JPH06317720A - Method for connecting coated optical fiber ribbon - Google Patents

Abstract

PURPOSE:To prevent the decrease of the radius of curvature of fibers to a prescribed value or below by fitting and positioning the fusion connected fibers into the grooves of hot melt reinforcing sheets provided with bent grooves and heating the fibers in this state by holding and heating the fibers with both the front and rear hot melt reinforcing sheets, thereby fixing the fibers. CONSTITUTION:At least one of the hot melt reinforcing sheets are provided with the many grooves g of the prescribed bend and the surfaces thereof are formed as fused layers for fusion by heating. The pitch P1 at the left end of the grooves g is equal to the pitch of the high density coated optical fiber ribbon A and the pitch P2 at the right end is equal to the pitch of the low- density coated optical fiber ribbon B. The fusion connected fibers 1 are fitted into the grooves g of the hot melt reinforcing sheet and another hot melt reinforcing sheet is superposed thereon to hold the fibers. These sheets are heated to fuse the fibers. As a result, the fibers 1 are fixed while the prescribed bent is maintained by both hot melt reinforcing sheets, by which the fibers are protected and reinforced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fusion splicing fibers of optical fiber ribbons having different pitches, and reliability of strength at a connecting end of fibers of optical fiber ribbons having a small pitch. It is possible to improve the property.

[0002]

2. Description of the Related Art In order to fusion splice fibers of an optical fiber ribbon, the coating of the optical fiber ribbon is removed,
A fiber of a predetermined length is exposed, its tip is cut linearly to align the end faces, and the fibers of both optical fiber tape cores are butted and fused together. Then, the exposed fiber and the fusion spliced portion are covered with a reinforcing tube for protection (see FIG. 5). When the pitches of both optical fiber tape cores to be connected are equal, the exposed parts of the fibers are parallel to each other, so there is no problem of strength due to bending, but when connecting optical fiber tape cores with different pitches (see FIG. 4). )
, The fiber 1 of the optical fiber ribbon A having a small pitch is opened in a fan shape, and therefore is bent to form a bend 2 (see FIG. 4), resulting in the above-mentioned problem of strength due to the bend. The symbol B is an optical fiber tape core wire having a large pitch. That is, although the allowable elongation required for the fiber is about 0.25%, the above-mentioned bending is not uniform and changes depending on the handling after connection. If the maximum elongation of the fiber due to this bending exceeds this allowable limit, the strength reliability of the fiber will be extremely lowered, and eventually the optical fiber ribbon may be damaged and the transmission efficiency may be remarkably lowered. Fibers that are fusion-spliced and opened in a fan shape are more likely to bend and increase in curvature when a compressive force in the longitudinal direction is applied (so-called buckling occurs), and the limit may be exceeded soon.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to reliably prevent the minimum radius of curvature of the bending of a fan-shaped fiber of the fusion splicing part from exceeding a predetermined safety curvature.

[0004]

[Means for Solving the Problems] The measures taken to solve the above problems are constituted by the following elements (a) and (b). (A) Fitted and temporarily fixed by fitting the fusion-spliced fiber in the groove of the grooved hot melt reinforcing sheet guided so as to be bent in a safe curvature within a predetermined range, and (b) hot melt of the front and back. A fiber is sandwiched by a reinforcing sheet, and both the front and back hot melt reinforcing sheets are heated and fused to each other to protect and reinforce the fusion-bonded fibers. In addition, the above-mentioned "safe curvature within a predetermined range" means a bending curvature within a range in which the elongation of the fiber caused by bending becomes 0.25% or less. Although its specific value varies depending on the fiber wire diameter, it cannot be determined unconditionally, but in order to guarantee sufficient fatigue strength, it is necessary for the fiber having a wire diameter of 125 μm to have a minimum radius of curvature of 25 mm or more.

[0005]

[Operation] When multi-core fusion splicing is performed, for optical fiber tape core wires with a small pitch, the tip of the fiber is fitted into the V groove of the V-groove fixing jig of the fusion splicing device, and the whole is fanned out. Fixed. At this time, the bending of the V-shaped groove of the fixing jig is within a range that does not impair the reliability of fiber strength. Since the fibers fused in this manner have a bend that is substantially the same as the bend of the V groove of the fixing jig, in this state the fibers are fitted into the grooves of the grooved hot melt reinforcing sheet and positioned, Both hot-melt reinforcing sheets are sandwiched and temporarily fixed, and then the hot-melt reinforcing sheets are heated and fixed to each other. As a result, the fiber is fixed to the hot melt reinforcing sheet while keeping the bend with a safe curvature below a predetermined value, and is protected and reinforced by the hot melt reinforcing sheet. Therefore, it is possible to reliably prevent the radius of curvature of the fiber from falling below a predetermined value.

[0006]

EXAMPLES Next, examples will be described with reference to FIGS. 1, 2 and 3. A large number of grooves g having a predetermined bend are provided on at least one side of the hot-melt reinforcing sheet 10, and the surface of this hot-melt reinforcing sheet is a fusion layer for heat fusion. The pitch P _{1 at} the left end of the groove is equal to the pitch of the high density optical fiber ribbon (see optical fiber ribbon A in FIG. 4), and the pitch P _{2 at} the right end is the low density optical fiber ribbon (see FIG. 4 of the optical fiber tape core wire B)). For example, as shown in FIG. 4, the fiber 1 fusion-spliced is replaced by the hot-melt reinforcing sheet 1
Another hot melt reinforced sheet 11 that fits in the groove of 0
Are piled up and sandwiched by both hot-melt reinforcing sheets 10 and 11, and these are heated and fused. As a result, the fiber 1 is fixed to both the hot melt reinforcing sheets 10 and 11 while keeping a predetermined bend, and is protected and reinforced by the both hot melt reinforcing sheets 10 and 11.

[0007]

[Effect] The invention which solves the above-mentioned problems of the present invention is not known. Therefore, since the subject of the present invention is novel, solving the subject and solving the above-mentioned problems in the prior art is an effect peculiar to the present invention. That is, the fusion-spliced fiber is fitted and positioned in the groove of the hot melt reinforcing sheet provided with the curved groove, and in that state, it is tentatively fixed by sandwiching both front and back hot melt reinforcing sheets, and in this state both hot melt By heating the reinforcing sheets and fixing them to each other, the fibers are fixed to the hot melt reinforcing sheet while maintaining a bend with a curvature less than a predetermined value, protected by the hot melt reinforcing sheet, and reinforced, so that they are maintained as they are. It Therefore,
It is possible to reliably prevent the radius of curvature of the fiber from becoming a predetermined value or less. As for the fiber of an ordinary high-density optical fiber tape, the reliability of strength can be sufficiently secured by setting the minimum radius of curvature of the bent portion to 25 mm or more. Therefore, the minimum radius of curvature of the groove of the hot melt reinforcing sheet is By setting the length to 25 mm or more, it is possible to deal with various fusion-spliced fibers.

[Brief description of drawings]

FIG. 1 is a plan view of a hot melt reinforcing sheet used in an example of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a cross-sectional view of an embodiment in which the fibers of the optical fiber tape are sandwiched and fixed by the front and back hot melt reinforcing sheets of the present invention.

FIG. 4 is a schematic view of a fusion splicing state of optical fiber tape core wires having different pitches.

FIG. 5 is a schematic diagram of a conventional fusion splicing procedure for optical fiber ribbons.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fiber 2 ... Bending of fiber 10 ... Hot-melt reinforcing sheet with groove 11 ... Hot-melt reinforcing sheet A ... Optical fiber tape core wire with small pitch (high density) B ... optical fiber ribbon g · · · groove P ₁ of the pitch larger (low density), P ₂ ··· pitch

Claims (1)

[Claims] 1. A hot melt reinforcing sheet having front and back sides, which is fitted and temporarily fixed in a groove of a grooved hot melt reinforcing sheet which is guided so as to be bent at a safe curvature within a predetermined range. A method of splicing a fiber with a sheet, heating both front and back hot melt reinforcing sheets to fuse them to each other to protect the fusion-spliced fibers, and connecting the reinforced optical fiber tape cores.