| 摘要 |
PROBLEM TO BE SOLVED: To obtain a constantly-suitable magnetostrictive characteristic, and to obtain constant sound quality and a constant sound volume. SOLUTION: In a speaker apparatus, a magnetostrictive actuator 30 and a coil spring 51 are inserted into a storage part 23 which is a hole vertically penetrating a base housing 20, and furthermore, a screw 52 is inserted up to a position where the tip of a driving rod 35 of the magnetostrictive actuator 30 is abutted on a lower end face 12 of an acoustic diaphragm 10 and the coil spring 51 is compressed by a prescribed quantity. The shrinkage amount of the coil spring 51 is set to an amount by which a sum of a preload F1 applied to a magnetostrictive element 31 in the magnetostrictive actuator 30 and a load F2 applied to the magnetostrictive element 31 by the coil spring 51 becomes an optimum value and an optimum magnetostrictive characteristic (a characteristic that a magnetic field range in which a magnetostrictive value is linearly changed in a change of a control magnetic field becomes the widest range and a change in the magnetostrictive value in the change of the control magnetic field in the magnetic field range becomes the largest change). COPYRIGHT: (C)2009,JPO&INPIT
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