The Magnetic Characteristics Analysis Of Miniature Loudspeaker

Miniature loudspeaker is mostly used in portable electronic products like mobile phones,it mainly includes vibration system,magnetic circuit system and support system.In this paper,the rectangle miniature loudspeaker which frequently used in the current market is focused on the study object.Base on the theory of magnetic circuit design in the modern electroacoustics,the practical research on the magnetic circuit system of the loudspeaker is launched in this paper.First,designing and modeling the magnetic circuit system,second,using two different kinds of finite element analysis software to analysis it,finally comparing the results.A kind of optimization analysis method about nonaxisymmetry structure miniature loudspeaker's magnetic circuit system and the calculating method of electric to force conversion coefficient(BL)are summarized,which provide the theoretical reference and design basis for the design of miniature loudspeaker system.On the basis of the miniature dynamic systems,the form of sound waves in acoustic theory and the application of electromagnetic theory are studied.Furthermore,both the operation principle of traditional loudspeaker system,the structure and classification of loudspeaker are illustrated.The magnetic circuit structure and operation principle of miniature loudspeaker are emphasized.The vibration system which contains a voice coil and diaphragm,the magnetic circuit system which consist of U magnet,magnet and the magnet core,as well as the support system is analyzed.Secondly,in this paper using finite element analysis method to simulate the magnetic circuit system of rectangle miniature loudspeaker is a major concern.Based on the magnetic circuit design theory,combining the 3D modeling softwareSolidWorks,each part of the magnetic circuit is designed and modeled,then assemble them into a whole.Involving three procedure,first,using the finite element analysis software ANSYS Workbench to analysis the model and observe the electromagnetic characteristics of the magnetic circuit system,second,using COMSOL Multiphysics to analysis the same model,finally comparing the magnetic parameters results with the result of ANSYS Workbench.The aforementioned procedure provides the theoretical reference for the method of finite element analysis of rectangle miniature loudspeaker's magnetic circuit system.Finally,the magnetic flux distribution in the rectangle miniature loudspeaker was simulated by finite element analysis.Analyze the magnetic flux density of air gap which constitute by U magnet and magnetic core.Extract the effective magnetic flux density on the coil which only acting the electromagnetic force.Analyze and summarize the magnetic flux density on each part of the voice coil which is the nonaxisymmetric.The calculating method and the displacement curve of BL,which is called electric to force conversion coefficient are summarized.Due to the complexity of analogy simulation about miniature loudspeakers products,only the rectangle loudspeaker is involved in the analysis method in the paper.