JPH11325907A - Angular speed sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular speed sensor of excellent detection sensitivity wherein mass-production effect is expected with a simple configuration and dimension precision of a vibrator which affects intrinsic characteristics of an angular speed sensor is satisfied with relative ease. SOLUTION: An angular speed sensor 1 comprises, being a non-piezoelectric body, a prism-like non-piezoelectric ceramics vibrator 2, and a piezoelectric elements 3 which is, with a piezoelectric body 3a sandwiched between an inside electrode 3b and outside electrodes 3c and 3d, fitted to one side surface 2a of the non-piezoelectric ceramics vibrator 2. Here, the non-piezoelectric ceramics vibrator 2 is vibrated by the piezoelectric element 3 while the Coriolis force caused by the non-piezoelectric ceramics vibrator 2 is detected by the piezoelectric element 3 for detecting an angular speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor used for detecting a camera shake of a video camera, detecting an operation in a virtual reality device, detecting a direction in a car navigation system, and the like.

[0002]

2. Description of the Related Art At present, as a commercial angular velocity sensor, a rod-shaped vibrator is vibrated at a predetermined resonance frequency, and an angular velocity is detected by detecting a Coriolis force generated by the influence of the angular velocity with a piezoelectric element or the like. A so-called vibrating gyroscope-type angular velocity sensor is widely used.

In such an angular velocity sensor, as a method of driving the vibrator, there are a method using a separately-excited oscillation type driving circuit and a method using a self-excited oscillation type driving circuit. However, the method using the separately-excited oscillation type driving circuit has a problem that if the oscillation frequency and the resonance frequency of the vibrator deviate due to the temperature characteristics of the vibrator or the like, the detection sensitivity of the Coriolis force is suddenly reduced. Has not been reached.

Therefore, at present, as shown in FIG. 3 or 4, an angular velocity sensor using a self-excited oscillation type driving circuit in which a vibrator is incorporated in a loop of a phase shift oscillation circuit is generally used. In such an angular velocity sensor, self-sustained pulsation is performed at the resonance frequency of the vibrator, so that a change in sensitivity due to temperature characteristics is small and an angular velocity output with stable sensitivity can be obtained in a wide temperature range.

In the conventional angular velocity sensor shown in FIG. 3, a first piezoelectric element 101 comprising an electrode 101a and a piezoelectric body 101b and a first piezoelectric element 101 comprising an electrode 102a and a piezoelectric body 102b are provided on a side surface of a triangular prism-shaped constant elastic vibrator 100. 2 piezoelectric elements 1
02 and a third electrode 103a and a piezoelectric body 103b.
And a triangular prism-shaped vibrator 104 to which each of the piezoelectric elements 103 is attached. For example, the constant elastic vibrator 100 is a constant elastic metal vibrator.

Further, this conventional angular velocity sensor has a first
Amplifier 105 connected to the piezoelectric element 101, a phase shifter 106 connected to the amplifier 105, and the second piezoelectric element 1
02 and the third piezoelectric element 103, and the synchronous detector 1 connected to the differential amplifier 107.
08 and a low-pass filter 109 connected to the synchronous detector 108. In this conventional angular velocity sensor, the second piezoelectric element 102 and the third piezoelectric element 10
Reference numeral 3 detects the vibration of the vibrator 104 for self-excited oscillation and detects the Coriolis force generated in the vibrator 104.

The angular velocity sensor using such a triangular prism-shaped vibrator 104 has the highest sensitivity at present and is in use. However, such an angular velocity sensor has a problem that it is difficult to achieve a mass production effect in a manufacturing process due to its complicated structure. For example,
A step of bonding the piezoelectric element to each of the triangular shaped constant elastic vibrators is required, and there is a problem that a mass production effect cannot be obtained. In addition, with the miniaturization, the precision of the support mechanism and the bonding accuracy of the piezoelectric element to the constant elastic metal vibrator are required, and the influence of the bonding layer on the vibrator due to the bonding increases. However, there is a problem that the cost is remarkably increased.

The conventional angular velocity sensor shown in FIG. 4 has six electrodes 111, 112, 113, 114, 115, and 11 on the side surface of a cylindrical piezoelectric ceramic vibrator 110.
6 is provided with a vibrator 117 on which is printed. Here, the first to third electrodes 111, 112, and 113 are independent electrodes, and the fourth to fifth electrodes 114, 11
5, 116 are connected to a common ground potential. Also,
The angular velocity sensor includes an amplifier 118 connected to the first electrode 111 and a phase shifter 11 connected to the amplifier 118.
9, an adder 120 connected to the phase shifter 119, and a second
And the differential amplifier 121 connected to the third electrodes 112 and 113, and the synchronous detector 1 connected to the differential amplifier 121.
22 and a low-pass filter 123 connected to the synchronous detector 122. In this angular velocity sensor, by applying a voltage to the first electrode 111, the vibrator 1
17 and the second and third electrodes 11
2 and 113, the Coriolis force generated in the vibrator 117 is detected.

In this conventional angular velocity sensor, as described above, the electrodes 111, 112, 113, 114, 115,
Since 116 is printed on the vibrator 117, there is no need to bond a piezoelectric element to the vibrator 117, and the structure is relatively simple. However, this conventional angular velocity sensor has a problem that it is difficult to manufacture the piezoelectric ceramic vibrator 110 and print electrodes on the piezoelectric ceramic vibrator 110 with high accuracy, particularly when the size is reduced.

That is, in this conventional angular velocity sensor, the columnar piezoelectric ceramic vibrator 110 is used, but the cylindrical piezoelectric ceramic vibrator 110 is manufactured with higher precision than triangular or quadrangular prismatic vibrators. It is difficult. Moreover, with this angular velocity sensor, it is not easy to accurately print electrodes on a curved surface.

As described above, this angular velocity sensor is difficult to manufacture because the cylindrical piezoelectric ceramic vibrator 110 is used, and has a structure in which a mass production effect cannot be expected.
Even if mass-produced, it is difficult to reduce costs.

[0012]

As described above, in the method using the separately-excited oscillation type driving circuit, a change in sensitivity due to temperature characteristics becomes a problem. In order to solve this problem, angular velocity sensors employing a self-excited oscillation type driving circuit have been proposed. However, these conventional angular velocity sensors still have various problems as described above.

That is, in the conventional angular velocity sensor as shown in FIG. 3, the structure such as the bonding of the piezoelectric element to the constant elastic metal vibrator and the vibrator support mechanism becomes complicated. Further, in the conventional angular velocity sensor as shown in FIG. 4, since a cylindrical piezoelectric ceramic vibrator is used, it is difficult to manufacture the vibrator 110 with high accuracy, and it is not possible to print electrodes with high accuracy on a curved surface. It's not easy.

The present invention has been proposed in view of the above-described conventional circumstances, and a mass production effect can be expected with a simpler configuration, and the dimensional accuracy of a vibrator which has an essential characteristic as an angular velocity sensor is determined. It is another object of the present invention to provide an angular velocity sensor excellent in detection sensitivity that can be satisfied relatively easily.

[0015]

In order to solve the above-mentioned problems, an angular velocity sensor according to the present invention is made of a non-piezoelectric body, in which a quadrangular prism-shaped vibrator and a piezoelectric body are sandwiched between electrodes. A piezoelectric element attached to one side surface of the vibrator. The angular velocity sensor detects the angular velocity by vibrating the vibrator by the piezoelectric element and detecting the Coriolis force generated in the vibrator by the piezoelectric element.

The angular velocity sensor having such a configuration causes the vibrator to vibrate by the piezoelectric element and detects the Coriolis force generated thereby.

The angular velocity sensor according to the present invention has a structure in which a piezoelectric element having a piezoelectric body sandwiched between electrodes is attached to one side of a vibrator made of a non-piezoelectric body in the form of a quadrangular prism. It is manufactured without the need for a step of printing electrodes in advance on the side surfaces of the device. Furthermore, after bonding the piezoelectric element to the non-piezoelectric block that constitutes the vibrator, simply cut out the individual vibrator,
The piezoelectric element can be accurately attached to the vibrator made of a non-piezoelectric body formed in a quadrangular prism shape.
And this makes it possible to miniaturize the vibrator,
Further, a mass production effect can be obtained. In addition, by setting the piezoelectric element to be accurately attached to the vibrator,
Unbalance of the vibrator due to displacement of the bonding position of the piezoelectric element does not occur.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the following examples, and it goes without saying that the present invention can be arbitrarily changed without departing from the gist of the present invention.

FIG. 1 shows a basic configuration of an example of an angular velocity sensor to which the present invention is applied. As shown in FIGS. 1 and 2, the angular velocity sensor 1 includes a non-piezoelectric ceramic vibrator 2 which operates as a vibrating gyroscope.

This angular velocity sensor 1 is a non-piezoelectric body, and has a configuration in which the non-piezoelectric ceramic vibrator 2 in the form of a quadrangular prism and a piezoelectric body 3a are sandwiched between an inner electrode 3b and outer electrodes 3c and 3d. One side 2a of the piezoelectric ceramic vibrator 2
A piezoelectric element 3 attached to the
The non-piezoelectric ceramic vibrator 2 is caused to vibrate, and the Coriolis force generated in the non-piezoelectric ceramic vibrator 2 is detected by the piezoelectric element 3 to detect the angular velocity.

Here, the non-piezoelectric ceramic vibrator 2 is formed such that the cross-sectional shape (hereinafter, simply referred to as a cross-sectional shape) when cut along a plane perpendicular to the longitudinal direction is a rectangle. . This non-piezoelectric ceramic vibrator 2
It is made of a non-piezoelectric ceramic body having constant elasticity, and is formed in a quadrangular prism shape. A rectangular piezoelectric element 3 is bonded to one side surface 2a of such a non-piezoelectric ceramic vibrator 2.

The piezoelectric element 3 constitutes first and second electrode portions in which the outer electrodes 3c and 3d are equally divided in parallel with the longitudinal direction of the non-piezoelectric ceramic vibrator 2. The piezoelectric element 3 is attached to the non-piezoelectric ceramic vibrator 2 by attaching the inner electrode 3 to the side surface 2 a of the non-piezoelectric ceramic vibrator 2.
This is performed by bonding b. The piezoelectric element 3 mounted in such a state is configured such that outer electrodes 3c and 3d opposed to the inner electrode 3b with the piezoelectric body 3a interposed therebetween are outwardly desired. Then, in the piezoelectric element 3, terminals A and B are led out from the outer electrodes 3c and 3d,
A terminal C extends from the inner electrode 3b.

The angular velocity sensor 1 includes an adder 10
, An amplifier 11, and a phase shifter 12, and the electrodes 3 c and 3 d of the piezoelectric element 4 function as a vibration driving unit that vibrates the non-piezoelectric ceramic vibrator 2. The angular velocity sensor 1 includes a differential amplifier 13, a synchronous detector 14 connected to the output of the adder 10,
A low-pass filter 15 is provided, and these and the outer electrodes 3c and 3d of the piezoelectric element 4 function as a detection unit that detects the vibration of the non-piezoelectric ceramic vibrator 2. That is, the piezoelectric element 3 of the angular velocity sensor 1 has both a vibration driving function and a function of detecting the vibration. Thereby, the angular velocity sensor 1 detects the Coriolis force generated by the rotation of the non-piezoelectric ceramic vibrator 2 by the detection function while vibrating by the vibration driving function.

More specifically, in the vibration driving section, terminals A and B from the outer electrodes 3c and 3d of the piezoelectric element 3 are connected to the adder 1
Connected to 0. That is, the electrode 3 of the piezoelectric element 3
The outputs from c and 3d are input to the adder 10, and the added value is taken by the adder 10. Then, the output from the adder 10 is input to the amplifier 11, and the input signal is amplified. Then, the phase of the output from the amplifier 11 is shifted by the phase shifter 12, and the outer electrodes 3c,
Output to 3d. This constitutes a so-called phase shift oscillation circuit, and the angular velocity sensor 1 causes the non-piezoelectric ceramic vibrator 2 to self-excitedly vibrate. The vibration direction of the non-piezoelectric ceramic vibrator 2 by this vibration drive unit is
This is a direction perpendicular to the side surface 2a to which the piezoelectric element 3 is bonded, and is hereinafter referred to as a vibration direction.

In the detecting section, the terminal A from the outer electrode 3c of the piezoelectric element 3 is connected to the positive input terminal of the differential amplifier 13, and the terminal B from the outer electrode 3d of the piezoelectric element 3 is It is connected to the negative input terminal of the differential amplifier 13. Note that a terminal C from the inner electrode 3b of the piezoelectric element 3 is connected to a reference voltage terminal of a circuit which is an output voltage at rest. That is, the electrodes 3c of the piezoelectric element 3,
The outputs from 3d are input to the differential amplifier 13, respectively.
Their difference is taken by the differential amplifier 13. In other words, the angular velocity sensor 1 generates the Coriolis force generated in the non-piezoelectric ceramic vibrator 2 by rotating the non-piezoelectric ceramic vibrator 2 while the non-piezoelectric ceramic vibrator 2 is vibrating in the vibration direction. , Detected by the piezoelectric element 3, and their differential is taken by the differential amplifier 13.

The output from the differential amplifier 13 is input to a synchronous detector 14, where synchronous detection is performed. At this time, the output from the adder 10 is supplied to the synchronous detector 14 as a synchronous signal in order to perform synchronous detection. The output from the synchronous detector 14 is the low-pass filter 1
5, is output as an angular velocity signal obtained by detecting the Coriolis force generated in the non-piezoelectric ceramic vibrator 2. In the angular velocity sensor 1 configured as described above, the Coriolis force detected by the piezoelectric element 3 is a force acting in a direction perpendicular to the side surface 2a to which the piezoelectric element 3 is bonded.

As described above, in the angular velocity sensor 1, the non-piezoelectric ceramic vibrator 2 is vibrated by using the piezoelectric element 3, and the Coriolis force generated in the non-piezoelectric ceramic vibrator 2 at that time is applied by the piezoelectric element 3. The angular velocity can be detected based on the Coriolis force detected by the piezoelectric element 3.

In the angular velocity sensor 1, a piezoelectric element 3 having a piezoelectric body sandwiched between electrodes is attached to the non-piezoelectric ceramic vibrator 2 on the opposite side surface of the non-piezoelectric ceramic vibrator 2. Thereby, for example, this angular velocity sensor 1
Before the piezoelectric element 3 is attached to the non-piezoelectric ceramic vibrator 2 in the manufacturing process of
A piezoelectric element having a structure sandwiched between the inner electrode 3b and the outer electrodes 3c and 3d is bonded to a non-piezoelectric ceramic wafer which is a block constituting the non-piezoelectric ceramic vibrator 2, and the individual non-piezoelectric ceramic vibrators It becomes possible by cutting out as 2.

Therefore, the angular velocity sensor 1 having such a structure does not require a step of printing an electrode on a side surface in advance, and does not require a difficult step of printing an electrode on a curved surface, for example. Further, as described above, since the piezoelectric element 3 is attached to the non-piezoelectric ceramic vibrator 2 only by cutting out, a vibrator with extremely high precision is formed, and ultra-miniaturization becomes possible. Further, a mass production effect can be obtained. In addition, a structure in which imbalance of the vibrator due to displacement of the bonding position of the piezoelectric element hardly occurs is obtained.

More specifically, since the angular velocity sensor 1 has a very simple structure in which a piezoelectric element is bonded to an opposing surface of a non-piezoelectric ceramic vibrator having a quadrangular prism, the angular velocity sensor 1 is manufactured in a manufacturing process. As described above, it is not necessary to provide a difficult process such as bonding a piezoelectric element to a constant elastic metal vibrator or printing an electrode on a curved surface.

Then, after bonding the piezoelectric elements on both sides of the non-piezoelectric ceramic wafer to which the double-sided electrode plating or the like has been applied, the individual elements are cut out as individual quadrangular prism vibrators, and are adhered to the non-piezoelectric ceramic vibrator 2 with high precision. The formed piezoelectric element is formed. Then, by this, the non-piezoelectric ceramic vibrator 2
Can be miniaturized, and a mass production effect can be obtained. In addition, since the piezoelectric element is accurately attached to the non-piezoelectric ceramic vibrator, the vibrator is not unbalanced due to the displacement of the bonding position of the piezoelectric element.

In addition, naturally, it is considered that the technical difficulty increases with miniaturization, and it becomes difficult to secure the accuracy. However, the fine processing technology already established in LSI and head processing is applied. By doing so, such a problem can be solved. Therefore, since high-precision dimensional accuracy can be obtained, frequency adjustment of the non-piezoelectric ceramic vibrator can be simplified. Note that, for example, a step of cutting out a quadrangular prism-shaped vibrator after previously bonding the piezoelectric element to the block made of the vibrator material described in the embodiment of the present invention,
When applied to a conventional constant elastic oscillator, a piezoelectric element is preliminarily bonded to a constant elastic oscillator material and cut out. However, here, since the piezoelectric body constituting the piezoelectric element is made of ceramic as described above, that is, a material different from the vibrator is used, it becomes difficult to cut out the piezoelectric element. That is, by using the same material for the piezoelectric body and the vibrator constituting the piezoelectric element as in the embodiment of the present invention, the processing is facilitated and a mass production effect can be obtained.

Further, by applying a self-excited oscillation type driving circuit to this angular velocity sensor 1, a highly accurate angular velocity sensor can be constituted by a very simple circuit.

Further, since the angular velocity sensor 1 is a self-excited oscillation type, the sensitivity does not decrease due to the influence of the temperature characteristic as in the separately excited oscillation type angular velocity sensor.

[0035]

The angular velocity sensor according to the present invention is a non-piezoelectric body, and has a structure in which a quadrangular prism-shaped vibrator and a piezoelectric body are sandwiched between electrodes, and is attached to one side surface of the vibrator. A piezoelectric element. This angular velocity sensor vibrates the vibrator by the piezoelectric element and detects the Coriolis force generated in the vibrator by the piezoelectric element.
Detect angular velocity.

The angular velocity sensor having such a configuration can vibrate the vibrator by the piezoelectric element and detect the Coriolis force generated thereby.

Thus, the angular velocity sensor has a structure in which the piezoelectric element formed by sandwiching the piezoelectric body between the electrodes is attached to one side surface of the vibrator made of a non-piezoelectric body in the form of a quadrangular prism. It is manufactured without a step of printing electrodes in advance on the side surfaces. Furthermore, after bonding the piezoelectric element to the non-piezoelectric block that constitutes the vibrator, simply cutting out the individual vibrator, the piezoelectric element can be accurately formed into a vibrator made of a non-piezoelectric body formed in a square pillar shape. Can be attached. Thus, the vibrator can be miniaturized, and a mass production effect can be obtained. In addition, since the piezoelectric element is accurately attached to the vibrator, the vibrator is not unbalanced due to the displacement of the bonding position of the piezoelectric element.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an angular velocity sensor to which the present invention is applied.

FIG. 2 is a perspective view showing a part of a non-piezoelectric ceramic vibrator of the angular velocity sensor.

FIG. 3 is a diagram showing an example of a conventional angular velocity sensor;
(A) is a figure which shows the whole structure of the said angular velocity sensor, (b) is a perspective view which shows the part of a vibrator, (c)
FIG. 4 is a cross-sectional view showing a cross section at a central portion of the vibrator.

4A and 4B are diagrams illustrating another example of a conventional angular velocity sensor, in which FIG. 4A is a diagram illustrating an entire configuration of the angular velocity sensor, and FIG. 4B is a perspective view illustrating a portion of a vibrator;
(C) is a cross-sectional view showing a cross section at the center of the vibrator.

[Explanation of symbols]

1 angular velocity sensor, 2 non-piezoelectric ceramic vibrator, 3
Piezoelectric element, 3a piezoelectric body, 3b inner electrode, 3c, 3
d outer electrode

Claims (4)

[Claims] 1. A non-piezoelectric body, comprising: a quadrangular prism-shaped vibrator and a piezoelectric body sandwiched between electrodes; and a piezoelectric element attached to one side surface of the vibrator. An angular velocity sensor characterized in that the vibrator is vibrated by an element and an angular velocity is detected by detecting a Coriolis force generated in the vibrator by the piezoelectric element. 2. The piezoelectric element includes first and second electrode portions in which the electrode is bisected in parallel with the longitudinal direction of the vibrator, and the detection of the angular velocity includes the first and second electrode portions. The angular velocity sensor according to claim 1, wherein the detection is performed based on a detection result of the electrode unit. 3. The angular velocity sensor according to claim 1, wherein the vibrator is made of non-piezoelectric ceramic, and the piezoelectric body is made of piezoelectric ceramic. 4. The angular velocity sensor according to claim 2, further comprising a self-excited oscillation type driving circuit including a phase shift oscillation circuit that causes the piezoelectric element to function as a vibration driving element.