US 4,844,575 A · Optical fiber cable

Abstract

An optical fiber cable (20) includes a core (21) comprising at least one optical fiber (24) which is enclosed in a tubular member (34) and which includes a sheath system (40). The sheath system includes two strength members 42--42 which extend linearly longitudinally along the cable parallel to a longitudinal axis (29) of the cable. The strength members are enclosed in a plastic jacket (46). The strength members have predetermined relative tensile and compressive stiffnesses. The stiffnesses are such that the strength members are capable of withstanding expected compressive as well as tensile loading and are coupled sufficiently to the jacket to provide a composite arrangement which is effective to inhibit contraction and which controls the position of the neutral axis during bending while providing suitable flexibility. The strength members in a preferred embodiment are made of a metallic material such as steel and have tensile and compressive stiffness which are substantially equal to cause the plane of bending to extend through the strength members. In other embodiments, the core is filled with a waterblocking material, the tubular member is enclosed by a water absorbent tape and/or a metallic shield and metallic conductors may extend colinearly with the strength members.

Claims21

Dependent claims

An optical fiber cable, which comprises:

a core comprising at least one optical fiber;
a tubular member which encloses said core;
a jacket which is made of a plastic material and which encloses said tubular member;
and
a strength member system which is held adjacent to said tubular member by said jacket and which is substantially embedded in said jacket, said strength member system comprising two diametrically opposed linear members extending parallel to a longitudinal axis of the cable and being coupled to said jacket without necessarily being coupled to said tubular member, the strength members being positioned and having relative tensile and compressive stiffnesses which are predetermined to control the location of the neutral axis of the cable in bending, with the compressive stiffness of the strength members and the coupling thereof to the jacket being sufficient to provide a composite which is effective to inhibit substantially contraction of said cable.

2 more elements

The cable of claim 14, wherein said waterblocking material is a composition of matter which comprises:

(a) 77 to 95% by weight of an oil selected from the group consisting of
i. paraffinic oil having a minimum specific gravity of about 0.86 and a pour point less than -4.degree. C. and being of ASTM type 103, 104A or 104B;
ii. naphthenic oil having a minimum specific gravity of about 0.86 and a pour point less than -4.degree. C. and being of ASTM type 103,104A or 104B;
and
iii. polybutene oil having a minimum specific gravity of about 0.83 and a pour point less than 18.degree. C.;
and
iv. any mixture thereof;
and
(b) 2 to 15% by weight of hydrophobic fumed silica colloidal particles.

6 more elements

Dependencies are inferred from the claim text.

Optical fiber cable

Life of this patent

Optical fiber cable

Life of this patent

Abstract

Claims21