JPS6057566B2 - Optical fiber flat cable with a twist and manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Background and Objectives An optical fiber flat cable is a tape-like or ribbon-like product in which a large number of optical fibers are arranged side by side and covered with a plastic coating all at once.

It has already been proposed to provide a twist around the cable centerline of this optical fiber flat cable in an attempt to improve its flexibility. Conventionally, optical fiber flat cables without twists were first made, and then the twists were added later.

Therefore, optical fibers placed away from the cable centerline have an increased probability of stretching and breaking. There is also a force that causes the stretched optical fiber to shrink. Therefore, buckling occurs when trying to give a short pitch twist. Therefore, twisted optical fiber flat cables made using conventional methods are weak in strength. It has also been reported that transmission loss increases compared to before twisting. An object of the present invention is to provide an optical fiber flat cable with a twist free from the above-mentioned problems and a method for manufacturing the same.

Summary of the Invention The first invention relates to a twisted optical fiber flat cable.

In this cable, the distance of each optical fiber from the cable center line is d1, and the length of the cable center line is L, so that no force acts on any of the optical fibers in the cable length direction. When, the length L(d) of each optical fiber
is now expressed as.

``The second invention relates to a manufacturing method thereof.

To always send out each optical fiber in a state where almost no tension is applied.

These are fed into a known flat cable forming device such as an extruder and collectively coated to form a flat cable. Immediately after leaving the forming device, the flat cable is given a twist, and then it is continuously pulled by a pulling machine consisting of rotating rollers and pinch rollers. In this way, the flat cable is delivered to the end of the take-off machine while maintaining its twisted shape and rotating around the cable center line. More Detailed Description "FIG. 1" is a plan view of the flat cable 10 with a twist.

Assuming that each optical fiber 12 can freely extend, the elongation rate of the optical fiber 12 at a distance d from the cable center line X is -.

However, p is the twist pitch. Note that the elongation rate refers to the ratio of the length of the optical fiber 12 stretched (length after twisting to length before twisting) to the length before twisting.

The length of the optical fiber 12 after being twisted can be considered in the same way as the length of each strand in a stranded wire.

Therefore, the above elongation rate formula is an application of the "twisting rate" formula for stranded wires (for example, Handbook of Electrical Engineering, Institute of Electrical Engineers of Japan, April 1930 edition, p. 6l3). Therefore, in the manufactured "twisted optical fiber flat cable", if each optical fiber 12 is lengthened by an amount equivalent to this elongation rate, no force will act on each optical fiber 12 in the cable length direction. .

That is, the length of the center line is L.

In this case, the length L(d) of the optical fiber 12 at a distance d from the distance d is sufficient.

Regarding the manufacturing method, the optical fibers 12 are arranged horizontally in one row and sent out as shown in "Fig. 2".

At this time, a slight reverse tension is applied to each optical fiber 12 so that a delivery reel (not shown) does not rotate too much, so that if the take-up force changes, the optical fiber 12 can be freely sent out. Reference numeral 14 denotes a known flat cable forming device, for example, a crosshead of an extruder.

Here, the flat cable 10 is formed by covering the optical fiber 12 with plastic all at once. Formation. A take-up machine 16 consisting of a rotating roller 20 driven by a motor 18 and a pinch roller 22 is provided at the far end of the roller 14 (rightward in FIG. 2). Then, the flat cable 10 immediately after coming out of the forming device 14 is twisted, for example, two to three times, and then inserted into the pulling machine 16 and continuously pulled.
In this way, the optical fibers 12 located away from the cable centerline x will naturally be drawn into the forming device 14 as many times as necessary and successively coated thereon.

Therefore, within the flat cable 10, no force acts on any of the optical fibers 12, especially in the cable length direction. Also, no distortion occurs. The flat cable 10 made in this way is twisted two to three times as described above, and then
6, during which time it cools down and is able to maintain its twisted shape.

Then, the flat cable 10 comes out of the pulling machine 16 while maintaining its twisted shape and rotating around the cable center line X, as shown in FIG. 3.

At this time, care must be taken because if the diameters of the rotating roller 20 and pinch roller 22 are too large or the pressure between them is too high, the twist that has been created will plastically deform again and become flat. be.

If the flat cables 10 that are twisted and sent out from the take-off machine 16 while rotating as described above are accumulated in some suitable form, a continuous "twisted optical fiber flat cable" can be obtained.

When winding this onto the winding bobbin 24 as shown in Figure 2, it is rotated by the same amount and in the same direction in accordance with the twist.

Therefore, for example, the winding bobbin 24 is attached to a ring-shaped rotating frame 26, and this is attached to a freely rotating support roller 28.
and placed on the drive roller 30 and rotated by the motor 32. "Figure 4" shows the flat cable forming device 14a
In this case, two known forming rolls are used.

Two tapes 11 are fed here, an optical fiber 12 is sandwiched between them, and the flat cable 10 is formed by integrating them by adhesion, heat fusion, adhesion, or the like. In this case as well, the flat cable 10 is twisted two to three times in the same manner as described above, and then put between the pulling machines 16 and taken off. Also, “Figure 5” is
This is the case when a known joining device is used as the flat cable forming device 14b.

The optical fiber 12 is covered with a coating 13 in advance and sent there, and the coatings 13 are integrated with each other by adhesion, welding, etc. to form the flat cable 10. Other details are the same as in the above case. Applications of the present invention A flat optical fiber cable in which one or more of the optical fibers 12 is replaced with a metal wire has already been proposed.

The present invention can be applied to such cables and their manufacture. Furthermore, as shown in FIG. 6, a cable 100 with a twist has been proposed, in which flat cables 10 are stacked in multiple stages to form a cable 100 that is sorted by adhesive or the like.

The present invention can also be applied to such cables and their manufacture. Example Doped quartz core (outer diameter 60 PTrl.), quartz cladding (outer diameter 150 μTrl.), six optical fibers with a diameter of 400 μm covered with a primary coat of silicone rubber were lined up, and nylon was coated all at once using an extruder. So, the thickness is 0.6T! It was a flat cable with a1 width of 2.6 m.

7. Connect the flat cable immediately after exiting the extruder crosshead.
Twist 200 (twice) and 400I on the other side of the crosshead.
Scissors in the pick-up machine installed at the r$& position, 107TL,
I was able to pull it off at Imin's speed. A flat cable with a twist pitch of 20'' was continuously obtained. In addition, in order to maintain this twist, the rotating frame 26 is
AνEf&/l& Todoroki ●! It was wound onto the bobbin 24 while rotating with υVHI-CVVRll.

The transmission characteristics of the flat cable with this twist are that the average of the six cables is 3.0 dB at a wavelength of 0.85 μml.
, the maximum was 3.2 dBI-, and the minimum was 2.7 dBIkm.

On the other hand, with conventional products (in which a normal flat cable is made and then a twist is added later), there is a particularly large increase in loss in the two fibers at the center of the cable.
What was 2.8dB1- before extrusion becomes 6.5dBI
km and 7.0dBIkfn. Furthermore, in terms of the strength of the optical fiber, as shown in Figure 7, not a single fiber was broken even at an elongation of 2.5%. On the other hand, in the conventional product, three of the six wires at the edges were disconnected. Effects (1) In the first invention, the actual length of each optical fiber becomes longer as it moves away from the center line, so by giving it a twist, there is almost no increase in transmission loss, and permanent strain can be reduced. Since it is not built-in, mechanical strength does not decrease.

(2) By the manufacturing method of the second invention, a homogeneous flat cable can be efficiently obtained.

[Brief explanation of the drawing]

The drawings relate to embodiments of the present invention, and Fig. 1 is a plan view of approximately 112 pitches, Fig. 2 is a schematic explanatory diagram of the equipment used to carry out the manufacturing method, and Fig. 3 is a flat diagram after passing through a pulling machine. An explanatory diagram of the state in which the cable maintains its twist and rotates around the center line, Figures 4 and 5 are explanatory diagrams of the means used in the flat forming process, and Figure 6 is a diagram of the cable being stacked in multiple stages. FIG. 7, a perspective view of the flat cable, is a tensile strength characteristic diagram. 10...Twisted optical fiber flat cable, 12...Optical fiber, 14, 14a,
14b...Flat cable forming device, 16.
... Entire collection machine, 20 ... Rotating roller, 22
...Zentirola.

Claims (1)

[Claims] 1. An optical fiber cable in which a plurality of optical fibers 12 are arranged horizontally and a common plastic coating is applied thereto is twisted around the cable center line x, and the cable of each optical fiber 12 is twisted around the cable center line x. When the distance from the center line x is d and the length of the cable center line x is L_o, the length L(d) of each optical fiber is L(d)=L_o√[1+4π^2(d/
An optical fiber flat cable with a twist, characterized in that it is shaped as shown in p)^2]. 2. The plurality of optical fibers 12 that are always sent out with almost no tension applied are arranged side by side and fed into the flat cable forming device 14 to form the flat cable 10, and the flat cable 10 immediately after coming out of the flat cable forming device 14 is After giving a twist to the
A method for manufacturing an optical fiber flat cable with a twist, which is characterized by continuous pulling by sandwiching the cable. 3. Twisted light according to claim 2, characterized in that the flat cable forming device 14 is a crosshead of an extruder, in which the plastic bulk coating is applied on the optical fiber 12. Method of manufacturing fiber flat cable. 4. Claim 2, characterized in that the flat cable forming device 14 consists of two forming rolls, in which the optical fiber is sandwiched between the two tapes 11 and integrated. A method for manufacturing optical fiber flat cables with a twist as described in . 5. The flat cable forming device 14 comprises a joining device, into which the optical fibers 12 covered with the coating 13 are fed, and are joined together and integrated. A method for manufacturing optical fiber flat cables with a twist.