Crossfield Sensitivity in AMR Sensors

Ripka, Pavel; Janošek, Michal; Butta, Mattia

doi:10.1109/tmag.2009.2022051

Cited by 23 publications

(4 citation statements)

References 9 publications

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“…As a result, the sensitivity changes as the sensor moves, which leads to a nonlinear transfer curve with respect to out-of-plane field, which may not precisely reflect the sinusoidal field profile of the scale. In fact, the sensitivity affected by the presence of the orthogonal field to the sensing direction, so-called the cross-field effect, is also observed in other types of MR sensors [ 22 , 23 ]. Its effects on the position accuracy will be discussed later.…”

Section: Resultsmentioning

confidence: 99%

Alignment-Free Sensing Module for Absolute and Incremental Lines in Linear Positioning System Based on Tunneling-Magnetoresistance Sensors

Lee

Yen

Lai

2021

Sensors

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An alignment-free sensing module for the positioning system based on tunneling magnetoresistive (TMR) sensors with an absolute-incremental-integrated scale is demonstrated. The sensors of the proposed system for both lines consist of identical layer stacks; therefore, all sensors can be fabricated in identical processes from thin film deposition to device patterning on a single substrate. Consequently, the relative position of the sensors can be predefined at the lithography stage and the alignment error between sensors caused by the manual installation is completely eliminated. Different from the existing sensing scheme for incremental lines, we proposed to utilize the magnetic tunnel junctions with a perpendicular anisotropy reference layer and an in-plane anisotropy sensing layer. The sensors are placed parallel to the scale plane with magnetization of the sensing layer in the plane, which show the capability of polarity detection for the absolute line and reveal sinusoidal output signal for the incremental line. Furthermore, due to the large signal of TMR, the working distance can be further improved compared with conventional sensors. In addition, the cost of the positioning system is expected to be lowered, since all the sensors are fabricated in the same process without extra installation. Our design may pave a new avenue for the positioning system based on a magnetic detection scheme.

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Section: Resultsmentioning

confidence: 99%

Alignment-Free Sensing Module for Absolute and Incremental Lines in Linear Positioning System Based on Tunneling-Magnetoresistance Sensors

Lee

Yen

Lai

2021

Sensors

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“…reversing the remanent magnetization of the magnetic layer by applying SET/RESET pulses into the flipping coil. Flipping pulses should have large amplitude to restore single-domain state of the sensor core [6]. The flipping field has the same direction as the crossfield.…”

Section: Amr Sensorsmentioning

confidence: 99%

Crossfield response of industrial magnetic sensors

Ripka¹,

Vyhnánek²,

Chirtsov³

2017

JAE

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Magnetic sensors used for non-destructive testing, metal detection and other applications are subjected to large perpendicular field. In this paper we show that the existing models describing the response of anisotropic magnetoresistors (AMR) cannot be used for fields larger than the critical value, which is 350 µT for the Honeywell HMC1001. This critical value is one order of magnitude lower than the anisotropy field and it is decreasing with increased value of the measured field. From our findings it is clear that AMR sensors cannot be safely used in applications in which fields above 250 µT can appear. Neither flipping, nor feedback compensation can compensate for this error. We show that this behaviour is caused by the fact that the single-domain state of the AMR is broken at the mentined critical field. Compared to that, fluxgate sensors including microfluxgates are by principle immune against the crossfield. Unlike in AMR, crossfield sensitivity in fluxgate sensors is second-order effect, which can be kept under control by proper design. We show that even crossfield of 10 mT does not cause significant degradation of the sensor precision.

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“…it is modulated by the flipping frequency. Flipping brings also other advantages: 1. suppression of the sensor offset 2. suppression of the crossfield effect [7] 3. doubling the sensitivity Anisotropic magnetoresistors were already used in eddycurrent NDT with high spatial resolution [8]. Compared to induction coil, AMR sensors have smaller size and their response is to some limit frequency independent.…”

Section: B Amr Position Sensormentioning

confidence: 99%

AMR Proximity Sensor With Inherent Demodulation

et al. 2014

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Our novel position sensor is based on the combination of the eddy-current and permeability effects. The primary field is excited by a coil, but instead of induction coil, the sensing part uses anisotropic magnetoresistor (AMR) which also measures DC magnetic field. As the AMR is being flipped at the excitation frequency, the sensor is self-demodulated and the output is DC. The AMR sensitivity does not depend on frequency; therefore this sensor can be used at ultralow frequencies, where coils fail as sensors. We show the response of our sensor to ferromagnetic and non-ferromagnetic metals and possibilities to distinguish between them. We also show that our sensor can measure position through the conducting sheath.

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Crossfield Sensitivity in AMR Sensors

Cited by 23 publications

References 9 publications

Alignment-Free Sensing Module for Absolute and Incremental Lines in Linear Positioning System Based on Tunneling-Magnetoresistance Sensors

Alignment-Free Sensing Module for Absolute and Incremental Lines in Linear Positioning System Based on Tunneling-Magnetoresistance Sensors

Crossfield response of industrial magnetic sensors

AMR Proximity Sensor With Inherent Demodulation

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