WO2011130941A1 - 变面积电容结构、梳状栅电容加速度计以及梳状栅电容陀螺 - Google Patents

变面积电容结构、梳状栅电容加速度计以及梳状栅电容陀螺 Download PDF

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WO2011130941A1
WO2011130941A1 PCT/CN2010/074340 CN2010074340W WO2011130941A1 WO 2011130941 A1 WO2011130941 A1 WO 2011130941A1 CN 2010074340 W CN2010074340 W CN 2010074340W WO 2011130941 A1 WO2011130941 A1 WO 2011130941A1
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Prior art keywords
front surface
triangular
rectangular
trapezoidal
fixed electrode
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PCT/CN2010/074340
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English (en)
French (fr)
Inventor
金仲和
胡世昌
张霞
朱辉杰
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浙江大学
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Priority claimed from CN2010101516300A external-priority patent/CN101834065B/zh
Priority claimed from CN2010101516368A external-priority patent/CN101819215B/zh
Priority claimed from CN2010101516531A external-priority patent/CN101813480B/zh
Application filed by 浙江大学 filed Critical 浙江大学
Priority to US13/576,042 priority Critical patent/US8971012B2/en
Publication of WO2011130941A1 publication Critical patent/WO2011130941A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
    • G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
    • G01C19/5719—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
    • G01C19/5733—Structural details or topology
    • G01C19/5755—Structural details or topology the devices having a single sensing mass
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/125—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by capacitive pick-up
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P2015/0805—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration
    • G01P2015/0808—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining in-plane movement of the mass, i.e. movement of the mass in the plane of the substrate
    • G01P2015/0811—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining in-plane movement of the mass, i.e. movement of the mass in the plane of the substrate for one single degree of freedom of movement of the mass
    • G01P2015/0814—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining in-plane movement of the mass, i.e. movement of the mass in the plane of the substrate for one single degree of freedom of movement of the mass for translational movement of the mass, e.g. shuttle type

Definitions

  • the invention belongs to the field of micromechanical sensors, in particular to a variable area capacitance structure capable of adjusting the elastic coefficient of a micromechanical sensor, a variable area comb gate capacitance accelerometer with adjustable elastic coefficient and a variable area with electric tuning function.
  • Comb-gate capacitor gyro Comb-gate capacitor gyro.
  • micromechanical sensors have developed rapidly.
  • common include micromechanical accelerometers and micromechanical gyroscopes.
  • the accelerometer is a device used to measure the acceleration of an object.
  • a high-precision accelerometer is one of the key basic components and an important component of the inertial unit.
  • accelerometers such as liquid floating pendulum accelerometers, flexible pendulum accelerometers, vibrating wire accelerometers, and pendulum-integrated gyro accelerometers.
  • Micro-mechanical accelerometer is an accelerometer developed based on the microelectronics industry. It can integrate accelerometer and sensitive circuit on the same chip. It has the advantages of small size and low cost, so it has been obtained in the field of automotive electronics and consumer electronics. A wide range of applications.
  • the gyro is a sensor used to measure angular velocity and angular displacement, and is an important component of the inertial sensing unit. From the initial demonstration of the rotation of the earth by the fixed-axis nature of the high-speed rotating rigid body, the gyro has been developed for more than one hundred years, and the rotor-type gyro, the optical gyro, and the micro-mechanical gyro have come out.
  • the sensitive mechanism of the vibrating micromachined gyroscope is Coriolis Coriolis ) Force, Coriolis force is proportional to the rotational speed of the object, and the rotation speed of the object can be obtained by detecting the Coriolis force.
  • micro-mechanical sensors are mainly piezoresistive, capacitive, resonant, and tunnel.
  • capacitive type has become the mainstream of today's design due to its fast response and simple fabrication.
  • variable pitch capacitor structures there are two types: variable pitch capacitor structures and variable area capacitor structures.
  • the traditional comb-gate capacitive accelerometer is a variable-area capacitor structure accelerometer, but due to (in traditional design
  • the unit movable electrode and the fixed electrode are both rectangular, and the elastic modulus is not adjustable.
  • micromachined capacitive gyro there are also variable pitch capacitor structures and variable area two capacitor structures.
  • the micro-mechanical gyro works at the resonant frequency point.
  • the important performance indexes such as sensitivity and bandwidth are related to the frequency difference between the driving direction and the detecting direction.
  • the frequency difference between the two needs to be properly selected to achieve the required performance.
  • micromachined gyro machining due to the limited processing accuracy and processing consistency, it is often difficult to obtain the frequency difference required for the design, resulting in device performance not meeting the design goals.
  • variable-area capacitor structure fails to adjust the resonant frequency of the driving or detecting direction of the comb-gate capacitive gyro, so that the performance of the comb-gate capacitive gyro cannot be effectively improved.
  • the technical problem to be solved by the present invention is how to adjust the elastic coefficient of the variable area capacitive micromechanical sensor, in particular, the elastic coefficient of the variable area capacitive accelerometer and the resonant frequency of the variable area capacitive gyro.
  • the invention adjusts the elastic modulus of the micromechanical device, the front surface of the movable electrode of the holding unit is parallel to the front surface of the unit fixed electrode, and the distance between the front surface of the unit movable electrode and the front surface of the unit fixed electrode is unchanged.
  • the shape of the front surface of the unit fixed electrode is changed from a conventional rectangle to a triangle or a zigzag shape, and the shape of the front surface of the unit movable electrode is still rectangular, or the shape of the front surface of the unit movable electrode is conventional.
  • the rectangular shape is changed to a triangle or a zigzag shape, and the front surface shape of the unit fixed electrode is still rectangular, and the front surface of the unit movable electrode and the front surface of the unit fixed electrode form a certain feature overlap, and the unit fixed electrode and unit
  • an equivalent elastic coefficient can be introduced, which is a constant, which can be either a positive number or a negative number, so that the total elastic modulus increases or decreases.
  • the capacitor structure is used for variable area capacitive accelerometers and variable area capacitive gyros, so that the elastic modulus of the variable area capacitive accelerometer and the resonant frequency of the variable area capacitive gyro can be adjusted.
  • a variable area capacitance structure capable of adjusting a modulus of elasticity of a micromechanical device, wherein in each unit capacitance, a front surface of the movable electrode and a front surface of the fixed electrode are parallel to each other, wherein The front surface of the movable electrode is rectangular and the front surface of the fixed electrode is triangular or zigzag, or the front surface of the movable electrode is triangular or zigzag and the front surface of the fixed electrode is rectangular; the triangular front surface only Overlaps a long side of the front surface of the rectangle.
  • the serrations of the zigzag front surface are triangular and the triangular serrations overlap only one long side of the rectangular front surface.
  • the serration of the zigzag front surface is trapezoidal and the trapezoidal serration overlaps only one long side of the rectangular front surface, and the overlapping portion is triangular.
  • the serration of the zigzag front surface is trapezoidal and the trapezoidal serration overlaps only one long side of the rectangular front surface, the overlapping portion is trapezoidal, and the bottom edge of the trapezoidal overlapping portion is The long sides of the rectangular front surface are parallel.
  • the variable area capacitor structure is applied to a conventional comb-cavity accelerometer, and a comb-cavity accelerometer with adjustable elastic coefficient is provided, and the accelerometer is distributed in a sensitive direction.
  • the front surface of the movable electrode and the front surface of the fixed electrode are parallel to each other, wherein the front surface of the movable electrode Rectangled and the front surface of the fixed electrode is triangular or zigzag, or the front surface of the movable electrode is triangular or zigzag and the front surface of the fixed electrode is rectangular; the triangular front surface is only opposite to the rectangular front surface A long side overlaps.
  • the serrations of the zigzag front surface are triangular and the triangular serrations overlap only one long side of the rectangular front surface.
  • the serration of the zigzag front surface is trapezoidal and the trapezoidal serration overlaps only one long side of the rectangular front surface, and the overlapping portion is triangular.
  • the serration of the zigzag front surface is trapezoidal and the trapezoidal serration overlaps only one long side of the rectangular front surface, the overlapping portion is trapezoidal, and the bottom edge of the trapezoidal overlapping portion is The long sides of the rectangular front surface are parallel.
  • variable area capacitor structure is applied to a conventional comb-gate capacitance gyro to provide a comb-gate capacitance gyro having an adjustable resonant frequency, and the driving or detecting direction of the gyro is electrically tuned.
  • variable area capacitance in which a positive surface of the movable electrode and a front surface of the fixed electrode are parallel to each other, and a front surface of the movable electrode is rectangular and a front surface of the fixed electrode
  • the shape is triangular or zigzag, or the front surface of the movable electrode is triangular or zigzag and the front surface of the fixed electrode is rectangular; the triangular front surface overlaps only one long side of the rectangular front surface.
  • the serration of the zigzag front surface of the present invention is triangular and the triangular serration overlaps only one long side of the rectangular front surface.
  • the serration of the zigzag front surface of the present invention is trapezoidal and the trapezoidal serration overlaps only one long side of the rectangular front surface, and the overlapping portion has a triangular shape.
  • the serration of the zigzag front surface of the present invention is trapezoidal and the trapezoidal serration overlaps only one long side of the rectangular front surface, the overlapping portion is trapezoidal, and the bottom edge of the trapezoidal overlapping portion is The long sides of the rectangular front surface are parallel.
  • variable area capacitor structure in the present invention has the following advantages:
  • the equivalent elastic coefficient introduced can be either positive or negative, and can be flexibly designed according to needs;
  • the total elastic modulus of the micromechanical device in the corresponding direction can be adjusted by adjusting the voltage difference between the fixed electrode and the movable electrode of the unit.
  • the comb-type gate capacitance accelerometer with adjustable elastic modulus has the following advantages:
  • the existing comb-like capacitor accelerometer has a large dispersion coefficient of elasticity, and it is difficult to obtain consistent performance, and the accelerometer of the present invention can overcome this defect through
  • the electric tuning variable area capacitance adjusting elastic coefficient of the elastic coefficient distributed in the sensitive direction makes the performance of the same batch acceleration device tend to be consistent;
  • the elastic coefficient of the device can be reduced by an electrical tuning method, thereby achieving high performance.
  • the comb-gate gate gyro with adjustable resonant frequency in the present invention has the following advantages:
  • the comb-gate capacitance gyro of the present invention adjusts the resonant frequency of the driving or detecting direction by the electric tuning variable area capacitance distributed in the driving or detecting direction, so that the performance of the same batch of gyro devices tends to be consistent;
  • the comb-gate capacitive gyro of the present invention can adjust the resonant frequency of the driving or detecting direction by the electric tuning variable area capacitance distributed in the driving or detecting direction, so that the resonant frequency of the driving and detecting directions tends to be uniform or even equal. Greatly improve the sensitivity of the gyro.
  • FIG. 1 is a top plan view of a first type of single-sided capacitor when the unit fixed electrode of the variable area capacitor structure of the present invention is triangular;
  • FIG. 2 is a plan view showing a second single-sided capacitor when the unit fixed electrode of the variable area capacitor structure of the present invention is triangular;
  • FIG. 3 is a plan view showing a third single-sided capacitor when the unit fixed electrode of the variable area capacitor structure of the present invention is triangular;
  • FIG. 4 is a plan view showing a fourth single-sided capacitor when the unit fixed electrode of the variable area capacitor structure of the present invention is triangular;
  • FIG. 5 is a plan view showing a first type of differential capacitance when the unit fixed electrode of the variable area capacitor structure of the present invention is triangular;
  • FIG. 6 is a plan view showing a second type of differential capacitance when the unit fixed electrode of the variable area capacitor structure of the present invention is triangular;
  • FIG. 7 is a top view of a third differential capacitor when the cell fixed electrode of the variable area capacitor structure of the present invention is triangular;
  • FIG. 8 is a plan view showing a fourth differential capacitor when the unit fixed electrode of the variable area capacitor structure of the present invention is triangular;
  • Figure 9 Is a first type of differential capacitance top view of the variable area capacitor structure of the present invention when the unit fixed electrode is zigzag and each saw tooth is triangular;
  • Figure 10 Is a second type of differential capacitance top view of the variable area capacitor structure of the present invention when the unit fixed electrode is zigzag and each saw tooth is triangular;
  • Figure 11 is a plan view showing the first structure of the variable area capacitor structure of the present invention when the unit movable electrode is zigzagged and each saw tooth is trapezoidal;
  • FIG. 12 is a plan view showing a second structure of the variable area capacitor structure of the present invention when the unit movable electrode is zigzag and each saw tooth is trapezoidal;
  • FIG. 13 is a schematic cross-sectional view showing a differential structure of a variable area comb-gate capacitor structure of the present invention.
  • FIG. 14 is a schematic cross-sectional view showing the structure of a comb-like gate capacitance accelerometer with adjustable elastic modulus according to the present invention.
  • FIG. 15 is a schematic diagram of a fixed electrode of a comb-cavity accelerometer with adjustable elastic modulus according to the present invention.
  • FIG. 16 is a top plan view of a comb-cavity accelerometer with adjustable elastic modulus according to the present invention.
  • FIG. 17 is a schematic cross-sectional structural view of a comb-gate capacitive gyro with adjustable resonant frequency according to the present invention.
  • FIG. 18 is a top plan view of a comb-gate gate gyro with adjustable resonant frequency according to the present invention.
  • Fig. 19 is a schematic view showing a fixed electrode distribution of a comb-gate capacitance gyro having a resonant frequency of the present invention.
  • the front surface of the unit movable electrode 1 refers to a surface facing the unit fixed electrode 2
  • the unit The front surface of the fixed electrode 2 refers to a surface that faces the unit movable electrode 1.
  • the front surface of each unit movable electrode 1 and the front surface of the unit fixed electrode 2 are parallel to each other.
  • the front surface of the unit movable electrode 1 is rectangular, and when the front surface of the unit fixed electrode 2 is triangular, the triangular front surface of the unit fixed electrode 2 is only related to the movable electrode 1 of the unit.
  • One long side of the rectangular front surface overlaps; when the front surface of the unit fixed electrode 2 is zigzag, as shown in FIGS. 9 and 10, each saw tooth is triangular, and each serration is only a rectangular front surface of the movable electrode 1 of the unit.
  • One of the long sides overlaps.
  • the front surface of the unit fixed electrode 2 is triangular and overlaps only one long side of the rectangular front surface of the unit movable electrode 1 to form a triangular overlapping region, and further, one side of the triangular unit fixed electrode 2 This side parallel to the long side of the rectangular unit movable electrode 1 and the triangular unit fixed electrode 2 is outside the overlapping area.
  • the voltage difference between the unit fixed electrode 2 and the unit movable electrode 1 is V
  • the length of the bottom side of the triangular unit fixed electrode 2 is m
  • the height of the triangular unit fixed electrode 2 is f
  • the displacement of the unit movable electrode 1 along the X-axis direction is x.
  • the overlapping portion of the unit movable electrode 1 and the unit fixed electrode 2 has a triangular shape, and the area of the overlapping region is s.
  • the unit movable electrode 1 generates a displacement x in the positive direction of the X-axis, according to the triangle
  • the capacitance is:
  • the tangential electrostatic force is obtained, that is, the electrostatic force in the X-axis direction is:
  • the capacitance is:
  • the tangential electrostatic force is obtained, that is, the electrostatic force in the X-axis direction is:
  • the width a of the rectangular unit movable electrode 1 is 10 ⁇ m
  • the length b of the rectangular unit movable electrode 1 is 2100 ⁇ m
  • the length m of the bottom side of the triangular unit fixed electrode 2 is 2000 ⁇ m
  • the height f of the fixed electrode 2 is 10 ⁇ m
  • the pitch h between the unit movable electrode 1 and the cell fixed electrode 2 is 1.5 ⁇ m
  • the voltage difference V between the cell fixed electrode 2 and the cell movable electrode 1 is 15V.
  • the equivalent elastic modulus introduced is -0.1328 N/m
  • the equivalent elastic coefficient is negative and constant
  • the equivalent elastic modulus introduced is 0.1328. N/m
  • the equivalent elastic modulus introduced is positive and constant.
  • the front surface of the unit fixed electrode 2 is a right triangle and overlaps only one long side of the rectangular front surface of the unit movable electrode 1, and a right angle side of the rectangular electrode unit fixed electrode 2 and the unit movable electrode
  • the long sides of the rectangular front surface of 1 are parallel, and the right angle of the right-angled triangular unit fixed electrode 2 is located outside the overlapping area of the unit movable electrode 1 and the unit fixed electrode 2.
  • the voltage difference between the unit fixed electrode 2 and the unit movable electrode 1 is V; the displacement of the unit movable electrode 1 is x, and x is the displacement of the unit movable electrode 1 in the X-axis direction, which may be positive or negative.
  • the initial overlapping width of the unit movable electrode 1 and the unit fixed electrode 2 is e; the height of the fixed triangular electrode of the right triangle unit is d, and the length of the bottom side of the fixed electrode 2 of the right triangle unit is c; as shown in FIG.
  • the distance between the unit movable electrode 1 and the unit fixed electrode 2 is h, and when the unit movable electrode 1 moves in the X-axis direction, the pitch h between the unit movable electrode 1 and the unit fixed electrode 2 does not change.
  • the overlapping portion of the unit movable electrode 1 and the unit fixed electrode 2 has a right-angled triangle shape, and the area of the overlapping region is s.
  • the capacitance is:
  • the tangential electrostatic force is obtained, that is, the electrostatic force in the X-axis direction is:
  • the front surface of the unit fixed electrode 2 is a right-angled triangle, which overlaps only one long side of the rectangular front surface of the unit movable electrode 1, and a right-angled side of the rectangular electrode unit fixed electrode 2 and the unit movable electrode
  • the long sides of the rectangular front surface of 1 are parallel, and the right angle of the right-angled triangular unit fixed electrode 2 is located in the overlapping area of the unit movable electrode 1 and the unit fixed electrode 2.
  • the overlapping shape of the unit movable electrode 1 and the unit fixed electrode 2 is trapezoidal, and the area of the overlapping region is s.
  • the capacitance is:
  • the tangential electrostatic force is obtained, that is, the electrostatic force in the X-axis direction is:
  • the width a of the rectangular unit movable electrode 1 is 10 ⁇ m
  • the length b of the rectangular unit movable electrode 1 is 2100 ⁇ m
  • the length c of the bottom side of the rectangular electrode unit fixed electrode 2 is 10 ⁇ m
  • a right angle The height d of the triangular unit fixed electrode 2 is 2000 ⁇ m
  • the pitch h between the unit movable electrode 1 and the unit fixed electrode 2 is 1.5 ⁇ m
  • the voltage difference V between the unit fixed electrode 2 and the unit movable electrode 1 is 15V.
  • the equivalent elastic modulus introduced is -0.1328 N/m, and the equivalent elastic coefficient is a negative number and is constant; as shown in FIG. 4, the equivalent elastic modulus introduced is 0.1328. N/m, and the equivalent elastic modulus introduced is a positive number and is a constant.
  • the different directions can be introduced in the X-axis direction.
  • the modulus of elasticity thereby adjusting the total modulus of elasticity of the micromechanical device in the X-axis direction.
  • the calculation method of the equivalent elastic coefficient introduced by one side is the same as the foregoing method, and the equivalent elastic coefficient introduced by the differential capacitance is introduced by one side.
  • the equivalent elastic modulus is twice. Wherein, in the predetermined structure and the voltage difference V between the unit fixed electrode 2 and the unit movable electrode 1 is constant, the equivalent elastic coefficients introduced in FIGS. 5 and 7 are negative and constant, and are introduced in FIGS. 6 and 8.
  • the equivalent elastic coefficient is a positive number and is a constant.
  • each of the saw teeth is triangular, and each of the serrations overlaps only one long side of the rectangular front surface of the unit movable electrode 1.
  • Each sawtooth forms a triangular sawtooth capacitor structure with the rectangular front surface of the unit movable electrode 1.
  • the calculation method of the equivalent elastic coefficient introduced by the single triangular sawtooth capacitor structure is the same as the foregoing method, and the equivalent elastic modulus introduced by the entire capacitor structure is The sum of the equivalent elastic coefficients introduced by all triangular sawtooth capacitor structures of the unit fixed electrode 2.
  • the front surface of the unit movable electrode 1 is triangular and the front surface of the unit fixed electrode 2 is rectangular (not shown in the figure), it can be known from the above calculation method that the fixed electrode in the predetermined structure and unit When the voltage difference V between the cell and the movable electrode 1 is constant, the equivalent elastic modulus introduced by the entire capacitance of the structure is either a negative number or a positive number and is constant.
  • FIG. 11 and 12 are views showing the structure of the variable area capacitor structure of the present invention in which the front surface of the unit movable electrode 1 is zigzagged and each saw tooth is trapezoidal while the front surface of the unit fixed electrode 2 is rectangular.
  • the serrations of the zigzag front surface of the unit movable electrode 1 in FIG. 11 are trapezoidal and each trapezoidal serration overlaps only one long side of the rectangular front surface of the unit fixed electrode 2, and the overlapping portion is triangular, each serration A rectangular sawtooth capacitor structure is formed with the rectangular front surface of the unit fixed electrode 2.
  • the calculation method of the equivalent elastic modulus introduced by the single trapezoidal sawtooth capacitor structure is the same as the calculation method when the overlapping portion is triangular.
  • the equivalent elastic modulus introduced by the entire capacitor structure is the equivalent elastic modulus introduced by all the trapezoidal sawtooth capacitor structures of the unit fixed electrode 2. The sum, and either negative or positive, and are constant.
  • Each of the serrations of the zigzag-shaped front surface of the unit movable electrode 1 in FIG. 12 is trapezoidal and each of the trapezoidal serrations overlaps only one long side of the rectangular front surface of the unit fixed electrode 2, and the overlapping portion is trapezoidal and trapezoidal The bottom edge of the stack portion is parallel to the long side of the rectangular front surface.
  • Each of the serrations forms a trapezoidal sawtooth capacitance structure with the rectangular front surface of the unit fixed electrode 2.
  • the calculation method of the equivalent elastic modulus introduced by the single trapezoidal sawtooth capacitor structure is the same as the calculation method when the overlapping portion is trapezoidal.
  • the equivalent elastic modulus introduced by the entire capacitor structure is the equivalent elastic modulus introduced by all the trapezoidal sawtooth capacitor structures of the unit fixed electrode 2. The sum, and either negative or positive, and are constant.
  • the positive surface of the unit fixed electrode 2 is zigzag and each saw tooth is trapezoidal, and the positive surface of the unit movable electrode 1 is rectangular.
  • the equivalent of the variable area capacitor structure (not shown) is introduced.
  • the modulus of elasticity is either a negative number or a positive number, and is constant when the predetermined structure and the voltage difference V between the unit fixed electrode 2 and the unit movable electrode 1 are constant values.
  • the variable-area comb-gate capacitive accelerometer with adjustable elastic modulus applies the variable-area capacitor structure to a conventional comb-cavity accelerometer
  • the grid 4 is a unit.
  • the movable electrode 1, the electric tuning interdigital 5 is the unit fixed electrode 2 of the electric tuning capacitor, the common interdigital finger 6 is the unit fixed electrode 2 of the conventional variable area capacitance, and the front surface of the unit movable electrode 1 is fixed to the unit
  • the surface on which the electrode 2 faces, the front surface of the unit fixed electrode 2 means the surface facing the unit movable electrode 1.
  • the outer frame 10 is fixed on the fixed electrode substrate 8, the electrical tuning fingers 5 are fixed on the fixed electrode substrate 8, the mass 3 is connected to the beam 7, the beam 7 is connected to the outer frame 10, and the electrical signal on the mass 3 is passed.
  • the input or output of the electrode 9 is taken up as shown in FIG.
  • the beam 7 can be a U-beam, a straight beam, a folded beam, etc., and the X-axis direction is a sensitive direction.
  • the mass m of the sensitive mass is 5.1882 ⁇ 10 -6 kg, and the elastic coefficient k is 591.19 N/m.
  • the electric tuning capacitor is applied to increase the elastic coefficient in the sensitive direction of the variable area comb-gate capacitive accelerometer by 5.3120 N/m, the resonance of the variable area comb-gate capacitance accelerometer in the sensitive direction The frequency can be increased by 7.6156 Hz; if the electric tuning capacitor is used to reduce the elastic coefficient in the sensitive direction of the variable-area comb-gate capacitive accelerometer by 5.3120 N/m, the resonant frequency in the sensitive direction of the variable-area comb-gate capacitive accelerometer can be Reduce 7.6499Hz.
  • variable area comb-gate capacitance accelerometer of the present invention by adjusting the voltage difference V between the unit fixed electrode 2 and the unit movable electrode 1, the resonance frequency can be made larger or smaller; the design has less elasticity.
  • the beam structure of the coefficient can even make the elastic coefficient and the resonant frequency in the sensitive direction of the variable-area comb-gate capacitive accelerometer device close to or equal to zero.
  • variable-area comb-gate capacitance gyro having an electric tuning function according to the present invention, wherein the variable-area capacitor structure is applied to a conventional comb-gate capacitance gyro, and the grid 13 is a unit movable electrode.
  • the electric tuning interdigital finger 14 is a unit fixed electrode 2 of an electrically tuned capacitor
  • the common interdigital finger 15 is a unit fixed electrode 2 of a conventional variable area capacitor.
  • the outer frame 20 is fixed on the fixed electrode substrate 18, the electrical tuning fingers 14 and the common fingers 15 are fixed on the fixed electrode substrate 18, and the driving mass 11 is connected to the outer frame 20 through the driving beam 16, and the detecting mass 12 passes.
  • the detecting beam 17 is connected to the driving mass 11 to become a part of the driving mass 11, and an electric signal is input or output through the extraction electrode 19 as shown in FIG.
  • the driving beam 16 and the detecting beam 17 may be U-shaped beams, straight beams, folded beams, etc., and the gyro driving direction and the detecting direction are also opposite, depending on the design.
  • the X-axis direction is the driving direction
  • the Y-axis direction is the detecting direction
  • the driving mass 11 is movable in the X-axis direction
  • the detecting mass 12 is movable in the X-axis direction and the Y-axis direction.
  • the driving mass 11 is resonantly moved in the X-axis direction together with the detecting mass 12, and when a fixed angular velocity is input, the same-frequency vibration of the detecting mass 12 in the Y-axis direction is caused.
  • the comb-gate capacitance gyro of the present invention distributes a certain number of electrically tuned variable area capacitances in the driving direction or the detecting direction, and the elastic coefficient of the driving direction or the detecting direction can be adjusted as needed to adjust the resonant frequency of the driving or detecting direction.
  • the mass of the proof mass 12 is 5.1882 ⁇ 10 -6 kg
  • the mass of the driving mass 11 is 1.0227 ⁇ 10 -5 kg
  • the elastic modulus of the detecting direction is 591.19 N/m.
  • the elastic modulus is 1145 N/m
  • the resonance frequency in the detection direction is 1699 Hz and the resonance frequency in the driving direction is 1684 Hz before electrical tuning is performed.
  • the resonant frequency of the driving direction can be adjusted to be the same as the detecting direction, or a certain elastic coefficient can be introduced in the driving or detecting direction at the same time, so that the resonant frequencies of the driving and detecting directions are both adjusted to the same frequency, thereby effectively improving the gyro Sensitivity.
  • the comb-gate capacitance can be realized by adjusting the voltage difference between the unit fixed electrode 2 and the unit movable electrode 1 of the electrically tuned variable area capacitance in the driving or detecting direction of the comb-gate capacitor gyro of the present invention.
  • the adjustment of the elastic coefficient in the gyro drive or detection direction to adjust the resonant frequency in the driving or detecting direction is simple and convenient.

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Description

变面积电容结构、梳状栅电容加速度计以及梳状栅电容陀螺 技术领域
本发明属于微机械传感器领域，尤其涉及一种可调节微机械传感器弹性系数的变面积电容结构、一种弹性系数可调的变面积梳状栅电容加速度计以及一种具有电调谐功能的变面积梳状栅电容陀螺。
背景技术
经过几十年的研究，微机械传感器发展迅速。在微机械传感器中，常见的包括微机械加速度计和微机械陀螺。
其中，加速度计是用来测量物体所受加速度的器件，在惯性导航系统中，高精度的加速度计是关键的基本元件之一，是惯性单元中的重要组成部分。加速度计的种类很多，如液浮摆式加速度计、挠性摆式加速度计、振弦式加速度计、摆式积分陀螺加速度计等。微机械加速度计是基于微电子产业发展起来的一种加速度计，可将加速度计与敏感电路集成在同一块芯片上，具有体积小，成本低等优点，因而在汽车电子和消费电子领域获得了广泛的应用。
而陀螺是用来测量角速度和角位移的传感器，是惯性传感单元的重要组成部分。从最初利用高速旋转刚体的定轴性对地球的自转现象进行演示至今，陀螺已经过了一百多年的发展历程，转子式陀螺，光学陀螺，微机械陀螺纷纷问世。振动式微机械陀螺的敏感机理是哥里奥利（ Coriolis ）力， Coriolis 力与物体的转动速度成正比，通过检测 Coriolis 力就能得到物体的转动速度。
微机械传感器的检测类型，主要有压阻式，电容式，谐振式，隧道式等。其中电容式由于其响应快，制作简单等优点已成为当今设计的主流。
具体到微机械电容式加速度计，可分为两种：变间距式的电容结构和变面积式的电容结构。传统的梳状栅电容加速度计为变面积式电容结构的加速度计，但由于 ( 传统设计中 ) 其单元可动电极和固定电极均为矩形，其弹性系数不可调。
而对于微机械电容式陀螺，也有变间距式的电容结构和变面积式两种电容结构。微机械陀螺工作在谐振频率点上，灵敏度、带宽等重要性能指标均与驱动方向和检测方向的频率差相关，设计中需要合理选择两者频率差来实现所需性能。而微机械陀螺加工中，由于加工精度和加工一致性有限，往往难以获得设计所需的频率差，导致器件性能无法达到设计目标。为改善陀螺性能，通常需要对陀螺驱动或检测方向上的谐振频率进行调整，即电调谐。这在采用变间距电容结构的陀螺器件中已经得到应用。而现有的变面积式的电容结构未能对梳状栅电容陀螺的驱动或检测方向的谐振频率进行调整，使得梳状栅电容陀螺的性能无法得到有效地提高。
 技术问题
本发明所要解决的技术问题是：如何调节变面积电容式微机械传感器的弹性系数，特别是调节变面积电容式加速度计的弹性系数和变面积电容式陀螺的谐振频率。
技术解决方案
本发明为实现对微机械器件的弹性系数进行调节，在保持单元可动电极的正表面与单元固定电极的正表面平行且单元可动电极的正表面与单元固定电极的正表面的间距不变的前提下，通过将单元固定电极的正表面的形状由传统的矩形改为三角形或锯齿形而单元可动电极的正表面形状仍为矩形，或者将单元可动电极的正表面的形状由传统的矩形改为三角形或锯齿形而单元固定电极的正表面形状仍为矩形，并且使单元可动电极的正表面与单元固定电极的正表面形成具有一定特征的交叠，在单元固定电极与单元可动电极间施加一电压，即可引入一等效弹性系数，该等效弹性系数为常数，既可以为正数，也可以为负数，使得总的弹性系数增大或减小。进而将这种电容结构用于变面积电容式加速度计和变面积电容式陀螺，从而可以调节变面积电容式加速度计的弹性系数和变面积电容式陀螺的谐振频率。
因此，根据本发明的一个方面，提供一种可调节微机械器件弹性系数的变面积电容结构，在每个单元电容中，可动电极的正表面与固定电极的正表面相互平行，其中，所述可动电极的正表面为矩形且固定电极的正表面为三角形或锯齿形，或者所述可动电极的正表面为三角形或锯齿形且固定电极的正表面为矩形；所述三角形正表面仅与所述矩形正表面的一条长边交叠。
进一步地，所述锯齿形正表面的锯齿为三角形且所述三角形锯齿仅与所述矩形正表面的一条长边交叠。
进一步地，所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈三角形。
进一步地，所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈梯形，所述梯形交叠部分的底边与所述矩形正表面的长边平行。
根据本发明的另一个方面，将前述变面积电容结构应用于传统的梳状栅电容加速度计中，提供一种弹性系数可调的梳状栅电容加速度计，该加速度计的敏感方向上分布有用来调节弹性系数的电调谐变面积电容，所述电调谐变面积电容的每个单元电容中，可动电极的正表面与固定电极的正表面相互平行，其中，所述可动电极的正表面为矩形且固定电极的正表面为三角形或锯齿形，或者所述可动电极的正表面为三角形或锯齿形且固定电极的正表面为矩形；所述三角形正表面仅与所述矩形正表面的一条长边交叠。
进一步地，所述锯齿形正表面的锯齿为三角形且所述三角形锯齿仅与所述矩形正表面的一条长边交叠。
进一步地，所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈三角形。
进一步地，所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈梯形，所述梯形交叠部分的底边与所述矩形正表面的长边平行。
根据本发明的又一方面，将前述变面积电容结构应用于传统的梳状栅电容陀螺中，提供一种谐振频率可调的梳状栅电容陀螺，该陀螺的驱动或检测方向分布有电调谐变面积电容，在所述电调谐变面积电容的每个单元电容中，可动电极的正表面与固定电极的正表面相互平行，所述可动电极的正表面为矩形且固定电极的正表面为三角形或锯齿形，或者所述可动电极的正表面为三角形或锯齿形且固定电极的正表面为矩形；所述三角形正表面仅与所述矩形正表面的一条长边交叠。
进一步地，本发明所述锯齿形正表面的锯齿为三角形且所述三角形锯齿仅与所述矩形正表面的一条长边交叠。
进一步地，本发明所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈三角形。
进一步地，本发明所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈梯形，所述梯形交叠部分的底边与所述矩形正表面的长边平行。
 有益效果
与现有技术相比，本发明中的变面积电容结构具有以下优点：
1、引入的等效弹性系数既可以为正数，也可以为负数，可以根据需要灵活地进行设计；
2、在电容的结构参数和个数确定且单元固定电极与单元可动电极的电压差为定值时，引入的等效弹性系数为常数；
3、通过调节单元固定电极与单元可动电极的电压差的大小即可调节微机械器件在相应方向上总的弹性系数。
与现有技术相比，本发明中的弹性系数可调的梳状栅电容加速度计具有以下优点：
1、由于微机械加工工艺的离散性导致现有的梳状栅电容加速度计弹性系数有较大的离散性，难以获得一致的性能，而本发明中的加速度计可克服这一缺陷，通过其敏感方向上分布的用来调节弹性系数的电调谐变面积电容调节弹性系数，使同批次加速度器件性能趋于一致；
2、在MEMS工艺中，加工弹性系数很小的梁存在困难，利用本发明，可以通过电调谐的方法，减小器件的弹性系数，从而获得高的性能。
与现有技术相比，本发明中的谐振频率可调的梳状栅电容陀螺具有以下优点：
1、本发明中的梳状栅电容陀螺通过其驱动或检测方向上分布的电调谐变面积电容调节驱动或检测方向的谐振频率，使同批次陀螺器件性能趋于一致；
2、本发明中的梳状栅电容陀螺可通过其驱动或检测方向上分布的电调谐变面积电容调节驱动或检测方向的谐振频率，使驱动与检测方向的谐振频率趋于一致甚至相等，可极大地提高陀螺的灵敏度。
 附图说明
图 1 是本发明变面积电容结构的单元固定电极为三角形时的第一种单边电容俯视图；
图 2 是本发明变面积电容结构的单元固定电极为三角形时的第二种单边电容俯视图；
图 3 是本发明变面积电容结构的单元固定电极为三角形时的第三种单边电容俯视图；
图 4 是本发明变面积电容结构的单元固定电极为三角形时的第四种单边电容俯视图；
图 5 是本发明变面积电容结构的单元固定电极为三角形时的第一种差分电容俯视图；
图 6 是本发明变面积电容结构的单元固定电极为三角形时的第二种差分电容俯视图；
图 7 是本发明变面积电容结构的单元固定电极为三角形时的第三种差分电容俯视图；
图 8 是本发明变面积电容结构的单元固定电极为三角形时的第四种差分电容俯视图；
图 9 是本发明变面积电容结构在其单元固定电极为锯齿形且各锯齿为三角形时的第一种差分电容俯视图；
图 10 是本发明变面积电容结构在其单元固定电极为锯齿形且各锯齿为三角形时的第二种差分电容俯视图；
图 11 是本发明变面积电容结构在其单元可动电极为锯齿形且各锯齿为梯形时的第一种结构俯视图；
图 12 是本发明变面积电容结构在其单元可动电极为锯齿形且各锯齿为梯形时的第二种结构俯视图；
图 13 是本发明变面积梳状栅电容结构的差分结构剖面示意图；
图 14 是本发明弹性系数可调的梳状栅电容加速度计结构剖面示意图；
图 15 是本发明弹性系数可调的梳状栅电容加速度计的一种固定电极公布示意图；
图 16 是本发明弹性系数可调的梳状栅电容加速度计的俯视图；
图 17 是本发明谐振频率可调的梳状栅电容陀螺的剖面结构示意图；
图 18 是本发明谐振频率可调的梳状栅电容陀螺的俯视图；
图 19 是本发明谐振频率可调的梳状栅电容陀螺的一种固定电极分布示意图。
图中： 1 、单元可动电极， 2 、单元固定电极， 3 、质量块， 4 、栅条， 5 、电调谐叉指， 6 、普通叉指， 7 、梁， 8 、固定电极衬底， 9 、引出电极， 10 、外框， 11 、驱动质量块， 12 、检测质量块， 13 、栅条， 14 、电调谐叉指， 15 、普通叉指， 16 、驱动梁， 17 、检测梁， 18 、固定电极衬底， 19 、引出电极， 20 、外框， a 、矩形单元可动电极的宽度， b 、矩形单元可动电极的长度， c 、直角三角形单元固定电极底边的长度， d 、直角三角形单元固定电极的高度， h 、单元可动电极与单元固定电极的间距， e 、单元可动电极与单元固定电极的初始交叠宽度， s 、单元可动电极与单元固定电极的交叠面积， x 、单元可动电极的位移， m 、三角形单元固定电极的底边长度， f 、三角形单元固定电极的高度。
 本发明的实施方式
如图1至图13所示的本发明的各种形式的变面积电容结构中，在每个单元电容中，单元可动电极1的正表面是指与单元固定电极2正对的表面，单元固定电极2的正表面是指与单元可动电极1正对的表面。每个单元可动电极1的正表面与单元固定电极2的正表面相互平行。
其中，如图1至图8所示，单元可动电极1的正表面为矩形，当单元固定电极2的正表面为三角形时，单元固定电极2的三角形正表面仅与单元可动电极1的矩形正表面的一条长边交叠；当单元固定电极2的正表面为锯齿形时，如图9、10所示，每个锯齿为三角形，各锯齿仅与单元可动电极1的矩形正表面的其中一条长边交叠。
如图1所示，单元固定电极2的正表面为三角形且仅与单元可动电极1的矩形正表面的一条长边交叠形成三角形的交叠区域，此外，三角形单元固定电极2的一条边与矩形单元可动电极1的长边平行且三角形单元固定电极2的这条边在交叠区域外。单元固定电极2与单元可动电极1的电压差为V，三角形单元固定电极2底边的长度为m，三角形单元固定电极2的高度为f，单元可动电极1沿X轴方向的位移为x。由图1可见，单元可动电极1与单元固定电极2的交叠部分的形状为三角形，交叠区域的面积为s，当单元可动电极1沿X轴正方向产生位移x后，根据三角形的面积计算公式s=底边长度×高度/2，可得单元可动电极1与单元固定电极2的交叠区域的面积s为：
S=m•(e-x)•(e-x)/2/f
根据平板电容公式可得到电容大小为：
C=ζ•S/h=ζ•m•(e-x)•(e-x)/2/h/f
根据切向静电力公式得到切向静电力大小，即在X轴方向上的静电力大小为：
Fx=V2/2 · dC/dx= V2/2 · ζ/h · dS/dx
最终得到在X轴方向上的等效弹性系数为：
kx=-dFx/dx=-V2 · ζ · m/2/h/f
另如图2所示，单元固定电极2的正表面为三角形且仅与单元可动电极1的矩形正表面的一条长边交叠。并且，三角形单元固定电极2的一条边与矩形单元可动电极1的长边平行且三角形单元固定电极2的这条边与矩形单元可动电极1交叠。此时，单元可动电极1与单元固定电极2的交叠部分的形状为梯形，梯形交叠区域的面积为s。根据梯形的面积计算公式：s=(上底长度+下底长度)×高度/2，得到单元可动电极1与单元固定电极2的交叠区域的面积s为：
S={m+[f-(e-x)]•m/f}•(e-x)/2
根据平板电容公式可得到电容大小为：
C=ζ•S/h=ζ•{m+[f-(e-x)]•m/f}•(e-x)/2/h
根据切向静电力公式得到切向静电力大小，即在X轴方向上的静电力大小为：
Fx=V2/2 · dC/dx= V2/2 · ζ/h · dS/dx
最终得到在X轴方向上的等效弹性系数为：
kx=-dFx/dx=V2 · ζ · m/2/h/f
为方便说明本发明的技术方案，以下假设矩形单元可动电极1的宽度a为10μm，矩形单元可动电极1的长度b为2100μm，三角形单元固定电极2底边的长度m为2000μm，三角形单元固定电极2的高度f为10μm，单元可动电极1与单元固定电极2的间距h为1.5μm，单元固定电极2与单元可动电极1的电压差V为15V。如图1所示的情况下，引入的等效弹性系数为-0.1328N/m，该等效弹性系数为负且为常数；如图2所示的情况下，引入的等效弹性系数为0.1328N/m，而该引入的等效弹性系数为正且为常数。
如图3所示，单元固定电极2的正表面为直角三角形且仅与单元可动电极1的矩形正表面的一条长边交叠，直角三角形单元固定电极2的一条直角边与单元可动电极1的矩形正表面的长边平行，且直角三角形单元固定电极2的直角位于单元可动电极1与单元固定电极2的交叠区域外。单元固定电极2与单元可动电极1的电压差为V；单元可动电极1的位移为x，x为单元可动电极1在X轴方向上的位移，既可为正，也可为负；单元可动电极1与单元固定电极2的初始交叠宽度为e；直角三角形单元固定电极2的高度为d，直角三角形单元固定电极2的底边的长度为c；如图13所示，单元可动电极1与单元固定电极2的间距为h，在单元可动电极1沿X轴方向运动时，单元可动电极1与单元固定电极2的间距h不变。单元可动电极1与单元固定电极2的交叠部分的形状为直角三角形，交叠区域的面积为s。当单元可动电极1沿X轴正方向产生位移x后，该交叠部分的直角三角形底边长度为e-x，高度为(e-x)*d/c，根据三角形的面积计算公式: s=底边长度×高度/2，得到单元可动电极1与单元固定电极2的交叠区域的面积s为：
S=d•(e-x)•(e-x)/2/c
根据平板电容公式可得到电容大小为：
C=ζ•S/h=ζ•d•(e-x)•(e-x)/2/h/c
根据切向静电力公式得到切向静电力大小，即在X轴方向上的静电力大小为：
Fx=V2/2 · dC/dx= V2/2 · ζ/h · dS/dx
最终得到在X轴方向上的等效弹性系数为：
kx=-dFx/dx=-V2 · ζ · d/2/h/c
如图4所示，单元固定电极2的正表面为直角三角形，仅与单元可动电极1的矩形正表面的一条长边交叠，直角三角形单元固定电极2的一条直角边与单元可动电极1的矩形正表面的长边平行，且直角三角形单元固定电极2的直角位于单元可动电极1与单元固定电极2的交叠区域内。单元可动电极1与单元固定电极2的交叠形状为梯形，交叠区域的面积为s。当单元可动电极1沿X轴正方向产生位移x后，该梯形上底长度为：[c-(e-x)]•d/c，
下底长度为d，高度为e-x。根据梯形的面积计算公式：s=(上底长度+下底长度)×高度/2，得到单元可动电极1与单元固定电极2的交叠区域的面积s为：
S={d+[c-(e-x)]•d/c}•(e-x)/2
根据平板电容公式可得到电容大小为：
C=ζ•S/h=ζ•{d+[c-(e-x)]•d/c}•(e-x)/2/h
根据切向静电力公式得到切向静电力大小，即在X轴方向上的静电力大小为：
Fx=V2/2 · dC/dx= V2/2 · ζ/h · dS/dx
最终得到在X轴方向上的等效弹性系数为：
kx=-dFx/dx=V2 · ζ · d/2/h/c
为方便说明本发明的技术方案，以下假设矩形单元可动电极1的宽度a为10μm，矩形单元可动电极1的长度b为2100μm，直角三角形单元固定电极2底边的长度c为10μm，直角三角形单元固定电极2的高度d为2000μm，单元可动电极1与单元固定电极2的间距h为1.5μm，单元固定电极2与单元可动电极1的电压差V为15V。如图3所示的情况下，引入的等效弹性系数为-0.1328N/m，该等效弹性系数为负数且为常数；如图4所示的情况下，引入的等效弹性系数为0.1328N/m，而该引入的等效弹性系数为正数且为常数。
以上各示例中，在既定的结构下，即电容的结构参数和个数确定时，通过调节单元固定电极2与单元可动电极1的电压差V，就能在X轴方向上引入不同的等效弹性系数，从而调节微机械器件在X轴方向上总的弹性系数。
当单元电容为差分电容时，如图5至图8所示，其单边引入的等效弹性系数的计算方法与前述方法相同，而该差分电容整体引入的等效弹性系数则为单边引入的等效弹性系数两倍。其中，在既定的结构及单元固定电极2与单元可动电极1的电压差V为定值时，图5和图7引入的等效弹性系数为负数且为常数，图6和图8引入的等效弹性系数为正数且为常数。
当单元固定电极2的正表面为锯齿形时，如图9、10所示，各锯齿为三角形，每个锯齿仅与单元可动电极1的矩形正表面的一条长边交叠。每个锯齿与单元可动电极1的矩形正表面形成一个三角形锯齿电容结构，单个三角形锯齿电容结构所引入的等效弹性系数的计算方法与前述方法相同，整个电容结构引入的等效弹性系数为单元固定电极2的所有三角形锯齿电容结构引入的等效弹性系数之和。
同理，若单元可动电极1的正表面为三角形、而单元固定电极2的正表面为矩形（未在图中示出），则按上述计算方法可以知道，在既定的结构及单元固定电极2与单元可动电极1的电压差V为定值时，具有该结构的整个电容所引入的等效弹性系数或为负数或为正数，且均为常数。
图11和图12示出了单元可动电极1的正表面为锯齿形且各锯齿为梯形、同时单元固定电极2的正表面为矩形的本发明变面积电容结构的结构示意图。
如图11中的单元可动电极1的锯齿形正表面的各锯齿为梯形且各梯形锯齿仅与单元固定电极2的矩形正表面的一条长边交叠，交叠部分呈三角形，每个锯齿与单元固定电极2的矩形正表面形成一个梯形锯齿电容结构。此时，单个梯形锯齿电容结构所引入的等效弹性系数的计算方法与前述交叠部分呈三角形时的计算方法相同。在既定的结构及单元固定电极2与单元可动电极1的电压差V为定值时，整个电容结构引入的等效弹性系数为单元固定电极2的所有梯形锯齿电容结构引入的等效弹性系数之和，且或为负数或为正数，且均为常数。
如图12中的单元可动电极1的锯齿形正表面的各锯齿为梯形且各梯形锯齿仅与单元固定电极2的矩形正表面的一条长边交叠，交叠部分呈梯形，且梯形交叠部分的底边与所述矩形正表面的长边平行。每个锯齿与单元固定电极2的矩形正表面形成一个梯形锯齿电容结构。此时，单个梯形锯齿电容结构所引入的等效弹性系数的计算方法与前述交叠部分呈梯形时的计算方法相同。在既定的结构及单元固定电极2与单元可动电极1的电压差V为定值时，整个电容结构引入的等效弹性系数为单元固定电极2的所有梯形锯齿电容结构引入的等效弹性系数之和，且或为负数或为正数，且均为常数。
同理，单元固定电极2的正表面为锯齿形且各锯齿为梯形、而单元可动电极1的正表面为矩形的本发明变面积电容结构（未在图中示出）所引入的等效弹性系数为或为负数或为正数，在既定的结构及单元固定电极2与单元可动电极1的电压差V为定值时均为常数。
如图14-16所示，在本发明中弹性系数可调的变面积梳状栅电容加速度计，将前述变面积电容结构应用于传统的梳状栅电容加速度计中，栅条4即为单元可动电极1，电调谐叉指5即为电调谐电容的单元固定电极2，普通叉指6即为传统变面积电容的单元固定电极2，单元可动电极1的正表面是指与单元固定电极2正对的表面，单元固定电极2的正表面是指与单元可动电极1正对的表面。外框10固定在固定电极衬底8上，电调谐叉指5固定在固定电极衬底8上，质量块3与梁7相连，梁7与外框10相连，质量块3上的电信号通过引出电极9输入或输出，如图15所示。梁7可以为U型梁、直梁、折叠梁等，X轴方向为敏感方向。在电调谐叉指5与栅条4间施加一电压，即可对本发明变面积梳状栅电容加速度计敏感方向的弹性系数进行调节。
以下举例说明。在变面积梳状栅电容加速度计中，敏感质量块质量m为 5.1882×10-6kg ，弹性系数k为591.19N/m，根据谐振频率的计算公式 f=1/2/π · (k/m) 1/2 可得在未进行弹性系数的调整之前，加速度计敏感方向上的谐振频率为1.6989kHz。应用上述实施例中的参数设置，若应用电调谐电容使变面积梳状栅电容加速度计敏感方向上的弹性系数增大5.3120N/m，该变面积梳状栅电容加速度计敏感方向上的谐振频率可增大7.6156Hz；若应用电调谐电容使变面积梳状栅电容加速度计敏感方向上的弹性系数减小5.3120N/m，该变面积梳状栅电容加速度计敏感方向上的谐振频率可减小7.6499Hz。在本发明变面积梳状栅电容加速度计中，通过调节单元固定电极2与单元可动电极1的电压差V，就可以使谐振频率变得更大或更小；通过设计具有更小的弹性系数的梁结构，甚至可以使变面积梳状栅电容加速度计器件敏感方向上的弹性系数及谐振频率接近或等于0。
图17所示为本发明具有电调谐功能的变面积梳状栅电容陀螺的剖面结构示意图，将前述变面积电容结构应用于传统的梳状栅电容陀螺中，栅条13即为单元可动电极1，电调谐叉指14即为电调谐电容的单元固定电极2，普通叉指15即为传统变面积电容的单元固定电极2。外框20固定在固定电极衬底18上，电调谐叉指14和普通叉指15固定在固定电极衬底18上，驱动质量块11通过驱动梁16与外框20相连，检测质量块12通过检测梁17与驱动质量块11相连而成为驱动质量块11的一部分，电信号通过引出电极19输入或输出，如图18所示。驱动梁16与检测梁17除可以为U型梁、直梁、折叠梁等，而陀螺驱动方向和检测方向也是相对的，依设计而定。
如图17-19所示，X轴方向为驱动方向，Y轴方向为检测方向，驱动质量块11可在X轴方向上运动，检测质量块12可在X轴方向及Y轴方向上运动。驱动质量块11同检测质量块12一起在X轴方向上作谐振运动，当输入一固定角速度时，引起检测质量块12在Y轴方向上的同频率振动。驱动方向与检测方向的谐振频率越接近，引起的检测质量块12在Y轴方向上的振动幅度也越大，陀螺灵敏度也越高。传统的梳状栅电容陀螺无法对驱动或检测方向上的谐振频率进行调节，故陀螺性能无法得到有效地提高。而本发明梳状栅电容陀螺在驱动方向或检测方向上分布一定数量的电调谐变面积电容，可以根据需要对驱动方向或检测方向的弹性系数进行调节从而调节驱动或检测方向的谐振频率。
以下举例说明。在梳状栅电容陀螺中，检测质量块12的质量为 5.1882×10-6kg ，驱动质量块11的质量为 1.0227×10-5kg ，检测方向的弹性系数为591.19N/m，驱动方向的弹性系数为1145N/m，则未进行电调谐之前，检测方向的谐振频率为1699Hz，驱动方向的谐振频率为1684Hz。通过上述电容结构在检测方向引入一值为-10.36N/m的弹性系数，可将检测方向的谐振频率调节至与驱动方向相同，或在驱动方向引入一值为20.5N/m的弹性系数，可将驱动方向的谐振频率调节至与检测方向相同，也可同时在驱动或检测方向上引入一定的弹性系数，使驱动与检测方向的谐振频率均调节至同一个频率，从而有效地提高陀螺的灵敏度。
综上可见，通过调节本发明梳状栅电容陀螺中驱动或检测方向上的电调谐变面积电容的单元固定电极2与单元可动电极1的电压差的大小，即可实现对梳状栅电容陀螺驱动或检测方向上弹性系数的调节，从而调节驱动或检测方向上的谐振频率，简单、方便。

Claims (12)

  1. 一种变面积电容结构，在每个电容单元中包括可动电极和固定电极，所述可动电极的正表面与所述固定电极的正表面相互平行，其特征是：所述可动电极的正表面为矩形且固定电极的正表面为三角形或锯齿形，或者所述可动电极的正表面为三角形或锯齿形且固定电极的正表面为矩形；所述三角形正表面仅与所述矩形正表面的一条长边交叠。
  2. 根据权利要求 1 所述的变面积电容结构，其特征是：所述锯齿形正表面的锯齿为三角形且所述三角形锯齿仅与所述矩形正表面的一条长边交叠。
  3. 根据权利要求 1 所述的变面积电容结构，其特征是：所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈三角形。
  4. 根据权利要求 1 所述的变面积电容结构，其特征是：所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈梯形，所述梯形交叠部分的底边与所述矩形正表面的长边平行。
  5. 一种弹性系数可调的 梳状栅电容加速度计，其特征是：在加速度计的敏感方向上分布有用来调节弹性系数的电调谐变面积电容，所述电调谐变面积电容的每个单元电容中，可动电极的正表面与固定电极的正表面相互平行，所述可动电极的正表面为矩形且固定电极的正表面为三角形或锯齿形，或者所述可动电极的正表面为三角形或锯齿形且固定电极的正表面为矩形；所述三角形正表面仅与所述矩形正表面的一条长边交叠。
  6. 根据权利要求 5 所述的弹性系数可调的梳状栅电容加速度计，其特征是：所述锯齿形正表面的锯齿为三角形且所述三角形锯齿仅与所述矩形正表面的一条长边交叠。
  7. 根据权利要求 5 所述的弹性系数可调的梳状栅电容加速度计，其特征是：所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈三角形。
  8. 根据权利要求 5 所述的弹性系数可调的梳状栅电容加速度计，其特征是：所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈梯形，所述梯形交叠部分的底边与所述矩形正表面的长边平行。
  9. 一种谐振频率可调的梳状栅电容陀螺，其特征是：在所述陀螺的驱动或检测方向分布有电调谐变面积电容，在所述电调谐变面积电容的每个单元电容中，可动电极的正表面与固定电极的正表面相互平行，其特征是：所述可动电极的正表面为矩形且固定电极的正表面为三角形或锯齿形，或者所述可动电极的正表面为三角形或锯齿形且固定电极的正表面为矩形；所述三角形正表面仅与所述矩形正表面的一条长边交叠。
  10. 根据权利要求 9 所述的谐振频率可调的梳状栅电容陀螺，其特征是：所述锯齿形正表面的锯齿为三角形且所述三角形锯齿仅与所述矩形正表面的一条长边交叠。
  11. 根据权利要求 9 所述的谐振频率可调的梳状栅电容陀螺，其特征是：所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈三角形。
  12. 根据权利要求 9 所述的谐振频率可调的梳状栅电容陀螺，其特征是：所述锯齿形正表面的锯齿为梯形且所述梯形锯齿仅与所述矩形正表面的一条长边交叠，交叠部分呈梯形，所述梯形交叠部分的底边与所述矩形正表面的长边平行。
PCT/CN2010/074340 2010-04-20 2010-06-23 变面积电容结构、梳状栅电容加速度计以及梳状栅电容陀螺 WO2011130941A1 (zh)

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