| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive multi-function sounder that can adjust a vibration characteristic in a completed product and enhance the yield of products without the need for excessive components and assembling precision. SOLUTION: A cover 1, a diaphragm 2 held by a cover 1a and vibrated through a sound frequency electromagnetic force, and upper and lower suspension spring 8a, 8b elastically supported to the cover 1 configure a vibration system operated at a comparatively lower frequency, a pole piece 4 is fixed at the center of the lower suspension spring 8b, a permanent magnet 5 and a voice coil 3 are fitted to the surrounding of the pole piece 4, and a permanent magnet 5 providing a magnetic field to generate an electromagnetic force to the diaphragm 2 configure a magnetic circuit having a comparatively greater mass. A groove 4c to match the mass of the magnetic circuit is placed to the center of the bottom face of the pole piece 4 and adding an additional mass to the groove 4c can match the resonance frequency. The additional mass is an adhesive including a high specific gravity adhesive or a weight. The component accuracy can easily be managed, the assembling load is relieved, the vibration characteristic is stabilized and the cost can be reduced.
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