JPH08122080A - Vibrating gyro and correcting device - Google Patents

Abstract

PURPOSE: To provide a vibrating gyro in which unnecessary vibration is not detected in the state that an angular velocity is not applied to a vibrator. CONSTITUTION: The vibrating gyro comprises at least a vibrating gyro body having displacement detecting electro-mechanical energy transducers 7, 8 which excite the vibration of exciting mode at a vibrator by inputting an exciting signal VIN to exciting means 6 and outputs the vibration of a detecting mode by the displacement of the vibrator based on an angular velocity in a reverse phase state, and subtracting means 13 for subtracting two signals of reverse phases detected by the transducers 7, 8. The gyro further comprises a signal processing means for outputting the detecting signal of the angular velocity component based on the signal fed via the means 13, and an unnecessary vibration removing mean 11 for superposing signals adjustable in the phases on the transducers 7, 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration gyro and a correction device for correcting an angular displacement caused by an angular velocity based on a detection signal of the vibration gyro.

[0002]

2. Description of the Related Art A vibrating gyro is known as one of means for detecting an angular velocity. It vibrates an object based on the principle that when an angular velocity is applied to an object having velocity, Coriolis force is generated. Is applied to give a velocity, and the Coriolis force generated when an angular velocity is applied to this object is received by the spring system, and the Coriolis force proportional to the input angular velocity is detected as the displacement of the spring system, and the angular velocity applied to the object is detected. Is to detect.

FIG. 10 is a schematic view of a vibration gyro proposed by the applicant of the present invention as a vibration gyro of a detection type that detects angular velocities around two axes orthogonal to each other.

In this vibrating gyroscope, when an AC voltage V _Tin that substantially matches the torsional natural frequency of the vibrator A is applied to a part of the piezoelectric element 3 of the vibrator A made of metal, the vibrator A twists. Vibration occurs.

When an angular velocity around the x-axis or the y-axis is applied to the vibrator A, the Coriolis force described above causes zx to occur.
Bending vibration in a plane or in a zy plane is generated in the vibrator A, and the piezoelectric element for detecting the strain due to each bending vibration is provided with a signal component according to the value of the angular velocity applied to the vibrator A. An AC voltage V _BX or V _BY containing the voltage is generated.

Since both of these output signals are AM waves in which the frequency of the angular velocity is superimposed on the torsional excitation frequency component, these both output signals are amplified (modulated) by the first amplifier 19 and the second amplifier 20, respectively. After that, the first detector 21 and the second detector 22 respectively detect (demodulate), and the first detector 21 outputs a bending signal in the x direction, which is a signal component proportional to the angular velocity, and the second detector 21 A bending signal in the y direction, which is a signal component proportional to the angular velocity, is output from the detector 22. At this time, the torsion signal V _T from the piezoelectric element for detecting torsional vibration provided in the vibrator A is converted into a synchronization amplifier. The synchronous detection signals Ref whose phases have been adjusted by the phase shifter 24 after amplification at 23 are output to the first detector 21 and the second detector 22, respectively, and the above-described demodulation operation is performed.

The synchronous detection signal Ref is applied to the piezoelectric element for generating torsional vibration as a vibration input V _Tin due to self-excited oscillation.
Used as. Further, 4 is a support rod that supports the vibrator A, and 5 is a support plate that forms a base on which the support rod 4 is attached.

[0008]

However, in the conventional vibration gyroscope described above, when torsional vibration is excited in the vibrator A, bending vibration is generated in the vibrator A by the applied torsional vibration. Excited or excited torsional vibration is detected by the bending vibration detection piezoelectric element, that is, the angular velocity detection piezoelectric element, and the detection voltages V _BX and V _BY are generated even when the angular velocity is not actually applied. There were times when it happened.

A first object of the present invention according to the present application is to provide a vibration gyro in which unnecessary vibration is not detected in a state where an angular velocity is not applied to the vibrator.

A second object of the present invention is to provide a correction device for correcting an error caused by an angular velocity (angular displacement) by using a vibrating gyroscope realizing the object of the first invention. Especially.

[0011]

A first configuration for achieving the object of the first invention according to the present application is to vibrate a vibrator by inputting a vibration signal as described in claim 1. A vibrating gyro main body having an exciter for exciting mode vibration, and two displacement-detection electro-mechanical energy conversion elements for taking out detection mode vibration due to displacement of the vibrator based on angular velocity in an antiphase state; Electricity for detecting the displacement
At least a subtraction unit for subtracting two signals of opposite phases detected by the mechanical energy conversion element, a signal processing unit for extracting a detection signal of an angular velocity component based on the signal passed through the subtraction unit, and the displacement detection electric device A vibration gyro, comprising: an unnecessary vibration removing unit that superimposes a signal whose mutual phase is adjustable on a signal from the mechanical energy conversion element.

In this structure, when the angular velocity is not applied in a state where the vibration mode is excited, when unnecessary vibration is detected in the electric-mechanical energy conversion element for displacement detection,
The two unnecessary signals are in a state where their phases are substantially reversed.

Then, the unnecessary vibration removing means applies, for example, a vibration signal to the electromechanical energy conversion element for displacement detection through some impedance circuit, and superimposes an unnecessary signal on this signal. In this state, there is an unnecessary signal on the signal, and when attention is focused on the point where the unnecessary signal is on the basis, the two superimposed signals have a phase shift.

Therefore, if the impedance circuit for adjusting the phases of the two excitation signals applied to the electromechanical energy conversion element for displacement detection is a variable resistor, for example,
A phase shift occurs between the two, and as a result, the phases of the two superimposed signals coincide with each other. When the two superimposed signals are subtracted by the subtracting means, the output becomes 0, and unnecessary vibration is removed.

A second configuration for realizing the first invention according to the present application is, as described in claim 2, in claim 1.
A vibrating gyro is characterized in that a pair of an electro-mechanical energy conversion element for displacement detection and a signal processing means is provided as one set, and two sets are provided so as to correspond to two different axes of a vibrator.

With this structure, the angular velocity around the two axes can be detected by one vibrator without detecting unnecessary vibration.

A third configuration for achieving the object of the first invention according to the present application is, as described in claim 3, in claim 1, in which the vibration mode and the detection mode have different amplitudes in these modes. A vibrating gyro is characterized in that there are two vibrating modes in which the vibrating directions in a large portion are components having two axial directions that are orthogonal to each other.

In this configuration, for example, the central axis of the vibrator can be a portion where the amplitude of the vibration and detection modes is large, and the piezoelectric element or the like for detection can be provided in axial symmetry.

A fourth structure for realizing the object of the first invention according to the present application is, as described in claim 4, in claim 2, in which the vibration mode and the two detection modes are of these modes. The vibration gyro is characterized in that there are three vibration modes having components in which the vibration directions in a portion with a large amplitude are directed in three axial directions orthogonal to each other.

With this structure, the same operation and effect as those of the above-described third structure can be achieved with a vibrating gyroscope capable of detecting an angular velocity around two axes.

According to a fifth configuration for achieving the object of the first invention according to the present application, as described in claim 5, in the vibration mode and the detection mode in claim 1 or 3, the vibration order is different. Equally, the vibration gyro is characterized in that the vibration mode is bending vibration and the detection mode is bending vibration orthogonal to the bending vibration of the vibration mode.

In this configuration, since both the vibration mode and the detection mode are bending vibrations, the structure of the electro-mechanical energy conversion element for vibration and the electro-mechanical energy conversion element for detection is simplified to reduce Coriolis Vibration due to force can be detected.

A sixth configuration for achieving the object of the first invention according to the present application is, as described in claim 6, in claim 2 or 4, the vibration mode and the two detection modes are vibration modes. The vibration gyro is characterized in that the vibration modes are equal, the vibration mode is torsional vibration, the one detection mode is bending vibration, and the other detection mode is bending vibration in a direction orthogonal to the one detection mode.

With this structure, the same effect as that of the fifth structure can be applied to the angular velocity detection around the two axes.

A seventh structure for realizing the object of the first invention according to the present application is characterized in that, in claim 5 or 6, the order of vibration is 1 as described in claim 7. Vibrating gyro.

In this configuration, since the vibration and the detection are performed by using the primary vibration, the angular velocity at a relatively low frequency can be detected, and for example, the camera shake of the camera can be detected with high accuracy.

An eighth structure for achieving the object of the first invention according to the present application is, as described in claim 8, claim 3,
The vibration gyro is characterized in that the natural frequencies of the vibrations in the modes 4, 5, or 6 are substantially the same.

With this configuration, since the vibration of each mode substantially matches the natural frequency of the system of that mode, vibration and detection can be performed in a substantially resonant state, and power can be saved.

A ninth structure for achieving the object of the first invention according to the present application is, as described in claim 9, in claim 2 or 4, wherein the vibration mode is longitudinal vibration and the two detection modes are The vibration gyro is characterized by bending vibration.

With this configuration, it is possible to use vibrations that are easy to handle, such as longitudinal vibration and bending vibration.

A tenth structure for realizing the object of the first invention according to the present application is, as described in claim 10, claim 1
In any one of claims 9 to 9, the unnecessary vibration eliminating means for superimposing a signal capable of adjusting the mutual phase shift on the signal from the electromechanical energy conversion element for displacement detection generates vibration in the vibration mode. The vibration gyro is also applied to two electro-mechanical energy conversion elements for detecting the displacement of the detection mode via the adjustable impedance.

In this structure, since the unnecessary vibration eliminating means superimposes the unnecessary vibration on the vibration signal, the unnecessary vibration can be removed with a simple structure without affecting the detection of the displacement.

The eleventh structure for achieving the object of the first invention according to the present application is, as described in claim 11, claim 1
At 0, the adjustable impedance is in a vibrating gyro characterized by a variable resistance.

With this structure, the impedance can be adjusted by a simple member called the variable resistance, and the adjustment work can be performed only by operating the variable resistance.

According to a twelfth aspect of the present invention, a configuration for achieving the object of the second invention is based on the detection signal of the vibration gyroscope according to any one of the first to eleventh aspects. A correction device is characterized by correcting an angular displacement error caused by an angular velocity.

With this configuration, the correction operation of each displacement error is not erroneously executed when the angular velocity is not applied.

[0037]

【Example】

(First Embodiment) FIG. 1 is a block diagram of a schematic configuration of a vibrating gyroscope showing a first embodiment of the present invention, showing a vibrating gyroscope for detecting an angular velocity around one axis of a vibrator.

The vibrator of this embodiment has a piezoelectric element for vibration (PZT) 6 for vibration mode, a first piezoelectric element for detection (PZT) 7 for detection mode, and a detection mode between vibration elastic bodies. The second detection piezoelectric element 7 and the second detection piezoelectric element 8 sandwich a second detection (PZT) 8 for use in mechanical-electrical energy conversion function for detecting an angular velocity about the same axis. And is provided at a position where the vibration generated by the Coriolis force generated by the angular velocity is detected in the opposite phase. That is, the first detecting piezoelectric element 7 and the second detecting piezoelectric element 8 are arranged so that the signs of the detected voltages are opposite and the magnitudes thereof are the same.

Reference numeral 10 is a transmitting / phase shifting circuit used for excitation, 11 and 12 are variable resistors, 13 is an amplifying / subtracting circuit, 1
_{Reference numeral} 4 is a synchronous detection circuit, 15 is a low-pass filter that outputs an angular velocity signal V _XOUT , D is an angular velocity correction system that controls vibration of a still camera, a video camera, or an automobile. The operation of these circuits will be described later.

Here, the vibration mode is n ₄ (n ₄
= Positive integer) Assuming the next torsional vibration, the detection mode is n
₄ (n ₄ = positive integer) If one of the following bending vibrations, for example, the axial direction of the vibrator is the Z axis and the two directions orthogonal to the Z axis are the X and Y directions, the vibration mode Can be torsional vibration around the Z axis, and the detection mode can be bending vibration in the X direction, for example.

Therefore, the first detection piezoelectric element 7 and the second
The detection voltages of the detection piezoelectric element 8 have opposite signs and the same magnitude.

A vibration mode detecting piezoelectric element (PZT) 9 is also sandwiched between the vibrating elastic bodies, and the detected vibration signal is output to the transmitting / phase shifting circuit 10 from the transmitting / phase shifting circuit 10. Of the oscillation output signal V _IN of the oscillation / phase-shift circuit 10 is generated through the variable resistor (R1) 11 while the self-excited oscillation circuit that outputs the oscillation output signal V _IN of The voltage is applied to the first detection piezoelectric element 7 and the second detection piezoelectric element 8.

That is, the voltages VX1 and VX2 applied to the first detection piezoelectric element 7 and the second detection piezoelectric element 8 are signals in which the unnecessary signal and the signal resulting from the vibration output signal V _IN are superimposed.

Although it seems that the detection mode is excited when a signal is applied to the first and second detection piezoelectric elements 7 and 8 which are the detection piezoelectric elements, the first detection piezoelectric element 7 and the second detection piezoelectric element 7 are detected.
Since the detection piezoelectric element 8 is provided at a position where the vibration is detected in the opposite phase, when the same signal is applied to the first detection piezoelectric element 7 and the second detection piezoelectric element 8, they are offset and excited. It will not be done.

Here, when the vibrator is vibrated by the above-mentioned self-excited oscillation circuit, an unnecessary signal is detected from the first detection piezoelectric element 7 and the second detection piezoelectric element 8 without applying the angular velocity. This unwanted signal may occur when the vibration of the excitation mode is excited in the vibrator, the vibration of the detection mode is excited by the vibration of the vibration, or the vibration of the vibration vibrates. This is because the piezoelectric elements 7 and 8 for detection detect.

The unnecessary signals detected by the first detecting piezoelectric element 7 and the second detecting piezoelectric element 8 are signals having a phase shift and having substantially the same magnitude, and their frequencies are in the vibration mode. Equal to the frequency of.

Therefore, when the output signals from the detection piezoelectric elements 7 and 8 are amplified by the amplification / subtraction circuit 13 so that their amplitudes are equalized and then subtracted, if the phases of both output signals are in phase, an angular velocity is added. In the state where the signal is not present, the signal V _X becomes almost 0, which means that the unnecessary signal is removed.

In the present embodiment, a variable resistor (R) is used as means for matching the output signals from both the detecting piezoelectric elements 7 and 8.
1) 11 is used. By changing the resistance value of the variable resistor 11, the first detection piezoelectric element 7 and the second detection piezoelectric element 8 can be provided without changing the frequency of the signal in the vibration mode. The phase of the applied vibration mode signal is changed so that the phases of both output signals VX1 and VX2 in which an unnecessary signal is superimposed on the vibration mode signal are matched. An adjustment method for matching the phases of the output signals VX1 and VX2 can be performed by adjusting the variable resistor 11 while watching the output waveform of the amplification / subtraction circuit 13.

It is to be noted that the phases of the output signals of the detection piezoelectric elements 7 and 8 are made to coincide with each other, that is, the phases of the vibration mode signals applied to the first and second detection piezoelectric elements 7 and 8 are shifted. As the means, as shown in FIG. 1B, an impedance Y other than the variable resistor can be used.

The vibration gyro thus adjusted is in a state in which unnecessary signals are removed by the amplifying / subtracting circuit 13 in a vibrating state due to torsional vibration, and when an angular velocity is added, the first detecting piezoelectric element is detected. 7 and the second detection piezoelectric element 8 generate AM waves with inverted phases, and when these AM waves are amplified / subtracted by the amplification / subtraction circuit 13, the output signal V _X is shown in FIG. 2B. Like

That is, the signal V _X1 output from the first detection piezoelectric element 7 and the signal V _X2 output from the second detection piezoelectric element 8 are shown in FIG. 2 (a) when the angular velocity is not applied.
As shown in (3), it is a wave of the frequency of the vibration of the excitation mode with a constant amplitude (unnecessary vibration is not shown), and the phases thereof match.

Then, when the angular velocity is applied, these waves are used as carrier waves, and the amplitude of each carrier wave becomes a modulation signal which is modulated by the angular velocity. The phase of both modulation signals is a phase shift between the first detection piezoelectric element 7 and the second detection piezoelectric element 8 (about 180 degrees).
The phase shift (about 180 °) occurs according to (°). Therefore, when the signal V _X1 modulated with the angular velocity and the signal V _X2 modulated with the angular velocity are subtracted by the amplifying / subtracting circuit 13, both the modulated signals are superposed and the amplitude is almost doubled.
As shown in (b) of, a waveform modulated at the angular velocity indicated by the broken line is obtained.

Next, the output signal V _X from the amplification / subtraction circuit 13 is converted into the reference signal V _REF obtained from the transmission phase shift circuit 10.
When the signal is demodulated by the synchronous detection circuit 14 which detects the signal using, and the high-frequency component is removed by the low-pass filter 15, the angular velocity signal V _XOUT is obtained. This angular velocity signal V
_XOUT is output to the angular velocity correction system D and is used for control of camera shake correction due to camera shake of a still camera or video camera, camera shake correction of an in-vehicle camera, and the like.

In FIG. 1A, the variable resistor (R2) 12 is for balancing the detection signals of the first and second detecting piezoelectric elements 7 and 8, and the resistor 12 is not always necessary. is not.

In this embodiment, torsional vibration is used as the vibration mode and bending vibration is used as the detection mode.
Although the angular velocity around the axis is detected, the angular velocity around one axis can be detected by the following combinations, and in this case also, unnecessary vibration can be eliminated by the circuit configuration shown in FIG. .

(1) Excitation mode is n ₁ (n ₁ = positive integer) Next longitudinal vibration, detection mode is n ₂ (n ₂ = positive integer)
One of the following bending vibrations.

(2) The excitation mode is the n ₅ (n ₅ = positive integer) next bending vibration, and the detection mode is the n ₅ (n ₅ = positive integer) next bending vibration, which is orthogonal to the excitation mode. vibration.

(Second Embodiment) FIG. 3 shows a second embodiment.

This embodiment relates to a vibrating gyroscope capable of detecting angular velocities around two axes. The detection circuit (detection piezoelectric elements 7 and 8 and variable resistor 1) in the first embodiment shown in FIG.
1 and 12, an amplification / subtraction circuit 13, a synchronous detection circuit 14, and a low-pass filter 15 are provided in parallel, and a self-excited oscillation circuit (excitation piezoelectric element 6, excitation mode detection piezoelectric element 9, oscillation / phase shift). The circuit 10) is shared.

As the vibration mode and the detection mode for detecting the angular velocity around the two axes, there are the following combinations, for example.

(1) Excitation mode is n ₁ (n ₁ = positive integer) Next longitudinal vibration, detection mode is n ₂ (n ₂ = positive integer)
Next bending vibration (bending vibration in two orthogonal axes).

(2) The vibration mode is the n ₄ (n ₄ = positive integer) next torsional vibration, and the detection mode is the n ₄ (n ₄ = positive integer) next bending vibration (bending in two orthogonal axes). vibration).

Various patterns are conceivable for the patterns of the piezoelectric element and the detecting piezoelectric element for applying or detecting such a mode of vibration.

(Third Embodiment) FIG. 4 shows a third embodiment.

In this embodiment, the vibration of the mode (2) shown in the second embodiment shown in FIG. 3 and the detection of the vibration mode, and 2
2 shows a piezoelectric element for detecting vibration around an axis.

Reference numeral 3A is a piezoelectric element capable of detecting bending vibrations in two directions orthogonal to each other, and a divided electrode film divided into four at 90 ° pitch is formed on one side of a piezoelectric body polarized so as to be displaced in the thickness direction. On the other surface side, a grounding whole surface electrode film is formed. Of the divided electrode films, a pair of divided electrode films facing the central axis are used for the first detection in a set of detection circuits. Piezoelectric element 7 (7 ′) and second detection piezoelectric element 8
(8 ′), one set of the first detection piezoelectric element 7
The signal V _X1 and the signal V _X2 are output from the second detection piezoelectric element 8 and
Are output, and the signals V _Y1 and V _Y2 are output from the other pair of the first detection piezoelectric element 7'and the second detection piezoelectric element 8 ', respectively.
And are output.

In this case, since the polarization direction of the piezoelectric body is the same as the thickness direction indicated by the arrow, when the bending vibration is excited in the vibrator by the Coriolis force generated by the angular velocity, it is reversed from the divided electrode films facing each other. The primary bending vibration of the phase will be detected. In addition, since the unnecessary vibration described above is also generated in the opposite phase, the phase of the superimposed vibration mode signal is shifted by the variable resistor 11 (11 '), and unnecessary vibration is erroneously detected as an angular velocity signal in the state where the angular velocity is not applied. This is prevented by the amplifying / subtracting circuit 13 (13 ').

Reference numeral 3B denotes a piezoelectric element that excites the first-order torsional vibration in the vibration mode and detects the vibration in the vibration mode. The piezoelectric body is subjected to a polarization process to displace in the direction around the Z axis, and one side Is a substantially plane C-shaped electrode film 3 for voltage application.
B1 is formed, a vibration mode detection electrode film 3B2 having a rectangular shape in a plane is formed in the radial direction, and a ground whole electrode film is formed on the other surface side.

Therefore, the electrode film 3B1 of the piezoelectric element 3B is
When a signal V _IN for vibration is applied to the piezoelectric element, the piezoelectric element causes relative sliding around the Z axis on both surface sides and excites torsional vibration in the vibrator. Then, the electrode film 3B2
From the detection signal V of the torsional vibration excited by the vibrator
_SENSOR is output.

(Fourth Embodiment) FIGS. 5 and 6 show a fourth embodiment.

In this embodiment, the vibration mode of (1) shown in the above-mentioned second embodiment is n ₁ (n ₁ = a positive integer), the next longitudinal vibration is n ₂ (n ₂₎ = Positive integer)
A vibrator having the following bending vibration (bending vibration in two orthogonal directions of axes) is shown.

The vibrator in each of the above-described embodiments employs a system in which the support rod is extended from the other surface side of the vibrating elastic body and the base is fixed to the extended end portion to support the vibrator. In this embodiment, the vibrator is supported by using the insulating substrate 16 sandwiched between the vibrating elastic bodies 1 and 2.

Reference numeral 3a denotes a piezoelectric element for detecting bending vibration in the biaxial directions which is polarized in the Z axis direction, and 3b is a piezoelectric element for exciting the longitudinal vibration for polarization which is polarized in the Z axis direction. It is an element, and is sandwiched between the vibrating elastic bodies 1 and 2 with the insulating substrate 16 sandwiched therebetween, and is fixed by screwing both vibrating elastic bodies 1 and 2 with screw portions 1a and 2a.

The vibrating piezoelectric element 3b has a substantially C-shaped planar voltage-applying electrode film and a detecting electrode film formed on one surface of the piezoelectric body as in the one surface of the piezoelectric element 3B of FIG. A full-scale electrode film for installation is formed on the surface side, the electrode pattern 16c formed on the back surface side of the insulating substrate 16 contacts the electrode film for voltage application, and the electrode pattern 16d contacts the electrode film for detection. . Further, the entire surface electrode film of the vibrating piezoelectric element 3b contacts the ground electrode plate 17 and is grounded.

If the electrodes 16c, 16d, 17 and the piezoelectric element 3b are in close contact with each other, no electrode film may be provided on the surface of the piezoelectric element 3b.

On the other hand, the detecting piezoelectric element 3a is in a state of being polarized so as to be displaced in the Z-axis direction with no electrode film formed on both surfaces, and is electrically connected to the vibrating elastic body 1 via the insulating plate 18. to be maintained in a non-conductive state, the contact pattern portion 16a ₁ of the electrode patterns 16a formed at a pitch of 90 degrees on the surface side of the insulating substrate 16, 'contact pattern portion 16a' of _first electrode patterns 16a, the electrode patterns 16b contact pattern portion 16b _1, as well as contact with ₁ 'contact pattern portion 16b' of the electrode patterns 16b, and so as to contact with the common pattern portion 16e of the ring shape formed in the central portion, the vibrator this configuration The principle by which the bending vibration formed in the above can be detected will be described below.

When the vibration signal V _IN is applied to the electrode pattern 16c, the piezoelectric element 3b expands and contracts in the Z-axis direction. If the frequency of the excitation signal V _IN is substantially equal to the natural longitudinal natural vibration frequency of the vibrator, the vibrator is shown in FIG. The primary longitudinal vibration,
That is, vibration of a mode occurs in which the vibrating elastic bodies 1 and 2 expand and contract in the Z-axis direction in opposite phases.

If the angular velocity ω about the Y-axis is applied to the vibrator, Coriolis forces of opposite phases are generated in the vibrating elastic bodies 1 and 2 in the X-axis direction, as indicated by the outlined arrows. In addition,
The frequency of this Coriolis force is substantially the same as the frequency of the excitation signal V _IN .

Here, the bending vibration is excited in the oscillator by the Coriolis force. Now, if the frequency of the vibration of the bending second mode in the XZ plane is close to the frequency of the Coriolis force, this mode is generated. Since the vibration directions of the vibrating elastic bodies 1 and 2 are in the opposite phase to the X-axis direction, vibration in the bending secondary mode as shown in FIG. 8 occurs in the vibrator.

Therefore, the magnitude of the applied angular velocity ω can be known by detecting the amplitude of this vibration. When an angular velocity around the X-axis is applied to the vibrator, bending 2 in the YZ plane is performed by the same principle as the above case.
The next mode occurs.

FIG. 8 shows the state of the vibrator in the XZ plane when the bending secondary mode is generated. In this case, the piezoelectric element for detection 3a indicated by hatching is sheared and deformed in the X-axis direction in FIG.

In order to detect such deformation by the piezoelectric element, (1) the charge in the X direction generated in the piezoelectric element polarized in the Z-axis direction is detected. (2) the piezoelectric polarized in the X-axis direction. Either of detecting the charge in the Z direction generated in the element can be applied.

In the present embodiment, the above method (1) is adopted. The detection principle of this method will be described with reference to FIG.

The detecting piezoelectric element 3a has the insulating substrate 16
Pattern portions 16a ₁ and 16a ′ on the pattern forming surface side of
₁ , 16b ₁ and 16b ′ ₁ and the common pattern portion 16e are in contact with each other. Specifically, on one surface side of the piezoelectric body, the common pattern portion 16e and each pattern portion 16a ₁ having a predetermined space on the outer peripheral side thereof. , 16a ′ ₁ , 16b ₁ , 16
b _'1 is in contact with. It should be noted that the pattern portions 16 facing each other
a ₁ and 16a ′ ₁ and the pattern portions 16b ₁ and 1 facing each other
6b ′ ₁ is orthogonal to that of 6b ′ ₁ .

Here, as shown in FIG. 9A, an electric field is not generated in the piezoelectric element 3a when the detecting piezoelectric element 3a is not sheared and deformed, but as shown in FIG. 9B. When shear deformation occurs, an electric field as indicated by a broken line is generated, and, for example, voltages V _X1 and V _X2 proportional to the amplitude of the bending secondary mode in the ZX plane are generated in the electrode patterns 16a and 16a ′. Similarly, voltages V _Y1 and V _Y2 proportional to the amplitude of the bending secondary mode in the ZY plane are generated in the electrode patterns 16b and 16b ′. Therefore, it is possible to detect the angular velocities on the two orthogonal axes.

Here, since the voltages of the pair of electrode patterns have opposite signs, the unnecessary signals can be removed by the amplifying / subtracting circuit as in the above-described embodiment, and the signals AM-modulated by the generation of the angular velocity are generated. Each velocity signal component can be extracted by demodulating with the synchronous detection circuit.

When the vibration mode is the longitudinal vibration and the detection mode is the bending vibration, the vibration mode order n ₁ and the detection mode vibration orders n ₂ and n ₃ are as follows.
n ₁ = first order, n ₂ = n ₃ = second order, or n ₁ = second order,
n ₂ = n ₃ = first order, or n ₁ = third order, n ₂ = n ₃ =
When the order of the excitation mode is odd, such as quadratic, the order of the detection mode is even, and conversely, when the order of the excitation mode is even, the order of the detection mode is odd.

This means that, as shown in FIG.
₁ = second order, and the case of n ₂ = 1 order, as shown in (b) of FIG. 11, n ₁ = 3-order and the case of n ₂ = Secondary as an example,
This is because the vibration mode vibration and the detection mode vibration waveform appear as similar waveforms.

In other words, the principle of this vibrating gyroscope is that when an angular velocity is applied to a vibrator excited by longitudinal vibration, the Coriolis force generated by the angular velocity about two axes orthogonal to the direction of longitudinal vibration causes two Since the bending vibration is excited, if the waveform of the longitudinal vibration and the waveform of the bending vibration are different, the vibration component generated by the Coriolis force cannot be regularly detected, and as a result, the angular velocity cannot be detected.

[0090]

According to the first aspect of the present invention, when the angular velocity is not applied in the state where the vibration mode is excited, and the unnecessary vibration is detected in the electric-mechanical energy conversion element for detecting displacement. However, unnecessary vibration can be eliminated.

According to the second aspect of the present invention, the angular velocity around the two axes can be detected by one vibrator without detecting unnecessary vibration.

According to the third aspect of the present invention, for example, the central axis of the vibrator can be a portion where the amplitude of the vibration and detection modes is large, and the piezoelectric element for detection and the like can be provided rotationally symmetrically. it can.

According to the invention described in claim 4, the same effect as that of the invention described in claim 3 can be exerted also in the vibration gyro which can detect the angular velocity around the two axes.

According to the invention described in claim 5, since the vibration mode and the detection mode are bending vibrations, the structure of the electric-mechanical energy conversion element for vibration and the electric-mechanical energy conversion element for detection is constituted. Can be simplified, and vibration due to Coriolis force can be detected.

According to the invention described in claim 6, the same operational effect as that of the invention described in claim 5 can be applied to the angular velocity detection around the two axes.

According to the invention described in claim 7, since the vibration and the detection are performed by using the primary vibration, it is possible to detect the angular velocity at a relatively low frequency, and for example, the camera shake of the camera can be detected with high accuracy. Can be detected.

According to the invention described in claim 8, since the vibration of each mode substantially coincides with the natural frequency of the system of the mode, vibration and detection can be performed in a substantially resonant state, and power saving is achieved. Can be achieved.

According to the ninth aspect of the invention, it is possible to use vibrations that are easy to handle, such as longitudinal vibration and bending vibration.

According to the tenth aspect of the present invention, since the unnecessary vibration eliminating means superimposes the unnecessary vibration on the excitation signal, the unnecessary vibration is removed without affecting the detection of the displacement with a simple structure. Removal can be achieved.

According to the eleventh aspect of the present invention, the impedance can be adjusted by a simple member called the variable resistor, and the adjustment work can be performed only by operating the variable resistor.

According to the twelfth aspect of the invention, the correction operation of each displacement error is not erroneously executed when the angular velocity is not applied.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention,
(A) shows the whole structure, (b) shows a modification.

2 is a waveform diagram showing modulation and demodulation in the embodiment of FIG.

FIG. 3 is a block diagram showing a second embodiment.

FIG. 4 is a perspective view of a piezoelectric element showing a third embodiment.

FIG. 5 is a sectional view of a vibrator according to a fourth embodiment.

FIG. 6 is an exploded perspective view of a vibrator according to a fourth embodiment.

FIG. 7 is a diagram showing a longitudinal vibration mode of a vibrator according to a fourth embodiment.

FIG. 8 is a diagram showing a bending vibration mode of a vibrator according to a fourth embodiment.

FIG. 9 is a diagram showing a bending vibration detection principle of the fourth embodiment.

FIG. 10 is a block diagram showing a configuration of a conventional vibrating gyro.

FIG. 11 is a waveform diagram showing the order relationship between the vibration in the excitation mode and the vibration in the detection mode in the present invention.

[Explanation of symbols]

 6 Piezoelectric element for vibration 7,8 Piezoelectric element for detection 9 Piezoelectric element for vibration mode detection 10 Oscillation / phase shift circuit 11,12 Variable resistance 13 Amplification / subtraction circuit 14 Synchronous detection circuit 15 Low-pass filter 16 Insulation substrate D Angular velocity correction System Y impedance

Claims (12)

[Claims] 1. A vibrating means for exciting a vibration in a vibration mode into a vibrator by inputting a vibration signal, and a vibration in a detection mode due to displacement of the vibrator based on an angular velocity are extracted in an antiphase state. A vibration gyro body having two electro-mechanical energy conversion elements for displacement detection, and at least subtraction means for subtracting two signals of opposite phases detected by the electro-mechanical energy conversion element for displacement detection. Signal processing means for extracting a detection signal of an angular velocity component based on the signal passed through the means, and unnecessary vibration eliminating means for superimposing a signal whose mutual phase can be adjusted on a signal from the electromechanical energy conversion element for detecting displacement. A vibrating gyro, which comprises: 2. The electric device for detecting displacement according to claim 1.
A set of a mechanical energy conversion element and a signal processing means,
A vibrating gyro, characterized in that two sets are provided corresponding to two different axes of the oscillator. 3. The vibrating mode and the detecting mode according to claim 1, wherein the vibrating modes and the detecting modes are two vibrating modes having components in which the vibrating directions of a portion where the amplitude of these modes is large are in two axial directions orthogonal to each other. Vibration gyro to be. 4. The vibration mode and the two detection modes according to claim 2, which are three vibration modes having components in which vibration directions in a portion having a large amplitude of these modes are directed in three axial directions orthogonal to each other. A vibrating gyro. 5. The vibration mode and the detection mode according to claim 1, wherein the vibration modes have the same vibration order, the vibration mode is the bending vibration, and the detection mode is the bending vibration orthogonal to the bending vibration of the vibration mode. A vibrating gyro that is characterized. 6. The vibration mode and the two detection modes according to claim 2, wherein the vibration modes have the same vibration order, the vibration mode is torsional vibration, one detection mode is bending vibration, and the other detection mode is the one. A vibration gyro, which is characterized by bending vibration in a direction orthogonal to the detection mode of. 7. The vibration gyro according to claim 5, wherein the order of vibration is 1. 8. The vibration gyro according to claim 3, 4, 5 or 6, wherein the natural frequencies of the vibrations of the respective modes are substantially the same. 9. The vibration gyro according to claim 2, wherein the vibration mode is longitudinal vibration and the two detection modes are bending vibration. 10. The unnecessary vibration removing means according to claim 1, wherein the signal from the electromechanical energy conversion element for displacement detection is superposed with a signal whose phase shift can be adjusted. A vibration gyro, characterized in that a vibration signal for generating vibration in a vibration mode is also applied to two electro-mechanical energy conversion elements for detecting a displacement in a detection mode via an adjustable impedance. . 11. The vibrating gyroscope according to claim 10, wherein the adjustable impedance is a variable resistance. 12. A correction device, which corrects an angular displacement error caused by an angular velocity based on the detection signal of the vibration gyro according to any one of claims 1 to 11.