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WO2018159776A1 - Capteur magnétique - Google Patents

Capteur magnétique Download PDF

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Publication number
WO2018159776A1
WO2018159776A1 PCT/JP2018/007876 JP2018007876W WO2018159776A1 WO 2018159776 A1 WO2018159776 A1 WO 2018159776A1 JP 2018007876 W JP2018007876 W JP 2018007876W WO 2018159776 A1 WO2018159776 A1 WO 2018159776A1
Authority
WO
WIPO (PCT)
Prior art keywords
magnetic field
magnetic
magnetoresistive
detection unit
operational amplifier
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2018/007876
Other languages
English (en)
Japanese (ja)
Inventor
圭 田邊
笠島　多聞
晶裕 海野
将司 ▲高▼橋
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TDK Corp
Original Assignee
TDK Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TDK Corp filed Critical TDK Corp
Publication of WO2018159776A1 publication Critical patent/WO2018159776A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/10—Magnetoresistive devices

Definitions

  • the present invention relates to a magnetic sensor that converts a negative feedback current corresponding to a magnetic field to be detected into a voltage and outputs the voltage.
  • Patent Document 1 discloses a magnetic field detection sensor capable of detecting a minute magnetic field.
  • the magnetic field detection sensor includes a bridge circuit configured to connect a plurality of magnetoresistive effect elements whose resistance values change according to the direction of a magnetic field to be detected, and to output a differential voltage between predetermined connection points.
  • a magnetic body that collects the magnetic field to be detected and changes the direction of the magnetic field to be detected is disposed near the center of the bridge circuit, and the direction of the magnetic field to be detected is opposite to the direction of the magnetic field to be detected.
  • a magnetic field generating conductor that provides a magnetic field and a differential voltage of the bridge circuit are input, and a feedback current that causes the magnetic field generating conductor to generate the magnetic field that is opposite to the direction of the detection target magnetic field is supplied to the magnetic field generating conductor.
  • the magnetic field detection sensor disclosed in Patent Document 1 has a configuration in which a feedback current is converted into a voltage by a resistor and outputs the voltage.
  • the frequency characteristics of the output voltage may not be sufficient. That is, in the configuration of Patent Document 1, when the frequency of the magnetic field to be detected is increased, the output voltage is reduced, and an error in the detected magnetic field occurs.
  • the present invention has been made in recognition of such a situation, and an object of the present invention is to provide a magnetic sensor capable of improving the frequency characteristics of the output voltage.
  • One embodiment of the present invention is a magnetic sensor.
  • This magnetic sensor A magnetic detection unit including at least one magnetic detection element to which a first magnetic field to be detected is applied; A first differential amplifier to which an output voltage of the magnetic detection unit is input; A magnetic field generating conductor that generates a second magnetic field that cancels the first magnetic field in the magnetic detection unit by flowing a negative feedback current output from the first differential amplifier; A detection resistor through which the negative feedback current flows; A second differential having an inverting input terminal connected to one end of the detection resistor on the magnetic field generating conductor side, an output terminal connected to the other end of the detection resistor, and a non-inverting input terminal connected to a fixed voltage terminal And an amplifier.
  • the magnetic detection unit may include a plurality of magnetoresistive elements that are bridge-connected.
  • FIG. 2 is a schematic cross-sectional view of a magnetic detection unit and its vicinity in the magnetic sensor.
  • the schematic plan view. The wiring pattern explanatory drawing of the magnetic field generating conductor in the said magnetic sensor.
  • the schematic diagram which shows the modification of FIG. 1 is a schematic circuit diagram of a magnetic sensor according to an embodiment.
  • the schematic circuit diagram of the magnetic sensor which concerns on a comparative example. 9 is a simplified graph comparing frequency characteristics of output voltages Vout shown in FIGS. 7 and 8.
  • FIG. The simple graph which compared the frequency characteristic of the magnetic resolution of the sensor in each sensor structure of FIG.7 and FIG.8.
  • FIG. 1 is a schematic circuit diagram of a bridge circuit constituting a magnetic detection unit of a magnetic sensor according to an embodiment of the present invention.
  • the bridge circuit includes a first magnetoresistive effect element 10, a second magnetoresistive effect element 20, a third magnetoresistive effect element 30, and a fourth magnetoresistive effect element 40.
  • the fixed layer magnetization directions of the first to fourth magnetoresistive elements (10, 20, 30, 40) are the same.
  • One end of the first magnetoresistance effect element 10 and one end of the second magnetoresistance effect element 20 are connected to a first power supply line to which a first power supply voltage Vcc is supplied.
  • the other end of the first magnetoresistance effect element 10 is connected to one end of the fourth magnetoresistance effect element 40.
  • the other end of the second magnetoresistive element 20 is connected to one end of the third magnetoresistive element 30.
  • the other end of the third magnetoresistive effect element 30 and the other end of the fourth magnetoresistive effect element 40 are connected to a second power supply line to which a second power supply voltage ⁇ Vcc is supplied.
  • the voltage output to the interconnection point between the first magnetoresistance effect element 10 and the fourth magnetoresistance effect element 40 is output to Va, and the voltage output to the interconnection point between the second magnetoresistance effect element 20 and the third magnetoresistance effect element 30.
  • the voltage is Vb.
  • FIG. 2 is a schematic cross-sectional view of a magnetic detection unit and its vicinity in the magnetic sensor according to the embodiment.
  • FIG. 3 is a schematic plan view of the same. 2 and 3, the XYZ axes that are orthogonal three axes are defined. 2 and 3 also show the lines of magnetic force of the magnetic field to be detected.
  • the first to fourth magnetoresistive elements (10, 20, 30, 40) are provided in the multilayer body 5 together with the magnetic field generating conductor 70, and on the surface of the multilayer body 5 A magnetic body 80 is provided. As shown in FIG. 3, the first magnetoresistive element 10 and the third magnetoresistive element 30 have the same position in the X direction.
  • the second magnetoresistive element 20 and the fourth magnetoresistive element 40 have the same position in the X direction. Further, the first magnetoresistive element 10 and the second magnetoresistive element 20 have the same position in the Y direction. Similarly, the third magnetoresistive element 30 and the fourth magnetoresistive element 40 have the same position in the Y direction.
  • the arrangement of the first magnetoresistive effect element 10 and the third magnetoresistive effect element 30 and the arrangement of the second magnetoresistive effect element 20 and the fourth magnetoresistive effect element 40 are axisymmetric in the X direction.
  • A be the center line.
  • the magnetic body 80 is preferably disposed at a position where the center line in the X direction and the center line in the Y direction of the magnetic body 80 match A and B, respectively.
  • the magnetic body 80 extends to the Y direction side of the first magnetoresistive effect element 10 and the second magnetoresistive effect element 20, and ⁇ of the third magnetoresistive effect element 30 and the fourth magnetoresistive effect element 40. It is preferable to extend in the Y direction side. Furthermore, the magnetic body 80 is arranged such that the end face on the laminated body 5 side is closest to the first to fourth magnetoresistive elements (10, 20, 30, 40) in the Z direction, that is, the end face on the laminated body 5 side is laminated. It is preferable to be in contact with the surface of the body 5. By arranging in this way, the resistance change of the first to fourth magnetoresistance effect elements (10, 20, 30, 40) according to the change of the magnetic field to be detected is efficiently and evenly generated.
  • the layer forming the magnetic field generating conductor 70 in the multilayer body 5 is lower than the layer where the first to fourth magnetoresistance effect elements (10, 20, 30, 40) are formed (on the ⁇ Z direction side). Layer).
  • the magnetic body 80 and the first to fourth magnetoresistive elements ( 10, 20, 30, 40) can be made closer to each other in the Z direction, so that the first to fourth magnetoresistive elements (10, 20, 30, 40) can respond efficiently to changes in the detection target magnetic field. become.
  • the magnetic body 80 may be a soft magnetic body.
  • the magnetic body 80 collects the magnetic field to be detected in the Z direction, and the magnetic field to be detected is approximately the same as the fixed layer magnetization direction of the first to fourth magnetoresistive elements (10, 20, 30, 40). Change to parallel direction.
  • FIG. 4 is an explanatory diagram of a wiring pattern of the magnetic field generating conductor 70 in the magnetic sensor of the embodiment.
  • the wiring pattern of the magnetic field generating conductor 70 in the multilayer body 5 is indicated by a solid line.
  • the magnetic field generating conductor 70 is preferably formed in a single layer in the same laminate 5 as the first to fourth magnetoresistive elements (10, 20, 30, 40).
  • the magnetic field generating conductor 70 is a U-shaped planar coil that is less than one turn, but may be a planar coil that circulates a plurality of turns in a spiral shape. Both ends of the magnetic field generating conductor 70 are electrically connected to terminal portions (terminals) 71 and 72 such as through holes, respectively.
  • the magnetic field generating conductor 70 generates a second magnetic field that cancels the detection target magnetic field (first magnetic field) in each magnetoresistive effect element.
  • FIG. 5 is a schematic diagram showing the direction of the magnetic field to be detected at the position of each magnetoresistive element of the bridge circuit shown in FIG. 1 and the change in resistance value of each magnetoresistive element due to this.
  • the magnetic field to be detected is a magnetic field that is entirely parallel to the ⁇ Z direction when the magnetic body 80 is not present, and is partially bent by the presence of the magnetic body 80, so that the first to fourth magnetoresistances At the position of the effect element (10, 20, 30, 40), it has a component in the direction shown in FIG.
  • the direction of the magnetic field to be detected has a component that is the same as the magnetization direction of the fixed layer.
  • the magnetization direction of the free layer coincides with the magnetization direction of the fixed layer.
  • the resistance value changes by ⁇ R from the resistance value R0 in the absence of a magnetic field.
  • the second magnetoresistance effect element 20 since the direction of the magnetic field to be detected has a component opposite to the fixed layer magnetization direction, the free layer magnetization direction is opposite to the fixed layer magnetization direction.
  • the resistance value of the effect element 20 changes by + ⁇ R from the resistance value R0 when there is no magnetic field.
  • the resistance value of the third magnetoresistive effect element 30 changes by - ⁇ R compared to when no magnetic field is applied
  • the resistance value of the fourth magnetoresistive effect element 40 changes by + ⁇ R compared with that when no magnetic field is applied.
  • the bridge circuit of the first to fourth magnetoresistive elements (10, 20, 30, 40) has a differential output, that is, a voltage Va and a voltage Vb that change in opposite directions according to the change in the detection target magnetic field. Output is possible.
  • the differential output can be similarly performed. is there.
  • FIG. 7 is a schematic circuit diagram of the magnetic sensor according to the embodiment.
  • the first to fourth magnetoresistance effect elements (10, 20, 30, 40) connected in a bridge form a magnetic detection unit to which a first magnetic field to be detected is applied.
  • the inverting input terminal is connected to the interconnection point of the first magnetoresistive effect element 10 and the fourth magnetoresistive effect element 40, and the non-inverting input terminal is the second magnetoresistive.
  • the effect element 20 and the third magnetoresistive effect element 30 are connected to the interconnection point, and the output terminal is connected to one end of the magnetic field generating conductor 70.
  • the first operational amplifier 50 receives the output voltage (voltage Va, Vb) of the magnetic detection unit and supplies a negative feedback current to the magnetic field generating conductor 70.
  • the magnetic field generating conductor 70 generates a second magnetic field that cancels out the first magnetic field in the magnetic detection section when a negative feedback current output from the first operational amplifier 50 flows.
  • the first operational amplifier 50 is configured so that the magnetic field generating conductor 70 generates a second magnetic field that cancels the first magnetic field in the magnetic detection unit, that is, a magnetic equilibrium state is established in the magnetic detection unit.
  • a negative feedback current is supplied to the magnetic field generating conductor 70.
  • the detection resistor Rs is provided in the negative feedback current path (connected in series with the magnetic field generating conductor 70).
  • the second operational amplifier 60 as the second differential amplifier has an inverting input terminal connected to one end of the detection resistor Rs on the magnetic field generating conductor 70 side, an output terminal connected to the other end of the detection resistor Rs, and a non-inverting input. The terminal is connected to the ground as a fixed voltage terminal. Both the first operational amplifier 50 and the second operational amplifier 60 are driven by both power sources, and the first power supply line to which the first power supply voltage Vcc is supplied and the second power supply line to which the second power supply voltage ⁇ Vcc is supplied. , Respectively.
  • the voltage at the output terminal of the second operational amplifier 60 becomes the output voltage Vout as the magnetic sensor.
  • FIG. 8 is a schematic circuit diagram of a magnetic sensor according to a comparative example. Compared with the circuit shown in FIG. 7, the circuit shown in FIG. 8 eliminates the second operational amplifier 60, the other end of the detection resistor Rs is connected to the ground, and the voltage at one end of the detection resistor Rs becomes the output voltage Vout. Are different, and are otherwise identical.
  • the output voltage Vout in FIG. 8 is the same as the output voltage Vout in FIG. 7 except that the plus and minus are inverted, but the frequency characteristics are different.
  • FIG. 9 is a simplified graph comparing the frequency characteristics of the output voltages Vout shown in FIGS. This graph represents the magnitude of each output voltage Vout when the magnitude of the detection target magnetic field is constant and the frequency is changed.
  • the current-voltage conversion circuit that converts the negative feedback current into a voltage includes the second operational amplifier 60 in addition to the detection resistor Rs, so that the current-voltage conversion is performed only by the detection resistor Rs.
  • the circuit shown in FIG. 7 is configured to supply the negative feedback current by the first operational amplifier 50 and the second operational amplifier 60, and therefore the circuit of FIG. This is because the burden on the first operational amplifier 50 is reduced as compared with FIG.
  • FIG. 10 is a simplified graph comparing the frequency characteristics of the magnetic resolution of the sensors in the sensor configurations of FIGS. Due to the presence of noise called 1 / f noise whose energy is inversely proportional to the frequency, the resolution of the magnetoresistive element generally becomes better as the frequency of the magnetic field to be detected becomes higher.
  • the frequency characteristic of the first operational amplifier 50 becomes a bottleneck, and the improvement in the resolution when the frequency becomes higher is slowed above a certain frequency.
  • the frequency characteristic of the first operational amplifier 50 becomes a bottleneck when the frequency becomes high even in the high frequency region. By being reduced, the resolution becomes higher in the high frequency region, so that even higher frequency magnetic fields can be detected.
  • the current-voltage conversion circuit for converting negative feedback current into voltage has the second operational amplifier 60 in addition to the detection resistor Rs, the frequency characteristic of the output voltage Vout (for example, frequency characteristic of 100 KHz or more) can be improved. it can. This makes it possible to detect a sudden magnetic field change that could not be detected in the past.
  • the negative magnetic field generating conductor 70 is formed in the same laminate 5 as the first to fourth magnetoresistive elements (10, 20, 30, 40), it is more product than using a separate solenoid coil. In addition to being advantageous for downsizing, it is possible to suppress variations in positional accuracy during manufacturing.
  • the magnetic detection element may be another type such as a Hall element.
  • the number of magnetic detection elements is not limited to the four exemplified in the embodiment, and may be one or more arbitrary numbers.
  • a magnetic detection unit in which four magnetoresistive effect elements are connected in a full bridge has been described as an example.
  • the magnetic detection unit may be a structure in which two magnetoresistive effect elements are connected in a half bridge.
  • One magnetoresistive element and one fixed resistor may be half-bridge connected.
  • the magnetic detection element and the magnetic field generating conductor are not limited to being configured in a common laminated body, and may be provided separately from each other.
  • the magnetic detection unit, the first operational amplifier 50, and the second operational amplifier 60 are not limited to the dual power supply drive, but may be a single power supply drive.
  • a yoke may be formed between the two. By forming the yoke, more magnetic fields can be efficiently guided to the first to fourth magnetoresistive elements (10, 20, 30, 40), so that a minute magnetic field can be detected with high accuracy. Is possible.
  • the yoke is formed by a thin film process, so that it can be placed with high precision in both dimensions and position, and can be formed in the same stacking process, so the cost is lower than the parts attached to the outside. Can be reduced.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Measuring Magnetic Variables (AREA)
  • Hall/Mr Elements (AREA)

Abstract

L'invention concerne un capteur magnétique qui permet d'améliorer les caractéristiques de fréquence d'une tension de sortie. Le capteur magnétique comprend : une unité de détection magnétique comprenant des premier à quatrième éléments à effet de magnétorésistance (10, 20, 30, 40) auxquels un premier champ magnétique à détecter est appliqué ; un premier amplificateur fonctionnel (50) dans lequel une tension de sortie de l'unité de détection magnétique est entrée ; un conducteur de génération de champ magnétique (70) pour générer un second champ magnétique neutralisant le premier champ magnétique dans l'unité de détection magnétique par un flux de courant de rétroaction négative délivré par le premier amplificateur fonctionnel (50) ; une résistance de détection (Rs) vers laquelle circule le courant de rétroaction négative ; et un second amplificateur fonctionnel (60). Le second amplificateur fonctionnel (60) comprend : une borne d'entrée inverseuse connectée à une extrémité côté conducteur de génération de champ magnétique (70) de la résistance de détection (Rs) ; une borne de sortie connectée à une autre extrémité de la résistance de détection (Rs) ; et une borne d'entrée non inverseuse connectée à la terre servant de borne à tension fixe.
PCT/JP2018/007876 2017-03-02 2018-03-01 Capteur magnétique Ceased WO2018159776A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2017-039643 2017-03-02
JP2017039643A JP2018146303A (ja) 2017-03-02 2017-03-02 磁気センサ

Publications (1)

Publication Number Publication Date
WO2018159776A1 true WO2018159776A1 (fr) 2018-09-07

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PCT/JP2018/007876 Ceased WO2018159776A1 (fr) 2017-03-02 2018-03-01 Capteur magnétique

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WO (1) WO2018159776A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116047138A (zh) * 2022-12-28 2023-05-02 国网智能电网研究院有限公司 一种改善隧穿磁阻元件强磁场稳定性的传感器
CN119644062A (zh) * 2024-11-28 2025-03-18 中国南方电网有限责任公司 局部放电检测电路和局部放电检测设备

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7455506B2 (ja) * 2018-11-20 2024-03-26 Tdk株式会社 磁気検出装置及び移動体検出装置
JP2020085574A (ja) * 2018-11-20 2020-06-04 Tdk株式会社 検波回路

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010085228A (ja) * 2008-09-30 2010-04-15 Tdk Corp 電流センサ
JP2013238580A (ja) * 2011-12-28 2013-11-28 Tdk Corp 電流センサ
WO2014006914A1 (fr) * 2012-07-06 2014-01-09 アルプス・グリーンデバイス株式会社 Procédé de fabrication d'un capteur de courant, et capteur de courant

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010085228A (ja) * 2008-09-30 2010-04-15 Tdk Corp 電流センサ
JP2013238580A (ja) * 2011-12-28 2013-11-28 Tdk Corp 電流センサ
WO2014006914A1 (fr) * 2012-07-06 2014-01-09 アルプス・グリーンデバイス株式会社 Procédé de fabrication d'un capteur de courant, et capteur de courant

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116047138A (zh) * 2022-12-28 2023-05-02 国网智能电网研究院有限公司 一种改善隧穿磁阻元件强磁场稳定性的传感器
CN119644062A (zh) * 2024-11-28 2025-03-18 中国南方电网有限责任公司 局部放电检测电路和局部放电检测设备

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