CN105445681A - Resonance-type magnetometer - Google Patents
Resonance-type magnetometer Download PDFInfo
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- CN105445681A CN105445681A CN201410513564.5A CN201410513564A CN105445681A CN 105445681 A CN105445681 A CN 105445681A CN 201410513564 A CN201410513564 A CN 201410513564A CN 105445681 A CN105445681 A CN 105445681A
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- mass
- resonance type
- type magnetometer
- detector structure
- displacement detection
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Abstract
The present invention discloses a resonance-type magnetometer. The resonance-type magnetometer comprises a detector structure body having a mass block and two displacement detection electrodes; a capacitance-to-voltage converter configured to convert the detection result of the detection electrodes to voltage signals which are taken as output signals of the resonance-type magnetometer, and an amplifier; a vibration driving circuit configured to provide the output signals in a current pattern for the mass block to drive the mass block to generate vibration. The vibration driving circuit provided by the invention is able to be a comparator.
Description
Technical field
The present invention relates to a kind of resonance type magnetometer, particularly a kind of must the resonance type magnetometer of external oscillator.
Background technology
Miniature magnetometers is the assembly that one is widely used in such as intelligent mobile phone, wearable type device and Internet of things device (InternetofThings – IOT – devices).Miniature magnetometers also can be applied in Other Engineering, science and industrial application.For providing the function of mgnetic observations in the application in modern times, miniature magnetometers must height aggregation, low power consumption and can provide correct magnetic force/magnetic-field measurement.
In various miniature magnetometers, the magnetometer that application Lorentz force (theLorentzforces) principle makes, comparatively closes in practicality.Because this miniature magnetometers can standard CMOS processing procedure make.In addition, resonance type magnetometer, that is the magnetometer worked under resonant frequency, relatively high susceptibility can be provided, and the reaction that detector produces can utilize and amplifies according to the amplifier designed by its quality factor (qualityfactor – Q-factor or Q value), therefore stronger output signal and preferably signal noise ratio can be provided.With this understanding, novel miniature magnetometers structure, is all application Lorentz force principle, works under its resonant frequency.
The magnetometer of application Lorentz force consists essentially of a mass, with spring suspended structurally or on substrate.Certain electric current is provided to this mass, there is reciprocation in the magnetic field (magneticfield) that this electric current sends with the magnetic field or other magnetic bodies that there is the earth, can Lorentz force be produced, this mass is moved to the direction perpendicular to this direction of current and this magnetic force direction.Detecting electrode forms comb shape or finger-like usually, the comb shape formed with this mass edge or interfingering, and maintains a distance; Between the two every same electric capacity.This detecting electrode can detect because mass moves, and causes mass to change with interelectrode relative position with detecting, the capacitance variation of generation, and produces detection signal.This detection signal through being transformed into voltage form and amplify after, as output signal.The sense of displacement of this mass of the output signal representative produced under magnetic influence and displacement, can calculate this magnetic force value according to this.
Above-mentioned Lorentz force magnetometer is identical substantially for framework and the principle of work of resonance type magnetometer, but when operating, uses one drive circuit that the current signal of one fixed value is provided to this magnetic force block.The frequency of this current signal is identical with the mechanical resonance frequency of this mass, for driving this mass with its resonant frequency vibration.When this mass vibrates under its resonant frequency, capture displacement and displacement that this mass produces because of Lorentz force, the magnetic field suffered by this mass can be calculated according to this.Its signal intensity is higher than the several order of magnitude of non-co-vibration shape Lorentz force magnetometer.
Existing resonance type magnetometer need use an external oscillator mostly, vibrates under its resonant frequency to drive the mass of this micro electronmechanical magnetometer.In this prior art, be the external oscillator of use one, produce the oscillator signal of a fixed frequency, to drive the mass of this magnetometer to vibrate, and its vibration frequency is locked in its resonant frequency.Vibrate under its resonant frequency about the application of this circumscribed oscillator and this mass, for detecting the technology when terrestrial magnetic field, " the SignalConditioningSystemWitha4 – 20mAOutputforaResonantMagneticFieldSensorBasedonMEMSTech nology " one that can deliver with reference to Dominguez-Nicolas is civilian, publication is at SensorsJournal, IEEE, Vol.12, No.5, pp.935-942, May2012.
Though existing resonance type magnetometer uses external oscillator that the mass of this micro electronmechanical magnetometer can be driven to vibrate under its resonant frequency, but the setting of this external oscillator not only can improve cost of manufacture and the volume of magnetometer, the difficulty that this resonant structure corrects more can be caused.Main cause is that the instability of device process itself can make the resonant frequency of the resonant structure of each oscillator change, and cannot reach an agreement.Therefore, magnetometer before the use, has to pass through adjustment, each magnetometer just can be made can to vibrate under its resonant frequency, and lock onto this frequency.In addition, simultaneously also to represent this detector quite narrow as the frequency response bandwidth of oscillator for the high q-factor of micro electronmechanical detector.Such as, if the resonant frequency of micro electronmechanical detector is 1kHz, its Q value is 10,000, then the bandwidth of its frequency response only has 1000/10000=0.1Hz.This characteristic makes this external oscillator must possess the frequency stability of height, can provide the stability of hundreds of ppm level.Moreover, this resonance driving frequency stability also can directly affect its amplitude, and then affects the resolution of gained signal.
Therefore, current industry need provide a kind of novel structure of resonance type magnetometer, to provide stable resonant frequency.
Also need the resonance type magnetometer structure that a kind of novelty is provided, so that its resonant structure is locked in its resonant frequency simultaneously.
Also need to provide a kind of resonance type magnetometer not needing to use external oscillator simultaneously.
Summary of the invention
For the deficiencies in the prior art, object of the present invention is intended to provide a kind of resonance type magnetometer not needing to use external oscillator.
Resonance type magnetometer, comprising: a detector structure, a converter circuit and a vibratory drive circuit.Wherein, this detector structure has a mass, is suspended in this detector structure; Two groups of displacement detection electrodes, are configured on this detector structure, this mass first direction X both sides in the plane.
This converter circuit connects the displacement detection electrode of this detector structure, for the detecting result will exported by this displacement detection electrode, is transformed into voltage signal.This converter circuit can comprise an amplifier, be connected to the rear class of this convert of capacitor to voltage device, amplify for voltage signal that this convert of capacitor to voltage device is exported, export the detection signal after amplifying, the magnetic field magnetic force value providing rear class counting circuit to calculate this displacement detection electrode to detect.This vibratory drive circuit connects the output of this amplifier, this output is provided the mass given in this detector structure with electric current kenel, produces vibration for driving this mass.The electric current that this vibratory drive circuit provides flows through this mass with a second direction Y; This second direction Y in this mass institute in the plane, with the direction of this first direction X orthogonal.This vibratory drive circuit also can provide enlarging function, to amplify the output signal of this amplifier.
In preferred embodiments of the present invention, this vibratory drive circuit can comprise a comparator circuit, is input as the output connecting this amplifier, and a reference potential, for exporting the comparative result of this amplifier output signal and this reference potential, as the vibration drive signal of this mass.The output of this vibratory drive circuit is provided to the mass of this detector structure, vibrates for driving this mass.The frequency of this vibration is the resonant frequency of this mass.The amplitude time of this mass strengthens, and reaches stable after the of short duration time.In preferred embodiments of the present invention, this reference potential is earthing potential.
Accompanying drawing explanation
Fig. 1 is the system diagram of a kind of embodiment of resonance type magnetometer of the present invention.
Fig. 2 is the planimetric map of a kind of detector structure 10 being useful in resonance type magnetometer of the present invention.
Fig. 3 exports Vout (upper figure) to carry out instantaneous analog analysis result with Vdrive (figure below) in the circuit to Fig. 1.
Fig. 4 is the enlarged drawing of Fig. 3.
Fig. 5 is another enlarged drawing of Fig. 3.
Symbol description
10 detector structures
11 masses
11a, 11b finger-like or comb shape are given prominence to
12,13 displacement detection electrodes
12a, 13a finger-like or comb shape are given prominence to
14a, 14b electrode
16,17,18,19 springs
15 clock signal generators
20 converter circuits
30 vibratory drive circuit
21 convert of capacitor to voltage devices
22 amplifiers
Embodiment
Below will adopt various embodiments, the structure of resonance type magnetometer of the present invention will be described.These embodiments are for the possible structure of resonance type magnetometer of the present invention and application are described, are not used for all possible embodiment of exclusive list the present invention.The scope of the claims of the present invention, must record with right and be as the criterion.
Fig. 1 is the system diagram of a kind of embodiment of resonance type magnetometer of the present invention.As shown in the figure, the resonance type magnetometer of the present embodiment comprises: detector structure 10, converter circuit 20, and a vibratory drive circuit 30.This detector structure 10 is the miniature magnetometers structures made by any applicable processing procedure, for providing the detection signal representing magnetic force and magnetic force direction suffered by this structure.This converter circuit 20 comprises a convert of capacitor to voltage device 21, after this detection signal is transformed into voltage kenel, amplifies with amplifier 22, becomes output detection signal.30, this vibratory drive circuit is for driving the mass in this detector structure 10 to vibrate, and its vibration frequency is locked in its resonant frequency.
Fig. 2 is the planimetric map of a kind of detector structure 10 being useful in resonance type magnetometer of the present invention.As shown in the figure, this detector structure 10 has a mass 11, is suspended on this detector structure 10, in suspended state with spring 16,17,18,19.This spring 16,17,18,19 is suspended in this detector structure 10 part, forms two electrode 14a and 14b.
This detector structure 10 also comprises two groups of displacement detection electrodes 12,13, is configured on this detector structure 10, this mass 11 first direction X both sides in the plane.In the embodiments illustrated in the figures, this mass 11 stretches out some finger-like in X-direction both sides or comb shape gives prominence to 11a, 11b.This displacement detection electrode 12,13, in the side of giving prominence to 11a, 11b relative to this finger-like, also respectively extends finger-like or comb shape gives prominence to 12a, 13a.The finger-like of this displacement detection electrode 12,13 gives prominence to 12a, 13a, gives prominence to 11a, 11b along Y-direction vertical with this X-direction in this plane respectively with corresponding mass 11 finger-like, interconnected.Make the finger-like of wantonly two displacement detection electrodes 12,13 give prominence to 12a, 13a, sandwiched mass 11 finger-like gives prominence to 11a, 11b respectively.Certainly, this interconnected form, just a kind of preferred embodiments of the present invention.At miniature magnetometers, and even in the technical field of micro accelerometer, develop various mass finger electrode and the configuration mode of detecting side's finger electrode already, respectively have its relative merits.All can be applicable to the present invention.Moreover this mass and this displacement detection electrode also must not use finger-like or comb electrode.Everyly can be used for detecting this mass either direction and move and the detecting mode of amount of movement, all can be applicable to the present invention.The shape of this mass 11 and displacement detection electrode 12,13, structure is emphasis of the present invention not, and belongs to the category of known techniques, and namely its ins and outs must not added to repeat at this.
This mass 11 and displacement detection electrode 12,13 must possess electric conductor, for the displacement of detecting mass 11 under magnetic influence and sense of displacement.Typically, what use any micro-electromechanical technology to make contains conductor mass and displacement detection electrode, all can be applicable to the present invention.But, in preferred embodiments of the present invention, this this mass 11 is use standard CMOS processing procedure to make with displacement detection electrode 12,13.In such instances, this mass 11 and displacement detection electrode 12,13 all can comprise one or more layers metal level, and this metal level coated or boundary connect the dielectric layer of two metal levels.In addition, the suspension structure of this mass 11 and this spring 16,17,18,19, the making of electrode 14a and 14b etc., the CMOS processing procedure of application standard can complete making.Detailed technology also must not repeat at this.
Current supply is this vibratory drive circuit 30 in the present embodiment, connects this mass 11 by this electrode 14a and 14b.To supply the electric current I drive (j ω) of a second direction Y to this mass 11.This second direction Y refers in this mass 11 institute in the plane, with the direction of this first direction X orthogonal.
This converter circuit 20 connects output V-and the V+ of this detector structure 10, that is the output of this displacement detection electrode 12,13, for the detection signal that this displacement detection electrode 12,13 is exported, be transformed into voltage signal and amplify, export the detection signal Vout after amplifying, the magnetic field magnetic force value providing rear class counting circuit (figure do not indicate) to calculate this detector structure 10 to detect.Output signal Vout after this amplification is the detecting result of resonance type magnetometer of the present invention.According to Lorentz force principle, this output signal Vout is directly proportional to the magnetic force of this mass 11 suffered by Z-direction.
The amplifier 22 of this converter circuit 20 can comprise a wave filter, for leaching in the output signal of this convert of capacitor to voltage device 21, represents the displacement of this mass under Lorentz force impact and the composition of sense of displacement.This wave filter 22 can be a low-pass filter, and its cutoff frequency is greater than mesomerism frequency 5.3kHz and is less than sampling frequency 500kHz.
This vibratory drive circuit 30 is one of emphasis of the present invention.Vibratory drive circuit 30 connects the output Vout of this converter circuit 20, this output signal is provided the mass 11 given in this detector structure 10 with electric current kenel, produces vibration for driving this mass 11.This vibratory drive circuit 30 also provides enlarging function, to amplify the output signal of this converter circuit 20.
In preferred embodiments of the present invention, this vibratory drive circuit 30 comprises a comparator circuit, one is input as the output Vout of this converter circuit 20, another is input as a reference potential Vref, export the comparative result that this converter circuit 20 outputs signal Vout and this reference potential Vref, as resonance drive singal Vdrive, with the form of electric current I drive, be supplied to this mass 11 by electrode 14a and the 14b of this mass 11.The output of this vibratory drive circuit 30 connects the drive singal input Vdrive/Idrive on this detector structure 10, for driving the mass 11 in this detector structure 10, produces vibration.The frequency of this vibration is the resonant frequency of this mass 11.After blink, this mass 11 can be made with its resonant frequency, stable vibration.
This resonance type magnetometer separately can comprise a clock signal generator 15, is connected to this detector 10, for providing the Vm of the frequency signal needed for sampling.
According to the principle of art technology, when supplying the electric current of second direction Y (Y-direction or negative Y-direction) to this mass 11, if magnetic force direction suffered by this mass 11 is to the close direction (negative Z-direction) of drawing, be subject to the traction of Lorentz force, this mass 11 and the displacement that can occur to first direction (negative X-direction or X-direction).If the frequency of this alternating current is identical with the resonant frequency of this mass 11, then this mass 11 will produce the vibration being same as its resonant frequency.
Though not for being restrained by any theory, but find through the present inventor, under foregoing circuit framework, the detection signal that this detector structure 10 exports, after converting electric current to, can be used for driving this mass to vibrate.After this mass 11 starting of oscillation, namely vibration frequency can reach the resonant frequency of this mass 11.Result after this frequency signal compares with a reference potential Vref, the signal amplitude exported can pass through along with the time and amplify, and reaches stable.This mass 11 can with stable amplitude vibration under its resonant frequency.
In preferred embodiments of the present invention, this reference potential Vref is earthing potential.But this reference potential according to the demand in application, can do suitable setting.When this reference potential Vref is earthing potential, as long as the output of this comparer 30 is not 0 current potential, this output will drive this mass 11 starting of oscillation as an electrical current.Its vibration frequency is resonant frequency.And under circuit design of the present invention, the output signal of this comparer 30 can be amplified gradually, until reach stable.Fig. 3 namely show in the circuit to Fig. 1 export Vout (upper figure) and Vdrive (figure below) carry out instantaneous analog analysis result.In the sunykatuib analysis of Fig. 3, this reference potential Vref is set to earthing potential.This instantaneous simulation analysis result display is about starting to vibrate the result within the scope of rear 250ms, and display system is after the of short duration starting stage, and namely vibration reaches stable.Wherein, the amplitude of 114mV and the frequency of Vout, namely input magnetic field 10 μ T with simulated conditions and conform to resonant frequency 5.3kHz.Although this feedback drive singal Vdrive is square wave kenel, the capacitance variations of detector is sine wave signal.This miniature detector is the resonator of a high q-factor, can provide the function of narrow band-pass filter of frequency band.
Fig. 4 is the enlarged drawing of Fig. 3.Show this mass 11 in figure when the output of this comparer 30 is not 0 current potential, can send out and shake.Its amplitude time increases, but frequency is then the resonant frequency of this mass 11.Fig. 5 is another enlarged drawing of Fig. 3.Be presented at input magnetic force in figure and change over 70 μ T by 10 μ T in 1ms, and after maintaining 3ms, become waveform change measured in the process of 10 μ T again.Now, there is good response in Vout, but the frequency of Vdrive unchanged.Prove that resonance type magnetometer of the present invention really can be used for driving mass starting of oscillation, and its vibration frequency is locked in its resonant frequency.This resonance type magnetometer also to make an immediate response suffered magnetic force change, and presents correct measurement result.
In sum, the invention provides a kind of must the resonance type magnetometer of external oscillator.This magnetometer send out shake after the vibration frequency of mass can be locked in its resonant frequency, do not need the external oscillator of use one.The resonance type magnetometer of a kind of novel structure of true genus.
Claims (9)
1. a resonance type magnetometer, comprising:
One detector structure, has a mass, is suspended in this detector structure; Two groups of displacement detection electrodes, are configured on this detector structure, this mass first direction X both sides in the plane;
One converter circuit, connects the displacement detection electrode of this detector structure, for the detecting result will exported by this displacement detection electrode, is transformed into voltage signal; And
One vibratory drive circuit, connects the output of this converter circuit, this output to be supplied to the mass in this detector structure with electric current kenel, as vibration drive signal, produces vibration for driving this mass;
Wherein, the electric current that this vibratory drive circuit provides flows through this mass with a second direction Y;
This second direction Y in this mass institute in the plane, with the direction of this first direction X orthogonal.
2. resonance type magnetometer as claimed in claim 1, it is characterized in that: this vibratory drive circuit comprises a comparator circuit, it is input as the output of this amplifier, and a reference potential, for exporting the comparative result of this amplifier output signal and this reference potential, as the vibration drive signal of this mass.
3. resonance type magnetometer as claimed in claim 2, is characterized in that: this reference potential is earthing potential.
4. the resonance type magnetometer as described in claim 1,2 or 3, is characterized in that: the mass of this detector structure is with spring suspended on this detector structure, and this spring suspended part forms two electrodes; This vibratory drive circuit by this mass of this electrode pair for should the electric current of second direction Y.
5. the resonance type magnetometer as described in claim 1,2 or 3, it is characterized in that: these mass both sides are stretched out some finger-like and given prominence to, this displacement detection electrode is relative to this digitate side, also respectively extend some finger-like to give prominence to, and the finger-like of this displacement detection electrode is given prominence to outstanding interconnected along this Y-direction with the finger-like of corresponding mass respectively.
6. the resonance type magnetometer as described in claim 1,2 or 3, is characterized in that: this mass and displacement detection electrode include one or more layers metal level, and this metal level coated or boundary connect the dielectric layer of two metal levels.
7. the resonance type magnetometer as described in claim 1,2 or 3, is characterized in that: this converter circuit also comprises an amplifier, for being amplified by this voltage signal.
8. resonance type magnetometer as claimed in claim 7, is characterized in that: this amplifier comprises a wave filter, for leaching in this displacement detection electrode detection signal, representing the composition of magnetic field intensity.
9. resonance type magnetometer as claimed in claim 8, is characterized in that: wave filter comprises a low-pass filter.
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| CN201410513564.5A CN105445681A (en) | 2014-09-29 | 2014-09-29 | Resonance-type magnetometer |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1886669A (en) * | 2003-09-23 | 2006-12-27 | 秦内蒂克有限公司 | Resonant magnetometer device |
| US20130027034A1 (en) * | 2010-04-22 | 2013-01-31 | Koninklijke Philips Electronics N.V. | Nuclear magnetic resonance magnetometer employing optically induced hyperpolarization |
| CN106199463A (en) * | 2014-09-18 | 2016-12-07 | 硕英股份有限公司 | Dual-purpose resonance magnetometer |
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- 2014-09-29 CN CN201410513564.5A patent/CN105445681A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1886669A (en) * | 2003-09-23 | 2006-12-27 | 秦内蒂克有限公司 | Resonant magnetometer device |
| US20130027034A1 (en) * | 2010-04-22 | 2013-01-31 | Koninklijke Philips Electronics N.V. | Nuclear magnetic resonance magnetometer employing optically induced hyperpolarization |
| CN106199463A (en) * | 2014-09-18 | 2016-12-07 | 硕英股份有限公司 | Dual-purpose resonance magnetometer |
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Application publication date: 20160330 |