Shenzhen, China
Shenzhen, China

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Zhang T.-L.,Tongji University | Huang X.,Tongji University | Zheng K.,Tongji University | Zhang X.-W.,Tongji University | And 5 more authors.
Wuli Xuebao/Acta Physica Sinica | Year: 2014

Piezoelectrets are a kind of space-charged electret material with a void-structure. The piezoelectric effect in such a material is related with its microstructure and space charge. In this paper the micro-structure of polypropylene (PP) films is first modified by using a pressed gas expansion process to enhance the charging capability of the films, and then a direct contact charging is carried out to polarize the expanded films. The relationship between the applied voltage and the space charge density, and the influence of the applied voltage on the piezoelectric performance of PP films are investigated. Results show that for 100 μm thick modified PP films, the critical voltage necessary for the build-up of the "macro-dipoles" in the inner voids is approximately 2 kV; once the "macro-dipoles" are built up, the PP films will exhibit piezoelectric effect. With increasing polarization voltage, the space charge density gradually increases, resulting in significant enhancement of piezoelectric effect. For the PP films polarized at a peak voltage of 8 kV, the space charge density, d33 coefficient, and the figure of merit FOMv (d33 · g33) are 0.56 mC/m2, 379 pC/N and 8.6 (GPa)-1, respectively. Since not only the FOMv of the PP films is almost two orders of magnitude larger than that of PVDF, but also the acoustic impedance in such a material is very low (~0.025 MRayl), the PP films have an obvious advantage as applied in airborne ultrasonic transmit-receive or pulse-echo systems. © 2014 Chinese Physical Society.


Zheng J.,Shenzhen Horn Audio Co. | Liu T.,Shenzhen Horn Audio Co. | Liang H.,Shenzhen Horn Audio Co. | Chen X.,Shenzhen Horn Audio Co. | Zhu B.,Shenzhen Horn Audio Co.
Yadian Yu Shengguang/Piezoelectrics and Acoustooptics | Year: 2015

We analyzed the effect of 4 different methods in stacking films to improve the miniature piezoelectric microphone's sensitivity. There is no effect to stack piezoelectric film by direct laminated or conductive adhesive bonded in miniature microphones. However, using the conductive ring to connect films can increase the microphone's sensitivity of 6 dB. The experiment results show that the microphones use the thin conductive ring to connect films have more stable performance than the microphones use thick conductive ring to connect the films, and the frequency response curve become smoother. ©, 2015, Sichuan Institute of Piezoelectric and Acoustooptic Technology. All right reserved.


Zheng J.,Shenzhen Horn Audio Co. | Liang H.,Shenzhen Horn Audio Co. | Zhu B.,Shenzhen Horn Audio Co.
Yadian Yu Shengguang/Piezoelectrics and Acoustooptics | Year: 2015

By using the porous piezoelectret film to replace the acoustic-electric conversion of conventional electret condenser microphone (ECM), a piezoelectric microphone was fabricated in this work. By making use of the advantage of ultra-thin piezoelectret film and the structure improvement, the piezoelectric microphone's thickness was reduced from 3 mm to 1 mm. We adopted 30 dB gain FET in the microphone's circuit to solve the problem of low sensitivity. And in order to reduce the influence of parasitic capacitance, we used the single copper PCB. However, when the microphone connected into mobile phone, it subjected to the electromagnetic interference(EMI). After that, we improved the PCB design by using double-sided copper PCB to enhance electromagnetic shielding, and resolved the problem of EMI. Finally, by making use of the waterproof performance of piezoelectret film, and by waterproofing the piezoelectric microphone circuit, the piezoelectric microphone satisfies the IPX7 waterproof standards. ©, 2015, Sichuan Institute of Piezoelectric and Acoustooptic Technology. All right reserved.


Huang H.,Shenzhen Horn Audio Co. | Zheng J.,Shenzhen Horn Audio Co. | Liang H.,Shenzhen Horn Audio Co. | Zhu B.,Shenzhen Horn Audio Co.
Yadian Yu Shengguang/Piezoelectrics and Acoustooptics | Year: 2015

Using porous piezoelectret film to fabricated piezoelectric sensor, then put it on wrist to collect pulse vibration signals, and with the corresponding circuit and display device, we fabricated a new type of piezoelectret pulse analyzer. Due to adopting piezoelectret film as the pulse transducer, the pulse analyzer has high sensitivity, low distortion and good repeatability. In the pulse analyzer, the piezoelectric membrane electrode in the form of plasticizing encapsulated is easy to introduce interference. The sensor encapsulate as piezoelectric microphone has the strong ability of anti-interference ability, and FET has the advantage of easy-integration, lower cost, and the waveform figure measured similar to typical ECG waveform has great medical reference value. © 2015, Sichuan Institute of Piezoelectric and Acoustooptic Technology. All right reserved.


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Shenzhen Horn Audio Co. | Date: 2012-01-25

Consumer electronic products, namely, audio amplifiers, audio speakers, audio receivers, electrical audio and speaker cables and connectors, audio decoders, video decoders, speakers, power conversion devices, power converters, and power inverters.

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