Nitto-denko Corporation

Mitsubishi Denki Kabushiki Kaisha

Seiichi Takaoka

Hidenori Takita

Tatsuhiro Hirakawa

Shinji Nohara

Kumie Yamana

Masatoshi Ochiai

An electret material having excellent charge retentivity against heat is provided. The electret materialincludes an electrode plate, a semiconducting layerformed on the electrode plate, and an electret layerformed on the semiconducting layer. The semiconducting layerincludes carbon and a fluororesin. This electret materialcan be inhibited from decreasing in the surface potential of the electret layerwhen heated to a high temperature.

Electret material and electrostatic-type acoustic transducer

Provided is a process by which an electret material having excellent thermal resistance of charge retentivity can be obtained. The process for producing an electret material of the invention includes an irradiation step, a formation step, and a charging step. In the irradiation step, a dispersion containing fine polytetrafluoroethylene particles is irradiated with &#x3b3; rays. In the formation step, the dispersion which has been irradiated with &#x3b3; rays is applied to an electrode plate and then dried, and the fine polytetrafluoroethylene particles are sintered to form a polytetrafluoroethylene layer on the electrode plate. In the charging step, the surface of the polytetrafluoroethylene layer is subjected to a charging treatment.

Process for production of electret material

A cathode-ray tube includes an envelope in which a panel portion, a funnel portion, and a neck portion are integrally formed, and a conductor film and a deflecting yoke mounted on an outer surface of the funnel portion. A strip-type electric field reducing piece has a coated portion coated with an insulator, and an exposed conductive material portion. The coated portion is disposed between the funnel portion and the deflecting yoke, and the conductive material portion is connected to the conductor film.

Growing community of inventors

Osaka, Japan

Seiichi Takaoka