SPEAKER, IN WHICH POLE PIECE IS NOT USED

摘要

PURPOSE: A speaker is provided to obtain the clear sound by reducing the deformation of the driving force. CONSTITUTION: A permanent magnet unit(11) is formed by arranging four small permanent magnets in a shape of a ring. A cylindrical voice coil(12) is arranged at a position apart from an inner surface of the permanent magnet unit in order to form the solenoid magnetic field according to the voice current. A cylindrical bobbin(14) is used for supporting the cylindrical voice coil. A vibration plate(15) is adhered to the cylindrical bobbin in order to convert an electric voice signal to sound by vibrating air according to the vibration of the cylindrical bobbin. A thin film(13) is used for covering all sides of the voice coil.