JPH04172403A - Method of feeding optical fiber into narrow duct - Google Patents

Abstract

PURPOSE:To feed optical fiber into a narrow duct while giving enough sag but less excessive stress to the fiber by using a pneumatic type optical fiber feeding device of a second one and thereafter as a substance to bring in the optical fiber from the direction crossing with the optical fiber feeding direction. CONSTITUTION:When an optical fiber 11 emitted from an outlet portion 31a has sagged enough, the tip of the fiber 11 is introduced into an inlet 21b of a second pneumatic type optical fiber feeding device 13b, passed through a gas seal portion 23b and fed into a narrow duct 15b by means of a veer-out structure 19b, while compressed gas is supplied from a supply outlet 17b. Because the optical fiber 11 is brought into the second device 13b from the direction crossing with the feeding direction of the optical fiber 11, the fiber 11 is fed into the duct 15b smoothly and fed out from the outlet end 31b without being subject to a bent of a small curvature. The fiber 11 is successively fed into the divided narrow duct by handling the fiber 11 in the same manner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for feeding a continuous optical fiber into a plurality of narrow diameter conduits arranged in series in the longitudinal direction.

[Conventional technology and its issues]

As a method of feeding an optical fiber into a small diameter pipe, there is a method of feeding compressed gas from one end of the small diameter pipe. As a conventional example of an apparatus for realizing this method, the one shown in FIG. 3 from Japanese Patent Application Laid-Open No. 59-104607 is known.

In the figure, 11 is an optical fiber, 13 is a pneumatic optical fiber feeding device, and 15 is a small diameter conduit. 17 is a compressed gas supply port of the pneumatic optical fiber feeding device 13, 19 is an optical fiber feeding mechanism, 21 is an optical fiber inlet,
23 is a gas seal portion, and 25 is an outlet of the optical fiber.

The optical fiber 11 passes through the gas seal section 23 and is sent out by the sending mechanism 19. On the other hand, compressed gas is supplied from the supply port 17 by a compressor or a high-pressure gas cylinder (not shown). Then, the optical fiber 11 is fed into the narrow diameter pipe 15 by a hydrodynamic force acting between the optical fiber 11 and the compressed gas flowing inside the small diameter pipe 15. At this time, the flow rate of the compressed gas flowing through the narrow diameter pipe 15 needs to be faster than the delivery rate of the optical fiber 11. However, since a frictional force acts on the compressed gas with the inner surface of the small diameter pipe 15, when the pressure is constant, the flow velocity of the compressed gas becomes slower as the pipe length becomes longer. It may become impossible to maintain the feed speed. When the pipe length is long, the flow rate of the compressed gas can be maintained by increasing the pressure of the compressed gas, but the maximum pressure is limited by the pressure resistance strength of the pipe.

Therefore, in practice, there is a limit to the length to which an optical fiber can be continuously fed.

For this purpose, the small-diameter pipes are divided and provided so as to be continuous in the longitudinal direction, and a pneumatic optical fiber feeding device is placed at the inlet end of each small-diameter pipe, and a continuous optical fiber is sequentially inserted into the air as described above. A method of feeding with a feeding type optical fiber feeding device has been proposed (Japanese Patent Laid-Open No. 2-210306).

However, in this method, when feeding optical fibers into a plurality of narrow-diameter pipes laid in the longitudinal direction, it is necessary to match the feeding speeds of the plurality of pneumatic optical fiber feeding devices, which is extremely difficult to adjust. If the feeding speeds of the pneumatic optical fiber feeding devices do not match, a tensile or compressive force will act on the optical fiber, damaging the optical fiber.

For this reason, before introducing the optical fiber sent out from each small-diameter pipe into the next pneumatic optical fiber feeding device, the optical fiber is taken out in the horizontal direction to take up sufficient slack, and the amount of slack is increased or decreased. One possible method is to adjust the sending speed of the feeding type optical fiber feeding device.

However, in many places where such work is performed, space is limited, such as manholes, and as with conventional pneumatic optical fiber feeders, it is necessary to connect the optical fiber from the inlet 21 to the outlet 2.
In the case where up to 5 (small diameter conduit connection part) are straight, the optical fiber is bent with a small curvature near the entrance of the optical fiber, and there is a risk of damaging the optical fiber.

[Means for solving problems and their effects]

The present invention provides a method for introducing an optical fiber into a small-diameter conduit that solves the above-mentioned problems, and the structure is such that a continuous optical fiber is fed into a narrow-diameter conduit that is divided into a plurality of parts in the longitudinal direction. In the method, a pneumatic optical fiber feeding device is installed at the entrance end of each divided small diameter pipe, and a second
The following pneumatic optical fiber feeding devices are characterized by using a device in which the optical fiber is introduced from a direction intersecting the feeding direction of the optical fiber.

In the present invention, as the second and subsequent pneumatic optical fiber feeding devices, a device in which the optical fiber is introduced from a direction intersecting the feeding direction of the optical fiber is used because the light emitted from each small diameter pipe is This is to prevent the optical fiber from being bent with a small curvature by introducing the fiber into the next pneumatic optical fiber feeder from a direction that intersects the direction in which the optical fiber is sent out.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the method for feeding an optical fiber into a small diameter pipe according to the present invention, and FIG. 2 shows an example of a pneumatic optical fiber feeding device used in the present invention. Components having the same functions as those in FIG. 3 are given the same reference numerals.

In this embodiment, when feeding a continuous optical fiber 11 into a plurality of small diameter pipes 15a, 15b, 15c, etc. divided in the longitudinal direction, the entrance of the first small diameter pipe 15a is At the end is the same pneumatic fiber feeding device 1 as before.
3a, and the second and subsequent small diameter pipes 15b, tSC
-... The pneumatic optical fiber feeding devices 13b, 13C... installed at the entrance end of the optical fiber feeder 13b, 13C... A device having an inlet 21b for introduction is used.

The optical fiber 11 enters from the entrance 21a of the first pneumatic optical fiber feeding device 13a, and passes through the gas sealing section 23.
a, and is sent out by the sending mechanism 19a.

On the other hand, compressed gas is supplied from the supply port 17a by a compressor or a high-pressure gas cylinder (not shown).

Then, the optical fiber 11 is fed into the small diameter pipe 15a by a hydrodynamic force acting between the optical fiber 11 and the compressed gas flowing in the small diameter pipe 15a, and is sent out from the outlet end 31a.

When the optical fiber 11 that has been sent out has become sufficiently slack, its tip is introduced into the inlet 21b of the second pneumatic optical fiber feeding device 13b, passes through the gas sealing part 23b, and is opened into a small diameter pipe by the feeding mechanism 19b. Send it to 15b. On the other hand, compressed gas is supplied from the supply port 17b.

The second pneumatic optical fiber feeding device 13b introduces the optical fiber 11 from a direction intersecting the feeding direction of the optical fiber 11, so that the optical fiber 11 smoothly has a small diameter without being bent by a small curvature. It is fed into the pipe line 15b and sent out from the outlet end 31b. below,
By similar operations, the optical fibers II are sequentially fed into the divided narrow diameter pipes.

According to this feeding method, the optical fiber fed out from the outlet end of the small-diameter conduit can have sufficient slack, and can cross the feeding direction of the optical fiber of the next pneumatic optical fiber feeding device. Since the optical fiber is introduced from this direction, it is possible to prevent the optical fiber from being bent with a small curvature.

In the above embodiment, the pneumatic optical fiber feeding devices 13b, 13C, . The pneumatic optical fiber feeding device used for this purpose is not limited to this, and the operation and effect will be the same even if you use one that has an entrance in a direction that crosses the optical fiber feeding direction from the right, left, or above. be.

Further, although FIG. 2 shows the case where the angle of the optical fiber introducing direction with respect to the optical fiber sending direction is 90'', this angle can be selected to be an appropriate value around 90°.

Further, in the above embodiment, the first pneumatic fiber feeding device 13a is the same as the conventional one, but the present invention is not limited to this, and the first pneumatic fiber feeding device 13a is Any type of pneumatic fiber delivery device may be used.

C) Effects of the invention) As explained above, the present invention installs a pneumatic optical fiber feeding device at the entrance end of each divided small diameter pipe, and the second and subsequent pneumatic optical fiber feeding devices Since we use a device in which the optical fiber is introduced from a direction that intersects with the direction in which the optical fiber is sent out, when the optical fiber sent out from each small diameter pipe is introduced into the next pneumatic optical fiber feeding device, , it is possible to prevent the optical fiber from being bent with a small curvature, and it is possible to safely feed the optical fiber into a small diameter conduit.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an example of the method for feeding optical fiber into a small diameter pipe according to the present invention, and Figure 2 is a sectional view showing an example of a pneumatic optical fiber feeding device used in the method. -3 is a sectional view of a conventional pneumatic optical fiber feeder. 11: Optical fibers 13a, 13b, 13c: Pneumatic optical fiber feeding device 15a, 15b, 15c: Small diameter pipe line

Claims (1)

[Claims] 1. In a method of feeding a continuous optical fiber into a narrow diameter pipe line divided into a plurality of parts in the longitudinal direction, a pneumatic optical fiber feeding device is installed at the entrance end of each divided narrow diameter pipe line, A method for feeding an optical fiber into a small diameter conduit, characterized in that the second and subsequent pneumatic fiber feeding devices are devices that introduce the optical fiber from a direction intersecting the feeding direction of the optical fiber.