JP2597094B2 - Linear lighting fixture - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a linear lighting device.

[Prior Art] A lighting device that emits light incident on a circular end face in a linear manner,
It has been proposed in Japanese Patent Application Laid-Open No. 60-118806. Fig.
It is shown in FIG. The light-transmitting rod 4 is provided with the diffusing portion 5 linearly on the outer peripheral surface thereof, and emits light linearly along the rod, so that linear illumination without heat generation is possible.

However, this lighting fixture, when light is transmitted through the rod,
The loss is large and the amount of emitted light decreases as the distance from the incident end increases.

Even when a quartz glass rod with the best light transmission is used, the rod length 1
It is reported in the above publication that the brightness of the emitted light is reduced to 56% as compared with the case of 0 cm.

[Problems to be Solved by the Invention] The causes of light loss in the lighting fixture include light absorption of the rod material itself, scattering due to microscopic non-uniformity, fine irregularities on the rod surface, scratches, dirt, etc. There is seepage of light from that part. In particular, the loss due to imperfections on the rod surface is large, and the scattering from inside the material is superimposed on this,
As the rod length increases, the amount of emitted light decreases significantly.

An object of the present invention is to solve this problem of the lighting fixture.

[Means for Solving the Problems] The present invention has been made for the above-mentioned object, and has a structure in which the outer periphery of a side surface of a rod that transmits light is coated with a clad rod having a lower refractive index than the rod. And a linear illuminator characterized in that a linear groove formed in parallel with the axis of the rod is provided with a light diffusing portion formed by embedding a silicon resin mixed with titanium dioxide. is there.

Hereinafter, a description will be given according to an embodiment of the present invention. However, the present invention is not limited to this embodiment. FIG. 1 shows the basic configuration of the present invention. 1 is a light transmission rod, 2 is a clad, and 3 is a light diffusion material.

A groove extending from the clad surface to the rod was formed in a clad rod formed by simultaneously stretching and fusing the rod material and the clad material, and a light diffusing substance was embedded in the groove.

The boundary surface between the rod and the clad of the clad rod thus formed has a smooth mirror surface, and functions as a good reflection surface for light transmitted through the rod. Also,
In order to return the light transmitted to the rod end without hitting the diffusion surface to the inside of the rod again, the rod end, which is the surface facing the incident end surface, may be used as the reflection surface. As the material, quartz glass, multi-component glass, plastic, or the like can be used, but the clad material must have a lower refractive index than the rod material. As the diffusion material, a silicon resin mixed with TiO ₂ can be used.

Further, the groove itself can be roughened to be a diffusion surface. The shape and width of the groove are determined according to the required light quantity, illumination range, and the like. Generally, when the groove width is increased, the amount of emitted light increases, and the illumination range also increases. The number of grooves does not need to be one, and by increasing the number, the amount of emitted light can be increased.

In addition, as a manufacturing method of this lighting fixture,
After providing the diffusing surface, it is possible to coat the cladding, but again the rod-cladding interface must be as smooth and clean as possible.

[Operation] The light incident on the circular end of the clad rod is transmitted through the rod while repeating total reflection at the boundary surface between the rod and the clad. The light is emitted with directivity by the lens effect. This is shown in FIG. The exit angle is determined by the refractive index of the rod and cladding. If the refractive index difference between the rod and the clad is large, the critical angle will be small,
The light emission angle range in the direction perpendicular to the rod length direction becomes smaller. In the case of only the rod, the air can be considered to be the clad, so that the light emission angle range is smaller than that of the rod with the clad (FIG. 3A) (FIG. 3B). .

In the case of only cladding, the critical angle is smaller,
Since the angle range for total reflection can be widened, the loss should be small, but in reality, the light escapes from the rod surface and the loss is large. Cover the rod with clad,
By keeping the total reflection surface smooth and clean, the escape of light from the rod surface is suppressed, and the loss is reduced.

Example In this example, optical glass (refractive index 1.620) was used as the rod material, and soda lime glass (refractive index 1.516) was used as the cladding material. Core: clad ratio is about 10:
Is one. Titanium dioxide (refractive index 2.9
03) was mixed with a silicone resin (refractive index: 1.404) and poured into a groove provided parallel to the rod axis. The clad rod diameter is 10 mm, the groove width is 1.2 mm, and the rod length is 1 m. Further, in order to return the light transmitted to the rod end without hitting the diffusion surface to the rod end again, the rod end which is the surface opposite to the incident end surface was provided with an aluminum plate as a reflection surface.

The measurement results using a halogen lamp with a reflector (12V 500W) as the light source show that the illuminance is about 1000lux at a distance of 10cm from the rod, and about 4cm in the length direction of the rod from the entrance end and reflection end. Mura Was able to be suppressed. (L: illuminance) In the case where the same rod material is not covered with the clad according to the method of the above-mentioned document and a diffusion portion having the same width is provided,
When the same measurement was performed, the illuminance was about 700lux at maximum,
Illuminance unevenness was about 18%, and it was confirmed that the illuminance increased and the illuminance unevenness decreased by coating the clad.

[Effect of the Invention] By using a clad rod for the optical transmission body and making the total reflection surface a smooth mirror surface, light escape from the surface is reduced,
This makes it possible to achieve linear illumination with low loss and small illumination unevenness compared to the case of using only a rod.

This illumination device can change the light emission angle by using the same rod material and using claddings having different refractive indexes.

Also, as in the case of only the rod, scratches on the rod surface,
It is also a great advantage that there is no need to cover with a protective tube for preventing dirt and the like. In addition, since titanium dioxide having a high refractive index is mixed with silicon resin having a low refractive index and provided in the groove, and the main total reflection due to the difference between the two refractive indexes is used, the reflection and diffusion efficiency of light is extremely high. Good.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the basic structure of the present invention. 1 is a rod, 2 is a clad, and 3 is a light diffusing substance. FIG. 2 shows a basic configuration of a lighting fixture proposed in the conventional example. 4 is a rod, 5 is a light diffusing substance, and 6 is a halogen lamp. FIGS. 3A and 3B are explanatory diagrams showing the state of emission in a direction perpendicular to the incident direction, wherein FIG. 3A shows the case of the present invention and FIG. 3B shows the case of a rod without cladding.

Claims (1)

(57) [Claims] 1. A linear groove formed on the outer periphery of a side surface of a rod that transmits light, from a clad rod surface coated with a clad having a lower refractive index than the rod to the rod, and formed in parallel with the axis of the rod. A linear lighting device comprising a silicon resin mixed with titanium dioxide embedded therein.