| 摘要 |
PURPOSE: A tightly bound optical cable is provided to greatly improve optical fiber density by closely disposing the units and thereby reducing a space for receiving additional tensile wires and coating layers. CONSTITUTION: A central tensile wire(31) made of a steel wire or a high tensile synthetic resin is arranged on a central axis of the optical cable. A plurality of tightly bound optical fibers(10) are closely deposited and positioned on a peripheral surface and are coated with predetermined enclosures(34,35,36) in a twisted state. The tightly bound optical fibers(10) are formed in a manner that a plurality of single-core fibers(11) are coated with predetermined successive coatings(13) and given neck portions(15) are provided between the adjacent coatings(13). Tension chambers(20) made of aramid fibers having high tensile strength are disposed between the adjacent optical fibers(10) in order to endure an external tensile load. The enclosures are formed in series with a waterproof layer(34), a coated layer(35) made of aluminum or steel, and an outermost layer(36).
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