Optical fiber manufacturing device and manufacturing method

Abstract

This optical fiber manufacturing device comprises: a drawing tower including a drawing furnace for heating an optical fiber preform, and a coating part for coating a drawn glass fiber with an ultraviolet curable resin; a direct-under roller for changing a direction of a travel path of the coated optical fiber; a plurality of guide rollers for respectively guiding the optical fibers fed from the direct-under roller; an ultraviolet irradiation device for irradiating the coated ultraviolet curable resin with ultraviolet rays to cure the ultraviolet curable resin; and a withdraw part for withdrawing the optical fibers guided by the guide rollers. The ultraviolet irradiation device is arranged on a downstream side of the drawing tower, and operates so as to form a state in which the travel path is exposed and a state in which the travel path is surrounded and ultraviolet rays are radiated toward the travel path.

Description

Optical fiber manufacturing apparatus and manufacturing method

[0001] The present disclosure relates to an apparatus and method for manufacturing an optical fiber.

[0002] This application claims priority based on Japanese Application No. 2023-147798 filed on September 12, 2023, and incorporates by reference all of the contents of the aforementioned Japanese application.

[0003] In a typical optical fiber manufacturing (drawing) method, the tip of a glass preform for optical fiber (hereinafter referred to as an optical fiber preform) is heated to soften it, and then tension is applied to the softened part to draw it into a thin glass fiber. The glass fiber then passes through a so-called drawing tower device, which includes a cooling process and a coating process including the application and hardening of a resin, to produce an optical fiber covered with a coating. The coated glass fiber is then guided by a roller directly below the fiber and a guide roller, and then taken up by a take-up device downstream of the pass line and wound onto a bobbin or the like.

[0004] Resin coatings for optical fibers are formed on the outer surface of bare glass optical fibers to protect the bare optical fibers from external impacts, etc. This coating process is disclosed as comprising a primary coating (primary: hardened inner layer resin) and a secondary coating (secondary: hardened outer layer resin) formed on the outer surface of the bare optical fiber (see Patent Document 1).

[0005] Japanese Patent Application Laid-Open No. 2019-64855

[0006] The optical fiber manufacturing apparatus according to the present disclosure comprises a drawing furnace that heats an optical fiber preform, a drawing tower including an application unit that applies ultraviolet curing resin to the drawn glass fiber, a roller directly below that changes the direction of the travel path of the applied optical fiber, a plurality of guide rollers that respectively guide the optical fiber sent from the roller directly below, an ultraviolet irradiation device that irradiates ultraviolet light onto the applied ultraviolet curing resin to harden the ultraviolet curing resin, and a take-up unit that takes up the optical fiber guided by the guide roller, and the ultraviolet irradiation device is positioned downstream of the drawing tower and operates to form a state in which the travel path is exposed and a state in which the travel path is enclosed and ultraviolet light is irradiated toward the travel path.

[0007] Furthermore, the optical fiber manufacturing method according to the present disclosure is a method for manufacturing an optical fiber using an optical fiber manufacturing apparatus having, in order: a drawing furnace for heating an optical fiber preform; a coating device for coating a drawn glass fiber with resin; a roller directly below for changing the direction of the running line of the coated optical fiber; a plurality of guide rollers for guiding the optical fiber sent from the roller directly below; and a take-up device for taking up the optical fiber guided by the guide roller, in which, after the drawn optical fiber has been arranged at all steps of the running path of the optical fiber manufacturing apparatus, an ultraviolet irradiation device operates to surround the optical fiber drawn downward from the coating device and irradiates the optical fiber with ultraviolet light.

[0008] Fig. 1 is a schematic diagram of an optical fiber manufacturing apparatus according to an embodiment of the present disclosure; Fig. 2 is a cross-sectional view of an optical fiber according to an embodiment of the present disclosure; Fig. 3 is a configuration diagram of an ultraviolet irradiation device according to an embodiment of the present disclosure; Fig. 4 is a configuration diagram of an ultraviolet irradiation device according to an embodiment of the present disclosure;

[0009] (Problem to be Solved by the Present Disclosure) As described above, a drawing tower apparatus is composed of a series of processes for feeding optical fiber vertically downward, and therefore requires a certain height. However, the vertical space of the drawing tower in which the optical fiber manufacturing apparatus is installed is limited due to factors such as the layout of the factory and the building. As a result, there is sometimes a lack of space for the curing step of irradiating ultraviolet light in the resin coating step, which is the final step of the drawing tower, and it is difficult to ensure the time and irradiation energy required for curing.

[0010] That is, since the space for the curing process is limited, the number of ultraviolet irradiation devices (UV lamps, LEDs, etc.) that can be installed in that space is limited, resulting in insufficient ultraviolet irradiation power. In order to sufficiently cure the resin, there is a limit to increasing the drawing speed of the optical fiber.

[0011] To address the above-mentioned issues, the technology disclosed in Patent Document 1 has a configuration in which a secondary irradiation unit is disposed immediately before the winding drum to harden the resin, as shown in Figure 2 of Patent Document 1. However, there is a risk that the fiber coating may be deformed because the optical fiber comes into contact with the capstan and many rollers on the way to the winding drum.

[0012] Furthermore, when the ultraviolet irradiation device for the curing process is arranged in advance in the overall layout, there is a problem in that it is difficult to adjust the relative positional relationship between the running path of the optical fiber that has been wired and the ultraviolet irradiation device.

[0013] The present disclosure has been made in light of the above background and these actual circumstances, and aims to provide an optical fiber manufacturing apparatus and manufacturing method that can reliably perform a resin curing process in an optical fiber manufacturing apparatus with limited installation space, while also achieving productivity and layout flexibility.

[0014] (Effects of the Present Disclosure) According to the present disclosure, it is possible to provide an optical fiber manufacturing apparatus and manufacturing method that can reliably perform a resin curing process in an optical fiber manufacturing apparatus having limited installation space and a restricted drawing tower height, and that can improve productivity and layout flexibility by increasing the drawing speed.

[0015] (Description of Embodiments of the Present Disclosure) First, embodiments of the present disclosure will be listed and described. (1) An optical fiber manufacturing apparatus according to one embodiment of the present disclosure includes a drawing furnace that heats an optical fiber preform, a drawing tower including a coating unit that coats a drawn glass fiber with an ultraviolet curable resin, a roller directly below the drawing tower that changes the direction of a travel path of the coated optical fiber, a plurality of guide rollers that guide the optical fiber fed from the roller directly below the drawing tower, an ultraviolet irradiation device that irradiates the coated ultraviolet curable resin with ultraviolet rays to cure the ultraviolet curable resin, and a take-up unit that takes up the optical fiber guided by the guide roller, wherein the ultraviolet irradiation device is disposed downstream of the drawing tower and operates to form a state in which the travel path is exposed and a state in which the travel path is enclosed and ultraviolet rays are irradiated toward the travel path.

[0016] According to this configuration, the ultraviolet irradiation device can be operated to create two states: one in which the travel path is exposed, and one in which it surrounds the travel path and irradiates ultraviolet light toward the travel path. Therefore, after drawing, the ultraviolet irradiation device can be arranged to surround the resin-coated optical fiber. Therefore, the ultraviolet irradiation device can be installed not on the drawing tower, where space is limited, but on the path line (travel path) downstream of the tower. Furthermore, since space utilization can be improved, by installing an LED or the like to irradiate sufficient ultraviolet light to harden the resin, the drawing speed can be increased and productivity can be improved. Furthermore, since the ultraviolet irradiation device can be installed after confirming the position of the drawn optical fiber, ultraviolet light can be reliably irradiated.

[0017] The operation referred to here is sufficient if it can realize both a state in which the travel path is exposed and a state in which the travel path is enclosed and ultraviolet light is irradiated toward the travel path.

[0018] (2) In the optical fiber manufacturing apparatus of (1), the ultraviolet irradiation device may be configured to be disposed upstream of the roller just below the coating. With this configuration, the coating can be cured before contacting the roller just below the coating, thereby maintaining the outer shape of the optical fiber and suppressing deformation of the optical fiber during its subsequent travel path.

[0019] (3) In the optical fiber manufacturing apparatus of (1), the ultraviolet irradiation device may be configured to be disposed downstream of the roller just below. With this configuration, the optical fiber is cured to a minimum extent to suppress deformation before passing through the roller just below, and additional curing is performed after passing through the roller just below, thereby further improving productivity.

[0020] (4) In the optical fiber manufacturing apparatus described in (1) to (3) above, the operation can be configured such that the ultraviolet irradiation device can move between a position enclosing the travel path and a position exposing the travel path. According to this configuration, one operating mode of the ultraviolet irradiation device is that it can move between a position enclosing the travel path and a position exposing the travel path, thereby reliably irradiating ultraviolet light onto the resin of the drawn optical fiber. The movement here can be realized, for example, by dividing a rectangular parallelepiped housing containing an ultraviolet light source into two parts vertically along the drawing direction, moving the divided part to the position of the drawn optical fiber, and then moving the divided part to close the divided part and enclose the optical fiber, thereby performing two orthogonal linear movements. This operating mode (movement mode) allows the ultraviolet irradiation device to be installed in a small space even after the drawing tower is installed.

[0021] (5) In the optical fiber manufacturing apparatus according to 1(1) to 1(3), the ultraviolet irradiation device may be configured to be composed of two half-tubular housings, which are configured to open and close in a pivotal manner so that the travel path is exposed when the halves are split and ultraviolet light is irradiated toward the travel path when the halves are joined together. This configuration allows the ultraviolet irradiation device, which is composed of two half-tubular housings, to achieve a pivotal opening and closing operation, such that the travel path is exposed when the halves are split and ultraviolet light is irradiated toward the travel path when the halves are joined together, or a linear operation using a guide or the like. This configuration improves space utilization, and by providing an LED or the like for irradiating sufficient ultraviolet light to harden the resin, the drawing speed can be increased, thereby improving productivity.

[0022] (6) In the optical fiber manufacturing apparatus according to (1) to (3), the ultraviolet irradiation device may include an ultraviolet light source and a mirror, and the ultraviolet light source and the mirror may be arranged so that ultraviolet light can be irradiated from all directions around the optical fiber in the travel path. According to this configuration, by providing the mirror that reflects ultraviolet light together with the irradiation device, unevenness in the irradiated ultraviolet light is eliminated, and reliable curing of the resin can be expected, while energy can be used efficiently.

[0023] (7) In the optical fiber manufacturing apparatus according to (1) to (3) above, the ultraviolet light source of the ultraviolet irradiation device may be a light-emitting diode (LED). According to this configuration, by using an LED as the light source for irradiating ultraviolet light, it is possible to, for example, use air cooling, thereby making it possible to reduce the installation space. Furthermore, with regard to the relative position between the ultraviolet irradiation light source and the drawn optical fiber, it is desirable that the base portion on which the light source is mounted has a mechanism for finely adjusting the horizontal position and a mechanism for adjusting the perpendicularity to the fiber, in order to efficiently impart ultraviolet irradiation power to the optical fiber.

[0024] (8) An optical fiber manufacturing method according to one embodiment of the present disclosure is a method for manufacturing an optical fiber using an optical fiber manufacturing apparatus having, in order: a drawing furnace for heating an optical fiber preform; a coating device for coating a drawn glass fiber with resin; a roller directly below for changing the direction of the running line of the coated optical fiber; a plurality of guide rollers for guiding the optical fiber sent from the roller directly below; and a take-up device for taking up the optical fiber guided by the guide roller, characterized in that after the drawn optical fiber is arranged at all steps of the running path of the optical fiber manufacturing apparatus, an ultraviolet irradiation device operates to surround the optical fiber drawn downward from the coating device and irradiates the optical fiber with ultraviolet light.

[0025] According to this optical fiber manufacturing method, after the drawn optical fiber has been arranged along the entire travel path of the manufacturing apparatus, an ultraviolet irradiation device can be operated to surround the optical fiber drawn downward from the coating device. Therefore, the ultraviolet irradiation device can be arranged to surround the resin-coated optical fiber after drawing. Therefore, the ultraviolet irradiation device can be installed not on the drawing tower, which has limited space, but on the path line (travel path) downstream of the drawing tower. Furthermore, since space utilization can be improved, by installing an LED or the like to irradiate sufficient ultraviolet light to harden the resin, the drawing speed can be increased and productivity can be improved. Furthermore, since the ultraviolet irradiation device can be arranged after the position of the drawn optical fiber is confirmed, ultraviolet light can be reliably irradiated.

[0026] (Details of the embodiment of the present disclosure) A specific example of an optical fiber manufacturing apparatus according to the present disclosure will now be described with reference to the drawings. Fig. 1 is a schematic diagram of an optical fiber manufacturing apparatus according to one aspect of the present disclosure. Fig. 2 is a cross-sectional view of an optical fiber according to one aspect of the present disclosure. As shown in Fig. 1, the optical fiber manufacturing apparatus 10 includes, at its most upstream position, a drawing furnace 11 that heats and softens an optical fiber preform G.

[0027] The drawing furnace 11 has a cylindrical furnace tube 12 into which the optical fiber preform G is supplied, a heating element 13 surrounding the furnace tube 12, and a gas supply unit 14 for supplying, for example, argon gas into the furnace tube 12. As a result, the atmosphere inside the furnace is filled with Ar, He, N ２ The drawing furnace 11 may be a resistance furnace or an induction furnace.

[0028] The upper portion of the optical fiber preform G is held by a preform feeding unit F, and the optical fiber preform G is fed into the furnace tube 12 by the preform feeding unit F. When the lower end portion of the optical fiber preform G is heated by the heating element 13 and drawn downward, a glass fiber G1, which is a component of the optical fiber G2, is formed.

[0029] The optical fiber manufacturing apparatus 10 includes a cooling unit 15 downstream of the drawing furnace 11. A cooling gas, such as helium gas, is supplied to the cooling unit 15, and the glass fiber G1 drawn from the optical fiber preform G is cooled by the cooling unit 15.

[0030] The optical fiber manufacturing apparatus 10 includes an outer diameter measuring unit 16 downstream of the cooling unit 15. The outer diameter measuring unit 16 is configured to be able to measure the outer diameter of the glass fiber G1 using, for example, laser light, and the glass fiber G1 cooled by the cooling unit 15 has its outer diameter measured by the outer diameter measuring unit 16 before being sent downward. Note that the outer diameter measuring unit 16 may use a measurement method other than laser light as long as it can measure the outer diameter of the glass fiber G1 in a non-contact manner.

[0031] The optical fiber manufacturing apparatus 10 in this embodiment includes a UV resin applicator 17a and a UV curing oven 17b downstream of the outer diameter measurement unit 16. The glass fiber G1, whose outer diameter has been measured, is coated with, for example, an ultraviolet-curable resin (also referred to as UV resin) such as urethane acrylate resin in the UV resin applicator 17a. The urethane acrylate resin is then irradiated with ultraviolet light in the UV curing oven 17b to harden. This results in an optical fiber G2 in which a resin layer is formed around the glass fiber G1. However, in this curing process, it is difficult to provide a UV curing oven 17b capable of sufficient ultraviolet irradiation in the drawing tower, as mentioned above, due to the limited space available. Therefore, it is anticipated that the resin applied to the optical fiber G2 in this state will be in a semi-cured state.

[0032] In this embodiment, the drawing tower 20 refers to an apparatus that includes a series of processes leading up to the formation of the optical fiber G2. Also, while a typical drawing tower has been described as including a UV resin applicator 17a and a UV curing oven 17b, the ultraviolet irradiation apparatus 32 according to the present disclosure differs from the UV curing oven 17b in the drawing tower 20 in that it irradiates ultraviolet light onto the optical fiber G2 delivered from the drawing tower 20. In another embodiment, it is also possible to omit the UV curing oven 17b in the drawing tower 20 and instead provide a plurality of ultraviolet irradiation apparatuses 32 according to the present disclosure.

[0033] The UV resin applicator 17a will be further described. The UV resin applicator 17a is an apparatus for applying uncured ultraviolet curable resin to the surface of the glass fiber G1 to form the first coating 52 and the second coating 54 shown in Fig. 2. In this embodiment, the UV resin applicator 17a is a double coating die in which two coating dies are provided one on top of the other.

[0034] The UV resin application device 17a is equipped with an application die that applies resin to form a first coating 52 (primary: hardened inner layer resin) on the upstream side and a second coating 54 (secondary: hardened outer layer resin) on the downstream side.

[0035] First, an upstream coating die applies an uncured ultraviolet curable resin to the surface of the glass fiber G1 to form the first coating 52, and then a downstream coating die applies an uncured ultraviolet curable resin to the outer surface of the first coating 52 to form the second coating 54. As a result, the glass fiber G1 is coated with both the first coating 52 and the second coating 54 in an uncured state, as shown in FIG.

[0036] Next, the glass fiber G1 passes through a UV curing oven 17b provided in the drawing tower 20 to cure the resin of the first coating 52 and the second coating 54. After the glass fiber G1 has been converted into an optical fiber G2 with a resin layer formed around it, the optical fiber G2 is sent out from the drawing tower 20 to the next process.

[0037] The optical fiber G2 is sent out from the drawing tower 20, and after the drawn optical fiber G2 has been arranged in all processes of the travel path from the ultraviolet irradiation device 32 onwards, the position of the drawn optical fiber G2 is confirmed. Thereafter, the ultraviolet irradiation device 32 moves from a position where the travel path is exposed to a position where it surrounds the optical fiber drawn downward from the coating device consisting of the UV resin applicator 17a and the UV curing furnace 17b, and irradiates the optical fiber G2 with ultraviolet light.

[0038] The operation referred to here is sufficient if it can achieve both states: a state in which the travel path is exposed, and a state in which the travel path is enclosed and ultraviolet rays are irradiated toward the travel path.For example, it can be a rotating opening and closing operation in which two half-tube ultraviolet irradiation devices are used, exposing the travel path when in the split state, and irradiating ultraviolet rays toward the travel path when both halves are joined, or it can be a linear operation using a guide, etc.

[0039] Generally, the only way to complete the curing of the glass fiber G2 at this point and prevent deformation of the periphery in the subsequent steps is to reduce the drawing speed or increase the power of the light source such as an LED. In contrast, in this embodiment, the ultraviolet irradiation device 32 described below is provided in the subsequent step of the drawing tower 20, so that even if the resin is, for example, semi-cured, the first coating 52 and the second coating 54 can be reliably cured in the subsequent step.

[0040] The ultraviolet irradiation after the drawing tower 20 can be carried out in air because most of the resin, including the secondary resin of the second coating 54, has already been cured by the light source installed in the tower, and when curing the primary resin of the first coating 52, it can be cured without contact with oxygen without the need for nitrogen purging or the like.

[0041] In this embodiment, the ultraviolet irradiation device 32 is provided directly below the fiber drawing tower 20. However, since the ultraviolet irradiation device 32 is separate from the fiber drawing tower 20, it is possible to not only place it directly below the tower 20, but also to place multiple devices just before the bobbin B that serves as the winding drum, as disclosed in Patent Document 1, or in locations where there is ample space in the travel path between the roller 34 directly below and the bobbin B.

[0042] The optical fiber manufacturing apparatus 10 includes a direct below roller 34 and, for example, nine guide rollers 36a to 36i downstream of the drawing tower 20. The direct below roller 34 is disposed directly below the drawing tower 20 and the ultraviolet irradiation device 32, and changes the running direction of the optical fiber G2 from a vertical direction to, for example, a horizontal direction.

[0043] The optical fiber G2, whose running direction has been changed by the immediately below roller 34, is guided by the guide rollers 36a to 36i, and its running direction is changed from horizontal to, for example, obliquely upward by the guide roller 36i located at the most downstream side.

[0044] The optical fiber manufacturing apparatus 10 further includes a take-up device 40, a guide roller 41, a dancer roller 42, and a winding device 43 downstream of the guide roller 36i. The optical fiber G2 is taken up at a predetermined speed by the capstan of the take-up device 40 and wound onto the bobbin B of the winding device 43 via the dancer roller 42. The take-up device 40 corresponds to the take-up section of the present disclosure. The take-up device is a device that first pulls the optical fiber G2 having a resin layer formed around the glass fiber G1.

[0045] (Explanation of an embodiment of an ultraviolet irradiation device) Next, an embodiment of an ultraviolet irradiation device of an optical fiber manufacturing apparatus according to the present disclosure will be described. Figures 3A to 3C are configuration diagrams of an ultraviolet irradiation device according to one aspect of the present disclosure, showing an ultraviolet irradiation device 32 disposed directly below the drawing tower 20 side of Figure 1, with Figure 3A illustrating the overall configuration of the ultraviolet irradiation device 32 and Figures 3B and 3C illustrating the manner of movement (operation). Note that Figures 3A to 3C omit mechanisms and the like provided on the travel path of the optical fiber G2, and merely illustrate the relationship between the optical fiber G2 and the ultraviolet irradiation device 32.

[0046] The movement (operation) mode shown in Figures 3A to 3C is an example of an operation in which a rectangular parallelepiped housing equipped with an ultraviolet light source inside is divided into two parts in the vertical direction along the drawing, and the divided part is moved to the position of the drawn optical fiber, and then moved to close the divided part and surround the optical fiber, performing two linear movements that are perpendicular to each other, and will be described in detail below.

[0047] First, we will explain the configuration of the ultraviolet irradiation device 32. The ultraviolet irradiation device 32 includes an LED irradiator 100 and a mirror unit 150. The LED irradiator 100 can be a housing having an LED element 110 on one side thereof that irradiates ultraviolet light onto the optical fiber G2.

[0048] Air cooling is preferable as a cooling method for the LED elements 110, since water cooling requires cooling piping and is not suitable for small spaces. The LED irradiator 100 preferably has a mechanism for finely adjusting the horizontal position and a mechanism for adjusting the perpendicularity to the fiber in order to adjust the ultraviolet irradiation position.

[0049] The LED irradiator 100 includes a first rail guide 120, a second rail guide 130, and a ball catcher 160, which are used for movement and coupling with a mirror unit 150, which will be described later.

[0050] The mirror unit 150 is provided with a mirror 152 at a position facing the LED element 110 of the LED irradiator 100. The mirror 152 can be a concave mirror curved so as to converge the ultraviolet light emitted from the LED element 110 into the optical fiber G2.

[0051] In addition, the mirror unit 150 is provided with a first rail guide 120, a second rail guide 130, and a ball 162 corresponding to the ball catcher 160 that cooperate with the LED irradiator 100 to determine their connection with the LED irradiator 100 and their relative positional relationship.

[0052] Next, the movement modes will be described with reference to Figures 3A through 3C. The state indicated by X in Figure 3A indicates a state in which drawing has begun, the optical fiber G2 has been sent out from the drawing tower 20, and the travel path has been determined. At this time, the ultraviolet irradiation device 32 is located at a position separated from the drawn optical fiber G2, allowing the state of the drawn optical fiber G2 to be visually confirmed.

[0053] After the drawing state of the optical fiber G2 has been confirmed, the LED irradiator 100 moves in the direction of the arrow M1 using the second rail guide 130 as a guide, as shown in Figure 3B, and transitions from the X state to the Y state. In the Y state, the optical fiber G2 is directly facing the LED element 110. Because the relative positions of the optical fiber G2 and the LED irradiator 100 are known in advance, no devices or the like come into contact with the optical fiber G2.

[0054] 3C, after the LED irradiator 100 moves to a position where the optical fiber G2 and the LED element 110 are directly opposite each other, the mirror unit 150 moves in the direction of arrow M2 using the first rail guide 120 as a guide, transitioning from state Y to state Z. After that, after fine adjustment of the mirror unit 150, ultraviolet light R is irradiated from the LED irradiator 100 onto the optical fiber G2 to harden the resin.

[0055] In this embodiment, in order to ensure that the ball is moved to the facing position, the ball catcher 160 is provided with a mechanism for holding the ball 162.

[0056] As described above, the ultraviolet irradiation device 32 according to this embodiment is composed of the LED irradiator 100 and the mirror unit 150, and the mirror unit 150 has a mechanism for opening and closing by a slide mechanism. Furthermore, the ultraviolet irradiation device 32 as a whole is configured to have a base with a slide mechanism for adjustment, and if there is a risk that the LED irradiator 100 will interfere with the optical fiber G2, it can move to the standby position X to avoid interference.

[0057] The present disclosure is not limited to the above-described embodiment and may be modified within the spirit and scope of the present disclosure. For example, the ultraviolet irradiation device 32 may operate not only by linear sliding but also by pivoting. Furthermore, since the ultraviolet irradiation device according to the present disclosure is configured as a separate unit from the drawing tower, it can be appropriately disposed in a location on the travel path after the drawing tower where space is available and where the resin can be cured efficiently. Furthermore, it is also possible to dispose of multiple ultraviolet irradiation devices 32 according to the present disclosure without installing a UV curing oven in the drawing tower.

[0058] 10...optical fiber manufacturing apparatus, 11...drawing furnace, 12...furnace tube, 13...heating element, 14...gas supply unit, 15...cooling unit, 16...outer diameter measurement unit, 17a...UV resin application device, 17b...UV curing furnace, 20...drawing tower, 32...ultraviolet irradiation device, 52...first coating, 54...second coating, 100...LED irradiator, 110...LED element, 120...first rail guide, 130...second rail guide, 150...mirror unit, 160...ball catcher, 162...ball, 34...directly below roller, 36a to 36i...guide roller, 40...take-up device, 41...guide roller, 42...dancer roller, 43...winding device, F...base material feeding unit, G...optical fiber base material, G1...glass fiber, G2...optical fiber, B...bobbin.

Claims

1. An optical fiber manufacturing apparatus comprising: a drawing furnace for heating an optical fiber preform; a drawing tower including a coating section for coating the drawn glass fiber with ultraviolet curing resin; a direct below roller for changing the direction of the travel path of the coated optical fiber; a plurality of guide rollers for guiding the optical fiber sent from the direct below roller; an ultraviolet irradiation device for irradiating the applied ultraviolet curing resin with ultraviolet light to harden the ultraviolet curing resin; and a take-up section for taking up the optical fiber guided by the guide roller, wherein the ultraviolet irradiation device is disposed downstream of the drawing tower and operates to form a state in which the travel path is exposed and a state in which the travel path is enclosed and ultraviolet light is irradiated toward the travel path.

2. The optical fiber manufacturing apparatus according to claim 1, wherein said ultraviolet ray irradiation device is disposed upstream of said roller just below said optical fiber.

3. The optical fiber manufacturing apparatus according to claim 1, wherein said ultraviolet ray irradiation device is disposed downstream of said roller immediately below.

4. An optical fiber manufacturing apparatus as claimed in any one of claims 1 to 3, wherein the operation comprises moving the ultraviolet irradiation device between a position enclosing the travel path and a position exposing the travel path.

5. An optical fiber manufacturing apparatus as claimed in any one of claims 1 to 3, wherein the ultraviolet ray irradiation device is composed of two half-split tubular housings, which expose the travel path when in a split state, and which rotate to open and close when both halves are joined together so as to irradiate ultraviolet rays toward the travel path.

6. An optical fiber manufacturing apparatus as claimed in any one of claims 1 to 3, wherein the ultraviolet irradiation device includes an ultraviolet light source and a mirror, and the ultraviolet light source and the mirror are arranged so that ultraviolet light can be irradiated from all directions around the optical fiber in the travel path.

7. An optical fiber manufacturing apparatus according to any one of claims 1 to 3, wherein the ultraviolet light source of said ultraviolet irradiation device is a light emitting diode.

8. A method for manufacturing an optical fiber by using an optical fiber manufacturing apparatus having, in order, a drawing furnace for heating an optical fiber preform, a coating device for coating a drawn glass fiber with resin, a direct below roller for changing the direction of the running line of the coated optical fiber, a plurality of guide rollers for guiding the optical fiber sent from the direct below roller, and a take-up device for taking up the optical fiber guided by the guide roller, in which, after the drawn optical fiber has been arranged at all steps of the running path of the optical fiber manufacturing apparatus, an ultraviolet irradiation device operates to surround the optical fiber drawn downward from the coating device and irradiate the optical fiber with ultraviolet light.

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