JP2006330265A - Snow-measured optical drop cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drop cable in which icing is suppressed and the deterioration in transmission characteristic or break due to icing is prevented. <P>SOLUTION: Tension members 12 composed of plastic cords reinforced by aramid fiber are arranged on both sides of a coated optical fiber 11 with a space, both tension members and the coated optical fiber are covered with a protective layer 15 of low frictional flame-retardant polyethylen or polyurethane composition in a form of a circular or oval cross section, a supporting wire 13 is arranged on the extension line connecting the coated optical fiber 11 and the tension member 12 and outside of the protective layer 15, and the outer coating 16 is provided on the supporting wire 13 via a bridge 17 together with the protective coating 15. The long axis/short axis ratio of the protective layer 15 is 1 to 2, V-shaped recessed grooves 14 whose bottom is an arc and a small rounding is formed at the part where the valley face and the outer circumferential face intersect are provided on the surface of the protective layer, and the depth of the V-shaped recessed grooves and the radius of the bottom of the valley have prescribed dimensions, respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a snow-prevention optical drop cable that is drawn from an aerial optical transmission cable to a user's house via an intermediate optical drop closure (hereinafter simply referred to as an optical closure).

  As shown in FIG. 3, the aerial optical transmission cable 31 is routed to the utility pole 32 and the like, and is drawn into the user's home 33 via the optical closure 34. Between the optical closure 34 and the user's home 33, 2 is suspended on a support line of the optical drop cable 10 shown in FIG. 2, and the support line is fastened to a bracket (not shown) attached to the user's house 33, and then the support line and the optical cable main body 10a. And only the optical cable body 10a is drawn into the house.

  Here, the optical drop cable drawn into the user's house 33 from the optical closure 34 is outdoors, and when it is pulled down in a heavy snowy area, it will snow on the optical drop cable, and the snow quality / temperature will be reduced. Snow changes grow greatly due to changes and the like, and a large tension is applied due to the weight. As a result, the transmission characteristics of the optical drop cable may be deteriorated or disconnected.

  In view of the above situation, an object of the present invention is to provide an optical drop cable that suppresses snowfall on the optical drop cable and does not cause deterioration in transmission characteristics due to snowfall or disconnection.

  In order to solve the above-mentioned problems, the present invention is arranged such that tension members made of aramid fiber reinforced plastic strings are arranged on both sides of an optical fiber core, and low friction flame retardant polyethylene or low friction flame is placed on both. A protective coating having a circular cross section or an elliptical shape is applied with a flame retardant polyurethane composition, and a support wire is disposed on an extension line connecting the optical fiber core wire and the tension member and outside the protective coating. In an optical drop cable in which an outer jacket is provided together with the protective coating via a bridge, the ratio of the major axis / short axis of the protective coating is set to 1 to 2, and the optical fiber core wire and the tension member are connected. At the midpoint of the line, on the surface of the protective coating on the orthogonal line, the bottom of the valley has an arc shape, and a V-shaped concave groove is formed in the portion where the valley surface and the outer peripheral surface intersect. The depth of the V-shaped groove is 1/12 to 1/7 of the minor axis of the protective coating, the radius of the arc is 1/18 to 1/8 of the minor axis of the protective coating, A minute gap is provided between the protective coating and the protective coating.

  According to the present invention configured as described above, since the surface has a curved surface and is not angular, it does not adversely affect the transmission characteristics of the optical drop cable because it falls before the snow accretion grows greatly, and it is of course disconnected. There is no worry.

  In addition, since the protective coating and jacket are made of low-friction flame-retardant polyurethane, it is effective in preventing snow accretion, and in addition, a small gap is provided between the protective coating and the optical fiber core, so Even if there is snow in the interference state, the external pressure is not directly applied to the optical fiber core wire, and the effect of preventing the deterioration of the transmission characteristics can be obtained.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1A is a cross-sectional view of the optical drop cable 10 according to the first embodiment, in which 0.25 mmφ optical fiber cores 11 are juxtaposed, with a 0.6 mm interval on both sides, and a 0.45 mmφ diameter. A tension member 12 made of an aramid fiber reinforced plastic string is arranged in parallel, and a 1.2 mmφ galvanized steel wire 13 is arranged in parallel on an extension line connecting the tension member 12 and the optical fiber core wire 11. The outer cover 16 is integrally extruded through the bridge 17 together with the protective coating 15 by the composition. The low-friction flame-retardant polyurethane composition used had a hardness of 90 (HDA) or more and a friction coefficient of 0.2 or less with respect to vinyl chloride. Moreover, low friction flame-retardant polyethylene can be adopted instead of the low friction flame-retardant polyurethane composition.

  When the protective coating 15 is extruded, the nipple is slightly protruded from the front surface of the die, and a so-called pipe extrusion method is employed to adopt a small gap G (0... O) between the optical fiber core wire 11 and the protective coating 15. 5 mm or less). The protective coating 15 has a thickness of 0.8 mm and an outer diameter of 2.4 mmφ.

  The reason why the minute gap G is set to 0.5 mm or less is that if it exceeds 0.5 mm, the thickness of the valley bottom portion of the V-shaped groove of the protective coating 15 becomes thin, and the protective coating 15 may be buckled. .

  Further, in the longitudinal direction of the outer peripheral surface of the protective coating 15, a V-shaped concave groove 14 having a bottom surface with a radius of 0.2 mm and a depth of 0.3 mm is formed, and the bridge 17 has a height of 0.1 mm and a thickness. Is 0.2 mm, the thickness of the jacket 16 is 0.4 mm, and the outer diameter is 2.0 mmφ.

  In addition, the dimension of said each part in a present Example is a mere Example, and does not restrain a claim.

  FIG. 1B is a cross-sectional view of the optical drop cable 10 according to the second embodiment, in which optical fiber cores 11 of 0.25 mmφ are arranged in parallel, and 0.4 mm intervals are provided on both sides thereof. A tension member 12 made of an aramid fiber reinforced plastic string is arranged in parallel, and a 1.2 mmφ galvanized steel wire 13 is arranged in parallel on an extension line connecting the tension member 12 and the optical fiber core 11 and is bridged with a protective coating 15. The outer cover 16 is integrally extruded through 17.

  When the protective coating 15 is extruded, the nipple is slightly protruded from the front surface of the die, and a so-called pipe extrusion method is employed to adopt a small gap G (0... O) between the optical fiber core wire 11 and the protective coating 15. 5 mm or less). The protective coating 15 has a wall thickness of 0.8 mm on the long axis side and 0.6 mm on the short axis side, and an outer diameter of 2.4 mm on the long axis side and 2.0 mm on the short axis side. The reason why the minute gap G is set to 0.5 mm is the same reason as in the first embodiment.

  Further, in the longitudinal direction of the outer peripheral surface of the protective coating 15, a V-shaped concave groove 14 having a bottom surface with a radius of 0.2 mm and a depth of 0.3 mm is formed, and the bridge 17 has a height of 0.1 mm and a thickness. Is 0.2 mm, the thickness of the jacket 16 is 0.4 mm, and the outer diameter is 2.0 mmφ.

  In addition, the dimension of said each part in a present Example is a mere Example, and does not restrain a claim.

  FIG. 1C shows a third embodiment, in which 11 is a four-core optical fiber ribbon in which four optical fiber cores having an outer diameter of 0.25 mm are arranged in parallel, and 12 is an interval between both sides of the optical fiber ribbon. A tension member composed of 0.45 mmφ aramid fiber reinforced plastic cords arranged in an open manner, 13 is a 1.2 mmφ galvanized steel wire, and a short axis of 2.0 mm × long length by a low friction flame retardant polyurethane composition. An oval protective coating with a shaft of 4.0 mm and a jacket with an outer diameter of 2.0 mmφ are provided via a bridge 17.

  The protective coating 15 is formed by a pipe extrusion method, and a small gap G of 0.11 mm on the short axis side and 0.35 mm on the long axis side is formed between the optical fiber tape core wire 11 and the protective coating 15. A V-shaped concave groove 14 in which a valley bottom is formed in an arc shape in the length direction of the outer peripheral surface of the protective coating 15 and a minute radius R is formed at a portion where the valley surface and the outer peripheral surface intersect is provided. Here, the micro gap G can be expanded to 0.5 mm on both the short axis side and the long axis side. However, it is not preferable to extend beyond this for the same reason as in the first and second embodiments. Other than the above, the description is omitted because it is basically the same as the first and second embodiments.

  In addition, the dimension of said each part in a present Example is a mere Example, and does not restrain a claim.

  As described above, according to the present invention, the surface has a curved surface and is not angular, so that it does not adversely affect the transmission characteristics of the optical drop cable by falling before the snow accretion grows greatly, and of course the disconnection. There is no worry.

  In addition, since the protective coating and jacket are made of low-friction flame-retardant polyurethane, it is effective in preventing snow accretion, and in addition, a small gap is provided between the protective coating and the optical fiber core, so Even if there is snow in the interference state, the external pressure is not directly applied to the optical fiber core wire, and the effect of preventing the deterioration of the transmission characteristics can be obtained.

It is sectional drawing of the optical drop cable which concerns on this invention, (a) Example 1, (b) Example 2, (c) Example 3 Sectional view of a conventional optical drop cable Illustration of optical drop cable lead-in construction

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical drop cable 10a Optical cable main body 11 Optical fiber (tape) core wire 12 Tension member 13 Galvanized steel wire (support wire)
14 V-shaped groove 15 Protective coating 16 Jacket 17 Bridge 31 Overhead optical transmission cable 32 Telephone pole 33 User's house 34 Intermediate light drop closure 35 Wall surface

Claims (3)

  A tension member made of an aramid fiber reinforced plastic string is arranged on both sides of the optical fiber core, and a circular or elliptical cross section is formed on both sides by a low friction flame retardant polyethylene or a low friction flame retardant polyurethane composition. A support line is disposed on the extension line connecting the optical fiber core wire and the tension member, and on the outside of the protective cover, and the jacket is placed on the support line via the bridge. In the optical drop cable provided with the protective coating, the ratio of the long axis / short axis of the protective coating is 1 to 2, and the protection on the line orthogonal to the midpoint of the line connecting the optical fiber core wire and the tension member A snow-prevention optical drop cable, characterized in that a V-shaped concave groove having a circular arc is formed at a portion where a valley bottom has an arc shape and a valley surface and an outer peripheral surface intersect on a coated surface.   The depth of the V-shaped groove is 1/12 to 1/7 of the minor axis of the protective coating, and the radius of the arc is 1/18 to 1/8 of the minor axis of the protective coating. The snow drop optical drop cable according to claim 1.   3. The snow-preventing optical drop cable according to claim 1, wherein a minute gap is provided between the optical fiber core wire and the protective coating.

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