| 摘要 |
PURPOSE:To extend surface sound phenomenon due to split resonance to a high frequency band by forming a diaphragm having film thickness made uniform with only the edge part made thin to improve a surface rigidity as the diaphragm. CONSTITUTION:A thermoplastic resin such as a polyarylate is formed into a film 1, it is heated 2 to near its melting point to fluidize. In this state, elastic bodies 5, 6 fix a part corresponding to an adhesion margin to be adhered to the speaker frame of said film 1. Then, the diaphragm part is formed (C) at the center of the film 1 fixed in ring shape with said elastic bodies 5, 6. This is formed by vacuum forming, compress forming or press forming using a desired shaped metal die 9. The edge part is formed (D) by expanding mechanically the distance between the diaphragm metal die 9 and said elastic bodies 5, 6. This is attained by inserting pseudo cylindrical rings 4, 7 having wedge cross section. Finally, the elastic bodies 5, 6 fixing said adhesion margin are removed from the film. |
