JPH07159177A - Piezoelectric vibration gyroscope device - Google Patents

Abstract

PURPOSE:To provide a piezoelectric vibration gyroscope device provided with a square pillar-shaped tuning fork vibrator with which offset noise by flexure vibration by driving is less likely to occur, and with which an S-N ratio can be set large. CONSTITUTION:This device is provided with an angular pole tuning fork type vibrator 2, piezoelectric elements 3 for driving provided at shaft parts 2d-1, 2d-2 of the vibrator 2, and piezoelectric elements 5 for detection provided at vibration parts 2a-1, 2a-2, at least. The piezoelectric element 3 for driving and the piezoelectric element 5 for detection are provided at perpendicular positional relation to each other, and a width A, on the right and left, of a turning fork- shaped surface of the angular pole tuning fork type vibrator 2 where the piezoelectric element 5 for detection is provided is set to be larger than a width D, on the right and left, of a tuning fork-shaped surface of the angular tuning form type vibrator 2 where the piezoelectric element 3 for driving is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrating gyro device used for detecting an angular velocity, for example, used in a rear wheel steering system of an automobile.

[0002]

2. Description of the Related Art Conventionally, there are tuning fork type gyroscopes or vibration type gyroscopes for detecting an angular velocity. For example, JP-A-59-170717 and JP-A-61-1919 are available.
No. 17, for example. JP-A-59-170
Japanese Patent No. 717 discloses that a tuning fork having a large inertial mass and a bending portion on a flat plate and capable of large-amplitude vibration is supported on a base by a piezoelectric element formed of a bimorph on one strip. The present invention relates to a gyro device with improved detection sensitivity.

On the other hand, Japanese Patent Application Laid-Open No. 61-191917 discloses that a driving or extracting piezoelectric ceramic is divided into two parts on the same arm of a tuning fork, and they are bonded along the corners so that the bonding position shifts. The present invention relates to a tuning fork type vibrating gyro device capable of detecting a stable angular velocity by reducing the coupling between the input and the output. However, the tuning fork vibrator, which is the angular velocity detecting portion of the gyro having the structure in which the piezoelectric body is bonded to the tuning fork vibrator made of metal as described above, has a complicated shape and requires a lot of man-hours for processing. Therefore, a tuning fork type gyro device including a simplified prismatic tuning fork vibrator has been proposed (Japanese Patent Application No.
272848). In the tuning fork type gyro device of this type, there is a problem that an offset noise having the same phase as the feedback voltage is likely to occur and the S / N ratio cannot be made large.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a piezoelectric vibration provided with a tuning fork vibrator having a simple structure in which offset noise is less likely to occur and the S / N ratio can be increased. It is an object to provide a gyro device.

[0005]

In order to solve the above-mentioned problems, a vibrating portion which is an upper end of a tuning fork shape having a prismatic cross section, a shaft portion which is continuous with the vibrating portion and is integrated with the shaft portion is a base. A prismatic tuning fork type oscillator consisting of a neck for fixing, a driving piezoelectric element driven by an AC voltage attached to the shaft of the oscillator, and a signal based on distortion generated by an angular velocity input from the outside. At least the detecting piezoelectric element is provided, and the driving piezoelectric element and the detecting piezoelectric element are attached in a positional relationship orthogonal to each other, and the prismatic tuning fork to which the detecting piezoelectric element is attached is further provided. The width of the tuning fork shaped surface of the die vibrator is set to be larger than the width of the tuning fork shaped surface of the prismatic tuning fork vibrator to which the driving piezoelectric element is attached. did.

[0006]

By adopting the above-mentioned means, the tuning fork shape of the prismatic tuning fork type vibrator to which the driving piezoelectric element is attached is equal to the width of the tuning fork shaped surface of the prismatic tuning fork type vibrator to which the detecting piezoelectric element is attached. With the configuration in which the width of the side surface of the surface is set larger to the left and right, the bending of the detection piezoelectric element, which is a cause of the offset noise, can be reduced, and the offset noise can be reduced. As a result, S / N
Can be dramatically improved.

[0007]

With the above operation, it is possible to provide a piezoelectric vibrating gyro device equipped with a tuning fork vibrator which can make offset noise less likely to occur and as a result have a large S / N ratio.

[0008]

【Example】

(First Embodiment) An embodiment of the present invention will be described below with reference to an example shown in the drawings. FIG. 1 is an overall configuration diagram showing the overall configuration of a piezoelectric vibration gyro device that is an embodiment of the present invention. The piezoelectric vibrating gyro device will be briefly described. Two vibrating parts having a rectangular cross section made of an elastic material such as metal are arranged in parallel to form a tuning fork type vibrator, and bending vibration is generated in each vibrating part. A piezoelectric element for driving and a piezoelectric element for detection that detects the stress generated in the vibrating portion due to the Coriolis force are joined to the side surfaces of each vibrating portion, and they are arranged and joined to the side surfaces orthogonal to each other. Has been done. The configuration of one embodiment will be described in detail below.

Reference numeral 1 is a piezoelectric vibrating gyro device of the present invention. Reference numeral 2 is a prismatic tuning fork type vibrator having a tuning fork shape including vibrating portions 2a-1, 2a-2 having a rectangular cross section, shaft portions 2d-1, 2d-2 and a neck portion 2c made of an elastic material such as metal. Yes, it is manufactured by wire cutting or sintering. Then, the vibrating portions 2a-1 and 2a of the vibrator 2 are
-2 is a shaft portion 2d-1, 2d- connected to the neck portion 2c.
It is provided at the tip of 2. Reference numeral 3 denotes a driving piezoelectric element provided by being bonded or bonded to the side surfaces 2e-1 and 2e-2 of the tuning fork-shaped shaft portions 2d-1 and 2d-2, and is a plate-shaped ceramic piezoelectric body such as PZT. Consists of. Reference numeral 4 denotes side surfaces 2f-1 and 2f of the tuning fork-shaped vibrating portions 2a-1 and 2a-2.
-2, which is a piezoelectric element for feedback provided by being bonded or bonded, and is made of a plate-shaped ceramic piezoelectric body such as PZT. 5
Is a piezoelectric element for detection provided by being bonded or bonded to the upper surfaces 2g-1 and 2g-2 of the vibrating portions 2a-1 and 2a-2 having a tuning fork shape, and is a plate-shaped ceramic piezoelectric body such as PZT. Consists of. The prismatic tuning fork vibrator 2 is firmly fixed to the base 6 by press fitting or the like by the neck portion 2c.

The bonding surface of the driving piezoelectric element 3 and the bonding surface of the feedback piezoelectric element 4 are parallel to each other, and the bonding surface of the driving piezoelectric element 3 and the feedback piezoelectric element 4 are parallel to each other.
The bonding surface of and the detection piezoelectric element 5 are arranged in an orthogonal relationship. Also, the upper surface 2g of the vibrating portions 2a-1 and 2a-2 having a tuning fork shape to which the detecting piezoelectric element 5 is adhered.
The width A of -1, 2g-2 is larger than the width D of the tuning fork-shaped shaft portions 2d-1, 2d-2 to which the driving piezoelectric element 3 is bonded, and the driving piezoelectric element 3 is bonded. The side surfaces 2e-of the tuning fork-shaped shaft portions 2d-1 and 2d-2
The width B of 1 and 2e-2 is the same as the width C of the side surfaces 2f-1 and 2f-2 of the tuning fork-shaped vibrating portions 2a-1 and 2a-2 to which the feedback piezoelectric element 4 is adhered. Has been made.

Next, the operation of the piezoelectric gyro device 1 having the above structure will be described. FIG. 2 shows the connection state of the driving piezoelectric element 3, the feedback piezoelectric element 4, and the detection piezoelectric element 5 to the electronic circuit section 10 serving as a power source. In the figure, 7 is a lead wire for connecting the driving piezoelectric element 3 and the output terminal of the driving section of the electronic circuit section 10, and 8 is the feedback piezoelectric element 4 and the electronic circuit section 1
Reference numeral 0 is a lead wire for connecting the input terminal of the drive unit, and reference numeral 9 is a lead wire for connecting the detection piezoelectric element 5 and the input terminal of the processing unit of the electronic circuit unit 10.

FIG. 3 is a diagram for explaining the operation of the piezoelectric gyro device 1. In the figure, a driving AC voltage is supplied to the driving piezoelectric element 3 from the electronic circuit section 10, and the AC voltage causes the vibrating sections 2a-1 and 2a-2 to move to the side surfaces 2f-1 and 2f-1, respectively. Two
It is vibrated in a driving direction which is a direction perpendicular to f-2. Along with this, the detection piezoelectric element 5 is also vibrated in the driving direction. At this time, a voltage is generated from the feedback piezoelectric element 4 due to the vibration in the driving direction by the driving piezoelectric element 3, and the vibration state is monitored so that the stable vibration state is set. The AC voltage and frequency supplied to the piezoelectric element 3 are controlled. When in this state,
When an angular velocity Ω is input from the outside, a Coriolis force is generated in a detection direction which is a direction perpendicular to the upper surfaces 2g-1 and 2g-2, and the vibrating portions 2a-1 and 2a-2, that is, the detection. The piezoelectric element 5 for bending also bends in the detection direction. Along with this bending operation, a minute electric signal is generated from the detection piezoelectric element 5 bonded to each of the vibrating portions 2a-1 and 2a-2, and is input to the processing portion of the electronic circuit portion 10. At this time, due to the displacement of the bonding position of the detection piezoelectric element 5, the non-uniform bonding state, the displacement of the neutral axis of the bending operation, etc., the detection piezoelectric element 5 generates the feedback piezoelectric element 4. Offset noise having the same phase as that of the applied voltage is generated, and the detection accuracy of the angular velocity deteriorates, that is, the S / N ratio deteriorates.

Here, FIG. 4 is an explanatory diagram of a mechanism of generating the above-mentioned offset noise. As a result of earnest studies on the generation mechanism of the offset noise, the present inventors were able to clarify that the generation mechanism of the offset noise is as follows. The mechanism of generating offset noise will be described below. In the figure, an AC voltage is applied to the driving piezoelectric element 3, and the vibrating portion 2a-
When 1 and 2a-2 are vibrating while bending in the driving direction, the voltage generated by the stress due to the strain in the driving direction of the detecting piezoelectric element 5 is not canceled in the plane of the detecting piezoelectric element 5. It is generated as offset noise. That is, to explain a case where the vibrating portions 2a-1 and 2a-2 are bent outward, the vibrating portion 2 will be described.
Since the outside portion of the bending neutral axis of the detection piezoelectric element 5 bonded to a-1 and a-2a-2 contracts and the inside portion extends, one of the detection piezoelectric elements 5 has Voltages of opposite phases are generated outside and inside the neutral axis of bending. Therefore, the neutral axis of bending of the vibrating portions 2a-1 and 2a-2 is
If the detection piezoelectric element 5 is adhered to the upper surfaces 2g-1 and 2g-2 so as to coincide with the center line of the detection piezoelectric element 5, the voltage of the opposite phase is applied to the detection piezoelectric element 5. Will be canceled within the plane. That is, the voltage portion of the voltage of the opposite phase that has not been canceled in the plane of the detection piezoelectric element 5 is generated as offset noise (the same applies to the case where the voltage is bent inward).

Therefore, according to the present invention, the vibrating section 2a-1,
The signal output from the feedback piezoelectric element 4 generated by the distortion of the driving direction of 2a-2 is the same as that of the vibrating section 2a.
Due to the distortion in the driving directions of a-1 and a-2, the detection piezoelectric element 5 has the same phase as the offset noise, and the magnitude of the offset noise is larger than that of the detection piezoelectric element 5.
Paying attention to the fact that there is a correlation with the bending amount of the vibrating parts 2a-1 and 2a-2 attached with, A> D as in the above-mentioned embodiment.
Configured to be. As a result, the bending of the detection piezoelectric element 5 in the driving direction, which is a cause of the offset noise, is reduced, and the offset noise can be reduced. Thereby, the S / N can be dramatically improved.

FIG. 5 shows the amount of generation of offset noise and the sensitivity of the piezoelectric vibrating gyro device 1 of the present invention with the piezoelectric vibrating gyro device (Japanese Patent Application No. 4-272848) of a prismatic tuning fork type vibrator as a conventional example. It is the figure which described the comparison result. In the figure, the vertical axis represents the offset noise occurrence rate and the sensitivity ratio. Offset noise of a piezoelectric vibrating gyro device of a prismatic tuning fork type vibrator (Japanese Patent Application No. 4-272848), which is a conventional example, and 1/2 of the value obtained by subtracting the D from the A when the sensitivity is 100. It shows the effect on the amount of protrusion of a certain detector. As is clear from the figure, the offset noise is gradually reduced as the amount of protrusion of the detection unit increases. Further, the sensitivity ratio has a smaller reduction rate than the offset noise. That is, it can be seen that the sensitivity ratio with respect to the offset noise occurrence rate increases, the angular velocity detection accuracy increases, and the S / N ratio of the present invention reaches about 3 times. From the above, it is possible to provide a piezoelectric vibrating gyro device equipped with a tuning fork vibrator in which offset noise having the same phase as the feedback voltage is unlikely to occur and which has a large S / N ratio.

Further, FIG. 6 shows the offset noise occurrence rate and the sensitivity ratio when the magnitudes of A and the detection portion overhang are fixed and the magnitude of C is changed. As is clear from the figure, in the present invention, the piezoelectric vibration gyro device of the prismatic tuning fork type vibrator as a conventional example does not affect the occurrence rate of offset noise (Japanese Patent Application No. 4-27).
2848), the sensitivity can be freely set between 10% and 80%. That is, S / N
In terms of ratio, the feature is that it can be freely set between 30% and 260%.

In the above example, the vibrating portions 2a-1 and 2a are used.
-2, the amount of protrusion of the detection unit is equal to that of the shaft portion 2d-
Although the examples provided on both sides of 1 and 2d-2 have been presented, only one side may be provided. Such an example is shown in FIG. 7 as another embodiment. In all of the above-mentioned embodiments, the piezoelectric element is provided at the symmetrical position, but the piezoelectric element may be provided on one side instead of the symmetrical position. The period piezoelectric element may be omitted if the AC voltage and frequency applied to the driving piezoelectric element can be controlled by another method.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a piezoelectric vibration gyro device that is an embodiment of the present invention.

FIG. 2 is a diagram showing a connection state with an electronic circuit section of the piezoelectric vibration gyro device which is an embodiment of the present invention.

FIG. 3 is a diagram for explaining the operation of the piezoelectric vibrating gyro device that is an embodiment of the present invention.

FIG. 4 is a diagram for explaining the operation of the piezoelectric vibrating gyro device that is an embodiment of the present invention.

FIG. 5A is a diagram showing the shape of a prismatic tuning fork type oscillator used for explaining the effect of the piezoelectric vibrating gyro device according to an embodiment of the present invention with respect to the conventional example. (A) It is a figure for demonstrating the effect with respect to the prior art example of the piezoelectric vibration gyro apparatus which is one Example of this invention.

FIG. 6A is a diagram showing the shape of a prismatic tuning fork type oscillator used for explaining the effect of the piezoelectric vibration gyro device according to the embodiment of the present invention over the conventional example. (A) It is a figure for demonstrating the effect with respect to the prior art example of the piezoelectric vibration gyro apparatus which is one Example of this invention.

FIG. 7A is a perspective view of a prismatic tuning fork type vibrator of a piezoelectric vibrating gyro device according to another embodiment of the present invention. (A) It is a perspective view of a prismatic tuning fork type vibrator of the piezoelectric vibration gyro device which is another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric vibration gyro device 2 Prism tuning-fork type vibrator 2a-1 Vibration part 2a-2 Vibration part 2c Neck part 2d-1 Shaft part 2d-2 Shaft part 2e-1 Side surface 2e-2 Side surface 2f-2 Side surface 2f-2 Side surface 2g -1 Upper surface 2g-2 Upper surface 3 Piezoelectric element for driving 4 Piezoelectric element for feedback 5 Piezoelectric element for detection 6 Base 7 Lead wire 8 Lead wire 9 Lead wire 10 Electronic circuit section

Front page continuation (72) Inventor Yoshinori Takeuchi 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd.

Claims (1)

[Claims] 1. A prismatic tuning-fork type vibrator comprising a vibrating portion which is an upper end of a tuning fork shape having a prismatic cross section, a shaft portion which is continuous with and integrated with the vibrating portion, and a neck portion which fixes the shaft portion to a base. And at least a driving piezoelectric element that is driven by an AC voltage attached to the shaft portion of the vibrator, and a detecting piezoelectric element that generates a signal based on strain generated by an angular velocity input from the outside. Further, the driving piezoelectric element and the detection piezoelectric element are provided in a positional relationship orthogonal to each other, and further, the width of the tuning fork shape surface of the prismatic tuning fork type vibrator to which the detection piezoelectric element is attached is both left and right. The piezoelectric vibrating gyro device is characterized in that the width is set to the left and right of the tuning fork-shaped surface of the prismatic tuning fork type vibrator provided with the driving piezoelectric element.