CN105723184A - Inertial sensor using sliding plane proximity switches - Google Patents
Inertial sensor using sliding plane proximity switches Download PDFInfo
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- CN105723184A CN105723184A CN201380074890.4A CN201380074890A CN105723184A CN 105723184 A CN105723184 A CN 105723184A CN 201380074890 A CN201380074890 A CN 201380074890A CN 105723184 A CN105723184 A CN 105723184A
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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
- G01C19/5642—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating bars or beams
- G01C19/5656—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating bars or beams the devices involving a micromechanical structure
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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
- G01C19/5607—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating tuning forks
- G01C19/5621—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating tuning forks the devices involving a micromechanical structure
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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
- G01P15/097—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 vibratory elements
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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
- G01P15/135—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 making use of contacts which are actuated by a movable inertial mass
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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
- 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
- G01P2015/0817—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 pivoting movement of the mass, e.g. in-plane pendulum
Abstract
A time-domain inertial sensor comprising: a support structure having an electrode plane parallel to an x-y plane of an x-y-z mutually orthogonal coordinate system, wherein the support structure's largest dimension lies within the x-y plane; a proof mass having a first surface parallel to the x-y plane; wherein the proof mass is springedly coupled to the support structure such that the first surface is separated from the electrode plane by a gap; a driver configured to drive the proof mass to oscillate with respect to the support structure in approximately only the x-direction such that, while oscillating, the gap does not vary significantly; and a first, time-domain, proximity switch disposed to switch from an open state to a closed state each time the proof mass is in a first reference position with respect to the support structure.
Description
Priority
This application claims following priority: U. S. application number is 13/847, 539, date of filing is on March 20th, 2013, title is owned together and co-pending patent application for " adopting the inertial sensor (INERTIALSENSORUSINGSLIDINGPLANEPROXIMITYSWITCHES) of slip plane proximity switch " (naval case #101875's), it is following continuation-in-part application: U. S. application number is 13/168, 603, date of filing is on June 24th, 2011, title is the patent application of " apparatus and method (ApparatusandMethodsforTimeDomainMeasurementofOscillation Perturbations) for the time domain measurement of oscillation disturbances " (naval case #100809), its content is integrally incorporated herein with it by reference.
The research and development that federal government subsidizes
The application transfers U.S. government and can be used for license for commercial object.License and technology inquiry can be led: California, Santiago, coding 72120, space and sea warfare system centre, research and technology office of application (postcode 92152)；Voice mail (619) 553-5118；Ssc_pac_t2navy.mil.Naval is with reference to case number 101875.
Background technology
It relates to time domain inertial sensor field.One example of time domain inertial sensor is accelerometer, and the time wherein passing through predefined reference position by measuring the detection mass body of harmonic oscillation may determine that inertial acceleration.
Summary of the invention
In the first aspect of the disclosure, disclose a kind of time domain inertial sensor.In one embodiment, this sensor includes supporting construction, and this supporting construction includes the electrode plane that the x-y plane of the coordinate system mutually orthogonal with x-y-z is parallel, and this supporting construction has the maximum sized feature being positioned within x-y plane；And detection mass body, including the first surface parallel with x-y plane.In a kind of variant, detection mass body is flexibly coupled to supporting construction, first structure is separated with electrode plane with certain interval, and this sensor farther includes driver, this driver is configured to drive detection mass body generally only to vibrate relative to supporting construction in the x direction so that this gap is in the duration of oscillation and changes indistinctively；And the first time domain proximity switch, it is configured to be switched to closure state from off-state when detection mass body is in the first reference position relative to supporting construction.
In another embodiment, this sensor includes supporting construction, and this supporting construction has the top surface that the x-y plane of the coordinate system mutually orthogonal with x-y-z is parallel；Detection mass body, by Elastic Coupling to supporting construction so that detection mass body is configured to generally only vibrate in x-y plane；Driver, is configured to drive detection mass body with relative to supporting construction harmonic oscillation；And multiple proximity switch, it is operatively coupled to supporting construction and is coupled to the multiple corresponding section of detection mass body so that each proximity switch is configured to work as the respective section of each correspondence of detection mass body and is switched to closure state through out-of-date from off-state under the section of supporting construction.
In another embodiment, this sensor includes the structure with the electrode plane parallel with the first plane of mutually orthogonal coordinate system, and this structure has the maximum sized feature being positioned within the first plane；Detection mass body, including the first surface substantially parallel with the first plane, detection mass body is flexibly coupled to supporting construction so that first surface separates with electrode plane with certain interval；Driver, is configured to drive detection mass body generally only to vibrate relative to supporting construction in a first direction so that this gap is in the duration of oscillation and changes indistinctively；And the first time domain proximity switch, it is configured to when detection mass body is in the first reference position relative to supporting construction and is switched to closure state from off-state.
Further, a kind of method sensing inertia is disclosed.In one embodiment, the method includes driving detection mass body only to vibrate relative to supporting construction in the first dimension so that the gap between detection mass body and supporting construction in the second orthogonal dimensions is in the duration of oscillation and changes indistinctively；And when detection mass body is in the first reference position relative to supporting construction, it is switched to closure state from off-state.
Accompanying drawing explanation
In some views, utilize the element that identical accompanying drawing labelling instruction is identical.Element in the accompanying drawings is not drawn with equal proportion, and for purposes of clarity some sizes has been exaggerated.
Fig. 1 is the front view of the embodiment of time domain inertial sensor.
Fig. 2 is the perspective view of the embodiment of time domain inertial sensor.
Fig. 3 is the perspective view of the embodiment of time domain inertial sensor.
Fig. 4 A is the perspective view of the manufacturing step of time domain inertial sensor.
Fig. 4 B is the perspective view of the manufacturing step of time domain inertial sensor.
Fig. 5 A is the perspective view of the manufacturing step of time domain inertial sensor.
Fig. 5 B is the perspective view of the manufacturing step of time domain inertial sensor.
Fig. 6 A is the perspective view of the manufacturing step of time domain inertial sensor.
Fig. 6 B is the bottom view of the manufacturing step of time domain inertial sensor.
Fig. 7 is the perspective view of the embodiment of time domain inertial sensor.
Fig. 8 A is the top view of the embodiment of time domain inertial sensor.
Fig. 8 B is the bottom view of the embodiment of time domain inertial sensor.
Fig. 9 A is the perspective view of the embodiment of time domain inertial sensor.
Fig. 9 B is the perspective view of the amplification of the part of the time domain inertial sensor shown in Fig. 9 A.
Figure 10 is the perspective view of the amplification of the part of the time domain inertial sensor shown in Fig. 9 A.
Figure 11 is the perspective view of the embodiment of time domain inertial sensor.
Figure 12 illustrates a series of drawing of two dimension (2D) cross section of the square electric wire being maintained at fixed voltage of process on the height being maintained at bottom surface place and narrow cantilever beam (rectangle) just.
Figure 13 A be the capacitive approach switch as the cantilever beam shown in Figure 11 and the function of the relative displacement between thin electric wire with shown in pico farad (pF) estimate electric capacity drawing.
Figure 13 B show the function as the relative displacement between cantilever beam and electric wire with the drawing of the estimation capacitance variations of pico farad (pF) every micron (μm).
Figure 13 C show introduce in capacitance-type switch with the electric current i of microampere (μ A) drawing relative to the time drawn with microsecond (μ s).
Figure 14 A is the perspective view of the embodiment of time domain inertial sensor.
Figure 14 B is the perspective view of the amplification of the part of the time domain inertial sensor shown in Figure 14 A.
Detailed description of the invention
Fig. 1 be the vague generalization view of time domain inertial sensor 10 face diagram, this time domain inertial sensor 10 includes supporting construction 12, detection mass body 14, driver 16 (figure 2 illustrates) and the first time domain proximity switch 18.Supporting construction 12 has electrode plane 20, and the x-y plane of its coordinate system mutually orthogonal with x-y-z is parallel.Within the full-size of supporting construction 12 is positioned at x-y plane.Detection mass body 14 has first surface 22, and it is parallel with x-y plane, and detection mass body 14 is flexibly coupled to supporting construction 12 so that first surface 22 separates with electrode plane 20 with certain interval 24.Driver 16 is configured to drive detection mass body 14 generally only to vibrate relative to supporting construction 12 in the x direction so that in duration of oscillation gap 24 and change indistinctively.First proximity switch 18 is configured to be switched to closure state when detection mass body 14 is in the first reference position relative to supporting construction 12 from off-state every time.Such as, in the embodiment of the sensor 10 shown in FIG, the first proximity switch 18 may be configured to every time when detection mass body 14 is switched to closure state through out-of-date under the feature 26 of supporting construction 12, and wherein the bottom of feature 26 limits electrode plane 20.
Inertial sensor 10 can be manufactured with any scale.Such as, in one embodiment, inertial sensor 10 can be integrated in MEMS (MEMS) device by monolithic.Inertial sensor 10 can be used with any orientation.Although x-y-z coordinate system is depicted and referenced herein in the accompanying drawings, it is to be understood that first, second, and third direction as used herein/axis can correspond to any three the mutually orthogonal direction/axis in any three-dimensional system of coordinate.
Supporting construction 12 can be any size and dimension, and can be made up of any materials that can provide inertial sensor 10 rigid support so that supporting construction 12 is not significant deflection and/or deformation when being exposed to transverse direction and the rotary acceleration of inertial sensor 10.
Detection mass body 14 can be able to be made detection mass body 14 in response to transverse direction and/or the rotary acceleration of inertial sensor 10 and any quality of movement by Elastic Coupling to supporting construction 12.The suitable example of detection mass body 14 includes but not limited to be integrated into the cantilever in supporting construction 12 by monolithic, all as shown in Figure 2.
Driver 16 is each can be able to cause detection mass body 14 relative to supporting construction 12 in x direction any device with the hunting of frequency of any desired.The suitable example of driver 16 includes but not limited to the variable area actuator that such as static broach drives (describing in such as Fig. 2) etc, the variable gap driver of such as parallel plate actuator etc, and activate other electromagnetism or piezoelectric device.Detection mass body 14 can be used continuous print oscillating force or be driven by periodicity " impulse function " power with the harmonic resonance homophase of detection mass body.
First proximity switch 18 can be able to produce any device of the digital signal corresponding relative to the various positions of supporting construction 12 with detection mass body 14.In other words, the first proximity switch 18 can be able to experience the random devices of state change based on the detection mass body 14 change in location relative to supporting construction 12.The suitable example of the first proximity switch 18 includes but not limited to electron tunneling switch, capacitive switches, optical shutter switch and magnetic switch.The purpose of the first proximity switch 18 is the section position relative to supporting construction 12 of the detection mass body 14 that localization the first proximity switch 18 is attached to, allow to perform the measurement mutually of acceleration independence accurately, thus adding the stability of phaselocked loop Guan Bi and reducing total phase noise and the time base error of inertial sensor 10.
Fig. 2 is the perspective view of the embodiment of inertial sensor 10.In this embodiment, supporting construction 12 and detection mass body 14 are by single-chip integration.Also it is illustrated that in this embodiment, first proximity switch 18 is electron tunneling tip switch, it includes the tunnelling tip 28 of the supporting construction 12 being rigidly attached in electrode plane 20, make, when the free end of detection mass body 14 and tunnelling tip 28 are aligned in a z-direction, tunnelling to occur between first surface 22 and tunnelling tip 28.Tunnelling tip 28 can be electroplated in a z-direction fully, so that it can be self-supporting in detection mass body 14 on the region of its vibration.
Fig. 3 is the first proximity switch 18 is the perspective view of the embodiment of the inertial sensor 10 of capacitance-type switch.In this embodiment, detection mass body 14 is used as the first half 30 of the first proximity switch 18, and the second half 32 of proximity switch 18 is installed to supporting construction 12.In this embodiment, the closure state of the first proximity switch 18 is the detection mass body 14 position generation of peak value electric capacity between existence first half 30 and second half 32.What supporting construction 12 can include cover wafer and proximity switch 18 the second half may be attached to this cover wafer.
Fig. 4 A to Fig. 7 illustrates the example manufacturing step of the accelerometer embodiment of inertial sensor 10.This exemplary step starts with double; two polishing 0.4 silicon wafers 34.It follows that the thermal oxide layer 36 of a micron can be deposited over top and the bottom of silicon wafer 34, as shown in the perspective view in Fig. 4 A.It follows that pattern 38 can be etched in top oxide layer 36, as shown in Figure 4 B.It follows that the tungsten layer 40 of 30nm can be deposited in top oxide layer 36, as shown in Figure 5 A.It follows that use identical photoresist mask, the copper-stripping of 100nm can be deposited on tungsten layer 40 followed by the plated copper film 42 of 10 microns, as shown in Figure 5 B.It follows that the part exposed of tungsten layer 40 can be removed, as shown in FIG.It follows that Fig. 6 B illustrates how back of the body oxide layer 36 can be patterned (front and back alignment), silicon substrate wafer 34 can be etched the end of up to by deep, and the part arbitrarily exposed of tungsten layer 40 can be removed.In fig. 6b, the bottom of detection mass body 14 and the bottom at multiple tunnelling tip 28 are now visible.The perspective view of the accelerometer embodiment completed of inertial sensor 10 figure 7 illustrates.In this embodiment, cantilever detection mass body 14 can freely move under copper tunnelling tip 28, and these copper tunnelling tips 28 are spaced apart what the gap of 30nm was left over after removing the part of the exposure sacrificing tungsten layer 40.
Inertial sensor 10 can include many proximity switches 18, all as shown in Figure 7.Multiple proximity switches may be used to determine when that the detection mass body 14 of harmonic oscillation is through known location so that can reconstruct relative to the motion of time and may determine that the power of perturbation harmonic vibration.When proximity switch 18 is electron tunneling switch, critical dimension is the tunnel gap 24 of electron tunneling proximity switch.In quasiconductor MEMS, the most controlled size is the thickness of deposition layer on a surface of the substrate.Being in the embodiment of inertial sensor 10 of electron tunneling switch at proximity switch 18, the thickness of (or growth) layer of deposition defines tunnel distance.Which has limited the axes of inertia quantity that can be integrated into one single chip, but significantly reduce cost and the complexity of element manufacturing, and the operation of tunnel proximity switch should be made more unified.In the embodiment of inertial sensor 10, detection mass body 14 in the lower slider at the tunnelling tip 28 being installed to supporting construction 12, as long as and conductivity detection mass body 14 be under tunnelling tip 28 (and near) this tunnelling and just occur.
As shown in Fig. 4 A to Fig. 7, the plane-parallel of bottom at the top and the fixing tunnelling tip 28 of conduction that define heavy doping conductive silicon detection mass body 14 separately can be defined by the planar depositions of expendable material (such as tungsten layer 40).Before the pattern deposition at fixing tunnelling tip 28, this material is deposited in silicon substrate wafer 34.Tunnelling tip 28 is patterned on the region of silicon waiting to be completely removed (by etching) from back, in order to allow detection mass body 14 to move within the plane on the surface of silicon substrate wafer 34.All of motion can be limited to the plane of substrate wafer 34, because tunnelling tip 28 is located just at above and moving both vertically of detection mass body 14 is likely to damage tunnelling tip 28.Such as, cross coupling can be rigidly attached to supporting construction and is positioned relative to detection mass body, thus limiting detection mass body motion in a z-direction.In order to maintain the appropriate tunnel distance between tunnelling most advanced and sophisticated 28 and detection mass body 14, the warpage caused due to the stress in silicon detection mass body 14, in spring and supporting construction 12 and/or tunnelling most advanced and sophisticated 28 itself should be kept relatively low.For this purpose, on the side of silicon substrate wafer 34, the electrolyte of growth or deposition can have the mirror image electrolyte of growth or deposition on another side, thus eliminating the stress of any generation.Tunnelling tip 28 can be made of an electrically conducting material, and this conductive material illustrates seldom or do not have tinsel or compression stress, and not can be used to dry ecthing penetrate silicon wafer 34 vertical wall sulfur hexafluoride (SF6) chemical treatment in etching.Copper can be used to this purpose because itself and be formed without the product during fluorine chemistry processes, and can easily be electroplated onto in thin evaporation Seed Layer with suitable thickness (there is the room temperature process of the rate of growth of optimization thus not introducing stress).
Fig. 8 A to Figure 10 B illustrates the time domain gyroscope-accelerometer of inertial sensor 10 in conjunction with the embodiments.This embodiment uses tunnelling tip 28 to monitor that gyroscope drives the motion of mass body (also serving as accelerometer detection mass body), and uses tunnelling tip with the motion of the control survey cantilever of Coriolis force for rotating around z (vertically) axis.Fig. 8 A and Fig. 8 B is corresponding top view and the bottom view of the gyroscope-accelerometer embodiment of inertial sensor 10.In this embodiment, the first surface 22 of detection mass body 14 is T-shaped and correspondingly includes substrate 44, cervical region 46 and the first free end 48 and the second free end 50.Substrate 44 is attached to supporting construction 12, and cervical region 46 is operatively coupled to more than first proximity switch 52.First free end 48 is operatively coupled to more than second proximity switch 54, and the second free end 50 is operatively coupled to the 3rd many proximity switches 56.Fig. 9 A is the perspective view of the gyroscope-accelerometer embodiment of inertial sensor 10.Fig. 9 B is the expanded view of the first free end 48 and more than second proximity switch 54.Figure 10 is cervical region 46 and the expanded view of more than first proximity switch 52.Figure 10 is corresponding to the region indicated by broken box 58 of Fig. 9 A.
Figure 11 is the perspective view of another embodiment of inertial sensor 10.In this embodiment, the first proximity switch 18 includes one or more thin electric wire 60 and detection mass body 14, and one rises and is used as (multiple) capacitance-type switch.Capacitance-type switch based on the principle that conductor (or quasiconductor) with short time period nearby through causing quick capacitance variations each other.The electric capacity of this change introduces the sharp current impulse in conductor then, and it is used as correct time trigger data to determine the immediate moment.In embodiment shown in fig. 11, detection mass body 14 is to be attached to the cantilever of supporting construction 12 so that there is small capacitances gap 24 between beam and supporting construction 12.Beam is allowed to be parallel in the x direction the planar oscillation of supporting construction 12, as indicated by double-head arrow 62 in fig. 11.This beam is relatively relatively stiff in other two dimensions (that is, y direction and z direction).In supporting construction 12, one or more thin electric wires 60 are disposed in cantilever by the predefined position in duration of oscillation process.Once beam is set in vibration, when this beam is through these electric wires 60, point capacitance variations occurs, and generates the current impulse in corresponding electric wire 60.
In order to model and quantify by beam through near the current impulse that generates of parallel wires 60, it is possible to first distinguish the general equation for the electric charge on capacitor:
Wherein Q (t), C (t) and V (t) be respectively the time-varying electric charge on capacitor, capacitor electric capacity and across the voltage of capacitor.In this case, long silicon beam nearby passes through between the electric wire 60 being deposited in substrate/supporting construction 12 and forms parallel plate capacitor.By pointing out that the change in electric capacity is the motion (such as, the variable quantity of beam/electric wire overlapping region) due to beam and passes through fixing voltage between beam and electric wire, it is concluded that:
Wherein dx/dt is the cantilever beam speed relative to electric wire, and due to fixed voltage level, dV/dt is zero.
To put it more simply, assume that cantilever motion (x (t)) is sinusoidal in the duration of oscillation, and electric wire is positioned very close to oscillation center (defining at the t=0 place) place of beam.Thus, the beam speed close to this point can be estimated as:
Wherein x0It is amplitude and the ω of the vibration of beam0It it is the resonance angular frequency of girder construction.Trigger current can be written out by the result of equation (2) and (3) is substituted into equation (1).
Can adopt such asEtc finite element analysis software to generate for the actual expectation (see Figure 12 to 13C) of the dC/dx item in equation (4).This emulation assumes that narrow silicon beam is through having and beam equal length, equal wide electric wire.Along with object is close and nearby through each other, it is positive pulse that pointy double-current pulse is formed first, it is negative pulse (see Figure 13 C) immediately after.Zero passage (see Figure 13 C, at t=0 place) between the two current impulse is used to define the closure state of definite triggering " moment " or proximity switch.This zero crossing can be defined as detection mass body 14 relative to shown in the relative position such as t=0 in Figure 13 C of current impulse polarity inversion place of supporting construction 12.Should being noted that, the oscillation amplitude of this beam and/or the change of frequency and any change in fixed voltage source will cause the size of output electric current to change (see equation 4).But, the position of zero cross fired point keeps constant with the change of these systematic parameters.
And then, the arbitrarily biasing of the vibration of the cantilever beam caused due to inertial acceleration is by the reduction of the overall magnitude of the asymmetric warpage and signal that cause output electric current.This warpage is owing to the tip of beam is caused at the rate of change of interval interested, and the reduction of amplitude is owing to speed causes from the relative reduction of the peak rate only occurred near zero offset again.But, no matter these changes, the position of zero cross fired example will keep consistent, and this is owing to there is (during when electric wire and beam perfect alignment) at the some place of peak value electric capacity in its design.Because the zero passage in capacitance-type switch is good definition and consistent parameter, regardless of the change of systematic parameter, it is used as good trigger mechanism (mainly by the electronic noise restriction in the circuit of voltage source and Time Triggered).
The making of condenser type electric wire 60 and silicon cantilever (that is, detection mass body 14) is very good definition and controlled manufacturing process.Physical clearance 24 between beam and electric wire can be defined by the thin film (sacrifice layer) of vertical deposition, and it is removed in the final step made.This gap 24 can be fairly small and well controlled, because the thickness of sacrificial film can be well controlled during making.
Figure 12 illustrates a series of drawing of two dimension (2D) cross section of the square electric wire being maintained at fixed voltage of process on the height being maintained at bottom surface place and narrow cantilever beam (rectangle) just.This calculating can be used to calculate along with electric wire and cantilever nearby close to and the capacitance variations (such as, dC/dx) of system of traverse.Time stream is from upper left downwards, continues thereafter with from upper right downward.The electric capacity of system is calculated and is used to generate drawing shown in Figure 13 A to 13C subsequently.
Figure 13 A show the capacitive approach switch as the cantilever beam shown in Figure 11 and the function of the relative displacement between thin electric wire with shown in pico farad (pF) estimate electric capacity drawing.What this calculating assumed to be maintained at fixed voltage has 2 microns (μm) the wide electric wire MEMS level device through 2 microns (μm) wide bottom surface silicon beam.Interval between electric wire and cantilever is assumed and closest to place is being 50 nanometers (nm).The peak value electric capacity realized is that 0.217 pico farad (measurable amount) occurs as expected when object relative to each other centers.Peak value electric capacity can be increased linearly by extending wire width or length.If broadened, this profile will be widened.
Figure 13 B shows the drawing that the estimation with the electric capacity of pico farad (pF) every micron (μm) of the function as the relative displacement (such as, the derivative of the drawing shown in Figure 11) between cantilever beam and electric wire changes.
Figure 13 C show introduce in capacitance-type switch with the electric current i of microampere (μ A) drawing relative to the time drawn with microsecond (μ s).The value using the space capacitance variations (dC/dx) in Figure 13 A is combined with equation 4, be maintained at 100 volts fixed voltage electric wire in introducing drawn using the electric current shown in microampere (μ A) as the function with the time shown in microsecond (μ s).This assumes that cantilever beam has the harmonic frequency of the 15kHz vibration of the fixed amplitude with ± 20 μm.The zero passage (at t=0) of this electric current output can be used to calculate for " cross events " needed for device operation.
Figure 14 A and Figure 14 B is the perspective view of another embodiment of inertial sensor 10.Figure 14 B is the perspective view of the amplification of the part of the inertial sensor 10 shown in Figure 14 A.In this embodiment of inertial sensor 10, driver 16 includes a pair capacitor board being arranged on the either side of detection mass body 14.Proximity switch 18 in this embodiment includes electrode 64, and it is depicted as circle in Figure 14 B.In practice, electrode 64 can be deposited and be patterned on the top of sacrifice layer in top wafer 66, is bonded to the electric trace 68 in bottom wafer 70 subsequently.When cantilever detection mass body 14 is pierced, the deep silicon etch of top wafer is defined and when sacrifice layer is removed, the thickness of sacrifice layer is the distance when cantilever detection mass body 14 spaning electrode 64 moves from electrode 64 with the surface of cantilever 14.
From the above description of inertial sensor, it is evident that various technology can be used for the concept implementing inertial sensor without departing from its scope.The embodiment described to be considered illustrative and not restrictive in all respects.Should also be understood that inertial sensor is not limited to specific embodiment as herein described, and be able to many embodiments without deviating from the scope of the present disclosure.
Claims (21)
1. a time domain inertial sensor, including:
Supporting construction, described supporting construction includes the electrode plane that the x-y plane of the coordinate system mutually orthogonal with x-y-z is parallel, and described supporting construction has the maximum sized feature being positioned within described x-y plane；
Detection mass body, described detection mass body includes the first surface parallel with described x-y plane；
Wherein said detection mass body is flexibly coupled to described supporting construction so that described first surface separates with described electrode plane with certain interval；
Driver, described driver is configured to drive described detection mass body generally only to vibrate relative to described supporting construction in the x direction so that in gap described in the duration of oscillation and change indistinctively；And
First time domain proximity switch, described first time domain proximity switch is configured to be switched to closure state from off-state when described detection mass body is in the first reference position relative to described supporting construction.
2. time domain inertial sensor according to claim 1, wherein said supporting construction and described detection mass body are formed via removing of expendable material by single-chip integration and described gap.
3. time domain inertial sensor according to claim 1, wherein said first proximity switch is capacitance-type switch.
4. time domain inertial sensor according to claim 3, wherein said supporting construction includes the half of cover wafer and described capacitance-type switch and is attached to described cover wafer.
5. time domain inertial sensor according to claim 3, wherein said first proximity switch includes being installed to the first the half of described detection mass body and is installed to the second the half of described supporting construction, and the closure state of wherein said first proximity switch is configured to occur at zero crossing place, described zero crossing has the feature of the peak value electric capacity between described the first half and described the second half.
6. time domain inertial sensor according to claim 1, wherein said first proximity switch is optical switch.
7. time domain inertial sensor according to claim 1, wherein said first proximity switch is electron tunneling tip switch, and described electron tunneling tip switch includes the tunnelling tip of the described supporting construction being rigidly attached in described electrode plane；
Wherein said electron tunneling tip switch is further configured to, when the section that described detection mass body is in described first reference position and described first surface is aligned in a z-direction with described tunnelling tip, enable the electron tunneling between described first surface and described tunnelling tip.
8. time domain inertial sensor according to claim 7, wherein said tunnelling tip is electroplated to certain thickness on described z direction, and described thickness is enough to support described tunnelling tip in described detection mass body on the region of its vibration.
9. time domain inertial sensor according to claim 1, wherein said driver includes feedback circuit device, and described feedback circuit device is configured to generate the signal of telecommunication to maintain the operation in resonant condition.
10. time domain inertial sensor according to claim 1, wherein said detection mass body driver includes condenser type pivotal quantity.
11. time domain inertial sensor according to claim 1, farther including multiple time domain proximity switch, each time domain proximity switch is configured to be switched to closure state from off-state when described detection mass body is in relative to the reference position of the correspondence of described supporting construction.
12. time domain inertial sensor according to claim 1, farther including the second time-domain digital proximity switch, described second time-domain digital proximity switch is configured to be switched to closure state from off-state when described detection mass body is in the first reference position relative to described supporting construction.
13. time domain inertial sensor according to claim 11, the described first surface of wherein said detection mass body is T-shaped and includes substrate, cervical region and the first free end and the second free end, wherein said substrate is attached to described supporting construction, described cervical region is operatively coupled to described first proximity switch, described first free end is operatively coupled to the second proximity switch, and described second free end is operatively coupled to the 3rd proximity switch.
14. a time domain inertial sensor, including:
Supporting construction, described supporting construction has top surface, and the x-y plane of the coordinate system that described top surface is mutually orthogonal with x-y-z is parallel；
Detection mass body, described detection mass body is flexibly coupled to described supporting construction so that described detection mass body is configured to generally only vibrate in described x-y plane；
Driver, described driver is configured to drive described detection mass body with relative to described supporting construction harmonic oscillation；And
Multiple proximity switches, the plurality of proximity switch is operatively coupled to described supporting construction and is coupled to multiple respective section of described detection mass body, make each proximity switch be configured to the respective section working as each correspondence of described detection mass body under the section of described supporting construction through out-of-date, be switched to closure state from off-state.
15. inertial sensor according to claim 14, wherein said multiple proximity switch is tunnelling tip switch, and the described section of the supporting construction of described detection mass body process under it is to be rigidly attached to described supporting construction the electrode separated on described z direction from the top surface of described detection mass body with certain interval, and described gap is formed from the period that removes of described supporting construction in sacrificial layer material；
Wherein said electron tunneling tip switch is further configured to, when the section that described detection mass body is in described first reference position and described first surface is aligned in a z-direction with described tunnelling tip, enable the electron tunneling between described first surface and described tunnelling tip.
16. time domain inertial sensor according to claim 14, the described top surface of wherein said detection mass body is T-shaped, and includes substrate, cervical region, the first end and the second end；
Wherein said driver is further configured to drive described cervical region to vibrate on described x direction；And
In response to Coriolis force, described first end and described second end are configured to vibrate in said y direction.
17. time domain inertial sensor according to claim 16, at least one proximity switch in wherein said multiple proximity switches is operatively coupled to each in described cervical region, described first end and described second end.
18. time domain inertial sensor according to claim 14, wherein said proximity switch is capacitance-type switch, each capacitance-type switch includes being installed to the first the half of described detection mass body and is installed to the second the half of described supporting construction, and the described closure state of wherein given capacitance-type switch is configured to occur at zero crossing place, described zero crossing has the feature of the peak value electric capacity between described the first half and described the second half.
19. time domain inertial sensor according to claim 18, described the first half of each proximity switch in wherein said proximity switch include the grounded part of described detection mass body.
20. the method sensing inertia, including:
Drive detection mass body only to vibrate relative to supporting construction in the first dimension so that the gap between described detection mass body and described supporting construction in the duration of oscillation and changes indistinctively in the second orthogonal dimensions；And
When described detection mass body is in the first reference position relative to described supporting construction, it is switched to closure state from off-state.
21. a time domain inertial sensor, including:
Supporting construction, described supporting construction includes the electrode plane parallel with the first plane of mutually orthogonal coordinate system, and described supporting construction has the maximum sized feature being positioned within described first plane；
Detection mass body, described detection mass body includes first surface, described first surface is substantially parallel with described first plane, and described detection mass body is flexibly coupled to described supporting construction so that described first surface separates with described electrode plane with certain interval；
Driver, described driver is configured to drive described detection mass body generally only to vibrate relative to described supporting construction in a first direction so that in gap described in the duration of oscillation and change indistinctively；And
First time domain proximity switch, described first time domain proximity switch is configured to be switched to closure state from off-state when described detection mass body is in the first reference position relative to described supporting construction.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
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| US13/847,539 US9103673B2 (en) | 2011-06-24 | 2013-03-20 | Inertial sensor using sliding plane proximity switches |
| US13/847,539 | 2013-03-20 | ||
| PCT/US2013/071076 WO2014149085A1 (en) | 2013-03-20 | 2013-11-20 | Inertial sensor using sliding plane proximity switches |
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| CN105723184A true CN105723184A (en) | 2016-06-29 |
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| CN201380074890.4A Pending CN105723184A (en) | 2013-03-20 | 2013-11-20 | Inertial sensor using sliding plane proximity switches |
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| EP (1) | EP2976597A4 (en) |
| JP (1) | JP2016520811A (en) |
| CN (1) | CN105723184A (en) |
| TW (2) | TWI528020B (en) |
| WO (1) | WO2014149085A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110780088A (en) * | 2019-11-08 | 2020-02-11 | 中北大学 | Multi-bridge tunnel magnetic resistance double-shaft accelerometer |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US9910061B2 (en) | 2014-06-26 | 2018-03-06 | Lumedyne Technologies Incorporated | Systems and methods for extracting system parameters from nonlinear periodic signals from sensors |
| US9989553B2 (en) | 2015-05-20 | 2018-06-05 | Lumedyne Technologies Incorporated | Extracting inertial information from nonlinear periodic signals |
| US10234477B2 (en) * | 2016-07-27 | 2019-03-19 | Google Llc | Composite vibratory in-plane accelerometer |
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2013
- 2013-11-20 EP EP13879155.3A patent/EP2976597A4/en not_active Withdrawn
- 2013-11-20 JP JP2016504286A patent/JP2016520811A/en not_active Ceased
- 2013-11-20 WO PCT/US2013/071076 patent/WO2014149085A1/en active Application Filing
- 2013-11-20 CN CN201380074890.4A patent/CN105723184A/en active Pending
- 2013-11-22 TW TW102142691A patent/TWI528020B/en not_active IP Right Cessation
- 2013-11-22 TW TW105100962A patent/TW201631298A/en unknown
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| US20050092085A1 (en) * | 2003-11-04 | 2005-05-05 | Shyu-Mou Chen | Solid-state gyroscopes and planar three-axis inertial measurement unit |
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Also Published As
| Publication number | Publication date |
|---|---|
| EP2976597A1 (en) | 2016-01-27 |
| JP2016520811A (en) | 2016-07-14 |
| WO2014149085A1 (en) | 2014-09-25 |
| TWI528020B (en) | 2016-04-01 |
| EP2976597A4 (en) | 2016-11-16 |
| TW201437607A (en) | 2014-10-01 |
| TW201631298A (en) | 2016-09-01 |
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