| 摘要 |
PURPOSE:To prevent the introduction of a radio wave to a telephone set, by covering an internal circuit of the telephone circuit with a conductive plastic film having the layer structure of a conductive layer and an insulating layer. CONSTITUTION:The circuit part 5 of a telephone set except a pushbutton dial 3 is covered with a conductive plastic film 7 of three-layer structure comprising a conductive layer 7a and an insulation layers 7b. The conductor layer 7 of the film 7 is made to an equal potential to a metallic bottom plate 2 by connecting them with a lead 8 and the bottom plate 2 is connected to an earth line 9. Thus, the circuit part 5 is covered with the conductor where all of the bottom plate 2, film 7 and pushbutton dial 2 are at 0 potential, allowing to prevent almost the introduction of radio wave to the circuit part 5. |
