JP2019064853A - Manufacturing method and manufacturing apparatus of optical fiber wire - Google Patents

Abstract

To provide a manufacturing method and a manufacturing apparatus of an optical fiber wire which hardly generate deterioration of a surface nature than hitherto.SOLUTION: A manufacturing apparatus of an optical fiber wire includes a primary irradiation part (106) for irradiating each point of the optical fiber wire in which an ultraviolet curable resin constituting at least a surface layer of a coating is in the uncured state, with ultraviolet light emitted from an ultraviolet lamp as long as 0.01 second, under a low oxygen atmosphere having an oxygen concentration of 2% or less and a secondary irradiation part (108) for irradiating each point of the optical fiber wire in which the ultraviolet curable resin constituting at least the surface layer of the coating is in the cured state, obtained from the primary irradiation part (106), with ultraviolet light emitted from the ultraviolet light emission diode.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing an optical fiber. The present invention also relates to an apparatus for manufacturing an optical fiber.

  The optical fiber strand is composed of (1) a bare glass optical fiber and (2) a resin coating that covers the side surface of the optical fiber strand. The coating plays a role of alleviating the side pressure on the bare optical fiber and improving the resistance to trauma. In the production of an optical fiber strand, it is general to form a coating by curing an ultraviolet curable resin by applying an ultraviolet curable resin to the side surface of an optical fiber bare wire and then irradiating it with ultraviolet radiation.

  Conventionally, an ultraviolet lamp such as a metal halide lamp has been used as a light source of an irradiation device for irradiating the ultraviolet curing resin with ultraviolet rays in the production of an optical fiber strand. The ultraviolet lamp has an advantage that high intensity ultraviolet light can be obtained, but has a disadvantage that the calorific value is large. For this reason, if ultraviolet irradiation using an ultraviolet lamp is performed for a long time, the ultraviolet curing resin may be heated to a high temperature and may be deteriorated. In addition, in an irradiation apparatus using an ultraviolet lamp, an intake and exhaust mechanism for cooling the ultraviolet lamp is indispensable. For this reason, the initial cost for preparing the irradiation apparatus equipped with the intake and exhaust mechanism, and the running cost for operating the intake and exhaust mechanism with large power consumption become expensive. In view of these problems, recently, the use of an ultraviolet light emitting diode has been considered as an alternative to the ultraviolet lamp.

  Patent Documents 1 to 3 describe that an ultraviolet light emitting diode is used instead of the ultraviolet ray lamp or in combination with the ultraviolet ray lamp in the manufacture of an optical fiber strand. Further, according to Patent Document 4, in the production of an optical fiber strand, after the ultraviolet ray irradiation using an ultraviolet ray lamp is performed on the ultraviolet ray curing resin constituting the coating, the ultraviolet ray irradiation using an ultraviolet light emitting diode is performed. It is described.

JP, 2014-95923, A (May 22, 2014 publication) JP-A-2015-212222 (released on November 26, 2015) Unexamined-Japanese-Patent No. 2016-70966 (May 9, 2016 publication) Unexamined-Japanese-Patent No. 2010-117525 (May 27, 2010 publication)

  However, in the conventional method of manufacturing an optical fiber, there is a problem that the surface property of the optical fiber is easily deteriorated.

  First, consider the case of performing ultraviolet irradiation using an ultraviolet lamp after performing ultraviolet irradiation using an ultraviolet light emitting diode. Since the spectrum width of the obtained ultraviolet light is narrower than that of the ultraviolet lamp, the ultraviolet light emitting diode is likely to have a mismatch between the absorption wavelength of the photopolymerization initiator contained in the ultraviolet curing resin and the emission wavelength of the ultraviolet light emitting diode. For this reason, the surface layer of the coating may not be sufficiently cured, and the surface properties of the optical fiber may be deteriorated. Furthermore, before the surface layer of the coating is sufficiently cured, it is likely that the optical fiber strand passes through the section to be irradiated with the ultraviolet light using the ultraviolet light emitting diode and contacts the pulley or the like. When such a situation occurs, the surface layer of the coating which is not sufficiently cured adheres to the pulley or the like and is peeled off from the optical fiber, further deteriorating the surface property of the optical fiber.

  Next, consider the case of performing ultraviolet irradiation using an ultraviolet light emitting diode after performing ultraviolet irradiation using an ultraviolet lamp. Since the spectrum width of the obtained ultraviolet light is wider than that of the ultraviolet light-emitting diode, the ultraviolet lamp hardly causes a mismatch between the absorption wavelength of the photopolymerization initiator contained in the ultraviolet curing resin and the emission wavelength of the ultraviolet lamp. However, when ultraviolet irradiation is performed in air, curing inhibition by oxygen may occur. Then, the surface layer of the coating may not be sufficiently cured, and the surface properties of the optical fiber may be deteriorated. In addition, the deterioration of the surface property due to the inhibition of curing by oxygen is likely not to be sufficiently improved by the subsequent ultraviolet irradiation. Furthermore, before the surface layer of the coating is sufficiently cured, a situation occurs in which the optical fiber strand passes through the section to be irradiated with ultraviolet light using an ultraviolet lamp and contacts a pulley or the like. Therefore, even when the ultraviolet light irradiation using the ultraviolet light emitting diode is performed after the ultraviolet light irradiation using the ultraviolet light lamp, the possibility that the surface property of the optical fiber strand is further deteriorated can not be excluded. . Patent Document 4 does not show any specific method for eliminating such a possibility.

  The present invention has been made in view of the above problems, and an object thereof is to realize a method and an apparatus for manufacturing an optical fiber in which deterioration of surface property is less likely to occur than in the prior art.

  In order to solve the above-mentioned subject, the manufacturing method of the optical fiber strand of the present invention is an optical fiber element of the uncured state of the ultraviolet curing resin which constitutes at least the surface layer of the coating among the ultraviolet curing resin which constitutes the coating. For each point of the line, in a low oxygen atmosphere with an oxygen concentration of 2% or less, a first irradiation step of irradiating the ultraviolet light emitted by the ultraviolet lamp for 0.01 seconds or longer and the first irradiation step are performed And a second irradiation step of irradiating the ultraviolet light emitted by the ultraviolet light emitting diode to each point of the optical fiber strand obtained by curing at least the ultraviolet curable resin constituting the surface layer of the coating. The spectral width of the ultraviolet light emitted by the ultraviolet lamp is characterized by being wider than the spectral width of the ultraviolet light emitted by the ultraviolet light emitting diode.

  Moreover, in order to solve said subject, the manufacturing apparatus of the optical fiber strand of this invention is the light of the uncured state of the ultraviolet-ray cured resin which comprises the surface layer of the said coating among the ultraviolet-ray cured resin which comprises a coating. A first irradiation unit for irradiating the ultraviolet light emitted by the ultraviolet lamp for 0.01 seconds or more in a low oxygen atmosphere with an oxygen concentration of 2% or less for each point of the fiber strand; And a second irradiation unit for irradiating the ultraviolet light emitted by the ultraviolet light emitting diode to each point of the optical fiber strand obtained by performing at least the curing of the ultraviolet curable resin constituting at least the surface layer of the coating. The spectral width of the ultraviolet light emitted by the ultraviolet lamp is wider than the spectral width of the ultraviolet light emitted by the ultraviolet light emitting diode.

  According to said structure, the optical fiber strand which passed the 1st irradiation process (1st irradiation part) will be in the state which the surface layer of coating | cover hardened. This is because, in the first irradiation step (the first irradiation section), the wide-spectrum ultraviolet light emitted by the ultraviolet lamp is irradiated for 0.01 seconds or more in the oxygen concentration control section where the oxygen concentration is 2% or less. is there. As a result, it is possible to suppress the deterioration of the surface property of the optical fiber strand that may occur in the manufacturing process subsequent to the first irradiation step (first irradiation unit).

  In the method of producing an optical fiber according to the present invention, the coating includes a primary coating that covers the side surface of the bare optical fiber and a secondary coating that covers the outer surface of the primary coating; In a step performed before the first irradiation step, the ultraviolet curing resin forming the primary coating and the ultraviolet curing resin forming the secondary coating are applied together to the bare optical fiber. Preferably, the method further comprises a coating step.

  According to the above configuration, the first irradiation step is obtained by performing the coating step in the process of manufacturing the optical fiber strand in which the ultraviolet curable resin constituting each of the primary coating and the secondary coating is applied collectively. The UV curable resin constituting the primary coating and the UV curable resin constituting the secondary coating are applied to each point of the uncured optical fiber. Thereby, the optical fiber strand which passed the 1st irradiation process will be in the state which the ultraviolet curing resin which comprises the surface layer of at least secondary coating hardened | cured. Thereafter, a second irradiation step is performed on each point of the optical fiber strand obtained by performing the first irradiation step and at which the ultraviolet curable resin constituting the surface layer of at least the secondary coating is cured. Thereby, the optical fiber strand which passed the 2nd irradiation process will be in the state hardened | cured to the primary coating. That is, according to said structure, the deterioration of the surface property of the secondary coating formed by a Wet-On-Wet system can be suppressed.

  In the method of producing an optical fiber according to the present invention, the coating includes a primary coating that covers the side surface of the bare optical fiber and a secondary coating that covers the outer surface of the primary coating; (1) a first application step of applying an ultraviolet curable resin that constitutes the primary coating to the bare optical fiber as a step performed before the first irradiation step; (2) the above Third step of irradiating the ultraviolet light emitted by the ultraviolet light emitting diode to each point of the optical fiber strand in the uncured state of the ultraviolet curable resin constituting the primary coating, which is obtained by performing the first application step And (3) an ultraviolet ray constituting a secondary coating on the optical fiber strand obtained by curing the ultraviolet curable resin constituting the primary coating, which is obtained by carrying out the third irradiation step A second application step of applying a cured resin; Including, it is preferable.

  According to the above configuration, in the production process of the optical fiber strand in which the ultraviolet curable resin constituting each of the primary coating and the secondary coating is sequentially applied, the first irradiation step comprises the ultraviolet curable resin constituting the primary coating Is in a cured state, and the UV curable resin constituting the secondary coating is applied to each point of the optical fiber in the uncured state. Thereby, the optical fiber strand which passed the 1st irradiation process will be in the state which the ultraviolet curing resin which comprises the surface layer of at least secondary coating hardened | cured. Thereafter, a second irradiation step is performed on each point of the optical fiber strand obtained by performing the first irradiation step and at which the ultraviolet curable resin constituting the surface layer of at least the secondary coating is cured. Thereby, the optical fiber strand which passed the 2nd irradiation process will be in the state where the primary coating and the secondary coating were also hardened. That is, according to said structure, the deterioration of the surface property of the secondary coating formed by a Dry-On-Wet system can be suppressed.

  In the method of manufacturing an optical fiber according to the present invention, the light obtained by performing the first irradiation step as the step performed before the second irradiation step, the light whose surface layer of the coating is cured is obtained It is preferable to further include a fourth irradiation step of irradiating the ultraviolet light emitted by the ultraviolet lamp in the air to each point of the fiber strand.

  According to said structure, the ultraviolet-ray which an ultraviolet-ray lamp emits can fully be irradiated in a 1st irradiation process and a 4th irradiation process. And according to said structure, the 4th irradiation process of irradiating an ultraviolet-ray with respect to the optical fiber strand which already hardened | cured the surface layer of coating | cover is implemented in air. For this reason, compared with the case where a 4th irradiation process is implemented by low oxygen atmosphere-ization, the initial cost and running cost which oxygen concentration management requires can be saved.

  In the method of manufacturing an optical fiber strand according to the present invention, in the first irradiation step, the optical fiber strand is a quartz tube traveling inside, and is filled with an inert gas having an oxygen concentration of 2% or less. The light traveling in the inside of the quartz tube, at least one irradiation unit having a quartz tube and the ultraviolet lamp irradiating the ultraviolet ray to the optical fiber through the quartz tube; It is preferable to use the irradiation apparatus arrange | positioned so that the irradiation time of the said ultraviolet-ray with respect to each point of a fiber strand may be 0.01 second or more.

  According to said structure, the surface layer of at least coating | cover of the optical fiber strand which passed the 1st irradiation process (1st irradiation part) can be made into the state hardened | cured more reliably.

  In the method of manufacturing an optical fiber strand according to the present invention, in the first irradiation step, each point of the optical fiber strand is irradiated with ultraviolet light emitted by the ultraviolet lamp for 0.07 seconds or less. preferable.

  According to said structure, it can prevent that the said coating becomes high temperature so that the ultraviolet curing resin which comprises coating | cover in a 1st irradiation process degrades. In addition, since the length of the section in which the oxygen concentration is controlled is limited, it is possible to suppress the increase in the scale of the manufacturing apparatus that implements the manufacturing method.

  According to the present invention, it is possible to realize a method and an apparatus for manufacturing an optical fiber in which deterioration of the surface property is less likely to occur than in the prior art.

It is sectional drawing which shows the cross section of the optical fiber strand manufactured in each embodiment of this invention. It is a block diagram which shows the structure of the manufacturing apparatus of the optical fiber according to the 1st Embodiment of this invention. It is a figure which shows an example of the spectrum of the ultraviolet-ray each radiate | emitted from UV lamp of a primary irradiation part, and UVLED of a secondary irradiation part in the 1st Embodiment of this invention. It is sectional drawing of the 1st irradiation unit which comprises the primary irradiation part which concerns on the 1st Embodiment of this invention. It is sectional drawing of the 2nd irradiation unit which comprises the secondary irradiation part which concerns on the 1st Embodiment of this invention. It is a flowchart explaining the manufacturing method of the optical fiber in accordance with the first embodiment of the present invention. It is a block diagram which shows the structure of the manufacturing apparatus of the optical fiber strand which concerns on the 2nd Embodiment of this invention. It is a flowchart explaining the manufacturing method of the optical fiber in accordance with the second embodiment of the present invention. It is a flowchart.

  Hereinafter, an optical fiber manufacturing apparatus and manufacturing method according to each embodiment of the present invention will be described. In each of the embodiments, the same components and steps are denoted by the same reference numerals and redundant description will be omitted.

[Configuration of optical fiber strand]
First, an optical fiber strand 10 manufactured by an optical fiber manufacturing apparatus and method according to each embodiment described later will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a cross section (a cross section orthogonal to the optical axis) of the optical fiber 10.

  The optical fiber strand 10 includes a cylindrical optical fiber bare wire 11 and a coating 12 that covers the side surface of the optical fiber bare wire 11.

  The bare optical fiber 11 is constituted by a cylindrical core 11 a and a cylindrical clad 11 b covering the side surface of the core 11 a. The core 11 a and the cladding 11 b are both made of quartz glass. However, the refractive index of the quartz glass which comprises the clad 11b is lower than the refractive index of the quartz glass which comprises the core 11a. The refractive index difference between the core 11a and the cladding 11b can be determined, for example, by adding a dopant (for example, germanium) for increasing the refractive index to the silica glass forming the core 11a, or by forming the cladding glass in the cladding 11b By adding a dopant (eg, fluorine) to lower the refractive index. The reason for making the refractive index of the cladding 11 b lower than that of the core 11 a is to give the bare optical fiber 11 the function of confining light in the core 11 a.

  The coating 12 is constituted by a cylindrical primary coating 12a covering the side surface of the bare optical fiber 11 (the outer surface of the clad 11b) and a cylindrical secondary coating 12b covering the outer surface of the primary coating 12a. ing. Each of the primary coating 12a and the secondary coating 12b is made of an ultraviolet curing resin. However, the Young's modulus of the ultraviolet curable resin constituting the primary coating 12 a is lower than the Young's modulus of the ultraviolet curable resin constituting the secondary coating 12 b. The difference in Young's modulus between the primary coating 12a and the secondary coating 12b is formed, for example, by making the degree of polymerization of the ultraviolet curable resin constituting the primary coating 12a and the secondary coating 12b different. The reason why the Young's modulus of the secondary coating 12b is relatively high and the Young's modulus of the primary coating 12a is relatively low is because the hard secondary coating 12b improves the trauma resistance and the soft primary It is for improving shock absorption nature by covering 12a.

  Each of the ultraviolet curable resins constituting the primary coating 12 a and the secondary coating 12 b contains a photopolymerization initiator. The curing of these UV curable resins is initiated by UV light having a wavelength belonging to the absorption wavelength range of the photoinitiator. The higher the temperature at the time of curing, the easier the curing of the UV curable resin that constitutes the secondary coating 12b tends to be, and the harder the curing of the UV curable resin that constitutes the primary coating 12a tends to proceed. In addition, as the temperature at the time of curing is lower, the curing of the ultraviolet curable resin constituting the secondary coating 12b tends not to proceed, and the curing of the ultraviolet curable resin constituting the primary coating 12a tends to proceed.

First Embodiment
(Configuration of optical fiber manufacturing equipment)
The configuration of the manufacturing apparatus 1 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the manufacturing apparatus 1.

  The manufacturing apparatus 1 is an apparatus for manufacturing the optical fiber strand 10 (see FIG. 1), and the drawing part 101, the cooling part 102, the bare wire outer diameter measuring part 103, the coating part 104, the strand outer diameter measurement A unit 105, a primary irradiation unit 106, a take-off unit 107, a secondary irradiation unit 108, and a winding unit 109 are provided. These components are arranged in this order along the traveling path of the optical fiber 10. Furthermore, the manufacturing apparatus 1 includes a control unit 110 that controls the coating unit 104 and the pulling unit 107 with reference to monitor signals acquired from the bare wire outer diameter measuring unit 103 and the wire outer diameter measuring unit 105. The manufacturing apparatus 1 also includes a plurality of pulleys 111_1 to 111_6. The travel path of the optical fiber 10 is defined by these pulleys 111_1 to 111_6.

  The primary irradiation unit 106 constitutes an example of the first irradiation unit in the present invention. Moreover, the secondary irradiation part 108 comprises an example of the 2nd irradiation part in this invention.

  The drawing part 101 is a means for drawing a preform to be a base material of the optical fiber bare wire 11. In the present embodiment, a heating furnace is used as the drawing unit 101. The preform is heated by the heating furnace and melted. Then, the melted preform is stretched by its own weight. Thus, melting and stretching the preform is called "drawing". The preform drawn in the drawing unit 101 is sent to a cooling unit 102 disposed below the drawing unit 101.

  The cooling unit 102 is a means for cooling the drawn preform. In the present embodiment, a cooling cylinder is used as the cooling unit 102. The drawn preform is cooled and hardened by the cooling gas flowing in the cooling cylinder. Thereby, the optical fiber bare wire 11 is obtained. The bare optical fiber wire 11 obtained in the cooling unit 102 passes through the bare wire outer diameter measuring unit 103 for measuring the outer diameter of the bare optical fiber wire 11, and then the coating unit disposed below the cooling unit 102 It is sent to 104.

  The application section 104 is a means for applying an uncured ultraviolet curable resin as a base material of the coating 12 to the side surface of the bare optical fiber 11. In the present embodiment, a double coating die in which two coating dies are stacked is used as the coating unit 104. On the side surface of the bare optical fiber 11, an uncured ultraviolet curing resin which is a base material of the primary coating 12a is applied by the coating die on the upstream side, and the outer surface of the primary coating 12a is downstream. An uncured ultraviolet curable resin, which is a base material of the secondary coating 12b, is applied by the application die. As a result, the optical fiber strand 10 in which both the primary coating 12a and the secondary coating 12b are uncured is obtained. The optical fiber 10 in this state is hereinafter referred to as an optical fiber 10α. The optical fiber strand 10α obtained in the coating unit 104 passes through the strand outer diameter measurement unit 105 for measuring the outer diameter of the optical fiber strand 10α, and is then disposed below the coating unit 104. It is sent to the irradiation unit 106.

  The thickness of the ultraviolet curable resin applied by the application unit 104 is variable, and is controlled by the control unit 110 based on the outer diameter of the optical fiber strand 10α measured by the strand outer diameter measurement unit 105. There is. When the outer diameter of the optical fiber strand 10α is smaller than a predetermined value, the control unit 110 controls the coating unit 104 to increase the thickness of the ultraviolet curable resin to be applied. Conversely, when the outer diameter of the optical fiber strand 10α is larger than a predetermined value, the control unit 110 controls the coating unit 104 so that the thickness of the ultraviolet curable resin to be applied decreases. Thereby, the outer diameter of the obtained optical fiber 10 can be brought close to a predetermined value.

  The primary irradiation unit 106 is a means for irradiating the optical fiber strand 10α with ultraviolet light using a UV lamp (ultraviolet light lamp) in a low oxygen atmosphere. In the present embodiment, n (where n is a natural number of 1 or more) UV lamp units 106_1 to 106 — n using a UV lamp as a light source are used as the primary irradiation unit 106. The configuration of each UV lamp unit 106 — i (i is a natural number greater than or equal to 1 and less than or equal to n) will be described later, replacing the reference drawings. In addition, in FIG. 2, although the case of n = 3 is illustrated, the number of objects of UV lamp unit 106_i which comprises the primary irradiation part 106 is arbitrary.

  The ultraviolet curable resin as the base material of the coating 12 is cured in order from the outside by ultraviolet irradiation using a UV lamp in the primary irradiation unit 106. In ultraviolet irradiation using a UV lamp in the primary irradiation unit 106, the ultraviolet curable resin that mainly constitutes the secondary coating 12b is cured. However, at the stage when ultraviolet irradiation using the UV lamp in the primary irradiation unit 106 is completed, it is sufficient that the ultraviolet curable resin constituting at least the surface layer of the secondary coating 12 b be sufficiently cured. May be uncured or semi-cured. The optical fiber strand 10 in this state is hereinafter referred to as an optical fiber strand 10β. The optical fiber strand 10β obtained in the primary irradiation unit 106 is sent to the take-up unit 107 after passing through the pulley 111_1. The pulley 111_1 functions as a turn pulley that changes the traveling path of the optical fiber strand 10β from a first direction (downward in FIG. 2) parallel to the gravity direction to a second direction (rightward in FIG. 2) perpendicular to the gravity direction. .

  The pick-up unit 107 is a means for picking up the optical fiber strand 10β at a specific pick-up speed. Here, the take-up speed refers to the length of the optical fiber strand 10β that the take-up unit 107 takes up per unit time. In the present embodiment, a capstan is used as the take-off unit 107. The optical fiber strand 10β picked up by the pick-up unit 107 is sent to the secondary irradiation unit 108 disposed to the side of the pick-up unit 107 after passing through the pulleys 111_2 to 111_6. Here, the pulley 111_5 is a dancer pulley that can be displaced in parallel with the first direction (in the vertical direction in FIG. 2). By urging the pulley 111_5 in the first direction (downward in FIG. 2), the optical fiber strand 10β is tensioned.

  The take-up speed of the take-up unit 107 is variable, and is controlled by the control unit 110 based on the outer diameter of the bare optical fiber 11 measured by the bare wire outer diameter measurement unit 103. When the outer diameter of the bare optical fiber 11 is smaller than a predetermined value, the control unit 110 controls the take-up unit 107 so that the take-up speed decreases. Conversely, when the outer diameter of the bare optical fiber 11 is larger than a predetermined value, the control unit 110 controls the take-up unit 107 so that the take-up speed increases. Thereby, the outer diameter of the obtained bare optical fiber 11 can be made close to a predetermined value.

  The secondary irradiation unit 108 is a means for irradiating the optical fiber strand 10β with ultraviolet light using a UV LED (ultraviolet light emitting diode). In the present embodiment, m (where m is a natural number of 1 or more) UV LED units 108 _ 1 to 108 _ m using a UV LED as a light source are used as the secondary irradiation unit 108. The configuration of each UV LED unit 108 — j (j is a natural number of 1 or more and m or less) will be described later, with reference to the drawings being replaced. In addition, in FIG. 2, although the case of m = 2 is illustrated, the number of objects of UVLED unit 108_j which comprises the secondary irradiation part 108 is arbitrary.

  Among the UV curable resins that become the base material of the coating 12, UV curable resins that have not yet been sufficiently cured by UV irradiation using the UV lamp in the primary irradiation unit 106 are UV radiation using the UV LED in the secondary irradiation unit 108 Curing is complete by irradiation. In the ultraviolet irradiation using the UV LED in the secondary irradiation unit 108, the ultraviolet curable resin that mainly constitutes the primary coating 12a is cured. Thereby, the optical fiber 10 is obtained. The optical fiber strand 10 obtained in the secondary irradiation unit 108 is sent to the winding unit 109.

  The winding unit 109 is a means for winding the optical fiber 10. In the present embodiment, a winding drum 109a having a rotation axis parallel to the second direction and a pulley 109b displaceable in parallel to the second direction are used as the winding portion 109. The optical fiber strand 10 is uniformly wound around the winding drum 109a by reciprocating the pulley 109b in parallel with the second direction while rotating the winding drum 109a.

  As described above, in the manufacturing apparatus 1, the UV lamp is used as the light source of the primary irradiation unit 106, and the UV LED is used as the light source of the secondary irradiation unit 108. This is due to the following reasons.

  UVLEDs consume less power than UV lamps. In addition, since the UVLED does not easily become high temperature, the cooling device can be simplified, and as a result, the power consumption during operation can be further suppressed. In addition, the UV LED has an advantage of being able to suppress the deterioration of the ultraviolet curable resin that may occur in a high temperature environment. However, using a UV LED as the light source of the primary irradiation unit 106 causes the following problems.

  That is, as shown in FIG. 3, the ultraviolet light emitted from the UV LED has a narrower spectral width than the ultraviolet light emitted from the UV lamp. Therefore, the peak wavelength of the UV LED is likely to be different from the absorption wavelength of the photopolymerization initiator contained in the secondary coating 12b. In addition, the secondary coating 12b tends to be more easily cured as the temperature of the fiber at the time of curing is higher. Therefore, when UVLED is used for the primary irradiation unit 106, there is a high possibility that the ultraviolet curable resin constituting the surface layer of the secondary coating 12b can not be sufficiently cured in the primary irradiation unit 106. Then, when the optical fiber strand 10β contacts the pulley 111_1, there arises a problem that the surface of the secondary coating 12b adheres to the pulley 111_1 and is peeled off.

  Therefore, in the manufacturing apparatus 1, these problems are avoided by using a UV lamp as a light source of the primary irradiation unit 106.

  Furthermore, the manufacturing apparatus 1 adopts the following configuration in the above-described primary irradiation unit 106.

  That is, the primary irradiation unit 106 performs ultraviolet irradiation using a UV lamp on the optical fiber strand 10α in a low oxygen atmosphere in which the oxygen concentration is 2% or less. This is to prevent the inhibition of the curing of the ultraviolet curing resin by oxygen. Specifically, the primary irradiation unit 106 is configured such that an inert gas having an oxygen concentration of 2% or less flows through the quartz tube in which the optical fiber strand 10α that emits the ultraviolet light emitted from the UV lamp travels. .

  Moreover, the primary irradiation part 106 is comprised so that the ultraviolet irradiation using a UV lamp may be performed for 0.01 second or more with respect to each point of optical fiber strand 10 alpha. This is an irradiation time for sufficiently curing the ultraviolet curing resin that constitutes at least the surface layer of the secondary coating 12b. Note that the irradiation time refers to the time from when each point of the optical fiber strand 10α enters the ultraviolet irradiation section by the primary irradiation unit 106 until it advances. For example, assume that the drawing speed is 3000 meters / minute. In this case, in order to secure the irradiation time of 0.01 second, the length of the irradiation section in the low oxygen atmosphere in the primary irradiation unit 106 may be configured to be 0.6 meters or more.

  Furthermore, the primary irradiation unit 106 is configured such that the irradiation time of ultraviolet light using a UV lamp is 0.07 seconds or less for each point of the optical fiber strand 10α. This is an irradiation time for preventing deterioration of the UV curable resin which may occur under a high temperature environment by the UV lamp while sufficiently curing the UV curable resin constituting at least the surface layer of the secondary coating 12b. For example, assume that the drawing speed is 1000 meters / minute. In this case, in order to set the irradiation time to 0.07 seconds or less, the length of the irradiation section in the low oxygen atmosphere in the primary irradiation unit 106 may be set to 1.2 meters or less.

  Furthermore, the manufacturing apparatus 1 may adopt the following configuration in the above-described secondary irradiation unit 108.

  That is, the secondary irradiation unit 108 may use, as the UV LED, a UV LED that emits ultraviolet light having the absorption wavelength of the photopolymerization initiator contained in the ultraviolet curable resin that constitutes the primary coating 12 a. This is because in the present embodiment, in the case of the optical fiber strand 10β, it is highly possible that the ultraviolet curable resin constituting the secondary coating 12a is cured to some extent by passing through the primary irradiation unit 106. Therefore, in the optical fiber strand 10β, the portion of the UV curable resin which is the base material of the coating 12 is considered to be mainly the UV curable resin constituting the primary coating 12a, which is not sufficiently cured.

(Configuration of UV lamp unit and UV LED unit)
The configuration of the UV lamp unit 106_i constituting the primary irradiation unit 106 will be described with reference to FIG. FIG. 4 is a cross-sectional view of the UV lamp unit 106 — i.

  The UV lamp unit 106_i includes a housing 106a, a quartz tube 106b penetrating the housing 106a, a UV lamp 106c housed inside the housing 106a, and a quartz tube 106b and a UV lamp 106c inside the housing 106a. And a reflecting plate 106d surrounding the plate. As the UV lamp 106c, for example, a metal halide lamp can be mentioned. The ultraviolet light emitted from the UV lamp 106c is directly or after being reflected by the reflection plate 106d, applied to the optical fiber strand 10α traveling inside the quartz tube 106b.

  The housing 106a is provided with an air supply port 106a1 for supplying a cooling gas into the housing 106a, and an exhaust port 106a2 for discharging the cooling gas to the outside of the housing 106a. There is. The UV lamp 106c housed inside the housing 106a is cooled by this cooling gas.

  In addition, the UV lamp unit 106_i further includes an upper cap 106e for housing the upper end of the quartz tube 106b projecting upward from the housing 106a, and a lower cap 106f for housing the lower end of the quartz tube 106b projecting downward from the housing 106a. And have. The upper cap 106e is provided with an air supply port 106e1 for supplying an inert gas having a low oxygen concentration into the upper cap 106e, and the lower cap 106f exhausts the inert gas to the outside of the lower cap 106f. An exhaust port 106f1 is provided. The inert gas includes, for example, nitrogen, argon or helium. The interior of the upper cap 106e, the quartz tube 106b, and the lower cap 106f is filled with the inert gas. For this reason, the optical fiber strand 10α traveling inside the quartz tube 106b is irradiated with ultraviolet light in a low oxygen atmosphere.

  In the present embodiment, such UV lamp units 106_1 to 3 are continuously arranged. The total length of the sections irradiated with ultraviolet light in each UV lamp unit 106 — i is a length such that the irradiation time becomes 0.01 seconds or more and 0.07 seconds or less according to the change of the take-up speed.

  Next, the configuration of the UV LED unit 108 _j constituting the secondary irradiation unit 108 will be described with reference to FIG. FIG. 5 is a cross-sectional view of the UVLED unit 108_j.

  The UVLED unit 108_j is a quartz tube 108b penetrating the housing 108a, a UVLED bar 108c housed inside the housing 108a, and quartz so as to face the UVLED bar 108c inside the housing 108a And a reflector 108d surrounding the tube 108b. The UVLED bar 108c is an ultraviolet light source in which a plurality of UVLED elements 108c1 to 108c5 are linearly arranged. The ultraviolet light emitted from the UV LED bar 108c is directly or after being reflected by the reflection plate 108d, is irradiated to the optical fiber strand 10β traveling inside the quartz tube 108b.

(Method of manufacturing optical fiber)
A method S1 of manufacturing the optical fiber in accordance with the first embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flowchart showing a method S1 of manufacturing the optical fiber 10. The manufacturing method S1 is a method for manufacturing the optical fiber strand 10 (see FIG. 1), and includes steps S101 to S109 described below.

  Step S101: The drawing part 101 draws a preform to be a base material of the optical fiber bare wire 11.

  Step S102: The cooling unit 102 cools the preform drawn in step S101. Thereby, the optical fiber bare wire 11 is obtained.

  Step S103: The bare wire outer diameter measurement unit 103 measures the outer diameter of the optical fiber bare wire 11 obtained in step S102, and provides a monitor signal representing the measured value of the outer diameter to the control unit 110.

  Step S104 (coating step): The coating unit 104 applies an uncured ultraviolet curing resin as a base material of the coating 12 to the side surface of the bare optical fiber 11 whose outer diameter has been measured in step S103. Specifically, the coating unit 104 applies an uncured ultraviolet curing resin as a base material of the primary coating 12a to the outer surface of the bare optical fiber 11, and an outer surface of the primary coating 12a, The operation of applying the uncured ultraviolet curable resin, which is the base material of the secondary coating 12b, is performed collectively. Thus, the optical fiber strand 10α is obtained.

  Note that the thickness of the ultraviolet curable resin applied in step S104 is adjusted by control of the control unit 110 based on the outer diameter of the optical fiber strand 10α measured in step S105 described later.

  Step S105: The wire outer diameter measurement unit 105 measures the outer diameter of the optical fiber strand 10α obtained in step S104, and provides a monitor signal representing the measured value of the outer diameter to the control unit 110.

  Step S106 (first irradiation step): The primary irradiation unit 106 irradiates the optical fiber strand 10α obtained in step S105 with ultraviolet light using a UV lamp. As a result, the ultraviolet curable resin, which is mainly the base material of the secondary coating 12b, is cured to obtain the optical fiber strand 10β. The ultraviolet curable resin that constitutes the surface layer of at least the secondary coating 12 b is sufficiently cured in this step.

  Step S107: The pick-up unit 107 picks up the optical fiber strand 10β obtained in step S106 at a specific pick-up speed.

  The take-up speed for taking the optical fiber strand 10β in step S107 is adjusted by the control of the control unit 110 based on the outer diameter of the bare optical fiber 11 measured in step S103 described above.

  Step S108 (second irradiation step): The secondary irradiation unit 108 irradiates the optical fiber strand 10β picked up in step S107 with ultraviolet light using a UV LED. As a result, the ultraviolet curing resin, which is mainly the base material of the primary coating 12a, is cured, and the optical fiber strand 10 is obtained.

  Step S109: The winding unit 109 winds up the optical fiber 10 obtained in step S108 on a winding drum 109a. Thereby, the optical fiber strand 10 wound up by the winding drum 109a is obtained.

  In step S106 described above, ultraviolet irradiation using the UV lamp by the primary irradiation unit 106 is performed for 0.01 seconds or more under a low oxygen atmosphere in which the oxygen concentration is 2% or less, as described above.

  As described above, in the present embodiment, the portion including at least the surface layer of the ultraviolet curable resin constituting the coating is in a low oxygen atmosphere with an oxygen concentration of 2% with respect to each point of the uncured optical fiber strand. UV irradiation with a UV lamp is performed for 0.01 seconds or more. Thereafter, in the present embodiment, ultraviolet light is irradiated by the UV LED to each point of the optical fiber strand.

  Here, the absorption wavelength of the photopolymerization initiator contained in the secondary coating 12b is likely to be included in the broad band ultraviolet light of the spectrum width emitted from the UV lamp. In addition, the secondary coating 12b tends to be more easily cured as the temperature of the fiber at the time of curing is higher.

  Therefore, in the present embodiment, at least the surface layer of the secondary coating 12 b can be sufficiently cured in the irradiation at the front stage of the manufacturing process of the optical fiber strand 10. As a result, in the manufacturing apparatus 1 in which the primary coating 12 a and the secondary coating 12 b are applied together, this embodiment can manufacture the optical fiber strand 10 in which the deterioration of the surface property is less likely to occur than in the conventional case.

(Modification)
In the present embodiment, the UV lamp units 106_1 to 106_3 constituting the primary irradiation unit 106 are described as being irradiated under a low oxygen atmosphere in which the oxygen concentration is 2% or less. However, ultraviolet irradiation in one or more UV lamp units 106 _i on the downstream side among the UV lamp units 106 _i constituting the primary irradiation unit 106 may not necessarily be performed in a low oxygen atmosphere. That is, if the irradiation time of 0.01 seconds or more is secured by the one or more UV lamp units 106_i on the upstream side, the UV lamp units 106_i on the remaining downstream side may be irradiated with ultraviolet rays even in the air I do not care. That is, an inert gas with a low oxygen concentration may not flow in such a downstream UV lamp unit 106 — i.

  This is because if the surface layer of the UV curable resin constituting the secondary coating 12 b is sufficiently cured by the UV lamp unit 106 _i on the upstream side of the primary irradiation unit 106, the remaining UV curable resin is not exposed. It is not necessary to prevent hardening inhibition by

  When configured in this manner, the first irradiation step in the present invention is performed by one or more UV lamp units 106 _i on the upstream side that irradiates ultraviolet light in the low oxygen atmosphere of the primary irradiation unit 106. After that, the fourth irradiation process in the present invention is performed by the remaining UV lamp units 106 _i on the downstream side of the primary irradiation unit 106 that irradiates the ultraviolet light in the air. Thereafter, the second irradiation step in the present invention is performed by the secondary irradiation unit 108.

(Other modifications)
In the present embodiment, an example in which the coating 12 of the optical fiber 10 is composed of two layers of the primary coating 12 a and the secondary coating 12 b has been described. However, the present embodiment is also applicable to the case where the coating 12 is formed of one layer. In that case, in the present embodiment, the coating unit 104 may be configured to apply the ultraviolet curing resin forming the coating 12 to the bare optical fiber 11.

Second Embodiment
(Configuration of equipment for manufacturing optical fiber)
A manufacturing apparatus 2 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a block diagram showing the configuration of the manufacturing apparatus 2.

  The manufacturing apparatus 2 is an apparatus for manufacturing the optical fiber strand 10 (see FIG. 1), and includes a wire drawing unit 201, a cooling unit 202, a bare wire outer diameter measuring unit 203, a primary application unit 204, and primary irradiation. A unit 205, a secondary application unit 206, a wire outer diameter measurement unit 207, a secondary irradiation unit 208, a take-off unit 209, a tertiary irradiation unit 210, and a winding unit 211 are provided. These components are arranged in this order along the traveling path of the optical fiber 10. Further, the manufacturing apparatus 2 controls the primary application unit 204, the secondary application unit 206, and the take-off unit 209 with reference to monitor signals acquired from the bare wire outer diameter measurement unit 203 and the wire outer diameter measurement unit 207. A section 212 is provided. The manufacturing apparatus 2 also includes a plurality of pulleys 213_1 to 213_6. The travel path of the optical fiber 10 is defined by the pulleys 213_1 to 213_6.

  In addition, the primary irradiation part 205 is an example of a component which implements the 3rd irradiation process in this invention. Moreover, the secondary irradiation part 208 comprises an example of the 1st irradiation part in this invention. Moreover, the tertiary irradiation part 210 comprises an example of the 2nd irradiation part in this invention.

  Here, in the configuration of the manufacturing apparatus 2 according to the present embodiment, the wire drawing unit 201, the cooling unit 202, the bare wire outer diameter measurement unit 203, the wire outer diameter measurement unit 207, the take-off unit 209, the winding unit 211, And pulleys 213 are configured to function in the same manner as the elements of the same name in the first embodiment. Among the configurations of the manufacturing apparatus 2 according to the present embodiment, the elements different from the configuration of the manufacturing apparatus 1 according to the first embodiment are the primary application unit 204, the primary irradiation unit 205, the secondary application unit 206, The secondary irradiation unit 208, the tertiary irradiation unit 210, and the control unit 212 are included. In the following, these components different from the first embodiment will be described in detail.

  The primary application portion 204 is a means for applying an uncured ultraviolet curable resin as a base material of the primary coating 12 a to the side surface of the bare optical fiber 11. The primary application unit 204 is disposed below the cooling unit 202. The bare optical fiber 11 obtained in the cooling unit 202 is fed to the primary application unit 204. In the present embodiment, a coating die is used as the primary coating unit 204. On the side surface of the bare optical fiber 11, an uncured ultraviolet curable resin, which is a base material of the primary coating 12a, is applied by an application die. As a result, an optical fiber 10 comprising the uncured primary coating 12 a and the bare optical fiber 11 is obtained. The optical fiber 10 in this state is hereinafter referred to as an optical fiber 10α1. The optical fiber strand 10α1 is sent to the primary irradiation unit 205 disposed below the primary application unit 204.

  The primary irradiation unit 205 is a means for irradiating the optical fiber strand 10α1 with ultraviolet light using a UV LED. In the present embodiment, m1 (m1 is a natural number of 1 or more) UV LED units 205_1 to 205_m1 using a UV LED as a light source are used as the primary irradiation unit 205. The configuration of each UV LED unit 205 _ k (k is a natural number of 1 or more and m 1 or less) is the same as that of the UV LED unit 108 _i in the first embodiment described with reference to FIG. In addition, in FIG. 7, although the case of m1 = 1 is illustrated, the number of objects of UVLED unit 205_k which comprises the primary irradiation part 205 is arbitrary.

  The uncured ultraviolet curable resin, which is the base material of the primary coating 12 a, is cured by ultraviolet radiation using the UV LED in the primary radiation unit 205. However, it is not necessary for the primary coating 12a to be sufficiently cured at the stage when the ultraviolet irradiation using the UVLED in the primary irradiation unit 205 is completed, and there may be an uncured or semi-cured portion. . The optical fiber strand 10 in this state is hereinafter referred to as an optical fiber strand 10α2. The optical fiber strand 10α2 obtained in the primary irradiation unit 205 is sent to the secondary application unit 206 disposed below the primary irradiation unit 205.

  The secondary application unit 206 is a means for applying an uncured ultraviolet curable resin, which is a base material of the secondary coating 12 b, to the outer surface of the primary coating 12 a. In the present embodiment, a coating die is used as the secondary coating unit 206. In the side surface of the primary coating 12a covering the bare optical fiber 11 in the optical fiber strand 10α2, an uncured ultraviolet curing resin which is a base material of the secondary coating 12b is applied by an application die. Thereby, the optical fiber strand 10 in which at least the secondary coating 12b of the coating 12 is in an uncured state is obtained. The optical fiber strand 10 in this state is hereinafter referred to as an optical fiber strand 10α3. The optical fiber strand 10α3 passes through the strand outer diameter measuring unit 207 for measuring the outer diameter of the optical fiber strand 10α3, and is then fed to the secondary irradiation unit 208 disposed below the secondary coating unit 206. Be

  The thickness of the ultraviolet curable resin applied by the primary application unit 204 and the secondary application unit 206 is variable, and is based on the outer diameter of the optical fiber strand 10α3 measured by the strand outer diameter measurement unit 207. , And controlled by the control unit 212. The control unit 212 causes one or both of the primary application unit 204 and the secondary application unit 206 to increase the thickness of the ultraviolet curable resin to be applied when the outer diameter of the optical fiber strand 10α3 is smaller than a predetermined value. Control. Conversely, when the outer diameter of the optical fiber strand 10α3 is larger than a predetermined value, the control unit 212 reduces the thickness of the UV curable resin to be applied, and the primary application unit 204 and the secondary application unit 206. Control one or both of Thereby, the outer diameter of the obtained optical fiber 10 can be brought close to a predetermined value. As in the case of the control unit 110 in the first embodiment, the control unit 212 is based on the outer diameter of the bare optical fiber 11 measured by the bare wire outer diameter measurement unit 203. It also performs processing to control the

  The secondary irradiation unit 208 is a means for irradiating the optical fiber strand 10α2 with ultraviolet light using a UV lamp. In the present embodiment, n UV lamp units 208_1 to 208 — n using a UV lamp as a light source are used as the secondary irradiation unit 208. The configuration of each UV lamp unit 208 — i is similar to that of the UV lamp unit 106 — i in the first embodiment described with reference to FIG. 3, so the description in the present embodiment is omitted. In addition, in FIG. 7, although the case of n = 2 is illustrated, the number of objects of UV lamp unit 208_i which comprises the secondary irradiation part 208 is arbitrary.

  In the ultraviolet irradiation using the UV lamp by the secondary irradiation unit 208, mainly, the ultraviolet curable resin constituting the secondary coating 12b is cured. However, at the stage when the ultraviolet irradiation using the UV lamp in the secondary irradiation unit 208 is completed, it is sufficient that the ultraviolet curable resin constituting at least the surface layer of the secondary coating 12b be sufficiently cured. May be uncured or semi-cured. The optical fiber strand 10 in this state is hereinafter referred to as an optical fiber strand 10β1.

  The optical fiber strand 10β1 obtained in the secondary irradiation unit 208 passes through the pulley 213_1, the take-off unit 209, and the pulleys 213_2 to 213_6, and is then sent to the tertiary irradiation unit 210 disposed to the side of the take-off unit 209. .

  The tertiary irradiation unit 210 is a means for irradiating the optical fiber strand 10β1 with ultraviolet light using a UV LED. In the present embodiment, m2 (m2 is a natural number of 1 or more) UVLED units 210_1 to 210 — m2 using a UV LED as a light source are used as the tertiary irradiation unit 210. The configuration of each UV LED unit 210 — j (j is a natural number of 1 or more and m 2 or less) is the same as that of the UV LED unit 108 — j in the first embodiment described with reference to FIG. In addition, in FIG. 7, although the case of m2 = 1 is illustrated, the number of objects of UVLED unit 210_j which comprises the tertiary irradiation part 210 is arbitrary.

  Of the UV curable resin that is the base material of the coating 12 in the optical fiber strand 10β1, UV irradiation using the UV LED in the primary irradiation unit 205 and UV irradiation using the UV lamp in the secondary irradiation unit 208 are still sufficient. There is an uncured part. The UV curable resin in the portion which is not sufficiently cured is cured in order from the outside by UV irradiation using the UV LED in the tertiary irradiation unit 210. In the ultraviolet irradiation using the UV LED in the tertiary irradiation unit 210, the ultraviolet curable resin that mainly constitutes the secondary coating 12b is cured. Thereby, the optical fiber 10 is obtained. The optical fiber strand 10 obtained in the tertiary irradiation unit 210 is sent to the winding unit 211.

  In the UVLED unit 108_i constituting the second irradiation unit of the present invention in the first embodiment, the UVLED has an absorption wavelength of a photopolymerization initiator contained in the ultraviolet curing resin constituting the primary coating 12a. It has been described that a UV LED emitting light may be used. In the present embodiment, the UV LED unit 210_i constituting the second irradiation unit of the present invention emits, as a UV LED, ultraviolet light having the absorption wavelength of the photopolymerization initiator contained in the ultraviolet curable resin constituting the secondary coating 12 b. A UV LED may be used. This is because in the present embodiment, in the optical fiber strand 10β1, there is a high possibility that the ultraviolet curing resin constituting the primary coating 12a is cured to some extent by having already passed through the primary irradiation unit 205. Therefore, in the optical fiber strand 10β1, a portion of the UV curable resin which is the base material of the coating 12 is not considered to be cured sufficiently, and is considered to be mainly the UV curable resin constituting the secondary coating 12b.

(Method of manufacturing optical fiber)
Next, a method of manufacturing the optical fiber 10 using the manufacturing apparatus 2 according to the second embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing a manufacturing method using the manufacturing apparatus 2.

  Step S201: The drawing part 201 draws a preform to be a base material of the optical fiber bare wire 11.

  Step S202: The cooling unit 202 cools the preform drawn in step S201. Thereby, the optical fiber bare wire 11 is obtained.

  Step S203: The bare wire outer diameter measurement unit 203 measures the outer diameter of the bare optical fiber 11 obtained in step S202, and provides a monitor signal representing the measured value of the outer diameter to the control unit 212.

  Step S204 (first coating step): The primary coating unit 204 is an ultraviolet ray in an uncured state which is a base material of the primary coating 12a on the side surface of the bare optical fiber 11 whose outer diameter has been measured in step S203. Apply the cured resin. Thus, the optical fiber strand 10α1 is obtained.

  Note that the thickness of the ultraviolet curable resin applied in step S204 is adjusted by control of the control unit 212 based on the outer diameter of the optical fiber strand 10α3 measured in step S207 described later.

  Step S205 (third irradiation step): The primary irradiation unit 205 irradiates the optical fiber strand 10α1 obtained in step S204 with ultraviolet light using a UV LED. Thereby, optical fiber strand 10 alpha 2 which the ultraviolet curing resin used as a base material of primary covering 12a hardened is obtained. However, in the optical fiber strand 10α2, the ultraviolet curable resin constituting the primary coating 12a may be partially uncured or semi-cured.

  Step S206 (second application step): The secondary application unit 206 applies an uncured ultraviolet curable resin as a base material of the secondary coating 12b to the optical fiber filament α2 obtained in step S205. . Thereby, the optical fiber strand 10α3 is obtained.

  The thickness of the ultraviolet curable resin applied in step S206 is adjusted by control of the control unit 212 based on the outer diameter of the optical fiber strand 10α3 measured in step S207 described later.

  Step S207: The strand outer diameter measurement unit 207 measures the outer diameter of the optical fiber strand 10α3 obtained in step S206, and provides a monitor signal representing the measured value of the outer diameter to the control unit 212.

  Step S208 (first irradiation step): The secondary irradiation unit 208 irradiates the optical fiber strand 10α3 obtained in step S207 with ultraviolet light using a UV lamp. As a result, the ultraviolet curable resin, which is mainly the base material of the secondary coating 12b, is cured to obtain the optical fiber strand 10β1. The ultraviolet curing resin that constitutes at least the surface layer of the secondary coating 12b is sufficiently cured in this step.

  Step S209: The pick-up unit 209 picks up the optical fiber strand 10β1 obtained in step S208 at a specific pick-up speed.

  The take-up speed for taking the optical fiber strand 10β1 in step S209 is adjusted by the control of the control unit 212 based on the outer diameter of the bare optical fiber 11 measured in step S203 described above.

  Step S210 (second irradiation step): The tertiary irradiation unit 214 irradiates the optical fiber strand 10β1 picked up in step S209 with ultraviolet light using a UV LED. As a result, the uncured or semi-cured portion of the ultraviolet curable resin, which is mainly the base material of the secondary coating 12 b, is cured to obtain the optical fiber strand 10.

  Step S211: The winding unit 211 winds up the optical fiber 10 obtained in step S210 on a winding drum 211a. Thereby, the optical fiber strand 10 wound up by the winding drum 211a is obtained.

  As described above, in the present embodiment, the secondary irradiation unit 208 generates an oxygen concentration for each point of the optical fiber filament α2 in which the primary coating 12a is cured to some extent and the secondary coating 12b is not cured. UV irradiation with a UV lamp is performed for 0.01 seconds or longer under a 2% low oxygen atmosphere.

  Here, the absorption wavelength of the photopolymerization initiator contained in the secondary coating 12b is likely to be included in the broad band ultraviolet light of the spectrum width emitted from the UV lamp. In addition, the secondary coating 12b tends to be more easily cured as the temperature of the fiber at the time of curing is higher.

  Therefore, this embodiment can sufficiently cure at least the surface layer of the secondary coating 12 b in the irradiation after the application of the secondary coating 12 b in the manufacturing process of the optical fiber strand 10. As a result, in the manufacturing apparatus 2 in which the primary coating 12 a and the secondary coating 12 b are applied at different times, this embodiment can produce the optical fiber strand 10 in which the deterioration of the surface property is less likely to occur than in the conventional case. .

(Modification)
In the present embodiment, in the UV lamp units 208_1 to 208_2 configuring the secondary irradiation unit 208, it has been described that the irradiation is performed in a low oxygen atmosphere in which the oxygen concentration is 2% or less. However, the UV irradiation in the UV lamp unit 208 _i on the downstream side of the UV lamp units 208 _i constituting the secondary irradiation unit 208 may be performed in the air. The reason is as described in the modification of the first embodiment of the present invention, so the description will be omitted in this embodiment.

[Items to be added]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims, and an embodiment obtained by appropriately combining the technical means disclosed in the different embodiments. The form is also included in the technical scope of the present invention.

1, 2 Manufacturing apparatus 10 Optical fiber wire 11a Core 11b Clad 12a Primary coating 12b Secondary coating 11 Optical fiber bare wire 101, 201 Wire drawing part 102, 202 Cooling part 103, 203 Bare wire outer diameter measuring part 104 Coating part 105, 207 wire outer diameter measurement unit 106, 205 primary irradiation unit 107, 209 take-off unit 108, 208 secondary irradiation unit 109, 211 winding unit 110, 212 control unit 111, 213 pulley 204 primary application unit 206 2 Next application unit 210 tertiary irradiation unit 106a, 108a housing 106b, 108b quartz tube 106c UV lamp 108c UV LED bar 106a1, 106e1 air supply port 106a2, 106f2 exhaust port 106d, 108d reflector

Claims (7)

Among the ultraviolet curable resins constituting the coating, at least the ultraviolet curable resin constituting the surface layer of the coating is in a low oxygen atmosphere having an oxygen concentration of 2% or less with respect to each point of the uncured optical fiber strand, A first irradiation step of irradiating the ultraviolet light emitted from the ultraviolet lamp for 0.01 seconds or longer;
A second method of irradiating the ultraviolet light emitted by the ultraviolet light emitting diode to each point of the optical fiber strand obtained by performing the first irradiation step and at least the ultraviolet curable resin forming the surface layer of the coating cured Irradiation step, and
The spectral width of the ultraviolet light emitted by the ultraviolet lamp is wider than the spectral width of the ultraviolet light emitted by the ultraviolet light emitting diode.
A method of manufacturing an optical fiber according to claim 1. The coating comprises a primary coating covering the side of the bare optical fiber and a secondary coating covering the outer surface of the primary coating;
The said manufacturing method is an ultraviolet curing resin which comprises the ultraviolet curing resin which comprises the said primary coating with respect to the said optical fiber bare wire as a process implemented before the said 1st irradiation process, and the said secondary coating. Further including an application step of applying
The method of manufacturing an optical fiber according to claim 1, The coating comprises a primary coating covering the side of the bare optical fiber and a secondary coating covering the outer surface of the primary coating;
The said manufacturing method is a process implemented before the said 1st irradiation process, The 1st application process of apply | coating the ultraviolet-ray cured resin which comprises primary coating with respect to (1) bare optical fiber ,; (2) The ultraviolet curing resin constituting the primary coating obtained by performing the first coating step emits ultraviolet light emitted from the ultraviolet light emitting diode to each point of the optical fiber uncured state (2) A second coating on the optical fiber strand obtained by curing the ultraviolet curable resin constituting the first coating, which is obtained by performing the third irradiation step of irradiating and (3) the third irradiation step And a second applying step of applying an ultraviolet curing resin constituting the
The method of manufacturing an optical fiber according to claim 1, In the air, with respect to each point of the optical fiber strand obtained by performing the first irradiation step as a step performed before the second irradiation step, the surface layer of the coating is cured. , And a fourth irradiation step of irradiating the ultraviolet light emitted by the ultraviolet lamp
The manufacturing method of the optical fiber in any one of the Claims 1-3 characterized by the above-mentioned. In the first irradiation step, a quartz tube through which the optical fiber strand travels, the quartz tube being filled with an inert gas having an oxygen concentration of 2% or less, and the quartz tube via the quartz tube The irradiation time of the ultraviolet light to each point of the optical fiber wire traveling inside the quartz tube is one or more irradiation units having the ultraviolet ray lamp irradiating the ultraviolet light to the optical fiber wire. Using an irradiation device arranged to be 0.01 seconds or longer,
The manufacturing method of the optical fiber in any one of the Claims 1-4 characterized by the above-mentioned. In the first irradiation step, each point of the optical fiber strand is irradiated with the ultraviolet light emitted by the ultraviolet lamp for 0.07 seconds or less.
The manufacturing method of the optical fiber in any one of the Claims 1-5 characterized by the above-mentioned. Among the ultraviolet curable resins constituting the coating, at least the ultraviolet curable resin constituting the surface layer of the coating is in a low oxygen atmosphere having an oxygen concentration of 2% or less with respect to each point of the uncured optical fiber strand, A first irradiation unit that irradiates the ultraviolet light emitted by the ultraviolet lamp for 0.01 seconds or more;
A second method of irradiating the ultraviolet light emitted by the ultraviolet light emitting diode to each point of the optical fiber strand obtained by implementing the first irradiation unit and at least the ultraviolet curing resin forming the surface layer of the coating cured And an irradiation unit of
The spectral width of the ultraviolet light emitted by the ultraviolet lamp is wider than the spectral width of the ultraviolet light emitted by the ultraviolet light emitting diode.
An optical fiber strand manufacturing apparatus characterized by the above.

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