JPH026352A - Optical fiber resin coating method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical fiber resin coating method and apparatus for applying a resin coating to an optical fiber, and in particular, it improves manufacturability by uniformly applying a polymeric material.

This is to improve quality.

<Prior art> Optical glass fibers (hereinafter referred to as optical fibers) used as optical transmission media usually have a diameter of 150 μm.
In addition, since the material is brittle, scratches are likely to occur on its surface during manufacturing, cable production, or storage, and furthermore, these scratches become a source of stress concentration and can be exposed to external forces. It has the disadvantage that it easily breaks when force is applied. Therefore, it is extremely difficult to use optical fiber as it is as an optical transmission medium, so conventionally, the surface of optical fiber is coated with resin to make coated optical fiber, in order to maintain the initial strength immediately after manufacturing the optical fiber. It is designed to withstand long-term use.

The resin coating material used for this coated optical fiber is
For example, thermosetting resins such as silicone resins, urethane resins, and epoxy resins, ultraviolet curable resins such as epoxy acrylates, urethane acrylates, and polyester acrylates, and other polymeric materials such as radiation curable resins (hereinafter simply referred to as resins). ), but an example of the process of applying this resin to an optical fiber and curing it to form a No. 11 resin coating is shown in FIG.

As shown in FIG. 4, the optical fiber 3 formed by drawing the tip of the optical fiber preform 1 while heating and melting it in a heating furnace is formed by a first pressure die (hereinafter referred to as a pressure die) 4.
By being inserted into A, a resin as a coating material is applied to the outer circumferential surface of the optical fiber, and by further being inserted into a first curing furnace 5A, the applied resin is cured to form a single-layer coated optical fiber 6A. reactor. This first layer coated optical fiber 6
A is then inserted into the second pressurizing die 4B, a resin as a second layer of coating material is applied to its outer peripheral surface, and is further inserted into the second curing furnace 5B, thereby forming the 2rfJth m1ll. is cured to form a 2R coated optical fiber 6B. Then, the double-layer coated optical fiber 6B is wound up by a winding machine 8 via a capstan 7.

Here, FIG. 5 shows an example of a resin pressure supply device 9 that supplies resin at a certain pressure to the pressure dies 4A and 4B. As shown in the figure, the resin pressure supply device 9 is
A pressure adjustment system consisting of a pressurized tank 9a that stores llllo and a pressure reducing valve that adjusts the pressure inside this pressurized tank 9a by FA! 2! It has a resin supply pipe 9C that sends the resin lO in the pressure tank 9a to the pressure die 4A (or 4B), and the pressure! The resin in the pressure tank 9a is supplied to the pressure die 4A (or 4B) through the resin supply pipe 9C by the high pressure gas introduced into the pressure tank 9a via the 1g regulator 9b.

In the manufacturing process of such coated optical fibers, it is necessary to maintain a uniform coating diameter even when the drawing speed (hereinafter referred to as the drawing speed) changes when applying resin as a coating material. It is necessary to set the resin pressure within the dies 4A and 4B to an optimum value. Therefore, conventionally, the optimum pressure value is determined in advance through experiments, and the pressure die 4A (or 4B
Pressure die 4A (or 4B
) is used to control the supply pressure set by the pressure regulator 9b while monitoring the pressure within ), or to simply fix the supply pressure to an optimum value at the planned manufacturing linear speed. .

<Problems to be Solved by the Invention> However, as described above, when controlling the supply pressure of resin to the pressure die while monitoring the resin pressure in the die with a pressure sensor, it is necessary to control the pressure sensor in the die. Direct I
Maintenance is difficult because it has to come into contact with the N resin, and since it only monitors the pressure inside the die rather than the application state itself, it is difficult to maintain the N resin if its physical properties have changed from the original experiment. In some cases, there is a problem that the coating condition cannot be maintained well. On the other hand, if the supply pressure of resin to the pressure die is simply fixed, the equipment will be simple and maintenance will not be difficult, but the linear speed, physical properties of the resin, etc. will change. In this case, there is a problem that a good coating state cannot be maintained.

In view of these circumstances, it is an object of the present invention to provide a method and apparatus for coating an optical fiber with resin, which can maintain a good coating state even when the linear speed, physical properties of the resin, etc. change.

<Means for Solving the Problems> A method for manufacturing an optical fiber according to the present invention that achieves the above object includes applying a polymer material to the outer peripheral surface of an optical fiber obtained by heating and drawing an optical fiber base material using a pressure die. In an optical fiber resin coating method in which a coated optical fiber is manufactured by coating the polymer material and then curing the polymer material in a curing furnace, the brightness of the optical fiber immediately after the polymer material is applied is measured directly under the pressure die. The optical fiber resin coating device is characterized in that the pressure of the pressurizing die is controlled according to the measured value of the brightness, and the optical fiber resin coating device coats the outer periphery of the optical fiber obtained by heating and drawing the optical fiber base material. V! of an optical fiber that has a pressure die that applies a polymer material to the surface and a curing furnace that cures the polymer material applied by the pressure die. ! The oil coating equipment includes a brightness sensor that measures the brightness of the optical fiber immediately after coating the polymeric material directly below the pressure die, and a control that controls the pressure of the pressure die in accordance with the measured value by this brightness sensor. It is characterized by providing means.

The present invention is a novel technology in which the brightness of the optical fiber directly under the pressure die increases when the resin supply pressure to the pressure die changes during drawing and becomes too high or too low, resulting in poor coating conditions. This was done based on extensive knowledge. in this way,
The reason why the brightness of the optical fiber changes when the coating condition becomes poor is presumed to be due to the following principle.

As shown in FIG. 2, when the optical fiber preform 1 is heated and drawn in a heating furnace 2, it receives light from a heater in the furnace, and a portion of this light propagates through the drawn optical fiber 3.

On the other hand, when the optical fiber 3 is coated with the resin 10 in the pressurizing die 4, if the resin coating is in a good coating state, specifically, a uniform coating diameter is maintained and the damage in the applied resin coating is small, the die exit part The vibration of the optical fiber near E is very small, but if the resin pressure in the pressure die is not appropriate and the coating of the resin 10 is poor, the resin 10
The flow is unstable, and vibrations occur in the optical fiber 3 at the die exit portion E.

When vibration occurs in the optical fiber 3 in this way, it is expected that part of the light propagated through the optical fiber 3 from the heating furnace 2 will be scattered as described above, and as a result, the brightness of the optical fiber will increase. Ru.

That is, as shown in FIG. 3, when the resin pressure in the pressure die 4 is within the appropriate R range a and the coating state is maintained well, the brightness of the optical fiber directly under the pressure die is stable. However, if the resin pressure is in a low range or a high range C and the coating state becomes poor, the brightness of the optical fiber directly under the pressure die becomes high.

Preferred embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 shows the manufacturing process of a coated optical fiber equipped with a resin-coated lid for carrying out the method of the present invention. Note that the same members as in Fig. 4 are given the same reference numerals and redundant explanations are omitted. do.

As shown in FIG. 1, in this embodiment, the pressure die 4
A brightness sensor 11 is provided directly under each of A and 4B, and these brightness sensors 11 measure the brightness of the fiber directly under the die, and a calculation @112 is provided to control the resin pressure supply device 9 according to the measured value. ing.

In the resin coating apparatus of this embodiment, by measuring the brightness of the optical fiber immediately after resin coating, it is possible to judge whether the coating condition is good or bad and to maintain a good coating condition. So that the resin supply pressure can be maintained properly. That is, when it is determined that the brightness measurement value and the pressure change have shifted from the optimum range a to b or c shown in FIG. 3, the pressure regulator (see FIG. 5) of the resin pressure supply device 9 is controlled. so that the pressure falls within the optimum range a.

When the positive fM pressure within the pressure die is maintained within the optimum range in this manner, coating with a uniform diameter and small coating flaws can be performed, and the quality of the coated optical fiber is significantly improved.

Using the apparatus configured as described above, an optical fiber having a diameter of 125 μm was drawn using an optical fiber base material having a diameter of 35 μm, and a two-layer resin coating was performed. At this time, the drawing speed was set at 50 to 300 m/
The diameter of the optical fiber was changed over min.
25±0.3μm 11th layer resin coating diameter is 200±1μm
It was possible to obtain a coated optical fiber with a second layer resin coating diameter of 250±1 μm, which was in a very good coating state.

<Effects of the Invention> As explained above, according to the present invention, it is determined whether the coating condition is good by measuring the change in the brightness of the optical fiber directly under the pressure die, and the resin supply pressure is adjusted accordingly. Since the coating is properly controlled, a good coating condition is always maintained even when the linear speed changes or the physical properties of the resin change, which significantly improves the manufacturability and quality of optical fibers. be able to.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the manufacturing process of a coated optical fiber according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the principle of the present invention, and FIG.
The figure is a graph showing the relationship between press die pressure and fiber stiffness directly under the die, Figure 4 is an explanatory diagram showing the manufacturing process of a coated optical fiber according to the prior art, and Figure 5 is a diagram of the resin pressure supply device. FIG. 2 is a configuration diagram showing an example of a configuration. In the drawing, 1 is an optical fiber base material, 2 is a heating furnace, 3 is an optical fiber, 4A and 4B are pressure dies, 5A and 5B are curing furnaces, 6A is a single-layer coated optical fiber, and 6B is a double-layer coated light 9 is a resin pressure supply device, 11 is a brightness sensor, 12 is a performance! ! It is L-sized. Patent application agent Sumitomo Electric Industries Co., Ltd.

Claims (2)

[Claims] (1) A coated optical fiber is manufactured by applying a polymer material to the outer peripheral surface of the optical fiber obtained by heating and drawing an optical fiber base material using a pressure die, and then curing the polymer material in a curing furnace. In the method for coating an optical fiber with resin, the brightness of the optical fiber immediately after coating the polymeric material is measured immediately below the pressure die, and the pressure of the pressure die is controlled according to the measured value of the brightness. Characteristic resin coating method for optical fiber. (2) It has a pressurizing die that applies a polymeric material to the outer peripheral surface of the optical fiber obtained by heating and drawing an optical fiber base material, and a curing furnace that hardens the polymeric material applied by the pressurizing die. In an optical fiber resin coating device, a brightness sensor is installed directly below the pressure die to measure the brightness of the optical fiber immediately after coating the polymer material, and the pressure of the pressure die is controlled according to the measured value by this brightness sensor. What is claimed is: 1. A resin coating apparatus for an optical fiber, comprising: a control means for controlling an optical fiber;