Mellow Tim, Kärkkäinen Leo
Nokia UK Ltd., Farnborough, Hants GU14 0NG, United Kingdom.
J Acoust Soc Am. 2008 Sep;124(3):1497-504. doi: 10.1121/1.2951601.
The equations for the electromechanical force conversion in single-ended and push-pull electret transducers are derived. Traditionally, the charge distribution has been modeled as a concentrated layer at an arbitrary distance from the surface of the dielectric. For the purpose of this analysis, a negative charge is assumed to be evenly distributed throughout the dielectric. The membrane has a conductive coating in which a positive charge is induced, giving an overall dipole charge. The resulting formulas are used to derive the voltage sensitivity of a microphone and the equivalent electrical circuit for the electromechanical transduction part of a microphone or loudspeaker. An equivalent external polarizing voltage is then derived that would produce the same driving force in a conventional electrostatic loudspeaker without a stored charge. The condition for the static stability of a circular electret membrane is also determined.
推导了单端和推挽式驻极体换能器中机电力转换的方程。传统上，电荷分布被建模为距电介质表面任意距离处的一个集中层。出于本分析的目的，假设负电荷均匀分布在整个电介质中。膜具有导电涂层，其中感应出正电荷，从而产生整体偶极电荷。所得公式用于推导麦克风的电压灵敏度以及麦克风或扬声器机电转换部分的等效电路。然后推导出一个等效外部极化电压，该电压在没有存储电荷的传统静电扬声器中会产生相同的驱动力。还确定了圆形驻极体膜静态稳定性的条件。
