JPS62148812A - Gyroscope device - Google Patents

Abstract

PURPOSE:To obtain a small-sized, high-performance gyro of simple structure by providing a couple of interdigital electrodes on a couple of surfaces which are parallel to the angular speed detection axis of a piezoelectric body installed on a base and perpendicular to its polarization axis. CONSTITUTION:When the left reed-screen type electrode 13a on a surface I is driven, a surface acoustic wave SAWI is led out of the right interdigital electrode 13b s a delay electrical signal, which is fed back to the left reed-screen type electrode 13a through an amplifier 15, so that oscillations are caused when the gain of the whole system is >=1. When an angular speed OMEGA inputted to an input angular speed axis Z-Z varies, the elastic constant, etc., of the piezoelectic body 12 vary with the acceleration of Coriolis force and the propagation speed V of the surface acoustic wave SAWI varies, so that the oscillation frequency varies. The constitution of respective elements and the connection of an amplifier 18 on the surface II are the same with the surface I. For the purpose, the outputs of the two amplifier 15 and 16 are supplied to a mixer 18 to detect the differential frequency between the both and this detection output is inputted to a frequency-voltage converter 20 through a low-pass filter 19, so that the angular speed OMEGA inputted to the gyro device can be detected as a voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gyro device, and particularly to a novel gyro device that utilizes surface acoustic waves.

[Conventional technology]

Although the present invention is different in principle from various types of gyro devices conventionally used, a vibrating gyro device whose principle is relatively similar to the present invention is used as a conventional example.
This will be explained with reference to FIG.

In the example shown in the figure, a tuning fork (1) is attached to a base (2) via a flexible shaft (3). A displacement detector (6) and a drive coil (4) are installed near the top of the tuning fork (1), and the output of the displacement detector (6) is passed through a drive amplifier (5) and input to the drive J coil (4). , the vibration amplitude of the tuning fork (1) is kept constant. The axis of the deflection axis (3) of the tuning fork (1) (
When the angular velocity Ω is input around the tuning fork (
Coriolis force Fc corresponding to the vibration velocity v1 of 1) and the human force angular velocity Ω is generated, and as a result, the entire tuning fork (1)
-2> rotates alternately. That is, torsional vibration occurs in the tuning fork (1).

In the conventional example shown in FIG. 4, this torsional vibration of the tuning fork (1) is detected by a torsion detector (8), and the detected output and the output of the drive amplifier (5) are synchronized by a demosimulator (7). By rectifying the current, the angular velocity Ω of the person is detected and a gyro device is constructed.

[Problem that the invention seeks to solve]

However, in such a conventional vibrating gyro device, precision machining is required for the tuning fork (1), the flexible shaft (3), etc., and the tuning fork (1) itself is unbalanced! l
1i (Z-Z), which causes a bias error in the output, requires precise balance of the tuning fork + 1), and requires a lot of time to adjust the balance;
It had many drawbacks such as high power consumption and large size.

[Means for solving problems]

In view of the above-mentioned problems, the present invention provides a new gyro device that eliminates the drawbacks of the conventional gyro device. Two pairs of interdigital electrodes (13a) are fabricated on a piezoelectric material by means such as photolithography.

(13b); (14a), (14b), and a driving means (14b) for driving the piezoelectric body using the interdigital electrodes.
15), (16), (21), (24a), (24
b) , (25) and a detection means (1B) for detecting a change in frequency or a change in phase difference due to a change in the velocity of the surface acoustic wave (SAWI), (SAWI[) excited by the interdigital electrode. 22).

[Effect]

According to the above-described gyro device according to the present invention, Coriolis acceleration acts on the piezoelectric body (12) due to the angular velocity Ω applied thereto, and the elastic constant etc. of the piezoelectric body change. Therefore, surface acoustic waves (SAWI), (SAW n
) changes in the propagation speed ■, so this change in speed can be considered as a change in phase difference, or as a change in the interdigital electrodes (13a), (1
3b), (14a), (14b) and the amplifier (15
) and (16) constitute an oscillator, and the surface acoustic wave (
If the propagation velocity change of SAWI) and (S static ■) is detected as a frequency change, the angular velocity Ω of the base (1)) with respect to the inertial space can be detected.

〔Example〕

Hereinafter, the present invention will be explained based on FIGS. 1 to 3.

FIG. 1 is a perspective view of an embodiment of the gyro device of the present invention. In the figure, (1)) is a base, and this base (1)
)) A rectangular parallelepiped-shaped piezoelectric body (12) whose polarization axis is (A-A') is installed on top. A pair of surfaces (1) and (II) parallel to the input angular velocity axis (Z - Z) of this piezoelectric body (12)
, a pair of interdigital electrodes (13a) and (13b), respectively.
and (14a) and (14b) are installed.

In addition, at each end of the surfaces (1) and (II) of the piezoelectric body (12) on one end side of each interdigital electrode (13a) to (14b),
In order to remove reflected waves, sound wave absorbing substances (17a) to (1
7d). Furthermore, an amplifier (15
) and (16) are electrically connected to each other.

The operation of this gyro device will be specifically explained.

If the left interdigital electrode (13a) of the surface (1) is driven and shifted,
The resulting surface acoustic wave (SAWI) is extracted as a delayed electrical signal at the right interdigital electrode (13b). When this signal is fed back to the left interdigital electrode (13a) via the amplifier (15), oscillation occurs when the gain of the entire system is 1 or more. The oscillation frequency f at this time is determined by the following phase condition.

2π・r−L □+φe =2nπ ...(1) ■ Here, L is the general propagation distance of surface acoustic waves (SAWI),
■ is the propagation speed of the surface acoustic wave (SAWI), ψe is the amplifier (15) and the interdigital electrodes (13a), (13b)
The electrical phase delay at , n is the mode order of oscillation and is an integer.

Now, the angular velocity Ω input to the input angular velocity axis (Z − Z)
When changes, the piezoelectric material (12) due to Coriolis acceleration
The elastic constants etc. of change, and therefore the surface acoustic wave (SA[)
The propagation velocity V changes. However, the first left side in equation (1)
Since φe is negligibly small compared to the term, the oscillation frequency r changes due to a change in the propagation speed ■.

On the other hand, the configuration of each element in plane (II) is similar to that in plane (II).
1) Same configuration as above. Also, the connection of the amplifier (16) is the same as in the case of plane (1). The reason for this is that, with respect to the input angular velocity Ω, the propagation speeds ■ of the surface acoustic waves (SAWI) and (SAW II) on the two surfaces (1) and (II) increase and decrease inversely. For this reason, 2
The mixer (18) outputs the outputs of the amplifiers (15) and (16).
This detects the differential frequency between the two, and inputs this detection output to the frequency-voltage converter (20) via the low-pass filter (19). The angular velocity Ω can be detected as a voltage.

In the example of FIG. 1, amplifiers (15) and (1
6) The mixer (18), etc. are shown not to be on the piezoelectric body (12), but these circuits are placed on the surface so as not to interfere with the general propagation of surface acoustic waves (SAWI) and (SAWII). It can be installed on a plane perpendicular to (I) and (II).

Furthermore, by providing the antenna on the piezoelectric body (12), the mixer (8) can be placed separately from the amplifiers (15), (16), etc. without being connected with electric wires.

In addition, in the example shown in the same figure, the direction of the polarization axis of the piezoelectric body (12) is (A-A') and Rayleigh waves are used as surface acoustic waves. It is also possible to use waves.

FIG. 2 is a perspective view showing another embodiment of the invention. In the figure, parts corresponding to those in Figure 1 are given the same numbers,
The explanation thereof will be omitted.

In the example of FIG. 1, the oscillators on each surface (1) and (II) were constructed by a pair of interdigital electrodes and one amplifier, but in the example of FIG. power supply(
21), one of the interdigital electrodes (13a) and (14a) on the surface (I) and the surface (II) are driven, and the surface acoustic wave (S
This detects the phase delay due to AWI) and (SAWII). That is, the phase lag ψ in plane (I)
1 and the phase delay φ2 in the plane (n), a signal of (φ1-φ2) is extracted from the differential amplifier (22), and this phase difference signal is converted to the input angular velocity Ω by the rectifier circuit (23).
is detected as a DC voltage.

FIG. 3 is a perspective view showing still another embodiment of the present invention. In this figure, parts corresponding to those in FIGS. 1 and 2 are designated by the same numbers, and explanation thereof will be omitted.

In the example in Figure 3, the drive power source (
21), the surface (1) of the piezoelectric body (12), (If
A pair of interdigital electrodes (24a) and (24b) are provided on one surface (Ill) perpendicular to both of the interdigital electrodes ( 13a) and (14a).

The other configurations are approximately the same as the example shown in FIG.

In addition, in order to avoid complication, the base (1) is shown in Figure 3.
) and sound wave absorbing substances (17a) to (17d) are omitted.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects can be obtained.

Since the structure is simple, it is possible to obtain a compact, low-cost, and high-performance gyro.

Unlike mechanical gyros, there are no bearings or other sliding parts, so it is highly reliable and has a long life.

Unlike conventional vibrating gyroscopes, it does not require precise balancing and is easy to assemble.

By incorporating the antenna, the sensor section and the detection circuit section can be separated, allowing remote detection.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the invention, FIG. 2 is a perspective view of another embodiment of the invention, and FIG. FIG. 4 is a perspective view of a conventional vibrating gyroscope. In the figure, (1)) is the base, (12) is the piezoelectric material, and (13) is the base.
a), (13b), (14a), (14b), (
24a) and (24b) are interdigital electrodes, (15),
(16) and (25) are amplifiers, (17a) to (17d
) is a sound wave absorbing material, (18) is a mixer, (19) is a low-pass filter, (20) is a frequency-voltage converter, (21) is a
) indicates a drive power supply, (22) a differential amplifier, and (23) a rectifier circuit, respectively.

Claims (4)

[Claims] (1) a base, a piezoelectric body installed on the base, a pair of interdigital electrodes provided on each of a pair of surfaces parallel to the angular velocity detection axis of the piezoelectric body and perpendicular to its polarization axis; It consists of a driving means that generates a voltage to be applied to the interdigital electrodes, and a detection means that detects a change in frequency or a change in phase difference due to a change in the speed of the surface acoustic wave propagating between each pair of interdigital electrodes. A gyro device characterized by: (2) The gyro device according to claim 1 is characterized in that the direction of the polarization axis is parallel to the angular velocity detection axis. (3) The gyro device according to claim 1 is characterized in that the driving means and the detecting means are arranged on the piezoelectric body. (4) The gyro device according to claim 1, wherein an antenna is provided on the piezoelectric body, and the interdigital electrode and the detection means are placed separately to enable remote detection. shall be.