JPH0786415B2 - Vibrating gyro - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vibration gyro that detects Coriolis force for the purpose of detecting angular velocity.

[Conventional technology]

A conventional vibration gyro of this type is shown in FIG. 7, for example.

This is two arm members that extend parallel to each other in the Z-axis direction of the three-dimensional coordinate system and are positioned at a predetermined interval in the Y-axis direction.
A drive vibrator 7 formed by integrally connecting the lower end portions of 4,5 with a base portion 6 is fixed to a base 9 via a support member 8, and the base portion 6 of the drive vibrator 7 is fixed. , And is provided with a detecting means 10 projecting in the X-axis direction.

In such a vibrating gyro, for example, an AC voltage is applied to the driving means 11 and 12 to cause the arm members 4 and 5 to vibrate symmetrically in the Y-axis direction by a piezoelectric method, an electromagnetic method, or the like, while driving the driving vibrator 7. When it is rotated around the Z-axis at an angular velocity ω, each arm member 4 and 5 moving at a velocity V at a certain moment X,
Axial and mutually opposite Coriolis forces Fc are generated.

Here, since the speed V of the arm members 4 and 5 changes alternately,
The Coriolis force Fc is generated in a form modulated by the frequencies of the arm members 4 and 5, and the drive vibrator 7 is torsionally vibrated around the Z axis with respect to the base 9, and the torsion angle is , Coriolis force Fc and, in turn, proportional to angular velocity ω.

Therefore, in this conventional device, the magnitude of the torsional vibration is
The detection means 10 protruding in the X-axis direction is used for detection by a piezoelectric method, an electromagnetic method, or the like. For example, in a piezoelectric method using a bimorph element or the like, torsional vibration is converted into bending vibration of the detection means 10. However, the charge generated by the bimorph element is extracted as a voltage and detected according to the amount of bending.

[Problems to be Solved by the Invention]

However, in such a conventional technique, the vibration of the arm members 4 and 5 in the Y-axis direction of the base member 6 is caused by the unbalance of the mass and the length of the arm members 4 and 5. Detection means due to causing unwanted vibration
Since 10 will output a signal generated by the unnecessary vibration, even if the angular velocity ω is zero, a state as if the Coriolis force is detected, that is, an offset is generated, There is a problem in that the S / N ratio and, eventually, the detection sensitivity are lowered.

In order to reduce such an offset, a method is generally adopted in which the output of the detection means 10 is subjected to synchronous detection, rectification to direct current, and the remaining direct current component is added to or subtracted from a separately provided reference voltage to make it zero. There is. However, since the sensitivity of this detection means 10 changes subtly with changes in the ambient temperature,
Again, a sufficient and effective reduction in offset was virtually impossible.

Moreover, in the related art, there is a problem that the detection means 10 protrudes in the X-axis direction, the structure becomes complicated, the apparatus becomes large, and the apparatus cost increases.

The present invention advantageously solves the problems of the prior art, and provides a vibration gyro having a simple structure, a small size, and a low cost, and a high sensitivity with an excellent S / N ratio.

[Means for Solving the Problems]

The vibrating gyroscope according to the present invention is provided with a support member projecting in the Z-axis direction at a base portion of a driving vibrator including two arm members and a base portion, preferably at a central portion thereof.
At least a sensing means constituted by providing an electrode on at least one side surface of the support member, the piezoelectric material extending along the Z-axis direction, and being provided on each of the opposing surfaces parallel to the Z axis. One of them is arranged so as to be biased in one of two directions orthogonal to the Z axis of the support member, and one electrode is fixed in contact with the support member, or the detection means. In particular, an electrode is provided on each of the opposing surfaces of the piezoelectric material having substantially the same width as the one side surface of the support member and parallel to the Z axis, and at least one of these electrodes is orthogonal to the electrode surface. In addition, the detecting means is divided into two parts by an imaginary plane parallel to the Z axis, and one of the electrodes is fixed in contact with the supporting member.

[Work]

First, as shown in FIG. 8, when a case where a rectangular parallelepiped-shaped columnar member 14 protruding from the base 13 in the Z-axis direction is twisted by receiving a couple Mt, the columnar member 14 is traversed. When the surface dimension is 2b × 2h, the shear stress τw in the U direction and the shear stress τu in the W direction at an arbitrary point P (u, w) in the cross section as shown in FIG. , Given in.

Here, when an electric displacement D generated when a response T and an electric field E are applied to the piezoelectric material is expressed by an equation, If lead zirconate titanate is used as an example of the piezoelectric material, the electric displacement when only the stress T is applied is It is represented by.

Here, it is assumed that the applied stresses T _{1 to} T ₆ act in the directions shown in FIGS. 10 and 11, and the piezoelectric material is polarized in the third axis direction as shown by the white arrow. It is assumed that

From this, for example, when electrodes are provided on the respective surfaces orthogonal to the first axis, the electrical displacement D _{1 in} the first axis direction is D ₁ = d ₁₅ T ₅ (5) Functions as a detection means that generates electric charges only in the electrode by the shear stress T ₅ around the second axis and is insensitive to other stresses T ₁ , T ₂ , T ₃ , T ₄ , T ₆ . become.

Therefore, when the piezoelectric material polarized in the Z-axis direction is bonded to the side surface of the columnar member 14 shown in FIG. 8, the voltage material is changed in the U direction or W depending on the bonding surface to the columnar member 14. Generates an electrical displacement corresponding to the directional shear stress.

By the way, as is clear from the equations (1) and (2),
In the UW coordinate system of FIG. 9, the first quadrant 15, the third quadrant 17, and the second quadrant
Shear stresses τw and τu of quadrant 16 and fourth quadrant 18 respectively.
Since the polarities are different from each other, if a piezoelectric material is simply bonded to the entire surfaces u ₁ and u ₂ orthogonal to the U direction in FIG. 9, even if the shear stress τw is generated, the electric displacement is It becomes zero as a whole, and no charge is generated at the electrodes. Similarly, if the piezoelectric material is simply bonded to the entire surface orthogonal to the W direction, electric charges due to the shear stress τu will not be generated in the electrodes.

Therefore, in the present invention, basically, the detecting means mainly composed of the piezoelectric material polarized in the Z-axis direction is provided on at least one of the (a) surfaces w ₁ and w ₂ on the surface u ₁ side or u side. ₂
(B), or at least one of the surfaces u ₁ and u ₂ is biased to the surface w ₁ side or the surface w ₂ side to form a simple structure, which is small and inexpensive. The vibration gyro is realized, and the influence of the imbalance of the arm member is effectively removed, and the detection sensitivity is sufficiently improved.

Here, in order to output the electric displacement more effectively, the detecting means is joined to the half of the surface w ₁ or the surface w ₂ or the surface u ₁ or u ₂ with the center in the width direction as a boundary. It is preferable.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention, in which the same parts as those described in the prior art are designated by the same reference numerals.

That is, reference numerals 4 and 5 denote arm members that extend in parallel to each other in the Z-axis direction and are positioned at a predetermined interval in the Y-axis direction, and 6 indicates those arm members 4 and 5. Shows the base parts integrally connected at the lower end. Also, 7
Indicates a drive vibrator including the arm members 4 and 5 and the base portion 6. The drive vibrator 7 is fixed to the base 9 by a support member 8 protruding from the base portion 6 in the Z-axis direction. There is.

Here, in this example, the vibrating gyro is configured by joining the detecting means 22 to the side surface y ₁ of the support member 8 which is orthogonal to the Y axis while being biased in the X axis direction.

As described in the prior art, this vibrating gyro is provided with the detecting means 22 along the side surface y ₁ of the support member 8 along the side surface y ₁ thereof without providing the detecting means 10 so as to project from the base portion 6 in the X-axis direction. It can be manufactured by joining, therefore the structure of the device can be simplified, the device itself can be made small and inexpensive, and the device can be assembled very easily.

Moreover, in this vibration gyro, the detection means 22 functions to detect the torsion moment Mt acting on the support member 8 due to the generation of the Coriolis force Fc. Even if unnecessary vibrations in the Y-axis direction occur in the base portion 6 due to imbalance in length, etc., the effect is effectively prevented from leaking into the detection signal without using special means. Then, the detection sensitivity can be greatly improved.

By the way, applied in this way, the torsion moment Mt
The detection means 22 for detecting the action of the UWZ is shown in FIG.
As shown in the coordinate system, the piezoelectric material 19 having a rectangular parallelepiped shape is polarized in the Z-axis direction, and
It can be constructed by providing electrodes 20 and 21 on opposite surfaces orthogonal to the W axis. This detection means 22 in the illustrated example is a support member 8 preferably made of an elastic material.
Is joined to _one side surface w ₁ orthogonal to the W axis while being biased toward the surface u ₁ side, and by such an arrangement, the detection means 22 is caused by the twisting moment Mt acting on the support member 8. Electric charges are generated based on the generated shear stress τu in the W-axis direction.

Therefore, under such a condition, the both arm members 4 and 5 are symmetrically vibrated in the Y-axis direction by the application of the AC voltage to the driving means 11 and 12, and the vibrating gyro is rotated at the angular velocity ω about the Z-axis. When rotated, the detection means 22 can detect the torsion moment Mt acting on the support member 8 based on the Coriolis force Fc.

In the vibration gyro shown in FIG. 1, the arm members 4,
5, the base portion 6 and the support member 8 do not necessarily have to be an integral structure, and may be configured to be interconnectable.

Further, the joining of the detecting means 22 is not limited to that shown in FIGS. 1 and 2, and for example, the detecting means 22 shown in FIG.
Disposing it so as to be biased to the opposite side of the side surface w ₁ (that is, the surface u ₂ side), and instead of or in addition to the detecting means 22, disposing the detecting means 22 also on the other side surface w _2. Or both sides
It is also possible to arrange two sensing means 22 in parallel with each other for each of w ₁ and w ₂ , which means that the sensing means 22 are arranged on the surfaces u ₁ and / or u _2. The same applies to the case.

FIG. 3 is a perspective view showing another embodiment of the vibrating gyroscope, which is configured such that the support member 8 is made of a plate-shaped material and that the support member 8 is provided on each surface orthogonal to the Y axis. The detection means 22 is provided.

As shown in the UWZ coordinate system in FIG. 4, the detecting means 22 of this example extends the piezoelectric material 19 along the plate-shaped support member 8 and has a width almost equal to that of the support member 8 in the Z-axis. A small electrode that is polarized in the direction and has electrodes 23 and 26 respectively provided on the respective surfaces of the piezoelectric material 19 which are orthogonal to the W axis, and one of the electrodes 23 is divided into two in the WZ plane. It is configured by setting 24,25,
In the illustrated applied state in which the detection means 22 is joined to the respective surfaces w ₁ and w ₂ of the support member 8 orthogonal to the W axis, in appearance, an elastic plate is sandwiched by general thickness vibrators. Similar to bimorph.

Here, the vibrating gyro shown in FIG. 3, which is obtained by applying the detecting means 22 in this way, is
It can function similarly to that shown in FIG.

In this case, the small electrodes 24, 24 and the small electrodes 25, 25 positioned diagonally with respect to the support member 8 generate charges of opposite polarities due to the action of the torsion moment Mt.

By the way, as shown in FIG. 4, the detecting means 22 can be constructed by dividing only the electrode 26 on the support member side into two, or by dividing both electrodes 23, 26 into two. It is also possible to use it by joining it to only one surface of the support member 8 orthogonal to the W axis. And further, the detection means
Instead of the above, 22 can also be used by joining it to at least one of the surfaces u ₁ and u ₂ orthogonal to the U axis in FIG. 4, and in this case, the detecting means. 22 generates an electric charge based on the shear stress τw in the U-axis direction.

When the detecting means 22 that can be configured as described above is applied, for example, as shown in FIG. Even if the flexural vibration as shown in FIG. 5 is generated, as described above, the detecting means 22 is not sensitive to the stress caused by the flexural deformation in principle, so that the vibration shown in FIG. Like the gyro, you can almost ignore the effect of the imbalance.

Therefore, according to the present invention, it is possible to widen the allowable range of unbalance between the arm members 4 and 5, and it is possible to greatly improve the production efficiency in mass production.

FIG. 6 is a perspective view showing still another embodiment of the present invention. This is for the purpose of reducing the occupied space in the Z-axis direction and the drive vibrator 7 is different from the above-mentioned embodiments. Are in opposite postures, and the supporting members 8 are provided so as to project between the respective arm members.
The detection means 22 is joined to the.

With such a vibration gyro, the detection means 22
Can bring about the same effect as each of the above-described embodiments.

〔The invention's effect〕

Thus, according to the present invention, as is clear from the above description, the offset amount resulting from the imbalance of the arm members can be significantly reduced, and the sensitivity of the device can be greatly improved, and the imbalance can be improved. It is possible to improve the production efficiency by widening the allowable range of.

Moreover, according to the present invention, the detecting means is joined to the supporting member protruding in the Z-axis direction along the X-axis, so that X
The occupied space in the axial direction can be made sufficiently small to downsize the apparatus, and the structure can be made simple to effectively reduce the number of assembly work steps.

In addition, by surface-bonding the detection means to the support member,
The mechanical strength of the detection means can be increased to prevent damage to the detection means due to impact or the like.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a perspective view showing a configuration example of a detecting means, FIG. 3 is a perspective view showing another embodiment of the present invention, and FIG. Is a perspective view showing another configuration example of the detecting means, FIG. 5 is a front view showing the influence of imbalance of both arm members, and FIG. 6 is a perspective view showing yet another embodiment of the present invention. FIG. 7 is a perspective view showing a conventional example, and FIGS. 8 to 11 are views for explaining the operating principle of the present invention. 4,5 ... Arm member, 6 ... Base part, 7 ... Drive vibrator, 8 ... Support member, 9 ... Base, 19 ... Piezoelectric material, 20, 21, 23, 26 ... Electrode, 24,25 …… Small electrode.

Claims (2)

[Claims] 1. Two arm members extending parallel to each other in the Z-axis direction of a three-dimensional coordinate system and positioned at a predetermined interval in the Y-axis direction, and one end portion of each of these arm members. A drive oscillator is configured with a base portion that is integrally connected, and a support member that projects in the Z-axis direction is provided on the base portion of the drive oscillator, and extends along at least one side surface of the support member. At least one of the detecting means constituted by providing an electrode on one of the opposing surfaces of the piezoelectric material polarized in the Z-axis direction parallel to the Z-axis, is arranged in two directions orthogonal to the Z-axis of the supporting member. A vibrating gyroscope, which is arranged so as to be biased in one of the two directions, and in which one electrode is in contact with and fixed to a supporting member. 2. Two arm members extending parallel to each other in the Z-axis direction of the three-dimensional coordinate system and positioned at a predetermined interval in the Y-axis direction, and one end portion of each of these arm members. A drive oscillator is configured with a base portion that is integrally connected, and a support member that projects in the Z-axis direction is provided on the base portion of the drive oscillator, and extends along at least one side surface of the support member. An electrode is provided on each of the opposing surfaces of the piezoelectric material, which is polarized in the Z-axis direction and has substantially the same width as the one side surface, parallel to the Z-axis, and at least one of these electrodes serves as the electrode surface. A vibrating gyroscope in which a detection means is provided that is divided into two parts by a virtual plane that is orthogonal to each other and is parallel to the Z axis, and one of the electrodes is brought into contact with a support member and fixed.