Single-chip triaxial MEMS (Micro Electro Mechanical System) gyroscope

Abstract

The utility model discloses a single-chip triaxial MEMS (Micro Electro Mechanical System) gyroscope which comprises four vibration mass blocks, a spring beam, a surface doped sensing beam, a side doped sensing beam, a driving electrode and a detection electrode, force sensing resistors are formed on the surfaces of the surface doped sensing beams through doping, force sensing resistors are formed on the side faces of the side face doped sensing beams through doping, and in-plane and out-of-plane deformation of the sensing beams caused by the Coriolis force is detected through changes of the force sensing resistors of the surface doped sensing beams and the force sensing resistors of the side face doped sensing beams respectively. Therefore, angular velocities in different axial directions can be detected. The three-axis angular velocity measurement is realized in a single chip, and compared with a capacitive MEMS gyroscope, the three-axis angular velocity measurement device is simple in structure and relatively low in processing precision requirement, and has certain practicability.

Description

Technical Field

[0001] The utility model relates to the technical field of MEMS gyroscopes, in particular to a three-axis MEMS gyroscope. Background Art

[0002] The traditional MEMS three-axis gyroscope mechanical structure consists of three independent X, Y, and Z single-axis gyroscopes. Each single-axis gyroscope mechanical structure includes an independent mass block, a drive structure, and a detection structure. In addition, the corresponding ASIC circuit needs to use three sets of independent drive circuits to drive them separately, which makes the three-axis gyroscope larger in size.

[0003] At present, most MEMS gyroscopes are mainly based on electrostatic excitation and capacitance detection. Electrostatic excitation has relatively high requirements for microstructure processing, microcircuit design and device packaging, resulting in high cost and low yield. From the perspective of microstructure processing, due to the short distance of electrostatic force, the spacing between the capacitor plates is required to be extremely small (submicron level), which increases the difficulty of microprocessing of electrostatic excitation structures. From the perspective of microcircuit design, electrostatic excitation requires the application of a DC bias voltage to reduce the dynamic impedance of the drive circuit, which increases the power consumption required for device operation. From the perspective of device packaging, in order to reduce the damping of the oscillator and improve the quality factor, MEMS gyroscopes using electrostatic excitation usually need to use a vacuum packaging process, which increases the difficulty of the packaging process. Although capacitance detection can be well compatible with IC circuits, due to the influence of parasitic capacitance and other problems, the accuracy and sensitivity of capacitance detection methods are greatly limited, especially when the three axes are integrated on a single chip, the influence of parasitic capacitance is particularly obvious. Summary of the invention

[0004] In view of the shortcomings of the prior art, the utility model provides a single-chip three-axis MEMS gyroscope, which adopts electromagnetic force drive and piezoresistive effect detection. The drive and detection do not rely on the comb tooth structure that requires precision machining, and are not affected by problems such as parasitic capacitance. It can solve the problems of high cost and low yield caused by high requirements for microstructure processing, microcircuit design and device packaging in the prior art MEMS gyroscopes with electrostatic excitation and capacitance detection.

[0005] In order to achieve the above object, the technical solution of the utility model is as follows:

[0006] The utility model provides a single-chip three-axis MEMS gyroscope, comprising: four vibration mass blocks, a spring beam, a surface doped sensing beam, a side doped sensing beam, a driving electrode, and a detection electrode, characterized in that the four vibration mass blocks are orthogonally symmetrically distributed, the vibration mass blocks are connected to the driving electrodes through the spring beams; the vibration mass blocks are respectively connected to the surface doped sensing beam and the side doped sensing beam through different spring beams; the surface of the surface doped sensing beam is doped to form a force-sensitive resistor; the side of the side doped sensing beam is doped to form a force-sensitive resistor; the surface doped sensing beam and the side doped sensing beam are respectively connected to the detection electrodes.

[0007] The surface-doped sensing beam is a thin plate structure parallel to the plane, and the side-doped sensing beam is a thin plate structure perpendicular to the plane.

[0008] The driving circuits of the four vibration mass blocks are connected in series. Beneficial Effects

[0009] Through the above scheme, the beneficial effects achieved by the utility model are:

[0010] The utility model realizes a three-axis MEMS gyroscope on a single chip. Compared with the traditional three-axis gyroscope integrated with three independent X, Y, and Z single-axis gyroscopes, it does not need three sets of independent driving structures, has a smaller size and a higher integration level.

[0011] The utility model adopts electromagnetic force drive and piezoresistive effect detection. Compared with the MEMS gyroscope adopting electrostatic drive and electrostatic detection, the utility model has a simpler structure, lower requirements on processing technology and packaging, and is easy to realize mass production.

[0012] Since the resistance changes of each sensing beam respond to the three-axis angular velocity in an orthogonal manner, the interference between the angular velocity detection of different axes can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of an embodiment of the utility model.

[0014] Figure 2 This is a schematic diagram of a driving mode of an embodiment of the utility model.

[0015] Figure 3 It is a schematic diagram of the deflection of the vibration mass block of one embodiment of the utility model when rotating in the x-axis direction.

[0016] Figure 4 It is a schematic diagram of the deflection of the vibration mass block of one embodiment of the utility model when rotating in the y-axis direction.

[0017] Figure 5 It is a schematic diagram of the deflection of the vibration mass block of one embodiment of the utility model when rotating in the z-axis direction.

[0018] Reference numerals:

[0019] 100. Vibration mass block, 110. First vibration mass block, 120. Second vibration mass block, 130. Third vibration mass block, 140. Fourth vibration mass block; 200. Sensing beam, 210. Surface-doped sensing beam, 211. First surface-doped sensing beam, 212. Second surface-doped sensing beam, 213. Third surface-doped sensing beam, 214. Fourth surface-doped sensing beam, 215. Fifth surface-doped sensing beam, 216. Sixth surface-doped sensing beam, 217. Seventh surface-doped sensing beam, 218. Eighth surface-doped sensing beam, 220. Side-doped sensing beam, 221. First side-doped sensing beam, 222. Second side-doped sensing beam, 223. Third side-doped sensing beam, 224. Fourth side-doped sensing beam, 300. Spring beam; 400. Driving electrode; 500. Detection electrode, 510. Surface deformation detection electrode, 520. Side deformation detection electrode. DETAILED DESCRIPTION

[0020] The specific implementation of the utility model is further described below in conjunction with the accompanying drawings.

[0021] like Figure 1 As shown, the utility model provides a single-chip three-axis MEMS gyroscope, including: a vibration mass block 100, a sensing beam 200, a spring beam 300, a driving electrode 400, and a detection electrode 500. There are four vibration mass blocks 100, which are orthogonally symmetrically distributed and connected to the driving electrode 400 through the spring beam 300; the vibration mass block 100 is connected to two surface sensing beams 210 through the spring beam 300, and adjacent vibration mass blocks 100 are connected to the same side sensing beam 220 through the spring beam 300. The surface sensing beam 210 is connected to the surface deformation detection electrode 510, and the side sensing beam 220 is connected to the side deformation detection electrode 520.

[0022] like Figure 2 As shown, the four vibration mass blocks 100 are in the same magnetic field, and an alternating current is applied to the vibration mass blocks 100 through the driving electrode 400, generating a periodically changing Lorentz force on the vibration mass blocks 100, driving the vibration mass blocks 100 to reciprocate. By connecting the circuit of the four vibration mass blocks in series, the vibration mass blocks can be synchronously moved toward and away from the center of the sensor. When no rotation occurs, the movement of adjacent vibration mass blocks 100 is symmetrical relative to the central axis.

[0023] The sensing beam 200 includes a surface-doped sensing beam 210 and a side-doped sensing beam 220. The surface-doped sensing beam 210 is a thin plate structure in the horizontal direction, which is easy to deform perpendicularly to the plane, but not easy to deform within the plane. The side-doped sensing beam 220 is a thin plate structure in the vertical direction, which is easy to deform within the plane, but not easy to deform perpendicularly to the plane. The surface of the surface-doped sensing beam 210 forms a surface force-sensitive resistor by doping. When the surface-doped sensing beam 210 is deformed perpendicularly to the plane, the resistance value of the surface force-sensitive resistor will change. The side of the side-doped sensing beam 220 forms a side force-sensitive resistor by doping. When the side-doped sensing beam 220 is deformed within the plane, the resistance value of the side force-sensitive resistor will change.

[0024] The first vibration mass 110 is connected to the first surface doped sensing beam 211, the second surface doped sensing beam 212, and the first side doped sensing beam 221 through the spring beam 300. The second vibration mass 120 is connected to the third surface doped sensing beam 213, the fourth surface doped sensing beam 214, and the second side doped sensing beam 222 through the spring beam 300. The third vibration mass 130 is connected to the fifth surface doped sensing beam 215, the sixth surface doped sensing beam 216, and the third side doped sensing beam 223 through the spring beam 300. The fourth vibration mass 140 is connected to the seventh surface doped sensing beam 217, the eighth surface doped sensing beam 218, and the fourth side doped sensing beam 224 through the spring beam 300.

[0025] When the first vibration mass 110 deflects perpendicularly to the plane, the first surface doped sensing beam 211 and the second surface doped sensing beam 212 deform perpendicularly to the plane. When the first vibration mass 110 deflects within the plane, the first side doped sensing beam 221 deforms within the plane. The deflection of other vibration mass 100 has the same effect on the connected sensing beam 200 as the first vibration mass.

[0026] like Figure 3As shown, when a rotation occurs around the positive direction of the x-axis, the first vibration mass block 110 and the third vibration mass block 130 will deflect under the action of the Coriolis force, and the deflection direction of the first vibration mass block 110 is the positive direction of the z-axis, and the deflection direction of the third vibration mass block 130 is the negative direction of the z-axis. The deflection of the first vibration mass block 110 will drive the first surface doped sensing beam 211 and the second surface doped sensing beam 212 to deflect in the positive direction of the z-axis, resulting in a change in the resistance value of the surface force-sensitive resistor on the first surface doped sensing beam 211 and the second surface doped sensing beam 212. The deflection of the third vibration mass block 130 will drive the fifth surface doped sensing beam 215 and the sixth surface doped sensing beam 216 to deflect in the negative direction of the z-axis, resulting in a change in the resistance value of the surface force-sensitive resistor on the fifth surface doped sensing beam 215 and the sixth surface doped sensing beam 216. The increase and decrease of the resistance values ​​of the surface force-sensitive resistors on the fifth surface-doped sensing beam 215 and the sixth surface-doped sensing beam 216 are opposite to the increase and decrease of the resistance values ​​of the surface force-sensitive resistors on the first surface-doped sensing beam 211 and the second surface-doped sensing beam 212 .

[0027] like Figure 4 As shown, when the rotation occurs around the positive direction of the y-axis, the second vibration mass 120 and the fourth vibration mass 140 will deflect under the action of the Coriolis force, the deflection direction of the second vibration mass 120 is the positive direction of the z-axis, and the deflection direction of the fourth vibration mass 140 is the negative direction of the z-axis. The deflection of the second vibration mass 120 will drive the third surface doped sensing beam 213 and the fourth surface doped sensing beam 214 to deflect in the positive direction of the z-axis, resulting in a change in the resistance value of the surface force sensitive resistor on the third surface doped sensing beam 213 and the fourth surface doped sensing beam 214. The deflection of the fourth vibration mass block 140 will drive the seventh surface-doped sensor beam 217 and the eighth surface-doped sensor beam 218 to deflect toward the negative direction of the z-axis, resulting in changes in the resistance of the surface force-sensitive resistors on the seventh surface-doped sensor beam 217 and the eighth surface-doped sensor beam 218. The increase or decrease in the resistance of the surface force-sensitive resistors on the seventh surface-doped sensor beam 217 and the eighth surface-doped sensor beam 218 is opposite to the increase or decrease in the resistance of the surface force-sensitive resistors on the third surface-doped sensor beam 213 and the fourth surface-doped sensor beam 214.

[0028] like Figure 5As shown, when rotation occurs about the positive direction of the z-axis, the first vibration mass 110, the second vibration mass 120, the third vibration mass 130 and the fourth vibration mass 140 will deflect in the plane under the action of the Coriolis force, and the deflection direction of the first vibration mass 110 is the negative direction of the x-axis, the deflection direction of the second vibration mass 120 is the positive direction of the y-axis, the deflection direction of the third vibration mass 130 is the positive direction of the x-axis, and the deflection direction of the fourth vibration mass 140 is the negative direction of the y-axis. The deflection of the first vibration mass block 110, the second vibration mass block 120, the third vibration mass block 130 and the fourth vibration mass block 140 will drive the first side doped sensing beam 221, the second side doped sensing beam 222, the third side doped sensing beam 223 and the fourth side doped sensing beam 224 to deflect in the plane, resulting in changes in the resistance values ​​of the side force-sensitive resistors on the first side doped sensing beam 221, the second side doped sensing beam 222, the third side doped sensing beam 223 and the fourth side doped sensing beam 224.

[0029] The change in resistance of the force-sensitive resistor will vary with the direction of rotation, so the angular velocity of the three axes can be detected by measuring the change in resistance of the force-sensitive resistor.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A single-chip three-axis MEMS gyroscope, comprising: Four vibration mass blocks, a spring beam, a surface-doped sensing beam, a side-doped sensing beam, a driving electrode, and a detection electrode, characterized in that the four vibration mass blocks are orthogonally symmetrically distributed, the vibration mass blocks are connected to the driving electrodes through the spring beams; the vibration mass blocks are respectively connected to the surface-doped sensing beam and the side-doped sensing beam through different spring beams; the surface of the surface-doped sensing beam is doped to form a force-sensitive resistor; the side of the side-doped sensing beam is doped to form a force-sensitive resistor; the surface-doped sensing beam and the side-doped sensing beam are respectively connected to the detection electrodes.

2. The single-chip three-axis MEMS gyroscope according to claim 1, characterized in that: The surface-doped sensing beam is a thin plate structure parallel to the plane, and the side-doped sensing beam is a thin plate structure perpendicular to the plane.

3. The single-chip three-axis MEMS gyroscope according to claim 1, characterized in that: The driving circuits of the four vibration mass blocks are connected in series.

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