Optical fiber and method for manufacturing optical fiber

Abstract

To suppress breakage of an optical fiber.SOLUTION: An optical fiber has a glass fiber, and a resin coating layer coating the outer periphery of the glass fiber. In a spectrum obtained by measuring the amount of eccentricity of the glass fiber from a central axis with reference to the outer periphery of the resin coating layer at a plurality of measurement points set at a predetermined interval in an axial direction of the glass fiber, and performing Fourier transform on a waveform indicating the amount of eccentricity for each position of the plurality of measurement points, the maximum value of an amplitude of the amount of the eccentricity is 6 μm or less.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to optical fibers and methods for making optical fibers. [Background technology]

[0002] 2. Description of the Related Art Optical fibers in which the outer periphery of a glass fiber is covered with a resin coating layer are known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-292334 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to suppress breakage of optical fibers. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, Glass fiber; a resin coating layer covering the outer periphery of the glass fiber; having At a plurality of measurement points set at a predetermined interval in the axial direction of the glass fiber, the amount of eccentricity of the glass fiber from a central axis based on the outer periphery of the resin coating layer is measured, and in a spectrum obtained by Fourier transforming a waveform showing the amount of eccentricity for each position of the plurality of measurement points, the maximum value of the amplitude of the amount of eccentricity is 6 μm or less. and the wavelength at which the amplitude of the eccentricity is maximum is 0.1 m or more. An optical fiber is provided.

[0007] According to yet another aspect of the present disclosure, forming a glass fiber; forming a resin coating layer so as to cover an outer periphery of the glass fiber; curing the resin coating layer using a predetermined curing device; conveying the optical fiber with the cured resin coating layer; having In the step of forming the resin coating layer, The outer circumferential diameter of the resin coating layer is 190 μm or less, In the step of transporting the optical fiber, Among all rollers, including the immediately below roller located immediately below the curing device and a plurality of guide rollers downstream of the immediately below roller, the circumference of the largest roller is 0.2 m or more. A method for manufacturing an optical fiber is provided.

[0008] According to yet another aspect of the present disclosure, forming a glass fiber; forming a resin coating layer so as to cover an outer periphery of the glass fiber; curing the resin coating layer using a predetermined curing device; conveying the optical fiber with the cured resin coating layer; having In the step of forming the resin coating layer, The outer circumferential diameter of the resin coating layer is 190 μm or less, In the step of transporting the optical fiber, A vibration suppressing unit is installed downstream of the curing device and upstream of a roller located immediately below the curing device to suppress vibration of the optical fiber. A method for manufacturing an optical fiber is provided.

[0009] According to yet another aspect of the present disclosure, forming a glass fiber; forming a resin coating layer so as to cover an outer periphery of the glass fiber; curing the resin coating layer using a predetermined curing device; conveying the optical fiber with the cured resin coating layer; having In the step of forming the resin coating layer, The outer circumferential diameter of the resin coating layer is 190 μm or less, In the step of transporting the optical fiber, The roller located immediately below the curing device is used in a fixed state independent of other equipment members involved in the manufacture of the optical fiber. A method for manufacturing an optical fiber is provided. Effect of the Invention

[0010] According to the present disclosure, breakage of optical fibers can be suppressed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating an optical fiber according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic cross-sectional view for explaining the definition of the eccentricity of a glass fiber. [Diagram 3] FIG. 3 is a diagram of an eccentricity waveform showing the eccentricity of a glass fiber with respect to the axial position of the glass fiber. [Figure 4] FIG. 4 is a diagram showing an example of a spectrum obtained by Fourier transforming the eccentricity waveform. [Diagram 5] FIG. 5 is a schematic configuration diagram showing an optical fiber manufacturing apparatus according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Description of the embodiments of the present disclosure] <Knowledge gained by the inventors> First, the findings of the inventors will be described.

[0013] In recent years, in order to pack multiple optical fibers at high density in an optical cable, there has been a demand for optical fibers with a smaller outer diameter. Specifically, the outer diameter of some optical fibers in recent years is 200 μm or less.

[0014] In the manufacturing process of such a small-diameter optical fiber, the optical fiber is more susceptible to breakage than an optical fiber having a conventional outer diameter. If the optical fiber breaks during the manufacturing process, there is a risk that the manufacturing efficiency of the optical fiber will decrease. Therefore, there is a need for a new manufacturing method.

[0015] As a result of extensive research into the above-mentioned problems, the inventors have found that the frequency of breakage of an optical fiber during the manufacturing process depends on the amount of eccentricity of the glass fiber in the optical fiber.

[0016] If the glass fiber vibrates in the radial direction of the glass fiber when passing through the die in the resin coating device, the glass fiber becomes eccentric with respect to the opening of the die, and the resin coating layer is formed in that state. Therefore, the resin coating layer becomes thin in the direction in which the central axis of the glass fiber is shifted from the central axis of the optical fiber. In this case, when the optical fiber comes into contact with burrs on the guide roller or foreign matter on the guide roller, a large stress may be locally applied to the glass fiber through the part where the resin coating layer is thin. This may cause damage such as cracks to the glass fiber. As a result, the optical fiber may break due to the damage to the glass fiber.

[0017] Therefore, the inventors, in order to study the eccentricity of the above-mentioned glass fiber, performed a Fourier transform on a waveform showing the eccentricity of the glass fiber with respect to the axial position of the glass fiber, and analyzed the spectrum obtained by the Fourier transform. As a result, they found out what components (elements) in the spectrum affect the breakage of the optical fiber.

[0018] As a result, the inventors have succeeded in suppressing breakage of the optical fiber by adjusting the components that affect breakage of the optical fiber in the spectrum obtained by Fourier transform of the eccentricity waveform of the glass fiber.

[0019] The present disclosure is based on the above findings made by the present inventors.

[0020] <Embodiments of the present disclosure> Next, embodiments of the present disclosure will be listed and described.

[0021] [1] An optical fiber according to one embodiment of the present disclosure comprises: Glass fiber; a resin coating layer covering the outer periphery of the glass fiber; having At a plurality of measurement points set at a predetermined interval in the axial direction of the glass fiber, the amount of eccentricity of the glass fiber from a central axis based on the outer periphery of the resin coating layer is measured, and in a spectrum obtained by Fourier transforming a waveform showing the amount of eccentricity for each position of the plurality of measurement points, the maximum value of the amplitude of the amount of eccentricity is 6 μm or less. and the wavelength at which the amplitude of the eccentricity is maximum is 0.1 m or more. . According to this configuration, breakage of the optical fiber can be suppressed.

[0024] [4] A method for producing an optical fiber according to still another aspect of the present disclosure includes the steps of: forming a glass fiber; forming a resin coating layer so as to cover an outer periphery of the glass fiber; curing the resin coating layer using a predetermined curing device; conveying the optical fiber with the cured resin coating layer; having In the step of forming the resin coating layer, The outer circumferential diameter of the resin coating layer is 190 μm or less, In the step of transporting the optical fiber, The circumference of the largest roller among all rollers, including a direct below roller located directly below the curing device and a plurality of guide rollers downstream of the direct below roller, is 0.2 m or more. According to this configuration, breakage of the optical fiber can be suppressed.

[0025] [5] A method for producing an optical fiber according to still another aspect of the present disclosure includes the steps of: forming a glass fiber; forming a resin coating layer so as to cover an outer periphery of the glass fiber; curing the resin coating layer using a predetermined curing device; conveying the optical fiber with the cured resin coating layer; having In the step of forming the resin coating layer, The outer circumferential diameter of the resin coating layer is 190 μm or less, In the step of transporting the optical fiber, The vibration of the optical fiber is suppressed using a vibration suppressing section installed downstream of the curing device and upstream of a roller located immediately below the curing device. According to this configuration, breakage of the optical fiber can be suppressed.

[0026] [6] A method for producing an optical fiber according to still another aspect of the present disclosure includes the steps of: forming a glass fiber; forming a resin coating layer so as to cover an outer periphery of the glass fiber; curing the resin coating layer using a predetermined curing device; conveying the optical fiber with the cured resin coating layer; having In the step of forming the resin coating layer, The outer circumferential diameter of the resin coating layer is 190 μm or less, In the step of transporting the optical fiber, A roller located immediately below the curing device is used in a fixed state independent of other equipment members related to the manufacture of the optical fiber. According to this configuration, breakage of the optical fiber can be suppressed.

[0027] [7] In the method for producing an optical fiber according to any one of the above [4], In the step of transporting the optical fiber, A vibration suppressing section disposed downstream of the curing device and upstream of the direct below roller is used to suppress vibration of the optical fiber. According to this configuration, breakage of the optical fiber can be stably suppressed.

[0028] [8] In the method for producing an optical fiber according to any one of the above [4], In the step of transporting the optical fiber, The immediately below roller is used in a fixed state independent of other equipment members involved in the production of the optical fiber. According to this configuration, breakage of the optical fiber can be stably suppressed.

[0029] [9] In the method for producing an optical fiber according to any one of the above [5], In the step of transporting the optical fiber, The immediately below roller is used in a fixed state independent of other equipment members involved in the production of the optical fiber. According to this configuration, breakage of the optical fiber can be stably suppressed.

[0030]

[10] In the method for producing an optical fiber according to any one of the above [4], In the step of transporting the optical fiber, a vibration suppressing unit disposed downstream of the curing device and upstream of the direct below roller is used to suppress vibration of the optical fiber; The immediately below roller is used in a fixed state independent of other equipment members involved in the production of the optical fiber. According to this configuration, breakage of the optical fiber can be stably suppressed.

[0031] [Details of the embodiment of the present disclosure] Next, an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0032] <One embodiment of the present disclosure> (1) Optical fiber An optical fiber 10 according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing the optical fiber according to the present embodiment.

[0033] In the following, the "axial direction" of the glass fiber 100 refers to the direction along the central axis of the glass fiber 100, which can be rephrased as the longitudinal direction of the glass fiber 100. The "radial direction" of the glass fiber 100 refers to the direction perpendicular to the axial direction of the glass fiber 100, which can be rephrased as the transverse direction of the glass fiber 100 in some cases. The "circumferential direction" of the glass fiber 100 refers to the direction along the outer periphery of the glass fiber 100 (the circumferential direction in FIG. 1). The same terms as those for the glass fiber 100 can be used for the optical fiber 10.

[0034] 1, the optical fiber 10 of this embodiment is configured as a linear body in which, for example, the outer periphery of a glass fiber 100 is covered with a resin coating layer 200. That is, the optical fiber 10 has, for example, the glass fiber 100 and the resin coating layer 200 in this order from the central axis side of the glass fiber 100 toward the outer periphery side.

[0035] The term "optical fiber 10" used herein includes the optical fiber strand before being colored and the optical fiber core wire after being colored. In the following, the optical fiber 10 will be described as an optical fiber strand, for example.

[0036] [Glass fiber] The glass fiber 100 is configured as, for example, an optical transmission body that transmits light introduced into the optical fiber 10 along the axial direction of the optical fiber 10. The glass fiber 100 is also called, for example, a "bare optical fiber." The glass fiber 100 is made of silica (SiO 2 1. The optical fiber 100 has glass as its base material (main component) and includes a core 120 and a cladding 140 .

[0037] [Resin coating layer] The resin coating layer 200 is provided, for example, so as to cover the outer periphery of the glass fiber 100 and is configured to protect the glass fiber 100 .

[0038] In this embodiment, the resin coating layer 200 has, for example, a first resin coating layer (primary resin coating layer) 220 and a second resin coating layer (secondary resin coating layer) 240.

[0039] The first resin coating layer 220 is provided, for example, so as to cover the outer periphery of the clad 140 of the glass fiber 100 and is in contact with the outer periphery of the clad 140. The second resin coating layer 240 is provided, for example, so as to cover the outer periphery of the first resin coating layer 220 and is in contact with the outer periphery of the first resin coating layer 220.

[0040] The first resin coating layer 220 and the second resin coating layer 240 are formed, for example, as a cured product obtained by curing an ultraviolet-curable resin composition by ultraviolet irradiation. Examples of the base resin in the ultraviolet-curable resin composition include urethane acrylate.

[0041] In this embodiment, the optical fiber 10 is configured to have a smaller diameter than the conventional one. Specifically, the outer diameter of the above-mentioned resin coating layer 200 (i.e., the outer diameter of the second resin coating layer 240) is, for example, 190 μm or less. This allows a plurality of optical fibers 10 to be densely packed as an optical cable.

[0042] (2) Eccentricity of glass fiber Next, the amount of eccentricity of the glass fiber 100 in this embodiment will be described with reference to Fig. 2 to Fig. 4. Fig. 2 is a schematic cross-sectional view for explaining the definition of the amount of eccentricity of a glass fiber. Fig. 3 is a diagram of an eccentricity waveform showing the amount of eccentricity of the glass fiber with respect to the axial position of the glass fiber. Fig. 4 is a diagram showing an example of a spectrum obtained by Fourier transforming the eccentricity waveform.

[0043] First, the definition of the eccentricity of a glass fiber will be described with reference to Fig. 2. Note that Fig. 2 is merely an explanatory diagram and does not show the state of the optical fiber 10 of this embodiment. However, to simplify the explanation, the same reference numerals as in Fig. 1 are used.

[0044] As shown in FIG. 2, the eccentricity d of the glass fiber 100 is defined as the distance (radial deviation, radial displacement) from the central axis RC based on the outer periphery of the resin coating layer 200 to the central axis GC of the glass fiber 100.

[0045] Here, the eccentricity of the glass fiber 100 is measured, for example, by an eccentricity fluctuation observation device.

[0046] The eccentricity amount variation observation device is configured as an eccentricity image recognition device, and includes, for example, a first light source, a first imaging section, a second light source, and a second imaging section.

[0047] The first light source is arranged to irradiate light in the short direction of the optical fiber 10 to be measured. The light of the first light source includes a wavelength that transmits through the resin coating layer 200. The first imaging unit is arranged to face the first light source across the optical fiber 10 to be measured, and is configured to obtain an image of the light that has transmitted through the optical fiber 10. The second light source and the second imaging unit are configured similarly to the first light source and the first imaging unit, except that they are arranged to be perpendicular to the facing direction of the first light source and the first imaging unit.

[0048] With this configuration, the outer periphery position of the resin coating layer 200 and the inner periphery position of the resin coating layer 200 (the outer periphery position of the glass fiber 100) can be obtained based on the light transmitted through the optical fiber 10 in two axial directions that are perpendicular to the central axis of the optical fiber 10 and perpendicular to each other, and the eccentricity amount of the glass fiber 100, which is the distance between their centers, can be measured. In other words, the eccentricity amount of the glass fiber 100 can be measured without destroying the optical fiber 10.

[0049] By measuring the eccentricity of the glass fiber 100 at a plurality of measurement points set at a predetermined interval in the axial direction of the glass fiber 100, and plotting the measurement results with the positions of the plurality of measurement points on the horizontal axis and the amount of eccentricity at each position on the vertical axis, a waveform (distribution) of the amount of eccentricity can be obtained. Hereinafter, the waveform of the amount of eccentricity of the glass fiber 100 is also referred to as the "eccentricity waveform."

[0050] By the above-mentioned measurement, for example, an eccentricity waveform shown in Fig. 3 can be obtained. Note that the "eccentricity" on the vertical axis of Fig. 3 is the absolute value of the eccentricity regardless of the direction, in other words, it corresponds to the radius r in the polar coordinate system.

[0051] As shown in FIG. 3, the eccentricity waveform in the actual optical fiber 10 is not a neat sine wave, but has a complex shape due to the vibration amount, vibration direction, vibration frequency, etc. in each part of the optical fiber manufacturing apparatus 50 described later.

[0052] Therefore, the inventors performed a Fourier transform on the eccentricity waveform of the optical fiber 10 as shown in FIG. 4, and analyzed the spectrum obtained by the Fourier transform.

[0053] As a result, the inventors found that in the spectrum obtained by Fourier transforming the eccentricity waveform, the "maximum value of the amplitude of the eccentricity" or the "wavelength at which the amplitude of the eccentricity is maximum" affects breakage of the optical fiber 10. The component at which the amplitude of the eccentricity is maximum is also called the "maximum amplitude component."

[0054] Based on the above findings, it is preferable that the optical fiber 10 of this embodiment satisfies at least one of the following requirements regarding the eccentricity of the glass fiber 100.

[0055] As shown in FIG. 4, in this embodiment, in the spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, the maximum value of the amplitude of the eccentricity (the amplitude value of the maximum amplitude component) is, for example, 6 μm or less.

[0056] If the maximum value of the amplitude of the eccentricity exceeds 6 μm, the glass fiber 100 will be locally largely eccentric at the position where the eccentricity components having different wavelengths overlap. Therefore, the resin coating layer is likely to become locally thin. As a result, there is a risk that the frequency of breakage of the glass fiber 100 will increase. In contrast, in this embodiment, by setting the maximum value of the amplitude of the eccentricity to 6 μm or less, it is possible to suppress locally large eccentricity of the glass fiber 100 even if the eccentricity components having different wavelengths overlap. This makes it possible to suppress the resin coating layer from becoming locally thin. As a result, it is possible to reduce the frequency of breakage of the glass fiber 100.

[0057] The maximum value of the amplitude of the eccentricity is not particularly limited, and is preferably as close to 0 μm as possible.

[0058] As shown in FIG. 4, in this embodiment, in the spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, the wavelength at which the amplitude of the eccentricity is maximum (the wavelength of the maximum amplitude component) is, for example, 0.1 m or more.

[0059] If the wavelength at which the amplitude of the eccentricity is maximum is less than 0.1 m, there is a lot of overlapping of other components having different wavelengths with the component at which the amplitude of the eccentricity is maximum. Therefore, the resin coating layer is often locally thin. That is, the number of places where the thickness of the resin coating layer per unit length in the axial direction of the glass fiber 100 is thin increases. As a result, there is a risk of an increase in the frequency of breakage of the glass fiber 100. In contrast, in this embodiment, by setting the wavelength at which the amplitude of the eccentricity is maximum to 0.1 m or more, it is possible to reduce the number of "other components having different wavelengths" that overlap with the component at which the amplitude of the eccentricity is maximum. This makes it possible to suppress the resin coating layer from becoming locally thin, that is, to suppress an increase in the number of places where the thickness of the resin coating layer per unit length in the axial direction of the glass fiber 100 is thin. As a result, it is possible to reduce the frequency of breakage of the glass fiber 100.

[0060] The upper limit of the wavelength at which the amplitude of the eccentricity is maximum is not particularly limited, and is preferably as large as possible. However, taking into consideration the drawing speed of the optical fiber manufacturing apparatus 50 described later, the wavelength at which the amplitude of the eccentricity is maximum is, for example, 1 m or less.

[0061] (3) Optical fiber manufacturing equipment Next, an optical fiber manufacturing apparatus 50 according to this embodiment will be described with reference to Figures 5 and 6. Figure 5 is a schematic diagram showing the configuration of the optical fiber manufacturing apparatus according to this embodiment.

[0062] 5, optical fiber manufacturing apparatus 50 of the present embodiment includes, for example, a drawing furnace 510, a fiber position measuring unit 522, a cooling unit 523, an outer diameter measuring unit 524, a resin coating unit 530, a curing unit 540, a conveying unit 550, a bobbin 560, and a control unit 590. The device members other than control unit 590 are provided in this order.

[0063] Hereinafter, in each device member of optical fiber production apparatus 50, the side closer to gripping mechanism 512 will be referred to as the "upstream" side, and the side closer to bobbin 560 will be referred to as the "downstream" side.

[0064] The drawing furnace 510 is configured to form the glass fiber 100. The glass preform G is heated in the drawing furnace 510, and the softened glass is drawn, thereby forming the glass fiber 100 having a small diameter.

[0065] The fiber position measuring unit 522 is configured to measure the horizontal position of the glass fiber 100 .

[0066] Cooling device 523 is configured to cool the glass fiber 100 formed in draw furnace 510 .

[0067] The outer diameter measuring unit 524 is configured to measure the outer diameter of the glass fiber 100 before it is resin-coated.

[0068] The resin coating device 530 is configured to form a resin coating layer 200 so as to cover the outer periphery of the glass fiber 100. The resin coating layer 200 has a die that applies an ultraviolet-curable resin composition to the outer periphery of the glass fiber 100 while inserting the glass fiber 100 therethrough.

[0069] In this embodiment, the resin coating device 530 has two dies for forming the first resin coating layer 220 and the second resin coating layer 240 in this order from the central axis side of the glass fiber 100 toward the outer periphery side.

[0070] The curing device 540 is configured to irradiate the resin coating layer 200 with ultraviolet rays to cure the resin coating layer 200 .

[0071] The conveying section 550 is configured to convey, for example, the optical fiber 10 with the resin coating layer 200 cured. Specifically, the conveying section 550 has, for example, a plurality of guide rollers 552, 556, and a capstan 554. A direct below roller 552a, which is one of the plurality of guide rollers 552, is located, for example, directly below the curing device 540. The capstan 554 is, for example, provided downstream of the direct below roller 552a, and configured to convey (pull) the optical fiber 10 with a predetermined tension while holding the optical fiber 10 between the belt and the roller. The screening rollers 552c, 552d, and 552e of the plurality of guide rollers 552 are provided downstream of the capstan 554, and configured to apply a screening tension to the optical fiber 10 together with the capstan 554. The guide roller 556 is provided downstream of the screening roller 552e, and configured to adjust the tension of the optical fiber 10 by moving up and down in response to fluctuations in the tension of the optical fiber 10.

[0072] The bobbin 560 is provided, for example, downstream of the guide roller 556 and configured to wind up the optical fiber 10.

[0073] The control unit 590 is configured, for example, to be connected to and control each unit of the optical fiber manufacturing apparatus 50. The control unit 590 is configured, for example, as a computer.

[0074] In this embodiment, in order to manufacture the optical fiber 10 that satisfies the requirements for the eccentricity of the glass fiber 100 described above, the optical fiber manufacturing apparatus 50 is configured, for example, as follows.

[0075] In this embodiment, the circumferential length of the largest roller among all rollers including the immediately below roller 552a and the plurality of guide rollers 552 downstream of the immediately below roller 552a is, for example, 0.2 m or more.

[0076] The circumferential length of the largest guide roller 552 is preferably, for example, 0.9 m or less.

[0077] 5, the conveying section 550 has, for example, a vibration suppressing section 555. The vibration suppressing section 555 is installed, for example, downstream of the curing device 540 and upstream of a direct below roller 552a located directly below the curing device 540. The vibration suppressing section 555 is configured, for example, such that two rollers come into contact with the optical fiber from different directions to suppress vibration of the optical fiber 10.

[0078] The vibration suppressing section 555 suppresses vibration of the optical fiber 10, thereby making it possible to stably maintain the position of the central axis of the glass fiber 100. In other words, eccentricity of the glass fiber 100 can be suppressed.

[0079] 5, in this embodiment, the immediately below roller 552a located immediately below the curing device 540 is fixed independently from, for example, other equipment members related to the manufacture of the optical fiber 10. Specifically, the immediately below roller 552a is fixed to, for example, the floor without being connected to other equipment members.

[0080] By using the direct-below roller 552a in a fixed state independent of other equipment members involved in the manufacture of the optical fiber 10, it is possible to suppress the direct-below roller 552a from receiving vibrations from other equipment members. As a result, in the spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, it is possible to reduce the maximum value of the amplitude of the eccentricity and to lengthen the wavelength at which the amplitude of the eccentricity is maximum.

[0081] <Other embodiments of the present disclosure> Although the embodiments of the present disclosure have been specifically described above, the present disclosure is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit and scope of the present disclosure.

[0082] In the above embodiment, the optical fiber 10 is illustrated and described as an optical fiber wire before being colored, but as described above, the optical fiber 10 may be an optical fiber core wire after being colored. That is, the optical fiber 10 may have a colored layer covering the outer periphery of the resin coating layer 200.

[0083] In the above embodiment, the resin coating layer 200 is configured with two layers, but the present invention is not limited to this. The resin coating layer 200 may be configured with only one layer, or may be configured with three or more layers.

[0084] In the above embodiment, the optical fiber 10 satisfies both of the following requirements (i) and (ii) regarding the eccentricity of the glass fiber 100; however, the present invention is not limited to this case. (i) In the spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, the maximum value of the amplitude of the eccentricity is 6 μm or less. (ii) In the spectrum obtained by Fourier transforming the eccentricity waveform of the glass fiber 100, the wavelength at which the amplitude of the eccentricity is maximum is 0.1 m or more. If the optical fiber 10 satisfies at least one of the requirements (i) and (ii), it is possible to obtain a significant effect of reducing the frequency of breakage of the glass fiber 100. However, the above-mentioned effect can be obtained more stably if both the requirements (i) and (ii) are satisfied.

[0085] In the above embodiment, the case where all of (x), (y) and (z) are implemented to manufacture the optical fiber 10 that satisfies the above requirement for the eccentricity of the glass fiber 100 has been described, but the present invention is not limited to this case. (x) Of all the rollers, including the immediately below roller 552a located immediately below the curing device 540 and the multiple guide rollers 552 downstream of the immediately below roller 552a, the circumference of the largest roller is set to 0.2 m or more. (y) The vibration suppressing unit 555 installed downstream of the curing device 540 and upstream of the direct below roller 552a located directly below the curing device 540 suppresses vibration of the optical fiber 10. (z) The roller 552a located immediately below the curing device 540 is used in a fixed state independent of other equipment members related to the manufacture of the optical fiber 10. By implementing at least one of (x), (y), and (z), the above-mentioned effects can be obtained to a certain extent. However, by implementing many of (x), (y), and (z), the above-mentioned effects can be obtained more stably. EXAMPLES

[0086] Next, examples according to the present disclosure will be described. These examples are merely examples of the present disclosure, and the present disclosure is not limited to these examples.

[0087] (1) Fabrication of optical fiber Under the conditions in Table 1 described later, optical fibers of samples A1 to A4, B1 and B2 were produced.

[0088] Common conditions not listed in Table 1 are as follows: Glass fiber outer diameter: 125μm Number of resin coating layers: 2 layers

[0089] (2) Evaluation [Eccentricity measurement] An eccentricity fluctuation observation device was used to measure the eccentricity of the glass fiber at a plurality of measurement points set at predetermined intervals in the axial direction of the glass fiber, thereby obtaining a waveform of the eccentricity for each of the positions of the plurality of measurement points.

[0090] After that, the eccentricity waveform of the optical fiber was Fourier transformed (FFT: Fast Fourier Transform) and the spectrum obtained by the Fourier transform was analyzed. In this way, the "maximum value of the eccentricity amplitude" and the "wavelength at which the eccentricity amplitude is maximum" were obtained from the spectrum obtained by Fourier transforming the eccentricity waveform. Note that the "wavelength at which the eccentricity amplitude is maximum" is hereinafter referred to as the "wavelength of the maximum amplitude component."

[0091] [Measurement of frequency of wire breakage] The optical fiber samples described above were rewound under a tension of 1.5 kg during the manufacturing process, and the number of times the optical fiber broke was measured. For each sample, the break frequency was calculated as the number of breaks per 1000 kilometers (mm). As a result, a break frequency of less than 5 times / mm was evaluated as "good," and a break frequency of 5 times / mm or more was evaluated as "poor."

[0092] (3) Results The results of the evaluation of each sample are explained using Table 1 below.

[0093] [Table 1]

[0094] [Samples B1 and B2] In the samples B1 and B2, the maximum amplitude of the eccentricity exceeded 6 μm in the spectrum obtained by Fourier transforming the eccentricity waveform. Also, the wavelength at which the amplitude of the eccentricity became maximum in the spectrum obtained by Fourier transforming the eccentricity waveform was less than 0.1 m.

[0095] As a result, in samples B1 and B2, the optical fibers were prone to breakage, with the breakage frequency being 5 times / mm or more. Also, sample B1, which had a relatively small diameter, tended to have a higher breakage frequency than sample B2, which had a conventional outer diameter.

[0096] In samples B1 and B2, the circumference of the maximum guide roller was less than 0.2 m, so the maximum guide roller could not stably transport the optical fiber. In addition, in samples B1 and B2, a vibration suppression unit was not provided, so the position of the center axis of the glass fiber was significantly shifted or shifted in a short cycle when the resin coating layer was coated due to vibration from the transport unit. In addition, in samples B1 and B2, the immediately below roller was used in a state where it was connected to other equipment components, so the vibration of the immediately below roller was large or short-period.

[0097] For these reasons, in the spectrum obtained by Fourier transforming the eccentricity waveform, the maximum amplitude of the eccentricity was large and the wavelength at which the amplitude of the eccentricity was maximum was short in samples B1 and B2. As a result, it is believed that the frequency of breakage was high in samples B1 and B2. It is also believed that the thinner the diameter of the optical fiber, the more likely it was to break.

[0098] [Sample A1~A4] In contrast, in the samples A1 to A4, the maximum amplitude of the eccentricity was 6 μm or less in the spectrum obtained by Fourier transforming the eccentricity waveform, and the wavelength at which the amplitude of the eccentricity was maximum in the spectrum obtained by Fourier transforming the eccentricity waveform was 0.1 m or more.

[0099] As a result, in the samples A1 to A4, the optical fibers were less susceptible to breakage, and the frequency of breakage was less than 5 times / Mm.

[0100] In Samples A1 to A4, the peripheral length of the largest guide roller was set to 0.2 m or more, and thus the optical fiber could be stably transported by the largest guide roller.

[0101] In addition, in samples A1 and A2, the vibration suppressing section was provided, and thus the position of the central axis of the glass fiber could be stably maintained when the resin coating layer was coated due to vibration from the conveying section.

[0102] In addition, in Samples A1 to A3, the directly below roller was used in a fixed state independent of other device members, so that an increase in vibration of the directly below roller and a shortening of the period could be suppressed.

[0103] As a result, in the spectrum obtained by Fourier transforming the eccentricity waveform, the maximum amplitude of the eccentricity could be reduced and the wavelength at which the amplitude of the eccentricity is maximum could be lengthened in Samples A1 to A4. As a result, it was confirmed that, in Samples A1 to A4, the frequency of wire breakage could be reduced, even though the diameter was smaller than that of Sample B1. [Explanation of symbols]

[0104] 10 Optical Fiber 50 Optical fiber manufacturing equipment 100 Glass Fiber 120 cores 140 Clad 200 Resin coating layer 220 1st resin coating layer 240 Second resin coating layer 430 Curing equipment 510 Wire drawing furnace 512 Gripping mechanism 514 Furnace tube 516 Heating element 518 Gas Supply Department 522 Fiber position measurement unit 523 Cooling device 524 Outer diameter measuring section 530 Resin coating device 540 Curing equipment 550 Transport section 552 Guide roller 552a Directly below roller 552b Guide roller 552c, 552d, 552e Screening Rollers 554 Capstan 555 Vibration suppressor 556 Guide Roller 560 Bobbin 590 Control Unit

Claims

1. Glass fiber; a resin coating layer covering the outer periphery of the glass fiber; having At a plurality of measurement points set at a predetermined interval in the axial direction of the glass fiber, the amount of eccentricity of the glass fiber from a central axis based on the outer periphery of the resin coating layer is measured, and in a spectrum obtained by Fourier transforming a waveform showing the amount of eccentricity for each position of the plurality of measurement points, the maximum value of the amplitude of the amount of eccentricity is 6 μm or less, and the wavelength at which the amplitude of the amount of eccentricity is maximum is 0.1 m or more. Optical fiber.

2. forming a glass fiber; forming a resin coating layer so as to cover an outer periphery of the glass fiber; curing the resin coating layer using a predetermined curing device; conveying the optical fiber with the cured resin coating layer; having In the step of forming the resin coating layer, The outer circumferential diameter of the resin coating layer is 190 μm or less, In the step of transporting the optical fiber, Among all rollers including a roller located immediately below the curing device and a plurality of guide rollers located downstream of the roller, the circumference of the largest roller is 0.2 m or more. A method for manufacturing optical fiber.

3. forming a glass fiber; forming a resin coating layer so as to cover an outer periphery of the glass fiber; curing the resin coating layer using a predetermined curing device; conveying the optical fiber with the cured resin coating layer; having In the step of forming the resin coating layer, The outer circumferential diameter of the resin coating layer is 190 μm or less, In the step of transporting the optical fiber, A vibration suppressing unit is installed downstream of the curing device and upstream of a roller located immediately below the curing device to suppress vibration of the optical fiber. A method for manufacturing optical fiber.

4. forming a glass fiber; forming a resin coating layer so as to cover an outer periphery of the glass fiber; curing the resin coating layer using a predetermined curing device; conveying the optical fiber with the cured resin coating layer; having In the step of forming the resin coating layer, The outer circumferential diameter of the resin coating layer is 190 μm or less, In the step of transporting the optical fiber, The roller located immediately below the curing device is used in a fixed state independent of other equipment members involved in the manufacture of the optical fiber. A method for manufacturing optical fiber.

5. In the step of transporting the optical fiber, A vibration suppressing unit is installed downstream of the curing device and upstream of the roller directly below the optical fiber to suppress vibration of the optical fiber. The method for producing the optical fiber according to claim 2 .

6. In the step of transporting the optical fiber, The roller is used in a fixed state independent of other equipment members involved in the manufacture of the optical fiber. The method for producing the optical fiber according to claim 2 .

7. In the step of transporting the optical fiber, The roller is used in a fixed state independent of other equipment members involved in the manufacture of the optical fiber. The method for producing the optical fiber according to claim 3 .

8. In the step of transporting the optical fiber, a vibration suppressing unit disposed downstream of the curing device and upstream of the direct below roller is used to suppress vibration of the optical fiber; The roller is used in a fixed state independent of other equipment members involved in the manufacture of the optical fiber. The method for producing the optical fiber according to claim 2 .

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