JPH06229764A - Piezoelectric oscillation gyro - Google Patents

Abstract

PURPOSE:To prevent the leakage of mechanical oscillation while protecting against external electromagnetic noise. CONSTITUTION:The case of a piezoelectric oscillation gyro is constituted of a plastic case body 13 and a conductor layer 12 provided on the outer surface of the case body 13. The case may be metallic and in that case the case is connected with the earth terminal of an external circuit board through a conductive rubber-like elastic body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a piezoelectric vibrator, in particular, of a gyroscope used for attitude control of a moving body such as a ship or an automobile and equipment mounted on the moving body itself, an automobile navigation system, and the like. The present invention relates to a piezoelectric vibration gyro device.

[0002]

2. Description of the Related Art A vibrating gyroscope is a gyroscope that utilizes a mechanical phenomenon in which a Coriolis force is generated in a direction perpendicular to a vibrating direction when a rotating angular velocity is applied to a vibrating body.

Generally, in a complex vibration system configured to be able to excite vibrations in two directions that are orthogonal to each other, when one of the vibrations is excited and the vibrator is rotated, the above-mentioned Coriolis force acts to make the vibration perpendicular to this vibration. A force acts in the direction, and the other vibration is excited. Since the magnitude of this vibration is proportional to the magnitude of the vibration on the input side and the angular velocity of rotation, the magnitude of the rotational angular velocity is changed from the magnitude of the output voltage proportional to the magnitude of this vibration when the input voltage is constant. You can ask.

5 and 6 are perspective views of a conventional vibrating gyro device, in which a drawn metal case 11 is used to prevent electromagnetic noise from the outside. Also,
As shown in FIG. 5, the pin terminals 15 for mounting the external circuit board are projected from the lower end.
As shown by, it is mounted on the external circuit board 22.

At this time, the metal case 11 and the earth pattern of the external circuit board 22 are brought into contact with each other to obtain the earth.

[0006]

However, since metal is generally used for a vibrator for a mechanical filter, a piezoelectric buzzer, etc., the metal case has a small mechanical loss against vibration and is made of a thin metal plate. Is a case that the case itself resonates due to the vibration of the internal vibrator that propagates through the support of the vibrator or propagates in the air, especially in applications where two or more vibration gyros are used in one system,
Vibrations propagating from the case in the air or through the gyro support member interfere with each other to form a noise signal, degrading the characteristics of the vibration gyro.

Therefore, the technical problem of the present invention is to eliminate the drawbacks of the conventional vibrating gyroscope described above, prevent leakage of mechanical vibration, and prevent the influence of electromagnetic noise from the outside. To provide a vibrating gyro.

[0008]

According to the present invention, a piezoelectric vibrator configured to couple two vibrations orthogonal to each other in a cross section through a Coriolis force is fixed to one surface of a fixed base, and the one surface is fixed. In a piezoelectric vibrating gyro device including a piezoelectric vibrator and a case, the case includes a case body made of plastic, and a conductor layer provided on at least one of an inner surface and an outer surface of the case body. A piezoelectric vibrating gyro device characterized by being provided.

According to the present invention, a rod-shaped piezoelectric vibrator configured to couple two vibrations orthogonal to each other in a transverse section through Coriolis force is fixed to one surface of a fixed base, and the one surface is the rod-shaped piezoelectric vibration. A piezoelectric vibrating gyro device comprising a child case covered with a metal case, and the metal case connected to an earth terminal of an external circuit board. A piezoelectric vibrating gyro device characterized by being connected via a body is obtained.

According to the present invention, a rod-shaped piezoelectric vibrator configured to couple two vibrations orthogonal to each other in a cross section through Coriolis force is fixed to one surface of a fixing base made of a plate, and the one surface is fixed. A piezoelectric vibrating gyro device comprising a rod-shaped piezoelectric vibrator and a metal case covering the piezoelectric vibrating gyro device, wherein an inner case made of foam plastic is provided inside the metal case so as to surround the vibrator. can get.

According to the present invention, in the piezoelectric vibrating gyro device, the circuit board provided with the vibrator is mounted on the inner case, and the inner case is provided with a spacer function for positioning the metal case. A piezoelectric vibrating gyro device is obtained.

[0012]

In the present invention, the piezoelectric vibrating gyro body is housed inside a plastic case having a conductive film on its outer surface. Since the mechanical loss of plastic against vibration is several orders of magnitude higher than that of metal, even if the vibration of the piezoelectric vibrator propagates in the air or propagates through the support to the case, it is absorbed by the case and is transmitted to the outside. Does not propagate. In addition, external vibration is absorbed by the case and does not affect the internal piezoelectric vibrator. Further, a conductor layer is formed on most of the outer surface or the inner surface of the plastic case of the piezoelectric vibrating gyro device of the present invention. Therefore, it prevents electromagnetic noise from the outside and prevents the electromagnetic noise generated by itself from being emitted to the outside.

In the present invention, the metal case and the ground terminal of the external circuit board are electrically connected to each other through the conductive rubber-like elastic body. Therefore, since the metal case is electrically connected to the ground terminal of the external circuit board, electromagnetic noise can be easily blocked, and the metal case is in mechanical contact with the rubber elastic body. Therefore, not only can mechanical vibrations that propagate from the metal case to the external circuit board be blocked, but also mechanical vibrations of the metal case itself can be suppressed, and vibrations that propagate into the air through the metal case can also be suppressed.

In the present invention, the vibrator of the piezoelectric vibrating gyro is enclosed in a metal case while being surrounded by an inner case made of foam plastic. Since plastic has a mechanical loss that is several orders of magnitude greater than that of metal, and innumerable bubbles are formed in this inner case, the vibration propagated from the piezoelectric vibrator into the air is It is absorbed by the case and does not propagate to the outside. Furthermore, even if the inner case used in the piezoelectric vibrating gyro device of the present invention is made of plastic having a relatively high hardness, the bubbles do not impair the vibration absorbing effect. It can have a function.

[0015]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a perspective view showing an example of the structure of the piezoelectric vibrating gyro main body. The strip electrodes 2, 3 in the lengthwise direction are formed on the outer peripheral surface of the piezoelectric ceramic cylinder 1 at positions that divide the circumference into six equal parts.
4, 5, 6 and 7 are formed. These strip electrodes 2, 3, 4, 5, 6 and 7 are piezoelectric ceramic columns 1
It can be easily obtained by directly forming by curved screen printing on the outer peripheral surface of ′ or by removing the unnecessary portion of the electrode formed on the entire surface by plating or the like by photoetching. The strip electrodes 2, 3, 4, 5, formed in this way
Every other strip electrodes 6 and 7 are electrically connected to each other to form two terminals, and the piezoelectric ceramic cylinder 1'is polarized in a direction perpendicular to the length direction of the strip electrodes. The electrodes are electrically connected to serve as a ground electrode, the remaining three strip electrodes are used as terminals, and the terminals are used as drive electrodes, and the terminals are used as detection electrodes. An input voltage is applied to the drive electrode terminals to generate bending vibration in the piezoelectric ceramic cylinder 1 '. Hereinafter, the piezoelectric ceramic cylinder 1 ′ that generates bending vibration is referred to as the piezoelectric vibrator 1. In this state, when the piezoelectric vibrator 1 is rotated about an axis parallel to its central axis, a Coriolis force acts on the piezoelectric vibrator 1 in a direction perpendicular to the bending vibration direction, and this direction Bending vibration occurs. As a result, a voltage proportional to the magnitude of the rotation angular velocity is generated at the detection electrode terminal and. The piezoelectric vibrator 1 has a soft elastic layer 8, such as silicon rubber, at the position of a vibration node when the bending vibration resonates.
It is supported by a support 9 via 8'and is fixed to a fixed substrate 10 of the gyro in which a drive / detection circuit is formed. The above has the same configuration as the conventional example.

FIG. 2 is a perspective view showing the casing structure of the piezoelectric vibrating gyro device of the first embodiment of the present invention. The vibrating gyro main body shown in FIG. 1 is a plastic having a conductor layer 12 plated on its outer surface. Case body 13
It is stored inside.

In the piezoelectric vibrating gyro device according to the first embodiment of the present invention shown in FIG. 2, plastic is used as the material of the case body. By the way, generally, the mechanical loss due to vibration of plastic is several orders of magnitude higher than that of metal. That is, the mechanical quality factor (the reciprocal of the mechanical loss) in the case of metal is several thousand to tens of thousands, whereas in the case of plastic, it is about several tens at most. Therefore, the vibration of the internal piezoelectric vibrator 1 propagates in the air,
Even if it propagates to the case through the support, it is absorbed by the case and does not propagate to the outside. In addition, vibrations from the outside that have propagated through the air, the gyro fixed substrate 10, etc. are also absorbed by the case and do not affect the internal piezoelectric vibrator 1 (see FIG. 1).

The plastic case 13 of the piezoelectric vibrating gyro device according to the first embodiment of the present invention has a conductor layer 12 formed on most of its outer surface or inner surface. Therefore, it prevents electromagnetic noise from the outside and prevents the electromagnetic noise generated by itself from being emitted to the outside.

FIG. 3 is a perspective view showing the structure of the vibrating gyro device of the second embodiment of the present invention. When the piezoelectric vibrating gyro device is fixed to the external circuit board 22, the outer case 11 made of metal and the external circuit. The ground terminal 23 of the substrate 22 is electrically connected via conductive rubbers 24 and 24 '.

In the piezoelectric vibrating gyro device according to the second embodiment of the present invention shown in FIG. 3, a metal is used as the material of the outer case 11, and a ground terminal of the external circuit board 22 is provided through the conductive rubbers 24 and 24 '. Since it is electrically connected to 23, electromagnetic noise can be easily blocked. In addition, according to the piezoelectric vibrating gyro device of the second embodiment of the present invention, the outer case 11 and the external circuit board 22 are mechanically in contact with each other through the conductive rubber that is a soft elastic body. Not only can the mechanical vibration propagating from 11 to the external circuit board 22 be blocked, but also the mechanical vibration of the outer case 11 itself can be suppressed, and the vibration propagating into the air through the outer case 11 can be greatly suppressed. .

Therefore, in the piezoelectric vibrating gyro device according to the second embodiment of the present invention, in addition to reducing the vibration leakage and electromagnetic noise generated by itself, the gyro characteristic is also against the external vibration and electromagnetic noise. A piezoelectric vibrating gyro device with less deterioration can be obtained.

FIG. 4 is a perspective view showing the casing structure of the vibrating gyroscope according to the third embodiment of the present invention. As shown in FIG. 4, the vibrating gyro device is housed in a metal case (not shown) in a state in which the vibrating gyro is surrounded by a plastic inner case 32 having numerous bubbles. This plastic inner case 32 is a box type having a bottom and four walls,
The bottom has a through hole through which the pin terminal 15 is inserted. The plastic inner case 32 has a function of a positioning spacer when being housed in the metal case.

In the piezoelectric vibration gyro device shown in FIG. 4, plastic is used as the material of the inner case 32. Generally, the mechanical loss of plastic due to vibration is several orders of magnitude higher than that of metal. That is, in the case of metal, the mechanical quality factor (the reciprocal of the mechanical loss is several thousands to tens of thousands, whereas in the case of plastic, it is about several tens at most. Furthermore, in the third embodiment of the present invention. In such a piezoelectric vibration gyro device, a foamed plastic having innumerable bubbles is used as the material of the inner case 32.
Even if the vibration of the internal oscillator propagates in the air or propagates to the case through the support, it is absorbed by the inner case and does not propagate to the outside. In addition, vibrations from the outside that have propagated in the air or through the gyro fixed substrate are absorbed by the plastic inner case and do not affect the internal vibrator.

Further, in the piezoelectric vibrating gyro device according to the third embodiment of the present invention, since the same metal case as the conventional one is used, the electromagnetic noise from the outside can be prevented and the electromagnetic noise generated by oneself can be prevented. I will not give it to you.

[0026]

As described above, according to the present invention,
The mechanical vibration and electromagnetic noise leaking from the piezoelectric vibrating gyro device are reduced, and especially when multiple piezoelectric vibrators, piezoelectric vibrating gyro bodies or piezoelectric vibrating gyro devices are used in one system, the gyro characteristics due to mutual interference A piezoelectric vibrating gyro device with less deterioration can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration example of a piezoelectric vibrating gyro body.

FIG. 2 is a perspective view showing a piezoelectric vibrating gyro device according to a first embodiment of the present invention.

FIG. 3 is a perspective view showing a piezoelectric vibrating gyro device according to a second embodiment of the present invention.

FIG. 4 is a perspective view showing a piezoelectric vibrating gyro device according to a third embodiment of the present invention.

FIG. 5 is a perspective view showing an example of a conventional piezoelectric vibration gyro device.

6 is a perspective view showing an example in which the piezoelectric vibration gyro device of FIG. 5 is mounted on an external circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 1'Piezoelectric ceramic cylinder 2,3,4,5,6,7 Strip electrode 8,8 'Soft elastic body layer 9 Supporting tool 10 Circuit board 11 Outer case 12 Plastic case 13 Conductor layer 15 Pin terminal 22 External circuit board 23 Ground terminal 24, 24 'Conductive rubber 32 Plastic inner case

Claims (4)

[Claims] 1. A rod-shaped piezoelectric vibrator configured to couple two vibrations orthogonal to each other in a cross section through a Coriolis force, is fixed to one surface of a fixing base made of a plate, and the one surface is the rod-shaped piezoelectric vibration. In a piezoelectric vibrating gyro device including a child and a case, the case includes a case body made of plastic, and a conductor layer provided on at least one of an inner surface and an outer surface of the case body. Characteristic piezoelectric vibrating gyro device. 2. A rod-shaped piezoelectric vibrator configured to couple two vibrations orthogonal to each other in a cross section through Coriolis force is fixed to one surface of a fixing base, and the one surface is made of metal together with the rod-shaped piezoelectric vibrator. In a piezoelectric vibrating gyro device, which is covered with a case, and the metal case is connected to an earth terminal of an external circuit board, the case is connected to the earth terminal of the external circuit board via a rubber-like elastic body having conductivity. A piezoelectric vibration gyro device characterized by being connected. 3. A rod-shaped piezoelectric vibrator configured to couple two vibrations orthogonal to each other in a cross section through a Coriolis force, is fixed to one surface of a fixing base made of a plate, and the one surface is the rod-shaped piezoelectric vibration. A piezoelectric vibrating gyro device including a child and a metal case, wherein an inner case made of foam plastic is provided inside the metal case so as to surround the vibrator. 4. The piezoelectric vibrating gyro device according to claim 3, wherein a circuit board provided with the vibrator is attached to the inner case, and a spacer function for positioning the metal case is added to the inner case. A piezoelectric vibration gyro device characterized by: