オオイシ　クニオ   大石　邦夫    所属   コンピュータサイエンス学部 コンピュータサイエンス学科    職種   教授
言語種別	英語
発行・発表の年月	2013/05
形態種別	国際会議論文
査読	査読あり
標題	Loudspeaker for low frequency signal driven by four piezoelectric ultrasonic motors
執筆形態	共著
掲載誌名	International Congress on Acoustics 2013 Montreal
掲載区分	国外
著者・共著者	Juro Ohga, Hirokazu Negishi, Ikuo Oohira, Hiroya Saito, Kunio Oishi, and Kazuaki Maeda
概要	The authors are developing a completely new direct-radiator loudspeaker as an alternative of the conventional electrodynamic loudspeaker. It is driven by continuous revolution of piezoelectric ultrasonic motors, It is useful for radiation of very low frequency signal because it shows almost flat phase frequency characteristics in low frequency region.. A preliminary model, named DMDS (dual-motor, de-spin) model, included co-axial two ultrasonic motors. Stator of one motor is fixed to the base and it of the other is connected to the cone radiator. Velocity modulation for any motor induces driving force for the cone radiator. Output sound at low frequency range (for example, 30 - 120 Hz) by this model was excellent because it has no significant resonance in this frequency region. However, its output sound was occasionally poor. At this Congress, a highly improved model named QMDS (quad-motor, de-spin) model is presented. It uses two co-axial DMDS mechanisms. The experimental model has a cone radiator of 46 centimeter in diameter and an enclosure of 268 liter. Its working frequency range is same as DMDS model. Harmonic distortions included in the output signal are improved to be less than 10 per cent. Its sound quality is excellent.