JPH06258559A - Optical cable unit - Google Patents

Abstract

PURPOSE:To easily drop optical fiber units into grooves a high speed and to prevent the jump of the optical fibers out of these grooves by forming the straight grooves parallel with the axial line of a grooved spacer, specifying the ratio of the radius of curvature of the bottom of these grooves and the radius of the optical fiber units and applying retaining winding on the outer periphery of the grooved spacer. CONSTITUTION:The grooves of the optical cable unit formed by housing the optical fiber units 3 in the grooves 5 of the grooved spacer 4 are formed as the straight grooves 5 parallel with the axial line of the grooved spacer 4. The ratio r/R of the radius R of curvature of the bottoms of the grooves 5 and the radius (r) of the optical fiber units 3 is specified to 0.7 to 0.95 and the retaining winding 6 is applied on the outer periphery of the grooved spacer 4. The generation of an increase in transmission loss is further effectively suppressed if the ratio d/D of the outside diameter D of the grooved spacer 4 and the outside diameter (d) of the circumcircle of the optical fiber units 3 stored in the grooves is set in a 0.7 to 0.95 range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable unit using a grooved spacer.

[0002]

2. Description of the Related Art An optical cable unit using a grooved spacer is widely used in an optical composite overhead ground wire such as an optical fiber built-in overhead ground wire or an optical cable winding type overhead ground wire, or a general optical cable. As shown in FIG. 3, a conventional optical cable unit of this type has a structure in which a grooved spacer 1 having a spiral groove 2 on the outer circumference is used, and an optical fiber unit 3 is housed in the groove 2. There is.

In the case of an optical cable unit used for an optical composite overhead ground wire, the grooved spacer 1 is formed by forming a spiral groove 2 on an aluminum or aluminum alloy wire having an outer diameter of about 3 to 6 mm. The spiral pitch is about 100 to 300 mm.

In the case of manufacturing an optical cable unit as shown in FIG. 3, a grooved spacer is twisted to manufacture a grooved spacer having a spiral groove of a predetermined pitch, and then the optical fiber is formed in the groove. It is manufactured by dropping the unit.

[0005]

In the conventional optical cable unit of this type, since the groove of the grooved spacer has a spiral shape, it is necessary to drop the optical fiber unit accurately according to the spiral pitch. For this reason, manufacturing is difficult and not only the manufacturing speed cannot be increased, but also the drop pitch of the optical fiber unit and the spiral pitch of the groove deviate, and the optical fiber unit rides out of the groove, and defective products are likely to occur. There was a problem.

In addition, the grooved spacers need to be twisted at a predetermined pitch, and it is necessary to use an optical fiber unit longer than the length of the grooved spacers.

[0007]

The present invention provides an optical cable unit which solves the above problems.
In the optical cable unit in which the optical fiber unit is housed in the groove of the grooved spacer, the groove is a linear groove parallel to the axis of the grooved spacer, the radius of curvature R of the bottom of the groove and the optical fiber. The ratio r / R to the radius r of the unit is 0.7 to 0.95, and the outer circumference of the grooved spacer is press-wound.

[0008]

If the groove of the grooved spacer is linear, it is not necessary to rotate the optical fiber unit when the optical fiber unit is dropped, and the dropping can be performed very easily and at high speed. Further, it is possible to prevent the optical fiber from jumping out of the groove by pressing and winding.

When the groove is formed in a straight line, when the optical fiber unit is housed in the groove of the grooved spacer and then wound, an unreasonable force is applied to the optical fiber unit on the inside and outside of the bend, thereby increasing the transmission loss. This may occur, but this is because the ratio r / R of the radius of curvature R of the bottom of the groove and the radius r of the optical fiber unit is 0.7 to 0.95, and the degree of freedom is set for the optical fiber unit in the groove. You can avoid it by giving it. The ratio d / D of the outer diameter D of the grooved spacer and the outer diameter d of the circumscribed circle of the optical fiber unit housed in the groove
When the ratio is 0.7 to 0.95, the increase in transmission loss can be suppressed more effectively.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 show an embodiment of the present invention. This optical cable unit uses a grooved spacer 4 having a linear groove 5 extending in the longitudinal direction on the outer circumference. The optical fiber unit 3 is housed in the groove 5 of the grooved spacer 4, and a press winding 6 with tape is applied to the outer periphery of the grooved spacer 4 in order to prevent the optical fiber unit 3 from jumping out of the groove 4. . The method of winding the presser winding 6 is not particularly limited, and is coarse spiral winding in the illustrated example, but it may be dense spiral winding or intermittent annular winding.

When manufacturing the optical cable unit as described above, the optical fiber unit 3 is dropped into the linear groove 5 of the grooved spacer 4, the press winding 6 is wound, and then wound on a drum. There is a risk that the optical fiber units located inside and outside the bend will be overloaded and transmission loss will increase. Therefore, it was examined whether an increase in transmission loss can be avoided by changing the ratio of the radius of curvature R of the bottom of the groove 5 of the grooved spacer to the radius r of the optical fiber unit (see FIG. 1).

That is, various optical cable units having different r / R were manufactured, wound on a drum, the transmission loss was measured, and the occurrence of the increase in the transmission loss above the allowable value was investigated. The drum used has a small diameter of 200 to 600 mm, which is relatively easy to cause an increase in transmission loss. The winding length for each drum of each optical cable unit was 2000 m. The configuration of each optical cable unit is as shown in FIG. 1, the number of grooves 5 is 5, the number of optical fiber units 3 is 3, and the number of optical fibers of each optical fiber unit 3 is 6.
It is the heart. Therefore, the number of optical fibers in each optical cable unit is 18.

Table 1 shows the results of the above-described prototype test. ○ is 1
No increase in transmission loss occurred in 1 of 8 cores, △
Indicates that the transmission loss increased for only one core, and x indicates that the transmission loss increased for two or more cores.

[0014]

[Table 1]

From the above results, the value of r / R is 0.7-
It was found that the increase in the transmission loss of the optical fiber can be avoided by setting it within the range of 0.95. When the optical fiber with increased transmission loss was wound around the drum, about 67% were located inside the bend (drum barrel side) and about 33% were located outside the bend.

Next, with respect to the optical cable unit in which the value of r / R is set within the range of 0.7 to 0.95, the outer diameter D of the grooved spacer and the outside of the circumscribed circle of the optical fiber unit housed in the groove. It was investigated how the transmission loss increase changes when the ratio d / D with the diameter d (see FIG. 1) is changed. The results are shown in Table 2. The evaluation method is the same as in Table 1.

[0017]

[Table 2]

From the above results, the value of d / D is 0.7 to
It was found that setting within the range of 0.95 is effective in avoiding an increase in transmission loss of the optical fiber. When the optical fiber with increased transmission loss is wound on the drum, about 89 fibers are located inside the bend (drum body side).
%, And those located outside the bend were about 11%.

[0019]

As described above, in the optical cable unit according to the present invention, since the groove of the grooved spacer is straight, it is not necessary to twist the grooved spacer, and the cost of the grooved spacer is reduced. The optical fiber unit can be easily dropped into the groove and the manufacturing speed can be increased, the trouble that the optical fiber unit gets out of the groove can be eliminated and the defect rate can be reduced, and the length of the optical fiber unit can be equal to the length of the grooved spacer. Because it is good, it is possible to significantly reduce the cost. Even if the groove is straight, it is possible to prevent an increase in transmission loss of the optical fiber when wound on a drum.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an optical cable unit according to the present invention.

FIG. 2 is a perspective view of the optical cable unit of FIG.

FIG. 3 is a perspective view of a conventional optical cable unit.

[Explanation of symbols]

3: Optical fiber unit 4: Spacer with groove 5: Linear groove 6: Press winding R: Radius of curvature of bottom of groove r: Radius of optical fiber unit 3 D: Outer diameter of spacer 4 with groove d: Groove 5 Outer diameter of circumscribed circle of optical fiber unit 3 stored in

Claims (2)

[Claims] 1. An optical cable unit in which an optical fiber unit is housed in the groove of a grooved spacer, wherein the groove is a linear groove parallel to the axis of the grooved spacer, and the radius of curvature R of the bottom of the groove and the optical An optical cable unit characterized in that the ratio r / R to the radius r of the fiber unit is set to 0.7 to 0.95, and the outer circumference of the grooved spacer is pressed. 2. The optical cable unit according to claim 1, wherein the ratio d / D of the outer diameter D of the grooved spacer and the outer diameter d of the circumscribed circle of the optical fiber unit housed in the groove is 0.7 to 0. .9
It is characterized by having been set to 5.