JPH0451368Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an illumination device that can provide a surface light source with particularly uniform brightness using a surface light source.

[Conventional technology]

A conventional surface light source lighting device has a linear light source 2 such as one or more fluorescent tubes arranged on a flat or curved reflecting plate 1 as shown in FIG. A diffuser plate 3 is placed on the opposite side of the reflector plate.

Among such lighting devices, for example, a lighting device using a single linear light source has a distribution of brightness on the diffuser plate as shown in Figure 5, with the brightness being highest in the center near the light source and spreading to the periphery. The distribution gradually decreases as the distance increases, and the distribution is not uniform over the entire diffuser plate. In particular, when the light source 2 and the diffuser plate 3 are placed close to each other in order to make the lighting device thinner, the brightness of the area directly above the light source becomes particularly high due to the light emitted upward from the light source and directly reaching the diffuser plate.

For this reason, many attempts have been made to reduce the light directed upward from the light source so that the brightness on the diffuser plate becomes uniform.

One of the conventional examples based on this idea is the conventional example described in Utility Model Application Publication No. 61-90106, in which a light source is installed in the upper part of the fluorescent tube (the part near the diffuser plate), which is a linear light source. A device in which a large number of linear light shielding portions 10 of a constant width are provided intermittently as shown in FIG. 4 is known. In this conventional example, an attempt is made to obtain a lighting device with a relatively uniform luminance distribution by appropriately selecting the width of each light shielding part, the number thereof, the interval between light shielding parts, and the like. However, in this conventional example, the luminance distribution generally becomes as shown in FIG. In other words, in this conventional example, part of the light directed upward from the light source is blocked by the light shielding part, reducing the amount of light that reaches the center of the diffuser plate, which is directly above the linear light source, and the brightness of this center decreases. However, the brightness of the adjacent portions on both sides is high, resulting in a brightness distribution with two peaks, which is undesirable.

Furthermore, as another conventional example, the one described in Japanese Patent Laid-Open No. 133008/1983 is also known. In this method, a light amount adjustment plate 11 is arranged between the diffuser plate and the light source, etc., with dot-shaped light shielding parts 12 such as black dots, as shown in Fig. 6, arranged in an appropriate density distribution. The aim is to obtain a relatively uniform brightness distribution by suppressing the light that reaches high brightness areas. In this conventional example, the brightness distribution on the diffuser plate is uniform to some extent, but it is difficult to maintain the mutual positioning accuracy of the light source and the light amount adjustment plate when assembling the device, and when multiple light sources are used, However, there was a problem in that it was difficult to deal with variations in luminance on the tube surface.

To solve this problem, a linear light source is placed above the reflector, and a diffuser plate is placed on the opposite side of the linear light source to control the amount of emitted light on the top of the light source tube. In a lighting device equipped with a light amount control means, a light-reducing sheet is provided at the bottom of the light source tube to form a region with low reflectance, thereby suppressing the brightness not only in the central region on the diffuser plate but also in the adjacent regions. A diffuser was developed that made the brightness uniform across all parts of the diffuser. Of the light reflected directly below or around the light source on the reflector plate, the light heading towards the center of the diffuser plate is blocked by the fluorescent tube of the light source, but the light reflected diagonally is at the center of the diffuser plate. This was done by focusing on the fact that the brightness of this part becomes relatively high when it reaches the part adjacent to the area, and by reducing this reflected light, the two peaks shown in Figure 8 can be suppressed and the brightness can be increased. The distribution is uniform. That is, the brightness is made uniform over the entire diffuser plate by reducing the reflected light directly below the light source tube that reaches the portion adjacent to the central portion of the diffuser plate.

However, the fluorescent tubes used in the above-mentioned lighting devices are generally provided with a trigger coat, and when installing the fluorescent tube, this trigger coat is directly below, that is, the low reflectance part on the reflector plate mentioned above. They must be positioned so that they face each other. In this case, if this positioning is out of order, it will cause uneven brightness.

[Problem that the invention attempts to solve]

The problem to be solved by the present invention is to provide a lighting device having the above-mentioned configuration that does not require any circumferential positioning of the fluorescent tube, which is a linear light source, when installing the fluorescent tube. It is in.

[Means for solving problems]

The lighting device of the present invention has a fluorescent tube placed above the reflector, and a diffuser plate placed on the opposite side of the fluorescent tube to the reflector. It is characterized by forming a low reflectance part using a material, and since the part using the conductive material is directly under and close to the fluorescent tube, it can also serve as a trigger coat. It is. Therefore, the fluorescent tube used in the lighting device of the present invention does not need to be provided with a trigger coat, so there is no need for positioning in the circumferential direction when installing it in the lighting device, and it is sufficient to simply attach it to the fluorescent tube holder. .

〔Example〕

Next, an embodiment of the lighting device of the present invention will be described based on the drawings. FIG. 1 is a cross-sectional view of one embodiment of the present invention, in which 1 is a curved reflector, 2 is a linear light source such as a fluorescent tube placed above the center of the reflector, and 3 is a cross-sectional view of an embodiment of the present invention.
4 is a diffuser plate placed above the light source 2 facing the reflector 1, and 4 is a diffuser plate placed above the fluorescent tube 2, which is a linear light source, with an intermittent pattern placed directly on the top of the fluorescent tube 2, as shown in Figure 2, using a light shielding material. It is formed on the fluorescent tube or by pasting a transparent sheet with a black light-shielding pattern on the fluorescent tube. Reference numeral 5 denotes a low-reflectance sheet member made of a conductive light-absorbing substance or the like, and is provided near the reflection plate 1 directly below the fluorescent tubes 2 .

In this embodiment, a portion of the light, such as the light ray l ₁ , which travels directly upward from the linear light source 2 is blocked by the light-shielding pattern 4, so that the amount of light is reduced.
Furthermore, the light ray _l2 , which is reflected near directly below the linear light source 2 and heads obliquely upward, is reflected on the member 5 having a low reflectance, so that the amount of light decreases. In this way, the light that is directly directed upward from the linear light source 2 and reaches the central part 3a of the diffuser plate 3, or the linear light source 2
The luminance distribution on the diffuser plate 3 is relatively uniform because the amount of light that is emitted from the diffuser plate 3 is reduced, goes downward, is reflected obliquely upward, and reaches the portion 3b adjacent to the center portion 3a on the diffuser plate 3. becomes. Here, the low reflectance member 5 provided on the reflector 1 is made of a conductive material, and since the fluorescent tube 2 is placed close to or in contact with this member 5, it also serves as a trigger coat for the fluorescent tube. obtain. Therefore, it is not necessary to provide a trigger coat to the fluorescent tube used in this embodiment, and there is no need to perform position adjustment when attaching the fluorescent tube to the lighting device.

The material for the low reflectance member used in this embodiment is, for example, printable ink containing carbon, aluminum, copper, or the like. In addition, even when forming a light amount control mask on a part of the fluorescent tube to reduce the amount of light emitted directly above the tube to equalize the brightness on the diffuser plate surface, the light amount control mask does not have a trigger coat. There is no positional restriction, and the printing work of the light amount control mask becomes easy.

[Effect of idea]

In the lighting device of the present invention, by providing a conductive low-reflectance member on the reflecting plate constituting the lighting device, it can also be used as a trigger coat for a fluorescent tube. Since there is no need to provide a , there is no need for positioning when installing the lighting device, and the installation is easy.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a perspective view showing a light-shielding pattern and members with low reflectance used in the same embodiment, and Fig. 3 is a sectional view of a conventional lighting device. FIG. 4 is a perspective view of a fluorescent tube provided with a conventional light-shielding pattern, and FIGS. 5 and 6 are graphs showing the luminance distribution on a diffuser plate of a conventional illumination device. 1... Reflector plate, 2... Fluorescent tube, 3... Diffusion plate,
4... Light-shielding pattern, 5... Conductive light-absorbing sheet.

Claims (1)

[Scope of utility model registration request] In a lighting device in which a fluorescent tube serving as a linear light source is placed above a reflecting plate and a diffuser plate is placed on the opposite side of the linear light source from the reflecting plate, a conductive material is placed on the reflecting plate directly below the light source tube. A lighting device characterized in that a portion with low reflectance is formed using