Optical fiber cable

Abstract

An optical fiber cable includes: optical fiber units each comprising optical fibers, and twisted together in an SZ shape; a wrapping tube that wraps around the optical fiber units; fillings disposed inside the wrapping tube, wherein the fillings include at least one first filling and at least one second filling that are located between two adjacent optical fiber units; and a sheath that covers the wrapping tube. The first filling is in contact with the wrapping tube. The second filling is located more radially inward than the first filling in a radial direction.

1 . An optical fiber cable comprising:
 optical fiber units each comprising optical fibers, and twisted together in an SZ shape;   a wrapping tube that wraps around the optical fiber units;   fillings disposed inside the wrapping tube, wherein the fillings include at least one first filling and at least one second filling that are located between two adjacent optical fiber units; and   a sheath that covers the wrapping tube,   wherein   the first filling is in contact with the wrapping tube, and   the second filling is located more radially inward than the first filling in a radial direction.   
     
     
         2 . The optical fiber cable according to  claim 1 , wherein
 the optical fiber units include outer units that are disposed at an outermost layer of the optical fiber units, and   at least one of the fillings is disposed on a straight line passing through a cable central axis and a center point of one of the outer units, in a cross-sectional view.   
     
     
         3 . The optical fiber cable according to  claim 1 , wherein
 the optical fiber units include outer units that are disposed at an outermost layer of the optical fiber units, and   an outer layer filling density D represented by D=S÷(π×r 2   2 −π×r 1   2 ) satisfies 0.05 or more and 0.20 or less,   where r 1  is a distance between a radially inner end of the outer units and a cable central axis,   r 2  is a distance between a radially outer end of the outer units and the cable central axis, and   S is a sum of cross-sectional areas of parts of the fillings disposed in a region of which a distance from the cable central axis is in a range of r 1  to r 2 .   
     
     
         4 . The optical fiber cable according to  claim 1 , wherein
 the first filling and the second filling are disposed at equivalent positions in a circumferential direction around a cable central axis of the optical fiber cable.   
     
     
         5 . The optical fiber cable according to  claim 1 , wherein the fillings are fibrous material. 
     
     
         6 . The optical fiber cable according to  claim 1 , wherein
 the optical fiber units have binding materials wound around the optical fibers, and   the optical fibers are partially exposed from a gap between the binding materials.   
     
     
         7 . The optical fiber cable according to  claim 1 , wherein
 the optical fiber units are disposed so as to form separated layers that include an outermost layer and a layer positioned inside of the outermost layer, and   the first filling and the second filling are disposed between the two adjacent optical fiber units in the outermost layer.   
     
     
         8 . The optical fiber cable according to  claim 7 , wherein
 the second filling is not in contact with the three or more optical fiber units positioned in the outermost layer.   
     
     
         9 . The optical fiber cable according to  claim 1 , wherein
 the first filling and the second filling are twisted in an SZ shape together with the optical fiber units positioned in an outermost layer.   
     
     
         10 . The optical fiber cable according to  claim 1 , wherein
 the optical fiber units include outer units that are disposed at an outermost layer of the optical fiber units,   at least one of the fillings is disposed on a straight line passing through a cable central axis and a center point of one of the outer units, in a cross-sectional view, and   in a cross-sectional view, at least one of the fillings is positioned inside a recessed portion that is formed in a radially outer edge of one of the outer units, and at least one of the fillings is sandwiched between one of the outer units in which the recessed portion is formed and the wrapping tube.   
     
     
         11 . The optical fiber cable according to  claim 3 , wherein
 the outer layer filling density D represented by D=S÷(π×r 2   2 −π×r 1   2 ) satisfies 0.05≤D≤0.10.