Optical fiber cable having fluted strength member core

Claim 1

An optical fiber cable, which comprises: a plurality of optical fibers; a fluted member which provides suitable tensile and compressive strength for the cable and which comprises a plurality of ribs extending radially from a central portion of said fluted member to provide a plurality of grooves each of which is disposed between two adjacent ribs with said optical fibers being disposed in said grooves, the ratio of the diameter of a circle that passes through outer ends of said ribs to the diameter of a circle that passes through the inverts of the grooves not exceeding a predetermined value which is sufficiently low to provide stability for said ribs and which is sufficiently high to cooperate with the spacing between adjacent ribs to allow a plurality of said optical fibers to be disposed in each groove and to be capable of longitudinal and transverse movement therein, further, the width of each rib as measured along the periphery of the circle that passes through the inverts of the grooves being substantially greater than the width of said each rib as measured along the periphery of the circle that passes through the outer ends of the ribs and being sufficient in value to strengthen and prevent rupture of each rib at its juncture with said central portion of said fluted member; and a sheath system which encloses said fluted member.