| In recent years, there has been a bone conduction technology rapid development .It has not only restricted in terms of military equipment, there are now included headphones, hearing aids, cell phone applications and so on in common life . The main way of current research and application of bone conduction hearing aids is convert electromagnetic signal into a sound vibration signal, but useing piezoelectric materials to conversion signal is very rarely.Because of The piezoelectric actuator has characteristics of compacting structure, no electromagnetic interference, fast response, high resolution deformation, the area of application will continue expand. Applied piezoelectric element to the bone conduction hearing aid devices in the country have the reseach of ultrasonic bone conduction hearing aid device , but it is primarily involved in the theoretical stage, but applied piezoelectric element to the bone conduction hearing aid devices in abroad are carried out rapidly, mainly in Japan, It has carried out more research work and has been made of piezoelectric actuator technology of bone conduction hearing aid device products, and for its products' in the market prospects for the development of applications is very optimistic estimates, there may be more widely used. However, the current study abroad piezoelectric bone conduction hearing aid devices, the application still at an early stage, small volume, higher prices, It's performance (voice spread effects, voice distortion, frequency, etc.) have to be in-depth study.This paper studies a new bone conduction hearing aid devices, this piezoelectric actuator bone conduction hearing aid devices, using a piezoelectric element as the conversion components, converses audio signal into a piezoelectric oscillator vibration using piezoelectric oscillator and skull contacts, and ultimately transmitted to the ears sound. And to study its basic laws and characteristics, with a view to gaining the optimum structure and voice signal transduction. This field of study, there are many interdisciplinary (research related to medicine, physiology, mechanical engineering, piezoelectric school, vibration analysis, electrical, and other various areas of knowledge) new problems to be solved, need a lot of theoretical analysis and experimental research.The full text is divided into six chapters, the following major department1. PerfaceThis chapter deals bone conduction phenomena, and made use of piezoelectric material audio signal conversion, as well as its advantages. Talking about the bone conduction technology applications and development prospects. Now bone conduction hearing device's developments at home and on abroad. The purpose and objective of research on the piezoelectric bone conduction hearing devices.2. The Piezoelectric bone conduction hearing device theoretical researchThe bone conduction acoustic vibration piezoelectric vibrator works by the piezoelectricity material counter piezoelectric effect, using the audio frequency electrical signal direct drive piezoelectric ceramics part to have the mechanical vibrations. Then the bone conduction acoustic vibration piezoelectric vibrator transmits directly this kind of vibration into the skull, men can sense the sound. This chapter first references overview of the hearing, followed by a piezoelectric drive element bone conduction acoustic vibration of the piezoelectric oscillator basic components, but also the electrical energy conversion components, piezoelectric drive element of the decision bone conduction vibration sound pressure the performance of electric oscillator, the piezoelectric effect on the basic concepts, the discussion of the piezoelectric material and the basic physical properties of the important performance parameters, including electrical and mechanical coupling coefficient, piezoelectric constant, mechanical quality factor and the frequency constant. Theoretical analysis choose suitable for piezoelectric bone conduction theory of piezoelectric ceramic materials, and supporting way. Rectangular ends of the piezoelectric chip clamped bending deformation and vibration-theoretical analysis to identify affected piezoelectric chip impact deformation and vibration factors.3. Bone conduction acoustic vibration of the piezoelectric oscillator Simulation and Experimental Research This chapter using finite element analysis software ansys to analysis the factors impact on the piezoelectric chip deformation and resonance frequency analysis . According to finite element analysis, select piezoelectric bimorph. On the selected of piezoelectric bimorph experiments performance analysis, test points piezoelectric chip at different voltages, and different rules on the length of the deformation, test bimorph dynamic response analysis of the frequency of response. Flexible application made of piezoelectric material to change the nature of the chip, and test coverage under the flexible material deformation of the piezoelectric chip, the resonant frequency of vibration and sound pressure generated, experimental prototype structure for the future and provide a theoretical basis.4. Experimental prototype structural design and experimental analysisThis chapter from the theoretical analysis design piezoelectric devices bone conduction hearing of the each parts, including the addition of a fixed structure, health-oriented structural vibration, noise institutions leakproof tone of the design. Then testing the performance of an experimental prototype . To illustrate the prototype performance, in contrast to market the electromagnetic bone conduction hearing device. Testing on the prototype and electromagnetic bone conduction hearing device in the basic parameters measured including DC resistance, impedance, resonant frequency, time-domain analysis, and the major tests prototype electromagnetic bone conduction hearing device on the conservation of harmonic signals in the signal response, the main frequency response is the frequency sound pressure curves were compared. Study on use of TES-1358 real-time audio analyzer in a number of different frequency bands selected election wave signal is inspired by the experimental prototype and electromagnetic bone conduction hearing device under two different frequency bone conduction hearing device performance. Oscilloscope analysis by the two devices distortion analysis, and analysis of the distortion of the reasons for the two devices.Conclusion:The performance of piezoelectric bone conduction hearing device is similar the performance of electromagnetic.It will be able to meet the needs of the hearing.5. Audio signal amplifier design and experimental analysis This chapter for the bone conduction hearing device designed simple application of portable amplifiers, to reallise audio signal amplification. According to test for the last chapter of the piezoelectric bone conduction hearing installed value of the basic parameters, determine the design of amplifier performance requirements, and in accordance with the requirement of the circuit form, select operational amplifier, identified circuit. According to the requirement of the circuit components determined resistance and capacitance values. Circuit design need testing, magnification and measurement-band amplifier is the main test , according to test results on the amplifier to analysis amplifier's performance.6. ConclusionHas given the full text main conclusion, and has carried on the forecast to the next bone conduction sense of hearing installment's research work, proposed present's research direction.
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