JPH05323312A - Back light for liquid crystal display - Google Patents

Abstract

PURPOSE:To obtain a back light which has no deformation and no decrease in brightness uniformity and has no breakage of a fluorescent tube even when applied with mechanical stress from an outside by embedding the fluorescent tube in a transparent resin. CONSTITUTION:Plural fluorescent tubes 5 are arranged successively in a housing 4 equipped with a reflecting plate molded out of polycarbonate, etc., so that the inside of a desired display screen is uniformly lighted. For example, seven fluorescent lamps 7 having a specific tube diameter and specific length are juxtaposed at specific pitches as the fluorescent tubes 5 so as to illuminate uniformly the display screen of, e.g. 9-inch size. A lighting curtain 2 is installed at a specific interval above the fluorescent lamps. Further, a diffusion plate 1 installed over the entire back light projection surface. Acrylic resin incorporating SiO2 particles and having specific plate thickness can be used for the diffusion plate 1. Further, the transparent resin 3 is filled in a housing 4 below the lighting curtain 2 so that the housing 4 is sealed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display backlight, and more particularly to a direct type liquid crystal display backlight constructed by arranging a plurality of fluorescent tubes on the back surface of a display screen.

[0002]

2. Description of the Related Art Liquid crystal displays are widely used as information terminals such as personal computers and word processors. Recently, a liquid crystal backlight (hereinafter referred to as "backlight") is usually installed on the back surface of a transmissive liquid crystal display for obtaining a bright display screen for display. Particularly in the case of color display, since a color filter is used for the liquid crystal panel, the light transmittance is lowered, and therefore it is essential to use a backlight.

On the other hand, in recent years, with the further demand for lighter, thinner, shorter, and smaller liquid crystal displays, there is a strong demand for thinner, more compact, bright and uniform illumination as a backlight.

The structure of the backlight is roughly classified into 2
Classified into types. One of them is a so-called side light method in which fluorescent tubes are arranged on the side surface to illuminate, and the other is a so-called direct type method in which a plurality of fluorescent tubes are arranged and illuminated on the back surface of the display screen. The sidelight method is suitable for liquid crystal panels with relatively high light transmittance such as monochrome display because it is difficult to obtain bright brightness, but for the color liquid crystal panel with low light transmittance. The direct type is suitable.

FIG. 2 is a sectional view showing the outline of the basic construction of a conventional direct type backlight.

As shown in FIG. 2, a plurality of fluorescent tubes 5 are juxtaposed in a housing 4 having a reflecting plate function. Further, in order to make the brightness distribution spatially uniform, a lighting curtain 2 that positively suppresses brightness is installed in the opening of the housing 4 immediately above the fluorescent tube, and further, a light diffusion plate 1 is installed on the entire backlight emission surface. ing.

[0007]

When a thin backlight is constructed in the above-mentioned backlight structure, the distance between the fluorescent tube and the housing provided with the reflection plate and the diffuser plate or the lighting curtain becomes narrower and shorter. . Generally, the housing is formed of a plastic molded product in order to reduce the weight. Therefore, the direct type backlight has a problem that the housing is deformed by mechanical stress from the outside, the brightness uniformity is deteriorated, and the fluorescent tube in the housing is broken.

It is an object of the present invention to provide a backlight which does not deform even when it receives mechanical stress from the outside, does not deteriorate the brightness uniformity and does not damage the fluorescent tube.

[0009]

According to the present invention, a plurality of fluorescent tubes arranged side by side, a housing provided with a reflector for accommodating the plurality of fluorescent tubes, and a lighting installed in an opening of the housing. In a backlight for a liquid crystal display having a curtain and a diffusion plate arranged on the entire emission surface so as to face the lighting curtain, the plurality of fluorescent tubes are embedded in a transparent resin.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a sectional view showing the outline of the configuration of the first embodiment of the present invention.

In the first embodiment, as shown in FIG. 1, a fluorescent tube 5 is provided in a housing 4 provided with a reflecting plate formed by molding of polycarbonate or the like so that the desired display screen is uniformly illuminated. Put multiple pieces side by side. For example, 9
In order to uniformly illuminate an inch size display screen, eight fluorescent lamps having a tube diameter of 4.1 mm and a length of 225 mm are juxtaposed at a 16 mm pitch as the fluorescent tubes 5. At this time, housing 4
Thickness of 1.5mm, distance between fluorescent lamp and housing 4 is 1
It is about mm.

Further, the lighting curtain 2 is installed at a position spaced apart by about 1 mm on the fluorescent lamp.

Further, the diffusion plate 1 is provided on the entire surface of the backlight emission surface.
Set up. As the diffusion plate 1, an acrylic resin containing SiO ₂ fine particles and having a plate thickness of 1.5 mm can be used.

Further, the space of the housing 4 under the lighting curtain 2 is filled with a transparent resin 3 so as to seal the inside of the housing 4. As an example, a silicone resin can be used. Since it is used in a backlight, it has only to have a high transmittance for visible light and a heat resistance of about 100 ° C. or higher.

A liquid crystal display was constructed by combining the backlight constructed as above and the liquid crystal panel 6, and it was investigated how much weight was applied from the back surface of the backlight to break the fluorescent tube. For reference, a liquid crystal display using a conventional backlight in which the transparent resin 3 is not included in the backlight was also investigated.

As a result, the fluorescent lamp was broken at about (10 kg weight) / (diameter 80 mm) using the conventional backlight, whereas the liquid crystal display using the backlight of this embodiment was (25 kg weight). ) / (Diameter 80 mm), cracking of the fluorescent lamp occurred, and it was confirmed that the static load resistance of the backlight of this example was improved by about 2.5 times.

The second embodiment is an example of a backlight having a structure in which the space below the housing is filled with transparent resin so that the emission surface of the upper part of the fluorescent tube is exposed. As a result of performing the same evaluation as above, almost the same effect was obtained.

Further, in the second embodiment, since the emission surface is exposed, there is an effect of increasing the brightness of the backlight.

[0020]

As described above, the present invention has a structure in which the fluorescent tube is embedded in the transparent resin, and thus has a higher reliability than that of the conventional backlight, particularly, mechanical stress resistance. The effect is that an excellent backlight can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an outline of the configuration of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an outline of a basic configuration of a conventional direct type backlight.

[Explanation of symbols]

 1 Diffusion plate 2 Lighting curtain 3 Transparent resin 4 Housing 5 Fluorescent tube 6 Liquid crystal panel

Claims (1)

[Claims] 1. A housing provided with a plurality of fluorescent tubes juxtaposed to each other, a reflecting plate accommodating the plurality of fluorescent tubes, a lighting curtain installed in an opening of the housing, and facing the lighting curtain. In the backlight for a liquid crystal display having a diffusion plate arranged over the entire emission surface as described above, the plurality of fluorescent tubes are embedded in a transparent resin.