| 摘要 |
PURPOSE:To prevent the breaking of an optical fiber and the increase in transmission loss at the time of a fire by holding non-combustile heat resistant fibers and optical fibers by retaining winding tapes in grooves provided longitudinally on the outside peripheral face of a wire-shaped body and by covering the entire part with a fire-retardant sheath. CONSTITUTION:The spiral grooves 2 are provided to the outside circumference of the wire-shaped body 1 consisting of aluminum and the optical fibers 3 and buffer layer 4 consisting of carbon fibers are packed therein. The assembly is held by the retaining windings 5 of glass mica tapes. The entire part thereof is then covered by the fire-retardant polyethylene sheath 6. The optical fibers 3 consisting of the two layers formed with denatured silicone rubber plus silicone rubber on glass fibers or the fiber type coated with a UV resin are used. The optical fibers 3 are protected at the time of the fire by this structures and since no side pressures are exerted to the optical fibers 3, the breakage thereof is prevented and the increase in the transmission loss is suppressed. |
