Optimization Of Electro-Thermo-Acoustic System Based On The Acoustic Source Of Carbon Nanotube Film

Carbon nanotube film is a new type of nano materials, which has good performance in mechanical, electrical, thermal, optical and other fields. With the AC power putted on the carbon nanotube film, It can produce sound. The carbon nanotube film can be made into a new kind of loudspeaker based on the theory of thermo acoustic effect. It has many advantages compared with the traditional loudspeaker, like transparency, flexibility, stretchability, no magnetism, no vibrating component. At the same time, it still has some disadvantages like frequency distortion, low output sound pressure and so on. The optimization in electro-thermo-acoustic system of the carbon nanotube film loudspeaker is significant.The main work and achievements are as follows:(1)The sound field characteristics and influencing factors of the sound source of carbon nanotube films are analyzed in this paper; In this paper, the basic sound source system of carbon nanotube film is constructed. We tested the near field and the far field sound pressure, and analyzed the test results.(2)Based on the temperature rise theory of carbon nanotube film, the trend of the film’s temperature with the sound frequency is analyzed; We used infrared thermal imaging instrument to test the film’s temperature with the input voltage, input frequency and time. And then, the change of film’s resistance with temperature was tested, and the influence of the factors above on the output sound pressure of the film was analyzed in this paper.(3) The output sound pressure frequency of the carbon nanotube film is two times of the input voltage. Based on the theory of thermo acoustic effect, we made a theoretical analysis of the frequency distortion. Three optimization methods are proposed in this paper, which are the series DC power method, the clamp circuit, and the summation circuit. The three methods are validated by experiments, and the advantages and disadvantages of each method are discussed. We solved the problem of frequency distortion and improved the output pressure of the film.