JPH0382911A - 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 of the axis Y and electrodes are formed on two facing surfaces which are in parallel with the axis Y as a part of a fixing means, and omitting a part of one electrode of the facing electrodes of said vibrator. CONSTITUTION:In a sliding vibrator 1, a piezoelectric material 14 having the shape of rectangular parallelopiped is polarized in the direction in parallel with the axis Y, and electrodes 15a and 16a are formed on planes x1 and x2, respectively. An arbitray point on the plane x1 is made to be Q1, and a point facing Q1 is made to be Q2. Then, a part of at least one electrode, e.g. the part of the point Q2 of the electrode 16a, is locally 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 linkage of a vibrator 5 to the fixing means 3 is performed by fixing one end part of one sheet of the vibrator 5 to the sliding vibrator 1 with a bonding agent and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a vibrating gyro for sensing Coriolis force for the purpose of sensing angular velocity.

[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 gyroscope, first,
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 between the electrodes provided in the detection means 6.

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

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 approximately several micrometers to 100 micrometers.
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]

- If 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 bend, then, taking the series bimorph 13 as an example,
Approximately, V= (3g3+・1−F)/(2t−w)g3I:
Voltage output coefficient I! : Length t : Thickness W : Generates a voltage V expressed as width. On the other hand, as shown in FIG. 24, a force F is applied to a piezoelectric material 14 acting as a sliding oscillator, which is polarized in the direction shown by the white arrow and has electrodes (not shown) on the upper and lower surfaces. Similarly, when deformed, v' = (t,' ・g+s・F
)/(j2'.w/)g15: Voltage output coefficient l': Generates voltage V' expressed by length tL and thickness W'.

Taking piezoelectric ceramic materials such as lead zirconate titanate (PZT) as an example, the voltage output coefficient g 31+ g +s is the ratio g +s/
g sl” 3, and the sliding vibrator is more advantageous in terms of voltage output coefficient with respect to the applied force, but the thickness t, t' width w, w', and length l of each piezoelectric material , 1', 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 is applied to the connecting portion 9 of the fixing means 4 with the vibrator 5, in addition to the shear stress shown by the broken line arrow, as shown by the solid line arrow. A bending moment M is applied to generate a force in a direction to twist 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
As a result, a torsional shear stress τ′ centered on the intersection point ○ of the coordinate axes x, y, and z is generated in the intermediate member 11. This torsional shear stress τ' is maximum at the midpoint A of the long side of the intermediate member 11 shown in FIG. 27, and its value is τ'max=F-L'/lx・a-b"α: It is a constant determined by the ratio a/b of the length of the long side and the short side.

0 This r'max is r'max /τ-L for τ
It is extremely effective to measure the torsional shear stress τ' because of the relative relationship of '/a·b.

Here, in order to simplify the explanation, the intermediate member II has a rectangular contour shape with a>b, but if a<b in FIG. 27, the maximum torsional shear stress acts on the midpoint B. Therefore, if a=b, the maximum shear stress will act on both midpoints A and B. by the way,
The torsional shear stress τ' exhibits a distribution in which it becomes zero at the center ○ 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 11 undergoes a shear strain T due to the shear stress τ, as shown in FIG. 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 1, and titanium acid as a piezoelectric material Taking lead zirconate as an example, it is expressed by the electrical change when only stress T is applied.

Note that here, the applied stresses T1 to T6 are 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 the electrode is provided on a plane perpendicular to the first axis, the electrical displacement in the first axis direction due to stress is D+ = d+s・T5, which is equal to the electric displacement around the second axis. It becomes a sliding oscillator that generates electrical displacement in response to shear stress T5.

Next, as shown in FIG. 31, a plane XI perpendicular to the X-axis
, X2, a plane 3'++yz perpendicular to the Y-axis, and a plane Zl+ZZ perpendicular to the Z-axis. Consider the electrical displacement caused by the action of torsional shear stress τ′ in a plane perpendicular to the axis.

When a torsional shear stress τ' is generated in a plane orthogonal to the Y axis due to the torsional moment M, an orthogonal shear stress of equal magnitude and opposite moment coexists on a plane orthogonal to this torsional shear stress. Become.

That is, the plane y2 of the piezoelectric material 14 polarized in the Y-axis direction
If the direction of the torsional shear stress τ/p2 acting on point P2 above, indicated by the dashed arrow in the figure, forms an angle of β with respect to the At the point P, a torsional shear stress of equal magnitude and opposite direction to the torsional shear stress τ'pz acts, and in the region connecting the points P, , P, it is perpendicular to the torsional shear stress τ/p2. In other words, the orthogonal shear stress τ as shown by the solid arrow in the figure is applied to the plane that includes the Y axis and forms an angle of (β+π/2) with the X axis.
'Pz will come into play.

Therefore, the electrical displacement in the areas PI and P2 in the direction perpendicular to the Y-axis and forming an angle α with the X-axis is Dp-d +sT'p
z cos (α−β). In addition, at point P2', which is axially symmetrical to point P2 with respect to the Y axis, point P
A torsional shear stress that is equal in magnitude and opposite in direction to the torsional shear stress acting on P2', and P1' that opposes P2'.
Since a torsional shear stress that is equal in magnitude and opposite in direction to the shear stress acting on point P2' acts on the area, a similar orthogonal shear stress τ is also applied to the region connecting points P1' and P2'. /p2 acts, and the area P z' + P
The electrical displacement of 4 in the direction perpendicular to the Y axis and making an angle α with the X axis at 2' is: 1) p' = d + 5τ' pz cos (α - β - π) -
d15τ'pz cos (α−β).

In this way, the regions P I, P z and the regions P 1',
Since an electric displacement of equal magnitude and different polarity occurs at p2/, for example, even if the angle α is zero, that is, electrodes are provided on the entire surfaces of planes X1 and x2, the generated charges will not mutually interact. By canceling out each other, no voltage is generated between the electrodes due to the action of the torsional moment M, and even if the intermediate member 1 shown in FIG.
Even if such a structure is used as a slip oscillator, the torsional shear stress τ' is not detected and only the simple shear stress τ is detected as a voltage, so the detected stress is small and high detection sensitivity cannot be obtained.

Therefore, the present invention makes it possible to detect the torsion moment M with high sensitivity by preferentially extracting a specific electrical displacement, and also enables high-precision vibration that is compact and highly productive. 5 Serve the gyro.

[Means to solve the problem]

In particular, the vibrating gyroscope of the present invention polarizes a piezoelectric material in the Y-axis direction of a three-dimensional coordinate system, and forms electrodes on at least two opposing surfaces of the piezoelectric material that are parallel to the Y-axis. A shear vibrator made of This is what was left out.

Here, instead of missing a part of at least one electrode, at least one of the opposing electrodes may be divided into a plurality of electrodes, or the shear oscillator itself may be
It is also possible to divide into a plurality of parts within a plane orthogonal to the Y-axis.

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 shear stress of the sliding oscillator based on the torsional moment generated by the Coriolis force. , the detection sensitivity can be greatly improved compared to the case where the deflection force of the detection means 6 is detected as in the prior art. The same applies to cases where at least one of the opposing electrodes or the shear vibrator 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.

7 Moreover, here, when assembling the vibrating gyroscope, one end of the driving vibrator can be surface-bonded to the fixing means, making it extremely easy to position both of them and maintain accuracy, and therefore improving performance. It becomes possible to supply vibration gyroscopes with small variations 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+X2+yl and y2+zl+Zz in a direction parallel to the Y axis, and forms electrodes 15a and 16a on each of planes xI+x2 as indicated by diagonal lines in the figure. Let Ql be an arbitrary point on the plane X, and Q2 be the opposing point on the plane Figure 1 shows the sliding oscillator 8 with a missing part.

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 vibrator 5 can be connected to the fixing means 3 by fixing one end of the second vibrator 5 (the lower end in the figure) 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 the fixing means 3 is rotated around the Z-axis at an angular velocity ω to generate a Coriolis force Fc, Due to the torsional moment M, the piezoelectric material 14 has Y
Torsional shear stress in a plane perpendicular to the axis and orthogonal shear stress of a magnitude corresponding to this torsional shear stress act, and the electrode 15
Between a and 16d, an electrical displacement occurs that is not canceled by the electrical displacement that occurs between points Q and Q2,
This is detected as a voltage between both electrodes.

In such an electrode configuration, a highly practical configuration with high detection sensitivity to the torsional moment M is the plane XI+
The electrodes on at least one surface of X2 are formed only on half of those surfaces, and the missing edge of the half electrode is parallel to the Y axis, or
The electrodes on at least one surface of the plane ZI+z2 are formed only on half of those surfaces, and the missing edge of the half electrode is parallel to the Y axis, as shown in FIGS. FIG. 3 shows an example of its configuration.

In the configuration shown in FIG. 2, the electrode 16h on the plane X2 has an area half that of the plane X2, and the missing edge 17b of the electrode 16b is parallel to the Y axis.
The configuration shown in the figure includes each electrode 15c on the inner planes XI and X2.
16c are made to oppose each other with an area half of those planes xl and x2, and the respective missing edges 17c and 17d are made parallel to the Y axis.

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 the Veri vibrators 1 to the two surfaces of the base 2 perpendicular to the Y-axis, and the fixing means 3 is constructed by attaching the two vibrators 5 at their lower ends. In the example shown in FIG. 6, the fixing means 3 is constructed by sandwiching the - number of sliding vibrators 1 between the bases, and each base 2 The lower ends of two vibrators 5 are fixed in the shape of a tuning fork to each plane perpendicular to the Y-axis. The example shown in Figure 7 is
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. This makes it possible to improve the S/N ratio with respect to external vibration noise, and to double the detection sensitivity of the Coriolis force Fc.

Furthermore, as shown in FIG. 9, when the entire unit 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 achieved. Can be guaranteed.

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 that is not sandwiched between the spacers 1 and 2 can be formed of another spacing member 18, and the spacer 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.
In order to effectively utilize the electrical displacement that occurs in the part where c is not formed, the polarization direction is set to the Y-axis direction, and the plane
, the upper electrodes and the electrodes on the plane X2 are each divided by punching patterns 19a and 19b parallel to the Y axis to form electrodes 15d and 16d and electrode 15e.
and 16e are opposed to each other, and in the same way, the electrode on the plane X1 is divided into electrodes i5f and 15g by the punching pattern 19c, and the electrode on the plane X2 is divided into electrodes 16f and 16g by the punching pattern 19d. 1
6f and electrodes 15e and 16e are opposed to each other.

Note that at each corner 20, 21, 22, 23 of the piezoelectric material 14, adjacent electrodes are insulated from each other.

In this shear oscillator 1, when a torsion moment (M) acts on it, between the opposing electrodes, the electrodes 15e,
Since the electrical displacements toward 15f, 16d, and 16g have the same polarity, for example, by configuring a detection circuit as shown in FIG. 12, the amount of charge generated by the torsion moment M can be increased, and the vibration The S/N ratio against noise 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 positions and numbers of the punching patterns are merely an example of good detection efficiency, and therefore are not limited to the illustrated example, and can of course be changed in various ways.

Further, it is also possible to leave the electrodes on either plane x1 or plane x2, and/or plane z1 or plane z2 without dividing them.

FIG. 13 is a perspective view illustrating still another slip oscillator, in which the polarization direction is the Y-axis direction, and the two pieces are divided into two by a plane perpendicular to the Z-axis at the coordinate origin position. Electrodes 15h are provided on each plane X and plane X2 of the piezoelectric material 14.
, 15i and 16h, 16i were formed.

This sliding oscillator 1 increases the amount of charge generated by the shear remomen M by effectively extracting electrical displacement of opposite polarity under the circuit configuration shown in FIGS. 14 and 15, for example. , it is possible to improve the S/N ratio against vibration noise.

Incidentally, the position and angle of division of the sliding vibrator 1 can be changed as appropriate. Note that the division is carried out by dividing Y with a plane that crosses both planes yI and y2.
It is necessary to perform this in a plane perpendicular to the axis.

FIG. 16 is a diagram showing an example thereof, in which the piezoelectric material 14 polarized in the Y-axis direction is +π including the Y-axis and relative to the X-axis.
/4 and -π/4, respectively, so that it is divided into four parts in a plane perpendicular to the Y axis.

17 to 20 are diagrams each showing an example of application of the above-mentioned split sliding oscillator, here the oscillator shown in FIG. 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, the desired effects of the present invention can be achieved even with other shapes. Furthermore, similar effects can be obtained by using lead titanate, barium titanate, or the like as the piezoelectric material.

〔Effect of the invention〕

Thus, according to the present invention, in addition to greatly improving detection sensitivity, it is also possible to achieve sufficient miniaturization of the vibrating gyroscope and improve its productivity, and furthermore, it is possible to stabilize quality and improve accuracy. and can bring about.

5

[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. 6 ■... Slip vibrator, 2... Base, 3... Fixing means, 5... Vibrator, 14... Piezoelectric material, 15a-15
i, 16a-16i... electrode, 17b-17d...
Missing edge, 193-19d... cutout pattern.

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 the Y-axis direction, and the Y-axis of the piezoelectric material is A shear vibrator having electrodes formed on at least two opposing surfaces parallel to the axis is disposed as at least a part of the fixing means, and at least one of the opposing electrodes of the shear vibrator is provided. A vibrating gyro that is partially missing. 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 the Y-axis direction, and the piezoelectric material is parallel to the Y-axis. A shear vibrator having electrodes formed on at least two opposing surfaces is disposed as at least a part of the fixing means, and at least one of the opposing electrodes of the shear vibrator is divided into a plurality of electrodes. A vibrating gyro. 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 the Y-axis direction, and the piezoelectric material is parallel to the Y-axis. A shear vibrator having electrodes formed on at least two opposing surfaces is disposed as at least a part of the fixing means, and the shear vibrator is divided into a plurality of pieces in a plane perpendicular to the Y-axis. vibrating gyro. A vibration gyro that is missing. 4. The vibrating gyroscope according to claim 1, wherein the two vibrators are attached to a fixing means in a tuning fork shape.