Methods to increase sound fidelity and quality produced from piezoelectric devices

Abstract

Methods to increase sound level, fidelity and quality produced from vibrating lamina such as piezoelectric actuators, vibrating plates or vibrating films are presented. Results of using the methods are shown for piezoelectric devices. Four methods are described: (1) tailoring the vibration response to develop desired deformation shapes and amplitudes, (2) mapping vibration out-of-plane deformation to ascertain locations on the surfaces of lamina suitable for stroke-like actuation, (3) coupling vibration to a collection of acoustic chambers and (4) increasing the vibration decay rate. The first two methods provide a single piezoelectric device with the functionality of numerous actuators combined. A piezoelectric actuator with numerous high-amplitude natural vibration responses has been produced using the aforementioned methods. Numerous high-amplitude vibrations increase the functionality of the devices. A collection of acoustic chambers were affixed to the piezoelectric actuator's surface. The addition of the chambers resulted in more efficient audio output. The result of using all of the aforementioned methods is a high fidelity, high-bandwidth, and high sound-quality audio device with a low physical profile. The use of the piezoelectric actuator effectively results in an audio driver with a thickness less than 1 mm. The piezoelectric audio device achieved a response of 93±4 dB measured at 1 cm in the frequency range (1–5 kHz) with very good audio output for frequencies less than 1 kHz. The methods can be used to design other devices using solid-state piezoelectric actuators or vibrating lamina (e.g., plates or films).