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Proceedings Paper

Light actuated piezoelectric speaker at resonant condition
Author(s): Hideki Okamura; Taki Yamamoto; Ryo Hamamura
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Paper Abstract

The concept of a light driven speaker was proposed as a new category of light driven actuator, and its feasibility was experimentally demonstrated. If a diaphragm of a speaker is made up of a light-driven actuator, sound would be produced upon irradiation of a modulated light. In this scheme, the light doubles as the signal and the energy source. With a conversion efficiency of 1 %, an audible sound is supposed to be generated from a 100 mW light source, therefore, energy-wise light actuated speaker should be possible. The limitation on the energy conversion efficiency of this scheme is discussed taking into account the energy loss due to the presence of a carrier wave that accompanies transmission. Unfortunately, a material that satisfies the requirements for this scheme is not found at present. Yet, since the purpose of this work is to show the feasibility of this concept and evaluate its possibility, it is an option to employ a combination of materials. In this preliminary study, we chose to combine a piezoelectric actuator and a solar cell with an appropriate interface for matching impedance. In the experiment, an 808 nm diode laser beam was modulated at audio frequency, and shined a solar cell. The audio signal was reproduced from the connected piezoelectric speaker as an audible sound. The maximum sound output of 3.1 mW was obtained. In a different scheme the maximum energy conversion efficiency of 4.4 % was obtained. These results show that the light actuated speaker is indeed feasible.

Paper Details

Date Published: 17 November 2008
PDF: 12 pages
Proc. SPIE 7266, Optomechatronic Technologies 2008, 72660C (17 November 2008); doi: 10.1117/12.813681
Show Author Affiliations
Hideki Okamura, International Christian Univ. (Japan)
Taki Yamamoto, Univ. of Massachusetts (United States)
Ryo Hamamura, International Christian Univ. (Japan)

Published in SPIE Proceedings Vol. 7266:
Optomechatronic Technologies 2008
John T. Wen; Dalibor Hodko; Yukitoshi Otani; Jonathan Kofman; Okyay Kaynak, Editor(s)

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