US 12,451,718 B2
Wearable computing device having a charging system for a rechargeable battery
Piyush Tulsidas Itankar, Bangalore (IN); Shantanu Goel, Bangalore (IN); Dheeraj Kumar Agrawal, Jaipur (IN); and Mahmad Saifuddin Bharmal, Rajkot (IN)
Assigned to GOOGLE LLC, Mountain View, CA (US)
Filed by Google LLC, Mountain View, CA (US)
Filed on Dec. 21, 2021, as Appl. No. 17/557,823.
Prior Publication US 2023/0198284 A1, Jun. 22, 2023
Int. Cl. H02J 7/14 (2006.01); G06F 1/16 (2006.01); G06F 3/0488 (2022.01); H02J 7/34 (2006.01)
CPC H02J 7/14 (2013.01) [G06F 1/163 (2013.01); H02J 7/345 (2013.01); G06F 3/0488 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A wearable computing device comprising:
a housing defining a cavity;
a rechargeable battery disposed within the cavity; and
a charging system disposed within the cavity, the charging system comprising:
an alternating current generator configured to generate alternating current power, the alternating current generator comprising a stator and a rotor, the stator comprising a plurality of poles arranged in an annular configuration about an interior circumferential portion of the housing, the rotor rotatable relative to the stator due to motion of a user wearing the wearable computing device;
a rectifier circuit electrically coupled to the stator of the alternating current generator, the rectifier circuit configured to convert the alternating current power to direct current power;
an energy storage device electrically coupled to the rectifier circuit such that the energy storage device is charged with the direct current power; and
a solid state switch coupled between the energy storage device and the rechargeable battery, the solid state switch configured to selectively couple the energy storage device to the rechargeable battery to transfer charge from the energy storage device to the rechargeable battery, wherein
each of the plurality of poles include a coil which is wrapped around a corresponding pole among the plurality of poles,
the rotor includes an arm configured to rotate about a center of the housing, and a magnet that is disposed at a distal end of the arm and which is spaced apart from the plurality of poles in a radial direction of the arm, the radial direction extending from the center of the housing toward the distal end of the arm, and
when a voltage across the energy storage device is less than a rated voltage of the rechargeable battery, the solid state switch is configured in a first state such that the energy storage device is decoupled from the rechargeable battery.