DEVICE FOR MANUFACTURING ELECTRET

摘要

The permanent electric polarization is imparted to the sensitive element by electronic bombardment within an enclosure wherein prevails a rarefied atmosphere and in which said bombardment is followed with a coating of the so-polarized sensitive element with a film of liquid of very low saturating vapor pressure whose dielectric strength is higher than that of the rarefied air of the enclosure and having advantageously lubricating properties.