JP2005075664A - Method for drawing optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for drawing an optical fiber, by which an abnormal part can be surely discarded. <P>SOLUTION: In the method for drawing the optical fiber, at least one abnormal part in the glass outer diameter of a drawn optical fiber 11a, the glass inside of the optical fiber 11a, and the inside of a resin applied on the optical fiber 11a is detected, and then a marking part is formed by changing the outer diameter of the resin applied into a prescribed outer diameter over a predetermined interval on the basis of the detection of the abnormal part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical fiber drawing method for drawing an optical fiber from an optical fiber preform, and more particularly to an optical fiber drawing method capable of removing an abnormal portion of an optical fiber.

FIG. 9 shows a conventional optical fiber drawing apparatus. As shown in FIG. 9, a conventional drawing apparatus 100 includes a heating furnace 102 that draws a thin optical fiber 101a by heating and melting an optical fiber preform 101, and an outer diameter of the drawn optical fiber 101a. An outer diameter measuring device 103 to be measured and a forced cooling device 104 disposed downstream of the outer diameter measuring device 103 are provided.
The drawing device 100 is arranged downstream of the forced cooling device 104, and a die 105 for coating the surface of the drawn optical fiber with a resin, a resin curing device 107 for curing the applied resin, and a resin Is provided with an outer diameter measuring device 108 for measuring the outer diameter of the optical fiber 101b coated with a bubble sensor and a bubble sensor 109 for detecting bubbles in the coating.
In the drawing device 100, the optical fiber 101b is guided to the winding device 113 by the capstan roller 112 of the capstan device 111 and wound around the bobbin 114 (for example, Patent Document 1).

By the way, abnormal portions such as a portion where the outer diameter of the optical fiber or the optical fiber is out of a desired range or a portion where bubbles are included in the optical fiber or the resin coating are wound around the bobbin 114. It must be separated from other normal parts and discarded in a later process.
Therefore, conventionally, the position of such an abnormal portion in the longitudinal direction of the optical fiber 101b is measured by the capstan roller 112 in accordance with the detection by the outer diameter measuring instruments 103 and 108 and the bubble sensor 109, and the bobbin 114 After winding up, the abnormal part can be determined as position information.

FIG. 10A is an explanatory view showing the position of the abnormal portion of the optical fiber in the drawing step, and FIG. 10B shows the position of the abnormal portion of the optical fiber in the coloring step. It is explanatory drawing.
10 (a) and 10 (b), the optical fiber wound on the bobbin in the drawing process is colored from the drawing end E side toward the drawing start end S in the coloring process. Applied. That is, conventionally, when the position of the abnormal part is located at the position Akm from the drawing end E, the abnormal part exists at the position Akm from the position where the coloring starts (that is, the drawing end E). And the position including the extra length a before and after this position (on both sides in the longitudinal direction of the optical fiber) from the position where the coloring starts is discarded as an abnormal part.

JP 2000-281379 A

  However, since the total length of the optical fiber is several hundred km, even if the extra length is included as described above, the abnormal portion may not be properly discarded due to the measurement error of the capstan roller. . For this reason, there is room for improvement in that the abnormal part remains in the optical fiber strand after the drawing process and the optical fiber core wire after the coloring process mixed with other normal parts, and the yield decreases.

Further, in the above conventional optical fiber drawing method, for example, when a coloring process is performed on the optical fiber after the drawing process, a colorant is applied to the outer peripheral surface of the optical fiber. Therefore, it was not possible to confirm whether it was disposed of online during the coloring process. For this reason, as described above, it was not possible to confirm at the time of the coloring step whether or not the abnormal portion could be properly discarded based on the position information obtained at the time of the drawing step.
The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical fiber drawing method capable of reliably discarding an abnormal portion.

  The above object of the present invention is to detect at least one abnormal portion of the drawn optical fiber glass outer diameter, the inside of the optical fiber glass, and the inside of the resin coated on the optical fiber, and to detect the abnormal portion. Accordingly, the marking portion is formed by changing the outer diameter of the coated resin so as to have a predetermined outer diameter over a predetermined section, and this is achieved by an optical fiber drawing method.

In this way, after the drawing process is completed, an abnormal portion is included in a predetermined section upstream or downstream from the marking portion in the optical fiber. And by separating this predetermined section from other normal parts in the optical fiber as a discarded part, the abnormal part can be reliably discarded. At this time, since the marking part is formed based on the abnormal part during the drawing process, it is not necessary to measure the abnormal part with a capstan roller or the like, and the abnormal part is positioned in the longitudinal direction of the optical fiber after winding. There is no need to measure by. For this reason, it is possible to prevent erroneous recognition of the position of the abnormal portion due to a measurement error of the capstan roller. Therefore, it is possible to suppress a decrease in yield due to an abnormal portion included in the optical fiber strand or the optical fiber core wire that has been commercialized after the drawing step or the coloring step.
In addition, when forming a marking part in an optical fiber strand, forming in the upstream of an abnormal part is preferable. In the drawing process, the optical fiber or the optical fiber is always moving at high speed while being drawn from upstream to downstream. For this reason, when an abnormal part is detected, even if the abnormal part is moving at a high speed downstream, if a marking part is provided upstream of the abnormal part with a predetermined interval, a predetermined downstream part of the marking part is used as a reference. An abnormal part is included in the section. Therefore, the operator can reliably eliminate the abnormal portion by removing the predetermined section including the marking portion.

In addition, according to the optical fiber drawing method according to the present invention, it is possible to confirm the variation of the outer diameter at the portion where the marking portion is formed even after the colorant is applied. For this reason, the operator can confirm the position of the abnormal part in the state (online state) which is performing the coloring process based on the marking part whose outer diameter is different from that of the normal part.
Here, “upstream” means the drawing start end side in the drawing process of the optical fiber, and “downstream” means the drawing end end side in the drawing process of the optical fiber. The same shall apply in this specification.

In the above optical fiber drawing method, it is preferable to adjust the amount of resin applied to the optical fiber by adjusting the temperature of the optical fiber before resin application to form the marking portion.
There is a correlation between the temperature of the optical fiber and the amount of resin applied to the optical fiber. Specifically, since the resin does not adhere easily when the temperature of the optical fiber is high, the amount of resin to be applied decreases, and when the temperature of the optical fiber is low, the resin easily adheres. The amount of resin to be increased.

Further, in the above optical fiber drawing method, before applying the resin, a cooling device is used to cool the optical fiber, and the flow rate of the cooling gas constituting the atmosphere inside the cooling device is changed to change the light. It is preferable to adjust the temperature of the fiber.
Usually, a cooling device (for example, a forced cooling device) forms an atmosphere with an inert gas such as helium that functions as a cooling gas inside the device, and adjusts the flow rate of the cooling gas flowing in the atmosphere, thereby providing an optical fiber. Adjust the cooling rate. At this time, for example, if the flow rate of the cooling gas is reduced, the cooling rate of the optical fiber passing therethrough is reduced. As a result, the optical fiber is not cooled as compared with the normal drawing, and the die for applying the resin at a high temperature is applied. Move to the side. Since the amount of resin applied to the high-temperature portion of the optical fiber decreases, the coating of the resin becomes thin, and the outer diameter becomes smaller than other portions of the optical fiber.

In the above optical fiber drawing method, it is preferable to form the marking portion by changing the amount of resin applied by controlling the resin pressure and the resin temperature.
As a method of changing the amount of resin applied, for example, the amount of resin applied to the optical fiber is adjusted by adjusting at least one of the pressure, amount and resin temperature at which the resin is supplied from the die to the optical fiber. Is to adjust.

  In the optical fiber drawing method, it is preferable to form the marking portion by applying the resin again on the downstream side of the die for applying the resin to the optical fiber. In this way, it is not necessary to control the amount of resin applied in the die.

  Further, the above object of the present invention is to detect at least one abnormal portion of the outer diameter of the drawn optical fiber, the outer diameter of the resin coated on the optical fiber, the inside of the glass of the optical fiber, and the inside of the resin. In addition, the marking portion is formed by spraying a special material that can be detected on the resin over a predetermined section based on the detection of the abnormal portion.

  If it carries out like this, when the said material will discard an abnormal part, it will function as a marking part which has the same function as the above-mentioned. And, like the optical fiber drawing method already described, the marking part is formed upstream of the abnormal part during the drawing process, so there is no need to measure the abnormal part with a capstan roller etc. It is not necessary to measure the portion based on position information in the longitudinal direction of the optical fiber. For this reason, it is possible to prevent erroneous recognition of the position of the abnormal portion due to a measurement error of the capstan roller. Therefore, it is possible to suppress a decrease in yield due to an abnormal portion included in the optical fiber strand or the optical fiber core wire that has been commercialized after the drawing step or the coloring step.

  In the optical fiber drawing method, it is preferable to use a colorant as the material. If it carries out like this, the operator can confirm an abnormal part visually as the end of a drawing process by making the location where this colorant was applied into a marking part.

  In addition, it is preferable to add a material that is sensitive to electromagnetic waves as the material and to add at least an amount of the material that can be confirmed in a subsequent process. In this way, when performing the coloring process after the drawing process, the above-mentioned material is detected with a detector using electromagnetic waves, the abnormal part can be confirmed and discarded by using the part containing this material as a marking part. it can.

  ADVANTAGE OF THE INVENTION According to this invention, the drawing method of the optical fiber which can discard an abnormal part reliably can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an optical fiber drawing apparatus used in an optical fiber drawing method according to the present invention.
As shown in FIG. 1, a drawing apparatus 10 includes a heating furnace 12 for drawing (spinning) an optical fiber 11a while heating and melting an optical fiber preform 11, and an outer diameter for measuring the outer diameter of the drawn optical fiber. A measuring device 13 and a forced cooling device (cooling device) 14 that is positioned downstream of the outer diameter measuring device 13 and cools the optical fiber 11a are provided.

Further, the drawing apparatus 10 includes a die 15 that coats and coats the optical fiber 11a cooled by the forced cooling device 14, and a UV curing apparatus that functions as a resin curing unit that cures the resin coated on the optical fiber 11a. 17 and an outer diameter measuring device 18 for measuring the outer diameter of the optical fiber 11b coated with resin.
Here, an optical fiber 11a is a thin glass body drawn from the optical fiber preform 11, and an optical fiber 11b is a resin coating applied to the optical fiber 11a. Hereinafter, the optical fiber 11a and the optical fiber 11b are similarly distinguished.

  In the drawing device 10, the optical fiber 11 b is pulled while being tensioned by the capstan roller 22 of the capstan device 21, and is wound around the bobbin 24 of the winding device 23.

  The UV curing device 17 irradiates the resin applied to the outer peripheral surface of the optical fiber 11a with a die 15 with ultraviolet rays, cures the resin, and coats the optical fiber 11a. The resin curing means is not limited to the UV curing device 17 described above, and a resin curing device having other configurations and functions may be used as long as the resin can be appropriately cured.

As shown in FIG. 1, the drawing apparatus 10 includes a control unit 20.
The control unit 20 is electrically connected to the outer diameter measuring devices 13 and 18 and the forced cooling device 14, respectively, so that the forced cooling device 14 can be controlled based on signals from the outer diameter measuring devices 13 and 18. It is configured.

  The outer diameter measuring device 13 is a measuring device using a laser which is arranged downstream of the heating furnace 12 and has a function of measuring the outer diameter of the optical fiber 11 a drawn by the heating furnace 12. The outer diameter measuring device 13 has a function of detecting bubbles generated in the optical fiber 11a. The outer diameter measuring device 13 detects a portion where the outer diameter (glass outer diameter) of the optical fiber is out of a desired range, and detects a portion where bubbles are contained inside the optical fiber 11a (inside the glass). Then, a signal is transmitted to the control unit 20. At this time, the control unit 20 recognizes the respective portions in the optical fiber 11a as abnormal portions.

  The outer diameter measuring device 18 is a measuring device using a laser which is arranged downstream of the UV curing device 17 and has a function of measuring the outer diameter of the optical fiber 11b. The outer diameter measuring device 18 transmits a signal to the control unit 20 when detecting a portion where the outer diameter of the optical fiber is out of a desired range. At this time, the control part 20 recognizes the said part which the optical fiber strand 11b leaves as an abnormal part.

  The forced cooling device 14 has a function of cooling the optical fiber 11 a heated by the heating furnace 12 when drawn from the optical fiber preform 11. The forced cooling device 14 is configured to release the heat of the optical fiber 11a passing through the atmosphere by creating an atmosphere of an inert gas such as helium that functions as a cooling gas inside. The forced cooling device 14 is configured such that the flow rate of the inert gas can be adjusted by the control unit 20.

  In the drawing apparatus 10, a bubble sensor 19 is provided below the outer diameter measuring device 18. The bubble sensor 19 can detect bubbles generated in the resin constituting the coating of the optical fiber 11b. For example, the bubble sensor 19 irradiates a laser and confirms whether bubbles are generated inside the resin from the scattered light. It is a measuring instrument. The bubble sensor 19 is electrically connected to the control unit 20. The bubble sensor 19 transmits a signal to the control unit 20 when detecting a portion including bubbles in the resin of the optical fiber 11b. At this time, the control part 20 recognizes the said part in the optical fiber strand 11b as an abnormal part.

Next, an optical fiber drawing method according to the present invention will be described.
An optical fiber drawing method according to the present invention detects an outer diameter of a drawn optical fiber, an outer diameter of an optical fiber having a resin coated on the optical fiber, an inside of the optical fiber, and an abnormal portion inside the resin. The marking portion is formed by changing the outer diameter of the optical fiber (the outer diameter of the resin to be coated) to a predetermined outer diameter over a predetermined section based on the detection of the abnormal portion. .

2A, 2B, and 2C are explanatory diagrams of the method of drawing an optical fiber according to the present invention.
FIG. 2A shows a state in which there is a fluctuation portion in the outer diameter of the optical fiber 11a in FIG. 1 in the drawing process of the optical fiber. FIG. 2B shows a state in which a marking portion is formed on the outer diameter of the optical fiber 11b in FIG. 1 in the optical fiber drawing step.
When the fluctuation part of the outer diameter of an optical fiber exceeds a desired range, it is recognized as an abnormal part. And as shown in FIG.2 (b), it fluctuates by making the outer diameter of the optical fiber strand upstream from this fluctuation part or a fluctuation part large or small. The part where the outer diameter is changed constitutes the marking portion M.

  FIG.2 (c) has shown the state of the optical fiber strand colored in the coloring process after winding up an optical fiber strand. The marking portion M applied to the optical fiber can be confirmed as a portion having a different outer diameter from other portions on the outer peripheral surface even after the coloring step. Here, some optical fiber products to be manufactured may be cut at a desired section in a state of an optical fiber without performing a coloring process. At this time, needless to say, the marking portion formed on the outer peripheral surface of the optical fiber can be confirmed.

Specifically, an optical fiber drawing method according to the present invention will be described using the drawing apparatus 10 shown in FIG.
When the controller 20 recognizes an abnormal portion based on signals from the outer diameter measuring devices 13 and 18 and the bubble sensor 19 during the drawing process of the optical fiber, the controller 20 transmits a signal to the forced cooling device 14. The forced cooling device 14 increases or decreases the flow rate of the cooling gas (here, He) based on a signal from the control unit 20.

  When the amount of He in the atmosphere of the forced cooling device 14 increases from a normal value, the cooling rate of the optical fiber passing through the atmosphere increases, and the temperature compared with the temperature when the optical fiber 11a has not detected an abnormal portion. Become lower. On the other hand, when the amount of He in the atmosphere of the forced cooling device 14 is decreased from a normal value, the cooling rate of the optical fiber 11a passing through the atmosphere is slowed down, and the optical fiber 11a is in a case where no abnormal portion is detected. Higher than temperature.

  Here, there is a correlation between the temperature of the optical fiber 11a and the amount of resin applied to the optical fiber 11a. Specifically, since the resin hardly adheres when the temperature of the optical fiber 11a is high, the amount of resin that can be applied decreases, and when the temperature of the optical fiber 11a is low, the resin easily adheres. The amount of resin that can be increased. For this reason, when the optical fiber 11a set at low temperature by the forced cooling device 14 passes through the die 15, the outer diameter of the optical fiber 11b coated with resin is the outer diameter when no abnormal portion is detected. Compared to larger. On the other hand, when the optical fiber 11a set at a high temperature by the forced cooling device 14 passes through the die 15, the outer diameter of the optical fiber 11b coated with resin is larger than the outer diameter when no abnormal portion is detected. Become smaller.

FIG. 3 is a graph showing the outer diameter (μm) of the optical fiber 11b with respect to the glass temperature (° C.) before the resin application of the optical fiber 11a and the He flow rate.
Thus, the amount of resin applied to the optical fiber can be adjusted by adjusting the glass temperature.
Further, as described above, the temperature of the optical fiber can be adjusted by changing the flow rate of the inert gas that functions as the cooling gas.
For this reason, the amount of resin applied to the optical fiber 11a is adjusted by adjusting the flow rate of the cooling gas of the forced cooling device 14 by the control unit 20, and a variable portion is formed on the outer peripheral surface of the optical fiber 11b. be able to. As shown in FIG. 2B, this variable portion functions as a marking portion M.

Next, as an example, an abnormal portion was detected using the optical fiber drawing method according to the present invention to form a marking portion. FIG. 4 shows a flow of an optical fiber drawing process executed in the present embodiment. In this embodiment, the drawing apparatus 10 shown in FIG. 1 is used. Hereinafter, reference will be made to FIGS. 1 and 4 as appropriate.
First, drawing is started with the settings of the forced cooling device 14 and the control unit 20 at the start of drawing being set to those at the normal drawing start time.
When the outer diameter measuring devices 13 and 18 detect a portion where the outer diameter of the optical fiber 11a or the optical fiber strand 11b is out of a desired range, and when the outer diameter measuring device 13 and the bubble sensor 19 detect the inside of the optical fiber 11a. Or when the part containing a bubble is detected inside the resin, the control part 20 detects these parts as an abnormal part (step 41).

  When detecting the abnormal portion, the control unit 20 transmits a signal to the forced cooling device 14 to decrease the flow rate of He in the forced cooling device 14 (step 42). As a result, the abnormal portion of the optical fiber 11b is detected. The upstream diameter is varied (step 43). At this time, since the flow rate of He in the forced cooling device 14 is decreased, the diameter of the optical fiber is reduced.

  When the abnormal portion is not detected based on the signals from the outer diameter measuring devices 13 and 18 (step 44), the control unit 20 is controlled to return the He flow rate in the forced cooling device 14 to the normal drawing value. (Step 46), it returns to Step 41. When the flow rate of He returns to the set value during the normal drawing process, the formation of the marking portion is stopped, and the amount of resin that coats the optical fiber 11a is the normal outer diameter (that is, the light when no abnormal portion is detected). It is adjusted according to the desired outer diameter of the fiber strand 11b.

  On the other hand, if an abnormal portion is still detected in step 44, the flow rate of He is maintained in forced cooling device 14 (step 45). At this time, a marking portion is continuously formed on the optical fiber 11b according to the abnormal portion.

If no abnormal portion is detected in step 41, a normal drawing process is performed to check whether the drawing process is completed (step 47), and the drawing process is terminated.
It should be noted that while the drawing process continues, the abnormal part is always detected, and when the abnormal part is detected, the control of step 42 is performed as described above.

FIG. 5 is a graph showing the change (μm) in the outer diameter of the optical fiber core with respect to the change (μm) in the outer diameter of the optical fiber in the optical fiber obtained in this example. Here, the optical fiber core wire is a fiber core subjected to a coloring process for applying a colorant, and is referred to as “core wire” in the drawing.
As shown in FIG. 5, the amount of change in the outer diameter of the optical fiber (referred to as “strand outer diameter change (μm)” in the figure) is the amount of change in the outer diameter of the optical fiber (in the figure “ The amount of change in the outer diameter of the wire (μm) ”). As a result, if the marking portion is formed by changing the outer diameter of the optical fiber large or small, the outer diameter of the optical fiber core wire is changed according to the marking portion of the optical fiber after the coloring step. A marking portion in which fluctuates is formed. At this time, the amount of variation in the radial direction of the marking portion of the optical fiber is proportional to the amount of variation of the marking portion of the optical fiber core wire.

FIG. 6 is an explanatory diagram showing the fluctuation amount (depth) of the formed marking portion with respect to the outer diameter of the optical fiber obtained by the present embodiment. Moreover, FIG. 7 is explanatory drawing which shows the state after giving the coloring process to the optical fiber strand obtained by the present Example.
As shown in FIG. 6, the diameter of the optical fiber is 246 to 247 μm, whereas the diameter of the portion where the marking portion is formed is around 230 μm.
As shown in FIG. 7, the diameter of the optical fiber core wire after the coloring step was around 255 μm, whereas the diameter of the portion where the marking portion was formed was around 250 μm. The coloring machine is provided with an outer diameter measuring device for monitoring the outer diameter after ink application, and if there is a diameter change of 5 μm, it can be reliably identified. As a result, it was found that the marking portion formed on the optical fiber could be confirmed even after the coloring step.

  According to the optical fiber drawing method according to the present invention, after the drawing process is completed, the operator enters a predetermined section downstream from the marking portion formed on the optical fiber strand (or the optical fiber core wire). An abnormal part is included. Then, by separating this predetermined section from other normal portions in the optical fiber as a discarding portion, the abnormal portion can be reliably discarded.

  In addition, since the marking part is formed upstream of the abnormal part during the drawing process, it is not necessary to measure the abnormal part with a capstan roller or the like as in the prior art, and the abnormal part is longitudinally aligned in the optical fiber after winding. There is no need to measure the position information. For this reason, it is possible to prevent erroneous recognition of the position of the abnormal portion due to a measurement error of the capstan roller. Therefore, it is possible to suppress a decrease in yield due to an abnormal portion included in the optical fiber strand or the optical fiber core wire that has been commercialized after the drawing step or the coloring step.

  Furthermore, in the coloring step, even when the colorant is applied to the surface of the optical fiber strand, even after the colorant is applied, the variation in the outer diameter can be confirmed at the location where the marking portion is formed. For this reason, the operator can confirm the position of the abnormal part in the state (online state) which is performing the coloring process based on the marking part whose outer diameter is different from that of the normal part.

In addition, this invention is not limited to embodiment mentioned above, A suitable deformation | transformation, improvement, etc. are possible.
For example, as shown in FIG. 1, a resin supply unit 16 that can control at least one of the pressure and temperature of the resin applied by the die 15 to be applied is provided, and the resin supply unit 16 is controlled by the control unit 20. Good.
In this way, when the controller 20 recognizes an abnormal portion during drawing of the optical fiber, the optical fiber 11a is coated by controlling at least one of the pressure and temperature of the resin applied by controlling the dice. The marking portion may be formed on the optical fiber by changing the amount of resin to be changed.
Also, for example, a marking part may be formed by providing a die for forming a marking part downstream of the die 15 shown in FIG. 1 and coating the optical fiber with the upstream die 15 and then applying a resin. Good.
Furthermore, it is preferable to appropriately set the outer diameter measuring device 18 or the control unit 20 so that the outer diameter measuring device 18 shown in FIG. 1 does not detect the marking portion as an abnormal portion.

Another embodiment of the optical fiber drawing method according to the present invention will be described. FIG. 8 shows a drawing apparatus 30 used in this embodiment. In the embodiments described below, members having the same configuration / action as those already described are denoted by the same or corresponding reference numerals in the drawings, and description thereof is simplified or omitted.
The drawing device 30 includes a foreign matter mixing unit 31 that adds a material different from resin to the optical fiber 11 a downstream of the die 15. Here, as the material, a colorant or a material sensitive to electromagnetic waves can be used. A special material that can be detected may be used and sprayed over a predetermined section of the resin based on the detection of the abnormal part.

  The foreign matter mixing unit 31 is connected to the foreign matter supply unit 36. The foreign material supply unit 36 is electrically connected to the control unit 40. Based on the abnormal part, the control unit 40 adds the above material upstream of the abnormal part in the optical fiber. At this time, the amount of material added can be controlled. Here, when the material is added, it may be added to the surface of the resin of the optical fiber or may be mixed into the resin.

As described above, the drawing method of the optical fiber according to the present invention includes the glass outer diameter of the drawn optical fiber, the outer diameter of the resin coated on the optical fiber, the glass inside of the optical fiber, and the inside of the resin. The marking portion is formed by detecting at least one abnormal portion and spraying a special material that can be detected on the resin over a predetermined section based on the detection of the abnormal portion.
If it carries out like this, when the said material will discard an abnormal part, it will function as the said marking part. And, like the optical fiber drawing method already mentioned, the marking part is formed based on the abnormal part during the drawing process, so there is no need to measure the abnormal part with a capstan roller etc. It is not necessary to measure the portion based on position information in the longitudinal direction of the optical fiber. For this reason, it is possible to prevent erroneous recognition of the position of the abnormal portion due to a measurement error of the capstan roller. Therefore, it is possible to suppress a decrease in yield due to an abnormal portion included in the optical fiber strand or the optical fiber core wire that has been commercialized after the drawing step or the coloring step.

  In the optical fiber drawing method, if a colorant is used as the material, the operator can visually confirm the abnormal part at the end of the drawing process by using the portion where the colorant is applied as a marking part. can do.

  In addition, if a material sensitive to electromagnetic waves is used as the above-mentioned material and at least the amount of the material that can be confirmed after the drawing process is added, a detector using electromagnetic waves is used when performing a coloring process after the drawing process. The above-mentioned material is detected, and the part including this material can be used as a marking part to confirm and discard the abnormal part.

Further, the above object of the present invention can be achieved by the optical fiber drawing device shown in FIGS.
Referring to FIG. 1 and the above description, a drawing apparatus according to the present invention includes a heating furnace 12 for drawing an optical fiber 11a by heating and melting an optical fiber preform 11, and an outer diameter of the drawn optical fiber 11a. An outer diameter measuring device 13 for measuring, a forced cooling device 14 for cooling the optical fiber 11a, a die 15 disposed below the forced cooling device 14 and applying a resin coating to the optical fiber 11a, and an optical fiber 11a The resin curing device 17 that forms the optical fiber 11b by curing the applied resin, the outer diameter measuring device 18 that measures the outer diameter of the optical fiber 11b, and the resin of the optical fiber 11b A bubble sensor 19 for detecting bubbles contained therein, and based on the abnormal portion of the optical fiber and the optical fiber, the diameter of the optical fiber positioned upstream of the abnormal portion is changed. Mechanism (forced cooling apparatus 14, the resin supply section 16, the foreign matter supply unit 36, etc.) drawing device 10 comprising the.

It is explanatory drawing which shows the drawing apparatus of the optical fiber used for the drawing method of the optical fiber concerning this invention. (A) It is explanatory drawing which shows the fluctuation | variation part of the outer diameter of an optical fiber in a drawing process. (B) In the drawing process, it is explanatory drawing which shows the marking part M formed in the optical fiber strand. (C) It is explanatory drawing which shows the marking part in the optical fiber strand in which the coloring process was given. It is a graph showing the outer diameter (micrometer) of the optical fiber with respect to the glass temperature (degreeC) and He flow rate of an optical fiber. It is a flowchart explaining the Example of the drawing method of the optical fiber concerning this invention. It is a graph which shows the variation | change_quantity (micrometer) of the optical fiber core wire with respect to the variation | change_quantity (micrometer) of the optical fiber strand in the optical fiber strand obtained by the present Example. It is explanatory drawing which shows the fluctuation amount (depth) of the marking part formed with respect to the outer diameter of the optical fiber strand obtained by the Example. It is explanatory drawing which shows the state after giving the coloring process to the optical fiber strand obtained by the Example. It is explanatory drawing which shows the drawing apparatus of the optical fiber used for another embodiment of the drawing method of the optical fiber concerning this invention. It is a figure explaining the drawing method of the conventional optical fiber. (A) In the conventional optical fiber drawing method, it is explanatory drawing which shows the position of the abnormal part of the optical fiber strand in a drawing process. (B) In the conventional optical fiber drawing method, it is explanatory drawing which shows the position of the abnormal part of the optical fiber strand in a coloring process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30 Drawing apparatus 11 Optical fiber preform | base_material 11a Optical fiber 11b Optical fiber strand 12 Heating furnace 13 Outer diameter measuring device 14 Forced cooling device 15 Dice 16 Resin supply part 17 Resin hardening device 18 Outer diameter measuring device 19 Bubble sensor 20 , 40 Control unit 21 Capstan device 22 Capstan roller 23 Winding device 24 Bobbin 31 Foreign matter mixing unit

Claims (8)

Detecting at least one abnormal part of the drawn optical fiber glass outer diameter, the inside of the optical fiber glass, and the inside of the resin coated on the optical fiber, and based on the detection of the abnormal part, A method of drawing an optical fiber, wherein the marking portion is formed by changing the outer diameter so as to have a predetermined outer diameter over a predetermined section. The optical fiber line according to claim 1, wherein the marking portion is formed by adjusting a temperature of the optical fiber before resin application to adjust an amount of the resin applied to the optical fiber. Pull method. Before the resin coating, a cooling device is used to cool the optical fiber, and the temperature of the optical fiber is adjusted by changing the flow rate of the cooling gas constituting the atmosphere inside the cooling device. An optical fiber drawing method according to claim 2. The optical fiber drawing method according to claim 1, wherein the marking portion is formed by changing the amount of resin applied by controlling a resin pressure and a resin temperature. The optical fiber drawing method according to claim 1, wherein the marking portion is formed by applying a resin again on a downstream side of a die for applying the resin to the optical fiber. At least one abnormal portion of the drawn optical fiber glass, the outer diameter of the resin coated on the optical fiber, the inside of the glass of the optical fiber, and the inside of the resin is detected, and based on the detection of the abnormal portion. A marking portion is formed by spraying a special material that can be detected on the resin over a predetermined section. The optical fiber drawing method according to claim 6, wherein a colorant is used as the material. 7. The method of drawing an optical fiber according to claim 6, wherein the material is sensitive to electromagnetic waves, and at least the amount of the material that can be confirmed in a later process is added.

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