WO2021134668A1

WO2021134668A1 - Mems gyroscope

Info

Publication number: WO2021134668A1
Application number: PCT/CN2019/130903
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 fixing member (11) with a cavity (111), a resonant ring (12) arranged in the cavity (111), and a first electrode (13) arranged on an inner side of the resonant ring (12). The first electrode (13) comprises a driving electrode for driving the resonant ring (12) to vibrate in a first direction (X) and a second direction (Y), which are perpendicular to each other, and a detection electrode for detecting the vibration of the resonant ring (12) 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); the resonant ring (12) comprises spokes (121) and a plurality of annular members (122), which are arranged between the fixing member (11) and the first electrode (13) and are sequentially nested from the fixing member (11) to the first electrode (13); any two adjacent annular members (122) are connected and the fixing member (11) and an annular member (122) close to the fixing member (11) are connected by means of the spokes (121); and the annular members (122) are a positive 8N-pointed star, wherein N is an integer, and N ≥ 2. According to the MEMS gyroscope, the annular members are arranged to be the positive 8N-pointed star, a flexible deformation width h is reduced, a gyroscope f_T is increased, and the quality factor of the gyroscope and the performance of the whole MEMS gyroscope are thus improved.

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 fixing member with a cavity, a resonant ring arranged in the cavity, and a first electrode arranged inside the resonant ring, the first electrode including a cavity for driving the resonance The driving electrode of the ring vibrating in the first direction and the second direction perpendicular to each other is used to detect that the angle between the resonant ring and the first direction is 45 degrees and the angle with the first direction is 135 degrees Directionally vibrating detection electrode, the resonant ring includes spokes and a plurality of ring members arranged between the fixing member and the first electrode and nested sequentially from the fixing member toward the first electrode, any phase The two adjacent ring members and the fixing member and the ring member close to the fixing member are all connected by the spokes. The ring member is a positive 8N angular star, where N is an integer, And N≥2.

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

As an improvement, 4N spokes are arranged between any two adjacent ring members, and the 4N spokes are distributed at equal intervals on the circumference, and the corner of one of the ring members includes two oppositely extending corners. The first diagonal rod and the first cross rod connected between the two first diagonal rods, and the corner of the other ring member includes two second diagonal rods extending oppositely and connected to the two first diagonal rods. For the second cross bar between the second diagonal bars, one end of the spoke is connected to the first cross bar, and the other end is connected to the second cross bar.

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

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

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

As an improvement, the first electrodes are provided with 8N and each of the first electrodes is provided with a V-shaped groove, and the corner of the ring member is embedded in the V-shaped groove.

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

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

Compared with the prior art, the embodiment of the present invention is configured to be a positive 8N angular star, and the corners of the star are easily deformed and the structure is symmetrical. On the one hand, the gyroscope driving mode and the detection mode can be achieved. Degenerate, in line with the principle of the Coriolis effect, on the other hand, the resonance ring is optimized into a structure of nested multi-layer similar positive 8N angular stars. This design method reduces the flexible deformation width h, increases the gyro f _T , and improves the gyro Quality factor, thereby enhancing the performance of the entire MEMS 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 partial schematic diagram of the MEMS gyroscope disclosed in the first embodiment of the present invention;

Fig. 3 is a schematic diagram of the vibration mode of the MEMS gyroscope disclosed in the first embodiment of the present invention in the X-axis direction;

4 is a schematic diagram of the detection mode of the MEMS gyroscope disclosed in the first embodiment of the present invention in the 135-degree axis direction;

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;

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

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

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

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

FIG. 10 is a partial schematic diagram of the MEMS gyroscope disclosed in the third 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 FIGS. 1-2, the first embodiment of the present invention discloses a MEMS gyroscope 100, which includes a fixing member 11 having a cavity 111, a resonant ring 12 arranged in the cavity 111, and an inner side of the resonant ring 12 The first electrode 13 includes a driving electrode for driving the resonance ring 12 to vibrate in a first direction X and a second direction Y that are perpendicular to each other, and a driving electrode for detecting the angle between the resonance ring 12 and the first direction. The 45-degree direction D and the first direction include a detection electrode that vibrates in a 135-degree direction M. The resonant ring 12 includes spokes 121 and a plurality of spokes disposed between the fixing member 11 and the first electrode 13 and moving from the fixing member 11 to the first A ring member 122 in which the electrode 13 is nested in sequence, between any two adjacent ring members 122, and between the fixing member 11 and the ring member 122 close to the fixing member 11 are connected by spokes 121, the ring member 122 is positive 8N Corner star, where N is an integer, and N≥2.

When the MEMS gyroscope 100 is used, when the object is not rotating, the ring member 122 vibrates in the first direction X and the second direction Y under the action of the driving electrode driving force F1 to form a vibration mode. Figure 3 shows a ring shape. The vibration mode of the member 122 in the first direction X. 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 ring member 122 in the directions D and 135 of 45 degrees. Vibrate in the direction M of degrees to form a detection mode. FIG. 4 shows the detection mode of the ring 122 in the direction M of 135 degrees. The detection electrode detects the displacement of the ring 122 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 through arithmetic processing.

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 the MEMS gyroscope 100 disclosed in this embodiment, by setting the ring 122 as 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 detection mode can be simplified. In addition, it conforms to the principle of Coriolis effect. On the other hand, the resonance ring 12 is optimized into a structure of nested multi-layer similar positive 8N angular stars. This design method reduces the flexible deformation width h, increases the gyro f _T , and improves the gyro The quality factor improves the performance of the entire MEMS gyroscope 100.

As an improvement of this embodiment, 4N spokes 121 are arranged between any two adjacent ring members 122, and the 4N spokes 121 are distributed at equal intervals on the circumference. One end of the spoke 121 is connected to the apex of one ring member 122 and the other One end is connected to the apex of the other ring 122.

Please refer to FIG. 6, in other embodiments, the corner of one of the ring members 122 of any two adjacent ring members 122 includes two first inclined rods 131 extending oppositely and connected to the two first inclined rods. The corner of the first crossbar 132 between 131 and the other ring 122 includes two second diagonal rods 141 extending toward each other, a second crossbar 142 connected between the two second diagonal rods 141, and spokes 121 One end is connected to the first cross bar 132, and the other end is connected to the second cross bar 142. This design method increases the reliability of the connection between the spoke 121 and the two adjacent ring members 122.

As an improvement of this embodiment, there are 8N first electrodes 13 and each first electrode 13 is provided with a V-shaped groove 131, and the corner 1221 of the ring member 122 is embedded in the V-shaped groove 131.

As an improvement of this embodiment, the fixing member 11 and the resonance ring 12 are integrally formed. Preferably, the fixing member 11 and the resonance ring 12 are integrally formed with silicon wafers. In other embodiments, the fixing member 11, the resonance ring 12 and the first electrode 13 are integrally formed.

As an improvement of this embodiment, the ring 122 is a regular sixteen-pointed star.

Embodiment two:

Referring to FIGS. 7-8, the difference between the MEMS gyroscope 200 disclosed in this embodiment and the MEMS gyroscope 100 disclosed in the first embodiment is: the MEMS gyroscope 200 disclosed in this embodiment further includes two adjacent ring members 222. Between the quality ring 40. By suspending the mass ring 40 between two adjacent ring members 222, the sensitivity of the ring member 40 can be increased, and the performance of the MEMS gyroscope 200 can be improved.

As an improvement of this embodiment, the mass ring 40 includes a plurality of first masses 41 distributed around the first electrode 23 at intervals, and two first masses 41 are respectively connected to both sides of each spoke 221.

As an improvement of this embodiment, the mass ring 40 also includes a plurality of second masses 42 spaced around the first electrode 23, and a second mass 42 is provided between two adjacent spokes 221, each The second mass 42 is V-shaped, and the tip of the second mass 42 is connected with the corner tip of the ring 222 protruding outward.

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:

9-10, the difference between the MEMS gyroscope 300 disclosed in this embodiment and the MEMS gyroscope 100 disclosed in the second embodiment is that the MEMS gyroscope 300 disclosed in this embodiment further includes two adjacent ring members 322. The second electrode 50 is located between the mass ring 40 and the fixing member 10. By providing the second electrode 50 between the two adjacent ring members 322, the second electrode 50 expands the usable capacitance of the MEMS gyroscope 300 and improves the sensitivity and performance of the MEMS gyroscope 300.

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.

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 in that it comprises a fixing member with a cavity, a resonance ring arranged in the cavity, and a first electrode arranged inside the resonance ring, and the first electrode includes The driving electrode that drives the resonant ring to vibrate in the first direction and the second direction perpendicular to each other is used to detect that the resonant ring is in a 45-degree direction with the angle between the resonant ring and the first direction. The detection electrode vibrating at an angle of 135 degrees, the resonance ring includes spokes and a plurality of spokes, which are arranged between the fixing member and the first electrode and nested sequentially from the fixing member toward the first electrode The ring member, between any two adjacent ring members, and between the fixing member and the ring member close to the fixing member, are connected by the spokes, and the ring member is a positive 8N angular star, wherein , N is an integer, and N≥2.
The MEMS gyroscope according to claim 1, wherein 4N said spokes are provided between any two adjacent said ring members, and 4N said spokes are distributed at equal intervals on a circumference, and one end of said spokes The apex of one ring is connected, and the other end is connected with the apex of the other ring.
The MEMS gyroscope according to claim 1, wherein 4N said spokes are arranged between any two adjacent said ring members, and 4N said spokes are distributed at equal intervals on a circumference, and one of said ring-shaped parts The corner of the ring member 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 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.
The MEMS gyroscope according to claim 2 or 3, wherein the MEMS gyroscope further comprises a mass ring suspended between two adjacent ring members.
The MEMS gyroscope according to claim 4, wherein the mass ring includes a plurality of first masses spaced around the first electrode, and each of the spokes is connected to the first mass on both sides of the spoke. One mass.
The MEMS gyroscope according to claim 5, wherein the mass ring further comprises a plurality of second masses spaced around the first electrode, and there is a space between two adjacent spokes. For 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 ring member protruding outward.
The MEMS gyroscope according to claim 4, wherein the MEMS gyroscope further comprises a second electrode arranged between two adjacent ring members, and the second electrode is located between the mass ring and the Between the fixing parts.
The MEMS gyroscope according to claim 1, wherein the first electrodes are provided with 8N and each of the first electrodes is provided with a V-shaped groove, and the corner of the ring is embedded in the In the V-slot.
The MEMS gyroscope according to claim 1, wherein the fixing member and the resonance ring are integrally formed.
The MEMS gyroscope according to claim 1, wherein the ring member is a regular sixteen-pointed star.