INDUCTIVE POSITION DETECTION

• US 20160069662A1
• Filed: 07/16/2015
• Published: 03/10/2016
• Est. Priority Date: 09/08/2014
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Reitsma, George, Mullenix, Joyce
• Granted Patent: US 11,226,211 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01D 5/202 by movable a non-ferromagnetic conductive element G01D5/2033 takes precedence
• CPC Class Codes: G01D 5/22 differentially influencing two coils
• CPC Class Codes: G01D 5/2225 by a movable non-ferromagnetic conductive element
• CPC Class Codes: G06F 3/00 Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements

Abstract

A position detecting system detects and responds to the movement of a target through a sensing domain area of a plane. The movement causes the amount of the target that lies within a first sensing domain area of a first sensor to change. A second sensor detects a height from the plane to a sensor for enhancing accuracy of measurements from the first sensor.

Claims

1. A system, comprising:

a first sensor having a coil, the coil having a longitudinal axis, the coil operable to generate a time varying magnetic field, the time varying magnetic field having a plurality of magnetic field lines intersecting a first sensing domain area associated with a plane, the plane being substantially orthogonal to the longitudinal axis;

a second sensor operable to measure a relative distance for determining a distance from the first sensor to a point substantially stationary with respect to the plane; and

a first target being movable within the plane, a portion of the first target lying within the first sensing domain area associated with the plane.

2. The system of claim 1, wherein the coil has a coil characteristic that changes as the first target moves within the first sensing domain area associated with the plane.

3. The system of claim 2, wherein the first target receives an amount of magnetic flux from the time varying magnetic field, wherein the amount of magnetic flux received by the first target changes as the first target moves within the plane;

and wherein the coil characteristic changes in response to changes of the amount of magnetic flux received by the first target.

4. The system of claim 2, wherein the coil characteristic is an inductance of the coil.

5. The system of claim 2, wherein the coil characteristic is a quality factor of the coil.

6. The system of claim 3, comprising a processing circuit operable to determine a positioning of the first target with respect to a position of the first sensor in response to the coil characteristic, and in response to the distance measured by the second sensor.

7. The system of claim 6, comprising a support structure connected to the first sensor and the first target, the first target being shaped to variably cover the first sensing domain area associated with the plane position in response to a movement of the first target within the plane, and the coil characteristic having an amplitude in measured in accordance with a coupling factor in response to the measured distance.

8. The system of claim 7, wherein the positioning is changed in response to a translation of the first target relative to the plane.

9. The system of claim 7, wherein the positioning is changed in response to a rotation of the first target relative to the plane.

10. The system of claim 7, wherein the processing circuit is operable to determine the positioning of the first target with respect to a position of the first sensor in response to the coil characteristic and the measured distance.

11. The system of claim 7, wherein the second sensor is operable to generate a reference coil characteristic in response to a second target being movable within the plane, a portion of the second target lying within a second sensing domain area associated with the plane, the second target being moveable in tandem with the first target.

12. The system of claim 7, wherein the reference coil characteristic in response to a second target positioned within the plane, a portion of the second target lying within a second sensing domain area associated with the plane, the area of coverage of the second sensing domain area by the second target not being substantially changed in response to a movement of the first target.

13. A system, comprising:

a first sensor having a coil, the coil having a longitudinal axis, the coil operable to generate a time varying magnetic field, the time varying magnetic field having a plurality of magnetic field lines intersecting a first sensing domain area associated with a surface, the surface having a line tangent substantially orthogonal to the longitudinal axis;

a second sensor operable to measure a relative distance for determining a distance from the first sensor to the surface;

a first target movable along the surface, a portion of the first target variably covering the first sensing domain area of the surface; and

a processor operable to determine a positioning of the first target in response to a coil characteristic of the first sensor and in response to the distance measured by the second sensor.

14. The system of claim 13, wherein the coil characteristic changes as the first target moves within the first sensing domain area of the surface.

15. The system of claim 14, wherein the processor is operable to scale first sensor quantities in response to the distance measured by the second sensor, the first sensor quantities including information of coverage of the first sensing domain area.

16. The system of claim 15, wherein the processor is operable to determine the positioning of the first target in response to a ratio of a coverage of the first sensing domain area measured by the first sensor to a coverage of a second sensing domain area measured by the second sensor.

17. The system of claim 16, wherein the coverage of a second sensing domain area measured by the second sensor changes in response to movement of a second target.

20. The system of claim 15, wherein the positioning of the target is determined in response to a ratio of a coverage of the first sensing domain area measured by the first sensor to a coverage of a second sensing domain area measured by the second sensor.

18. A method, comprising:

generating a time varying magnetic field, the time varying magnetic field having a plurality of magnetic field lines extending from a first sensor and intersecting a first sensing domain area associated with a surface, the surface having a line tangent substantially orthogonal to the longitudinal axis;

determining a distance from the first sensor to a point substantially stationary with respect to the surface, wherein the distance is determined using a second sensor;

moving a target along the surface, a portion of the target variably covering the first sensing domain area of the surface, a coil characteristic of the first sensor being changed in response to the movement of the target; and

determining a positioning of the target in response to the coil characteristic of the first sensor and in response to the determined distance.

19. The process of claim 18, comprising scaling first sensor quantities in response to the determined distance, the first sensor quantities including information of coverage of the first sensing domain area.