JP3243833B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight structure for a liquid crystal display.

[0002]

2. Description of the Related Art Transmissive and transflective liquid crystal display devices using a backlight are widely used as portable display devices because of their thinness, light weight, and good visibility. As a backlight light source for such a liquid crystal display device, a sidelight type, which can be relatively easily reduced in thickness as shown in FIG. In the figure, the liquid crystal panel is composed of two glass plates 2 on which transparent electrodes are formed and a seal 4.
After the liquid crystal layer 3 is formed therebetween, the polarizing plate 1 is attached to the glass plate 2 to be manufactured. A diffusion film 6, a light guide plate 7, a reflection plate 8, a cathode tube 9 After disposing a backlight unit composed of the cathode tube reflector 10, the case 11 is entirely covered to manufacture a liquid crystal display device. The cathode tube 9 in the backlight unit
Is reflected by the cathode ray tube reflector 10 and radiated to the light guide plate 7. The light is supplied to the liquid crystal panel through the diffusion film 6 by the reflection plate 8 while being transmitted through the light guide plate 7.
It is to be noted that the reflectance of the reflection plate 8 is changed depending on the distance from the cathode tube 9 or the light is dispersed by the diffusion film 6 so that the brightness of the entire liquid crystal panel becomes uniform.

[0003]

However, in the above-mentioned prior art, since the liquid crystal panel and the backlight unit are separate parts, the structure must be such that the liquid crystal panel and the backlight unit are fixed using a case or the like. There is a problem that it becomes complicated and costs increase. Also,
Since a space is formed between the liquid crystal panel and the backlight unit, there is also a problem in that display quality is deteriorated due to intrusion of dust.

Accordingly, the present invention is to solve such a problem. It is an object of the present invention to provide a liquid crystal display device in which cost can be reduced by simplifying an assembly structure and dust does not enter. There.

[0005]

According to the present invention, there is provided a liquid crystal display device comprising: a liquid crystal panel having a liquid crystal layer between two substrates; and a backlight for supplying light to the liquid crystal panel. And an adhesive layer containing an adhesive and a filler between the liquid crystal panel and the backlight, wherein the adhesive is an acrylic adhesive or an epoxy adhesive.
Selected from agents, the filler is a glass filler,
The adhesive layer has a function of diffusing light from the backlight.

[0006]

In a liquid crystal display device comprising a liquid crystal panel having a liquid crystal layer between two substrates, and a backlight for supplying light to the liquid crystal panel, a liquid crystal display device includes a liquid crystal panel between the liquid crystal panel and the backlight. Has an adhesive layer containing an adhesive and a filler, the adhesive is selected from an acrylic adhesive and an epoxy adhesive, the filler is a resin filler, and the light from the backlight emits the adhesive layer. Is characterized by being diffused.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention. An adhesive layer 12 is formed between the polarizing plate 1 below the liquid crystal panel and the diffusion film 6 on the surface of the backlight unit, and the liquid crystal panel and the backlight unit are bonded. The adhesive is set on either the polarizing plate or the diffusion film, and when assembling the liquid crystal display device, the liquid crystal panel and the backlight unit are lightly pressed and integrated. For this reason, the number of assembling steps is simplified, and the cost can be reduced. In addition, since there is no space between the liquid crystal panel and the backlight unit, there is no intrusion of dust.

[Embodiment 2] FIG. 2 is a sectional view of an embodiment of the present invention.

The difference from the first embodiment is that an epoxy adhesive layer 13 is formed between the liquid crystal panel and the backlight unit. This time, the epoxy adhesive used was a transparent and room temperature curing type. Before assembling the liquid crystal display device, an epoxy adhesive is printed on the diffusion film of the backlight unit by using a screen printing method, and then the liquid crystal panel is placed while being aligned, and left for 30 minutes while applying a load of 50 g. And let it cure. By performing such pre-processing in advance, it is possible to reduce the number of assembling steps of the liquid crystal display device and to prevent dust from entering, as in the first embodiment. Needless to say, the same effect can be obtained even when printing the adhesive on the liquid crystal panel surface.

[Embodiment 3] FIG. 3 is a sectional view of an embodiment of the present invention and a top view of an adhesive printing surface. The difference from the second embodiment is that the adhesive is arranged not in the entire surface of the diffusion film but in a frame shape around the diffusion film. An epoxy adhesive was used in the same manner as in Example 2. However, in this case, a non-transparent adhesive, which is less expensive than that of Example 2, could be used to print around the diffusion film that was off the display position of the liquid crystal.

As for the printing method of the adhesive, a dispenser could be used in addition to the screen printing method used in Example 2. Also, by adding 5% of a filler having a maximum particle size of 200 μm to the adhesive, the adhesive did not spread even when a load was applied when the adhesive was cured, so that an adhesive layer having a uniform thickness could be formed. It should be noted that in a product such as a small liquid crystal display device having a size of about 100 mm × 30 mm that does not require much uniformity of the adhesive layer, it may not be necessary to mix the filler. Also in the liquid crystal display device manufactured by the above method, as in the first and second embodiments, the number of assembling steps can be reduced and contamination of dust can be prevented. Further, in the case of this method, even if a defective product is mixed in the liquid crystal panel or the diffusion film, the liquid crystal panel and the diffusion film can be separated with a relatively light force, so that the repair becomes easy. In addition, particularly in the case of a product having a strict weight limit, there is an advantage that the amount of the adhesive used is small and thus the product is advantageous.

Example 4 A liquid crystal display having the same structure as that of Example 2 was manufactured using an acrylic adhesive. This time, an acrylic adhesive was printed on the diffusion film before the reflection plate 8 was attached to the backlight unit, and the liquid crystal panel was irradiated with ultraviolet rays while applying a load of 50 g to cure the acrylic adhesive. After the adhesive was cured, a reflector was attached to the light guide plate 7 to complete the function as a backlight unit.

According to the above method, as in the other embodiments, the number of assembling steps of the liquid crystal display device can be reduced and the intrusion of dust can be prevented. In addition, since the adhesive can be cured by ultraviolet rays, the curing time can be drastically reduced to several seconds.

Example 5 A liquid crystal display having the same structure as that of Example 2 was manufactured using a silicon-based adhesive as the adhesive. The manufacturing method this time is exactly the same as that of the second embodiment. According to this method, as in the other embodiments, the number of assembling steps of the liquid crystal display device can be reduced, and entry of dust can be prevented. Also,
Even if a large-area liquid crystal panel of 284 mm x 196 mm is used, a liquid crystal display without cracking of the adhesive layer caused by the difference in thermal expansion between the liquid crystal panel and the backlight module can be obtained by selecting a silicone adhesive having low hardness and elasticity. The device could be manufactured.

Example 6 A liquid crystal display having the same structure as in Example 2 was manufactured using a hot-melt type adhesive as the adhesive. This time the melt temperature of the hot melt adhesive is 8
The temperature was set to 0 ° C., and a plate-like adhesive having a thickness of 0.5 mm was placed between the liquid crystal panel and the backlight unit.
Bonding was performed by heating to ° C. By this method, as in the other embodiments, it was possible to reduce the number of assembling steps of the liquid crystal display and to prevent dust from entering. Furthermore, in the case of this method, even if a defective product is mixed in the liquid crystal panel or the diffusion film, it is easy to repair the liquid crystal panel and the diffusion film by heating the whole to 80 ° C. Have.

Embodiment 7 FIG. 4 is a sectional view of an embodiment of the present invention. The difference from the previous embodiments is that one surface of the polarizing plate on the lower surface of the liquid crystal panel is roughened and that no diffusion film is used in the backlight unit.
Also in this method, as in the other embodiments, the number of assembling steps of the liquid crystal display device can be reduced, and intrusion of dust can be prevented. In addition, by roughening the surface of the polarizing plate, the polarizing film itself was made to have a light diffusing property, and the cost of the parts could be reduced by eliminating the diffusing film. Needless to say, the methods of Embodiments 1 to 6 can be used to realize the above structure.

Embodiment 8 FIG. 5 is a sectional view of an embodiment of the present invention. Example 4 differs from Example 4 in that 30% of a glass filler having an average particle size of 100 μm was mixed in an acrylic adhesive, and that no diffusion film was used in the backlight unit. By this method, as in the other embodiments, it was possible to reduce the number of assembling steps of the liquid crystal display and to prevent dust from entering. In addition, even if the filler diffused the light and there was no diffusion film, the luminance variation of the light emitting surface of the backlight was within 10%, and a good luminance uniformity could be obtained. Needless to say, an epoxy-based adhesive can provide the adhesive layer with the same effect as the diffusion film. In addition, it goes without saying that a diffusion film can be omitted by mixing a substance other than the glass filler, such as a resin filler, having an effect of diffusing light into the adhesive.

[0020]

As described above, according to the liquid crystal display device of the present invention, the effect that the light emitted from the backlight reaches the liquid crystal panel after being dispersed in the adhesive layer occurs. Even when the omitted structure is selected, the effect of each step that the luminance of the liquid crystal display device becomes uniform can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view and a top view of an adhesive printing surface according to a third embodiment of the present invention.

FIG. 4 is a sectional view showing a seventh embodiment of the present invention.

FIG. 5 is a sectional view showing an eighth embodiment of the present invention.

FIG. 6 is a diagram showing a conventional liquid crystal display device.

[Explanation of symbols]

 1. Polarizing plate 2. Glass plate 3. Liquid crystal layer 4. Spacer 6. Diffusion film 7. Light guide plate 8. Reflector plate 9. Cathode tube 10. Reflector plate 11. Case 12. Adhesive 13. Adhesive 14. Filler

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/13357 G09F 9/00 336

Claims (2)

(57) [Claims] 1. A liquid crystal display device comprising: a liquid crystal panel having a liquid crystal layer between two substrates; and a backlight for supplying light to the liquid crystal panel, between the liquid crystal panel and the backlight. Is the adhesive and
And an adhesive layer containing filler and filler , wherein the adhesive is an acrylic adhesive or an epoxy adhesive.
The filler is a glass filler, and the adhesive layer has a function of diffusing light from the backlight. 2. A liquid crystal display device comprising: a liquid crystal panel having a liquid crystal layer between two substrates; and a backlight for supplying light to the liquid crystal panel, between the liquid crystal panel and the backlight. Has an adhesive layer containing an adhesive and a filler, the adhesive is selected from an acrylic adhesive and an epoxy adhesive, the filler is a resin filler, and the light from the backlight is the adhesive layer. A liquid crystal display device characterized by being diffused by: