JPS60170811A - Optical fiber cable - Google Patents

Abstract

PURPOSE:To obtain an optical fiber cable which does not have any increase in light loss due to the disorder of arrangement of optical fibers by providing a layer of specific consistent material on a cable core composed of numbers of optical fibers and holding the fibers fixed or semifixed. CONSTITUTION:Eight optical fiber units 11 each formed by stranding six optical fibers around a tension member are stranded around another tension member 12 to form a cable core 1; and a layer 2 which is made of a hydrophobic consistent material whose mixing worked penetration measured at room temperature by ASTM D-217 is 85-475 and at least 1mm. thick is provided on the additional winding part of the cable core 1 and a consistent material of the same kind is c charged between the units and tension member 12 and among the units. A water shield layer 3 and a protection sheath 4 are provided on the layer 2. Consequently, the optical fiber cable which does not have any increase in light loss due to the disorder of arrangement of the optical fibers is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an improvement in an optical fiber cable having a structure in which a cable core is constructed using a large number of optical fibers and a protective sheath is provided thereon.

[Prior art]

``Distribution cables are subjected to various external forces during the manufacturing process and installation process, and these external forces may cause bends or microhends in some optical fibers in the core, reducing optical signal transmission characteristics, or water may enter after installation. There are problems such as long-term deterioration of the optical fiber.

In order to improve this problem, the present invention contemplates the use of ASTM I) on a cable core consisting of multiple optical fibers.
He invented an optical fiber cable comprising at least 11 layers of viscous material with a mixing consistency of 85 to 475 at room temperature measured at -217, and filed a patent application (Japanese Patent Application No. 1977, 1977). issue).

However, when the above-mentioned optical fiber cable is subjected to repeated stress, the cable core or optical fiber can move relatively freely in the layer made of the above-mentioned viscous material, so the arrangement of the cable core or optical fiber is disturbed and the cable core ( A phenomenon in which optical fibers) cross each other occurs,
It was found that the optical loss of optical fiber increases.

[Disclosure of the invention]

The present invention provides a new optical fiber cable in which such a phenomenon does not occur, and therefore, there is no increase in optical loss of the optical fiber. This optical fiber cable is provided with a layer made of a viscous material having a mixing consistency of 85 to 475 at a temperature of 100.degree. C., in which the optical fibers are substantially fixed or semi-fixed.

There is no particular restriction on the means for fixing or semi-fixing the optical fiber in the present invention, and the method is such that the arrangement of the optical fiber is not disturbed or the optical fiber is fixed by a means that does not substantially move through the layer made of viscous material. (Preferably, means for fixing the optical fiber unit to the outer periphery of the tension member is taken. Examples of such fixing means include:
Examples include methods exemplified in the embodiments shown in FIGS. 1 and 2, which will be described later.

[Disclosure of the present invention based on examples]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, where l is a cable core, and eight units of an optical fiber unit 11 formed by twisting six optical fibers around a tensilon member are connected to another cable core. The tension member 12 has a structure in which, for example, rubber or plastic insulated steel strands are twisted together. 2 is a layer of viscous material provided on top of the cable core 1, the thickness of which is typically at least l mu.

Generally, the cable core 1 has a chrysanthemum-like unevenness on its outermost periphery, so in the present invention, the thickness of the viscous material layer 2 is set at the top of the chrysanthemum-like protrusion of the cable core, as shown in FIG. Let the thickness t be measured from .

As a viscous substance, + measured by ASTM D-217
Those with a mixing consistency at P m of 85 to 475 are used,
Various inorganic or organic substances may be used as the constituent material of layer 2, regardless of their chemical structure, as long as they have the above-mentioned mixing consistency. In particular, a hydrophobic organic viscous substance is used as a constituent material of the layer 2, and as shown in FIG. 1, between the units 11 of the cable core 1,
If the gap between the unit 11 and the tension member 12 and the space inside the unit 11 are filled with the same hydrophobic viscous material as the layer 2 constituent material or the same type of hydrophobic viscous substance, even if water intrudes from outside the cable, Another advantage is that it prevents the water from migrating within the cable. Examples of the hydrophobic viscous substance having the above-mentioned mixing consistency include greases, such as polyurea grease,
One example is the lithium stone Kengris.

In FIG. 1, reference numeral 5 denotes a restraining winding portion, which fixes the optical fiber unit. As the restraining portion, cloth, Teflon, nylon mylar, cheesecloth (adhesive) tape, string, etc. are used. It is preferable to provide a gap (preferably a gap of at least 5%) sufficient for the viscous substance to pass through in the restraining winding portion. For that purpose, perforated tape (opening ratio 5~
9%) is preferably used.

In FIG. 1, numeral 3 is a water-blocking layer formed by vertically applying a metal laminate tape and positioned in close contact with layer 2, and 4 is a protective sheath made of rubber or plastic.

FIG. 2 is a sectional view of another embodiment of the present invention.

In the actual h8I example, instead of excluding the restraining winding part 5 in the embodiment shown in FIG. 1, an adhesive layer 6 was provided around the outer periphery of the tension member 12, and the optical fiber unit 11 was fixed on this adhesive layer. It is something.

(Experiment example) (A 12-core Gl type fiber core wire with core diameter/fiber diameter = 50/125 μm was twisted on a tension member of a steel coated wire of at 2.6 m and φ with a pinch of 150 mm, and then 2 17 pieces of dragon φ net-like 0.1+u” cloth tape
After 3-gap winding, filling with urea grease filler (containing modified starch), and longitudinally attaching A1 laminate tape, the polyethylene jacket was extruded to produce a cable with an outer diameter of 13 amφ. [Invention (a)] fb) A thermoplastic resin layer of 0.5 mmt is applied on the tension member of the steel coated wire of 2.6 length φ, and a GL type of core diameter/fiber diameter −50/125 μm is applied on top of the tension member. The fiber core wire is twisted with a 12-fiber pinch 1501, and then a urea grease filling (including modified starch) is filled on top of it, and A
After applying I-laminate tape vertically, the polyethylene jacket was extruded to create a cable with an outer diameter of 13111φ.

[Invention (b)] fcl The same cable as the invention +al was produced except that the net-like cloth tape was not wrapped. [Comparative Example] An ironing test was conducted by passing the cables of the invention 1al and +b+ and the cable of the comparative example through a metal wheel of 138 dragon diameter 5 times at a straining length of 1.5 m and a tension of 100 kg, and the results are shown below. Shown in the table. The table value is the average value of the results conducted with N=3, and is also the sum of the loss increases of 12 cores.

table

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention. FIG. 2 is a sectional view of another embodiment of the present invention. 1.-Cable core made up of a unit 11 that collects a large number of optical fibers 2-Viscous substance layer 3-Water-blocking layer 4...-Protective sheath 5-Pressure winding section 6-Adhesive layer 12-Tension Member Patent Applicant Dainichi Nippon Electric Cable Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) A cable core consisting of multiple optical fibers has a mixing consistency of 8 at room temperature measured by ASTM D-217.
An optical fiber cable comprising a layer of 5 to 475 viscous substances, in which the optical fiber is substantially fixed or semi-fixed. +21 Claim No. +l) in which the Hikari 7 AIHA unit is fixed or semi-fixed to the outer periphery of the tension member
Fiber optic cable as described in section.