Ube Nitto Kasei Co., Ltd.

Sumitomo Electric Industries, Limited

Nippon Telegraph and Telephone Corporation

Toku Ishii

Kazunori Watanabe

Hiroki Ishikawa

Yoshiyuki Suetsugu

Hideyuki Iwata

Ryouzo Nishikawa

Kenji Ito

Shigeru Tanaka

In applying an intermediate coating layer of thermoplastic resin onto the periphery of a central tensile member and applying a main coating of polyethylene resin, having continuous spiral grooves that are for accommodating optical fibers and are inverted periodically in direction along the length direction, onto the outer periphery of the abovementioned intermediate coating layer, a cooling medium is blown or made to flow with priority onto the grooves after melt discharge to form a spacer with which even though the minimum rib thickness of the ribs that define the abovementioned spiral grooves is 1.0 mm or less, the groove inclination angle &#x3b1; of the spacer cross section at the inversion parts is 18&#xb0; or less.

Spacer for optical fiber cable, method for producing said spacer, and optical fiber cable using said spacer

A polyethylene spacer for optical fiber cable including a central tensile member, an intermediate coating layer arranged on an outer periphery of the central tensile member and being compatible with polyethylene and a main coating arranged on an outer periphery of the intermediate coating layer and having continuous spiral grooves for accommodating optical fibers and which are inverted periodically in a lengthwise direction. The main coating is formed from polyethylene resin. The spacer includes ribs defining the spiral grooves. A minimum thickness of the ribs is 1.0 mm or less, the groove inclination angle &agr; of a cross section of the spacer at inversion part is 18&deg; or less. A resin density of a root part of each rib is the lowest in comparison to a resin density at a tip part of the rib and central parts of the rib between the root part and the tip part.

Spacer for optical fiber cable and optical fiber cable using the spacer

An optical cable has a plurality of optical fibers. The optical fibers are contained in fiber containing cavities of chamber elements. Each chamber element has a bottom part and a pair of side wall parts, which defines a fiber containing cavity. The individual chamber elements containing the optical fibers are assembled around a thickening layer in an S-Z strand. Each side wall part is formed such that its thickness gradually decreases from its base end portion toward free end portion. Also, the thickness of the bottom part is greater than the thickness of each side wall part.

Optical cable and optical cable chamber element

An optical cable has an S-Z stranded part in which plurality of chamber elements containing optical fibers are assembled around a central member in an S-Z strand in the state where their bottom faces are in contact with the central member. Each chamber element has such a characteristic that its flexural rigidity in the depth direction of its fiber containing cavity is smaller than that in the widthwise direction thereof. Assuming, of distortion energy of the chamber element in an S-Z reverse portion within the S-Z stranded part, the distortion energy in the case where the bottom face of the chamber element is in contact with the central member to be U.sub.1, and the distortion energy in the case where a side face of the chamber element is in contact with the central member to be U.sub.2, a relational expression of .DELTA.U=U.sub.1 -U.sub.2 .ltoreq.0.2(mJ/mm) is satisfied.

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Gifu, Japan

Toku Ishii