CN104897144A - Multi-drive electrode mode-coupled micro-solid mode gyroscope - Google Patents

Abstract

The invention discloses a multi-drive electrode mode-coupled micro-solid mode gyroscope which comprises a piezoelectric vibrator, multiple pairs of drive electrodes, reference electrodes, signal detection electrodes and isolating electrodes, wherein the drive electrodes, the reference electrodes, the signal detection electrodes and the isolating electrodes are located on the upper surface and the lower surface of the piezoelectric vibrator and form fixed connection with the piezoelectric vibrator. The vibration in a special mode of the piezoelectric vibrator is utilized as reference vibration; and meanwhile, the coriolis effect and the piezoelectric effect are used for sensing the external input angle velocity to detect an output signal. By introducing the multiple pairs of drive electrodes, the reference vibration velocity amplitude is increased and the detection sensitivity of the micro-gyroscope is improved; and the size of the piezoelectric vibrator is optimized so that the inherent frequencies in the reference mode and the detection mode are the same; the detection vibration amplitude is increased by employing the mode-coupling effect; the output sensitivity of the gyroscope is improved; and the detection sensitivity of the micro-solid mode gyroscope is greatly improved.

Description

Mode-Coupled Micro-Solid Mode Gyroscope with Multi-Drive Electrodes

technical field

The invention relates to a micro-gyroscope in the field of micro-electromechanical technology, in particular to a multi-drive electrode mode-coupled micro-solid mode gyroscope.

Background technique

The micro solid mode gyroscope uses piezoelectric materials as the driving and detection components, and is a new type of all-solid-state MEMS micro gyroscope. Different from general MEMS vibrating gyroscopes, micro solid mode gyroscopes have no support or moving parts, so they have the advantages of overload resistance, strong impact resistance, high operating resonance frequency, no need for vacuum packaging, and short start-up time. They are widely used in consumer electronics products. , aircraft navigation, intelligent shells and guidance and other fields have broad application prospects.

After searching the literature of the prior art, it was found that in January 2006, at the MEMS2006 conference held in Istanbul, Turkey, Japanese scholar K.Maenaka et al. published a paper entitled "New Micro-solid-state Gyroscope", which was included in the On pages 634 to 637, an all-solid-state micro-gyroscope based on the special vibration mode of the piezoelectric body is proposed for the first time. The researchers found that the square piezoelectric body-mass has a special vibration mode at a certain frequency. In this vibration mode, the piezoelectric body-mass is stretched or compressed in the same direction, and the corresponding The vibration directions of the two adjacent edges are opposite (when one is in tension, the other is in compression). The vibration in this special mode is used as the reference vibration, assuming that the polarization direction of the piezoelectric body is in the Z direction, and the reference vibration is in the X direction. When the external angular velocity is input in the Y direction, due to the Coriolis force, the piezoelectric body Induced vibrations are generated in the direction of polarization. Due to the piezoelectric effect of the piezoelectric body, the surface perpendicular to the Z direction will generate an induced charge or voltage, and its magnitude is proportional to the external input angular velocity. The external input angular velocity can be obtained by detecting the amplified charge or voltage of the peripheral circuit. size.

This technology has the following disadvantages: firstly, there are only a pair of driving electrodes on the upper and lower surfaces of the piezoelectric vibrator, the use efficiency of the surface is not high, and the distance between the driving electrodes is relatively large, and the electric field strength is small, resulting in a small reference vibration amplitude; secondly, the piezoelectric vibrator The resonance frequency of the vibration mode detected by the electric vibrator is not consistent with the frequency of the driving mode. When the piezoelectric body is driven by the reference vibration mode frequency, the detected vibration amplitude does not reach the maximum value, resulting in a decrease in the voltage amplitude at the detection electrode. Small, which affects the acquisition of high sensitivity of the micro gyroscope.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the prior art, to provide a micro-solid modal gyroscope with multi-drive electrode modal coupling, which uses the special vibration mode of the piezoelectric vibrator to work, and utilizes the Coriolis effect and the piezoelectricity of the piezoelectric material. The electric effect is detected; by introducing multiple pairs of driving electrodes on the upper and lower surfaces of the piezoelectric vibrator, the surface use efficiency is improved, the electric field strength is increased, and the reference vibration velocity amplitude is increased; in addition, by adjusting the size of the piezoelectric body, the detection The vibration mode is consistent with the natural frequency of the reference vibration mode, which can strengthen the induced vibration in the polarization direction and improve the sensitivity of the micro gyroscope.

The present invention is achieved through the following technical solutions:

The present invention provides a multi-drive electrode modal coupling micro-solid modal gyroscope, comprising: a piezoelectric vibrator, multiple pairs of drive electrodes, multiple reference electrodes, multiple signal detection electrodes and multiple isolation electrodes, drive electrodes, reference electrodes , the signal detection electrode and the isolation electrode are located on the upper and lower surfaces of the piezoelectric vibrator, and form a fixed connection with the piezoelectric vibrator;

There are four pairs of driving electrodes, two pairs of driving electrodes are evenly distributed at the center of the upper surface of the piezoelectric vibrator, and the other two pairs of driving electrodes are evenly distributed at the center of the lower surface of the piezoelectric vibrator; the driving electrodes are used to excite the piezoelectric vibrator. The electric vibrator generates the driving mode shape;

There are four reference electrodes, two of which are distributed in the middle of the upper surface of the piezoelectric vibrator near the two edges, and the other two reference electrodes are distributed in the middle of the lower surface of the piezoelectric vibrator near the two edges. position; the reference electrode is used to monitor whether the piezoelectric vibrator starts to vibrate normally under the excitation of the driving electrode, and track the working vibration mode, so that the piezoelectric vibrator works stably in the working vibration mode;

There are eight signal detection electrodes, four of which are distributed on the four corners of the upper surface of the piezoelectric vibrator, and the other four signal detection electrodes are distributed on the four corners of the lower surface of the piezoelectric vibrator; The detection electrode is used to detect the induced voltage generated in the polarization direction of the piezoelectric vibrator;

There are four isolation electrodes, two of which are located between the driving electrode on the upper surface of the piezoelectric vibrator and the reference electrode and the signal detection electrode, and the other two are located between the driving electrode on the lower surface of the piezoelectric vibrator and the reference electrode and the signal detection electrode. Between; the isolation electrode is used to isolate the impact of the driving voltage on the output voltage or charge of the signal detection electrode and the reference electrode.

Preferably, when an alternating voltage is applied to the driving electrode at a selected resonance frequency, the piezoelectric vibrator has a certain order of special vibration mode under the excitation of the alternating voltage, and the piezoelectric vibrator in this mode Each point basically moves in the same direction at the same frequency, and the vibration directions on the two adjacent sides are opposite (when one is stretched, the other is compressed), and the vibration directions on the two opposite sides are exactly the same (same as For stretching or compression), the special vibration at this frequency is used as the reference vibration, and the polarization direction of the piezoelectric vibrator is perpendicular to the reference vibration direction of the piezoelectric vibrator.

Preferably, when there is an angular velocity input perpendicular to the reference vibration direction, under the action of the Coriolis force, the piezoelectric vibrator will induce a detection vibration in the polarization direction, and its amplitude is proportional to the magnitude of the external input angular velocity. Using the reference mode The coupling between the detection mode and the detection mode makes the detection vibration amplitude reach the maximum value at this frequency, and the polarity change and variation of the piezoelectric voltage on the electrode are detected by the detection signal, that is, the magnitude of the external input angular velocity is obtained.

Preferably, the piezoelectric vibrator has a cuboid structure and is made of piezoelectric ceramics or other piezoelectric materials.

Preferably, the length, width and height of the piezoelectric vibrator are selected such that the reference vibration mode frequency is the same as the detection vibration mode frequency.

Preferably, when the driving electrodes work, it is ensured that the voltages applied to adjacent driving electrodes on the same surface of the piezoelectric vibrator have the same frequency and amplitude, but opposite polarities.

Preferably, the material of the driving electrode, the reference electrode, the signal detection electrode, and the isolation electrode are all metal, and the structures are all rectangular.

Compared with the prior art, the present invention has the following beneficial effects:

The invention provides a micro-solid modal gyroscope with multi-drive electrode modal coupling. Multiple pairs of drive electrodes are introduced on the upper and lower surfaces of the piezoelectric vibrator, which can not only improve the surface use efficiency, but also increase the electric field intensity, thereby increasing the reference vibration Velocity amplitude; the reselection of the size of the micro-gyroscope ensures the consistency of the natural frequency of the reference mode and the detection mode, and the mutual coupling between the reference mode and the detection mode is used to increase the detection vibration amplitude. The invention optimizes the size of the micro-gyroscope, and finally improves the output sensitivity and performance of the micro-gyroscope.

Description of drawings

Fig. 1, 2 is the general structural representation of the present invention;

Fig. 3 is the driving mode of the present invention, the simulation schematic diagram of detection mode vibration shape respectively, wherein (a) is the simulation schematic diagram of driving mode vibration shape, 3 (b) is the simulation schematic diagram of detection mode vibration shape;

Fig. 4 is a coupling curve diagram of the driving mode and the detection mode of the present invention at five heights of different sizes;

In the figure: piezoelectric vibrator 1, drive electrodes 6, 7, 8, 9, 18, 19, 20, 21, reference electrodes 3, 12, 15, 24, signal detection electrodes 2, 4, 11, 13, 14, 16 , 23,25 and isolated electrodes 5,10,17,22.

Detailed ways

The embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. This embodiment is based on the technical solution of the present invention, and provides detailed implementation methods and specific operating procedures, but the scope of protection of the present invention is not limited to the following embodiments. .

As shown in Figures 1 and 2, this embodiment provides a micro-solid modal gyroscope with multi-drive electrode modal coupling, including a piezoelectric vibrator 1, drive electrodes 6, 7, 8, 9, 18, 19, 20, 21 , reference electrodes 3, 12, 15, 24, signal detection electrodes 2, 4, 11, 13, 14, 16, 23, 25 and isolation electrodes 5, 10, 17, 22.

In this embodiment, the piezoelectric vibrator 1 has a cuboid structure, and the material is piezoelectric ceramics or other piezoelectric materials. The length, width and height dimensions are selected so that the reference vibration modal frequency is the same as the detection vibration modal frequency, as shown in Figure 4 As shown in the coupling curve, its polarization direction is along the Z axis.

In this embodiment, the driving electrodes 6, 7, 8, 9, 18, 19, 20, and 21 are made of metal and have a rectangular structure, wherein: the driving electrodes 6, 7, 8, and 9 are evenly distributed on the piezoelectric vibrator 1 At the center of the upper surface, the drive electrodes 18, 19, 20, 21 at the center of the lower surface of the piezoelectric vibrator 1 are used to excite the piezoelectric vibrator 1 to generate the driving mode shape; during operation, on the same surface of the piezoelectric vibrator 1 Apply equal-amplitude, opposite-phase driving mode frequency alternating voltages on adjacent driving electrodes (such as the polarities of the voltages on the driving electrodes 6 and 7 are opposite, but the polarities on the driving electrodes 6 and 8 are the same), and the driving electrodes on the lower surface The situation is similar to the above surface.

In this embodiment, the material of the reference electrodes 3, 12, 15, and 24 is metal, and the structure is rectangular, wherein: the reference electrodes 3, 12 are distributed in the middle of the upper surface of the piezoelectric vibrator near the two edges. The electrodes 15 and 24 are distributed in the middle of the lower surface of the piezoelectric vibrator 1 near the two edges, and are used to monitor whether the piezoelectric vibrator 1 vibrates normally under the excitation of the driving electrodes, and to track the working vibration mode, so that the piezoelectric vibrator The vibrator 1 works stably in the working vibration mode.

In this embodiment, the signal detection electrodes 2, 4, 11, 13, 14, 16, 23, and 25 are made of metal and have a rectangular structure, wherein: the signal detection electrodes 2, 4, 11, and 13 are distributed on the piezoelectric vibrator On the four corners of the upper surface of the piezoelectric vibrator 1 , signal detection electrodes 14 , 16 , 23 , and 25 are distributed on the four corners of the lower surface of the piezoelectric vibrator 1 for detecting the induced voltage generated in the polarization direction of the piezoelectric vibrator 1 .

In this embodiment, the isolation electrodes 5, 10, 17, and 22 are made of metal and have a rectangular structure, and are respectively located between the drive electrode, the reference electrode, and the signal detection electrode, and are used to isolate the influence of the excitation voltage on the output voltage and reduce the impact of the excitation voltage on the output voltage. The effect of small common-mode signals.

In this embodiment, all electrodes (including drive electrodes 6, 7, 8, 9, 18, 19, 20, 21, reference electrodes 3, 12, 15, 24, signal detection electrodes 2, 4, 11, 13, 14, 16 , 23 , 25 and isolation electrodes 5 , 10 , 17 , 22 ), are all manufactured on the upper and lower surfaces of the piezoelectric vibrator 1 through MEMS technology, using double-sided photolithography and electroplating technology.

As shown in FIG. 2 , the structure of the piezoelectric vibrator 1 in this embodiment is a cuboid, L represents its length, W represents its width, H represents its height, and the direction of the height is its polarization direction. Since the micro-solid-state modal gyroscope utilizes the coupling effect between the reference mode and the detection mode when it works, the selection of the length, width and height of the piezoelectric vibrator 1 needs to satisfy a certain relationship. In this embodiment, the variation range of the length L of the piezoelectric vibrator 1 is 4.8mm to 5.6mm, the variation range of the width W is 3mm to 4mm, and five different sizes are selected for the height H, which are 2.8mm, 2.9mm, and 3.0mm respectively. mm, 3.1mm and 3.2mm. The research found that when the thickness is constant, the increase of the length or the increase of the width will cause the decrease of the driving modal frequency, but the influence of the width on the driving modal frequency is more significant; the detection modal frequency will decrease with the increase of the length. Unlike the drive modal frequency, the detection modal frequency is more sensitive to changes in length.

As shown in FIG. 3 , it is a schematic diagram of the simulation of the vibration mode and the detection mode shape of the piezoelectric vibrator 1 obtained through finite element analysis. Apply an alternating voltage signal of selected frequency on the driving electrodes 6, 7, 8, 9, 18, 19, 20, 21, wherein the voltage polarity on 6, 7 is opposite, but the voltage on 6, 8, 19, 21 With the same polarity, the piezoelectric vibrator 1 produces a special reference vibration mode due to the inverse piezoelectric effect, as shown in Figure 3(a). In this vibration mode, each point of the piezoelectric vibrator 1 basically moves in tension or compression along the Y direction, the vibration direction of two adjacent edges is opposite, and the vibration direction of the two opposite sides is the same. The force is the largest in the middle near the edge, and the displacement on the four corners is the largest. This is the reason for the distribution design of the reference electrode and the signal detection electrode. When there is an angular velocity input in the X direction, since a pair of signal detection electrodes 2 and 4 on the Y axis move in opposite directions along the X axis, they will receive an opposite Coriolis force, but the direction is along the Z direction of the polarization direction, that is, the signal detection The detection vibration directions of the electrodes 2 and 4 are opposite, resulting in opposite changes in the output signals on the signal detection electrodes 2 and 4, wherein the amplitude of the output signal is related to the magnitude of the input angular velocity. The magnitude of the Y-axis input angular velocity can be obtained by subtracting the output signal amplitudes of a pair of signal detection electrodes 2 and 4 on the Y-axis. As shown in Figure 3(b), when there is an external angular velocity input, the detection vibration mode induced by the polarization direction, the detection vibration frequency is the same as the reference vibration frequency.

As shown in FIG. 4 , it is a coupling curve diagram of the driving mode and the detection mode at five heights of different sizes according to the present invention. When the piezoelectric vibrator 1 is excited at the driving resonance frequency, under the joint action of the Coriolis effect and the piezoelectric effect, the detection vibration of the same frequency is induced in the polarization direction. If the natural frequency of the driving mode and the detection mode are the same, that is, the driving mode When the mode and the detection mode are coupled with each other, the amplitude of the detection vibration will reach the maximum value at this frequency, thereby increasing the change of the output signal at the signal detection electrodes 2 and 4, which is beneficial to the improvement of sensitivity. In Figure 4, each point on the curve represents a set of indications of length, width and height under the condition of modal coupling, and each curve corresponds to a height of the piezoelectric vibrator 1, and the heights from left to right are 2.8 mm and 2.9 mm respectively. mm, 3.0mm, 3.1mm and 3.2mm. It can be seen from Figure 4 that as the height H of the piezoelectric vibrator 1 increases, the curve becomes steeper and steeper, that is, as the height increases, the modal coupling curve becomes more and more sensitive to the width change. According to the size on the curve To optimize the size of the micro solid-state modal gyroscope, the reference mode is the same as the detection mode.

By selecting 3 points from each curve in Figure 4, 15 piezoelectric vibrators of different sizes can be obtained. Through finite element analysis, the corresponding reference mode and detection mode resonance frequency under different sizes are obtained, and then an angular velocity of 1rad/s is applied in the X-axis direction to measure its scale factor. The detailed parameters are shown in the table below. The natural frequencies of the reference mode and the detection mode of the 15 points are basically the same, which meets the requirements of modal coupling. It can be seen that when the length L remains constant, the larger the thickness H is, the larger the scale factor will be; when the thickness H is constant, the scale factor will decrease with the increase of the length L.

The following table shows the specific parameters of some points on the curve in Figure 4, including the size of the piezoelectric vibrator, the modal coupling frequency, and the corresponding sensitivity:

As a preferred embodiment, the multi-drive electrode modal coupling micro-solid modal gyroscope uses a piezoelectric ceramic substrate, adopts a double-sided alignment process, and first sputters a layer of seed layer on the substrate; then spin-coats photoresist, Use the prepared mask to perform photolithography; then develop and pattern; then electroplate metal electrodes to form drive electrodes, reference electrodes, signal detection electrodes, and isolation electrodes; finally connect peripheral circuits and package to obtain finished products.

The invention uses the vibration in the special mode of the piezoelectric vibrator as the reference vibration, and uses the Coriolis effect and the piezoelectric effect to sense the external input angular velocity to detect the output signal. The present invention increases the amplitude of the reference vibration velocity by introducing multiple pairs of driving electrodes, improves the detection sensitivity of the micro-gyroscope; optimizes the size of the piezoelectric vibrator so that the natural frequencies of the reference mode and the detection mode are the same, and utilizes the mode coupling effect Increase the detection vibration amplitude and improve the output sensitivity of the gyroscope. The invention greatly improves the detection sensitivity of the micro solid mode gyroscope by adopting multiple driving electrodes and the coupling effect of the driving detection mode.

The above descriptions are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions under the idea of the present invention belong to the protection category of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the premise of the present invention should also be regarded as the protection scope of the present invention.

Claims (7)

1. A multi-drive electrode modal coupling micro-solid modal gyroscope is characterized in that, comprising: a piezoelectric vibrator, many pairs of drive electrodes, a plurality of reference electrodes, a plurality of signal detection electrodes and a plurality of isolation electrodes, and the drive electrodes , the reference electrode, the signal detection electrode, and the isolation electrode are located on the upper and lower surfaces of the piezoelectric vibrator, and form a fixed connection with the piezoelectric vibrator; There are four pairs of driving electrodes, two pairs of driving electrodes are evenly distributed at the center of the upper surface of the piezoelectric vibrator, and the other two pairs of driving electrodes are evenly distributed at the center of the lower surface of the piezoelectric vibrator; the driving electrodes are used to excite the piezoelectric vibrator. The electric vibrator generates the driving mode shape; There are four reference electrodes, two of which are distributed in the middle of the upper surface of the piezoelectric vibrator near the two edges, and the other two reference electrodes are distributed in the middle of the lower surface of the piezoelectric vibrator near the two edges. position; the reference electrode is used to monitor whether the piezoelectric vibrator starts to vibrate normally under the excitation of the driving electrode, and track the working vibration mode, so that the piezoelectric vibrator works stably in the working vibration mode; There are eight signal detection electrodes, four of which are distributed on the four corners of the upper surface of the piezoelectric vibrator, and the other four signal detection electrodes are distributed on the four corners of the lower surface of the piezoelectric vibrator; The detection electrode is used to detect the induced voltage generated in the polarization direction of the piezoelectric vibrator; There are four isolation electrodes, two of which are located between the driving electrode on the upper surface of the piezoelectric vibrator and the reference electrode and the signal detection electrode, and the other two are located between the driving electrode on the lower surface of the piezoelectric vibrator and the reference electrode and the signal detection electrode. Between; the isolation electrode is used to isolate the impact of the driving voltage on the output voltage or charge of the signal detection electrode and the reference electrode. 2. A multi-drive electrode modal coupling micro-solid modal gyroscope according to claim 1, wherein when an alternating voltage is applied on the drive electrodes with a selected resonant frequency, the piezoelectric Under the excitation of alternating voltage, the vibrator has a certain order of special vibration mode. In this mode, each point of the piezoelectric vibrator basically moves in the same direction at the same frequency, and the vibration directions on the two adjacent sides are opposite. The vibration directions on the two sides are exactly the same, and the special vibration at this frequency is used as the reference vibration, and the polarization direction of the piezoelectric vibrator is perpendicular to the reference vibration direction of the piezoelectric vibrator. 3. A kind of multi-drive electrode mode coupling micro-solid mode gyroscope according to claim 2, it is characterized in that, when there is an angular velocity input perpendicular to the reference vibration direction, the piezoelectric vibrator is under the effect of Coriolis force , the polarization direction will induce the detection vibration, and its amplitude is proportional to the external input angular velocity. Using the coupling of the reference mode and the detection mode makes the detection vibration amplitude reach the maximum value at this frequency. The polarity change and variation of the piezoelectric voltage, that is, the magnitude of the external input angular velocity. 4. A multi-drive electrode modal coupling micro-solid modal gyroscope according to any one of claims 1-3, wherein the piezoelectric vibrator is a cuboid structure, and the material is piezoelectric ceramics or other piezoelectric Material. 5. A multi-drive electrode mode-coupled micro-solid modal gyroscope according to any one of claims 1-3, characterized in that the length, width and height of the piezoelectric vibrator are selected such that the reference vibration modal frequency Same as detecting vibration modal frequencies. 6. A multi-drive electrode mode-coupled micro-solid modal gyroscope according to any one of claims 1-3, characterized in that, when the drive electrodes are in operation, they are guaranteed to be applied adjacently on the same surface of the piezoelectric vibrator. The voltages across the electrodes have the same frequency, amplitude, but opposite polarity. 7. A multi-drive electrode modal coupling micro-solid modal gyroscope according to any one of claims 1-3, wherein the drive electrodes, the reference electrodes, the signal detection electrodes, the The materials of the isolation electrodes are all metal, and the structures are all rectangular.