JP3614966B2 - Backlight for LCD - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal backlight used in a transmissive liquid crystal display, and more particularly to an edge light type liquid crystal display backlight in which a light source is installed on an end face of a light guide.
[0002]
[Prior art]
Conventionally, color display methods of a liquid crystal display include a color filter type in which a color filter is built in a liquid crystal cell and a color light source type in which a color light source is used as a backlight.
[0003]
Of these, the color light source type uses a plurality of light sources, so the power consumption is slightly increased. However, the high resolution display is possible and the manufacturing cost is low, so a large screen such as a stationary television is used. Suitable for display.
[0004]
In addition, the backlight for the edge-light type liquid crystal display in which the light source is installed on one end surface of the light guide body is relatively excellent in luminance uniformity, and moreover than the direct type with the light source mounted on the back of the light guide plate. Therefore, it contributes to the thinning of high-quality liquid crystal displays.
[0005]
Therefore, as shown in FIG. 2 (a), light sources 53, 54, and 55 made of fluorescent lamps of red, green, and blue (hereinafter referred to as R, G, and B) colors are installed on the end surface 60 of the light guide plate 52. The color light source type backlight is generalized.
[0006]
[Problems to be solved by the invention]
However, in this method, since the three light sources 53, 54, and 55 of R, G, and B are arranged side by side in the thickness direction of the light guide plate 52, the light guide plate 52 becomes thick and the liquid crystal display is thin. It was preventing the conversion.
[0007]
Therefore, as shown in FIG. 2B, when the point light sources 63, 64, 65 of the three colors R, G, B are arranged on the end face 70 of the light guide plate 62, the line light source shown in FIG. ) Has a problem in that it is difficult to maintain the uniformity of luminance.
[0008]
The present invention solves the above-mentioned problems of a conventional backlight for a liquid crystal display and intends to arrange a plurality of light sources so that the light guide does not become thick.
[0009]
[Means for Solving the Problems]
The present invention, in order to achieve the above object, a light guide, are arranged in parallel along a surface of the light guide on an end face of the light guide, individually lighted, R, G, and B colors and three light sources for emitting respectively, said three light sources, a gas emission lamp light source except for the at least one of the outermost end is made of a transparent tube filled with gas that emits light of the color corresponding Provided is a backlight for a liquid crystal display.
[0010]
If a plurality of light sources are made of cold cathode tubes that emit light of R, G, and B colors, for example, the cold cathode tubes of two colors R and B can be made transparent when extinguished. If arranged at the outer end, the light from each cold cathode tube can be transmitted without reaching the light guide and reach the light guide. Therefore, since three cold cathode tubes can be arranged in the same direction as the surface of the light guide, the thickness of the light guide need only be the thickness of one cold cathode tube, and the backlight portion is thinly formed. can do.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG.
[0012]
FIG. 1 shows an example of an embodiment of the present invention. Like a conventional liquid crystal display backlight, the light guide 2 is formed of, for example, a transparent acrylic plate, the surface is a diffusion plate 3, and the back surface From side to side, it is covered with a reflector 4.
[0013]
On one end face 21 of the light guide 2, for example, cold cathode tubes 11, 12, and 13 (hereinafter referred to as R tube, G tube, and B tube) that emit light in R, G, and B colors, respectively. They are arranged side by side along the surface of the light guide 2.
[0014]
These cold-cathode tubes include, for example, an R tube 11 in which neon is sealed in a transparent glass tube, and a B tube 13 in which argon and mercury are also sealed in a transparent glass tube. The tube may be a gas light emitting lamp in which a gas that emits light of the color is enclosed in a transparent glass tube. The G tube 12 is a fluorescent lamp in which a phosphor that emits green color, such as zinc sulfide, is applied to the inner wall of the tube.
[0015]
In this way, the R tube 11 and the B tube 13 are colorless and transparent when extinguished. Therefore, if the G tube 12 is disposed at the outermost end farthest from the light guide 2, the R tube 11, the G tube 12, B When the tubes 13 are individually lit, the colored light reaches the light guide 2 without the influence of other cold cathode tubes. Therefore, three types of cold-cathode tubes R tube 11, G tube 12 and B tube 13 can be arranged on the end face of the light guide 2 in the same direction as the surface of the light guide 2.
[0016]
According to the backlight for a liquid crystal display having the above configuration, the R tube 11, the G tube 12, and the B tube 13 are arranged side by side in the same direction as the surface of the light guide 2. One cold cathode tube may be sufficient. Accordingly, the thickness of the light guide 1 can be reduced as compared with the case where the R tube 11, the G tube 12, and the B tube 13 are arranged so as to overlap each other in the thickness direction of the light guide 1.
[0017]
Furthermore, in order to increase the brightness of the display surface, even when it is desired to install a plurality of R, G, and B tubes, if a G tube that does not become colorless and transparent when turned off is disposed at the outer end, the same as in the case of FIG. Can be arranged in a row in the surface direction.
[0018]
The raw materials for the three-color tube are not limited to those described above, and at least two types may be cold-cathode tubes that emit light of the corresponding color in a colorless and transparent tube. If possible, the arrangement order may be arbitrary. However, if the color light emitted from the outer light source passes through the inner transparent tube and the light amount is slightly reduced, the intensity of each light source can be increased, for example, by making the light source arranged on the outer side a larger light amount. It is necessary to adjust accordingly.
[0019]
On the other hand, in a color filter type liquid crystal display, the present invention can be similarly applied to a case where a plurality of light sources are to be arranged for the purpose of, for example, increasing the luminance or for the purpose of standby.
[0020]
【The invention's effect】
According to the present invention, since a plurality of light sources are arranged along the surface of the light guide, even when it is desired to arrange a plurality of light sources to provide light sources of a plurality of colors such as RGB, a thin back of the light guide is provided. It can be a light.
[0021]
And since what was conventionally arrange | positioned in the thickness direction of a light guide is only arrange | positioned in a surface direction, special processing and a troublesome effort are not taken, and cost does not become high.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a schematic view showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Backlight for liquid crystal display 2 Light guide 11, 12, 13 Light source

Claims (4)

A light guide;
Wherein arranged on the end face of the light guide in parallel along the surface of the light guide, individually lighted, with R, G, and three light sources which respectively emit colors of B,
The three light sources are gas light-emitting lamps comprising a transparent tube filled with a gas that emits light of the color corresponding to the light source except at least one of the outermost ends. Light. 2. The backlight for a liquid crystal display according to claim 1, wherein the light source that emits the R color is the gas light emitting lamp in which neon that emits the R color is enclosed. 3. 2. The backlight for a liquid crystal display according to claim 1, wherein the light source at the outermost end is a fluorescent lamp in which a fluorescent material that emits light of the corresponding color is applied to the inner wall of the tube.   The backlight for a liquid crystal display according to claim 1, wherein the plurality of light sources are cold cathode tubes.

Images