WO2021134678A1

WO2021134678A1 - Mems gyroscope

Info

Publication number: WO2021134678A1
Application number: PCT/CN2019/130915
Authority: WO
Inventors: 占瞻; 马昭; 李杨; 张睿; 刘雨微; 谭秋喻; 黎家健
Original assignee: 瑞声声学科技(深圳)有限公司; 瑞声科技（南京）有限公司
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2021-07-08

Abstract

Disclosed is an MEMS gyroscope (100). The MEMS gyroscope comprises a first annular member (11), a fixing member (12) arranged on an inner side of the first annular member (11), a connecting member (13) connected between the first annular member (11) and the fixing member (12), and an outer electrode (14) surrounding the periphery of the first annular member (11). The outer electrode (14) comprises a driving electrode (141) for driving the first annular member (11) to vibrate in a first direction (X) and a second direction (Y), which are perpendicular to each other, and a detection electrode (142) for detecting the vibration of the first annular member (11) in a direction (D) forming a 45-degree included angle with the first direction (X) and a direction (M) forming a 135-degree included angle with the first direction (X), and the outer contour of the first annular member (11) is a positive 8N-pointed star, wherein N is an integer, and N ≥ 2. According to the MEMS gyroscope, the outer contour of the first annular member is configured to be a positive 8N-pointed star, and the characteristics of star-shaped corners being prone to deformation and the structure being symmetric are utilized, such that on the one hand, degeneracy of a driving mode and a detection mode of the gyroscope can be achieved, and the principle of the Coriolis effect is met, and on the other hand, the star-shaped structure can improve the quality factor of the MEMS gyroscope and improve the performance of the gyroscope.

Description

MEMS gyroscope

【Technical Field】

The invention relates to the technical field of gyroscopes, in particular to a MEMS gyroscope.

【Background technique】

Micromechanical gyroscopes, namely MEMS (Micro Electro Mechanical systems) gyroscopes, are a typical angular velocity micro sensor. Due to its small size, low power consumption and convenient processing, it has a very wide range of applications in the consumer electronics market. In recent years, with the gradual improvement of the performance of MEMS gyroscopes, it has been widely used in fields such as automobiles, industry, and virtual reality.

MEMS gyroscopes can be divided into two types: linear vibration tuning fork gyroscopes and disc gyroscopes. Among them, the drive mode and detection mode of the disc gyroscope are degenerate, with high sensitivity and simple structure. It has gradually become a more practical and widely used high-performance gyroscope. However, the disc-shaped gyroscope is limited by the structure and space layout, resulting in a low quality factor, and the electric capacity that can be accommodated in the structure is small, which has application limitations.

Therefore, it is necessary to provide a new MEMS gyroscope to solve the above-mentioned problems.

[Summary of the invention]

The purpose of the present invention is to disclose a MEMS gyroscope with a high quality factor.

The purpose of the present invention is achieved by adopting the following technical solutions:

A MEMS gyroscope, comprising a first ring member, a fixing member arranged on the inner side of the first ring member, a connecting member connected between the first ring member and the fixing member, and a ring surrounding the first ring member. An outer electrode on the outer periphery of a ring member, the outer electrode includes a driving electrode for driving the first ring member to vibrate in a first direction and a second direction perpendicular to each other, and a driving electrode for detecting that the first ring member is The first direction has an angle of 45 degrees and the angle of the first direction is a detection electrode of 135 degrees. The outer contour of the first ring is a positive 8N angular star, where N is an integer. , And N≥2.

As an improvement, the connecting member is a ring-shaped solid member, the outer side of which is connected with the first ring member and the inner side of which is connected with the fixing member.

As an improvement, the connecting member includes spokes and a plurality of second ring members arranged at coaxial intervals between the first ring member and the fixing member, and the second ring member is positive 8N-pointed star, between the first ring member and the second ring member close to the first ring member, between any two adjacent second ring members, and between the fixing member and the adjacent The second ring members of the fixing member are all connected by the spokes.

As an improvement, 4N spokes are arranged between any two adjacent second ring members, 4N spokes are distributed at equal intervals around the fixing member, and one end of the spoke is connected to one of the The apex of the second ring member and the other end are connected to the apex of the other second ring member.

As an improvement, 4N spokes are arranged between any two adjacent second ring members, and 4N spokes are distributed at equal intervals around the fixing member, and one of the second ring members is The corner includes two first diagonal rods extending toward each other and a first cross rod connected between the two first diagonal rods, and the corner of the other second ring member includes two second diagonal rods extending toward each other. An oblique rod and a second crossbar connected between the two second oblique rods, one end of the spoke is connected to the first crossbar, and the other end is connected to the second crossbar.

As an improvement, the MEMS gyroscope further includes a mass ring suspended between two adjacent second ring members.

As an improved manner, the mass ring includes a plurality of first masses distributed around the fixing member at intervals, and each of the two sides of the spoke is connected to one of the first masses.

As an improvement, the mass ring also includes a plurality of second masses spaced around the fixing member, and one second mass is provided between two adjacent spokes, each of the The second mass is V-shaped, and the tip of the second mass is connected with the corner of the second ring member protruding outward.

As an improvement, the MEMS gyroscope further includes an inner electrode arranged between two adjacent second ring members, and the inner electrode is located between the mass ring and the fixing member.

As an improvement, there are 8N external electrodes and each of the external electrodes is V-shaped, and each corner of the first ring member is provided with one external electrode.

As an improvement, the first ring member, the fixing member and the connecting member are integrally formed.

As an improvement, the first ring member is a regular six-pointed star.

Compared with the prior art, the embodiment of the present invention uses the features of easy deformation and symmetrical structure of the corners of the star by arranging the first ring as a positive 8N angular star. On the one hand, it can realize the driving mode of the gyroscope and the detection mode. The degeneracy of the state conforms to the principle of the Coriolis effect. On the other hand, the star-shaped structure can improve the quality factor of the MEMS gyroscope and improve the performance of the gyroscope.

【Explanation of the drawings】

FIG. 1 is a schematic front view of the MEMS gyroscope disclosed in the first embodiment of the present invention;

2 is a schematic diagram of the vibration mode in the Y-axis direction of the MEMS gyroscope disclosed in the first embodiment of the present invention;

3 is a schematic diagram of the detection mode of the MEMS gyroscope disclosed in the first embodiment of the present invention in the direction of the 45-degree axis;

4 is a schematic front view of the MEMS gyroscope disclosed in the second embodiment of the present invention;

Figure 5 is a schematic diagram of the relationship between the _{thermoelastic damping Q TED} of the gyroscope and the heat release frequency f _T;

6 is a schematic diagram of the connection between two adjacent second ring members and spokes in other embodiments of the present invention;

7 is a schematic front view of the MEMS gyroscope disclosed in the third embodiment of the present invention;

8 is a partial schematic diagram of the MEMS gyroscope disclosed in the third embodiment of the present invention;

9 is a schematic front view of the MEMS gyroscope disclosed in the fourth embodiment of the present invention;

FIG. 10 is a partial schematic diagram of the MEMS gyroscope disclosed in the fourth embodiment of the present invention.

【Detailed ways】

The present invention will be further described below in conjunction with the drawings and embodiments.

It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relationship between components in a specific posture (as shown in the accompanying drawings). If the relative position relationship, movement situation, etc. change, the directional indication will change accordingly.

It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be a centering element at the same time. When an element is said to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time.

In addition, the descriptions related to "first", "second", etc. in the present invention are only used for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on what can be achieved by a person of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that such a combination of technical solutions does not exist. , Is not within the protection scope of the present invention.

Example one:

Referring to FIG. 1, the first embodiment of the present invention discloses a MEMS gyroscope 100, which includes a first ring member 11, a fixing member 12 arranged inside the first ring member 11, connected to the first ring member 11 and the fixing member The connecting member 13 between 12 and the outer electrode 14 surrounding the outer circumference of the first ring member 11, the outer electrode 14 includes a drive for driving the first ring member 11 to vibrate in a first direction X and a second direction Y perpendicular to each other The electrode 141 and the detection electrode 142 used to detect the first ring member 11 vibrating along the direction D at the angle of 45 degrees with the first direction X and the direction M at the angle of 135 degrees with the first direction X, the first ring member 11 The outer contour of is a positive 8N-pointed star, where N is an integer, and N≥2. The MEMS gyroscope 100 is fixed by the fixing member 12.

When the MEMS gyroscope 100 is used, when the object is not rotating, the first ring member 11 vibrates in the first direction X and the second direction Y under the action of the driving force F1 of the driving electrode 141 to form a vibration mode, as shown in Figure 2 Is the vibration mode of the first ring 11 in the second direction Y. When the object rotates, according to the Coriolis principle, the angular velocity of the rotation of the object produces a resultant force F2 of the Coriolis force along the direction D of 45 degrees and the direction M of 135 degrees. The resultant force F2 of the Coriolis force will force the first ring member 11 along the 45 degree direction D. It vibrates in the direction M of 135 degrees to form a detection mode. FIG. 3 shows the detection mode of the first ring member 11 in the direction D of 45 degrees. The detecting electrode 142 detects the displacement of the first ring member 11 in the direction D of 45 degrees and the direction M of 135 degrees, and can obtain the magnitude of the rotation angular velocity of the object after arithmetic processing.

In the MEMS gyroscope 100 disclosed in this embodiment, by setting the outer contour of the first ring member 11 to be a positive 8N angular star, the corners of the star are easily deformed and the structure is symmetrical. On the one hand, the gyroscope driving mode and The degeneracy of the detection mode conforms to the principle of the Coriolis effect. On the other hand, the star-shaped structure can improve the quality factor of the MEMS gyroscope 100 and improve the performance of the gyroscope.

As an improvement of this embodiment, the connecting member 13 is a ring-shaped solid member, the outer side of which is connected to the first ring member 11 and the inner side of which is connected to the fixing member 12. Specifically, the first ring member 11, the fixing member 12, and the connecting member 13 are an integral part, the first ring member 11 is the part defined by the outer edge A of the integral part and the dashed line B, and the fixing member 12 is defined by the dashed line C section.

As an improvement of this embodiment, there are 8N external electrodes 14 and each external electrode 14 is V-shaped, and each corner 111 of the first ring member 11 is provided with an external electrode 14. It should be noted that the outer electrode 14 is spaced from the corner 111 and forms a capacitor with the corner 111. By adjusting the capacitor, the driving force required for the first ring member 11 to vibrate in the X-axis and Y-axis directions can be formed, and By detecting the size of the capacitance formed between the outer electrode 14 and the corner 111, the displacement of the first ring member 11 along the 45-degree axis and the 135-degree axis can be detected and converted, and then the angular velocity of the object can be converted.

As an improvement of this embodiment, the first ring member 11, the fixing member 12 and the connecting member 13 are integrally formed. Preferably, the first ring member 11, the fixing member 12 and the connecting member 13 are integrally formed by a silicon wafer integrally formed.

Preferably, the first ring 11 is a regular sixteen-pointed star.

Embodiment two:

Please refer to FIGS. 4-5. The difference between the MEMS gyroscope 200 disclosed in this embodiment and the MEMS gyroscope 100 disclosed in the first embodiment is: in the MEMS gyroscope 200 disclosed in this embodiment, the connecting member 23 includes a spoke 231 and a plurality of spokes. The second ring member 232 is arranged between the first ring member 21 and the fixing member 22 at a coaxial interval. The second ring member 232 is a positive 8N angular star. The first ring member 21 is close to the first ring member 21. The second ring members 232, any two adjacent second ring members 232, and the fixing member 22 and the second ring member 232 close to the fixing member 22 are all connected by spokes 231. The coaxially spaced arrangement refers to that a plurality of second ring members 232 are coaxially arranged and any adjacent second ring members 232 are arranged at intervals.

In order to improve the performance of the gyroscope, the first choice is to increase the quality factor of the gyroscope. The quality factor is an index to evaluate the energy loss of the gyroscope structure. Common energy loss mechanisms include: air damping loss, surface loss, fixed point loss, electronic device damping, and thermoelastic damping loss. Since the gyroscope is working in a high vacuum state, the air damping loss is small, and the thermoelastic damping Q _TED becomes the main source of energy loss when the gyroscope is working, that is, Q _TED is the upper limit of the gyroscope's quality factor. According to Zener's theory of thermoelastic loss, the calculation model of the _{thermoelastic quality factor Q TED is:}

Among them, f _M and f _T are the mechanical frequency and heat release frequency of the resonator, respectively. E is Young's modulus, and a is the linear coefficient of thermal diffusion. T ₀ is the ambient temperature of the beam, c _v is the specific heat capacity, k is the thermal conductivity, and h is the flexible deformation width of the resonator. According to the above formula, the _{law of change between f T} and Q _TED is shown in Figure 5.

Substituting the material parameters of silicon and the flexural deformation width of a typical MEMS resonator (take h = 1-500um), the calculation shows that the heat release frequency of a typical MEMS resonator f _T > 2MHz, and the calculated heat release frequency value is much larger than The mechanical frequency of a typical gyroscope. Therefore, for the gyroscope Q _TED _{in the region where f M} <f _T in FIG. 5, increasing the gyroscope f _T can increase the gyroscope Q _TED . Correspondingly, according to the _{expression of f T,} it can be inferred that reducing the flexural deformation width h in the resonator is a structural optimization method _{for improving the Q TED of the gyro.}

In this embodiment, the connecting member 13 in the first embodiment is optimized into a structure of nesting multiple layers of similar positive 8N angular stars. This design method reduces the flexible deformation width h, increases the top f _T , and improves the top quality Factor, thereby improving the performance of the entire MEMS gyroscope 200.

Preferably, the number of second ring members 232 is 3-8, more preferably 5. Preferably, the fixing member 22 is also a positive 8N-point star. Of course, the fixing member 22 can also be provided in other shapes, for example, a circular shape is also possible.

As an improvement of this embodiment, 4N spokes 231 are arranged between any two adjacent second ring members 232, 4N spokes 231 are distributed at equal intervals around the fixing member 22, and one end of each spoke 231 is connected to a first The apex of the two ring members 232 and the other end are connected to the apex of the other second ring member 232.

Please refer to FIG. 6, in some other embodiments, the corner 233 of one of the second ring members 232 includes two first inclined rods 241 extending oppositely and a first horizontal rod connected between the two first inclined rods 241. The rod 242, the corner 234 of the other second ring 232 includes two second inclined rods 251 extending toward each other and a second cross rod 252 connected between the two second inclined rods 251. One end of the spoke 231 is connected to The other end of the first cross bar 242 is connected to the second cross bar 252. This design method increases the reliability of the connection between the spokes 231 and the two adjacent second ring members 232.

The structure of other components in the MEMS gyroscope 200 disclosed in this embodiment and the connection relationship between the components can refer to the MEMS gyroscope 100 disclosed in Embodiment 1, which will not be repeated here.

Embodiment three:

Referring to FIGS. 7-8, the difference between the MEMS gyroscope 300 disclosed in this embodiment and the MEMS gyroscope 200 disclosed in the second embodiment is that the MEMS gyroscope 300 disclosed in this embodiment also includes two adjacent second rings. Mass ring 35 between pieces 332. By suspending the mass ring 35 between two adjacent second ring members 332, the sensitivity of the second ring member 332 can be increased, and the performance of the MEMS gyroscope 200 can be improved.

As an improvement of this embodiment, the mass ring 35 includes a plurality of first masses 351 distributed around the fixing member 312 at intervals, and two first masses 351 are respectively connected to both sides of each spoke 331.

As an improvement of this embodiment, the mass ring 35 further includes a plurality of second masses 352 spaced around the fixing member 312, and a second mass 352 is provided between two adjacent spokes 331. The second mass 352 is V-shaped, and the tip of the second mass 352 is connected to the corner of the second ring 332 protruding outward.

The structure of other components in the MEMS gyroscope 300 disclosed in this embodiment and the connection relationship between the components can refer to the MEMS gyroscope 100 disclosed in the first embodiment, which will not be repeated here.

Embodiment four:

9-10, the difference between the MEMS gyroscope 400 disclosed in this embodiment and the MEMS gyroscope 300 disclosed in the third embodiment is: the MEMS gyroscope 400 disclosed in this embodiment further includes two adjacent second rings. The inner electrode 46 between the parts 432 is located between the mass ring 45 and the fixing part 42. By arranging the inner electrode 46 between the two adjacent second ring members 432, the inner electrode 46 expands the usable capacitance of the MEMS gyroscope 400 and improves the sensitivity and performance of the MEMS gyroscope 400.

The structure of other components in the MEMS gyroscope 400 disclosed in this embodiment and the connection relationship between the components can refer to the MEMS gyroscope 100 disclosed in the first embodiment, which will not be repeated here.

The above are only the embodiments of the present invention. It should be pointed out here that for those of ordinary skill in the art, improvements can be made without departing from the inventive concept of the present invention, but these all belong to the present invention. The scope of protection.

Claims

A MEMS gyroscope, which is characterized by comprising a first ring member, a fixing member arranged inside the first ring member, a connecting member connected between the first ring member and the fixing member, and a surrounding An outer electrode on the outer periphery of the first ring member, the outer electrode includes a driving electrode for driving the first ring member to vibrate in a first direction and a second direction perpendicular to each other, and a driving electrode for detecting the first ring member The detection electrode vibrates along the angle of 45 degrees with the first direction and the angle of 135 degrees with the first direction. The outer contour of the first ring is a positive 8N angular star, wherein , N is an integer, and N≥2.
The MEMS gyroscope according to claim 1, wherein the connecting member is a ring-shaped solid member, the outer side of which is connected to the first ring member, and the inner side of which is connected to the fixing member.
The MEMS gyroscope according to claim 1, wherein the connecting member includes a spoke and a plurality of second ring members arranged between the first ring member and the fixing member and arranged at coaxial intervals. , The second ring member is a positive 8N angular star, and between the first ring member and the second ring member close to the first ring member, one of any two adjacent second ring members And between the fixing member and the second ring member close to the fixing member are connected by the spokes.
The MEMS gyroscope according to claim 3, wherein 4N said spokes are arranged between any two adjacent second ring members, and 4N said spokes are distributed at equal intervals around said fixing member, One end of the spoke is connected to the apex of the second ring member, and the other end is connected to the apex of the other second ring member.
The MEMS gyroscope according to claim 3, wherein 4N said spokes are arranged between any two adjacent second ring members, and 4N said spokes are distributed at equal intervals around said fixing member, One of the corners of the second ring member includes two first diagonal rods extending opposite to each other and a first cross rod connected between the two first diagonal rods, and the other corner of the second ring member The part includes two second diagonal rods extending toward each other and a second cross rod connected between the two second diagonal rods. One end of the spoke is connected to the first cross rod, and the other end is connected to the first cross rod. The second crossbar.
The MEMS gyroscope according to claim 4, wherein the MEMS gyroscope further comprises a mass ring suspended between two adjacent second ring members.
The MEMS gyroscope according to claim 6, wherein the mass ring includes a plurality of first masses spaced around the fixing member, and each of the spokes is connected to one of the first masses on both sides of the spoke. Mass.
The MEMS gyroscope according to claim 7, wherein the mass ring further comprises a plurality of second masses spaced around the fixing member, and a second mass is provided between two adjacent spokes. The second masses, each of the second masses is V-shaped, and the tip of the second mass is connected with the corner tip of the second ring member protruding outward.
The MEMS gyroscope according to claim 6, wherein the MEMS gyroscope further comprises an internal electrode arranged between two adjacent second ring members, and the internal electrode is located between the mass ring and the mass ring. Between the fixing parts.
The MEMS gyroscope according to claim 1, wherein there are 8N external electrodes and each of the external electrodes is V-shaped, and each corner of the first ring is covered with one External electrode.
The MEMS gyroscope according to claim 1, wherein the first ring member, the fixing member and the connecting member are integrally formed.
The MEMS gyroscope according to claim 1, wherein the first ring member is a regular sixteen-pointed star.