JPH0760093B2 - Vibrating gyro - Google Patents

Description

The present invention relates to a vibrating gyro that detects Coriolis force for the purpose of detecting angular velocity.

[Prior Art] As a conventional vibration gyro of this type, for example, there is a piezoelectric type as shown in FIG. 2, which is orthogonal to the Y axis of the fixing means 4 in a three-dimensional coordinate system. On each surface, two bimorph oscillators, unimorph oscillators and other driving means 5 made of a piezoelectric material are fixed in a tuning fork shape, and the free ends of these respective driving means 5 are also piezoelectric material. Each of the detection means 6 is formed by fixing each of the wide-width surfaces in a state in which the wide surface faces a direction orthogonal to that of the driving means 5 forming the pair of arm members.

When using such a vibration gyro, first,
An alternating voltage is applied to the driving means 5 to cause the driving means 5 to vibrate symmetrically in the direction of the solid arrow (Y-axis direction). As a method of producing such symmetrical vibration, in addition to a method of applying an AC voltage to both drive means 5, an AC voltage is applied to only one drive means 5 and the other drive means 5 is used as a vibration monitor. There is a method of controlling the vibration state and stabilizing the vibration by this. In any of these methods, the driving means 5 is vibrated in the resonance state to increase the vibration amplitude in order to strengthen the Coriolis force described later. I have decided.

Then, the vibrating gyro is moved to Z while the driving means 5 vibrates.
The Coriolis force Fc acting on the detection means 6 by rotating it about the axis at the angular velocity ω causes the detection means 6 to bend in the direction of the broken line arrow (X-axis direction) according to the magnitude of the angular velocity ω. Is generated, and as a result, a voltage is generated between the electrodes provided in the detection means 6.

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

Incidentally, in general, a device for increasing the operating efficiency in the resonance state by supporting the entire device as described above by the support member 7 is made.

[Problems to be Solved by the Invention]

However, in such a conventional technique, the driving means 5
Since the detection means 6 is connected to the tip of the
In addition to the increase in size of the device, there is a drawback that the wiring for supplying the AC voltage to the driving means 5, the wiring for taking out the signal voltage from the detection means 6, and the like become complicated.
For the wiring to, there was a great deal of difficulty in routing the wire. That is, the detection means 6 is always on the order of several μm.
It is placed under a vibration amplitude of about 100 μm, and the mass and elastic modulus of the wire rod for extracting the signal voltage, as well as the deformation state and the like, have a large effect mainly on the vibration of the driving means 5 to improve the detection sensitivity. Since it causes fluctuation, the wire is adhered to the side surface 5 ′ of the driving means 5 and extended to the vicinity of the fixing means 4 with small vibration, and pulled out from there to a predetermined connection terminal. Measures have been taken such as extending the terminal to a position near the detection means 6 and shortening the length of the wire to reduce the influence of the wire.

However, according to this, a significant reduction in the manufacturing work efficiency of the vibration gyro was inevitable.

On the other hand, when the wide surface of the driving unit 5 and the wide surface of the detecting unit 6 are not exactly orthogonal to each other, a vibration component in the Y-axis direction leaks into the detection signal of the detecting unit 6. At the same time, the detection accuracy itself decreases. By the way, as shown in the figure, under the structure in which the end surface of the driving means 5 and the end surface of the detection means 6 are directly connected, it is not possible to obtain a high connection accuracy simply by fixing them with an adhesive. .

Therefore, a method of connecting the driving means 5 and the detection means 6 via a connecting member 8 as shown in FIG. 3 has been proposed. According to the method of using the connecting member 8, the driving means 5 is connected.
The respective end portions of the detecting means 6 and the detecting means 6 are adhered to the respective surfaces formed in the connecting member 8 and oriented in directions orthogonal to each other through the electrodes provided on the surfaces, whereby the driving means 5 and the detecting means are connected. 6 and 6 can be connected relatively easily with a high squareness.

However, in this case, since the driving means adhering surface and the detecting means adhering surface of the connecting member 8 are oriented in directions orthogonal to each other, the adhering of the driving means 5 and the detecting means 6 to the connecting member 8 is performed. In order to do this at the same time, until the adhesive cures,
Each of the driving means 5 and the detection means 6 is connected to the connecting member 8
In addition, the structure of the jig required for accurate positioning and holding under a predetermined relative relationship becomes complicated, and the jig becomes large and the workability deteriorates. When the process is divided into steps, the number of work steps is significantly increased.

[Background technology]

Generally, when a force F as shown in FIG. 4 is applied to a piezoelectric bimorph element whose one end is fixed in a cantilevered manner to bend it, taking the series type bimorph 13 as an example, V = (3g ₃₁ · l · F) / (2t · w) g ₃₁ : Voltage output coefficient l: Length t: Thickness w: A voltage V represented by width is generated. On the other hand, as shown in FIG. 5, while polarizing in the direction indicated by the white arrow,
When the piezoelectric material 14 having upper and lower surfaces provided with electrodes (not shown) and acting as a slip oscillator is subjected to shear deformation by applying force F, similarly, V ′ = (t ′ · g ₁₅ · F) / ( l ′ · w ′) g ₁₅ : voltage output coefficient l ′: length t ′: thickness w ′: width to generate a voltage V ′ represented by:

Here, taking a piezoelectric ceramic material typified by lead zirconate titanate (PZT) and the like as an example, the voltage output coefficients g ₃₁ and g ₁₅ are about g ₁₅ / g ₃₁ 3 in terms of the ratio and are added. Although the slip oscillator is more advantageous in terms of voltage output coefficient than the force, the thickness t,
Considering t ', width w, w', and length l, l ', it is clear from the above two equations that the slip oscillator is not always advantageous as the output voltage.

Therefore, as shown in FIG. 6, the lower end portion of the driving means 5 is fixed to the fixing means 4, and an AC voltage is applied to the electrodes of the driving means 5 to vibrate in the Y-axis direction while the fixing means 4 is moved in the Z direction.
When rotated about 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 driving means 5,
In addition to the shear stress in the direction indicated by the broken line arrow, a torsion moment M indicated by the solid line arrow is applied to generate a force in the direction of twisting the fixing means 4. Therefore, this torsion moment M
By positively utilizing the Coriolis force Fc to measure, it is possible to improve the workability in manufacturing the vibrating gyro and also to reduce the size of the vibrating gyro.
Moreover, high measurement accuracy can be brought about.

The present invention was made with attention to such points,
The present invention provides a novel vibration gyro that has never existed before.

This will be described in more detail. As shown in FIG.
The arm 12 and the long side length a as shown in FIG.
When a force F in the X-axis direction is applied to the tip of the arm 12 when the intermediate member 11 having a rectangular contour with a short side length of b is connected, the shear stress τ = F / a is applied to the intermediate member 11.・ Along with b, the torsional moment about the Y axis is M = F ・
L'acts, and the torsional moment M causes a torsional shear stress τ'in the intermediate member 11 about the intersection O of the coordinate axes X, Y, Z. This torsional shear stress τ ′ is maximum at the midpoint A of the long side of the intermediate member 11 shown in FIG. 8, and its value is τ′max = F · L ′ / α · a · b ² α: long It is a constant determined by the ratio of the side length to the short side length, a / b.

Since τ′max has a relative relationship of τ′max / τ = L ′ / α · b with respect to τ, it is extremely effective to measure the torsional shear stress τ ′.

In addition, here, in order to facilitate the explanation, the intermediate member
Although 11 has a rectangular contour shape of a> b, if a <b in FIG. 8, the maximum torsional shear stress acts on the midpoint B, and if a = b, both midpoints are applied. The maximum torsional shear stress acts on A and B. By the way, the torsional shear stress τ ′ has a distribution in which it becomes zero at the center O and four corners of the intermediate member 11 and becomes high at the midpoint of the side.

As described above, the intermediate member 11 is subjected to not only the shear stress τ but also the torsional shear stress τ ′, so that
As shown in FIG. 9, 11 is the shear strain γ due to the shear stress τ.
And a shear strain γ ′ due to the torsional shear stress τ ′.

Here, regarding the relationship between the tensile and shear stresses and the electric displacement, when the electric displacement D generated when the stress T and the 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. In this case, the applied stresses T _{1 to} T ₆
Is acting in the direction shown in FIG. 10 and FIG. 11, and the piezoelectric material is assumed to be polarized in the direction of the third axis as indicated by the white arrow.

From the above, when the electrode is provided on the surface orthogonal to the first axis, the electric displacement D _{1 in} the first axis direction due to stress is D ₁ = d ₁₅ · T ₅ , which is It becomes a sliding oscillator that generates electrical displacement with respect to the surrounding shear stress T ₅ .

Next, as shown in FIG. 12, planes x ₁ and x ₂ orthogonal to the X-axis
And the planes y ₁ and y ₂ orthogonal to the Y axis and the plane z orthogonal to the Z axis.
It occurs when a torsional shearing stress τ'acts in the plane orthogonal to the Y-axis due to the torsional moment M about the Y-axis passing through the center of the rectangular parallelepiped piezoelectric material 14 formed by ₁ and z _2. Consider electrical displacement.

First, the piezoelectric material 14 is polarized in the X-axis direction, and the plane y ₁
When the direction of the torsional shear stress Tau'p ₁ acting on the point P ₁ of the above and an angle α with respect to the X axis, in the plane y _2, the point P ₂ against the point P _1, the point P torsional shear stress Tau'p ₁ acting on the ₁
If the size is equal direction shear stress Tau'p ₁ twist reverse acts, in the region connecting the two points P _1, P _2, electric displacement directed from the points P ₁ to point P ₂ is, Dp = d ₁₅ tau Since ′ p ₁ cosα, this electric displacement has different polarities in the range of −π / 2α <π / 2 and the range of π / 2α <3π / 2.

Therefore, in the present invention, the twisting moment M is obtained by appropriately combining the polarization direction of the piezoelectric material and the electrode arrangement.
Provided is a small-sized, high-precision vibration gyro with excellent productivity that can detect a high sensitivity.

[Means for Solving the Problems]

The vibrating gyroscope of the present invention uses two rectangular arm portions (adjacent surfaces are oriented in directions orthogonal to each other) and a base portion that interconnects these arm portions at their lower ends with a piezoelectric material. It is integrally molded into a tuning fork shape, both arms are oriented in the Z-axis direction of the three-dimensional coordinate system, and the base part is Y-shaped with the Y-axis direction spaced apart.
It is polarized in the axial direction, and is located on each surface of the base portion that is orthogonal to the X-axis in close proximity to the upper surface, the lower surface, or both sides of the upper surface and the lower surface of the base portion, and extends in the Y-axis direction. A detection electrode is provided.

[Work]

Here, while oscillating both arms symmetrically in the Y-axis direction and rotating them around the Z-axis to generate Coriolis force in each arm, as described above, In addition, the torsional moment due to the Coriolis force acts and the torsional shear stress due to the torsional moment is generated. Therefore, in the vibrating gyroscope according to the present invention, the torsion around the Z axis generated in the base portion by the both arm portions is By detecting the shear stress component, it is possible to detect the torsional moment, and thus the Coriolis force, with excellent sensitivity.

In addition, in this vibrating gyro, the fixed portion that is integrated with the arm portion functions as a slide oscillator, so that the detecting means 6 described in the prior art can be dispensed with, and the device can be sufficiently miniaturized. Can be arranged in the fixed part and the vicinity thereof, and the troubles associated with drawing the wire can be advantageously removed.

In addition, here, it is not necessary to connect the arm portion to the fixed portion, so that it is possible to manufacture a vibrating gyro with high dimensional accuracy and uniform performance.

〔Example〕

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

1 (a) to (c) are all perspective views showing an embodiment of the present invention.

In FIG. 1 (a), reference numeral 15 in the figure denotes a base portion, and 1
Reference numerals 6 and 17 denote first and second arm portions, respectively, and these arm portions 16 and 17 are integrally formed of a piezoelectric material together with a base portion 15 that interconnects their lower end portions.

And here, this molded body having an overall shape in the shape of a tuning fork with the adjacent surfaces directed in directions orthogonal to each other
The first arm portion 16 is indicated by an outline arrow in the figure under the condition that the postures of 6, 17 are oriented in the Z-axis direction of the three-dimensional coordinate system and spaced apart in the Y-axis direction. In the X-axis direction as described above, and on each of the first surface (front surface in the figure) x ₁ and the second surface x ₂ of the first arm portion 16 orthogonal to the X-axis, The first and second electrodes 18, 1 which are located apart from the second arm portion 17 and extend in the length direction of the arm portion 16.
Set 9.

Here, of these electrodes, when the first electrode 18 is grounded and a driving AC voltage is applied to the second electrode 19, the first arm portion 16 vibrates in the Y-axis direction. By the way, when the frequency of the applied AC voltage is the resonance frequency of the molded body,
The first arm portion 16 and the second arm portion 17 vibrate symmetrically in the Y-axis direction, and a large vibration amplitude is obtained.

Note that, here, when the second arm portion 17 is polarized in an appropriate direction and an electrode is also formed there, the second arm portion 17 serves as a vibration monitor for controlling the vibration state. Can be operated.

Further, in the base portion 15 of the molded body in the above-mentioned posture, it is polarized in the Y-axis direction, and
The electrodes 24 and 25 are provided so as to extend in the Y-axis direction at the positions of x ₁ and x ₂ close to the upper surface z ₁ of the base.

The one shown in FIG. 1 (b) is for both detection electrodes 24 ', 2
5 'shows an example in which in proximity to the bottom surface z ₂ of the base portion 15, and, the one shown in FIG. 1 (c), base portion
Each pair of detection electrodes 24, 24 on both sides of the upper surface z ₁ and the lower surface z ₂ of 15 ', 25, 25' shows an example in which a, which are also the embodiment (FIG. 1 a) It has the same action and effect as.

According to such a configuration, for example, the electrode 24 is grounded,
By connecting the electrode 25 to the detection circuit, the first arm portion 16 and the second arm portion 17 are caused to vibrate symmetrically in the Y-axis direction while being rotated around the Z-axis, whereby the respective arm portions are rotated. When a torsional moment based on the Coriolis force generated in 16, 17 acts on the base portion 15, a vibration gyro that senses a component of the torsional shear stress due to the torsional moment around the Z axis is provided.

The present invention has been described above based on the illustrated example.
14 includes lead zirconate titanate, lead titanate,
Of course, various materials such as barium titanate can be used.

〔The invention's effect〕

Thus, according to the present invention, the vibration gyro can be reduced in size and weight by detecting the Coriolis force at the base portion, and the electrodes can be concentrated on the base portion and its vicinity. Thus, it is possible to extremely easily wire the wire.

Moreover, by integrally molding the base part and the first and second arm parts with a piezoelectric material, the connecting work for them can be completely eliminated, and vibration with high dimensional accuracy and stable performance is achieved. Can bring a gyro.

In addition, since the electrode forming surface is limited to the two surfaces x ₁ and x ₂ which are orthogonal to the X axis, it is possible to reduce the number of electrode printing steps and reduce the production cost.

[Brief description of drawings]

1 (a) to 1 (c) are all perspective views showing an embodiment of the present invention, FIG. 2 is a perspective view showing a conventional example, and FIG. 3 is a perspective view illustrating a conventional connecting member. 4 to 12 are reference diagrams for explaining the present invention. 14 ... Piezoelectric material, 15 ... Base part, 16, 17 ... Arm part, 18, 19 ... Electrode, 20-27 ... Electrode.

Claims (1)

[Claims] 1. An overall shape of a tuning fork is formed by integrally molding two rectangular arm portions and a base portion interconnecting these arm portions at their lower end portions with a piezoelectric material to form a tuning fork. The part is oriented in the Z-axis direction of the three-dimensional coordinate system, and the base part is polarized in the Y-axis direction in a posture in which the parts are positioned at intervals in the Y-axis direction, and the X-axis of the base part is A vibrating gyroscope that has detection electrodes located on the upper surface and the lower surface of the base part, or on both sides of the upper surface and the lower surface, respectively, on each surface orthogonal to