Improvement Efficiency and Miniaturization of Bone Conduction Speaker

抄録

　This paper presents a new structure of bone conduction speaker. It is smaller than the conventional structure by removing an extra space. The magnetic path of this structure is not wasteful because the coil case is attached a cover and this structure uses the magnetic material as the vibrating plate. This structure operates by flowing the audio current into the voice coil. That reason is the change of magnetic attractive force between the magnetic pole of yoke and magnet. The authors revealed various characteristics of this structure by the electromagnetic field analysis and structural analysis by using the 3-dimensional finite element method (3D-FEM). As the result of electromagnetic analysis, the leakage flux of this structure is lower than the conventional structure by 55.2 %. As the result of structural analysis, the sound pressure level (SPL) of this structure is higher than the conventional structure by 12.6 %. Consequently, the performance of this structure is improved.