| 摘要 |
PURPOSE:To attenuate a high frequency component and to reproduce a soft sound by bonding a drawn film having microvoids on the surface of a foaming material in an acoustic transducer in which a plate piezoelectric element is formed in the foaming material. CONSTITUTION:The plate piezoelectric element 1 is incorporated in the center part of the plate form synthetic resin forming material 2 consisting of a hard resin foaming material. The lead wire 4 of the piezoelectric element 1 is connected to a connector 5 disposed at the end face of the foaming material 2. On both the surfaces of the foaming material 2, the drawn film 3 made of polyethylene or polypropylene having the microvoids is bonded. When a sound signal is inputted to the connector 5, the element 1 resonates in the foaming part at both the sides, resonates in the direction of the thickness of the foaming material 2 to enhance an output sound pressure level and reproduce the sound of a high output from the surface of the foaming material 2. At this time, the sound of a high pitched sound area is attenuated by the film 3 and reproduced to reproduce the soft and easily listening sound.
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