Portable battery pack for wirelessly charging body-worn devices through clothing
A portable battery pack is disclosed for wirelessly powering a portable electronic device through a user's clothing. The portable battery pack includes a housing with a mating surface that includes one or more permanent magnets to facilitate mating with a portable electronic device, such as a body-worn camera.
1. A wireless power transfer system, comprising:
a portable battery pack including:
a first housing having a first mating surface;
a first permanent magnet disposed on the first mating surface for coupling with a second permanent magnet on a portable electronic device;
first battery cells secured within the first housing;
a first printed circuit board (PCB) secured within the first housing, the first PCB including:
a power amplifier coupled to the first battery cells;
a rectifier and battery charger coupled to the first battery cells;
a connector with metal contacts coupled to the rectifier and battery charger, the connector configured for connecting to an input power source; and
a transmitter coil coupled to the power amplifier through transmitter resonant capacitors;
a portable electronic device including:
a second housing having a second mating surface;
the permanent magnet disposed on the second mating surface for coupling with the first permanent magnet disposed on the first mating surface of the portable battery pack;
a second battery included in the second housing; and
a receiver coil included in the second housing and coupled to the second battery, wherein the first mating surface and the second mating surface have the same dimensions, such that there is no overhanging portions of the first housing or the second housing when the portable battery pack and the portable electronic device are joined in a mated configuration by the first and second permanent magnets.
2. The wireless power transfer system of claim 1 , further comprising:
a second PCB included in the second housing; and
a camera attached to the second PCB, the camera having a lens aligned with an opening in the second housing.
3. The wireless power transfer system of claim 1 , wherein the transmitter coil is constructed using spiral wound traces on the first PCB, and a shield of ferrite material is used behind the first PCB to shape a magnetic field emitted by the transmitter coil.
4. The wireless power transfer system of claim 1 , wherein at least one of the portable battery pack or the portable electronic device provides haptic feedback indicating successful mating or connection to the input power source.
5. The wireless power transfer system of claim 4 , wherein the haptic feedback is provided by a linear actuator.
6. The wireless power transfer system of claim 1 , wherein in the mated configuration, the transmitter coil of the portable battery pack is excited by the power amplifier of the portable battery pack, causing a quasi-static magnetic field coupled to the receiver coil of the portable electronic device to form a loosely-coupled transformer.