JPH04269716A - Light source device - Google Patents

Abstract

PURPOSE:To attain thickness reduction and high-brightness output at the same time by arranging a fluorescent lamp in a light guide plate. CONSTITUTION:A U-shaped groove 11a is formed in the light guide plate 11 formed of a transparent acryl plate so that the U-shaped fluorescent lamp 10 is fitted therein; and the fluorescent lamp 10 is arranged in the groove 11a. A diffusion coat processing layer 11b is formed at the back surface part of the light guide plate 11 by vapor deposition, silk printing, etc., so as to reflect light. A lighting curtain 12 is formed by forming a U-shaped vapor-deposited part 12a of a transparent sheet along the fluorescent lamp 10 and the direct light from the fluorescent lamp 10 is dispersed to some extent. The light outputted by the fluorescent lamp 10 is therefore diffused by the light guide plate 11 in the surface direction, uniformed by the lighting curtain 12 and diffusion sheet for transmission, and outputted by face lighting.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device suitable for, for example, a backlight of a liquid crystal display device.

0002

2. Description of the Related Art For a light source device used as a backlight for a liquid crystal display, for example, it is preferable that the device itself be a thin surface emitting source that can provide a certain level of high brightness. As conventional backlights for liquid crystals, the direct lighting type shown in FIG. 5 and the light guide plate type shown in FIG. 6 are mainly used.

The direct illumination type backlight shown in FIG. 5 has a curved reflector 2 on the back side of a fluorescent lamp 1, and a diffuser plate 3 on the front side that diffuses the light and makes it uniform as surface emission. The output surface is the basic structure.

On the other hand, a light guide plate type backlight is shown in FIG.
As shown in a), fluorescent lamps 1 are arranged on both sides of a light guide plate 4 made of a transparent acrylic plate which has been subjected to a diffusion coating process by vapor deposition, silk printing, etc., and as can be seen from FIG. The peripheral surface of the light guide plate 4 and the back surface of the light guide plate 4 are covered with a reflector plate 5, and a diffuser plate 3 is disposed on the front surface of the light guide plate 4 to diffuse the light and make it uniform as surface light emission.

[0005]

[Problems to be Solved by the Invention] In such conventional backlights, the direct illumination method has the advantage of obtaining considerably high brightness output, and the light guide plate method has the advantage that it can produce a light output of approximately the same diameter as the fluorescent lamp 1. However, neither method can satisfy these advantages at the same time.

In other words, in the case of the direct lighting method, the thickness of the entire backlight is required to be at least twice the diameter of the fluorescent lamp 1, and there is a problem that it cannot be used as a backlight for a liquid crystal display device that requires thinning. In the light guide plate type backlight, there is a limit to high brightness output due to poor conversion efficiency in the light guide plate 4, and there is a problem that it cannot be used for, for example, a high-definition liquid crystal screen or a color liquid crystal screen.

[0007]

[Means for Solving the Problems] In view of these problems, it is an object of the present invention to realize a light source device that achieves thinness and high brightness output at the same time. The light source device is configured so that the fluorescent lamp is located inside the.

[0008]

[Operation] By adopting the light guide plate method, the light source device itself can be made thinner, and by arranging the fluorescent lamp inside the light guide plate, it is possible to use direct light, and the light output is achieved by the conversion efficiency of the light guide plate. Luminance limitations can be resolved.

[0009]

[Embodiment] FIG. 1(a) is an exploded perspective view showing the structure of one embodiment of the light source device of the present invention, in which 10 is a U-shaped fluorescent lamp, and 11 is a light guide plate formed from a transparent acrylic plate. It is. A U-shaped groove 10a is provided in the light guide plate 11 so that the fluorescent lamp 10 is fitted therein, and the fluorescent lamp 10 is disposed within the groove 10a as shown. Further, on the back surface of the light guide plate 10, a diffusion coating layer 10b is formed by vapor deposition, silk printing, etc. in order to reflect light, as shown in the configuration diagram of FIG. 1(b).

Reference numeral 12 denotes a lighting curtain for canceling and diffusing the extreme brightness of direct light output from the fluorescent lamp 10, in which a U-shaped vapor deposition part is formed along the fluorescent lamp 10 on a transparent sheet. 12a disperses direct light from the fluorescent lamp 10 to some extent. Further, 13 is a diffusion sheet for transmission, and the light output from the fluorescent lamp 10 is diffused to some extent in the surface direction by the light guide plate 11, and the lighting curtain 1
2 and the diffusion sheet 13, the light is made uniform in the plane direction, and the light is output as surface emission. Although not shown, reflective plates are arranged on the back and side surfaces of the light guide plate 11 as necessary.

By adopting the light guide plate method, the light source device of this embodiment can be made thin to a size approximately equivalent to the diameter of the fluorescent lamp 10, and the fluorescent lamp 10 is located inside the light guide plate 11. By doing so, not only the light component that is converted in the planar direction by the light guide plate 11 and output, but also the direct light component that does not go through the light guide plate 11 is used as the actual output light, making it possible to output high brightness, and the LCD back A light source device that is very suitable as a light is realized.

FIG. 2 shows another embodiment of the present invention, in which the fluorescent lamp 10 is completely embedded inside the light guide plate 14. That is, when molding the light guide plate 14, the fluorescent lamp 10 is embedded and integrally molded, and a diffusion coating layer 14b is provided on the back surface for reflection. The other configurations are the same as in FIG. 1. In the case of this embodiment, the same effect as in FIG. 1 is achieved, and the fluorescent lamp 1
This eliminates the need for 0 installation work and facilitates handling.

The fluorescent lamp 10 in these embodiments may be a cold cathode lamp that emits electrons through ion collision and has a long life and low brightness, or a cold cathode lamp that emits thermoelectrons when the electrodes are heated and has a short lifespan. Either a hot cathode tube, which has the characteristics of long life and high brightness, or a semi-hot fluorescent tube, which has the characteristics of both, can be applied. In addition, the shape may be a U-shaped tube, a straight tube, or a W tube, as long as it is determined according to the size of the liquid crystal screen to which it is applied. In the case of the embodiment shown in FIG. 1, the groove 11a may be formed in the light guide plate 11 in accordance with the shape of the fluorescent lamp 10 employed.

Note that examples such as those shown in FIGS. 3 and 4 can be considered as examples that achieve thinness and high brightness output. That is, as shown in FIG. 3(a), the light guide plate 20 is surrounded by U-shaped fluorescent lamps 21, and as shown in FIG. A diffusion sheet 23 is arranged to serve as a light emitting surface. Alternatively, as shown in FIG. 4, the light guide plate 20 may be surrounded by fluorescent lamps 24. The front and back configurations of the light guide plate 20 are similar to those shown in FIG. 3(b).

In these embodiments, the brightness is improved compared to the conventional light guide plate type backlight explained in FIG. 6, and since only one fluorescent lamp is used, the inverter circuit associated with the fluorescent lamp is It has the advantage that it is possible to reduce the size of the circuit and reduce the cost.

Note that the light source devices of the various embodiments shown in FIG.
．． It is very suitable as a backlight for a liquid crystal display device with a size of about 7 to 10 inches.

[0017]

[Effects of the Invention] As explained above, the light source device of the present invention has the effect that by configuring the fluorescent lamp to be located inside the light guide plate, the light source device can be made thinner and achieve high brightness output at the same time. For example, it is suitable for backlights for liquid crystal displays. Further, the high brightness output enables power saving, and the integration of the fluorescent lamp with the light guide plate simplifies manufacturing.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view and a sectional configuration diagram showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view and a cross-sectional configuration diagram showing another embodiment of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment of the light source device.

FIG. 4 is an explanatory diagram of a fourth embodiment of the light source device.

FIG. 5 is an explanatory diagram of a conventional direct-light type backlight.

FIG. 6 is an explanatory diagram of a conventional light guide plate type backlight.

[Explanation of symbols]

10 Fluorescent lamp 11, 14 Light guide plate 11a Groove 12. Lighting curtain 13 Diffusion sheet

Claims (1)

[Claims] 1. A light source device characterized in that a fluorescent lamp is located inside a light guide plate.