JPH1030929A - Angular-velocity detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately detect angular-velocity by detecting the phase of the AC signal including the AC signal component in correspondence with the vibrating component of the second part and the other AC signal component with a detecting means connected to the second part. SOLUTION: This angular-velocity detector is provided with a vibrator 102, which has a vibrating first part 4 and a second part 6 that is mechanically connected to the first part and can perform the vibration including the vibrating component along a direction V3 of the force by the force acting on the first part 4 depending on the magnitudes of a vibrating velocity V1 and angular velocity Ω, and a detecting means, which is connected to the second part 6 and detects the phase of the AC signal including the AC signal component in correspondence with the vibrating component based on the force of the part 6 and the other AC signal component. Furthermore, the amplitude of the AC signal is changed by the change in environment, but the phase is not changed much. The phase of the AC signal detected by the detecting means is in correspondence with the angular velocity of a body to be detected. Therefore, when this device is used, the angular velocity can be accurately detected even when the environment change occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detector for detecting the angular velocity of a moving object by detecting Coriolis force, and more particularly to a technique for detecting angular velocity with high accuracy. INDUSTRIAL APPLICABILITY The angular velocity detection device of the present invention can be applied to a navigation system or attitude control of a moving object such as a vehicle, an aircraft, or a ship, or a camera shake correction of an imaging device.

[0002]

2. Description of the Related Art A so-called piezoelectric vibrating gyroscope having a piezoelectric vibrator is a kind of angular velocity detecting device.

[0003] Such a piezoelectric vibrating gyroscope is disclosed in
No. 91957. In the section of the prior art of this publication, a piezoelectric vibrating gyroscope using a vibrator in which a piezoelectric element is provided on three sides of a vibrating body of a regular triangular prism is disclosed. When the piezoelectric vibrating gyroscope is rotated about the axis of the vibrating body while exciting the vibrating body, Coriolis force acts on the vibrating body according to the angular velocity of rotation. Two piezoelectric elements provided on the vibrator output the amount of distortion of the piezoelectric element due to Coriolis force as a voltage signal. In a voltage signal from each piezoelectric element, a component of a drive signal when the vibrating body is not rotating is superimposed on a signal component due to Coriolis force. Since the voltage signals from these piezoelectric elements are input to the differential amplifier, the components of the drive signal are canceled out, so that the signal component due to the Coriolis force, that is, the angular velocity of the piezoelectric vibrating gyroscope can be detected.

[0004]

However, in the above-described conventional apparatus, when the environment such as temperature changes outside the apparatus, the amplitude of the excitation vibration of the vibrating body changes, and the Coriolis force is determined based on the amplitude change. Causes the signal component to change. Therefore, in the conventional device, the accuracy of the angular velocity detected based on the Coriolis force is not sufficient.

The present invention has been made based on such a problem, and it is an object of the present invention to provide an angular velocity detecting device capable of detecting an angular velocity with higher accuracy than before.

[0006]

The present invention provides an angular velocity detecting device for solving the above-mentioned problems. This device is
The present invention is directed to an angular velocity detection device that is provided on a detection target such as a moving body or an electronic information device that performs a rotational movement about a predetermined axis and detects the angular velocity of the detection target.

The device is mechanically coupled to the oscillating first portion and the first portion, and the force acting on the first portion depends on the speed of the vibration and the angular velocity of the first portion. A vibrator having a second portion capable of performing vibration including a vibration component along a direction, an AC signal component connected to the second portion and corresponding to a vibration component based on the force of the second portion, and another Detecting means for detecting the phase of the AC signal containing the AC signal component.

When the object to be detected rotates around a predetermined axis while the first portion is vibrating, a force depending on the speed of the vibration and the magnitude of the angular velocity of the object is applied to the first portion. That is, Coriolis force works. Since the first part is vibrating, the force dependent on the speed of the vibration periodically fluctuates in direction, so that the first part also vibrates the vibration component in a direction different from the direction of the vibration. Since the second portion is mechanically coupled to the first portion, the vibration component generated by the Coriolis force acting on the first portion is transmitted to the second portion, and the second portion is subjected to the Coriolis force. A vibration including a vibration component along the direction is performed.

The detecting means is connected to the second portion and detects a phase of an AC signal including an AC signal component corresponding to the vibration component of the second portion and another AC signal component. The phase of the AC signal changes depending on the amplitude of the AC signal component corresponding to the vibration component of the second portion, that is, the magnitude of the Coriolis force applied to the first portion. Since the Coriolis force depends on the angular velocity of the detection target, the present apparatus can detect the angular velocity of the detection target.

The amplitude of the vibration of the first portion, which does not depend on the Coriolis force, changes as the environment such as temperature changes. With this change in amplitude, the amplitude of the AC signal changes. However, even if the amplitude of the vibration of the first portion changes in a state where the Coriolis force is not applied, the phase of the AC signal hardly changes.

Further, the first part of the present device is configured such that the first piezoelectric crystal part vibrates in a predetermined direction by applying an AC voltage to the first piezoelectric crystal part made of a piezoelectric crystal. , At least two electrodes provided on the first piezoelectric crystal part, and the second part is made of a piezoelectric crystal,
A second piezoelectric crystal part mechanically coupled to the piezoelectric crystal part;
The AC signal, which has at least two other electrodes provided on the second piezoelectric crystal unit and whose phase is detected by the detection means, is a signal corresponding to a potential difference between the other electrodes or the signal It is preferable that the signal is a signal on which another AC signal component is superimposed.

In this case, since the first piezoelectric crystal portion is made of a piezoelectric crystal, an AC voltage is applied between the electrodes provided on the first piezoelectric crystal portion, whereby the first piezoelectric crystal portion is formed. The portion vibrates in a predetermined direction based on the inverse piezoelectric effect. At this time, when the detected object moves at a predetermined angular velocity,
A Coriolis force that depends on the speed of vibration of the first piezoelectric crystal unit along a predetermined direction and the angular velocity of the object to be detected acts on the first piezoelectric crystal unit. Vibrates along different directions. Since the second piezoelectric crystal portion is mechanically coupled to the first piezoelectric crystal portion, the vibration of the first piezoelectric crystal portion is transmitted to the second piezoelectric crystal portion, and the second piezoelectric crystal portion Performs a vibration including a vibration component along a direction different from the predetermined direction.

Since the second piezoelectric crystal portion is made of a piezoelectric crystal, a piezoelectric effect is generated between the other electrodes provided on the second piezoelectric crystal portion with the vibration of the second piezoelectric crystal portion. , A potential difference is generated. This potential difference includes a signal corresponding to a vibration component based on the Coriolis force of the second piezoelectric crystal unit. When this signal includes a vibration component not based on the Coriolis force as the another AC signal component, the phase of the AC signal changes according to the amplitude of the AC signal component based on the Coriolis force. If this signal does not include an AC signal component that is not based on the Coriolis force, if the another AC signal is superimposed on this signal, the phase of the AC signal becomes
It changes according to the amplitude of the signal of the vibration component based on the Coriolis force. The detecting means can detect the Coriolis force, that is, the magnitude of the angular velocity of the object by detecting the phase of the AC signal.

When the temperature characteristics of the first and second piezoelectric crystal portions change, a vibration component which becomes a noise transmitted from the first piezoelectric crystal portion to the second piezoelectric crystal portion, that is, is based on the Coriolis force. The amplitude of the non-vibrating component also changes. In such a case, the amplitude of the AC signal changes due to a change in the amplitude of the signal due to a vibration component that becomes noise, and the amplitude of the AC signal changes even when the angular velocity of the detected object is zero.
However, in this case, the amplitude of the AC signal changes, but the phase does not change. Since the detected phase corresponds to the angular velocity of the object to be detected, according to the present apparatus, even when the environment such as temperature changes, the detected angular velocity hardly changes.

Preferably, the detecting means includes a comparator for generating a square wave voltage from the AC signal, and the square wave voltage is preferably synchronously detected with a predetermined square wave voltage. The AC signal is converted to a square wave voltage by a comparator. These square wave voltages do not include amplitude information, but only phase information defined by the repetition period. Therefore, the square wave voltage is synchronously detected with a predetermined square wave voltage, thereby outputting a signal including only the phase information of the AC signal. This phase information corresponds to the angular velocity of the object to be detected. Therefore, even if the amplitude of the AC signal changes, the detected angular velocity of the detected object hardly changes.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the angular velocity detecting device according to the present invention will be described below with reference to the accompanying drawings.
In the following description, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 shows an angular velocity detecting device according to an embodiment. The apparatus includes a vibrator 102 fixed at one end to the front surface of a support 101 and a processing circuit 103 mounted on the back of the support 101. Note that, in the following description, the direction from the back surface to the front surface of the support base 101 is “up”.
Direction and the opposite direction is defined as the “down” direction.

The support table 101 has a main surface S1 and a main surface S1.
1 and has an installation surface S2 which is separated from the main surface S1 by a predetermined distance above the main surface S1.
Forms a step at its boundary.

The vibrator 102 has a fixing portion 1 at one end thereof, and the fixing portion 1 is fixed to an installation surface S2 of the support 101 with an adhesive or the like. The vibrator 102 includes a support rod 2 extending from the fixing part 1 in a direction from the installation surface S2 toward the main surface S1 while maintaining a predetermined distance from the fixing part 1 and the support table 101, and a base 3 supported by the support rod 2. A pair of excitation vibrating reeds 4 and 5 extending in a direction away from the base 3 with respect to the fixed portion 1 and a pair of detection vibrating reeds 6 and 7 extending from the base 3 in a direction approaching the fixed portion 1.

Further, the fixed portion 1, the support rod 2, the base 3, and the vibrating bars 4 to 7 are composed of an integral piezoelectric crystal member and a plurality of electrodes attached to the piezoelectric crystal member. The material of the piezoelectric crystal member according to the present embodiment is quartz.

Natural quartz is generally a columnar crystal, and the vertical central axis of the columnar crystal is defined as a Z axis or an optical axis, and a line passing through the Z axis and perpendicularly intersecting each surface of the columnar crystal. Is defined as the Y axis or the machine axis. Also, passing through the Z axis,
A line orthogonal to the vertical ridge line of the columnar crystal is defined as an X axis or an electric axis. The quartz used for the resonator 102 is an artificial quartz, but since the structure is the same as a natural quartz, in the description, the directions of the respective axes comply with the above-described rules. That is, the thickness direction of the vibrator 102 is defined as the Z axis, and axes perpendicular to the Z axis and perpendicular to each other are defined as the X axis and the Y axis, respectively.

Hereinafter, the vibrator 102 will be described in more detail based on this rule.

The fixing portion 1 is provided on the installation surface S2 of the installation table 101.
And has a lower surface fixed thereto. The lower surface is X
It has a rectangular shape along the axis and each side is defined by the X axis and the Y axis. The upper surface facing the lower surface has substantially the same shape as the lower surface. Note that the outer surface of the fixing portion 1 located between the upper surface and the lower surface is defined as a side surface of the fixing portion 1. One end of the support bar 2 is continuous with one side surface of the fixed portion 1 and extends from the fixed portion 1 along the Y axis. The base 3 is continuous with the other end of the support rod 2 and extends along the X axis.

FIG. 2 shows the vibrator 102 shown in FIG.
FIG. 4 is a cross-sectional view of the vibrator viewed from a direction of an arrow A line.

The first excitation vibrating reed 4 extends from one end of the base 3 in a direction away from the fixed portion 1 along the Y-axis, and as shown in FIGS. Crystal part 4p, upper electrodes 4a, 4d, lower electrodes 4c, 4f, and right electrode 4b fixed to each side surface of piezoelectric crystal part 4p
And the left side electrode 4e.

The cross section of the piezoelectric crystal portion 4p perpendicular to the Y axis is
It is a general rectangle defined by four sides. In the description, the outline rectangle does not mean an exact rectangle defined mathematically, and when an accurate rectangle cannot be formed due to etching at the time of manufacturing the piezoelectric crystal portion 4p, for example, of the four sides, The one in which one side is bent to form a pentagon is also generally defined as a rectangle. The piezoelectric crystal portion 4p includes these four sides, and has four side surfaces parallel to the Y axis. Of the side surfaces of these piezoelectric crystal parts 4p, the lower surface is the support 1
01 faces the main surface S1 via a space, and the upper surface faces the lower surface of the piezoelectric crystal part 4p. Also, the piezoelectric crystal part 4p
Are perpendicular to the upper and lower surfaces and face each other. Of these two sides, the one located on the right side when viewed from the tip direction of the resonator element 4 is defined as the right side, and the one located on the left side is defined as the left side.

The upper electrodes 4a and 4d are formed physically only on the upper surface of the piezoelectric crystal portion 4p, respectively, from the vicinity of the boundary between the base 3 and the vibrating piece 4 in the direction of the tip of the vibrating piece 4. Extending. The lower electrodes 4c and 4f are physically separated from each other only on the lower surface of the piezoelectric crystal portion 4p, and extend from the vicinity of the boundary between the base 3 and the vibrating reed 4 toward the tip of the vibrating reed 4. The right side electrode 4b covers a part of the right side surface of the piezoelectric crystal part 4p.

The right-side electrode 4b is maintained at a certain distance from the upper surface electrode 4a located on the right side, and extends along the longitudinal direction of the upper surface electrode 4a from the vicinity of the boundary between the base 3 and the vibrator bar 4 It extends in the tip direction and is physically separated from the upper surface electrode 4a. The left surface electrode 4e covers a part of the left side surface of the piezoelectric crystal part 4p.

The left-side electrode 4e is also kept at a constant distance from the upper surface electrode 4d located on the left side, and extends along the longitudinal direction of the upper surface electrode 4d from the vicinity of the boundary between the base 3 and the vibrating bar 4 from the vicinity of the vibrating bar 4. It extends in the tip direction and is physically separated from the upper surface electrode 4d. The electrodes 4b and 4e on the left and right sides are
Each of the lower electrodes 4c and 4f is kept at a fixed interval and physically separated from each other.

After these electrodes 4a to 4f are formed so as to cover the entire surface of the piezoelectric crystal portion 4p, the electrodes are physically separated only by removing the electrodes in the area between the electrodes. Can be. That is, these electrodes 4a to 4f
Can be separated by using a photolithography etching process.

The second excitation vibrating reed 5 extends from one end of the base 3 in a direction away from the fixed portion 1 along the Y-axis, and as shown in FIGS. Crystal part 5p, upper electrodes 5a, 5d, lower electrodes 5c, 5f, right electrode 5b fixed to each side surface of piezoelectric crystal part 5p
And the left side electrode 5e. The shortest distance between the YZ plane including the center line CL of the support bar 2 and the second excitation vibrating reed 5 is equal to the shortest distance between this surface and the first excitation vibrating reed 4. That is, the excitation vibrating reeds 4 and 5 are
Are arranged symmetrically with respect to

Since the second excitation vibrating reed 5 has the same structure as the first excitation vibrating reed 4, the detailed description of the structure is omitted.

Next, the detecting vibrating bars 6 and 7 will be described.

FIG. 3 is a sectional view of the vibrator 102 shown in FIG.
FIG. 4 is a cross-sectional view of the vibrator viewed from a direction of an arrow B line.

The first detecting resonator element 6 extends from one end of the base 3 in the direction approaching the fixed part 1 along the Y axis.
As shown in FIG. 3, a piezoelectric crystal portion 6p made of a piezoelectric crystal and an upper right electrode 6 covering each corner of the piezoelectric crystal portion 6p.
a, lower right electrode 6b, upper left electrode 6c, and lower left electrode 6d. The longitudinal direction of the first detecting vibration piece 6 is the first direction.
The length of the vibrating reeds 4 coincides with the longitudinal direction of the vibrating reed 4, and the shapes and weights of the vibrating reeds 6 and 4 are adjusted so that at least vibration in the Z-axis direction is transmitted.

The cross section of the piezoelectric crystal portion 6p perpendicular to the Y axis is
It is a general rectangle defined by four sides. The piezoelectric crystal part 6p includes these four sides, and has four sides parallel to the Y axis. Four corners of the piezoelectric crystal part 6p are defined by the intersection of the four sides. Of the side surfaces of these piezoelectric crystal parts 6p, the lower surface is
1 faces the main surface S1 via a space, and the upper surface faces the lower surface of the piezoelectric crystal portion 6p. The remaining two side surfaces of the piezoelectric crystal portion 6p are perpendicular to the upper surface and the lower surface and face each other. Of these two sides, the one located on the right side when viewed from the tip direction of the resonator element 4 is defined as the right side, and the one located on the left side is defined as the left side.

The upper right electrode 6a covers only the corner defined by the intersection of the upper surface and the right side of the piezoelectric crystal portion 6p, and the lower right electrode 6b is connected to the lower surface and the right side of the piezoelectric crystal portion 6p. It covers only the corner defined by the intersection with the surface. The upper left electrode 6c is connected to the piezoelectric crystal part 6p.
Covers only the corner defined by the intersection of the upper surface and the left side surface of the piezoelectric crystal part 6p.
Covers only the corners defined by the intersection of the lower surface and the left side surface. Each of the electrodes 6a to 6d extends from the vicinity of the boundary between the base 3 and the vibrating piece 6 toward the tip end of the vibrating piece 6 while maintaining a predetermined interval therebetween, and is physically separated from each other.

FIG. 4 is a cross-sectional view of the resonator element 6 shown in FIG. 1 when viewed from the direction of the arrows CC.

When the mass of the resonator element 6 changes, the natural frequency of the resonator element changes. The change in mass and shape of the electrode on the tip side of the resonator element 6 has a greater effect on the natural frequency of the resonator element 6 than on the root side. Further, since the stress acting on the tip side is smaller than that on the root side, the change in the mass and shape of the electrode on the tip side of the resonator element 6 has less influence on the detection sensitivity than on the root side. Therefore, in order to adjust the natural frequency, FIG.
As shown in FIG. 4, the upper right electrode 6 a and the upper left electrode 6 c on the tip side of the position of the center of gravity of the resonator element 6 have a region TR partially removed by trimming. In other words, the interval between the upper right electrode 6a and the upper left electrode 6c at the tip of the resonator element 6 is wider than the interval on the root side of the resonator element 6. The removal of such an electrode can be performed using a laser beam machine.

The second detecting vibrating piece 7 extends from one end of the base 3 in the direction approaching the fixed portion 1 along the Y axis.
As shown in FIG. 3, a piezoelectric crystal portion 7p made of a piezoelectric crystal and an upper right electrode 7 covering each corner of the piezoelectric crystal portion 7p.
a, a lower right electrode 7b, an upper left electrode 7c, and a lower left electrode 7d. The shortest distance between the YZ plane including the center line CL of the support rod 2 and the second detecting vibrating bar 7 is equal to the shortest distance between this surface and the first detecting vibrating bar 6. That is, these detecting vibrating reeds 6 and 7 correspond to the exciting vibrating reeds 4 and 5.
Similarly to the above, they are arranged at symmetrical positions with respect to the support rod 2.

In the second detecting vibrating bar 7, the electrode on the tip side of the vibrating bar 7 is not removed like the first detecting vibrating bar 6. Except for this point, the second detecting vibrating bar 7 is
Since it has the same structure as the first detecting vibrating reed 6, the detailed description of the structure is omitted. In addition, each vibrating reed 4
It is preferable that the vibrator 102 is disposed in a closed container whose internal pressure is set lower than the atmospheric pressure so that the vibrations 7 to 7 are stably vibrated.

Each of the piezoelectric crystal parts 4p, 5p, 6p,
It is desirable that the upper surface and the lower surface of 7p are each perpendicular to the Z axis, but may be shifted from the plane perpendicular to the Z axis by an angle of 15 ° or less.

Next, the excitation of the vibrator 102 and the detection of the angular velocity will be described.

FIG. 5 shows the electrodes 4a-4 of the vibrating bars 4-7.
The connection relation of f, 5a to 5f, 6a to 6d, and 7a to 7d and the processing circuit 103 electrically connected to these electrodes are shown.

The upper and lower electrodes 4a on the right side of the vibrating piece 4 for excitation,
4c and the left side electrode 5e of the excitation vibrating piece 5 are electrically connected to the terminal T1 via the wiring W1. The right-side electrode 4b of the vibrating piece 4 for excitation and the upper and lower electrodes 5d and 5f on the left side of the vibrating piece 5 for excitation are electrically connected to the terminal T2 via the wiring W2.

The left side electrode 4e of the excitation vibrating piece 4 and the upper and lower electrodes 5a, 5c on the right side of the excitation vibrating piece 5 are electrically connected to a terminal T3 via a wiring W3. The upper and lower electrodes 4d and 4f on the left side of the excitation vibrating reed 4 and the right side electrode 5b of the excitation vibrating reed 5 are electrically connected to the terminal T4 via the wiring W4.

Further, the upper right electrode 6a,
The lower left electrode 6d and the lower right electrode 7b and the upper left electrode 7c of the detecting resonator element 7 are connected to a terminal T5 via a wiring W5. The lower right electrode 6b and the upper left electrode 6c of the detecting vibrating reed 6 and the upper right electrode 7a and the lower left electrode 7d of the detecting vibrating reed 7 are connected to the terminal T6 via the wiring W6. Note that these wirings W1 to W6 are formed using photolithography technology.
It is desirable that the vibrator 102 be formed so as to reach the fixed portion 1 through a region on the support bar 2 of the vibrator 102 shown in FIG.

The input terminals T1 to T6 are connected to the processing circuit 10
3 is electrically connected to the input side, and the output side of the processing circuit 103 is electrically connected to the output terminal T7.

The processing circuit 103 includes an excitation drive circuit including an excitation circuit 8, current-voltage conversion circuits 9 and 10, a differential amplifier circuit 11, and a comparator 12, and the comparator 12, the comparator 17, and the phase shift circuit. 18. Synchronous detection circuit 19 and integration circuit 2
And a detection circuit (detection means) 103a composed of 0. Further, the processing circuit 103 includes current-voltage conversion circuits 13 and 14, a differential amplifier circuit 15 and a mixer circuit 16 on the input side of the detection circuit 103a, and the offset adjustment circuit 21 and the amplification circuit on the output side of the detection circuit 103a. 22. Note that the comparator 12 is also used for the excitation drive circuit and the detection circuit 103a.

FIG. 6 is a timing chart for explaining the operation of the processing circuit 103. Graphs (c) and (f) to (k) show nodes C and F to K in FIG. 5, respectively.
3 shows a voltage waveform of the first embodiment. Hereinafter, the operation of the angular velocity detecting device according to the embodiment will be described with reference to FIG.

The excitation circuit 8 branches the input AC voltage signal into two, and inverts and outputs one of the branched AC voltage signals using an inverter. One of the branched AC voltage signals is input to a terminal T1, and the other is input to a terminal T2 without passing through an inverter. The voltage at the point A input to the terminal T2 is a square wave voltage having a predetermined repetition frequency. Since the voltage input to the terminal T1 is obtained by inverting this voltage, the voltage between the right upper electrode 4a and the right upper electrode 4b of the excitation vibrating reed 4 in FIG. The indicated square wave voltage (first AC voltage) is applied.

In the following description, a square wave voltage is not an exact one whose rise and fall times are zero and whose amplitude is constant, and its waveform is slightly distorted from a rectangle due to the time constant of the circuit and the like. A pulse wave voltage is also defined as a square wave voltage. The waveform of the first AC voltage applied between the electrodes may be a sine wave or the like as long as the vibration of the resonator element 4 is started and the vibration is maintained.

When a voltage is applied to the excitation vibrating reed 4, the piezoelectric crystal portion 4p is polarized by the inverse piezoelectric effect and bends along the X-axis direction. Since a square wave voltage having a predetermined repetition frequency is applied to the excitation vibrating reed 4 according to the present embodiment, the piezoelectric crystal portion 4p vibrates along the X-axis direction. In other words, the electrodes 4a to 4c are provided on the piezoelectric crystal part 4p so as to bend along the X-axis direction when a square wave voltage as the first AC voltage is applied.
Again, since the structure of the resonator element 5 is the same as the structure of the resonator element 4, the electrode 5 connected to the terminals T1 and T2
e, 5d, and 5f, when a voltage is applied between the piezoelectric crystal parts 5
p also vibrates along the X-axis direction.

When the vibrating piece 4 for excitation vibrates, electric charges are induced in the central area on the left and right sides and the central area on the upper and lower faces of the vibrating piece 4. The electric charge induced on the left side surface is converted into a voltage signal by the current-voltage conversion circuits 9 and 10 via the left surface electrode 4e, and the electric charge induced on the upper and lower surfaces via the upper and lower surface electrodes 4d and 4f, respectively. Therefore, the differential amplifier circuit 1 to which the outputs from the current-voltage conversion circuits 9 and 10 are input
At 1, an AC voltage corresponding to the potential difference between the electrodes 4e and 4d is detected. That is, by applying a square wave voltage shown in FIG. 6A between the terminal T1 connected to the electrodes 4a, 4c, 5e and the terminal T connected to the electrodes 4b, 5d, 5f, As shown by arrows V1 and V2 in FIG.
Vibrates so as to bend in opposite directions along the X-axis direction. On the other hand, the terminal T3 connected to the electrodes 4e, 5a, 5c
An AC voltage corresponding to the potential difference between the terminal and the terminal T4 connected to the electrodes 4f, 4d, 5b is detected by the differential amplifier circuit 11.

The voltage output from the current-to-voltage conversion circuit 9 due to the vibration of the excitation vibrating reed 4 is a sine wave voltage shown in FIG. 10, the sine wave voltage _Vf shown in FIG. 6C is output from the differential amplifier circuit 11 to which these sine wave voltages are input. The amplitude of the voltage waveform shown in FIG. 6C is smaller than the amplitude of the voltage waveform shown in FIG. 6C for convenience of description in the drawing, but the amplitude of the voltage waveform shown in FIG. Greater than the amplitude of Here, the phase of the rise time of the square wave voltage shown in FIG. 6A is set to −90 °, and the excitation AC voltage _Vf output from the differential amplifier circuit 11 is given by the following equation. .

[0056]

(Equation 1) Here, _Af is the amplitude, ω is the angular frequency of the AC voltage, and t is the time.

The AC voltage output from the differential amplifier circuit 11 is input to the comparator 12. Comparator 12 outputs a high-level voltage signal when a voltage signal higher than a predetermined voltage level is input, and outputs a low-level voltage signal when a voltage signal lower than the predetermined voltage level is input. . Since the differential amplifier circuit 11 outputs a sine wave voltage having an amplitude center at a predetermined voltage level shown in FIG. 6C, the comparator 12 outputs a square wave voltage synchronized with the sine wave voltage. Is output. Therefore, the sine wave voltage output from the differential amplifier 11 is pulse-shaped by the comparator 12 into a square wave voltage.

The excitation circuit 8 inverts the polarity of the input square wave voltage in accordance with the repetition period of the square wave voltage and outputs the inverted voltage.
Therefore, the excitation circuit 8, the vibrators 4 and 5, the current-voltage conversion circuits 9 and 10, the differential amplifier circuit 11 and the comparator 12
Constitutes a feedback loop, and since this loop satisfies the oscillation condition, the resonator elements 4 and 5 continuously vibrate along the X-axis direction. In this feedback loop,
Since the comparator 12 detects the phase of the vibration of the vibrating bars 4 and 5 and generates a square wave for vibrating the vibrating bars 4 and 5, the phase at the time of vibration is stabilized. If this phase is used as a reference, the phase of the voltage signal generated by the Coriolis force described later can be detected with high reliability.

When the vibrator 102 is rotated in the direction indicated by the arrow Ω in FIG. 1 in a state where the pair of excitation vibrating reeds 4 and 5 are vibrating in the X-axis direction at the speed V, the vibrating reeds 4
And 5, a Coriolis force proportional to V × Ω acts along the Z-axis direction, and the excitation vibrating reeds 4 and 5 also vibrate also in the direction along the Z-axis.

On the other hand, the detecting vibrating reeds 6 and 7 are mechanically coupled to the exciting vibrating reeds 4 and 5, respectively, to such an extent that the vibration in the Z-axis direction is transmitted.
The detecting vibrating bars 6 and 7 vibrate along the Z-axis along with the axial vibration. As shown by arrows V3 and V4 in FIG. 1, the detecting vibrating bars 6 and 7 have opposite phases, that is, the Z of each vibrating bar 6 and 7 at an arbitrary time during vibration.
It vibrates so that the velocity vectors in the axial direction are opposite to each other.

When the detecting vibrating bars 6 and 7 bend in the Z-axis direction and vibrate due to the Coriolis force, the piezoelectric effect causes the piezoelectric crystal portions 6 and 7 of the detecting vibrating bars 6 and 7 shown in FIG.
Electric charges are generated at all corners of p and 7p. Since these charges are efficiently detected by the electrodes 6a to 6d and 7a to 7d covering the corners, the potential difference between the electrodes is detected with high accuracy.

The electric charge generated at the corner covered by the upper right electrode 6a of the detecting resonator element 6 is converted into a voltage signal by the current-voltage conversion circuit 13, and the electric charge generated at the corner covered by the upper left electrode 6c is Is converted into a voltage signal by the current / voltage conversion circuit 14. These voltage signals are supplied to the differential amplifier 15
, A voltage signal including a signal corresponding to the potential difference between the electrodes 6 a and 6 c is output from the differential amplifier circuit 15.

Since this potential difference is generated based on the bending of the detecting vibrating piece 6 due to the Coriolis force, if a signal corresponding to this potential difference is detected, the Coriolis force,
That is, the rotational angular velocity applied to the vibrator 102 can be detected.

The electric charge generated at the corner covered by the upper right electrode 7a of the detecting resonator element 7 is converted into a voltage signal by the current / voltage converter 14 and generated at the corner covered by the upper left electrode 7c. The electric charge is converted into a voltage signal by the current-voltage conversion circuit 13. Since these voltage signals output from the detecting resonator element 7 are also input to the differential amplifier circuit 13, the voltage signals output from the differential amplifier circuit 15 correspond to the voltages between the electrodes 7a and 7c. Signal components are also included.

The electrode 6 covering the remaining corners of the detecting resonator element 6
The signals from d and 6b are superimposed on the signals from the electrodes 6a and 6c, respectively, and the signals from the electrodes 7d and 7b covering the remaining corners of the detecting vibrating bar 7 are the signals from the electrodes 7a and 7c, respectively. Superimposed. Therefore, the intensity of the voltage component based on the Coriolis force with respect to the noise component is increased by the superposition, and the accuracy of detecting the angular velocity by the present apparatus is further increased by the superposition.

Therefore, the differential amplifier circuit 15 includes the electrodes 4a to 4f, 5a provided on the piezoelectric crystal portions 4p and 5p.
By applying the first AC voltage _Vf to the other electrodes 6a to 6p provided in the piezoelectric crystal portions 6p and 7p.
d, and outputs a second AC voltage V _o corresponding to the potential difference generated between 7a to 7d.

[0067] FIG. 6 (e) of the second alternating voltage at which the AC voltage V _o output from the differential amplifier circuit 15, indicating the component of the AC voltage based on the Coriolis force. That is, the AC voltage V _s based on the Coriolis force is given by the following equation.

[0068]

(Equation 2) However, A _s is a constant, Omega is the angular velocity, is [Phi _s is the phase.

In most cases, the cross-sectional shapes of the vibrating bars 4 to 7 are not completely rectangular due to the above-described imperfect etching, and the cross-sectional shapes are not symmetric with respect to the YZ plane including the center of gravity. Here, the excitation vibrating reeds 4 and 5 are vibrated along the X-axis direction, but the vibrations of the vibrating reeds 4 and 5 are along the Z-axis direction based on the anisotropy or asymmetry of the shape. It has a leak vibration component. Since the detection vibrating reeds 6 and 7 are mechanically coupled to the excitation vibrating reeds 4 and 5 to such an extent that the vibration in the Z-axis direction is transmitted, the leakage vibrations
And 5 to the detecting vibrating bars 6 and 7. FIG.
(D) shows the AC voltage V output from the differential amplifier circuit 15;
Of _o, indicating the component of the AC voltage V _n based on the leakage vibration.
That is, the AC voltage V _n based on the leakage vibration is given by the following equation.

[0070]

(Equation 3) Here, _An is an amplitude, and Φ _n is a phase.

[0071] AC voltage V _n based on the leak vibration, an AC voltage V _f and the phase output from the vibration-use vibrating bars 4 and 5 shown in FIG. 6 (c) are offset [Phi _n. The amplitude of the AC voltage V _n based on the leaked vibration along the Z-axis direction A _n is an AC voltage V _s based on the Coriolis force along the Z-axis direction amplitude A _s
It is larger than × Ω.

[0072] differential from the amplifier circuit 15, FIG. 6 to the AC voltage V _s based on the Coriolis force (e), a second AC voltage V _n based on the leak vibration component is superimposed shown in FIG. 6 (d) AC voltage V _o is output. FIG. _6F shows the second AC voltage Vo output from the differential amplifier circuit 15 and is given by the following equation.

[0073]

(Equation 4) Where A _o is the amplitude and Φ _o is the phase.

Here, when the ambient temperature is constant, the amplitude A _{f of the} excitation AC voltage V _f output from the differential amplifier circuit 11
When you make the transition, the AC voltage V _n by leakage vibration amplitude A
_n varies in proportion to the amplitude A _f of the excitation AC voltage V _f. However, even _if the amplitude A _{f of} the excitation AC voltage V _f changes, the phase Φ _n of the AC voltage V _n due to the leakage vibration hardly changes.

In a state where Coriolis force is not applied to the vibrating bars 4 and 5, that is, in a state where the angular velocity Ω = 0, Equation 4
As it is apparent from, detection AC voltage V _o is equal to the AC voltage V _n by leakage vibration. As described above, even _if the amplitude A _f of the excitation AC voltage V _f changes, the phase Φ _n of the AC voltage V _n due to the leakage vibration does not change. Therefore, when the angular velocity Ω = 0, the excitation AC voltage V _f is changed. _{Even if} the amplitude A _{f of f} changes, the phase Φ _o of the detection AC voltage V _o does not change. In other words,
The amplitude A _o of the detected AC voltage V _o output from the differential amplifier circuit 15 vary, the phase [Phi _o does not change.

[0076] On the other hand, when the Coriolis force is exerted on the vibration-use vibrating bars 4 and 5, the amplitude A _o and phase [Phi _o of detection AC voltage V _o output from the differential amplifier circuit 15 is changed.
Therefore, if the phase Φ _o of the detection AC voltage V _o is detected, the angular velocity of the object to be detected based on the Coriolis force can be detected.

Note that the linearity of the change in the phase Φ _o of the AC voltage V _o output from the differential amplifier circuit 15 is such that the amplitude of the signal superimposed on the AC voltage signal V _s based on the Coriolis force is large and the phase difference is large. The higher is the higher. Therefore, in this device,
Such signals, i.e., large amplitude as compared to the AC voltage signal V _s based on a Coriolis force, the phase 90 ° shifted excitation AC voltage signal V _f, detection by the mixer circuit 16 AC signal V _o Superimposed on Although the leakage signal changes due to a manufacturing error or temperature, a change in the excitation AC voltage signal _{Vf having} a large amplitude is small with _{respect to} the change.
Therefore, the signal superimposed by the mixer circuit 16 has high stability and the detection output is stable.

The mixer circuit 16 outputs a part of the excitation AC voltage signal _Vf output from the excitation side differential amplifier circuit 11 shown in FIG. 6C and the output from the detection side differential amplifier circuit 15. and the detection AC voltage signal V _o was synthesized. The output voltage V _t from the mixer circuit 16 shown in FIG. 6 (g). Phase of the AC voltage signal V _t output from the mixer circuit 16,
It changes substantially in proportion to the amplitude A _s × Ω of the AC voltage V _s based on the Coriolis force. The AC voltage signal V _t is given by the following equation.

[0079]

(Equation 5) However, A _t is the amplitude, Φ _t is phase.

The AC voltage signal output from mixer circuit 16 is input to comparator 17. Comparator 17 outputs a high-level voltage signal when a voltage signal higher than a predetermined voltage level is input, and outputs a low-level voltage signal when a voltage signal lower than the predetermined voltage level is input. . From the mixer circuit 16, the second AC voltage V
signal based on _o, i.e., the AC voltage V _t of the amplitude around a predetermined voltage level is outputted from the comparator 17, a square wave voltage synchronized with the AC voltage V _t is output. FIG. 6H shows the square wave voltage output from the comparator 17.

On the other hand, the square wave voltage output from the comparator 12 on the excitation side is input to the phase shift circuit 18 and the phase thereof is changed to the AC voltage V shown in FIG. _It is shifted 90 ° with respect to _f . The first square wave voltage output from the comparator 12 on the excitation side and the second square wave voltage output from the comparator 17 on the detection side are input to the synchronous detection circuit 19, and these square wave voltages are shown in FIG. Multiplied as shown in j).

These first and second square wave voltages do not include amplitude information but only phase information defined by the repetition period. Therefore, the second square-wave voltage is synchronously detected with the first square-wave voltage to output a signal including only phase information of a signal based on the second AC voltage. That is, the square wave voltage has the amplitude information removed and includes only the phase information. When the amplification factor of the amplifier constituting the processing circuit 103, the capacitance of the capacitor, the resistance value of the resistor, and the like change, the amplitude of the AC voltage signal (g) based on the second AC voltage changes. However, since the first and second square wave voltages do not include the amplitude information, the signal-to-noise ratio of the processing circuit 103 can be improved, and the detection accuracy of the finally detected angular velocity of the detected object can be improved. be able to.

The characteristics of the elements constituting the processing circuit 103 change depending on the temperature and the like. Therefore, the processing circuit 10
In 3, the signal based on the second AC voltage is converted into a second square wave voltage, and this is compared with the first square wave voltage.
The detection output of the processing circuit 103 does not change with the temperature change. In addition, since this device uses this configuration, it is not necessary to use a specific temperature compensation circuit, and the device can be manufactured at low cost.

The DC component of the AC voltage signal output from the synchronous detection circuit 19 is the phase of the AC voltage signal output from the mixer circuit 16, that is, the amplitude A _s × Ω of the AC voltage signal V _s based on the Coriolis force. Changes substantially in proportion to. Therefore, if the AC voltage signal output from the synchronous detection circuit 19 is input to the integration circuit 21, a DC voltage signal that changes depending on the Coriolis force can be obtained. If the amplitude of the square wave output from the synchronous detection circuit 19 is assumed to be 1 and zero-crossing is performed, the output _Vy is given by the following equation.

[0085]

(Equation 6)

The offset adjustment circuit 21 is adjusted so that the DC voltage signal output from the amplification circuit 22 becomes 2.5 V when the angular velocity of the object to be detected is 0. Therefore, a DC voltage signal depending on the angular velocity of the detected object is output from the output terminal T7.

Hereinafter, further advantages of the apparatus according to this embodiment will be described.

FIG. 7 is a graph showing the frequency characteristic of the Q value of the vibration of the excitation vibrating reed 4 or 5 in the X-axis and Z-axis directions.

When the frequency of the vibration in the X-axis direction of the vibrating piece 4 or 5 coincides with the natural frequency f _x of the vibrating piece 4 in the X-axis direction, the Q of the vibration (horizontal vibration) A in the X-axis direction is obtained. And the vibration of the resonator element 4 in the X-axis direction is
Vibrates with the largest amplitude. On the other hand, Z of the excitation vibrating piece 4
When the frequency of the vibration in the axial direction matches the natural frequency f _z of the vibrating reed 4 in the Z-axis direction, the Q value of the vibration (vertical vibration) B in the Z-axis direction becomes highest, and therefore the Z The axial vibration oscillates with the largest amplitude.

[0090] Q value when Here, the vibrating reed 4 in the frequency f _x for Q value (Q _m) when vibrating the vibrating reed 4 in the X-axis direction at the frequency f _x vibrates in the Z-axis direction ( Q ₁ )
Is the transmission efficiency η. When the natural frequency f _{x in} the X-axis direction of the vibrating reed 4 matches the natural frequency f _{z in the} Z-axis direction,
That is, when the frequency difference f _z −f _x = 0, the transmission efficiency η becomes maximum, and the amplitude of the vibration of the vibrating piece 4 along the X-axis and Z-axis directions can both be maximized. Also,
In case that the transfer efficiency η higher natural frequency f _x and f _z of the respective directions away from each other decreases, to vibrate the vibrating reed 4 with a frequency f _x to maximize the amplitude of vibration in the X-axis direction, Z axis The amplitude of the directional vibration decreases. The frequency characteristic of the Q value of the vibration of the resonator element 4 in the X-axis direction has temperature dependency,
Since it is different from that in the Z-axis direction, the transmission efficiency η changes with temperature.

When the excitation vibrating reed 4 is vibrated along the X-axis direction, leakage vibration is induced based on the anisotropy or asymmetry of the shape of the vibrating reed 4. Since the amplitude of the vibration in the Z-axis direction depends on the transmission efficiency η, if the transmission efficiency η increases due to a temperature change, the amplitude of the leakage vibration increases.
In other words, in order to reduce the influence of the leakage vibration due to the temperature change, it is better to make the natural frequencies in the X-axis direction and the Z-axis direction different. In this case, the vibration component in the Z-axis direction due to the Coriolis force Also becomes smaller. On the other hand, in order to increase the amplitude of the vibration due to the Coriolis force, the X-axis direction and Z
It is preferable to make the natural frequency in the axial direction closer, but in this case, the amplitude of the vibration component due to the leakage vibration increases.

FIG. 8 is a diagram for explaining the movement of the center of gravity of the resonator element 4 in the XZ plane due to the leakage vibration. AC voltage V _n due to leakage vibration, an AC voltage V _nx generated by exciting a vibration member 4 is linearly reciprocated as shown by the solid line arrow L1 along a direction intersecting the X-axis at a predetermined angle, excitation This is considered to be a composite voltage of the AC voltage _Vnz generated by the vibrating bars 4 and 5 performing an elliptical motion having a major axis coinciding with the X axis as shown by the solid arrow E1.

That is, the AC voltages V _nx and V _nz are represented by the following equations.

[0094]

(Equation 7) Here, k _nx is a constant, and k _of is the value of the amplitude A _nx when the transmission efficiency η is 0.

[0095]

(Equation 8)

Here, k _nz is a constant, and k _ofz is the value of the amplitude A _nz of the voltage induced by the reciprocating linear motion caused by the asymmetry of the shape when the transmission efficiency η is 0.

[0097] Incidentally, the constant A _s described above (Equation 2) is given by the following equation.

[0098]

(Equation 9)

As the transmission efficiency η increases, the component of the leakage vibration along the Z-axis direction increases. Therefore, the reciprocating linear motion and the elliptical motion correspond to the solid arrows L1 and E1 in FIG.
9 changes to the motion indicated by the dotted arrows L1 and E1, and the leakage vibration changes from the solid arrow C1 in FIG. 9 to the motion indicated by the dotted arrow C1.

Therefore, as the transmission efficiency η changes,
Generated by leakage vibration AC voltage V _n amplitude A _nx and A _nz of the AC voltage configuration is changed, the amplitude A _n of the AC voltage V _n by leakage vibration changes.

[0102] According to the above-described apparatus, in a state where the Coriolis force is not applied to the vibration-use vibrating bars 4 and 5, even if the amplitude A _n of the AC voltage V _n due to leakage vibration is changed, detection AC voltage V The phase of _o does not change. Therefore, in this state, even after changing the amplitude V _n transmission efficiency by a change in environment such as temperature η is changed, also the excitation AC voltage V _f
This apparatus can accurately detect the Coriolis force, that is, the angular velocity of the object to be detected, even _if the amplitude _Af of the object changes. As described above, since the detection output of the present apparatus does not change much with the change of the transmission efficiency η, the natural frequency f in the X-axis direction
_{It is} possible to increase the transmission efficiency η by making _x and f _z closer to each other as compared with the related art, to increase the amplitude of the vibration due to the Coriolis force, and therefore to improve the signal-to-noise ratio of the detection output. According to the apparatus of the present embodiment, if the shape anisotropy or asymmetry of the vibrating bars 4 and 5 is improved, the ratio of the excitation AC voltage mixed in the mixer circuit 16 increases, so that the detection output Accuracy can be further improved.

FIG. 10 shows a state where the Coriolis force is not acting on the vibrator 102 (Ω = 0 deg / sec), and the output from the amplifier circuit 22 when the amplitude of the vibration of the vibrating vibrating reeds 4 and 5 changes. 6 is a graph showing a DC voltage value. Note that k
_nz · η = 5 mV, K _ofz = 0, k _nx · η = 3.5 m
V, k _of = 11 mV. Sensor sensitivity is 15.3μ
V. FIG. 11 is a graph showing a DC voltage value output from the conventional device in this state as a comparison.
As is clear from these graphs, the output of the above-described conventional device changes with the change in the amplitude of the vibration of the excitation vibrating reeds 4 and 5, but the output of the present device does not change. Further, even when the Coriolis force is applied to the vibration-use vibrating bars 4 and 5, since the phase change in the detected AC voltage V _o by the amplitude change of the AC voltage V _n by leakage vibration is small, according to the apparatus In addition, the detection accuracy of the angular velocity of the detection target can be improved as compared with the related art.

When the angular velocity detecting device is mounted on a detection object such as an automobile, the rotation center axis of the detection object does not always coincide with the center line CL of the support rod 2. If the movement of the object includes a rotation component about the center line CL of the support rod 2, the angular velocity of the object to be detected can be detected.

FIG. 12 is a graph showing the relationship between the angular velocity and the detection output. In general, an angular velocity detecting device for an automobile uses a single power supply of 5V. The angular velocity detecting device detects, for example, yawing of an automobile, and uses the detected output for controlling the attitude of the vehicle body. When the traveling direction of the running vehicle changes, the angular velocity detected by the angular velocity detecting device changes. When the detected angular velocity is zero, the angular velocity detector outputs a voltage value of a predetermined level. The voltage value output according to the yawing direction changes with reference to this predetermined level. Therefore, when the maximum angular velocity in the positive direction (Ω _max = 100 deg / sec) expected while the vehicle is running, 4 V close to 5 V is output, and when the maximum angular velocity in the negative direction is −Ω _max , 0 V is output. , It is possible to detect angular velocities of all magnitudes with a single power supply of 5V. Since the output of the angular velocity detecting device according to the present embodiment is offset-adjusted by the offset adjusting circuit 21 so that 2.5 V becomes the predetermined level, the angular velocity detecting device is driven by a single power supply of 5 V. be able to.

Further, the vibrator 102 of the present apparatus uses four vibrating reeds 4 to 7, which use only two vibrating reeds, each of which has an excitation electrode and a detection electrode. May be arranged, and quartz is used as the material of the piezoelectric crystal of the present device, but this may be replaced by a piezoelectric crystal such as LiTaO ₃ . Furthermore, PZT (lead zirconate titanate) or the like may be used as a material of the piezoelectric crystal, and the piezoelectric crystal may be attached to a metal or the like with electrodes interposed therebetween to form a resonator element.

Needless to say, the vibrator using only the two vibrating pieces has two metal columns 201,
A piezoelectric body made of a PZT piezoelectric crystal and an electrode may be attached to the side surface of the piezoelectric element 202. FIG. 13 shows the vibrating element when such a vibrator is cut along a plane perpendicular to the longitudinal direction of the element. 2 shows a cross section and wiring connected to each electrode. FIG. 3 shows only a cross section of a portion where the piezoelectric bodies 203 to 206 necessary for exciting the vibrating reed are attached. However, excitation and detection of the vibrating reed are only the difference between the piezoelectric effect and the inverse piezoelectric effect. Electrodes 203-mounted on the left and right surfaces of columns 201 and 202
206 are attached to the upper and lower surfaces, and these electrodes are connected to the Coriolis force detection terminals T5 and T6 shown in FIG.
An angular velocity detection device having the same function as the above embodiment can be provided.

In the angular velocity detecting device according to the above embodiment, the electrodes 4 provided on the piezoelectric crystal parts 4p and 5p
The first AC voltage applied between a to 4f and 5a to 5f is
The square wave voltage may be a sine wave voltage or the like as long as the vibration of the vibrating bars 4 and 5 is started and the vibration is maintained.

With the vibration of the piezoelectric crystal parts 4p and 5p, the electrodes 4a to 4e provided on the piezoelectric crystal parts 4p and 5p
A potential difference based on the piezoelectric effect is generated between 4f and 5a to 5f. In the angular velocity detecting device according to the above embodiment, the current flowing based on the potential difference is converted into a voltage, the converted voltage is amplified by the differential amplifier circuit 15 and output as the second AC voltage. , Waveform shaping, amplification or phase conversion may be performed, and the second AC voltage may be the potential difference itself.

Further, in the angular velocity detecting device according to the above embodiment, the signal based on the second AC voltage corresponds to the voltage component V _s based on the Coriolis force, the voltage component V _n based on the leakage vibration, and the excitation vibration. Voltage component _Vf
Voltage component V _f corresponding to the vibration of the voltage component V _n and excitation based on the leak vibration, if included either component,
The phase of the signal based on the second AC voltage changes. Also, by superimposing the AC voltage component serving as another reference voltage component V _s based on the Coriolis force, the phase of the superimposed voltage signal changes, by detecting the phase, detects the Coriolis force can do.

Further, in the angular velocity detecting device of the above embodiment, the first square wave voltage synchronously detected with the second square wave voltage is generated from a part of the AC voltage for exciting the piezoelectric crystal parts 4p and 5p. However, since the first square wave voltage only needs to be a reference for phase detection of the second square wave voltage, for example, the first square wave voltage may be generated from another reference clock.

As described above, the angular velocity detecting device according to the present embodiment is provided for the object to be detected which performs a rotating motion about a predetermined axis, and is intended for the device for detecting the angular velocity of the object to be detected. The first part 4 that vibrates and is mechanically coupled to the first part 4, and the force acting on the first part 4 depending on the velocity V 1 of the vibration of the first part 4 and the magnitude of the angular velocity Ω, A vibrator 102 having a second portion 6 capable of performing vibration including a vibration component along the direction V3, and an alternating current connected to the second portion 6 and corresponding to a vibration component based on the force of the second portion 6 An AC signal (FIG. 6D) including a signal component (FIG. 6 (e)) and another AC signal component (FIG. 6 (d) or (c))
(G)) detecting means 103a for detecting the phase.

According to the present apparatus, the amplitude of the AC signal (FIG. 6 (g)) changes but the phase does not change so much as the environment changes. The phase of the AC signal (FIG. 6 (g)) detected by the detecting means 103a corresponds to the angular velocity of the detected object. Therefore, according to the present device, the angular velocity can be accurately detected even when the environment changes.

Further, the first portion 4 is formed by applying an AC voltage (FIG. 6A) to the first piezoelectric crystal portion 4p made of a piezoelectric crystal so that the first piezoelectric crystal portion 4p is oriented in a predetermined direction. It has at least two electrodes 4a and 4b provided on the first piezoelectric crystal part 4p so as to vibrate along the (X-axis direction), and the second part 6 is made of a piezoelectric crystal. 1
A second piezoelectric crystal part 6p mechanically coupled to the piezoelectric crystal part 4p, and at least two other electrodes 6a and 6c provided on the second piezoelectric crystal part 6p;
The AC signal whose phase is detected by the signal is a signal corresponding to the potential difference between the other electrodes 6a and 6c (FIG. 6).
(F)) or a signal in which another AC signal component (FIG. 6 (c)) is superimposed on this signal (FIG. 6 (f)).

According to this device, the detecting means 103a detects the phase of the AC signal (FIG. 6 (g)) using a signal based on the piezoelectric effect of the second piezoelectric crystal part. Even when the temperature characteristics of the first and second piezoelectric crystal portions change, the phase of the AC signal (FIG. 6 (g)) does not change much. Therefore, according to the present device, the angular velocity can be accurately detected even when the environment changes.

The detecting means 103a is provided with a comparator 17 for generating a square wave voltage (FIG. 6 (h)) from the AC signal (FIG. 6 (g)), and the square wave voltage is a predetermined square wave voltage (FIG. 6 (g)). 6
It is preferable to perform synchronous detection with (i)). The AC signal (FIG. 6 (g)) is converted into a square wave voltage by the comparator 17. This square wave voltage (FIG. 6 (h)) is synchronously detected with a predetermined square wave voltage (FIG. 6 (i)) to output a signal containing only phase information of the AC signal (FIG. 6 (g)). I do. This phase information corresponds to the angular velocity of the object to be detected. Therefore, even if the amplitude of the AC signal (FIG. 6 (g)) changes,
The detected angular velocity of the detected object does not change.

Further, the present apparatus is different from the above-mentioned other electrodes 6a, 6
Mixer circuit 1 that superimposes another AC signal component (FIG. 6 (c)) on a signal (FIG. 6 (f)) corresponding to the potential difference between c and c.
6, the amplitude of the another AC signal component (FIG. 6 (c)) is larger than the amplitude of the signal (FIG. 6 (f)) corresponding to the potential difference between the other electrodes 6a and 6c. preferable. In this case, the mixer circuit 16 superimposes a signal having a large amplitude on the signal (FIG. 6F) as the another AC signal component (FIG. 6C), so that the AC signal to be synchronously detected is stabilized. However, the detection accuracy of the finally detected angular velocity can be improved.

[0117]

As described above, according to the angular velocity detecting device according to the present invention, the amplitude of the AC signal including the AC signal component corresponding to the vibration component of the second portion changes due to a change in the environment. Does not change much. The phase of the AC signal depends on the magnitude of the angular velocity of the object. Since the detection means detects the phase of the AC signal, the detection accuracy of the detected angular velocity can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of an angular velocity detecting device according to an embodiment of the present invention.

FIG. 2 is a sectional view of the vibrator shown in FIG. 1 taken along the line AA.

FIG. 3 is a sectional view of the vibrator shown in FIG. 1 taken along the line BB.

FIG. 4 is a sectional view of the resonator element shown in FIG. 1 taken along the line CC.

FIG. 5 is a block diagram showing a system of the angular velocity detection device according to the embodiment of the present invention.

FIG. 6 is a diagram showing a voltage waveform in the angular velocity detecting device.

FIG. 7 is a diagram showing a frequency characteristic of a Q value of a resonator element.

FIG. 8 is a diagram showing the movement of the position of the center of gravity due to the leakage vibration of the vibrating reed broken down into components.

FIG. 9 is a diagram showing the motion of the position of the center of gravity of the resonator element.

FIG. 10 is a diagram showing the amplitude dependence of the resonator element of the output voltage of the angular velocity detection device according to the embodiment.

FIG. 11 is a diagram showing the amplitude dependency of a resonator element of the output voltage of a comparative angular velocity detecting device.

FIG. 12 is a diagram showing a relationship between an angular velocity and an output voltage.

FIG. 13 is an end view of a cross section of a vibrator of another angular velocity detecting device.

[Explanation of symbols]

4p: first piezoelectric crystal part, 4a, 4b: electrode, 6p: second piezoelectric crystal part, 6a, 6c: another electrode, 102: vibrator, 103a: detection circuit, 17: comparator.

Claims (3)

[Claims] 1. An angular velocity detecting device provided on an object to be detected which makes a rotating motion about a predetermined axis and detecting an angular velocity of the object to be detected, wherein the vibrating first portion and the first portion are mechanically connected to each other. Combine
A second portion capable of performing a vibration including a vibration component along a direction of the force by a force acting on the first portion depending on a speed of vibration of the first portion and a magnitude of the angular velocity; A vibrator, and detecting means connected to the second portion and detecting a phase of an AC signal including an AC signal component corresponding to the vibration component based on the force of the second portion and another AC signal component. An angular velocity detection device, comprising: 2. The angular velocity detecting device according to claim 1, wherein the first portion is formed by applying a first piezoelectric crystal portion made of a piezoelectric crystal and an AC voltage to the first piezoelectric crystal portion. And at least two electrodes provided on the first piezoelectric crystal part so that the first part vibrates along a predetermined direction. The second part is made of a piezoelectric crystal, and the first piezoelectric crystal part A second piezoelectric crystal portion mechanically coupled to the second piezoelectric crystal portion, and at least two other electrodes provided on the second piezoelectric crystal portion. The AC signal whose phase is detected by the detection unit is An angular velocity detection device, wherein the signal is a signal corresponding to a potential difference between the other electrodes or a signal in which the another AC signal component is superimposed on the signal. 3. The angular velocity detecting device according to claim 1, wherein said detecting means includes a comparator for generating a square wave voltage from said AC signal, and wherein said square wave voltage is a predetermined square wave voltage. Angular velocity detection device, wherein the angular velocity is detected synchronously.