JPH1114374A - Vibration gyroscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration gyroscope whose constitution is simplified and which can be horizontally installed in mounting and whose height can be reduced. SOLUTION: This gyroscope uses a vibrator 1 constituted of a pair of driving arms 2 and 3 having driving means 11-1 to 11-4, a detecting arm 4 having detecting means 12-1 to 12-4 arranged between a pair of driving arms 2 and 3 and a base part 5 to connect these driving arms 2 and 3 and detecting arm 4 in a single plane. In this case, it is constituted so that a pair of driving arms 2 and 3 are vibrated mutually in an opposite phase in a single plane in a driving vibration mode by a driving means, and when rotational angular velocity is applied to the vibrator 1 with the axis vertical to this single plane as the center, Coriolis force is made to act mutually in the reverse direction along a pair of driving arms 2 and 3, and the rotation moment is thereby applied to the whole vibrator, and vibration of a detecting vibration mode in a single plane is generated, and this vibration is found as an electric signal by detecting means 12-1 to 12-4, and the rotational angular velocity is found.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pair of driving arms having driving means, a detecting arm having detecting means provided between the pair of driving arms, and the driving arm and the detecting arm in one plane. The present invention relates to a vibratory gyroscope using a vibrator composed of a base to be connected.

[0002]

2. Description of the Related Art Conventionally, as an angular velocity sensor for detecting a rotational angular velocity in a rotating system, a vibrating gyroscope using a piezoelectric body has been used for confirming the position of an aircraft, a ship, a space satellite, or the like. Was. Recently, it has been used as a consumer field for car navigation, detection of camera shake of a VTR or a still camera, and the like.

[0003] Such a piezoelectric vibratory gyroscope utilizes the fact that when an angular velocity is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the vibration. And the principle is analyzed with a mechanical model (for example,
"Acoustic Wave Technology Handbook", Ohmsha, 491
497). Various types of piezoelectric vibrating gyroscopes have been proposed so far. For example, Sperry tuning fork type gyroscope, Watson tuning fork type gyroscope, equilateral triangular prism type resonating gyroscope,
A cylindrical sound piece gyroscope and the like are known.

[0004]

In any of the above-described conventional piezoelectric vibratory gyroscopes, the rotational angular velocity cannot be detected unless the vibrator is disposed parallel to the rotational axis (vertically disposed). Usually, the rotation axis of the rotating system to be measured is perpendicular to the mounting part, so when mounting such a piezoelectric vibratory gyroscope, the height of the piezoelectric vibratory gyroscope is reduced with respect to the mounting part. It was difficult.

In recent years, a piezoelectric vibratory gyroscope capable of detecting a rotational angular velocity even when a vibrator is arranged perpendicularly (horizontally) with respect to a rotation axis has been proposed in Japanese Patent Application Laid-Open No. Hei 8-128833. In this example, as shown in an example in FIG. 5, a weight 53 is provided at the tip of three elastic bodies 51a, 51b, and 51c. Elastic bodies 51a, 51b, 51c
Are vibrated in the XY plane by the piezoelectric elements 54 and 55 in phases opposite to each other. The Coriolis force in the Y direction generated by the rotational angular velocity ω about the Z axis is applied to the position of the center of gravity of the weight 53. Since the surfaces of the elastic bodies 51a, 51b, and 51c and the position of the center of gravity of the weight 53 are slightly separated in the Z direction, the elastic body 51 is generated by Coriolis force acting on the center of gravity of the weight 53.
The tips of a, 51b, and 51c bend in opposite directions in the Z direction. By detecting this bending vibration with the piezoelectric elements 56 and 57, the rotational angular velocity ω about the Z axis is obtained.

In the piezoelectric vibratory gyroscope described in the above-mentioned Japanese Patent Application Laid-Open No. 8-128833, the rotational angular velocity can be detected even if the vibrator is placed horizontally in principle. However, since the weight 53 needs to be provided, the height is not sufficiently reduced. Further, when the thickness of the weight 53 is reduced in order to sufficiently reduce the height, the moment due to the Coriolis force is correspondingly reduced, the bending vibration becomes minute, and the measurement sensitivity is lowered.

Further, in the vibrator of the piezoelectric vibratory gyroscope having the above-described configuration, the vibration directions of driving and detection are different due to the configuration of the vibrator. That is, the elastic body 51a,
The vibration in two directions was required, in which the vibrations 51b and 51c also vibrate in the Z direction while vibrating in the XY plane. In general, in a piezoelectric vibratory gyroscope, the natural frequency of the driving vibration mode and the natural frequency of the detecting vibration mode are:
In order to improve the measurement sensitivity, it is required to maintain a constant relationship. Here, when a single crystal is considered as a material of the vibrator, since the single crystal has anisotropy, a change in a natural frequency depending on a temperature differs depending on a vibration direction. For this reason, if the oscillator having the above-described configuration is made of a single crystal, the relationship cannot be maintained when the temperature changes, even if the natural frequency of the vibration and the detection frequency is fixed at a certain temperature. There is a problem that the sensitivity easily changes with temperature.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a vibratory gyroscope that has a simplified configuration, can be placed horizontally when mounted, and can achieve a low profile.

[0009]

According to the vibration gyroscope of the present invention, a pair of driving arms having driving means, a detecting arm having detecting means provided between the pair of driving arms, and detecting means for detecting these driving arms. A vibrating gyroscope using a vibrator comprising an arm and a base connecting the arm in one plane, wherein the driving means causes a pair of driving arms to vibrate in a driving vibration mode in opposite phases in one plane. When a rotational angular velocity is applied to the vibrator about an axis perpendicular to this one plane, Coriolis forces act in opposite directions along a pair of drive arms, thereby rotating the vibrator as a whole. A moment is applied to the detection arm to generate vibration in a detection vibration mode within one plane, and the vibration is obtained as an electric signal by the detection means to obtain a rotational angular velocity. It is characterized in that it has cormorants configuration.

According to the present invention, the pair of drive arms constituting the vibrator, the detection arm provided between them, and the base can be formed in the same plane. Therefore, if a vibrating gyroscope of a horizontal type is configured using this vibrator, the height of the gyroscope can be reduced.

Further, since the vibration of the drive vibration mode of the drive arm and the vibration of the detection vibration mode of the detection arm are in the same plane, quartz, LiTaO _{3 are used} as the material of the vibrator.
Single crystal, LiNbO ₃ single crystal, Li (Nb, Ta) O ₃
Single crystals can be suitably used. In this case, the measurement sensitivity can be improved, and the vibrator can be formed from a single crystal thin plate by a wafer process such as etching (in the case of quartz) or a method of cutting a single crystal such as cutting (LiTaO ₃ single crystal, LiNbO ₃ single crystal). Etc.), which is preferable. In addition, when each of the open ends of the drive arm is provided with an overhang portion that is symmetrically overhang in the same plane as the drive vibration mode vibration and the detection vibration mode vibration around the drive arm, the vibrator has a low profile. In addition, the width of the vibrator can be reduced, and the gyroscope can be made more compact.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an example of the structure of a vibrator used in a vibratory gyroscope according to the present invention. In the example shown in FIG. 1, the vibrator 1 is provided between a pair of drive arms 2 and 3 parallel to each other, and between the pair of drive arms 2 and 3, at a position intermediate between the two in parallel with the drive arms 2 and 3. Detection arm 4 and a base 5 for connecting these three drive arms 2, 3 and detection arm 4 in the same plane.
It is composed of In this example, a case is considered in which the vibrator 1 is formed of a Z plate of LiTaO ₃ single crystal, which is an example of a piezoelectric single crystal, and therefore, two faces of the driving arms 2 and 3 facing each other corresponding to the main surface of the base 5 are considered. Driving electrodes 11-1 to 11-4 as driving means are provided one by one, and two detecting electrodes 12-1 as detecting means are respectively provided on two opposing surfaces of the detection arm 4 corresponding to the main surface of the base 5.
To 12-4. Of course, when the vibrator 1 is made of a constant elastic alloy such as an Elinvar alloy, the driving electrodes 11-1 to 11-
It is necessary to use a piezoelectric plate in combination with No. 4 and the detection electrodes 12-1 to 12-4.

Although the drive arms 2 and 3, the detection arm 4 and the base 5 constituting the vibrator 1 can be formed of separate members, they are integrally formed because of the easiness of manufacture particularly when they are formed of a piezoelectric single crystal. It is preferable to configure. In addition, their materials are not particularly limited, but quartz, LiNb
It is preferable to use a piezoelectric single crystal composed of O ₃ , LiTaO ₃ , and Li (Nb, Ta) O ₃ . The vibrator 1 having the configuration shown in FIG.
When the vibration type gyroscope is formed perpendicular to the above, the vibrations of the drive arms 2 and 3 can be made in the same plane as described later, so that the piezoelectric single crystal can be suitably used.

Further, when these piezoelectric single crystals are used,
The detection sensitivity can be improved and the detection noise can be improved.
Size can be reduced. Furthermore, it is insensitive to temperature changes.
Therefore, it is suitable for in-vehicle use requiring temperature stability.
You. Note that among the piezoelectric single crystals, LiNbO_Three Simple connection
Crystal, LiTaO_Three Single crystal has relatively small electromechanical coupling coefficient
LiNbO is larger than quartz_Three Single crystal or
LiTaO _Three Preferably, a single crystal is used. Also,
LiNbO_Three Single crystal and LiTaO_ThreeCompare with single crystal
And LiTaO_Three Single crystal is LiNbO_Three From a single crystal
Also has a relatively higher specific gravity, so that LiNbO_Three 
LiTaO than single crystal_Three The use of single crystals
Preferred.

Next, a description will be given of the operation when a vibrating gyroscope of a horizontal type is constructed using the vibrator 1 shown in FIG. First, by applying an AC voltage to the drive electrodes 11-1 to 11-4 in a rotating system having the Z axis as a central axis, the drive arms 2 and 3 are driven in opposite directions in the drive vibration mode in the XY plane. Let In this state, when the rotational angular velocity ω acts on the Z axis, F1 and F2 in opposite directions along the Y axis act on the respective drive arms 2 and 3 due to the Coriolis force. Since the base 5 is fixed at the end opposite to the side where the drive arms 2 and 3 and the detection arm 4 are provided, for example, the moments acting to rotate the entire vibrator 1 by the forces F1 and F2. M1 and M2 work. By the moments M1 and M2,
The drive arms 2 and 3 and the detection arm 4 are caused to vibrate in the detection vibration mode in the XY plane. By obtaining the vibration in the detection vibration mode of the detection arm 4 as electric vibration using the detection electrodes 12-1 to 12-4, the rotational angular velocity ω can be measured. 2A and 2B show examples of the driving vibration mode and the detection vibration mode of the vibrator 1 shown in FIG. 1, and FIG. 3 shows a wiring state of each electrode.

In the vibratory gyroscope of the present invention using the vibrator 1 having the above-described configuration, the Coriolis forces F1 and F2 generated in the same XY plane as the drive arms 2 and 3 apply to the rotational movement of the vibrator 1. The vibrator 1 is arranged perpendicularly to the rotation axis Z (horizontal) since the detection arm 4 is caused to vibrate in the detection vibration mode in the XY plane and the rotational angular velocity is obtained from the vibration. Even so, the rotational angular velocity can be detected. Therefore, even when the vibratory gyroscope of the present invention is mounted as an angular velocity sensor, for example, for the purpose of determining the rotational angular velocity of a vehicle body, the height of the mounting portion can be reduced.

FIG. 4 is a diagram showing the configuration of another example of the vibrator used in the vibratory gyroscope of the present invention. In the example shown in FIG. 4, the same members as those in the example shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. 4 is different from the example shown in FIG. 1 in that each of the open ends 2a and 3a of the drive arms 2 and 3 symmetrically protrudes in the XY plane around the drive arms 2 and 3, respectively. Part 2
b-1, 2b-2; 3b-1, 3b-2. Overhangs 2b-1, 2b-2; 3b-1, 3b-
In this example, the shape of 2 is a rectangular shape, but the overhanging portions 2b-1 and 2b-2 or the overhanging portion 3
If b-1 and 3b-2 have the same shape, it goes without saying that the same effect can be obtained with other shapes. When a vibrating gyroscope of a horizontal type is configured using the vibrator 1 shown in FIG. 4, the vibrations in the driving vibration mode and the detection vibration mode are shown in FIGS. 2 (a) and 2 (b).
The wiring state of each electrode is the same as that shown in FIG.
This is the same as the example shown in FIG.

In the example shown in FIG. 4, the overhangs 2b-1,
2b-2; 3b-1, since the volume of the arm can be increased at the open ends 2a, 3a by providing 3b-2, FIG.
The drive arm having the same natural frequency as the drive arms 2 and 3 shown in FIG. Therefore, in addition to the reduction in height as in the example shown in FIG. 1, the length of the drive arms 2 and 3 can be reduced, in other words, the width of the vibrator 1 can be reduced, and if the vibrator 1 shown in FIG. It can be seen that the vibratory gyroscope can be made more compact.

[0019]

As is apparent from the above description, according to the present invention, a pair of drive arms constituting a vibrator, and a detection arm and a base provided therebetween are formed in the same plane. Therefore, if a vibrating gyroscope of a horizontal type is configured using this vibrator, the height of the gyroscope can be reduced.

Further, since the vibration of the drive vibration mode of the drive arm and the vibration of the detection vibration mode of the detection arm are in the same plane, the material of the vibrator is quartz, LiTaO _3.
Single crystal, LiNbO ₃ single crystal, Li (Nb, Ta) O ₃
Single crystals can be suitably used. In this case, the measurement sensitivity can be improved, and the vibrator can be formed from a single crystal thin plate by a wafer process such as etching (in the case of quartz) or a method of cutting a single crystal such as cutting (LiTaO ₃ single crystal, LiNbO ₃ single crystal). Etc.), which is preferable.

Further, in the case where a projecting portion symmetrically projecting in the same plane as the driving vibration mode vibration and the detection vibration mode vibration with the driving arm as a center is provided for each of the open ends of the driving arm, In addition to the reduction in height, the width of the vibrator can be reduced, and the gyroscope can be made more compact.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an example of a vibrator used for a vibratory gyroscope of the present invention.

FIGS. 2A and 2B are diagrams respectively showing examples of a driving vibration mode and a detection vibration mode in the example shown in FIG.

FIG. 3 is a diagram showing a wiring state of each electrode in the example shown in FIG.

FIG. 4 is a diagram showing the configuration of another example of a vibrator used for the vibratory gyroscope of the present invention.

FIG. 5 is a diagram showing a configuration of an example of a vibrator used in a conventional vibratory gyroscope.

[Explanation of symbols]

1 vibrator, 2, 3 drive arm, 4 detection arm, 5
Base, 11-1 to 11-4 Drive electrode, 12-1 to 1
2-4 Detection electrode

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takao Soma 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Insulator Co., Ltd.

Claims (3)

[Claims] 1. A pair of driving arms having driving means, a detecting arm having detecting means provided between the pair of driving arms, and a base connecting these driving arms and the detecting arm in one plane. A vibratory gyroscope using a vibrator, wherein a pair of driving arms vibrate in a driving vibration mode in a phase opposite to each other in a plane by a driving means, and vibrate around an axis perpendicular to the plane. When a rotational angular velocity is applied to the vibrator, Coriolis forces act in opposite directions along a pair of drive arms, thereby applying a rotational moment to the entire vibrator and applying a rotational moment to the detection arm in one plane. A vibratory gyroscope in which a vibration in a detection vibration mode is generated, and the vibration is obtained as an electric signal by a detection means to obtain a rotational angular velocity. 2. An open end of each of the pair of drive arms,
2. The vibratory gyroscope according to claim 1, wherein a protruding portion symmetrically protruding in one plane with respect to the drive arm is provided. 3. The vibrator according to claim 1, wherein the vibrator is quartz, LiTaO ₃ single crystal, LiNbO ₃ single crystal, or Li (Nb, Ta) O _3.
3. The method according to claim 1, wherein the single crystal is used.
The described vibration gyroscope.