JP4891205B2 - Optical fiber cord and wiring method - Google Patents

Description

  The present invention relates to an optical fiber cord and a wiring method for wiring an optical fiber for communication freely in a house.

  In Japan, public communication using optical fibers has become popular in recent years, and optical fiber wiring in the house has become common.

FIG. 6 is a cross-sectional view of an optical fiber cord called an optical indoor cable. Reference numeral 1 denotes an optical fiber core, which is an optical fiber 1-1 made of quartz glass and coated with a synthetic resin, and a single mode fiber is generally used as the type of optical fiber. However, in a normal single mode fiber, if a tight bend is applied, light leaks and becomes a loss, so the bend radius is limited. Until recently, the tolerance of the bending radius was usually 30 mm. As the reinforcing material 3 ′, a steel wire or a wire material in which aramid fibers are hardened with an epoxy resin is applied. These are manufactured by batch-coating with polyethylene as the protective member 2 ′.
Conventionally, in wiring that crosses indoor corners (edges) and entering corners, optical fiber cords (those used for in-home wiring are also called indoor cables) are floated from the walls and pillars so that the bending radius increases. There was a need. Such a wiring configuration has an aesthetic problem and a problem that the optical fiber cord is easily caught and broken.

  In recent years, single-mode fibers, which are less likely to cause loss even when bent, have become widespread, and the allowable value of the bending radius can be set to 15 mm or 10 mm, so that the wiring at the exit and entry corners can be made less noticeable. As an example of the technique, for example, Non-Patent Document 1 shown below describes the structure of FIG. 6 with two cores.

  Recently, an optical fiber called a hole assist type fiber (simply called a holey fiber) has been developed, and if this is applied, no loss occurs even when the bending radius is 5 mm or less. It became easy to make close wiring to the. FIG. 7 shows a cross-sectional structure of this hole assist type fiber. A hole 1-1-3 is formed in the cladding 1-1-1 around the core 1-1-2 to enhance light confinement. However, the structure shown in FIG. 6 is not suitable for tightly bent wiring because the rigidity of the reinforcing material is too large, and a loose-type cord with a round cross section is used for this fiber. This technique is described in Patent Document 1 shown below.

Recently, an optical fiber called nanoStructures ^TM fiber has been recently announced by Corning, USA. This optical fiber is described in, for example, Non-Patent Document 2 below.

JP 2005-345805 "Optical fiber cord" Terasawa et al., “Single-mode optical fiber for small-diameter bending access”, SEI Technical Review, No.163, September 2003. US magazine FORTUNE, August, 6, 2007 article "Bend It Like Corning" (http://www.corning.com/docs/corporate/media_center/69738_E_Print_R1.pdf)

  In this way, optical fibers that are less prone to light loss due to bending have been developed, but if optical fibers made of glass are left with tight bends, fine scratches on the surface will grow and become long-term. Since it breaks, there is a limit to the allowable bending radius. With respect to the hole assist type fiber, bending loss is not a problem, but this mechanical strength is a limitation when the bending radius is reduced.

  Wiring that passes through sash windows, indoor doors, and sliding doors has continuous corners and corners, and the gap is narrow, so there is no space for optical fibers to escape. FIG. 8 shows an example of a cross-sectional structure of the sash door. The number written represents the dimensions, and the unit is mm. Therefore, since the fiber sandwiched between the fibers is tightly bent as shown in the figure, it has been considered that wiring is difficult even if any optical fiber is used.

  The present invention has been made in view of the above circumstances, and an object thereof is to easily implement optical fiber wiring through doors, sliding doors, and windows, which has been difficult until now.

  In order to achieve this object, in the present invention, a hole assist type fiber is used as an optical fiber, and this optical fiber is not perpendicular to the ridge line of the protruding corner, but is crossed with an angle of a specific value or less. is there. For this purpose, the optical fiber cord has a tape shape with a thickness of 1.5 mm or less. To maintain the bending shape and to prevent side pressure, both sides of the optical fiber are vertically attached with metal wires that are easily plastically deformed. Into a tape shape. A guide line is displayed on the surface of the optical fiber cord so that the inclination can be easily set at the time of operation so that the cable can be wired at an appropriate angle. It should be noted that the metal wire can be omitted or a synthetic resin having a higher elastic modulus than that of the coating can be used for wiring where the external pressure and impact are not easily applied.

  As described above, the present invention enables optical wiring that passes through windows, sliding doors, and indoor doors, which has been difficult until now, and allows the wiring work to be easily performed. This can greatly contribute to the further spread of future optical broadband services based on in-home optical wiring.

  Embodiments of the present invention will be described below with reference to the drawings.

ただし、t₁はエッジ表面から光ファイバ中心軸までの距離である。光ファイバは被覆されているため、t₁は有限の大きさを持つ。被覆が全く無い極限条件では、t₁はファイバ半径となる。光ファイバをこのエッジの稜線に直角に沿わせたとき（θ=90°）、曲げ半径はr+ t₁となる。 FIG. 1 is a diagram showing the principle of the present invention. The upper left in the figure shows the shape of the protruding corner (edge) as a model. If a sharp edge is enlarged, its tip is rounded and can be approximated by a cylinder. At this time, when the optical fiber is inclined at an angle θ from the ridge line at the edge tip of the curvature radius r, the curvature radius ρ of the optical fiber itself can be obtained by the following equation.

Here, t ₁ is the distance from the edge surface to the optical fiber central axis. Since the optical fiber is coated, t ₁ has a finite size. In extreme conditions with no coating at all, t ₁ is the fiber radius. When the optical fiber is perpendicular to the edge of this edge (θ = 90 °), the bending radius is r + t ₁ .

The graph shown in FIG. 2 is the result of calculating the bending radius of the optical fiber when the optical fiber is obliquely along the edge ridgeline. As shown in FIG. 1, θ on the horizontal axis is an angle formed with the ridge line. In the figure, the case where r + t ₁ is 0.25 mm, 0.5 mm, and 1.0 mm is shown. From this, it can be seen that as θ decreases, the bending radius of the optical fiber increases remarkably. Therefore, even if the edge is sharp, long-term reliability can be maintained by wiring the optical fiber with a small θ. This is the principle of the present invention. Since the bending radius of the optical fiber as r + t ₁ is increased becomes larger, less likely to break.

  In the case of a holey fiber with an outer diameter (cladding diameter) of 125 μm, the allowable bending radius is about 2.5 mm, and for a holey fiber with an outer diameter of 80 μm, the allowable bending radius is about 1.6 mm. Yes. The mechanical long-term reliability of optical fibers subjected to tight bending is described in detail, for example, in the following document.

また、きつい曲げ状態を保持することも一般的には容易ではないため、塑性変形しやすい金属、たとえば銅、アルミニウム、黄銅などを、補強材に採用する。これにより、曲げ形状が保持されることになる。また、この補強材を光ファイバ心線径よりも太くしておくことにより、外側から力が加わった場合にも、光ファイバ心線にその力が働かないように保護することができる。 Masao Tachikura, "Improved theoretical estimation of mechanical reliability of optical fibers", Proceedings of SPIE, Volume 5623, January, 2005. "
Next, the value to be taken of θ will be described. If the outer diameter (cladding diameter) of the optical fiber is d, the allowable bending radius ρ _min can be roughly expressed by ρ _min = 20d. Therefore, θ should be set so as to satisfy the following expression.

In addition, since it is generally not easy to maintain a tight bending state, a metal that is easily plastically deformed, such as copper, aluminum, brass, or the like, is employed as the reinforcing material. As a result, the bent shape is maintained. Further, by making the reinforcing material thicker than the diameter of the optical fiber core wire, even when a force is applied from the outside, it can be protected so that the force does not act on the optical fiber core wire.

  Even if the angle θ is determined in the design, the work using the protractor in the actual work is troublesome. Therefore, in the present invention, a line or pattern whose angle is known is displayed on the outer surface of the optical fiber cord.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

  3A and 3B are diagrams showing an embodiment of the present invention. FIG. 3A is a diagram showing the structure, and FIG. 3B is a diagram showing a cross section taken along the line AA ′ of FIG. In these figures, the optical fiber core wire 1 of a hole assist type fiber is sandwich-fixed with a double-sided adhesive tape together with a reinforcing material 3, and a protective sheet 2-1 is attached to the upper surface. The optical fiber core wires coming out from both ends are covered with a core wire protection tube 5 and a connector plug 6 is attached to the end portion. The connector plug is used to connect to an optical cord wired in the room, but is not necessary when connecting by fusion splicing or mechanical splice.

  At the time of wiring work, the release paper 4 on the lower surface is peeled off, and the adhesive surface is attached to the location where wiring is desired. The release paper is not necessarily paper, but may be a synthetic resin sheet. As the material of the protective sheet, for example, polyester-based or polypropylene-based synthetic paper is suitable. This is a white or semi-transparent milky white by creating micro holes in the resin, etc. so that it can be used as a substitute for paper, and surface-treated to make printing easier. It is. By this surface treatment, usually, the adhesiveness with the pressure-sensitive adhesive is increased and long-term reliability is obtained. There is a commercial product with a thickness of about 0.1mm, which is not easily damaged. Synthetic paper includes a product in which a synthetic resin cloth is bonded to improve the tear strength, and these are also applicable. The resin cloth alone may be used as a protective sheet.

  A stripe pattern is printed on the protective sheet 2-1 on the upper surface of the cord so as to form a specific angle θ with respect to the axis of the cord. If wiring is made to a frame such as an open / close door, a sliding door, or a sash window so that the stripe line is vertical, the work can be easily performed without checking the angle with a protractor or the like.

  The adhesive layer can be formed using a commercially available double-sided tape. The adhesive layer preferably has a high adhesive force, but it is also important that it is flexible. This is because if the rigidity is large, the bending rigidity at the time of bonding becomes high, and it becomes difficult to form a tight bending shape. In this respect, a type in which an adhesive is applied to both surfaces of the foamable substrate is preferable. Typical examples of this substrate include acrylic foam and urethane foam. A dense one is preferred.

  The reinforcing member has a round cross-sectional shape in the figure, but may be rectangular. The role of the reinforcing material is to protect the core wire from external pressure and impact from the upper surface and to easily maintain the bent wiring shape. Therefore, the reinforcing material is preferably an incompressible material having a thickness (thickness in the case of a reinforcing material having a rectangular cross section) equal to or greater than that of the optical fiber core wire. The requirement to hold the bent wiring is not present in the conventional optical cord or optical cable. By using copper wire, aluminum wire, nickel wire, or alloy wires (brass wire, nichrome wire, etc.) as the reinforcing material, it will be plastically deformed and maintain its shape during tight bending. There are easy advantages. This shape retention force can be made appropriate by selecting the thickness of the reinforcing material. If a steel wire or the like that is unlikely to be plastically deformed is applied as in the prior art, not only is wiring difficult, but the force to return straight after wiring continues, and there is a risk of the adhesive surface peeling off. . Therefore, there is a great merit in applying a metal having strong plasticity.

  In many cases, a sash window or the like has a structure in which the door does not directly hit the window frame when opening and closing. For example, the door collides with a buffer member attached to a part of the window frame, and there is no worry of external pressure or impact if wiring is avoided. In such wiring applications, the need to use a metal wire as a reinforcing material is small, and therefore it is possible to omit the metal wire or substitute a synthetic resin wire having a higher elastic modulus than the batch coating resin. In that case, since the bending rigidity of the optical fiber cord itself is significantly reduced, wiring work is facilitated. The synthetic resin reinforcing material has low rigidity and has a characteristic of gradually relieving stress in a bent state. Therefore, there is no fear of delamination induction like a steel wire, and a certain amount of reinforcing effect against external pressure can be expected.

Next, how to determine the angle of the guide line displayed on the protective sheet will be described.
FIG. 4 is a diagram illustrating a result of calculating the upper limit of θ with respect to r + t ₁ when the outer diameter d of the optical fiber is 125 μm and 80 μm using the equation (2). d is generally 125 μm, but recently, products adopting a dimension of 80 μm are also applied to some products. In this embodiment, both dimensions are included. Further, d is preferably as d is less likely to cause breakage due to bending, and the case where it is smaller than 80 μm is also included in the present invention.

In the prototype shown in the example, t ₁ corresponds to the thickness of the adhesive layer on the lower surface side and was 0.4 mm. Next, r is an industrial product, and the corners touched by hands are rounded for safety, and r is at least 0.3 mm. Therefore, the lower limit of r + t ₁ is expected to be 0.7 mm. At this time, as can be seen from the figure, the upper limit value of θ is slightly over 30 ° when the optical fiber outer diameter is φ125 μm and slightly over 40 ° when φ80 μm. Therefore, in this example, long-term reliability can be guaranteed by setting the angle of the guide line displayed on the protective sheet to 30 ° when the optical fiber outer diameter is 125 μm and 40 ° when the optical fiber is 80 μm. .

  In the embodiment shown in FIG. 3, the number of optical fibers to be accommodated is one, but a plurality of fibers may be used. FIG. 5 shows a cross-sectional shape of another embodiment. FIG. 5A shows a configuration in which two optical fiber cores are arranged between reinforcing members, and FIG. 5B shows a configuration in which one reinforcing material is arranged between two optical fiber cores. Thus, it is not necessary to have a relationship between the number of optical fiber cores and the number of reinforcing members. The number of cores and the reinforcing material may be arbitrarily increased as necessary. Increasing the number of reinforcing materials is effective when it is desired to secure the shape retention force while suppressing the thickness.

  5A, 5B, and 5C show other embodiments corresponding to FIG. 3B, respectively. FIG. 5C shows an example in which the optical fiber core wire is converted to a tape core wire by the tape core wire coating 7. It is also possible to use a 4-core tape or an 8-core tape. In this case, in the case where the optical cord for indoor wiring to be connected is the same tape core wire, a multi-fiber connector such as an MT connector or an MPO connector is effective as the connector. On the other hand, for the purpose of branching into a plurality of indoor wiring cords, it is possible to have a structure in which a single core connector plug is attached by separating the tape into a single core. In the case of 2-core, a commercially available connector for 2-core batch connection called MT-RJ connector can also be applied.

  The wiring method of the present invention is not necessarily applied only to the optical fiber cord having the structure given in the embodiment. An optical fiber cord having a diameter or thickness of 1.5 mm or less and incorporating a hole assist type fiber can be implemented only by fixing the wiring. For fixing the wiring, an adhesive typified by an instantaneous adhesive, a pressure-sensitive adhesive typified by a double-sided tape, a cover with a pressure-sensitive adhesive tape from above can be applied.

In the embodiments of the present invention, the optical fiber has been described as a hole assist type fiber, but recently, an optical fiber called nanoStructures ^™ fiber shown in Non-Patent Document 2 has recently been announced by Corning, USA. This is also included in the hole-assisted fiber in principle, although there are differences in the number of fine holes around the core and a large number of manufacturing methods, and in the manufacturing method. The embodiment of the present invention includes a hole having the structure shown in FIG. This includes not only the assist type fiber but also those to which the above optical fiber is applied.

FIG. 2 is an explanatory diagram of the principle of the present invention. The figure which shows the example of calculation which shows the effect of this invention. FIG. 3 is a structural diagram in an embodiment of the present invention. The figure which shows the example of calculation for design of wiring angle (theta). The figure which shows the cross-sectional shape of the other Example of this invention. Sectional drawing which shows the structure of the conventional indoor optical cable. Sectional drawing which shows the structure of a typical hole assist type | mold fiber. The figure which shows the example of the cross-section of a sash door.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical fiber core wire, 1-1 ... Optical fiber, 1-1-1 ... Cladding part, 1-1-2 ... Core, 1-1-3 ... Hole, 2, 2 '... Optical fiber protection member, 2-1 ... Protective sheet, 2-2 ... Adhesive layer, 3, 3 '... Reinforcing material, 4 ... Release paper, 5 ... Core wire protection tube, 6 ... Connector plug, 7 ... Tape core wire coating.

Claims (5)

It is a tape-shaped optical fiber cord with a thickness of 1.5 mm or less, and the core wire of a single-core or multiple-core hole-assist fiber, and the diameter or thickness of the optical fiber cord is equal to or greater than that of the optical fiber core wire and is plastically deformed Easy-to-use metal wires are arranged in a line in the cross-sectional width direction, one side is a protective sheet with adhesive, the other side is release paper with adhesive, and is bonded and fixed in a sandwich shape with adhesive. The wire has an extra length, and both ends thereof are outside the protective sheet. The radius of curvature of the hole assist fiber is r, and the distance from the edge surface of the hole assist fiber to the central axis is t _1. The optical fiber cord is characterized in that a straight line or a pattern indicating an angle θ satisfying the following formula is displayed on the protective sheet.

  2. The optical fiber cord according to claim 1, wherein a metal wire is omitted, or a synthetic resin wire having a higher elastic modulus than the coated thermoplastic resin is incorporated instead.   3. The optical fiber cord according to claim 1, wherein a clad diameter of the built-in single-core or plural-core hole assist type fiber is approximately 80 [mu] m or less. The optical fiber wiring method for the optical fiber cord according to any one of claims 1 to 3 , wherein after the release paper is peeled off, the fixed wiring is performed with an angle θ satisfying the above expression with respect to the ridgeline of the protruding corner. Optical fiber cord wiring method. According to claim 4, characterized in that the diameter or thickness incorporates a hole-assisted fiber is an optical fiber cord is 1.5mm or less, to secure the wiring with a said angle θ satisfying the expression for ridge external corner An optical fiber cord wiring method.

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