JPH0972744A - Angular speed sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an angular speed sensor having characteristics for detecting an angular speed signal accurately. SOLUTION: The angular speed sensor has a fork arm structure where first and second U-shaped piezoelectrics 4, 5 laminated through a detection electrode 6 are polarized in the laminating direction of at least one fork arm 4a, 5a thereof and drive signals are fed, with reverse phases, between drive electrodes 7, 12 and 8, 11 disposed on the diagonal of fork arm. Since the drive signals are canceled in the vicinity of detection electrodes, the signal detected by the detection electrode 6 is never mixed with drive signal and the angular speed signal detection power is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration-type angular velocity sensor that can be used for attitude control and navigation of moving bodies such as aircraft, automobiles, robots, ships, and vehicles, or for preventing camera shake of still cameras and video cameras. The present invention relates to an angular velocity sensor used as a remote controller for remote operation.

[0002]

2. Description of the Related Art In this type of angular velocity sensor, a piezoelectric body is attached to a U-shaped vibrating member to form a drive section and a detection section, and a single drive is applied to an electrode of a piezoelectric element of the vibrating section. The tuning fork arm of the piezoelectric body is driven by the signal supplied from the power source, and the Coriolis force generated in the detection unit by this drive is extracted from the piezoelectric body of the detection unit as an angular velocity signal.

[0003]

In the above structure, since the signal extracted from the detection electrode contains the component induced by the drive signal in addition to the angular velocity signal,
A circuit for separating the mixed signal is required. In this case, the signals other than the angular velocity signal cannot be completely separated, and by any means,
There is a problem that it is difficult to improve the detection characteristics because a part thereof remains and becomes a noise component.

Therefore, it is an object of the present invention to eliminate the influence of the noise component due to the drive signal and enhance the detection characteristic of the angular velocity signal.

[0005]

In the angular velocity sensor of the present invention, the U-shaped first and second piezoelectric bodies that are superposed via the detection electrodes, and at least one tuning fork of the first piezoelectric body are provided. In the tuning fork arm of the second piezoelectric body facing the tuning fork arm provided with the first and second driving electrodes and the first and second driving electrodes provided on the surface of the arm opposite to the detection electrode. The third and fourth drive electrodes provided on the surface opposite to the detection electrode are provided, and among the first to fourth drive electrodes, the first and third drive electrodes that are diagonally across the detection electrode are provided. A first drive power supply is connected to the drive electrodes, and similarly, a signal having a phase opposite to that of the first drive power supply is supplied to the second and fourth drive electrodes on the diagonal line via the detection electrodes. So that the second drive power source is connected, and at least one of the U-shaped first and second piezoelectric bodies has a tuning fork position. Beam is characterized in first, it was polarized tuning fork arm structure of the second piezoelectric in the thickness direction in the same direction which is allowed to polymerize.

[0006]

With the above arrangement, the drive signal is supplied from the first drive power source to the first and third drive electrodes on the diagonal line of the tuning fork arm, and the second and fourth drive electrodes are supplied to the second and fourth drive electrodes. Is the second
A drive signal having a phase opposite to that of the first drive power source is supplied from the drive power source of, and the signal for driving the tuning fork arm is driven through the detection electrode, so that the drive signals are mutually canceled on the detection electrode, It is not mixed in the detection signal,
As a result, the detection capability of the angular velocity signal extraction can be improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The angular velocity sensor of the present invention will be described below. 1, 2 and 3 show an embodiment of the angular velocity sensor of the present invention. In FIG. 1, reference numeral 1 denotes an iron cap having an open lower surface, and nickel plating is provided on the front and back surfaces thereof. A disc-shaped base 2 is fitted into the opening on the lower surface of the cap 1 so that the inside of the cap 1 becomes a closed space.

The detection element 3 is arranged in the closed space in a non-contact state with the inner surface of the cap 1.
Are vertically fixed on the base 2 with an adhesive. As shown in FIGS. 1 and 2, the detection element 3 is formed by superimposing U-shaped first and second piezoelectric bodies 4 and 5 via a U-shaped Ag-Pg-based detection electrode 6. It is formed by integrally firing. Further, the tuning fork arms 4a, 4b, 5a, 5b of the first and second piezoelectric bodies 4, 5 respectively.
On the surface opposite to the detection electrode 6, that is, on the surface exposed to the outside, the vertically elongated Ag-Pg-based electrodes 7, 8, 9, 10,
11, 12, 13, and 14 are printed and provided by printing. Of these electrodes, 7, 8, 11, and 12 are drive electrodes, and 9, 10, 13, and 14 are monitor electrodes. That is, as shown in FIG. 2, in the polymer of the tuning fork arms 4a and 5a, the first drive power source 15 is connected to the drive electrodes 7 and 12 on the diagonal line via the detection electrode 6 and crosses the drive electrodes. The second drive power source 16 is connected to the drive electrodes 8 and 11 on the diagonal line. The first of these,
The second drive power sources 15 and 16 are drive electrodes 7 and 12, respectively.
An AC signal (tuning fork resonance frequency) for causing tuning fork resonance is supplied to 8 and 11, and the signals supplied from the first and second driving power supplies 15 and 16 are in a reverse phase state. There is.

The tuning fork arms 4b and 5 on the monitor side are also provided.
In b, the diagonal monitor electrodes 9 and 14 are both connected to the ground terminal, and the diagonal monitor electrodes 10 and 13 crossing the same are connected to the monitor detection terminal 17.
Further, the detection electrode 6 is connected to the detection terminal 18.
FIG. 1 is a perspective view showing an electrically connected state of these, in which 19 and 20 are power supply terminals, and lead wires A respectively.
Connected by The lead wire A connecting the detection terminal 18 and the detection electrode 6 is connected to the tuning fork arms 4a, 4b, 5
It is connected to the detection electrode 6 below a and 5b.

In the above structure, the tuning fork arm 4
As shown in FIG. 2, a and 5a are polarized in the same direction as the thickness direction with an electric field strength of 3 kV / mm.
b and 5b were also polarized in the same direction in the thickness direction but with an electric field strength of 3 kV / mm in the opposite direction. In FIG.
The polarization directions are indicated by P1 and P2.

In the above structure, the drive electrodes 7, 8, 11, 12 from the first and second drive power supplies 15, 16 are connected.
When a signal is supplied to the tuning fork arms 4a and 5a, the tuning fork arms 4a and 5a vibrate in the lateral direction in FIG. 2, and accordingly, the tuning fork arms 4b and 5b also resonate and vibrate in the lateral direction.

This point will be specifically described below. Now, at a certain point in time, the tuning fork arms 4a and 5 will be described.
A signal of opposite phase is applied to the drive electrodes 8 and 12 on the inner surface side of a. When viewed from the polarization direction P1, a negative electric field is applied to the drive electrode 8 and a positive electric field is applied to the drive electrode 12, which is Since both tuning fork arms 4a and 5a apply a negative electric field to the lower surface side in FIG. 2, that is, to the side opposite to the polarization direction,
As a result, the inner surfaces of the tuning fork arms 4a and 5a, that is,
The tuning fork arms 4b and 5b are contracted and bent inward, that is, toward the right side in FIG. Conversely, on the outside of the tuning fork arms 4a and 5a, an electric field in the same direction as the polarization direction is applied from the drive electrodes 7 and 11, so that an extension action occurs, and as a result
At this time, the tuning fork arms 4a and 5a are bent inward.
At this time, the tuning fork arms 4b and 5b correspondingly bend to the tuning fork arms 4a and 5a side. However, if the signals supplied from the first and second drive electrodes 15 and 16 are reversed at the next time point, conversely, the tuning fork arms 4a, 5a, 4b, and
Both 5b will bend outward and will vibrate resonantly.

Next, when an angular velocity is applied in a situation where such inward and outward vibrations are repeated, the tuning fork arms 4a, 5a, 4b, 5b are deflected in the thickness direction by the principle of Coriolis force, and the degree of deflection is The angular velocity signal is taken out through the detection electrode 6 and the detection terminal 18. For example, if the tuning fork arms 4a and 5a are bent in the direction in which the lower surface side of the tuning fork arm 4a in FIG. 2 extends and the upper surface side of the tuning fork arm 5a in FIG. 2 contracts, the drive electrodes 7,
8 is the polarization direction, which extends in the orthogonal direction and positive charge is generated, and the drive electrodes 11 and 12 contract in the orthogonal direction opposite to the polarization direction, and the positive charge is also generated. Become. At this time, the tuning fork arm 4 in contact with the detection electrode 6
Negative charges are generated in the portions a and 5a, and negative charges are also generated in the portions connected to the tuning fork arms 4b and 5b, which are taken out from the detection terminal 18. On the contrary, when the tuning fork arms 4a and 5a extend on the drive electrodes 11 and 12 side and contract on the drive electrodes 7 and 8 side due to the addition of the angular velocity, a positive charge is taken out to the detection terminal 18 by the same theory.

Further, the tuning fork arms 4a and 5 are driven during driving.
The signals for driving a, 4b and 5b are the tuning fork arms 4a and 5b.
Although they are supplied to drive a, 4b, and 5b, they are canceled as signal components, so that this drive signal is not mixed with the detection signal detected via the detection electrode 6.

FIG. 3 shows the circuit diagram, and the detection terminal 18 is inputted to the inverting input terminal of the charge amplifier composed of the amplifier 21 and the capacitor C1. The output terminal 27 of the charge amplifier is connected to the synchronous detection circuit 22 and the filter 23, and finally to the output terminal 24.
The inverting amplifier composed of the resistors R1 and R2, the variable resistor Rx, and the amplifier 25 is the first and second driving power sources 15 and 1.
It is for making 6. Reference numeral 26 is an AGC amplifier for stabilizing the amplitude of the tuning fork.

FIG. 4 shows another embodiment of the angular velocity sensor of the present invention, in which the polarization direction P3 of the tuning fork arms 4b and 5b is changed to the same direction as the polarization direction P1. Therefore, in this case, since the detection electrode cannot take the Coriolis signal components of the tuning fork arms 4a, 5a and 4b, 5b together as in the case shown in FIG. 2, it is separated from the detection electrodes 18a, 18b, respectively. In this case, the Coriolis signal components obtained from the tuning fork arm are inverted and then added up.

[0017]

As described above, in the angular velocity sensor of the present invention, at least one tuning fork arm of the superposed U-shaped first and second piezoelectric bodies is arranged in the same direction as the superposed thickness direction. By forming the tuning fork arm structure in which the first and second piezoelectric bodies are polarized, the driving signal is supplied from the first driving power source to the first and third driving electrodes on the diagonal line of the tuning fork arm,
Further, since the second and fourth drive electrodes are supplied with a drive signal having a phase opposite to that of the first drive power supply from the second drive power supply, the signal component for driving the tuning fork arm works as a tuning fork drive. These drive signals are canceled by each other and are not mixed with the detection signal detected through the detection electrode. As a result, the angular velocity detection capability can be enhanced with high accuracy.

Furthermore, by making the polarization directions of the left and right tuning fork arms opposite to each other, the Coriolis force obtained by the left and right tuning fork arms becomes in phase with the signal on the detection electrode.
Since the summing is processed on the detection electrodes, no summing circuit is required, which is very simple.

The detection electrodes 18a and 18b are separated by making the polarization directions of the left and right tuning fork arms the same, and the signal components obtained from one tuning fork arm are inverted and then obtained from each tuning fork arm. The ability to detect angular velocity could be improved by summing the signal components.

Further, when the tuning fork arm is driven by subjecting the electrode portion provided in the drive / detection portion as a polarization portion to the polarization processing, only the vicinity of the electrode is subjected to the polarization processing, so that an unnecessary vibration component is generated. The generated noise component can be made very small.

[Brief description of drawings]

FIG. 1 is an assembled perspective view showing an embodiment of an angular velocity sensor of the present invention.

FIG. 2 is a schematic diagram showing a main part of the sensor.

FIG. 3 is a circuit diagram of the sensor.

FIG. 4 is a schematic diagram showing a main part of another embodiment of the angular velocity sensor of the present invention.

[Explanation of symbols]

 4a tuning fork arm 4b tuning fork arm 5a tuning fork arm 5b tuning fork arm 6 detection electrode 7 drive electrode 8 drive electrode 9 monitor electrode 10 monitor electrode 11 drive electrode 12 drive electrode 13 monitor electrode 14 monitor electrode P1, P2 polarization direction

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyuki Shimizu 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A U-shaped first and second piezoelectric body superposed through a detection electrode, and the first piezoelectric body is provided on a surface of at least one tuning fork arm opposite to the detection electrode. A first and a second drive electrode, and a second piezoelectric electrode facing the tuning fork arm provided with the first and second drive electrodes, the second piezoelectric body being provided on a surface of the tuning fork arm opposite to the detection electrode. A first and a fourth drive electrode, a first drive power source is connected to the first and third drive electrodes on the diagonal line of the first to fourth drive electrodes through the detection electrode. Similarly, the first and second driving electrodes, which are diagonally arranged through the detection electrodes
The second drive power source is connected so as to supply a signal having a phase opposite to that of the drive power source, and at least one tuning fork arm of the U-shaped first and second piezoelectric bodies has a superposed thickness. An angular velocity sensor having a tuning fork arm structure in which first and second piezoelectric bodies are polarized in the same direction. 2. The angular velocity sensor according to claim 1, wherein the drive electrode is similarly provided on the other tuning fork arm, and the polarization directions of the left and right tuning fork arms are opposite to each other. 3. The angular velocity sensor according to claim 1, wherein the drive electrode is also provided with the other tuning fork arm, and the left and right tuning fork arms are polarized in the same direction. 4. A structure in which only the portion provided with the drive electrode is subjected to polarization treatment.
3. The angular velocity sensor according to any one of 3 above.