Application of ceramic piezoelectric device to audio speaker

This paper describes a new flat-panel type ceramic piezoelectric transducer for audio speakers. The proposed transducer offers a simple configuration compared to a conventional magnetically actuated transducer. The drawbacks of piezoelectric actuated transducers are: (P1)..Impedance matching problem due to piezoelectric transducer; (P2) Resonance frequency problem caused by stiffness of piezoelectric transducer; (P3) Directivity problem caused by shape of panel; (P4) Amplitude problem caused by small piezoelectric vibration amplitudes. To solve (P1) and (P2), we newly developed a low frequency boost filter based on an LC resonance circuit. To solve (P3), to improve the directivity of the proposed transducer, we are actuated and measured various transducer arrangements and types of vibration plate. To solve (P4), we developed a new voltage based BTL amplifier which is suitable for piezoelectric actuators. We verified the validity of the proposed transducer by the frequency domain of white noise.