WO2023151129A1 - 一种三轴压阻式加速度计 - Google Patents

一种三轴压阻式加速度计 Download PDF

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Publication number
WO2023151129A1
WO2023151129A1 PCT/CN2022/077535 CN2022077535W WO2023151129A1 WO 2023151129 A1 WO2023151129 A1 WO 2023151129A1 CN 2022077535 W CN2022077535 W CN 2022077535W WO 2023151129 A1 WO2023151129 A1 WO 2023151129A1
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Prior art keywords
axis
piezoresistors
axis direction
compound cantilever
distributed
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PCT/CN2022/077535
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English (en)
French (fr)
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维尼·辛格
陈林峰
潘峰
魏锦烨
陈锦华
李敏
韩文都
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湖州久鼎电子有限公司
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Publication of WO2023151129A1 publication Critical patent/WO2023151129A1/zh

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    • 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
    • G01P15/12—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 alteration of electrical resistance

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  • the invention relates to the field of sensors, in particular to a three-axis piezoresistive accelerometer.
  • Triaxial piezoresistive accelerometers usually use the same mass to sense acceleration signals in three directions. When the mass senses the acceleration in different directions, the resistance values of the piezoresistors at different positions will change, so that the output voltage of the Wheatstone bridge composed of piezoresistors will change, and then the magnitude and magnitude of the acceleration will be detected. direction.
  • This single-mass triaxial piezoresistive accelerometer has the advantages of small size, light weight, low cost, and low power consumption, and has been developed rapidly in recent years.
  • the purpose of the present invention is to provide a three-axis piezoresistive accelerometer to solve the problems raised in the background art.
  • the technical solution of the present invention is: a kind of triaxial piezoresistive accelerometer, it is characterized in that, comprises:
  • the mass blocks are suspended at the center of the support frame by the compound cantilever beams, and the mass blocks are respectively connected to the support frame by the compound cantilever beams in the X-axis direction and the Y-axis direction perpendicular to each other ;
  • the upper surface of the mass block is located on a plane determined by the X-axis and the Y-axis, and the Z-axis is perpendicular to the upper surface of the mass block;
  • the multiple piezoresistors have the same resistance value under no stress state
  • each of the compound cantilever beams there is at least one piezoresistor arranged in a direction parallel to the X axis, and at least one piezoresistor arranged in a direction parallel to the Y axis;
  • the X-axis, the Y-axis and the Z-axis are three axes in a three-dimensional Cartesian coordinate system, and the coordinate system takes the center of the upper surface of the proof mass as a coordinate origin.
  • the multiple compound cantilever beams include four compound cantilever beams, which are respectively located in the negative direction of the X axis, the positive direction of the X axis, the negative direction of the Y axis, and the positive direction of the Y axis.
  • the compound cantilever beam includes a single-end portion, a double-end portion, and an intermediate portion connecting the single-end portion and the double-end portion;
  • the single-end portion is connected to the mass block, and the double-end portion is connected to the supporting frame.
  • piezoresistors are symmetrically distributed on the four compound cantilever beams, and six piezoresistors are distributed on each of the compound cantilever beams.
  • piezoresistors are distributed on the compound cantilever beam, wherein:
  • the two piezoresistors are located at a position close to the supporting frame of the double-ended part;
  • the two piezoresistors are located at the position of the single-ended part close to the proof mass
  • the two piezoresistors are located at the position where the middle part is close to the connection with the double-terminal part, and are located at a side of the middle part that is close to the mass block.
  • a plurality of metal pads distributed on the support frame wherein the plurality of metal pads are electrically connected to the piezoresistors on the compound cantilever beam through metal leads.
  • the supporting frame Preferably, twenty-four metal pads are distributed on the supporting frame;
  • Each side of the support frame has six metal pads
  • the six metal pads on each side of the supporting frame are electrically connected to the six piezoresistors on the adjacent compound cantilever beams through metal leads in one-to-one correspondence.
  • the mass block there are a plurality of limit modules, wherein an anti-overload gap in the X-axis direction and the Y-axis direction is left between each limit module and the mass block.
  • each inner corner of the supporting frame has one limiting module.
  • the upper cover plate and the lower cover plate respectively located above and below the supporting frame, wherein an anti-overload gap in the Z-axis direction is left between the mass block and the upper cover plate and the lower cover plate respectively.
  • the Wheatstone bridge for measuring the X-axis acceleration component includes the piezoresistors distributed along the X-axis direction on the two compound cantilever beams in the X-axis direction, and also includes the piezoresistors on the Y-axis The piezoresistors distributed along the X-axis direction on the two compound cantilever beams in the X-axis direction.
  • the Wheatstone bridge used to measure the Y-axis acceleration component includes the piezoresistors distributed along the Y-axis direction on the two compound cantilever beams in the Y-axis direction, and also includes the piezoresistors in the X-axis direction The piezoresistors distributed along the Y-axis direction on the two compound cantilever beams.
  • the Wheatstone bridge used to measure the Z-axis acceleration component includes the piezoresistors distributed on the single-ended part of the composite cantilever beam, and the double-ended piezoresistors distributed on the composite cantilever beam. end portion of the varistor.
  • piezoresistors are distributed on the compound cantilever beam, wherein:
  • the two piezoresistors are located at a position close to the supporting frame of the double-ended part;
  • the two piezoresistors are located at the position of the single-ended part close to the proof mass
  • the two piezoresistors are located at the position where the middle part is close to the connection with the single-end part, and are located at a side of the middle part that is close to the mass block.
  • the Wheatstone bridge for measuring the X-axis acceleration component includes the piezoresistors distributed along the X-axis direction on the two compound cantilever beams in the X-axis direction, and also includes the piezoresistors on the Y-axis The piezoresistors distributed along the X-axis direction on the two compound cantilever beams in the X-axis direction.
  • the Wheatstone bridge used to measure the Y-axis acceleration component includes the piezoresistors distributed along the Y-axis direction on the two compound cantilever beams in the Y-axis direction, and also includes the piezoresistors in the X-axis direction The piezoresistors distributed along the Y-axis direction on the two compound cantilever beams.
  • the Wheatstone bridge used to measure the Z-axis acceleration component includes the piezoresistors distributed on the single-ended part of the composite cantilever beam, and the double-ended piezoresistors distributed on the composite cantilever beam. end portion of the varistor.
  • the present invention when measuring the acceleration components of the X-axis and the Y-axis, not only the compressive stress and the tensile stress directly caused by the component are used, but also the shear stress caused by the component is used. Compressive stress and tensile stress.
  • the compound cantilever beam used in the present invention has better rigidity than the currently commonly used cantilever beam, which is helpful for the reset of the mass block, reduces system errors, and improves measurement accuracy.
  • the shear stress in the direction of the Y-axis (X-axis) caused by the acceleration component of the X-axis (Y-axis) is mainly concentrated in the middle part of the compound cantilever beam, reducing the impact of the shear stress on the single-end part and double-end of the compound cantilever beam.
  • the influence of the piezoresistor at the end part reduces the inter-axis coupling of the accelerometer.
  • Fig. 1 is a schematic structural view of a triaxial piezoresistive accelerometer provided by an embodiment of the present invention
  • Fig. 2 is the sectional view of Fig. 1 along A-A ' direction;
  • Figure 3 is a partially enlarged view of Figure 1;
  • Fig. 4 is the wiring diagram of varistor in Fig. 3;
  • Fig. 5 is a Wheatstone bridge diagram for measuring the X-axis acceleration component composed of piezoresistor connections provided by an embodiment of the present invention
  • Fig. 6 is a Wheatstone bridge diagram for measuring the Y-axis acceleration component composed of piezoresistor connections provided by an embodiment of the present invention
  • Fig. 7 is the Wheatstone bridge diagram that detects the Z-axis direction acceleration component that is formed by piezoresistor connection provided by the embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of another three-axis piezoresistive accelerometer provided by an embodiment of the present invention.
  • FIG. 9 is a partially enlarged view of FIG. 8 .
  • 1 is the support frame
  • 2 is the mass block
  • 3 is the compound cantilever beam
  • 31 is the compound cantilever beam located in the negative direction of the X axis
  • 32 is the compound cantilever beam located in the positive direction of the X axis
  • 33 is located in the negative direction of the Y axis
  • 34 is the compound cantilever beam located in the positive direction of the Y axis
  • 301 is the single-end part of the compound cantilever beam
  • 302 is the middle part of the compound cantilever beam
  • 303 is the double-end part of the compound cantilever beam
  • 4 is the limit Module
  • 5 is the upper cover
  • 6 is the lower cover
  • R1-R24 are varistors
  • 7 is the metal pad
  • 8 is the metal lead.
  • the current single-mass triaxial piezoresistive accelerometer has the problem of inter-axial coupling.
  • Fig. 1 is a schematic structural view of a three-axis piezoresistive accelerometer provided by an embodiment of the present invention
  • Fig. 2 is a sectional view along AA' of Fig. 1
  • Fig. 3 is a partial enlarged view of Fig. 1
  • Fig. 4 is The wiring diagram of the varistor in Figure 3.
  • the three-axis piezoresistive accelerometer includes a support frame 1 , a proof mass 2 , and a compound cantilever beam 3 .
  • the mass block 2 is suspended at the center of the support frame l through the compound cantilever beam 3 .
  • the mass block 2 is connected to the support frame 1 through the compound cantilever beam 3 in the X-axis direction and the Y-axis direction which are perpendicular to each other.
  • the upper surface of the mass block 2 is located on a plane defined by the X axis and the Y axis, and the Z axis is perpendicular to the upper surface of the mass block 2 .
  • the X axis, Y axis and Z axis are three axes in a three-dimensional Cartesian coordinate system.
  • the coordinate system takes the center of the upper surface of the mass block 2 as the coordinate origin.
  • the shape of the upper surface of the proof mass 2 in this embodiment is a square.
  • the shape of the upper surface of the proof mass 2 can be other centrosymmetric shapes, such as octagon and circle.
  • the compound cantilever beam 3 includes four compound cantilever beams located between the supporting frame 1 and the mass block 2, which are respectively compound cantilever beam 31, compound cantilever beam 32, compound cantilever beam 33, and compound cantilever beam 34.
  • the compound cantilever beam 31 is located in the negative direction of the X axis
  • the compound cantilever beam 32 is located in the positive direction of the X axis
  • the compound cantilever beam 33 is located in the negative direction of the Y axis
  • the compound cantilever beam 34 is located in the positive direction of the Y axis.
  • the three-axis piezoresistive accelerometer also includes a plurality of piezoresistors symmetrically distributed on the four compound cantilever beams.
  • the resistance values of the multiple piezoresistors are equal in a state of no stress.
  • the same number of piezoresistors are distributed on each compound cantilever beam.
  • On each compound cantilever beam there is at least one piezoresistor arranged in a direction parallel to the X axis, and at least one piezoresistor arranged in a direction parallel to the Y axis.
  • twenty-four piezoresistors R1-R24 are symmetrically distributed on the four compound cantilever beams, and six piezoresistors are distributed on each compound cantilever beam 3 .
  • the compound cantilever beam includes a single-end portion 301 , a double-end portion 303 , and a middle portion 302 connecting the single-end portion 301 and the double-end portion 303 .
  • the present invention does not limit the position of the middle part 302 in the compound cantilever beam, that is, does not limit and connect the length ratio of the single-end part 301 and the double-end part 303 .
  • the single-end portion 301 of the compound cantilever beam 3 is connected to the proof mass 2
  • the double-end portion 303 of the compound cantilever beam 3 is connected to the supporting frame 1 .
  • Six piezoresistors (R1, R2, R9, R10, R17 and R18) are distributed on the compound cantilever beam 31 located in the negative direction of the X axis. Wherein, R1, R2, R17 and R18 are arranged along a direction parallel to the X axis, and R9 and R10 are arranged along a direction parallel to the Y axis.
  • R1 and R2 are located at the position where the double-end part is close to the supporting frame 1
  • R17 and R18 are located at the position where the single-end part is close to the mass block 2
  • R9 and R10 are located at the position where the middle part 302 is close to the connection with the double-end part, and are at the position where the middle part 302 is close to One side of mass block 2.
  • Six piezoresistors (R5, R6, R13, R14, R21 and R22) are distributed on the compound cantilever beam 32 located in the positive direction of the X-axis. Wherein, R5, R6, R21 and R22 are arranged along a direction parallel to the X axis, and R13 and R14 are arranged along a direction parallel to the Y axis.
  • R5 and R6 are located at the position where the double-end part is close to the supporting frame 1
  • R21 and R22 are located at the position where the single-end part is close to the mass block 2
  • R13 and R14 are located at the position where the middle part 302 is close to the connection with the double-end part, and are at the position where the middle part 302 is close to One side of mass block 2.
  • Six piezoresistors (R3, R4, R11, R12, R19 and R20) are distributed on the compound cantilever beam 33 located in the negative direction of the Y axis. Wherein, R3, R4, R19 and R20 are arranged along a direction parallel to the Y axis, and R11 and R12 are arranged along a direction parallel to the X axis.
  • R3 and R4 are located at the position where the double-end part is close to the supporting frame 1
  • R19 and R20 are located at the position where the single-end part is close to the mass block 2
  • R11 and R12 are located at the position where the middle part 302 is close to the connection with the double-end part, and are at the position where the middle part 302 is close to One side of mass block 2.
  • Six piezoresistors (R7, R8, R15, R16, R23 and R24) are distributed on the compound cantilever beam 344 located in the positive direction of the Y axis.
  • R7, R8, R23 and R24 are arranged along a direction parallel to the Y axis, and R15 and R16 are arranged along a direction parallel to the X axis.
  • R7 and R8 are located at the position where the double-end part is close to the supporting frame 1
  • R23 and R24 are located at the position where the single-end part is close to the mass block 2
  • R15 and R16 are located at the position where the middle part 302 is close to the connection with the double-end part, and are at the position where the middle part 302 is close to One side of mass block 2.
  • the three-axis piezoresistive accelerometer also includes a plurality of metal pads distributed on the support frame l.
  • the metal pad is electrically connected to the piezoresistor on the compound cantilever beam through a metal lead.
  • twenty-four metal pads are distributed on the supporting frame 1.
  • the six metal pads on each side of the support frame 1 are electrically connected to the six piezoresistors on the adjacent compound cantilever beam 3 through metal leads 8 in one-to-one correspondence.
  • the three-axis piezoresistive accelerometer also includes a limit module. As shown in FIG. 1 , each inner corner of the supporting frame 1 has a limiting module 4 . There is an anti-overload gap in the X-axis direction and the Y-axis direction between each limit module 4 and the mass block 2 . When the acceleration component in one direction exceeds the preset maximum load, the limit module can prevent the mass block 2 from moving further in this direction, so as to protect the accelerometer.
  • the three-axis piezoresistive accelerometer also includes an upper cover plate 5 and a lower cover plate 6 respectively located above and below the supporting frame l. There is an anti-overload gap in the Z-axis direction between the mass block 2 and the upper cover plate 5 and the lower cover plate 6 respectively.
  • the upper cover plate 5 or the lower cover plate 6 can prevent further movement of the mass block 2 in the Z-axis direction, thereby protecting the accelerometer.
  • the acceleration of the mass 2 of the accelerometer has components in the X-axis, Y-axis and Z-axis. Without loss of generality, the components of the acceleration of the mass block 2 on the X-axis, Y-axis and Z-axis are all positive values.
  • the Wheatstone bridge used to measure the acceleration component of the X axis includes piezoresistors distributed along the X-axis direction on two compound cantilever beams in the X-axis direction, and also includes piezoresistors distributed along the X-axis direction on the two compound cantilever beams in the Y-axis direction Varistor.
  • the Wheatstone bridge used to measure the Y-axis acceleration component includes piezoresistors distributed along the Y-axis direction on two compound cantilever beams in the Y-axis direction, and also includes piezoresistors distributed along the Y-axis direction on two compound cantilever beams in the X-axis direction. Varistor.
  • Fig. 5 is a diagram of a Wheatstone bridge for measuring X-axis acceleration components composed of piezoresistor connections provided by an embodiment of the present invention.
  • the varistor R5 and the varistor R18 are connected in series to form the first bridge arm of the Wheatstone bridge, the varistor R1 and the varistor R22 are connected in series to form the second bridge arm of the Wheatstone bridge, and the varistor R11
  • the third bridge arm of the Wheatstone bridge is formed in series with the piezoresistor R16, and the fourth bridge arm of the Wheatstone bridge is formed in series with the piezoresistor R12 and the piezoresistor R15.
  • the piezoresistor R5 on the first bridge arm and the piezoresistor R1 on the second bridge arm are connected on an input end of this Wheatstone bridge
  • the piezoresistor R16 on the 3rd bridge arm and the 4th bridge arm The piezoresistor R15 on the arm is connected to the other input of the Wheatstone bridge.
  • the piezoresistor R18 on the first bridge arm and the piezoresistor Rl1 on the third bridge arm are connected on an output end of the Wheatstone bridge
  • the piezoresistor R22 on the second bridge arm and the fourth bridge arm The piezoresistor R12 is connected to the other output terminal of the Wheatstone bridge.
  • the output signal V out in FIG. 5 reflects the magnitude of the X-axis acceleration component.
  • the deformation caused by shear stress can be ignored, and it can be considered that the resistance values of R17, R18, R21, R22, R1, R2, R5 and R6 do not change.
  • the shear stress deforms the middle portion 302 of the compound cantilever beams 31 and 32 , so that the resistance values of the piezoresistors R10 and R13 increase, and the resistance values of the piezoresistors R9 and R14 decrease.
  • the Y-axis acceleration component does not affect the resistance of each piezoresistor in Figure 5, and does not affect the output signal Vout in Figure 5, so the coupling between the X-axis and the Y-axis can be ignored.
  • the Z-axis acceleration component does not affect the resistance of each piezoresistor in FIG. 5 , and does not affect the output signal V out in FIG. 5 , so the coupling between the X-axis and the Z-axis can be ignored.
  • FIG. 6 is a diagram of a Wheatstone bridge for measuring Y-axis acceleration components composed of piezoresistor connections provided by an embodiment of the present invention.
  • the varistor R7 and the varistor R20 are connected in series to form the first bridge arm of the Wheatstone bridge, the varistor R3 and the varistor R24 are connected in series to form the second bridge arm of the Wheatstone bridge, and the varistor R10
  • the third bridge arm of the Wheatstone bridge is formed in series with the varistor R13
  • the fourth bridge arm of the Wheatstone bridge is formed in series with the varistor R9 and the varistor R14.
  • the piezoresistor R7 on the first bridge arm and the piezoresistor R3 on the second bridge arm are connected on an input end of this Wheatstone bridge
  • the piezoresistor R13 on the 3rd bridge arm and the 4th bridge arm The piezoresistor R14 on the arm is connected to the other input of the Wheatstone bridge.
  • the varistor R20 on the first bridge arm and the varistor R10 on the third bridge arm are connected on an output end of the Wheatstone bridge
  • the varistor R9 is connected to the other output of the Wheatstone bridge.
  • the output signal V out in FIG. 6 reflects the magnitude of the Y-axis acceleration component, and the coupling between the Y-axis and the X-axis can be ignored, and the coupling between the Y-axis and the Z-axis can be ignored.
  • the Wheatstone bridge for measuring the Z-axis acceleration component includes piezoresistors distributed on the single-end portion 301 of the composite cantilever beam 301 and piezoresistors distributed on the double-end portion 303 of the composite cantilever beam 301 .
  • FIG. 7 is a diagram of a Wheatstone bridge composed of piezoresistor connections for detecting acceleration components in the Z-axis direction provided by an embodiment of the present invention.
  • the varistor R2 and the varistor R6 are connected in series to form the first bridge arm of the Wheatstone bridge, the varistor R17 and the varistor R21 are connected in series to form the second bridge arm of the Wheatstone bridge, and the varistor R19
  • the third bridge arm of the Wheatstone bridge is formed in series with the varistor R23
  • the fourth bridge arm of the Wheatstone bridge is formed in series with the varistor R4 and the varistor R8.
  • the piezoresistor R2 on the first bridge arm and the piezoresistor R17 on the second bridge arm are connected on an input end of the Wheatstone bridge
  • the piezoresistor R8 on the arm is connected to the other input of the Wheatstone bridge.
  • the piezoresistor R6 on the first bridge arm and the piezoresistor R19 on the third bridge arm are connected on an output end of the Wheatstone bridge
  • the varistor R4 is connected to the other output of the Wheatstone bridge.
  • the output signal V out in FIG. 7 reflects the magnitude of the Z-axis acceleration component, and the coupling between the Z-axis and the X-axis can be ignored, and the coupling between the Z-axis and the Y-axis can be ignored.
  • the supporting frame 1, the mass block 2 and the compound cantilever beam 3 between them are made of SOI sheet material through the existing standard piezoresistive semiconductor micro-machining process.
  • the twenty-four piezoresistors arranged on the elastic beam arm 3 are processed through the existing diffusion or ion implantation process.
  • the upper cover plate 5 and the lower cover plate 6 are made of Pyrex glass, and the upper cover plate 5 and the lower cover plate 6 are connected to the supporting frame 1 through electrostatic bonding.
  • the overall size of the accelerometer is: about 6000 ⁇ m in length, about 6000 ⁇ m in width, and about 2000 ⁇ m in height.
  • the side length of the mass block is about 2400 ⁇ m, and the thickness is about 300 ⁇ m;
  • the beam length of the compound cantilever beam is about 800 ⁇ m,
  • the beam width of the single-end part is about 200 ⁇ m, and the beam width of the double-end part is about 1200 ⁇ m.
  • the thickness is about 20 ⁇ m;
  • the side length of the supporting frame is about 4000 ⁇ m, and the width of the frame is about 1000 ⁇ m.
  • the compound cantilever beam used in this embodiment has better rigidity than the currently commonly used cantilever beam, which is helpful for the reset of the mass block, reduces system errors, and improves measurement accuracy.
  • the shear stress in the direction of the Y-axis (X-axis) caused by the acceleration component of the X-axis (Y-axis) is mainly concentrated in the middle part of the compound cantilever beam, reducing the impact of the shear stress on the single-end part and double-end of the compound cantilever beam.
  • the influence of the piezoresistor at the end part reduces the inter-axis coupling of the accelerometer.
  • FIG. 8 is a schematic structural diagram of another three-axis piezoresistive accelerometer provided by an embodiment of the present invention
  • FIG. 9 is a partially enlarged view of FIG. 8
  • the compound cantilever beam 3 is a compound cantilever beam, including a single-end part 301 , a double-end part 303 and a middle part 302 .
  • the single-end portion of the compound cantilever beam 3 is connected to the proof mass
  • the double-end portion of the compound cantilever beam 3 is connected to the support frame 1.
  • R1, R2, R9, R10, R17 and R18 are distributed on the compound cantilever beam 31 located in the negative direction of the X axis.
  • R1 and R2 are located at the position where the double-end part is close to the supporting frame 1
  • R17 and R18 are located at the position where the single-end part is close to the mass block 2
  • R9 and R10 are located at the position where the middle part is close to the connection with the single-end part, and are in the middle part close to One side of mass block 2.
  • Six piezoresistors (R5, R6, R13, R14, R21 and R22) are distributed on the compound cantilever beam 32 located in the positive direction of the X-axis.
  • R5 and R6 are located at the position where the double-end part is close to the supporting frame 1
  • R21 and R22 are located at the position where the single-end part is close to the mass block 2
  • R13 and R14 are located at the position where the middle part is close to the connection with the single-end part, and are in the middle part close to One side of mass block 2.
  • Six piezoresistors (R3, R4, R11, R12, R19 and R20) are distributed on the compound cantilever beam 33 located in the negative direction of the Y axis.
  • R3 and R4 are located at the position where the double-end part is close to the supporting frame 1
  • R19 and R20 are located at the position where the single-end part is close to the mass block 2
  • R11 and R12 are located at the position where the middle part is close to the connection with the single-end part, and are in the middle part close to One side of mass block 2.
  • Six piezoresistors (R7, R8, R15, R16, R23 and R24) are distributed on the compound cantilever beam 34 located in the positive direction of the Y axis.
  • R7 and R8 are located at the position where the double-end part is close to the supporting frame 1
  • R23 and R24 are located at the position where the single-end part is close to the mass block 2
  • R15 and R16 are located at the position where the middle part is close to the connection with the single-end part, and are in the middle part close to One side of mass block 2.
  • the output signal Vout in Figure 5 reflects the magnitude of the X-axis acceleration component, and the coupling between the X-axis and the Y-axis can be ignored , the coupling between the X-axis and the Z-axis can be ignored;
  • the output signal V out in Figure 6 reflects the magnitude of the acceleration component of the Y-axis, and the coupling between the Y-axis and the X-axis can be ignored, and the coupling between the Y-axis and the Z-axis The coupling can be ignored;
  • the output signal Vout in Figure 7 reflects the magnitude of the Z-axis acceleration component, and the coupling between the Z-axis and the X-axis can be ignored, and the coupling between the Z-axis and the Y-axis can be ignored.
  • the compound cantilever beam used in this embodiment has better rigidity than the currently commonly used cantilever beam, which is helpful for the reset of the mass block, reduces system errors, and improves measurement accuracy.
  • the shear stress in the direction of the Y-axis (X-axis) caused by the acceleration component of the X-axis (Y-axis) is mainly concentrated in the middle part of the compound cantilever beam, reducing the impact of the shear stress on the single-end part and double-end of the compound cantilever beam.
  • the influence of the piezoresistor at the end part reduces the inter-axis coupling of the accelerometer.

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Abstract

一种三轴压阻式加速度计，包括：支撑边框（1）；质量块（2）；多个复式悬臂梁（3）；分布于多个复式悬臂梁（3）上的多个压敏电阻（R1-R24），其中，质量块（2）通过复式悬臂梁（3）悬于支撑边框（1）的中心位置，质量块（2）在相互垂直的X轴方向和Y轴方向上，分别通过复式悬臂梁（3）与支撑边框（1）连接。该复式悬臂梁（3）较常用的悬臂梁具有更好的刚性，有助于质量块（2）的复位，减少了系统误差，提高了测量准确性。

Description

一种三轴压阻式加速度计 技术领域
本发明涉及传感器领域，特别涉及一种三轴压阻式加速度计。
背景技术
随着微机电(MEMS)技术的发展和推广，加速度计正在向微型化和集成化的方向发展。压阻式加速度计由于具有灵敏度高、稳定性好、动态响应特性好、批量生产成本低、与半导体集成电路工艺兼容性好等优点，得到了广泛青睐。三轴压阻式加速度计通常利用同一个质量块来感测三个方向的加速度信号。当质量块感测到不同方向的加速度时，不同位置的压敏电阻的阻值会发生变化，从而使由压敏电阻构成的惠斯通电桥的输出电压发生变化，进而检测到加速度的大小和方向。这种单质量块三轴压阻式加速度计具有体积小、重量轻、成本低和功耗低等优点，近年来得到了快速发展。
然而，目前单质量块三轴压阻式加速度计存在轴间耦合的问题。如何有效减少轴间耦合是三轴压阻式加速度计设计、生产和应用中急需解决的问题。
发明内容
本发明的目的是提供一种三轴压阻式加速度计，以解决背景技术中提出的问题。
本发明的技术解决方案是：一种三轴压阻式加速度计，其特征在于，包括：
支撑边框；
质量块；
多个复式悬臂梁；
分布于所述多个复式悬臂梁上的多个压敏电阻，
其中：
所述质量块通过所述复式悬臂梁悬于所述支撑边框的中心位置，所述质量块在相互垂直的X轴方向和Y轴方向上，分别通过所述复式悬臂梁与所述支撑边框连接；
所述质量块的上表面位于由所述X轴和所述Y轴确定的平面，Z轴垂直 于所述质量块的上表面；
所述多个压敏电阻在没有应力的状态下，阻值相等；
每根所述复式悬臂梁上分布有相同数量的所述压敏电阻；
每根所述复式悬臂梁上，至少有一个沿平行于所述X轴方向设置的所述压敏电阻，至少有一个沿平行于所述Y轴方向设置的所述压敏电阻；
所述X轴、所述Y轴和所述Z轴为三维直角坐标系中的三个轴，所述坐标系以所述质量块的所述上表面的中心为坐标原点。
作为优选，所述多个复式悬臂梁包括四根复式悬臂梁，分别位于X轴负方向，X轴正方向，Y轴负方向，和Y轴正方向。
作为优选，所述复式悬臂梁包括单端部分、双端部分，和连接所述单端部分和所述双端部分的中间部分；
所述单端部分与所述质量块连接，所述双端部分与所述支撑边框连接。
作为优选，所述四根复式悬臂梁上对称分布有二十四个的所述压敏电阻，每根所述复式悬臂梁上分布有六个所述压敏电阻。
作为优选，所述复式悬臂梁上分布有六个压敏电阻，其中：
二个所述压敏电阻位于所述双端部分靠近所述支撑边框的位置；
二个所述压敏电阻位于所述单端部分靠近所述质量块的位置；
二个所述压敏电阻位于所述中间部分靠近与所述双端部分连接的位置，并处于所述中间部分靠近所述质量块的一侧。
作为优选，分布在所述支撑边框上的多个金属焊盘，其中，所述多个金属焊盘与所述复式悬臂梁上的所述压敏电阻通过金属引线电连接。
作为优选，所述支撑边框上分布有二十四个所述金属焊盘；
所述撑边框的每条边有六个金属焊盘；
所述支撑边框的每条边上的所述六个金属焊盘与相邻的所述复式悬臂梁上的所述六个压敏电阻通过金属引线一一对应电连接。
作为优选，多个限位模块，其中，每个所述限位模块与所述质量块之间留有所述X轴方向和所述Y轴方向的抗过载间隙。
作为优选，所述支撑边框的每个内角有一个所述限位模块。
作为优选，分别位于所述支撑边框的上方与下方的上盖板与下盖板，其中所述质量块分别与上盖板和下盖板之间留有Z轴方向抗过载间隙。
作为优选，用于测量X轴加速度分量的惠斯通电桥，包括在所述X轴方向的两个所述复式悬臂梁上沿所述X轴方向分布的所述压敏电阻，还包括在所述Y轴方向的两个所述复式悬臂梁上沿所述X轴方向分布的所述压敏电阻。
用于测量Y轴加速度分量的惠斯通电桥，包括在所述Y轴方向的两个所述复式悬臂梁上沿所述Y轴方向分布的所述压敏电阻，还包括在所述X轴方向的两个所述复式悬臂梁上沿所述Y轴方向分布的所述压敏电阻。
作为优选，用于测量Z轴加速度分量的惠斯通电桥，包括分布于所述复合悬臂梁的所述单端部分上的所述压敏电阻，和分布于所述复合悬臂梁的所述双端部分上的所述压敏电阻。
作为优选，所述复式悬臂梁上分布有六个压敏电阻，其中：
二个所述压敏电阻位于所述双端部分靠近所述支撑边框的位置；
二个所述压敏电阻位于所述单端部分靠近所述质量块的位置；
二个所述压敏电阻位于所述中间部分靠近与所述单端部分连接的位置，并处于所述中间部分靠近所述质量块的一侧。
作为优选，用于测量X轴加速度分量的惠斯通电桥，包括在所述X轴方向的两个所述复式悬臂梁上沿所述X轴方向分布的所述压敏电阻，还包括在所述Y轴方向的两个所述复式悬臂梁上沿所述X轴方向分布的所述压敏电阻。
用于测量Y轴加速度分量的惠斯通电桥，包括在所述Y轴方向的两个所述复式悬臂梁上沿所述Y轴方向分布的所述压敏电阻，还包括在所述X轴方向的两个所述复式悬臂梁上沿所述Y轴方向分布的所述压敏电阻。
作为优选，用于测量Z轴加速度分量的惠斯通电桥，包括分布于所述复合悬臂梁的所述单端部分上的所述压敏电阻，和分布于所述复合悬臂梁的所述双端部分上的所述压敏电阻。
本发明有益效果是：
与现有技术相比，本发明中，在测量X轴和Y轴的加速度分量时，不仅利用了该分量直接引起的压缩应力和拉伸应力，还利用了该分量引起的剪切应力导致的压缩应力和拉伸应力。此外，本发明采用的复式悬臂梁，较目前常用的悬臂梁，具有更好的刚性，有助于质量块的复位，减少了系统误差，提高了测 量准确性。而且，由X轴(Y轴)加速度分量引起的Y轴(X轴)方向的剪切应力主要集中在复式悬臂梁的中间部分，减少了剪切应力对位于复式悬臂梁的单端部分和双端部分的压敏电阻的影响，降低了加速度计的轴间耦合。
附图说明
图1为本发明实施例提供的一种三轴压阻式加速度计的结构示意图；
图2为图1沿A-A’向的剖面图；
图3为图1的局部放大图；
图4为图3中压敏电阻的接线图；
图5为本发明实施例提供的由压敏电阻连接构成的用于测量X轴加速度分量的惠斯通电桥图；
图6为本发明实施例提供的由压敏电阻连接构成的用于测量Y轴加速度分量的惠斯通电桥图；
图7为本发明实施例提供的由压敏电阻连接构成的检测Z轴方向加速度分量的惠斯通电桥图；
图8为本发明实施例提供的另一种三轴压阻式加速度计的结构示意图；
图9为图8的局部放大图。
图中：1为支撑边框，2为质量块，3为复式悬臂梁，31为位于X轴负方向的复式悬臂梁、32为位于X轴正方向的复式悬臂梁、33为位于Y轴负方向的复式悬臂梁、34为位于Y轴正方向的复式悬臂梁，301为复式悬臂梁的单端部分、302为复式悬臂梁的中间部分，303为复式悬臂梁的双端部分、4为限位模块，5为上盖板，6为下盖板，R1-R24为压敏电阻，7为金属焊盘，8为金属引线。
具体实施方式
以下参照附图来详细描述本发明的各种示例性实施例。对示例性实施例的描述仅仅是说明性的，不能作为对本发明及其应用或使用的任何限制。应注意到：除非另外具体说明，在这些实施例中阐述的部件和步骤的相对布置、数字表达式和数值不限制本发明的范围。
对于相关领域普通技术人员已知的技术、方法和设备可能不作详细讨论，但在适当情况下，这些技术、方法和设备应当被视为说明书的一部分。
如背景技术所述，目前单质量块三轴压阻式加速度计存在轴间耦合的问题。
为了解决上述技术问题，本发明提供一种三轴压阻式加速度计。图1为本发明实施例提供的一种三轴压阻式加速度计的结构示意图；图2为图1沿A-A’向的剖面图；图3为图1的局部放大图；图4为图3中压敏电阻的接线图。
参考图1至图4，所述三轴压阻式加速度计，包括支撑边框l、质量块2，以及复式悬臂梁3。质量块2通过复式悬臂梁3悬于支撑边框l的中心位置。质量块2在相互垂直的X轴方向和Y轴方向上，分别通过复式悬臂梁3与支撑边框l连接。质量块2的上表面位于由X轴和Y轴确定的平面，Z轴垂直于质量块2的上表面。所述X轴、Y轴和Z轴为三维直角坐标系中的三个轴。所述坐标系以质量块2的上表面的中心为坐标原点。
需要指出的是，本实施例的质量块2的上表面的形状为正方形。在本发明的其他实施例中，质量块2的上表面的形状可以为其他中心对称的现状，例如八边形和圆形。
复式悬臂梁3包括位于支撑边框l与质量块2之间的四根复式悬臂梁，分别是复式悬臂梁31、复式悬臂梁32、复式悬臂梁33、和复式悬臂梁34。复式悬臂梁31位于X轴负方向，复式悬臂梁32位于X轴正方向，复式悬臂梁33位于Y轴负方向，复式悬臂梁34位于Y轴正方向。
所述三轴压阻式加速度计还包括对称分布于4个复式悬臂梁上的多个压敏电阻。所述多个压敏电阻在没有应力的状态下，阻值相等。每根复式悬臂梁上分布有相同数量的压敏电阻。每根复式悬臂梁上，至少有一个沿平行于X轴方向设置的压敏电阻，至少有一个沿平行于Y轴方向设置的压敏电阻。在本实施例中，4个复式悬臂梁上对称分布有二十四个的压敏电阻Rl-R24，每根复式悬臂梁3上分布有六个压敏电阻。
如图1，3和4所示，复式悬臂梁包括单端部分301、双端部分303，和连接所述单端部分301和所述双端部分303的中间部分302。本发明不限制所述中间部分302在复式悬臂梁中的位置，亦即，不限制和连接所述单端部分301和所述双端部分303的长度比例。
在本实施例中，复式悬臂梁3的单端部分301与质量块2连接，复式悬臂梁3的双端部分303与支撑边框1连接。位于X轴负方向的复式悬臂梁31上分布有六个压敏电阻(R1、R2、R9、R10、R17和R18)。其中，R1、R2、R17和R18沿平行于X轴方向设置，R9和R10沿平行于Y轴方向设置。R1和R2位于双端 部分靠近支撑边框1的位置，R17和R18位于单端部分靠近质量块2的位置，R9和R10位于中间部分302靠近与双端部分连接的位置，并处于中间部分302靠近质量块2的一侧。位于X轴正方向的复式悬臂梁32上分布有六个压敏电阻(R5、R6、R13、R14、R21和R22)。其中，R5、R6、R21和R22沿平行于X轴方向设置，R13和R14沿平行于Y轴方向设置。R5和R6位于双端部分靠近支撑边框1的位置，R21和R22位于单端部分靠近质量块2的位置，R13和R14位于中间部分302靠近与双端部分连接的位置，并处于中间部分302靠近质量块2的一侧。位于Y轴负方向的复式悬臂梁33上分布有六个压敏电阻(R3、R4、R11、R12、R19和R20)。其中，R3、R4、R19和R20沿平行于Y轴方向设置，R11和R12沿平行于X轴方向设置。R3和R4位于双端部分靠近支撑边框1的位置，R19和R20位于单端部分靠近质量块2的位置，R11和R12位于中间部分302靠近与双端部分连接的位置，并处于中间部分302靠近质量块2的一侧。位于Y轴正方向的复式悬臂梁344上分布有六个压敏电阻(R7、R8、R15、R16、R23和R24)。其中，R7、R8、R23和R24沿平行于Y轴方向设置，R15和R16沿平行于X轴方向设置。R7和R8位于双端部分靠近支撑边框1的位置，R23和R24位于单端部分靠近质量块2的位置，R15和R16位于中间部分302靠近与双端部分连接的位置，并处于中间部分302靠近质量块2的一侧。
所述三轴压阻式加速度计还包括分布在支撑边框l上的多个金属焊盘。所述金属焊盘与复式悬臂梁上的压敏电阻通过金属引线电连接。本实施例中，支撑边框l上分布有二十四个金属焊盘。撑边框l的每条边有六个金属焊盘。支撑边框l的每条边上的六个金属焊盘与相邻的复式悬臂梁3上的六个压敏电阻通过金属引线8一一对应电连接。
所述三轴压阻式加速度计还包括限位模块。如图1所示，支撑边框1每个内角有一个限位模块4。每个限位模块4与质量块2之间留有X轴方向和Y轴方向的抗过载间隙。当一个方向的加速度分量超过预设最大载荷时，限位模块能阻止质量块2在该方向的进一步移动，起到保护保护加速度计的作用。
所述三轴压阻式加速度计还包括分别位于支撑边框l的上方与下方的上盖板5与下盖板6。质量块2分别与上盖板5和下盖板6之间留有Z轴方向抗过载间隙。当Z轴方向的加速度分量超过预设最大载荷时，上盖板5或下盖板6能阻止质量块2在Z轴方向的进一步移动，起到保护保护加速度计的作用。
以下阐述提供的三轴压阻式加速度计测量加速度原理。所述加速度计的质量块2的加速度在X轴、Y轴和Z轴均有分量。不失一般性，质量块2的加速度在X轴、Y轴和Z轴的分量均为正值。
用于测量X轴加速度分量的惠斯通电桥，包括在X轴方向的两个复式悬臂梁上沿X轴方向分布的压敏电阻，还包括在Y轴方向的两个复式悬臂梁上沿X轴方向分布的压敏电阻。用于测量Y轴加速度分量的惠斯通电桥，包括在Y轴方向的两个复式悬臂梁上沿Y轴方向分布的压敏电阻，还包括在X轴方向的两个复式悬臂梁上沿Y轴方向分布的压敏电阻。
图5为本发明实施例提供的由压敏电阻连接构成的用于测量X轴加速度分量的惠斯通电桥图。压敏电阻R5和压敏电阻R18串联构成该惠斯通电桥的第一个桥臂，压敏电阻Rl和压敏电阻R22串联构成该惠斯通电桥的第二个桥臂，压敏电阻R11和压敏电阻R16串联构成该惠斯通电桥的第三个桥臂，压敏电阻R12和压敏电阻R15串联构成该惠斯通电桥的第四个桥臂。并且，第一桥臂上的压敏电阻R5和第二桥臂上的压敏电阻Rl连接在该惠斯通电桥的一个输入端上，第三桥臂上的压敏电阻Rl6和第四桥臂上的压敏电阻R15连接在该惠斯通电桥的另一个输入端上。第一桥臂上的压敏电阻R18和第三桥臂上的压敏电阻Rl1连接在该惠斯通电桥的一个输出端上，第二桥臂上的压敏电阻R22和第四桥臂上的压敏电阻R12连接在该惠斯通电桥的另一个输出端上。
参照图1和图5，在正值X轴加速度分量的作用下，压敏电阻R1，R2，R21和R22的阻值增大，压敏电阻R17，R18，R5和R6的阻值减少，压敏电阻R9、R10、R13和R4不发生变化。此时，位于Y轴负方向的复式悬臂梁33、位于Y轴正方向的复式悬臂梁34上产生剪切应力。在梁宽度远大于厚度的情况下，该剪切应力产生的形变可以忽略，可以认为R19、R20、R23、R24、R3、R4、R7和R8的阻值不发生变化。不过，该剪切应力让复式悬臂梁33和34的中间部分302发生变形，使得压敏电阻R11和R16的阻值增大，压敏电阻R12和R15的阻值减少。因此，图5中的输出信号V out反映X轴加速度分量的大小。
参照图1和图5，在正值Y轴加速度分量的作用下，压敏电阻R3，R4，R23和R24的阻值增大，压敏电阻R19，R20，R7和R8的阻值减少，压敏电阻R11、R12、R15和R6不发生变化。此时，位于X轴负方向的复式悬臂梁31和位于X 轴正方向的复式悬臂梁32上产生剪切应力。在梁宽度远大于厚度的情况下，剪切应力产生的形变可以忽略，可以认为R17、R18、R21、R22、R1、R2、R5和R6的阻值不发生变化。不过，该剪切应力让复式悬臂梁31和32的中间部分302发生变形，使得压敏电阻R10和R13的阻值增大，压敏电阻R9和R14的阻值减少。可见，Y轴加速度分量不影响图5中各压敏电阻的阻值，不影响图5中的输出信号Vout，所以，X轴和Y轴之间的耦合可以忽略。
参照图1和图5，在正值Z轴加速度分量的作用下，压敏电阻R17、R18，R19、R20、R21、R22、R23和R24的阻值增大，压敏电阻R1、R2，R3、R4、R5、R6、R7和R8的阻值减少，压敏电阻R9、R10，R11、R12、R13、R14、R15和R16不发生变化。在图5所示的惠斯通电桥中，由于压敏电阻R1和R5的变化相同，压敏电阻R22和R18的变化相同，压敏电阻R12和R11的变化相同，压敏电阻R15和R16的变化相同，可见，Z轴加速度分量不影响图5中各压敏电阻的阻值，不影响图5中的输出信号V out，所以，X轴和Z轴之间的耦合可以忽略。
图6为本发明实施例提供的由压敏电阻连接构成的用于测量Y轴加速度分量的惠斯通电桥图。压敏电阻R7和压敏电阻R20串联构成该惠斯通电桥的第一个桥臂，压敏电阻R3和压敏电阻R24串联构成该惠斯通电桥的第二个桥臂，压敏电阻R10和压敏电阻R13串联构成该惠斯通电桥的第三个桥臂，压敏电阻R9和压敏电阻R14串联构成该惠斯通电桥的第四个桥臂。并且，第一桥臂上的压敏电阻R7和第二桥臂上的压敏电阻R3连接在该惠斯通电桥的一个输入端上，第三桥臂上的压敏电阻Rl3和第四桥臂上的压敏电阻R14连接在该惠斯通电桥的另一个输入端上。第一桥臂上的压敏电阻R20和第三桥臂上的压敏电阻R10连接在该惠斯通电桥的一个输出端上，第二桥臂上的压敏电阻R24和第四桥臂上的压敏电阻R9连接在该惠斯通电桥的另一个输出端上。
同理，图6中的输出信号V out反映Y轴加速度分量的大小，且Y轴和X轴之间的耦合可以忽略，Y轴和Z轴之间的耦合可以忽略。
用于测量Z轴加速度分量的惠斯通电桥，包括分布于复合悬臂梁301的单端部分301上的压敏电阻，和分布于复合悬臂梁301的双端部分303上的压敏电阻。
图7为本发明实施例提供的由压敏电阻连接构成的检测Z轴方向加速度分量的惠斯通电桥图。压敏电阻R2和压敏电阻R6串联构成该惠斯通电桥的第一 个桥臂，压敏电阻R17和压敏电阻R21串联构成该惠斯通电桥的第二个桥臂，压敏电阻R19和压敏电阻R23串联构成该惠斯通电桥的第三个桥臂，压敏电阻R4和压敏电阻R8串联构成该惠斯通电桥的第四个桥臂。并且，第一桥臂上的压敏电阻R2和第二桥臂上的压敏电阻R17连接在该惠斯通电桥的一个输入端上，第三桥臂上的压敏电阻R23和第四桥臂上的压敏电阻R8连接在该惠斯通电桥的另一个输入端上。第一桥臂上的压敏电阻R6和第三桥臂上的压敏电阻R19连接在该惠斯通电桥的一个输出端上，第二桥臂上的压敏电阻R21和第四桥臂上的压敏电阻R4连接在该惠斯通电桥的另一个输出端上。
同理，图7中的输出信号V out反映Z轴加速度分量的大小，且Z轴和X轴之间的耦合可以忽略，Z轴和Y轴之间的耦合可以忽略。
本实施例中，所述的支撑边框1、质量块2及其之间的复式悬臂梁3是以SOI片材料经现有的标准压阻式半导体微机械工艺加工制成。设置于弹性梁臂3上的二十四个压敏电阻是经现有的扩散或离子注入工艺加工制成。所述上盖板5和所述下盖板6的材料为Pyrex玻璃，所述上盖板5和所述下盖板6与所述支撑边框1通过静电键合实现连接。
本实施例中，所述加速度计的总体尺寸为：长约6000μm、宽约6000μm、高约2000μm。其中，所述质量块的边长约为2400μm、厚度约为300μm；所述的复式悬臂梁的梁长约为800μm、单端部分梁宽约为200μm、双端部分梁宽约为1200、梁厚为约20μm；支撑边框的边长约为4000μm，边框的宽度约为1000μm。
本实施例中，在测量X轴和Y轴的加速度分量时，不仅利用了该分量直接引起的压缩应力和拉伸应力，还利用了该分量引起的剪切应力导致的压缩应力和拉伸应力。此外，本实施例采用的复式悬臂梁，较目前常用的悬臂梁，具有更好的刚性，有助于质量块的复位，减少了系统误差，提高了测量准确性。而且，由X轴(Y轴)加速度分量引起的Y轴(X轴)方向的剪切应力主要集中在复式悬臂梁的中间部分，减少了剪切应力对位于复式悬臂梁的单端部分和双端部分的压敏电阻的影响，降低了加速度计的轴间耦合。
可选的，图8为本发明实施例提供的另一种三轴压阻式加速度计的结构示意图，图9为图8的局部放大图。如图8和9所示，本实施例中，复式悬臂梁3为复式悬臂梁，包括单端部分301、双端部分303和中间部分302。在本实施例中，复式悬臂梁3的单端部分与质量块连接，复式悬臂梁3的双端部分与支撑 边框1连接。位于X轴负方向的复式悬臂梁31上分布有六个压敏电阻(R1、R2、R9、R10、R17和R18)。其中，R1和R2位于双端部分靠近支撑边框1的位置，R17和R18位于单端部分靠近质量块2的位置，R9和R10位于中间部分靠近与单端部分连接的位置，并处于中间部分靠近质量块2的一侧。位于X轴正方向的复式悬臂梁32上分布有六个压敏电阻(R5、R6、R13、R14、R21和R22)。其中，R5和R6位于双端部分靠近支撑边框1的位置，R21和R22位于单端部分靠近质量块2的位置，R13和R14位于中间部分靠近与单端部分连接的位置，并处于中间部分靠近质量块2的一侧。位于Y轴负方向的复式悬臂梁33上分布有六个压敏电阻(R3、R4、R11、R12、R19和R20)。其中，R3和R4位于双端部分靠近支撑边框1的位置，R19和R20位于单端部分靠近质量块2的位置，R11和R12位于中间部分靠近与单端部分连接的位置，并处于中间部分靠近质量块2的一侧。位于Y轴正方向的复式悬臂梁34上分布有六个压敏电阻(R7、R8、R15、R16、R23和R24)。其中，R7和R8位于双端部分靠近支撑边框1的位置，R23和R24位于单端部分靠近质量块2的位置，R15和R16位于中间部分靠近与单端部分连接的位置，并处于中间部分靠近质量块2的一侧。
需要指出的是，在图1与图8所示的两个实施例中，压敏电阻R9与R10，R11与R12，R13与R14，R15与R16的编号次序对调。按照图1所示实施例的分析方法可以得到，在图8所示的实施例中，图5中的输出信号Vout反映X轴加速度分量的大小，且X轴和Y轴之间的耦合可以忽略，X轴和Z轴之间的耦合可以忽略；图6中的输出信号V out反映Y轴加速度分量的大小，且Y轴和X轴之间的耦合可以忽略，Y轴和Z轴之间的耦合可以忽略；图7中的输出信号Vout反映Z轴加速度分量的大小，且Z轴和X轴之间的耦合可以忽略，Z轴和Y轴之间的耦合可以忽略。
本实施例中，在测量X轴和Y轴的加速度分量时，不仅利用了该分量直接引起的压缩应力和拉伸应力，还利用了该分量引起的剪切应力导致的压缩应力和拉伸应力。此外，本实施例采用的复式悬臂梁，较目前常用的悬臂梁，具有更好的刚性，有助于质量块的复位，减少了系统误差，提高了测量准确性。而且，由X轴(Y轴)加速度分量引起的Y轴(X轴)方向的剪切应力主要集中在复式悬臂梁的中间部分，减少了剪切应力对位于复式悬臂梁的单端部分和双端部分的压敏电阻的影响，降低了加速度计的轴间耦合。
以上所述仅为本发明的实施例，并不用以限制本发明。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (15)

  1. 一种三轴压阻式加速度计，其特征在于，包括：
    支撑边框；
    质量块；
    多个复式悬臂梁；
    分布于所述多个复式悬臂梁上的多个压敏电阻，
    其中：
    所述质量块通过所述复式悬臂梁悬于所述支撑边框的中心位置，所述质量块在相互垂直的X轴方向和Y轴方向上，分别通过所述复式悬臂梁与所述支撑边框连接；
    所述质量块的上表面位于由所述X轴和所述Y轴确定的平面，Z轴垂直于所述质量块的上表面；
    所述多个压敏电阻在没有应力的状态下，阻值相等；
    每根所述复式悬臂梁上分布有相同数量的所述压敏电阻；
    每根所述复式悬臂梁上，至少有一个沿平行于所述X轴方向设置的所述压敏电阻，至少有一个沿平行于所述Y轴方向设置的所述压敏电阻；
    所述X轴、所述Y轴和所述Z轴为三维直角坐标系中的三个轴，所述坐标系以所述质量块的所述上表面的中心为坐标原点。
  2. 根据权利要求1所述的加速度计，其特征在于：
    所述多个复式悬臂梁包括四根复式悬臂梁，分别位于X轴负方向，X轴正方向，Y轴负方向，和Y轴正方向。
  3. 根据权利要求2所述的加速度计，其特征在于：
    所述复式悬臂梁包括单端部分、双端部分，和连接所述单端部分和所述双端部分的中间部分；
    所述单端部分与所述质量块连接，所述双端部分与所述支撑边框连接。
  4. 根据权利要求3所述的加速度计，其特征在于：
    所述四根复式悬臂梁上对称分布有二十四个的所述压敏电阻，每根所述复式悬臂梁上分布有六个所述压敏电阻。
  5. 根据权利要求4所述的加速度计，其特征在于：
    所述复式悬臂梁上分布有六个压敏电阻，其中：
    二个所述压敏电阻位于所述双端部分靠近所述支撑边框的位置；
    二个所述压敏电阻位于所述单端部分靠近所述质量块的位置；
    二个所述压敏电阻位于所述中间部分靠近与所述双端部分连接的位置，并处于所述中间部分靠近所述质量块的一侧。
  6. 根据权利要求5所述的加速度计，其特征在于，还包括：
    分布在所述支撑边框上的多个金属焊盘，其中，所述多个金属焊盘与所述复式悬臂梁上的所述压敏电阻通过金属引线电连接。
  7. 根据权利要求6所述的加速度计，其特征在于：
    所述支撑边框上分布有二十四个所述金属焊盘；
    所述撑边框的每条边有六个金属焊盘；
    所述支撑边框的每条边上的所述六个金属焊盘与相邻的所述复式悬臂梁上的所述六个压敏电阻通过金属引线一一对应电连接。
  8. 根据权利要求1所述的加速度计，其特征在于，还包括：
    多个限位模块，其中，每个所述限位模块与所述质量块之间留有所述X轴方向和所述Y轴方向的抗过载间隙。
  9. 根据权利要求8所述的加速度计，其特征在于：
    所述支撑边框的每个内角有一个所述限位模块。
  10. 根据权利要求1所述的加速度计，其特征在于，还包括：
    分别位于所述支撑边框的上方与下方的上盖板与下盖板，其中所述质量块分别与上盖板和下盖板之间留有Z轴方向抗过载间隙。
  11. 根据权利要求5所述的加速度计，其特征在于：
    用于测量X轴加速度分量的惠斯通电桥，包括在所述X轴方向的两个所述复式悬臂梁上沿所述X轴方向分布的所述压敏电阻，还包括在所述Y轴方向的两个所述复式悬臂梁上沿所述X轴方向分布的所述压敏电阻。
    用于测量Y轴加速度分量的惠斯通电桥，包括在所述Y轴方向的两个所述复式悬臂梁上沿所述Y轴方向分布的所述压敏电阻，还包括在所述X轴方向的两个所述复式悬臂梁上沿所述Y轴方向分布的所述压敏电阻。
  12. 根据权利要求5所述的加速度计，其特征在于：
    用于测量Z轴加速度分量的惠斯通电桥，包括分布于所述复合悬臂梁的所述单端部分上的所述压敏电阻，和分布于所述复合悬臂梁的所述双端部分上的所述压敏电阻。
  13. 根据权利要求4所述的加速度计，其特征在于：
    所述复式悬臂梁上分布有六个压敏电阻，其中：
    二个所述压敏电阻位于所述双端部分靠近所述支撑边框的位置；
    二个所述压敏电阻位于所述单端部分靠近所述质量块的位置；
    二个所述压敏电阻位于所述中间部分靠近与所述单端部分连接的位置，并处于所述中间部分靠近所述质量块的一侧。
  14. 根据权利要求13所述的加速度计，其特征在于：
    用于测量X轴加速度分量的惠斯通电桥，包括在所述X轴方向的两个所述复式悬臂梁上沿所述X轴方向分布的所述压敏电阻，还包括在所述Y轴方向的两个所述复式悬臂梁上沿所述X轴方向分布的所述压敏电阻。
    用于测量Y轴加速度分量的惠斯通电桥，包括在所述Y轴方向的两个所述复式悬臂梁上沿所述Y轴方向分布的所述压敏电阻，还包括在所述X轴方向的两个所述复式悬臂梁上沿所述Y轴方向分布的所述压敏电阻。
  15. 根据权利要求13所述的加速度计，其特征在于：
    用于测量Z轴加速度分量的惠斯通电桥，包括分布于所述复合悬臂梁的所述单端部分上的所述压敏电阻，和分布于所述复合悬臂梁的所述双端部分上的所述压敏电阻。
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