JPH06242319A - Illumination tube - Google Patents

Abstract

PURPOSE:To improve an illumination tube appropriate as a secondary light source fat a decorative illumination and to remove the unenvenness of luminance generated in the longitudinal direction of the tube. CONSTITUTION:The inside of a cylindrical body 11 having transmissivity is filled with elastomer as a core material 12. Particulates 13 are mixed with the core material 12 so that their density is increased in accordance with a distance separated from the light incident end of the body 11. Thereby the luminance of incident light is increased by the light dispersion of the particulates 13 and a linear illuminating body reducing the unevenness of luminance distribution in the longitudinal direction can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting tube that introduces light emitted from a light source and converts it into light that is spatially wide and highly decorative.

[0002]

2. Description of the Related Art As a secondary light source that introduces light from a primary light source and converts its irradiation pattern, there is a linear optical waveguide represented by an optical fiber, most of which are from the end face of the fiber. The emitted light is used.

Therefore, this type of secondary light source has a disadvantage that it is suitable for local illumination but not for decorative illumination because it becomes spot light whose emission direction is limited and the irradiation range is extremely narrow.

Therefore, as a secondary light source suitable for decorative illumination, a transparent tubular body having an inner wall surface with an appropriate surface roughness is filled with a core material having a refractive index higher than that of the tubular body. An illumination tube was developed (Japanese Patent Laid-Open No. 18750/1989).
No. 5). When using this lighting tube as a secondary light source, the light of the primary light source is introduced from one end, but the introduced light is, except for the loss specific to the core material,
Most of the light propagates in the tubular body by repeating total internal reflection between the core material and the tubular body. Here, if the interface between the core material and the tubular body is a perfectly smooth surface, there should be no light leakage from the tubular body to the outside, but as described above, the inner wall surface of the tubular body has an appropriate surface roughness. Therefore, in the process of repeating the reflection of light, the condition of total reflection is broken for a part of the light to cause light leakage, and as a result, it is possible to cause the illumination tube to emit light over the entire longitudinal direction.

Further, in a light source device in which a surface of a plastic light guide plate on which light is incident from an end face is subjected to a light diffusion process, and light is emitted from the surface, fine particles having different refractive indexes in the light guide plate. In some cases, the brightness of the emitted light is increased by the light scattering of the fine particles (Japanese Patent Laid-Open No. 4-145485).

[0006]

By the way, the above-mentioned illumination tube emits light in a wide range of the entire peripheral surface of the tubular body, and can realize a decorative illumination which is spatially wide and has excellent distinguishability. Therefore, it can be said that the secondary light source is more suitable for decorative illumination than a simple optical waveguide such as an optical fiber.

However, with only the light leakage due to the interface roughness as described above, only the light in the lower mode propagates as the distance from the light incident end face increases, and the amount of light leakage from the peripheral surface of the tubular body is attenuated, so that the illumination There arises a problem that uneven brightness occurs in the longitudinal direction of the tube.

When fine particles are mixed in the light guide plate as described above, light is scattered by the fine particles and the brightness of light can be increased. However, this is for the entire light guide plate, and uneven brightness is eliminated. Not something to do.

Therefore, an object of the present invention is to further improve an illumination tube suitable as a secondary light source for decorative illumination as described above so as to eliminate the uneven brightness occurring in its longitudinal direction.

[0010]

In order to solve the above-mentioned problems, the present invention provides a cylindrical body which is made of a synthetic resin having a light-transmitting property and has at least one end serving as a light incident end. In a lighting tube made of a core material filled with an elastomer having a large refractive index and a light-transmitting property, and the core material is mixed with fine particles having a different refractive index from the elastomer, the core material is The distribution density of the fine particles was increased.

The light incident end may be one end or both ends of the tubular body. In the case of one end, the distribution density of fine particles increases according to the distance from the light incident end, and the distribution density peaks at the opposite end. Fine particles should be mixed in such a manner that the distribution density of fine particles increases from both incident ends to the center of the tubular body at both ends, and the distribution density of the fine particles reaches a peak in the center of the tubular body. Fine particles may be mixed in.

Examples of the fine particles to be mixed include inorganic or organic fine particles such as alumina, titanium oxide, barium oxide, silica, polymethylmethacrylate, polystyrene and polyacrylic acid ester.

[0013]

With the illumination tube constructed as described above, as it gets away from the light incident end, strong scattered light leakage is caused by the fine particles, and attenuation of the amount of light leakage from the peripheral surface of the tubular body is suppressed.

[0014]

EXAMPLES Examples will be described below with reference to the drawings. As shown in FIG. 1, the illumination tube 10 is formed by filling a light-transmissive tubular body 11 with an elastomer as a core material 12. The core material 12 contains fine particles 13 for light scattering. It is mixed.

The cylindrical body 11 has an inner diameter of 2 mm and a wall thickness of 1 m.
m, 1.5 m long polytetrafluoroethylene (PTFE)
It is made of a tube (made by Nichias) and has a refractive index of 1.35. As the elastomer constituting the core material 12, a transparent silicone rubber (a transparent potting RTV rubber compound KE-
103), the refractive index of which is the cylindrical body 11
Which is larger than that of 1.40. In addition, the fine particles 1
An alumina powder having a particle diameter of 0.3 μm (manufactured by Marumoto Kogyo Co., Ltd.) is used as 3, and its refractive index is 1.68, which is different from the core material 12. The distribution density of the fine particles 13 in the core material 12 is not uniform over the entire length of the tubular body 11, and increases as the distance from the light incident end increases. Specifically, when the fine particles 13 in the core material 12 are expressed by weight ratio,
As shown in FIG. 2, fine particles 13 are hardly mixed up to 40 cm from the light incident end, and 40 cm to 100 cm.
The weight ratio gradually increases between 100 cm and 150 cm
During the period, the weight ratio is 0.0066%, which is substantially constant.

Illumination tube 10 constructed as described above
3, the light generated by the light source device (150 W halogen) 20 is introduced with one end as a light incident end, and the light is emitted from the outer peripheral surface of the tubular body 11 in the radial direction 20.
The illuminance at positions separated by mm was measured using the illuminometer 30 over the entire length in the longitudinal direction.

Similarly, in the conventional example (1), an elastomer having no fine particles mixed therein is used as the core material, and an elastomer having the fine particles uniformly mixed in a weight ratio of 0.0066% is used as the core material. As the conventional example (2), the illuminance was measured for each, and the results are shown in a graph as shown in FIG.

Further, based on the above measurement results, Table 1 shows the amount of attenuation of the illuminance at the position 1 m from the position 5 cm from the light incident end for the conventional examples (1) and (2) and the example.

[0019]

[Table 1]

The illuminance drop was improved by about 1.1 dB with respect to the conventional example (1) and about 13.2 dB with respect to the conventional example (2). It is understood that the difference in the density of the fine particles in the core material as described above can prevent the decrease in the amount of light leakage when the fine particles are not mixed as in the conventional example (1). In particular, the fact that this effect is obtained by providing a difference in the particle density is clear by comparison with the conventional example (2) in which the particles are uniformly mixed.

As described above, when light is made to enter from the end face side of the illumination tube having a small particle density, the light incident portion has a brightness equal to or higher than that of an illumination tube in which particles are not mixed, and The brightness from the central part to the end part is higher than that of the lighting tube in which no fine particles are mixed, and as a result, it is possible to obtain a linear lighting body with less unevenness in the brightness distribution in the longitudinal direction.

In this embodiment, one-sided incidence is used, but the present invention is not limited to this, and both-sided incidence is also possible. However, in the case of both-side incidence, it is necessary to make the particle density highest near the center of the illumination tube.

[0023]

As described above, according to the illumination tube of the present invention, the density of the fine particles in the core material increases as the distance from the light incident end of the cylindrical body increases. It is possible to obtain a linear illumination body that stimulates scattered light leakage, suppresses the attenuation of the amount of light leakage from the peripheral surface of the cylindrical body, and has less unevenness in the luminance distribution over the entire length.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment according to the present invention.

FIG. 2 is a relationship diagram of a weight ratio of fine particles mixed in a core material and a distance from a light incident end face.

FIG. 3 is a schematic diagram showing a method of measuring the amount of light leakage of an illumination tube.

FIG. 4 is a relationship diagram between a distance from a light incident end face and illuminance.

[Explanation of symbols]

 10 Illumination tube 11 Cylindrical body 12 Core material 13 Fine particles 20 Light source device 30 Illuminance meter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuro Akasaka 1-1-14 Nishisuehiro-cho, Yokkaichi-shi, Mie Sumitomo Wiring Systems, Ltd.

Claims (1)

[Claims] 1. A tubular body, which is made of a synthetic resin having a light-transmitting property and has at least one end serving as a light-incident end, is filled with an elastomer having a refractive index larger than that of the tubular body and having a light-transmitting property as a core material. In an illumination tube in which fine particles having a refractive index different from that of the elastomer are mixed in the core material, the distribution density of the fine particles increases as the distance from the light incident end of the tubular body increases. Lighting tube.