JPH10227644A - Angular velocity sensor using vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a signal processing for detecting an angular velocity. SOLUTION: A flexible displacement substrate 110 and a stiff, fixed substrate 120 are supported by a device enclosure 140 while they oppose each other. A vibrator 130 is sealed to the displacement substrate 110. An AC drive signal is fed between electrodes E15 and E25 and Coulomb's force is utilized, thus vibrating the vibrator 130 up and down. A capacitor element C1 is constituted of electrodes E11 and E21 and a capacitor element C2 is constituted of electrodes E12 and E22, periodical signals with different phases are given to a CR delay circuit using the capacitor element C1 and a CR delay circuit using the capacitor element C2, and the phase difference between both periodical signals after delay is detected. When an angular velocity ωy is operated, a displacement substrate 110 is inclined due to Coriolis force +Fx, and a difference is generated in the delay time of both delay circuits, thus changing a phase difference. An angular velocity ωy is detected according to the changing form of the phase difference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an angular velocity sensor using a vibrator, and more particularly to an angular velocity sensor for detecting a Coriolis force acting on a vibrator based on a change in capacitance of a capacitive element.

[0002]

2. Description of the Related Art In the automobile industry, the machine industry, and the like, there is an increasing demand for a sensor capable of accurately detecting the acceleration and angular velocity of a moving object. 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.

[0003] As a sensor for detecting the angular velocity,
An angular velocity sensor using a vibrator has attracted attention. The basic principle of the angular velocity sensor using this vibrator is to detect the Coriolis force acting on the second axis in a state where the vibrator is vibrated in the first axial direction with respect to three axes orthogonal to each other. , The angular velocity about the third axis. This utilizes a physical phenomenon in which when an angular velocity around a third axis acts on an object moving in a first direction, a Coriolis force acts in a second axis direction. By detecting the Coriolis force in the second axial direction, the angular velocity around the third axis can be obtained indirectly.

As an angular velocity sensor based on such a principle, for example, International Publication No. WO9 based on the Patent Cooperation Treaty
Japanese Patent Application Laid-Open No. 4/23272 discloses a multi-axis angular velocity sensor capable of detecting an angular velocity around two axes or three axes by detecting Coriolis force based on a change in capacitance of a capacitive element. . This sensor has a structure in which when the Coriolis force acts, a change occurs in the electrode spacing of the capacitive element. By monitoring the change in the capacitance of the capacitive element, it is possible to detect the applied angular velocity. Become.

[0005]

The above-mentioned angular velocity sensor, which detects the Coriolis force acting on the vibrator by using a capacitance element, is mass-produced because the mechanical structure of the main body is relatively simple. It is suitable for commercial use and is expected to be used at low cost for commercial use. However, the simplification of the signal processing circuit portion is insufficient compared with the structure of the main body portion, which prevents cost reduction in practical use. That is, in this type of angular velocity sensor, signal processing for extracting a change in the capacitance of the capacitive element as some kind of electric signal is indispensable. Although some analog circuits for performing such signal processing have been proposed, However, the circuit configuration must be quite complicated.

[0006] Further, in the present day when the control technology using digital signals is generalized, the use form of digital signals is becoming mainstream even when the signals from the angular velocity sensor are used. It is desired to realize a simple signal processing circuit suitable for use.

Accordingly, an object of the present invention is to provide an angular velocity sensor using a vibrator having a simple and efficient signal processing circuit.

[0008]

Means for Solving the Problems (1) In a first aspect of the present invention, a vibrator vibrating in a first axial direction is moved in a second axial direction orthogonal to the first axis. In an angular velocity sensor for detecting an acting Coriolis force to determine an angular velocity about a third axis orthogonal to both the first axis and the second axis, some or all of the elements constituting the sensor are accommodated. The device housing and the vibrator accommodated in the device housing are oscillated in a first axial direction and tilted by the action of a Coriolis force in the second axial direction. Supporting means for supporting the vibrator with a predetermined degree of freedom with respect to the device housing, driving means for vibrating the vibrator in the first axial direction at a predetermined cycle φ, and a displacement electrode formed on the vibrator side. A fixed electrode formed on the device housing side, and a positive direction of the second axis. When the Coriolis force directed to the electrode acts, the electrode interval decreases due to the inclination of the vibrator, and when the Coriolis force directed to the negative direction of the second axis acts, the electrode interval increases due to the inclination of the vibrator. It has a first capacitive element arranged, a displacement electrode formed on the vibrator side, and a fixed electrode formed on the device housing side, and a Coriolis force directed in the positive direction of the second axis acts. In this case, the second capacitor is arranged such that the electrode interval becomes large due to the inclination of the vibrator, and the electrode interval becomes small due to the inclination of the vibrator when the Coriolis force in the negative direction of the second axis acts. An element, a first delay circuit combining a first capacitance element and a resistance element, a second delay circuit combining a second capacitance element and a resistance element,
A first signal supply circuit for generating a first periodic signal having a period φ and supplying the first periodic signal to a first delay circuit; A second signal supply circuit for generating a second periodic signal having a phase difference p of the following, and providing the second periodic signal to a second delay circuit;
A first delay signal output from the first delay circuit;
A phase difference detection circuit that generates a phase difference signal indicating a phase difference between the second delay signal output from the delay circuit and an odd-numbered period And an angular velocity detection circuit for detecting an angular velocity about the third axis based on at least one of the phase difference shown in (1) and the phase difference shown in the even-numbered period.

(2) The second aspect of the present invention is the above-mentioned first aspect.
In the angular velocity sensor using the vibrator according to the aspect, instead of using a variable capacitance element having a displacement electrode formed on the vibrator side and a fixed electrode formed on the device housing side as the second capacitance element, Further, a fixed capacitance element having a predetermined fixed capacitance is used.

(3) A third aspect of the present invention is the above-mentioned first aspect.
Alternatively, in the angular velocity sensor using the vibrator according to the second aspect, the angular velocity detection circuit detects the angular velocity based on a difference between the phase difference shown in the odd-numbered period and the phase difference shown in the even-numbered period. This is to detect.

(4) The fourth aspect of the present invention is the above-mentioned first aspect.
Alternatively, in the angular velocity sensor using the vibrator according to the second aspect, the phase difference detection circuit detects the phase difference using a first logic element that obtains an exclusive OR of the first delay signal and the second delay signal. And a third signal supply circuit for causing the angular velocity detection circuit to generate a third periodic signal having a period φ so that the phase difference is indicated by the pulse width of the phase difference signal output from the first logic element. And a second logic element for obtaining a logical product of the third periodic signal and the phase difference signal, wherein the second logic element generates an odd-numbered pulse and an even-numbered pulse of the phase difference signal. And the angular velocity is detected based on at least one of the pulse width of the odd-numbered pulse and the pulse width of the even-numbered pulse.

(5) The fifth aspect of the present invention is the above-mentioned first aspect.
Alternatively, in the angular velocity sensor using the vibrator according to the second aspect, the phase difference detection circuit detects the phase difference using a first logic element that obtains an exclusive OR of the first delay signal and the second delay signal. And a third signal supply circuit for causing the angular velocity detection circuit to generate a third periodic signal having a period φ so that the phase difference is indicated by the pulse width of the phase difference signal output from the first logic element. A fourth signal supply circuit for generating a fourth periodic signal in a logically inverted state with respect to the third periodic signal, and a second signal for obtaining a logical product of the third periodic signal and the phase difference signal A logic element, a third logic element that generates an inverted phase difference signal that is in a logic inversion state with respect to the phase difference signal, and a fourth logic element that obtains a logical product of the fourth periodic signal and the inverted phase difference signal And the output signal of the second logic element and the fourth
And a fifth logic element for calculating a logical sum with the output signal of the logic element of (a), wherein the angular velocity is detected based on the pulse width of the output signal of the fifth logic element.

(6) The sixth aspect of the present invention is the above-mentioned first aspect.
In the angular velocity sensor using the vibrator according to the fifth to fifth aspects, the angular velocity detection circuit defines a phase difference in a state where no Coriolis force is acting as a reference value, and the actually detected phase difference is larger than the reference value. If the difference is larger, the difference is output as the angular velocity in the first rotation direction. If the actually detected phase difference is smaller than the reference value, the difference is converted to the second rotation opposite to the first rotation direction. Are output as angular velocities with respect to the rotation direction.

(7) A seventh aspect of the present invention is the above-mentioned first aspect.
In the angular velocity sensor using the vibrator according to any one of the sixth to sixth aspects, the driving means includes a driving capacitive element including a displacement electrode formed on the vibrator side and a fixed electrode formed on the device housing side; And a drive signal supply circuit for supplying an AC drive signal having a period φ to the capacitive element for use, wherein the vibrator is vibrated by Coulomb force acting in the capacitive element for drive.

(8) The eighth aspect of the present invention is the above-mentioned first aspect.
In the angular velocity sensor using the vibrator according to the sixth to sixth aspects, at least a part of the vibrator is formed of a magnetic material, and a driving unit includes a magnetic field generating unit configured to generate a magnetic field acting on the magnetic material portion of the vibrator. A driving signal supply circuit that supplies an alternating current signal having a period φ to the magnetic field generating unit, and a vibrator is oscillated by generating a periodic magnetic field based on the alternating current signal in the magnetic field generating unit. .

(9) The ninth aspect of the present invention is the above-mentioned first aspect.
In the angular velocity sensor using the vibrator according to the aspect, the supporting means is constituted by a flexible displacement substrate partially fixed to the device housing and partially fixed to the vibrator, and the displacement substrate A fixed substrate is provided on the device housing so as to face the device housing, and a displacement element formed on the displacement substrate and a fixed electrode formed on the fixed substrate constitute a capacitive element.

(10) A tenth aspect of the present invention relates to an angular velocity sensor using the vibrator according to the ninth aspect described above.
A plane perpendicular to the displacement substrate and including the center of gravity of the vibrator and the third axial direction is defined, a first capacitive element is formed on a first side with respect to this plane, and a plane is defined with respect to this plane. The second capacitance element is formed on a second side opposite to the first side.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

§1. Basic Structure of Sensor Body FIG. 1 is a side sectional view showing a basic structure of a sensor body of an angular velocity sensor according to one embodiment of the present invention. The angular velocity sensor requires a signal processing circuit in addition to the sensor main body shown in FIG. 1, and the configuration of the signal processing circuit will be described later.

As shown in FIG. 1, the displacement substrate 110 and the fixed substrate 120 are arranged so as to face each other at a predetermined distance from each other, and the lower surface of the displacement substrate 110 has a vibration having a predetermined mass. The child 130 is fixed. In the example shown here, each of the displacement substrate 110 and the fixed substrate 120 is a disk-shaped substrate, and its peripheral portion is the device housing 1.
It is fixed by 40. In this embodiment, the vibrator 130 fixed to the lower surface of the displacement substrate 110 is
It is a cylindrical weight. On the other hand, the device housing 140 is a cylindrical structure, and the outer peripheral portion of the displacement substrate 110 and the outer peripheral portion of the fixed substrate 120 are fixed to the inner peripheral portion of the device housing 140.

Here, for convenience of explanation, an origin O is defined at the position of the center of gravity G of the vibrator 130 in the stationary state, the X axis is located on the right side of the figure, the Y axis is perpendicular to the plane of the drawing, and the Z axis is located on the top of the figure. Consider an XYZ three-dimensional coordinate system with axes. Displacement board 1
Reference numeral 10 denotes a substrate having flexibility and functioning as a so-called diaphragm. The vibrator 130 can be vibrated in the Z-axis direction by applying an external force. On the other hand, the fixed substrate 120 has rigidity and does not substantially bend even when an external force acts. Both the displacement substrate 110 and the fixed substrate 120 are supported so as to be parallel to the XY plane, and when no external force is applied, the two substrates are parallel to each other.

As shown in the top view of FIG. 2, five electrodes E11 to E15 are formed on the upper surface of the displacement substrate 110. Each of the electrodes E11 and E12 has the same shape that is line-symmetric with respect to the X axis, and both are disposed at positions that are line-symmetric with respect to the Y axis. On the other hand, the electrode E1
Each of E3 and E14 has the same shape that is line-symmetric with respect to the Y axis, and both are arranged at positions that are line-symmetric with respect to the X axis. The electrode E15 is a disk-shaped electrode whose center is located on the Z axis. These five electrodes E11
Electrodes E15 are displaced together with the displacement substrate 110, and are hereinafter referred to as displacement electrodes.

On the other hand, on the lower surface of the fixed substrate 120, as shown in the bottom view of FIG.
5 are formed. Since these electrodes are electrodes fixed on the fixed substrate 120 side, they are hereinafter referred to as fixed electrodes.
The five fixed electrodes E21 to E25 are electrodes having the same shape as the five displacement electrodes E11 to E25, respectively, and are arranged at mirror image positions with respect to the respective displacement electrodes. Therefore, the displacement electrodes E11 to E15 and the opposing fixed electrodes E21 to E25 form five sets of capacitive elements. Here, the capacitive element including the electrode pair E11 and E21 is referred to as a first capacitive element C1, and the electrode pair E1
The capacitance element composed of the pair of electrodes E14 and E24 is referred to as a third capacitance element C3, and the capacitance element composed of the pair of electrodes E14 and E24 is referred to as a fourth capacitance element. Called element C4, electrode pair E15, E2
5 is referred to as a fifth capacitor C5.

§2. Detecting principle of angular velocity The angular velocity sensor according to the embodiment described here has an angular velocity ωx around the X axis and an angular velocity ω around the Y axis which act on the entire device.
This is a two-axis angular velocity sensor that can simultaneously detect y and y. For example, in a state where the vibrator 130 is vibrated in the Z-axis direction, when an angular velocity ωy about the Y-axis acts on the device housing 140, the Coriolis force Fx in the X-axis direction
(If the mass of the vibrator 130 is m and the speed is Vz, the acting Coriolis force Fx is Fx = 2 · m · Vz
-Ωy). Therefore, if the Coriolis force Fx can be detected, the angular velocity ωy about the Y axis can be obtained indirectly. The first capacitive element C1 and the second capacitive element C2 arranged on the X axis have a function of detecting the Coriolis force Fx in the X axis direction. Where YZ
Considering a plane (a plane perpendicular to the displacement substrate 110 and including the center of gravity G of the vibrator 130 and the Y axis), the first capacitive element C1 is located on the first side of the YZ plane, The second capacitive element C2 is located on the second side of the YZ plane. As described above, in order to efficiently detect the Coriolis force Fx in the X-axis direction, it is preferable to use a pair of capacitive elements C1 and C2 disposed on opposite sides of the YZ plane and at symmetrical positions.

When the angular velocity ωx about the X axis acts on the device housing 140 in a state where the oscillator 130 is vibrated in the Z axis direction, a Coriolis force Fy acts in the Y axis direction. Therefore, if the Coriolis force Fy can be detected, the angular velocity ωx about the X axis can be obtained indirectly. The third capacitive element C3 and the fourth capacitive element C4 arranged on the Y axis have a function of detecting the Coriolis force Fy in the Y axis direction. Here, considering the XZ plane (a plane perpendicular to the displacement substrate 110 and including the center of gravity G of the vibrator 130 and the X axis), the third capacitive element C
3 is located on the first side of the XZ plane, and the fourth capacitive element C4 is located on the second side of the XZ plane. As described above, in order to efficiently detect the Coriolis force Fy in the Y-axis direction, it is preferable to use a pair of capacitive elements C3 and C4 disposed on opposite sides of the XZ plane and at symmetrical positions.

As described above, each of the capacitance elements C1 to C4 is a detection capacitance element used for detecting Coriolis force, whereas the fifth capacitance element C5 vibrates the vibrator 130 in the Z-axis direction. This is a driving capacitive element used for driving. Here, using this driving capacitive element C5,
The principle of vibrating the vibrator 130 will be described. Now, let us consider a case where a positive charge is supplied to the displacement electrode E15 and a negative charge is supplied to the fixed electrode E25 as shown in the side sectional view of FIG. 4 (the polarities of the charges may be reversed). When different charges are supplied to the pair of electrodes facing each other, Coulomb force acts between the two electrodes, and an attractive force acts between the two electrodes. Here, since the fixed substrate 120 is a rigid substrate, while the displacement substrate 110 is a flexible substrate, the displacement substrate 110 is moved by this Coulomb attraction as shown in FIG. 110 is bent (elastic deformation), and the displacement electrode E15 approaches the fixed electrode E25. In other words, the vibrator 130 moves with the velocity + Vz in the positive direction of the Z axis.

As described above, if the supply of charges to the displacement electrode E15 and the fixed electrode E25 is stopped while the oscillator 130 is moving in the positive direction of the Z axis, the Coulomb attraction disappears. Then, the vibrator 130 moves in the negative direction of the Z-axis at a speed -Vz due to the restoring force of the displacement substrate 110 against the elastic deformation. At this time, the center of gravity G of the transducer 130
Is the position of the original origin O (the position in the stationary state shown in FIG. 1)
And will continue to move further downward as shown in the side sectional view of FIG.

Therefore, as shown in FIG. 6, if an AC drive signal U having a period φ is supplied between the displacement electrode E15 and the fixed electrode E25, the vibrator 130 vibrates in the Z-axis direction with a period φ. Will be. In practice, for example, the fixed electrode E25 may be grounded, and an AC drive signal U as shown in FIG. 6 may be supplied to the displacement electrode E15. However, the period during which energy is supplied by the AC drive signal U is only the first half period t1 of the cycle φ, and no energy is supplied during the second half period t2.
The vibration of the vibrator 130 does not become a simple vibration centered on the origin O (the position of the center of gravity G in a stationary state). That is, the movement in the positive direction of the Z axis is a movement obtained by positively sucking in the positive direction of the Z axis by Coulomb force, whereas the movement in the negative direction of the Z axis is positive in the negative direction of the Z axis. The movement is not a movement obtained by the specific suction, but a movement based on the restoring force of the displacement substrate 110. Therefore, when the position of the origin O is used as a reference, the amplitude in the positive direction of the Z-axis and the amplitude in the negative direction of the Z-axis are not necessarily equivalent. However, although the center position moves slightly above the origin O, the up-and-down movement of the vibrator 130 becomes almost a single vibration, and there is no problem in practical use. Of course, if a mechanism for applying a Coulomb force in the negative direction of the Z-axis is added in the latter half period t2 of the cycle φ, it is possible to cause a simple vibration centered on the origin O, but the structure is more It has to be complicated.

After all, by supplying such an AC driving signal U to the driving capacitive element C5, the vibrator 130
With the velocity Vz as shown in FIG. 6, the robot moves in both the positive and negative directions of the Z axis at a period φ (actually, the velocity Vz
Is expected to be a gentle waveform close to a sine wave instead of a sawtooth wave as shown in the figure, but here, for convenience of explanation, a simple waveform as shown is shown). The time point when the velocity Vz = 0 corresponds to the time point when the transducer 130 reaches the maximum amplitude position (the highest point or the lowest point). Period P in FIG.
Indicates that the first period P1 in which the speed Vz takes a positive value and the second period P2 in which the speed Vz takes a negative value alternately appear, and each of the periods P1 and P2 is half of the period φ. It will be a long period. In other words, the first period P1 is a period in which the vibrator 130 is moving upward in the figure, as shown in FIG. 4, and the second period P2 is, as shown in FIG. This is a period during which the oscillator 130 is moving downward in the figure.

Thus, as long as the vibrator 130 is vibrating along the Z axis, the displacement substrate 110 and the fixed substrate 12
A relationship parallel to 0 is maintained. That is, in the state shown in FIG. 4, the distance between the two substrates is small, and in the state shown in FIG. 5, the distance between the two substrates is large, but the relationship that the two substrates are parallel is maintained. However, when the angular velocity ωy around the Y axis is acting, a Coriolis force is generated in the X axis direction, so that the parallel state of the two substrates cannot be maintained. For example, as shown in the side sectional view of FIG. 7, when the angular velocity ωy about the Y axis is acting on the device housing 140, the vibrator 130 is driven at the speed + Vz
Moves upward in the figure, the Coriolis force in the positive X-axis direction + F
x will occur. When such Coriolis force + Fx acts on the vibrator 130, the displacement substrate 110
Is caused as shown in the figure, and the vibrator 130 is inclined as shown in the figure. As a result, the distance between the pair of electrodes E11 and E12 constituting the first capacitive element C1 is smaller than that in the normal state (the state where the angular velocity is not acting), and conversely, the second capacitive element C2 The electrode interval between the pair of electrodes E12 and E22 constituting the above becomes large. In other words, due to the action of the angular velocity ωy, the capacitance value of the first capacitance element C1 increases and the capacitance value of the second capacitance element C2 decreases.

However, as shown in the side sectional view of FIG.
When the vibrator 130 moves downward at the speed -Vz in the figure, the direction of the Coriolis force acting is also reversed because the direction of movement is reversed, and a Coriolis force -Fx in the negative X-axis direction is generated. . When such Coriolis force -Fx acts on the vibrator 130, the displacement substrate 110 bends as shown in FIG. 8, and the vibrator 130 is inclined in a direction opposite to that of FIG. . As a result, the distance between the pair of electrodes E11 and E12 constituting the first capacitive element C1 is larger than that in the normal state (the state where the angular velocity is not acting), and conversely, the second capacitive element C2 The electrode interval between the pair of electrodes E12 and E22 constituting the above becomes smaller.
In other words, the capacitance value of the first capacitance element C1 decreases and the capacitance value of the second capacitance element C2 increases due to the action of the angular velocity ωy.

It should be noted here that in the above discussion, the expression that the capacitance value of each capacitance element is “increased” or “decreased” is used only in a normal state where the angular velocity ωy does not act. And the state when the angular velocity ωy acts. That is, the vibrator 130
In the state where is vibrated, the electrode spacing of each capacitive element narrows or widens in a cycle φ, and changes periodically, even if no angular velocity acts. For example, as shown in FIG. 4, when the vibrator 130 moves upward in the drawing, the electrode spacing of each capacitance element becomes narrow,
While the capacitance value increases, as shown in FIG.
When the vibrator 130 moves downward in the drawing, the distance between the electrodes of each capacitance element increases, and the capacitance value decreases.
Thus, the capacitance value of each capacitance element is constantly changing in the period φ.

After all, the change in the capacitance value of each capacitance element includes an element caused by the vibration of the vibrator 130 and an element caused by the action of the angular velocity. In the angular velocity sensor according to the present invention, by employing the signal processing circuit described in §3 below, it is possible to extract only the elements resulting from the action of the angular velocity.

§3. Signal processing for detecting angular velocity
Circuit 9 is a circuit diagram showing a part of a signal processing circuit used in an angular velocity sensor according to the present invention. In this circuit diagram, the variable capacitance elements C1 and C2 correspond to the first capacitance element C1 and the second capacitance element C2 in the above-described sensor main body, respectively. Actually, in this example, the ground electrode of the capacitive element C1 in FIG. 9 is the fixed electrode E21, and the electrode connected to the resistive element R1 is the displacement electrode E11. Similarly,
The electrode on the ground side of the capacitance element C2 in FIG. 9 is the fixed electrode E22, and the electrode connected to the resistance element R2 is the displacement electrode E2.
Twelve. Here, the capacitance element C1 and the resistance element R1
Constitutes a first delay circuit, and the capacitor C2 and the resistor R2 constitute a second delay circuit.
The resistance value of the resistance element R1 is equal to the resistance value of the resistance element R2.

Here, when a first periodic signal φ1 having a period φ is applied to the input terminal T1 in the figure, the first delay circuit (R
, C1) outputs a first delay signal D1, and when a second periodic signal φ2 having a period φ is applied to an input terminal T2 in the figure, the second delay circuit (R2, C2) outputs a second delayed signal D2. 2 will be output. The pair of delay signals D1 and D2 are used as logic elements L for performing an exclusive OR operation.
1, and a phase difference signal A indicating the phase difference between the two delayed signals D1 and D2 is obtained at an output terminal T3.

Now, with respect to the circuit shown in FIG.
Consider a case where a first periodic signal φ1 and a second periodic signal φ2 as shown in FIG. Here, the first periodic signal φ1 is a rectangular wave signal having a period φ and a duty ratio of 50%. Also, the second periodic signal φ2 has a period φ
Is a rectangular wave signal having a duty ratio of 50% and having a predetermined moving difference p with respect to the first periodic signal φ1. Here, the phase difference p = π / 2 (1/3 of the period φ)
4) is set.

The first delay signal D1 and the second delay signal D2 are signals obtained by delaying the first periodic signal φ1 and the second periodic signal φ2, respectively, so that the delay times are d1 and d2, respectively. Then, a signal as shown in FIG. 10 is obtained. Actually, the waveform of the delay signal that has passed through the CR delay circuit will be rounded. However, in the waveform diagram of the present application, each signal is shown in a rounded state for convenience of explanation.

First, consider the operation of this signal processing circuit in a normal state where no angular velocity is applied. Now, when the vibrator 130 is vibrated at a period φ in the Z-axis direction, the distance between the pair of electrodes constituting the capacitance elements C1 and C2 becomes larger or smaller, so that the capacitance of the capacitance elements C1 and C2 The value will change with the period φ. However, as described above, in a state where the angular velocity is not acting, the vibrator 130 vibrates without tilting, so that the capacitance value of the capacitance element C1 and the capacitance value of the capacitance element C2 are different. Even at the moment, they are equal to each other. Therefore, the delay time d1 by the first delay circuit (R1, C1) in the circuit diagram shown in FIG. 9 is equal to the delay time d2 by the second delay circuit (R2, C2). Therefore, between the first delay signal D1 and the second delay signal D2, the phase difference p between the first periodic signal φ1 and the second periodic signal φ2 (p = π / 2 in this example) ) Is maintained as it is, and as the phase difference signal A, a pulse signal having a pulse width corresponding to the period t10 or the period t20 is obtained as shown in FIG. Here, the period t10
= T20, which is a period corresponding to the phase difference p.

The period t10 of the phase difference signal A in the timing chart of FIG. 10 indicates the period of the odd-numbered pulse, and the period t20 indicates the period of the even-numbered pulse (here, for convenience, the first period is the first period). Starting from the first rising edge portion of the periodic signal φ1, the pulse appearing first thereafter is counted as the odd-numbered pulse). Thus, in the state where the angular velocity is not acting,
t10 = t20. Here, this pulse width is referred to as a reference width. However, the angular velocity ωy about the Y axis
Under the environment in which is applied, the pulse width of the pulse included in the phase difference signal A deviates from this reference width. In other words, the phase difference between the first delay signal D1 and the second delay signal D2 changes due to the action of the angular velocity ωy. The reason is that considering the detection principle described in §2,
Easy to understand. That is, when the angular velocity ωy acts, as shown in FIG. 7 or FIG. 8, the vibrator 130 is inclined, so that the capacitance value of the capacitive element C1 and the capacitive element C2
And a difference between the delay time d1 of the first delay circuit (R1, C1) and the delay time d2 of the second delay circuit (R2, C2). This is because it occurs.

Here, the operation of this signal processing circuit in an environment where the angular velocity ωy is acting will be described with reference to a timing chart shown in FIG. As described above, when the AC drive signal U having the cycle φ is supplied to the driving capacitive element C5, the vibrator 130 vibrates in the Z-axis direction at the Z-axis speed Vz. At this time, as shown as a period P in FIG. 11, a first period P1 in which the speed Vz takes a positive value and a second period P1 in which the speed Vz takes a negative value
2 alternately appear, but in the first period P1, the oscillator 130 tilts as shown in FIG. 7, and in the second period P2, the oscillator 130 tilts as shown in FIG. . As described above, when the first periodic signal φ1 and the second periodic signal φ2 are supplied to the circuit shown in FIG. 9 in a state where the oscillator 130 is vibrated, the first delay signal D1 and the second delayed signal D1 shown in FIG. The second delay signal D2 is obtained.

Here, the first delay signal D1 shown in FIG.
10 is longer than the delay time d1 shown in FIG. 10, and conversely, the delay time d12 of the falling edge is shorter than the delay time d1 shown in FIG. This is because the delay time d11 is the first period P1
This is because the delay time d12 is the delay time obtained in the second period P2.
That is, in the first period P1, the vibrator 130 is inclined as shown in FIG. 7, so that the capacitance value of the capacitive element C1 is in a state where the vibrator 130 is not inclined (that is, a state where the angular velocity is not acting). And the delay time d11
Is greater than d1. Conversely, in the second period P2,
As shown in FIG. 8, since the vibrator 130 is tilted, the capacitance value of the capacitive element C1 is smaller than the state where the vibrator 130 is not tilted (that is, the state where the angular velocity is not acting), and the delay time d12 is It becomes smaller than d1.

On the other hand, the delay time d21 of the rising edge of the second delay signal D2 shown in FIG. 11 is smaller than the delay time d2 shown in FIG. 10, and conversely, the delay time d22 of the falling edge is Is longer than the delay time d2 shown in FIG. This is because the delay time d21 is a delay time obtained in the first period P1, whereas the delay time d22 is a delay time obtained in the second period P2. That is, in the first period P1, the vibrator 130 is inclined as shown in FIG. 7, so that the capacitance value of the capacitive element C2 is in a state where the vibrator 130 is not inclined (that is, a state where the angular velocity is not acting). The delay time d21 is smaller than d2. Conversely, in the second period P2, since the vibrator 130 is inclined as shown in FIG. 8, the capacitance value of the capacitive element C2 is in a state where the vibrator 130 is not inclined (that is, a state where the angular velocity is not acting). , And the delay time d22 becomes larger than d2.

As described above, when the delay time of the two-period signal changes due to the action of the angular velocity ωy, the phase difference signal A has a pulse width corresponding to the period t11 or the period t21 as shown in FIG. It becomes a pulse signal with a pulse.
Here, the pulse indicated by the dashed line indicates a pulse having the same pulse width as the period t10 = t20 shown in FIG. 10, that is, a pulse having a standard width. In the timing chart of FIG. 11, the period t11 of the phase difference signal A indicates the period of the odd-numbered pulse, and the period t21 indicates the period of the even-numbered pulse. Thus, it should be noted that in the signal processing circuit according to the present invention, the odd-numbered pulse and the even-numbered pulse behave differently. That is, in this example, the pulse width of each of the odd-numbered pulses is smaller than the reference width, whereas the pulse width of each of the even-numbered pulses is larger than the reference width.

Here, the difference between the actual pulse width and the reference width corresponds to the magnitude of the applied angular velocity ωy. In other words, if a large angular velocity acts, a large Coriolis force acts and the vibrator 130 tilts greatly, so that the capacitance value changes greatly and the delay time also changes greatly. The direction of the acting angular velocity ωy (clockwise or counterclockwise) is a factor for determining whether the actual pulse width is larger or smaller than the reference width. That is, in the example of FIG. 7 or FIG. 8, the case where the angular velocity ωy indicated by the left-handed arrow acts in the figures is shown. In the application, the left-handed angular velocity in the figure is positive,
The clockwise angular velocity is defined as negative for convenience), the direction of the Coriolis force is reversed, and a phenomenon opposite to the phenomenon described so far occurs. As a result, contrary to the phase difference signal A shown in FIG. 11, the pulse width of the odd-numbered pulse is larger than the reference width, and the pulse width of the even-numbered pulse is smaller than the reference width.

As described above, the pulse width of one pulse included in the phase difference signal A is measured, and based on the phase relationship with the AC drive signal φ, this one pulse is an odd-numbered pulse or an even-numbered pulse. By identifying the above and comparing the measured pulse width with the reference width, the direction and magnitude of the instantaneous angular velocity ωy can be recognized. Therefore, if the pulse width of the pulse obtained in time series is measured one after another,
The value of the angular velocity can be obtained continuously. Further, if the integrated value of the pulse width is obtained, an average angular velocity value within a certain period can be obtained.

However, since the odd-numbered pulses and the even-numbered pulses included in the phase difference signal A behave differently from each other, they must be treated separately. For example, when obtaining an integrated value, a correct result cannot be obtained if the pulse widths of all the pulses are integrated as they are. That is, when the pulse widths of all the pulses of the phase difference signal A shown in FIG. 11 are integrated, odd-numbered pulses having a pulse width smaller than the reference width and even-numbered pulses having a pulse width larger than the reference width are obtained. Will be offset. Therefore, the phase difference signal A is divided into periods of every cycle φ / 2, and an odd-numbered period in which an odd-numbered pulse exists and an even-numbered period in which an even-numbered pulse exists are defined. And the pulse width for the even-numbered pulse may be obtained separately and independently.

For example, as shown in FIG. 11, a third periodic signal φ3 is prepared. The third periodic signal φ3 is a rectangular wave signal having a period φ and a duty ratio of 50%, and is provided with an odd-numbered pulse of the phase difference signal A (a period t11) in a high-level section hatched in the drawing. (Pulse having a pulse width). For example, a phase difference signal A is experimentally obtained using a trial sensor body and a trial circuit, and the center position of an odd-numbered pulse included in the phase difference signal A is determined by a third periodic signal. The phase difference may be adjusted so as to coincide with the center position of the high-level section of φ3. And
If a signal corresponding to the logical product of the third periodic signal φ3 and the phase difference signal A is obtained, this signal includes only the odd-numbered pulses, so that the pulse width of the odd-numbered pulses is obtained. Only one can be selectively extracted.
Conversely, as shown in FIG. 11, a fourth periodic signal φ3 ^*, which is in a logically inverted state with respect to the third periodic signal φ3, is prepared.
If a signal corresponding to the logical product of the fourth periodic signal φ3 ^* and the phase difference signal A is obtained, this signal includes only the even-numbered pulses. Only the width can be selectively extracted.

In order to integrate the pulse width, for example, a method may be employed in which a signal including one of the selectively extracted pulses is applied to a smoothing capacitor for smoothing, and an integrated value is obtained as an analog voltage value. Can, or
It is also possible to adopt a method in which the pulse width is counted by a counter that operates with a sufficiently short cycle with respect to the cycle φ, and an integrated value is obtained as a digital count value.

Both the pulse width of the odd-numbered pulse and the pulse width of the even-numbered pulse thus obtained have information on the direction and magnitude of the angular velocity ωy. In other words, the former corresponds to the period t11 of the phase difference signal A shown in FIG. 11, so that if it is smaller than the standard width, it indicates the action of the counterclockwise angular velocity ωy. Angular velocity -ωy
Will be shown. Conversely, the latter corresponds to the period t21 of the phase difference signal A shown in FIG.
If it is larger than the standard width, the effect of the counterclockwise angular velocity ωy is shown. If it is smaller than the standard width, the clockwise angular velocity −
The effect of ωy will be shown. In both cases,
The difference between the standard width and the actual pulse width will indicate the magnitude of the applied angular velocity.

Thus, both the pulse width of the odd-numbered pulse and the pulse width of the even-numbered pulse are:
Since each of them has information on the direction and the magnitude of the angular velocity ωy, the angular velocity can be detected using only one of them in principle. However, to obtain a highly accurate detection value, it is preferable to use both pulse widths. For this purpose, the difference between the pulse width of the odd-numbered pulse and the pulse width of the even-numbered pulse may be calculated. When the same angular velocity is applied, the odd-numbered pulse and the even-numbered pulse have complementary behaviors in which one pulse width increases and the other pulse width decreases. , Both of which can be detected. A more practical signal processing circuit capable of performing detection using both the odd-numbered pulse and the even-numbered pulse will be described below.

§4. Practical for detecting angular velocity
Signal Processing Circuit FIG. 12 is a circuit diagram showing a practical signal processing circuit used for the angular velocity sensor according to the present invention. This signal processing circuit includes a detection circuit 71 and a drive circuit 72. The detection circuit 71 is a circuit for detecting the angular velocity ωy acting around the Y axis by using the sensor main body shown in FIG. 1, and the drive circuit 72 is configured to detect vibration when performing such detection. This is a circuit for driving the vibrator 130 to vibrate in the Z-axis direction.

Here, the resistance elements R1 and R2, the capacitance elements C1 and C2, and the logic circuit L1 for performing an exclusive OR operation shown in the upper part of the detection circuit 71 are the respective components of the circuit shown in FIG. Is exactly the same. The first signal supply circuit 10 is a circuit that generates a first periodic signal φ1, and the second signal supply circuit 20 is a circuit that generates a second periodic signal φ1.
2 is shown. This signal processing circuit further generates a third periodic signal φ3 to
4 and a fourth signal supply circuit 40 that generates a fourth periodic signal φ3 ^* and supplies the signal to the input terminal T5. Here, the third periodic signal φ3 and the fourth periodic signal φ3 ^* are the signals shown in the timing chart of FIG.

The logic circuit L2 performs a logical AND operation of the phase difference signal A obtained at the output terminal T3 and the third periodic signal φ3 provided at the input terminal T4 to obtain an output signal A1. . The logic circuit L3 logically inverts the phase difference signal A obtained at the output terminal T3 to obtain an inverted phase difference signal A ^* . The logic circuit L4 outputs the inverted phase difference signal A ^* and the input signal. Fourth periodic signal φ applied to terminal T5
3 ^* is a circuit for performing an AND operation with ^* to obtain an output signal A2. Further, the logic circuit L5 is a circuit that performs a logical sum operation of the output signal A1 and the output signal A2 to obtain the output signal B, and the integrating circuit 50 connected to the subsequent stage performs a logical sum operation on all the pulses included in the output signal B. And outputs an output signal C indicating the integrated value. Thus, an output signal C indicating a predetermined integrated value is obtained at the output terminal T6.

On the other hand, the drive circuit 72 is substantially a circuit constituted by the drive signal supply circuit 60. The drive signal supply circuit 60 is a circuit that generates an AC drive signal U to be supplied to the drive capacitance element C5. As described above, the AC drive signal U is a periodic signal having a cycle φ, and the AC drive signal U is connected to the fifth capacitive element C5.
, The vibrator 130 can be vibrated in the Z-axis direction.

Now, the operation of the signal processing circuit shown in FIG. 12 will be described with reference to the timing chart of FIG. As described in §3, a phase difference signal A as shown in FIG. 13 is obtained at the output terminal T3 of this circuit. Here, the pulse indicated by the dashed line is a pulse having a standard width obtained in a state where the angular velocity is not acting. In this example, by the action of the counterclockwise angular velocity ωy,
The pulse width of the odd-numbered pulse (period t11) is smaller than the standard width, and the pulse width of the even-numbered pulse (period t2)
1) is larger than the standard width. In the logic circuit L2, an AND operation of the phase difference signal A and the third periodic signal φ3 is performed, and an output signal A1 is obtained. Output signal A1
Is a signal obtained by extracting only the odd-numbered pulses in the phase difference signal A. On the other hand, the waveform of the inverted phase difference signal A ^* inverted by the logic circuit L3 and the waveform of the fourth periodic signal φ3 ^{* applied} to the input terminal T5 are as shown in FIG. The signal A2 is a pulse having a pulse width corresponding to a predetermined period t21 ^* as shown in the figure. Here, the period t21 and the period t21 ^* have a complementary relationship. That is, t21 + 2 · t21 ^* = φ /
Since there is a relationship of 2 (half cycle), as the period t21 increases, the period t21 ^* decreases, and as the period t21 decreases, the period t21 ^* increases.

In the logic circuit L5, a logical sum signal B of the signal A1 and the signal A2 is obtained. The logical sum signal B has a period t11 (pulse width of an odd-numbered pulse) as shown in FIG. And a pulse having a period t21 ^* (a value complementary to the pulse width of the even-numbered pulse). Therefore, the integrated value S of the pulse widths of all the pulses included in the OR signal B corresponds to the difference between the integrated value of the odd-numbered pulse of the phase difference signal A and the integrated value of the even-numbered pulse. Value. The integrating circuit 50 outputs an output signal C indicating the integrated value S to an output terminal T
Give to 6. The integrated value S corresponds to the total area of the hatched portion shown at the bottom of FIG.

There is a relationship between the integrated value S and the angular velocity ωy, for example, as shown in the graph of FIG. Although FIG. 14 shows a graph showing a linear relationship between the two for convenience of explanation, the relationship between the two is not necessarily a linear relationship. However, the relationship between them is always a monotonically increasing (or monotonically decreasing) function, and a one-to-one correspondence is always obtained between the integrated value S and the angular velocity ωy. Therefore, if the integrated value S is specified, the value of the angular velocity ωy is always specified. In the case of the graph of the linear relationship shown in FIG. 14, when the integrated value S takes the reference integrated value S0 (integrated value of a pulse having a standard width obtained without an angular velocity), the angular velocity ωy about the Y axis is used.
= 0, and when the integrated value S0 + ΔS is larger than the reference integrated value S0, it indicates that the angular velocity ωy about the Y axis is a positive value (for example, counterclockwise). When the integrated value S0−ΔS smaller than S0 is taken, it indicates that the angular velocity ωy around the Y axis is a negative value (for example, clockwise).

The reason for setting the predetermined phase difference p between the first periodic signal φ1 and the second periodic signal φ2 is to set the reference integrated value S0 to a predetermined value other than zero.
That is, when the phase difference is set to p = 0, the reference integrated value S0
= 0, so that it is impossible to obtain correct information on the direction of the angular velocity (clockwise or counterclockwise). If the phase difference p is provided in advance, the reference integrated value S0 can be set to a predetermined value other than zero, and whether the actually obtained integrated value S is larger or smaller than the reference integrated value S0 is determined. The direction of the applied angular velocity can be recognized from the information, and the actually obtained integrated value S and the reference integrated value S are obtained.
The magnitude of the applied angular velocity can be recognized from the difference ΔS from 0. It is preferable that the reference integrated value S0 be set to a value as large as possible so that the direction of the angular velocity can be correctly recognized even if ΔS increases to some extent. For that purpose, it is most preferable to set the phase difference p = π / 2.

§5. Other Embodiments While the present invention has been described based on the basic embodiment illustrating the present invention, some other embodiments of the present invention will be described here.

(1) Detection of angular velocity ωx So far, a signal processing circuit for detecting the angular velocity ωy acting around the Y axis using the sensor main body having the structure shown in FIG. 1 has been described. The angular velocity sensor shown in FIG. 1 has a function of detecting an angular velocity ωx about the X axis together with an angular velocity ωy about the Y axis. The angular velocity ωy about the Y axis is determined by the Coriolis force F acting in the X axis direction while vibrating the vibrator 130 having the mass m in the Z axis direction at the speed Vz.
x (Fx = 2 · m · Vz · ωy) could be determined. Similarly, the angular velocity ωx about the X-axis is determined by the Coriolis force Fy (Fy = 2 · m) acting in the Y-axis direction while vibrating the vibrator 130 having the mass m in the Z-axis direction at the speed Vz.
Vz · ωx) may be measured.

The detection circuit 71 shown in FIG. 12 is a signal processing circuit incorporating a first capacitance element C1 and a second capacitance element C2 arranged on the X axis. The output terminal T6 has a Coriolis force Fx The detected value of the angular velocity ωy based on the above was obtained.
Therefore, a circuit exactly the same as the detection circuit 71 is prepared.
If the first capacitance element C1 and the second capacitance element C2 are replaced with the third capacitance element C3 and the fourth capacitance element C4, respectively, the Coriolis force F is applied to the output terminal T6.
A detection value of the angular velocity ωx based on y is obtained.
Here, as described above, C1,
A circuit in which C2 is replaced with C3 and C4 is a detection circuit 73.
I will call it.

The sensor body shown in FIG. 1 has a structure capable of simultaneously detecting the angular velocities ωx and ωy. That is, of the electrodes shown in FIGS. 2 and 3,
The electrodes E15 and E25 (capacitance element C5) are
To vibrate in the Z-axis direction.
E21 (capacitance element C1) and electrodes E12 and E22 (capacitance element C2) are used to detect the angular velocity ωy based on the Coriolis force Fx, and electrodes E13 and E23 (capacitance element C3) and electrodes E14 and E24 (capacitance element). C4) is used to detect the angular velocity ωx based on the Coriolis force Fy. Therefore, in order to make this sensor body function as a two-axis angular velocity sensor, the above-described detection circuit 73 may be prepared in addition to the detection circuit 71 and the drive circuit 72 shown in FIG. . Driving circuit 7
When the vibrator 130 is vibrated in the Z-axis direction by using 2, the angular velocity ωy is obtained at the output terminal T6 of the detection circuit 71, and the angular velocity ωx is obtained at the output terminal T6 of the detection circuit 73. Will be.

(2) Detection Using a Single Capacitive Element In the examples described above, a pair of capacitive elements is used for detecting the angular velocity around one axis. For example, capacitive elements C1 and C2 are used to detect angular velocity ωy, and capacitive elements C3 and C4 are used to detect angular velocity ωx.
In this manner, the mode using a pair of capacitors can improve the detection accuracy as compared with the mode using a single capacitor, and is a practically preferable embodiment. However, the technical idea of the present invention is not limited to a mode using a pair of capacitors. Here, for reference,
It is shown that the angular velocity can be detected even when a single capacitance element is used.

For example, it will be shown that the angular velocity ωy can be detected by using only the single capacitive element C1. In this case, the capacitor C2 becomes unnecessary, but instead, a fixed capacitor C0 having a predetermined fixed capacitance may be used. That is, in the detection circuit 71 shown in FIG. 12, the capacitor C2 may be replaced with the fixed capacitor C0. The capacitance element C2 is a variable capacitance element constituted by the electrodes E12 and E22 of the sensor main body shown in FIG. 1, but the fixed capacitance element C0 used here is an element having a fixed capacitance value. It may be provided. For example, it is sufficient to provide a capacitor element on a circuit board on which the detection circuit 71 is mounted.

Now, as shown in FIG. 7, when the angular velocity ωy acts while the oscillator 130 is moving at the velocity + Vz, as described above, the Coriolis force +
Due to the action of Fx, the electrode spacing of the capacitive element C1 becomes smaller than when no angular velocity ωy is acting. Similarly, as shown in FIG. 8, considering the state when the angular velocity ωy acts while the vibrator 130 is moving at the velocity -Vz, as described above, the capacitive element is actuated by the action of the Coriolis force -Fx. The electrode interval of C1 is larger than when the angular velocity ωy is not acting. Thus, even if attention is paid only to the single capacitive element C1, the capacitance value changes due to the action of the Coriolis force.
Therefore, even when only a single capacitance element C1 is used, the delay signal D1 is still obtained in the timing chart shown in FIG.

However, when the fixed capacitance element C0 is used instead of the variable capacitance element C2, the other delay signal D2
Are slightly different from those shown in the timing chart of FIG. That is, since the capacitance value is fixed,
This is a fixed signal obtained by always delaying the periodic signal φ2 by a fixed delay time. However, since the delay signal D1 is a signal that changes in accordance with the action of the angular velocity, the phase difference signal A indicating the phase difference between the two signals includes a signal component indicating the action of the angular velocity. As described above, the angular velocity can be detected.

(3) Another Mode of Vibration In the example described so far, the fifth embodiment composed of the electrodes E15 and E25
The AC drive signal U is given to the capacitive element to vibrate the vibrator 130 in the Z-axis direction. However, the vibrating direction of the vibrator 130 is not necessarily limited to the Z-axis direction. For example,
Two types of AC drive signals U1 and U2 as shown in FIG.
(A rectangular wave signal having a duty ratio of 50% and a phase difference of π) is provided, the first AC drive signal U1 is supplied to the first capacitive element C1, and the second AC drive signal U2 is supplied to the second capacitor. If given to the element C2, the vibrator 130 will have X
It vibrates in the X-axis direction with the axial velocity component Vx.

As described above, when the vibrator 130 is vibrated in the X-axis direction, for example, the capacitance elements C3 and C4
Is used to detect the Coriolis force Fy acting in the Y-axis direction, it is possible to detect the angular velocity ωz about the Z-axis. Alternatively, if the Coriolis force Fz acting in the Z-axis direction is detected using the capacitance element C5 and the fixed capacitance element C0, the angular velocity ωy around the Y axis can be detected.

It should be noted that in any of the vibration modes,
It is preferable that an AC drive signal U having a resonance frequency capable of causing the vibrator 130 to vibrate most efficiently be provided and vibrated at this resonance frequency. The value of the resonance frequency can be obtained, for example, by conducting an experiment for applying AC drive signals of various frequencies to a prototype.

(4) More Practical Structure of Sensor Body The structure of the sensor body shown in FIG. 1 shows one embodiment of the present invention, and various other structures may be used. Is possible. For example, FIG. 16 is a side sectional view showing a more practical structure of the sensor body used in the present invention. A fixed substrate 220 is mounted on a flexible displacement substrate 210. A leg 221 is formed on the outer periphery of the fixed substrate 220, and the bottom surface of the leg 221 is fixed to the upper surface of the displacement substrate 210. Therefore, the displacement substrate 210 and the fixed substrate 220 are supported in parallel at a predetermined interval. A vibrator 230 is fixed to the center of the lower surface of the displacement substrate 210. A pedestal 240 is provided around the vibrator 230, and the pedestal 240 supports the displacement substrate 210 with respect to the base substrate 250. Vibrator 23
Since a small space is secured above and below 0, vibration in the vertical direction in the figure is possible.

FIG. 17 is a top view of the displacement substrate 210. As shown in this figure, five displacement electrodes E31 to E35 are formed on the upper surface of the displacement substrate 210. These are the displacement electrodes E in the embodiment shown in FIG.
These correspond to 11 to E15. On the other hand, FIG.
FIG. 4 is a bottom view of the fixed substrate 220. On the lower surface of the fixed substrate 220, a single common electrode E40 is formed. The common electrode E40 corresponds to the fixed electrodes E21 to E25 in the embodiment shown in FIG. As can be seen from the circuit diagram of FIG. 12, in an actual signal processing circuit,
One electrode of each of the capacitance elements C1 to C5 is grounded. Therefore, if one of them is used as the common electrode E40 and the common electrode E40 is grounded, no practical problem occurs. Rather, in order to simplify the structure, it is preferable to use one of the electrodes as a common electrode. In particular, if the fixed substrate 220 also serves as a sensor housing and is made of a conductive material, the fixed substrate 220 itself can be used as a common electrode, and the structure is further simplified.

(5) Another method of driving the vibrator In the above-described embodiments, the vibrator is vibrated by supplying an AC drive signal to the driving capacitive element. However, vibration energy is applied to the vibrator. As a supply method,
Any method is acceptable. For example, FIG.
The embodiment shown in FIG. 9 is different from the embodiment shown in FIG.
This is an example in which the driving method of the vibrator is changed to a method using magnetic force. That is, carry of the pedestal 245 is performed, and the vibrator 23
0, a magnetic field generating unit 300 is provided, and a driving signal supply circuit 310
Supplies an AC signal having a period φ. As the magnetic field generator 300, for example, a general electromagnetic coil may be used. At least a part of the vibrator 230 is made of iron,
If the oscillator 230 is made of a magnetic material such as cobalt or nickel and generates a periodic magnetic field based on an AC signal having a period φ in the magnetic field generator 300, the vibrator 230 can be vibrated up and down in the figure. In this case, the displacement electrode E35 constituting the driving capacitive element C5 becomes unnecessary.

[0073]

As described above, according to the angular velocity sensor using the vibrator according to the present invention, the vibrator is inclined by the action of the Coriolis force, and the change of the capacitance based on the inclination is reduced by two. Since the detection is performed as the phase difference between the two periodic signals, the signal processing circuit can be simplified, and the angular velocity can be detected efficiently.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a basic structure of a sensor main body of an angular velocity sensor according to one embodiment of the present invention.

FIG. 2 shows a displacement substrate 11 in the sensor body shown in FIG.
0 is a top view.

FIG. 3 shows a fixed substrate 12 in the sensor body shown in FIG.
0 is a bottom view.

FIG. 4 shows a vibrator 13 in the sensor main body shown in FIG.
FIG. 7 is a side sectional view showing a state where 0 is moved upward in the figure.

FIG. 5 shows a vibrator 13 in the sensor body shown in FIG.
It is a sectional side view showing the state where 0 was moved below the figure.

FIG. 6 shows a vibrator 13 in the sensor body shown in FIG.
6 is a timing chart showing waveforms of an AC drive signal U supplied to vibrate 0 in the vertical direction in the figure and a velocity component Vz of the vibrator 130.

FIG. 7 shows a vibrator 13 in the sensor body shown in FIG.
0 is a side sectional view showing a state in which a Coriolis force + Fx in the X-axis direction based on an angular velocity ωy around the Y-axis acts while 0 moves upward in the drawing.

FIG. 8 is a diagram showing a vibrator 13 in the sensor main body shown in FIG.
0 is a side cross-sectional view showing a state in which a Coriolis force −Fx in the X-axis direction based on the angular velocity ωy around the Y-axis acts while 0 moves downward in the figure.

FIG. 9 is a circuit diagram showing a part of a signal processing circuit used in the angular velocity sensor according to the present invention.

FIG. 10 is a timing chart for explaining an operation of the signal processing circuit shown in FIG. 9;

FIG. 11 is another timing chart for explaining the operation of the signal processing circuit shown in FIG. 9;

FIG. 12 is a circuit diagram showing a practical signal processing circuit used for the angular velocity sensor according to the present invention.

FIG. 13 is a timing chart for explaining the operation of the signal processing circuit shown in FIG.

14 is a graph showing a relationship between an integrated value S obtained by the signal processing circuit shown in FIG. 12 and an angular velocity ωy.

FIG. 15 shows a vibrator 1 in the sensor body shown in FIG.
6 is a timing chart showing waveforms of AC drive signals U1 and U2 supplied to vibrate the actuator 30 in the left-right direction in the figure and a velocity component Vx of the vibrator 130.

FIG. 16 is a side sectional view showing a more practical structure of a sensor main body used in the present invention.

FIG. 17 is a top view of the displacement substrate 210 in the sensor main body shown in FIG.

18 is a bottom view of the fixed substrate 220 in the sensor main body shown in FIG.

FIG. 19 is a side sectional view showing a structure of an embodiment in which a method of driving a vibrator is changed in the sensor main body shown in FIG. 16;

[Description of Signs] 10 to 40 Signal supply circuit 50 Integration circuit 60 Drive signal supply circuit 71 Detection circuit 72 Drive circuit 110 Displacement substrate 120 Fixed substrate 130 Vibrator 140 Device housing 210 ... displacement board 220 ... fixed board 221 ... leg part 230 ... vibrator 240, 245 ... pedestal 250 ... base board 300 ... magnetic field generation part 310 ... drive signal supply circuit A ... phase difference signal A1, A2 ... logical product signal A ^* ... Inverted phase difference signal B: output signal C: output signal C1 to C5: capacitive element D1, D2: delay signal d1, d2, d11, d12, d21, d22, t21
^* : Delay time E11 to E15: Displacement electrode E21 to E25: Fixed electrode E31 to E35: Displacement electrode E40: Common electrode G: Center of gravity L1 to L5: Logic element p: Phase difference P1, P2: Odd number period, even number R1, R2: resistance element S: integrated value S0: reference integrated value T1 to T6: input / output terminals t1, t2, t10, t11, t20, t21: period (pulse width) U, U1, U2: AC drive signal Vx, Vz: velocity components in the X-axis and Z-axis directions φ1, φ2, φ3, φ3 ^* : periodic signal with period φ ωy: angular velocity around Y-axis

Claims (10)

[Claims] 1. A method for detecting a Coriolis force acting on a vibrator vibrating in a first axis direction in a second axis direction orthogonal to the first axis, thereby detecting the first axis and the first axis. An angular velocity sensor for obtaining an angular velocity around a third axis orthogonal to both of the second axes, an apparatus housing accommodating a part or all of elements constituting the sensor, and being housed in the apparatus housing. The vibrator with respect to the device housing so that the vibrator can vibrate in the first axial direction and can be inclined by the action of the Coriolis force in the second axial direction. A driving means for vibrating the vibrator at a predetermined cycle φ in the first axial direction; a displacement electrode formed on the vibrator side; A fixed electrode formed on the body side; When the Coriolis force directed in the positive direction of the axis acts, the electrode interval becomes smaller due to the inclination of the vibrator, and when the Coriolis force directed in the negative direction of the second axis acts, the inclination of the vibrator causes A first capacitive element arranged so as to increase an electrode interval; a displacement electrode formed on the vibrator side; and a fixed electrode formed on the device housing side, wherein the second shaft is provided. When a Coriolis force directed in the positive direction is applied, the gap between the electrodes is increased by the inclination of the vibrator. When a Coriolis force directed in the negative direction of the second axis is applied, the electrode is inclined by the inclination of the vibrator. A second capacitance element arranged so as to have a smaller spacing, a first delay circuit formed by combining the first capacitance element and a resistance element, and a combination of the second capacitance element and a resistance element And a second delay circuit Generating a first periodic signal having a period phi, the first
A first signal supply circuit for supplying the first periodic signal to the first delay circuit; and generating a second periodic signal having the period φ and having a predetermined phase difference p with respect to the first periodic signal. A second signal supply circuit that supplies the second periodic signal to the second delay circuit; a first delay signal output from the first delay circuit;
A second delay signal output from the second delay circuit;
A phase difference detection circuit for generating a phase difference signal indicating a phase difference between the phase difference signal and the phase difference signal shown in the odd-numbered period and the even-numbered period. An angular velocity detection circuit that detects an angular velocity about a third axis based on at least one of the phase differences. 2. The angular velocity sensor according to claim 1, wherein a variable capacitance element having a displacement electrode formed on the vibrator side and a fixed electrode formed on the device housing side is used as the second capacitance element. An angular velocity sensor using a vibrator, wherein a fixed capacitance element having a predetermined fixed capacitance is used instead of using the fixed capacitance element. 3. The angular velocity sensor according to claim 1, wherein the angular velocity detection circuit detects an angular velocity based on a difference between a phase difference indicated in an odd-numbered period and a phase difference indicated in an even-numbered period. Angular velocity sensor using a vibrator characterized by detecting the following. 4. The angular velocity sensor according to claim 1, wherein the phase difference detection circuit uses a first logic element for calculating an exclusive OR of the first delay signal and the second delay signal. Detection, and the phase difference is indicated by the pulse width of the phase difference signal output by the first logic element. The angular velocity detection circuit generates a third signal having a period φ. And a second logic element for obtaining a logical product of the third periodic signal and the phase difference signal. The second logic element allows the odd-numbered pulse and the even number pulse of the phase difference signal to be obtained. An angular velocity sensor using a vibrator, wherein an angular velocity is detected based on at least one of a pulse width of the odd-numbered pulse and a pulse width of the even-numbered pulse. 5. The angular velocity sensor according to claim 1, wherein the phase difference detection circuit uses a first logic element for calculating an exclusive OR of the first delay signal and the second delay signal. Detection, and the phase difference is indicated by the pulse width of the phase difference signal output by the first logic element. The angular velocity detection circuit generates a third signal having a period φ. A circuit for generating a fourth periodic signal in a logically inverted state with respect to the third periodic signal;
A second logic element for obtaining a logical product of the third periodic signal and the phase difference signal; and a second logic element for generating an inverted phase difference signal that is in a logically inverted state with respect to the phase difference signal. A third logical element, a fourth logical element for obtaining a logical product of the fourth periodic signal and the inverted phase difference signal, an output signal of the second logical element, and an output signal of the fourth logical element And a fifth logic element for calculating a logical sum of the first and second logic elements, wherein an angular velocity is detected based on a pulse width of an output signal of the fifth logic element. 6. The angular velocity sensor according to claim 1, wherein the angular velocity detection circuit defines a phase difference in a state where no Coriolis force is acting as a reference value, and the actually detected phase difference Is larger than the reference value, the difference is output as the angular velocity in the first rotation direction. If the actually detected phase difference is smaller than the reference value, the difference is used as the first rotation. An angular velocity sensor using a vibrator, which outputs an angular velocity in a second rotation direction opposite to the direction. 7. The driving capacitive element according to claim 1, wherein the driving means includes a displacement electrode formed on the vibrator side and a fixed electrode formed on the apparatus housing side. When,
A drive signal supply circuit for supplying an AC drive signal having a period φ to the drive capacitance element, wherein the vibrator is vibrated by Coulomb force acting in the drive capacitance element. Angular velocity sensor using. 8. The angular velocity sensor according to claim 1, wherein at least a part of the vibrator is made of a magnetic material, and a driving means generates a magnetic field acting on a magnetic material portion of the vibrator. A magnetic field generator for generating the magnetic field, and a drive signal supply circuit for supplying an alternating current signal having a period of φ to the magnetic field generator. The vibrator is oscillated by generating a periodic magnetic field based on the alternating current signal in the magnetic field generator. An angular velocity sensor using a vibrator. 9. The angular velocity sensor according to claim 1, wherein the supporting means is constituted by a flexible displacement substrate having a part fixed to the apparatus housing and a vibrator fixed to a part. A fixed substrate is provided in the device housing so as to face the displacement substrate, and a displacement element formed on the displacement substrate and a fixed electrode formed on the fixed substrate constitute a capacitive element. An angular velocity sensor using a vibrator characterized in that: 10. The angular velocity sensor according to claim 9, wherein a plane perpendicular to the displacement substrate and including a center of gravity of the vibrator and a third axial direction is defined, and a first side is defined with respect to the plane. An angular velocity sensor using a vibrator, wherein a first capacitive element is formed on the second surface, and a second capacitive element is formed on a second side of the plane opposite to the first side.