Electromagnetic-Mechanical Analysis of a Balanced Armature Receiver by Considering the Nonlinear Parameters as the Function of Displacement and Current

Balanced armature receiver is widely used in hearing aid and earphone because of the small size and high sensitivity. Balanced armature receiver is a product which covers multi-physics. It contains the electromagnetic, mechanical domain and the property such as current and displacement can affect each other. In one hand, the current in electromagnetic domain will take effect on the force which determines the displacement in mechanical domain. In the other hand, displacement change can contribute to the change of back electromotive force (EMF) which affects the current. So the current and displacement are coupled and need to be considered at the same time to analyze the balanced armature receiver. In terms of equation, current and displacement are coupled in the voltage equation which involves the nonlinear parameters such as inductance, speedance, and force factor. Based on lumped parameter method, the nonlinear parameters were calculated as functions of displacement in balanced armature speaker [1]. By using finite element method, Lee et al. analyzed the nonlinear parameters as the function of displacement in microspeaker [2]. In this study, the displacement and current are both considered in the nonlinear parameters to analyze the performance of balanced armature receiver by using FEM.