JP2000035514A - Optical fiber and color developing device using the optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the occurrence of a dark part at the boundary part of a discharge tube or at the boundary part of an optical fiber so as to realize multicolored display by incorporating at least one coloring part in which a color developing body is dispersed in a clad. SOLUTION: The optical fibers 14a to 14j are equipped with what is called a core 16 occupying a center part and the clad 18 provided at a periphery part surrounding the core 16 and having a lower refractive index than the core 16, respectively. Then, the optical fibers 14a to 14j are equipped with the coloring parts 18a and 18b having different colors uniformly in a peripheral direction by the color developing body which develops color by pigments along in the longitudinal direction at the desired position of the clad 18 in the optical fibers 14a to 14j, At such a time, a connection member 19 consisting of a thermal contraction tube made of FEP intervenes between the coloring parts 18a and 18b so as to connect both of them. The core 16 does not have a joint which prevents the transmission of light corresponding to the boundary part between the coloring parts 18a and 18b. Therefore, the optical fiber can multicolored light emission over a comparatively long distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber, particularly to a side emission type optical fiber, and a light emitting device using the same.

[0002]

2. Description of the Related Art A discharge tube such as a fluorescent lamp emits light having a specific wavelength, and is usually used as a light emitting device for illumination. In particular, when the discharge tube is a neon tube, it is used for displaying advertisements or decorations in the form of a so-called neon sign. The discharge tube emits light when a voltage is applied, and at that time, the discharge tube generally generates heat. Therefore, when using the discharge tube as a light emitting device, it is necessary to use the discharge tube in consideration of electric leakage and heat. Further, for such a reason, it is practically impossible to use the discharge tube for, for example, illumination or display in water.

However, recently, in order to realize the above-described illumination or display, a light-emitting device having a light source arranged at a place remote from a place where illumination or display is to be performed (hereinafter also referred to as “illumination place”) has been developed. Attention has been paid. In such a light emitting device, an optical fiber for connecting them is provided between a light source and a lighting place. In general, an optical fiber includes a so-called core at the center thereof, and a cladding having a lower refractive index than the core at a peripheral portion surrounding the core, and transmits light incident from one end of the optical fiber to the other end. be able to. In particular, U.S. Pat.
No. 2,719 and JP-A-60-118806 disclose a side emission type optical fiber capable of emitting light from a side surface portion of the optical fiber to illuminate a relatively large area. I have.

In general, an optical fiber is colorless and transparent and does not emit light by itself, so that the light emitted from one end depends on the light source to be connected to the other end. However, WO 98/08024 also discloses a side emission type optical fiber having a clad colored with a pigment. Such an optical fiber is used for displaying advertisements or decorations like a neon tube without requiring a special light source.

[0005]

A variety of displays may be provided by a light emitting device having optical fibers having different colors from each other, especially for advertisement or decoration using a discharge tube such as a neon tube. This is remarkable in display applications.
However, in the case of such a multi-color display, more or less dark portions are generated to the extent that they cannot be ignored not only at the boundary between the discharge tubes emitting different colors but also at the boundary between the optical fibers emitting different colors. In general, such a dark portion generated at the boundary between the discharge tube and the optical fiber draws attention of an observer who sees a display of an advertisement or decoration, and impairs or reduces the original effect of the advertisement or decoration. There is a possibility that. Further, when such a light emitting device is used for illumination, the generated dark portion may cause unevenness in the illuminance distribution.

Accordingly, the present invention provides a method of using an optical fiber for display such as advertisement or decoration using a discharge tube such as a neon tube or the like at the boundary between the discharge tube and the optical fiber. An object of the present invention is to provide an optical fiber capable of performing various displays while suppressing generation of a dark portion. Another object of the present invention is to provide a light emitting device using such an optical fiber.

[0007]

According to the present invention, there is provided an optical fiber comprising a central core, and a clad provided at a peripheral portion of the core with a lower refractive index than the core. An optical fiber is provided, wherein the clad includes at least one colored portion in which a color former is dispersed.

According to the present invention, there is provided a light source, and at least one end connected to the light source, comprising a central core and a clad provided at a peripheral edge of the core with a lower refractive index than the core. There is provided a light emitting device comprising at least one optical fiber, wherein the cladding includes at least one colored portion in which a coloring material is dispersed.

In the optical fiber of the present invention, the colored portions are preferably provided with different colors along the longitudinal direction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below according to its embodiments. In the drawings, the same or corresponding portions are denoted by the same reference numerals. FIG. 1 schematically illustrates a light-emitting device according to a preferred embodiment of the present invention. In the illustrated light-emitting device 10, a specific character is emitted by a combination of a plurality of optical fibers 14a to 14j. It can be displayed (in the illustrated example, English character A is displayed).

The light emitting device 10 will be described with reference to FIG. 1. Basically, the light emitting device 10 has side-emitting optical fibers 14a to 14j and optically connected to one end of each optical fiber. Plurality of light sources 12a to 12j
And the other end of each optical fiber (light sources 12a to 12
A plurality of light sources 12k to 12t optically connected to an end where j is not connected) are provided. Light source 12
a to 12t are disposed near both ends of the optical fibers 14a to 14j, respectively. Although the light source is not limited to those listed below, for example, a metal halide lamp (LB, manufactured by 3M, Minnesota, USA)
M130H (trade name), a light emitting diode (LED), a halogen lamp, condensed sunlight, or the like. The light source is a metal halide lamp,
In the case of halogen lamps or condensed sunlight, the light-emitting device is used for large-scale display or illumination, while in the case of light-emitting diodes, it is used for relatively small-scale display or illumination. Although not shown, the light source may be provided with a color filter and a control unit for controlling the color filter, and may arbitrarily change the color of light introduced into the optical fiber.

The arrangement of the light sources is not limited to the above embodiment. Although not shown, the light source may be directly connected to both ends of the optical fiber in order to suppress light leakage at both ends of the optical fiber. Also, a single light source may be connected to one or both ends of each optical fiber. Alternatively, two light sources may be connected to one end of each optical fiber. The connection of each optical fiber to the light source is not limited to the above embodiment. For example, although not shown, a light source may be connected to only one end of each optical fiber. In such a case,
A reflection member is attached to the other end of each optical fiber,
It is fundamental to prevent light from leaking from the end.
Also, a single light source may be connected to one or both ends of each optical fiber.

The optical fibers 14a to 14j are basically
As conceptually shown in the partial sectional side view of FIG. 2, a so-called core 16 occupying a central portion, and a clad 1 having a lower refractive index than the core 16 in a peripheral portion surrounding the core 16.
8 is provided. The core 16 is made of a solid material such as quartz glass, optical glass, or a light transmissive material such as a polymer, and has a refractive index of 1.4 to 2.0. The light transmissive material is generally a solid, but is not limited thereto, and may be made of a liquid. However, when a liquid light-transmissive material is used for forming the core 16, the core liquid is sealed in a flexible tube made of resin, for example, to prevent liquid leakage.

The cladding 18 is made of a light-transmitting resin such as a tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Further, the clad 18 is preferably colored by including a color forming body 20 such as a light scattering particle or a dye which is colored by a pigment. In particular, in the present embodiment, as shown in FIG. 1, the above-described color former uniformly has different colors along the longitudinal direction at desired positions of the cladding 18 of the optical fibers 14 a to 14 j in the circumferential direction. It has coloring portions 18a and 18b. At this time, a connecting member 19 made of a heat shrinkable tube made of FEP is interposed between the colored portion 18a and the colored portion 18b to connect them. Such a light emitting device can display a variety of characters including the English character A as shown in the figure by using different colors emitted by the color forming bodies.
Preferably, the cladding 18 comprises 100 parts by weight of the color former 20 so that the optical fibers 14a to 14j can scatter light isotropically over a wide range in the longitudinal direction using the color former 20. 0.01 to resin
It is contained in the range of 10 parts by weight. More preferably, the cladding 18 contains the color former 20 in the range of 0.1 to 1 part by weight based on 100 parts by weight of the cladding resin. in this case,
The uniformity of the colors of the colored portions 18a and 18b in the circumferential direction enables display substantially independent of the viewing direction.

In the present embodiment, the above-described colored portion 1
Core 1 covered with cladding 18 having 8a and 18b
6 does not have a seam that obstructs light transmission corresponding to the boundary between the colored portions 18a and 18b. Therefore, this optical fiber can emit various lights over a relatively long distance, and as a result, display by light emission can be performed on a large scale.

Next, a method for manufacturing the above optical fiber will be described with reference to a preferred example. Therefore,
The following preparation methods can be variously modified within the scope of the present invention, as can be easily understood by those skilled in the art. To generate cladding occupying a central portion of the optical fiber, first, for example DuPont Teflon ^TM
A resin pellet, FEP100-J, for example, is prepared in an amount of 10 kg. In addition, for example, inorganic pigment pellets (TFM0166Blue pellets or TFM012
A pellet containing a blue or red inorganic pigment as a color former, such as a 2Red pellet, is prepared, for example, in an amount of 1 kg. Next, the prepared Teflon ^™ pellets and inorganic pigment pellets are mixed with a mixer. Thereafter, the obtained mixture is molded using a conventional general extruder (extruder). For example, a tubular first clad precursor having an outer diameter of 12 mm and a thickness of 0.8 mm and having a specific color can be obtained.

Further, a second clad precursor having a color different from that of the first clad precursor but having the same dimensions is produced by the same method as described above. Then, after these clad precursors are cut into appropriate dimensions, they are joined together, for example, via a FEP heat-shrinkable tube as a connecting member. The desired cladding is obtained. Next, in order to produce a core surrounding the produced clad,
A mixed solution of monomers is prepared by mixing parts by weight of 2-ethylhexyl methacrylate, 100 parts by weight of n-butyl methacrylate, and 2 parts by weight of triethylene glycol dimethacrylate. Thereafter, bis (4-t-butylcyclohexyl) peroxydicarbonate is further added to the mixed solution of the monomers as a polymerization initiator to prepare a core precursor. Next, after the clad prepared in the above-described step is bent into a U-shape, a core precursor is injected into the inside of the clad from one end of the bent clad. Then, when the core precursor is heated to the polymerization initiation temperature, a seamless solid core is formed inside the clad, and a side emission type optical fiber is obtained.

In the above-described optical fiber manufacturing process, the heating of the core precursor is basically performed sequentially from the bottom to the top of the U-shaped clad. At that time, the core precursor may be brought into contact with an inert gas such as nitrogen or argon to give pressure thereto. Thereafter, in order to completely react the core precursor, the entire core precursor may be heated together with the clad for a predetermined time. Further, the clad may be expanded in advance by heat in order to prevent a gap from being formed between the core and the clad due to contraction that occurs when the reaction of the core precursor is completed. This is because, after the core is reacted, the clad can also be thermally contracted.

The light emitting device 10 having the optical fibers 14a to 14j as described above is constituted, and the optical fibers 14a to 14j
When light is introduced from the other end of j using any of the light sources 12a to 12t associated with each optical fiber, at the interface between the core 16 and the cladding 18,
The light travels along the longitudinal direction of the core 16 as indicated by an arrow A in FIG. However, some light having a particular wavelength is substantially isotropically scattered by the color former 20 in the cladding 18 as shown in FIG. Some of the light thus scattered travels again in the longitudinal direction toward the inside of the core by total internal reflection as shown by arrow B, but the rest goes out of the core as shown by arrow C. It heads directly and exits out of the optical fiber and is observed by an observer.

At this time, the brightness of the light emitted from the optical fiber to the outside may be relatively reduced due to the absorption of the light by the color former or the clad. However, the optical fiber of the present embodiment has a sufficiently high luminance enough to ensure nighttime visibility. Further, the optical fiber of the present embodiment is colored, and high visibility can be secured by itself without using a light source during the day. Therefore, this optical fiber can basically emit light colored in the longitudinal direction without requiring a special light source, and can be used for displaying advertisements or decorations day or night instead of neon tubes, for example. Can be used for

Also, the boundary between the different colored regions of the cladding may be out of the core without being totally reflected at the periphery of the core, but is generally darker than its surroundings. However, of the isotropically scattered light, the light is emitted through the boundary between regions of different colors. As a result, in the present embodiment, compared to the case of performing various light emission displays using a plurality of optical fibers that emit different colors, the lowering of the brightness at the boundary portion is suppressed, and the regions emitting different colors are continuously formed. Can be formed. As a result, it is not necessary to illuminate the optical fiber from its back surface to compensate for the decrease in brightness at the boundary.

The present invention has been described with reference to an optical fiber that can emit two different colors along the longitudinal direction. However, the present invention is not limited to this. As shown in FIG. 3, the optical fiber 14 has colored portions 18a to 18c having three different colors formed by a color forming body (not shown) or colored portions having more colors (see FIG. 3). (Not shown).
The light emitting device in this case can display more various displays than the light emitting device of the above-described embodiment, and can further attract the observer's attention. Alternatively, the optical fiber may partially include a colored portion having at least one color in the substantially colorless and transparent clad.

Although not shown, the clad may have two or more different colored regions along its circumferential direction. In this case, unlike a neon tube that can perform only a single display, various displays can be performed by changing the display format depending on the observation direction of the clad.

[0024]

As described above, when the optical fiber of the present invention is used for display such as advertisement or decoration by a discharge tube such as a neon tube or the like, the boundary portion of the discharge tube or the boundary of the optical fiber. There is an effect that various displays can be performed while suppressing the occurrence of a dark portion in a portion. Therefore,
The optical fiber of the present invention can be used for displaying advertisements or decorations day or night, instead of neon tubes or the like.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a light emitting device according to one embodiment of the present invention.

FIG. 2 is a partial side sectional view conceptually showing an optical fiber according to another embodiment of the present invention.

FIG. 3 is an enlarged sectional view illustrating another configuration of the optical fiber of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Light-emitting device 12 ... Light source 14 ... Optical fiber 16 ... Core 18 ... Cladding 18a ... Colored part 18b ... Colored part 19 ... Connection member 20 ... Coloring body

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Claims (3)

[Claims] 1. An optical fiber comprising: a central core; and a clad provided at a peripheral edge of the core with a lower refractive index than the core, wherein the clad is colored by dispersing a color former. An optical fiber comprising at least one portion. 2. The optical fiber according to claim 1, wherein the colored portions are provided with colors different from each other along a longitudinal direction. 3. A light source, and at least one optical fiber having at least one end connected to the light source, a central core, and a cladding provided at a peripheral edge of the core with a lower refractive index than the core. A light emitting device comprising: a light emitting device, wherein the clad includes at least one colored portion in which a coloring material is dispersed.