JP3636412B2 - Vibrating gyroscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vibratory gyroscope using a tuning fork vibrator.
[0002]
[Prior art]
Conventionally, it is composed of a plurality of arms and a base part connecting the plurality of arms, and gives a driving vibration in a predetermined plane to the arm, and from the detected vibration corresponding to the applied rotational angular velocity perpendicular to the driving vibration. Various types of vibratory gyroscopes using tuning fork vibrators for obtaining rotational angular velocities are known. For example, Japanese Laid-Open Patent Publication No. 7-83671 discloses a vibratory gyroscope using a tuning fork vibrator having a structure in which a central drive arm and a total of three detection arms on its left and right are connected together at the base. Has been. FIG. 8 is a diagram showing a configuration of an example of such a conventional vibration type gyroscope. In the example shown in FIG. 8, the tuning-fork vibrator 51 constituting the vibratory gyros scope, the center of the drive arm 53, and the three arms of the detection arm 52, 54 which are disposed substantially parallel to the left and right The drive arm 53 and the detection arms 52 and 54 are integrally connected by a base 55.
[0003]
In the tuning fork vibrator 51 described above, the drive arm 53 is vibrated in the XZ plane by a drive means (not shown) provided on the drive arm 53. Then, the left and right detection arms 52 and 54 are resonated in the same XZ plane. In this state, when the rotational angular velocity ω acts around the symmetry axis Z of the tuning fork vibrator 51, Coriolis force f acts on the detection arms 52 and 54. Since the detection arms 52 and 54 vibrate in the XZ plane, vibration is induced in the detection arms 52 and 54 in the YZ plane. This vibration is detected by a detection means (not shown) provided on the detection arms 52 and 54, and the rotational angular velocity is measured.
[0004]
[Problems to be solved by the invention]
In the tuning fork vibrator 51 described above, all of the drive arm 53 and the detection arms 52 and 54 are driven by the vibration of the drive arm 53 and the resonance of the detection arms 52 and 54 caused by the vibration of the drive arm 53. Is vibrating. For this reason, it has been difficult to suppress the noise appearing in the detection vibration by the detection means provided in the detection arms 52 and 54 to a low level. That is, in the above-described conventional tuning fork vibrator 51, the distortion in the driving mode also affects the detection means, and appears as noise in the detection vibration of the detection means. In particular, in the vibration type gyroscope in which the tuning fork vibrator 51 is formed of a single crystal, there is a problem that the tendency becomes remarkable because piezoelectric constants exist in various directions of the piezoelectric single crystal. Further, in the tuning fork vibrator 51 described above, there is a high demand for further increasing the sensitivity while keeping the overall size of the tuning fork vibrator 51 as it is.
[0005]
An object of the present invention is to solve the above-described problems and to provide a vibration type gyroscope that has no influence of vibration in a driving mode on a detection signal and that has high sensitivity.
[0006]
[Means for Solving the Problems]
The vibration type gyroscope of the present invention is a vibration type gyroscope using a tuning fork type vibrator made of a piezoelectric single crystal, wherein a part of an arm constituting the tuning fork type vibrator is formed thinner than other parts, and a drive vibration mode The portion where the strain of the vibration is concentrated and the portion where the strain of the detection vibration mode is concentrated are different on each arm, and the detection means is provided in the portion where the strain of the detection vibration mode is concentrated. .
[0007]
In the present invention, a part of the arm constituting the tuning fork vibrator is formed to be thinner than the other part, and the part where the distortion of the driving vibration mode is concentrated and the part where the distortion of the detection vibration mode is concentrated are arranged on each arm. By adopting a configuration in which the detection means is provided in a part where the strain in the detection vibration mode is concentrated, the position where the detection means is provided in the detection arm is the maximum distortion due to the detection vibration in the detection vibration mode. It can be set as the position where the distortion resulting from the drive vibration in the drive mode does not concentrate. Therefore, when the tuning fork type vibrator is made of a constant elastic alloy such as Elinba alloy and a detection part made of a piezoelectric material is formed as a detection means, the tuning fork type vibrator is made of piezoelectric ceramics, quartz, LiTaO ₃ single unit. The detection unit in the case of forming a detection unit composed of a crystal and a LiNbO ₃ single crystal and including an electrode as a detection means has a detection vibration mode based on the Coriolis force when any detection unit is given a rotational angular velocity. Vibration can be efficiently used for detection, and the influence of noise based on drive vibration can be eliminated at the position where the detection unit is provided.
[0008]
The above-described operational effects of the present invention are as follows. When a LiTaO ₃ single crystal or a LiNbO ₃ single crystal having piezoelectric constants in various directions is used as a tuning fork type vibrator, the influence of the drive vibration in a considerably large drive vibration mode has been conventionally achieved. However, according to the present invention, this noise can be greatly reduced. In addition, by narrowing a part of the arm, even if the arm of the tuning fork vibrator of the present invention is the same size as the conventional arm, the detection amplitude is increased compared with the conventional tuning fork vibrator, and the amplitude Can be controlled, and the sensitivity can be increased without changing the size of the tuning fork vibrator.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a configuration of an example of a vibrating gyroscope according to the present invention. In the example shown in FIG. 1, a tuning fork vibrator 1 constituting a vibration gyroscope includes three arms 2 to 4 arranged substantially parallel to each other, and a base 5 that connects these three arms 2 to 4. It consists of. Of the three arms 2 to 4, the arms 2 and 4 at both ends constitute a detection arm, and the central arm 3 constitutes a drive arm. As a material of the tuning fork vibrator 1, a conventionally known constant elastic alloy such as an Elinba alloy, or a piezoelectric material such as piezoelectric ceramics, crystal, LiTaO ₃ single crystal, LiNbO ₃ single crystal can be used. However, the effects of the present invention are great when a single crystal such as a LiTaO ₃ single crystal or a LiNbO ₃ single crystal is used. In the example shown in FIG. 1, an example in which a LiTaO ₃ single crystal is used as the tuning fork vibrator 1 is shown.
[0010]
The operation of the tuning fork vibrator 1 of the vibration gyroscope of the present invention described above is the same as the operation of a conventionally known tuning fork vibrator. That is, first, the drive arm 3 is vibrated in the XZ plane by the drive electrodes 11-1 to 11-4 as drive means provided on the drive arm 3. Then, the left and right detection arms 2 and 4 are resonated in the same XZ plane. As a result, vibration in the drive vibration mode as shown in FIG. In this state, when the rotational angular velocity ω acts on the axis of symmetry C of the tuning fork vibrator 1, the Coriolis force f acts on the detection arms 2 and 4. Since the detection arms 2 and 4 vibrate in the XZ plane, the detection arms 2 and 4 are induced to vibrate in the YZ plane. Thereby, the vibration of the detection vibration mode as shown in FIG. This detection mode vibration is detected by the detection electrodes 12-1 to 12-4 separately provided on the detection arms 2 and 4, and the rotational angular velocity is measured. FIG. 3 shows the wiring state of each electrode.
[0011]
What is important in the above-described vibratory gyroscope of the present invention is that the shape of each arm of the drive arm 3 and the detection arms 2 and 4 constituting the tuning fork vibrator 1 is made thinner than the other parts. is there. That is, in the example shown in FIG. 1, when the direction extending upward from the base portion 5 of each arm is the longitudinal direction and the direction perpendicular thereto is the width direction, the width direction is within the vibration surface (XZ plane) in the drive vibration mode. In the vibration plane (YZ plane) in the detection vibration mode, a part of the shape in the width direction is made thinner than the other parts. Specifically, in the example shown in FIG. 1, the configuration of each arm of the drive arm 3 and the detection arms 2 and 4 is changed to an arm base 2-1 having a predetermined length in the longitudinal direction from an end contacting the base 5. 3-1 and 4-1 are formed to have the same thickness as the base 5 in the XZ plane, and the arm narrow portions 2-2, 3- following the arm bases 2-1, 3-1, 4-1 are formed. The thicknesses 2 and 4-2 are configured to be thinner than the thicknesses of the arm bases 2-1, 3-1, and 4-1, in the YZ plane. The shapes of the drive arm 3 and the detection arms 2 and 4 are all the same.
[0012]
In the tuning fork type vibrator 1 used in the above-described vibration type gyroscope of the present invention, the center of vibration distortion in the YZ plane of the detection vibration mode is the A part of the detection arms 2 and 4 and the drive arm 3, and the drive vibration The center of vibration distortion in the XZ plane of the mode is the B part of the detection arms 2 and 4 and the drive arm 3. Therefore, when considering the detection arm 2 or 4, the portion B where the strain in the driving vibration mode is concentrated is different from the portion A where the strain in the detection vibration mode is concentrated. As a result, as shown in FIG. 1, the detection electrodes 12-1 to 12-4 are formed in the portion A where the strain of the detection vibration mode is concentrated, so that the vibration in the detection vibration mode is efficiently used for detection. On the other hand, since the distortion of the vibration in the driving vibration mode is not concentrated on this portion, the vibration in the driving vibration mode is not adversely affected. In the example shown in FIG. 1, in the drive arm 3, the drive electrodes 11-1 to 11-4 are provided in the portion B where the strain in the drive vibration mode is concentrated.
[0013]
FIG. 4 is a diagram showing the configuration of another example of the vibrating gyroscope of the present invention. In the example shown in FIG. 4, the same members as those in the example shown in FIG. The example shown in FIG. 4 differs from the example shown in FIG. 1 in that the detection arms 2, 4 and the drive arm 3 have the same shape in the width direction in the vibration plane (YZ plane) in the detection vibration mode. In the vibration plane (XZ plane) in the drive vibration mode, a part of the shape in the width direction is made thinner than the other part. Specifically, in the example shown in FIG. 4, the configuration of each arm of the drive arm 3 and the detection arms 2, 4 is changed to an arm base 2-1 having a predetermined length in the longitudinal direction from the end connected to the base 5. 3-1 and 4-1 are formed to have the same thickness as the base 5 in the YZ plane, and the arm narrow portions 2-2, 3- following the arm bases 2-1, 3-1, 4-1 are formed. The thicknesses 2 and 4-2 are made thinner than the thicknesses of the arm bases 2-1, 3-1, and 4-1 in the XZ plane. In the example shown in FIG. 4, the same effect as the example shown in FIG. 1 can be obtained. 5A and 5B show examples of the drive vibration mode and the detection vibration mode of the example shown in FIG. 4, and FIG. 6 shows the wiring state of each electrode.
[0014]
FIGS. 7A to 7H are diagrams showing configurations of still other examples of the detection arm and the drive arm, respectively. In the example of FIGS. 7A to 7H, the example of the detection arm 2 is shown, but the configurations of the other detection arms 4 and the drive arm 3 are also the same. . 7A to 7D, similarly to the example of FIGS. 1 and 4, the arm 2 is thinned from both sides to provide the arm base portion 2-1 and the arm narrow portion 2-2. An example is shown. 7 (e) to 7 (h), unlike the example of FIGS. 7 (a) to 7 (d), the arm base 2-1 and the arm thin portion are made thin by reducing the thickness only from one side with respect to the arm 2. The example which provided the shape part 2-2 is shown. In any example, the effects of the present invention can be obtained in the same manner.
[0015]
In the above-described example, the example in which the three arms 2 to 4 are used as the tuning fork type vibrator 1 is shown. However, the number of arms is not limited to three, but other numbers such as four and five are available. It goes without saying that the present invention can be applied even in the number of lines.
[0016]
【The invention's effect】
As is apparent from the above description, according to the present invention, a part of the arm constituting the tuning fork vibrator is formed to be thinner than the other parts, and the part where the distortion of the driving vibration mode is concentrated and the distortion of the detection vibration mode The position where the detection means is provided on the detection arm is set to be the detection vibration in the detection arm. It is possible to set the position where the distortion caused by the mode detection vibration is maximum and the distortion caused by the drive vibration in the drive mode is not concentrated. Therefore, in the detection means, the vibration in the detection vibration mode based on the Coriolis force when the rotational angular velocity is given can be efficiently used for detection, and the influence of noise based on the drive vibration is eliminated at the position where the detection means is provided. High sensitivity measurement can be performed.
[0017]
In addition, since a part of the arm is made thin, even if the arm of the tuning fork type vibrator of the present invention is the same size as the conventional arm, the detection amplitude is increased compared to the conventional tuning fork type vibrator, The amplitude can also be controlled, and the sensitivity can be increased without changing the size of the tuning fork vibrator.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an example of a tuning fork vibrator used in a vibration gyroscope of the present invention.
2A and 2B are diagrams showing examples of a drive vibration mode and a detection vibration mode in the example shown in FIG. 1, respectively.
3 is a diagram showing a wiring state of each electrode in the example shown in FIG. 1;
FIG. 4 is a diagram showing a configuration of another example of the vibration type gyroscope of the present invention.
5A and 5B are diagrams illustrating examples of a driving vibration mode and a detection mode in the example illustrated in FIG. 4, respectively.
6 is a diagram showing a wiring state of each electrode in the example shown in FIG.
FIGS. 7A to 7H are views showing other shapes of the arm in the present invention, respectively.
FIG. 8 is a view showing a configuration of an example of a tuning fork type vibrator used in a conventional vibration type gyroscope.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tuning fork type vibrator, 2, 4 detection arm, 3 drive arm, 5 base, 11-1 to 11-4 drive electrode, 12-1 to 12-4 detection electrode

Claims (6)

In a vibratory gyroscope using a tuning fork vibrator made of a piezoelectric single crystal, a part of the arm constituting the tuning fork vibrator is made narrower than the other parts, and the strain-concentrated part of the drive vibration mode and the detected vibration A vibration type gyroscope characterized in that a portion where the strain of the mode is concentrated is a different portion on each arm, and a detection means is provided in a portion where the strain of the detection vibration mode is concentrated. In the vibration plane in the drive vibration mode, the shape in the width direction is the same in the vibration plane in the drive vibration mode, and the vibration plane in the detection vibration mode is the same when the arm is perpendicular to the longitudinal direction in which the arm extends. The vibrating gyroscope according to claim 1, wherein a part of the shape in the width direction is made thinner than the other part. When the width of the arm is perpendicular to the longitudinal direction in which the arm extends, the shape in the width direction is the same in the vibration plane in the detection vibration mode, and the vibration plane in the drive vibration mode. The vibrating gyroscope according to claim 1, wherein a part of the shape in the width direction is made thinner than the other part. The vibrating gyroscope according to any one of claims 1 to 3, wherein the arm is gradually thinner in the longitudinal direction. The vibrating gyroscope according to claim 4, wherein the arm gradually becomes thinner from an end contacting the base toward a tip. Vibratory gyroscope according to any one of claims 1 to 5, the strain of the driving vibration mode is provided drive means at a portion concentrated.

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