JPH095086A - Tuning fork type angular speed detector - Google Patents

Abstract

PURPOSE: To prevent reduction in sharpness of resonance in vibrators so as to improve detecting precision to angular speed. CONSTITUTION: Fork oscillation is generated in a pair of vibrators 30, 31 arranged opposedly to each other, and displacement, which is generated by Coriolis force in the rotational motion around a shaft put between a pair of the vibrators 30, 31 in the vertical direction to the fork oscillating face of a pair of the vibrators 30, 31 is detected, and then, an angular speed of the rotational motion is detected. Displacement detecting means 40, 41 optically detect displacement in the vertical direction to the fork oscillating face.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tuning fork type angular velocity detecting device, and more particularly to a device for detecting an angular velocity by utilizing a Coriolis force generated by a rotary motion of a tuning fork type oscillator.

[0002]

2. Description of the Related Art Hitherto, as an angular velocity detecting device for detecting an angular velocity of a rotational motion applied to an object such as a yaw applied to a vehicle, a tuning fork type angular velocity detecting device as disclosed in Japanese Patent Laid-Open No. 4-1852 has been used. .

FIG. 5 is a structural diagram of a tuning fork type angular velocity detecting device. In FIG. 5A, the vibrators 10 and 11 are connected to each other by the coupling unit 1.
They are connected by 2 to form a tuning fork. Piezoelectric elements 14 and 15 for driving are attached to the outer side surfaces 10a and 11a in the X direction of the oscillators 10 and 11, respectively, and by supplying a drive signal to the piezoelectric elements 14 and 15, The tuning fork vibrations 10 and 11 horizontally in the XZ plane. In addition, the Y-direction front side surface 10 of each of the vibrators 10 and 11
A piezoelectric element 1 for detection is provided in the vicinity of the joint 12 of b and 11b.
6 and 17 are attached.

Here, when the rotational motion of the angular velocity ω about the axis 18 between the oscillators 10 and 11 is applied, the oscillators 10 and 1
The Coriolis force in the Y direction acts on each. Oscillator 10, 11
The Coriolis forces acting on each of them are equal in magnitude and opposite to each other. As shown in FIG. 6B, the transducers 10 and 11 are displaced from the solid line positions to the broken line positions, and then return to the solid line positions to form the alternate long and short dash line. The signal that is displaced to the position and returns to the solid line position is given.

The displacements of the vibrators 10 and 11 in the Y direction are detected by the piezoelectric elements 16 and 17, respectively, and the angular velocity ω is detected by differentially amplifying the detection signals.

[0006]

In the conventional device, the vibrator 1 is used.
Piezoelectric element 1 attached to surfaces 10b and 11b of 0 and 11 respectively
Displacements in the Y direction of the vibrators 10 and 11 are detected by 6 and 17. That is, the piezoelectric elements 16 and 17 are deformed by the Coriolis force and generate a detection voltage.

Therefore, the Coriolis force is generated by the oscillators 10, 11
And the piezoelectric elements 16 and 17 are dispersed by the deformation stress, and as shown in FIG. 6, the resonance characteristics of the vibrators 10 and 11 are shown by a solid line I when the vibrator is a single body and a solid line when the piezoelectric element is attached. II, the frequency width Δf of the resonance is widened by sticking the piezoelectric element, and the sharpness Q of the resonance is reduced. Therefore, there is a problem that the amplitude of vibration of the vibrators 10 and 11 is reduced, the displacement amount caused by the Coriolis force is reduced accordingly, and the detection accuracy of the Coriolis force, that is, the detection accuracy of the angular velocity is deteriorated.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a tuning fork type angular velocity detection device capable of preventing a reduction in the resonance sharpness of the oscillator and improving the angular velocity detection accuracy by optically detecting the displacement of the oscillator caused by the Coriolis force.

[0009]

According to the present invention, a pair of vibrators are arranged to face each other to vibrate a tuning fork, and the pair of vibrators generate a Coriolis force of a rotary motion about an axis sandwiched between the pair of vibrators. A tuning fork type angular velocity detecting device for detecting a displacement of a vibrator in a direction perpendicular to a vibrating surface of a tuning fork to detect an angular velocity of the rotary motion, a displacement detecting means for optically detecting a displacement in a direction perpendicular to the vibrating surface of the tuning fork. Have.

[0010]

In the present invention, since the displacement of the oscillator in the direction perpendicular to the vibrating surface of the tuning fork caused by Coriolis force is detected optically without contact, it is necessary to attach a piezoelectric element to the oscillator for detecting the displacement. Therefore, it is possible to prevent the sharpness of the resonance of the vibrator from being reduced, which increases the displacement amount and improves the angular velocity detection accuracy.

[0011]

1 is a structural diagram of an embodiment of a tuning fork type angular velocity detecting device of the present invention. In FIG. 1A, the vibrators 30 and 31 of constant elastic body made of, for example, an Erinvar material are connected by a connecting portion 32 to form a tuning fork shape. Piezoelectric elements 34 and 35 for driving made of, for example, barium titanate are attached to the outer side surfaces 30a and 31a of the vibrators 30 and 31 in the X direction, respectively. Piezoelectric elements 52 and 53 for drive detection are attached to the inner surface (surfaces facing each other) of the. In the vicinity of the tip of each of the vibrators 30 and 31, the front side surface 30 in the Y direction is formed.
Optical displacement gauges 40 and 41 as displacement detecting means are fixed so as to be spaced apart from and face a and 31a.

As shown in FIG. 2, the optical displacement meter has an optical fiber 45 for emitting light and an optical fiber 46 for receiving light. A light beam of a constant light amount emitted from the light emitting element 47 is supplied to the optical fiber 45 and emitted from the open end 45a of the optical fiber 45. The optical fiber 46 is arranged in parallel with the optical fiber 45, and the open end 46 a of the optical fiber 46 is oriented in the same direction as the open end 45 a of the optical fiber 45. The light emission pattern from the open end 45a has a substantially conical shape 45b, and the light receiving pattern at the open end 46a has a substantially conical shape 46b.
It is. The conical patterns 45b and 46b partially overlap with each other, and the overlapping increases as the distance d from the open ends 45a and 46a to the reflecting object increases.

Therefore, the received light quantity at the open end 46a of the optical fiber 46 has a relationship with the distance d as shown by the solid line in FIG. 3, and the received light quantity P is proportional to the distance d in the range from the distance d ₁ to d _2. . The light received by the optical fiber 46 is photoelectrically converted by the light receiving element 48, and the light detection signal is output to the terminal 49.
Output from

Returning to FIG. 1A, when the drive signals are supplied to the piezoelectric elements 34 and 35, the vibrators 30 and 31 are transmitted.
Vibrates horizontally in the X-Z plane (tuning fork vibration plane). Here, when the rotational motion of the angular velocity ω is applied about the shaft 38 sandwiched between the oscillators 30 and 31, the oscillators 30 and 31 are
A Coriolis force in the Y direction, which is the direction perpendicular to the tuning fork vibrating surface, acts on each. The Coriolis forces acting on the vibrators 30 and 31 have the same magnitude and opposite directions. As shown in FIG. 1B, the vibrators 30 and 31 are displaced from the solid line positions to the broken line positions, and then the solid line positions. Then, the signal is returned to the position indicated by the alternate long and short dash line and returned to the position indicated by the solid line.

The optical displacement meters 40 and 41 respectively include a vibrator 30,
In order to detect the Y-direction displacement due to the Coriolis force of 31, the transducers 30 and 31 shown by the solid lines in FIG. 1B are spaced apart by a distance (d ₁ + d ₂ ) / 2. Since the Y-direction displacements due to the Coriolis forces of the vibrators 30 and 31 are opposite to each other, for example, when the detection signal of the optical displacement meter 40 increases, the detection signal of the optical displacement meter 41 decreases.

FIG. 4 shows a circuit block diagram of the device of the present invention. In the figure, the drive circuit 51 supplies a drive signal to the piezoelectric elements 34 and 35, whereby the vibrators 30 and 31 automatically vibrate. The tuning fork vibration of each of the vibrators 30 and 31 is detected by a driving detection circuit 54 connected to the piezoelectric elements 52 and 53, and a driving detection signal is generated. The AGC circuit 55 controls the level of the drive signal output from the drive circuit 51 so that the peak value of the drive detection signal becomes a predetermined value.

The Y-direction distances of the vibrators 30 and 31 detected by the optical displacement meters 40 and 41, that is, the displacement detection signals are supplied to the differential amplifier 56 and differentially amplified. As a result, the differential amplifier 56 outputs a displacement detection signal corresponding to twice the displacement of each of the vibrators 30 and 31 generated by the Coriolis force. This displacement detection signal is supplied to the phase detection circuit 57, and DC conversion of the same phase component as the drive detection signal is performed.
The in-phase component is a signal proportional to the angular velocity ω. The detection signal output from the phase detection circuit 57 is a low-pass filter (LP
In F) 58, unnecessary high frequency components are removed and output from the terminal 59.

In this embodiment, the optical displacement gauges 40 and 41 are used to detect the displacement in the Y direction of the vibrators 30 and 31 caused by the Coriolis force. Therefore, the conventional piezoelectric elements 16 and 17 for detection are unnecessary, the resonance characteristics of the vibrators 30 and 31 are as shown by the solid line I in FIG. 6, and the decrease in Q is prevented and the amplitude of vibration is increased. Therefore, Y due to Coriolis force
The amount of displacement in the direction is also increased, and the angular velocity detection accuracy is improved accordingly.

[0019]

As described above, according to the present invention, the displacement in the direction perpendicular to the tuning fork vibrating surface of the vibrator caused by the Coriolis force is detected optically in a non-contact manner. Since it is not necessary to attach a piezoelectric element, it is possible to prevent the resonance sharpness of the vibrator from being lowered, which increases the displacement amount and improves the angular velocity detection accuracy, which is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a structural diagram of a device of the present invention.

FIG. 2 is a configuration diagram of an optical displacement meter.

FIG. 3 is a diagram showing characteristics of an optical displacement meter.

FIG. 4 is a circuit block diagram of the device of the present invention.

FIG. 5 is a structural diagram of a conventional device.

FIG. 6 is a diagram showing a resonance characteristic of a vibrator.

[Explanation of symbols]

 30, 31 Oscillator 32 Coupling part 34, 35, 52, 53 Piezoelectric element 40, 41 Optical displacement meter 51 Drive circuit 54 Drive detection circuit 55 AGC circuit 56 Differential amplifier 57 Phase detection circuit 58 Low pass filter

Claims (1)

[Claims] 1. A pair of vibrators are arranged to face each other to vibrate a tuning fork, and are perpendicular to a tuning fork vibrating surface of the pair of vibrators generated by a Coriolis force of a rotary motion about an axis sandwiched between the pair of vibrators. A tuning fork type angular velocity detecting device for detecting the angular velocity of the rotational motion by detecting the displacement in the direction, the tuning fork type having a displacement detecting means for optically detecting the displacement in the direction perpendicular to the tuning fork vibrating surface. Angular velocity detector.