JPH07301535A - Frequency adjusting mechanism of vibrating element - Google Patents

Abstract

PURPOSE:To provide a frequency adjusting mechanism which can finely adjust the resonance frequency of a fine semiconductor vibrating element used for oscillatory gyros, etc. CONSTITUTION:Three vibration adjusting beams l of the resonance frequency adjusting mechanism of a semiconductor vibrating element 2 are provided on the vibrating 'beam 4 of the element 2 and fixed electrodes 3 for adjustment are arranged opposedly to the free ends of the beams 1 with very small clearances in between. A voltage applying means which applies voltages across the electrodes is connected to the electrodes 3. When a voltage is applied across, for example, one 3a of the electrodes 3, the beam la is attracted to the electrode 3a until it comes into contact with the electrode 3a. As a result, the fixed end of the vibrating element 3 moves to a point Q from a point O and the length of the element 2 apparently becomes shorter. Therefore, the resonance frequency of the element 2 becomes higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for adjusting the resonance frequency of a vibration element used in a vibration type gyro.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional example of a vibration sensor section of a vibration gyro. This vibration sensor unit is configured to have a fine semiconductor vibration element 2 manufactured on a silicon substrate by a micromachining technique. The semiconductor vibrating element 2 shown in FIG. 4 has a vibration detecting body 6, a comb-shaped movable electrode 5 and two vibrating beams 4, the movable electrode 5 is provided on the vibration detecting body 6, and the vibration detecting body 6 vibrates. It has a gate-shaped structure fixed via a beam 4. A comb-shaped fixed electrode 7 is arranged so as to mesh with the movable electrode 5.

When an AC voltage is applied to the movable electrode 5 and the fixed electrode 7, an electrostatic force is generated between the movable electrode 5 and the fixed electrode 7, and the electrostatic force causes the semiconductor vibrating element 2 to vibrate in the x-axis direction.

When the semiconductor vibrating element 2 is vibrated (excited vibration) in the x-axis direction as described above and rotated about the z-axis, a direction orthogonal to both the rotational axis direction and the excited vibration direction (in FIG. A Coriolis force is generated in the vertical y-axis direction, and this Coriolis force is applied to the semiconductor vibrating element 2, and the semiconductor vibrating element 2 vibrates (detection vibration) in the direction in which the Coriolis force is generated, resulting in excitation vibration and detection vibration. When vibrating at the matching resonance frequency, the semiconductor vibrating element 2 vibrates with the maximum amplitude. Electrodes (not shown) are formed on both front and back surfaces of the vibration detection body 6, and detection electrodes (not shown) are installed in opposition to the respective electrodes on the vibration detection body 6, The magnitude of the rotational angular velocity about the z-axis is detected by measuring the change in electrostatic capacitance corresponding to the magnitude of the detected vibration of the semiconductor vibrating element 2 due to the generation of the Coriolis force.

[0005]

However, in the fine semiconductor vibrating element 2 manufactured on the silicon substrate using the micromachining technique, all the semiconductor vibrating elements 2 are manufactured so as to vibrate at the maximum amplitude at the designed resonance frequency. Is impossible. Therefore, using the fact that the resonance frequency of the semiconductor resonator element 2 increases as the mass of the semiconductor resonator element 2 decreases, the semiconductor resonator element 2 having a resonance frequency lower than the designed resonance frequency is manufactured in advance in the conventional example. Then, the resonance frequency is adjusted to a higher direction by scraping off the scraping region of the semiconductor vibrating element 2 with laser light so that the designed frequency is obtained. However, when the amount of scraping by the laser light is larger than the target amount and the resonance frequency is adjusted to a higher resonance frequency than the designed resonance frequency, it is impossible to adjust the resonance frequency to the lower direction again. there were.

Further, since the spot diameter of the laser beam is large with respect to the scraped region of the fine semiconductor vibrating element 2, it is difficult to finely adjust the resonance frequency by scraping a minute portion of the scraped region with the laser beam. There was a problem.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a mechanism for adjusting the resonance frequency of the semiconductor vibrating element 2 which can be finely adjusted without scraping off the semiconductor vibrating element 2. To provide.

[0008]

In order to achieve the above object, the present invention is constructed as follows. That is, in the frequency adjusting mechanism of the vibrating element of the first aspect of the invention, one or more vibration adjusting beams are projected from different positions from the vibrating element, and the fixed electrode is provided on the free tip side of each vibration adjusting beam with a minute gap therebetween. Are arranged so as to face each other, and a voltage applying means to the fixed electrode for bringing the free tip side of the vibration adjusting beam into contact with this fixed electrode by electrostatic force is provided.

A frequency adjusting mechanism for a vibrating element according to a second aspect of the invention is characterized in that the vibrating element according to the first aspect is formed of a semiconductor vibrating element.

[0010]

In the above invention, when the resonance frequency of the vibration element is lower than the designed resonance frequency, a voltage is applied to the corresponding fixed electrode on the free tip side of one vibration adjusting beam. By applying this voltage, an electrostatic attractive force acts between the free tip side of the vibration adjusting beam and the fixed electrode, and the free tip side of the vibration adjusting beam is attracted to the fixed electrode and comes into contact therewith, whereby the resonance frequency of the vibrating element changes to a higher direction. . Further, when finely adjusting the resonance frequency of the vibrating element to increase, the voltage applied to the fixed electrode is increased and the electrostatic attraction is increased to increase the contact area between the free tip side of the vibration adjustment beam and the fixed electrode. The resonance frequency of the vibrating element is adjusted to be higher and the resonance frequency is designed to be slightly higher. Further, when the resonance frequency of the vibration element is slightly lowered, the contact area between the fixed tip and the free tip side of the vibration adjustment beam is reduced by weakening the electrostatic attraction, and the resonance frequency of the vibration element is slightly decreased. Match the resonance frequency designed in this way.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same reference numerals will be given to the same names as those in the conventional example, and detailed description thereof will be omitted.

FIG. 1 shows a semiconductor resonator element 2 according to the present invention.
The first embodiment of the frequency adjusting mechanism is shown together with the vibration sensor part of the vibration type gyro. 2 is a cross-sectional view showing the AA cross section of FIG. This vibration sensor unit
The semiconductor vibrating element 2 is configured to have a fine semiconductor vibration element 2 having the same configuration as that of the conventional example, and like the conventional example, the static vibration between the movable electrode (not shown) and the fixed electrode (not shown) of the semiconductor vibrating element 2 is performed. Excitation vibration in the x-axis direction is generated by the electric power, and when the z-axis is rotated, the detection vibration due to the Coriolis force occurs in the y-axis direction perpendicular to the paper surface in FIG. 1, which corresponds to the magnitude of the amplitude of the detection vibration. The change in electrostatic capacitance is measured, and the magnitude of the angular velocity of rotation around the z axis is measured. The frequency adjusting mechanism of the present embodiment has a vibration adjusting beam 1 for adjusting the resonance frequency of the semiconductor vibrating element 2. The vibration adjusting beam 1 is provided on the vibrating beam 4 so as to project laterally in the figure, and the vibration adjustment thereof is performed. An adjustment fixed electrode 3 is arranged opposite to the free tip side of the beam 1 with a minute gap 8 therebetween.

The vibration adjusting beam 1 includes a vibration adjusting beam 1a for adjusting the resonance frequency of the semiconductor vibrating element 2 in a slightly higher direction (for example, about 5%) and a direction higher than the vibration adjusting beam 1a (for example, 5%).
It has a vibration adjusting beam 1b for adjusting to about 10%) and a vibration adjusting beam 1c for adjusting to a higher direction (for example, about 15%), and is integrally formed with a semiconductor vibrating element 2 on a silicon substrate by using micromachining technology. Has been done. Further, fixed electrodes 3a, 3b, 3c for adjustment are fixedly arranged at positions facing the free front ends of the respective vibration adjusting beams 1a, 1b, 1c with a minute gap therebetween. Further, the fixed electrodes for adjustment 3a, 3
b, 3c is provided with a voltage applying means for applying a voltage, and the voltage applying means is provided for each of the adjustment fixed electrodes 3a, 3b,
3c is connected.

In the adjusting mechanism having the vibration adjusting beam 1 and the adjusting fixed electrode 3, when a positive voltage is applied to the adjusting fixed electrode 3, the free tip side of the adjusting beam 1 and the adjusting fixed electrode 3 are applied.
And an electrostatic attractive force is generated between the free end side of the vibration adjusting beam 1 and the fixed fixed electrode 3 by the electrostatic attractive force,
Contact is made by electrostatic attraction generated at a contact voltage or more, and if the voltage is further increased to increase the electrostatic attraction, the contact area increases, and if the voltage is lowered to decrease the electrostatic attraction, the contact area decreases.

By the way, the mass m of the semiconductor vibrating element 2
The resonance frequency of the semiconductor vibrating element 2 can be changed using the length L from the fixed end O of the semiconductor vibrating element 2 to the free leading edge P as a parameter. For example, when the mass m of the semiconductor vibrating element 2 is constant, when the length L of the semiconductor vibrating element 2 is shortened, the resonance frequency of the semiconductor vibrating element 2 is high, and when the length L is long, the resonance frequency is low. Therefore, the present inventor has paid attention to the length L of the semiconductor resonator element 2 and invented a mechanism for adjusting the resonance frequency of the semiconductor resonator element 2.

Next, a method of adjusting the resonance frequency using the frequency adjusting mechanism of the semiconductor resonator element 2 shown in FIG. 1 will be described.

First, wiring for driving the semiconductor vibrating element 2, wiring for measuring the resonance frequency of the semiconductor vibrating element 2, and fixing for adjustment through a distributor (not shown) from a power source (voltage applying means). Electrodes 3a, 3b, 3c
Wiring for selectively applying a voltage to any one of the above is provided and installed in the inspection adjustment apparatus.

Next, the frequency of the AC voltage for exciting the semiconductor vibrating element 2 is changed, and the resonant frequency at which the exciting vibration of the semiconductor vibrating element 2 resonates with the detected vibration and vibrates at the maximum amplitude is measured. To do. If the resonance frequency of the semiconductor resonator element 2 obtained by this measurement is lower than the designed resonance frequency, for example, if the error between the resonance frequency of the semiconductor resonator element 2 and the designed resonance frequency is about 5%, the semiconductor A contact voltage or more is applied to the corresponding adjustment fixed electrode 3a of the vibration adjustment beam 1a for adjusting the resonance frequency of the vibrating element 2 to a direction higher by about 5%, and the vibration adjustment beam 1a is electrically fixed to the adjustment fixed electrode 3a. Then, the resonance frequency is measured again.
Thus, by fixing the vibration adjusting beam 1a, the fixed end O of the semiconductor vibrating element 2 moves to the temporary fixed end Q, and apparently the length L of the semiconductor vibrating element 2 is actually shortened. As a result, the resonance frequency of the semiconductor vibrating element 2 increases.

Similarly, if the error between the resonance frequency of the semiconductor vibrating element 2 and the designed resonance frequency is about 10%, the vibration adjusting beam 1b is selected, and if the error is about 15%, the vibration adjusting beam 1c is selected.
Select and fix electrically, and measure again.

When the resonance frequency designed by the selected vibration adjustment beam 1 or a resonance frequency close to the designed resonance frequency is not obtained, the vibration adjustment beam 1 of one rank higher than that of the resonance adjustment beam 1 (for example, the vibration adjustment beam 1a is used) is adjusted. If the resonance frequency cannot be approximated to the designed resonance frequency, the above adjustment is repeated for the vibration adjustment beam 1b), an appropriate vibration adjustment beam 1 is selected, and the resonance frequency of the semiconductor resonator element 2 is roughly adjusted.

Further, after the rough adjustment as described above, the following fine adjustment is made to match the designed resonance frequency.

When the resonance frequency of the semiconductor vibrating element 2 is slightly low, the voltage applied to the fixed fixed electrode 3 for adjustment corresponding to the selected vibration adjusting beam 1 is increased to make the vibration adjusting beam 1 and the fixed electrode 3 for adjustment. By increasing the electrostatic attraction between them and increasing the contact area between the vibration adjusting beam 1 and the fixed electrode 3 for adjustment, the resonance frequency of the semiconductor vibrating element 2 is adjusted to a slightly higher direction. On the contrary, if the resonance frequency is slightly higher,
By lowering the voltage applied to the fixed electrode 3 for adjustment corresponding to the selected vibration adjusting beam 1 to weaken the electrostatic attraction and reduce the contact area, the resonance frequency of the semiconductor vibrating element 2 is slightly lowered. adjust. The fine adjustment by the contact area and the measurement of the resonance frequency of the semiconductor resonator element 2 are alternately repeated to match the designed resonance frequency with the resonance frequency of the semiconductor resonator element 2.

As described above, the voltage applied to the vibration adjusting beam 1 used in the two-step adjustment and the adjusting fixed electrode 3 corresponding to the vibration adjusting beam 1 is determined. When the vibration sensor having the frequency adjusting mechanism actually operates, the voltage determined above is supplied from the voltage applying means to only one adjusting fixed electrode 3 to be used.

In this embodiment, a frequency adjusting mechanism is provided in the semiconductor vibrating element 2 and one of the vibration adjusting beams 1 provided in the vibrating beam 4 is electrically fixed to adjust the resonance frequency of the semiconductor vibrating element 2. Since the configuration is performed, the vibration adjustment beam 1 to be used is selected according to the magnitude of the deviation with respect to the designed resonance frequency, and the voltage applied to the adjustment fixed electrode 3 is changed to easily set the resonance frequency to the design value. Can be adjusted to. Further, in the conventional example, the spot diameter of the laser light is large with respect to the shaving area, and it is difficult to finely adjust the resonance frequency for shaving a minute portion of the shaving area with the laser light. 1 and fixed electrode 3 for adjustment
By changing the contact area with the semiconductor vibrating element 2, the resonance frequency of the semiconductor vibrating element 2 can be finely adjusted (resonance frequency change rate 1 to 5%).

Further, the resonance frequency of the semiconductor vibrating element 2 is measured, and the voltage corresponding to the deviation between the measured value and the designed resonance frequency is applied to the adjustment fixed electrode 3 by the voltage applying means to adjust the resonance frequency. The feedback adjustment can be performed, and the adjustment accuracy of the resonance frequency becomes very good.

FIG. 3 shows a second embodiment of the frequency adjusting mechanism of the semiconductor vibrating element 2 together with the vibration sensor portion of the vibration type gyro. In the description of the second embodiment, the same names as those in the conventional example and the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

This vibration sensor section is constituted by including a fine semiconductor vibration element 2 having the same structure and function as those of the first embodiment. The second embodiment of the frequency adjusting mechanism of the semiconductor vibrating element 2 is characterized in that the right vibrating beam 4A and the left vibrating beam 4B are bridged beams in order to adjust the resonance frequency of the semiconductor vibrating element 2. Pass 9 and the bridge beam 9
That is, the vibration adjusting beam 1 is projected upward from the symmetrical center position in the drawing, and the adjusting fixed electrode 3 is arranged to face the vibration adjusting beam 1 with a minute gap therebetween. Similarly to the first embodiment, the vibration adjusting beam 1 and the bridging beam 9 also use the micromachining technique and the semiconductor vibrating element 2 is a silicon substrate.
It is integrally formed with.

In the second embodiment described above, as in the first embodiment, by adjusting the voltage applied to the adjustment fixed electrode 3,
The resonance frequency of the semiconductor resonator element 2 can be finely adjusted.

In the second embodiment, in addition to the effect similar to that of the first embodiment, the vibration adjusting beam 1 constituting the frequency adjusting mechanism is provided so as to project symmetrically with respect to the semiconductor vibrating element 2. Since the excited vibration of the semiconductor vibrating element 2 does not vary in the left-right direction, the left-right vibration balance is good, and the Q value (Quality factor value) of the semiconductor vibrating element 2 can be prevented from decreasing. Is a fixed electrode for adjustment 3
Even if the semiconductor vibrating element 2 is fixed to, the semiconductor vibrating element 2 can maintain its high sensitivity to the resonance frequency.

In each of the first and second embodiments, if the resonance frequency of the semiconductor resonator element 2 is preliminarily manufactured to be lower than the designed resonance frequency, the adjustment as in the first and second embodiments is performed. The resonance frequency of all the semiconductor vibrating elements 2 can be adjusted by the mechanism.

The present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted. For example, in the above embodiment, the semiconductor vibrating element 2 has a gate-shaped structure in which the vibration detecting body 6 is supported by the two vibrating beams 4, but one vibrating beam 4 is used.
A structure that supports the vibration detector 6 may be used.

In the above embodiment, the semiconductor vibrating element 2 is used.
Although it was a cantilever, it may be a cantilever.

Further, in the above embodiment, the movable electrode and the fixed electrode are provided, and the electrostatic vibration generated by applying the AC voltage to the electrodes is used to cause the vibration of the semiconductor vibration element 2 to be excited. Two piezoelectric elements having different polarization states are alternately laminated on the surface of 4, and the vibration of the vibrating beam 4 generated by applying a voltage to the piezoelectric elements is used to excite the vibration of the semiconductor vibrating element 2. , Also vibrating beam 4
The fixed end of 1 may be connected to a vibrating device so that the semiconductor vibrating element 2 is excited and vibrated.

Further, in the above embodiment, the vibration adjusting beam 1 was installed on the vibrating beam 4. However, as shown in FIG. 3, the vibration adjusting beam 1 shown by a dotted line is provided on the free tip side of the vibration detecting body 6. You may project in the upward direction of a figure.

Further, although the semiconductor vibrating element 2 having the frequency adjusting mechanism of the above-mentioned embodiment is used in the vibrating gyro, it can be applied to the adjustment of the resonance frequency of the resonator.

Furthermore, although the vibrating element of the above-described embodiment is formed of a semiconductor, it may be formed of an element other than a semiconductor.

[0037]

According to the present invention, when the resonance frequency of the vibrating element is lower than the designed resonance frequency, a voltage is applied to the fixed electrode on the free tip side of the vibration adjusting beam, and the voltage is applied to the fixed electrode. It is possible to adjust the resonance frequency of the vibrating element so as to match the resonance frequency designed in the higher direction by pulling the free tip end side of the contact electrode toward and contacting the fixed electrode. In particular, when the voltage applied to the fixed electrode is changed, the contact area of the vibration adjusting beam can be changed, and the resonance frequency of the vibration element can be finely adjusted.

[Brief description of drawings]

FIG. 1 shows a first frequency adjusting mechanism for a vibrating element according to the present invention.
FIG. 3 is an explanatory diagram showing the embodiment of FIG.

FIG. 2 is an explanatory view showing a cross section taken along the line AA of FIG.

FIG. 3 is an explanatory view showing a second embodiment of the frequency adjusting mechanism of the vibration element together with the vibration sensor unit.

FIG. 4 is an explanatory diagram showing a vibration sensor unit of a conventional example.

[Explanation of symbols]

 1 Vibration adjustment beam 2 Semiconductor vibration element 3 Fixed electrode for adjustment

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomohisa Hasegawa 2 26-10 Tenjin Tenjin, Nagaokakyo City, Kyoto Stock Company Murata Manufacturing Co., Ltd. (72) Inventor Katsuhiko Tanaka 2 26-10 Tenjin Tenjin, Nagaokakyo, Kyoto Murata Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. A vibrating element is provided with one or more vibration adjusting beams projecting from different positions, and fixed electrodes are arranged opposite to each other through a minute gap on the free tip side of each vibration adjusting beam. A frequency adjusting mechanism for a vibrating element, which is provided with a means for applying a voltage to a fixed electrode that brings the free tip side of the vibration adjusting beam into contact with the electrostatic force. 2. The frequency adjusting mechanism according to claim 1, wherein the vibrating element is a semiconductor vibrating element.