JP2000340018A - Lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent adverse effect of heat on a light diffusion plate or a prism sheet by installing the light diffusion plate on the top surface of a light guide plate for radiating light from a light source from the top surface and a second frame coupled with a first frame, and forming a gap between the light diffusion plate and the second frame. SOLUTION: When an electric energy is supplied, a light source 9 is lit, light comes in a light guide plate 4, is emitted from the top surface of the light guide pate 4, and radiated upward through a light diffusion plate 6 and a prism sheet 7. When the light source 9 is lit for a long time, heat is generated, and temperature of the whole lighting system is raised. The thin light diffusion plate 6 or the thin prism sheet 7 is bent or deformed by the influence of temperature. If they are closely arranged with no gap, they cannot deform, unreasonable force is applied, and troubles may be caused. Since the deformation is absorbed by a gap, the generation of troubles is avoided, and when temperature is lowered, the deformation is recovered to eliminate troubles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a lighting device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been frequently used for displaying images on personal computers, word processors, video cameras, and the like, and the applications thereof have been diversified and are increasing. As the liquid crystal display device, there is one disclosed in JP-A-10-199487, which illuminates the liquid crystal display device from behind the liquid crystal display device by an illuminating device, and recognizes an image from the front surface of the liquid crystal display device. It is configured as follows.

[0003]

The above-mentioned device requires an illuminating device for illuminating the liquid crystal display element from the back, and the illuminating device receives light from a fluorescent discharge tube of a cold cathode or a hot cathode. A light guide plate is provided on the front surface, and a light diffusion plate and a prism sheet are sequentially arranged on the upper surface of the light guide plate. Light from the fluorescent discharge tube is incident on the side surface of the light guide plate, and light emitted from the upper surface of the light guide plate is diffused. The light is emitted through a plate and a prism sheet to illuminate the liquid crystal display element.

[0004] In recent years, this type of lighting apparatus has been tending to be thin, and therefore, a chassis, a light guide plate, a light source, a light diffusion plate, and further a prism sheet are housed in a very thin and narrow container. In general, an elongated straight tube type cold cathode or hot cathode fluorescent discharge tube is often used as the light source. Recently, a very thin tube having a diameter of about 2 mm and a high light efficiency has been used. However, even a light emitting device having such a diameter generates a considerable amount of heat when emitting light, and the generated heat increases the temperature of the entire device.

[0005] By the way, a light diffusion plate and a prism sheet on the light guide plate which are as thin as about 200 µm are used and often warp even at a slight temperature. On the other hand, as mentioned above,
In order to reduce the thickness of the device, a light guide plate, a light diffusion plate, and a prism sheet are assembled so as to be densely overlapped. Therefore, in such a tightly assembled state, if the temperature of the device rises due to the heat generated by the light source, the light diffusion plate and the prism sheet cannot cope with the temperature rise, and the temperature acts forcibly to cause the light diffusion plate and The prism sheets may be cracked or distorted due to temperature, and their performance may be impaired during use.

Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide an illuminating device in which the action of heat is not forcibly applied to a light diffusion plate or a prism sheet.

[0007]

In order to achieve the object of the present invention, even if warpage or deformation due to temperature rise occurs above a light reflecting plate or a prism sheet disposed on the upper surface of a light guide plate,
The light diffusion plate or the prism sheet is provided with a gap that can thermally respond.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is such that a gap is provided between the light diffusing plate and the upper first frame, and the warping of the light diffusing plate due to a rise in temperature and the like. Deformation can be handled by the gap.

According to a second aspect of the present invention, a gap is provided between a prism sheet disposed on an upper surface of a light diffusing plate and an upper first frame, and the light diffusing plate is raised due to a rise in temperature. Warpage and deformation can be handled by the gap.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is a perspective view of a lighting device according to an embodiment of the present invention, wherein 1 is an upper frame, 2 is a lower frame, and 10 and 13 are incorporated in a container constituted by a frame 1 and a frame 2. Lead wires electrically connected to the electrodes of the light source
Reference numeral 12 denotes a frame hole of the upper frame.

FIG. 2 is a longitudinal sectional view taken along line AA of FIG. In the figure, 3 is a chassis, 4 is a light guide plate incorporated in the chassis, 5 is a light reflection sheet disposed on the bottom surface of the chassis, 6 is a light diffusion plate disposed on the upper surface of the light guide plate, and 7 is a light diffusion plate. It is a prism sheet arranged on the upper surface. 8 is a gap provided between the frame hole 12 of the upper frame and the prism sheet, 9 is a light source such as a cold cathode or hot cathode fluorescent discharge tube, 10 is a lead wire electrically connected to an electrode of the light source, 11 is a frame hole of the lower frame, and 12 is a frame hole of the upper frame.

In the lighting apparatus having the above-described structure, when electric energy is supplied to the light source 9 through the lead wires 10 and 13, the light source is turned on, and the light emitted from the light source enters the light guide plate.
Light is emitted from the upper surface of the light guide plate. The emitted light is emitted upward through the light diffusion plate 7 and the prism sheet 8.

By the way, when the light source is turned on for a long time, for example, heat is naturally generated, and the generated heat increases the temperature of the entire apparatus. Therefore, a light diffusion plate or a prism sheet having a small thickness is warped or deformed under the influence of the temperature. If they are densely arranged without gaps, they cannot be deformed, and excessive force may be applied to the light diffusion plate or the prism sheet, which may cause the above-described problem. However, this deformation can be sufficiently dealt with by the gap 8, and there is no danger of such a problem occurring. Then, when the temperature of the device decreases after use, the deformation of the light diffusion plate and the prism sheet is restored to the original state, and there is no problem in the next use.

In this embodiment, the prism sheet is provided, but it is not always necessary depending on the form of the light guide plate and the light diffusion plate.

[0016]

As described above, the illuminating device of the present invention is densely arranged because the light diffusing plate or the prism sheet is provided with a gap that can cope with warping or deformation due to a rise in temperature during use. As described above, it is possible to provide a lighting device capable of completely removing the influence of receiving an extra force due to a temperature rise.

[Brief description of the drawings]

FIG. 1 is a perspective view of a lighting device according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the lighting device of the embodiment of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper frame 2 Lower frame 3 Chassis 4 Light guide plate 5 Light reflection plate 6 Light diffusion plate 7 Prism sheet 8 Gap 9 Light source

Claims (2)

[Claims] 1. A first frame, a chassis incorporated in the frame, a light source mounted on the chassis, a light reflector mounted on the chassis, and the light source disposed on an upper surface of the light reflector. A light guide plate that emits light from the upper surface, the light diffuser plate being provided on the upper surface of the light guide plate, and a second frame combined with the first frame; A lighting device comprising a gap provided between the first frame and the second frame. 2. A first frame, a chassis incorporated in the frame, a light source mounted on the chassis, a light reflector mounted on the chassis, and the light source disposed on an upper surface of the light reflector. A light guide plate that emits light from which light is incident from the top surface, a light diffusion plate provided on the top surface of the light guide plate, a prism sheet disposed on the top surface of the light diffusion plate, and the first frame. An illumination device comprising a second frame to be combined, wherein a gap is provided between the prism sheet and the second frame.