ALEXANDRIA, Va., Sept. 3 -- United States Patent no. 12,407,976, issued on Sept. 2, was assigned to AAC Microtech (Changzhou) Co. Ltd. (Changzhou, China).
"Coaxial earphone core" was invented by Zhang Ren (Changzhou, China) and Zhiwei Zhong (Changzhou, China).
According to the abstract* released by the U.S. Patent & Trademark Office: "The present disclosure discloses a coaxial earphone core including a magnet system, which includes a first yoke, a first magnet, a second magnet surrounding the first magnet to form a first magnetic gap, a second yoke fixed to the first magnet, and an annular third magnet fixed to the second yoke; the second yoke includes an extending wall bending and extending into the third magnet; the extending wall is sp...