteristics shown in FIG. 67 is used instead of the piezoelectric element 520 in the sensor of FIG. 57 described above, what is the polarity of the charges generated in each electrode layer? Considering whether the upper electrode layers L2, L4, L6, L8, L10, L11, L14, L15 and the lower electrode layers M2, M4, formed in the region having the polarization characteristics of type IV, It can be seen that the polarities of the charges generated in M6, M8, M10, M11, M14, and M15 are inverted. For example, when the Coriolis force Fx in the X-axis direction acts, the above-described sensor of FIG. 57 generates a charge having a polarity as shown in FIG. 61, whereas the sensor of this modification example is shown in FIG. 68. Charges of such polarity are generated. When the Coriolis force Fz in the Z-axis direction acts, charges of the polarity shown in FIG. 62 are generated in the sensor of FIG. 57 described above, whereas charges of the polarity shown in FIG. Charges of such polarity are generated. Therefore, if wirings as shown in FIGS. 70 to 72 are provided for each electrode layer, Coriolis forces Fx, Fy, Fz can be obtained as potential differences Vx, Vy, Vz, respectively. become.

  For example, regarding the detection operation of the Coriolis force Fx in the X-axis direction, the wirings shown in FIG. 63 are replaced with the wirings shown in FIG. Can be Similarly, regarding the operation of detecting the Coriolis force Fy in the Y-axis direction, the polarity of the charges generated in the electrode layers L6, M6 and L8, M8 is reversed, so that the wiring shown in FIG. Be replaced. Further, regarding the operation of detecting the Coriolis force Fz in the Z-axis direction, the polarity of the charges generated in the electrode layers L10, M10, L11, M11, L14, M14, and L15, M15 is reversed, so that the wiring shown in FIG. Is replaced by the wiring shown in FIG.

  When the piezoelectric element 540 having local polarization characteristics is used, the AC signal applied to vibrate the vibrator 550 is also simplified. That is, when vibrating in the X-axis direction, as shown in FIG. 68, an in-phase AC signal may be supplied to all of the localization elements D1 to D4. Similarly, when vibrating in the Y-axis direction, May supply an in-phase AC signal to all of the localization elements D5 to D8. In the case of vibrating in the Z-axis direction, an in-phase AC signal may be supplied to all of the localization elements D9 to D16 as shown in FIG.

  The wiring shown in FIGS. 70 to 72 has a significant merit in manufacturing an actual sensor, compared to the wiring shown in FIGS. 63 to 65. The feature of the wiring shown in FIGS. 70 to 72 is that even when Coriolis force acts in any of the X, Y, and Z axes, the Coriolis force acts in the positive direction of each axis. If so, a positive charge is always generated on the upper electrode layer side, and a negative charge is generated on the lower electrode layer side. By using this feature, it is possible to simplify the wiring of the entire sensor. For example, consider a case where the terminals Tx2, Ty2, and Tz2 in FIGS. 70 to 72 are connected to the sensor housing 560 and set to a reference potential (earth). In this case, the 16 lower electrode layers M1 to M16 are in a conductive state with each other. Also in this case, the potential difference Vx indicating the Coriolis force Fx in the X-axis direction is obtained as a voltage with respect to the ground of the terminal Tx1, the potential difference Vy indicating the Coriolis force Fy in the Y-axis direction is obtained as a voltage with respect to the ground of the terminal Ty1, Since the potential difference Vz indicating the Coriolis force Fz in the Z-axis direction is obtained as a voltage with respect to the ground of the terminal Tz1, this sensor operates without any trouble. Moreover, the wiring for the sixteen lower electrode layers M1 to M16 only needs to be conducted to each other, so that a very simple wiring is sufficient.

<5.6> Modification 2
When the piezoelectric element 540 having a local polarization characteristic is used as in the above-described first modification, wiring for conducting the 16 lower electrode layers M1 to M16 can be realized. Thus, if the lower electrode layers M1 to M16 can be made conductive, it is not necessary to dare to make these 16 electrode layers independent electrode layers. That is, as shown in the side sectional view of FIG. 73, only one common lower electrode layer M0 may be provided. The common lower electrode layer M0 is a single donut-shaped electrode layer, and serves as an electrode facing all of the 16 upper electrode layers L1 to L16.

<5.7> Modification 3
In order to further simplify the structure of Modification 2 described above, a flexible substrate 570 made of a conductive material (for example, metal) may be used instead of the flexible substrate 510. This can realize a structure in which the lower surface of the piezoelectric element 540 is directly joined to the upper surface of the flexible substrate 570 without using a special lower electrode layer M0, as shown in the side sectional view of FIG. . In this case, the flexible substrate 570 itself functions as a common lower electrode layer M0.

  Further, in the above-described Modifications 2 and 3, the lower electrode layer side is a common single electrode layer, but the upper electrode layer side may be a common single electrode layer.

<5.8> Other Modifications Although each of the above-described sensors physically uses a single piezoelectric element 520 or 540, these may be physically configured by a plurality of piezoelectric elements. For example, in FIG. 59, each of the localization elements D1 to D16 may be configured using separate and independent piezoelectric elements, and a total of 16 piezoelectric elements may be used. Also, for example, one localized element is used for two localized elements, such as using a single piezoelectric element for localized elements D1 and D2 and using another piezoelectric element for localized elements D3 and D4. , A total of eight piezoelectric elements can be used. As described above, how many piezoelectric elements are physically used is a matter which can be appropriately changed in design.

<<<< Section 6 Sixth Example >>>
<6.1> Principle of Sensor According to Sixth Embodiment The multi-axis angular velocity sensor according to the sixth embodiment described here uses a mechanism using electromagnetic force as a vibration mechanism, and uses a differential transformer as a detection mechanism. This is a sensor using the mechanism used. First, the principle will be briefly described with reference to FIG. Now, an origin O is set at the position of the center of gravity of the vibrator 610 made of a magnetic material, and an XYZ three-dimensional coordinate system is defined. Then, a pair of coils J1 and J2 are provided on the X axis, a pair of coils J3 and J4 are provided on the Y axis, and a pair of coils J5 and J6 are provided on the Z axis so as to sandwich the vibrator 610.

  By arranging the six coils in this way, it is possible to vibrate the vibrator 610 made of a magnetic material in any of the X, Y, and Z axes. For example, in order to apply the vibration Ux in the X-axis direction, the coils J1 and J2 disposed on the X-axis may be energized alternately. When the coil J1 is energized, the vibrator 610 moves in the positive direction of the X axis due to the magnetic force generated by the coil J1. Move in the negative direction. Therefore, if current is alternately applied, the vibrator 610 reciprocates in the X-axis direction. Similarly, in order to apply the vibration Uy in the Y-axis direction, the coils J3 and J4 disposed on the Y-axis may be energized alternately, and in order to apply the vibration Uz in the Z-axis direction, What is necessary is just to energize the arranged coils J5 and J6 alternately.

  On the other hand, the displacement of the vibrator 610 made of a magnetic material can be detected by the six coils arranged as described above. For example, when the vibrator 610 is displaced in the positive direction of the X axis, the distance between the vibrator 610 and the coil J1 is short, and the distance between the vibrator 610 and the coil J2 is long. Generally, a change in the distance of the magnetic material from the coil causes a change in the inductance of the coil. Therefore, if the change in the inductance of the coil J1 and the change in the inductance of the coil J2 are detected, the displacement of the vibrator 610 in the X-axis direction can be recognized. Similarly, the displacement of the vibrator 610 in the Y-axis direction can be recognized based on the change in the inductance of the coil J3 and the change in the inductance of the coil J4. The displacement of the child 610 in the Z-axis direction can be recognized. Therefore, if the vibrator 610 is configured to be displaced by Coriolis force, the Coriolis force in each axial direction can be detected by the change in inductance of each coil.

  As described above, the coils J1 to J6 have the function of vibrating the vibrator 610 and the function of detecting the displacement of the vibrator 610, but the vibrating coil and the detecting coil may be provided separately. Good.

<6.2> Specific sensor structure and operation The seventy-sixth is a sectional side view showing a specific structure of a multi-axis angular velocity sensor based on the above-described principle. A cylindrical vibrator 610 made of a magnetic material such as iron is housed in a sensor housing 620. A partition plate 630 is joined to the upper surface of the sensor housing 620, and a dish-shaped diaphragm 640 is attached to the upper surface of the partition plate 630 in a state where the diaphragm 640 faces down. The upper end of a connecting rod 650 is fixed to the center of the diaphragm. A through hole is formed at the center of the partition plate 630, and the connecting rod 650 passes through the through hole. A vibrator 610 is attached to a lower end of the connecting rod 650, and the vibrator 610 is suspended in the sensor housing 620 by the connecting rod 650. A protective cover 660 is attached above the partition plate 630 so as to cover the diaphragm 640.

  Here, the origin O is set at the position of the center of gravity of the vibrator 610, the Y axis is set to the right in FIG. 76, the Z axis is set to the upper side, and the X axis is set to a direction perpendicular to the paper surface. Then, six coils J1 to J6 are arranged inside the sensor housing 620 as shown in the figure (the coils J1 and J2 are not shown in FIG. However, the coil J2 is arranged on the other side). This arrangement is the same as the arrangement shown in FIG.

  As described above, by energizing the predetermined coil, the vibrator 610 can be vibrated in the predetermined axial direction, and by detecting a change in the inductance of the predetermined coil, the vibrator 610 can operate in the predetermined axial direction. The detected Coriolis force can be detected. Therefore, it is possible to detect the angular velocity around a predetermined axis based on the basic principle shown in FIGS.

<<<< Section 7 Detection operation >>>
<7.1> Detection of Acceleration Although the various embodiments described above are all multiaxial angular velocity sensors, these sensors also have a function as a multiaxial acceleration sensor. This will be shown for the sensor of the first embodiment. FIG. 15 is a view for explaining the operation of detecting the angular velocity ωx about the X axis in the sensor according to the first embodiment. To detect the angular velocity ωx, the Coriolis force Fy acting in the Y-axis direction may be measured in a state where the vibration Uz in the Z-axis direction is applied to the vibrator 130. The reason why the Coriolis force Fy in the Y-axis direction is generated is that the vibrator 130 is intentionally vibrated in the Z-axis direction in a state where the angular velocity ωx is applied. If the vibrator 130 is not vibrated, no Coriolis force Fy is generated. However, even when the vibrator 130 is not vibrated, a force Fy for moving the vibrator 130 in the Y-axis direction may be generated. This is a case where acceleration in the Y-axis direction acts on the vibrator 130. According to the basic law of dynamics, when an acceleration acts on an object having mass, a force proportional to the mass of the object acts in the same direction as the acceleration. Therefore, when acceleration in the Y-axis direction acts on the vibrator 130, a force Fy in the Y-axis direction having a magnitude proportional to the mass of the vibrator 130 acts. As described above, the force Fy and the Coriolis force Fy caused by the acceleration are exactly the same as the force, and the force caused by the acceleration can be detected by the exactly same method as the method of detecting the Coriolis force.

  After all, in the sensors of the above-described embodiments, the force detected in the predetermined axial direction while the vibrator is intentionally vibrated in the predetermined axial direction is Coriolis force, and the magnitude of this Coriolis force is The value corresponds to the angular velocity around the predetermined axis. However, the force detected in a predetermined axial direction without vibrating the vibrator is a force based on the acceleration acting in the axial direction, and the magnitude of this force is a value corresponding to the acceleration in the axial direction. It becomes. As described above, the sensor of each embodiment described above functions as an angular velocity sensor if measurement is performed with the vibrator vibrated, but functions as an acceleration sensor if measurement is performed without vibrating the vibrator. Become.

<7.2> Time-Division Detection Operation As described above, the sensor according to the present invention has both a function as a multi-axis angular velocity sensor and a function as a multi-axis acceleration sensor. Therefore, in practice, a time-division detection operation as shown in the flow chart of FIG. 77 is performed to obtain an acceleration αx in the X-axis direction, an acceleration αy in the Y-axis direction, an acceleration αz in the Z-axis direction, and an angular velocity around the X-axis. ωx, an angular velocity ωy about the Y axis, and an angular velocity ωz about the Z axis can be detected.

  First, in step S1, the accelerations αx, αy, αz in the respective axial directions are simultaneously detected. That is, a detection process equivalent to the detection of Coriolis force may be performed without vibrating the vibrator. The force detected at this time is not a Coriolis force but a force generated based on the acceleration. Regarding acceleration, it is possible to detect three axis components simultaneously. This is because there is no need to perform an operation of applying vibration to the vibrator, and each electrode layer does not need to play a role as a vibration mechanism, but only plays a role as a detection mechanism. For example, in the case of the sensor according to the fourth embodiment shown in FIG. 42, a circuit as shown in FIGS. 46 to 48 is formed for detecting the Coriolis force. In the case of detecting the acceleration, it is not necessary to supply an AC signal for giving a vibration, so that an AC signal is given to any of the electrode layers E1 to E5 and F1 to F5 shown in these circuits. No need. Therefore, the potential differences Vx, Vy, Vz detected by these circuits directly indicate the accelerations αx, αy, αz.

  Subsequently, the angular velocity ωx is detected in step S2, the angular velocity ωy is detected in the next step S3, and the angular velocity ωz is detected in the following step S4. As for the angular velocities, as described above, it is not possible to simultaneously detect the angular velocities around the three axes. Therefore, the detection of each angular velocity is performed in order by such time division.

  Finally, the process returns from step S5 to step S1 again, and the same operation is repeatedly performed as long as the detection operation is continuously performed.

<7.3> Detection Circuit Next, FIG. 78 shows a basic configuration of a detection circuit for performing the above-described time-division detection operation. Here, the block 700 corresponds to the various embodiments of the multi-axis angular velocity sensor described above, and is divided into two parts, a vibration part 710 and a detection part 720, from the viewpoint of function. is there. The vibrating unit 710 is a part having a function of vibrating the built-in vibrator in a predetermined axial direction. When a drive signal is supplied to each terminal indicated by X, Y, and Z in FIG. , Y axis and Z axis. The detection section 720 is a section having a function of outputting a detection signal indicating the displacement of the built-in vibrator. The X-axis, Y-axis, and Z-axis are respectively provided from terminals indicated as X, Y, and Z in the drawing. A detection signal of displacement in the axial direction is output. In an actual sensor, one electrode layer may have both the function of the vibrating section 710 and the function of the detecting section 720, and each part constituting the sensor may be provided by either the vibrating section 710 or the detecting section 720. Although it is difficult to classify the sensor clearly, here, for the sake of convenience, this sensor will be represented by a simple model such as a block 700 by functionally capturing the sensor.

  The vibration generation circuit 711 is a circuit that generates a drive signal to be supplied to each of the terminals X, Y, and Z of the vibration unit 710, and specifically, is, for example, a device that generates an AC signal. The multiplexer 712 has switches SW1, SW2, and SW3, and controls which of the terminals X, Y, and Z of the vibration unit 710 supplies the drive signal generated by the vibration generation circuit 711. On the other hand, the detection signals output from the terminals X, Y, and Z of the detection unit 720 are provided to the displacement detection circuit 721 via the multiplexer 722. The multiplexer 722 has switches SW4, SW5, and SW6, and selects a detection signal to be supplied to the displacement detection circuit 721. The displacement detection circuit 721 detects a specific displacement amount based on the supplied detection signal, and supplies the detected displacement amount to the detection value output circuit 730. The controller 740 controls the operations of the multiplexers 712 and 722 and provides a control signal to the detection value output circuit 730.

  The above is the configuration of the detection circuit. FIG. 78 is not a specific circuit diagram showing an actual current path, but a diagram showing an outline of the configuration of a detection circuit. Therefore, one line shown in the figure indicates a path of a group of control signals or detection signals, and does not indicate a current path itself. For example, only one control signal line is drawn between the switch SW1 and the terminal X of the vibrating unit 710. However, in order to vibrate the vibrator in the X-axis direction, a plurality of control signal lines are actually used. It is necessary to supply an AC signal having a predetermined phase to the electrode layer, and a plurality of current paths are required.

  If such a detection circuit is configured, the detection operation shown in the flowchart of FIG. 77 is executed as follows. First, the controller 740 performs a process of detecting the accelerations αx, αy, αz as Step S1. That is, the controller 740 gives an instruction to the multiplexers 712 and 722 to turn off all the switches SW1, SW2 and SW3 and turn on all the switches SW4, SW5 and SW6. As a result, no drive signal is supplied to the vibrating section 710, and no intentional excitation of the vibrator is performed. Therefore, at this time, the detection signals output from the terminals X, Y, and Z of the detection unit 720 are signals indicating a displacement generated by a force based on the action of the acceleration, not the Coriolis force. Since the switches SW4, SW5, and SW6 are all ON, all three signals are supplied to the displacement detection circuit 721, where the amounts of displacement in the X, Y, and Z axes are detected. The controller 740 instructs the detection value output circuit 730 to output the detected three displacement amounts as acceleration values. Thus, the displacement amounts in the three axial directions detected by the displacement detection circuit 721 are output from the detection value output circuit 730 as acceleration values αx, αy, αz, respectively.

Subsequently, the controller 740 performs a process of detecting the angular velocity ωx as Step S2. That is, the controller 740 is based on the principle shown in FIG.
Switch SW1: OFF Switch SW4: OFF
Switch SW2: OFF Switch SW5: ON
Switch SW3: ON Switch SW6: OFF
Is given to the multiplexers 712 and 722. As a result, the vibrating section 710 gives a vibration Uz in the Z-axis direction to the vibrator, and the detecting section 720 outputs from the terminal Y a detection signal indicating the displacement of the vibrator in the Y-axis direction due to the action of the Coriolis force Fy generated at this time. I do. The displacement detection circuit 721 detects the amount of displacement in the Y-axis direction based on the detection signal. The controller 740 instructs the detection value output circuit 730 to output the detected displacement amount as the value of the angular velocity ωx around the X axis. Thus, the displacement amount in the Y-axis direction detected by the displacement detection circuit 721 is output from the detection value output circuit 730 as the angular velocity ωx.

Next, the controller 740 performs a process of detecting the angular velocity ωy as Step S3. That is, the controller 740 is based on the principle shown in FIG.
Switch SW1: ON Switch SW4: ON
Switch SW2: OFF Switch SW5: OFF
Switch SW3: OFF Switch SW6: OFF
Is given to the multiplexers 712 and 722. As a result, the vibrating unit 710 gives a vibration Ux in the X-axis direction to the vibrator, and the detecting unit 720 outputs from the terminal Z a detection signal indicating the displacement of the vibrator in the Z-axis direction due to the action of the Coriolis force Fz generated at this time. I do. The displacement detection circuit 721 detects a displacement amount in the Z-axis direction based on the detection signal. The controller 740 instructs the detection value output circuit 730 to output the detected displacement amount as the value of the angular velocity ωy around the Y axis. Thus, the displacement amount in the Z-axis direction detected by the displacement detection circuit 721 is output from the detection value output circuit 730 as an angular velocity ωy.

Further, the controller 740 performs a process of detecting the angular velocity ωz as Step S4. That is, the controller 740 is based on the principle shown in FIG.
Switch SW1: OFF Switch SW4: OFF
Switch SW2: ON Switch SW5: OFF
Switch SW3: OFF Switch SW6: ON
Is given to the multiplexers 712 and 722. As a result, the vibrating section 710 gives a vibration Uy in the Y-axis direction to the vibrator, and the detecting section 720 outputs from the terminal X a detection signal indicating the displacement of the vibrator in the X-axis direction due to the action of the Coriolis force Fx generated at this time. I do. The displacement detection circuit 721 detects a displacement amount in the X-axis direction based on the detection signal. The controller 740 instructs the detection value output circuit 730 to output the detected displacement amount as the value of the angular velocity ωz about the Z axis. Thus, the displacement amount in the X-axis direction detected by the displacement detection circuit 721 is output from the detection value output circuit 730 as the angular velocity ωz.

  The above processing is repeatedly executed after step S5. Therefore, if this sensor is mounted on a moving object, it is possible to continuously detect the acceleration in the three-axis directions and the angular velocities around the three axes at each time point.

<7.4> Another Principle of Detecting Angular Velocity The description so far regarding the detection of the multiaxial angular velocity has been based on the basic principle shown in FIGS. 3 to 5. On the other hand, detection based on the basic principle shown in FIGS. 79 to 81 is also possible. For example, when detecting the angular velocity ωx about the X-axis, according to the basic principle shown in FIG. 3, the Coriolis force Fy generated in the Y-axis direction when a vibration Uz in the Z-axis direction is applied to the vibrator is detected. In other words, according to the basic principle shown in FIG. 79, it is only necessary to detect the Coriolis force Fz generated in the Z-axis direction when a vibration Uy in the Y-axis direction is applied to the vibrator. Similarly, when detecting the angular velocity ωy around the Y axis, according to the basic principle shown in FIG. 4, the Coriolis force Fz generated in the Z axis direction when the vibration Ux in the X axis direction is applied to the vibrator is detected. However, according to the basic principle shown in FIG. 80, it is only necessary to detect the Coriolis force Fx generated in the X-axis direction when a vibration Uz in the Z-axis direction is applied to the vibrator. When detecting the angular velocity ωz around the Z-axis, according to the basic principle shown in FIG. 5, the Coriolis force Fx generated in the X-axis direction when a vibration Uy in the Y-axis direction is applied to the vibrator is detected. In other words, according to the basic principle shown in FIG. 81, the Coriolis force Fy generated in the Y-axis direction when the vibration Ux in the X-axis direction is applied to the vibrator may be detected.

  In short, the multi-axis angular velocity sensor according to the present invention generates the vibration U in the second axial direction when the angular velocity ω is acting around the first axis with respect to the vibrator located at the origin of three axes orthogonal to each other. This applies a natural law that a Coriolis force acts in the third axial direction if given, and even if an axis is selected as shown in FIG. 3 to FIG. It does not matter which axis is selected as shown in the figure. Therefore, it is possible to perform detection applying the basic principle shown in FIGS. 79 to 81 for all the embodiments described so far.

<7.5> Detection by Combination of Basic Principles As described above, in the angular velocity detection according to the present invention, detection based on the basic principles shown in FIGS. 3 to 5 and detection based on the basic principles shown in FIGS. Any of detection based on the principle is possible, and detection in which both are combined is also possible. Here, when each basic principle is arranged for easy understanding, it is understood that six kinds of detection operations as shown in the following table are possible.

<U><F><ω> Principle diagram detection operation 1 XYZ FIG. 81 detection operation 2 XZY FIG. 4 detection operation 3 YZX FIG. 79 detection operation 4 YXZ FIG. 5 detection operation 5 ZXY FIG. 80 Detection Operation 6 ZYX FIG.

Here, the U column indicates the axial direction for exciting the vibrator, the F column indicates the axial direction for detecting the Coriolis force acting on the vibrator, and the ω column indicates the axis relating to the angular velocity to be detected. The detection based on the basic principle shown in FIGS. 3 to 5 is for performing the three even-numbered detection operations in the above table, and the detection based on the basic principle shown in FIGS. The three odd-numbered detection operations are performed. As described above, the angular velocities around the three XYZ axes can be detected by the three detection operations.

  Incidentally, the combination for detecting such angular velocities around the three axes is not limited to the even-numbered and odd-numbered combinations. For example, the angular velocities around the three axes of XYZ can be detected by the combination of the detection operations 1 to 3 in the first half, and the angular velocities around the three axes of XYZ can be detected by the combination of the detection operations 4 to 6 in the second half (see the above table). ω)). Moreover, when such a combination is adopted, a part of the vibration mechanism and the detection mechanism can be omitted. For example, in order to perform the detection operations 1 to 3 in the above table, the excitation axes of the vibrator need only be the X axis and the Y axis (see the column of U). In other words, it is not necessary to vibrate the vibrator in the Z-axis direction. Further, the detection axes of the Coriolis force may be only the Y axis and the Z axis (see the column of F). In other words, there is no need to detect the Coriolis force in the X-axis direction. After all, it is sufficient for the vibration mechanism to be able to vibrate in two directions of the X axis and the Y axis, and as the detection mechanism, it is sufficient to be able to detect the directions of the two axes of the Y axis and the Z axis. Each of the various embodiments described above is based on the premise that a vibration mechanism that vibrates in the XYZ three-axis directions and a detection mechanism that detects Coriolis force in the XYZ three-axis directions are provided. However, by properly combining the basic principles in this way, it is possible to detect angular velocities in three axes by a two-axis vibration mechanism and a two-axis detection mechanism.

  In the above embodiments, the three-dimensional angular velocity sensor for detecting the angular velocities of three axes of XYZ is used. However, only the angular velocity of two specific axes among these three axes is detected. If it is sufficient, a two-dimensional angular velocity sensor in which a part of the vibration mechanism or the detection mechanism is further omitted can be used. For example, consider only detection operation 1 and detection operation 2 in the above table. In order to perform these two detection operations, it is sufficient to have a vibration mechanism in the X-axis direction and a detection mechanism in the Y-axis and Z-axis directions. As a result, the angular velocity around the Z-axis and the Y-axis Around angular velocity can be detected. Therefore, a two-dimensional angular velocity sensor can be realized by the one-axis vibration mechanism and the two-axis detection mechanism.

  Alternatively, the following combinations are also possible. Now consider only detection operation 2 and detection operation 3 in the table above. In order to perform these two detection operations, it is sufficient to have a vibration mechanism in the X-axis and Y-axis directions and a detection mechanism in the Z-axis direction. As a result, the angular velocity around the Y-axis and the X-axis Around angular velocity can be detected. Therefore, a two-dimensional angular velocity sensor can be realized by the two-axis vibration mechanism and the one-axis detection mechanism.

  When the vibrators are vibrated in the angular velocity sensor according to the present invention, it is preferable that the vibrators be vibrated at a unique resonance frequency of each vibrator. Each of the transducers 130, 211, 241, 260, 321, 440, 550, and 610 in the above-described embodiment has a unique resonance frequency. By vibrating each of the vibrators at such a unique resonance frequency, a large vibration can be generated with a small supply energy, and the efficiency is extremely improved.

  The multi-axis angular velocity sensor according to the present invention independently and independently detects an angular velocity ωx about the X axis, an angular velocity ωy about the Y axis, and an angular velocity ωz about the Z axis for an object moving in the XYZ three-dimensional coordinate system. be able to. Therefore, it can be mounted on an industrial machine, an industrial robot, an automobile, an aircraft, a ship, or the like, and widely used as a sensor for recognizing a motion state or performing feedback control on the motion. Further, it can also be used for control for correcting camera shake at the time of photographing by the camera.

FIG. 3 is a perspective view showing a basic principle of a conventionally proposed one-dimensional angular velocity sensor using Coriolis force. FIG. 3 is a diagram illustrating angular velocities around respective axes in an XYZ three-dimensional coordinate system to be detected according to the present invention. FIG. 4 is a diagram illustrating a basic principle of detecting an angular velocity ωx around an X axis according to the present invention. FIG. 3 is a diagram illustrating a basic principle of detecting an angular velocity ωy around a Y axis according to the present invention. FIG. 3 is a diagram illustrating a basic principle of detecting an angular velocity ωz about the Z axis according to the present invention. FIG. 2 is a side sectional view showing a structure of the multi-axis angular velocity sensor according to the first embodiment of the present invention. FIG. 7 is a top view of a flexible substrate 110 of the multi-axis angular velocity sensor shown in FIG. FIG. 7 is a bottom view of a fixed substrate 120 of the multi-axis angular velocity sensor shown in FIG. 6. FIG. 7 is a side sectional view showing a state in which a vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6 is displaced in the X-axis direction. FIG. 7 is a side cross-sectional view showing a state where a vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6 is displaced in the −X-axis direction. FIG. 7 is a side sectional view showing a state in which a vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6 is displaced in the Z-axis direction. FIG. 7 is a diagram showing a supply voltage waveform for giving a vibration Ux in the X-axis direction to a vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6. FIG. 7 is a diagram showing a supply voltage waveform for giving a vibration Uy in the Y-axis direction to a vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6. FIG. 7 is a diagram showing a supply voltage waveform for giving a vibration Uz in the Z-axis direction to a vibrator 130 in the multi-axis angular velocity sensor shown in FIG. 6. FIG. 7 is a side cross-sectional view showing a phenomenon in which a Coriolis force Fy is generated based on an angular velocity ωx when a vibration Uz is applied to a vibrator 130 in the multiaxial angular velocity sensor shown in FIG. 6. FIG. 7 is a side sectional view showing a phenomenon in which when a vibration Ux is applied to a vibrator 130, a Coriolis force Fz is generated based on an angular velocity ωy in the multiaxial angular velocity sensor shown in FIG. FIG. 7 is a side cross-sectional view showing a phenomenon in which when a vibration Uy is applied to a vibrator 130, a Coriolis force Fx is generated based on an angular velocity ωz in the multiaxial angular velocity sensor shown in FIG. FIG. 4 is a circuit diagram showing an example of a circuit for detecting a change in the capacitance value of a capacitance element C. 19 is a timing chart illustrating the operation of the circuit illustrated in FIG. FIG. 4 is a circuit diagram illustrating an example of a circuit for detecting a change in capacitance value of a pair of capacitance elements C1 and C2. 21 is a timing chart illustrating the operation of the circuit illustrated in FIG. FIG. 7 is a side sectional view for explaining the principle of a first modification of the multi-axis angular velocity sensor shown in FIG. 6. FIG. 7 is another sectional side view for explaining the principle of a first modification of the multi-axis angular velocity sensor shown in FIG. 6. FIG. 13 is a further side sectional view for explaining the principle of a first modification of the multi-axis angular velocity sensor shown in FIG. 6. FIG. 7 is a side sectional view showing a specific structure of a first modified example of the multi-axis angular velocity sensor shown in FIG. 6. 26 is a diagram illustrating an example of a method of applying a voltage to each electrode of the multi-axis angular velocity sensor illustrated in FIG. 25. FIG. FIG. 13 is a side sectional view showing a specific structure of a second modification of the multi-axis angular velocity sensor shown in FIG. 6. It is a sectional side view showing the structure of the multi-axis angular velocity sensor concerning a 2nd example of the present invention. FIG. 29 is a top view of a flexible substrate 210 of the multi-axis angular velocity sensor shown in FIG. 28. FIG. 29 is a side sectional view showing a cross section at another position of the multi-axis angular velocity sensor shown in FIG. 28. FIG. 29 is a bottom view of a fixed substrate 230 of the multi-axis angular velocity sensor shown in FIG. 28. FIG. 29 is a side sectional view showing a first modification of the multi-axis angular velocity sensor shown in FIG. 28. FIG. 29 is a side sectional view showing a second modification of the multi-axis angular velocity sensor shown in FIG. 28. 34 is a top view of a flexible substrate 250 of the multi-axis angular velocity sensor shown in FIG. It is a sectional side view showing the structure of the multi-axis angular velocity sensor concerning a 3rd example of the present invention. FIG. 36 is a top view of a flexible substrate 310 of the multi-axis angular velocity sensor shown in FIG. 35. FIG. 37 is a diagram showing an arrangement of a resistance element R shown in FIG. 36. FIG. 36 is a side sectional view showing a state where a Coriolis force Fx acts on the multi-axis angular velocity sensor shown in FIG. 35. FIG. 36 is a circuit diagram illustrating an example of a circuit that detects a Coriolis force Fx acting on the multi-axis angular velocity sensor illustrated in FIG. 35 in the X-axis direction. FIG. 36 is a circuit diagram illustrating an example of a circuit that detects a Coriolis force Fy acting on the multi-axis angular velocity sensor illustrated in FIG. 35 in the Y-axis direction. FIG. 36 is a circuit diagram illustrating an example of a circuit that detects a Coriolis force Fz in the Z-axis direction that acts on the multi-axis angular velocity sensor illustrated in FIG. 35. It is a sectional side view showing the structure of the multi-axis angular velocity sensor concerning a 4th example of the present invention. FIG. 43 is a diagram showing polarization characteristics of a piezoelectric element used in the multi-axis angular velocity sensor shown in FIG. 42. FIG. 43 is a side cross-sectional view showing a state where displacement in the X-axis direction is caused in the multi-axis angular velocity sensor shown in FIG. 42. FIG. 43 is a side cross-sectional view showing a state where a displacement in the Z-axis direction is caused in the multi-axis angular velocity sensor shown in FIG. 42. FIG. 43 is a wiring diagram showing wiring for detecting a Coriolis force Fx in the X-axis direction applied to the multi-axis angular velocity sensor shown in FIG. 42. 43 is a wiring diagram showing wiring for detecting a Coriolis force Fy in the Y-axis direction applied to the multi-axis angular velocity sensor shown in FIG. 42. FIG. FIG. 43 is a wiring diagram showing wiring for detecting a Coriolis force Fz in the Z-axis direction applied to the multi-axis angular velocity sensor shown in FIG. 42. FIG. 44 is a diagram illustrating polarization characteristics opposite to the polarization characteristics illustrated in FIG. 43. 43 is a plan view showing a distribution of polarization characteristics of a piezoelectric element used in a first modification of the multi-axis angular velocity sensor shown in FIG. 42. FIG. FIG. 51 is a wiring diagram showing wiring for detecting a Coriolis force Fx in the X-axis direction applied to the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 50. FIG. 51 is a wiring diagram showing wiring for detecting a Coriolis force Fy in the Y-axis direction applied to the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 50. FIG. 51 is a wiring diagram showing wiring for detecting a Coriolis force Fz in the Z-axis direction applied to the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 50. FIG. 43 is a side sectional view showing a structure of a second modification of the multi-axis angular velocity sensor shown in FIG. 42. FIG. 43 is a side sectional view showing the structure of a third modification of the multi-axis angular velocity sensor shown in FIG. 42. FIG. 43 is a side sectional view showing the structure of a fourth modification of the multi-axis angular velocity sensor shown in FIG. 42. It is a top view showing the structure of the multi-axis angular velocity sensor concerning a 5th example of the present invention. FIG. 58 is a side sectional view showing the structure of the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a top view showing the arrangement of the localized elements defined in the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a diagram showing polarization characteristics of a piezoelectric element used in the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a side cross-sectional view showing a state where displacement in the X-axis direction is caused in the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a side cross-sectional view showing a state where a displacement in the Z-axis direction is caused in the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a wiring diagram showing wiring for detecting the Coriolis force Fx acting on the multi-axis angular velocity sensor shown in FIG. 57 in the X-axis direction. FIG. 58 is a wiring diagram showing wiring for detecting the Coriolis force Fy in the Y-axis direction acting on the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a wiring diagram showing wiring for detecting the Coriolis force Fz in the Z-axis direction applied to the multi-axis angular velocity sensor shown in FIG. 57. FIG. 61 is a diagram illustrating polarization characteristics opposite to the polarization characteristics illustrated in FIG. 60. FIG. 58 is a plan view showing a distribution of polarization characteristics of a piezoelectric element used in a first modification of the multi-axis angular velocity sensor shown in FIG. 57. FIG. 67 is a side cross-sectional view showing a state where a Coriolis force Fx in the X-axis direction has acted on the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 68 is a side cross-sectional view showing a state in which a Coriolis force Fz in the Z-axis direction acts on the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 68 is a wiring diagram showing wiring for detecting a Coriolis force Fx in the X-axis direction applied to the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 67 is a wiring diagram showing wiring for detecting a Coriolis force Fy in the Y-axis direction applied to the multi-axis angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 67 is a wiring diagram showing wiring for detecting a Coriolis force Fz in the Z-axis direction applied to the multiaxial angular velocity sensor using the piezoelectric element shown in FIG. 67. FIG. 58 is a side sectional view showing the structure of a second modification of the multi-axis angular velocity sensor shown in FIG. 57. FIG. 58 is a side sectional view showing the structure of a third modification of the multi-axis angular velocity sensor shown in FIG. 57. It is a perspective view showing the basic principle of a multi-axis angular velocity sensor concerning a 6th example of the present invention. FIG. 14 is a side sectional view showing a specific structure of a multi-axis angular velocity sensor according to a sixth embodiment of the present invention. 6 is a flowchart showing a procedure of a detection operation in the multi-axis angular velocity sensor according to the present invention. FIG. 3 is a diagram illustrating a specific circuit configuration example for performing a detection operation in the multi-axis angular velocity sensor according to the present invention. FIG. 7 is a diagram illustrating another basic principle of detecting the angular velocity ωx around the X axis according to the present invention. FIG. 9 is a diagram illustrating another basic principle of detecting the angular velocity ωy around the Y axis according to the present invention. FIG. 9 is a diagram illustrating another basic principle of detecting the angular velocity ωz about the Z axis according to the present invention.

Explanation of reference numerals

Reference Signs List 10 vibrators 11, 12 piezoelectric element 20 object 30 vibrator 110 flexible substrate 120 fixed substrate 130 vibrator 140 sensor housing 151, 152 inverter 153 resistor 154 exclusive OR circuit 161 , 162, inverters 163, 164, resistors 165, exclusive OR circuits 171, 172, dielectric substrate 210, first substrate 211, vibrator 212, bridge 213, support frame 220, second substrate 221, depression 230. ... Third substrate 231 Cutting surface 240 Fourth substrate 241 Vibrator 242 Pedestal 250 Flexible substrate 251 Working part 252 Flexible part 253 Fixed part 260 Vibrator 270 Pedestal 280 Base Substrate 290 Lid substrate 310 First substrate 311 Working part 312 Flexible part 313 Fixed part 320 Second substrate 321 Vibrator 322 Pedestal 330 3 substrate 331 recess 340 fourth substrate 350 power supply 361-363 voltmeter 410 flexible substrate 420 fixed substrate 430 piezoelectric element 440 vibrator 450 sensor housing 460 piezoelectric element 470 piezoelectric Element 480 Flexible substrate 490 Flexible substrate 510 Flexible substrate 520 Piezoelectric element 530 Piezoelectric element 540 Piezoelectric element 550 Vibrator 560 Sensor housing 570 Flexible substrate 610 Vibrator 620 Sensor housing Body 630 Partition plate 640 Diaphragm 650 Connection rod 660 Protective cover 700 Block 710 showing an angular velocity sensor Vibration unit 711 Vibration generation circuit 712 Multiplexer 720 Detection unit 721 Displacement detection circuit 722 Multiplexer 730 Detection Value output circuit 740 Controller a Delay time b Pulse width / delay time C1 to C5 Capacitance Element / capacitance value ΔC, ΔC12, ΔC34... Capacitance difference D1 to D16... Localized element d... Pulse width / delay time d1, d2... Delay time E0, E1 to E5... Upper electrode layers E1a to E5a. F0, F1 to F5: Lower electrode layers F1a to F5a: Auxiliary electrode layers F, Fx, Fy, Fz: Coriolis force f: Period G: Center of gravity G0: Upper electrode layers G1 to G5: Lower electrode layers G6 to G10: Upper electrodes Layers H1 to H4 Openings J1 to J6 Coils L1 to L16 Upper electrode layers M0 and M1 to M16 Lower electrode layers N1 to N4 Node R Piezoresistive elements Rx1 to Rx4 Piezoresistive elements Ry1 to Ry4 Piezoelectric Resistance elements Rz1 to Rz4 Piezoresistive elements SW1 to SW6 Switches T1 to T4, Tx1, Ty1, Tz1, Tx2, Ty2, Tz2 Terminals t1 to t5 Periods U, Ux, Uy, Uz ... vibration V, V1 to V5 ... voltage Vx, Vy, Vz ... bridge voltages W1, W2, X, Y, Z ... coordinate axes α, αx, αy, αz ... acceleration ω, ωx, ωy, ωz ... angular velocity

Claims (2)

An angular velocity sensor for detecting an angular velocity about a Z axis in an XYZ three-dimensional coordinate system,
A first substrate fixed to the sensor housing and having a substrate surface parallel to the XY plane;
A central portion having a substrate surface disposed in parallel with the substrate surface of the first substrate at a predetermined distance, a flexible intermediate portion located outside the central portion, A second substrate, the second substrate comprising a peripheral portion located outside the portion, the peripheral portion being fixed to the first substrate;
With
When an external force is applied to the central portion, the central portion is configured to be displaced with respect to the first substrate by bending the intermediate portion,
A first displacement electrode, a second displacement electrode, a third displacement electrode, and a fourth displacement electrode are formed in the central portion of the second substrate, and the first displacement electrode, the third displacement electrode, and the fourth displacement electrode are formed on the first substrate. , A second fixed electrode, a second fixed electrode, a third fixed electrode, a third fixed electrode, A fourth fixed electrode is formed, a first capacitive element is formed by the first fixed electrode and the first displacement electrode, and a fourth capacitor is formed by the second fixed electrode and the second displacement electrode. A second capacitance element is formed, a third capacitance element is formed by the third fixed electrode and the third displacement electrode, and a fourth capacitance element is formed by the fourth fixed electrode and the fourth displacement electrode. Of the capacitive element is formed,
The first capacitive element and the second capacitive element are arranged at positions such that when the center portion is displaced in the X-axis direction, the interval between one electrode increases and the interval between the other electrodes decreases. The third capacitive element and the fourth capacitive element are configured such that, when the center portion is displaced in the Y-axis direction, the interval between one electrode increases and the interval between the other electrodes decreases. Are located in
By supplying AC signals having different phases to each other between a pair of electrodes constituting the third capacitive element and between a pair of electrodes constituting the fourth capacitive element, a Coulomb force is caused to act. Means for vibrating the central portion in the Y-axis direction;
Means for outputting a value indicating an angular velocity about the Z axis based on a difference between the capacitance value of the first capacitance element and the capacitance value of the second capacitance element;
An angular velocity sensor, further comprising: The angular velocity sensor according to claim 1,
The first capacitive element is arranged on a positive area on the X axis, the second capacitive element is arranged on a negative area on the X axis, and the third capacitive element is arranged on a positive area on the Y axis. An angular velocity sensor, wherein the fourth capacitive element is arranged on a negative region of the Y-axis.

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