| 摘要 |
PURPOSE:To limit an optical fiber distortion which is generated when a cable has been bent, to <=0.25%, by selecting a twist pitch of an optical cable and a density of a resin, to an appropriate value. CONSTITUTION:A groove whose sectional shape is a U-shape is provided spirally on a grooved rod 5, and a steel stranded wire 6 which functions as a tension member is provided in the center of the grooved rod 5. Optical fiber tapes 7a, 7b,...,7e are contained in the U-shaped groove, the space part is filled with grease 8, a pressure winding 9 and a housing 4 are provided on the periphery of this optical fiber aggregate, and it functions as a cable. The optical fiber tape is formed by laminating four pieces of 5-core optical fiber tapes 7, and constituted of optical fibers 10a, 10b,...,10e of fiber cores, and a plastic coating 11 for surrounding them. When a density of a resin packed in the optical cable exceeds 400, there is the possibility that it flows out of the inside of the cable, therefore (d)<400 is given as a limiting condition, and also the twist pitch (p) is set to the maximum 1,000mm.
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