JPS5938563B2 - Fiber cable for optical transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fiber cable for optical transmission. In particular, consideration has been given to prevent the fiber for optical transmission from being deformed or cut, and the structure is designed to prevent damage during the manufacturing process of the cable. be.

Figure 1 is a fiber cable for optical transmission that was already proposed by one of the inventors of the present invention, and is made by inserting an optical fiber strand f into a space b between protrusions 1 and 2 of a linear object a with a single-shaped cross section. A cross-sectional view is shown. In this case, protrusions 1, 2...
The entire body is a rigid body, which is twisted and stable at a certain pitch like a sticky candy.

That is, spaces b, c, d, . . . form a spiral space in the length direction. When forming such a rod-like object into a cable shape, it is difficult to process, that is, it is likely to become a polygon, and depending on the material, the cross-sectional structure may be deformed. The present invention has been improved in view of the above points.

The embodiment of the present invention shown in FIG. 2 will be described below. In the figure, reference numeral 3 denotes a linear object made of plastic or the like, and cavities 4 that open to the outside are provided at equal intervals on its outer periphery, and these cavities 4 are formed in a spiral shape in the axial direction of the linear object 3. In this cavity 4, one or more optical transmission fibers 5 (hereinafter referred to as optical fibers) are housed. The optical fiber 5 may be either the fiber itself or the surface of the fiber may be coated or coated with a reinforcing substance.

Reference numeral 6 denotes the opening of the cavity 4, which is generally desirably narrow.

This opening is an inevitable part when creating the cavity 4 with a linear material (for example, extruded plastic), and is an opening for dropping the fiber 5 from this part along its spiral. It is. FIG. 3 is an explanatory diagram of the cross-sectional shape of the cavity, and 4 is the cavity 4 of the embodiment shown in FIG.
It has a substantially circular cross-sectional shape, and the negative part is an opening.

Further, reference numeral 8 indicates a case where the cross-sectional shape is triangular, and the width becomes wider toward the center than the opening. Further, reference numeral 9 indicates a U-shaped cross-sectional shape, which has the same width as the width of the opening. Further, 10 indicates a rectangular cross-sectional shape and has the same width as the width of the opening. In any case, the characteristics are (i) the cross section of the linear object has a cavity in a shape that erodes a part of the original figure cross section (g) the shape of the hollow part in the cross section is the same as the original figure cross section In order to maintain the linkage of the wire as much as possible, and to maintain the cross-sectional structure of the linear object due to the hollow portion, it is necessary to maintain the cross-sectional structure of the wire to the extent that it does not weaken; generally, extrudable plastic material is used. In this case, it is empirically necessary that the ratio of the total cavity area in the cross section to the cross-sectional area of the linear object is not larger than 1:1.5.

Further, the linear object 3 has cavities 4 formed in a spiral shape at a predetermined pitch in the axial direction.

This can be easily made, for example, by rotating the die and point part of an extruder, and the method for inserting the optical fiber 5 into the cavity 4 can also be done by using a conventional twisting device or by slightly modifying it. This can be easily achieved by doing this. As described above, the cable of the present invention has the advantage that since the fiber 1 is placed in a cavity, no force is applied directly to the fiber 1 even when the cable is bent or pulled, so that the fiber 1 is less susceptible to damage. The cross-section of the linear object is such that a hollow part exists inside, and the cross-sectional shape of the hollow is 4, 8, and 8 in Fig. 3.
9 and 10, the cross-sectional width of the cavity is selected to be equal to or larger than the width of the opening, and the opening toward the outside is at least not wider than the inside. Since it can take any shape, for example, if the cross section of a linear object is circular, it is easy to manufacture it into a cable, and the ratio of the total cross-sectional area of the cavity to the cross-sectional area of the linear object is Since l: is not larger than 1.5, there is an advantage that there is no fear that the linear object will become soft due to the cavity.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional cable, FIG. 2 is a perspective view of the cable of the present invention, and FIG. 3 is an explanatory view showing various modifications of the same cavity. 3... Linear object, 4... Hollow, 5...
...Optical fiber, 6...Aperture, 8, 9, 1
0...Deformed cavity.

Claims (1)

[Claims] 1 Having an opening on the outer periphery of the linear object into which an optical transmission fiber can be inserted, and forming a cavity in which the optical transmission fiber is housed in a spiral shape at a predetermined pitch along the length of the linear object. The cross-sectional shape of the cavity is a groove having a width equal to or larger than the width of the opening, and the ratio of the total cross-sectional area of the cavity to the cross-sectional area of the linear object is 1.
: A fiber cable for optical transmission, characterized in that it is configured so as not to exceed 1.5.