Systems and methods for wirelessly projecting power using in-phase current loops

• US 6,388,628 B1
• Filed: 05/14/1999
• Issued: 05/14/2002
• Est. Priority Date: 05/18/1998
• Status: Expired due to Fees

• Current Assignee: DB Tag Incorporated
• Original Assignee: DB Tag Incorporated
• Inventors: Batchelor, William E., Heaton, Robert A., Steer, Michael B., Dettloff, Wayne D.
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US09/312,577
• Time in Patent Office: 1,096 Days
• Field of Search: H01/Q 1.112, 343/742, 343/741, 343/866, 343/867, 343/895
• US Class Current: 343/742
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

An array of in-phase current loops are disposed adjacent to one another to define a surface and to define a virtual current loop at a periphery of the surface that produces a same direction virtual current while current in adjacent portions of adjacent current loops flows in opposite directions, to thereby wirelessly project power from the surface. It has been found according to the invention that the array of in-phase current loops that are disposed adjacent to one another to define a surface and to define a virtual current loop at a periphery of the surface that produces a same direction virtual current while current in adjacent portions of adjacent current loops flows in opposite directions, can provide acceptable power to RFID tags, while reducing the risk of violating regulatory constraints. A plurality of arrays of in-phase current loops also may be provided. The multiple arrays of in-phase current loops are disposed adjacent to one another to define a surface. Each array of in-phase current loops may be configured as was described above. N-ary tree traversals, push and pop commands and/or warp commands also may be used to efficiently identify tags.

Claims

1. A system for wirelessly projecting power to wirelessly power microelectronic devices, the system comprising:

an array of current loops that are disposed adjacent to one another to define a surface and to define an in-phase virtual current loop at a periphery of the surface that produces a same direction, in-phase virtual current while current in adjacent portions of adjacent current loops flows in opposite directions, to wirelessly project power orthogonal to the surface to power microelectronic devices that are spaced apart from, and orthogonal to, the surface;

wherein the array of current loops comprises an array of at least ten wedge-shaped current loops each having an outer portion and a pair of sides. the at least ten wedge-shaped current loops being disposed adjacent to one another to define a surface such that currents in the outer portions are in-phase and current in adjacent sides of adjacent current loops are out-of-phase.

2. A system for wirelessly projecting power to wirelessly power microelectronic devices, the system comprising:

a plurality of arrays of current loops, the arrays of current loops being disposed adjacent to one another to define a surface, each array of current loops defining an in-phase virtual current such that in-phase virtual currents of at least some adjacent arrays of current loops are not in-phase with one another, each array of current loops comprising a plurality of current loops that are disposed adjacent to one another in the surface, such that current in adjacent portions of adjacent current loops in an array flows in opposite directions, to wirelessly project power orthogonal to the surface to power microelectronic devices that are spaced apart from, and orthogonal to, the surface.

3. A system according to claim 2 wherein the virtual currents of adjacent arrays of current loops are of opposite phase from one another.

4. A system according to claim 2 wherein the plurality of arrays of current loops comprises four arrays of current loops that are arranged in two rows and two columns, such that the virtual currents in the arrays in each row and each column are of opposite phase.

5. A system according to claim 2 wherein the plurality of arrays of current loops comprises four arrays of current loops that are arranged in two rows and two columns, such that the virtual currents in the arrays in each row and each column are ninety degrees out-of-phase from one another.

6. A system according to claim 4 wherein the two rows and two columns are two oblique rows and two oblique columns.

7. A system according to claim 5 wherein the two rows and two columns are two oblique rows and two oblique columns.

8. A system according to claim 2 wherein the plurality of arrays of current loops comprises a plurality of arrays of current loops that are arranged in a circle, such that the virtual currents in adjacent arrays in the circle are of opposite phase.

9. A system according to claim 2 wherein each array of loops is arranged to provide at least some reinforcement of an electromagnetic near field that is produced by the current loops orthogonal to the surface in an array while producing at least some cancellation of a far field electromagnetic wave orthogonal to the surface that is produced by the current loops in the array.

10. A system according to claim 9 wherein the plurality of arrays of current loops arc arranged provide at least some further reinforcement of the electromagnetic near fields that are produced by the arrays of current loops orthogonal to the surface and at least some further cancellation of the far field electromagnetic waves orthogonal to the surface that are produced by the arrays of in-phase current loops.

11. A system according to claim 2 wherein each array of current loops comprises an array of at least ten wedge-shaped current loops, each having an outer portion and a pair of sides, the at least ten wedge-shaped current loops being disposed adjacent to one another to define a surface such that currents in the outer portions are in-phase and current in adjacent sides of adjacent current loops are out-of-phase.

12. A system according to claim 2 wherein each array of current loops comprises an array of at least ten polygonal current loops, each having a plurality of sides, the at least ten polygonal current loops being disposed adjacent to one another to define a surface having an outer boundary, such that currents in the sides of the at least ten polygonal loops that are adjacent the outer boundary are in-phase and current in adjacent sides of adjacent current loops are out-of-phase.

13. A system according to claim 2 wherein each array of current loops comprises an array of spiral current loops.

14. A system according to claim 2 wherein each of the current loops is less than a quarter wavelength long.

15. A system according to claim 2 wherein each array of current loops comprises an array of concentric current loops.

16. A system according to claim 2 wherein each array of current loops comprises an array of stacked current loops.

17. A system according to claim 2 further comprising a driver that drives each array of current loops at 13.56 MHz to thereby wirelessly project power.

18. A method for wirelessly projecting power to wirelessly power microelectronic devices, the method comprising the step of:

applying current to a plurality of arrays of current loops, the arrays of current loops being disposed adjacent to one another to define a surface, each array of current loops defining an in-phase virtual current such that in-phase virtual currents of at least some adjacent arrays of current loops are out-of-phase with one another, each array of current loops comprising a plurality of current loops that are disposed adjacent to one another in the surface, such that current in adjacent portions of adjacent current loops in an array flows in opposite directions, to wirelessly project power orthogonal to the surface to power microelectronic devices that are spaced apart from, and orthogonal to, the surface.