SENSOR ARRANGEMENT FOR POSITION SENSING

• US 20170122780A1
• Filed: 01/17/2017
• Published: 05/04/2017
• Est. Priority Date: 11/28/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: PANTAZI, ANGELIKI, SEBASTIAN, ABU, TUMA, TOMAS
• Granted Patent: US 9,964,419 B2
• Time in Patent Office: Days
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/16 by varying resistance
• CPC Class Codes: G01R 33/09 Magnetoresistive devices
• CPC Class Codes: G01R 33/091 Constructional adaptation of the sensor to specific applications
• CPC Class Codes: G11B 5/39 using magneto-resistive devices or effects
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3932 Magnetic biasing films

Abstract

A sensor arrangement for position sensing comprises a magnetic field source and a magnetoresistive element arranged in a magnetic field generated by the magnetic field source, which magnetoresistive element provides an output signal (R) dependent on a position (x) of the magnetoresistive element relative to the magnetic field source. A feedback controller is configured to receive the output signal (R) of the magnetoresistive element and is configured to adjust one or more of the position (x) of the magnetoresistive element relative to the magnetic field source and a strength of the magnetic field generated by the magnetic field source acting on the magnetoresistive element dependent on the output signal (R) of the magnetoresistive element.

Claims

1. A sensor arrangement for position sensing, comprising

a magnetic field source,

a magnetoresistive element arranged in a magnetic field generated by the magnetic field source and providing an output signal (R) dependent on a position (x) of the magnetoresistive element relative to the magnetic field source, and

a feedback controller configured to receive the output signal (R) of the magnetoresistive element and to adjust one or more of the position (x) of the magnetoresistive element relative to the magnetic field source and a strength of the magnetic field generated by the magnetic field source acting on the magnetoresistive element dependent on the output signal (R) of the magnetoresistive element.

2. The sensor arrangement of claim 1, wherein one of the magnetoresistive element and the magnetic field source is coupled to an object, wherein the feedback controller is configured to determine a position of the object dependent on one or more of:

an adjustment of the strength of the magnetic field generated by the magnetic field source;

the adjustment of the position (x) of the magnetoresistive element relative to the magnetic field source; and

the output signal (R).

3. The sensor arrangement of claim 2, wherein the magnetoresistive element comprises a stack of layers including at least a conductive layer in between two magnetic layers which layers have a longitudinal extension (L) along a longitudinal axis (X) and a lateral extension along a transverse axis (Y), wherein the magnetic field source has a dipole axis (DA) extending along a vertical axis (Z) orthogonal to a plane defined by the longitudinal axis (X) and the transverse axis (Y), and wherein an electrical resistance of the magnetoresistive element depends on a position of the magnet field source along the longitudinal axis (X).

4. The sensor arrangement of claim 3, wherein the object (5) is movable along the longitudinal axis (X) a position of which object (5) along the longitudinal axis (X) is to be sensed by the sensor arrangement.

5. The sensor arrangement of 4, further comprising an actuator for moving one or more of the magnetic field source and the magnetoresistive element relative to each other along the longitudinal axis (X), wherein the feedback controller is configured to adjust the position (x) of the magnetoresistive element along the longitudinal axis (X) relative to the magnetic field source by controlling the actuator.

6. The sensor arrangement of claim 5, wherein the feedback controller is configured to adjust the position (x) of the magnetoresistive element relative to the magnetic field source dependent on a deviation of the output signal (R) of the magnetoresistive element from a reference output (R₀).

7. The sensor arrangement of claim 6, further comprising another actuator for moving one or more of the magnetic field source and the magnetoresistive element along the vertical axis (Z), wherein the feedback controller is configured to adjust a vertical position (z) of the magnetoresistive element along the vertical axis (Z) relative to the magnetic field source by controlling the other actuator, and wherein the feedback controller is configured to adjust the strength of the magnetic field acting on the magnetoresistive element by controlling the other actuator.

8. The sensor arrangement of claim 7, wherein the feedback controller is configured to adjust the strength of the magnetic field acting on the magnetoresistive element dependent on a deviation of the output signal (R) of the magnetoresistive element from a reference output (R₀).

9. The sensor arrangement of claim 8, wherein the feedback controller is configured to adjust the strength of the magnetic field acting on the magnetoresistive element dependent on a deviation of the output signal (R) of the magnetoresistive element from a reference output (R₀).

10. The sensor arrangement of claim 9, wherein the output signal (R) represents a resistance of the magnetoresistive element, wherein the reference output (R₀) represents a constant reference resistance value, and wherein the feedback controller is configured to adapt the one or more of the position of the magnetoresistive element relative to the magnetic field source and the strength of the magnetic field of the magnetic field source to maintain the resistance of the magnetoresistive element equal to the constant reference resistance value.

11. The sensor arrangement of claim 10, wherein the reference output (R₀) is selected from a range of output signal values in which the combination of the magnetoresistive element and the magnetic field source are operated in a non-saturated state.

12. The sensor arrangement of claim 11, wherein the magnetic field source is arranged at a distance D>

0 μ

m from the magnetoresistive element along the vertical axis (Z).