JPH04115206A - Gripping method for optical fiber cord in optical fiber connection box - Google Patents

Abstract

PURPOSE:To increase a clamping force and also secure a slide which is necessary between tensile strength coated optical fibers by inserting the optical fiber cord into an arcuate slit formed in the surface of a rubbery elastic body clamp, and pressing the cord by a flat plate from above and clamping it when the optical fiber cord is drawn out of the optical fiber connection box. CONSTITUTION:The optical fiber cord 4 formed by providing a fibrous tensile strength body longitudinally along the periphery of coated optical fibers and providing a plastic jacket made of vinyl chloride resin, etc., thereupon is inserted into the arcuate slit 6 formed in the surface of the rubbery elastic body clamp 5, pressed by the flat plate 7 from above, and drawn out of the optical fiber connection box. Further, the slit 6 is 0.1mmphi less than the external diameter of the optical fiber cord jacket of, for example, 2.8mmphi and when the cord 4 is inserted into the slit 6, the optical fiber cord jacket protrudes from the surface of the cord clamp 5 by 0.1 - 0.2mm. Thus, pressure is applied to the entire periphery of the jacket of the cord 4. When the cord is clamped with screws 12, the cord 4 is not compressed, so there is no increase in transmission loss.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to fusion splicing or connector connection of an optical fiber core and an optical fiber cord in a junction box for terminating an optical cable mainly used for an optical transmission line. The present invention relates to a method of holding an optical fiber cord when pulling the optical fiber cord out of an optical fiber connection box.

(Prior Art) When an optical fiber core wire and an optical fiber cord are fused or connected with a connector and the optical fiber cord is pulled out from an optical fiber splicing box, the method of holding the optical fiber cord has conventionally been as follows. As shown in the figure, adhesive PVC tape 17 and self-fusing tape 18 are wrapped around the outer sheath of the optical fiber cord 4 and tightened with the cable connector 13, or (1) as shown in Figure 6, Peel off the outer sheath of the optical fiber cord for each fiber, (b) fold back the tensile strength material such as Kevlar, (c) cover it with a sleeve, and (d) apply adhesive and attach the sleeve and Kevlar etc. There was a method in which the tensile strength body and the optical fiber cord jacket were integrated, the cord processing was completed, and (e) the sleeve was hooked onto the banking for each fiber to be fixed and held.

(Problems to be Solved by the Invention) The conventional method of wrapping tape on the outer sheath of an optical fiber cord and tightening it with a cable connector has the following problems in the case of multiple fibers:
Code number is unclear, ■ Insufficient gripping force, ■ In some cases, it may be over tightened, causing an increase in transmission loss.

In addition, the method of inserting a sleeve into the optical fiber cord jacket for each fiber and integrating the tensile strength member such as Kevlar and the optical fiber cord jacket ends up integrating the optical fiber core with adhesive, which is not the case. Although it is possible to ease the tension on the optical fiber by providing slippage between the optical fiber and the tensile strength body, they become one piece and when tension is applied to the optical fiber cord jacket, the optical fiber is pulled. However, there were problems such as breakage of the optical fiber and increased loss.

(Means for Solving the Problems) That is, the present invention provides: (1) An optical fiber in which a fibrous tensile strength member is vertically attached around an optical fiber core, and a plastic jacket made of vinyl chloride resin or the like is provided thereon. In the cord gripping method, the optical fiber cord is inserted into an arcuate slit machined on the surface of the rubber-like elastic clamp, and a flat plate is pressed from above to grip the optical fiber cord, and optical fiber connections are made as necessary. This is a method for holding an optical fiber cord in an optical fiber junction box, which is pulled out from a box, and further includes: (1) the shape of the arcuate slit has a diameter slightly smaller than the outer diameter of the outer sheath of the optical fiber cord; Optical fiber connection with a shape that provides strong gripping force by shifting the center of the arcuate slit toward the flat plate within a range that does not apply pressure to the optical fiber core when the optical fiber cord is inserted and pressed with a flat plate. This is how to hold the optical fiber cord inside the box.

Next, the present invention will be specifically explained based on FIGS. 1 to 3.

The optical fiber cord used in the present invention is, for example, as shown in FIG. It has a structure in which a plastic outer cover 3 is provided.

FIG. 2 is a schematic diagram for explaining a method of holding an optical fiber cord when pulling it out from an optical fiber junction box according to the present invention.

FIG. 2-1 is a partially cutaway view showing a state in which the optical fiber cord 4 is pulled out and held from the optical fiber junction box;
FIG. 2-2 is a perspective view showing the distribution state of the cord clamp 5 provided in the optical fiber junction box and the slit 6 provided thereon, and FIG. 2-4 shows the flat plate 7 that presses the
Insert the 12-fiber optical fiber cord 4 into the slit 6,
The optical fiber 4 is pressed by the flat plate 7 and tightened by the screw 12.
FIG.

Moreover, FIG. 3 is a structural diagram of a cord clamp for 12 cores, and FIGS. 3-1 and 3-2 are its plan view and side view.

FIG. 4 is an enlarged view showing details of part A of the slit 6 shown in FIG. 3-2.

In FIG. 2, the optical fiber cord 4 is inserted into the slot of the cord clamp 5 installed on the inlet side of the optical fiber cord 4 in the optical fiber junction box 8 (FIG. 2-2),
The optical fiber cord 4 is held by the flat plate 7, tightened with the screw 12 (Fig. 2-3), and the optical fiber cord 4 is gripped as shown in Fig. 2-1.4.

Next, the structure of the cord clamp 5 will be explained based on FIGS. 3 and 4.

The cord clamp 5 shown in FIG. 3 is for 12 fibers, and is provided with 12 slits 6 of the same shape and size, 6 in the upper part and 6 in the lower part.

FIG. 4 is an enlarged detailed view of the slit 6 in section A shown in FIG. 3-2.

In FIG. 4, the slit 6 is 0.0 mm smaller than the outer diameter of the optical fiber cord jacket of, for example, 2.8 mm. When the lvtmφ is made smaller and the optical fiber cord 4 is inserted into the slit 6, the outer sheath of the optical fiber cord is 0.1 to 0.0 mm lower than the surface of the cord clamp 5. It is configured to protrude beyond 2M.

Since pressure is applied to the entire circumference of the optical fiber cord jacket in this way, a strong gripping force can be obtained.

In addition, when the optical fiber cord 4 is held down by the flat plate 7 and tightened with the screw 12, the optical fiber cord 4 is not compressed to less than φ2.6 am, so there is no increase in optical transmission loss, as shown in FIG. In addition, the necessary slippage between the tensile strength member 2 such as Kevlar and the optical fiber core 1 can be ensured.

The gripping force is 3 kgf or more on average, which is sufficient for this type of gripping force6.In addition, when the cord clamp 5 has 12 cores or less, the It is preferable that the cord clamp 5 is configured to be gripped by six pieces at the top and bottom. Furthermore, in the case of 12 or more fibers, the cord clamps 5' are stacked on the flat plate 7 shown in Figure 2-4, the flat plate 7' is placed, and the cord clamps 5'' and the flat plate 7' are placed in that order as necessary. and can be stacked.

(Effects of the Invention) As explained above, the present invention has a clamp structure in which pressure is applied to the entire circumference of the outer sheath of an optical fiber cord, so it is effective when used in fields such as securing optical fiber cords.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of an optical fiber cord used in the present invention. FIG. 2 is a schematic diagram for explaining a method of holding an optical fiber cord when pulling it out from an optical fiber junction box according to the present invention. FIG. 2-1 is a partially cutaway view showing a state in which the optical fiber cord is pulled out and held from the optical fiber connection box. FIG. 2-2 is a perspective view showing the distribution of the cord clamp provided in the optical fiber connection box and the slit provided thereon. FIGS. 2-3 are schematic diagrams showing a flat plate that presses an optical fiber cord inserted into a slit. FIG. 2-4 is a perspective view showing a state in which a 12-fiber optical fiber cord is inserted into a slit and held. FIG. 3 is a structural diagram of a cord clamp for 12 fibers. 2-1 and 2-2 are a plan view and a side view thereof. FIG. 4 is an enlarged view showing details of part A of the slit shown in FIG. 2-2. FIG. 5 is a partially cutaway schematic diagram showing a state in which a tape is wrapped around an optical fiber cord sheath of the prior art and tightened with a cable connector. FIG. 6 is a schematic diagram showing a procedure for covering the conventional optical fiber cord jacket with a sleeve and integrating the sleeve, the tensile strength member, and the cord jacket with an adhesive. 1: Optical fiber core 2: N male tensile strength body 3 Niblastic outer skin 4: Optical fiber cord 5: Cord clamp 6: Slit 7: Flat plate 8: Optical fiber junction box 9: Base 10: m 11: Wiring duct 12: Screw 13: Cable connector 14 Fiber cord collection part 15: Main box Main box bottom Two adhesive PVC tapes Two self-fusing tape: Fiber cord assembly Figure 2-1 Figure 4', Figure 2-2 Figure 3- Figure 1 Coffin Figure 3-2 Figure 4 Figure 5-1 Pattern Figure 5-2

Claims (2)

[Claims] (1) In a method of gripping an optical fiber cord, in which a fibrous tensile strength member is attached vertically around the optical fiber core wire, and a plastic jacket made of vinyl chloride resin or the like is provided on top of the fiber-like tensile strength member, a rubber-like elastic member is attached to the clamp surface. The optical fiber inside the optical fiber junction box is designed so that the optical fiber cord is inserted into the arc-shaped slit made by processing, the optical fiber cord is pressed from above with a flat plate, the optical fiber cord is gripped, and the optical fiber cord is pulled out from the optical fiber junction box as needed. How to hold fiber cord. (2) The shape of the arcuate slit has a diameter slightly smaller than the outer diameter of the jacket of the optical fiber cord, and when the optical fiber cord is inserted and pressed with a flat plate, pressure is not applied to the optical fiber core wire. 2. The method of holding an optical fiber cord in an optical fiber junction box according to claim 1, wherein the center of the arc-shaped slit is shifted toward the flat plate side within a range such that a strong holding force can be obtained.