JP2018083744A - Manufacturing method of optical fiber single wire, manufacturing device of optical fiber single wire and inspection device of optical fiber single wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of optical fiber single wire, a manufacturing device of optical fiber single wire, and an inspection device of optical fiber single wire, capable of detecting abnormality generated in a coating resin with good accuracy.SOLUTION: The manufacturing method includes a first process for applying an ultraviolet curable coating resin to a surface of a glass wire, a second process for irradiating ultraviolet to the coating resin, and a third process for measuring intensity of fluorescence generated by the coating resin and detecting change of intensity of the fluorescence in a longer direction of the glass wire. In the third process, the glass wire is passed in an integrating sphere and fluorescence is measured in the integrating sphere. Alternatively, in the third process, a plurality of photoelectric sensors are arranged in parallel along a travel line of the glass wire and a light reflection member is arranged along the travel line, and fluorescence which reflects at the light reflection member and fluorescence which directly reaches from the coating resin are injected into the plurality of photoelectric sensors.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical fiber manufacturing method, an optical fiber manufacturing apparatus, and an optical fiber inspection apparatus.

  Patent Document 1 discloses a defect detection device in an optical fiber coating layer. The apparatus includes a light source that couples light to the coating layer of the optical fiber at a predetermined angle with respect to the axis of the optical fiber, and a photodetector disposed a predetermined distance away from the point where the light is coupled to the coating layer. With. The light incident on the coating layer from the light source is reflected by the defect in the coating layer, and the reflected light is detected by the photodetector.

Japanese Patent Laid-Open No. 10-267859

  When manufacturing an optical fiber, first, a glass wire including a core and a clad is drawn from a glass base material, and a coating resin is applied and cured on the outer periphery of the glass wire. In such a process, when an abnormality such as bubbles, voids, peeling, resin bumps, or foreign matter is generated in the coating resin, the optical transmission characteristics of the optical fiber deteriorate. Accordingly, it is desirable to inspect the optical fiber for abnormalities. And it is desirable to perform this inspection in the middle of the line of the optical fiber that travels on the production line.

  In the apparatus described in Patent Document 1, light is irradiated from the outside of the optical fiber and a defect is detected by detecting the reflected light. However, when the coating resin is colored, light is always scattered by the pigment in the resin, and the scattered light becomes noise and decreases detection accuracy.

  The present invention has been made in view of such problems, and an optical fiber manufacturing method, an optical fiber manufacturing apparatus, and an optical device capable of accurately detecting an abnormality occurring in a coating resin. An object of the present invention is to provide a fiber strand inspection apparatus.

  In order to solve the above-described problem, an optical fiber manufacturing method according to an embodiment of the present invention includes a first step of applying an ultraviolet curable resin to the surface of a glass wire, and irradiating the resin with ultraviolet rays. A second step and a third step of measuring the intensity of the fluorescence emitted from the resin and detecting a change in the intensity of the fluorescence.

  An apparatus for manufacturing an optical fiber according to an embodiment of the present invention includes a resin application unit that applies an ultraviolet curable resin to the surface of a glass wire, an ultraviolet irradiation unit that irradiates the resin with ultraviolet rays, and a resin. A fluorescence measuring unit that measures the intensity of the emitted fluorescence, and a signal processing unit that detects a change in the intensity of the fluorescence based on the measurement result output from the fluorescence measuring unit.

  In addition, an optical fiber strand inspection apparatus according to an embodiment of the present invention includes a fluorescence measuring unit that measures the intensity of fluorescence emitted from an ultraviolet curable resin that has been applied around a glass wire and irradiated with ultraviolet rays. A signal processing unit that detects a change in the intensity of the fluorescence based on the measurement result output from the fluorescence measurement unit.

  According to the optical fiber manufacturing method, the optical fiber manufacturing apparatus, and the optical fiber inspection apparatus according to the present invention, it is possible to accurately detect bubbles or the like generated in the glass wire or the coating resin.

FIG. 1 shows a configuration of a manufacturing apparatus according to an embodiment. Fig.2 (a) is sectional drawing which shows the structure of an optical fiber strand in case secondary resin is colored including a pigment and dye. FIG.2 (b) is sectional drawing which shows the structure of an optical fiber strand in case a colored layer is provided on a secondary resin layer. FIG. 3 is a manufacturing process diagram of the optical fiber shown in FIG. FIG. 4 is a manufacturing process diagram of the optical fiber shown in FIG. FIG. 5 shows a configuration of an inspection apparatus according to an embodiment. FIG. 6 is a graph showing an example of the time change of the measurement signal. FIG. 7 is a flowchart illustrating a method of manufacturing an optical fiber according to an embodiment. FIG. 8 is a perspective view showing a configuration of an inspection apparatus according to a modification. FIG. 9 is a cross-sectional view of the inspection apparatus shown in FIG. 8 taken along line IX-IX. Fig.10 (a)-FIG.10 (c) are graphs which show the time change of the measurement signal output from three photoelectric sensors. FIG. 10D is a graph showing the time change of the synthesized measurement signal.

[Description of Embodiment of Present Invention]
First, the contents of the embodiment of the present invention will be listed and described. An optical fiber manufacturing method according to an embodiment of the present invention includes a first step of applying an ultraviolet curable coating resin to the surface of a glass wire, a second step of irradiating the coating resin with ultraviolet rays, and a coating resin. And measuring the intensity of the fluorescence emitted from the glass, and detecting a change in the intensity of the fluorescence in the longitudinal direction of the glass wire.

  An apparatus for manufacturing an optical fiber according to an embodiment of the present invention includes a coating resin application unit that applies an ultraviolet curable coating resin to the surface of a glass wire, and an ultraviolet irradiation unit that irradiates the coating resin with ultraviolet rays. A fluorescence measurement unit that measures the intensity of fluorescence emitted by the coating resin, and a signal processing unit that detects a change in fluorescence intensity in the longitudinal direction of the glass wire based on the measurement result output from the fluorescence measurement unit; Is provided.

  In addition, the optical fiber strand inspection apparatus according to an embodiment of the present invention includes a fluorescence measuring unit that measures the intensity of fluorescence emitted from an ultraviolet curable coating resin that is applied to the surface of a glass wire and irradiated with ultraviolet rays. And a signal processing unit that detects a change in the intensity of fluorescence in the longitudinal direction of the glass wire based on the measurement result output from the fluorescence measurement unit.

  Moreover, in said manufacturing method, in the 3rd process, the intensity | strength of fluorescence is measured over the area of predetermined length along the running line of a glass wire, and predetermined length may be 50 mm or more and 300 mm or less.

  Moreover, in said manufacturing method, in a 3rd process, the inside of an integrating sphere may be made to pass through a glass wire, and fluorescence may be measured inside an integrating sphere. Similarly, in the inspection apparatus described above, the fluorescence measurement unit may have an integrating sphere through which the glass wire passes, and may measure fluorescence inside the integrating sphere.

  In the above manufacturing method, in the third step, the plurality of photoelectric sensors are juxtaposed along the traveling line of the glass wire, and the light reflecting member is disposed along the traveling line, and the fluorescence reflected by the light reflecting member and The fluorescent light that directly reaches from the coating resin may be incident on a plurality of photoelectric sensors. Similarly, in the above-described inspection apparatus, the fluorescence measuring unit includes a plurality of photoelectric sensors arranged in parallel along the traveling line of the glass wire, and a light reflecting member disposed along the traveling line, and the light reflecting member The plurality of photoelectric sensors may receive the fluorescence reflected by the fluorescent light and the fluorescence directly reached from the coating resin.

[Details of the embodiment of the present invention]
Specific examples of an optical fiber manufacturing method, an optical fiber manufacturing apparatus, and an optical fiber inspection apparatus according to an embodiment of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included. In the following description, the same reference numerals are given to the same elements in the description of the drawings, and redundant descriptions are omitted.

  FIG. 1 shows a configuration of a manufacturing apparatus 1A according to the present embodiment. As shown in FIG. 1, a manufacturing apparatus 1 </ b> A is an apparatus for manufacturing an optical fiber F having a glass wire F <b> 11 including a core and a clad and a coating resin, and includes a drawing furnace 11 and a forced cooling device. 12, first resin coating unit 14, second resin coating unit 15, UV furnace 17, inspection device 19A, guide roller 20, capstan 21, and take-up bobbin 22, glass wire F11 and optical fiber strand F In order along the passage route.

  In this manufacturing apparatus 1A, the initial traveling direction of the glass wire F11 is set to the vertical direction, and the traveling direction of the optical fiber F is in a horizontal direction or an oblique direction in the subsequent stage from the guide roller 20 below the inspection apparatus 19A. Is set. The drawing furnace 11 draws a preform (glass base material) 10 mainly composed of quartz glass to form a glass wire F11 including a core and a clad. The drawing furnace 11 has a heater arranged so as to sandwich (or surround) the preform 10 set in the drawing furnace 11. The preform 10 is melted by being heated by a heater at its end, and becomes a glass wire F11. The drawn glass wire F11 moves along a predetermined travel line.

  The forced cooling device 12 cools the drawn glass wire F11. The forced cooling device 12 has a sufficient length along the travel line in order to sufficiently cool the glass wire F11. The forced cooling device 12 includes, for example, an intake port and an exhaust port (not shown) for cooling the glass wire F11, and cools the glass wire F11 by introducing a cooling gas from the intake port and the exhaust port.

  The resin application portions 14 and 15 apply an ultraviolet curable coating resin to the surface of the glass wire F11. A liquid resin that is cured by ultraviolet rays is injected into the resin application parts 14 and 15, and the type of resin injected into the resin application part 14 is different from the type of resin injected into the resin application part 15. . By passing the glass wire F11 sequentially through the resin of the resin application portions 14 and 15, the inner layer resin (primary resin 14A) and the outer layer resin (secondary resin 15A) are sequentially applied to the surface of the glass wire F11.

  The UV furnace 17 is an ultraviolet irradiation unit that irradiates the coating resin (primary resin and secondary resin) applied on the surface of the glass wire F11 with ultraviolet rays to cure. When the glass wire F11 having the surface coated with the coating resin passes through the UV furnace 17, the coating resin starts to be cured. The UV furnace 17 includes a semiconductor light emitting element such as an ultraviolet lamp or LED. The wavelength of the ultraviolet rays irradiated from the UV furnace 17 is, for example, 310 to 405 nm.

  The inspection device 19A inspects the coating resin applied to the surface of the glass wire F11 extending from the UV furnace 17, and detects abnormalities such as bubbles, voids, peeling, resin bumps, or foreign matter mixed in the coating resin. . As will be described later, the inspection device 19 </ b> A detects the presence of an abnormality by detecting the intensity of fluorescence emitted by the coating resin immediately after the irradiation of ultraviolet rays in the UV furnace 17. The position of the inspection device 19A is preferably directly below the UV furnace 17 where the fluorescence intensity is large.

  The guide roller 20 guides the optical fiber strand F so that the optical fiber strand F in which the coating resin is cured moves along a predetermined travel line. The traveling direction of the optical fiber F is changed by the guide roller 20, is taken up by the capstan 21, and is sent to the take-up bobbin 22. The take-up bobbin 22 takes up the completed optical fiber F.

  In the optical fiber strand F of the present embodiment, the coating resin includes a colored layer. FIG. 2A is a cross-sectional view showing the structure of the optical fiber F when the secondary resin layer 35A is colored with pigments and dyes. The optical fiber F includes a glass wire F11 and a coating resin 33A provided around the glass wire F11. The coating resin 33A includes a primary resin layer 34 and a colored secondary resin layer 35A. . The optical fiber F does not have a colored layer on the secondary resin layer 35A.

  Moreover, FIG.2 (b) is sectional drawing which shows the structure of the optical fiber strand F in case a colored layer is provided on a secondary resin layer. The optical fiber F includes a glass wire F11 including a core 31 and a clad 32, and a coating resin 33B provided around the glass wire F11. The covering resin 33 </ b> B includes a primary resin layer 34, a secondary resin layer 35 </ b> B, and a colored layer 36.

  FIG. 3 shows a production process diagram of the optical fiber F shown in FIG. In the manufacturing process shown in the figure, a glass base material is drawn to form a glass wire F11 (step S11), and a primary resin and a secondary resin are applied (step S12). On the other hand, FIG. 4 shows a production process diagram of the optical fiber F shown in FIG. In the manufacturing process shown in the figure, a process S13 for applying and coloring an ink resin is added to the manufacturing process shown in FIG. The ink resin application unit is provided between the resin application unit 15 and the thickness deviation measuring device 16 in FIG. As in the optical fiber F shown in FIG. 2A, by coloring the secondary resin layer and omitting the colored layer, step S13 can be omitted and the number of manufacturing steps can be reduced.

  FIG. 5 shows a configuration of the inspection apparatus 19A of the present embodiment. When the ultraviolet curable coating resin is irradiated with ultraviolet rays, the coating resin immediately fluoresces. The wavelength of this fluorescence is 400-700 nm, for example, and is yellow visible light in one example. This fluorescence is emitted from the inside of the coating resin. As shown in FIG. 5, the inspection device 19 </ b> A includes a fluorescence measurement unit 23 and a signal processing unit 24. The fluorescence measurement unit 23 measures the intensity of fluorescence emitted from the coating resin immediately after being irradiated with ultraviolet rays by the UV furnace 17.

  Since the fluorescence emitted from the coating resin is weak, the fluorescence measuring unit 23 transmits the fluorescence over a section of a predetermined length L along the travel line of the glass wire F11 (ie, the optical fiber strand F) coated with the coating resin. Measure strength. The predetermined length L is, for example, 50 mm or more and 300 mm or less. More preferably, the predetermined length L is, for example, not less than 50 mm and not more than 150 mm. In addition, although the case where the travel line in the fluorescence measurement part 23 is linear is illustrated in FIG. 5, the travel line in the fluorescence measurement part 23 may be bent.

  The fluorescence measurement unit 23 of the present embodiment includes an integrating sphere 25 and a photoelectric sensor 26 and measures fluorescence inside the integrating sphere 25. The integrating sphere 25 is an optical system for collecting fluorescence emitted in all directions, and covers a section of a predetermined length L of the optical fiber strand F. The optical fiber F is introduced into the integrating sphere 25 through an opening 25 a formed at the upper end of the integrating sphere 25, travels through the integrating sphere 25, and is then formed at the lower end of the integrating sphere 25. It moves to the outside of the integrating sphere 25 through the opening 25b. The fluorescence emitted by the coating resin is repeatedly reflected on the inner wall surface 25 c of the integrating sphere 25. The light receiving surface 26a of the photoelectric sensor 26 is disposed inside the integrating sphere 25, and receives the fluorescence R1 that reaches directly from the coating resin and the fluorescence R2 that reaches after reflecting on the inner wall surface 25c of the integrating sphere 25. The photoelectric sensor 26 generates an electrical measurement signal corresponding to the light intensity of the fluorescence R1 and R2 incident on the light receiving surface 26a. The measurement signal is provided to the signal processing unit 24 via the wiring 41 as a fluorescence intensity measurement result. For example, when the line speed of the optical fiber F is 2400 m / min and the predetermined length L is 100 mm, the time required for a certain point of the optical fiber F to pass through the predetermined length L is 2 .5 milliseconds. Fluorescence output from the point enters the photoelectric sensor 26 for 2.5 milliseconds.

  The inner wall surface 25c (reflection surface) of the integrating sphere 25 is made of a material such as frosted glass. The photoelectric sensor 26 is, for example, a photodiode (in one example, a Si photodiode having sensitivity in the visible light range).

  Based on the measurement signal provided from the fluorescence measurement unit 23, the signal processing unit 24 detects a change in the intensity of fluorescence in the longitudinal direction of the glass wire F11 (that is, the longitudinal direction of the optical fiber strand F). FIG. 6 is a graph showing an example of the time change of the measurement signal, where the vertical axis shows the measurement signal value and the horizontal axis shows the time. In FIG. 6, it is assumed that there is no abnormality in the coating resin in the periods T1 and T3, and there is an abnormality (bubbles, voids, peeling, resin bumps, or foreign matters) in the period T2. In periods T1 and T3 in which there is no abnormality, slight fluctuations occur in the measured fluorescence intensity due to fluctuations in the ultraviolet intensity in the UV furnace 17 and fluctuations in the degree of reaction of the coating resin with respect to the ultraviolet rays. There is no measurement signal. On the other hand, the fluorescence intensity greatly fluctuates during the period T2 in which the coating resin has an abnormality. This is because the fluorescence is scattered at the abnormal location and the fluorescence reaching the outside of the coating resin (that is, the photoelectric sensor) increases.

  Also, abnormalities such as bubbles often occur continuously within a certain length range. When the abnormality is only at one place, the transmission characteristic of the optical fiber is not greatly affected. However, when the abnormality occurs at a plurality of places continuously, the transmission characteristic of the optical fiber is not a little affected. For example, when the line speed of the optical fiber F is 1600 m / min and the abnormal part continues for 4 m, the time during which the fluctuation of the fluorescence intensity is measured (period T2 in FIG. 6) is 2.5 milliseconds. During that period, the fluorescence intensity vibrates greatly. The frequency of this vibration is, for example, on the order of kHz to MHz. When such a change is detected in the time change of the measurement signal, the signal processing unit 24 determines that there is an abnormality in the coating resin.

  FIG. 7 is a flowchart showing the method for manufacturing the optical fiber according to the present embodiment. In the first step S21, an ultraviolet curable coating resin including a colored layer is applied to the surface of the glass wire F11. This process is performed by, for example, the resin application units 14 and 15 of the manufacturing apparatus 1A. Next, in the second step S22, the coating resin is irradiated with ultraviolet rays. This step is performed by, for example, the UV furnace 17 of the manufacturing apparatus 1A. Subsequently, in the third step S23, the intensity of the fluorescence emitted from the coating resin is measured, and a change in the intensity of the fluorescence in the longitudinal direction of the glass wire F11 is detected. This process is performed by, for example, the inspection apparatus 19A. As described above, in the third step S23, the fluorescence intensity may be measured over a section having a predetermined length L along the travel line of the glass wire F11. In the third step S23, the glass wire F11 may be passed through the integrating sphere 25 and the fluorescence may be measured inside the integrating sphere 25.

  The effects obtained by the manufacturing method, the manufacturing apparatus 1A, and the inspection apparatus 19A according to the present embodiment described above will be described. In the present embodiment, an ultraviolet curable resin is applied to the surface of the glass wire F11, irradiated with ultraviolet rays, and then the intensity of fluorescence emitted from the resin is measured. As described above, when an ultraviolet curable resin is irradiated with ultraviolet rays, the resin immediately fluoresces. Since this fluorescence is generated from the inside of the resin, the influence (noise level) of scattering by the pigment at the time of light detection is small as compared with the case where light is applied to the resin from the outside. When the resin is irradiated with light from the outside, the light is scattered by the pigment on the resin surface layer, so that the ratio of the light that does not reach the bubbles in the irradiated light is large. On the other hand, the light generated from the inside reaches the bubbles without being scattered by the pigment on the resin surface layer, and it is easier to detect the change in scattering caused by the bubbles. Therefore, according to the manufacturing method, the manufacturing apparatus 1A, and the inspection apparatus 19A of the present embodiment, the abnormality generated in the coating resin is more accurate than the method of irradiating light from the outside as described in Patent Document 1, for example. It can be detected well. Moreover, since it is not necessary to irradiate the resin with light from the outside, power consumption can be reduced.

  Further, in the method of irradiating light to the resin from the outside, when light is irradiated from only one direction, there is a portion where light is not irradiated due to refraction in the optical fiber. Therefore, in order to reliably inspect the coating resin over the entire circumference, it is necessary to irradiate light from a plurality of directions. Therefore, there exists a problem that an inspection apparatus will enlarge. On the other hand, according to the present embodiment, a light source is unnecessary, and the photoelectric sensor 26 only needs to be arranged in one direction in the integrating sphere 25, so that the inspection apparatus can be downsized.

  Further, as in the present embodiment, the intensity of fluorescence is measured over a section having a predetermined length L along the travel line of the glass wire F11, and the predetermined length may be 50 mm or more and 300 mm or less. Since the fluorescence emitted from the resin is weak, it may be difficult to detect a change in the fluorescence intensity when the intensity of the fluorescence is measured at only one point. Even in such a case, it is possible to accurately detect a change in the fluorescence intensity by measuring the intensity of the fluorescence over the section of the predetermined length L.

  Further, as in this embodiment, the glass wire F <b> 11 may pass through the integrating sphere 25 and the fluorescence may be measured inside the integrating sphere 25. Thereby, weak fluorescence can be collected and detected as stronger light, so that a change in fluorescence intensity can be detected with high accuracy.

(Modification)
FIG. 8 is a perspective view showing a configuration of an inspection apparatus 19B according to a modification. FIG. 9 is a cross-sectional view taken along line IX-IX of the inspection device 19B shown in FIG. This inspection device 19B has a fluorescence measurement unit 27 instead of the fluorescence measurement unit 23 shown in FIG. The fluorescence measurement unit 27 measures the intensity of fluorescence emitted by the coating resin immediately after being irradiated with ultraviolet rays by the UV furnace 17. Since the fluorescence emitted from the coating resin is weak, the fluorescence measuring unit 27 transmits the fluorescence over a section of a predetermined length L along the travel line of the glass wire F11 (that is, the optical fiber F) coated with the coating resin. Measure strength. The range of the predetermined length L is the same as that in the above embodiment.

  The fluorescence measuring unit 27 includes a light reflecting member 28 and a sensor array 29 including a plurality of photoelectric sensors 29a. The light reflecting member 28 is a curved plate member whose inner surface 28a has light reflectivity, and is disposed along a running line of a glass wire F11 (ie, an optical fiber F) coated with a coating resin. Specifically, as shown in FIG. 9, the cross section of the light reflecting member 28 perpendicular to the longitudinal direction of the optical fiber F is a semi-elliptical shape, and the optical fiber element disposed at one focal point of the ellipse. The fluorescence R2 emitted from the coating resin of the line F is collected in the photoelectric sensor 29a disposed at the other focal point. The light reflecting member 28 has the cross-sectional shape shown in FIG. 9 in any cross section in the longitudinal direction of the optical fiber F. In other words, the light reflecting member 28 extends in the longitudinal direction of the optical fiber F with the cross-sectional shape shown in FIG. The length of the light reflection member 28 in the longitudinal direction of the optical fiber F is equal to the predetermined length L.

  As shown in FIG. 8, the plurality of photoelectric sensors 29 a of the sensor array 29 are arranged in a line along the traveling line of the glass wire F <b> 11 (that is, the optical fiber strand F) coated with the coating resin. The light receiving surface of each photoelectric sensor 29a faces the direction of the optical fiber F, and fluorescence R2 reflected by the light reflecting member 28 and fluorescence R1 directly reaching from the coating resin are incident on each photoelectric sensor 29a. To do. Each photoelectric sensor 29a generates an electrical measurement signal corresponding to the light intensity of the fluorescence R1, R2 incident on the light receiving surface. The measurement signal is provided to the signal processing unit 24 through the wiring 42 as a measurement result of the fluorescence intensity. Although FIG. 8 shows a mode in which the photoelectric sensors 29a are adjacent in an array, the photoelectric sensors 29a may be arranged discretely.

  The inner surface 28a (reflective surface) of the light reflecting member 28 is constituted by a mirror, for example. The photoelectric sensor 29a is, for example, a photodiode (in one example, a Si photodiode having sensitivity in the visible light range).

  Based on the measurement signal provided from the fluorescence measurement unit 27, the signal processing unit 24 detects a change in the intensity of fluorescence in the longitudinal direction of the glass wire F11 (that is, the longitudinal direction of the optical fiber strand F). FIG. 10A to FIG. 10C are graphs showing, as an example, time changes of measurement signals output from the three photoelectric sensors 29a, with the vertical axis indicating the measurement signal value and the horizontal axis indicating the time. . Similar to FIG. 6 of the above embodiment, also in FIGS. 10A to 10C, there is no abnormality in the coating resin in the periods T1 and T3, and there is an abnormality in the coating resin in the period T2 (bubbles, voids, peeling, It is assumed that there is a resin knob or foreign matter contamination). In the periods T1 and T3 in which there is no abnormality, there is no abrupt change and the measurement signal changes substantially constant. On the other hand, the fluorescence intensity greatly fluctuates (vibrates) during the period T2 in which there is an abnormality in the coating resin.

  However, since the three photoelectric sensors 29a are arranged in the longitudinal direction of the optical fiber F, there is a time difference in the fluctuation of the fluorescence intensity. That is, with respect to the fluctuation timing of the measurement signal output from the photoelectric sensor 29a located on the upstream side, the fluctuation timing of the measurement signal output from the photoelectric sensor 29a located on the downstream side is the distance and light of these photoelectric sensors 29a. The time is delayed according to the line speed of the fiber strand F. The signal processing unit 24 corrects this delay time and then synthesizes the measurement signals from the respective photoelectric sensors 29a (FIG. 10 (d)). And when a fluctuation | variation is detected in the time change of the measurement signal after a synthesis | combination, the signal processing part 24 judges that abnormality exists in coating resin.

  Also in the manufacturing method of the above embodiment (see FIG. 7), in the third step S23, a plurality of photoelectric sensors 29a are juxtaposed along the traveling line of the glass wire F11, and the light reflecting member is aligned along the traveling line. 28 may be arranged so that the fluorescence R2 reflected by the light reflecting member 28 and the fluorescence R1 that reaches directly from the coating resin are incident on the plurality of photoelectric sensors 29a.

  According to this modification, weak fluorescence can be continuously detected and synthesized over a certain length, so that a change in fluorescence intensity can be accurately detected as a larger signal change as shown in FIG. be able to.

  The optical fiber strand manufacturing method, optical fiber strand manufacturing apparatus, and optical fiber strand inspection apparatus according to the present invention are not limited to the above-described embodiments, and various other modifications are possible. For example, the above-described embodiments and modification examples may be combined with each other according to necessary purposes and effects. Moreover, in the said embodiment and modification, although the fluorescence is collected using the integrating sphere or the light reflecting plate of cross-section ellipse as a fluorescence measurement part, as a fluorescence measurement part, various condensing means are not restricted to these. Can be used. In addition, by measuring the change in fluorescence intensity over a longer period of time, it is possible to record how the coating resin is cured.

  DESCRIPTION OF SYMBOLS 1A ... Manufacturing apparatus, 10 ... Preform, 11 ... Drawing furnace, 12 ... Forced cooling device, 14, 15 ... Resin application part, 14A ... Primary resin, 15A ... Secondary resin, 17 ... UV furnace, 19A, 19B ... Inspection 20 ... guide roller, 21 ... capstan, 22 ... bobbin, 23 ... fluorescence measuring unit, 24 ... signal processing unit, 25 ... integral sphere, 25a, 25b ... opening, 25c ... inner wall surface, 26 ... photoelectric sensor, 26a ... light receiving surface, 27 ... fluorescence measuring part, 28 ... light reflecting member, 28a ... inner surface, 29 ... sensor array, 29a ... photoelectric sensor, 31 ... core, 32 ... cladding, 33A, 33B ... covering resin, 34 ... primary resin Layer, 35A, 35B ... secondary resin layer, 36 ... colored layer, 41, 42 ... wiring, F ... optical fiber, F11 ... glass wire, R1, R2 ... fluorescence.

Claims (8)

A first step of applying an ultraviolet curable coating resin to the surface of the glass wire;
A second step of irradiating the coating resin with ultraviolet rays;
Measuring the intensity of fluorescence emitted by the coating resin, and detecting a change in the intensity of the fluorescence in the longitudinal direction of the glass wire;
A method for manufacturing an optical fiber. In the third step, the fluorescence intensity is measured over a section of a predetermined length along the traveling line of the glass wire,
The method for manufacturing an optical fiber according to claim 1, wherein the predetermined length is not less than 50 mm and not more than 300 mm.   3. The method for manufacturing an optical fiber according to claim 1, wherein, in the third step, the glass wire is passed through an integrating sphere and the fluorescence is measured inside the integrating sphere.   In the third step, a plurality of photoelectric sensors are juxtaposed along the traveling line of the glass wire, a light reflecting member is disposed along the traveling line, and the fluorescence reflected by the light reflecting member, and the coating The method for manufacturing an optical fiber according to claim 1, wherein the fluorescence directly reaching from the resin is incident on the plurality of photoelectric sensors. A coating resin coating portion for coating the surface of the glass wire with a UV curable coating resin;
An ultraviolet irradiation unit for irradiating the coating resin with ultraviolet rays;
A fluorescence measuring unit for measuring the intensity of fluorescence emitted by the coating resin;
Based on the measurement result output from the fluorescence measurement unit, a signal processing unit that detects a change in the intensity of the fluorescence in the longitudinal direction of the glass wire;
An apparatus for manufacturing an optical fiber. A fluorescence measuring unit for measuring the intensity of fluorescence emitted from the ultraviolet curable coating resin applied to the surface of the glass wire and irradiated with ultraviolet rays;
Based on the measurement result output from the fluorescence measurement unit, a signal processing unit that detects a change in the intensity of the fluorescence in the longitudinal direction of the glass wire;
An inspection apparatus for an optical fiber.   The optical fiber strand inspection apparatus according to claim 6, wherein the fluorescence measuring unit has an integrating sphere through which the glass wire passes, and measures the fluorescence in the integrating sphere.   The fluorescence measuring unit includes a plurality of photoelectric sensors arranged along the traveling line of the glass wire, and a light reflecting member disposed along the traveling line, and is reflected by the light reflecting member. The optical fiber strand inspection apparatus according to claim 6, wherein the plurality of photoelectric sensors receive fluorescence and the fluorescence that directly reaches from the coating resin.

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