| 摘要 |
PROBLEM TO BE SOLVED: To provide a three pole plug/jack having the same dimension as a two pole plug/jack by constituting with a first electrode formed in a cylinder shape, projecting from a housing; a second electrode formed on the outside of the first electrode; and a third electrode which is a signal terminal installed on the surface of the second electrode. SOLUTION: A cylindrical insulating part 2 for holding an electrode and insulating two electrodes is installed, and a first electrode 1 made of a conductive metal is installed on the cylindrical outer surface, and a spring electrode 3 of a second electrode is installed on the inner surface. A third electrode serving as a signal electrode 11 is installed on the first electrode 1 through an insulating layer 10. The signal electrode 11 is electrode is simply produced by conducting metal plating on the surface of the insulating layer 10. A housing 4 holds and insulates electrodes, and a lead wire is connected to each electrode. Since the energy electrode is not exposed, short circuit between electrodes is hardly generated, and since the signal electrode 11 is not exposed, oil films and dust are not attached and no contact failure is produced.
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