Optical fiber cable
An optical fiber cable includes optical fibers, a wrapping tube that wraps around the optical fibers and contacts outermost ones of the optical fibers, and a sheath that covers the wrapping tube and has recesses on an inner circumferential surface of the sheath. The recesses are recessed toward a radially outer side of the optical fiber cable such that a space exists between the wrapping tube and the sheath in each of the recesses.
1 . An optical fiber cable comprising:
optical fibers;
a wrapping tube that wraps around the optical fibers and contacts outermost ones of the optical fibers; and
a sheath that covers the wrapping tube and has recesses on an inner circumferential surface of the sheath, wherein
the recesses are recessed toward a radially outer side of the optical fiber cable such that a space exists between the wrapping tube and the sheath in each of the recesses, and
each of the recesses is configured to receive a different one of the optical fibers when the sheath shrinks.
2 . The optical fiber cable according to claim 1 , wherein each of the recesses includes an arc shape bottom.
3 . The optical fiber cable according to claim 2 , wherein
each of the recesses includes first and second sidewalls connected to the arc shape bottom, and
an angle between the first sidewall and the second sidewall is equal to or greater than 90 degrees.
4 . The optical fiber cable according to claim 2 , wherein
each of the recesses includes first and second sidewalls connected to the arc shape bottom, and
an end of the first sidewall on a radially inner side of the optical fiber cable and an end of the second sidewall on the radically inner side have an arc shape.
5 . The optical fiber cable according to claim 1 , further comprising:
a tensile strength member embedded in the sheath, wherein
one of the recesses overlaps the tensile strength member toward a radial direction of the optical fiber cable.
6 . The optical fiber cable according to claim 1 , wherein
the sheath has protrusions on an outer circumferential surface of the sheath,
the protrusions protrude toward the radially outer side of the optical fiber cable, and
one of the recesses overlaps one of the protrusions toward a radial direction of the optical fiber cable.
7 . The optical fiber cable according to claim 1 , wherein the optical fiber cable is a slotless-type optical fiber cable having no rod with slots.
8 . The optical fiber cable according to claim 1 , wherein
the wrapping tube comprises a wrapping tape longitudinally wound around the optical fibers, and
the wrapping tape has a lap portion in which one end of the wrapping tape overlaps another end of the wrapping tape without overlapping any of the recesses toward a radial direction of the optical fiber cable.
9 . The optical fiber cable according to claim 1 , wherein
the sheath includes main surfaces between the recesses adjacent to each other along a circumferential direction of the optical fiber cable, and
20%≤CL1/CL0×100≤80% is met,
where
CL0 is a length of a virtual inscribed circle inscribed in the main surfaces, and
CL1 is a total length of the main surfaces.
10 . The optical fiber cable according to claim 1 , wherein none of the recesses accommodates any of the optical fibers.
11 . The optical fiber cable according to claim 1 , further comprising:
optical fiber ribbons each comprising the optical fibers intermittently fixed to each other, wherein
the wrapping tube wraps around the optical ribbons, and
the optical fiber cable is a slotless-type optical fiber cable having no rod with slots.