JP2000329560A - Angular velocity sensor and its detection circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an angular velocity sensor by which an angular velocity can be detected with good efficiency even when a deviation is generated in the phase of an output signal due to the Coriolis force and in the phase of a signal to be used as the gate signal of a synchronous detection. SOLUTION: Since, by setting the inclination state of a vibrator 1 to an elliptical motion before an angular velicity is given, the null output of a detection means agrees with the phase of an output due to the Coriolis force, the output due to the Coriolis force can be detected by a detection signal itself. Consequently, since the phase of a null voltage does not differ from the phase of the output due to the Coriolis force, it is not required to set the null voltage at an apparent zero by using a differential circuit and to synchronously detect the null voltage by a driving signal or a signal for feedback.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor for detecting the magnitude of an angular velocity by detecting a Coriolis force acting in a direction perpendicular to the direction of motion of the moving object when the angular velocity is applied to the object. It relates to the detection circuit.

[0002]

2. Description of the Related Art An angular velocity sensor is widely used as an autonomous navigation sensor for a car navigation system and a camera shake prevention sensor for a video movie. Above all, a piezoelectric gyro using a piezoelectric body for driving a vibrator and detecting Coriolis force is widely used as a small and inexpensive angular velocity sensor. For example, see the document “Basics of Piezoelectric Gyroscope Sensor Technology”, Electronic Ceramics, October 1991, pp. 146-64. 27-35 discloses such a piezoelectric gyro.

FIG. 10 is a schematic block diagram showing the configuration of an angular velocity sensor comprising such a first conventional piezoelectric gyro.

[0004] In FIG. 10, a piezoelectric gyro part is shown in a plan view. Referring to FIG. 10, in a piezoelectric gyro, a vibrator 1 having a rectangular cross section is provided with a driving piezoelectric body 2.
A predetermined self-excited oscillation is performed in the x-axis direction by a self-excited oscillation circuit 30 using 0 and the feedback piezoelectric body 21. Then, when an angular velocity Ω about the z-axis is applied under such vibration,
Vibration is excited in the y-axis direction orthogonal to the self-excited vibration.
A voltage is generated in the detection piezoelectric bodies 22 and 23 by the axial vibration.

By passing these voltages through a differential circuit 31, a synchronous detection circuit 32, and a smoothing circuit 33, the angular velocity sensor outputs a DC voltage output proportional to the angular velocity Ω.

In the case of such a piezoelectric gyro, the voltage generated in the detecting piezoelectric members 22 and 23 by the Coriolis force coincides in phase with the drive signal of the self-excited oscillation circuit 30. By detecting the phase of the signal, only the signal due to the Coriolis force can be extracted.

However, when mechanical leakage coupling occurs between the vibration in the x-axis direction and the vibration in the y-axis direction of the vibrator 1, the vibrator 1 can operate even when no angular velocity is applied.
Vibration in the x-axis direction also causes vibration in the y-axis direction, which is output from the detecting piezoelectric bodies 22 and 23 as a null voltage.

When the summation of the detecting piezoelectric members 22 and 23 is performed, the null voltage can be apparently reduced to zero, but the voltage signal due to the Coriolis force when the angular velocity is applied is canceled out, and the detection becomes impossible. .

Therefore, when a null voltage is generated,
Using the fact that the phase of the voltage output from the feedback piezoelectric element 21 and the phase of the null voltage output from the detection piezoelectric element 22 or 23 match, the output of the feedback piezoelectric element 21 and the detection piezoelectric element 22 are used. Alternatively, by taking the differential with the output of 23, the null voltage can be apparently reduced to zero, and only the signal due to the Coriolis force is extracted by detecting the phase of the voltage signal due to the Coriolis force with the drive signal. The method has been taken.

A method for solving the problem of the null voltage described above is described in the document “Small Gyro and Its Application”, Journal of the Japan Society of Mechanical Engineers, November, 1993, pp. 14-17.

FIG. 11 is a schematic block diagram showing an example of the configuration of a piezoelectric gyro in the case where the cross section of the vibrator is triangular.

Referring to FIG. 11, a conventional piezoelectric gyro includes a vibrator 1 having a triangular cross section and a driving piezoelectric body 2.
A predetermined self-excited oscillation is performed in the x-axis direction by a self-excited oscillation circuit 30 using 4 and 25 and the feedback piezoelectric body 21.
Then, under such vibration, the angular velocity Ω around the z-axis
Is added, vibration is excited in the y-axis direction orthogonal to the self-excited oscillation.

Here, the voltage generated on the driving piezoelectric elements 24 and 25 which also serves as the piezoelectric element for detecting the vibration in the y-axis direction is passed through a differential circuit 31, a synchronous detection circuit 32 and a smoothing circuit 33. , And output as a DC voltage output proportional to the angular velocity Ω.

In this case, a voltage is generated in the driving piezoelectric members 24 and 25 also serving as the detecting piezoelectric members by vibration in the x-axis direction even when no angular velocity is applied. However, since the phases of the voltages match, the difference can be apparently reduced to zero.

In addition, when an angular velocity is applied, voltages are generated in opposite phases by the Coriolis force on the driving piezoelectric elements 24 and 25 which also serve as detecting piezoelectric elements.
By taking the difference between the two, it is possible to cancel the apparent null voltage and to detect only the voltage due to the Coriolis force by detecting the phase with the drive signal.

[0016]

In the first conventional piezoelectric gyro as shown in FIG. 10, when the null voltage is zero, only the output by the Coriolis force is output from the detecting piezoelectric body. By performing synchronous detection with the drive signal, the magnitude of the angular velocity can be detected by the magnitude of the detection output, and the directional component of the angular velocity can be detected by the sign of the detection output.

However, it is difficult to make the vibrator ideally a vibration state having a displacement component only in the x-axis direction, which is the driving direction, and if the null voltage is not canceled by any method,
Synchronous detection cannot extract only the output due to the Coriolis force.

Therefore, the null voltage is apparently reduced to zero by taking the differential from the feedback piezoelectric signal having the same or opposite phase.

However, it is necessary to exactly match the amplitudes of the signals input to the differential circuit, and the phase relationship of the signals input to the differential circuit may be the same if the vibration balance of the oscillator is lost. Alternatively, since the phase shifts from the opposite phase, the null voltage cannot be apparently reduced to zero, and there is a problem that only the output due to the Coriolis force cannot be extracted even with synchronous detection.

A second conventional piezoelectric gyro as shown in FIG. 11 obtains an apparent null voltage by taking a difference between outputs from two detecting piezoelectric bodies which also serve as driving piezoelectric bodies. Is set to zero. However, also in this case, it is necessary to exactly match the amplitudes of the two detection signals input to the differential circuit, and the phase relationship between the two detection signals input to the differential circuit depends on the vibrator. If the vibration balance is lost, the phase is shifted from the same phase, so that the null voltage cannot be apparently reduced to zero. Therefore, there is a problem that it is not always possible to extract only the output due to the Coriolis force even with synchronous detection.

The present invention has been made in order to solve such a problem, and an object of the present invention is to eliminate the necessity of making a null voltage seemingly zero by a differential circuit, and to realize a synchronous detection. It is an object of the present invention to provide an angular velocity sensor which does not need to use a signal other than the detection means.

[0022]

According to a first aspect of the present invention, there is provided an angular velocity sensor for driving a vibrator, a driving means for exciting the vibrator, and a feedback for detecting an excitation state and controlling an excitation operation of the driving means. A first detecting means, and a second detecting means for detecting a vibration component caused by Coriolis force corresponding to an angular velocity acting from outside with an axis parallel to the central axis of the vibrator as a central axis, wherein the angular velocity is an angular velocity sensor Before the vibration, the vibration of the vibrator excited by the driving means makes a circular motion or an elliptical motion in a plane orthogonal to the central axis of the vibrator.

The angular velocity sensor according to the second aspect is the first aspect.
In addition to the configuration of the angular velocity sensor described above, a signal conversion unit that generates an angular velocity detection signal proportional to a time average of the absolute value of the signal from the second detection unit based on the output signal of the second detection unit is further provided. Prepare.

According to a third aspect of the present invention, there is provided an angular velocity sensor.
In addition to the configuration of the angular velocity sensor described above, the second detection unit that detects a vibration component due to Coriolis force includes a piezoelectric body.

According to a fourth aspect of the present invention, there is provided an angular velocity sensor.
In addition to the configuration of the angular velocity sensor described above, the second detection means for detecting a vibration component due to Coriolis force is at least one permanent magnet provided at a free end of the vibrator and is induced by a change in position of the permanent magnet. And a coil for detecting an induced current.

According to the fifth aspect of the present invention, there is provided an angular velocity sensor according to the fourth aspect.
In addition to the configuration of the angular velocity sensor described above, the vibrator provided with at least one permanent magnet near the free end is a magnetic body magnetized in a direction orthogonal to the coil surface of the second detection means.

According to the sixth aspect of the present invention, there is provided an angular velocity sensor according to the fourth aspect.
Alternatively, in addition to the configuration of the angular velocity sensor described in 5, the coil included in the second detection means for detecting a vibration component caused by Coriolis force is rotatable while keeping the center axis and the coil surface parallel.

According to the seventh aspect of the present invention, there is provided an angular velocity sensor according to the first aspect.
In addition to the configuration of the angular velocity sensor according to any one of the first to sixth aspects, the driving unit that excites the vibrator includes a piezoelectric body.

The angular velocity sensor according to claim 8 is the first embodiment.
In addition to the configuration of the angular velocity sensor according to any one of (6) to (6), the driving unit for exciting the vibrator includes a coil.

The angular velocity sensor according to the ninth aspect is the third aspect.
In addition to the configuration of the angular velocity sensor described above, the phase of the output signal of the piezoelectric body included in the second detection unit that detects the vibration component due to the Coriolis force is the same or opposite to the phase of the drive signal of the drive unit. .

According to a tenth aspect of the present invention, in addition to the configuration of the angular velocity sensor according to any one of the fourth to sixth aspects, the output of the coil included in the second detecting means for detecting a vibration component due to Coriolis force is provided. The phase of the signal has a phase difference of 90 ° with respect to the phase of the drive signal of the drive means.

According to an eleventh aspect of the present invention, in addition to the configuration of the angular velocity sensor according to any one of the first to tenth aspects, the feedback first detecting means for detecting the excitation state includes a piezoelectric body. .

According to a twelfth aspect of the present invention, in addition to the configuration of the angular velocity sensor according to any one of the first to tenth aspects, the feedback first detecting means for detecting the excitation state includes a coil.

According to a thirteenth aspect of the present invention, in addition to the configuration of the angular velocity sensor according to the second aspect, the signal conversion means includes a detection means for generating a synchronous detection control signal based on an output signal of the second detection means. The control device further includes a synchronous detection unit that synchronously detects the output signal of the second detection unit and generates an angular velocity detection signal based on the synchronous detection control unit.

According to a fourteenth aspect of the present invention, in addition to the configuration of the angular velocity sensor of the second aspect, the signal conversion means receives an output signal of the second detection means and performs envelope detection to detect the angular velocity. An envelope detection means for generating a signal is included.

According to a fifteenth aspect of the present invention, there is provided a detection circuit for an angular velocity sensor, comprising: a vibrator; driving means for exciting the vibrator; first detecting means for feedback for detecting an excited state; A second detecting means for detecting a vibration component caused by Coriolis force according to an angular velocity acting from the outside with a central axis as a central axis, the second circuit comprising:
A detection control means for generating a synchronous detection control signal based on the output signal of the detection means, and a synchronous detection means for synchronously detecting the output signal of the second detection means based on the synchronous detection control means.

According to a sixteenth aspect of the present invention, there is provided a detection circuit for an angular velocity sensor, comprising: a vibrator; driving means for exciting the vibrator; first detecting means for feedback for detecting an excited state; A second detecting means for detecting a vibration component caused by Coriolis force according to an angular velocity acting from the outside with a central axis as a central axis, the second circuit comprising:
And an envelope detection circuit for inputting a signal from the detecting means.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS.

[Embodiment 1] FIG. 1 is a perspective view of an angular velocity sensor unit 10 according to Embodiment 1 of the present invention, and FIG. 2 is a plan view and a block diagram thereof. 1 and 2, the angular velocity sensor unit 10 includes a vibrator 1, a driving piezoelectric body 2, a feedback piezoelectric body 3, and a detecting piezoelectric body 4.

The vibrator 1 can be made of a constant elastic metal (manufactured by Sumitomo Special Metals, EL-3) so that the vibration characteristics do not change with changes in the ambient temperature. It is also possible to use a constant elastic metal such as another Elinvar alloy. As the piezoelectric bodies 2, 3, and 4, PZT (Pb (Zr, Ti)
O ₃ ) can be used, and piezoelectric ceramics such as BaTiO ₃ can also be used.

When a piezoelectric body is used as the vibrator 1, an arrangement may be made in which electrodes are provided instead of the piezoelectric bodies 2, 3, and 4.

In the first embodiment, the vibrator 1 is excited by the driving piezoelectric body 2. At this time, if the resonance frequency in the x-axis direction and the resonance frequency in the y-axis direction of the vibrator are close to each other, mechanical coupling occurs in the vibrator in vibration modes in the x-axis direction and the y-axis direction. The vibration state of the elliptical motion as shown by the arrow DA of FIG. That is, even if the vibrator 1 is driven in the x direction, if the above mechanical coupling occurs, the energy of the vibration vibrating in the x direction becomes y.
It leaks to generate vibration in the direction. As long as such a mechanical coupling exists, energy leaks into vibration in the y direction, so that the motion of the vibrator 1 is circular or elliptical. This mechanical coupling tends to increase as the resonance frequency in the x and y directions approaches.

In this embodiment, for example, the difference between the resonance frequency in the x-axis direction and the resonance frequency in the y-axis direction is 2 Hz,
The driving piezoelectric body 2 is driven at a resonance frequency in the x-axis direction.

However, the resonance frequency in the x-axis direction and the resonance frequency in the y-axis direction of the vibrator 1 and the driving frequency of the driving piezoelectric element 2 are set so that the driving vibration state is a circular motion or an elliptical motion. For example, in a vibrator having a resonance frequency of about 2 to 8 kHz, if the difference between the resonance frequency in the x-axis direction and the resonance frequency in the y-axis direction is adjusted to a range of 10 Hz or less, the vibrator moves in a circular motion. Alternatively, it can be vibrated by elliptical motion. With this setting, the null output due to the circular motion or the elliptical motion becomes a sufficiently detectable level, and the synchronous detection described later becomes possible.

Conventionally, efforts have been made to reduce such a mechanical coupling. In the present invention, however, such a mechanical coupling is used for detecting an angular velocity as described below. I do.

Also, by driving the driving piezoelectric body 2 at the resonance frequency in the y-axis direction, the vibrator can be excited in a circular or elliptical vibration state. In this case, the resonance frequency in the x-axis direction is increased. And the difference between the resonance frequencies in the y-axis direction may be 10 Hz or more.

This is because, by driving the driving direction (x-direction) at the resonance frequency in the y-direction and vibrating in the x-direction at a frequency (resonance frequency in the y-direction) that is originally very easy to vibrate in the y-direction, x , Even if the resonance frequencies in the y direction are far apart,
This is because vibration in the y direction is easily generated. Originally, x
As a result, the vibrator 1 has a circular or elliptical motion even when the difference Δf between the resonance frequencies is large.

That is, in any method, in the initial state before the angular velocity is applied to the angular velocity sensor, the vibrator 1 has already performed a circular motion or an elliptical motion.

The feedback piezoelectric element 3 outputs a feedback signal for driving the vibrator at a desired frequency by a control circuit in the transmission circuit 30.

When an angular velocity Ω about the z-axis is applied, Coriolis force proportional to the angular velocity Ω is generated in a direction orthogonal to the direction of motion of the vibrator. As a result, in the vibrator 1, the radii of the major axis and the minor axis of the elliptical motion increase or decrease in the direction of the angular velocity. Then, since the signal output from the detecting piezoelectric element 4 is large or small, the angular velocity Ω can be detected.

FIG. 3 is a timing chart for explaining the operation of gate circuit 34 and synchronous detection circuit 32 shown in FIG.

The gate circuit 34 receives the signal DS from the detecting piezoelectric element 4 and generates a binarized gate signal GS1 according to the positive level of the signal DS.
Gate signal GS binarized according to the negative level of
Generate 2.

In the synchronous detection circuit 32, the signal DS is
The signal DM1 is generated by detecting the signal DS, and the signal DM2 is generated by detecting the signal DS by the signal GS2. The synchronous detection circuit 32 outputs the signal D
The difference signal between M1 and DM2 is output to the smoothing circuit 33 as a signal after synchronous detection.

FIG. 4 is a timing chart for explaining the operation of the angular velocity sensor according to the first embodiment.
FIG. 4A shows waveforms at each part of the detection circuit during non-rotation, and FIG.

In the case of the vibrator 1 vibrating in an elliptical motion in the direction of arrow A in FIG. 2, the drive signal during non-rotation, the piezoelectric signal for feedback, and the null voltage signal of the piezoelectric element for detection are respectively shown in FIG.
(A) of (a), (2), and (3).

In the present embodiment, since the vibrator 1 performs an elliptical motion, the null voltage signal of the detecting piezoelectric element has the same phase as the drive signal.

Next, when the angular velocity sensor 10 rotates, the output due to the Coriolis force is generated in the same phase as the null voltage signal of the detecting piezoelectric element as shown in (3) of FIG. 4 (b), the detection piezoelectric signal DS is input to the gate circuit 34, and synchronous detection is performed by the synchronous detection circuit 32 using the gate signals GS1 and GS2 from the gate circuit 34. The angular velocity can be detected by performing smoothing by the smoothing circuit 33.

As described above, when the vibrator 1 is in an elliptical motion as shown in the present embodiment, the output phase of the null voltage of the detecting piezoelectric body and the phase of the output due to the Coriolis force coincide with each other. Thus, it is not necessary to make the apparent null voltage zero by the differential circuit. In addition, since there is no need to perform synchronous detection using a drive signal or a feedback piezoelectric signal, a phase shift does not occur during synchronous detection, and Coriolis force can be detected efficiently.

In this embodiment, the vibration state of the vibrator 1 is an elliptical motion. However, even when the vibration state is a circular motion, the angular velocity can be detected by a similar detection method. .

In this embodiment, a cantilevered vibrator is used as the vibrator 1, but a vibrator of a tuning fork type, an H type, or the like may be used.

In the present embodiment, a piezoelectric body is used as the driving means. However, a method is employed in which a magnet and a driving coil are provided on the side of the vibrator on the side of the driving vibration, and the vibrator is excited by electromagnetic induction. You can also.

Further, in the present embodiment, the piezoelectric body 3 is used as the feedback detecting means. However, a combination of a permanent magnet fixed to the vibrator and a coil opposed to the permanent magnet is used as the feedback detecting means. It is also possible.

[Second Embodiment] FIG. 5 shows a plan view and a block diagram of an angular velocity sensor according to a second embodiment of the present invention. In the present embodiment, except for the configuration of the detection circuit, the excitation method and the vibration state of the vibrator 1 are the same as those in the first embodiment. Do not repeat.

In the second embodiment, the amplitude of the detection signal is detected by using the envelope detection circuit 35 instead of performing synchronous detection of the detection signal with the gate signal from the gate circuit.

Since the vibrator 1 makes an elliptical motion, the output of the null voltage of the detecting piezoelectric element and the phase of the output due to the Coriolis force coincide with each other. And it is not necessary to extract only the output component due to the Coriolis force by synchronous detection.

Therefore, the Coriolis force can be efficiently detected with a simple circuit configuration using the envelope detection circuit 35 to detect the amplitude of the detection signal.

In the present embodiment, the vibrating state of the vibrator 1 is an elliptical motion.
It is possible to detect the angular velocity by a similar detection method.

In this embodiment, a cantilevered vibrator is used as the vibrator 1, but a vibrator of a tuning fork type, an H type, or the like can also be suitably used. In this embodiment, the piezoelectric body is used as the driving means. However, a method may be adopted in which a magnet and a driving coil are provided on the side of the vibrator on the driving vibration side, and the vibrator is excited by electromagnetic induction.

In the present embodiment, the piezoelectric body 3 is used as the feedback detecting means. However, a coil may be used as the feedback detecting means.

[Third Embodiment] FIG. 6 is a perspective view of an angular velocity sensor unit 12 according to a third embodiment of the present invention. further,
FIG. 7 shows a plan view and a block diagram of an angular velocity sensor according to Embodiment 3 of the present invention.

Referring to FIG. 6 and FIG. 7, the angular velocity sensor section 12 includes a vibrator 1, a driving piezoelectric body 2, a feedback piezoelectric body 3, a permanent magnet 4, and a detection coil 5.

As the permanent magnet 4, for example, a rare earth magnet (manufactured by Sumitomo Special Metals, NEOMAX) can be used, and a samarium cobalt magnet (SmCo magnet) or a permanent magnet other than the rare earth magnet can be used. .

The detection coil 5 may be, for example, a copper wire having a wire diameter of 20 μm, which is wound 100 turns in a circle with a diameter of 5 mm.
The shape and the number of turns of the coil may be appropriately selected according to the detection sensitivity, cost, and the like.

In the present embodiment, the center of the detection coil 5 is hollow, but the sensitivity of the detection coil 5 can be improved by providing a core made of a high magnetic permeability material such as Sendust or Permalloy.

In the present embodiment, the detection coil 5
Although the magnetic pole of the permanent magnet 4 on the surface opposite to the N pole is an N pole, this may be an S pole.

The distance between the detection coil 5 and the permanent magnet 4 is
For example, it can be 0.1 mm, but 0.05 mm
The range may be about 3 mm.

In the present embodiment, a permanent magnet having a square pillar shape is used, but other shapes such as a columnar shape and a polygonal pillar shape may be used.

In this embodiment, except that the permanent magnet 4 and the detection coil 5 are provided as described above,
Excitation method and vibration state of vibrator 1 are also the same as those in the first embodiment, and therefore, the same portions are denoted by the same reference characters and description thereof will not be repeated.

When an angular velocity Ω about the z-axis is applied to the angular velocity sensor, Coriolis force proportional to the angular velocity Ω is generated in a direction orthogonal to the direction of motion of the vibrator. As a result, the vibrator 1
In, the radii of the major axis and the minor axis of the elliptical motion are larger or smaller depending on the direction of the angular velocity. Then, since the signal output from the detection coil 5 is large or small, it is possible to detect the angular velocity Ω.

When the permanent magnet 4 is excited, it also has an x-axis component, so strictly speaking, the magnetic flux passing through the detection coil 5 may be changed by the vibration component in the x-axis direction. However, such a possibility is negligible because it is very small as compared with the change in magnetic flux due to the vibration component in the y-axis direction.

FIG. 8 is a timing chart for explaining the operation of the angular velocity sensor according to the third embodiment of the present invention. FIG. 8 (a) shows the detection at the time of no rotation, and FIG. 8 (b) shows the detection at the time of rotation. The waveform at each part of the circuit is shown.

In the case of the vibrator 1 vibrating in an elliptical motion in the direction of the arrow DA in FIG. 7, the drive signal during non-rotation, the piezoelectric signal for feedback, and the null voltage signal of the detection coil are respectively shown in FIG. (A), (1), (2), and (3).

In this embodiment, since the vibrator 1 is performing an elliptical motion, the null voltage signal of the detection coil has the same phase as the feedback piezoelectric signal.

Next, when the angular velocity sensor 10 rotates, the output due to the Coriolis force is generated in the same phase as the null voltage signal of the detection coil as shown in (3) of FIG. As shown in (4) of FIG. 8B, the detection piezoelectric signal is input to the gate circuit 34, and the gate circuit 34
It is possible to detect the angular velocity by performing synchronous detection by the synchronous detection circuit 32 using the gate signal from the controller and smoothing by the smoothing circuit 33.

As described above, as shown in the present embodiment, since the vibrator 1 performs an elliptical motion, the output phase of the null voltage of the detection coil coincides with the phase of the output due to the Coriolis force.
Unlike the conventional case, there is no need to reduce the apparent null voltage to zero by a differential circuit, and there is no need to perform synchronous detection using a drive signal or a feedback piezoelectric signal. Does not occur, and the Coriolis force can be detected efficiently.

In the present embodiment, the vibration state of the vibrator 1 is an elliptical motion. However, when the vibration state is a circular motion, the angular velocity can be detected by the same detection method.

In this embodiment, a cantilevered vibrator is used as the vibrator 1, but a vibrator of a tuning fork type, an H type, or the like can be used.

In this embodiment, a vibrator having a magnet attached to a free end is used. However, as a vibrator, a magnetic material having a magnetization direction in a direction perpendicular to the driving vibration direction can be used.

Further, in this embodiment, the piezoelectric body is used as the driving means. However, a method is adopted in which a magnet and a driving coil are provided on the side of the vibrator on the side of the driving vibration, and the vibrator is excited by electromagnetic induction. You can also.

Further, in the present embodiment, the piezoelectric body 3 is used as the feedback detecting means. However, a coil may be used as the feedback detecting means.

Further, in the present embodiment, the configuration is such that the detection coil signal is input to the gate circuit 34, the synchronous detection is performed by the synchronous detection circuit 32 using the gate signal from the gate circuit 34, and the smoothing is performed by the smoothing circuit 33. However, it is also possible to use the envelope detection circuit 35 as described in the second embodiment.

Fourth Embodiment FIG. 9 is a plan view of an angular velocity sensor according to a fourth embodiment of the present invention. Referring to FIG. 9, the angular velocity sensor unit 14 includes a vibrator 1, a driving piezoelectric body 2, a feedback piezoelectric body 3, a permanent magnet 4, and a detection coil 5.

In the present embodiment, except that the detection coil 5 is rotatable in the direction of arrow DB in the figure,
Since the configuration is the same as that of the second embodiment, the same portions are denoted by the same reference characters and description thereof will not be repeated.

In this embodiment, the vibrator 1 is in an elliptically oscillating state as indicated by an arrow DA in FIG.
Here, a case is shown where the vibration balance of the vibrator 1 is poor, and unlike the third embodiment, the direction of the major axis of the ellipse is inclined by an angle θ with respect to the x-axis direction.

In this vibration state, when the detection coil 5 has its surface parallel to the x-axis as shown by C in FIG. 9, the phase of the null output from the detection coil 5 becomes Coriolis It will not match the phase of the output due to force.

Therefore, in the present embodiment, the detection coil 5 is rotatable as indicated by the arrow DB.

When the coil surface of the detection coil 5 is rotated by an angle θ in the direction of arrow B such that the coil surface is parallel to the major axis direction of the elliptical motion of the vibrator 1 as shown in D in FIG. The phase of the null output from the coil 5 can match the phase of the output due to Coriolis force.

Therefore, the detection coil signal is supplied to the gate circuit 3
4, synchronous detection is performed by the synchronous detection circuit 32 using the gate signal from the gate circuit 34, and smoothing is performed by the smoothing circuit 33, whereby the angular velocity can be detected.

As described above, as shown in this embodiment, since the detection coil 5 is installed so as to be rotatable, the vibration balance of the vibrator is poor, and the vibration state is an elliptical motion with a tilt. However, the output of the null voltage of the detecting coil and the phase of the output due to the Coriolis force can be made to coincide with each other, and there is no need to perform synchronous detection using a drive signal or a piezoelectric signal for feedback. Therefore, there is no phase shift at the time of synchronous detection, so that the Coriolis force can be detected efficiently.

In this embodiment, a cantilevered vibrator is used as the vibrator 1, but a vibrator of a tuning fork type, an H type, or the like can be used.

In the present embodiment, a piezoelectric body is used as the driving means. However, a method is employed in which a magnet and a driving coil are provided on the side of the vibrator on the side of the driving vibration, and the vibrator is excited by electromagnetic induction. It is also possible.

Further, in the present embodiment, the piezoelectric body 3 is used as the feedback detecting means, but a coil may be used as the feedback detecting means.

Further, in this embodiment, the piezoelectric signal for detection is input to the gate circuit 34, synchronously detected by the synchronous detection circuit 32 using the gate signal from the gate circuit 34, and smoothed by the smoothing circuit 33. However, as described in the second embodiment, the envelope detection circuit 35 can be used.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0105]

As described above, in the angular velocity sensor according to the present invention, since the vibrator makes a circular motion or an elliptical motion, even if the detecting means is a piezoelectric body or a coil, the null voltage of the detecting means can be reduced. Since the phase of the output coincides with the phase of the output due to the Coriolis force, there is no need to reduce the apparent null voltage to zero by a differential circuit as in the related art. In addition, since there is no need to perform synchronous detection using a signal other than a detection signal such as a drive signal or a piezoelectric signal for feedback, no phase shift occurs during synchronous detection, and Coriolis force can be detected efficiently. .

Further, if the detection signal is subjected to envelope detection, a synchronous detection circuit is not required, and the circuit configuration can be simplified.

Further, when the detecting coil is installed so as to be rotatable as a detecting means, even if the vibration balance of the vibrator is poor and the vibration state is an elliptical motion in which the vibration is inclined, the detection is performed. The output of the null voltage of the coil for use and the phase of the output by the Coriolis force can be made to coincide with each other, and there is no need to perform synchronous detection with a drive signal or a piezoelectric signal for feedback. Therefore, there is no phase shift at the time of synchronous detection, so that the Coriolis force can be detected efficiently.

Further, if the detection signal is subjected to envelope detection, a synchronous detection circuit is not required, and the circuit configuration can be simplified.

[Brief description of the drawings]

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

FIG. 2 is a schematic block diagram illustrating a configuration of an angular velocity sensor according to Embodiment 1 of the present invention.

FIG. 3 is a timing chart for explaining operations of a gate circuit 34 and a synchronous detection circuit 32 shown in FIG. 2;

FIG. 4 is a timing chart for explaining the operation of the angular velocity sensor according to Embodiment 1 of the present invention, and FIG.
FIG. 4B shows a detection waveform at the time of rotation, and FIG. 4B shows a detection waveform at the time of rotation.

FIG. 5 is a schematic block diagram illustrating a configuration of an angular velocity sensor according to Embodiment 2 of the present invention.

FIG. 6 is a perspective view showing an angular velocity sensor according to Embodiment 3 of the present invention.

FIG. 7 is a schematic block diagram illustrating a configuration of an angular velocity sensor according to Embodiment 3 of the present invention.

FIG. 8 is a timing chart for explaining the operation of the angular velocity sensor according to the third embodiment of the present invention;
FIG. 8B shows a detected waveform at the time of rotation, and FIG. 8B shows a detected waveform at the time of rotation.

FIG. 9 is a plan view showing a configuration of an angular velocity sensor according to Embodiment 4 of the present invention.

FIG. 10 is a schematic block diagram showing a configuration of a first conventional angular velocity sensor.

FIG. 11 is a schematic block diagram showing a configuration of a second conventional angular velocity sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibrator 2 Driving piezoelectric body 3 Feedback piezoelectric body 4 Permanent magnet 5 Detecting coil 30 Self-excited oscillation circuit 31 Differential circuit 32 Synchronous detection circuit 33 Smoothing circuit 34 Gate circuit 35 Envelope detection circuit

Continuing from the front page (72) Inventor Tomohisa Koda 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Toru Kira 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka F term (reference) 2F105 AA02 AA08 BB08 CC06 CD01 CD06 CD11

Claims (16)

[Claims] 1. An angular velocity sensor, comprising: a vibrator; driving means for exciting the vibrator; first detection for feedback for detecting the excited state and controlling an exciting operation of the driving means. Means, and second detecting means for detecting a vibration component due to Coriolis force according to an angular velocity acting from outside with an axis parallel to the central axis of the vibrator as a central axis, wherein the angular velocity is applied to the angular velocity sensor In the above, the vibration of the vibrator excited by the driving means makes a circular motion or an elliptical motion in a plane orthogonal to the central axis of the vibrator. 2. The apparatus according to claim 1, further comprising: a signal conversion unit configured to generate an angular velocity detection signal proportional to a time average of an absolute value of a signal from the second detection unit based on an output signal of the second detection unit. Item 2. The angular velocity sensor according to Item 1. 3. The angular velocity sensor according to claim 1, wherein said second detecting means for detecting a vibration component caused by the Coriolis force includes a piezoelectric body. 4. A second detecting means for detecting a vibration component due to the Coriolis force includes: at least one permanent magnet provided at a free end of the vibrator; and induction induced by a change in position of the permanent magnet. The angular velocity sensor according to claim 1, further comprising: a coil that detects a current. 5. The vibrator provided with at least one permanent magnet near the free end is a magnetic material magnetized in a direction orthogonal to a coil surface of the second detecting means. An angular velocity sensor as described. 6. The coil according to claim 4, wherein the coil included in the second detecting means for detecting a vibration component due to the Coriolis force is rotatable while keeping the center axis and the coil surface parallel. Angular velocity sensor. 7. The driving means for exciting the vibrator,
The angular velocity sensor according to any one of claims 1 to 6, further comprising a piezoelectric body. 8. The driving means for exciting the vibrator,
The angular velocity sensor according to claim 1, further comprising a coil. 9. The phase of an output signal of a piezoelectric body included in a second detecting means for detecting a vibration component caused by the Coriolis force is:
4. The angular velocity sensor according to claim 3, wherein the phase of the driving signal of the driving unit is the same as or opposite to the phase of the driving signal. 10. A phase of an output signal of a coil included in a second detecting means for detecting a vibration component caused by the Coriolis force has a phase difference of 90 ° with respect to a phase of a driving signal of the driving means. Item 7. An angular velocity sensor according to any one of Items 4 to 6. 11. The feedback first detecting means for detecting the excitation state includes a piezoelectric body.
The angular velocity sensor according to any one of the above. 12. The feedback first detecting means for detecting the excitation state includes a coil.
The angular velocity sensor according to any one of the above. 13. The detection means for generating a synchronous detection control signal based on an output signal of the second detection means, and the second detection means based on the synchronous detection control means. 3. The angular velocity sensor according to claim 2, further comprising: synchronous detection means for synchronously detecting an output signal of the means and generating the angular velocity detection signal. 14. The angular velocity according to claim 2, wherein the signal conversion unit includes an envelope detection unit that receives the output signal of the second detection unit, performs envelope detection, and generates the angular velocity detection signal. Sensor. 15. A vibrator, driving means for exciting the vibrator, first detecting means for feedback detecting the excited state, and an external device having a central axis parallel to the central axis of the vibrator. A second detection means for detecting a vibration component due to Coriolis force according to the angular velocity acting from the second detection means, wherein a synchronous detection control signal is provided based on an output signal of the second detection means. And a synchronous detection means for synchronously detecting the output signal of the second detection means based on the synchronous detection control means. 16. A vibrator, driving means for exciting the vibrator, first feedback detecting means for detecting the excited state, and an external device having a central axis parallel to the central axis of the vibrator. A detection circuit for an angular velocity sensor, comprising: a second detection means for detecting a vibration component caused by Coriolis force according to an angular velocity acting from an envelope detection circuit for inputting a signal from the second detection means; A detection circuit for an angular velocity sensor, comprising: