Novel magnets configuration toward a high performance electrodynamic micro-electro-mechanical-systems microspeaker

This paper presents a study of different configurations of permanent magnets' to maximize microspeakers' electroacoustic performances. The proposed theoretical approach is based on an analytical model allowing the calculation of the magnetic field created by cylindrical and ring-shaped permanent magnet, making thus possible to analyze different magnetic structures. Several combinations of cylindrical and rings were analyzed in view of maximizing the magnetic field in the vicinity of the voice coil. Taking into account the whole electro-mechano-acoustic behavior of the microspeaker, we present two optimized magnets configurations which increase the efficiency by factors between 2.7 and 5 comparing to previously optimized microspeakers. Moreover, we show that it is possible to get devices twice smaller with efficiencies increased by factors between 1.2 and 3.4.