JPS63231301A - Plate for illumination - Google Patents

Abstract

PURPOSE:To improve the uniformity of the panel light emission of an illumination plate by decreasing the thickness of a printing film and the occupying area rate per unit area gradually with a decrease in the luminance of the light from a light source from the part where the luminance of the light is high. CONSTITUTION:The light transmittable printing film 2 is formed nearly to a circular shape to face the halogen lamp 4 on the surface of a transparent plate 1. The printing film 2 is formed to the large thickness in the central part facing the lamps 4 to suppress the luminance of the light transmitting therethrough. The thickness of the printing film 2 is decreased successively from the central part toward the circumferential part to allow the transmission of the luminance of the light from the lamps 4 as it is. The occupying area rate per unit area of the printing films 2 with respect to the transparent plate 1 is increased in the central part of the printing film 2 and is decreased toward the circumferential part to change the transmittance. The panel light emission of the illuminating plate 6 is uniformized by such constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an illumination plate that allows light from a light source to pass through it, thereby emitting more or less uniform surface light.

<Prior Art> Conventionally, various structures have been known as illumination plates that produce this type of surface light emission. For example, a light emitting diode on a printed circuit board is surrounded by a reflective layer, a first confusion sheet is arranged facing the light emitting diode, and a first confusion sheet is placed on the opposite side of the first confusion sheet from the light emitting diode. There is a method in which a second confusion sheet is arranged at a predetermined interval, and the light from the light emitting diode is transmitted through the first and first confusion sheets, thereby making the light from the light emitting diode surface-emitting. (Sho 59-121374).

In addition, as another structure, a light emitting diode on a printed circuit board is surrounded by a reflective layer, a Fresnel lens is formed on a lighting board facing the light emitting diode, and a Fresnel lens is formed on the lighting board opposite to the light emitting diode. Place the confusion sheet,
There is a device that attempts to make the light of a light emitting diode surface-emitting by transmitting the light of the light emitting diode through a Fresnel lens and a confusion sheet (Japanese Patent Laid-Open No. 169787/1987).
issue).

However, in the former structure, the brightness at the center of the light emitting diode was too high compared to the brightness at the surrounding area, and uniform surface light emission over a wide range could not be obtained.

In addition, even with the latter structure, even if the light from the center of the light source is diffused with a Fresnel lens, the brightness of this light is higher than the brightness of the light around the light source, and uniform surface emission over a wide range can be obtained. It was something that didn't exist.

In order to solve these problems, the present inventors previously developed a lighting board in which the printed film was made thicker in the areas where the brightness of the light from the light source was high, and the thickness of the printed film was reduced in the areas where the brightness of the light was low. (Japanese Patent Application No. 154840/1982), and a lighting board in which the area occupied by the printed film is increased in areas where the brightness of the light from the light source is high, and the area occupied by the printed film is decreased in areas where the brightness of the light is low. Patent Application No. 154841/1983) was proposed.

<Problems to be Solved by the Invention> However, the above-mentioned lighting board is very effective when the light source type is a light emitting diode with a low amount of light, but it is not suitable for a large light source such as a halogen lamp. The light shielding properties are insufficient for a light source with a large amount of light, and it is difficult to express uniform surface light emission.

Therefore, the purpose of this invention is to solve the above problems,
An object of the present invention is to provide an illumination plate capable of emitting uniform surface light.

<Means for Solving the Problems> In order to achieve the above object, the present invention forms a light-transmissive printed film, and at the same time, the thickness and unit of the printed film are While increasing the area ratio per unit area, the thickness of the printed film and the area ratio per unit area are gradually decreased as the brightness of the light decreases from the high brightness area. That is, the present invention forms a light-transmissive printed film on either the front or back surface of a light-transmissive plate at a position corresponding to the light source, and adjusts the thickness of this printed film to reflect light from the light source. The thickness of the printed film is increased in areas with high brightness and the area ratio per unit area of this printed film is increased, while the thickness of the printed film is gradually decreased as the brightness of the light decreases from the high brightness areas. The structure was designed to reduce the occupied area ratio per unit area.

<Function> When the illumination plate with the above configuration is applied to a lighting device, the high-brightness light from the light source is transmitted through a thick printed film with poor light transmittance and a large area ratio. The brightness of the light is suppressed. On the other hand, low-luminance light is transmitted through a thin printed film with good light transmittance and a low occupation area ratio, so that the luminance of the light from the light source is maintained almost unchanged. Therefore, the brightness of the light passing through this illumination plate is made substantially uniform over a wide range.

<Example> Below, an example according to the present invention will be described in detail based on the drawings.

As shown in FIG. 1, the illumination plate 6 according to this embodiment is constructed by printing a light-transmissive printed film 2 on the surface of a transparent plate 1 made of polyethylene terephthalate (PET) or the like. do.

The transparent plate 1 may be a semi-transparent plate (with a thickness of, for example, 2 to 3 mm).
A glass plate as thick as VM or a thin transparent sheet may be used.

On the surface of the transparent plate 1, a light-transmitting printed film 2 is printed in a substantially circular shape, facing the halogen lamp 4.

As a printing method, a screen printing method that can form a thick film is suitable. The thickness of the printed film 2 is changed as follows. That is, as shown in FIGS. 2 and 3, the thickness of the central part of the printed rW 12 facing the halogen lamp 4 is increased to reduce the transmittance, thereby suppressing the brightness of the transmitted light, and the center of the printed film 2 The thickness of printing 1) and 2 is made smaller in order from the part to the surrounding part corresponding to the surrounding part of the halogen lamp 4 to increase the transmittance, so that the light from the halogen lamp 4 can be transmitted while maintaining almost the same brightness. do it like this. In addition, in this way, the printing film 2
At the same time as changing the thickness of the printed film 2, the area ratio per unit area of the printed film 2 relative to the transparent plate l is changed. That is, as shown in FIGS. 2 and 3, in the central part of the printed film 2 facing the halogen lamp 4, the occupied area ratio is increased to reduce the transmittance, suppressing the brightness of the transmitted light, and the printed film The area ratio occupied by the printed film 2 is gradually decreased from the central part of the halogen lamp 2 to the part corresponding to the peripheral part of the halogen lamp 4, and the transmittance is increased, so that the brightness of the light from the halogen lamp 4 is maintained almost as it is. and allow it to pass through.

Next, a case where this illumination plate 6 is incorporated into the illumination device 7 will be explained based on FIG. 1. In the lighting device 7, the lighting board 6 is arranged so that the thick part of the printing 1) 2 faces the light source of the halogen lamp 4 fixed on the reflection plate 3, and A diffusion sheet 5 is arranged on the opposite side.

The reflecting plate 3 is configured so that the light emitted from the halogen lamp 4 to the reflecting plate side and the light reflected by the printed film 2 are transmitted to the reflecting plate 3.
The reflected light is transmitted through the thin printed film 2 of the transparent plate 1 so that the brightness of the light transmitted through the peripheral portion of the printed film 2 corresponding to the peripheral portion of the halogen lamp 4 is increased. Make it.

The above-mentioned diffusion sheet 5 is for further diffusing the light transmitted through the illumination plate 6 to produce more uniform surface light emission.

According to the above configuration, in the portion of the transparent plate 1 facing the halogen lamp 4, that is, the portion through which high-brightness light is transmitted,
Since the thickness of the printed layer 2 is large and the area occupied by the printed layer 2 is large, the transmittance of light from the halogen lamp 4 is poor, and the brightness of the transmitted light is reduced. On the other hand, in the peripheral part of the printed film 2 corresponding to the peripheral part of the halogen lamp 4 on the transparent plate 1, that is, in the part through which low-luminance light passes, the thickness of the printed film 2 is small and its area ratio is small, so the halogen lamp 4 It has good transmittance to light, and the brightness of the light that is intended to pass through is maintained almost unchanged. Furthermore, since the reflected light reflected by the reflection tff13 passes through the peripheral portion of the printing Wi42 corresponding to the peripheral portion of the halogen lamp of the transparent plate 1, as a result, the halogen lamp of the transparent plate 1 is more effective than the conventional illumination plate. The brightness of the light transmitted through the peripheral portion of the printed film 2 corresponding to the peripheral portion is increased. Therefore, the brightness of the light transmitted through the transparent plate 1 is made almost uniform over the entire transparent plate due to changes in the thickness and occupied area ratio of the printed film 2, so that the center of the printed film 2 facing the light source Approximately uniform surface light emission can be performed over a wide range not only in the area but also in the peripheral area of the printed film 2 corresponding to the peripheral area of the light source. Moreover, if the lighting board 6 is used as the lighting device 7,
Since the printed film 2 formed on the transparent plate 1 is extremely thin compared to the thickness of the transparent plate itself, the gap between the transparent plate 1 and the diffusion sheet 5 can be made smaller than before, and the entire lighting device can be made smaller. Can be done. Therefore, this lighting bag W7 is
For example, it is suitable for surface emitting devices or liquid crystal backlights.

Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented in various other ways. For example, the printed film 2 may be formed on the back surface of the transparent plate 1.

<Effects of the Invention> According to the above configuration, the printing film is thick and occupies a large area ratio per unit area in the portion through which high-luminance light from the light source passes, resulting in poor light transmittance. , the brightness of the light decreases. On the other hand, in the area around the light source through which low-luminance light is transmitted, the printed film has a small thickness and occupies a small area ratio, so the light transmittance is good and the luminance of the light can be maintained at approximately the same level. Therefore, the brightness of the light transmitted through the transparent plate is made substantially uniform over the entire transparent plate due to changes in the printed film, so that substantially uniform surface light emission can be performed over a wide range even in the area corresponding to the light source. In addition, when incorporated into the above-mentioned illumination plate lighting device, the printed film formed on the transparent plate is extremely thin compared to the thickness of the transparent plate itself, so the gap between the transparent plate and the diffusion sheet can be made smaller than before, and the illumination The entire device can be downsized.

That is, for example, in a case where the Fresnel lens used to constitute the illumination plate, the Fresnel lens protrudes from the illumination plate, and only the protruding bone makes up the illumination plate. It was not possible to make the wall thinner, which hindered miniaturization of the entire lighting device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an illumination device using an illumination plate according to an embodiment of the present invention, FIG. 2 is a schematic enlarged plan view of a printed film,
FIG. 3 is a further enlarged cross-sectional view of a portion of the printing film shown in FIG. 2 from the center to the periphery. ■...Light transmitting plate, 2...Printed film, 3...Reflecting plate, 4...Light source, 5...Diffusion sheet, 6...Illumination board, 7...Lighting device . Patent applicant: Nissha Printing Co., Ltd.

Claims (3)

[Claims] (1) A light-transmissive printed film (2) is formed on either the front or back surface of the light-transparent plate (1) and at a position corresponding to the light source (4), and this printed film (2) The thickness of the printed film (2) is increased in the areas where the brightness of the light from the light source (4) is high, and the area ratio per unit area of this printed film (2) is increased. 1. A lighting board characterized in that the thickness of the printed film (2) is gradually reduced as the density decreases, and the area occupied per unit area is reduced. (2) The illumination plate according to claim 1, wherein the light-transmitting plate (1) is a transparent plate. (3) The illumination plate according to claim 1, wherein the light-transmitting plate (1) is a semi-transparent plate.