Du Li

US Patent:

20140176060, Jun 26, 2014

Filed:

Jul 2, 2013

Appl. No.:

13/934165

Inventors:

- Westlake Village CA, US
Leon ALKALAI - Studio City CA, US
Donald HUNTER - La Verne CA, US
Du LI - Oak Park CA, US
Noam LOTAN - Westlake Village CA, US

International Classification:

H02J 7/02
H02J 7/00

US Classification:

320108, 320137

Abstract:

In some embodiments, the charging magnetic field produced in an air gap within an inductive charger for a hearing aid or other miniature device is shaped by lateral protrusions, which draw the magnetic field away from a body of a device battery situated behind a receiver inductor. Shaping the magnetic field allows reducing the magnetic field flux intercepted by the battery (rater than the receiver inductor), reducing the inductive heating of the battery. A charging element produces a high-frequency, 120 kHz, magnetic field inside the gap in which the hearing aid or other device is inserted to charge its battery. A loosely-coupled magnetic transformer circuit forms a resonant tank circuit that is excited, by a feedback control circuit, at its resonant frequency to ensure power transfer across the large gap regardless of the dimensional variations of the gap and the relative position of the hearing aid in the gap.