Optical fiber cable

Abstract

An optical fiber cable is constituted by a cylindrical spacer having on its surface helical grooves reversing their direction at a given pitch in which a stack of ribbon optical fibers is received. In the optical fiber cable, the reverse angle ø of the groove is 210°≦ø≦330°; the groove has a size to contain a virtual circle therein whose diameter D is represented by equation of D=(W2+(N·T)2)½ where W is the width of the ribbon optical fiber, T is the thickness of the ribbon optical fiber, and N is the number of the ribbon optical fibers stacked in a groove; the angle θ formed between each of side walls of the groove and a line connecting the center of the bottom of the groove and the center of the spacer varies periodically; and the angle θ of the side wall on the inner side of the curvature of the center of the groove increases continuously and monotonously at least over the part extending from a position distant from a helical portion between adjacent reverse portions at approximately 90° in a circumferential direction to the next reverse portion.

Dependencies are inferred from the claim text.