JP2008267983A - Piezoelectric vibrating gyroscope and its adjusting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small piezoelectric vibrating gyroscope of high reliability and its adjusting method that can make balance adjustment and output stability adjustment to null voltage or disturbance without degrading reliability of mechanical strength. <P>SOLUTION: The vibrating gyroscope has a driving means for vibrating in one direction a vibrator partially or entirely composed of a piezoelectric element, and a means for detecting the amplitude of vibration in the other direction perpendicular to the one direction. Reference electrodes 2, 4 and a detecting electrode 3 are provided almost parallel on the surface of a vibrator body 1, and then electrode eliminating parts 7, 8, 9 are formed to eliminate part of the electrodes, thus making direction adjustment of driving vibration. At this time, part of the electrodes is eliminated so that output obtained from the detecting electrode 3 takes a requested value in a state of not applying angular velocity in driving vibration. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vibration gyro for detecting an angular velocity and an adjustment method thereof, and more particularly to a vibrator for a piezoelectric vibration gyro suitable for an automobile navigation system, attitude control, a camera shake correction device for a camera-integrated VTR, and the adjustment method thereof. .

  A vibrating gyroscope is an angular velocity sensor that utilizes a dynamic phenomenon in which when an angular velocity is applied to an object having velocity, the object itself generates a Coriolis force in a direction perpendicular to the velocity direction. The vibration gyro is an electrical signal that excites mechanical vibrations to drive vibrations, and mechanical vibrations having a component orthogonal to the drive vibrations caused by the Coriolis force are detected vibrations, and the magnitude is electrically It is a sensor to detect automatically. This vibration gyroscope generates excitation vibration by Coriolis force when it is given an angular velocity of rotation around an axis parallel to the intersection line of the drive vibration surface and the detection vibration surface in a state where the drive vibration is excited in advance. And detected as an output voltage. Since the output voltage is proportional to the magnitude and angular velocity of the driving vibration, the magnitude of the angular velocity can be obtained from the magnitude of the output voltage in a state where the magnitude of the driving vibration is constant.

  In recent years, with the miniaturization of equipment, there is an increasing need for miniaturization of piezoelectric vibration gyros. In order to realize miniaturization of piezoelectric vibration gyroscopes, vibrators for piezoelectric vibration gyroscopes were conventionally manufactured by cutting, but in recent years, vibrators have been manufactured by microfabrication using photolithography technology. I came. However, due to the growing needs for miniaturization, design that emphasizes miniaturization that cannot be compensated for by the recent improvement in machining accuracy has been made, and as a result, further ingenuity is required in the adjustment process performed after the machining process. It has become.

  There are two types of adjustments for adjusting the vibrator for piezoelectric vibration gyro. The other adjusts the sensitivity and responsiveness of the piezoelectric vibration gyro, and the other adjusts the output stability against null voltage and disturbance. The former adjusts the difference between the resonance frequency of the drive vibration of the vibrator and the resonance frequency of the detection vibration, and is generally called detuning. On the other hand, the latter is an adjustment for aligning the levels of detection signals obtained from the two detection electrodes, and is generally called balance adjustment. In order to stabilize the output against disturbances such as temperature changes and vibrations, the piezoelectric vibration gyro detects the detection vibration with two detection electrodes, and differentially amplifies the detection signal obtained from each detection electrode to output the output signal. The configuration is taken.

  In general terms, detuning is related to the vibration amplitude of the vibrator, and balance adjustment is related to the vibration direction of the vibrator.

  For the additional work performed by these detuning and balance adjustment, a rotary grindstone called a reuter, a laser, and the like have been used for some time. For example, Patent Document 1 discloses a technique for adjusting the balance by grinding the end face of the vibrator main body with a router or drilling with a laser. This adjustment method is known to be able to perform adjustment with a wide adjustment range and high accuracy because the vibrator main body having the greatest influence on the resonance frequency and vibration characteristics of the vibrator is modified.

  However, the adjustment method that is additionally performed on the vibrator main body causes more or less micro cracks in the vibrator main body and deteriorates the mechanical strength. In particular, the smaller the vibrator, the greater the effect. When the vibration part of the vibrator is small and less than 100 μm, the adjustment method additionally processed in the vibrator body can ensure the reliability of the mechanical strength. There was a problem that it was extremely difficult.

  Among the adjustment methods, there is a method of removing or attaching the electrodes of the vibrator. For example, Patent Document 2 discloses a technique for adjusting a resonance frequency by generating an ion beam and removing an Au electrode or attaching metal ions. This adjustment principle is to adjust the resonance frequency by changing the mass of the vibrator. If an ion beam or a laser is used under appropriate conditions, it can be adjusted without generating microcracks in the vibrator body. That is, it can be said that even a small vibrator is an adjustment method in which it is easy to ensure reliability of mechanical strength. However, there is a problem that the adjustment range is narrow because the mass of the electrode or the like is minute relative to the vibrator body. In particular, it is difficult to use for balance adjustment that requires a great change in the vibration direction of the vibrator.

  For adjustment using a laser, there are Patent Document 3 which is a technique for creating a stray capacitance by electrode removal and detuning and Patent Document 4 which is a technique for removing a part of the monitor electrode and controlling a self-excited oscillation signal. In either case, adjustment control of the vibration direction cannot be performed, and it is difficult to perform balance adjustment, that is, adjustment of output stability against null voltage or disturbance.

JP-A-6-289043 JP-A-8-114460 JP 2006-17469 A JP 2006-105659 A

  The present invention makes it possible to adjust the balance, that is, to adjust the output stability against a null voltage or a disturbance without deteriorating the reliability of the mechanical strength. It is to provide.

  The present invention employs the following means in order to solve the above problems.

  First, in a vibrating gyroscope having driving means for vibrating a vibrator partially or entirely made of a piezoelectric material in one direction and means for detecting the amplitude of vibration in the other direction perpendicular to the one direction. Forming a plurality of strip electrodes substantially parallel to the surface of the piezoelectric body, using at least one of the strip electrodes as a detection electrode for detecting the amplitude of vibration in the other direction, and at least one of the strip electrodes Is a vibrating gyroscope partly removed for output balance adjustment.

  Furthermore, a part of at least one of the strip electrodes is removed so that the output obtained from the detection electrode takes a desired value while driving the vibration in one direction and applying no angular velocity. It is possible to use a vibration gyro adjustment method characterized by this.

  Furthermore, a vibration gyro adjustment method is used, wherein a part of at least one of the plurality of strip electrodes is removed so as to change a relative position of the detection electrode with respect to the plurality of strip electrodes. be able to.

  As described above, according to the present invention, the mechanical strength is not deteriorated even for a small vibrator, and balance adjustment, that is, adjustment of output stability against a null voltage or a disturbance can be performed, and the small vibrator is reliable. A high-performance piezoelectric vibration gyro can be obtained.

  FIG. 1 shows a part of a general piezoelectric vibration gyro vibrator. FIG. 1A is a perspective view thereof, and FIG. 1B is a sectional view thereof. In order to avoid overlapping with other displays, hatching is omitted. The principle of the piezoelectric vibration gyro will be described with reference to FIG. The rectangular parallelepiped vibrator body 1 is made of a piezoelectric material, for example, a single crystal material such as quartz or lithium niobate, or a piezoelectric material is formed on a polycrystalline material such as lead zirconate titanate or silicon. It may be a composite material.

  Band-shaped electrodes 2, 3, 4 are formed substantially parallel on the surface of the vibrator body 1, the electrodes 2, 4 are used as reference electrodes, and the electrode 3 is used as a detection electrode. In FIG. 1B, the white arrow P indicates the direction of polarization. Although not shown in the figure, the drive means functions as a piezoelectric vibration gyro vibrator if it is driven and vibrated in a bending vibration mode in the black arrow (double arrow) direction in advance and can detect a bending vibration in a direction perpendicular to the driving vibration. When the distance between the electrode 2 and the electrode 3 is extended by the drive vibration and the bending vibration in the vertical direction, the distance between the electrode 3 and the electrode 4 is contracted, so that the electric field generated by the piezoelectric effect is reversed between the electrodes in parallel with the polarization direction. appear. Therefore, if the electrodes 2 and 4 are used as the reference electrodes, when the drive vibration and the bending vibration in the direction perpendicular to the detection electrode 3 are generated, a charge corresponding to the vibration amplitude is generated. Functions as a vibrator for a piezoelectric vibration gyro. For driving vibration, when the electrode 2 and the electrode 3 are extended, the electrode 3 and the electrode 4 are also extended. Therefore, the electric field generated by the piezoelectric effect is in the same direction between the electrodes in parallel with the polarization direction. appear. Therefore, if the electrodes 2 and 4 are used as reference electrodes, the generated electric field is canceled and no charge is generated in the detection electrode 3. That is, the detection electrode 3 generates a charge only when bending vibration in the direction perpendicular to the drive vibration occurs.

  However, as shown in FIG. 2 (FIG. 2A is a perspective view thereof, and FIG. 2B is a cross-sectional view thereof). The symmetry of the outer shape is lost, and the drive vibration cannot be vibrated straight with respect to the detection electrode as shown by the arrow, and vibrates obliquely. Thus, when the drive vibration vibrates obliquely with respect to the detection electrode, that is, when a vertical bending vibration component is included, charge is generated without applying an angular velocity from the detection electrode, and generation of a null voltage or The output stability against disturbance will be impaired.

  In order to improve this phenomenon, as shown in FIG. 3 (FIG. 3 (a) is a perspective view and FIG. 3 (b) is a cross-sectional view), in order to cancel the processing error part 5 by the grinding part 6, as shown in FIG. Trimming adjustment was made to the part by cutting or the like to drive the drive vibration straight to the detection electrode. However, in a small vibrator, there has been a problem related to the mechanical properties of the piezoelectric body in the cutting of the vibrator body 1.

  On the other hand, the present invention removes a part of the belt-like electrode by trimming in order to control the direction of driving vibration with respect to the detection electrode without performing cutting that leads to the generation of microcracks. This will be described with reference to the drawings.

  (Embodiment 1) FIG. 4 shows a method for adjusting a vibrating gyroscope according to Embodiment 1, FIG. 4 (a) is a perspective view thereof, FIG. 4 (b) is a sectional view thereof, and FIGS. Is an electrode removal part.

  In the present embodiment, as shown in FIG. 4, the ends in the width direction of the electrodes 2, 3, 4 are removed with a laser, the center positions (center of gravity positions) of the electrodes 2, 3, 4 are shifted, and processing errors occur. It is made to vibrate relatively straightly with respect to the drive vibration that is inclined by the portion 5. Specifically, the amount of charge generated in the detection electrode in a state where the drive vibration is performed in advance is monitored, and a trimming unit (electrode removal unit) that is an end of the electrodes 2, 3, and 4 until the generated charge becomes zero. This can be realized by removing 7, 8, and 9 with a laser. Since the output stability against disturbance increases as the null voltage is closer to 0, the output stability can be adjusted and the balance can be adjusted by adjusting the null voltage.

  (Embodiment 2) FIG. 5 is a perspective view showing a method for adjusting a vibrating gyroscope according to Embodiment 2, and 11, 12 and 13 are electrode removal portions.

  Even if the trimming part is not all but part of the longitudinal direction of the vibrator as in the electrode removing parts 11, 12, and 13 shown in FIG. 5, the same effect as in the first embodiment can be produced.

  (Embodiment 3) FIG. 6 is a perspective view showing a method for adjusting a vibrating gyroscope according to Embodiment 3, and 13 is an electrode removing portion.

    Even if the removal is performed on only one electrode among the plurality of electrodes as in the trimming portion (electrode removing portion) 13 in FIG. 6, the same effect as in the first and second embodiments can be produced.

  (Embodiment 4) FIG. 7 is a perspective view showing a method for adjusting a vibrating gyroscope according to Embodiment 4, and 14 is an electrode removing portion.

  The same effects as those of the first to third embodiments can be obtained by removing the end of only one electrode among the plurality of electrodes as in the trimming unit (electrode removing unit) 14 of FIG. .

  (Embodiment 5) FIG. 8 is a perspective view showing a method for adjusting a vibrating gyroscope according to Embodiment 5, and 15 is an electrode removing portion.

  In FIG. 8, the same effect as that of the fourth embodiment can be obtained by removing a part of the electrode removing unit 14 of FIG. .

  It supplements about the adjustment method in those embodiment. Depending on the bending direction of the vibration direction with respect to the detection electrode, it is necessary to remove the electrodes having various shapes as described above. In general, when a part of the detection electrode is removed, the detection efficiency is lowered. Further, the reduction is greater when the longitudinal direction is removed than when the width direction of the strip electrode is removed. In that respect, the adjustment method of FIG. 5 is a method that can be adjusted without substantially reducing the detection efficiency. However, considering the laser irradiation tact in the adjustment process and damage to the vibrator due to laser irradiation, it is preferable that the removal range is as small as possible. Therefore, the adjustment method in FIG. 8 can be said to be superior in terms of productivity and reliability.

  When the adjustment amount is small, the reliability is emphasized by the adjustment method of FIG. 5, and when a large adjustment amount is necessary, the adjustment method of FIG.

  Since the present invention is adjusted by controlling the piezoelectric efficiency and is not mass controlled, the electrode does not need to be formed thicker than necessary, and the reliability of conduction can be ensured, for example, about 0.3 μm. There is no loss of productivity such as costs. Further, since the laser used for the adjustment may be such that the electrode can be removed, a relatively inexpensive one that does not require a large power can be used.

FIG. 1A is a perspective view and FIG. 1B is a sectional view of a part of a general piezoelectric vibration gyro vibrator. FIG. 2A is a perspective view and FIG. 2B is a cross-sectional view of a vibrator in which the symmetry of the outer shape is lost due to a processing error. 3A and 3B show a conventional method for adjusting a vibration gyro, FIG. 3A is a perspective view thereof, and FIG. 3B is a cross-sectional view thereof. FIGS. 4A and 4B show a method for adjusting a vibrating gyroscope according to the first embodiment, FIG. FIG. 6 is a perspective view showing a method for adjusting a vibration gyro according to a second embodiment. FIG. 10 is a perspective view showing a method for adjusting a vibration gyro according to a third embodiment. FIG. 10 is a perspective view showing a method for adjusting a vibration gyro according to a fourth embodiment. FIG. 10 is a perspective view illustrating a method for adjusting a vibration gyro according to a fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibrator body 2, 3, 4 Electrode 5 Processing error part 6 Grinding part 7-15 Electrode removal part

Claims (3)

  In the vibrating gyroscope, comprising: a driving unit that vibrates a vibrator partially or wholly composed of a piezoelectric body in one direction; and a unit that detects amplitude of vibration in another direction perpendicular to the one direction. A plurality of strip electrodes are formed substantially parallel to the surface of the substrate, and at least one of the strip electrodes is used as a detection electrode for detecting the amplitude of vibration in the other direction, and at least one of the strip electrodes is a balance of output. A vibrating gyroscope that has been partially removed for adjustment.   Drive means for vibrating a vibrator partially or entirely made of a piezoelectric material in one direction, and means for detecting amplitude of vibration in another direction perpendicular to the one direction, the surface of the piezoelectric material being In the method for adjusting a vibration gyro, wherein a plurality of strip electrodes are formed substantially in parallel, and at least one of the strip electrodes is used as a detection electrode for detecting the amplitude of vibration in the other direction, the vibration in one direction is driven. The vibration gyro is characterized in that at least one of the strip electrodes is removed so that the output obtained from the detection electrode takes a desired value when no angular velocity is applied. Method.   The vibration gyro adjustment according to claim 2, wherein a part of at least one of the plurality of strip electrodes is removed so as to change a relative position of the detection electrode with respect to the plurality of strip electrodes. Method.

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