JPH0522206B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of forming an end portion of a fiber bundle made of optical fibers.

[Conventional technology and its problems]

Optical fibers used in light guides and the like are made of glass fibers with a diameter of about 100 μm, for example, and several thousand fibers are bundled together to form a fiber bundle. In this case, the central portion of the fiber bundle is made flexible, the end portions are focused and fixed, and the end faces are polished to facilitate light reception and transmission.

It is known to use organic resin adhesives, such as epoxy resins, in order to focus and fix fiber bundle terminals (Japanese Patent Application Laid-Open No. 1986-1999).
111908). However, a structure in which a large number of fibers are fixed with resin has poor heat resistance, and airtightness is problematic due to the formation of voids in the resin adhesion reaction process. Another disadvantage is that the resin deteriorates due to heat when exposed to strong light.

Furthermore, it is known to braze the ends of fiber bundles with low-melting glass. This method is excellent in terms of heat resistance and airtightness, but the gaps between the fibers are too small for the glass to penetrate well, and if the temperature is raised to make it easier for the glass to penetrate into the gaps, There is a problem that the fiber may be thermally deformed or become brittle. On the other hand, as described in Japanese Patent Application Laid-Open No. 55-65907, a method is already known in which glass is powdered and embedded in the gap, but with this method, the bundle cross-sectional area There is a problem in that the occupancy of the core cross-sectional area in the light guide decreases, and the performance as a light guide decreases.

The present invention has been made to eliminate the problems and drawbacks of the prior art described above, and its purpose is to facilitate focusing and fixing of optical fibers,
Moreover, it is an object of the present invention to provide a method for forming an end portion of a fiber bundle that can improve airtightness and the degree of filling of optical fibers.

[Means for solving problems]

This object is, according to the present invention, to provide a method for forming an end portion of a fiber bundle in which the end portions of optical fibers are immersed in molten low-melting glass and fused. This is accomplished by attaching molten low-melting glass to this and solidifying it, immersing the end portion in the low-melting molten glass, and squeezing the end portion with a sleeve-shaped jig to perform focused welding.

〔Example〕

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

FIG. 1a shows a drum 1 for collecting and winding optical fibers to form a fiber bundle. This drum is made of aluminum, for example, and its diameter and width are determined depending on the length and thickness of the fiber bundle, and in this example the diameter is 60 cm and the width is 20 cm. As shown in an enlarged view in FIG. 1b, a heat-resistant sheet 2, for example, a mica plate sheet, is pasted on the surface of the drum 1, and a low-melting glass fiber 3 is placed on the mica plate sheet 2. arranged parallel to the axial direction of
It is set by temporarily fixing both ends with mica plate sheets 4, 4. Fiber 3 of this low melting point glass
is, for example, a lead-boric acid glass fiber with a softening temperature of 330° C., and its diameter is, for example, about 800 μm. The fibers 3 made of low melting point glass are arranged in a width of about 50 mm, and are set on the drum 1 at one or more locations, for example about 50 to 60 fibers at each location. Note that other temporary fasteners, such as heat-resistant adhesive tape, may be used instead of the mica plate sheets 4, 4.

The drum 1 prepared in advance as described above is set in a fiber drawing device, and the optical fiber 6 is wound and collected through the guide reel 5 (see FIG. 2). In this example,
An optical fiber 6 (diameter 100 μm) made of multicomponent glass with a softening temperature of 480° C. was wound up. The optical fiber may be collected directly through the capstan (drive-controlled rotary machine) of the drawing device, or it may be collected by collecting it onto another drum and then winding it again. It is desirable that the winding speed of the optical fiber 6 be relatively slow, and in this example it was 25 to 30 m/min.

After winding and collecting the optical fiber 6 on the drum 1, heat the intersection of the optical fiber 6 and the low melting point glass fiber 3 to about 450°C with a local heating device such as a heat gun. By melting the melting point glass fibers 3, the low melting point glass of the fibers 3 is attached to the individual optical fibers 6. Then, when the temperature is lowered, the low melting point glass solidifies and the fiber 3
The portion 6a of the upper optical fiber 6 is fixed in layers. At that time, in order to prevent this optical fiber 6 from falling apart, a third
As shown in the figure, an optical fiber 6 is attached using a plate-shaped auxiliary tool 7 (made of metal such as aluminum).
may be temporarily fixed to the drum 1. Note that instead of this auxiliary tool 7, an adhesive may be used for temporary fixation.

With the portion 6a of the optical fiber 6 fixed in a layered manner in this manner, the layered fixed portion 6a of the optical fiber 6 is cut with a cutter and removed from the drum 1. As a result, both ends 8 of the optical fiber 6 are fixed in a layered manner, as shown in FIG. 4, and the portion between them is flexible.

Next, the flexible portion of the optical fiber 6 is bundled into a circle with a predetermined thickness. For example, when about 8000 fibers 6 are bundled together, a fiber bundle 9 with a diameter of about 10 mm is created. Then, a sleeve-shaped jig 10 shown in FIGS. 5 and 6 is set on the bundled portion of the fiber bundle 9. This sleeve-like jig 10 is divided into halves, and the joint surfaces thereof are provided with protrusions 11 and grooves 12 that engage with each other. The diameter of the inner hole of the sleeve-shaped jig 10 is, for example,
10.5 mm and made of heat-resistant ceramic or metal such as stainless steel. Note that the sleeve-shaped jig 10 may have a tapered or chamfered portion in the inner hole. This taper or chamfer facilitates optical fiber focusing as described below.

Next, as shown in FIG. 7, the fixed end portion 8 of the fiber bundle 9 produced by the above process is
It is immersed in the pot melt tank 13. This pot melt tank 13 is made of, for example, a 300 c.c. alumina melt, and a low melting point glass 14 having the same composition as the low melting point glass fiber 3 to which the fiber bundle 9 is fixed in a layer is heated by a heater 15 to form the fiber glass. It is sufficiently melted at a temperature below 480 to 500°C, for example, 450°C, where it becomes soft. The fixed end portion 8 of the fiber bundle 9 is immersed in the low melting point glass 14 for about 15 seconds to form the fixed low melting point glass fiber 3 in a layered manner.
After sufficiently melting, the sleeve-shaped jig 10 is slid toward the end, and the end portion of the fiber bundle 9 is squeezed to collect the fiber bundle 9 and fuse it as a bundle end portion of a predetermined diameter. At that time, the end portions are sufficiently low melting point glasses 3 and 14.
Since the optical fibers 6 are wet and are considerably thicker than the predetermined thickness, the sliding movement of the sleeve-like jig 10 sufficiently presses the optical fibers 6 together and fuses them with each other without any gaps. The degree of filling also increases.

Then, lift it out of the pot melt tank 13,
After cooling and solidifying, the sleeve-shaped jig 10 is removed. The terminal thus created is polished, fitted into the terminal cap, and polished again to create a finished product.

〔Effect of the invention〕

As explained above, the method for forming the end portion of a fiber bundle according to the present invention involves fusing the end portions of individual optical fibers in a layered manner with low melting point glass, and then immersing this in a low melting point molten glass. In this way, the glass is sufficiently spread around each optical fiber, and the ends are converged using a sleeve-like jig, so that the optical fiber is highly filled and airtight. A fiber bundle end portion with excellent properties can be obtained. Furthermore, since the optical fibers are fixed in layers in advance, it is easy to handle the optical fibers during subsequent work, and the sleeve-shaped jig allows the optical fibers to be fused and bundled at the same time. Therefore, the work of focusing and fixing the fiber bundle end portion is easy.

[Brief explanation of drawings]

Fig. 1a is a perspective view showing a drum prepared for winding up optical fiber, Fig. 1b is a partially enlarged view of the drum shown in Fig. 1a, and Fig. 2 shows an optical fiber being wound onto the drum. Figure 3 is a perspective view showing how the optical fiber and low melting point glass fiber intersect at the end of winding.
Figure 3 is a diagram showing the optical fiber cut at the location shown in Figure 5 is a diagram showing the sleeve-shaped jig set in the fiber bundle, and Figure 6 is a cross-section showing the sleeve-shaped jig in half. FIG. 7 shows a state in which the fiber bundle is immersed in low melting point glass. 1...Drum, 2, 4...Heat-resistant sheet, 3...
...Low melting point glass fiber, 5...Guide reel,
6...Optical fiber, 7...Auxiliary device, 8
. . . End portion of fiber bundle, 9 . . . Central flexible portion of fiber bundle, 10 . . . Sleeve-shaped jig, 11 . , 15...
heater.

Claims (1)

[Claims] 1. A method for forming an end portion of a fiber bundle in which the end portions of optical fibers are immersed in molten low-melting glass and fused, comprising: arranging the end portions of the optical fibers in a layered manner;
A fiber bundle end section characterized in that a molten low melting point glass is attached and solidified, the end section is immersed in the low melting point molten glass, and the end section is squeezed with a sleeve-shaped jig to be focused and fused. How to form.