JPS636767Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a light box that can be used for illuminated signboards, electric bulletin boards, transparent stands, etc.

More specifically, the present invention relates to a thin light box that can eliminate light unevenness on the illumination surface of the light-transmitting table or the like.

Traditionally, in illuminated signboards with built-in fluorescent tubes, lighting fixtures, and transparent stands used for traces that use transparent light, etc., a reflective base plate that uses light absorption as a means of uniforming the light on the illuminated surface. The shape of the surface is devised and many fluorescent tubes are installed. Examples include using a diffuser plate with high light diffusivity and low light transmittance on the illumination surface, and further increasing the distance between the fluorescent tube and the illumination surface. However, all of these methods have drawbacks such as high light loss, complicated internal structure, wasted energy, and high cost of equipment and equipment.

Furthermore, in the past, there have been seen viewing tables that have a reflector plate with a V-shaped cross section and both ends facing the illumination surface between the fluorescent tube and the illumination surface in a cross section perpendicular to the tube axis of the fluorescent tube. With these devices, it was possible to reduce the thickness of the device to some extent by eliminating light unevenness on the illumination surface. However, since the reflector has a light-shielding property, the slope of the light intensity on any plane immediately above the reflector becomes large. Therefore, it is necessary to increase the distance between the reflector and the illumination surface to diffuse the light. For this reason, it has been difficult to make a so-called thin light box using the reflector.

The object of the present invention is to provide a light box that eliminates the above-mentioned drawbacks and has a uniform illumination surface. In detail, by improving the light box that uses the light unevenness removing member (Japanese Patent Application No. 53-087284) invented by the present inventor, we can create a thin light box with no light unevenness and further reduce energy consumption and cost. be.

The features of this invention are to achieve the above-mentioned purpose.
The face angle θ is set to θ>90°. By setting θ>90°, the angle of reflection of the light from the fluorescent tube that is irradiated onto the reflective surface of the light unevenness removing member is increased, and the light that is irradiated onto the surface of the transparent member that also constitutes the light unevenness removing member is increased. The method is to increase the surface reflectance of the transparent member by increasing the reflection angle of the transparent member.

Next, the present invention will be explained based on examples.

1 and 2 show a light box 1 according to an embodiment of the present invention.

In Figures 1 and 2, the housing 2 whose inner surface is painted white has an acrylic milk half plate 4 with a thickness of 2 mm forming the illumination surface 3, and a transparent member 5 made of a transparent acrylic plate with a thickness of 1.5 mm. A light unevenness removing member 7 formed with a reflective surface 6 having distribution characteristics, a fluorescent tube 8,
8' are arranged parallel to each other at intervals of 250 mm.
The transparent member 5 is bent by a heating means so that the plane angle θ=100°, and the distance from the bending line to the end face is 75°.
mm. The reflective surface 6 is formed with silver reflective ink in the form of halftone dots by screen printing.
The halftone dot is formed so that it gradually becomes smaller as the distance from the fluorescent tubes 8, 8' increases, and its reflection distribution characteristics are almost reciprocal to the light intensity distribution irradiated from the fluorescent tubes 8, 8'. It's getting old.

Next, when the light box 1 shown in FIG. 1 was turned on and the illumination surface 3 was observed, no light unevenness was observed. Further, when light was measured on the illumination surface 3 in a direction perpendicular to the tube axes of the fluorescent tubes 8, 8' using an XY recorder and a photo sensor, the light intensity distribution was uniform as shown in a of FIG. Next, the light unevenness removing member 7
When the lens was removed and photometry was performed, it showed the light intensity distribution characteristic shown in Fig. 3b. Furthermore, when the planar light unevenness removing member 9 shown in FIG. 4 was attached and photometry was carried out, the light intensity distribution characteristic shown in c in FIG. 3 was obtained.

FIG. 5 shows a light box 10 according to another embodiment of the present invention.

In FIG. 5, the optical unevenness removing member 11 is made up of a transparent member 12 made of transparent styrene, and a transparent polyester film 14 having a reflective surface 13 formed of an aluminum vapor-deposited surface is adhered by a transparent adhesive. The reflective surface 13 is the film 1 whose entire surface is vapor-deposited with aluminum.
4 is formed into a slit shape parallel to the tube axis of the fluorescent tube 15 by etching.

Next, when this light box 10 was photometered using the method described above, the light intensity was approximately 20% lower at the minimum value than the maximum value. However, the unevenness of the light on the illuminated surface could not be seen with the naked eye. Furthermore, the width of each fluorescent tube that appeared to be uniform in light to the naked eye was about 1.3 times that of the light box 1 of the above-mentioned embodiment.

As mentioned above, the light box of the present invention has a surface angle of θ
By setting θ > 90°, the angle of reflection of the light from the fluorescent tube toward the reflective surface becomes large, so that more light can be directed to dark areas away from the fluorescent tube. Similarly, since the angle of reflection of the light from the fluorescent tube directed toward the surface of the transparent member becomes larger especially in the portion closer to the end face of the transparent member, the surface reflectance of the transparent member can be increased. Therefore, even though it is transparent, it is possible to spread the light to a dark area further away from the fluorescent tube and make the light uniform.

As is clear from the explanation in Fig. 3, the light box of the present invention can brighten even darker areas than the light box equipped with a planar light unevenness removing member. It is possible to efficiently remove light unevenness on a large area illumination surface.

Furthermore, by setting θ>90°, the number of repeated reflections for uniformizing light within the light box is reduced, so that a light box with low light loss and high efficiency can be obtained.

In the present invention, the material of the transparent member is not particularly limited as long as it is transparent, and a plurality of materials may be combined. Note that the higher the refractive index of the transparent member, the more effective it is in increasing the surface reflectance.

In addition to silver reflective ink and aluminum vapor deposition, the material forming the reflective surface may be white ink, metal plating, etc., and a coating agent for protecting these may be applied to the surface. In this way, there are no limitations on the material or forming method of the material forming the reflective surface. Further, the reflective surface may be formed on the surface of the transparent member that faces the illumination surface.

In addition, in the present invention, the face angle θ is not particularly limited as long as it is in the range θ>90°, but if the thickness of the light box, the spacing between the fluorescent tubes, the light loss, etc. are taken into consideration, it is preferably 90°<θ. A range of <150° was appropriate.

Furthermore, the illumination surface is not limited to one side, but may be a double-sided type in which the illumination surfaces are opposed to each other.

As explained above, the light box of the present invention can efficiently remove light unevenness, so it is thin and has no uneven light, making it possible to save energy and reduce costs, and it is a light box that fully satisfies the purpose of the present invention. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a light box according to an embodiment of the present invention, and FIG. 2 is a partial sectional view of FIG. 1. FIGS. 3 and 4 are explanatory diagrams illustrating the effects of the present invention. FIG. 4 is a sectional view of a conventional optical unevenness removing member. FIG. 5 is a partial sectional view of a light box according to another embodiment of the present invention. 1, 10... Light box, 2... Housing, 3
...Lighting surface, 4...Arryl milk half plate, 5,12...
... Transparent member, 6, 13 ... Reflective surface, 7, 9, 11
...Light unevenness removing member, 8, 8', 15...Fluorescent tube,
14...Polyester film.

Claims (1)

[Scope of utility model registration request] In a light box configured of at least an illuminating surface, a light unevenness removing member in which a transparent member is formed with a reflective surface having reflection distribution characteristics, and a fluorescent tube, a vertical plane from the illuminating surface passing through the tube axis of the fluorescent tube and the surface of the light unevenness removing member facing the fluorescent tube, the surface angle θ is greater than 90°.