Acoustic Research and Control of Piezoelectric Speakers Using a Spatially Modulated TiOPc/Piezo Buzzer Actuator

An opto-piezoelectric laminate composed of a photosensitive electrode and a PZT (Lead Zirconate Titanate) layer modulated by a light field was adopted as the research platform of this paper. The photosensitive electrode is a thin film formed by mixing TiOPc (Titanium oxide phthalocyanine) and a copolymer. During operation, the instant variation of TiOPc impedance when illuminated with light beam patterns created spatially varying electric field across the piezoelectric actuator made of PZT. The processes used to create this opto-piezoelectric composite and its application to acoustics are discussed in this paper. For example, it was known that the low-frequency performance of flat piezoelectric loudspeakers is poor. By taking advantages of the characteristic of the photoelectric conductive electrode, which demonstrated noticeable impedance change at low-mid range frequency (about 40-8000Hz), a way to enhance the low-frequency performance of the flat piezoelectric speakers are examined. Various illumination pattern tried and examined to control the acoustic beam patterns created are also presented. The experimental results confirmed the directivity controlling capability of acoustic pressure generated through external illuminated light patterns by using the opto-piezoelectric platform are detailed as well.