Method and apparatus for manufacturing a colored optical fiber core

Abstract

This manufacturing method for a colored optical fiber core wire includes: a step in which a colored resin is fed into a die; a step in which an optical fiber strand is passed through the die to coat the colored resin onto the periphery of the optical fiber strand, thereby forming a colored optical fiber core wire provided with a colored layer; a step in which the color of the colored layer is detected; and a step in which the quality of the detected color is determined to be acceptable or not.

Description

Technical Field

[0001] The present disclosure relates to a method and an apparatus for manufacturing a colored optical fiber core wire. This application claims priority based on Japanese Application No. 2020-197905 filed on November 30, 2020, and incorporates by reference all the descriptions described in the Japanese application.

Background Art

[0002] Patent Document 1 discloses a defect detection device capable of detecting defects in a colored layer in a colored optical fiber element wire.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A method for manufacturing a colored optical fiber core wire according to one aspect of the present disclosure includes: a step of drawing a glass fiber while heating an optical fiber base material to form a glass fiber; a step of applying a primary resin around the glass fiber to form an optical fiber element wire having a primary resin layer; a step of feeding a colored resin into a die; a step of passing the optical fiber element wire through the die and applying the colored resin around the optical fiber element wire to form a colored optical fiber core wire having a colored layer; a step of detecting the color of the colored layer; a step of determining whether the detected color is good or bad, and in the step of feeding the colored resin into the die, filled with a first colored resin used as a secondary resin FirstA step of sending out the first colored resin from the tank into the die and applying the first colored resin around the primary resin layer to form a first secondary resin layer; from the first tank A tank filled with a second colored resin that is used as a secondary resin and has a color different from that of the first colored resin; Second tank switch to, A step of sending out the second colored resin into the die and applying the second colored resin around the primary resin layer to form a second secondary resin layer; In the step of detecting the color, it is detected that the color has changed from the color of the first colored resin in the first secondary resin layer to the color of the second colored resin in the second secondary resin layer; In the step of determining the quality, when the color change is determined to be a predetermined is greater than or equal to the threshold the winding of the colored optical fiber core wire as a good product is started.

[0005] Further, a manufacturing apparatus for a colored optical fiber core wire according to an aspect of the present disclosure includes: A wire drawing device that forms a glass fiber by wire drawing while heating an optical fiber base material; A primary resin tank that sends out a primary resin into a primary die; A primary die that allows the glass fiber to pass through and applies the primary resin around the glass fiber to form an optical fiber element wire having a primary resin layer; A secondary resin tank that sends out a colored resin into a secondary die; A secondary die that allows the optical fiber element wire to pass through and applies the colored resin around the optical fiber element wire; A sensor that detects the color of a colored layer formed around the optical fiber element wire by the colored resin; A control unit that determines the quality of the color detected by the sensor; The secondary resin tank sends out the first colored resin used as a secondary resin from the First tank into the secondary die, The secondary die coats the first colored resin around the primary resin layer to form a first secondary resin layer. The secondary resin tank from the first tank is filled with a second colored resin that is used as the secondary resin and has a color different from that of the first colored resin. Second tank switch to, sends the second colored resin into the secondary die. The secondary die coats the second colored resin around the primary resin layer to form a second secondary resin layer. The sensor detects that the color has changed from the color of the first colored resin in the first secondary resin layer to the color of the second colored resin in the second secondary resin layer. When the control unit determines that the color change is a predetermined is greater than or equal to the threshold and is determined arrive at it starts winding up the colored optical fiber core wire as a good product.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

DETAILED DESCRIPTION OF THE INVENTION

[0007] (Problems to be Solved by the Present Disclosure) In order to identify individual optical fibers, a colored layer may be provided on the surface of the optical fiber to facilitate identification. Conventionally, the presence or absence of the colored layer and the color of the colored layer are fixed for each optical fiber manufacturing facility. When changing the color of the colored layer, it is necessary to replace or clean dies, pipes, etc.

[0008] Therefore, an object of the present disclosure is to provide a method and an apparatus for manufacturing a colored optical fiber core wire capable of flexibly switching the color of the colored layer.

[0009] (Description of Embodiments of the Present Disclosure) First, embodiments of the present disclosure will be listed and described. A method for manufacturing a colored optical fiber core wire according to one aspect of the present disclosure includes: (1) a step of drawing a glass fiber while heating an optical fiber base material to form a glass fiber; a step of applying a primary resin around the glass fiber to form an optical fiber element wire having a primary resin layer; a step of feeding a colored resin into a die; a step of passing the optical fiber element wire through the die and applying the colored resin around the optical fiber element wire to form a colored optical fiber core wire having a colored layer; a step of detecting the color of the colored layer; a step of determining whether the detected color is good or not, and includes: In the step of feeding the colored resin into the die, a step of feeding the first colored resin filled in a tank used as a secondary resin into the die and applying the first colored resin around the primary resin layer to form a first secondary resin layer; First from the first tank, a second coloring resin having a color different from that of the first coloring resin used as a secondary resin is filled in the Second tank switch to, feeding the second coloring resin into the die and applying the second coloring resin around the primary resin layer to form a second secondary resin layer, In the step of detecting the color, it is detected that the color has changed from the color of the first coloring resin in the first secondary resin layer to the color of the second coloring resin in the second secondary resin layer, In the step of determining the quality, when the color change is a predetermined is greater than or equal to the threshold and it is determined, winding of the colored optical fiber core as a good product is started. According to this method, when the color of the coloring resin is switched, it is possible to correctly determine whether the color of the coloring layer is defective (such as colors being mixed). Therefore, it is possible to switch the color without replacing or cleaning the equipment for applying the coloring resin when switching the color of the coloring resin. As a result, the color of the coloring layer can be flexibly switched according to the inventory and demand situation. The above manufacturing method is preferably carried out in the drawing process of the optical fiber.

[0010] (2) In the step of detecting the color, by irradiating the colored optical fiber core with light containing RGB and detecting a part of the light irradiated on the colored optical fiber core with a sensor, each light quantity of RGB of the light is detected to detect the color, In the step of determining the quality of the color, the quality may be determined based on each light quantity. According to this method, it is possible to simply determine the quality of the color of the coloring layer. Note that RGB indicates the light components of R (red), G (green), and B (blue). Light containing RGB means light containing any one or all of the components of red, green, and blue. Each light quantity of RGB of the light means the light quantity of each of red, green, and blue in the light.

[0011] (3) In the step of detecting the color, when irradiating each of the RGB lights separately onto the colored optical fiber core wire and detecting a part of each light with the sensor, by synchronizing the irradiation timing of each light and the detection timing at the sensor, the light amounts of each of the RGB lights are detected to detect the color. In the step of determining the quality of the color, the quality may be determined based on each of the light amounts. According to this method, by detecting with the sensor for each of the RGB lights irradiated onto the colored optical fiber core wire, the color of the colored layer can be correctly recognized.

[0012] (4) In the step of detecting the color, by irradiating white light onto the colored optical fiber core wire and detecting a part of the white light with the sensor, the light amounts of each of the RGB lights are detected to detect the color. In the step of determining the quality of the color, the quality may be determined based on each of the light amounts. According to this method, since it is not necessary to use light sources of different colors, the color of the colored layer can be correctly recognized with a simple configuration.

[0013] (5) In the step of detecting the color, by irradiating light containing RGB onto the colored optical fiber core wire and detecting the transmitted light of the light transmitted through the colored optical fiber core wire with the sensor, the light amounts of each of the RGB lights are detected to detect the color. In the step of determining the quality of the color, the quality may be determined based on each of the light amounts. According to this method, not only can the color be measured from the ratio of the transmitted light amounts, but also the transparency can be measured from the intensity of the transmitted light amounts. Thereby, even when the color of the colored layer is switched from a transparent color to an opaque color or from an opaque color to a transparent color, it is possible to detect whether the switching has been correctly performed.

[0014] (6) In the step of detecting the color, by irradiating light containing RGB onto the colored optical fiber core wire and detecting the reflected light of the light reflected by the colored optical fiber core wire with the sensor, the light amounts of each of the RGB lights are detected to detect the color. In the step of determining the quality of the color, the quality may be determined based on each of the light amounts. According to this method, by detecting the light reflected by the colored optical fiber core wire with a sensor, it is possible to easily determine the quality of the color of the colored layer.

[0015] (7) In the step of detecting the color, the sensor that detects a part of the light irradiated on the colored optical fiber core wire may be a line camera sensor having a plurality of pixels in the width direction of the colored optical fiber core wire. A line camera sensor captures an image of one row (a plurality of pixels) at a time. According to this method, by using a line camera sensor, the measurement frequency can be increased, and minute color defects in the longitudinal direction of the colored optical fiber core wire can also be detected.

[0016] (8) In the step of detecting the color, the sensor that detects a part of the light irradiated on the colored optical fiber core wire may be an area camera sensor having a plurality of pixels in the width direction and the longitudinal direction of the colored optical fiber core wire. An area camera sensor captures the entire field of view at a time. According to this method, by using an area camera sensor, color variations within the colored layer can be detected.

[0017] (9) In the step of detecting the color, a part of the light irradiated on the colored optical fiber core wire may be detected by the sensor from three directions. According to this method, it is possible to detect a defective state in which the color is discontinuous at any position in the circumferential direction.

[0019] Further, a manufacturing apparatus for a colored optical fiber core wire according to an aspect of the present disclosure includes (10) A wire drawing device that forms a glass fiber by wire drawing while heating an optical fiber base material, A primary resin tank that feeds a primary resin into a primary die, A primary die that forms an optical fiber strand provided with a primary resin layer by passing the glass fiber therethrough and applying the primary resin around the glass fiber A secondary resin tank that feeds a coloring resin into a secondary die A secondary die that passes the optical fiber strand therethrough and applies the coloring resin around the optical fiber strand A sensor that detects the color of a colored layer formed around the optical fiber strand by the coloring resin A control unit that determines the quality of the color detected by the sensor, comprising The secondary resin tank is filled with a first coloring resin used as a secondary resin First The first coloring resin is fed from the tank into the secondary die The secondary die applies the first coloring resin around the primary resin layer to form a first secondary resin layer The secondary resin tank from the first tank is filled with a second coloring resin used as a secondary resin and having a color different from that of the first coloring resin Second tank switch to, The second coloring resin is fed into the secondary die The secondary die applies the second coloring resin around the primary resin layer to form a second secondary resin layer The sensor detects that the color has changed from the color of the first coloring resin in the first secondary resin layer to the color of the second coloring resin in the second secondary resin layer When the control unit determines that the color change is a predetermined is greater than or equal to the threshold and determines arrive at The winding of the colored optical fiber core wire as a good product is started According to this configuration, since the quality of the color can be determined when the color of the colored layer is changed, the color of the colored layer can be flexibly switched according to the inventory and demand situation without replacing or cleaning the equipment for applying the coloring resin

[0020] (Effect of the Invention) According to the present disclosure, it is possible to provide a method and an apparatus for manufacturing a colored optical fiber core wire capable of flexibly switching the color of a colored layer.

[0021] (Details of Embodiments of the Present Disclosure) Specific examples of the method and apparatus for manufacturing a colored optical fiber core wire according to an embodiment of the present disclosure will be described with reference to the drawings. It should be noted that the present disclosure is not limited to these examples, and is intended to be indicated by the claims and to include all modifications within the meaning and scope equivalent to the claims.

[0022] The optical fiber element wire used in the method for manufacturing a colored optical fiber core wire of the present embodiment is a glass fiber formed by drawing an optical fiber base material (preform) in a drawing process, and is provided with a primary resin layer by applying a primary resin. The glass fiber is composed of, for example, a core and a cladding of silica glass. In the coating process following the drawing process, a coating layer, for example, a primary resin layer and a secondary resin layer, is formed around the optical fiber. In the method for manufacturing a colored optical fiber core wire of the present embodiment, a secondary resin layer (hereinafter referred to as a colored resin) containing a coloring pigment is used. By forming a secondary resin layer around the primary resin layer, a colored optical fiber core wire is produced. The colored optical fiber core wire produced in this way facilitates the identification of colored optical fiber core wires by changing the color of the colored resin used for the secondary resin layer.

[0023] FIG. 1 is a schematic configuration diagram showing a manufacturing apparatus for a colored optical fiber core wire according to the present embodiment. As shown in FIG. 1, the manufacturing apparatus 1 for the colored optical fiber core wire G2 includes a resin coating die 2, a resin tank 3, a color measuring device 5, an ultraviolet irradiator 6, an outer diameter measuring device 7, a winding machine 9, and a control unit 10. Note that G1 in FIG. 1 is a glass fiber G1 obtained by heating and melting an optical fiber base material in a drawing device (not shown).

[0024] The resin coating die 2 is a die that passes the glass fiber G1 and applies a coating resin around the glass fiber G1. The resin coating die 2 includes a primary die 21 that applies a primary resin around the glass fiber G1 to form a primary resin layer, and a secondary die 22 that applies a secondary resin made of a colored resin around the primary resin layer to form a secondary resin layer. By forming a primary resin layer around the glass fiber G1 with the primary die 21 and forming a secondary resin layer around the primary resin layer with the secondary die 22, a colored optical fiber core wire G2 is obtained. In addition, in this embodiment, the primary resin and the secondary resin are applied with one resin coating die 2, but the present invention is not limited to this, and the primary resin and the secondary resin may be applied with separate dies.

[0025] The resin tank 3 is a tank that sends out the coating resin toward the resin coating die 2. The resin tank 3 includes a primary resin tank 31 that sends out the primary resin P toward the primary die 21, and secondary resin tanks 32 and 33 that send out the secondary resins S1 and S2 toward the secondary die 22. The secondary resin S1 accommodated in the secondary resin tank 32 and the secondary resin S2 accommodated in the secondary resin tank 33 are colored resins of different colors. For the primary resin P and the secondary resins S1 and S2, an ultraviolet curable resin such as a urethane acrylate resin is used, for example.

[0026] The primary resin tank 31 is connected to the primary die 21 via the supply pipe 34. The secondary resin tanks 32 and 33 are connected to the secondary die 22 via the supply pipe 35. The secondary resin sent out to the secondary die 22 via the supply pipe 35 can select either of the secondary resins S1 and S2 by controlling the switching valve 36. The primary resin tank 31, the secondary resin tanks 32 and 33, and the switching valve 36 are connected to the control unit 10. Note that the number of secondary resin tanks connectable to the secondary die 22 via the supply pipe 35 is not limited to the two secondary resin tanks 32 and 33. For example, three or more secondary resin tanks may be connected, and in that case, any of three or more different colored colored resins can be selected by controlling the switching valve 36.

[0027] The coloring measuring device 5 is a device that detects the color of the colored resin in the secondary resin layer formed around the optical fiber strand coated with the primary resin. As the coloring measuring device 5, measuring devices such as an optical sensor, an image sensor, an area camera (area camera sensor), and a line camera (line camera sensor) are used. The coloring measuring device 5 is connected to the control unit 10 and transmits data regarding the detected colored resin to the control unit 10.

[0028] The ultraviolet irradiator 6 is a device that irradiates ultraviolet rays to the primary resin and the secondary resin applied to the glass fiber G1 to cure them. The ultraviolet irradiator 6 is connected to the control unit 10.

[0029] The outer diameter measuring device 7 is a device that measures the outer diameter of the colored optical fiber core wire G2 on which the primary resin layer and the secondary resin layer are formed. The outer diameter measuring device 7 measures the outer diameter of the colored optical fiber core wire G2 by irradiating laser light from the side of the colored optical fiber core wire G2, for example. The outer diameter measuring device 7 is connected to the control unit 10 and transmits the measured result to the control unit 10.

[0030] The take-up machine 9 winds the produced colored optical fiber core wire G2 around a take-up bobbin 91. The colored optical fiber core wire G2 is wound around the take-up machine 9 with a constant tension by passing through a capstan 92. The take-up machine 9 is connected to the control unit 10.

[0031] Based on the data regarding the colored resin transmitted from the color measuring device 5, the control unit 10 determines the quality of the color of the secondary resin. The determination of the quality of the color means determining whether the secondary resin layer is formed with the color of a predetermined colored resin sent out from the secondary resin tanks 32, 33, etc. Further, the control unit 10 controls the irradiation time or irradiation intensity of the ultraviolet irradiator 6, the winding speed of the take-up machine 9, etc., based on the data transmitted from the color measuring device 5, the outer diameter measuring device 7, etc.

[0032] Next, the manufacturing method of the colored optical fiber core wire according to the present embodiment will be described. The manufacturing method of the colored optical fiber core wire of the present embodiment is a method of manufacturing the colored optical fiber core wire G2 using the manufacturing apparatus 1 shown in FIG. 1.

[0033] [First Embodiment] With reference to FIGS. 2 to 4, a method for manufacturing a colored optical fiber core according to the first embodiment will be described below. FIG. 2 is a diagram showing a color measuring device 5A used in the method for manufacturing a colored optical fiber core according to the first embodiment. FIG. 3 is a diagram showing the irradiation timing of color light and the imaging timing of the camera in the color measuring device 5A. FIG. 4 is a diagram showing the brightness of the image captured by the camera. As shown in FIG. 2, the color measuring device 5A includes a red illumination 51R, a green illumination 51G, a blue illumination 51B, a camera 52, and an image display device 53. In the following description, the red illumination 51R, the green illumination 51G, and the blue illumination 51B may be collectively referred to as RGB illumination. As the RGB illuminations 51R, 51G, 51B, for example, LEDs that emit respective color lights of RGB are used. As the camera 52, for example, a monochrome area camera is used. The camera 52 as an area camera includes, for example, a two-dimensional image sensor having a plurality of pixels in the width direction and the longitudinal direction of the colored optical fiber core G2. As the image display device 53, for example, a personal computer is used. Each of the RGB illuminations 51R, 51G, 51B and the camera 52 is connected to the control unit 10.

[0034] (Wire drawing process) First, the optical fiber preform is drawn while being heated by a wire drawing device (not shown) to form a glass fiber G1.

[0035] (Coating process) Next, the control unit 10 controls the primary resin tank 31 to send the primary resin P from the primary resin tank 31 toward the primary die 21 through the supply pipe 34. The primary die 21 applies the primary resin P sent from the primary resin tank 31 around the glass fiber G1 passing through the primary die 21.

[0036] Next, the control unit 10 selects, for example, the secondary resin S1 in the secondary resin tank 32 by switching the switching valve 36, and causes the secondary resin S1 to be sent from the secondary resin tank 32 toward the secondary die 22 through the supply pipe 35. For example, when a red colored resin is stored in the secondary resin tank 32 as the secondary resin S1, the red secondary resin S1 is sent out from the secondary resin tank 32 toward the secondary die 22. The secondary die 22 applies the red secondary resin S1 sent from the secondary resin tank 32 around the primary resin P of the optical fiber strand passing through the secondary die 22.

[0037] Thereby, a red colored optical fiber core wire G2 coated with the primary resin P and the red secondary resin S1 is produced around the glass fiber G1.

[0038] (First inspection process) Next, in the colorimeter 5A, the control unit 10 irradiates the produced colored optical fiber core wire G2 with color lights from the red illumination 51R, the green illumination 51G, and the blue illumination 51B, respectively. The control unit 10 images the reflected light irradiated from the red illumination 51R, the green illumination 51G, and the blue illumination 51B and reflected by the colored optical fiber core wire G2 with the camera 52.

[0039] As shown in FIG. 3, the control unit 10 turns on the red illumination 51R, the green illumination 51G, and the blue illumination 51B in order at different timings. The control unit 10 images the reflected light reflected by the colored optical fiber core wire G2 with the camera 52 in synchronization with the lighting timings of the red illumination 51R, the green illumination 51G, and the blue illumination 51B.

[0040] The control unit 10 processes each image in the red illumination 51R, green illumination 51G, and blue illumination 51B captured by the camera 52 (a monochrome area camera), and detects the brightness (an example of the amount of light) of the reflected light reflected by the colored optical fiber core G2 in each image. Based on the detected brightness of each reflected light, the control unit 10 determines the color of the secondary resin of the colored optical fiber core G2. The color determination is made based on whether the brightness of each reflected light of the colored optical fiber core G2 in the red illumination 51R, green illumination 51G, and blue illumination 51B satisfies each predetermined threshold condition. When the red secondary resin S1 is being sent from the secondary resin tank 32 toward the secondary die 22 as in this example, the control unit 10 determines that the color of the secondary resin is red based on the brightness of each reflected light. When the color of the colored resin sent from the secondary resin tank 32 to the secondary die 22 is the same as the color of the secondary resin determined based on the brightness of the reflected light of the colored optical fiber core G2, the control unit 10 determines that the color of the colored optical fiber core G2 is "good".

[0041] As shown in FIG. 4, each image captured by the camera 52 and the brightness of the reflected light detected in each image may be displayed on the image display device 53. The brightness of the reflected light reflected by the red colored optical fiber core G2 is high when irradiated with the red illumination 51R (for example, brightness 255), and low when irradiated with the green illumination 51G and blue illumination 51B (for example, brightness 10). The control unit 10 determines the color of the secondary resin based on whether these brightness values "255" and "10" satisfy each predetermined threshold condition.

[0042] (Curing process) Next, the control unit 10 controls the ultraviolet irradiator 6 to irradiate the colored optical fiber core G2 with ultraviolet light to cure the primary resin P and the secondary resin S1.

[0043] (Second inspection process) Next, the outer diameter measuring device 7 measures the outer diameter of the colored optical fiber core G2 whose coating layer has been cured. The outer diameter measuring device 7 transmits the measured outer diameter value to the control unit 10.

[0044] (Winding process) Finally, based on the data transmitted from the color measurement device 5A, the outer diameter measurement device 7, etc., the control unit 10 controls the winder 9, and winds the red colored optical fiber core wire G2 onto the winding bobbin 91 at a predetermined linear velocity while applying a predetermined tension.

[0045] Next, after manufacturing the red colored optical fiber core wire G2 as described above, for example, the case of manufacturing a yellow colored optical fiber core wire G2 will be described.

[0046] In the coating process, the control unit 10 changes the secondary resin tank that sends the secondary resin to the secondary die 22 by switching the switching valve 36. The control unit 10 selects, for example, the secondary resin tank 33 in which the yellow colored resin is stored, and sends out the secondary resin S2, which is the yellow colored resin, from the secondary resin tank 33 toward the secondary die 22 through the supply pipe 35. The secondary die 22 applies the yellow secondary resin S2 sent from the secondary resin tank 33 around the primary resin P of the optical fiber strand passing through the secondary die 22.

[0047] However, when the secondary resin tank that sends out the secondary resin is switched from the secondary resin tank 32 to the secondary resin tank 33 by the switching valve 36, the red secondary resin S1 sent out from the secondary resin tank 32 remains in the supply pipe 35 between the switching valve 36 and the secondary die 22. Therefore, the yellow secondary resin S2 is not immediately supplied to the secondary die 22. Thus, immediately after switching the secondary resin tank, the red secondary resin S1 or a resin in which the red secondary resin S1 and the yellow secondary resin S2 are mixed is supplied to the secondary die 22. Then, the secondary die 22 applies the red secondary resin S1 or a resin in which the red secondary resin S1 and the yellow secondary resin S2 are mixed around the primary resin P of the optical fiber strand passing through the secondary die 22.

[0048] Therefore, in the coloring measurement of the coloring measuring device 5A in the first inspection process, even though the control unit 10 selects the secondary resin tank 33 containing the yellow secondary resin S2 when switching the switching valve 36, it determines that the color of the secondary resin based on the brightness of the reflected light reflected by the coloring optical fiber core wire G2 is not yellow. That is, the control unit 10 determines that the brightness of the reflected light does not satisfy the threshold condition previously defined for the yellow coloring optical fiber core wire G2, and determines that there is a difference between the color of the coloring resin sent to the secondary die 22 and the color of the secondary resin determined based on the brightness of the reflected light, and determines that the color of the coloring optical fiber core wire G2 is "no (defective)". "The brightness of the reflected light being equal to or higher than the threshold" is an example of "the color change satisfying the predetermined condition".

[0049] Thus, at the time of switching the switching valve 36, until the coloring resin (secondary resin) in the supply pipe 35 is replaced, it is determined that a coloring optical fiber core wire G2 of a color different from the setting is produced. And when the coloring resin in the supply pipe 35 is completely replaced, it is determined that the set yellow coloring optical fiber core wire G2 is produced, and the color of the coloring optical fiber core wire G2 is determined to be "good".

[0050] In the winding process, the control unit 10 winds, for example, the coloring optical fiber core wire G2 determined to be "no (defective)" as a defective product onto the winding bobbin 91 for defective products, and winds the yellow coloring optical fiber core wire G2 determined to be "good" as a non-defective product onto the winding bobbin 91 for non-defective products. Thus, the coloring optical fiber core wire G2 (defective product) determined to be "no (defective)" and the yellow coloring optical fiber core wire G2 (non-defective product) determined to be "good" may be wound onto different winding bobbins 91, or the defective coloring optical fiber core wire G2 and the non-defective coloring optical fiber core wire G2 may be continuously wound onto the same winding bobbin 91. When continuously winding the defective product and the non-defective product onto the same winding bobbin 91, it is preferable to be able to recognize the winding start position of the yellow coloring optical fiber core wire G2 determined to be a non-defective product. In addition, since each manufacturing method after color switching in other processes is the same as each manufacturing method described above, the description thereof is omitted.

[0051] As described above, the manufacturing method of the colored optical fiber core wire according to the first embodiment includes a step of feeding a colored resin (secondary resins S1, S2) into the secondary die 22, a step of passing an optical fiber element wire through the secondary die 22 and applying the colored resin around the optical fiber element wire to form a colored optical fiber core wire G2 provided with a colored layer, a step of detecting the color of the colored layer of the colored optical fiber core wire G2, and a step of determining whether the detected color of the colored layer is good or not. According to this method, the color of the colored resin supplied to the secondary die 22 can be switched by switching the switching valve 36. Then, it can be determined by the color measuring device 5A whether the colored optical fiber core wire G2 is correctly colored with the color of the resin after switching (whether the colored layer has changed from a defective color state to a good state). Therefore, when changing the color of the colored resin applied to the glass fiber G1, it is not necessary to replace / clean the equipment (die, piping, etc.) for applying the colored resin. Thereby, the color of the colored layer in the colored optical fiber core wire G2 can be flexibly switched according to the inventory and demand situation of the colored resin.

[0052] Further, in the manufacturing method of the colored optical fiber core wire, in the step of detecting the color, each of the RGB lights is irradiated onto the colored optical fiber core wire G2, and the reflected light of each of the RGB lights reflected by the colored optical fiber core wire G2 is imaged by the camera 52, thereby detecting the brightness (light amount) of the reflected light. Then, in the step of determining whether the color is good or not, it is determined whether the color of the colored layer is good or not based on the brightness of the reflected light. According to this method, it is possible to easily determine whether the color is good or not after switching the color of the colored resin by using the RGB illuminations 51R, 51G, 51B and one camera 52.

[0053] In addition, in the method for manufacturing a colored optical fiber core, in the step of detecting color, light from RGB illuminations 51R, 51G, and 51B is irradiated in order, and the timing of each irradiation of RGB light is synchronized with the imaging timing by the camera 52. According to this method, since the reflected light of the colored optical fiber core G2 is imaged by the camera 52 for each RGB light, the brightness of each reflected light can be accurately measured, and the color of the colored layer can be accurately judged as good or bad.

[0054] In addition, the method for manufacturing a colored optical fiber core includes a step of forming a glass fiber G1 by wire drawing while heating an optical fiber base material before the step of feeding a colored resin into the secondary die 22, and a step of forming an optical fiber strand provided with a primary resin layer by applying a primary resin P around the glass fiber G1. Then, in the step of feeding the colored resin into the secondary die 22, a step of feeding the first colored resin from the secondary resin tank 32 filled with the first colored resin used as the secondary resin S1 into the secondary die 22 and applying the first colored resin around the primary resin layer to form a secondary resin layer, and a step of feeding the second colored resin from the secondary resin tank 33 filled with the second colored resin having a color different from that of the first colored resin into the secondary die 22 and applying the second colored resin around the primary resin layer to form a secondary resin layer. In the step of detecting color, it is detected that the color of the secondary resin layer has changed from the color of the first colored resin to the color of the second colored resin. In the step of judging the quality of the color, when it is judged that the color change satisfies a predetermined condition, winding of the colored optical fiber core G2 as a good product is started. According to this method, the color of the colored layer can be judged based on a predetermined threshold value, and a good colored optical fiber core G2 that satisfies the threshold condition can be wound up. Therefore, the colored resin can be changed in color without increasing the wasted portion that does not become a good product.

[0055] In addition, the manufacturing apparatus 1 for the colored optical fiber core wire includes secondary resin tanks 32 and 33 that send out the colored resin into the secondary die 22, a secondary die 22 that allows the optical fiber element wire to pass through and applies the colored resin around the optical fiber element wire, a color measuring device 5 (sensor) that detects the color of the colored layer formed around the optical fiber element wire by the colored resin, and a control unit 10 that determines whether the color of the colored layer detected by the color measuring device 5 is good or not. According to this configuration, when the color of the colored resin supplied to the secondary die 22 is switched, it is possible to determine by the color measuring device 5A whether the colored optical fiber core wire G2 is colored with the color of the resin after the switch (i.e., whether it has changed from a defective color state of the colored layer to a good state). Therefore, when changing the color of the colored resin applied to the glass fiber G1, it is not necessary to replace or clean the equipment (such as dies and pipes) for applying the colored resin. As a result, the color of the colored layer in the colored optical fiber core wire G2 can be flexibly switched according to the inventory and demand situation of the colored resin.

[0056] In the above embodiment, the color measuring device 5 is provided between the resin coating die 2 and the ultraviolet irradiator 6, but it is not limited to this. The color measuring device 5 may be provided at other positions as long as it is between the resin coating die 2 and the take-up machine 9. However, since the color changes before and after the resin hardens, it is necessary to detect the color by setting a threshold value according to each state.

[0057] Also, in the above embodiment, the secondary resin applied around the optical fiber element wire coated with the primary resin is the colored resin, but it is not limited to this. For example, a primary resin and a secondary resin may be applied around the glass fiber and used as the optical fiber element wire, and a colored layer made of colored ink may be formed in the coloring process around the secondary resin of the optical fiber element wire.

[0058] Also, in the above embodiment, in order to shorten the color switching time of the coloring resin when switching the switching valve 36, for example, the position of the switching valve 36 may be set closer to the secondary die 22. In this case, for example, by switching the switching valve 36 in accordance with the replacement of the take-up bobbin 91, it becomes possible to change the color of the coloring resin during wire drawing while suppressing the amount of the colored optical fiber core wire G2 for which the color determination is "no (defective)".

[0059] Also, in the above embodiment, the switching valve 36 may be switched in accordance with the tip of the optical fiber preform being extruded. In this case, it is possible to use the colored optical fiber core wire G2 for which the color determination is "no (defective)" during the increase in the wire speed, and it is possible to start the good product take-up of winding the colored optical fiber core wire G2 for which the color determination is "good" onto the take-up bobbin 91 earlier. Thereby, it becomes possible to change the color of the coloring resin while suppressing the amount of the colored optical fiber core wire G2 for which the color determination is "no (defective)".

[0060] [Second Embodiment] Referring to FIG. 5, a method for manufacturing a colored optical fiber core according to the second embodiment will be described below. FIG. 5 is a diagram showing a color measuring device 5B used in the method for manufacturing a colored optical fiber core according to the second embodiment. As shown in FIG. 5, the color measuring device 5B includes a red laser light source 151R, a green laser light source 151G, a blue laser light source 151B, a red camera 152R, a green camera 152G, and a blue camera 152B. An infrared filter 153R that can transmit red laser light is attached to the red camera 152R. A green filter 153G that can transmit green laser light is attached to the green camera 152G. A blue filter 153B that can transmit blue laser light is attached to the blue camera 152B. The red laser light source 151R and the red camera 152R, the green laser light source 151G and the green camera 152G, and the blue laser light source 151B and the blue camera 152B are provided at positions facing each other with the colored optical fiber core G2 interposed therebetween. Each of the laser light sources 151R, 151G, 151B and each of the cameras 152R, 152G, 152B are connected to the control unit 10.

[0061] In the color measurement of the color measuring device 5B in the first inspection process, the control unit 10 irradiates color light from the red laser light source 151R, the green laser light source 151G, and the blue laser light source 151B toward the colored optical fiber core G2, respectively. The control unit 10 detects the amount of transmitted light that is irradiated from the red laser light source 151R, the green laser light source 151G, and the blue laser light source 151B and passes through the colored optical fiber core G2 with the red camera 152R, the green camera 152G, and the blue camera 152B, respectively.

[0062] The control unit 10 determines the color of the secondary resin of the colored optical fiber core G2 based on the detected light amount of each transmitted light. The color determination is made based on whether or not the light amounts of the respective transmitted lights of the colored optical fiber core G2 in the red laser light source 151R, the green laser light source 151G, and the blue laser light source 151B satisfy each predetermined threshold condition. When the control unit 10 determines that the light amount of each transmitted light satisfies the predetermined threshold condition, it determines that the color of the secondary resin determined based on the color of the colored resin sent to the secondary die 22 and the light amount of each transmitted light is the same color, and determines that the color of the colored optical fiber core G2 is "good". On the other hand, when the control unit 10 determines that the light amount of each transmitted light does not satisfy the predetermined threshold condition, it determines that the color of the secondary resin determined based on the color of the colored resin sent to the secondary die 22 and the light amount of each transmitted light is different, and determines that the color of the colored optical fiber core G2 is "no (defective)".

[0063] As described above, in the method for manufacturing a colored optical fiber core according to the second embodiment, in the step of detecting the color, each of the RGB lights is irradiated onto the colored optical fiber core G2, and the light amount of each transmitted light of the RGB light transmitted through the colored optical fiber core G2 is detected by the cameras 152R, 152G, 152B corresponding to each color light. In the step of determining whether the color is good or bad, it is determined whether the color of the colored layer is good or bad based on the light amount of each transmitted light. According to this method, based on the ratio of the transmitted light amounts of the RGB lights, it is possible to easily determine whether the color of the colored layer is good or bad after switching the color of the colored resin. Also, in the method of the second embodiment, it is possible to measure the transparency of the colored layer based on the intensity of the transmitted light amount. Therefore, even when the color of the colored layer is switched from a transparent color to an opaque color or from an opaque color to a transparent color, it is possible to detect whether the switching was correctly performed. Further, by using a single sensor instead of the cameras 152R, 152G, 152B (for example, an area camera, a line camera, etc.), the processing of the camera image can be eliminated, and thus a high-speed and low-cost colored measuring device 5B can be obtained.

[0064] In the above-described embodiment, cameras 152R, 152G, and 152B are used to detect the amount of transmitted light of each laser light source 151R, 151G, and 151B, but the present invention is not limited thereto. For example, a laser detection sensor may be used to detect the amount of light.

[0065] [Third Embodiment] With reference to FIGS. 6, 7A, and 7B, a method for manufacturing a colored optical fiber core wire according to the third embodiment will be described below. FIG. 6 is a diagram showing a color measuring device 5C used in the method for manufacturing a colored optical fiber core wire according to the third embodiment. FIG. 7A is a diagram showing the luminance distribution of an image captured by the camera of the color measuring device 5C. FIG. 7B is a diagram showing the change in the luminance distribution when the colored resin applied to the optical fiber element wire is switched. As shown in FIG. 6, the color measuring device 5C includes three white illuminations 251 arranged in three rotationally symmetric directions so as to surround the colored optical fiber core wire G2, and three color cameras 252. In this embodiment, one white illumination 251 and one color camera 252 are integrally formed. For the white illumination 251, for example, a white LED or the like is used. For the color camera 252, for example, a line camera is used. The color camera 252 as a line camera includes, for example, a one-dimensional image sensor having a plurality of pixels in the width direction of the colored optical fiber core wire G2. The imaging interval of the color camera 252 is preferably, for example, 1 kHz or more (1 msec or less). Each white illumination 251 and each color camera 252 are connected to the control unit 10.

[0066] In the color measurement of the color measuring device 5C in the first inspection step, the control unit 10 issues an instruction to irradiate the colored optical fiber core wire G2 with white light from each white illumination 251. Further, the control unit 10 issues an instruction to image the reflected light irradiated from the white illumination 251 and reflected by the colored optical fiber core wire G2 with each color camera 252. Further, the control unit 10 processes the images captured by each color camera 252 (line camera) and detects the RGB luminance (an example of the amount of light of the light) of the reflected light reflected by the colored optical fiber core wire G2 in each image.

[0067] Based on the RGB luminance of each detected reflected light, the control unit 10 determines the color of the secondary resin of the colored optical fiber core G2. The color determination is made based on whether the RGB luminance of each reflected light of the colored optical fiber core G2 under white illumination 251 satisfies each predetermined threshold condition. When the control unit 10 determines that the RGB luminance of the reflected light satisfies the predetermined threshold condition, it determines that the color of the secondary resin determined based on the color of the colored resin sent to the secondary die 22 and the RGB luminance of the reflected light is the same color, and determines that the color of the colored optical fiber core G2 is "good". On the contrary, when the control unit 10 determines that the RGB luminance of the reflected light does not satisfy the predetermined threshold condition, it determines that the color of the secondary resin determined based on the color of the colored resin sent to the secondary die 22 and the RGB luminance of the reflected light is different, and determines that the color of the colored optical fiber core G2 is "no (defective)".

[0068] For example, when the color of the secondary resin of the produced colored optical fiber core G2 is yellow, as shown in FIG. 7A, the RGB luminance of the reflected light reflected by the colored optical fiber core G2 is detected such that the luminance of R (red) and G (green) is high and the luminance of B (blue) is low. When these detected RGB luminance values satisfy the predetermined threshold condition for yellow, the control unit 10 determines that the color of the secondary resin is yellow.

[0069] Next, for example, the color measurement of the color measuring device 5C when switching from the state of producing the blue colored optical fiber core G2 to the state of producing the yellow colored optical fiber core G2 will be described.

[0070] As described in the first embodiment above, when the colored resin (secondary resin) sent out from the secondary resin tank is switched by the switching valve 36, there is a period during which the colored resin before switching and the colored resin after switching are mixed and supplied to the secondary die 22. Therefore, when switching from the production of the blue-colored optical fiber core G2 to the production of the yellow-colored optical fiber core G2 as in this example, as shown in FIG. 7B, during the predetermined period T1 at the time of switching, the RGB luminance of the reflected light reflected by the colored optical fiber core G2 becomes unstable.

[0071] In this case, the control unit 10 determines that the RGB luminance of the detected reflected light does not satisfy the threshold conditions previously defined for the yellow-colored optical fiber core G2 during the predetermined period T1, and determines that there is a difference between the color of the secondary resin determined based on the color and RGB luminance of the colored resin sent to the secondary die 22, and determines that the color of the colored optical fiber core G2 is "no (defective)".

[0072] Then, after the predetermined period T1, when the RGB luminance of the reflected light becomes stable and it is determined that the threshold conditions previously defined for the yellow-colored optical fiber core G2 are satisfied (during the period of T2), the control unit 10 determines that the color of the colored resin sent to the secondary die 22 and the color of the secondary resin determined based on the RGB luminance of the reflected light are the same color, and determines that the color of the colored optical fiber core G2 is "good".

[0073] In the above embodiment, the RGB luminance is measured using three white illuminations 251 and three color cameras 252, but it is not limited to this. For example, it may be measured using one white illumination 251 and one color camera 252.

[0074] As described above, in the method for manufacturing a colored optical fiber core according to the third embodiment, in the step of detecting the color, white light is irradiated from the white illumination 251 to the colored optical fiber core G2, and the reflected light of the white light reflected by the colored optical fiber core G2 is imaged by the color camera 252, thereby detecting the RGB luminance of the reflected light. In the step of determining the quality of the color, the quality of the color of the colored layer is determined based on the RGB luminance of the reflected light. According to this method, since it is not necessary to use light sources of different colors, the RGB luminance of each reflected light can be accurately measured with a simple configuration, and the quality of the color of the colored layer can be accurately determined.

[0075] Further, in the method for manufacturing a colored optical fiber core wire, in the step of detecting color, the colored optical fiber core wire G2 is imaged by a color camera 252 from three directions. According to this method, since the color camera 252 arranged in three directions can detect the color of the entire circumference of the colored optical fiber core wire G2 without omission, it is possible to accurately determine the quality of the color of the colored layer. Also, since imaging is performed from three directions, it is possible to detect a defective state in which the color is discontinuous at any position in the circumferential direction. Further, by using the color camera 252, which is a line camera capable of high-definition imaging, it is possible to detect small color defects in the longitudinal direction. Therefore, for example, it is also possible to detect leakage of discontinuous coloring such as a ring mark applied to the colored optical fiber core wire G2.

[0076] As described above, the present disclosure has been described in detail with reference to specific embodiments, but it is apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present disclosure. Also, the number, position, shape, etc. of the constituent members described above are not limited to the above-described embodiments, and can be changed to appropriate numbers, positions, shapes, etc. for implementing the present disclosure.

Explanation of Reference Numerals

[0077] 1: Manufacturing apparatus 2: Resin coating die 3: Resin tank 5(5A, 5B, 5C): Color measuring device 6: Ultraviolet irradiator 7: Outer diameter measuring device 9: Take-up machine 10: Control unit 21: Primary die 22: Secondary die 31: Primary resin tank 32, 33: Secondary resin tank 34, 35: Supply pipe 36: Switching valve 51R: Red illumination 51G: Green illumination 51B: Blue illumination 52: Camera 53: Image display device 91: Take-up bobbin 92: Capstan 151R: Red laser light source 151G: Green laser light source 151B: Blue laser light source 152R: Red camera 152G: Green camera 152B: Blue camera 153R: Red filter 153G: Green filter 153B: Blue filter 251: White illumination 252: Color camera G1: Glass fiber G2: Colored light fiber core P: Primary resin S1, S2: Secondary resin

Claims

1. A step of drawing while heating an optical fiber preform to form a glass fiber; A step of applying a primary resin around the glass fiber to form an optical fiber element wire having a primary resin layer; A step of feeding a colored resin into a die; A step of passing the optical fiber element wire through the die and applying the colored resin around the optical fiber element wire to form a colored optical fiber core wire having a colored layer; A step of detecting the color of the colored layer; A step of determining whether the detected color is good or not, including: In the step of feeding the colored resin into the die, A step of feeding the first colored resin filled in the first tank used as the secondary resin into the die, applying the first colored resin around the primary resin layer, and forming a first secondary resin layer; A step of switching from the first tank to a second tank filled with a second colored resin used as the secondary resin and having a color different from that of the first colored resin, feeding the second colored resin into the die, applying the second colored resin around the primary resin layer, and forming a second secondary resin layer; In the step of detecting the color, detecting that the color has changed from the color of the first colored resin in the first secondary resin layer to the color of the second colored resin in the second secondary resin layer; In the step of determining whether it is good or not, when it is determined that the color change is equal to or greater than a predetermined threshold, starting winding the colored optical fiber core wire as a good product. A method for manufacturing a colored optical fiber core wire.

2. In the step of detecting the color, irradiating the colored optical fiber core wire with light including RGB, and detecting a part of the light irradiated on the colored optical fiber core wire with a sensor, thereby detecting each light quantity of RGB of the light and detecting the color; In the step of determining whether the color is good or not, determining whether it is good or not based on each light quantity. The method for manufacturing a colored optical fiber core wire according to Claim 1.

3. In the step of detecting the color, when irradiating each light of RGB on the colored optical fiber core wire separately and detecting a part of each light with the sensor, synchronizing the irradiation timing of each light and the detection timing at the sensor, thereby detecting each light quantity of RGB of each light and detecting the color. The method for manufacturing a colored optical fiber core according to claim 2, wherein in the step of determining the quality of the color, the quality is determined based on each of the light amounts.

4. In the step of detecting the color, white light is irradiated onto the colored optical fiber core, and a part of the white light is detected by the sensor, thereby detecting each light amount of RGB of the light and detecting the color. The method for manufacturing a colored optical fiber core according to claim 2, wherein in the step of determining the quality of the color, the quality is determined based on each of the light amounts.

5. In the step of detecting the color, light including RGB is irradiated onto the colored optical fiber core, and transmitted light of the light transmitted through the colored optical fiber core is detected by the sensor, thereby detecting each light amount of RGB of the light and detecting the color. The method for manufacturing a colored optical fiber core according to any one of claims 2 to 4, wherein in the step of determining the quality of the color, the quality is determined based on each of the light amounts.

6. In the step of detecting the color, light including RGB is irradiated onto the colored optical fiber core, and reflected light of the light reflected by the colored optical fiber core is detected by the sensor, thereby detecting each light amount of RGB of the light and detecting the color. The method for manufacturing a colored optical fiber core according to any one of claims 2 to 4, wherein in the step of determining the quality of the color, the quality is determined based on each of the light amounts.

7. The method for manufacturing a colored optical fiber core according to any one of claims 2 to 6, wherein the sensor that detects a part of the light irradiated onto the colored optical fiber core is a line camera sensor having a plurality of pixels in the width direction of the colored optical fiber core.

8. The method for manufacturing a colored optical fiber core according to any one of claims 2 to 6, wherein the sensor that detects a part of the light irradiated onto the colored optical fiber core is an area camera sensor having a plurality of pixels in the width direction and the longitudinal direction of the colored optical fiber core.

9. The method for manufacturing a colored optical fiber core according to any one of claims 2 to 8, wherein in the step of detecting the color, a part of the light irradiated onto the colored optical fiber core is detected by the sensor from three directions.

10. A wire drawing device that forms a glass fiber by wire drawing while heating an optical fiber base material. A primary resin tank for sending a primary resin into a primary die; A primary die for passing the glass fiber therethrough and applying the primary resin around the glass fiber to form an optical fiber element wire having a primary resin layer; A secondary resin tank for sending a colored resin into a secondary die; A secondary die for passing the optical fiber element wire therethrough and applying the colored resin around the optical fiber element wire; A sensor for detecting the color of a colored layer formed around the optical fiber element wire by the colored resin; A control unit for determining the quality of the color detected by the sensor, and comprising: The secondary resin tank sends the first colored resin into the secondary die from a first tank filled with the first colored resin used as the secondary resin; The secondary die applies the first colored resin around the primary resin layer to form a first secondary resin layer; The secondary resin tank switches from the first tank to a second tank filled with a second colored resin used as the secondary resin and different in color from the first colored resin, and sends the second colored resin into the secondary die; The secondary die applies the second colored resin around the primary resin layer to form a second secondary resin layer; The sensor detects that the color has changed from the color of the first colored resin in the first secondary resin layer to the color of the second colored resin in the second secondary resin layer; When it is determined that the color change is equal to or greater than a predetermined threshold, the control unit starts winding the colored optical fiber core wire as a good product; A manufacturing apparatus for a colored optical fiber core wire.

Images