Circular Holes Punched in a Magnetic Circuit used in Microspeakers to Reduce Flux Leakage

Abstract

Lower flux leakage designs have become important in the development of microspeakers used in thin and miniaturized mobile phones. We propose four methods to reduce the flux leakage of the magnetic circuit in a microspeaker. Optimization was performed based on the proposed approach by using the response surface method. Electromagnetic analyses were conducted using the finite element method. Experimental results are in good agreement with the simulated results obtained in one degree-of-freedom analysis from 100 to 5 kHz. Both the simulated and experimental results confirm that one of the proposed methods is much more effective in reducing flux leakage than the other methods. In the optimized method, compared with a default approach, the average radial flux density in the air gap decreased only by 5.5 %, the maximum flux leakage was reduced by 28.6 %, and the acoustic performance at primary resonance decreased by 0.45 dB, which gap is indiscernible to the human ear.

Analysis and Design of a New Linear Vibration Motor Used to Reduce Magnetic Flux Leakage in In-Vehicle Infotainment

“…The force factor and the magnetic flux leakage decreased as the hole diameter increased. Xu et al [13] presented a new way to reduce the magnetic flux leakage on the microspeaker by punching circular holes into a magnetic circuit. In their study, there were holes punched in the inner plate and inner magnet, which were the main parts of the microspeaker's magnetic circuit.…”