| 摘要 |
Thin film electrets for use in transducers, or the like, may be prepared by irradiating the film with controlled electrons applied by way of a beam. According to this invention, a low energy, focused beam is scanned over the surface of a thin film to produce individual electret areas. Beam energy is maintained low enough to insure that electron penetration is substantially less than the thickness of the film and high enough to insure that the beam is not deflected away from the foil before the charge reaches a sufficiently high level. As a result, a more uniform charge-density product is formed, the charge is bipolar, charge is retained more efficiently than with other processes, and charge time is shortened. |
