JPH0425776Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lighting device, and particularly to a lighting device that is thin and has good uniformity of irradiated light.

[Conventional technology]

A lighting device illuminates paintings and text examples from behind,
When attempting to observe them transparently, planar homogeneity of the illumination device is highly required.

In order to homogenize the light irradiated by a lighting device, it is possible to increase the number of light-emitting lamps or expand the light-emitting area of the lamps themselves, but this increases the size of the device and increases costs.

For this reason, a configuration has been proposed that uses a relatively small number of small lamps to ensure uniformity of the lighting device.

FIG. 6 is a diagram for explaining a conventional example of a lighting device, in which FIG. 6(a) is a cross-sectional view, and FIG. 6(b) is a diagram showing brightness characteristics corresponding to the cross-section.

In Figure 6, 3 is a lamp, 4 is a reflective surface, 6
is a diffuser plate.

A highly scattering reflective surface 4 is arranged behind the lamp 3, and a highly diffusive semitransparent diffuser plate 5 is arranged on the light output side to homogenize the light emitted from the lamp 3. was.

[Problem that the invention attempts to solve]

However, when the diffuser plate 5 is used to improve homogeneity, the transmittance decreases, and as shown in FIG. 6(b), there is a problem that sufficient brightness cannot be obtained in the peripheral area of the lighting device. It was hot.

For this reason, if an attempt is made to improve homogeneity by arranging the lamp 3 at a distance from the diffuser plate 5, the entire device becomes large, and it becomes difficult to downsize the device, particularly in the thickness direction.

An object of the present invention is to solve the above-mentioned problems and provide an illumination device that is suitable for a thin device and can obtain irradiated light with high planar homogeneity.

[Means for solving problems]

In developing a thin lighting device that uses a relatively small number of light sources per unit light emitting area, the inventor of the present invention discovered that the brightness directly above the light source is high, and the brightness decreases as you move away from the light source. We focused on the fact that uniformity of brightness cannot be achieved, and came up with the present invention.

That is, the lighting device according to the present invention includes a light source;
It is composed of a lenticular lens sheet and a reflective layer.

As the light source, one or more point light sources or rod-shaped light sources can be suitably used.

A lenticular lens sheet is a lens sheet that is provided on the light output side of a light source and has convex lenticular lenses formed on both sides.

In this case, in the lenticular lens sheet, the optical axes of the lenticular lens on the light output side and the lenticular lens on the light source side are substantially coincident, and the optical axes of the lenticular lens on the light source side are inward from the focal position of the lenticular lens on the light source side. The surface of the lenticular lens is on the light output side.

The reason for this is that if the light output position matches the focal position of the lenticular lens, all the incident light will be focused on the reflective layer and there will be no direct transmitted light. Then, the light that perpendicularly passes through the lens sheet hits the reflective layer, but the side light is refracted by the lens surfaces on both sides of the reflective layer and becomes appropriately scattered light. Conversely, when the light output position is outside the focal point, the light on the side that does not hit the reflective layer is refracted by the lens, and the direction of the light is corrected to be perpendicular to the lens sheet, resulting in less scattered light. .

The reflective layer is provided on a part of each lenticular lens surface on the light exit side of the lenticular lens sheet. This reflective layer is provided at and in the vicinity of the light output portion of the lenticular lens on the light output side when parallel light from a vertical direction is incident on the lenticular lens on the light source side.

Furthermore, in order to improve homogenization, the lenticular lens sheet may be used in combination with a light-concentrating linear Fresnel lens between the light source and whose optical axis is at a position opposite to the light source position;
It can be used in combination with an isotropic light diffuser placed on the outside.

[Effect]

Therefore, according to the present invention, since a reflective layer is provided on a part of the light exit surface side of the biconvex lenticular lens,
Directly above the light source, most of the light is reflected by the reflective layer. On the other hand, at a distance from the light source, less light is reflected and is refracted and passes in the front direction. Therefore, it is possible to obtain irradiated light with good homogeneity as a whole.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings and the like.

FIG. 1 is a diagram for explaining the first embodiment of the lighting device according to the present invention, in which (a) is a cross-sectional view, and (b) is a diagram showing the brightness characteristics corresponding to the cross-section. FIG. 2(a) is a diagram showing the optical path far from the lamp of the device of the first embodiment, and FIG. 2(b) is a diagram showing the optical path far from the lamp of the first embodiment device.
FIG. 3 is a diagram showing the optical path directly above the lamp of the embodiment device.

In FIG. 1, 1 is a biconvex lenticular lens sheet, and 2 is a reflective layer. Note that the same reference numerals are given to parts that perform the same functions as those of the conventional example described above.

The present invention is applied to a planar illumination device, in which one side is primarily a light emitting surface.

On the inner surface of the lamp house other than the light emitting surface,
A reflective surface 4 is formed. This reflective surface 4 is intended to increase the luminance of light emitted from the light emitting surface side, and may be, for example, a curved mirror surface or a white painted surface with high reflectance to form a diffusive reflective surface. ing.

A transparent or semi-transparent biconvex lenticular lens sheet 1 is arranged on the light exit surface side.

The lenticular lenses 11 and 12 are shaped so that their optical axes substantially coincide with each other, and the surface of the lenticular lens 11 on the light output side is located inside the focal point of the lenticular lens 12 on the lamp side. It is arranged as it is.

A reflective layer 2 that functions as a filter is formed on a part of the top of the lenticular lens 11 on the side far from the lamp 3 of the biconvex lenticular lens sheet 1 . This reflective layer 2 is formed on the lenticular lens 11 on the light output side when parallel light enters the lenticular lens 12 on the light source side from the vertical direction.
It is provided at the light emitting part and its vicinity. This reflective layer 2 is for reducing the luminance of light directly above the lamp 3, and for example, a white reflective layer made of an opaque material can be suitably used.

Therefore, as shown in FIG. 2(b), most of the light incident on the lenticular lens directly above the lamp 3 is reflected by the reflective layer 2 on the top of the lenticular lens 11 on the light output side. Since the light returns to the lamp 3 side, which is the light source, the brightness decreases.

On the other hand, as shown in Fig. 2(a), the light incident at a position away from the lamp 2 enters the lenticular lens 12 on the light input side from an oblique direction, and most of the light enters the lenticular lens 12 on the light output side. Since it does not pass through the top of the lenticular lens 12, it passes through without being reflected, and
The light is refracted in the front direction of the illumination device by the lenticular lens 11 on the light output side.

Therefore, since the luminance characteristics are as shown in FIG. 1(b), it is possible to obtain irradiated light with good homogeneity as a whole.

FIG. 3 is a diagram showing a second embodiment of the lighting device according to the present invention.

The second embodiment is an example in which a condensing lens is further used in combination.

A light-condensing linear Fresnel lens sheet 5 is placed between the fluorescent tube 3 and the lenticular lens sheet 1, and the optical axis of this linear Fresnel lens sheet 5 is aligned with the position of the fluorescent lamp 3. .

In this way, even better homogeneity can be achieved.

FIG. 4 is a diagram showing a third embodiment of the lighting device according to the present invention.

In the second embodiment, one fluorescent lamp 3 is shown as an example, but the number of fluorescent lamps 3 does not necessarily have to be one, and as in the third embodiment, a plurality of lamps 31, 31, ... can be placed.

In this case, light-concentrating linear Fresnel lens sheets 5, 5, . . . may also be provided as a plurality of light-condensing sheets.

FIG. 5 is a diagram showing a fourth embodiment of the lighting device according to the present invention.

In this embodiment, an isotropic light diffusing plate 6 is further arranged on the outside of the lenticular lens sheet 1.

In this way, the generation of a linear pattern in the lenticular lens sheet 1 for homogenization can be effectively prevented.

Note that a similar effect can be obtained by mixing a light-diffusing substance into the lenticular lens sheet 1.

[Effect of idea]

As explained in detail above, according to the present invention,
Since a reflective layer is provided on a part of the light exit surface of the biconvex lenticular lens, most of the light is reflected by the reflective layer directly above the light source, and less light is reflected away from the light source. Since the light is refracted and passes in the front direction, it is possible to obtain illumination light with good homogeneity as a whole.

Therefore, it is possible to realize a lighting device that is thin and has good uniformity of irradiated light.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the first embodiment of the lighting device according to the present invention, in which (a) is a cross-sectional view, and (b) is a diagram showing the brightness characteristics corresponding to the cross-section. FIG. 2(a) is a diagram showing the optical path far from the lamp of the device of the first embodiment, and FIG. 2(b) is a diagram showing the optical path far from the lamp of the first embodiment device.
FIG. 3 is a diagram showing the optical path directly above the lamp of the embodiment device. FIG. 3 is a diagram showing a second embodiment of the lighting device according to the present invention. FIG. 4 is a diagram showing a third embodiment of the lighting device according to the present invention. Fifth
The figure shows a fourth embodiment of the lighting device according to the present invention. Fig. 6 is a diagram for explaining a conventional example of a lighting device, in which Fig. 6 (a) is a cross-sectional view;
(b) is a diagram showing the origin characteristic corresponding to the cross section. 1... Double convex lenticular lens sheet, 2...
...Reflection layer, 3...Lamp, 4...Reflection surface, 5...
Linear Fresnel lens, 6...Diffusion plate.

Claims (1)

[Claims for Utility Model Registration] (1) A light source, a lenticular lens sheet provided on the light output side of the light source and having convex lenticular lenses formed on both sides, and a lenticular lens sheet on the light output side of the lenticular lens sheet. A lighting device comprising a reflective layer provided on a part of each lenticular lens surface. (2) In the lenticular lens sheet, the optical axes of the lenticular lens on the light output side and the lenticular lens on the light source side are substantially aligned, and the light is emitted inward from the focal position of the lenticular lens on the light source side. The lighting device according to claim 1, characterized in that there is a surface of a lenticular lens on the side. (3) The reflective layer is provided at and in the vicinity of a light output portion of the light output side lenticular lens when parallel light from a vertical direction is incident on the light source side lenticular lens. A lighting device according to claim 1 of the utility model registration claim. (4) The lighting device according to claim 1, wherein the light source is one or more point light sources or rod-shaped light sources. (5) A request for registration of a utility model characterized in that the lenticular lens sheet is used in combination with a light-condensing linear Fresnel lens between the light source and whose optical axis is at a position opposite to the light source position. The lighting device according to item 1. (6) The lighting device according to claim 1, wherein the lenticular lens sheet is used in combination with an isotropic light diffusing plate disposed on the outside.