JP4216418B2 - PLASTIC OPTICAL FIBER, MANUFACTURING METHOD THEREOF, AND LIGHTING DEVICE USING THE PLASTIC OPTICAL FIBER - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of light guide, light emission, and illumination, and particularly relates to an optical fiber having excellent side leakage characteristics and an illumination device that performs light guide and light emission using the optical fiber.
[0002]
[Prior art and problems to be solved by the invention]
The light emitted from the primary light source is incident on the optical fiber from the end face of the optical fiber, guided in the optical fiber, and appropriately leaked from the side surface of the optical fiber, so that the side surface of the optical fiber is secondary light source. Can be used to illuminate (illuminate) the outside. Moreover, such a side light leakage optical fiber can be used for illumination (electrical decoration).
[0003]
As a plastic optical fiber for illumination using such side light leakage (hereinafter abbreviated as “POF” where appropriate), a core made of polymethyl methacrylate (PMMA) is usually a fluorine polymer having a lower refractive index than the core. A core-sheath structure having a diameter of about 1.0 mm to 0.5 mm and a structure covered with a sheath made of In order to obtain a sufficient amount of light, a bundle of a plurality of optical fibers is used. In this case, in order to improve the side light leakage characteristics of the optical fiber and to make the amount of light leakage uniform, when the optical fibers are bundled, they are twisted together in a spiral shape. In addition, the optical fiber bundled in this manner is housed in a tube such as a transparent vinyl chloride resin to form an illuminating body, and a light source is disposed at at least one end of the illuminating body. The lighting device is composed of the above.
[0004]
However, it is quite difficult to bundle POF uniformly in a spiral shape over the entire length direction, and there is a problem in that the amount of light emitted from the side surface of the POF tends to be uneven in the length direction.
[0005]
Japanese Patent Application Laid-Open No. 7-72341 discloses that bubbles are formed in the POF in the POF quenching step by 0.1-4 times shorter and longer diameters than the POF diameter, and the side light leakage is increased based on light scattering by the bubbles. Illuminated POF is described.
[0006]
However, since the POF described in JP-A-7-72341 generates large scattering, the light transmission characteristic (light guide characteristic) is greatly impaired. When this POF is used at a long distance, light leakage in the longitudinal direction occurs. The amount of this non-uniformity becomes large, and this POF, like other conventional POFs, has a large frictional resistance on the surface, so that excessive rubbing occurs, for example, when the POF is stored in the tube in the process after spinning. The surface of the POF is likely to be damaged due to, etc., and in this case, the amount of light leakage differs greatly between the damaged part and the damaged part, and the damaged part appears as a bright spot or bright line. is there.
[0007]
Accordingly, the object of the present invention is that the uniformity of side leakage in the longitudinal direction of the optical fiber is good, and even if the surface of the optical fiber is slightly damaged, the damaged part is difficult to see as a bright spot or bright line, and the surface friction is An object of the present invention is to provide a plastic optical fiber that has a low resistance and that can be easily bundled and housed in a transparent tube for manufacturing a lighting device.
[0008]
Another object of the present invention is to provide an illumination device using such a plastic optical fiber.
[0009]
[Means for Solving the Problems]
According to the present invention, in order to achieve the above-described object, a plurality of layers are formed on the surface of the sheath portion of the core-sheath plastic optical fiber at a depth of 20% to 90% of the layer thickness of the sheath portion. There is provided a plastic optical fiber characterized in that a depression is formed.
[0010]
In one aspect of the invention, Has a protective layer on the outer periphery of the core-sheath structure A plurality of depressions are formed on the surface of the protective layer of the plastic optical fiber at a depth of 20% to 100% of the thickness of the protective layer. In one embodiment of the present invention, a plurality of protective layers having a depth of 20% to 100% of the thickness of the protective layer are formed on the surface of the protective layer of the plastic optical fiber having the protective layer on the outer peripheral portion of the sea-island structure. A depression is formed. Moreover, in 1 aspect of this invention, the circular equivalent diameter of the said depression part is 50 micrometers or less. In one embodiment of the present invention, the plurality of depressions have an area ratio of 20 to 80% with respect to the surface of the plastic optical fiber.
[0011]
Furthermore, according to the present invention, there is provided a method for producing the plastic optical fiber as described above, wherein (a) a plastic optical fiber having a core-sheath structure, (b) Has a protective layer on the outer periphery of the core-sheath structure Evaporable or sublimable fine particles on the surface layer of a plastic optical fiber or (c) a plastic optical fiber having a protective layer on the outer periphery of a sea-island structure in a soft state body Are sprayed to form a plurality of depressions on the surface of the plastic optical fiber of (a), (b) or (c), and the evaporable or sublimable fine particles in the depressions body A method for producing a plastic optical fiber is provided, wherein the surface layer portion of the plastic optical fiber is cured by evaporating or sublimating.
[0012]
In one aspect of the present invention, the evaporable or sublimable fine particles body Is injected at a temperature that contributes to heating of the surface layer of the plastic optical fiber. In one embodiment of the present invention, the evaporable or sublimable fine particles body Consists of water. In one embodiment of the present invention, the evaporable or sublimable fine particles body Is started while the surface layer portion of the plastic optical fiber is in a softened state following the spinning process of the plastic optical fiber.
[0013]
Furthermore, according to the present invention, an illuminating device comprising: an illuminating body formed by bundling a plurality of plastic optical fibers as described above; and a light source disposed at at least one end of the illuminating body, Is provided.
[0014]
In one aspect of the present invention, the illuminator includes a light-transmitting tube that covers the plurality of plastic optical fibers.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
[0016]
(First embodiment)
FIG. 1 is a schematic cross-sectional view showing a configuration of an embodiment of a plastic optical fiber (POF) having a core-sheath two-layer structure according to the present invention. A sheath portion 11 is formed around the core portion 10 so as to cover the core portion 10. The cross-sectional shape of the POF is preferably a circular shape, but is not limited thereto, and may be a noncircular shape such as an elliptical shape. The outer diameter of the POF is not particularly limited, but is about 0.5 to 20 mm, for example. If the outer diameter of the POF is too large, the flexibility may be reduced, making it difficult to bend.
[0017]
Examples of the material constituting the core 10 include organic materials such as polymethyl methacrylate (PMMA), polycarbonate, and polystyrene. The material for the core 10 is preferably PMMA, which is inexpensive and excellent in transparency, but a copolymer of methyl methacrylate (MMA) and benzyl methacrylate (BzMA) is also a preferred material. In other words, this copolymer is a material that has very little light scattering, can have a higher refractive index than PMMA, and can increase the incident angle of light that can be transmitted by POF. Thus, the amount of side light leakage can be increased and can be suitably used as the core material of the POF of the present invention.
[0018]
Examples of the material constituting the sheath portion 11 include materials such as polyvinylidene fluoride, vinylidene fluoride / tetrafluoroethylene copolymer, and fluoroalkyl methacrylate / methyl methacrylate copolymer. Although the thickness (layer thickness) of the sheath part 11 is not specifically limited, For example, it is 2-20 micrometers, Preferably it is 4-10 micrometers.
[0019]
In order to promote light leakage from the side surface of the POF (the outer surface of the sheath portion 11 in this embodiment), a large number of depressions 12 are formed on the surface of the sheath portion 11. FIG. 2 shows a development view of the surface of the sheath 11. As shown in FIG. 2, the depressed portion 12 preferably has a substantially circular shape (including a shape that is not completely circular, such as an elliptical shape), and the dimensions thereof are circular equivalent diameters (major axis and minor axis). The average value is preferably 50 μm or less, more preferably 30 μm or less, and particularly preferably 20 μm or less. If the size of the depressed portion 12 is too large, the number of the depressed portions 12 that can be formed is reduced, and the depressed portion is visually recognized as a bright spot at the time of side light leakage observation, which may reduce the illumination effect. is there. In addition, if the size of the depressed portion 12 is too small, it may be difficult to form a depressed portion having a depth that can provide a sufficient light leakage enhancement effect. Therefore, the circular equivalent diameter of the depressed portion 12 may be 5 μm or more. preferable. The depth of the depressed portion 12 is 20% to 90% of the layer thickness of the sheath portion 11, preferably 20% to 70%, and more preferably about 30% to 50%. If the depth of the depressed portion 12 is too deep and reaches the core portion 10, the optical transmission characteristic (light guide characteristic) of the POF is greatly impaired, and the dependency of the side light leakage intensity attenuation on the POF length increases. If the depth of the depressed portion 12 is too shallow, a sufficient light leakage promoting effect may not be obtained.
[0020]
On the side of the POF, it is preferable that a large number of depressions 12 are distributed as uniformly as possible, and the area ratio occupied by the depressions 12 is preferably 20 to 80%, and more preferably 40 to 60%. . If the area ratio of the depressed portion 12 on the POF surface is too small, there is a possibility that a sufficient light leakage promoting effect cannot be obtained. If it is too large, mechanical properties such as repeated bending characteristics and fracture characteristics of the POF are deteriorated. There is a fear.
[0021]
In addition, in order to reduce the light absorption in the sheath part 11 and increase the amount of light leakage from the POF side surface, a material having excellent transparency is selected as the material of the sheath part 11 covered with the core part 10. Is particularly preferred.
[0022]
When light is incident and guided from the end portion of the core-sheath POF having the sheath portion 11 in which the depressed portion 12 is formed as described above, a part of the light in the core portion 10 is sheathed. It progresses to the part 11, reaches | attains the depression part 12 in this sheath part, and radiate | emits in this depression part 12, and POF side surface light leakage is accelerated | stimulated.
[0023]
(Second Embodiment)
FIG. 3 is a schematic cross-sectional view showing a configuration of an embodiment of a POF having a three-layer structure of a core-sheath-protective layer according to the present invention. In this embodiment, although it has the core part 10 and the sheath part 11 which consist of the material similar to the said 1st Embodiment, unlike the 1st Embodiment, the depression part is formed in the sheath part 11. In addition, a protective layer 20 is formed around the sheath portion 11 so as to cover the sheath portion 11.
[0024]
Examples of the material constituting the protective layer 20 include the same material as that of the sheath portion 11, but materials such as polymethyl methacrylate and polycarbonate may be used. Although the thickness (layer thickness) of the protective layer 20 is not specifically limited, For example, it is 2-15 micrometers, Preferably it is 5-10 micrometers.
[0025]
In order to reduce the light absorption in the sheath part 11 and the protective layer 20 and increase the amount of light leakage from the POF side surface, the material of the sheath part 11 and the protective layer 20 covered by the core part 10 is excellent in transparency. It is particularly preferable to select the material.
[0026]
In order to cause light leakage from the side surface of the POF (in this embodiment, the outer surface of the protective layer 20), a large number of depressions 12 ′ are formed on the surface of the protective layer 20. The recessed portion 12 ′ is preferably substantially circular, like the recessed portion 12 of the first embodiment, and the size is preferably, for example, 50 μm or less, more preferably 30 μm or less in terms of a circular equivalent diameter. Particularly preferably, it is 20 μm or less. Moreover, it is preferable that the circular equivalent diameter of depression part 12 'is 5 micrometers or more. However, the depth of the depressed portion 12 ′ is 20% to 100% of the thickness of the protective layer 20, preferably 20% to 90%, and more preferably about 50% to 70%. In the case of the core-sheath-protective layer structure, even if the depressed portion 12 ′ reaches the sheath portion 11, the optical transmission function of the POF is not significantly impaired, but this is one purpose of providing a protective layer. In some cases, the effect of improving the resistance to repeated bending resistance of POF may be lowered. From this point, even in the case of the core-sheath-protective layer structure, it is desirable that the depressed portion 12 ′ does not reach the sheath portion 11 and is not too deep. . Further, if the depth of the depressed portion 12 ′ is too shallow, there is a possibility that a sufficient light leakage promoting effect cannot be obtained.
[0027]
In addition, in order to reduce the light absorption in the sheath part 11 and the protective layer 20 and increase the amount of light leakage from the POF side surface, the material of the sheath part 11 and the protective layer 20 covered by the core part 10 is transparent. It is particularly preferable to select a material that is superior to the above.
[0028]
When light is incident and guided from the end of the core-sheath POF having the protective layer 20 formed with the depression 12 'as described above, a part of the light in the core 10 is obtained. Proceeding to the sheath part 11, further proceeding to the protective layer 20, reaching the depressed part 12 'in the protective layer, and exiting into the depressed part 12', POF side light leakage is promoted.
[0029]
(Third embodiment)
FIG. 4 is a schematic cross-sectional view showing a configuration of an embodiment of a sea-island POF with a protective layer according to the present invention.
[0030]
In the present embodiment, a plurality of island portions 30 each having a core or core-sheath structure are used, and the plurality of island portions 30 are arranged in the sea portion 31 to protect the periphery so as to cover the sea portion 31. Layer 20 is formed.
[0031]
As a core and a sheath of the island part 30, what consists of the material similar to the core part and sheath part which were demonstrated in the said 1st Embodiment can be used. Moreover, as the sea part 31, what consists of the material similar to the sheath part demonstrated in the said 1st Embodiment and the protective layer demonstrated in the said 2nd Embodiment can be used. As the protective layer 20, a layer made of the same material as that described in the second embodiment can be used.
[0032]
The cross-sectional shape of the island part 30 is typically circular or hexagonal, and the diameter of the island part 30 is not particularly limited, but is preferably about 20 to 1000 μm. The number of island portions 30 is not particularly limited, but is preferably about 5 to 200, for example. The arrangement of the plurality of island portions 30 in the sea portion 31 is preferably substantially stacked as shown in FIG.
[0033]
In order to cause light leakage from the side surface of the POF (in this embodiment, the outer surface of the protective layer 20), as in the second embodiment, a large number of depressions 12 'are formed on the surface of the protective layer 20. .
[0034]
By using a material having a lower bending elastic modulus than the material of the island part 30 as the material of the sea part 31, the bending elastic modulus of the POF can be lowered and the flexibility can be improved.
[0035]
In addition, in order to reduce the light absorption in the sea part 31 and the protective layer 20 and to increase the amount of light leakage from the POF side surface, the material of the sea part 31 and the protective layer 20 surrounding the island part 30 is excellent in transparency. It is particularly preferred to select the material.
[0036]
When light is incident and guided to the POF having the sea-island structure having the protective layer 20 having the depressed portion 12 ′ as described above, a part of the light in the island portion 30 is obtained. Proceeding to the sea part 31, further proceeding to the protective layer 20, reaching the depressed part 12 ′ in the protective layer and emitting into the depressed part 12 ′, and POF side light leakage is promoted.
[0037]
The multi-core POF as described above has a small increase in light leakage from the fiber due to bending due to its structure, and even when applied to an application where it is bent so as to have a small radius of curvature, local light leakage at the bent portion. It is possible to perform illumination with little increase and excellent light leakage uniformity.
[0038]
(Fourth embodiment)
FIG. 5 is a schematic cross-sectional view showing an embodiment of a method for producing a POF according to the present invention. This figure particularly shows a process of forming a depression on the POF surface.
[0039]
In the present embodiment, fine particles are applied to the surface at high speed (jetting) while the fiber surface layer portion is softened, for example, during or immediately after the heat drawing process or heat treatment process in general plastic optical fiber manufacturing. The surface layer portion is cured after forming the depressed portion on the POF surface.
[0040]
As fine particles, it is possible to use quartz sand, glass beads or the like used when the surface of the resin or the like is treated, but such solid matter bites into or remains on the surface of the POF. It is not necessarily preferable for the injection of fine particles for forming the depression on the outer surface of the POF.
[0041]
Therefore, in the present embodiment, as the ejected fine particles, those made of a material that can be easily removed from the POF surface by evaporation or sublimation by heating or the like such as water, ice and dry ice are used. And when the injection | pouring microparticles | fine-particles which consist of these evaporable or sublimable materials are used, it is possible to make it act as a POF cooling refrigerant | coolant after a fiber heat processing process, and is convenient. In particular, water vapor (water), which can easily give energy to the fine particles that collide with the POF at a high speed and can simultaneously function as a heat source for softening the surface layer of the POF, is vaporizable for producing the POF of the present invention. It is particularly preferably used as a material, and the surface temperature of the POF is softened by uniformly spraying the entire surface of the POF at a water vapor temperature of about 100 ° C. to 150 ° C. under conditions near the saturated pressure where the water vapor is in a gas-liquid mixed state. And fine water droplets body It is possible to simultaneously perform the formation of the depressed portion of the surface by the collision.
[0042]
In FIG. 5, while the POF 40 having no depression on the surface is running upward so as to pass through the central portion of the porous cylinder 42, for example, from the outside of the porous cylinder to the inside of the porous cylinder through the numerous holes of the porous cylinder 42. Steam of about 120 ° C. is supplied by injection. The porous cylinder 42 is disposed in a steam heating furnace, and the flow resistance when the saturated pressurized steam supplied from the porous cylinder is discharged from both ends of the porous cylinder, or leakage of water vapor provided at both ends of the porous cylinder. Due to the pressure loss in the seal mechanism that prevents the pressure, the pressure is maintained against the atmospheric pressure.
[0043]
In the porous cylinder 42, the surface layer portion of the POF 40 is softened, and water vapor fine particles are formed on the surface. body The depression is formed by jetting. Thereby, the depression part is formed in the surface of POF40 which came out of the steam heating furnace, and the water fine particle injected here body Is removed by evaporation. At that time, the POF is cooled.
[0044]
Such fine particles body In the process of forming the depressed portion by injection, an external force is applied to the POF surface, and based on this, a birefringent structure is partially formed in the sheath portion 11 or the protective layer 20 where the depressed portions 12, 12 ′ are formed. Therefore, in addition to the light leakage promoting effect based on the surface shape of the depressions 12 and 12 ′, the light leakage promoting effect based on optical scattering by the birefringent structure is also added.
[0045]
In addition, since a large number of depressions 12 and 12 'having a uniform distribution that can be regarded as pseudo flaws are formed on the surface, and a large amount of light leakage can be generated from these portions, before and after the depression formation. Even if the surface of the POF 40 is damaged by spinning, post-treatment, processing, etc., the light leakage from the damaged portion is mixed with the light leakage from the depressed portion, so that it is not visually recognized as a remarkable bright spot.
[0046]
(Fifth embodiment)
FIG. 6 is a partial cross-sectional perspective view showing an embodiment of a lighting device using a POF according to the present invention.
[0047]
A plurality of (for example, 20 to 100) POFs 40 as in the first to third embodiments or the POFs 40 obtained in the fourth embodiment are bundled to have a light transmitting property (preferably transparent). The illuminating body 46 is formed by being housed in the conductive tube 44, and the primary light source 48 is disposed so as to face at least one end surface of the illuminating body 46. Thereby, an illuminating device is obtained. The plurality of POFs 40 may be arranged in parallel to each other, or may be twisted in an appropriate form.
[0048]
As the light-transmitting and flexible tube 44, for example, a tube made of vinyl chloride resin or polyethylene having a thickness of about 1 mm can be used. The length of the tube 44 can be sufficiently about 30 m. As the light source 48, a known light source can be used, but a light source having a large light amount such as a halogen lamp, a metal halide lamp, or a high-pressure mercury lamp is preferably used.
[0049]
When manufacturing a lighting device according to this embodiment, when a bundle of a plurality of POFs 40 is inserted into the tube 44, the surface of the POF 40 has a number of depressions, so that the POF has a satin finish. The frictional resistance at the time of contact between each other or between the POF and the tube inner surface is low, damage due to rubbing between the POFs or between the POF and the tube inner surface can be reduced, and the POF can be easily inserted into the tube.
[0050]
Furthermore, in order to promote light leakage, it is better to twist the POF in the tube. However, in this embodiment, since the light leakage promoting effect based on the depression is sufficiently large, it is not necessary to twist the POF. It becomes easier to load POF inside.
[0051]
In the illumination device of the present embodiment, a considerable portion of the light transmitted through each POF can be extracted to the outside due to the light leakage promoting effect due to the depression on the POF surface, and the amount of light leakage along the longitudinal direction of the POF The uniformity of distribution is good, and defects such as specific bright spots and light intensity spots can be reduced.
[0052]
【Example】
The present invention will be specifically described below with reference to examples. In the examples, “parts” means parts by weight.
[0053]
[Example 1]
As shown in FIG. 1, polymethylmethacrylate is used as the material for the core, and a copolymer of vinylidene fluoride / tetrafluoroethylene = 72/28 (parts) is used as the material for the sheath. A POF having a core-sheath structure as described above was produced.
[0054]
That is, first, the core material resin and the sheath material resin are passed through a melt extruder set at a temperature of 220 ° C. and a metering gear metering pump into a two-layer composite spinning nozzle used for ordinary POF spinning. Then, it was discharged from the composite spinning nozzle, taken up at a constant speed, and subsequently heated and stretched twice using a hot air heating furnace at 140 ° C. to obtain a POF having a normal core-sheath structure. The outer diameter of POF was about 1000 μm, and the layer thickness of the sheath was about 6 μm.
[0055]
Next, the normal POF obtained as described above is passed through a steam heating furnace in which sealing mechanisms are provided at both ends and a porous cylinder is arranged on the outer periphery of the POF passage part, and the internal pressure of the steam heating furnace is reduced. The absolute pressure is maintained at 0.2 Mpa, and water vapor of 120 ° C. is injected and supplied to the outer surface of the POF through the hole of the porous cylinder, and the circular converted diameter is about 10 μm from the surface to the surface of the POF sheath. A large number of substantially mortar-shaped depressions having a depth of about 3 μm were formed to obtain a POF as shown in FIG. On the side of the POF, the area ratio occupied by the depression was about 50%.
[0056]
60 POFs were bundled in parallel with each other, and housed in a transparent vinyl chloride resin tube having an outer diameter of 12 mm, an inner diameter of 10 mm, and a length of 20 m, to produce a lighting body. The POF storage operation was easy, and there was no difficulty in insertion due to friction between the tube inner surface and the POF.
[0057]
A light source is arranged facing both ends of the illuminating body (both ends of the POF bundle), light emitted from the light source is incident on each POF, light is guided through each POF, and light is leaked from the side surfaces of the POF. When light was leaked from the side of the tube, there was almost no unevenness in the lengthwise direction, and no specific bright spot was observed.
[0058]
[Example 2]
Polymethyl methacrylate is used as the material for the core, and 2,2,2-trifluoroethyl methacrylate (3FM) / 2- (perfluorooctyl) ethyl methacrylate (17FM) / methyl methacrylate (MMA) is used as the material for the sheath. / A copolymer of methacrylic acid (MAA) = 51/30/18/1 (part), and a copolymer of vinylidene fluoride / tetrafluoroethylene = 72/28 (part) as a material for the protective layer. The core-sheath-protective layer structure POF as shown in FIG. 2 was produced as follows.
[0059]
That is, first, in the same manner as in Example 1 except that the core material resin, the sheath material resin, and the protective layer material resin were supplied to a three-layer composite spinning nozzle used for normal POF spinning, POF having a core-sheath-protective layer structure was obtained. The outer shape of the POF was about 1000 μm, and the layer thickness of the sheath and the layer thickness of the protective layer were both about 5 μm.
[0060]
Next, the normal POF obtained as described above was treated in the same manner as in Example 1, and the surface of the protective layer of POF had an approximately mortar shape with a circular equivalent diameter of about 10 μm and a depth of about 3 μm from the surface. A large number of depressions were formed, and a POF as shown in FIG. 3 was obtained. On the side of the POF, the area ratio occupied by the depression was about 50%.
[0061]
60 POFs were bundled in parallel with each other, and housed in a transparent vinyl chloride resin tube having an outer diameter of 12 mm, an inner diameter of 10 mm, and a length of 20 m, to produce a lighting body. The POF storage operation was easy, and there was no difficulty in insertion due to friction between the tube inner surface and the POF.
[0062]
A light source is arranged facing both ends of the illuminating body (both ends of the POF bundle), light emitted from the light source is incident on each POF, light is guided through each POF, and light is leaked from the side surfaces of the POF. When light was leaked from the side of the tube, there was almost no unevenness in the lengthwise direction, and no specific bright spot was observed.
[0063]
Example 3
Polymethylmethacrylate (PMMA) is used as the material for the core (island), and a copolymer of vinylidene fluoride / tetrafluoroethylene = 72/28 (parts) is used as the material for the sea and the protective layer. Then, a POF having a sea-island structure as shown in FIG. 3 was manufactured as follows. In addition, a material having a lower melt viscosity at the same temperature as the sea part material was used as the protective layer material.
[0064]
That is, as a composite spinning nozzle, 37 inner layers (hole diameter 1.0 mm) / outer layer (a trumpet shape spreading from a hole diameter 1.1 mm to a hole diameter 2.3 mm) in a cross section of φ20 mm are stacked in a stack of 37 nozzles. It has a structure that is arranged almost evenly, has a funnel-shaped throttle part with an inlet diameter of φ20 mm and a discharge hole diameter of φ4 mm below the outer layer nozzle hole, and a protective layer material introduction part on the outer peripheral side surface of the inlet part of the throttle part The installed structure was used. Then, the core material resin is introduced into the inner layer nozzle, the sea portion material resin is supplied to the outer layer nozzle, the protective layer material resin is introduced into the protective layer material introduction portion, and discharged from each outer layer nozzle below the outer layer nozzle. The sea part material resin to be fused is discharged from the composite spinning nozzle, taken out at a constant speed, and heated twice using a 140 ° C. hot air heating furnace, and the island part is made of only PMMA. A normal sea-island POF having 37 islands having a protective layer on the outer periphery was produced. The outer diameter of POF was 1000 μm, the diameter of the island portion was about 150 μm, and the thickness of the protective layer was about 5 μm.
[0065]
Next, the POF obtained as described above is treated in the same manner as in Example 1, and the surface of the protective layer of POF has a substantially mortar shape having a circular equivalent diameter of about 10 μm and a depth of about 3 μm from the surface. Many depressions were formed, and a POF as shown in FIG. 4 was obtained. On the side of the POF, the area ratio occupied by the depression was about 50%.
[0066]
60 POFs were bundled in parallel with each other, and housed in a transparent vinyl chloride resin tube having an outer diameter of 12 mm, an inner diameter of 10 mm, and a length of 20 m, to produce a lighting body. The POF storage operation was easy, and there was no difficulty in insertion due to friction between the tube inner surface and the POF.
[0067]
A light source is arranged facing both ends of the illuminating body (both ends of the POF bundle), light emitted from the light source is incident on each POF, light is guided through each POF, and light is leaked from the side surfaces of the POF. When light was leaked from the side of the tube, there was almost no unevenness in the lengthwise direction, and no specific bright spot was observed.
[0068]
【The invention's effect】
As described above, the optical fiber of the present invention has good uniformity of side light leakage without unevenness in the amount of light over the entire length direction, and even if the surface of the optical fiber is slightly damaged, the damaged part is a bright spot or bright line. It is difficult to see as. In addition, since the optical fiber of the present invention has a small frictional resistance on the surface, it is easy to bundle a plurality and store them in a transparent tube, and an illumination device can be easily manufactured using this.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a configuration of an embodiment of a plastic optical fiber (POF) having a core-sheath two-layer structure according to the present invention.
FIG. 2 is a development view of the surface of the sheath portion of the plastic optical fiber (POF) of the embodiment of FIG. 1;
FIG. 3 is a schematic cross-sectional view showing a configuration of an embodiment of a plastic optical fiber (POF) having a three-layer structure of a core-sheath-protective layer according to the present invention.
FIG. 4 is a schematic cross-sectional view showing a configuration of an embodiment of a sea-island structure plastic optical fiber (POF) with a protective layer according to the present invention.
FIG. 5 is a schematic cross-sectional view showing an embodiment of a method for producing a plastic optical fiber (POF) according to the present invention.
FIG. 6 is a partial cross-sectional perspective view showing an embodiment of a lighting device using a plastic optical fiber (POF) according to the present invention.
[Explanation of symbols]
10: Core part
11: sheath
12, 12 ': depression
20: Protective layer
30: Island
31: Kaifu
40: Plastic optical fiber (POF)
42: perforated tube
44: Translucent flexible tube
46: Lighting body
48: Light source

Claims (1)

A plastic optical fiber in which a plurality of depressions are formed on the surface of a sheath portion of a plastic optical fiber having a core-sheath structure at a depth of 20% to 90% of the layer thickness of the sheath portion, or a core-sheath On the surface of the protective layer of the plastic optical fiber having a protective layer on the outer periphery of the structure or the sea-island structure, a plurality of depressions are formed at a depth of 20% to 100% of the thickness of the protective layer. A method of manufacturing a plastic optical fiber , comprising:
(A) Plastic optical fiber having a core-sheath structure, (b) Plastic optical fiber having a protective layer on the outer periphery of the core-sheath structure, or (c) Plastic optical fiber having a protective layer on the outer periphery of the sea-island structure A plurality of depressions are formed on the surface of the plastic optical fiber of (a), (b) or (c) by injecting evaporating or sublimating fine particles onto the softened surface layer of A method for producing a plastic optical fiber, comprising evaporating or sublimating the evaporable or sublimable fine particles in the section to cure a surface layer portion of the plastic optical fiber.

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