JP2005035799A - Optical fiber production apparatus and optical fiber production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber production method comprising curing a coating material comprising a curable resin in a curing furnace, wherein irregularities or damages are not formed on the surface of the cured coating material and to provide an optical fiber production apparatus which is compact as a whole because of the shortened distance between an ultraviolet irradiation step and the subsequent guide roller. <P>SOLUTION: The optical fiber production method comprises passing a coating material around first and second fixed guide rollers 7 and 9 and a swing guide roller 8 at a temperature not lower than the glass transition temperature in the step of drawing an optical fiber. The optical fiber production apparatus is characterized in that the first, second, and swing guide rollers 7, 9, and 8 around which a primary coated optical fiber 6 passes have surface states satisfying the arithmetic mean roughness Ra≤0.5 μm, the maximum height Ry≤2.7 μm, and the ten-point average roughness Rz≤1.4 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical fiber manufacturing apparatus and manufacturing method, and more particularly, to an optical fiber manufacturing apparatus and an optical fiber manufacturing method that do not cause unevenness or scratches on the surface of an optical fiber coating material in an optical fiber drawing apparatus.
[0002]
[Prior art]
Conventionally, in the case of manufacturing an optical fiber, when the coating material is an ultraviolet curable resin, the optical fiber drawn by a drawing furnace is coated with the ultraviolet curable resin, and then cured by irradiating ultraviolet rays with an ultraviolet irradiation device. In the ultraviolet irradiation step, the coating material is cured, but the cured coating material is heated to a high temperature by the light emitted from the ultraviolet lamp, and as a result, the ultraviolet curable resin is softened. If the coating material comes into contact with a hard guide roller in a softened state, the coating material surface may be uneven and damaged, or the optical fiber may be bent.
[0003]
As an optical fiber manufacturing method for preventing damage to the coating material surface or bending of the optical fiber ribbon and preventing an increase in transmission loss, the optical fiber ribbon disclosed in Patent Document 1 is manufactured. The method is known.
[0004]
In the manufacturing method of the optical fiber ribbon disclosed in Patent Document 1, the optical fiber ribbon is collectively coated with a coating material made of an ultraviolet curable resin, and then the coating material is cured when the coating material is cured by an ultraviolet irradiation device. The thickness, the diameter of the guide roller immediately after the ultraviolet irradiation device, and the time t (ms) until the optical fiber tape core wire reaches the guide roller from the ultraviolet irradiation device are defined as follows.
[0005]
d / ((R + d) × t) <0.2
Here, the thickness of the optical fiber ribbon is 2d (μm), and the diameter of the guide roller is 2R (mm).
Accordingly, the surface of the optical fiber ribbon is not damaged, no bending occurs, and deterioration of transmission characteristics is prevented.
[0006]
Another object of the present invention is to provide a predetermined twist effectively by rolling the optical fiber by the swinging motion of the swing guide roller, and to suppress polarization dispersion equivalently to the case of a perfect circular concentric shape. Patent Document 2 discloses an optical fiber and an optical fiber manufacturing method.
[0007]
In the optical fiber and the optical fiber manufacturing method disclosed in Patent Document 2, by rotating the swing guide roller, the optical fiber is rolled on the surface of the roller to alternately rotate the clockwise twist and the counterclockwise twist. The first fixed guide roller of the next stage installed in the lateral direction of the swinging guide roller inserts the optical fiber into the V-shaped narrow groove provided at the center of the roller surface. Thus, the rolling of the optical fiber on the roller surface is suppressed, and the smooth rolling of the optical fiber on the roller surface of the swing guide roller is assisted.
[0008]
In addition, in order to manufacture an optical fiber having a good surface state with no irregularities or scratches on the surface of the coating material, it is necessary to observe the uneven state of the surface of the traveling optical fiber. As a method of observing the uneven state of the fiber surface, a surface state observing method of a multi-core tape optical fiber disclosed in Patent Document 3 is known.
[0009]
In the method for observing the surface state of a multi-fiber ribbon optical fiber disclosed in Patent Document 3, the projection light is projected from the light projecting unit to the surface of the tape, and the light receiving unit is arranged at an angle that does not receive the specularly reflected light from the light projecting unit. If there is an abnormal part on the surface of the tape, the reflected light reflected at an angle different from the specularly reflected light is captured by the objective lens and received by a sensor using a CCD, and the reflected light of only the abnormal part is imaged get information. Next, this image information is processed by an image processing apparatus, so that the area and number of portions with high luminance can be detected, and the surface state irregularities, the position and size of bubbles can be known.
[0010]
[Patent Document 1]
JP-A-10-170787 [Patent Document 2]
JP-A-8-295528 [Patent Document 3]
Japanese Patent Laid-Open No. 10-246616
[Problems to be solved by the invention]
A step of drawing an optical fiber from an optical fiber preform in a drawing furnace installed at the top of the drawing tower, a step of coating a predetermined coating material on the drawn optical fiber, and curing the coating material by irradiating with ultraviolet rays After the optical fiber strand is obtained through the process, the optical fiber strand is sent to the next process by the guide roller. The time t (ms) until the optical fiber strand reaches the guide roller after the ultraviolet irradiation is disclosed in Patent Document 1. Unless the relational expression defined in (1) is satisfied, the coating material for the optical fiber is damaged. When the unevenness of the optical fiber coating surface is large, there is a problem of deteriorating the transmission characteristics of the optical fiber.
[0012]
In particular, as disclosed in Patent Document 2, by rolling the optical fiber and periodically applying a predetermined twist in the longitudinal direction, polarization dispersion is equivalent to the case where the optical fiber is a perfect circle. In the swing drawing for the purpose of suppression, the optical fiber rolls on the swing roller, so that depending on the surface condition of the swing roller, the surface of the optical fiber coating may be uneven and damaged, and transmitted. There are problems such as deterioration of characteristics and reduction of mechanical strength.
[0013]
In addition, when the coating material of the optical fiber is made of an ultraviolet curable resin, the ultraviolet curable resin is cured by irradiating the ultraviolet ray with an ultraviolet ray irradiation device. Softens when heated. When the coating material is heated to a temperature equal to or higher than the glass transition point, contact with the guide roller having a rough surface causes a problem that the shape of the guide roller surface is transferred and the surface of the coating material of the optical fiber is damaged. Even when the covering material is made of a thermosetting resin or the like, there is a similar problem when the covering material is heated.
[0014]
The present invention has been made in view of the above circumstances, and in an optical fiber manufacturing apparatus and an optical fiber manufacturing method for passing a guide roller at a temperature equal to or higher than a glass transition point of an optical fiber coating material, The object is to prevent unevenness and damage on the surface of the material.
[0015]
It is another object of the present invention to provide a compact optical fiber manufacturing apparatus that shortens the distance from the ultraviolet irradiation process to the next guide roller as much as possible.
[0016]
[Means for Solving the Problems]
An optical fiber manufacturing apparatus according to the present invention is an optical fiber manufacturing apparatus in which a coating material passes through a guide roller at a temperature equal to or higher than a glass transition point in an optical fiber drawing process, and the guide roller is in contact with the optical fiber. The surface state of the surface is characterized by satisfying the conditions of arithmetic average roughness Ra ≦ 0.5 μm, maximum height Ry ≦ 2.7 μm, and ten-point average roughness Rz ≦ 1.4 μm.
[0017]
The optical fiber manufacturing method according to the present invention is an optical fiber manufacturing method in which the coating material is cured in a curing furnace in the optical fiber drawing step, wherein the coating material is heated to a temperature equal to or higher than the glass transition point. The surface condition of the guide roller at the position where the fiber passes is characterized by satisfying the conditions of arithmetic average roughness Ra ≦ 0.5 μm, maximum height Ry ≦ 2.7 μm, and ten-point average roughness Rz ≦ 1.4 μm. To do.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram showing an optical fiber manufacturing apparatus for carrying out the optical fiber manufacturing method of the present invention.
[0019]
In the optical fiber manufacturing method of the present invention, an optical fiber preform (not shown) manufactured in a separate process is set in a drawing furnace 1, and the lower end of the optical fiber preform is heated and softened by a heater in the drawing furnace 1. The optical fiber 2 is drawn.
[0020]
Next, the outer diameter of the drawn optical fiber 2 is measured by the laser outer diameter measuring device 3. The measurement result obtained here is monitored by a drawing controller (not shown), and the drawing speed and the optical fiber mother are adjusted so that the outer diameter of the optical fiber 2 becomes a predetermined value (for example, 125 μm) based on the measurement result. The heating temperature of the material is controlled.
[0021]
Next, the drawn optical fiber 2 is passed through the ultraviolet curable resin stored in the resin coating die 4 to coat the surface of the optical fiber 2 with the ultraviolet curable resin. Examples of the resin material include urethane acrylate-based and epoxy acrylate-based ultraviolet curable resins, but thermosetting resins and silicone rubber that is baked by heating may be used.
[0022]
The optical fiber 6 coated with the ultraviolet curable resin is subsequently sent to the ultraviolet irradiation process, and irradiated with ultraviolet rays emitted from an ultraviolet lamp (not shown) of the ultraviolet irradiation device in the curing furnace 5 to cure the ultraviolet curable resin. To do. At this time, the outer diameter of the optical fiber 6 is, for example, 250 μm.
[0023]
Next, the optical fiber 6 coated with an ultraviolet curable resin passes through the first fixed guide roller 7, then passes through the swing guide roller 8 and the second fixed guide roller 9, and then the optical fiber in the next process. After being passed through the third fixed guide roller 11 and driven by the capstan 12 so as to have a predetermined winding tension and speed, the winding device passes through the fourth fixed guide roller 13. 14 is wound up.
[0024]
The first to fourth fixed guide rollers 7, 9, 11, and 13 have, for example, a roller diameter of 150 mmφ and a roller width of 30 mm, similar to the swing guide roller 8, but a V-shaped groove 7 a at the center of each roller surface. , 9a, 11a, 13a (11a, 13a are not shown).
[0025]
FIG. 2 is a sectional view taken along line XX of FIG. 1 showing the first and second fixed guide rollers and the swing guide roller. The first and second fixed guide rollers 7 and 9 and the swing guide roller 8 that change the traveling direction of the optical fiber are made of, for example, aluminum, and the surface with which the optical fiber 6 is in contact is processed with a plated layer or a ceramic layer. The roughness of the surface is adjusted so that the arithmetic average roughness (Ra), the maximum height (Ry), and the ten-point average roughness (Rz) as described later satisfy predetermined values. It is desirable to adjust the V-shaped groove of the third fixed guide roller 11 to the same surface roughness.
[0026]
The surface of the swing guide roller 8 that contacts the optical fiber 6 is the cylindrical surface 8a in the example shown in FIG. 2, but may be a U-shaped groove surface or a V-shaped groove surface. In the case of the cylindrical surface 8a, flanges 8b and 8c are formed on both side edges. Further, V-shaped grooves are formed on the surfaces of the first and second fixed guide rollers 7 and 9 that are in contact with the optical fiber 6.
[0027]
By combining the first fixed guide roller 7 and the swing guide roller 8 as described above, a predetermined twist is added to the optical fiber 6 with respect to the swing speed of the swing guide roller 8. A clockwise twist and a counterclockwise twist can be alternately added to the optical fiber 2 to be drawn.
[0028]
FIG. 3 is a schematic diagram showing a state in which the surface state of the optical fiber is being measured. In the surface state measuring step, the outer diameter of the optical fiber 6 is measured in a non-contact manner by the surface state measuring device 10 based on the measurement principle as disclosed in Patent Document 3.
[0029]
The surface state measuring device 10 includes a light projecting unit 15, a light receiving unit 18, and an image processing device 22. The light projecting unit 15 includes a laser diode 16, a slit 17, and the like, and the light receiving unit 18 includes an objective lens 19, a lens barrel 20, a sensor 21, and the like. The sensor 21 of the light receiving unit 18 uses a CCD capable of taking in two-dimensional image information related to irregularities and scratches on the surface of the coating material of the optical fiber 6. Further, since the optical fiber 6 is traveling, image information can be captured even by using a one-dimensional sensor in which photoelectric conversion elements such as photodiodes are arranged in a line.
[0030]
The light projecting unit 15 and the light receiving unit 18 are supported so that the angles Ψ ₁ and Ψ ₂ with the optical fiber 6 can be adjusted, and project light is projected from the light projecting unit 15 onto the optical fiber 6. . The light receiving unit 18 is supported at an angle that does not receive regular reflection light from the light projecting unit 15. When there is a defect such as irregularities on the surface of the optical fiber 6, the reflected light reflected at an angle different from the regular reflected light is captured by the objective lens 19 and received by the sensor 21 using the CCD, Image information of reflected light only from the defective portion can be obtained. By processing this image information by the image processing device 22, the area and the number of portions with high luminance can be calculated, and the position and size of the concavo-convex bubbles in the surface state can be known.
[0031]
The V-shaped grooves 7a and 9a of the first and second fixed guide rollers 7 and 9 and the cylindrical surface 8a of the swing guide roller 8 are in contact with the optical fiber strand 6 immediately after coming out of the curing furnace 5, and the optical fiber. Although the strand 6 passes while changing the traveling direction, the coating material of the optical fiber strand 6 at this time is cured by ultraviolet rays, but is heated and softened by the heat generated by the ultraviolet lamp in the curing furnace 5. It may cause unevenness or scratches. If the temperature of the coating material immediately after exiting the curing furnace 5 is equal to or higher than the glass transition temperature, the risk is further increased.
[0032]
For this reason, in the present invention, the V-shaped grooves 7a and 9a of the first and second fixed guide rollers 7 and 7 and the cylindrical surface of the swinging guide roller 8 are in contact with the coating material heated to the glass transition temperature or higher. By making the surface state of 8a into a state having a specific surface roughness, it is possible to remove the above-mentioned danger.
[0033]
(Example 1)
About the surface state of the surface on which the optical fiber of the guide roller runs, arithmetic average roughness Ra ≦ 0.5 (μm), maximum height Ry ≦ 2.7 (μm), and ten-point average roughness Using a fixed guide roller and a swing guide roller with Rz ≦ 1.4 (μm), the optical fiber travels in a state where the temperature of the optical fiber coating material made of UV curable resin is heated to a temperature higher than the glass transition point. I let you. The arithmetic average roughness Ra, the maximum height Ry, and the ten-point average roughness Rz are respectively defined in the standards of [JIS B 0601-1994].
[0034]
Here, the guide roller rotates in the circumferential direction of the roller and guides so as to change the traveling direction of the optical fiber, and swings that impart a predetermined twist to the optical fiber when drawing the swing The guide roller corresponds to the first and second fixed guide rollers 7 and 9 and the swing guide roller 8. Moreover, the surface state of each guide roller was measured using a non-contact type three-dimensional shape measuring instrument.
[0035]
As described above, when the surface of the optical fiber 6 after traveling on the first and second fixed guide rollers 7 and 9 and the swinging guide roller 8 was observed by SEM (Scanning Electron Microscope), light was observed. Concavities and convexities and scratches were not detected on the surface of the fiber strand coating material.
[0036]
(Comparative example)
Regarding the surface state of the surface on which the optical fiber of the guide roller runs, the arithmetic average roughness Ra> 2.3 (μm), the maximum height Ry> 15 (μm), and the ten-point average roughness Rz> Light having a coating material made of an ultraviolet curable resin similar to that used in the first embodiment using the first and second fixed guide rollers 7 and 9 and the swing guide roller 8 of 8.0 (μm). When the fiber strand was run and the surface of the optical fiber was observed by SEM, irregularities or scratches having a maximum height Ry or less were detected on the surface of the optical fiber coating material.
[0037]
(Example 2)
In Example 1, the irregularities on the surface of the optical fiber coating material and the defects of the scratches were observed by SEM, but can be detected by the surface state observation method disclosed in Patent Document 3 or the sensor of the measuring device. In this case, as shown in FIG. 3, the light projecting portion 15 that is incident on the optical fiber 6 at an angle ψ ₁ in the longitudinal direction is disposed, and the angle at which the laser scattered light on the surface of the optical fiber coating material can be received arranging the light receiving portion 18 in the [psi _2. Then, by detecting the scattered light by the sensor 21, it is possible to detect irregularities and scratches on the optical fiber coating.
[0038]
4 is a diagram showing the relationship between the scattered light sensing voltage and the surface state of the guide roller. FIG. 4A is a diagram showing the relationship between the sensor output (V) and the arithmetic average roughness Ra (μm) of the guide roller surface. 4B is a diagram showing the relationship between the sensor output (V) and the maximum height Ry (μm) of the guide roller surface, and FIG. 4C is a ten-point average roughness of the sensor output (V) and the guide roller surface. It is a figure which shows the relationship of thickness Rz (micrometer). In FIG. 4, a specific state of the surface state of the guide roller is determined by three parameters (Ra, Ry, Rz), and indicates first to fourth states.
[0039]
The surface condition of the guide roller is processed so as to satisfy arithmetic average roughness Ra = 0.5 (μm), maximum height Ry = 2.7 (μm), and ten-point average roughness Rz = 1.4 (μm). Using the first and second fixed guide rollers and the swinging guide roller in the first state, when the optical fiber strand heated to the temperature of the glass transition point or higher is run, The sensor output 0 (V) as shown in FIGS. 4A, 4B, and 4C was obtained from the light receiving portion shown in FIG. 3, and no irregularities or scratches were detected on the surface of the covering material.
[0040]
On the other hand, as for the surface state of the guide roller, the first state of the second state processed so as to satisfy Ra = 2.35 (μm), Ry = 15.4 (μm), and Rz = 8.56 (μm). When the same fixed optical fiber is run using the second fixed guide roller and the swing guide roller, the sensor output as shown in FIGS. 4A, 4B, and 4C is obtained from the light receiving unit shown in FIG. 1.0 (V) was obtained, and defects including irregularities and scratches were detected on the surface of the covering material.
[0041]
Further, the surface state of the guide roller is the first and second states of the third state processed so as to satisfy Ra = 2.29 (μm), Ry = 15.4 (μm), and Rz = 8.61 (μm). 2 When a similar optical fiber was run using a fixed guide roller and a swing guide roller, a sensor output 0. 0 as shown in FIGS. 4 (A), (B), and (C) from the light receiving portion shown in FIG. 4 (V) was obtained, and defects including irregularities and scratches were detected on the surface of the covering material.
[0042]
Further, regarding the surface state of the guide roller, the first and first states in the fourth state processed to satisfy Ra = 2.24 (μm), Ry = 15.1 (μm), and Rz = 8.14 (μm). 2 When a similar optical fiber was run using a fixed guide roller and a swing guide roller, a sensor output 0. 0 as shown in FIGS. 4 (A), (B), and (C) from the light receiving portion shown in FIG. 1 (V) was obtained, and it was detected that the surface of the covering material had some defects.
[0043]
In the above embodiment, the coating material for the optical fiber has been described with respect to the ultraviolet curable resin. However, the present invention is not limited to this, and a thermosetting resin or silicone rubber that is baked by heating may be used. In addition, a description has been given of an optical fiber in which a single optical fiber is coated with a coating material and cured. However, a plurality of optical fibers are arranged in parallel, and this is applied to an optical fiber tape core wire taped by collective coating. The invention can also be applied.
[0044]
【The invention's effect】
As is clear from the above description, according to the present invention, the surface condition of the guide roller is calculated by arithmetic mean roughness Ra ≦ 0.5 μm, maximum height Ry ≦ 2.7 μm, ten-point average roughness Rz ≦ 1.4 μm. By satisfying the above condition, even if the optical fiber is passed through the guide roller at a temperature higher than the glass transition point of the coating material, the surface of the optical fiber coating material will not be uneven or damaged, and high quality An optical fiber can be manufactured. In addition, the distance from the ultraviolet irradiation process to the next guide roller can be shortened, and the optical fiber manufacturing apparatus can be made compact as a whole.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing the configuration of an optical fiber manufacturing apparatus that performs an optical fiber manufacturing method according to an embodiment of the present invention.
2 is a cross-sectional view taken along the line XX of FIG. 1 showing the first and second fixed guide rollers and the swinging guide roller.
FIG. 3 is a schematic diagram showing a state in which the surface state of an optical fiber is being measured.
FIG. 4 is a diagram showing the relationship between the scattered light sensing voltage and the surface state of the guide roller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Drawing furnace, 2 ... Optical fiber, 3 ... Laser outer diameter measuring device, 4 ... Resin coating die, 5 ... Curing furnace, 6 ... Optical fiber strand, 7 ... 1st fixed guide roller, 8 ... Swing guide roller , 9 ... Second fixed guide roller, 10 ... Surface state measuring device, 11 ... Third fixed guide roller, 12 ... Capstan, 13 ... Fourth fixed guide roller, 14 ... Winding device, 15 ... Light projecting unit, 16 DESCRIPTION OF SYMBOLS ... Laser diode, 17 ... Slit, 18 ... Light-receiving part, 19 ... Objective lens, 20 ... Lens barrel, 21 ... Sensor, 22 ... Image processing apparatus.

Claims (4)

In an optical fiber drawing process, an optical fiber manufacturing apparatus in which a coating material passes through a guide roller at a temperature equal to or higher than a glass transition point, and a surface state of a contact surface of the guide roller with the optical fiber is an arithmetic average roughness. An apparatus for manufacturing an optical fiber, which satisfies the following conditions: Ra ≦ 0.5 μm, maximum height Ry ≦ 2.7 μm, and ten-point average roughness Rz ≦ 1.4 μm. The optical fiber manufacturing apparatus according to claim 1, wherein the covering material is made of a curable resin, and the guide roller is a roller that changes a traveling direction of the optical fiber. An optical fiber manufacturing method in which a coating material is cured in a curing furnace in a drawing process of the optical fiber, and the surface state of the guide roller at a position where the coating material passes through the optical fiber heated to a temperature equal to or higher than the glass transition point. Is an optical fiber manufacturing method characterized by satisfying the conditions of arithmetic average roughness Ra ≦ 0.5 μm, maximum height Ry ≦ 2.7 μm, and ten-point average roughness Rz ≦ 1.4 μm. 4. The method of manufacturing an optical fiber according to claim 3, wherein the covering material is made of a curable resin, and the guide roller is a roller that changes a traveling direction of the optical fiber.

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