Entitled ultrasensitive micromagnetic sensor

Technical field

[0001]

　The present invention relates to a technique for improving the sensitivity characteristic of GSR sensors by employing the rising pulse detection.
　Here, the GSR sensor ultrafast spin rotation effect (English name; GHz Spin Rotation effect) that ultrasensitive micro magnetic sensor was based.

BACKGROUND

[0002]

　High sensitivity micromagnetic sensor, lateral FG sensor, vertical FG sensor, Hall sensor, GMR sensor, TMR sensors, MI sensors, GSR sensors, high-frequency carrier sensor. Currently, these sensors are smart phones, automotive, medical, has been widely adopted, such as the robot. GSR sensors Among them are excellent in sensitivity surface and size surface, it is the most attention.

[0003]

　Currently, advanced studies to determine the position and orientation equipped with a three-dimensional magnetic sensor utilizing GSR sensors for remote control implementation of in-vivo motion device.
　For mounting the motion devices are sensor size smaller desired, the detection sensitivity is lowered in inverse proportion to it. Further reduction of the power consumption during the measurement there is also restriction of power supply is required.

CITATION

Patent Document

[0004]

Patent Document 1: Japanese Patent No. 5839527

Summary of the Invention

Problems that the Invention is to Solve

[0005]

　The detection method of the GSR sensor, there is a rising pulse detection and two ways falling pulse detection. The former is larger magnetic field sensitivity as 2.5 times the latter, it is possible to reduce power consumption by shortening the pulse time, the linearity is about 1-2%, compared to 0.5% or less of the latter inferior Te.
　An object of the present invention, the linearity of the rising pulse detection is to bring out the advantages of pulse detection rise to below 0.5%.

[0006]

Coil output voltage of the GSR sensor (hereinafter. Referred coil voltage) (that a voltage.) Induced voltage depends on the pulse current and comprises two voltage of the voltage which depends on the external magnetic field (b voltage of.) there. When comparing both of the rising pulse detection and the falling pulse detection, strongly influenced by the pulse current towards the case of the falling pulse detection is close peaks of the two voltages. Moreover a voltage, impedance of the magnetic wire is changed under the influence of the magnetic field by MI effect, as a result, can not be canceled easily because overlapping effect of the magnetic field to a voltage which depends on the pulse current.
That is, if the a voltage is not affected by the magnetic field can be measured a voltage at H = 0G, detects the net b voltage if cancel it.

[0007]

　Research to remove induced voltage depending from the coil voltage of the rising pulse detection to the pulse current is being addressed from 20 years ago, is a difficult problem not yet solved.

Means for Solving the Problems

[0008]

　The present inventors, when flowing one pulse current in the reverse direction by installing the two magnetic wires on the coil, it was found that the coil induced voltage of the rising pulse detection when H = 0G becomes zero (FIG. 7). When there is a magnetic field H, when a current flows in the opposite direction, the coil voltage does not change, it can be seen that detects the b voltage only (Figure 8). That appears to be a voltage is lost.
Furthermore, measurement of the b voltage by changing the magnetic field, symmetrically voltage to positive and negative magnetic field is outputted linearly, found that excellent linearity of 0.3% or less is obtained.　
　When the magnetic field H is changed from zero also, why a voltage disappears, the impedance changes of the two wires regardless of the orientation of the current, both of the impedance for varying symmetrically magnetic field H is always the same , the effect of the pulse current flowing in both the coils of the same next both believed to be because would be canceled even after changing the magnetic field (Fig. 9).

[0009]

　For rising pulse detection, the pulse time since detection rise at the same time can be less than 1 ns (1 ns). On the other hand, if the falling pulse detection, the rising coil voltage is finished attenuation, it is necessary to maintain approximately 10ns pulse time it is necessary to perform the falling pulse detection. Therefore rise Employing pulse detection pulse current consumption can be reduced to 1/10 or less.

[0010]

　Coil voltage of the element made of a magnetic wire 2 of the present invention is twice as compared with the coil voltage of the element consisting of one magnetic wire. Also, the coil voltage of the rising pulse detection is 2.5 times the coil voltage of the falling pulse detection (Figure 10). Compared to GSR sensor described in Patent Document 1, 5 times the coil voltage obtained when the element of the same size.

[0011]

　The relationship between coil voltage and the external magnetic field, it was confirmed that the same as the relational expression of GSR sensors described in Patent Document 1. That,
　Vs = Vo · 2L · [pi] D · p · Nc · f · sin (PaiH / 2 hm) (1)

[0012]

　Here, Vs is the coil voltage, Vo wire permeability, proportionality constant determined by the magnetic properties and the pulse current of the wire material of the saturation magnetic flux density, as the regulator constants, L is the length of the wire, D is the diameter of the wire , p is the skin depth of the pulse current, Nc is the number of turns of the coil, f is the pulse frequency, H is an external magnetic field, Hm is the external magnetic field strength coil output voltage takes the maximum value.

[0013]

　This was arcsine transformation of both sides of the equation (1), 'When, its value in terms of voltage V
V' = arcsin (Vs / Vo · 2L · [pi] D · p · Nc · f) = ([pi · 1/2 hm ) ·
H (2) H = 2 hm / [pi × V '(3)
as can be obtained H from equation (3).
　V 'varies linearly from -Hm to + Hm respect to the magnetic field H. Measurement range Hm, and the enlarged 4 times as compared with the case where no inverse sine transform. Note linearity P as Vx = a (1-Δ) Hx, is defined as P = 100 × Δ (%) ( Figure 11).
That is, define the linearity in the amount of deviation from relation Vx = Ahx when the delta = 0 delta.

[0014]

0 Further than 0.5% is also a deviation amount of the falling pulse of GSR sensors for linearity.
It was confirmed that excellent and 2% (Figure 12).
GSR sensor is enhanced electromagnetic coupling between the magnetic wire and the coil spacing between the magnetic wire and the coil inner diameter as 3μm or less. We shall maintain the same relationship except during two magnetic wire in the present invention.

[0015]

Electronic circuit employs the same circuit as the electronic circuit described in Patent Document 1. Convert frequency 0.2 GHz ~ 4 GHz of the pulse current to be supplied to the magnetic wire, the strength of the pulse current and the strength required to generate the circumferential magnetic field of 1.5 times the anisotropy field on the magnetic wire surface to.
Coil voltage generated during pulse electric current is sent to the sample-and-hold circuit via a pulse corresponding type buffer circuit. If the winding number Nc of the coil is small, it is also possible to send directly to the sample-hold circuit.

[0016]

Detection of the rising pulse is performed by an electronic switch, the detection timing is performed at a peak timing of the coil output waveforms. Since a voltage is not present, the temporal timing of the peak voltage is constant independently of the magnetic field H. But peak timing time, if a voltage is present, changes depending on the magnetic field H, can not strictly be matched to the peak timing of the coil output waveforms. This is the cause of non-linearity.
The capacitance of the capacitor of the sample-and-hold circuit is set to 4pF ~ 100pF. On-off capacitor capacitance finely as possible of undesired electronic switch is also possible to reduce the 4 pF ~ 8 pF. Thereby holding the capacitor voltage of the peak timing as an instantaneous voltage value. The hold A capacitor voltage is output via the programming amplifier.

The invention's effect

[0017]

　GSR sensor rising pulse detection type, it is possible to realize a 5-fold magnetic field detection sensitivity and 1/10 or less of the pulse power with the same element size, a significant reduction in size of the magnetic sensor of the motion device mounted in the body possible to be.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]

FIG. 1 is a plan view of a GSR sensor element in the embodiments and examples.
It is a cross-sectional view of a GSR sensor element along the [Fig 2] A1-A2 line in FIG.
[3] is an electronic circuit diagram of the embodiment and examples.
4 is a graph showing the relationship between the application of the pulse time and the pulse current in the embodiments and examples.
5 is a waveform diagram of the coil voltage when applying the pulse current in the embodiments and examples.
6 is an output waveform diagram of the embodiment and examples.
Is a diagram of the output V when a current of pulse current - [7] the external magnetic field H = 0 in the opposite direction to the two magnetic wires (direction + direction and).
8 is a diagram of the output V obtained while the external magnetic field H = -2G ~ + 2G and varied.
9 is a graph showing the relationship between the external magnetic field H and the impedance Z.
[10] is an output diagram of the coil voltage of the pulse detection and falling pulse detection rise in the magnetic wire one and two.
11 is an explanatory view of a linear P in relation change in the external magnetic field and the output.
[12] Ru relationship diagram der of the magnetic field Hx and the amount of displacement rising pulse of GSR sensors.

BEST MODE FOR CARRYING OUT THE INVENTION

[0019]

　Embodiments of the present invention is as follows.
Incidentally, the configuration of the present invention may be added to selected one or more configuration arbitrarily herein. Whether it is best either embodiment, a different subject, the request characteristics.

[0020]

GSR sensor is a highly sensitive micro magnetic sensor of the present invention,
arranged close to the magnetic field detecting magnetic wire 2 having conductivity over a substrate, circling coil wire energization wound two magnetic wires together sensing the coil voltage generated upon applying the pulse current in the opposite direction to the electrode 2 and the means for flowing a pulse current to the magnetic field detecting element and the magnetic wire two electrodes were placed in the coil voltage detection and two magnetic wire It consists of a means for converting the circuit and the coil voltage to the external magnetic field H,
magnetic wires, central with spin alignment in the surface domain and axially having the following anisotropy field 20G, and having a circumferential spin sequence becomes a two-phase domain structure parts core domain,
pulse current supplied to the magnetic wire, the frequency is 0.2 GHz ~ 4.0 GHz, the wire 1.5 times the anisotropy field on the surface circumference of Not less than the current intensity necessary to generate direction magnetic field,
the coil is less coil pitch 10 [mu] m. The coil average inner diameter 35μm or less.
Further, when arranging a plurality of pairs of wires, the spacing between the coil and the magnetic wire is preferably set to 1 [mu] m ~ 5 [mu] m.

[0021]

Further, GSR sensor is ultrasensitive micro magnetic sensor of the present invention,
by energizing the pulse current to the magnetic wire, a circumferential spin inclined in the axial direction by the magnetic field of the wire axis in the surface domain ultrafast rotate simultaneously extracts only the axial direction of the magnetization change of the wire by using ultrafast spinning phenomenon occurring at that time as the coil output, and converts the magnetic field H with the equation (1).
Vs = Vo · 2L · πD ·p · Nc · f · sin (πH / 2Hm) (1)
where, Vs is the coil output voltage, Vo is a proportionality constant, as the regulator constants, L is the length of the wire, external magnetic field intensity when D is the skin depth of the wire diameter, p is the pulse current, Nc is the number of turns of the coil, f is the pulse frequency, Hm is the coil output voltage takes a maximum value.

[0022]

Moreover, the electronic circuit of the GSR sensor is ultrasensitive micro magnetic sensor of the present invention,
a pulse transmission circuit for transmitting a pulse current, the peak of the output waveform of the input circuit, the pulse corresponding type buffer circuit and the coil voltage input coil voltage constructed from the sample-and-hold circuit comprising a capacitor 4 ~ 100 pF capacitor to store an electronic switch and a peak voltage for detecting a voltage and amplified by programming the amplifier, and connects to an electronic circuit that converts AD (analog-digital) .

[0023]

Embodiments of the present invention will be described in detail with reference to FIGS.
GSR sensor element (hereinafter, referred to as elements.) 1, two electrodes of magnetic wire 2 (21 and 22) and one coil 3 and wire energization orbiting the two that magnetic wire on the substrate 10 consists (24 and and 25) and two electrodes (33 and 34) and the connecting portion between the magnetic wire and the wire current-carrying electrodes, connecting portions of the coil and the coil voltage detection electrode for the coil voltage detection. Further, it comprises means 23 for supplying a pulse current in the opposite direction to the two magnetic wires (21 and 22) the element 1. Then, and a means for converting circuit 5 and the coil voltage for detecting the coil voltage generated upon applying a pulse current to the external magnetic field. The external magnetic field H and the coil voltage Vs is expressed by the mathematical relationship as in the above formula (1).

[0024]

　
　structure of the element 1 are shown in FIGS. 1-2.
　The size of the element 1, the width 0.07 mm ~ 0.4 mm which is the size of the substrate 10, made of a length 0.25 mm ~ 1 mm. The middle of the device 1, the width 20 ~ 60 [mu] m as magnetic wire 2 (21 and 22) can be aligned parallel arrangement, a groove depth of 2 ~ 20 [mu] m are formed on the substrate 10. The two magnetic wires (21 and 22) the spacing of the magnetic wire is close is 1 ~ 5 [mu] m, magnetic wire (21 and 22) each other that are separated by an insulating material, for example insulating separation wall preferable.

[0025]

　
　magnetic wire 2 has a diameter 5 ~ 20 [mu] m of CoFeSiB amorphous alloy. Around the magnetic wire 2 is preferably covered with an insulating material, for example insulating glass. And a length of 0.07 ~ 1.0mm.
　Anisotropic magnetic field of the magnetic wire 2 is 20G or less, with a two-phase domain structure of the central portion core domain with spin alignment in the surface domain and the axial direction having a circumferential spin sequence.

[0026]

　
　coils 3, the number of coil turns is 6-180 times, coil pitch 5μm is preferred. Distance between the coil 3 and the magnetic wire 2 is preferably 3μm or less. Coil average inner diameter is preferably 10 ~ 35 [mu] m.

[0027]

　
　manufacturing method for the device will be described with reference to FIG.
　Performing an electrode wiring on the lower coil 31 and the substrate surface along the groove 11 formed on the substrate 10. Thereafter, the two grooves shaped to form an insulating separation wall 41 in a central portion of the groove 11, to which the two respective aligning magnetic wire 21 and 22 and the glass coating. Then, applying the insulating resist on the entire surface of the substrate. Thus magnetic wire 21 and 22 are fixed in the groove 11. The upper part of the magnetic wire 21 and 22 upon application is thinly coated. Forming an upper coil 32 in the photolithography therein.
　In the case of using the magnetic wire 2 that is not glass coating is to the lower coil 31 and the magnetic wire 21 and 22 keep applying the pre-insulation material 4 so as not to cause electrical contact.

[0028]

　Preparation of the coil, the lower coil 31 recessed along opposite sides of the groove surface and the groove 11 of the groove 11 formed in the substrate 10 is formed. On the coil 32 of the convex shape is that the electrical connection and the lower coil through the joint portion 33, the helical coil 3.

[0029]

　The ends of the two magnetic wires 21 and 22, to enable electrical connection by metal deposition and removing the glass of the insulating coating.

[0030]

　
　wiring structure of the magnetic wire 2, as shown in FIG. 1, the wire input electrode (+) 24 is connected to the upper portion of the magnetic wire 21, the lower portion of the magnetic wire 21 is a wire connecting portion It is connected to the lower part of the magnetic wire 22 through 23. Top of the magnetic wire 22 is a wire output electrode - is connected to the 25 (). The wire connecting portion 23, a downward pulse current to the lower stream from the upper the magnetic wire 21 passes a pulse current (in the opposite direction. The magnetic wire 21) upward from the lower the magnetic wire 22 to the upper be able to.

[0031]

　Wiring structure of the coil 3, as shown in FIG. 1, the coil output electrode (+) 33 is connected to the lower end of the coil 3, an upper end portion of the coil 3 is a coil ground electrode - is connected to the 34 ().

[0032]

　
　electronic circuit 5, the pulse transmission circuit 51 for transmitting a pulse current, an input circuit 53 for inputting the coil voltage, pulse-responsive buffer circuit 54, an electronic switch 56 for detecting the peak voltage of the output waveform of the coil voltage sample-and-hold circuit comprising a capacitor 4 ~ 100 pF capacitor for holding a peak voltage, and then amplified by programming the amplifier of the amplifier 58 performs AD conversion.
　Further, GSR sensor element is connected to output the coil voltage of the electronic circuit 5.

[0033]

　Conversion frequency of the pulse current at 0.2 ~ 4 GHz, the intensity of the pulse current is 50 ~ 200 mA, pulse time is 0 ~ 2 nsec. Figure 4 shows the relationship between the application of the course and a pulse current of the energizing time when energized pulse current to the GSR sensor element. In the example of FIG. 4, the rising in 0.5nsec When starting the energization, maintaining a predetermined pulse time 0.5nsec in its applied state, it falls in 0.5nsec when deenergized.

[0034]

　
　5 shows a waveform diagram of a coil voltage when energized the above pulse current.
　In the present invention, it detects the timing of the peak voltage. Electronic switch its opening and closing times consists of on-off is repeated at 0.1 ~ 1.5nsec.

[0035]

　Capacitance of the sample-and-hold circuit is set to 4 ~ 100 pF, AD conversion of the electronic circuit is 14 to 16 bits. The capacitor capacitance to finely on-off of the electronic switch is preferably 4 ~ 8 pF.
　Coil output is a measurement range 3 ~ 100G in a sine wave output as shown in FIG. 6, the sensitivity is 50mG / G ~ 3V / G. Linearity is 0.3% or less.

Example

[0036]

A plan view of a GSR sensor device according to Example shown in FIG. 1 shows a sectional view thereof in FIG. Also shown in FIG. 5 the electronic circuit. GSR sensor of the present invention, magnetic wire 2 (21 and 22) and two electrodes (24 and 25) and detection coil voltage of one coil 3 and wire energization circling together two magnetic wire converting electrode and GSR sensor element 1 composed of (33 and 34), a circuit and a coil voltage for detecting the coil voltage generated upon applying means and the pulse current a pulse current to the magnetic wire 2 to an external magnetic field H It is composed of a unit. The external magnetic field H and the coil voltage is expressed by the mathematical relation shown in Equation (1).

[0037]

The size of the element 1 has a length 0.12 mm, the width of the groove 11 of the substrate 10 at a width 0.20mm is 40 [mu] m, the depth 8 [mu] m. Wire spacing is 3 [mu] m.

[0038]

Magnetic wire (21 and 22), the diameter 10μm of CoFeSiB amorphous alloys are glass coated the following thickness 1 [mu] m, a wire length 0.12 mm.
Anisotropic magnetic field is 15G.

[0039]

Coil 3, the number of turns in coil pitch 5μm is 14 times, the average inner diameter of the coil 3 is the distance between the coil 3 and the magnetic wire 2 at 30μm is 2 [mu] m.

[0040]

Structure of the element, as shown in FIG. 2, a half of the diameter of the glass coated magnetic wire (21 and 22) embedded in a groove 11 formed in the substrate 10, the lower coil 31 on the inner surface of the groove 11 It was placed, the upper coil 32 is disposed on top of the magnetic wire, between them were joined with the joint portion 33 on the substrate plane is fixed with an insulating resin.
Both end portions of the coil 3, between the respective coil electrodes provided electrical connections with a conductive metal evaporated film.
Magnetic wire 2 and the electrode, after removing the glass coating material of the upper surface of the end of the magnetic wire, provided the electrical junction with a conductive metal evaporated film between the covering removed wire surface and the electrode.
Moreover, it was performed electrically connected by the connecting portion 23 a similar process with the two magnetic wire 21 and the magnetic wire 22.

[0041]

Equipped with a GSR sensor element 1 to the electronic circuit 5, and energizing pulse transmission circuit 51 from the converted frequency 1 GHz, at the intensity of the pulse current 120mA in pulse width 0.8Nnsec. Interval of on-off of the electronic switch at that time is 0.2nsec. The capacitance of the capacitor of the sample-and-hold circuit is 6pF.

[0042]

16 bits are obtained by AD conversion. Further, the sine wave output, the sensitivity in the measurement range 90G could be obtained 200 mV. In the power consumption at that time 0.3 mW, linearity was obtained 0.2%.

Industrial Applicability

[0043]

The present invention, higher sensitivity of the GSR sensor, intended to reduce power consumption, used in applications requiring high performance at ultra-compact is expected as the motion device in vivo.

DESCRIPTION OF SYMBOLS

[0044]

1: GSR sensor element, 10: substrate, 11:
groove, 2: magnetic wire, 21: magnetic wire 2 one of the, 22: other one of the magnetic wire 2, 23: wire connecting portion , 24: wire input electrode (+), 25: wire output electrode (-), 3: coil, 31: lower coil, 32: upper coil, 33: joint part, 34: coil output
electrode (+), 35: coil a ground electrode
(-), 4: insulating resin, 41: insulating separating
wall, 5: electronic circuit, 51: pulse transmission circuit, 52: GSR sensor element, 53: input circuit, 54: a buffer circuit, 55: sample hold circuit, 56: electronic switch, 57: capacitor, 58: amplifier

The scope of the claims

[Requested item 1]

Placed close magnetic field detecting magnetic wire 2 having conductivity on a substrate, the magnetic two circling coil wound two wires together and electrodes for wire energization and installed two coil voltage detecting electrodes means for converting circuit and the coil voltage to an external magnetic field H for detecting the the magnetic field detecting element and the coil voltage generated upon applying the pulse current in the reverse direction to the magnetic wire and means for supplying a pulse current the two magnetic wires in the magnetic sensor consisting of
the magnetic wire, two-phase domain structure of the central portion core domain with spin alignment in the surface domain and axially having the following anisotropy field 20G, and having a circumferential spin sequence the result has,
the pulse current to be supplied to the magnetic wire, said frequency is 0.2 GHz ~ 4.0 GHz, to generate a circumferential magnetic field of 1.5 times the anisotropy field on the wire surface A current intensity more than necessary, the
ultra-sensitive micro magnetic sensor the coil is characterized by the following coil pitch 10 [mu] m.

[Requested item 2]

In ultrasensitive micro magnetic sensor of claim 1,
wherein by energizing the pulse current, the wire axis ultrafast circumferential spin inclined in the axial direction by the magnetic field in the surface magnetic domains in the magnetic wire ultrahigh which rotate simultaneously, extracts only the axial direction of the magnetization change of the wire by using ultrafast spinning phenomenon occurring at that time as the coil output, and converting the magnetic field H with the equation (1) to sensitivity micromagnetic sensor.
Vs = Vo · 2L · πD ·p · Nc · f · sin (πH / 2Hm) (1)
where, Vs is the coil output voltage, Vo is a proportionality constant, as the regulator constants, L is the length of the wire, external magnetic field intensity when D is the skin depth of the wire diameter, p is the pulse current, Nc is the number of turns of the coil, f is the pulse frequency, Hm is the coil output voltage takes a maximum value.

[Requested item 3]

In ultrasensitive micro magnetic sensor according to claim 1,
the electronic circuit, a pulse transmission circuit for transmitting the pulse current, the input-side circuit, the output waveform of the pulse corresponding type buffer circuit and the coil voltage to enter the coil voltage constructed from the sample hold circuit comprising a capacitor capacitance 4 ~ 100 pF for storing the peak voltage and electronic switch for detecting the peak voltage, it is amplified by programming amplifier, and characterized in that connected to the electronic circuit for AD conversion ultrasensitive micro magnetic sensor for.