Shaped Coil for Wireless Power Transmission System Coupling

Abstract

A wireless power transfer system includes an antenna base having a charger surface configured substantially as a concave spherical section and a first antenna comprising a spiral wire coil conforming to the charger surface of the antenna base. A target item includes an interface surface configured as a convex spherical section substantially matching the concave spherical section of the charger base. A second antenna is located within the target item and adjacent to the interface surface such that when the target item is placed in the antenna base with the interface surface mated to the charger surface, the first and second antennas are within inductive coupling range for wireless power transfer between the antennas.

1 . A wireless power transfer system comprising:
 a base comprising a charger surface having a spherical section that is substantially concave;   a first antenna comprising a spiral wire coil, wherein the first antenna conforms to the spherical section of the charger surface, wherein the spherical section of the charger surface defines a base axis that is substantially a center point of the spherical section of the charger surface and the first antenna;   a target comprising:
 a target surface having a spherical section that is substantially convex such that the spherical section of the target surface substantially matches the spherical section of charger surface; and 
 a second antenna within the target and adjacent to the spherical section of the target surface, wherein a target axis substantially passes through a center point of the second antenna and is substantially perpendicular to the spherical section of the target surface, wherein when the spherical section of the target surface is mated to the spherical section of the charger surface, the first antenna is within inductive coupling range of the second antenna for wireless power transfer, 
 wherein a coupling strength between the first antenna and the second antenna is substantially constant when the target is in a first configuration and a second configuration, wherein the first configuration comprises the target axis aligned with the base axis, and wherein the second configuration comprises an angular offset between the target axis and the base axis such that the second antenna is positioned within an outermost turn of the first antenna and the base axis falls outside an outermost turn of the second antenna. 
   
     
     
         2 . The wireless power transfer system in accordance with  claim 1 , wherein the target is substantially spherical. 
     
     
         3 . The wireless power transfer system in accordance with  claim 1 , wherein the target is a ball. 
     
     
         4 . The wireless power transfer system in accordance with  claim 1 , wherein the charger surface defines a recessed spiral track configured to retain the spiral wire coil. 
     
     
         5 . The wireless power transfer system in accordance with  claim 4 , wherein the recessed spiral track includes an inner face and an outer face, and wherein the inner face is undercut to retain the spiral wire coil. 
     
     
         6 . The wireless power transfer system in accordance with  claim 4 , wherein the recessed spiral track includes an inner face and an outer face, and a plurality of tabs protruding outward over the recessed spiral track from the inner face to retain the spiral wire coil. 
     
     
         7 . The wireless power transfer system in accordance with  claim 1 , wherein the second antenna comprises a substantially cylindrical coil. 
     
     
         8 . The wireless power transfer system in accordance with  claim 1 , wherein the second antenna comprises a substantially flat coil. 
     
     
         9 . The wireless power transfer system in accordance with  claim 1 , further comprising an electrical circuit within the target, linked to the second antenna, wherein the electrical circuit includes a battery charged by power received at the second antenna from the first antenna. 
     
     
         10 . The wireless power transfer system in accordance with  claim 9 , wherein the electrical circuit is configured to sense and record motion of the target. 
     
     
         11 . The wireless power transfer system in accordance with  claim 9 , wherein the electrical circuit is configured to communicate with the first antenna via the second antenna when the second antenna is within inductive coupling range of the first antenna. 
     
     
         12 . The wireless power transfer system in accordance with  claim 11 , wherein the electrical circuit is configured to employ amplitude shift keying (ASK) data signals to communicate with the first antenna via the second antenna. 
     
     
         13 . The wireless power transfer system in accordance with  claim 12 , wherein the electrical circuit is configured to transmit the ASK data signals over a base operating frequency of about 6.78 MHz. 
     
     
         14 . A wireless power transfer system comprising:
 a base comprising a charger surface having a spherical section that is substantially concave, the spherical section of the charger surface configured to mate with a target comprising a target surface having a spherical section that is substantially convex and substantially matches the spherical section of the charger surface;   a first antenna comprising a spiral wire coil, wherein the first antenna conforms to the spherical section of the charger surface, wherein the spherical section of the charger surface defines a base axis that is substantially a center point of the first antenna and the spherical section of the charger surface;   a second antenna within the target and adjacent to the target surface, wherein a target axis substantially passes through a center point of the second antenna and is substantially perpendicular to the spherical section of the target surface, wherein when the spherical section of the target surface is mated to spherical section of the charger surface, the first antenna is within inductive coupling range of the second antenna for wireless power transfer, wherein a coupling strength between the first antenna and the second antenna is substantially constant when the target is in a first configuration and a second configuration, wherein the first configuration comprises the target axis aligned with the base axis, and wherein the second configuration comprises an angular offset between the target axis and the base axis such that the second antenna is positioned within an outermost turn of the first antenna and the base axis falls outside an outermost turn of the second antenna; and   a transmitter controller configured to transmit, at the charger surface via the first antenna, alternating current wireless signals including wireless power signals and wireless data signals.   
     
     
         15 . The wireless power transfer system in accordance with  claim 14 , wherein the charger surface defines a recessed spiral track configured to retain the spiral wire coil. 
     
     
         16 . The wireless power transfer system in accordance with  claim 15 , wherein the recessed spiral track includes an inner face and an outer face, and wherein the inner face is undercut to retain the spiral wire coil. 
     
     
         17 . The wireless power transfer system in accordance with  claim 15 , wherein the recessed spiral track includes an inner face and an outer face, and a plurality of tabs protruding outward over the spiral track from the inner face to retain the spiral wire coil. 
     
     
         18 . A wireless power transfer system comprising:
 a base comprising a charger surface having a first non-planar shape section;   a first antenna comprising a spiral wire coil, wherein the first antenna conforms to the first non-planar shape section of the charger surface, wherein the first non-planar shape section defines a base axis that is substantially a center point of the first non-planar shape section and the first antenna;   a target comprising a target surface having a second non-planar shape section, the second non-planar shape section substantially matching the first non-planar shape section; and   a second antenna within the target and adjacent to the second non-planar shape section, wherein a target axis substantially passes through a center point of the second antenna and is substantially perpendicular to the second non-planar shape section, wherein when the second non-planar shape section is mated to the first non-planar shape section, the first antenna is within inductive coupling range of the second antenna for wireless power transfer, wherein a coupling strength between the first antenna and the second antenna is substantially constant when the target is in a first configuration and a second configuration, wherein the first configuration comprises the target axis aligned with the base axis, and wherein the second configuration comprises an angular offset between the target axis and the base axis such that the second antenna is positioned within an outermost turn of the first antenna and the base axis falls outside an outermost turn of the second antenna.   
     
     
         19 . The wireless power transfer system in accordance with  claim 18 , further comprising a first electrical circuit associated with the first antenna and a second electrical circuit associated with the second antenna wherein the first and second electrical circuits are configured to provide wireless power transfer between the first antenna and the second antenna via an inducing signal. 
     
     
         20 . The wireless power transfer system in accordance with  claim 19 , wherein the first and second electrical circuits are configured to exchange data via the inducing signal by superimposing perturbations on the inducing signal.