Recent use of mobile phones as a multimedia device has increased the development of micro-speaker modules having high quality and a compact size. Micro-speakers use polymer diaphragms fabricated by the thermoforming process. To improve the sound quality, micro-speaker diaphragms are usually designed to contain a number of micro-corrugations. This study investigated the effects of the corrugation depth on the acoustic characteristics of the diaphragm, using finite element (FE) analysis. Structural FE analysis was performed to investigate the stiffness change according to the corrugation depth. Modal FE analysis was used to compare the change in natural frequencies for each case. Harmonic response analysis further investigated the resulting variation in acoustic power. The effects of the corrugation depth on the acoustic characteristics of the diaphragm were discussed by reviewing all the FE analysis results synthetically.

Micro-speaker diaphragms play an important role in generating a desired audio response. The diaphragm is generally a circular membrane, and the cross section is a double dome, with an inner dome and an outer dome. To improve the sound quality of the speaker, a number of corrugations may be included in the outer dome region. In this study, the role of these corrugations is investigated using two kinds of finite element method (FEM) calculations. Structural FEM modeling was carried out to investigate the change in stiffness of the diaphragm when the corrugations were included. Modal FEM modeling was then carried out to compare the natural frequencies and the resulting vibrational modes of the plain and corrugated diaphragms. The effects of the corrugations on the vibration characteristics of the diaphragm are discussed.