A three-axis grating accelerometer device based on electrostatic feedback structure

Abstract

The present invention discloses a three-axis grating accelerometer device based on an electrostatic feedback structure. The accelerometer adopts a glass-silicon-glass sandwich structure, wherein the top layer is a glass layer with a metal grating, the middle layer is a silicon layer main structure, and the bottom layer is a glass layer plated with a metal electrode. The middle layer main structure compactly arranges the sensitive structures in the three directions of X, Y, and Z on the same silicon structure, and the three submodules independently realize three-axis acceleration measurement, with extremely low crosstalk, forming a three-axis silicon micro-sensitive structure, and then the control of the mass block is realized through the electrostatic feedback structure, so that the mass block is always in a balanced position. The device has good output linearity and high mechanical sensitivity. The present invention realizes a monolithic integrated micro-accelerometer device, reduces the device size and the overall packaging difficulty, and is used for acceleration measurement.

Description

Technical Field

[0001] The invention relates to the technical field of micro-electromechanical systems (MEMS) and micro-inertial measurement instruments, and in particular to a three-axis grating accelerometer device based on an electrostatic feedback structure. Background Art

[0002] As an important component of inertial measurement systems, accelerometers are widely used in inertial navigation, seismic monitoring, and resource exploration. These fields usually require the detection of µg-level acceleration. In order to obtain extremely low mechanical thermal noise and extremely high displacement resolution, the optical interference principle is combined with micro-electromechanical systems (MEMS) to realize an accelerometer based on the grating interferometric displacement measurement principle. Compared with mainstream capacitive accelerometers, grating accelerometers have the advantages of high sensitivity, high linearity, and strong anti-electromagnetic interference ability.

[0003] Due to the rapid development of MEMS processing technology, high precision, integration and miniaturization of inertial instruments have become the main development trends. Miniaturized accelerometers can now reach micro-G levels. If you want to further improve, it is difficult to achieve both miniaturization and high precision. The miniaturization of the mass block of traditional MEMS accelerometers will obtain several times the mechanical thermal noise, which is also an important reason why ultra-high precision inertial devices are difficult to break through miniaturization. Grating accelerometers combine grating interference technology with MEMS technology to form a highly sensitive integrated accelerometer, realizing high-sensitivity measurement of miniaturized inertial devices. Summary of the invention

[0004] To solve the above problems, the present invention discloses a three-axis grating accelerometer device based on an electrostatic feedback structure, which aims at solving the current technical difficulties in miniaturization of ultra-high precision inertial instruments and has the advantages of extremely high mechanical sensitivity, high linearity, strong anti-electromagnetic interference ability, etc.

[0005] A three-axis grating accelerometer device based on an electrostatic feedback structure includes a top structure, a middle main structure and a bottom structure, and the top structure, the middle main structure and the bottom structure are arranged from top to bottom to form a complete three-axis grating accelerometer structure. The middle main structure includes an X-axis module, a Y-axis module, a Z-axis module, a bonding module and a first bonding layer structure; the X-axis module is located at the upper left corner of the middle main structure, the Y-axis module is located at the lower right corner of the middle main structure, the X-axis module and the Y-axis module are arranged vertically, the Z-axis module is located at the lower left corner of the middle main structure, the bonding module is located at the upper right corner of the middle main structure, and the bonding electrodes of the first bonding layer structure are distributed at the four corners of each module; the middle main structure is a square, the X-axis module and the Y-axis module are exactly the same in structure, both are rectangular, the Z-axis module and the bonding module are It is a square, the lower long side of the X-axis module coincides with the upper side of the Z-axis module, the left long side of the Y-axis module coincides with the right long side of the Z-axis module, the left long side of the bonding module coincides with the right short side of the X-axis module, the lower long side coincides with the upper short side of the Y-axis module, and the lower surface of the first bonding layer structure coincides with the upper surfaces of the X-axis module, the Y-axis module, the Z-axis module, and the bonding module; the X-axis module is used to measure the acceleration in the X-axis direction, the Y-axis module is used to measure the acceleration in the Y-axis direction, the Z-axis module is used to measure the acceleration in the Z-axis direction, and the first bonding layer structure is used to bond with the top structure.

[0006] The present invention is further improved in that: the X-axis module is composed of an X-axis annular outer frame, first and second X-axis annular outer elastic beams, an X-axis annular connecting frame, first and second X-axis annular inner elastic beams, an X-axis comb tooth structure, an X-axis movable grating mass block, and first and second X-axis fixed grating mass blocks; the first and second X-axis fixed grating mass blocks are located at the center of the X-axis movable grating mass block, and are symmetrically distributed about the center of the X-axis module, and a large number of parallel equidistant grooves are engraved on the upper surfaces of the first and second X-axis fixed grating mass blocks to form a grating part; the X-axis movable grating mass block is located at the exact center of the X-axis module, and is equidistantly divided into five parts, the second and fourth parts are hollowed out, and the first, third and fifth parts are kept connected, and a large number of parallel equidistant grooves are also engraved on the upper surface of the X-axis movable grating mass block to form a grating part; the X-axis comb tooth structure is located on the left and right sides of the X-axis movable grating mass block, and the X-axis comb tooth structure is composed of the first, second and third parts on the left side of the X-axis movable grating mass block. X-axis feedback comb teeth, composed of the fourth, fifth and sixth X-axis feedback comb teeth on the right side of the X-axis movable grating mass block, the feedback comb teeth on the left and right sides are equally spaced, the feedback comb teeth are composed of a pair of fixed comb teeth and a movable comb tooth, the fixed comb teeth are symmetrically distributed on the upper and lower sides of the movable comb teeth, and a certain overlapping length is formed between the comb teeth and the spacing between adjacent comb teeth is equal, the upper side is the driving comb teeth, and the lower side is the sensing comb teeth, the movable comb teeth are connected to the X-axis movable grating mass block, and reflect the displacement of the X-axis movable grating mass block; the X-axis movable grating mass block is supported on the X-axis annular connection frame through the upper first X-axis annular inner elastic beam and the lower second X-axis annular inner elastic beam, the internal structure of the X-axis annular connection frame is supported on the X-axis annular outer frame as a whole through the upper first X-axis annular outer elastic beam and the lower second X-axis annular outer elastic beam, wherein the first and second X-axis annular outer elastic beams are slightly longer than the first and second X-axis annular inner elastic beams. When the collimated laser beam passes through the top glass and irradiates the grating approximately, part of the light is directly reflected and forms diffraction beam 1, and the other part of the incident light is reflected back after passing through the gap of the grating, and forms diffraction beam 2 after passing through the grating again. The two diffraction beams will interfere and produce interference spots. When there is an X-axis acceleration input from the outside, the X-axis movable grating mass block will be displaced by the inertial force, while the first and second X-axis fixed grating mass blocks will not change, thereby affecting the change of the spot intensity. At the same time, the X-axis electrostatic feedback comb structure is used to control the X-axis movable grating mass block, so that the X-axis movable grating mass block is always in a balanced position, and finally the closed-loop measurement of the X-axis acceleration is realized.

[0007] The present invention is further improved in that: the Y-axis module is composed of a Y-axis annular outer frame, first and second Y-axis annular outer elastic beams, a Y-axis annular connecting frame, first and second Y-axis annular inner elastic beams, a Y-axis comb tooth structure, a Y-axis movable grating mass block, and first and second Y-axis fixed grating mass blocks; the first and second Y-axis fixed grating mass blocks are located at the inner center of the Y-axis movable grating mass block, and are symmetrically distributed up and down about the center of the Y-axis module, and a large number of parallel equidistant grooves are engraved on the upper surfaces of the first and second Y-axis fixed grating mass blocks to form a grating part; the Y-axis movable grating mass block is located at the exact center of the Y-axis module, and is equidistantly divided into five parts, the second and fourth parts are hollowed out, the first, third and fifth parts are kept connected, and a large number of parallel equidistant grooves are also engraved on the upper surface of the Y-axis movable grating mass block to form a grating part; the Y-axis comb tooth structure is located at the upper and lower sides of the Y-axis movable grating mass block, and the Y-axis comb tooth structure is composed of the first, second and third parts above the Y-axis movable grating mass block. The Y-axis feedback comb teeth are composed of the fourth, fifth and sixth Y-axis feedback comb teeth below the Y-axis movable grating mass block. The feedback comb teeth on the upper and lower sides are equally spaced. The feedback comb teeth are composed of a pair of fixed comb teeth and a movable comb tooth. The fixed comb teeth are symmetrically distributed on the left and right sides of the movable comb teeth, and a certain overlapping length is formed between the comb teeth, and the spacing between adjacent comb teeth is equal. The left side is the driving comb teeth, and the right side is the sensing comb teeth. The movable comb teeth are connected to the Y-axis movable grating mass block to reflect the displacement of the Y-axis movable grating mass block. The Y-axis movable grating mass block is supported on the Y-axis annular connection frame by the first Y-axis annular inner elastic beam on the left and the second Y-axis annular inner elastic beam on the right. The internal structure of the Y-axis annular connection frame is supported on the Y-axis annular outer frame as a whole by the first Y-axis annular outer elastic beam on the left and the second Y-axis annular outer elastic beam on the right, wherein the first and second Y-axis annular outer elastic beams are slightly longer than the first and second Y-axis annular inner elastic beams. When the collimated laser beam passes through the top glass and irradiates the grating approximately vertically, part of the light is directly reflected and forms diffraction beam 1, and the other part of the incident light is reflected back after passing through the gap of the grating, and forms diffraction beam 2 after passing through the grating again. The two diffraction beams will interfere and produce interference spots. When there is Y-axis acceleration input from the outside, the Y-axis movable grating mass block will be displaced by the inertial force, while the first and second Y-axis fixed grating mass blocks will not change, thereby affecting the change of the spot intensity. At the same time, the Y-axis movable grating mass block is controlled by the Y-axis electrostatic feedback comb structure, so that the Y-axis movable grating mass block is always in a balanced position, and finally the closed-loop measurement of the Y-axis acceleration is realized.

[0008] The present invention is further improved in that: the Z-axis module is composed of a Z-axis annular outer frame, a first, second, third, and fourth Z-axis U-shaped outer elastic beams, a Z-axis annular connecting frame, a first, second, third, and fourth Z-axis U-shaped inner elastic beams, a Z-axis mass block, a first and second Z-axis metal electrodes, and a Z-axis inner reflective film; the Z-axis mass block is square and is located at the exact center of the Z-axis module; the Z-axis inner reflective film is square and has a side length smaller than the side length of the Z-axis mass block and is located at the center of the upper surface of the Z-axis mass block; the first and second Z-axis metal electrodes are annular and have an outer size slightly smaller than the Z-axis mass block and an inner size slightly larger than the Z-axis inner reflective film; the first Z-axis metal electrode is located at the center of the upper surface of the Z-axis mass block, and the second Z-axis metal electrode is located at the center of the lower surface of the Z-axis mass block; the first Z-axis U-shaped inner elastic beam is located above the Z-axis mass block, and the second Z-axis U-shaped inner elastic beam is located above the Z-axis mass block. Located on the right side of the Z-axis mass block, the third Z-axis U-shaped inner elastic beam is located below the Z-axis mass block, and the fourth Z-axis U-shaped inner elastic beam is located on the left side of the Z-axis mass block. The Z-axis mass block is supported on the Z-axis annular connecting frame through the first, second, third and fourth Z-axis U-shaped inner elastic beams. The first Z-axis U-shaped outer elastic beam is located above the Z-axis annular connecting frame, the second Z-axis U-shaped outer elastic beam is located on the right side of the Z-axis annular connecting frame, the third Z-axis U-shaped outer elastic beam is located below the Z-axis annular connecting frame, and the fourth Z-axis U-shaped outer elastic beam is located on the left side of the Z-axis annular connecting frame. The internal structure of the Z-axis annular connecting frame is taken as a whole, and is supported on the Z-axis annular outer frame through the first, second, third and fourth Z-axis U-shaped outer elastic beams, wherein the first, second, third and fourth Z-axis U-shaped outer elastic beams are slightly longer than the first, second, third and fourth Z-axis U-shaped inner elastic beams. When the collimated laser beam passes through the top glass and irradiates the grating approximately vertically, part of the light is directly reflected and forms diffraction beam 1, and the other part of the incident light is reflected back after passing through the gap of the grating, and forms diffraction beam 2 after passing through the grating again. The two diffraction beams will interfere and produce interference spots. When there is external Z-axis acceleration input, the Z-axis mass block will be affected by the inertial force, resulting in displacement along the Z-axis direction, thereby affecting the change of the spot intensity. At the same time, the closed-loop control of the Z-axis mass block is realized through the electrostatic feedback structure, so that the Z-axis mass block is always in a balanced position, and finally the closed-loop measurement of the Z-axis acceleration is realized.

[0009] The present invention is further improved in that: the first bonding layer structure includes first, second, third, fourth, fifth, sixth, seventh, eighth and ninth middle-layer bonding electrodes, the first middle-layer bonding electrode is located at the upper left corner of the upper surface of the X-axis module, the third middle-layer bonding electrode is located at the upper right corner of the upper surface of the bonding module, the seventh middle-layer bonding electrode is located at the lower left corner of the upper surface of the Z-axis module, the ninth middle-layer bonding electrode is located at the lower right corner of the upper surface of the Y-axis module, the centers of the fourth, fifth and sixth middle-layer bonding electrodes are located on the boundary line between the X-axis module and the Z-axis module, the centers of the second, fifth and eighth middle-layer bonding electrodes are located on the boundary line between the Y-axis module and the Z-axis module, the first, fourth and seventh middle-layer bonding electrodes, the second, fifth and eighth middle-layer bonding electrodes and the third, sixth and ninth middle-layer bonding electrodes are respectively located on the same vertical line, and the first, second and third middle-layer bonding electrodes, the fourth, fifth and sixth middle-layer bonding electrodes and the seventh, eighth and ninth middle-layer bonding electrodes are respectively located on the same horizontal line.

[0010] The present invention is further improved in that: the lower surface of the second bonding layer structure of the top structure completely overlaps with the upper surface of the first bonding layer structure of the middle main structure, and the lower surface of the annular outer frame and the bonding module of the middle main structure completely overlaps with the upper surface of the anchor layer of the bottom structure, forming a three-dimensional structure similar to a sandwich. In the top structure, the upper surface of the metal grating overlaps with the lower surface of the top glass substrate, the metal grating is directly opposite to the Z-axis inner reflective film of the middle main structure and there is a certain distance between the metal grating and the Z-axis inner reflective film, the upper surface of the top metal electrode overlaps with the lower surface of the top glass substrate, the top metal electrode is directly opposite to the first Z-axis metal electrode of the middle main structure and there is a certain distance between the metal electrode and the first Z-axis metal electrode, the upper surface of the second bonding layer structure overlaps with the lower surface of the top glass substrate, and the lower surface of the second bonding layer structure overlaps with the upper surface of the first bonding layer structure. In the middle main structure, the left side is X The Y-axis module is the same as the X-axis module. From left to right in the X-axis module are the X-axis annular outer frame, the first X-axis annular outer elastic beam, the X-axis annular connecting frame, the first X-axis annular inner elastic beam, the X-axis movable grating mass block, the second X-axis annular inner elastic beam, the X-axis annular connecting frame, the second X-axis annular outer elastic beam, and the X-axis annular outer frame. The X-axis movable grating mass block is located at the center of the X-axis module. The left surface of the X-axis movable grating mass block is adjacent to the first X-axis annular elastic beam. The right surface of the X-axis movable grating mass block is connected to the second X-axis annular inner elastic beam, the inner surface of the X-axis annular connecting frame is connected to the first and second X-axis annular inner elastic beams, the outer surface of the X-axis annular connecting frame is connected to the first and second X-axis annular outer elastic beams, and the inner surface of the X-axis annular outer frame is connected to the first and second X-axis annular outer elastic beams to form a nested structure; the Z-axis module is composed of the Z-axis annular outer frame, the first Z-axis U-shaped outer elastic beam, the Z-axis annular connecting frame, The first Z-axis U-shaped inner elastic beam, the Z-axis mass block, the third Z-axis U-shaped inner elastic beam, the Z-axis annular connecting frame, the third Z-axis U-shaped outer elastic beam, the Z-axis mass block is located at the center of the Z-axis module, the lower surface of the Z-axis inner reflective film coincides with the upper surface of the Z-axis mass block and is located at the center of the upper surface of the Z-axis mass block, the lower surface of the first Z-axis metal electrode coincides with the upper surface of the Z-axis mass block and is located at the center of the upper surface of the Z-axis mass block, the upper surface of the second Z-axis metal electrode coincides with the upper surface of the Z-axis mass block, and is located at the center of the upper surface of the Z-axis mass block. The lower surfaces of the Z-axis mass blocks overlap and are located at the center of the lower surface of the Z-axis mass block. The left surface of the Z-axis mass block is connected to the first Z-axis U-shaped inner elastic beam, the right surface of the Z-axis mass block is connected to the third Z-axis U-shaped inner elastic beam, the inner surface of the Z-axis annular connecting frame is connected to the first and third Z-axis U-shaped inner elastic beams, the outer surface of the Z-axis annular connecting frame is connected to the first and third Z-axis U-shaped outer elastic beams, and the inner surface of the Z-axis annular outer frame is connected to the first and third Z-axis U-shaped outer elastic beams, forming a nested structure.In the bottom structure, the upper surface of the X-axis outer frame anchor point coincides with the lower surface of the X-axis annular outer frame, the lower surface of the X-axis outer frame anchor point coincides with the upper surface of the bottom glass substrate, the upper surface of the Z-axis outer frame anchor point coincides with the lower surface of the Z-axis annular outer frame, the lower surface of the Z-axis outer frame anchor point coincides with the upper surface of the bottom glass substrate, the lower surface of the bottom metal electrode coincides with the upper surface of the bottom glass substrate, it is directly below the second Z-axis metal electrode and there is a certain distance between the second Z-axis metal electrode, the lower surface of the peripheral electrode coincides with the upper surface of the bottom glass substrate, and is located in the peripheral area of ​​the bottom glass substrate beyond the middle-layer main structure.

[0011] The present invention is further improved in that: the top structure is composed of a top glass substrate, a metal grating, a top metal electrode and a second bonding layer structure, the top glass substrate is square and consistent in size with the middle main structure, the metal grating is located directly above the Z-axis inner reflective film, and its size is consistent with the size of the Z-axis inner reflective film, the top metal electrode is annular and located directly above the Z-axis mass block, and its size is consistent with the first and second Z-axis metal electrodes, the metal grating is located inside the top metal electrode, and the centers of the two coincide, the second bonding layer structure includes the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth top bonding electrodes, the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth top bonding electrodes are respectively located directly above the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth middle bonding electrodes, and the first top bonding electrode is located The third top bonding electrode is located at the upper right corner of the upper surface of the top glass substrate, the seventh top bonding electrode is located at the lower right corner of the upper surface of the top glass substrate, the ninth top bonding electrode is located at the lower left corner of the upper surface of the top glass substrate, the centers of the fourth, fifth and sixth top bonding electrodes are located on the line where the boundary line of the X-axis module and the Z-axis module corresponds to the top glass substrate, the centers of the second, fifth and eighth top bonding electrodes are located on the line where the boundary line of the Y-axis module and the Z-axis module corresponds to the top glass substrate, the first, fourth and seventh top bonding electrodes, the second, fifth and eighth top bonding electrodes and the third, sixth and ninth top bonding electrodes are respectively located on the same vertical line, and the first, second and third top bonding electrodes, the fourth, fifth and sixth top bonding electrodes and the seventh, eighth and ninth top bonding electrodes are respectively located on the same horizontal line.

[0012] The present invention is further improved in that: the bottom structure is composed of a bottom glass substrate, an anchor layer, first and second X-axis fixed grating mass block anchors, first and second Y-axis fixed grating mass block anchors, bottom metal electrodes, X-axis drive electrodes, X-axis sensing electrodes, Y-axis drive electrodes, Y-axis sensing electrodes, and peripheral electrodes; the bottom glass substrate is a square, and the side length is slightly longer than the side length of the top glass substrate; the anchor layer includes an X-axis outer frame anchor, a Y-axis outer frame anchor, a Z-axis outer frame anchor, and a bonding module anchor; the outer size of the anchor layer is consistent with the size of the middle-layer main structure; the sizes of the X-axis outer frame anchor, the Y-axis outer frame anchor, the Z-axis outer frame anchor, and the bonding module anchor are respectively consistent with the sizes of the X-axis annular outer frame, the Y-axis annular outer frame, the Z-axis annular outer frame, and the bonding module anchor. The size of the bonding module is consistent, the X-axis outer frame anchor point is located directly below the X-axis annular outer frame and the upper surface coincides with the lower surface of the X-axis annular outer frame, the Y-axis outer frame anchor point is located directly below the Y-axis annular outer frame and the upper surface coincides with the lower surface of the Y-axis annular outer frame, the Z-axis outer frame anchor point is located directly below the Z-axis annular outer frame and the upper surface coincides with the lower surface of the Z-axis annular outer frame, the bonding module anchor point is located directly below the bonding module and the upper surface coincides with the lower surface of the bonding module, the size of the first and second X-axis fixed grating mass blocks anchor points is consistent with the size of the first and second X-axis fixed grating mass blocks, the first and second X-axis fixed grating mass blocks anchor points are respectively located directly below the first and second X-axis fixed grating mass blocks and the upper surfaces coincide with the first and second X-axis fixed grating mass blocks. The lower surface of the grating mass block coincides with that of the first and second Y-axis fixed grating mass blocks, the sizes of the first and second Y-axis fixed grating mass blocks anchor points are consistent with the sizes of the first and second Y-axis fixed grating mass blocks, the first and second Y-axis fixed grating mass blocks anchor points are respectively located directly below the first and second Y-axis fixed grating mass blocks and the upper surfaces coincide with the lower surfaces of the first and second Y-axis fixed grating mass blocks, the size of the bottom metal electrode is consistent with the size of the second Z-axis metal electrode, the bottom metal electrode is located directly below the second Z-axis metal electrode and there is a certain interval, the X-axis driving electrode includes the first, second, third, fourth, fifth and sixth X-axis driving electrodes, and the first, second, third, fourth, fifth and sixth X-axis driving electrodes are respectively located at the driving combs of the first, second, third, fourth, fifth and sixth X-axis feedback comb teeth. teeth, the X-axis sensing electrodes include first, second, third, fourth, fifth and sixth X-axis sensing electrodes, which are respectively located directly below the sensing comb teeth of the first, second, third, fourth, fifth and sixth X-axis feedback comb teeth, the Y-axis driving electrodes include first, second, third, fourth, fifth and sixth Y-axis driving electrodes, which are respectively located directly below the driving comb teeth of the first, second, third, fourth, fifth and sixth Y-axis feedback comb teeth, the Y-axis sensing electrodes include first, second, third, fourth, fifth and sixth Y-axis sensing electrodes, which are respectively located directly below the sensing comb teeth of the first, second, third, fourth, fifth and sixth Y-axis feedback comb teeth;The peripheral electrodes include first, second, third, fourth, fifth, sixth, seventh and eighth peripheral electrodes, which are located outside the anchor point layer on the upper surface of the bottom glass substrate, the first peripheral electrode is connected to the first, second and third X-axis sensing electrodes through a wire, the second peripheral electrode is connected to the first, second and third X-axis driving electrodes through a wire, the third peripheral electrode is connected to the fourth, fifth and sixth X-axis sensing electrodes through a wire, the fourth peripheral electrode is connected to the fourth, fifth and sixth X-axis driving electrodes through a wire, the fifth peripheral electrode is connected to the first, second and third Y-axis sensing electrodes through a wire, the sixth peripheral electrode is connected to the first, second and third Y-axis driving electrodes through a wire, the seventh peripheral electrode is connected to the fourth, fifth and sixth Y-axis sensing electrodes through a wire, and the eighth peripheral electrode is connected to the fourth, fifth and sixth Y-axis driving electrodes through a wire. ;

[0013] Beneficial effects of the present invention:

[0014] (1) The present invention proposes a three-axis grating accelerometer, which converts weak acceleration into displacement of a mass block, thereby causing the intensity of the interference spot to change. The distance between the mass block and the glass substrate is controlled by electrostatic feedback to achieve closed-loop control, thereby improving output linearity, improving sensitivity, and increasing the range. The acceleration in the three directions of the X-axis, Y-axis, and Z-axis is measured. The three axes do not interfere with each other and the crosstalk is extremely low, which effectively avoids the influence of cross-coupling on the accuracy of the three-axis grating accelerometer and enhances stability.

[0015] (2) The present invention micro-assembles an X-axis module, a Y-axis module, and a Z-axis module together to form a three-axis grating accelerometer. At the same time, each module adopts a highly symmetrical structure, and the overall structure adopts a glass-silicon-glass sandwich structure with a compact structure size to form a three-axis grating accelerometer with high integration and high detection accuracy.

[0016] (3) In the present invention, acceleration detection in the X and Y directions is realized by using an array grating structure and a horizontal axis acceleration sensitive structure, which are arranged perpendicular to each other to realize simultaneous measurement of the X and Y axes. The detection principles and structural schemes of the two are completely consistent. Acceleration causes a phase difference between the horizontal movable grating and the fixed grating. The horizontal acceleration measurement is realized by measuring the intensity change of the interference spot. At the same time, the electrostatic feedback comb structure is used to restore the mass block to its original position, realizing closed-loop detection of the acceleration signal. The Z-axis scheme uses a Fraunhofer interferometer cavity and a vertical axis acceleration sensitive structure to realize acceleration detection. The input acceleration causes the optical cavity length to change, thereby causing the intensity of the interference spot to change accordingly. The electrostatic feedback structure in the vertical direction is used to restore the mass block to its original position, realizing closed-loop detection of the acceleration signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A top view of the middle layer main structure of the present invention;

[0018] Figure 2 It is an overall side sectional view of the present invention;

[0019] Figure 3 A bottom view of the top structure of the present invention;

[0020] Figure 4 It is a top view of the underlying structure of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the accompanying drawings, and the words "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0022] like Figure 1 As shown, a three-axis grating accelerometer device based on an electrostatic feedback structure of this embodiment includes a top structure 24, a middle main structure 1 and a bottom structure 29, and the top structure 24, the middle main structure 1 and the bottom structure 29 are arranged from top to bottom to form a complete three-axis grating accelerometer structure. The middle-level main structure 1 includes an X-axis module 1-1, a Y-axis module 1-2, a Z-axis module 1-3, a bonding module 1-4 and a first bonding layer structure 23; the X-axis module 1-1 is located at the upper left corner of the middle-level main structure 1, the Y-axis module 1-2 is located at the lower right corner of the middle-level main structure 1, the X-axis module 1-1 and the Y-axis module 1-2 are arranged vertically, the Z-axis module 1-3 is located at the lower left corner of the middle-level main structure 1, the bonding module 1-4 is located at the upper right corner of the middle-level main structure 1, and the bonding electrodes of the first bonding layer structure 23 are distributed at the four corners of each module; the middle-level main structure 1 is a square, the X-axis module 1-1 and the Y-axis module 1-2 are completely consistent in structure, both are rectangular, the Z-axis module 1-3 and the bonding module 1-4 are arranged vertically, and the Z-axis module 1-3 and the bonding module 1-4 are arranged vertically. -4 is a square, the lower long side of the X-axis module 1-1 coincides with the upper side of the Z-axis module 1-3, the left long side of the Y-axis module 1-2 coincides with the right long side of the Z-axis module 1-3, the left long side of the bonding module 1-4 coincides with the right short side of the X-axis module 1-1, and the lower side coincides with the upper short side of the Y-axis module 1-2, and the lower surface of the first bonding layer structure 23 coincides with the upper surfaces of the X-axis module 1-1, the Y-axis module 1-2, the Z-axis module 1-3, and the bonding module 1-4; the X-axis module 1-1 is used to measure the acceleration in the X-axis direction, the Y-axis module 1-2 is used to measure the acceleration in the Y-axis direction, the Z-axis module 1-3 is used to measure the acceleration in the Z-axis direction, and the first bonding layer structure 23 is used to bond with the top structure 24.

[0023] The X-axis module 1-1 is composed of an X-axis annular outer frame 2, first and second X-axis annular outer elastic beams 3-1, 3-2, an X-axis annular connecting frame 4, first and second X-axis annular inner elastic beams 5-1, 5-2, an X-axis comb structure, an X-axis movable grating mass block 7, and first and second X-axis fixed grating mass blocks 8-1, 8-2; the first and second X-axis fixed grating mass blocks 8-1, 8-2 are located at the center of the X-axis movable grating mass block 7, and are symmetrically distributed about the center of the X-axis module 1-1. A large number of parallel equidistant grooves are engraved on the upper surfaces of the grating mass blocks 8-1 and 8-2 to form a grating part; the X-axis movable grating mass block 7 is located at the exact center of the X-axis module 1-1, and is equidistantly divided into five parts, the second and fourth parts are hollowed out, and the first, third and fifth parts are kept connected. A large number of parallel equidistant grooves are also engraved on the upper surface of the X-axis movable grating mass block 7 to form a grating part; the X-axis comb tooth structure is located on the left and right sides of the X-axis movable grating mass block 7, and the X-axis comb tooth structure consists of the first, second and third X-axis feedback comb teeth 6 on the left side of the X-axis movable grating mass block 7 -1, 6-2, 6-3, the fourth, fifth, and sixth X-axis feedback comb teeth 6-4, 6-5, and 6-6 on the right side of the X-axis movable grating mass block 7 are composed, and the feedback comb teeth on the left and right sides are evenly spaced. The feedback comb teeth are composed of a pair of fixed comb teeth and a movable comb tooth. The fixed comb teeth are symmetrically distributed on the upper and lower sides of the movable comb teeth, and a certain overlapping length is formed between the comb teeth, and the spacing between adjacent comb teeth is equal. The upper side is the driving comb tooth, and the lower side is the sensing comb tooth. The movable comb tooth is connected to the X-axis movable grating mass block 7, reflecting the X-axis movable grating mass block 7 The X-axis movable grating mass block 7 is supported on the X-axis ring connection frame 4 through the upper first X-axis ring inner elastic beam 5-1 and the lower second X-axis ring inner elastic beam 5-2. The internal structure of the X-axis ring connection frame 4 is supported on the X-axis ring outer frame 2 through the upper first X-axis ring outer elastic beam 3-1 and the lower second X-axis ring outer elastic beam 3-2 as a whole. The first and second X-axis ring outer elastic beams 3-1 and 3-2 are slightly longer than the first and second X-axis ring inner elastic beams 5-1 and 5-2. When the collimated laser beam passes through the top glass and irradiates the grating, a part of the light is directly reflected and forms a diffraction beam 1, and the other part of the incident light passes through the gap of the grating and is reflected back, and passes through the grating again to form a diffraction beam 2. The two diffracted beams will interfere and generate interference spots. When there is an X-axis acceleration input from the outside, the X-axis movable grating mass block 7 will be displaced by the inertial force, while the first and second X-axis fixed grating mass blocks will not change, thereby affecting the change of the spot intensity. At the same time, the X-axis movable grating mass block is controlled by the X-axis electrostatic feedback comb structure, so that the X-axis movable grating mass block 7 is always in a balanced position, and finally the closed-loop measurement of the X-axis acceleration is realized.

[0024] The Y-axis module 1-2 is composed of a Y-axis annular outer frame 9, a first and a second Y-axis annular outer elastic beams 10-1, 10-2, a Y-axis annular connecting frame 11, a first and a second Y-axis annular inner elastic beams 12-1, 12-2, a Y-axis comb structure, a Y-axis movable grating mass block 14, and a first and a second Y-axis fixed grating mass blocks 15-1, 15-2; the first and the second Y-axis fixed grating mass blocks 15-1, 15-2 are located at the inner center of the Y-axis movable grating mass block 14, and are symmetrically distributed about the center of the Y-axis module 1-2. A large number of parallel equidistant grooves are engraved on the upper surfaces of the fixed grating mass blocks 15-1 and 15-2 to form a grating part; the Y-axis movable grating mass block 14 is located at the exact center of the Y-axis module 1-2 and is equidistantly divided into five parts, the second and fourth parts are hollowed out, and the first, third and fifth parts are kept connected. A large number of parallel equidistant grooves are also engraved on the upper surface of the Y-axis movable grating mass block 14 to form a grating part; the Y-axis comb tooth structure is located on the upper and lower sides of the Y-axis movable grating mass block 14, and the Y-axis comb tooth structure consists of the first, second and third Y-axis feedback comb teeth 13- 1, 13-2, 13-3, the fourth, fifth, and sixth Y-axis feedback comb teeth 13-4, 13-5, and 13-6 below the Y-axis movable grating mass block 14 are composed, the feedback comb teeth on the upper and lower sides are evenly spaced, the feedback comb teeth are composed of a pair of fixed comb teeth and a movable comb tooth, the fixed comb teeth are symmetrically distributed on the left and right sides of the movable comb teeth, and a certain overlapping length is formed between the comb teeth, and the spacing between adjacent comb teeth is equal, the left side is the driving comb tooth, and the right side is the sensing comb tooth, the movable comb tooth is connected to the Y-axis movable grating mass block 14, and reflects the position of the Y-axis movable grating mass block 14 The Y-axis movable grating mass block 14 is supported on the Y-axis ring connection frame 11 by the first Y-axis ring inner elastic beam 12-1 on the left and the second Y-axis ring inner elastic beam 12-2 on the right. The internal structure of the Y-axis ring connection frame 11 is supported on the Y-axis ring outer frame 9 by the first Y-axis ring outer elastic beam 10-1 on the left and the second Y-axis ring outer elastic beam 10-2 on the right. The first and second Y-axis ring outer elastic beams 10-1 and 10-2 are slightly longer than the first and second Y-axis ring inner elastic beams 12-1 and 12-2. When the collimated laser beam passes through the top glass and irradiates the grating approximately vertically, a part of the light is directly reflected and forms a diffraction beam 1, and the other part of the incident light passes through the gap of the grating and is reflected back, and passes through the grating again to form a diffraction beam 2. The two diffracted beams will interfere and generate interference spots. When there is Y-axis acceleration input from the outside, the Y-axis movable grating mass block 14 will be displaced by the inertial force, while the first and second Y-axis fixed grating mass blocks will not change, thereby affecting the change of the spot intensity. At the same time, the Y-axis movable grating mass block 14 is controlled by the Y-axis electrostatic feedback comb structure, so that the Y-axis movable grating mass block 14 is always in a balanced position, and finally the closed-loop measurement of the Y-axis acceleration is realized.

[0025] The Z-axis module 1-3 is composed of a Z-axis annular outer frame 16, the first, second, third and fourth Z-axis U-shaped outer elastic beams 17-1, 17-2, 17-3 and 17-4, a Z-axis annular connecting frame 18, the first, second, third and fourth Z-axis U-shaped inner elastic beams 19-1, 19-2, 19-3 and 19-4, a Z-axis mass block 20, the first and second Z-axis metal electrodes 21-1 and 21-2, and a Z-axis inner reflective film 22; the Z-axis mass block 20 is a square and is located at the exact center of the Z-axis module 1-3, and the Z-axis inner reflective film 22 is a square and has a side length smaller than that of the Z-axis mass block 20. 0, and is located at the center of the upper surface of the Z-axis mass block 20. The first and second Z-axis metal electrodes 21-1 and 21-2 are ring-shaped, with an outer size slightly smaller than the Z-axis mass block 20 and an inner size slightly larger than the Z-axis inner reflective film 22. The first Z-axis metal electrode 21-1 is located at the center of the upper surface of the Z-axis mass block 20, and the second Z-axis metal electrode 21-2 is located at the center of the lower surface of the Z-axis mass block 20; the first Z-axis U-shaped inner elastic beam 19-1 is located above the Z-axis mass block 20, the second Z-axis U-shaped inner elastic beam 19-2 is located on the right of the Z-axis mass block 20, and the first Z-axis U-shaped inner elastic beam 19-1 is located on the right of the Z-axis mass block 20. The third Z-axis U-shaped inner elastic beam 19-3 is located below the Z-axis mass block 20, the fourth Z-axis U-shaped inner elastic beam 19-4 is located on the left of the Z-axis mass block 20, the Z-axis mass block 20 is supported on the Z-axis annular connecting frame 18 by the first, second, third and fourth Z-axis U-shaped inner elastic beams 19-1, 19-2, 19-3 and 19-4, the first Z-axis U-shaped outer elastic beam 17-1 is located above the Z-axis annular connecting frame 18, the second Z-axis U-shaped outer elastic beam 17-2 is located on the right of the Z-axis annular connecting frame 18, and the third Z-axis U-shaped outer elastic beam 17-3 is located Below the Z-axis ring connecting frame 18, the fourth Z-axis U-shaped outer elastic beam 17-4 is located on the left side of the Z-axis ring connecting frame 18. The internal structure of the Z-axis ring connecting frame 18 is supported on the Z-axis ring outer frame 16 as a whole through the first, second, third, and fourth Z-axis U-shaped outer elastic beams 17-1, 17-2, 17-3, and 17-4, wherein the first, second, third, and fourth Z-axis U-shaped outer elastic beams 17-1, 17-2, 17-3, and 17-4 are slightly longer than the first, second, third, and fourth Z-axis U-shaped inner elastic beams 19-1, 19-2, 19-3, and 19-4. When the collimated laser beam passes through the top glass and irradiates the grating approximately vertically, a part of the light is directly reflected and forms a diffraction beam 1, and another part of the incident light is reflected back after passing through the gap of the grating, and forms a diffraction beam 2 after passing through the grating again. The two diffracted beams will interfere and generate interference spots. When there is an external Z-axis acceleration input, the Z-axis mass block 20 will be affected by the inertial force, resulting in displacement along the Z-axis direction, thereby affecting the change of the spot intensity. At the same time, the closed-loop control of the Z-axis mass block 20 is achieved through the electrostatic feedback structure, so that the Z-axis mass block 20 is always in a balanced position, and finally the closed-loop measurement of the Z-axis acceleration is achieved.

[0026] The first bonding layer structure 23 includes first, second, third, fourth, fifth, sixth, seventh, eighth and ninth middle-layer bonding electrodes 23-1, 23-2, 23-3, 23-4, 23-5, 23-6, 23-7, 23-8 and 23-9. The first middle-layer bonding electrode 23-1 is located at the upper left corner of the upper surface of the X-axis module 1-1, the third middle-layer bonding electrode 23-3 is located at the upper right corner of the upper surface of the bonding module 1-4, the seventh middle-layer bonding electrode 23-7 is located at the lower left corner of the upper surface of the Z-axis module 1-3, the ninth middle-layer bonding electrode 23-9 is located at the lower right corner of the upper surface of the Y-axis module 1-2, and the centers of the fourth, fifth and sixth middle-layer bonding electrodes 23-4, 23-5 and 23-6 are located between the X-axis module 1-1 and the Z-axis module 1- 3, the centers of the second, fifth and eighth middle-layer bonding electrodes 23-2, 23-5 and 23-8 are located on the boundary line of the Y-axis module 1-2 and the Z-axis module 1-3, the first, fourth and seventh middle-layer bonding electrodes 23-1, 23-4 and 23-7, the second, fifth and eighth middle-layer bonding electrodes 23-2, 23-5 and 23-8 and the third, sixth and ninth middle-layer bonding electrodes 23-3, 23-6 and 23-9 are respectively located on the same vertical line, and the first, second and third middle-layer bonding electrodes 23-1, 23-2 and 23-3, the fourth, fifth and sixth middle-layer bonding electrodes 23-4, 23-5 and 23-6 and the seventh, eighth and ninth middle-layer bonding electrodes 23-7, 23-8 and 23-9 are respectively located on the same horizontal line.

[0027] like Figure 2As shown, the lower surface of the second bonding layer structure 28 of the top structure 24 completely overlaps with the upper surface of the first bonding layer structure 23 of the middle main structure 1, and the lower surface of the annular outer frame and the bonding modules 1-4 of the middle main structure 1 completely overlaps with the upper surface of the anchor layer of the bottom structure 29, forming a three-dimensional structure similar to a sandwich. In the top structure 24, the upper surface of the metal grating 26 overlaps with the lower surface of the top glass substrate 25, the metal grating 26 is directly opposite to the Z-axis inner reflective film 22 of the middle main structure 1 and there is a certain distance between the metal grating 26 and the Z-axis inner reflective film 22, the upper surface of the top metal electrode 27 overlaps with the lower surface of the top glass substrate 25, the top metal electrode 27 is directly opposite to the first Z-axis metal electrode 21-1 of the middle main structure 1 and there is a certain distance between the metal grating 26 and the first Z-axis metal electrode 21-1, the upper surface of the second bonding layer structure 28 overlaps with the lower surface of the top glass substrate 25, and the lower surface of the second bonding layer structure 28 overlaps with the upper surface of the first bonding layer structure 23.In the middle main structure 1, the left side is the X-axis module 1-1, the right side is the Z-axis module 1-3, the Y-axis module 1-2 is consistent with the X-axis module 1-1, and the X-axis module 1-1 is composed of the X-axis annular outer frame 2, the first X-axis annular outer elastic beam 3-1, the X-axis annular connecting frame 4, the first X-axis annular inner elastic beam 5-1, the X-axis movable grating mass block 7, the second X-axis annular inner elastic beam 5-2, the X-axis annular connecting frame 4, the second X-axis annular outer elastic beam 3-2, and the X-axis annular outer frame 2. The X-axis movable grating mass block 7 is located at the center of the X-axis module 1-1, and the left surface of the X-axis movable grating mass block 7 is connected to the first X-axis annular inner elastic beam 5-2. The right surface of the X-axis movable grating mass block 7 is connected to the second X-axis annular inner elastic beam 5-2, the inner surface of the X-axis annular connecting frame 4 is connected to the first and second X-axis annular inner elastic beams 5-1 and 5-2, the outer surface of the X-axis annular connecting frame 4 is connected to the first and second X-axis annular outer elastic beams 3-1 and 3-2, and the inner surface of the X-axis annular outer frame 2 is connected to the first and second X-axis annular outer elastic beams 3-1 and 3-2, forming a nested structure; the Z-axis module 1-3 is composed of a Z-axis annular outer frame 16, a first Z-axis U-shaped outer elastic beam 17-1, a Z-axis annular connecting frame 18, and a first Z-axis U The Z-axis U-shaped inner elastic beam 19-1, the Z-axis mass block 20, the third Z-axis U-shaped inner elastic beam 19-3, the Z-axis annular connecting frame 18, and the third Z-axis U-shaped outer elastic beam 17-3, the Z-axis mass block 20 is located at the center of the Z-axis module 1-3, the lower surface of the Z-axis inner reflective film 22 coincides with the upper surface of the Z-axis mass block 20 and is located at the center of the upper surface of the Z-axis mass block 20, the lower surface of the first Z-axis metal electrode 21-1 coincides with the upper surface of the Z-axis mass block 20 and is located at the center of the upper surface of the Z-axis mass block 20, the upper surface of the second Z-axis metal electrode 21-2 coincides with the upper surface of the Z-axis mass block 20 The lower surfaces overlap and are located at the center of the lower surface of the Z-axis mass block 20. The left surface of the Z-axis mass block 20 is connected to the first Z-axis U-shaped inner elastic beam 19-1, and the right surface of the Z-axis mass block 20 is connected to the third Z-axis U-shaped inner elastic beam 19-3. The inner surface of the Z-axis annular connecting frame 18 is connected to the first and third Z-axis U-shaped inner elastic beams 19-1 and 19-3. The outer surface of the Z-axis annular connecting frame 18 is connected to the first and third Z-axis U-shaped outer elastic beams 17-1 and 17-3. The inner surface of the Z-axis annular outer frame 16 is connected to the first and third Z-axis U-shaped outer elastic beams 17-1 and 17-3, forming a nested structure.In the bottom structure 29, the upper surface of the X-axis outer frame anchor point 31-1 coincides with the lower surface of the X-axis annular outer frame 2, the lower surface of the X-axis outer frame anchor point 31-1 coincides with the upper surface of the bottom glass substrate 30, the upper surface of the Z-axis outer frame anchor point 31-3 coincides with the lower surface of the Z-axis annular outer frame 16, the lower surface of the Z-axis outer frame anchor point 31-3 coincides with the upper surface of the bottom glass substrate 30, the lower surface of the bottom metal electrode coincides with the upper surface of the bottom glass substrate 30, and is directly below the second Z-axis metal electrode 21-2 and has a certain distance from the second Z-axis metal electrode 21-2. The lower surface of the peripheral electrode 39 coincides with the upper surface of the bottom glass substrate 30 and is located in the outer area of ​​the bottom glass substrate 30 beyond the middle main structure 1.

[0028] like Figure 3As shown, the top structure 24 is composed of a top glass substrate 25, a metal grating 26, a top metal electrode 27 and a second bonding layer structure 28. The top glass substrate 25 is square and has the same size as the middle main structure 1. The metal grating 26 is located directly above the Z-axis inner reflective film 22 and has the same size as the Z-axis inner reflective film 22. The top metal electrode 27 is annular and is located directly above the Z-axis mass block 20. The size is consistent with the first and second Z-axis metal electrodes 21-1 and 21-2. The metal grating 26 is located inside the top metal electrode 27, and the centers of the two coincide. The second bonding layer structure 28 includes the first, second, The third, fourth, fifth, sixth, seventh, eighth and ninth top layer bonding electrodes 28-1, 28-2, 28-3, 28-4, 28-5, 28-6, 28-7, 28-8 and 28-9 and the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth top layer bonding electrodes 28-1, 28-2, 28-3, 28-4, 28-5, 28-6, 28-7, 28-8 and 28-9 are respectively located above the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth middle layer bonding electrodes 23-1, 23-2, 23-3, 23-4, 23-5, 23-6, 23-7, 23-8 and 23-9. The bonding electrode 28-1 is located at the upper right corner of the upper surface of the top glass substrate 25, the third top bonding electrode 28-3 is located at the upper left corner of the upper surface of the top glass substrate 25, the seventh top bonding electrode 28-7 is located at the lower right corner of the upper surface of the top glass substrate 25, the ninth top bonding electrode 28-9 is located at the lower left corner of the upper surface of the top glass substrate 25, the centers of the fourth, fifth and sixth top bonding electrodes 28-4, 28-5 and 28-6 are located on the line corresponding to the boundary line of the X-axis module 1-1 and the Z-axis module 1-3 on the top glass substrate 25, the centers of the second, fifth and eighth top bonding electrodes 28-2, 28-5 and 28-8 are located on the Y-axis The boundary line between module 1-2 and Z-axis module 1-3 corresponds to the line of the top glass substrate 25, the first, fourth and seventh top bonding electrodes 28-1, 28-4 and 28-7, the second, fifth and eighth top bonding electrodes 28-2, 28-5 and 28-8 and the third, sixth and ninth top bonding electrodes 28-3, 28-6 and 28-9 are respectively located on the same vertical line, and the first, second and third top bonding electrodes 28-1, 28-2 and 28-3, the fourth, fifth and sixth top bonding electrodes 28-4, 28-5 and 28-6 and the seventh, eighth and ninth top bonding electrodes 28-7, 28-8 and 28-9 are respectively located on the same horizontal line.

[0029] like Figure 4As shown, the bottom structure 29 is composed of a bottom glass substrate 30, an anchor layer, first and second X-axis fixed grating mass block anchors 32-1, 32-2, first and second Y-axis fixed grating mass block anchors 33-1, 33-2, a bottom metal electrode 34, an X-axis driving electrode, an X-axis sensing electrode, a Y-axis driving electrode, a Y-axis sensing electrode, and a peripheral electrode 39. The bottom glass substrate 30 is a square, and the side length is slightly longer than the side length of the top glass substrate 25. The anchor layer includes an X-axis outer frame anchor 31-1, a Y-axis outer frame anchor 31-2, a Z-axis outer frame anchor 31-3, and a bonding module anchor 31-4. The outer size of the anchor layer is consistent with the size of the middle-layer main structure 1. The X-axis outer frame anchor 31-1, the Y-axis outer frame anchor 31-2, and the Z-axis outer frame anchor 31-3 are connected to the bonding module 31-4. The sizes of the outer frame anchor point 31-3 and the bonding module anchor point 31-4 are respectively consistent with the sizes of the X-axis annular outer frame 2, the Y-axis annular outer frame 9, the Z-axis annular outer frame 16, and the bonding module 1-4. The X-axis outer frame anchor point 31-1 is located directly below the X-axis annular outer frame 2 and its upper surface coincides with the lower surface of the X-axis annular outer frame 2. The Y-axis outer frame anchor point 31-2 is located directly below the Y-axis annular outer frame 9 and its upper surface coincides with the lower surface of the Y-axis annular outer frame 9. The Z-axis outer frame anchor point 31-3 is located directly below the Z-axis annular outer frame 16 and its upper surface coincides with the lower surface of the Z-axis annular outer frame 16. The bonding module anchor point 31-4 is located directly below the bonding module 1-4 and its upper surface coincides with the lower surface of the bonding module 1-4. The first and second X-axis fixed grating mass block anchor points The sizes of the first and second X-axis fixed grating mass blocks 32-1 and 32-2 are consistent with the sizes of the first and second X-axis fixed grating mass blocks 8-1 and 8-2. The first and second X-axis fixed grating mass block anchor points 32-1 and 32-2 are respectively located directly below the first and second X-axis fixed grating mass blocks 8-1 and 8-2, and the upper surfaces coincide with the lower surfaces of the first and second X-axis fixed grating mass blocks 8-1 and 8-2. The sizes of the first and second Y-axis fixed grating mass blocks anchor points 33-1 and 33-2 are consistent with the sizes of the first and second Y-axis fixed grating mass blocks 15-1 and 15-2. The first and second Y-axis fixed grating mass blocks anchor points 33-1 and 33-2 are respectively located directly below the first and second Y-axis fixed grating mass blocks 15-1 and 15-2, and the upper surfaces coincide with the lower surfaces of the first and second Y-axis fixed grating mass blocks. The lower surfaces of the two Y-axis fixed grating quality blocks 15-1 and 15-2 overlap, the size of the bottom metal electrode is consistent with the size of the second Z-axis metal electrode 21-2, the bottom metal electrode is located directly below the second Z-axis metal electrode 21-2 and there is a certain distance, the X-axis driving electrodes include the first, second, third, fourth, fifth and sixth X-axis driving electrodes 35-1, 35-2, 35-3, 35-4, 35-5 and 35-6, the first, second, third, fourth, fifth and sixth X-axis driving electrodes 35-1, 35-2, 35-3, 35-4, 35-5 and 35-6 are respectively located directly below the driving comb teeth of the first, second, third, fourth, fifth and sixth X-axis feedback comb teeth 6-1, 6-2, 6-3, 6-4, 6-5 and 6-6,The X-axis sensing electrodes include first, second, third, fourth, fifth, and sixth X-axis sensing electrodes 36-1, 36-2, 36-3, 36-4, 36-5, and 36-6, which are respectively located directly below the sensing comb teeth of the first, second, third, fourth, fifth, and sixth X-axis feedback comb teeth 6-1, 6-2, 6-3, 6-4, 6-5, and 6-6, and the Y-axis driving electrodes include first, second, third, fourth, fifth, and sixth Y-axis driving electrodes 37-1, 37-2, 37-3, 37-4, 37-5, and 37-6, and the first, second, third, fourth, fifth, and sixth Y-axis driving electrodes 37-3, 37-4, 37-5, and 37-6. 7-1, 37-2, 37-3, 37-4, 37-5, 37-6 are respectively located directly below the driving comb teeth of the first, second, third, fourth, fifth, and sixth Y-axis feedback comb teeth 13-1, 13-2, 13-3, 13-4, 13-5, and 13-6, the Y-axis sensing electrodes include the first, second, third, fourth, fifth, and sixth Y-axis sensing electrodes 38-1, 38-2, 38-3, 38-4, 38-5, and 38-6, the first, second, third, fourth, fifth, and sixth Y-axis sensing electrodes 38-1, 38-2, 38-3, 38-4, 38-5, and 38-6 are respectively located at the first, second, third, fourth, fifth, and sixth Y-axis feedback comb teeth 13-1, 13-2, 13-3, 13-4, The peripheral electrodes 39 include first, second, third, fourth, fifth, sixth, seventh and eighth peripheral electrodes 39-1, 39-2, 39-3, 39-4, 39-5, 39-6, 39-7 and 39-8. The peripheral electrodes 39 are located outside the anchor layer on the upper surface of the bottom glass substrate 30. The first peripheral electrode 39-1 is connected to the first, second and third X-axis sensing electrodes 36-1, 36-2 and 36-3 through a wire. The second peripheral electrode 39-2 is connected to the first, second and third X-axis driving electrodes 35-1, 35-2 and 35-3 through a wire. The third peripheral electrode 39-3 is connected to the fourth, fifth and sixth X-axis sensing electrodes 36-1, 36-2 and 36-3 through a wire. 6-4, 36-5, 36-6, the fourth peripheral electrode 39-4 is connected to the fourth, fifth, and sixth X-axis driving electrodes 35-4, 35-5, and 35-6 through a wire, the fifth peripheral electrode 39-5 is connected to the first, second, and third Y-axis sensing electrodes 38-1, 38-2, and 38-3 through a wire, the sixth peripheral electrode 39-6 is connected to the first, second, and third Y-axis driving electrodes 37-1, 37-2, and 37-3 through a wire, the seventh peripheral electrode 39-7 is connected to the fourth, fifth, and sixth Y-axis sensing electrodes 38-4, 38-5, and 38-6 through a wire, and the eighth peripheral electrode 39-8 is connected to the fourth, fifth, and sixth Y-axis driving electrodes 37-4, 37-5, and 37-6 through a wire.

[0030] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above technical features.

Claims

1. A three-axis grating accelerometer device based on an electrostatic feedback structure, characterized in that: The invention comprises a top structure (24), a middle main structure (1) and a bottom structure (29), wherein the top structure (24), the middle main structure (1) and the bottom structure (29) are arranged from top to bottom to form a complete three-axis grating accelerometer structure; wherein the middle main structure (1) comprises an X-axis module (1-1), a Y-axis module (1-2), a Z-axis module (1-3), a bonding module (1-4) and a first bonding layer structure (23); the X-axis module (1-1) is located at The Y-axis module (1-2) is located at the upper left corner of the middle main structure (1), the X-axis module (1-1) and the Y-axis module (1-2) are arranged vertically, the Z-axis module (1-3) is located at the lower left corner of the middle main structure (1), the bonding module (1-4) is located at the upper right corner of the middle main structure (1), and the bonding electrodes of the first bonding layer structure (23) are distributed at the four corners of each module; the middle main structure (1) is a square, the X-axis module (1-1) and the Y-axis module (1-2) are arranged vertically, the Z-axis module (1-3) is located at the lower left corner of the middle main structure (1), and the bonding module (1-4) is located at the upper right corner of the middle main structure (1). The module (1-1) and the Y-axis module (1-2) are identical in structure and are both rectangular. The Z-axis module (1-3) and the bonding module (1-4) are square. The lower long side of the X-axis module (1-1) coincides with the upper side of the Z-axis module (1-3). The left long side of the Y-axis module (1-2) coincides with the right long side of the Z-axis module (1-3). The left long side of the bonding module (1-4) coincides with the right short side of the X-axis module (1-1). The lower long side coincides with the right short side of the Y-axis module (1-2). The upper short sides overlap, and the lower surface of the first bonding layer structure (23) overlaps with the upper surfaces of the X-axis module (1-1), the Y-axis module (1-2), the Z-axis module (1-3), and the bonding module (1-4); the X-axis module (1-1) is used to measure the acceleration in the X-axis direction, the Y-axis module (1-2) is used to measure the acceleration in the Y-axis direction, the Z-axis module (1-3) is used to measure the acceleration in the Z-axis direction, and the first bonding layer structure (23) is used to bond with the top structure (24);The X-axis module (1-1) is composed of an X-axis annular outer frame (2), first and second X-axis annular outer elastic beams (3-1, 3-2), an X-axis annular connecting frame (4), first and second X-axis annular inner elastic beams (5-1, 5-2), an X-axis comb structure, an X-axis movable grating mass block (7), and first and second X-axis fixed grating mass blocks; the first and second X-axis fixed grating mass blocks (8-1, 8-2) are located at the center of the X-axis movable grating mass block (7) and are symmetrically distributed about the center of the X-axis module (1-1); a large number of Parallel equidistant grooves form the grating part; the X-axis movable grating mass block (7) is located at the exact center of the X-axis module (1-1), and is equidistantly divided into five parts, the second and fourth parts are hollowed out, and the first, third and fifth parts are kept connected. A large number of parallel equidistant grooves are also engraved on the upper surface of the X-axis movable grating mass block (7) to form the grating part; the X-axis comb tooth structure is located on the left and right sides of the X-axis movable grating mass block (7), and the X-axis comb tooth structure consists of the first, second and third X-axis feedback comb teeth (6-1, 6-2, 6-3) on the left side of the X-axis movable grating mass block (7), and the fourth, fifth and sixth X-axis feedback comb teeth (6-4, The feedback comb teeth on the left and right sides are evenly spaced, the feedback comb teeth are composed of a pair of fixed comb teeth and a movable comb tooth, the fixed comb teeth are symmetrically distributed on the upper and lower sides of the movable comb teeth, and a certain overlapping length is formed between the comb teeth and the spacing between adjacent comb teeth is equal, the upper side is the driving comb teeth, and the lower side is the sensing comb teeth, the movable comb teeth are connected to the X-axis movable grating mass block (7), and reflect the displacement of the X-axis movable grating mass block (7); the X-axis movable grating mass block (7) is supported on the X-axis annular connection frame (4) through the upper first X-axis annular inner elastic beam (5-1) and the lower second X-axis annular inner elastic beam (5-2). ), the internal structure of the X-axis annular connecting frame (4) is taken as a whole, and is then supported on the X-axis annular outer frame (2) by the upper first X-axis annular outer elastic beam (3-1) and the lower second X-axis annular outer elastic beam (3-2), wherein the first and second X-axis annular outer elastic beams (3-1, 3-2) are slightly longer than the first and second X-axis annular inner elastic beams (5-1, 5-2); when the collimated laser beam passes through the top glass and irradiates the grating, a part of the light is directly reflected and forms a diffraction beam 1, and another part of the incident light passes through the gap of the grating and is reflected back, and passes through the grating again to form a diffraction beam 2;The two diffracted light beams interfere with each other to generate interference spots. When an external X-axis acceleration is input, the X-axis movable grating mass block (7) is displaced by the inertial force, while the first and second X-axis fixed grating mass blocks (8-1, 8-2) do not change, thereby affecting the change of the intensity of the light spots. At the same time, the X-axis movable grating mass block (7) is controlled by an X-axis electrostatic feedback comb structure, so that the X-axis movable grating mass block (7) is always in a balanced position, and finally a closed-loop measurement of the X-axis acceleration is achieved. Top layer structure The structure (24) is composed of a top glass substrate (25), a metal grating (26), a top metal electrode (27) and a second bonding layer structure (28), and the bottom structure (29) is composed of a bottom glass substrate (30), an anchor layer, first and second X-axis fixed grating mass block anchors (32-1, 32-2), first and second Y-axis fixed grating mass block anchors (33-1, 33-2), bottom metal electrodes, X-axis drive electrodes, X-axis sensing electrodes, Y-axis drive electrodes, Y-axis sensing electrodes, and peripheral electrodes (39).

2. The three-axis grating accelerometer device based on electrostatic feedback structure according to claim 1, characterized in that: The Y-axis module (1-2) is composed of a Y-axis annular outer frame (9), first and second Y-axis annular outer elastic beams (10-1, 10-2), a Y-axis annular connecting frame (11), first and second Y-axis annular inner elastic beams (12-1, 12-2), a Y-axis comb structure, a Y-axis movable grating mass block (14), and first and second Y-axis fixed grating mass blocks (15-1, 15-2); the first and second Y-axis fixed grating mass blocks (15-1, 15-2) are located at the inner center of the Y-axis movable grating mass block (14) and are symmetrically distributed up and down about the center of the Y-axis module (1-2); a large number of parallel equidistant grooves are engraved on the upper surfaces of the first and second Y-axis fixed grating mass blocks (15-1, 15-2) to form a grating portion The Y-axis movable grating mass block (14) is located at the exact center of the Y-axis module (1-2) and is equidistantly divided into five parts. The second and fourth parts are hollowed out, and the first, third and fifth parts are kept connected. A large number of parallel equidistant grooves are also engraved on the upper surface of the Y-axis movable grating mass block (14) to form a grating part. The Y-axis comb tooth structure is located on the upper and lower sides of the Y-axis movable grating mass block (14). The Y-axis comb tooth structure consists of the first, second and third Y-axis feedback comb teeth (13-1, 13-2, 13-3) above the Y-axis movable grating mass block (14) and the fourth, fifth and sixth Y-axis feedback comb teeth (13-4, 13-5, 13-6) below the Y-axis movable grating mass block (14). The feedback comb teeth on the upper and lower sides are equidistantly distributed, and the feedback comb teeth are composed of a pair of fixed The invention is composed of a fixed comb tooth and a movable comb tooth, wherein the fixed comb teeth are symmetrically distributed on the left and right sides of the movable comb teeth, and a certain overlapping length is formed between the comb teeth, and the spacing between adjacent comb teeth is equal. The left side is the driving comb tooth, and the right side is the sensing comb tooth. The movable comb tooth is connected to the Y-axis movable grating mass block (14) to reflect the displacement of the Y-axis movable grating mass block (14); the Y-axis movable grating mass block (14) is supported on the Y-axis ring connection frame (11) through the first Y-axis ring inner elastic beam (12-1) located on the left and the second Y-axis ring inner elastic beam (12-2) located on the right. The internal structure of the Y-axis ring connection frame (11) is taken as a whole, and then through the first Y-axis ring outer elastic beam (10-1) on the left and the second Y-axis ring outer elastic beam (10-2) on the right. The annular outer elastic beam (10-2) is supported on the Y-axis annular outer frame (9), wherein the first and second Y-axis annular outer elastic beams (10-1, 10-2) are longer than the first and second Y-axis annular inner elastic beams (12-1, 12-2); when the collimated laser beam passes through the top glass and irradiates the grating approximately vertically, a part of the light is directly reflected and forms a diffraction beam 1, and another part of the incident light passes through the gap of the grating and is reflected back, and passes through the grating again to form a diffraction beam 2; the two diffraction beams interfere and generate interference spots, and when there is an external Y-axis acceleration input, the Y-axis movable grating mass block (14) is displaced by the inertial force, while the first and second Y-axis fixed grating mass blocks do not change.Thus, the intensity of the light spot is changed; at the same time, the Y-axis movable grating mass block (14) is controlled by the Y-axis electrostatic feedback comb structure, so that the Y-axis movable grating mass block (14) is always in a balanced position, and finally the closed-loop measurement of the Y-axis acceleration is realized; the Z-axis module (1-3) is composed of a Z-axis annular outer frame (16), first, second, third, and fourth Z-axis U-shaped outer elastic beams (17-1, 17-2, 17-3, and 17-4), a Z-axis annular connecting frame (18), first, second, third, and fourth Z-axis U-shaped inner elastic beams (19-1, 19-2, 19-3, and 19-4), a Z-axis mass block (20), first and second Z-axis metal electrodes (21-1 and 21-2), and a Z-axis inner reflective film (22); the Z-axis mass block (20) is a square and is located at the exact center of the Z-axis module (1-3); the Z-axis inner reflective film (22) is a square and has a side length that is smaller than the side length of the Z-axis mass block (20) and is located at the center of the upper surface of the Z-axis mass block (20); the first and second Z-axis metal electrodes (21-1, 21-2) are ring-shaped and have an outer size that is smaller than the Z-axis mass block (20) and an inner size that is slightly larger than the Z-axis inner reflective film (22); the first Z-axis metal electrode (21-1) is located at the center of the upper surface of the Z-axis mass block (20) and the second Z-axis metal electrode (21-2) is located at the center of the lower surface of the Z-axis mass block (20); the first Z-axis U-shaped inner elastic beam (19-1) is located above the Z-axis mass block (20) and the second Z-axis U-shaped inner elastic beam (19-2) is located at the center of the lower surface of the Z-axis mass block (20); The beam (19-2) is located on the right side of the Z-axis mass block (20), the third Z-axis U-shaped inner elastic beam (19-3) is located below the Z-axis mass block (20), the fourth Z-axis U-shaped inner elastic beam (19-4) is located on the left side of the Z-axis mass block (20), the Z-axis mass block (20) is supported on the Z-axis annular connection frame (18) through the first, second, third and fourth Z-axis U-shaped inner elastic beams (19-1, 19-2, 19-3 and 19-4), the first Z-axis U-shaped outer elastic beam (17-1) is located above the Z-axis annular connection frame (18), the second Z-axis U-shaped outer elastic beam (17-2) is located on the right side of the Z-axis annular connection frame (18), and the third Z-axis U-shaped outer elastic beam (17-3) is located above the Z-axis annular connection frame (18). (18), the fourth Z-axis U-shaped outer elastic beam (17-4) is located on the left side of the Z-axis annular connecting frame (18), and the internal structure of the Z-axis annular connecting frame (18) is supported on the Z-axis annular outer frame (16) by the first, second, third and fourth Z-axis U-shaped outer elastic beams (17-1, 17-2, 17-3, 17-4), wherein the first, second, third and fourth Z-axis U-shaped outer elastic beams (17-1, 17-2, 17-3, 17-4) are longer than the first, second, third and fourth Z-axis U-shaped inner elastic beams (19-1, 19-2, 19-3, 19-4); when the collimated laser beam passes through the top glass and irradiates the grating approximately vertically, a part of the light is directly reflected and forms a diffraction beam 1,Another part of the incident light is reflected back after passing through the gap of the grating, and forms a diffraction beam 2 after passing through the grating again; the two diffraction beams interfere with each other to generate an interference light spot, and when there is an external Z-axis acceleration input, the Z-axis mass block (20) is affected by the inertial force, resulting in a displacement along the Z-axis direction, thereby affecting the change of the light spot intensity; at the same time, the Z-axis mass block (20) is controlled in a closed loop through an electrostatic feedback structure, so that the Z-axis mass block (20) is always in a balanced position, and finally a closed-loop measurement of the Z-axis acceleration is achieved; the first bonding layer structure (23) includes first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth middle-layer bonding electrodes (23-1, 23-2, 23-3, 23-4, 23-5 , 23-6, 23-7, 23-8, 23-9), the first middle-layer bonding electrode (23-1) is located at the upper left corner of the upper surface of the X-axis module (1-1), the third middle-layer bonding electrode (23-3) is located at the upper right corner of the upper surface of the bonding module (1-4), the seventh middle-layer bonding electrode (23-7) is located at the lower left corner of the upper surface of the Z-axis module (1-3), the ninth middle-layer bonding electrode (23-9) is located at the lower right corner of the upper surface of the Y-axis module (1-2), the centers of the fourth, fifth, and sixth middle-layer bonding electrodes (23-4, 23-5, 23-6) are located on the boundary line between the X-axis module (1-1) and the Z-axis module (1-3), the second, fifth, and eighth middle-layer bonding electrodes (23-2, 23-5, The center of the top structure (23-8) is located on the boundary line between the Y-axis module (1-2) and the Z-axis module (1-3); the first, fourth and seventh middle-layer bonding electrodes (23-1, 23-4 and 23-7), the second, fifth and eighth middle-layer bonding electrodes (23-2, 23-5 and 23-8) and the third, sixth and ninth middle-layer bonding electrodes (23-3, 23-6 and 23-9) are respectively located on the same vertical line; the first, second and third middle-layer bonding electrodes (23-1, 23-2 and 23-3), the fourth, fifth and sixth middle-layer bonding electrodes (23-4, 23-5 and 23-6) and the seventh, eighth and ninth middle-layer bonding electrodes (23-7, 23-8 and 23-9) are respectively located on the same horizontal line; The lower surface of the second bonding layer structure (28) of the middle layer main structure (1) is completely overlapped with the upper surface of the first bonding layer structure (23) of the middle layer main structure (1), and the lower surface of the annular outer frame and the bonding module (1-4) of the middle layer main structure (1) is completely overlapped with the upper surface of the anchor layer of the bottom layer structure (29), forming a three-dimensional structure similar to a sandwich; in the top layer structure (24), the upper surface of the metal grating (26) is overlapped with the lower surface of the top layer glass substrate (25), the metal grating (26) is directly opposite to the Z-axis inner layer reflection film (22) of the middle layer main structure (1) and there is a spacing of 100µm between the metal grating (26) and the Z-axis inner layer reflection film (22), and the upper surface of the top metal electrode (27) is overlapped with the lower surface of the top layer glass substrate (25),The top metal electrode (27) is directly opposite to the first Z-axis metal electrode (21-1) of the middle main structure (1) and has a spacing of 100 µm between the first Z-axis metal electrode (21-1). The upper surface of the second bonding layer structure (28) overlaps with the lower surface of the top glass substrate (25). The lower surface of the second bonding layer structure (28) overlaps with the upper surface of the first bonding layer structure (23). In the middle main structure (1), the left side is X The Y-axis module (1-2) is constructed in the same manner as the X-axis module (1-1). The X-axis module (1-1) includes an X-axis annular outer frame (2), a first X-axis annular outer elastic beam (3-1), an X-axis annular connecting frame (4), a first X-axis annular inner elastic beam (5-1), an X-axis movable grating mass block (7), a second X-axis annular inner elastic beam (5-2), an X-axis annular connecting frame (4), a second X-axis annular outer elastic beam (3-2), and an X-axis annular outer frame (2). The X-axis movable grating mass block (7) is located at the center of the X-axis module (1-1). The left surface of the X-axis movable grating mass block (7) is connected to the first X-axis annular inner elastic beam (5-1), the right surface of the X-axis movable grating mass block (7) is connected to the second X-axis annular inner elastic beam (5-2), the inner surface of the X-axis annular connecting frame (4) is connected to the first and second X-axis annular inner elastic beams (5-1, 5-2), the outer surface of the X-axis annular connecting frame (4) is connected to the first and second X-axis annular outer elastic beams (3-1, 3-2), and the inner surface of the X-axis annular outer frame (2) is connected to the first and second X-axis annular outer elastic beams (3-1, 3-2), forming a ring-nested structure; the Z-axis module (1-3) is connected from left to right. On the right are, in order, a Z-axis annular outer frame (16), a first Z-axis U-shaped outer elastic beam (17-1), a Z-axis annular connecting frame (18), a first Z-axis U-shaped inner elastic beam (19-1), a Z-axis mass block (20), a third Z-axis U-shaped inner elastic beam (19-3), a Z-axis annular connecting frame (18), and a third Z-axis U-shaped outer elastic beam (17-3); the Z-axis mass block (20) is located at the center of the Z-axis module (1-3); the lower surface of the Z-axis inner reflective film (22) overlaps with the upper surface of the Z-axis mass block (20) and is located at the center of the upper surface of the Z-axis mass block (20); the first Z-axis metal electrode (2 The lower surface of the Z-axis metal electrode (21-1) overlaps with the upper surface of the Z-axis mass block (20) and is located at the center of the upper surface of the Z-axis mass block (20); the upper surface of the second Z-axis metal electrode (21-2) overlaps with the lower surface of the Z-axis mass block (20) and is located at the center of the lower surface of the Z-axis mass block (20); the left surface of the Z-axis mass block (20) is connected to the first Z-axis U-shaped inner elastic beam (19-1); the right surface of the Z-axis mass block (20) is connected to the third Z-axis U-shaped inner elastic beam (19-3); and the inner surface of the Z-axis annular connection frame (18) is connected to the first and third Z-axis U-shaped inner elastic beams (19-1, 19-3).The outer surface of the Z-axis annular connection frame (18) is connected to the first and third Z-axis U-shaped outer elastic beams (17-1, 17-3), and the inner surface of the Z-axis annular outer frame (16) is connected to the first and third Z-axis U-shaped outer elastic beams (17-1, 17-3), forming a ring-nested structure; in the bottom structure (29), the upper surface of the X-axis outer frame anchor point (31-1) coincides with the lower surface of the X-axis annular outer frame (2), the lower surface of the X-axis outer frame anchor point (31-1) coincides with the upper surface of the bottom glass substrate (30), the upper surface of the Z-axis outer frame anchor point (31-3) coincides with the lower surface of the Z-axis annular outer frame (16), the lower surface of the Z-axis outer frame anchor point (31-3) coincides with the upper surface of the bottom glass substrate (30), and the lower surface of the bottom metal electrode coincides with the bottom The top glass substrate (25) is square and has the same size as the middle main structure (1). The metal grating (26) is located directly above the Z-axis inner reflective film (22) and has the same size as the Z-axis inner reflective film (22). The top metal electrode (27) is annular and is located directly above the Z-axis mass block (20) and has the same size as the first and second Z-axis metal electrodes (21-2). -1, 21-2) are consistent, the metal grating (26) is located inside the top metal electrode (27), and the centers of the two coincide, the second bonding layer structure (28) includes the first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth top bonding electrodes (28-1, 28-2, 28-3, 28-4, 28-5, 28-6, 28-7, 28-8, 28-9), the first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth top bonding electrodes (28-1, 28-2, 28-3, 28-4, 28-5, 28-6, 28-7, 28-8, 28-9) are respectively located on the first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth middle bonding electrodes (23-1, 23-2, 23-3, The top glass substrate (25) is directly above the top glass substrate (23-4, 23-5, 23-6, 23-7, 23-8, 23-9), the first top-layer bonding electrode (28-1) is located at the upper right corner of the upper surface of the top glass substrate (25), the third top-layer bonding electrode (28-3) is located at the upper left corner of the upper surface of the top glass substrate (25), the seventh top-layer bonding electrode (28-7) is located at the lower right corner of the upper surface of the top glass substrate (25), the ninth top-layer bonding electrode (28-9) is located at the lower left corner of the upper surface of the top glass substrate (25), the centers of the fourth, fifth, and sixth top-layer bonding electrodes (28-4, 28-5, 28-6) are located on a line corresponding to the boundary line of the X-axis module (1-1) and the Z-axis module (1-3) on the top glass substrate (25),The centers of the second, fifth and eighth top-layer bonding electrodes (28-2, 28-5 and 28-8) are located on a line corresponding to the top glass substrate (25) at the boundary line between the Y-axis module (1-2) and the Z-axis module (1-3); the first, fourth and seventh top-layer bonding electrodes (28-1, 28-4 and 28-7), the second, fifth and eighth top-layer bonding electrodes (28-2, 28-5 and 28-8) and the third, sixth and ninth top-layer bonding electrodes (28-3, 28-6 and 28-9) are respectively located on the same vertical line; the first, second and third top-layer bonding electrodes (28-1, 28-2 and 28-3), the fourth, fifth and sixth top-layer bonding electrodes (28-4, 28-5 and 28-6) and the seventh, eighth and ninth top-layer bonding electrodes (28-7 , 28-8, 28-9) are respectively located on the same horizontal line; the bottom glass substrate (30) is a square, and the side length is longer than the side length of the top glass substrate (25); the anchor point layer includes an X-axis outer frame anchor point (31-1), a Y-axis outer frame anchor point (31-2), a Z-axis outer frame anchor point (31-3), and a bonding module anchor point (31-4); the outer size of the anchor point layer is consistent with the size of the middle layer main structure (1); the sizes of the X-axis outer frame anchor point (31-1), the Y-axis outer frame anchor point (31-2), the Z-axis outer frame anchor point (31-3), and the bonding module anchor point (31-4) are respectively consistent with the sizes of the X-axis annular outer frame (2), the Y-axis annular outer frame (9), the Z-axis annular outer frame (16), and the bonding module (1-4); the X-axis outer frame The anchor point (31-1) is located directly below the X-axis annular outer frame (2) and its upper surface coincides with the lower surface of the X-axis annular outer frame (2); the Y-axis outer frame anchor point (31-2) is located directly below the Y-axis annular outer frame (9) and its upper surface coincides with the lower surface of the Y-axis annular outer frame (9); the Z-axis outer frame anchor point (31-3) is located directly below the Z-axis annular outer frame (16) and its upper surface coincides with the lower surface of the Z-axis annular outer frame (16); the bonding module anchor point (31-4) is located directly below the bonding module (1-4) and its upper surface coincides with the lower surface of the bonding module (1-4); the sizes of the first and second X-axis fixed grating mass block anchor points (32-1, 32-2) are consistent with the sizes of the first and second X-axis fixed grating mass blocks (8-1, 8-2); The first and second X-axis fixed grating mass block anchor points (32-1, 32-2) are respectively located directly below the first and second X-axis fixed grating mass blocks (8-1, 8-2) and their upper surfaces coincide with the lower surfaces of the first and second X-axis fixed grating mass blocks (8-1, 8-2); the sizes of the first and second Y-axis fixed grating mass block anchor points (33-1, 33-2) are consistent with the sizes of the first and second Y-axis fixed grating mass blocks (15-1, 15-2); the first and second Y-axis fixed grating mass block anchor points (33-1, 33-2) are respectively located directly below the first and second Y-axis fixed grating mass blocks (15-1, 15-2) and their upper surfaces coincide with the lower surfaces of the first and second Y-axis fixed grating mass blocks (15-1, 15-2);The size of the bottom metal electrode is consistent with that of the second Z-axis metal electrode (21-2), the bottom metal electrode is located directly below the second Z-axis metal electrode (21-2) and there is a certain interval between them, the X-axis driving electrodes include the first, second, third, fourth, fifth and sixth X-axis driving electrodes (35-1, 35-2, 35-3, 35-4, 35-5 and 35-6), the first, second, third, fourth, fifth and sixth X-axis driving electrodes (35-1, 35-2, 35-3, 35-4, 35-5 and 35-6) are located directly below the driving comb teeth of the first, second, third, fourth, fifth and sixth X-axis feedback comb teeth (6-1, 6-2, 6-3, 6-4, 6-5 and 6-6) respectively, and the X-axis sensing electrodes include the first, second, third, fourth, fifth and sixth X-axis driving electrodes (35-1, 35-2, 35-3, 35-4, 35-5 and 35-6). The fourth, fifth and sixth X-axis sensing electrodes (36-1, 36-2, 36-3, 36-4, 36-5 and 36-6), the first, second, third, fourth, fifth and sixth X-axis sensing electrodes (36-1, 36-2, 36-3, 36-4, 36-5 and 36-6) are respectively located directly below the sensing comb teeth of the first, second, third, fourth, fifth and sixth X-axis feedback comb teeth (6-1, 6-2, 6-3, 6-4, 6-5 and 6-6), the Y-axis driving electrodes include the first, second, third, fourth, fifth and sixth Y-axis driving electrodes (37-1, 37-2, 37-3, 37-4, 37-5 and 37-6), the first, second, third, fourth, fifth and sixth Y-axis driving electrodes (37-1, 37-2, 37-3, 37-4, The Y-axis sensing electrodes include the first, second, third, fourth, fifth and sixth Y-axis sensing electrodes (38-1, 38-2, 38-3, 38-4, 38-5 and 38-6), and the first, second, third, fourth, fifth and sixth Y-axis sensing electrodes (38-1, 38-2, 38-3, 38-4, 38-5 and 38-6) are respectively located directly below the driving comb teeth of the first, second, third, fourth, fifth and sixth Y-axis feedback comb teeth (13-1, 13-2, 13-3, 13-4, 13-5 and 13-6); the periphery The electrodes (39) include first, second, third, fourth, fifth, sixth, seventh and eighth peripheral electrodes (39-1, 39-2, 39-3, 39-4, 39-5, 39-6, 39-7 and 39-8), the peripheral electrodes (39) are located in the area outside the anchor point layer on the upper surface of the bottom glass substrate (30), the first peripheral electrode (39-1) is connected to the first, second and third X-axis sensing electrodes (36-1, 36-2 and 36-3) through a wire, the second peripheral electrode (39-2) is connected to the first, second and third X-axis driving electrodes (35-1, 35-2 and 35-3) through a wire, the third peripheral electrode (39-3) is connected to the fourth, fifth and sixth X-axis sensing electrodes (36-4, 36-5 and 36-6) through a wire,The fourth peripheral electrode (39-4) is connected to the fourth, fifth and sixth X-axis driving electrodes (35-4, 35-5 and 35-6) through a wire, the fifth peripheral electrode (39-5) is connected to the first, second and third Y-axis sensing electrodes (38-1, 38-2 and 38-3) through a wire, the sixth peripheral electrode (39-6) is connected to the first, second and third Y-axis driving electrodes (37-1, 37-2 and 37-3) through a wire, the seventh peripheral electrode (39-7) is connected to the fourth, fifth and sixth Y-axis sensing electrodes (38-4, 38-5 and 38-6) through a wire, and the eighth peripheral electrode (39-8) is connected to the fourth, fifth and sixth Y-axis driving electrodes (37-4, 37-5 and 37-6) through a wire.

Images