Magnetic shield for use in a location sensing system

• US 7,787,259 B2
• Filed: 12/28/2006
• Issued: 08/31/2010
• Est. Priority Date: 12/28/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Hauck, Karl P., Free, M. Benton, Geaghan, Bernard O., Libbey, Albert H., Weaver, Billy Lee
• Primary Examiner(s): Levi; Dameon E
• Application Number:
  US11/617,352
• Publication Number:
  US 20080158848A1
• Time in Patent Office: 1,342 Days
• Field of Search: 361/800, 361/816, 361/818, 345/173, 178/18.07, 174/350
• US Class Current: 361/816
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• CPC Class Codes: G06F 3/046 by electromagnetic means
• CPC Class Codes: H05K 9/0075 Magnetic shielding materials

Abstract

An energy transfer apparatus with a magnetic shield is configured to magnetically couple energy from a fixed location to a mobile or moveable device within a field-activated space of the energy transfer apparatus. Apparatuses include a location sensing surface and a drive coil arranged in relation to a periphery of the location sensing surface. A magnetic shield plate is disposed below the location sensing surface and the drive coil. The shield plate includes a number of radially oriented slots originating at, and distributed about, a periphery of the shield plate.

Claims

1. An apparatus, comprising:

a location sensing surface;

a drive coil arranged in relation to a periphery of the location sensing surface; and

a magnetic shield plate disposed below the location sensing surface and the drive coil, the shield plate comprising a plurality of radially oriented slots originating at, and distributed about, a periphery of the shield plate,

wherein the shield plate has relatively low reluctance along a first direction, and the shield plate has relatively high reluctance along a second direction, wherein the first direction is approximately orthogonal to the second direction.

2. An apparatus, comprising:

a location sensing surface;

a drive coil arranged in relation to a periphery of the location sensing surface; and

a magnetic shield plate disposed below the location sensing surface and the drive coil, the shield plate comprising a plurality of radially oriented slots originating at, and distributed about, a periphery of the shield plate,

wherein the shield plate has relatively low reluctance along a radial direction, and the shield plate has relatively high reluctance along a circumferential direction.

3. An apparatus, comprising:

a location sensing surface;

a drive coil arranged in relation to a periphery of the location sensing surface; and

a magnetic shield plate disposed below the location sensing surface and the drive coil, the shield plate comprising a plurality of radially oriented slots originating at, and distributed about, a periphery of the shield plate,

wherein the shield plate has relatively low electrical resistance along a first direction, and the shield plate has relatively high electrical resistance along a second direction, wherein the first direction is approximately orthogonal to the second direction.

4. An apparatus, comprising:

a location sensing surface;

a drive coil arranged in relation to a periphery of the location sensing surface; and

a magnetic shield plate disposed below the location sensing surface and the drive coil, the shield plate comprising a plurality of radially oriented slots originating at, and distributed about, a periphery of the shield plate,

wherein the shield plate has relatively low electrical resistance along a radial direction, and the shield plate has relatively high electrical resistance along a circumferential direction.

5. An apparatus, comprising:

a location sensing surface;

a drive coil arranged in relation to a periphery of the location sensing surface; and

a magnetic shield plate disposed below the location sensing surface and the drive coil, the shield plate comprising a plurality of radially oriented slots originating at, and distributed about, a periphery of the shield plate,

wherein the shield plate has relatively low reluctance along a first direction, and the shield plate has relatively high electrical resistance along a second direction, wherein the first direction is approximately orthogonal to the second direction.

6. The apparatus of claim 5, wherein first and second directions vary relative to one another across a surface of the shield plate.

7. The apparatus of claim 5, wherein first direction is oriented in alignment with a direction of a magnetic field generated by the drive coil.

8. An apparatus, comprising:

a location sensing surface;

a drive coil arranged in relation to a periphery of the location sensing surface; and

a magnetic shield plate disposed below the location sensing surface and the drive coil, the shield plate comprising a plurality of radially oriented slots originating at, and distributed about, a periphery of the shield plate,

wherein the shield plate has relatively low reluctance along a radial direction, and the shield plate has relatively high electrical resistance along a circumferential direction.

9. An apparatus, comprising:

a location sensing surface;

a drive coil arranged in relation to a periphery of the location sensing surface; and

a magnetic shield plate disposed below the location sensing surface and the drive coil, the shield plate comprising a plurality of radially oriented slots originating at, and distributed about, a periphery of the shield plate,

wherein at least some of the slots have a curved portion situated near or at the drive coil, the curved portion oriented substantially perpendicular to the drive coil.

10. An apparatus, comprising:

a location sensing surface;

a drive coil disposed relative to a periphery of the location sensing surface; and

a magnetic shield plate disposed below the location sensing surface and the drive coil, the shield plate formed to provide a relatively low reluctance and electrical resistance in a first direction, and a relatively high reluctance and electrical resistance in a second direction, the second direction differing from the first direction.

11. The apparatus of claim 10, wherein the first direction is a substantially radially inward direction relative to a periphery of the shield plate, and the second direction is a substantially circumferential direction relative to the periphery of the shield plate.

12. The apparatus of claim 10, wherein the first direction is substantially orthogonal to the second direction.

13. The apparatus of claim 10, wherein the first and second directions change relative to one another as a function of position across a surface of the shield plate.

14. The apparatus of claim 10, wherein the first direction is oriented generally in alignment with a direction of a magnetic field generated by the drive coil.

15. The apparatus of claim 10, wherein the drive coil is arranged in a substantially circular or rectangular shape.

16. The apparatus of claim 10, wherein the shield plate comprises a bent portion extending along the periphery of the shield plate.

17. The apparatus of claim 10, wherein the reluctance associated with the first and second directions differ by a factor of 5:

1 or greater.

18. The apparatus of claim 10, wherein the electrical resistance associated with the first and second directions differ by a factor of 5:

1 or greater.