Directivity Analysis of a Novel Piezoelectric Film Based Ultrasonic Microspeaker Array

In this paper, a novel piezoelectric film based ultrasonic microspeaker array is proposed. The SiO₂/Pt/Pb(Zr,Ti)O₃ /Pt/Ti/SiO₂ multimorph structure has been designed and fabricated using silicon based micro-machining process. The membrane size of the single transducer cell is 1000times1000times2.5 mum ³, and the main resonance frequency is located near 68kHz. The performance of directivity is a very important parameter in microspeaker array. Especially in ultrasonic applications, a good transmitting directivity of microspeaker array is indispensable. Dissimilar arrangement of the cells in transducer array could cause different directivity performance. After comparison, when achieving a good transmitting directivity, the square combined plane array has the smallest array area. In addition, the directivity patterns of different planes vertical to the microspeaker array plane are also discussed