JPH10197253A - Piezoelectric vibration type angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve manufacturing yield and precision, by dividing a pair of exciting electrodes formed on one of the leg parts of a piezoelectric vibrator into two parts, arranging the electrodes at the positions where displacement is generated by distortion due to an electric field which is applied to the piezoelectric vibrator, and applying an AC voltage to the electrodes. SOLUTION: A first exciting electrode 5 and a second exciting electrode 6 are formed on one leg part 2 of a piezoelectric vibrator 1. A detecting electrode is formed on the other leg part 2 of the piezoelectric vibrator 1. The first exciting electrode 5 and the second exciting electrode 6 are excited by mutually independent electric field intensities, so that 'vibration leakage' is made zero. Therefore, the deviation of vibrating posture which is caused by factors such as characteristics of crystal structure of the piezoelectric vibrator and manufacturing process can be easily corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excitation electrode structure of a piezoelectric vibrator in which a vibration mode is changed by adjusting an excitation electric field strength in a piezoelectric vibration angular velocity sensor.

[0002]

2. Description of the Related Art Vibration frequencies of a vibrator in an X-axis direction and a Z-axis direction are previously adjusted. For example, when it is rotated about the Y axis while vibrating in parallel to the X axis, X
Since Coriolis force is generated in the Z-axis direction perpendicular to the axis,
It has a vibration component having a magnitude proportional to the Coriolis force in the axial direction. Therefore, it is possible to detect the magnitude of the Coriolis force by measuring the amount of charge generated by the vibration component in the Z-axis direction or detecting the displacement of the vibration.

[0003] Since the Coriolis force is determined in proportion to the magnitude of the angular velocity, if the Coriolis force is directly measured indirectly as the amount of deflection displacement of the Coriolis force by the piezoelectric effect of the piezoelectric element, a change in capacitance, etc. The magnitude of the rotational angular velocity acting on the rotation of the child in the Y-axis direction can be obtained. By utilizing these characteristics, a vibrating vibrator is mounted on a vehicle or aircraft as an element for detecting angular velocity, and its running or flight trajectory is recorded, and yaw rate generated during turning is detected. I have. Further, the angular velocity detecting element can be mounted on a robot, and can be applied to control of a posture thereof.

[0004]

In the angular velocity sensor using vibration as described above, there is a problem of mass imbalance due to insufficient precision in the manufacturing process, and vibration due to approaching two orthogonal vibration frequencies to improve sensitivity. Due to the degeneration phenomenon, a vibration mode having a component in the Z-axis direction occurs although the excitation vibration originally needs to be vibrated in parallel to the X-axis.

[0005] In short, the arrangement of excitation electrodes (accuracy: position, size, amount of formation), element shape (processing accuracy: etching, machining), crystal structure, crystal defects (impurities, etc.) formed on the vibrator, etc. The vibration direction of the vibrator becomes X due to the mass imbalance of the vibrator due to the manufacturing technology of
Despite being off the axis and not rotating,
A phenomenon occurs in which charges are generated by the vibration component in the Z-axis direction.

[0006] The phenomenon of abnormal charge generation of the vibrator, that is, "leakage of vibration" occurs when the vibrator originally vibrating along the X axis rotates around the Y axis.
Although the angular velocity can be detected by the generation of the Coriolis force in the axial direction, as shown in FIG. 10, the amount of deviation of the vibration form due to factors such as the mass imbalance of the vibrator itself further fluctuates even with temperature changes. In addition, there is a problem that the amount of electric charge generated in the Z-axis direction of the vibrator to be detected as the angular velocity changes irrespective of the Coriolis force, causing an error in the detected rotational angular velocity.

[0007]

SUMMARY OF THE INVENTION In order to solve the problem of "vibration leakage" in the above-described piezoelectric vibration type angular velocity sensor, according to the present invention, an excitation formed on at least one of the legs of the piezoelectric vibrator is provided. At least one pair of the electrodes is divided into two parts, and the excitation electrode arrangement (accuracy: position, size, formation amount) described in the conventional problem (FIG. 10), the element shape (processing accuracy: etching, machining), It corrects vibrational state abnormalities of the vibrator due to manufacturing technical reasons such as crystal structure and crystal defects (impurities and the like) and degeneracy.

When an electric field is applied to the piezoelectric vibrator, an electrode is arranged at a position where displacement occurs due to a distortion caused by the electric field, and when an AC voltage is applied to the electrode, an electric field proportional to the magnitude is generated between the electrodes. Displacement occurs due to the corresponding distortion. This makes it possible to cause mechanical vibration.

Conventionally, as shown in FIG. 6, excitation is performed by electric fields having the same intensity from e1 to e4.
Although it should vibrate parallel to the axis, a vibration component in the Z-axis direction actually occurs due to mass imbalance and degeneracy in manufacturing. Therefore, in the present invention, FIGS.
As shown in (c), by independently varying the electric field strengths from e1 to e4, the displacement amount of the vibrator is adjusted so that the vibration leakage becomes zero (minimized), thereby solving the problem. We were able to.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In each drawing, the same reference numeral indicates the same object. FIG. 1 shows a side view of a piezoelectric vibrator 1 of the present invention. A first excitation electrode 5 and a second excitation electrode 6 are formed on one of the legs 2 (a surface parallel to the Y axis) of the piezoelectric vibrator 1, and a detection electrode is provided on the other leg 2 of the piezoelectric vibrator 1. 3 are formed.

Conventionally, as shown in FIG. 8, the excitation electrode 3 is formed on the surface of one of the legs 2 of the piezoelectric vibrator 1 facing the other, and as shown in FIG. Due to manufacturing technology reasons such as electrode arrangement (accuracy: position, size, formation amount), element shape (processing accuracy: etching, machining), crystal structure, crystal defects (impurities, etc.), vibration mode It shifts and vibrates.

Therefore, as shown in the side view of the piezoelectric vibrator 1 in FIG. 1, the excitation electrode 3 is divided into two parts in the longitudinal direction (Y-axis direction), and the first excitation electrode 5 and the second The two excitation electrodes 6 are formed, are excited with independent electric field strengths, and the "vibration leakage" is reduced to zero, thereby correcting the above-described deviation of the vibration form of the leg 2 on the excitation side. .

As shown in FIG. 9, a first excitation electrode 5 and a second excitation electrode 6 are formed on the upper halves (in the figure) of both legs 2 of the piezoelectric vibrator 1, and both legs 2 are formed. The same control can be performed by forming the detection electrode 3 in the lower half (in the figure) of the section 2. Although this is not shown, H shown in FIG.
It goes without saying that the same applies to the piezoelectric vibrator of the type.

FIG. 2 shows an example of electric field intensity control, in which the leg 2 on the excitation side of the piezoelectric vibrator 1 is divided into two parts in the longitudinal direction (Y-axis direction), and a first excitation electrode 5 and a second excitation electrode are provided. An electrode 6 is formed. First excitation electrode 5 and second excitation electrode 6
Is adjusted by adjusting the potential applied to the first excitation electrode 5 and the second excitation electrode 6 by means of the variable resistor R, and thereby the excitation electrode arrangement, the element shape, the crystal structure, the crystal defects, etc. Voltage (charge) is separately applied to the first excitation electrode 5 and the second excitation electrode 6 formed on the leg 2 on the excitation side in the direction in which the displacement of the vibrator can be corrected. The purpose is to adjust and correct the vibration mode of the piezoelectric vibrator 1.

To correct the vibration mode of the piezoelectric vibrator 1 by applying a voltage to the vibration mode of the piezoelectric vibrator 1 using the first excitation electrode 5 and the second excitation electrode 6, the piezoelectric vibrator 1 is excited and the detection electrode 4
Detects the amount of “vibration leakage” that occurs in the
The adjustment is performed by adjusting the variable resistor R so that the amount becomes zero or minimum. In this embodiment, the charge signal to the excitation electrode is varied by the variable resistor R, but each excitation electrode is (individually)
It may be directly excited.

Although the above description has been made with respect to a so-called U-shaped piezoelectric vibrator, the same applies to an H-shaped piezoelectric vibrator as shown in FIG. In the H-type piezoelectric vibrator, the upper half in the drawing has a leg configuration as an excitation unit, and the lower half in the drawing has a leg configuration as a detection unit. Therefore, the leakage of the vibration of the excitation electrode propagates from the upper half to the lower half in the figure.

In this embodiment, a U-shaped piezoelectric vibrator and an H-shaped piezoelectric vibrator are described. However, a rod-shaped piezoelectric vibrator may be used.

[0018]

According to the present invention, it is possible to easily correct the deviation of the vibration form due to various characteristics of the crystal structure (crystal structure, crystal defect) of the piezoelectric vibrator and the manufacturing process (excitation electrode arrangement and element shape). In addition, the manufacturing yield was improved, and the accuracy of the angular velocity detector was improved, so that the product quality was improved and the manufacturing process was simplified.

[Brief description of the drawings]

FIG. 1 is a side view showing a piezoelectric vibration type angular velocity sensor and an electrode structure of the present invention.

FIG. 2 is a view of a U of the present invention when only the legs are viewed from the Y-axis direction.
It is a figure which shows the excitation electrode arrangement | positioning and voltage application method of a character-shaped piezoelectric vibration type angular velocity sensor.

FIG. 3 is a side view showing an H-type piezoelectric vibration type angular velocity sensor and an electrode structure of the present invention.

FIG. 4 is a view showing H when only the legs of the present invention are viewed from the Y-axis direction.
FIG. 3 is a diagram showing an excitation electrode arrangement and a voltage application method of a piezoelectric vibration type angular velocity sensor.

FIG. 5 is a partially enlarged view of a leg showing an arrangement diagram of an excitation electrode according to the present invention when viewed from a Y-axis direction.

FIG. 6 is a partially enlarged view of a leg portion showing a layout of conventional excitation electrodes when viewed from the Y-axis direction.

FIG. 7 is a side view showing a conventional piezoelectric vibration type angular velocity sensor and an electrode structure.

FIG. 8 is a diagram showing an excitation electrode arrangement and a voltage application method of a conventional U-shaped piezoelectric vibration type angular velocity sensor when only a leg is viewed from the Y-axis direction.

FIG. 9 is a side view showing a piezoelectric vibration type angular velocity sensor of the present invention and another electrode structure arrangement.

FIG. 10 is a view for explaining a vibration state of the excitation-side leg when only the leg is viewed from the Y-axis direction, which is a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 2 Leg 3 Excitation electrode 4 Detection electrode 5 First excitation electrode 6 Second excitation electrode R Variable resistance

Claims (3)

[Claims] An excitation electrode formed on a surface parallel to a leg Y axis of a U-shaped piezoelectric vibrator, and a detection electrode formed on the same leg or the other leg of the excitation electrode, A piezoelectric element for detecting an angular velocity acting around the direction of expansion and contraction of the leg portion based on a charge signal generated on a detection electrode of the piezoelectric vibrator while vibrating the piezoelectric vibrator by applying an AC voltage to the excitation electrode. In the vibration type angular velocity sensor, in order to correct the vibration state that can vibrate parallel to the X axis,
A piezoelectric vibration type angular velocity sensor, wherein the excitation electrode of the piezoelectric vibrator is divided into a first excitation electrode and a second excitation electrode, and an independent voltage is applied to each of the electrodes. 2. An excitation electrode is provided on a surface parallel to the Y-axis of the leg of the H-type piezoelectric vibrator, and an excitation electrode is provided on the other leg with the Y-axis symmetrical. A detection electrode is provided on the leg of the book, and while the piezoelectric vibrator is vibrated by applying an AC voltage to the excitation electrode, the leg is expanded and contracted based on a charge signal generated at the detection electrode of the piezoelectric vibrator. In the piezoelectric vibration type angular velocity sensor that detects the angular velocity acting around the direction, in order to correct the vibration form that can vibrate parallel to the X axis,
A piezoelectric vibration type angular velocity sensor, wherein the excitation electrode of the piezoelectric vibrator is divided into a first excitation electrode and a second excitation electrode, and an independent voltage is applied to each of the electrodes. 3. The piezoelectric vibration angular velocity sensor according to claim 1, wherein a variable resistor is connected to the charge signal for exciting the first excitation electrode and the second excitation electrode.