Wireless Charging System With Solenoids

Abstract

A wireless power transmitting device may transmit wireless power signals to a wireless power receiving device. The wireless power receiving device may have a housing. A display may be mounted in the housing on a front face of the device. A rear housing wall on a rear face of the device may be provided with a wireless power receiving solenoid. The solenoid may have a linear strip shape that extends along a longitudinal axis. The longitudinal axis may extend perpendicularly to a wrist strap coupled to the housing. The wireless power receiving solenoid may have opposing first and second ends. The wireless power transmitting device may have a wireless power transmitting solenoid with opposing first and second ends that are configured to transmit the wireless power signals respectively to the first and second ends of the wireless power receiving device when the wireless power receiving solenoid is within the cradle.

What is claimed is: 
     
         1 . A wireless power receiving device having opposing front and rear faces, wherein the wireless power receiving device is configured to receive wireless power signals from a wireless power transmitting device, the wireless power receiving device comprising:
 a housing having a rear housing wall at the rear face;   a display mounted in the housing at the front face; and   a solenoid that extends across at least part of the rear face and that is configured to receive the wireless power signals.   
     
     
         2 . The wireless power receiving device defined in  claim 1  wherein the solenoid comprises a linear solenoid having a core of magnetic material wrapped with a conductive wire, wherein the solenoid has opposing ends, wherein the solenoid extends across at least part of the rear housing wall, and wherein the rear housing wall has recessed portions at the ends. 
     
     
         3 . The wireless power receiving device defined in  claim 2  wherein the conductive wire comprises a conductive wire selected from the group consisting of: a metal strand with a dielectric coating, a metal strand with a magnetic coating, a metal strand with a rectangular cross-sectional shape, and a conductive wire formed from multiple intertwined metal strands. 
     
     
         4 . The wireless power receiving device defined in  claim 3  wherein the core has a relative permeability of at least 1000 at 300 to 400 kHz. 
     
     
         5 . The wireless power receiving device defined in  claim 4  wherein the housing is a metal housing and wherein the wireless power receiving device further comprises a wrist strap coupled to the metal housing. 
     
     
         6 . The wireless power receiving device defined in  claim 5  wherein the metal housing has sidewalls coupled to the rear housing wall, wherein the wrist strap is coupled to the sidewalls, and wherein the solenoid extends parallel to the sidewalls to which the wrist strap is coupled and perpendicular to the wrist strap. 
     
     
         7 . The wireless power receiving device defined in  claim 6  wherein the core extends along a longitudinal axis, wherein the core has a length along the longitudinal axis, a thickness extending away from the rear housing wall, and a width that runs parallel to the rear housing wall, wherein the length is 1-5 cm, wherein the width is 0.3 to 1.2 cm, and wherein the thickness is 0.05-0.2 cm. 
     
     
         8 . The wireless power receiving device defined in  claim 1  wherein the rear housing wall is planar and wherein the solenoid has a portion that curves within a plane parallel to the rear housing wall. 
     
     
         9 . A wireless power transmitting device configured to transmit wireless power signals to a wireless power receiving device that has a wireless power receiving solenoid with opposing first and second ends, the wireless power transmitting device comprising:
 a support structure that is configured to receive the power receiving solenoid;   a wireless power transmitting solenoid that has opposing first and second ends; and   wireless power transmitting circuitry coupled to the wireless power transmitter solenoid, wherein the wireless power transmitting circuitry is configured to transmit the wireless power signals to the wireless power receiving device with the wireless power transmitting solenoid when the first and second ends of the wireless power transmitting solenoid are respectively adjacent to the opposing first and second ends of the wireless power receiving solenoid.   
     
     
         10 . The wireless power transmitting device defined in  claim 9  wherein the support structure forms a cradle having a recessed portion that receives the power receiving solenoid. 
     
     
         11 . The wireless power transmitting device defined in  claim 10  further comprising a shield layer under the cradle. 
     
     
         12 . The wireless power transmitting device defined in  claim 11  wherein the shield layer comprises a copper plate. 
     
     
         13 . The wireless power transmitting device defined in  claim 10  further comprising magnets that are configured to attract the wireless power transmitting device. 
     
     
         14 . The wireless power transmitting device defined in  claim 9  wherein the wireless power transmitting device comprises a U-shaped core of magnetic material wrapped with wire. 
     
     
         15 . The wireless power transmitting device defined in  claim 9  wherein the wireless power transmitting device comprises a C-shaped core of magnetic material wrapped with wire. 
     
     
         16 . A wireless power receiving device that has opposing front and rear faces and that is configured to receive wireless power signals from a wireless power transmitting device, the wireless power receiving device comprising:
 a housing having a metal rear housing wall at the rear face;   a display at the front face that is mounted in the housing;   a wrist strap coupled to the housing; and   a solenoid supported by the metal rear housing wall that is configured to receive the wireless power signals.   
     
     
         17 . The wireless power receiving device defined in  claim 16  wherein the solenoid comprises a strip-shaped core wrapped with wire and wherein the strip-shaped core extends perpendicularly to the wrist strap. 
     
     
         18 . The wireless power receiving device defined in  claim 17  wherein the metal rear housing wall has an external surface, wherein the solenoid has an inner surface facing the external surface, and wherein the inner surface is separated from the external surface by a gap that is filled with dielectric. 
     
     
         19 . The wireless power receiving device defined in  claim 17  wherein the metal rear housing wall has an external surface, wherein the solenoid has an inner surface facing the external surface, and wherein the inner surface is flush with the external surface. 
     
     
         20 . The wireless power receiving device defined in  claim 19  wherein the metal rear housing wall has an external surface and wherein the solenoid has an inner surface that lies flush with a recessed portion of the external surface.