A piezo-electric speaker capable of easily ensuring a uniform broad-band sound pressure and reproducing a large acoustic signal has a piezo-electric member (10) to generate vibration in accordance with an applied electric signal. A piezo-electric vibration plate (15) is adhered to the piezo-electric member (10). The piezo-electric vibration plate (15) converts the vibration to sound. The thickness of the piezo-electric vibration plate (15) is formed so as to be different in accordance with the distance from the vibration center of the piezo-electric member (10).

 
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> Semiconductor laser element and optical data recording device

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