| 摘要 |
The object is to prevent damage to or breakage of optical fiber cores 11 due to the cable getting stuck with ovipositors of black cicadas. An optical drop cable 10 is proposed which includes optical fiber cores 11, tension-resistant members 12, an outer sheath 15 made of a single material and covering the cores 11 and the tension-resistant members 12. The bark of a young tree T has elasticity, so that if cicadas lay eggs in such a bark, the holes in which eggs are laid closes and the eggs will not hatch. If such a bark has abrasion resistance, cicadas cannot stick their ovipositors into the bark. Thus, the outer sheath 15 is made of a polyurethane resin having a rebound resilience equivalent to that of a bark of a young tree, and having high abrasion resistance. By making the outer sheath 15 from such a resin, due to the elasticity and abrasion resistance of the resin, holes in which eggs are laid closes, thus making hatching of the eggs impossible, or cicadas cannot stick their ovipositors into the outer sheaths. Black cicadas will therefore not lay eggs in the outer sheath 15. This in turn prevents damage to or breakage of the optical fiber due to the cable getting stuck with ovipositors of black cicadas.
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