JP2000106020A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a liquid crystal display device in which a display defect referred to as an Ekubo defect does not occur. SOLUTION: The liquid crystal display panel 1 and the liquid crystal display panel 1
A liquid crystal display device 11 comprising a wedge-type light guide plate 4 having a thicker light incident side 4a from a light source provided on the back surface of
The light-emitting side 4 of the wedge-type light guide plate 4 is provided on the back of the liquid crystal display panel 1.
d is held in contact.

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 comprising a liquid crystal display panel and a wedge type light guide plate.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been rapidly advanced in research, development, manufacturing, etc. due to their features such as small size, light weight, and low power consumption, and have been widely used in various fields.
O such as word processors and personal computers
Use in the field of A equipment is becoming remarkable.

In addition, with the recent reduction in the weight and thickness of OA equipment, there has been a strong demand for a thinner liquid crystal display device used in the OA equipment. 2 and 3 show a conventional liquid crystal display device.

FIG. 2 is a sectional view of a liquid crystal display device, and FIG.
Shows the configuration of a wedge-type light guide plate used in a liquid crystal display device. As shown in FIG. 2, the liquid crystal display device 11 has a cold cathode tube 8 as a light source and light emitted from the cold cathode tube 8 on the back of the liquid crystal display panel 1 provided with a drive circuit (not displaying). And a wedge-shaped light guide plate 4 for irradiating the liquid crystal display panel 1 with the liquid crystal display panel 1, the cold cathode tubes 8 and the wedge-type light guide plate 4 are held by the back metal plate 3, and fixed by the front metal frame 2 and the resin frame 9. By doing so, it is configured integrally.

More specifically, on both sides of the liquid crystal display panel 1,
Deflection plates 12a and 12b are provided. Deflection plate 12b
For example, as shown in FIGS. 3A and 3B, the wedge-type light guide plate 4 arranged on the side
In general, a wedge shape is formed so that the thickness decreases from a to the side 4b, and projections 4e and 4f for fitting with the resin frame 9 are formed on both sides thereof.

The light emitting surface 4d adjacent to the rear surface of the liquid crystal display panel 1 is a mirror surface, and the light reflecting surface 4c is printed or dug with a pattern for uniformly guiding the light from the end surface to the surface. The lens sheet 5 and the diffusion sheet 6 are sequentially laminated on the light exit surface 4d side, and the reflection sheet 7 is provided on the light reflection surface 4c.

[0007] The liquid crystal display panel 1 configured as described above.
The wedge-type light guide plate 4 is held by a resin frame 9 with the back surface of the liquid crystal display panel 1 and the light-emitting surface 4d of the wedge-type light guide plate 4 facing each other. The space 10 shown is formed.

[0008]

In the liquid crystal display device 11 configured as described above, the wedge-type light guide plate 4 is formed of an acrylic resin. Acrylic resin is a substance that is easily deformed into a convex or concave shape in a high-temperature and high-humidity atmosphere. In the liquid crystal display device 11 using the wedge-type light guide plate 4 made of such a material, the ambient temperature of the device increases, Under such an environment, the wedge-type light guide plate 4 incorporated in the liquid crystal display device 11 is easily deformed into a convex or concave shape.

In particular, when the wedge-type light guide plate 4 bulges toward the space 10 and becomes a convex shape, the convex portion of the deformed wedge-type light guide plate 4 comes into contact with the rear surface of the liquid crystal display panel 1 so that a liquid crystal display is formed. There is a problem that the display of the panel 1 is disturbed, and a display defect called an ecbo defect occurs.

An object of the present invention is to provide a liquid crystal display device which solves the above-mentioned problem and does not cause a display defect called "ecbo defect".

[0011]

The liquid crystal display device of the present invention is characterized in that the space between the back surface of the liquid crystal display panel and the wedge-type light guide plate is eliminated.

According to the present invention, it is possible to provide a liquid crystal display device having good display quality by suppressing the deformation of the wedge-type light guide plate in the high or high humidity atmosphere.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The liquid crystal display device according to the first aspect is
The wedge-type light guide plate constituting the liquid crystal display device is sandwiched between the liquid crystal display panel and the back plate to prevent the wedge-type light guide plate from being deformed into a convex or concave shape.

According to this configuration, deformation of the wedge-type light guide plate in a high-temperature and high-humidity atmosphere can be suppressed, and a display defect called an exbo defect can be eliminated. According to a second aspect of the present invention, in the liquid crystal display device according to the first aspect, the thickness of the wedge-type light guide plate on the light incident side is 2.5 mm or less.

According to this configuration, it is possible to more effectively eliminate the ecbo defect. According to a third aspect of the present invention, in the liquid crystal display device according to the first or second aspect, the wedge-type light guide plate is made of a soft resin.

According to this structure, the wedge-type light guide plate has a weak force to deform convexly or concavely, and even if it tries to deform convexly, the glass plate constituting the liquid crystal display panel is stronger.
Since it cannot be deformed, it is possible to prevent the occurrence of an ecbo defect.

According to a fourth aspect of the present invention, there is provided a liquid crystal display device.
The liquid crystal display panel according to any one of claims 1 to 3, wherein the surface side of the back polarizing plate of the liquid crystal display panel is roughened. According to this configuration, it is possible to eliminate the occurrence of Newton rings due to the contact between the liquid crystal display panel and the wedge-type light guide plate.

Hereinafter, each embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. 2 and 3 showing the above conventional example.
The same components as those described above will be described with the same reference numerals.

(Embodiment 1) FIG. 1 shows (Embodiment 1) of the present invention. The configuration is almost the same as that shown in FIGS. 2 and 3 showing the above-mentioned conventional example, but in this (Embodiment 1), the rear surface of the liquid crystal display panel 1 and the wedge-shaped conductive member provided with the lens sheet 5 and the diffusion sheet 6 are provided. The difference is that the light exit surface 4d of the light plate 4 is in contact with the light exit surface 4d.

More specifically, the liquid crystal display panel 1 is placed in a front metal frame 2 having a window formed in the center, and a wedge is formed such that the rear surface of the liquid crystal display panel 1 and the light emitting surface 4d of the wedge-type light guide plate 4 face each other. The light guide plate 4 is inserted, the cold cathode tubes 8, the resin frame 9 and the like are sequentially inserted, and the back metal plate 3 is arranged so as to abut the reflection surface 4 c of the wedge-shaped light guide plate 4.

In a state where the back metal plate 3 is regulated so that the light exit surface 4d of the wedge-shaped light guide plate 4 is in contact with the back surface of the liquid crystal display panel 1, the front metal frame 2 is attached to the bent portions 3a and 3b of the back metal plate 3. Some of the claws 2a and 2b are bent inward to engage and fix.

In the liquid crystal display device 11 assembled in such a state, the wedge-shaped light guide plate 4 is held by the back metal plate 3 so as to be pressed against the liquid crystal display panel 1, so that the above-described conventional example is shown. In 2, the space 10 formed between the back surface of the liquid crystal display panel 1 and the light exit surface 4d of the wedge-shaped light guide plate 4 is eliminated.

Since the wedge-type light guide plate 4 is formed of an acrylic resin, it is considered that the wedge-type light guide plate 4 is deformed in a high-temperature and high-humidity atmosphere. Therefore, the wedge-type light guide plate 4
In order to examine the degree of deformation due to the difference in the thickness of the light incident side 4a of the wedge-shaped light guide plate 4, the thickness d of the light incident side 4a of the wedge type light guide plate 4 is set to 4.
The liquid crystal display device 1 was formed in a range of 0 mm to 1.5 mm in increments of 0.5 mm, and a reliability test was performed in a high-temperature and high-humidity environment.

Table 1 shows the obtained measurement results.

[0025]

[Table 1]

As shown in Table 1, when the thickness d on the light incident side of the wedge-type light guide plate 4 exceeds 2.5 mm, the wedge-type light guide plate 4 is placed on the rear side of the liquid crystal display panel 1 in a high-temperature and high-humidity atmosphere. The force to expand is stronger than the force to deform the glass plate constituting the liquid crystal display panel 1, so that the glass is pressed and an exbo defect occurs.

Therefore, in the present invention, in addition to the configuration in which the rear surface of the liquid crystal display panel 1 is brought into contact with the light exit surface 4d of the wedge-type light guide plate 4, the thickness d of the wedge-type light guide plate 4 on the light incident side is reduced. When the thickness is 2.5 mm or less, the ecbo defect is eliminated.

Further, between the reflection sheet 7 provided on the reflection surface 4c of the wedge-shaped light guide plate 4 and the back metal plate 3 as a reinforcing material for the back metal plate 3 so that the wedge-type light guide plate 4 is not deformed in a concave shape. May be interposed.

(Embodiment 2) In the above (Embodiment 1), the wedge-type light guide plate 4 is made of acrylic resin. In this (Embodiment 2), the wedge-type light guide plate 4 is made of acrylic resin. The difference is that it is formed of a soft silicon resin, and the other points are substantially the same as those of the first embodiment.

With such a structure, the wedge-type light guide plate 4 made of a silicon resin does not deform even in a high-temperature and high-humidity atmosphere because the silicon resin has a small hygroscopic property. Even if it is 2.5 mm or more, it will not be deformed, and it is possible to eliminate the ecbo defect. In addition, a soft resin such as a silicon-based resin has a weak force of deforming into a convex or concave shape, and does not push and deform the glass plate constituting the liquid crystal display panel 1 to cause an exbo defect.

(Embodiment 3) Although the structure is almost the same as that of (Embodiment 1), in this (Embodiment 3),
Although the above-described configuration (Embodiment 1) alone eliminates the ecbo defect, a so-called Newton's ring may occur in some cases.

That is, the back polarizing plate 1 of the liquid crystal display panel 1
Since the surface of 2b is a mirror surface, in some cases,
A so-called Newton ring may occur. Therefore, the surface of the back polarizing plate 12b, here, the surface of the back polarizing plate 12b is directly scratched or roughened to form irregularities, and the Newton ring can be eliminated by making the surface non-boundary. . The unevenness or flaw has a center line average roughness (Ra) of 0.3 μm to 2.0 μm according to JIS B0601 (1982).

[0033]

As described above, according to the liquid crystal display device of the present invention, since the back surface of the liquid crystal display panel and the wedge-type light guide plate are held in contact with each other, the occurrence of so-called ecbo defects is suppressed, and the liquid crystal display device is excellent. Display quality can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a liquid crystal display device in Embodiment Mode.

FIG. 2 is a front view and a side view of a conventional wedge-type light guide plate.

FIG. 3 is a front view and a side view of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 Front metal frame 3 Back metal plate 4 Wedge type light guide plate 5 Lens sheet 6 Diffusion sheet 7 Reflection sheet 8 Cold cathode tube 9 Resin frame 11 Liquid crystal display

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Sakakura 1006 Kazuma Kadoma, Kazuma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (Reference) 2H091 FA08Z FA16Z FA21Z FA23Z FA26Z FA32Z FA42Z FB02 FC25 FD13 KA10 LA04 LA21

Claims (4)

[Claims] 1. A liquid crystal device comprising a liquid crystal display device comprising a wedge-type light guide plate sandwiched between a liquid crystal display panel and a back plate to prevent the wedge-type light guide plate from being deformed into a convex or concave shape. Display device. 2. A wedge-type light guide plate having a light incident side thickness of 2.5
The liquid crystal display device according to claim 1, which is not more than mm. 3. The liquid crystal display device according to claim 1, wherein the wedge-type light guide plate is made of a soft resin. 4. The liquid crystal display device according to claim 1, wherein the surface side of the back polarizing plate of the liquid crystal display panel is roughened.