| 摘要 |
1504203 Piezo electric film transducers PIONEER ELECTRONIC CORP 12 Feb 1975 [18 Feb 1974] 5886/75 Heading H4R In a transducer, e.g. for a headphone receiver, which employs a piezo-electric diaphragm made of uniaxially oriented high polymeric resin film which has a maximum piezo-electric constant in one direction in its plane and a lesser piezo-electric constant in all other directions, the diaphragm is of a shape having a major axis and a minor axis with the minor axis aligned with the direction of maximum piezo-electric constant. As described the diaphragm 1 can be of polyvinyl fluoride, p.v.c., nylon 11 or polypeptide but preferably of polyvinylidene fluoride which is uniaxially oriented by stretching the film to four times its length in one direction while holding the film in a bath at a temperature of 60‹ to 100‹ C. The film is coated on both surfaces with vacuum deposited aluminium to form electrodes and mounted on a frame 2 with its direction of largest piezo-electric constant aligned with the minor axis of the frame. The film is tensioned by a pad 3 of polyurethane foam between the diaphragm 1 and a perforated backing plate 4.
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