JP2000162595A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance liquid crystal display device dissolving moire stripes and enhancing display image quality. SOLUTION: In the liquid crystal display device 14 consisting of a liquid crystal display panel 2 and an illuminator 3a, a light diffusion plate 9 is formed on one side surface of the light transmission plate 5 of the illuminator 3a, and a light reflection plate 8 is formed on the other side surface, and further, a light source 6 is provided on the end surface of the light transmission plate 5, and a dot like pattern 15 is formed belt-likely in the vicinity of the light source 6 on the light diffusion plate 9 along the longitudinal direction, and its arrangement property is pattern formed so as to become non-parallel to either of the X direction and Y direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device having an edge light type illumination device (backlight).

[0002]

2. Description of the Related Art FIG. 7 is a sectional view of a liquid crystal display device 1 provided with an edge light type illumination device. 2 is a liquid crystal display panel, 3 is a lighting device, 4 is a liquid crystal display panel 2 and a lighting device 3
Bezel. In the lighting device 3, 5 is a light guide plate made of a transparent material, 6 is a light source such as a cold cathode discharge tube arranged on an end face of the light guide plate 2, 7 is a light reflective reflector attached so as to cover the light source 6, Reference numeral 8 denotes a light reflecting plate, 9 denotes a light diffusing plate for diffusing the emitted light when the light entering the light guiding plate 5 is emitted while being reflected by the light reflecting plate 7, and 10 denotes a light diffusing plate. This is a lens sheet for condensing outgoing emitted light, and is made up of one or more sheets.

According to the liquid crystal display device 1, the light source 6 approaches the light diffusing plate 9 in response to the recent market demand for miniaturization, so that the diffused light of the light diffusing plate 9 tends to be non-uniform. And becomes extremely bright near the light source 6,
There is a problem that a so-called bright line is generated.

In order to solve this problem, a light diffusing plate 9 is required.
(Japanese Utility Model Laid-Open No. 5-64829).

On the other hand, the liquid crystal display panel 2 is locally heated by the heat generated by the light source 6, thereby causing a problem that the threshold value for each pixel fluctuates, thereby causing uneven brightness. On the other hand, as shown in FIGS. 8 and 9, there has been proposed a technique of printing a dot pattern in the vicinity of the light source 6 on the light diffusion plate 8.

FIG. 8 shows an arrangement relationship between the light diffusing plate 8 and the light source 6, and FIG. 9 is an enlarged view of a region A in FIG. The light diffusion plate 8 is screen-printed with a light-shielding ink to form a strip-shaped light-shielding dot pattern 11. The light-shielding dot-shaped pattern 11 is provided by dot printing in which pattern arrangement rules are regularly arranged, thereby facilitating design and production of a printing plate and simplifying the printing plate. Further, a dot-shaped aggregate having a larger occupied area closer to the light source 6 is formed. FIG. 9 shows an example of the regularity of the dot pattern 11. The dot pitch is arranged along the orthogonal X and Y directions. For example, the dot pitch is 0.9 mm in the X direction and 6.0 mm in the Y direction. is there.

[0007] By forming the dot-shaped pattern 11, it is possible to reduce the luminance unevenness caused by the bright line caused by the light diffusing plate 8 and the threshold variation of each pixel due to the heat generated by the light source 6.

[0008]

However, since the pixel patterns are arranged in the X direction and the Y direction, there is a problem that the display image quality is reduced. This problem will be described in detail with reference to FIGS.

FIG. 10 shows an arrangement of pixel patterns 12 in a color liquid crystal display device, and FIG. 11 shows an arrangement of pixel patterns 13 in a monochrome liquid crystal display device. In each case, each pixel region has a rectangular shape. In addition, each pixel pattern 1
Both 2 and 13 are regularly arranged in a matrix in the X and Y directions, and are arranged at a constant pitch. Then, the pixel pattern 12 and the dot pattern 11
Are superimposed in a parallel and orderly manner in both the X and Y directions, as shown in FIG. 12, thereby causing optical interference due to the respective arrangement relationship between the pixel pattern 12 and the dot-shaped pattern 11. Interference fringes called fringes were formed, and as a result, the quality of the displayed image was reduced. In addition, even when the pixel pattern 13 and the dot pattern 11 were overlapped, moire fringes were similarly generated.

Therefore, the present invention has been completed in view of the above circumstances, and an object of the present invention is to provide a high-performance liquid crystal display device in which moire fringes are eliminated and display image quality is improved.

[0011]

According to the liquid crystal display of the present invention, a light reflecting member is provided on one main surface and a light scattering member is provided on the other main surface of a light guide plate having a long light source disposed on an end face. A lighting device is mounted, and a liquid crystal display panel in which a number of pixels are arranged in a matrix with a predetermined matrix regularity is mounted on a light scattering member of the lighting device, and the light guide plate, the light scattering member or the light The light-shielding layer formed along the longitudinal direction in the vicinity of the elongated light source on any surface of the reflecting member is configured so as to be formed of a dot-shaped aggregate having an occupied area larger as being closer to the elongated light source. Whether the dot-shaped aggregate of the light-shielding layer is dot-arranged at a shift angle of 1 to 44 ° with respect to at least one of the row direction and the column direction in the predetermined matrix regularity,
Alternatively, a random dot group is provided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to FIGS. FIG. 1 is a sectional view of a main part of a liquid crystal display device, FIG. 2 shows an arrangement relationship between a light diffusion plate and a light source in the liquid crystal display device, and FIG. 3 shows a dot pattern in a region B formed on the light diffusion plate. FIG. 4 shows a state in which the pixel pattern and the dot pattern are overlapped. FIG. 5 shows an arrangement relationship between a light diffusion plate and a light source in another liquid crystal display device, and FIG. 6 shows a dot pattern in a region C formed on the light diffusion plate. The same parts as those of the liquid crystal display device 1 shown in FIGS.

In the liquid crystal display device 14 shown in FIG. 1, a liquid crystal display panel 2 for displaying images and a lighting device 3a are held by a bezel 4. The liquid crystal display panel 2 is formed by bonding two glass substrates on which electrodes are patterned through a sealing material and sealing the liquid crystal, thereby defining an effective display area where an image is displayed.
An effective light emitting area is also defined in the lighting device 3a so as to face the effective display area.

The illumination device 3a has a light diffusing plate 9 formed on one surface of a flat or wedge-shaped light guide plate 5 made of a transparent acrylic resin, and a light reflecting plate 8 formed on the other surface. One or a plurality of lens sheets for condensing light may be provided on the light diffusion plate 9. A light source 6 is provided on an end face of the light guide plate 5 and further covers a reflector 7. Irradiation light from the light source 6 is reflected by the reflector 7 and guided into the light guide plate 5.

Further, a dot-like pattern 15 is formed in a strip shape along the longitudinal direction in the vicinity of the light source 6 on the light diffusion plate 9, thereby eliminating bright lines and luminance unevenness due to unevenness of diffused light near the light source 6. are doing. Further, uneven brightness caused by heat generation of the light source 6 is also reduced.

In the present invention, the dot pattern 15 is formed in the X direction and the Y direction in which the dot arrangement is orthogonal.
The pattern is formed so as to be non-parallel to the direction.

That is, the pixel pattern 12 shown in FIG.
The pixel patterns 13 in FIG. 11 are regularly arranged at a constant pitch in the X direction and the Y direction, and are arranged in a matrix with matrix regularity.
When the pixel pattern 12 and the pixel pattern 13 (or the pixel pattern 13) are overlapped, the dot pattern 15 is patterned so as to be non-parallel in both the X and Y directions.

For example, the dot pattern 1 shown in FIG.
In No. 5, the arrangement angle (shift angle) in the oblique direction with respect to the matrix arrangement is set to 30 ° or 60 °. Further, the dot diameter decreases as the distance from the light source 6 increases. In this manner, the belt-like regions are provided with the dot diameters, and the respective regions are displayed with the boundary lines.

In the present invention, in a dot arrangement having a dot pattern 15 in which the X direction and the Y direction are orthogonal to each other, the shift angle between the X direction and the Y direction is 1 to 44 °.
Or, it is defined orthogonally so as to be 46 to 89 °. In the case where there are two types of shift angles, the shift angle is defined by the smaller shift angle.

Regarding the shift angle, in the pixel patterns 12 (pixel patterns 13) arranged in a matrix with matrix regularity, at least one of the shift angles in the row direction or the column direction in the matrix regularity is 1 to 44 °. ,
Preferably, it is 5 to 40 °, and most preferably, 15 to 30 °.

Thus, according to the liquid crystal display device 14,
When the dot pattern 15 and the pixel pattern 12 are overlapped, or when the dot pattern 15 and the pixel pattern 13 are overlapped, the dot pattern 15 is not parallel to the X direction and / or the Y direction. As a result of the patterning, interference did not occur, and thereby moiré fringes did not occur.

In the other liquid crystal display device shown in FIGS. 5 and 6, a random (disordered) dot pattern 16 having no regularity is formed, and the arrangement angle and pitch of the dot pattern are all randomly set. You have set. Even in such a configuration, when the dot pattern 16 is superposed on the pixel pattern 12 or 13, the dot pattern 16 is non-parallel in both the X and Y directions, so that interference does not occur and moire fringes do not occur.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements may be made without departing from the scope of the present invention. For example, the dot shape of the dot pattern may be various shapes such as an ellipse, a rectangle, and a star, in addition to the circle. In addition to the light diffusing plate 9, the dot pattern may be formed near the light guide plate 5, the light reflecting plate 8, or the light source 6 of the lens sheet.

[0024]

As described above, according to the liquid crystal display device of the present invention, the vicinity of the long light source on any one of the light guide plate, the light scattering member and the light reflection member provided in the illumination device (backlight). The light-shielding layer formed along the longitudinal direction is formed of a dot-shaped aggregate having an occupied area larger as it is closer to the long light source, and the dot-shaped aggregate of the light-shielding layer is formed in the row direction or the predetermined matrix regularity. By arranging dots at a shift angle of 1 to 44 ° with respect to at least one in the column direction or forming a random dot group, optical interference (moire fringes) occurs between the pixel group and the light shielding layer. As a result, a high-performance liquid crystal display device with improved display image quality can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a liquid crystal display device of the present invention.

FIG. 2 is a plan view showing an arrangement relationship between a light diffusion plate and a light source in the liquid crystal display device of the present invention.

FIG. 3 is a state diagram of a dot pattern in a region B shown in FIG. 2;

FIG. 4 is an explanatory diagram showing a state in which a pixel pattern and a dot pattern according to the present invention are superimposed.

FIG. 5 is a plan view showing an arrangement relationship between a light diffusion plate and a light source in another liquid crystal display device of the present invention.

6 is a state diagram of a dot pattern in a region C shown in FIG.

FIG. 7 is a schematic sectional view of a conventional liquid crystal display device.

FIG. 8 is a plan view showing an arrangement relationship between a light diffusion plate and a light source in a conventional liquid crystal display device.

9 is a state diagram of a dot pattern in a region A shown in FIG.

FIG. 10 is a pixel pattern diagram in a color liquid crystal display device.

FIG. 11 is a pixel pattern diagram in a monochrome liquid crystal display device.

FIG. 12 is an explanatory diagram showing a state in which a pixel pattern and a dot pattern in the related art are superimposed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 14 Liquid crystal display device 2 Liquid crystal display panel 3, 3a Illumination device 5 Light guide plate 6 Light source 8 Light reflection plate 9 Light diffusion plate 10 Lens sheet 11 Light-shielding dot-shaped pattern 12, 13 Pixel pattern 15, 16 Dot-shaped pattern

Claims (1)

[Claims] 1. A light guide plate having a long light source disposed on an end face thereof, a light reflecting member on one main surface, and a large number of pixels on a light scattering member of a lighting device having a light scattering member on the other main surface. A liquid crystal display panel arranged in a matrix with a predetermined matrix regularity is mounted, and formed along a longitudinal direction near a long light source on any surface of the light guide plate, the light scattering member or the light reflection member. The light-shielding layer is a liquid crystal display device in which a dot-like aggregate having an occupied area larger as being closer to a long light source is provided, and the dot-like aggregate of the light-shielding layer is arranged in a row direction in the predetermined matrix regularity. Alternatively, the liquid crystal display device is characterized in that dots are arranged at a shift angle of 1 to 44 ° with respect to at least one of the column directions, or a random dot group is formed.