JPH0382910A - Vibration gyroscope - Google Patents

Abstract

PURPOSE:To make it possible to detect torsional moment at high sensitivity by arranging a sliding vibrator wherein a piezoelectric material is polarized in the direction perpendicular to the axis Y and electrodes are formed on the surfaces which are perpendicular to the axis Y as a part of a fixing means, and omitting a part of the electrode at least on one surface of said vibrator. CONSTITUTION:In a sliding vibrator 1, piezoelectric material 14 in the shape of a rectangular parallelopiped which is constituted of planes x1, x2, y1, y2, z1 and z2 is polarized in the direction which forms an angle alpha with the axis X. Electrodes 15a and 16a are formed on the planes y1 and y2. An arbitrary point on the plane y1 is made to be Q1. A point facing Q1 on the plane y2 is made to be Q2. Positions which are symmetrical to the points Q1 and Q2 with repect to the axis Y are made to be Q1' and Q2'. Then the electrode part on at least one of the points Q1 and Q2 or at least one of the points Q1' and Q2 is omitted. When said vibrator 1 is attached to one surface of a base stage 2 which is perpendicular to the axis Y, a fixing means 3 is formed. The fixing means 3 is linked to a vibrator 5 by fixing the one end part of the vibrator 5 to the vibrator 1 with a bonding agent and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vibrating gyroscope that determines angular velocity by detecting Coriolis force.

[Conventional technology]

As a conventional vibrating gyroscope of this kind, for example, there is a piezoelectric type as shown in FIG. Two bimorph, unimorph, or other vibrators 5 made of a piezoelectric material are fixed in a tuning fork shape, and at the free end of each of the vibrators 5, a respective detection means 6 also made of a piezoelectric material is provided. It is constructed by fixing each of the wide surfaces of the vibrator 5 so that it faces in a direction perpendicular to that of the vibrator 5.

When using such a vibrating gyro, please
An alternating current voltage is applied to the vibrator 5 to cause the vibrator 5 to vibrate symmetrically in the direction of the solid arrow in the figure (Y-axis direction). Note that methods for producing such symmetrical vibration include applying an AC voltage to both vibrators 5, as well as applying an AC voltage to only one vibrator 5 and using the other vibrator 5 as a vibration monitor. There are methods of controlling the vibration state and thereby stabilizing the vibration, but in any of these methods, the vibrator 5 is vibrated in a resonant state to increase the vibration amplitude in order to strengthen the Coriolis force, which will be described later. It is said that

Next, by rotating the vibrating gyroscope around the Z-axis at an angular velocity ω while the vibrator 5 is vibrating, the detecting means 6 is caused to deflect in the direction of the broken line arrow (X-axis direction) in the figure. An acting Coriolis force Fc is produced, which results in the generation of a voltage in the sensing means 6.

Here, since this generated voltage is proportional to the magnitude of the Coriolis force Fc, by measuring the generated voltage,
The angular velocity ω can be determined.

Incidentally, in boat fishing, a device has been devised to improve efficiency by providing a support rod 7 on the fixing means 4 to support the entire device.

[Problem to be solved by the invention]

However, in such conventional technology, the structure in which the detection means 6 is connected to the tip of the vibrator 5 increases the size of the device and requires wiring for supplying alternating current to the vibrator 5. There is a drawback that the wiring for extracting the signal voltage from the detection means 6 is complicated, and in particular, the wiring for the detection means 6 is difficult to route.

That is, the detection means 6 always detects a distance of approximately several μm to 100 μm.
The mass and elastic modulus of the wire for extracting the signal voltage, as well as the state of deformation, etc., have a major influence on the vibration of the vibrator 5, which affects the detection sensitivity. Therefore, it is necessary to glue the wire to the side surface 5' of the vibrator 5, extend it to the vicinity of the fixing means 4 with low vibration, and pull it out from there to a predetermined connection terminal. Measures have been taken to reduce the influence of the wire by extending the connection terminal to a position near the detection means 6 and shortening the length of the wire.

However, according to this, a significant reduction in the manufacturing efficiency of the vibrating gyroscope was unavoidable.

On the other hand, if the wide surface of the vibrator 5 and the wide surface of the detection means 6 are not exactly orthogonal, a vibration component in the Y-axis direction will leak into the detection signal from the detection means 6. At the same time, the detection accuracy itself decreases. By the way, in a structure in which the end face of the vibrator 5 and the end face of the detection means 6 are directly connected as shown in the figure, sufficient connection accuracy cannot be expected by simply fixing them with adhesive. do not have.

Therefore, a method has been proposed in which the transducer 5 and the detection means 6 are connected via a coupling member 8 as shown in FIG. By adhering a portion of each electrode of the means 6 to each of the surfaces provided on the connecting member 8 and facing in mutually orthogonal directions, the vibrator 5 and the sensing means 6 can be connected relatively easily. It becomes possible to connect with a high perpendicularity. However, in this case, since the vibrator adhesive surface and the detection means adhesive surface of the connecting member 8 are oriented in directions perpendicular to each other, it is difficult to bond the vibrator 5 and the detecting means 6 to the connecting member 8. To do this at the same time, until the adhesive hardens,
The structure of the jig required to accurately position and hold each of the vibrator 5 and the detection means 6 on the connecting member 8 in a predetermined relative relationship becomes complex, and the jig becomes large and difficult to work with. Moreover, when such bonding work is performed in two steps, the number of work steps increases significantly.

[Background technology]

In general, when a force F as shown in FIG. 23 is applied to a piezoelectric bimorph element whose one end is fixed in a cantilevered manner to cause it to deflect, taking the series bimorph 13 as an example, approximately V = (3gs+1!-F) / (2mu ・
W) g3. : Voltage output coefficient l : Length t : Thickness W : Generates voltage V expressed as width. On the other hand, as shown in Fig. 24, a force F is applied to the piezoelectric material ■4, which acts as a sliding oscillator and is polarized in the direction shown by the white arrow and has electrodes (not shown) on the top and bottom surfaces. Similarly, in the case of shear deformation, V' - (t' ・g + s ・F)
/ (j!'・w')gI5: Voltage output coefficient β': Length β': Thickness W' A voltage V' expressed by two widths is generated.

Here, taking a piezoelectric ceramic material such as lead zirconate titanate (PZT) as an example, the voltage output coefficient g ffl+ g +5 is the ratio g+s/
g3+=3, and although the sliding vibrator is more advantageous in terms of voltage output coefficient with respect to the applied force, the thickness t, t' width w, w', and length j of each piezoelectric material
! , A', it is clear from the above two equations that the slip oscillator is not always advantageous in terms of output voltage.

However, as shown in FIG. 25, one end of the driving vibrator 5 is connected to the fixing means 4, and while an AC voltage is applied to the vibrator 5 to vibrate it in the Y-axis direction, the fixing means 4 is moved to the Z direction. When it is rotated around the axis at an angular velocity ω, the generated Coriolis force Fc causes not only the shear stress shown by the broken line arrow but also the torsional stress shown by the solid line arrow on the connection part 9 of the fixing means 4 with the vibrator 5. A moment M is applied to generate a force in a direction that twists the fixing means 4. Therefore, by actively utilizing this torsional moment M to measure the Coriolis force Fc, it is possible to improve the workability in manufacturing the vibrating gyroscope, and also to realize miniaturization of the vibrating gyroscope. Furthermore, high measurement accuracy can be achieved.

This invention was made with attention to this point,
This provides a new vibration gyroscope that has never existed before.

To explain this in more detail, as shown in FIG. 26, the base 10 and the arm 12 have a rectangular outline with a long side length a and a short side length b as shown in FIG. Intermediate member 1
1, when a force F in the X-axis direction is applied to the tip of the arm 12, the intermediate member 11 receives a shear stress τ-
Along with F/a-b, a torsional moment M=F-L' with the Y-axis as the rotation axis acts, and this torsional moment M
, the intersection point O of the coordinate axes x, y, and z is placed on the intermediate member 11.
A torsional shear stress τ′ centered at is generated. This torsional shear stress τ' reaches its maximum at the midpoint A of the long side of the intermediate member 11 shown in FIG. 27, and its value is r' max=F - L' /cx -a -b2α:
It is a constant determined by the ratio a/b of the length of the long side and the short side.

This r'max is expressed as r'max/r −L for τ
'/a-1), it is extremely effective to measure the torsional shear stress τ'.

0 Here, in order to simplify the explanation, the intermediate member 11 is assumed to have a rectangular contour shape with a>b, but if a<1) in FIG. If a=b, the midpoints A and B4
This causes the maximum torsional shear stress to act. Incidentally, the torsional shear stress τ' exhibits a distribution in which it becomes zero at the center O and the four corners of the intermediate member 11, and has a high value at the midpoint of the sides.

As described above, as a result of the torsional shear stress τ' acting on the intermediate member 11 in addition to the shear stress τ, the intermediate member II is subjected to shear strain due to the shear stress τ, as shown in FIG. T and shear strain γ' due to torsional shear stress τ'. Here, looking at the relationship between tensile and shear stress and electric displacement, the electric displacement generated when stress T and electric field E are applied to a piezoelectric material is expressed as follows, and zirconium titanate is used as a piezoelectric material. Taking acid lead as an example, it is expressed by the electrical change when only stress T is applied.

Note that here, the applied stress T, -T6 is the second
It is assumed that the piezoelectric material is acting in the directions shown in FIGS. 9 and 30, and that the piezoelectric material is polarized in the third axis direction as shown by the white arrow.

2 From the above, when an electrode is provided on a plane perpendicular to the first axis, the electrical displacement in the first axis direction due to stress is: DI"dls・T.

This becomes a shear oscillator that generates electrical displacement in response to the shear stress T5 around the second axis.

Next, as shown in FIG. 31, a plane XI perpendicular to the X-axis
+XZ, a plane Y++ Yz perpendicular to the Y-axis, and a plane Zl+ZZ perpendicular to the Z-axis. Torsional shear stress τ in orthogonal planes
Consider the electrical displacement caused by the action of ′.

The direction of the torsional shear stress τ/p2 acting on the point P2 on the plane y2 of the piezoelectric material 14, which is polarized in a direction perpendicular to the Y axis and forming an angle α with the X axis, makes an angle β with the X axis. Then, the electric displacement from point PI to point P2 at jl M P r , P z connecting point P1 opposite to point P2 on plane yI and that point P2 is DI)"d+sτ
/p, CO8(α-β)3. In addition, at point P2', which is axially symmetrical to point P2 with respect to the Y axis, the direction of torsional shear stress forms an angle of (β + π) with respect to the X axis, and its magnitude acts on point P2. Since the stress τ'pz is equal to the stress τ'pz, the point p2 on the plane g1
An area P 1 connecting the point p, / opposite to 1 and the point P2'
The electrical displacement from point Pt' to point P2' at '+P2' is Dp'=d, 5τ'Pz COS (α-β-π)=d
, τ1p2CO3(α-β), and the area P, ,P2 and the area p , / , p 2
/ generates electric displacements of equal magnitude and different polarity.

Therefore, plane! +'++ Even if electrodes are formed on the entire surface of each Yt, the generated charges cancel each other out, so no voltage is generated between the electrodes due to the action of the torsional moment M. Even if the intermediate member 11 shown in FIG. Unable to obtain detection sensitivity.

4 Therefore, the present invention makes it possible to detect the torsional moment M with high sensitivity by preferentially extracting a specific electric signal, and also enables the detection of high-precision vibration that is small and highly productive. Serve gyros.

[Means to solve the problem]

In particular, the vibrating gyroscope of the present invention polarizes the piezoelectric material in a direction orthogonal to the Y-axis of a three-dimensional coordinate system, and
A shear vibrator formed by forming electrodes on each surface orthogonal to the Y-axis of the piezoelectric material is disposed as at least a part of a fixing means for fixing one end of the vibrator, and at least One side of the electrode is partially missing.

Note that instead of missing a part of the electrode on at least one side, the electrode on at least one side may be divided into a plurality of parts, or the shear oscillator itself may be divided into a plurality of parts in a plane perpendicular to the Y-axis. is also possible.

Preferably, two vibrators are attached to the fixing means in a tuning fork shape.

[For production]

This vibrating gyroscope detects the Coriolis force using both the simple shear stress acting on the sliding oscillator and the torsional shearing stress of the sliding oscillator based on the torsional moment generated by the Coriolis force. As shown in , the detection sensitivity can be greatly improved compared to the case where the deflection force of the detection means 6 is detected, and this means that when a part of the electrode on at least one side is missing, The same applies to any case where the slip oscillator itself is divided into a plurality of parts.

Further, in a vibrating gyroscope in which two driving vibrators are attached to a fixing means in a tuning fork shape, the detection sensitivity can be doubled and the S/N ratio with respect to external vibration noise can be improved.

On the other hand, in this vibrating gyroscope, by disposing the sliding oscillator as at least a part of the fixing means for the driving oscillator, the detection means 6 mentioned in the prior art can be made unnecessary, and the device can be sufficiently miniaturized. In addition, by concentrating the electrodes near the fixing means, inconveniences associated with routing the wire can be effectively eliminated.

Furthermore, when assembling the vibrating gyroscope, one end of the drive vibrator can be surface-bonded to the fixing means, making it extremely easy to position both of them and maintain precision. It becomes possible to supply vibration gyroscopes with small size and stable performance at low cost and in large quantities.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a perspective view illustrating a slip oscillator, which is the essential part of the present invention.

This polarizes the rectangular hexahedral piezoelectric material 14 composed of planes XI+Xl+3'I+y2121122 in a direction forming an angle α with the X axis, and also polarizes planes y+, ! An electrode 15a is formed on each of I'2 as shown by diagonal lines in the figure.

7 16a, let any point on the plane y1 be Ql, and the opposing point on the plane y2 be Q2, and for each of these points Q, Qz, the positions symmetrical to the Y axis are Q1. ', Q2', the points Q +, Q
2 or at least one of points Q1' and Q2', the figure shows a shear vibrator 1 in which the electrode portion at point Q2 is missing.

Such a sliding vibrator 1 constitutes a fixing means 3 by attaching it to one surface of a base 2 orthogonal to the Y-axis, as shown in FIG. 4, for example. The connection of the vibrator 5 to the fixing means 3 is as follows: - one end of the vibrator 5;
In the figure, this can be done by fixing the lower end to the sliding vibrator 1 with adhesive or the like.

Here, when an AC voltage is applied to the vibrator 5 to force it to vibrate in the Y-axis direction, and at the same time, the fixing means 3 is rotated around the Z-axis at an angular velocity ω to generate a Coriot force Fc. , the piezoelectric material 14 has Y due to the shear moment M.
Torsional shear stress in the plane perpendicular to the axis acts, and the electrode 15
Between a and 16a, an electrical displacement occurs between points Q1' and Q2' that is not canceled by the electrical displacement that occurs between points 8Q + and Q2, and this is the voltage between the two electrodes. Detected.

However, if the electrode is removed at a location where the polarization direction and the direction of action of torsional shear stress are perpendicular, that is, at a location where no electrical displacement occurs, two locations where electrical displacement of equal magnitude and opposite polarity occurs will occur. If the electrode is missing in each case, no electrical displacement will be detected.

In addition, in the electrode configuration as described above, a highly practical configuration in which the detection sensitivity to the torsional moment M is maximum is when the polarization angle α is 0 π/2 π or 3/2 π,
The electrodes on at least one surface of the plane y++ yz are formed only on half of those surfaces, and the missing edge of the half electrode is parallel to the polarization direction, as shown in FIG. An example is shown in FIG. In all of these, the polarization angle α=0, and the configuration shown in FIG. 2 has the electrode 16b on the plane y2 having an area half that of the plane y2, and is parallel to the polarization direction. Also,
The configuration shown in FIG.
5c and 16c are both half the area of those planes Y and Yz, and together with the missing edges 17c and 17, respectively.
d is parallel to the polarization direction.

5.6.7 are perspective views showing other application examples of the sliding oscillator, in other words, other embodiments of the invention.

FIG. 5 shows that the fixing means 3 is constructed by attaching sliding transducers I to two surfaces perpendicular to the Y-axis of the base 2, and two transducers 5 are attached to the lower ends of the fixing means 3. It is attached to the sliding vibrator 1 in a tuning fork shape, and the example shown in Fig. 6 is as follows.
- The fixing means 3 is constituted by sandwiching the two sliding transducers l between the bases, and each lower end of the two transducers 5 is attached to each surface of each base 2 perpendicular to the Y axis. is fixed in the shape of a tuning fork. In the example shown in FIG. 7, the fixing means 3 is composed of only the sliding vibrator 1.

For example, in the vibrating gyroscope shown in FIG. 5, the output voltages of the two piezoelectric materials 14 can be differentially extracted by configuring a detection circuit as shown in FIG. It is possible to improve the S/N ratio against external vibration noise, and also to reduce the Coriolis force Fc.
The detection sensitivity can be doubled.

Furthermore, as shown in FIG. 9, when the entire body is supported by a support rod 7 attached to the fixing means 3, the forced vibration of the vibrator 5 is stabilized and efficient operation under resonance is ensured. be able to.

Note that when using the slip oscillator 1 as shown in FIG. 3, the part where no electrode is formed is not necessarily necessary since the electrical displacement generated there cannot be used as a signal. As shown, electrodes 15c, 16
The portion not sandwiched by c may be constructed of other spacing members, or the spacing member 18 may be integrally formed with the base 2.

FIG. 11 is a diagram illustrating another slip oscillator. In the slip oscillator shown in FIG. 3, electrodes 15c, 16
In order to effectively utilize the electric displacement 1 that occurs in the part that does not form c, the polarization direction is set to the X-axis direction (α-〇), and the electrodes on the plane yI and the electrodes on the plane y2 are A punching pattern 19a parallel to the X axis,
19b, and electrodes 15d and 16
d and electrodes 15e and 16e are opposed to each other.

In this sliding oscillator 1, when a torsional moment M acts thereon, the difference between the electrodes 1.5d and 166 and the electrode 15e1
Since an electrical displacement with a different polarity occurs between 6e and 6e, by configuring a detection circuit as shown in FIG. /N ratio can be improved. Therefore, by constructing a vibrating gyroscope as shown in FIGS. 4 to 7 using this sliding vibrator, excellent performance can be exhibited.

Note that the direction of polarization, the position and orientation of the punched pattern are not limited to the illustrated example, and may be changed in various ways. It is also possible to combine the two without dividing them.

FIG. 13 is a perspective view illustrating still another slip oscillator, in which the polarization direction is the X-axis direction, and the two pieces are divided into two by a plane perpendicular to the Z-axis at the coordinate origin position. An electrode 15 is placed on each plane y++ plane y2 of the piezoelectric material 14.
f, 15g and 16f, 16g.

This sliding oscillator 1 increases the amount of charge generated by the torsional moment M by effectively extracting electrical displacement of opposite polarity under the circuit configuration shown in FIGS. 14 and 15, for example, and vibrates. It is possible to improve the S/N ratio with respect to noise.

By the way, the position and angle of one division in the polarization direction of the slip oscillator 1 can be changed as appropriate. Note that the division must be performed within a plane that intersects the circumferential planes y1 and y2 and is perpendicular to the Y axis.

FIG. 16 is a diagram showing an example of this, in which the piezoelectric materials 14 are divided into four pieces: two piezoelectric materials 14 with a polarization angle of α-0 and two piezoelectric materials 14 with a polarization angle of α-π/2. There are 3 things.

17 to 20 are diagrams showing common examples of the above-mentioned split sliding oscillator, here the oscillator shown in FIG. 13, and any of these vibrating gyroscopes can achieve excellent performance. can bring.

In addition, in the above description, in order to simplify the explanation, the basic shape of the piezoelectric material 14 is assumed to be a rectangular hexahedral shape.
Of course, other shapes can also achieve the desired effects of the present invention. Furthermore, similar effects can be obtained by using lead titanate, barium titanate, or the like as the piezoelectric material.

[Effects of the Invention] Thus, according to the present invention, in addition to greatly improving detection sensitivity, it is possible to achieve sufficient miniaturization of the vibrating gyroscope and improve its productivity, and furthermore, it is possible to achieve stable quality. This can lead to improvements in accuracy and accuracy.

4

[Brief explanation of drawings]

1 to 3 are respectively perspective views illustrating a sliding oscillator according to the present invention. 4 to 7 and 9 and 10 are respectively perspective views illustrating a vibrating gyroscope according to the present invention. , a diagram illustrating a detection circuit; FIG. 11 is a perspective view illustrating another slip oscillator;
2 is a perspective view illustrating another detection circuit for Coriolis force, FIG. 13 is a perspective view illustrating still another slip oscillator, and FIGS. 14 and 15 respectively illustrate still other detection circuits. FIG. 16 is a perspective view showing an example of dividing the piezoelectric material, and FIG.
20 is a perspective view illustrating a vibrating gyroscope using a split type sliding oscillator, FIG. 21 is a perspective view illustrating a conventional technique, and FIG. 22 is a perspective view illustrating a conventional connecting member. 23 to 31 are diagrams for explaining the present invention in detail, respectively. 5 1... Slip vibrator, 2... Base, 3... Fixing means, 5... Vibrator, 14... Piezoelectric material, 15a-15
g, 16a-16g...electrodes, 17b-17d...
- Missing margin.

Claims (1)

[Claims] 1. One end of the vibrator is fixed to a surface perpendicular to the Y-axis of a fixing means in a three-dimensional coordinate system, and when the vibrator vibrates in the Y-axis direction. In the vibrating gyroscope that detects the Coriolis force generated in the X-axis direction by rotational movement of the fixing means around the Z-axis, the piezoelectric material is polarized in a direction perpendicular to the Y-axis, and
A shear vibrator formed by forming electrodes on each surface of the piezoelectric material perpendicular to the Y-axis is disposed as at least a part of the fixing means, and an electrode on at least one side of the shear vibrator is disposed on its surface. A vibrating gyro that is missing in some parts. 2. One end of the vibrator is fixed to a surface perpendicular to the Y-axis of a fixing means within a three-dimensional coordinate system, and the fixing means is fixed under vibration of the vibrator in the Y-axis direction. In a vibrating gyroscope that detects the Coriolis force generated in the X-axis direction by rotational movement around the Z-axis, the piezoelectric material is polarized in a direction perpendicular to the Y-axis, and
A shear vibrator formed by forming an electrode on each surface orthogonal to the Y-axis of the piezoelectric material is disposed as at least a part of the fixing means, and the electrode on at least one side of the shear vibrator is arranged in a plurality of A vibrating gyro made up of parts. 3. One end of the vibrator is fixed to a surface perpendicular to the Y-axis of a fixing means within a three-dimensional coordinate system, and the fixing means is fixed under vibration of the vibrator in the Y-axis direction. In a vibrating gyroscope that detects the Coriolis force generated in the X-axis direction by rotational movement around the Z-axis, the piezoelectric material is polarized in a direction perpendicular to the Y-axis, and
A shear vibrator formed by forming electrodes on each plane orthogonal to the Y-axis of the piezoelectric material is disposed as at least a part of the fixing means, and the shear vibrator is arranged in a plane orthogonal to the Y-axis. A vibrating gyro that is divided into multiple parts. 4. The vibrating gyroscope according to claim 1, wherein the two vibrators are attached to a fixing means in a tuning fork shape.