FOCUSING DEVICE FOR LOW FREQUENCY OPERATION

• US 20130003245A1
• Filed: 06/29/2011
• Published: 01/03/2013
• Est. Priority Date: 06/29/2011
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Motor Engineering & Manufacturing North America Incorporated (Toyota Motor Corporation)
• Inventors: Banerjee, Debasish, Iizuka, Hideo, Lee, Jaewook, Dede, Ercan Mehmet
• Granted Patent: US 8,797,702 B2
• Time in Patent Office: Days
• US Class Current: 361/143
• CPC Class Codes: G01R 33/38 Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
• CPC Class Codes: G02B 1/002 made of materials engineered to provide properties not available in nature, e.g. metamaterials
• CPC Class Codes: G02B 3/08 with discontinuous faces, e.g. Fresnel lens diffractive Fresnel lenses G02B5/1876
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles

Abstract

An example apparatus for obtaining a desired magnetic field distribution from an incident magnetic field, such as a kHz magnetic field, comprises a structure receiving the incident magnetic field and generating the desired magnetic field distribution at a predetermined distance from the transmitting side of the apparatus. The desired magnetic field distribution results from a spatial distribution of induced electrical current over the structure. Examples of the invention also include design methods and methods of using the apparatus.

Claims

1. A method of modifying an incident magnetic field to obtain a magnetic field distribution, the method comprising:

providing a focusing device having a first side and a second side;

directing the incident magnetic field towards the first side,

the incident magnetic field generating an induced electrical current profile within the focusing device; and

obtaining a transmitted magnetic field from the second side, the transmitted magnetic field providing the magnetic field distribution,

the transmitted magnetic field being generated by the induced electrical current profile within the focusing device,

the incident magnetic field having a frequency in the range 1 Hz-30 MHz.

2. The method of claim 1, the focusing device including a patterned electrical conductor, the spatial distribution of the induced electrical current profile being determined by the patterned electrical conductor.

3. The method of claim 2, the patterned electrical conductor having an array of apertures formed therethrough.

4. The method of claim 1, the patterned electrical conductor including a pair of ladder-shaped conducting structures arranged end-to-end along a common long axis and separated by a gap therebetween.

5. The method of claim 1, the incident magnetic field being incident normally or near-normally on the first side.

6. The method of claim 1, the magnetic field profile being a focused incident magnetic field obtained within the near field region of the focusing device.

7. The method of claim 1, the focusing device being a generally planar structure or a curved sheet-like structure.

8. An apparatus, the apparatus being a focusing device configured to obtain a magnetic field distribution from an incident magnetic field,

the focusing device having a first side and a second side, and including a plurality of conductive loops, a transmitted magnetic field emerging from the second side when the incident magnetic field is incident on the first side,

the incident magnetic field inducing an electric current profile within the focusing device, the electric current profile inducing the transmitted magnetic field and having an induced current density,

the magnetic field distribution being obtained using the transmitted magnetic field,

the focusing device having a spatial profile of real values of a ratio of the transmitted magnetic field to a curl of the induced current density,

the focusing device being configured for an incident magnetic field frequency in the range 1 Hz-30 MHz.

9. The apparatus of claim 8, the focusing device including:

a dielectric substrate; and

a patterned electrical conductor supported by the dielectric substrate, the patterned electrical conductor providing the plurality of conductive loops.

10. The apparatus of claim 8, the patterned electrical conductor including a conducting film having an array of apertures formed therethrough.

11. The apparatus of claim 8, the patterned electrical conductor including a ladder-shaped conducting element.

12. The apparatus of claim 11, the patterned electrical conductor including a pair of ladder-shaped conducting elements arranged end-to-end and separated by a gap region.

13. The apparatus of claim 8, the magnetic field distribution being a focused magnetic field.

14. The apparatus of claim 8, the focusing device having a planar form, the focusing device including a planar dielectric substrate supporting a conducting sheet,

the conducting sheet having an array of apertures formed therethrough.

15. The apparatus of claim 8, the focusing device having a curved sheet-like form.

16. A magnetic apparatus including the focusing device of claim 8, the magnetic apparatus being a motor, an actuator, or a power inverter.

17. The magnetic apparatus of claim 16, the magnetic apparatus including a pole piece, the focusing device being supported by the pole piece.

18. The apparatus of claim 16, the magnetic apparatus being a switched reluctance motor.

19. An apparatus, the apparatus being a focusing device configured to obtain a magnetic field distribution from an incident magnetic field,

the focusing device including a substrate supporting a patterned electrical conductor, the patterned electrical conductor providing a plurality of conductive loops,

the focusing device having a first side and a second side, a transmitted magnetic field emerging from the second side when the incident magnetic field is incident on the first side,

the incident magnetic field inducing an electric current profile within the patterned electrical conductor, the electric current profile inducing the transmitted magnetic field,

the magnetic field distribution being obtained using the transmitted magnetic field,

the focusing device being operable for an incident magnetic field frequency in the range 1 kHz-30 MHz.

20. The apparatus of claim 19, the patterned electrical conductor including a conducting sheet having an array of apertures formed therethrough.

21. The apparatus of claim 20, the patterned electrical conductor including a ladder-shaped conducting element having a linear array of slot-like apertures.