Study On System Design And Optimization Of Piezoelectric Ceramic Loudspeaker

The basic working principle of a piezoelectric ceramic loudspeaker is very different from an electro-dynamic loudspeaker. When an electrical signal is applied to the piezoelectric ceramic, the "inverse piezoelectric effect" causes the bending vibration of ceramic, then the sound can be reproduced to the air. Piezoelectric ceramic loudspeaker commonly consists of 5(or over) piezoelectric layers and metal layers. Because of the complication of structure and vibration mode of piezoelectric ceramic loudspeaker, there are few research and study on piezoelectric ceramic loudspeaker and no mature model which can describe the vibration of piezoelectric ceramic loudspeaker exactly. In fact, relative to electro-dynamic loudspeaker, the main problem of piezoelectric ceramic loudspeaker is lack of low frequency. Also, piezoelectric ceramic loudspeaker is always used with a front cavity or a back cavity. Therefore, the study on low frequency performance of piezoelectric ceramic loudspeaker and performance of piezoelectric ceramic loudspeaker system can make great senses and solve many problems.By laser measurement of Klippel, the displacement curve is got to analyze the vibration mode of piezoelectric ceramic loudspeaker. This paper found that in low frequency the piezoelectric ceramic loudspeaker still works like a piston(not exactly). Then this paper discusses the design and optimization of the piezoelectric ceramic loudspeaker with a front cavity or a back cavity. By experiment design and result analysis, this paper found:With a front cavity, Q value of the piezoelectric ceramic loudspeaker and the location of intermediate-high frequency response peak is related to the number of holes in front cavity. With the increase of the number of holes in front cavity, the Q value becomes bigger and the location of the peak moves towards the higher frequency.With a front cavity, the intermediate frequency response compensation and high frequency performance is related to the volume of the front cavity. With the increase of the volume of front cavity, the intermediate frequency response compensation moves towards the lower frequency and the high frequency response declines earlier.With a back cavity, the system resonant frequency is related to the volume of back cavity. With the increase of the volume of back cavity, the system resonant frequency of piezoelectric ceramic loudspeaker system moves towards the lower frequency.Meanwhile, this paper introduces the inverted box structure to piezoelectric ceramic loudspeaker system. By theoretical analysis and experiment design, this paper found that inverted box structure also applies to piezoelectric ceramic loudspeaker system, and by suitable design of the inverted box structure, the low frequency performance can be improved effectively.