Electret membrane - has constant resonance frequency with varying temp combined with good electret properties

摘要

An electret membrane comprises a thin layer of electret material possessing good charge-retaining properties, e.g. Teflon (RTM), laminated onto a thin support layers, e.g. by welding, glueing or spraying. This supporting layer determines the resonance frequency and pref. has mechanical properties such that the frequency remains effectively constant from -30 to + 80 degrees C. Prefd. support materials are Mylar (RTM) or metal, e.g. Ti or Ni.