JPH043843B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a plastic optical fiber light guide used as an optical transmission path for various sensors, light guides, and the like.

(Prior art) Plastic optical fibers are drawn during the manufacturing process, so when they are heated, they expand in the diameter direction, and when they are heated to the point that their end faces are melted, they become smooth when they are cooled. be.

Taking advantage of these characteristics, it is possible to fix the cylindrical body called a ferrule or the like fitted to the end of a plastic optical fiber and finish the end surface.
This method is known from Japanese Patent Laid-Open Nos. 57-181513 and 58-187903, which were proposed by the present applicant.

(Problems to be Solved by the Invention) Among the methods described above, the present invention proposes that heating the plastic optical fiber at a high temperature and without contact with a mirror surface, etc. shortens processing time and prevents staining of the end face. The present invention was completed by paying attention to the fact that this method is effective for treatment, and further examining the treatment conditions.

(Means for Solving the Problems) That is, the gist of the present invention is to fit a plastic optical fiber into a cylindrical body made of a heat-resistant material so that its tip faces the effective surface of the cylindrical body, This is a method of manufacturing a light guide by finishing this effective surface with high heat, and the contact temperature with heat is 300℃ to 700℃.
℃, the cylinder with its effective surface facing upward and the flame emitted downward are moved relative to each other for a time that does not cause foaming due to thermal decomposition of the optical fiber core material, thereby causing light to be emitted. A method for manufacturing a light guide, which is characterized by enlarging the fiber in the diameter direction and mirror-finishing the end face.

The manufacturing method of the present application having the above configuration operates and functions as follows.

When a flame is shot downward onto the upper surface of a plastic optical fiber that is fitted into a cylinder made of heat-resistant material and its tip faces the effective surface of the cylinder, the contact temperature with the heat increases from 300℃ to 700℃. Become. As it softens, the optical fiber expands in diameter. Although the temperature will be high,
Since the optical fiber and the flame move relative to each other, foaming due to thermal decomposition does not occur in the optical fiber core material.

Dirt such as soot from the flames flows downward, but
Since it is scattered upward along with light high-temperature gas, it is possible to produce a light guide with a beautiful mirror finish in a short time without being contaminated by flame soot, and the cylindrical body is firmly fixed.

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

FIG. 1 shows an outline of the method of the present invention using flame as a heat source, in which 1 is a plastic optical fiber, 2 is a cylinder made of a heat-resistant material, 3 is a flame, 4 is a nozzle in a flame generator, 5 is a gas supply pipe.

Among these, the plastic optical fiber 1 used includes one in which the core material is made of acrylic resin and the sheath material made of fluorine-containing resin, and one in which the core material is made of styrene resin and the sheath material is made of acrylic resin, but of course it is limited to these. Not done. Further, the cylindrical body 2 made of a heat-resistant material is made of metal such as brass or stainless steel, or ceramic.

Further, the flame generator in this case is not particularly limited, but it is preferable to use a high-temperature, clean oxyhydrogen flame generator.

The present invention is a method for manufacturing a light guide using such an apparatus, in which the cylindrical body 2 made of a heat-resistant material and the flame 3 are connected at a position where the contact temperature of the heat, that is, the flame in this case, is 300°C or higher. The process is characterized in that the process is performed by moving the optical fibers 1 and 2 relative to each other for a period of time that does not cause foaming due to thermal decomposition of the core material of the optical fiber 1.

That is, first, as shown in FIG. 2A, the optical fiber 1 is fitted into the cylindrical body 2 made of a heat-resistant material. At this time, the protective material 12 is removed from the tip of the optical fiber 1, and
The fitted tips are made to slightly protrude from the effective surface 21 of the cylinder body 2. In order to maintain this state, it is best to apply adhesive or swage it in place.
Note that 22 in the figure is a cutout portion provided on the effective surface 21 side.

Next, as shown in Figure 1, flame 3 is emitted from nozzle 4.
The cylindrical body 2 is turned upward and moved in the direction of arrow a for a short time with respect to the flame which is now directed downward. At this time, the flame 3 and the cylindrical body 2 are placed at a position where the contact temperature of the flame 3 is 300°C or higher. In addition, the temperature at this time is 300
If the temperature is less than 0.degree. C., not only the processing time cannot be shortened, but also defects such as stains due to contact with the flame 3 are likely to occur. By the way, in the case of optical fiber 1 whose core material is acrylic resin and sheath material is made of fluorine-containing resin,
It is best to do this at a temperature of about 500 to 700°C.

In addition, the processing time at this time is such that the core material of the optical fiber 1 does not foam due to thermal decomposition.
For example, in the above temperature range, the cylinder body 2
All you have to do is move it. At this time, as shown in Figure 1, the flame 3
When the optical fiber 1 is directed downward and the optical fiber 1 is directed upward, the curved surface shape of the tip of the molten optical fiber 1 is less likely to be distorted, and a beautiful mirror finish can be achieved without being contaminated by flame soot. Further, at this time, the cylinder body 2 may be fixed without being moved, and the flame may be moved.

(Example) Example 1 A plastic optical fiber "ESCA" (manufactured by Mitsubishi Rayon Co., Ltd.) with a diameter of 1 mm was prepared approximately as shown in Figure 1.
A light guide was manufactured by fitting a cylindrical body made of brass to the light guide. A small gas generator manufactured by Herb Co., Ltd. was used as the flame generator, and the treatment was carried out by moving the flame for about 1 second at a position where the contact temperature of the flame was 600°C.

The cylindrical part of the obtained light guide is approximately as shown in Figure 2B.
As shown in Figure 2, the tip of the optical fiber had a curved mirror surface and was in good contact with the cylindrical body.

When this light guide was pulled in the direction of arrow B in FIG. 2B and the pull-out strength was measured, it was 4 kg, and the optical fiber itself was destroyed at the cut point. In addition, the glossiness of the mirror surface (reflectance at a 60° angle, compared with the mirror-finished glass surface as the standard (100%)) was 97%.

Example 2 A light guide was manufactured in the same manner as in Example 1 using "ESCA" with a diameter of 0.5 mm. At this time, the flame was moved in about 1 second to a position where the contact temperature was 500°C.

The light guide thus obtained was of good quality as in Example 1, with a pull-out strength of 2 kg and a gloss level of 98%.

Comparative Example The end face of an optical fiber was processed by flame treatment in the same manner as in Example 1, except that the flame was directed upward.

The resulting light guide had a pull-out strength of 4 kg, but the end face of the fiber was stained with flame soot and had a gloss level of 60%.

In the above embodiments, a case has been described in which a flame generating device, which is relatively inexpensive and easy to handle, is used as a heat source. Similarly, in the example,
Although the light guide is manufactured with the end face of the plastic optical fiber 1 slightly protruding from the effective surface of the cylinder 2, the light guide may be manufactured with the end face of the plastic optical fiber 1 facing slightly inward from the effective surface of the cylinder 2.

(Effects of the Invention) Since the present invention has the configuration described in detail above, it is possible to achieve a beautiful mirror finish in a short time and to efficiently manufacture a light guide in which the cylindrical body is firmly fixed. There are advantages.

[Brief explanation of drawings]

FIG. 1 is a schematic illustration of the state in which the method of the present invention is carried out, and FIGS. 2A and 2B are cross-sectional views of the main parts of the light guide before and after treatment. 1...Plastic optical fiber, 2...Cylinder made of heat-resistant material, 3...Flame.

Claims (1)

[Claims] 1. A method of manufacturing a light guide by fitting a plastic optical fiber into a cylindrical body made of a heat-resistant material, making the tip face the effective surface of the cylindrical body, and finishing this effective surface with high heat. and the contact temperature with heat is
At a position where the temperature is between 300°C and 700°C, the cylinder with its effective surface facing upward and the flame shot downward are moved relative to each other for a time that does not cause foaming due to thermal decomposition of the optical fiber core material. 1. A method of manufacturing a light guide, which comprises enlarging an optical fiber in the diametrical direction and mirror-finishing the end surface.