title: Preventing damage to miniature-loudspeaker by means of dynamic detection of excessive diaphragm displacement.
abstract: The rapid development of consumer electronics and the extensive use of mobile devices require the ample use of miniature-loudspeakers for audio applications. The demand for better sound pushes manufacturers to design digital signal processing (DSP) chips (smart amplifiers), which in turn could cause unpleasant sound due to distortion and parameter nonlinearity or transducer damage caused by large diaphragm excursion or voice-coil (VC) burn. This article presents a methodology for nonlinear parameter estimation using an inverse method and displacement limiter for large VC displacement-dependent transducer damage prevention. A set of transduction equations is employed to inversely determine parameters using a polynomial expression. The appropriate selection of an objective function incorporating the unknown vector of nonlinear parameters leads to the adjoint problem that requires a gradient solution. A numerical solver is provided to obtain the VC displacement, current, and derivatives using a robust hybrid spline differential method. The dynamic limiter is proposed to control the peak values of the VC velocity so as to limit an excessive displacement which prevents impulsive damage to the receiver and further application of the DSP board. Numerical and experimental results indicate that the proposed method has high efficiency and can be widely used in transducer applications.
authors.affiliation: Bachelor Program in Precision System Design, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan.
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Tsai
authors.affiliation: Department of Applied Mechanics, Motilal Nehru National Institute of Technology Allahabad, Teliyarganj, Allahabad (UP) 211004, India.
authors.forename: S J
authors.initials: SJ
authors.lastname: Pawar
authors.affiliation: Department of Mechanical and Computer-Aided Engineering, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan.
authors.forename: Chi-Chang
authors.initials: CC
authors.lastname: Wang
authors.affiliation: Department of Mechanical and Computer-Aided Engineering, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan.
authors.forename: Jin H
authors.initials: JH
authors.lastname: Huang
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D000465:Algorithms; D000669:Amplifiers, Electronic; D003198:Computer Simulation; D004867:Equipment Design; D008904:Miniaturization; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D009716:Numerical Analysis, Computer-Assisted; D012815:Signal Processing, Computer-Assisted; D013016:Sound / Q000009:adverse effects; D014159:Transducers