JPH0651585B2 - Manufacturing equipment for glass fiber for optical transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for manufacturing a glass fiber for optical transmission, and more particularly to an ultraviolet irradiation apparatus for curing an ultraviolet curable resin applied to an optical fiber drawn from a preform. is there.

[Conventional technology]

Thermosetting silicone rubber and ultraviolet curing resin are used as the coating material for the optical fiber. Of these, when the optical fiber is coated with an ultraviolet curable resin (hereinafter referred to as UV resin), conventionally, the ultraviolet curable resin is applied inline as shown in FIG. 6 and cured by an ultraviolet irradiation device (hereinafter referred to as UV furnace). Fiber drawing equipment is used. Preform 1
Is melted in the heating furnace 5 and drawn on the optical fiber 2, and the UV resin 3 is applied by the coating dies 4 and 8, and the UV furnace 6, which is arranged below the coating dies 4 and 8.
Ultraviolet rays are irradiated from 7 and 9 to cure the UV resin.

[Problems to be Solved by the Invention] Generally, since UV resin requires a certain amount of ultraviolet energy to cure, the output energy of the UV furnace used in the production line and the production drawing speed (hereinafter referred to as the drawing speed). , And the output energy of the UV furnace must be kept constant with respect to the drawing speed. However, the output energy of each UV furnace is limited, and in order to improve the drawing speed, the UV energy shown in FIG.
An apparatus configuration is employed in which several units such as the furnaces 6 and 7 are installed, and the number of UV furnaces to be used is changed according to the drawing speed to keep the ultraviolet energy constant.

This type of conventional UV furnace has a light wavelength of 200nm to 1200n.
Since it emits light in a wide wavelength range of m, it can be used not only for UV light required for curing UV resin, but also for infrared light.
Since the resin-coated optical fiber is irradiated, the optical fiber is unnecessarily heated. Therefore, as illustrated in FIG.
When the number of UV furnaces used is increased with respect to the drawing speed, the optical fibers are further heated, and the temperature of the optical fibers upon entering the coating die 8 becomes high, and the UV in the coating die 8 is increased.
The coating diameter of the resin changes and does not become uniform. Therefore, there is a problem that a good optical fiber cannot be obtained until the conditions of the drawing speed and the number of UV furnaces at which a predetermined coating outer diameter and the degree of curing of the UV resin are obtained are reached, and the productivity is reduced.

[Means for solving problems]

In order to solve the conventional problems, the present invention applies a UV resin to a drawn optical fiber and cures it in a UV furnace to manufacture a glass fiber for optical transmission. In the manufacturing apparatus, the UV furnace emits light from a lamp. It is characterized in that it has a filter for irradiating the UV resin coated on the optical fiber with only the light having a wavelength of 500 nm or less, which is necessary for curing the UV resin, of the light in a wide wavelength range.

[Action]

The present invention prevents heating of the optical fiber by irradiating the UV resin coated on the optical fiber with only ultraviolet rays out of the light of a wide range of wavelengths generated from the lamp, and changes the number of UV furnaces used according to the drawing speed. Even so, the temperature of the optical fiber in the coating die is always kept constant, and a uniform coating can be formed. Embodiments will be described below with reference to the drawings.

〔Example〕

FIG. 1 is a sectional view of the essential parts of a first embodiment of a UV furnace according to the present invention. Light in a wide wavelength range emitted from the lamp 10 13
Is condensed by the reflection plate 12 and is irradiated onto the optical fiber 2 through the infrared reflection filter 11 which is a feature of the present invention. In the infrared reflection filter 11, infrared light having a wavelength of 500 nm or more cannot pass and is reflected. Therefore, infrared reflection filter 11
Only the ultraviolet light 14 having a wavelength of 500 nm or less that has passed through is irradiated onto the optical fiber 2, and the optical fiber 2 is not heated.

2 and 3 are cross-sectional views of the essential parts of the second and third embodiments of the UV furnace according to the present invention, in which the arrangement of the infrared reflection filter 11 is different. The same reference numerals as those in FIG. 1 indicate the same parts.

FIG. 4 is a sectional view of the essential parts of a fourth embodiment of a UV furnace according to the present invention. The same reference numerals as those in FIG. 1 indicate the same parts. In this embodiment, the structure in which the reflection plate 12 in the first to third embodiments shown in FIGS. 1 to 3 is formed by the ultraviolet reflection filter 15 (in the figure, an example in which the filter is provided on the entire circumference is shown. ,
The filter does not have to be the entire circumference. ), The optical fiber 2 is irradiated with only the ultraviolet light 14 of 500 nm or less reflected by the ultraviolet reflection filter 15 other than the wide wavelength range light 13 'directly irradiated from the lamp 10, and the embodiment shown in FIG. The same effect as 1 can be obtained.

Next, by using the optical fiber drawing device of FIG.
The relationship between the drawing speed, the fiber temperature, and the outer diameter of the optical fiber manufactured by using the UV furnace having the structure of Example 1 shown in the figure and the optical fiber manufactured by using the conventional UV furnace were compared.

That is, the drawing apparatus shown in FIG. 6 is used to heat the preform 1 and spin the optical fiber 2 having an outer diameter of 125 μmφ
As the resin 3, 950Y100 manufactured by Nippon Synthetic Rubber Co., Ltd. was applied in two layers with a coating die 4 having a coating diameter of about 300 μm and a coating die 8 having a coating diameter of about 400 nm. In addition, the UV furnace is
That is, in order to match the Young's modulus of the resin, a drawing speed of 150
The number of units used varies according to the drawing speed, such as 1 unit up to m / min, 2 units at a drawing speed of 150 m / min to 300 m / min, 3 units at a drawing speed of 300 m / min to 450 m / min. The applied resin was cured.

FIG. 5 shows the coating diameter with respect to the drawing speed and the fiber temperature when entering the coating die 8 when a conventional UV resin is used. By increasing the number of UV furnaces by one, the fiber temperature rises by 20 ° C and the coating diameter becomes 10μ.
However, the coating outer diameter could not be kept constant. At this time, the coating diameter of the first layer is 301 μmφ
It was constant at.

FIG. 7 shows the coating diameter and the fiber temperature when entering the coating die 8 with respect to the drawing speed when the UV furnace having the structure of FIG. 1 of the present invention is used. Even if the number of UV furnaces was changed, the fiber temperature and the coating diameter had no effect, and an optical fiber with a uniform coating outer diameter was obtained up to a drawing speed of 450 m / min.

〔The invention's effect〕

As described above, the apparatus for manufacturing a glass fiber for optical transmission using the UV furnace according to the present invention keeps the curing degree of the UV resin applied to the optical fiber constant, and corresponds to the drawing speed during manufacturing. Since the temperature change of the optical fiber due to the change of the number of UV furnaces is prevented, the glass fiber for optical transmission having a uniform coating diameter is manufactured, and the effect is remarkable.

[Brief description of drawings]

1 to 4 are cross-sectional views of the essential parts of the UV furnaces of Examples 1 to 4 of the present invention, and FIG. 5 is a diagram showing the relationship between the drawing speed, fiber temperature, and coating outer diameter of the conventional UV furnace. , FIG. 6 is a schematic view of the optical fiber drawing apparatus, and FIG. 7 is the UV of the present invention.
It is a figure which shows the relationship of the drawing speed by a furnace, fiber temperature, and the coating | coated outer diameter. 1 ... Preform, 2 ... Optical fiber, 3 ... UV resin,
4, 8 ... Coating die, 5 ... Heating furnace, 6, 7, 9 ... UV
Furnace, 10 ... Lamp, 11 ... UV reflection filter, 12 ... Reflector, 13, 13 '... Wide wavelength band light, 14 ... UV light, 15 ... UV reflection filter that also serves as a reflection plate

Claims (1)

[Claims] 1. A glass fiber for optical transmission, in which an ultraviolet curable resin is applied in-line to an optical fiber obtained by melting and drawing a tip of a preform in a heating furnace, and the ultraviolet curable resin is irradiated with ultraviolet rays to cure the ultraviolet curable resin. In the manufacturing apparatus, the ultraviolet irradiation device applies only the light having a light wavelength of 500 nm or less necessary for curing the ultraviolet curable resin out of the light in the wide wavelength range emitted from the lamp to the ultraviolet curing resin. An apparatus for manufacturing a glass fiber for optical transmission, which comprises a filter for irradiating resin.