Method for manufacturing optical fiber and apparatus for manufacturing optical fiber

Abstract

To provide a method for manufacturing an optical fiber and an apparatus for manufacturing an optical fiber capable of improving responsiveness of changing a feed rate of an optical fiber preform to a drawing furnace in accordance with a change in an amount of melting of the optical fiber preform.SOLUTION: A method for manufacturing an optical fiber from an optical fiber preform, comprises steps of: placing the optical fiber preform in a feeder and feeding it into a drawing furnace; melting and drawing the optical fiber preform in the drawing furnace; measuring an outer diameter D of the drawn optical fiber; and taking up the drawn optical fiber, wherein a target value DG of the outer diameter of the optical fiber is preset, a take-up speed VL, which is a speed for taking up the optical fiber in the take-up step, is controlled based on the outer diameter D measured in the measuring step, and a feed speed VG, which is a speed for feeding the optical fiber preform into the drawing furnace in the feeding step, is controlled so that the outer diameter D matches the target value DG.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] In the method for manufacturing an optical fiber described in Patent Document 1, when drawing the optical fiber, the supply speed, which is the speed at which the optical fiber preform is fed into the drawing furnace, is controlled based on the drawing speed of the optical fiber, which is the line speed. Specifically, the difference between the current line speed of the optical fiber and the line speed a certain time ago is calculated, and the supply speed of the optical fiber preform is controlled based on the difference between the difference and the target value of the difference.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method for manufacturing an optical fiber described in Patent Document 1, the supply speed of the optical fiber preform is controlled based on the acceleration of the line speed of the optical fiber. However, the line speed of this optical fiber is controlled so that the outer diameter of the drawn optical fiber becomes the target outer diameter. This control of the line speed is performed so that the change in the outer diameter is relatively gentle, mainly using an integration operation, in order to suppress an unnecessary influence on the outer diameter due to a sudden change in the line speed. Therefore, in the method for manufacturing an optical fiber described in Patent Document 1, the control of the supply speed of the optical fiber preform is limited by the control of the line speed based on the outer diameter of the optical fiber. As a result, the response of the control of the supply speed becomes slow with respect to the change in the melting amount of the optical fiber preform in the drawing furnace, and the line speed may overshoot.

[0005] For example, when connecting and drawing two types of optical fiber preforms with different viscosities, if the interface of the connection part melts out, it is known that the melting amount of the optical fiber preform increases rapidly and the outer diameter of the optical fiber increases. At this time, when controlling the wire speed based on the outer diameter of the optical fiber, the increase in the wire speed is slower than the increase in the outer diameter of the optical fiber. Furthermore, since the supply speed of the optical fiber preform is controlled based on the wire speed of the optical fiber, the control of the supply speed lags behind the change in the wire speed. From the above, when the melting amount of the optical fiber preform increases rapidly, the control of the supply speed of the optical fiber preform lags significantly. As a result, the movement of pulling up the optical fiber preform from the drawing furnace is delayed, and the wire speed of the optical fiber may overshoot.

[0006] An object of the present disclosure is to provide a method for manufacturing an optical fiber and an apparatus for manufacturing an optical fiber that can improve the responsiveness of the change in the supply speed of the optical fiber preform to the drawing furnace with respect to the change in the melting amount of the optical fiber preform.

Means for Solving the Problem

[0007] A method for manufacturing an optical fiber according to an embodiment of the present disclosure is a method for manufacturing an optical fiber from an optical fiber preform, comprising a step of disposing the optical fiber preform in a feeder and feeding it into a drawing furnace, a step of melting and drawing the optical fiber preform in the drawing furnace, a step of measuring the outer diameter D of the drawn optical fiber, and a step of taking up the drawn optical fiber. A target value D G of the outer diameter of the optical fiber is preset. In the taking-up step, the taking-up speed V L , which is the speed of taking up the optical fiber, is controlled based on the outer diameter D measured in the measuring step. In the feeding step, the supply speed V G , which is the speed of feeding the optical fiber preform into the drawing furnace, is controlled so that the outer diameter D matches the target value D G .

[0008] A method for manufacturing an optical fiber according to an embodiment of the present disclosure is a method for manufacturing an optical fiber from an optical fiber preform, the method comprising: disposing the optical fiber preform in a feeder and feeding it into a drawing furnace; melting and drawing the optical fiber preform in the drawing furnace; measuring the outer diameter D of the drawn optical fiber; and taking up the drawn optical fiber. A target value D of the outer diameter of the optical fiber G is preset. In the taking-up step, a taking-up speed V L , which is the speed at which the optical fiber is taken up, is controlled based on the outer diameter D measured in the measuring step. In the feeding step, a calculated value D 2 V L and a target value D G 2 V L are derived, and a supply speed V G , which is the speed at which the optical fiber preform is fed into the drawing furnace, is controlled such that the calculated value D 2 V L matches the target value D G 2 V L .

[0009] An optical fiber manufacturing apparatus according to an embodiment of the present disclosure is a manufacturing apparatus for manufacturing an optical fiber by heating and drawing an optical fiber preform. The manufacturing apparatus includes a drawing furnace that heats and melts the optical fiber preform, a feeder that feeds the optical fiber preform into the drawing furnace, an outer diameter measuring device that measures the outer diameter D of the drawn optical fiber, a take-up machine that takes up the optical fiber, and a control device that controls a supply speed V G which is the speed at which the optical fiber preform is fed into the drawing furnace, and a take-up speed V L which is the speed at which the optical fiber is taken up. The control device includes an acquisition unit that acquires the outer diameter D of the optical fiber, a setting unit that sets a target value D G of the outer diameter of the optical fiber, and a control unit that controls the take-up speed V L based on the outer diameter D and controls the supply speed V G such that the outer diameter D matches the target value D G .

[0010] The optical fiber manufacturing apparatus according to an embodiment of the present disclosure is a manufacturing apparatus that manufactures an optical fiber by heating and drawing an optical fiber preform. This manufacturing apparatus includes a drawing furnace that heats and melts the optical fiber preform, a feeder that feeds the optical fiber preform into the drawing furnace, an outer diameter measuring device that measures the outer diameter D of the drawn optical fiber, a take-up machine that takes up the optical fiber, and a supply speed V that is the speed at which the optical fiber preform is fed into the drawing furnace G and a take-up speed V that is the speed at which the optical fiber is taken up L and a control device that controls them. This control device includes an acquisition unit that acquires the outer diameter D of the optical fiber, a setting unit that sets a target value D G of the outer diameter of the optical fiber, controls the take-up speed V L based on the outer diameter D, and derives a calculated value D 2 V L and the target value D G 2 V L and controls the supply speed V G so that the calculated value D 2 V L matches the target value D G 2 V L . It has a control unit

Advantages of the Invention

[0011] According to the present disclosure, it is possible to provide an optical fiber manufacturing method and an optical fiber manufacturing apparatus that can improve the responsiveness of changing the supply speed of the optical fiber preform to the drawing furnace to changes in the melting amount of the optical fiber preform

Brief Description of the Drawings

[0012]

Figure 1

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Figure 5

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Figure 8

[0013] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments of the present disclosure will be listed and described. [1] A method for manufacturing an optical fiber according to an embodiment is a method for manufacturing an optical fiber from an optical fiber preform, including a step of disposing the optical fiber preform in a feeder and feeding it into a wire drawing furnace, a step of melting and wire drawing the optical fiber preform in the wire drawing furnace, a step of measuring the outer diameter D of the wire-drawn optical fiber, and a step of taking up the wire-drawn optical fiber. A target value D of the outer diameter of the optical fiber is preset. In the taking-up step, the take-up speed V, which is the speed at which the optical fiber is taken up, is controlled based on the outer diameter D measured in the measuring step. In the feeding step, the supply speed V, which is the speed at which the optical fiber preform is fed into the wire drawing furnace, is controlled so that the outer diameter D matches the target value D. G L G G

[0014] In this method for manufacturing an optical fiber, the supply speed V is such that the outer diameter D of the optical fiber matches the target value D. G G ​​​​​is controlled to match. Here, when the melting amount of the optical fiber preform increases, if the take-up speed V, which is the linear speed of the optical fiber, L is constant, the outer diameter of the optical fiber increases. Therefore, in the method for manufacturing an optical fiber according to the present embodiment, the supply speed V is controlled so that the outer diameter of the optical fiber matches the target value. G Therefore, the responsiveness of the change in the supply speed V to the change in the melting amount of the optical fiber preform can be improved. For example, the response speed of the supply speed V to the change in the melting amount of the optical fiber preform can be improved without relying on the control of the take-up speed V. G For example, the response speed of the supply speed V to the change in the melting amount of the optical fiber preform can be improved without relying on the control of the take-up speed V. G is improved without relying on the control of the take-up speed V. L is possible.

[0015] [2] The method for manufacturing an optical fiber according to an embodiment of the present disclosure is a method for manufacturing an optical fiber from an optical fiber preform, including a step of disposing the optical fiber preform in a feeder and feeding it into a wire drawing furnace, a step of melting and wire drawing the optical fiber preform in the wire drawing furnace, a step of measuring the outer diameter D of the wire-drawn optical fiber, and a step of taking up the wire-drawn optical fiber. The target value D G of the outer diameter of the optical fiber is preset. In the taking-up step, the take-up speed V, which is the speed at which the optical fiber is taken up, L is controlled based on the outer diameter D measured in the measuring step. In the feeding step, the calculated value D 2 V L and the target value D G 2 V L are derived, and the supply speed V, which is the speed at which the optical fiber preform is fed into the wire drawing furnace, G is controlled so that the calculated value D 2 V L matches the target value D G 2 V L .

[0016] In this method for manufacturing an optical fiber, the supply speed V G is such that the calculated value D 2 V L matches the target value D G 2 V Lis controlled to match. Here, the calculated value D 2 V L is a value proportional to the melting amount Q = πD 2 V L / 4 of the optical fiber preform. Therefore, the supply rate V G is controlled so that the melting amount of the optical fiber preform matches the target value of the melting amount. As a result, the responsiveness of the change in the supply rate V G to the change in the melting amount of the optical fiber preform can be improved.

[0017] [3] In the method for manufacturing an optical fiber according to [1] or [2] above, the target value D L of the outer diameter of the optical fiber is preset. In the drawing step, the drawing speed V L may be controlled based on the difference between the outer diameter D and the target value D L . In this case, in the control of the drawing speed V L , since the responsiveness of the change in the drawing speed V L to the change in the melting amount of the optical fiber preform is improved, the wire drawing of the optical fiber can be appropriately performed.

[0018] [4] In the method for manufacturing an optical fiber according to [3] above, the target value V1 of the drawing speed V L of the optical fiber is preset. In the feeding step, the target value D G is set to a value smaller than the target value D L when the drawing speed V L is larger than the target value V1, and is set to the same value as the target value D L when the drawing speed V L is the target value V1, and may be set to a value larger than the target value D L when the drawing speed V L is smaller than the target value V1. In this case, when the outer diameter D of the optical fiber approaches the target value D L , even when the outer diameter D of the optical fiber deviates slightly from the target value D L , the supply rate V G is controlled or the calculated value D G V 2 V Lbe the target value D G 2 V L such that the supply rate V G matches one of the controls is executed. As a result, the supply rate V G can be stably controlled. Note that the target value D L A value close to is, for example, 0.99 times or more and 1.01 times or less with respect to D L

[0019] [5] In the method for manufacturing an optical fiber according to [3] or [4] above, upper and lower limit values are preset for the value obtained by dividing the target value D G by the target value D L . In this case, when D G becomes a value greatly deviated from the target value D L , the supply rate V such that the outer diameter D of the optical fiber matches the target value D G control or the calculated value D G V 2 V L becomes a value greatly deviated from the target value D G 2 V L control of the supply rate V such that the outer diameter D of the optical fiber matches the target value D G can be executed more effectively. As a result, the response speed of the supply rate V G with respect to changes in the melting amount of the optical fiber preform can be improved. Note that a value greatly deviated from the target value D L is, for example, 0.99 times or less or 1.01 times or more with respect to D L

[0020] [6] The optical fiber manufacturing apparatus according to an embodiment of the present disclosure is a manufacturing apparatus that manufactures an optical fiber by heating and drawing an optical fiber preform. This manufacturing apparatus includes a drawing furnace that heats and melts the optical fiber preform, a feeder that feeds the optical fiber preform into the drawing furnace, an outer diameter measuring device that measures the outer diameter D of the drawn optical fiber, a take-up machine that takes up the optical fiber, and a supply rate V that is the speed at which the optical fiber preform is fed into the drawing furnace G and a take-up speed V that is the speed at which the optical fiber is taken up L ​​A control device for controlling; and. This control device includes an acquisition unit that acquires the outer diameter D of the optical fiber, and a target value D of the outer diameter of the optical fiber G A setting unit for setting, and a take-up speed V L Is controlled based on the outer diameter D, and the supply speed V G Is controlled so that the outer diameter D matches the target value D G And a control unit.

[0021] In this optical fiber manufacturing apparatus, the supply speed V G Is controlled so that the outer diameter D matches the target value D G Here, when the melting amount of the optical fiber preform increases, if the take-up speed V, which is the linear speed of the optical fiber, L Is constant, the outer diameter of the optical fiber increases. Therefore, in the optical fiber manufacturing method according to the present embodiment, the supply speed V G Is controlled so that the outer diameter D of the optical fiber matches the target value D G Therefore, the responsiveness of the supply speed V G To changes in the melting amount of the optical fiber preform can be improved. For example, the response speed of the supply speed V G To changes in the melting amount of the optical fiber preform can be improved without relying on the control of the take-up speed V L .

[0022] [7] An optical fiber manufacturing apparatus according to an embodiment of the present disclosure is an optical fiber manufacturing apparatus that manufactures an optical fiber by heating and drawing an optical fiber preform. This manufacturing apparatus includes a drawing furnace that heats and melts the optical fiber preform, a feeder that feeds the optical fiber preform into the drawing furnace, an outer diameter measuring device that measures the outer diameter D of the drawn optical fiber, a take-up machine that takes up the optical fiber, and a supply speed V G Which is the speed at which the optical fiber preform is fed into the drawing furnace, and a take-up speed V L Which is the speed at which the optical fiber is taken up, and a control device for controlling. This control device includes an acquisition unit that acquires the outer diameter D of the optical fiber, and a target value D of the outer diameter of the optical fiber G A setting unit for setting, and a take-up speed V L Is controlled based on the outer diameter D, and the calculated value D2 V L and target value D G 2 V L is derived to obtain the supply speed V G and the calculated value D 2 V L is such that the target value D G 2 V L matches, and has a control unit for controlling accordingly.

[0023] In this optical fiber manufacturing apparatus, the supply speed V G is such that the calculated value D 2 V L matches the target value D G 2 V L is controlled to match. Here, the calculated value D 2 V L is a value proportional to the melting amount Q = πD 2 V L / 4 of the optical fiber preform. Therefore, the supply speed V G is controlled such that the melting amount of the optical fiber preform matches the target value of that melting amount. As a result, the responsiveness of the change in the supply speed V G to changes in the melting amount of the optical fiber preform can be improved.

[0024] [Details of Embodiments of the Present Disclosure] Specific examples of the optical fiber manufacturing method and the optical fiber manufacturing apparatus according to the embodiments of the present disclosure will be described below with reference to the drawings. In the following description, the same reference numerals will be used for the same elements or elements having the same function, and duplicate descriptions will be omitted. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0025] [First Embodiment] (Optical Fiber Manufacturing Apparatus) Referring to FIG. 1, a wire drawing apparatus 10A (an optical fiber manufacturing apparatus) used in a method for manufacturing an optical fiber according to an embodiment will be described. FIG. 1 is a configuration diagram of the wire drawing apparatus 10A used in the method for manufacturing an optical fiber according to an embodiment. As shown in FIG. 1, the wire drawing apparatus 10A includes a feeder 11, a motor 12, a driver 13, a wire drawing furnace 14, an outer diameter measuring device 15, a cooler 16, a die 17, an ultraviolet irradiator 18, a directly-below guide roller 19, a capstan 20, a take-up machine 21, and a control device 30A. In the wire drawing apparatus 10A, an optical fiber preform P disposed in the feeder 11 is melted and wire drawn to form an optical fiber F.

[0026] The feeder 11 is a device for gripping the optical fiber preform P and feeding it into the wire drawing furnace 14 at a constant speed. The optical fiber preform P has a base end portion P1 gripped by the feeder 11 and a tip end portion P2 inserted into the wire drawing furnace 14. The feeder 11 is a supply device for supplying the optical fiber preform P to the wire drawing furnace 14. The motor 12 grips the feeder 11. When the motor 12 receives an electrical signal from the driver 13 and rotates, the feeder 11 moves to supply the optical fiber preform P to the wire drawing furnace 14. Hereinafter, the supply speed V at which the feeder 11 and the optical fiber preform P move G is the speed at which the optical fiber preform P is fed into the wire drawing furnace 14.

[0027] The wire drawing furnace 14 has an opening 14a into which the optical fiber preform P is inserted and an opening 14b that faces the opening 14a and from which the optical fiber preform P is drawn out as a fibrous optical fiber F1. The wire drawing furnace 14 heats and melts (softens) the tip end portion P2 of the optical fiber preform P supplied into the wire drawing furnace 14. From the tip end portion P2 melted by heating, a glass fiber-like optical fiber F1 is drawn out. The glass fiber-like optical fiber F1 is drawn out of the wire drawing furnace 14 through the opening 14b.

[0028] The outer diameter measuring device 15 measures the outer diameter D of the optical fiber F1 drawn out to the outside of the wire drawing furnace 14. The outer diameter measuring device 15 measures the outer diameter D by irradiating the optical fiber F1 with, for example, a laser. The outer diameter measuring device 15 transmits the measured outer diameter D to the control device 30A. The cooler 16 is arranged downstream of the outer diameter measuring device 15 and cools the fibrous optical fiber F1. Note that the outer diameter of the optical fiber F is measured by the outer diameter measuring device 15 after it has become constant due to the rapid cooling of the optical fiber F outside the wire drawing furnace 14.

[0029] The die 17 applies resin to the outer peripheral surface of the incoming optical fiber F1 to form a resin coating. The resin contains an acrylate-based ultraviolet curable resin. The ultraviolet irradiator 18 irradiates the coated resin formed on the optical fiber F1 with ultraviolet rays to cure the coated resin. Thereby, the optical fiber F2 is formed by coating the fiber with resin. The optical fiber F2 is sent by the directly-below guide roller 19 to the take-up machine 21 via the capstan 20. The capstan 20 pulls and takes up the optical fiber F2 at a predetermined speed and tension. Hereinafter, the take-up speed V L is the speed at which the capstan 20 takes up the optical fiber F2. The optical fiber F2 taken up by the capstan 20 is taken up by the take-up machine 21.

[0030] The control device 30A controls the supply speed V G at which the optical fiber base material P is fed into the wire drawing furnace 14 and the take-up speed V LControl it. The control device 30A may control the entire wire drawing device 10A. The control device 30A may be configured as a computer system including, for example, a processor such as a CPU (Central Processing Unit), a memory such as a RAM (Random Access Memory) and a ROM (Read Only Memory), an input / output device such as a touch panel, a mouse, a keyboard, a display, and a communication device such as a network card. The control device 30A realizes its functions by operating each hardware under the control of the processor based on a computer program stored in the memory.

[0031] (Configuration of Control Device 30A) FIG. 2 is a block diagram showing the functional configuration of the control device 30A. As shown in FIG. 2, the control device 30A includes an acquisition unit 31A that acquires the outer diameter D of the optical fiber F1, a setting unit 32A that sets the target values D G and D L of the outer diameter of the optical fiber F1, and a control unit 33A that controls the take-up speed V L and the supply speed V G . Note that the target value D L is the target value of the outer diameter D of the optical fiber F1 in the control of the take-up speed V L . The target value D G is the target value of the outer diameter D of the optical fiber F1 in the control of the supply speed V G , and is, for example, a value set based on the target value D L (described later).

[0032] The acquisition unit 31A acquires the outer diameter D of the optical fiber F1 from the outer diameter measuring device 15. The acquisition unit 31A acquires the take-up speed V L from the capstan 20. The acquisition unit 31A acquires the supply speed V G from the motor 12 via the driver 13. The acquisition unit 31A acquires the target value V1 of the take-up speed and the target value D L of the outer diameter of the optical fiber F1 from outside the wire drawing device 10A. The acquisition unit 31A acquires the outer diameter D of the optical fiber F1, the target value D L, take-up speed V L , and supply speed V G are output to the setting unit 32A and the control unit 33A. The acquisition unit 31A outputs the target value V1 of the take-up speed to the setting unit 32A.

[0033] The setting unit 32A obtains the outer diameter D of the optical fiber F1, the target value D L , take-up speed V L , supply speed V G , and the target value V1 of the take-up speed. The setting unit 32A sets the target value D G of the outer diameter of the optical fiber F1. Specifically, when the take-up speed V L is greater than the target value V1, the target value D L is set to a value smaller than the target value D G . When the take-up speed V L is equal to the target value V1, the target value D L is set to the same value as the target value D G . When the take-up speed V L is smaller than the target value V1, the target value D L is set to a value larger than the target value D G . Further, the setting unit 32A sets upper and lower limit values for the value obtained by dividing the target value D G by the target value D L .

[0034] FIG. 3 is a graph showing the relationship between the target value D L and the take-up speed V G when the target value D L is set. As an example, when the outer diameter D of the optical fiber F1 at the take-up speed V L is larger than the reference outer diameter D0 determined by the following formula (1) under the condition that the melting amount in the optical fiber base material P is the target value, the melting amount is excessive. When the outer diameter D of the optical fiber F1 is smaller than the reference outer diameter D0, the melting amount is insufficient. [Equation] Therefore, in the example shown in FIG. 3, the setting unit 32A sets the take-up speed V L when it is close to the target value V1, the target value D G is set as in the following formula (2-2). Also, when the difference between the take-up speed V L and the target value V1 is large, the setting unit 32A sets as in the following formulas (2-1) and (2-3). That is, for the target value D G , an upper limit value D L (1 + Δ1) and a lower limit value D L (1 - Δ2) are set. Note that Δ1 and Δ2 are preset minute limit values. For example, they may be numerical values from 0.001 times to 0.01 times, or from 0.002 times to 0.005 times, or, for example, a numerical value of about 0.003 times with respect to D L . [Number]

[0035] The control unit 33A controls the take-up speed V L based on the outer diameter D of the optical fiber F1. Specifically, the control unit 33A acquires the outer diameter D of the optical fiber F1 and the target value D L of the outer diameter of the optical fiber F1 from the acquisition unit 31A. The control unit 33A controls the take-up speed V L based on the difference between the outer diameter D of the optical fiber F1 and the target value D L of the outer diameter of the optical fiber F1. FIG. 4 is a circuit block diagram showing an arithmetic circuit for controlling the take-up speed V L and the supply speed V G in the control device 30A. In the example shown in FIG. 4, the control unit 33A performs PID control on the take-up speed V L so that it matches the target value D L of the outer diameter of the optical fiber F1.

[0036] In addition to the control of the take-up speed V L described above, the control unit 33A controls the supply speed V G based on the outer diameter D of the optical fiber F1Control it. Specifically, the control unit 33A performs PID control on the supply speed V so that the outer diameter D of the optical fiber F1 matches the target value D G In the example shown in FIG. 4, the control unit 33A performs PID control on the set value V of the speed at which the optical fiber preform P is fed into the wire drawing furnace 14 so that the outer diameter D of the optical fiber F1 matches the target value D G In the example shown in FIG. 4, the control unit 33A performs PID control on the set value V of the speed at which the optical fiber preform P is fed into the wire drawing furnace 14 so that the outer diameter D of the optical fiber F1 matches the target value D G In the example shown in FIG. 4, the control unit 33A performs PID control on the set value V of the speed at which the optical fiber preform P is fed into the wire drawing furnace 14 so that the outer diameter D of the optical fiber F1 matches the target value D f1 The control unit 33A adds the controlled set value V to the reference supply speed V f1 to output the supply speed V f2 The control of such a supply speed V is performed independently of the control of the take-up speed V G The reference supply speed V G represents the supply speed of the optical fiber preform P corresponding to the melting amount of the optical fiber preform P when the optical fiber F1 is taken up at the take-up speed V L and the outer diameter D of the optical fiber F1 is the target value D f2 The reference supply speed V L is calculated by the following formula (3) based on the take-up speed V G the outer diameter D of the optical fiber preform P f2 the outer diameter D of the optical fiber preform P L、 the outer diameter D of the optical fiber preform P P and the target value D of the optical fiber F1 G Next, with reference to FIG. 5, a method for manufacturing an optical fiber F from the optical fiber preform P using the above-described wire drawing device 10A will be described. FIG. 5 is a flowchart showing the method for manufacturing the optical fiber F. In this manufacturing method, the target value D of the outer diameter of the optical fiber

Equation

[0037] (Method for manufacturing optical fiber) Next, with reference to FIG. 5, a method for manufacturing an optical fiber F from the optical fiber preform P using the above-described wire drawing device 10A will be described. FIG. 5 is a flowchart showing the method for manufacturing the optical fiber F. In this manufacturing method, the target value D of the outer diameter of the optical fiber L is set in advance

[0038] First, an optical fiber preform P is placed on a feeder 11 of a wire drawing apparatus 10A and fed into a wire drawing furnace 14 (step S1). Next, the optical fiber preform P is melted in the wire drawing furnace 14, and an optical fiber F1 is wire drawn (step S2). Specifically, first, the optical fiber preform P is placed on the feeder 11. Next, a tip portion P2 of the optical fiber preform P is inserted into the wire drawing furnace 14, and the tip portion P2 of the optical fiber preform P is heated. Thereafter, when the tip portion P2 of the optical fiber preform P is sufficiently heated and melted, a fibrous optical fiber F1 is drawn out from the tip portion P2.

[0039] Subsequently, an outer diameter D of the wire drawn optical fiber F is measured by an outer diameter measuring device 15 (step S3). Finally, the optical fiber F is taken up by a take-up machine 21 (step S4). Specifically, the outer diameter D of the optical fiber F1 is measured by the outer diameter measuring device 15, and the optical fiber F1 is cooled by a cooler 16. Subsequently, a coating layer is formed on the optical fiber F by a die 17, and the coating layer is cured by ultraviolet rays by an ultraviolet irradiator 18 to obtain an optical fiber F2. The optical fiber F2 having the coating layer formed thereon is then wound up by the take-up machine 21 via a directly-below guide roller 19 and a capstan 20. Thereby, the optical fiber F is manufactured.

[0040] When the optical fiber F1 is fed (step S1), a setting unit 32A sets a target value D G Specifically, as shown in FIGS. 3 and 4, when a take-up speed V L is greater than a target value V1, the setting unit 32A sets the target value D L to a value smaller than the target value D G When the take-up speed V L is equal to the target value V1, the setting unit 32A sets the target value D L to the same value as the target value D G When the take-up speed V L is smaller than the target value V1, the setting unit 32A sets the target value D L to a value larger than the target value D G Furthermore, when the target value D G is the target value D LSet upper and lower limit values for the value divided by

[0041] When the optical fiber preform P is fed into the wire drawing furnace 14 (step S1), the control unit 33A controls the supply speed V based on the outer diameter D of the optical fiber F1 measured by the outer diameter measuring device 15 (step S3). G as described above. Specifically, the control unit 33A controls the supply speed V so that the outer diameter D of the optical fiber F1 matches the target value D of the outer diameter of the optical fiber F1. G G For example, the control unit 33A performs PID control on the supply speed V so that the outer diameter D of the optical fiber F1 matches the target value D of the outer diameter of the optical fiber F1. G G

[0042] When the optical fiber F2 is taken up (in step S4), the control unit 33A of the control device 30A controls the take-up speed V based on the outer diameter D of the optical fiber F1 measured by the outer diameter measuring device 15 (step S3). L as described above. Specifically, the control unit 33A controls the take-up speed V based on the difference between the outer diameter D of the optical fiber F1 and the target value D of the outer diameter of the optical fiber F1. L L

[0043] Hereinafter, the effects of the method for manufacturing an optical fiber according to the present embodiment will be described in comparison with a comparative example. In this comparative example, the target value of the acceleration a of the take-up speed V is set based on the take-up speed V. L And the supply speed V is controlled so that the target value of the above acceleration becomes 0 at the target value V1 of the take-up speed V. FIG. 6 is a circuit block diagram of an arithmetic circuit for controlling the take-up speed V and the supply speed V in the wire drawing device according to the comparative example. As shown in FIG. 6, the target value a of the acceleration of the take-up speed V is a preset acceleration value a. L G L L G and the supply speed V. As shown in FIG. 6, the target value a of the acceleration of the take-up speed V is a preset acceleration value a. L t g ​​​​​​​​​​​From the take-up speed V L The value obtained by time-differentiating (dV L / dt) is subtracted. The target value a t of the acceleration is set to 0, and the set value V f1 is PID-controlled. Based on the set value V f1 , the reference supply speed V f2 is added to obtain the supply speed V G . The reference supply speed V f2 is such that when the optical fiber F1 is taken up at the take-up speed V L and the outer diameter D of the optical fiber F1 is the target value D L , it indicates the supply speed of the optical fiber preform P corresponding to the melting amount of the optical fiber preform P. The reference supply speed V f2 is calculated by the following formula (4) based on the take-up speed V L、 , the outer diameter D P of the optical fiber preform P, and the target value D L of the optical fiber F1.

Equation

[0044] Furthermore, with respect to changes in the melting amount of the optical fiber preform in the drawing furnace, there is a problem that the response of the control of the supply speed V G becomes slow, and the take-up speed V L overshoots. For example, when drawing by connecting two types of optical fiber preforms with different viscosities, when the interface of the connection part melts out, it is known that the melting amount of the optical fiber preform increases rapidly and the outer diameter of the optical fiber increases. At this time, when controlling the take-up speed V L based on the outer diameter of the optical fiber, the take-up speed V LThe increase is slower than the increase in the outer diameter of the optical fiber. Further, the supply speed V G is controlled based on the take-up speed V L . Therefore, the control of the supply speed V G lags behind the change in the take-up speed V L . From the above, when the melt amount of the optical fiber preform rapidly increases, the control of the supply speed V G lags significantly. As a result, the movement of pulling up the optical fiber preform from the drawing furnace is delayed, and the take-up speed V L may overshoot.

[0045] In contrast to the above comparative example, in the method for manufacturing an optical fiber according to the present embodiment, the supply speed V G is controlled so that the outer diameter D of the optical fiber F1 matches the target value D G . Here, when the melt amount of the optical fiber preform P increases, if the take-up speed V L which is the linear speed of the optical fiber F is constant, the outer diameter D of the optical fiber F1 increases. Therefore, in the method for manufacturing an optical fiber according to the present embodiment, since the supply speed V G is controlled so that the outer diameter D of the optical fiber F1 matches the target value D G , the responsiveness of the change in the supply speed V G to the change in the melt amount of the optical fiber preform P can be improved. For example, it becomes possible to improve the response speed of the supply speed V G to the change in the melt amount of the optical fiber preform P without relying on the control of the take-up speed V L . Also, for example, when the melt amount of the optical fiber preform P rapidly increases and the outer diameter of the optical fiber F increases, it becomes possible to quickly pull up the optical fiber preform P from the drawing furnace 14, and it becomes possible to suppress the take-up speed V L from overshooting. Further, since the time taken for the increase or decrease of the supply speed V G is reduced, the yield is improved.

[0046] Also, in the method for manufacturing an optical fiber according to the present embodiment, the target value D of the outer diameter of the optical fiber F1 Lis preset, and in the take-up process, the take-up speed V L is controlled based on the difference between the outer diameter D and the target value D L . In this case, in the control of the take-up speed V L , the responsiveness of the change in the take-up speed V L to the change in the melting amount of the optical fiber preform P is improved, so that the wire drawing of the optical fiber F can be appropriately performed.

[0047] Also, in the method for manufacturing an optical fiber according to the present embodiment, the target value V1 of the take-up speed V L of the optical fiber F2 is preset, and in the feeding process, the target value D G is set to a value smaller than the target value D L when the take-up speed V L is larger than the target value V1, and is set to the same value as the target value D L when the take-up speed V L is the target value V1, and is set to a value larger than the target value D L when the take-up speed V L is smaller than the target value V1. In this case, when the outer diameter D of the optical fiber F1 becomes a value close to the target value D L , even if the outer diameter D of the optical fiber F1 deviates slightly from the target value D L , control is executed so that the outer diameter D of the optical fiber F1 matches the target value D G . As a result, the supply speed V G can be stably controlled. Note that the value close to the target value D L is, for example, D L (1 - Δ2) or more and D L (1 + Δ1) or less.

[0048] Also, in the method for manufacturing an optical fiber according to the present embodiment, upper and lower limit values are preset for the value obtained by dividing the target value D G by the target value D L . In this case, when D G becomes a value greatly deviated from the target value D L , the supply speed V such that the outer diameter D of the optical fiber F1 matches the target value D G ​G can be executed more effectively. As a result, the response speed of the supply rate V with respect to the change in the melting amount of the optical fiber preform P G can be improved. Note that a value that deviates significantly from the target value D L is, for example, a value smaller than D L (1 - Δ2) or a value larger than D L (1 + Δ1).

[0049] In addition, the optical fiber manufacturing apparatus according to the present embodiment is a drawing device 10A that manufactures an optical fiber F by heat-drawing an optical fiber preform P. This drawing device 10A includes a drawing furnace 14 that melts the optical fiber preform P, a feeder 11 that feeds the optical fiber preform P into the drawing furnace 14, an outer diameter measuring device 15 that measures the outer diameter D of the drawn optical fiber F1, a take-up machine 21 that takes up the optical fiber F2, and a supply rate V that is the rate at which the optical fiber preform P is fed into the drawing furnace 14 G and a take-up rate V that is the rate at which the optical fiber F is taken up L and a control device 30A that controls them. This control device 30A includes an acquisition unit 31A that acquires the outer diameter D of the optical fiber F, a setting unit 32A that sets a target value D for the outer diameter of the optical fiber F G , and a control unit 33A that controls the take-up rate V based on the outer diameter D and controls the supply rate V L so that the outer diameter D matches the target value D G . G

[0050] In this optical fiber manufacturing apparatus, the supply rate V G is controlled so that the outer diameter D matches the target value D G . Here, when the melting amount of the optical fiber preform P increases, if the take-up rate V, which is the linear velocity of the optical fiber F2, is constant, the outer diameter D of the optical fiber F1 increases. Therefore, in the optical fiber manufacturing method according to the present embodiment, since the supply rate V is controlled so that the outer diameter D of the optical fiber F1 matches the target value D L , the response speed of the supply rate V with respect to the change in the melting amount of the optical fiber preform P G is improved. G G ​​The responsiveness to changes can be improved. For example, the response speed of the supply speed V with respect to the change in the melting amount of the optical fiber preform P G can be improved without relying on the control of the take-up speed V L .

[0051] [Second Embodiment] (Optical Fiber Manufacturing Apparatus) With reference to FIGS. 1, 7, and 8, a second embodiment of the optical fiber manufacturing method and the optical fiber manufacturing apparatus will be described. FIG. 7 is a block diagram showing the functional configuration of the control device 30B of the wire drawing device 10B according to the second embodiment. FIG. 8 is a circuit block diagram of an arithmetic circuit that controls the take-up speed V L and the supply speed V G . In the following description, the differences from the above-described embodiment will be mainly described, and the common points may be omitted from the description.

[0052] The wire drawing device 10B according to the second embodiment includes, in the same manner as the wire drawing device 10A, a feeder 11, a motor 12, a driver 13, a wire drawing furnace 14, an outer diameter measuring device 15, a cooler 16, a die 17, an ultraviolet irradiator 18, a directly-below guide roller 19, a capstan 20, a take-up machine 21, and a control device 30B (see FIG. 1). In the wire drawing device 10B, in the same manner as the wire drawing device 10A, the optical fiber preform P disposed in the feeder 11 is melted and wire-drawn to form the optical fiber F.

[0053] The control device 30B controls the supply speed V G which is the speed at which the optical fiber preform P is fed into the wire drawing furnace 14, and the take-up speed V LThe control device 30B may control the entire wire drawing device 10B. The control device 30B may be configured as a computer system including, for example, a processor such as a CPU (Central Processing Unit), a memory such as a RAM (Random Access Memory) and a ROM (Read Only Memory), input / output devices such as a touch panel, a mouse, a keyboard, and a display, and a communication device such as a network card. The control device 30B realizes the functions of the control device 30B by operating each piece of hardware under the control of the processor based on a computer program stored in the memory.

[0054] As shown in FIG. 7, the control device 30B includes an acquisition unit 31B that acquires the outer diameter D of the optical fiber F1 and a target value D of the outer diameter of the optical fiber F1. G and D. L and a setting unit 32B for setting the take-up speed V L and the feed rate V G and a control unit 33B that controls the above.

[0055] The acquisition unit 31B, like the setting unit 32A, acquires the outer diameter D of the optical fiber F1 from the outer diameter measuring instrument 15. The acquisition unit 31B acquires the outer diameter D of the optical fiber F1 from the outer diameter measuring instrument 15. L is acquired from the capstan 20. The acquisition unit 31B acquires the supply speed V G is acquired from the motor 12. The acquisition unit 31B acquires the take-up speed V L The target value V1 of the outer diameter of the optical fiber F1 and the target value D L The acquisition unit 31B acquires the outer diameter D of the optical fiber F1 and the target value D L , take-up speed V L , and the feed rate V G to setting unit 32B and control unit 33B. Acquiring unit 31B outputs target value V1 of the take-up speed to setting unit 32B.

[0056] The setting unit 32B, like the setting unit 32A, sets the outer diameter D of the optical fiber F1 and the target value D L , take-up speed VL and obtain the supply speed V G and the target value V1 of the take-up speed. The setting unit 32B sets the target value D G . Specifically, similar to the setting unit 32A, when the take-up speed V L is greater than the target value V1, the setting unit 32B sets the target value D L to a value smaller than D G . When the take-up speed V L is equal to the target value V1, the setting unit 32A sets the target value D L to the same value as D G . When the take-up speed V L is smaller than the target value V1, the setting unit 32B sets the target value D L to a value greater than D G . Also, the setting unit 32B sets the upper limit value and the lower limit value for the target value D G .

[0057] As shown in FIG. 8, when the take-up speed V L is close to the target value V1, the setting unit 32B sets the target value D G as shown in Equation (2-2). Also, when the take-up speed V L is close to the target value V1, the setting unit 32B sets it as shown in Equations (2-1) and (2-3). That is, the upper limit value and the lower limit value are set for the target value D G . [Number] Here, different from the setting unit 32A, the setting unit 32B substitutes the target value V1 of the take-up speed V 2 V L and the target value D of the outer diameter of the optical fiber F1 into D L V G π / 4 to set the target value Q G = D G 2 V1π / 4. At the same time, the setting unit 32B sets the upper limit value (D G (1 + Δ1)) L V1π / 4 of the target value Q 2 and the target value Q GThe lower limit value (D L (1 - Δ2)) 2 Set V1π / 4.

[0058] Similar to control unit 33A, control unit 33B controls the take-up speed V based on the outer diameter D of the optical fiber F1. L Specifically, control unit 33B acquires the outer diameter D of the optical fiber F1 and the target value D of the outer diameter of the optical fiber F1 from acquisition unit 31B. Control unit 33B controls the take-up speed V based on the difference between the outer diameter D of the optical fiber F1 and the target value D of the outer diameter of the optical fiber F1. In the example shown in FIG. 8, control unit 33B performs PID control on the take-up speed V so that the outer diameter D of the optical fiber F1 matches the target value D of the outer diameter of the optical fiber F1. L L L In the example shown in FIG. 8, control unit 33B performs PID control on the take-up speed V so that the outer diameter D of the optical fiber F1 matches the target value D of the outer diameter of the optical fiber F1. L L

[0059] Control unit 33B controls the supply speed V based on the outer diameter D of the optical fiber F1. G Specifically, control unit 33B acquires the target value Q G from setting unit 32B. Control unit 33B controls the supply speed V so that the melt amount Q = D 2 V L π / 4 matches the target value Q G and the melt amount Q = D 2 V L π / 4 of the optical fiber preform P matches the target value Q G of the melt amount of the optical fiber preform P. For example, control unit 33B performs PID control on the supply speed V so that the melt amount Q of the optical fiber preform P matches the target value Q G G In the example shown in FIG. 8, control unit 33B performs PID control on the set value V 2 of the speed at which the optical fiber preform P is fed into the wire drawing furnace 14 so that the melt amount Q = D L V G = D G 2 matches the target value Q f1 = D f1 f2 of the melt amount of the optical fiber preform P and is equal to V1π / 4. Control unit 33B controls the controlled set value V​​​​​By adding them together, the supply speed V G is output. The reference supply speed V f2 is the supply speed of the optical fiber preform P corresponding to the melting amount of the optical fiber preform P when the optical fiber F1 is drawn at the drawing speed V L and the outer diameter D of the optical fiber F1 is the target value D G . The drawing speed V L、 the outer diameter D of the optical fiber preform P P , and the target value D of the optical fiber F1 G are calculated by the following formula (5). [Number]

[0060] (Method for manufacturing optical fiber) The method for manufacturing an optical fiber according to the second embodiment is different from the method for manufacturing an optical fiber according to the first embodiment in that the control device 30B is used instead of the control device 30A. Other steps are the same as the steps shown in FIG. 5.

[0061] When the optical fiber F1 is fed (step S1 in FIG. 5), the setting unit 32B of the control device 30B sets the target value D L to a value smaller than the target value D L when the drawing speed V G is greater than the target value V1. The setting unit 32B sets the target value D L to the same value as the target value D L when the drawing speed V G is the target value V1. The setting unit 32B sets the target value D L to a value larger than the target value D L when the drawing speed V G is smaller than the target value V1. Further, the setting unit 32B sets an upper limit value and a lower limit value for the target value D G .

[0062] When the optical fiber F1 is fed in (step S1 in FIG. 5), the control unit 33B of the control device 30B controls the supply speed V based on the outer diameter D of the optical fiber F1 measured by the outer diameter measuring device 15 (step S3 in FIG. 5). G as described above. Specifically, the control unit 33B sets the melting amount Q = D 2 V L π / 4 of the optical fiber preform P, and controls the supply speed V so that the target value D G of the outer diameter and the target value V1 of the take-up speed are substituted into the function to obtain the target value Q G of the melting amount Q = D 2 V L π / 4. The control unit 33B performs PID control on the supply speed V so that the melting amount Q of the optical fiber preform P matches the target value Q G . G G

[0063] In the method for manufacturing an optical fiber according to the present embodiment, the supply speed V G is controlled such that the calculated value D 2 V L π / 4 matches the target value D G 2 V L π / 4. Here, since the calculated value D 2 V L π / 4 is the melting amount Q of the optical fiber preform, the supply speed V G is controlled such that the melting amount Q of the optical fiber preform matches the target value Q G of the melting amount. As a result, the responsiveness of the change in the supply speed V to the change in the melting amount of the optical fiber preform P can be improved. Note that the method for manufacturing an optical fiber according to the present embodiment has the same effects as the method for manufacturing an optical fiber according to the first embodiment described above. G

[0064] ​​​The fiber drawing apparatus according to this embodiment is a fiber drawing apparatus 10B that manufactures an optical fiber F by heating and drawing an optical fiber preform P. This fiber drawing apparatus 10B includes a fiber drawing furnace 14 that heats and melts the optical fiber preform P, a feeder 11 that feeds the optical fiber preform P into the fiber drawing furnace 14, an outer diameter measuring device 15 that measures the outer diameter D of the drawn optical fiber F1, a take-up machine 21 that takes up the optical fiber F2, and a supply speed V that is the speed at which the optical fiber preform P is fed into the fiber drawing furnace 14 G and a take-up speed V that is the speed at which the optical fiber F2 is taken up L and a control device 30B that controls them. This control device 30B includes an acquisition unit 31B that acquires the outer diameter D of the optical fiber F1, a setting unit 32B that sets a target value D G of the outer diameter of the optical fiber F1, controls the take-up speed V L based on the outer diameter D, and derives a calculated value D 2 V L and a target value D G 2 V L and controls the supply speed V G so that the calculated value D 2 V L matches the target value D G 2 V L . It has a control unit 33B

[0065] In this optical fiber manufacturing apparatus, the supply speed V G is controlled so that the calculated value D 2 V L π / 4 matches the target value D G 2 V L π / 4. Here, the calculated value D 2 V L π / 4 is the melting amount Q of the optical fiber preform. Therefore, the supply speed V G is controlled so that the melting amount Q of the optical fiber preform matches the target value Q G of the melting amount. As a result, the responsiveness of the change in the supply speed V G to the change in the melting amount of the optical fiber preform can be improved

[0066] In the method for manufacturing an optical fiber according to the present embodiment, the target value D G is divided by the target value D L , and upper and lower limit values are preset for the resulting value. In this case, when D G is a value that deviates significantly from the target value D L , the calculated value D 2 V L can be more effectively controlled to match the target value D G 2 V L . As a result, it becomes possible to improve the response speed of the supply speed V G with respect to changes in the melting amount of the optical fiber preform P. Note that a value that deviates significantly from the target value D G is, for example, a value smaller than D L (1 - Δ2)) L V1π / 4 or a value larger than D 2 (1 + Δ1)) L V1π / 4. 2

[0067] As described above, the method for manufacturing an optical fiber and the manufacturing apparatus for an optical fiber according to the present disclosure have been described in detail. However, the present invention is not limited to the above embodiment and can be applied to various embodiments and modifications. Specifically, the target value D L of the outer diameter of the optical fiber F1 and the target value V1 of the take-up speed are obtained from outside the pay-off devices 10A and 10B by the acquisition units 31A and 31B, but are not limited thereto. For example, the target value D L and the target value V1 may be set by the setting units 32A and 32B.

[0068] In the first embodiment, in the feeding step, when the outer diameter D is controlled to match the target value D G , the outer diameter D may be a value that matches the target value D G or a value that approximates the target value D G . Further, in the second embodiment, in the feeding step, when the calculated value D 2 V L matches the target value D G ​2 V L When controlled to match 2 V L the calculated value D becomes the target value D G 2 V L and may become a value that matches the target value D G 2 V L or may become a value that approximates the target value D

Explanation of symbols

[0069] 10A, 10B... Wire drawing device 11... Feeder 12... Motor 13... Driver 14... Wire drawing furnace 14a... Opening 14b... Opening 15... Outer diameter measuring device 16... Cooler 17... Die 18... Ultraviolet irradiator 19... Directly below guide roller 20... Capstan 21... Take-up machine 30A, 30B... Control device 31A, 31B... Acquisition unit 32A, 32B... Setting unit 33A, 33B... Control unit a... Acceleration a g ... Acceleration value a t ... Target value D... Outer diameter D0... Reference outer diameter D G ... Target value D L ... Target value F... Optical fiber F1... Optical fiber F2... Optical fiber P... Optical fiber preform P1... Base end portion P2... Tip end portion Q G ... Target value V f1 ... Set value V f2 …reference supply speed V G …supply speed V L …take-up speed V1... target value

Claims

1. A method for manufacturing an optical fiber from an optical fiber preform, comprising: placing the optical fiber preform in a feeder and feeding it into a drawing furnace; melting and drawing the optical fiber preform in the drawing furnace; measuring the outer diameter D of the drawn optical fiber; taking up the drawn optical fiber.

2. The target value D of the outer diameter of the optical fiber Ｇ is set in advance, In the step of taking up, the take-up speed V, which is the speed at which the optical fiber is taken up Ｌ is controlled based on the outer diameter D measured in the step of measuring, In the feeding step, a supply speed V, which is a speed at which the optical fiber preform is fed into the wire drawing furnace, Ｇ is controlled such that the outer diameter D Ｇ matches the target value D. A method for manufacturing an optical fiber. A method for manufacturing an optical fiber from an optical fiber preform, comprising: placing the optical fiber preform in a feeder and feeding it into a drawing furnace; melting and drawing the optical fiber preform in the drawing furnace; measuring the outer diameter D of the drawn optical fiber; taking up the drawn optical fiber.

3.

4. The target value D of the outer diameter of the optical fiber Ｇ is set in advance, In the step of taking up, the take-up speed V, which is the speed at which the optical fiber is taken up Ｌ is controlled based on the outer diameter D measured in the step of measuring, In the feeding step, the calculated value D ２ V Ｌ and the target value D Ｇ ２ V Ｌ are derived, and the supply rate V Ｇ which is the rate of feeding the optical fiber preform into the wire drawing furnace ２ V Ｌ is controlled so that the calculated value D Ｇ ２ V Ｌ matches the target value D A method for manufacturing an optical fiber.

5. The target value D of the outer diameter of the optical fiber Ｌ is set in advance, In the taking-up step, the taking-up speed V Ｌ is controlled based on the difference between the outer diameter D and the target value D Ｌ The method for manufacturing an optical fiber according to claim 1 or claim 2.

6. The take-up speed V of the optical fiber Ｌ has a preset target value V1, In the feeding step, the target value D Ｇ is The take-up speed V Ｌ When it is greater than the target value V1, the target value D Ｌ is set to a value smaller than the take-up speed V Ｌ when it is the target value V1, the target value D Ｌ is set to the same value as The take-up speed V Ｌ When it is smaller than the target value V1, the target value D Ｌ is set to a value larger than that, and the method for manufacturing an optical fiber according to claim 3. An optical fiber manufacturing apparatus for manufacturing an optical fiber by heat-drawing an optical fiber preform, comprising: the target value D Ｇ is the target value D Ｌ The manufacturing method of the optical fiber according to claim 3, wherein at least one of an upper limit value and a lower limit value is preset for a value obtained by dividing by the target value D. a drawing furnace for heating and melting the optical fiber preform; a feeder for feeding the optical fiber preform into the drawing furnace; an outer diameter measuring device for measuring the outer diameter D of the drawn optical fiber; a take-up machine for taking up the optical fiber. The control device: has an acquisition unit for acquiring the outer diameter D of the optical fiber. The supply speed V, which is the speed at which the optical fiber preform is fed into the wire drawing furnace Ｇ and the take-up speed V, which is the speed at which the optical fiber is taken up Ｌ a control device for controlling them Optical fiber manufacturing apparatus.

7. An optical fiber manufacturing apparatus for manufacturing an optical fiber by heat-drawing an optical fiber preform, comprising: A setting unit that sets a target value D for the outer diameter of the optical fiber Ｇ and the take-up speed V Ｌ is controlled based on the outer diameter D, and the supply speed V Ｇ is controlled such that the outer diameter D matches the target value D Ｇ and a control unit for controlling as described above; a drawing furnace for heating and melting the optical fiber preform; a feeder for feeding the optical fiber preform into the drawing furnace; an outer diameter measuring device for measuring the outer diameter D of the drawn optical fiber; a take-up machine for taking up the optical fiber. The control device: has an acquisition unit for acquiring the outer diameter D of the optical fiber. Optical fiber manufacturing apparatus. ​ The supply rate V which is the rate at which the optical fiber preform is fed into the drawing furnace Ｇ and the take-up rate V which is the rate at which the optical fiber is taken up Ｌ a control device for controlling them ​ ​ ​ A setting unit that sets a target value D for the outer diameter of the optical fiber Ｇ and The take-up speed V Ｌ is controlled based on the outer diameter D, and the calculated value D ２ V Ｌ and the target value D Ｇ ２ V Ｌ are derived, and the supply speed V Ｇ is adjusted such that the calculated value D ２ V Ｌ matches the target value D Ｇ ２ V Ｌ by a control unit ​ ​

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