The device relates to improvement in flexible, flat, multi-conductor electrical cables. As a flexible flat cable of this type, a cable such as shown in FIG. 1 has been suggested and is disclosed in Japanese Patent Application JUA-sho 58-143,540. As shown in FIG. 1, flat cable 1 is prepared by arranging in parallel a plurality of flexible conductor assemblies 4 made by winding a conductor 3 such as copper foil around a flexible filamentary body 2 helically in one direction, and laminating the flexible conductor assemblies 4 between resinous layers to fix them and provide insulating covering layers.
In flat cables of this type, a conductor 3 is helically wound around flexible filamentary body 2 in one direction. Therefore, that flat cable was difficult to manufacture because the flexible conductor assemblies 4 bent or wound. The finished flat cables had occurrences of breaking due to formation of looseness or strains and application of excessive reaction to a specific flexible conductor. To eliminate such defects, it is suggested according to this invention to form two conductor layers which differ from each other in the directions of winding about the periphery of the flexible filamentary core. Flat cables made in accordance with this suggestion are improved in looseness, and they tend to have a somewhat shorter bending life and be somewhat less flexible than the cables shown in FIG. 1.
Therefore, the object of the invention is to provide highly flexible flat cables having substantially eliminated the above-mentioned defects, having substantially no cable looseness and having excellent bending life and excellent flexibility.