Optical fiber coloring apparatus and optical fiber manufacturing method

Abstract

The present invention provides a coloring apparatus for optical fibers and a method for manufacturing optical fibers that can reduce defects in the appearance of optical fibers. [Solution] The optical fiber coloring apparatus comprises a coating apparatus for applying coloring ink to the surface of a moving optical fiber, a curing apparatus including an ultraviolet lamp and an ultraviolet LED as an ultraviolet light source for curing the coloring ink applied by the coating apparatus, and a control device that controls the curing apparatus to irradiate ultraviolet light using only the ultraviolet LED when the traveling speed of the optical fiber is less than a first reference linear speed.

Description

[Technical Field]

[0001] The present disclosure relates to a coloring apparatus for optical fibers and a method for manufacturing an optical fiber. [Background Art]

[0002] An ultraviolet curable resin is sometimes used as a colored layer of an optical fiber. The colored layer is formed, for example, by applying an ultraviolet curable resin containing a pigment to the surface of an optical fiber, then irradiating ultraviolet rays to cure the resin. Patent Document 1 discloses a method of curing an ultraviolet curable resin constituting a coating of an optical fiber through a first irradiation step and a second irradiation step of irradiating ultraviolet rays. Patent Document 2 discloses a method for manufacturing an optical fiber that can prevent air bubbles from mixing into the colored layer of the optical fiber and suppress appearance defects. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2019-99436 [Patent Document 2] Japanese Unexamined Patent Publication No. 2022-32525 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The step of irradiating ultraviolet rays to cure the ultraviolet curable resin is performed by passing the optical fiber through an ultraviolet irradiation device. In a state where the linear velocity of the optical fiber is not constant, such as during the increase of the linear velocity, uneven curing of the resin may occur, which may impair the appearance of the colored layer.

[0005] An object of the present disclosure is to provide a coloring apparatus for optical fibers and a method for manufacturing an optical fiber that can reduce appearance defects of optical fibers. [Means for Solving the Problem]

[0006] An optical fiber coloring apparatus according to one embodiment of the present disclosure comprises: a coating apparatus for applying coloring ink to the surface of a moving optical fiber; a curing apparatus including an ultraviolet lamp and an ultraviolet LED as an ultraviolet light source for curing the coloring ink applied by the coating apparatus; and a control device for controlling the curing apparatus to irradiate ultraviolet light using only the ultraviolet LED when the traveling speed of the optical fiber is less than a first reference linear speed. [Effects of the Invention]

[0007] According to this disclosure, it is possible to reduce defects in the appearance of optical fibers. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing a coloring apparatus for optical fibers according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a graph showing an example of the time change in the optical fiber's travel speed immediately after the start of coloring. [Modes for carrying out the invention]

[0009] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described. (1) An optical fiber coloring apparatus according to one embodiment of the present disclosure comprises: a coating apparatus for applying coloring ink to the surface of a moving optical fiber; a curing apparatus including an ultraviolet lamp and an ultraviolet LED as an ultraviolet light source for curing the coloring ink applied by the coating apparatus; and a control device for controlling the curing apparatus to irradiate ultraviolet light using only the ultraviolet LED when the traveling speed of the optical fiber is less than a first reference linear speed.

[0010] According to the above-described optical fiber coloring apparatus, by using an ultraviolet LED that can reduce the intensity compared to an ultraviolet lamp in the low linear velocity region, excessive ultraviolet irradiation can be avoided, thereby reducing defects in the appearance of the colored optical fiber.

[0011] (2) In (1) above, the control device may be controlled to irradiate ultraviolet light with the ultraviolet lamp when the travel speed is equal to or greater than the first reference linear speed. In regions where the travel speed of the optical fiber is relatively fast, the colored ink can be sufficiently cured by using an ultraviolet lamp with high ultraviolet intensity.

[0012] (3) In (2) above, the control device may be controlled to irradiate ultraviolet light using both the ultraviolet LED and the ultraviolet lamp when the travel speed is equal to or greater than the first reference linear speed and less than the second reference linear speed, and to irradiate ultraviolet light using only the ultraviolet lamp when the travel speed is equal to or greater than the second reference linear speed. By providing a region in which both the ultraviolet LED and the ultraviolet lamp are used, a decrease in ultraviolet intensity when switching light sources can be avoided.

[0013] (4) In (1) to (3) above, the control device may control the intensity of ultraviolet light emitted from the ultraviolet LED according to the travel speed. By controlling the intensity of the ultraviolet LED, the amount of ultraviolet energy emitted onto the colored ink can be appropriately adjusted even in regions where the travel speed of the optical fiber is extremely slow, and an optical fiber with a good appearance can be obtained.

[0014] (5) In (1) to (4) above, the first reference linear velocity may be 20 m / min or more and 50 m / min or less. By setting the first reference linear velocity, which is the standard for irradiation using only ultraviolet LEDs, within the above range, it is possible to avoid excessive irradiation with ultraviolet light and obtain an optical fiber with a good appearance.

[0015] (6) A method for manufacturing an optical fiber according to one embodiment of the present disclosure is a method for manufacturing a colored optical fiber, comprising: a coating step of applying a colored ink to the surface of a moving optical fiber; and a curing step of irradiating the optical fiber coated with the colored ink with ultraviolet light to cure the colored ink, wherein in the curing step, when the traveling speed of the optical fiber is less than a first reference linear velocity, ultraviolet light is irradiated only with an ultraviolet LED, and when the traveling speed is equal to or greater than the first reference linear velocity, ultraviolet light is irradiated with an ultraviolet lamp. By using an ultraviolet LED that can have a lower intensity than an ultraviolet lamp in the low linear velocity region, excessive irradiation with ultraviolet light can be avoided, and a colored optical fiber with a good appearance can be manufactured.

[0016] [Details of the embodiments of this disclosure] Specific examples of the optical fiber coloring apparatus and optical fiber manufacturing method described herein will be described below with reference to the drawings. However, the present invention is not limited to these examples, and is intended to include all modifications within the meaning and scope of the claims as defined herein.

[0017] Figure 1 is a schematic diagram showing an optical fiber coloring apparatus 1 according to one embodiment of the present disclosure. As shown in Figure 1, the optical fiber coloring apparatus 1 comprises a coating apparatus 10, a curing apparatus 20, and a control device 30. The optical fiber coloring apparatus 1 is an apparatus for coloring optical fibers F. The optical fiber F is an uncolored fiber, for example, comprising a glass fiber and a coating resin layer formed around the glass fiber. As shown in Figure 1, the optical fiber F introduced into the optical fiber coloring apparatus 1 via a guide roller 41 passes through the coating apparatus 10 and the curing apparatus 20 in order, and is then wound onto a bobbin (not shown) via a guide roller 42.

[0018] The coating apparatus 10 includes a die 11. Colored ink is supplied to the die 11. When a traveling optical fiber F passes through the die 11 of the coating apparatus 10, the colored ink is applied to the surface of the optical fiber F. The colored ink is, for example, an ultraviolet curable resin containing a pigment, a photopolymerizable compound and a photopolymerization initiator. Although the components of the colored ink are not particularly limited, examples of each component are shown below.

[0019] Examples of pigments include colored pigments such as carbon black, titanium oxide, and zinc white; magnetic powders such as γ-Fe₂O₃, mixed crystals of γ-Fe₂O₃ and γ-Fe₃O₄, CrO₂, cobalt ferrite, cobalt-coated iron oxide, barium ferrite, Fe-Co, and Fe-Co-Ni; inorganic pigments such as MIO, zinc chromate, strontium chromate, aluminum tripolyphosphate, zinc, alumina, glass, and mica; and organic pigments such as azo pigments, phthalocyanine pigments, and dye lake pigments.

[0020] Examples of photopolymerizable compounds include (meth)acrylate-based oligomers such as urethane (meth)acrylate and epoxy (meth)acrylate; monofunctional monomers such as methyl (meth)acrylate; and polyfunctional monomers such as ethylene glycol di(meth)acrylate. In the present disclosure, (meth)acrylate means acrylate or the corresponding methacrylate.

[0021] Examples of photopolymerization initiators include radical photopolymerization initiators such as acylphosphine oxide-based initiators and acetophenone-based initiators.

[0022] The curing device 20 is a device for curing colored ink applied by the coating device 10. The curing device 20 includes a first ultraviolet irradiation device 21 and a second ultraviolet irradiation device 22. The first ultraviolet irradiation device 21 includes an ultraviolet lamp as an ultraviolet light source. The ultraviolet lamp is, for example, a mercury lamp or a metal halide lamp. The second ultraviolet irradiation device 22 includes an ultraviolet LED (Light Emitting Diode) as an ultraviolet light source. As shown in Fig. 1, the traveling optical fiber F passes through the first ultraviolet irradiation device 21 and the second ultraviolet irradiation device 22 in this order. The colored ink is cured by irradiating the colored ink on the surface of the optical fiber F with ultraviolet rays from the first ultraviolet irradiation device 21 and the second ultraviolet irradiation device 22. The emission wavelengths of the ultraviolet lamp and the ultraviolet LED can be appropriately changed depending on the type of the colored ink used, and may be, for example, 200 nm or more and 400 nm or less.

[0023] Ultraviolet rays are irradiated from the curing device 20 to cure the colored ink, whereby a colored layer is formed on the surface of the optical fiber F, and a colored optical fiber can be obtained. The thickness of the colored layer may be, for example, 2 µm or more and 15 µm or less.

[0024] The control device 30 is a device for controlling the operation of the curing device 20. Specifically, the control device 30 controls, for each of the first ultraviolet irradiation device 21 and the second ultraviolet irradiation device 22, switching whether to irradiate ultraviolet rays and the intensity of the irradiated ultraviolet rays. The control device 30 is configured to be capable of acquiring the traveling speed (linear speed) of the optical fiber F traveling in the optical fiber coloring apparatus 1, and controls the curing device 20 based on the acquired traveling speed. Details of the control by the control device 30 will be described later.

[0025] Incidentally, the degree of curing of UV-curable resin depends on the total amount of UV energy irradiated onto the UV-curable resin. In a device that irradiates UV light onto a colored ink applied to the surface of a moving optical fiber F, such as the optical fiber coloring device 1, the total amount of UV energy irradiated onto the colored ink at a certain position changes depending on the speed of the optical fiber F and the intensity of the irradiated UV light. If there is insufficient UV light irradiated onto the colored ink, the colored ink will not cure sufficiently, and conversely, if there is too much UV light irradiated, the colored ink will cure excessively, and in either case, the appearance of the colored optical fiber F may be impaired. Therefore, when coloring an optical fiber F, the amount of UV energy irradiated onto the colored ink is adjusted by appropriately controlling the UV irradiation device according to the speed of the optical fiber F. Specifically, by controlling the UV irradiation device to weaken the UV intensity when the optical fiber F is traveling slowly and to strengthen the UV intensity when the optical fiber is traveling fast, the amount of UV energy irradiated onto the colored ink can be adjusted to an appropriate range.

[0026] However, because there is a limit to the minimum output of the ultraviolet lamp, when using an ultraviolet lamp as an ultraviolet light source, it can only output ultraviolet light of a certain intensity or higher. Therefore, in regions where the travel speed of the optical fiber F is very slow, such as immediately after starting operation of the optical fiber coloring device 1, even if the output of the ultraviolet lamp is set to the minimum, the amount of ultraviolet energy irradiated onto the coloring ink can become excessively large, sometimes resulting in defects in appearance.

[0027] The optical fiber coloring apparatus 1 according to this embodiment controls the curing apparatus 20 so that the amount of ultraviolet energy does not become excessively large even in a region where the optical fiber F travels at a very slow speed. Specifically, the control device 30 controls the curing apparatus 20 to irradiate with ultraviolet light only using the ultraviolet LED when the optical fiber F travels at a speed less than the first reference linear velocity. The first reference linear velocity is a reference linear velocity that defines a linear velocity region where the optical fiber F travels at a very slow speed. That is, when the optical fiber F travels at a very slow speed, the control device 30 controls the curing apparatus 20 so that ultraviolet light is not irradiated from the first ultraviolet irradiation device 21 equipped with an ultraviolet lamp, but only from the second ultraviolet irradiation device 22 equipped with an ultraviolet LED. Unlike ultraviolet lamps, ultraviolet LEDs have no minimum output limitations, so the intensity of ultraviolet light can be appropriately adjusted even when the optical fiber F travels at a very slow speed, and the occurrence of appearance defects can be avoided. The first reference linear velocity may be, for example, 20 m / min or more and 50 m / min or less.

[0028] Furthermore, the control device 30 may control the curing device 20 to irradiate ultraviolet light with an ultraviolet lamp when the travel speed of the optical fiber F is equal to or greater than the first reference linear velocity. In regions where the travel speed of the optical fiber F is relatively fast, the colored ink can be sufficiently cured by using an ultraviolet lamp with high ultraviolet intensity.

[0029] Furthermore, the control device 30 may control the optical fiber F to irradiate with ultraviolet light using both the ultraviolet LED and the ultraviolet lamp when the optical fiber F's travel speed is greater than or equal to the first reference linear speed but less than the second reference linear speed, and to irradiate with ultraviolet light using only the ultraviolet lamp when the travel speed is greater than or equal to the second reference linear speed. The second reference linear speed is the reference linear speed for controlling the ultraviolet LED and is greater than the first reference linear speed. According to this configuration, a region in which both the ultraviolet LED and the ultraviolet lamp are used is provided between the linear speed region less than the first reference linear speed, where only the ultraviolet LED is used, and the linear speed region greater than or equal to the second reference linear speed, where only the ultraviolet lamp is used. If the light source is switched from the ultraviolet LED to the ultraviolet lamp without providing a region in which both the ultraviolet LED and the ultraviolet lamp are used, there may be a period during the switch in which ultraviolet light is not irradiated or the intensity is weakened, which may prevent the resin from curing sufficiently. By providing a region in which both the ultraviolet LED and the ultraviolet lamp are used, as in this configuration, a decrease in ultraviolet intensity when switching light sources can be avoided. When the travel speed of the optical fiber F moves from a region less than the first reference linear speed to the first reference linear speed or greater, the intensity of ultraviolet light increases by starting irradiation with the ultraviolet lamp. However, if the optical fiber F is traveling at a speed close to the first reference linear velocity, the travel speed is sufficiently high, and even when irradiation with the ultraviolet lamp is started, the amount of ultraviolet energy irradiated onto the colored ink will not become excessively large, thus preventing defects in appearance.

[0030] The second reference linear velocity is not particularly limited as long as it is greater than the first reference linear velocity, but it may be, for example, 75 m / min or more and 100 m / min or less. The typical travel speed of the optical fiber F in the optical fiber coloring device 1 is, for example, 1000 m / min or more, and may be 2000 m / min or more.

[0031] Furthermore, the control device 30 may control the intensity of ultraviolet light emitted from the ultraviolet LED according to the travel speed of the optical fiber F. Specifically, the intensity of ultraviolet light is reduced when the travel speed of the optical fiber F is low, and increased when the travel speed of the optical fiber F is high. In particular, in regions where the travel speed of the optical fiber F is extremely slow, such as in the linear velocity region lower than the first reference linear velocity, the amount of ultraviolet energy emitted to the colored ink changes significantly with changes in travel speed. Therefore, by controlling the ultraviolet LED as described above, the amount of ultraviolet energy emitted to the colored ink can be appropriately adjusted even in regions where the travel speed of the optical fiber F is extremely slow, and an optical fiber with a good appearance can be obtained.

[0032] The control by the control device 30 will be further explained with reference to a specific example. Figure 2 is a graph showing an example of the time change in the traveling speed of the optical fiber F immediately after the optical fiber coloring device 1 starts coloring the optical fiber F. Figure 2 shows the change in traveling speed when the optical fiber F starts traveling from a stopped state at time 0. As shown in Figure 2, the traveling speed of the optical fiber F increases with time after the optical fiber F starts traveling. In this example, the region in which the traveling speed of the optical fiber F is less than the first reference linear speed V1 is defined as S1. The region in which the traveling speed is greater than or equal to the first reference linear speed V1 and less than the second reference linear speed V2 is defined as S2. The region in which the traveling speed is greater than or equal to the second reference linear speed V2 is defined as S3.

[0033] In this example, in region S1 immediately after the start of travel, the control device 30 controls the curing device 20 so that ultraviolet light is irradiated only by the ultraviolet LEDs of the second ultraviolet irradiation device 22. Furthermore, the control device 30 controls the curing device 20 so that the intensity of ultraviolet light irradiated from the ultraviolet LEDs increases as the travel speed of the optical fiber F increases.

[0034] Next, when moving from region S1 to region S2, that is, when the travel speed of the optical fiber F reaches the first reference linear velocity V1, the control device 30 controls the curing device 20 to start irradiating with ultraviolet light from the ultraviolet lamp provided by the first ultraviolet irradiation device 21. In region S2, ultraviolet light is irradiated from both the ultraviolet lamp and the ultraviolet LED.

[0035] Next, when moving from region S2 to region S3, that is, when the travel speed of the optical fiber F reaches the second reference linear velocity V2, the control device 30 controls the curing device 20 to stop irradiation by the ultraviolet LEDs of the second ultraviolet irradiation device 22. In region S3, ultraviolet light is irradiated only by the ultraviolet lamp. Region S2 and the control device 30 may control the intensity of the ultraviolet lamp according to the travel speed of the optical fiber F.

[0036] By performing the control described above, it is possible to use only the ultraviolet LED when the optical fiber F is traveling at an extremely slow speed immediately after starting, while switching to irradiation with an ultraviolet lamp when the speed is sufficiently high. With this configuration, it is possible to obtain an optical fiber F that is well colored in any linear velocity range. In this example, control is shown for when the traveling speed of the optical fiber F is increasing immediately after starting, but the above control is not limited to the immediate post-start period. For example, the same control can be performed when the traveling speed of the optical fiber F is decreasing, such as just before stopping, and it can also be applied when the optical fiber F is traveling at a very low speed for some reason.

[0037] This disclosure also relates to a method for manufacturing optical fibers. One embodiment of this disclosure is a method for manufacturing a colored optical fiber, comprising a coating step of applying a colored ink to the surface of a moving optical fiber F, and a curing step of curing the colored ink by irradiating the optical fiber F coated with the colored ink with ultraviolet light. In this embodiment, in the curing step, when the traveling speed of the optical fiber F is less than a first reference linear velocity, ultraviolet light is irradiated only by an ultraviolet LED, and when the traveling speed is equal to or greater than the first reference linear velocity, ultraviolet light is irradiated by an ultraviolet lamp. According to this embodiment, by using only an ultraviolet LED in the region where the traveling speed of the optical fiber F is very slow, the intensity of ultraviolet light can be appropriately adjusted, and defects in the appearance of the colored optical fiber F can be avoided. The method for manufacturing an optical fiber according to this embodiment can be carried out, for example, using the optical fiber coloring apparatus 1 shown in Figure 1. For specific aspects and permissible modifications of the method for manufacturing an optical fiber according to this embodiment, refer to the above-described explanation of the optical fiber coloring apparatus 1, and omit redundant explanations.

[0038] Although the present disclosure has been described in detail above with reference to specific embodiments, the present disclosure is not limited to these examples.

[0039] In Figure 1, the first ultraviolet irradiation device 21 equipped with an ultraviolet lamp and the second ultraviolet irradiation device 22 equipped with an ultraviolet LED were arranged in this order along the direction of travel of the optical fiber F, but the order of the ultraviolet light sources is not particularly limited. That is, the ultraviolet LED may be placed upstream of the ultraviolet lamp. Also, the number of the first ultraviolet irradiation device 21 and the second ultraviolet irradiation device 22 is not limited to one each, and two or more may be arranged. [Explanation of symbols]

[0040] 1. Coloring device for optical fibers 10 Coating device 11 dice 20 Curing equipment 21. First ultraviolet irradiation device 22. Second ultraviolet irradiation device 30 Control device 41, 42 Guide rollers F Optical fiber V1 First reference linear velocity V2 Second reference linear velocity S1, S2, S3 Regions

Claims

1. A coating device for applying colored ink to the surface of a moving optical fiber, A curing apparatus including an ultraviolet lamp and an ultraviolet LED as an ultraviolet light source for curing the colored ink applied by the coating apparatus, A control device that controls the curing apparatus to irradiate ultraviolet light using only an ultraviolet LED when the traveling speed of the optical fiber is less than the first reference linear speed, A coloring device for optical fibers equipped with the following features.

2. The optical fiber coloring apparatus according to claim 1, wherein the control device controls the ultraviolet lamp to irradiate ultraviolet light when the travel speed is equal to or greater than the first reference linear speed.

3. The optical fiber coloring apparatus according to claim 2, wherein the control device controls the device to irradiate ultraviolet light using both the ultraviolet LED and the ultraviolet lamp when the travel speed is equal to or greater than the first reference linear speed and less than the second reference linear speed, and to irradiate ultraviolet light using only the ultraviolet lamp when the travel speed is equal to or greater than the second reference linear speed.

4. The optical fiber coloring apparatus according to any one of claims 1 to 3, wherein the control device controls the intensity of ultraviolet light emitted from the ultraviolet LED according to the travel speed.

5. The optical fiber coloring apparatus according to any one of claims 1 to 3, wherein the first reference linear velocity is 20 m / min or more and 50 m / min or less.

6. A method for manufacturing colored optical fibers, A coating process in which colored ink is applied to the surface of the optical fiber that is traveling, The process includes a curing step of curing the colored ink by irradiating the optical fiber coated with the colored ink with ultraviolet light, A method for manufacturing an optical fiber, wherein in the curing step, if the traveling speed of the optical fiber is less than a first reference linear velocity, ultraviolet light is irradiated only by an ultraviolet LED, and if the traveling speed is equal to or greater than the first reference linear velocity, ultraviolet light is irradiated by an ultraviolet lamp.

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