DIAPHRAGM USING POLYMER COMPOSITE FILM FOR LOUDSPEAKERS.

Acoustic characteristics of loudspeakers largely depend on the physical properties of diaphragm materials. Composite films made of thermoplastics and inorganic fillers with a flaky shape have been developed. These films have been found to be excellent diaphragm materials in terms of physical properties, acoustic characteristics and reliability. Polyarylate film containing mica, which has been developed as the diaphragm material for microspeakers, can be accurately formed into any shape, and shows a high specific modulus and high flexural rigidity. This film and new molding technology controlling the edge-stiffness of the diaphragm make it possible to miniaturize microspeakers much more. As a diaphragm material for Hi-Fi loudspeakers, a composite film made of polymethyl pentene, with the lowest density in polymers, and a flaky material has been developed, of which the mechanical loss tangent, the specific modulus, and the flexural rigidity are high. By using a diaphragm made of the composite film, it is possible to realize flat frequency response characteristics and low harmonic distortion, especially in the high frequency range.