JPH087068B2 - Sound piece type vibration gyro - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sound piece type vibration gyro for detecting a rotation speed.

[Conventional technology]

A conventional sound piece type vibration gyro is illustrated in FIGS. 3 (a), (b) and (c). In this figure, a piezoelectric ceramic 2 for driving is placed at the center of one side surface of a sound piece 1 having a square cross section.
The piezoelectric ceramic 3 for extraction is adhered to the center of the adjacent side surface that is perpendicular to the side surface. When a signal is applied to the driving piezoelectric ceramic 2 in the sound piece type vibration gyro, the sound piece makes bending vibration in the X-axis direction in the vibration mode as shown in FIG. 3B, but the extraction piezoelectric ceramic Since the driving piezoelectric ceramic is bonded to the central portion of the side surface at a right angle to the bonding surface, the charges generated in the extracting piezoelectric ceramic have the same positive and negative amounts and cancel each other out. Therefore, no week force is generated in the piezoelectric ceramic for extraction. However, when the real piece vibration gyro is rotated about the Z axis as shown in FIG. 3 (a), a force in the Y axis direction due to the Coriolis force is generated,
Lateral vibration in the Y-axis direction as shown in FIG. 3 (c) is also generated. Therefore, an output is produced in the extracting piezoelectric ceramic. The Coriolis force Fc is expressed by the following equation.

Fc = −2mΩ In this formula: m is the equivalent mass, Ω is the angular velocity of rotation, and is the velocity in the Y-axis direction.

As described above, the angular velocity of rotation with respect to the Z axis can be detected by the output generated in the extracting piezoelectric ceramic.

[Problems to be solved by the invention]

In the conventional sound piece type vibration gyroscope described above, the driving and extracting piezoelectric ceramics are accurately adhered to the centers of the respective surfaces of the sound piece, so that in the driving piezoelectric ceramics,
The vibration in the X direction is not driven, and the piezoelectric ceramic for extraction does not extract the vibration in the Y direction. Therefore, when the bonding position of the piezoelectric ceramic is not exactly in the center of the surface but is slightly displaced, vibration in the X direction is also driven by the driving piezoelectric ceramic. Similarly, the piezoelectric ceramic for extraction also extracts vibration in the Y direction. Therefore, there is a drawback that an output is generated even when the sound piece type vibration gyro does not rotate, and only the rotation component cannot be accurately detected. Further, since the driving piezoelectric ceramic and the extracting piezoelectric ceramic are close to each other, there is a drawback that a capacitance exists between both piezoelectric ceramics and a signal leaks directly between the piezoelectric ceramics, so that an output is easily generated even when there is no rotation.

[Means for solving problems]

An object of the present invention is to provide a sound piece type vibration gyro which eliminates the above-mentioned drawbacks.

The sound piece type vibrating gyroscope of the present invention comprises a sound piece having a cross section in which one corner of a square is chamfered, one piezoelectric ceramic bonded to one side surface adjacent to the chamfer of the sound piece, and the side surface. And a pair of piezoelectric ceramics, one of which is adhered to each of the two side surfaces adjacent to each other.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (a), (b) and (c) are a perspective view, a front view and a right side view of an embodiment of the present invention. In the figure, a driving piezoelectric ceramic 2 is bonded to one side surface of the sound piece 1 having a chamfered portion 4 in contact with the chamfered portion. Also,
Adjacent to the surface where the driving piezoelectric ceramic is bonded 2
One piezoelectric ceramic for extraction on each side 3,
3'is glued. These extraction piezoelectric ceramics are arranged on the respective bonding surfaces along the corners that contact the surface on the opposite side of the bonding surface of the driving-side piezoelectric ceramics. In FIG. 1 (c), +-is a display of the polarity on the front side to indicate the polarization direction of the piezoelectric ceramic. With this sound piece type vibration gyro, when a signal is input to the driving piezoelectric ceramic,
As shown in FIG. 1C, since the chamfered portion 4 is provided in the vicinity of the driving piezoelectric ceramic 2, two vibrations in a vibration mode degenerated in the X direction and the Y direction are excited. Both vibrations have opposite polarities in the extracting piezoelectric ceramics 3 and 3 ', and the same amount of electric charge is generated, so that the electric charges are canceled.
Therefore, no output is generated when there is no rotation. When there is rotation, Coriolis forces Fxy (X component) and Fxy (Y component) of the following equations are generated.

Fxy = 2m ₂ Ω Fxy = −2m ₁ Ω where m ₁ and m ₂ are equivalent masses, Ω is the angular velocity of rotation, and is the velocity in the X-axis and Y-axis directions, respectively. Fxy (X component) generated in these X direction and Y direction, Fxy
The (Y component) has different values because the equivalent masses m ₁ and m ₂ are different. Therefore, the amount of electric charge generated in the extracting piezoelectric ceramics 3 and 3'is also different, so that an output is generated. An equivalent circuit of the present sound piece type vibrator is shown in FIG. Since Z ₁ = Z _{2 in} this circuit, non-rotation results in Fxy = 0, Fxy = 0 and output is 0. At the time of rotation, Fxy ≠ 0 and Fxy ≠ 0, and an output is generated.

In the sound piece type vibration gyroscope of the present invention, since the piezoelectric ceramics on the extraction side are arranged along the corners of the sound piece, the piezoelectric ceramics can be easily positioned and are not easily displaced. Further, since the distance between the piezoelectric ceramics on the drive side and the extraction side can be made large, there is an advantage that the electrostatic coupling between both piezoelectric ceramics is also small.

〔The invention's effect〕

As described above, according to the present invention, by dividing the piezoelectric ceramic on the extraction side into two pieces, the displacement of the bonding position is unlikely to occur, and the coupling between the input and the output can be reduced.

[Brief description of drawings]

1 (a), (b) and (c) are respectively a perspective view, a front view and a right side view of a sound piece type vibration gyro according to the present invention,
FIG. 2 is an equivalent circuit diagram of the sound piece type vibration gyro of the present invention, and FIG. 3 (a) is a perspective view of a conventional sound piece type vibration gyro.
It is a figure for explaining the figure (b) and (c) vibration mode. In the figure, 1 ... sound piece, 2 ... drive side piezoelectric ceramic, 3,3 '... extraction side piezoelectric ceramic, 4 ... chamfered portion.

Claims (1)

[Claims] 1. A sound piece type vibrating gyroscope comprising a sound piece having a square cross section with one corner chamfered and three piezoelectric ceramics bonded to the side surfaces of the sound piece. One of the sheets is arranged on the side surface in contact with the chamfer, and the remaining two sheets of the same shape are arranged on two side surfaces adjacent to the one side surface along the corners not in contact with the one side surface, respectively. Characteristic type vibration gyro.