Micro Electromagnetic Flat Motor Using an 80-Poles and 0.3-mm-Thick Ring Magnet for High Torque

This paper presents a micro electromagnetic flat motor with high torque for cameras in mobile applications. As far as we know, this is the first micro motor to feature both a thin profile less than 1 mm and a high diving torque more than 20 μNm. As the critical component, the 0.3-mm-thick ring permanent magnet plate possesses the highest pole number of 80 reported to date and a pole pitch of 0.3 mm. The ultra multipole and fine pitch magnetization is realized by a combination of laser heating and external magnetic field. Compared with single-sided laser heating, the double-sided one helps assure the sufficient heating on both sides of magnet surfaces and improves the magnetization from 53.6% to 75.9% of the design value. The magnetization performance and rotation results validate the proposed micro flat motor.