Optical fiber cable
An optical fiber cable of the present disclosure is formed by assembling a plurality of drop optical cables, and each of the drop optical cables has a structure where at least one or more optical fiber cores and a tension fiber or a tension member is embedded in a sheath such that the drop optical cable has two or more axes each having a minimum value of a second moment of area with respect to arbitrary neutral planes, and even an optical cable obtained by assembling drop optical cables has a structure having two or more axes each having a minimum value of the second moment of area with respect to arbitrary neutral planes.
1 . An optical fiber cable in which a plurality of drop optical cables are bundled, wherein each of the drop optical cables has, in a cross section perpendicular to a longitudinal direction thereof, two or more neutral planes minimalizing a second moment of area; and
wherein 2N 2 −2N+1 (where N=1, 2, 3, . . . ) drop optical cables are arranged in a rhomboid shape on a cross section of the optical fiber cable, and each of the neutral planes of the plurality of drop optical cables is parallel to a diagonal line of the rhomboid shape.
2 . The optical fiber cable according to claim 1 , wherein each of the drop optical cables comprises an optical fiber core arranged at the center thereof,
a sheath covering a periphery of the optical fiber core, and
a tension member or a tension fiber embedded in the sheath symmetrically with respect to the neutral planes.
3 . The optical fiber cable according to claim 1 , wherein the N (where N≥3) drop optical cables are uniformly arranged in an outer periphery around tension member, and
the neutral planes of the N drop optical cables are orthogonal to a straight line connecting the center of the drop optical cables and the center of the tension member.
4 . The optical fiber cable according to claim 3 , wherein the N drop optical cables are arranged in S-twist or SZ-twist around the tension member.
5 . The optical fiber cable according to claim 1 , wherein each of the plurality of drop optical cables have
a cross-sectional shape regarded as a regular polygon, and
a tension member is disposed at each corner.