JP3266487B2 - 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 type liquid crystal display device.

[0002]

2. Description of the Related Art In a liquid crystal display device of a time division system or an active matrix system, a backlight system is employed in order to improve the visibility, and in recent years, there has been a demand for thinner, lighter and lower power consumption. The edge light method has become mainstream according to the requirements.

FIGS. 8 and 9 show an example of a one-light type edge light type liquid crystal display device 1. FIG. 8 is a sectional view orthogonal to the fluorescent lamp 2, and FIG. FIG.

In the liquid crystal display device 1, reference numeral 3 denotes a liquid crystal panel, 4 denotes a backlight, and 5 denotes a housing for holding and fixing the liquid crystal panel 3 and the backlight 4 inside. There is an opening a on the display surface side of the housing 5, whereas the display area b of the liquid crystal panel 3 is small. Further, the light emitting area c of the backlight 4 has substantially the same planar shape corresponding to the display area b of the liquid crystal panel 3.

[0005] The backlight 4 has a light guide plate 6, an elongated fluorescent lamp 2 is provided on one end face of the light guide plate 6, and a light reflection sheet 7 is provided on the other three end faces. Then, the light reflecting plate 8 is surrounded by the fluorescent lamp 2, a light reflecting sheet 9 is provided on one main surface of the light guide plate 6, and a light diffusing plate 10 and a lens sheet 11 are sequentially arranged on the other main surface side. ing. The light reflecting sheet 7 and the light reflecting sheet 9 are made of a white PET film or a polyester film, and irregularly reflect the light inside the light guide plate 6, thereby emitting light from the light emitting area c of the backlight 4.
Moreover, a dot-like pattern in which white ink is printed is formed between the light-reflecting sheet 9 and the one main surface of the light guide plate 6 to enhance the scattering effect.

According to the liquid crystal display device 1 having the above-described structure, the irradiation light of the fluorescent lamp 2 is directly projected on the light guide plate 6, or a part of the irradiation light is reflected by the light reflection plate 8, and the reflected light is reflected. Is also guided to the light guide plate 6, and the light introduced into the light guide plate 6 irradiates the liquid crystal panel 3 with light through the light diffusion plate 10 while being reflected by the light reflection sheets 7 and 9 and the dot pattern.

[0007]

However, according to the liquid crystal display device 1, since the display area "b" of the liquid crystal panel 3 is smaller than the opening "a" of the housing 5, external light is prevented from passing through the opening. a, the light enters the housing 5 and diffusely reflects. On the other hand, since the liquid crystal panel 3 has a structure in which two glass substrates are bonded to each other, the liquid crystal panel 3 enters the backlight 4 through the glass substrates, thereby emitting light. There is a problem that light is not uniformly irradiated over the surface of the region c.

Further, since the light reflecting sheet 7 and the light reflecting sheet 9 are made of a white PET film or a polyester film, complete light shielding properties cannot be obtained. The light passes through the reflection sheets 7 and 9 and is not evenly irradiated with light over the surface of the light emitting region c.

The light introduced from the fluorescent lamp 2 into the light guide plate 6 is reflected by the light reflecting sheets 7 and 9 while a part of the light passes through the light reflecting sheets 7 and 9 when the light is emitted. There is a problem that light is diffusely reflected in the housing 5 and leaks through the glass substrate of the liquid crystal panel 3, thereby lowering the luminance in the light emitting area c of the backlight 4.

Accordingly, an object of the present invention is to provide a high-performance backlight-type liquid crystal display device in which light is uniformly radiated over the surface of the light-emitting region of the backlight and the brightness is increased.

[0011]

According to the liquid crystal display device of the present invention, a light guide plate provided with a long light source on one end face is provided with a light reflection means made of a white PET film or a polyester film on one main face, and the other main light guide is provided. A light diffusing plate is arranged on the surface side, and the long light source is further covered with a reflecting member, and the irradiation light of the long light source is introduced into the light guide plate while being reflected by the reflecting member. A backlight configured to emit more light and a liquid crystal panel disposed on a light diffusion plate of the backlight are housed in a housing, and a display area having substantially the same shape as the light emitting area is provided in the liquid crystal panel. ,
In a device configuration in which an opening larger than this display area is provided on the display surface side of the housing, light shielding properties are provided over the end face where the long light source of the light guide plate is not provided and around the light emitting area on the other main surface. A sheet is provided, and the light-shielding sheet is further extended from one main surface of the light guide plate to the housing.

[0012]

[0013]

1 and 2 show a main part of a one-light type edge light type liquid crystal display device 12 according to the present invention. FIG.
FIG. 2 is a sectional view parallel to the fluorescent lamp 2. FIG.
7 are the backlight 1 mounted on the liquid crystal display device 12.
3 and FIG.
3 is a plan view and a right side view, FIG. 5 is a cross-sectional view taken along section line XX in FIG. 3, FIG. 6 is a perspective view of a portion Y in FIG. 3, and FIG. It is an enlarged view. FIG.
And the same parts as those of the liquid crystal display device 1 shown in FIG.

Reference numeral 5 denotes a housing of the liquid crystal display device 12, in which a liquid crystal panel 3 and a flat or wedge-shaped light guide plate 6 made of polymethyl methacrylate (PMMA) are arranged. 6, a light reflecting sheet 9 made of a low-foamed film of white polyester manufactured by Toray Industries, Ltd. is provided on one main surface as the light reflecting means, and PE
A sheet-like light diffusion plate 10 made of T or polycarbonate (PC) is provided, and a fluorescent lamp 2 (a cold-cathode or hot-cathode fluorescent lamp with a 2.6 mm tube diameter) is provided along one short-axis end surface of the light guide plate 6. A light reflecting plate having, on the outer periphery of the fluorescent lamp 2, a polyethylene film whose cross-sectional shape is curved along the longitudinal direction of the fluorescent lamp 2, and the film has a reflecting surface of silver evaporation or aluminum evaporation. 8
Is provided. The light reflecting plate 8 is fixed to the light guide plate 6 with an adhesive tape.

On one main surface of the light guide plate 6, a printing pattern (not shown) containing glass beads obtained by adding titanium oxide exhibiting white or milky white as an adjusting means for increasing the brightness in a planar manner. ) Are formed on almost the entire surface so as to be distributed at a high density. In this print pattern, as the distance from the fluorescent lamp 2 increases, the density of the dot pattern increases. The light reflection sheet 9 is provided below the light reflection sheet 9, and the combination of such a dot-shaped print pattern and the light reflection sheet 9 increases the luminance and increases the uniformity of the luminance.

In addition, between the light diffusing plate 8 and the liquid crystal panel 3, Sumitomo 3M Co., Ltd. product names BEF100, BEF90,
Alternatively, any one of the lens sheets 11 of BEFII 90-50 is interposed to further increase the brightness.

Further, as a characteristic part of the present invention, a light-shielding sheet 14 is provided in the backlight 13 over the end face of the light guide plate 6 where the fluorescent lamps 2 are not provided and around the light emitting area c on the other main face. ing. This light-shielding sheet 1
Reference numeral 4 denotes a light-shielding metal material (e.g., aluminum coated or laminated on a sheet made of polyester or the like, and an excellent light-shielding property is obtained by this laminated structure.
4 is fixed with a double-sided tape 15 as shown in FIG.

According to the liquid crystal display device 12,
The configuration is such that the irradiation light of the fluorescent lamp 2 irradiates the liquid crystal panel 3 with light through the light guide plate 6 and further through the light diffusion plate 8. The light-emitting region c of the light guide plate 6 is defined to have substantially the same shape in dimensions.

Thus, according to the liquid crystal display device 12,
Even when external light enters the housing 5 through the opening a of the housing 5, the light is prevented from being incident on the interior of the backlight 13 by the light-shielding sheet 14, and furthermore, the light introduced into the light guide plate 6 from the fluorescent lamp 2. Is not leaked, thereby uniformly irradiating light over the surface of the light emitting area c of the backlight 13 and improving the luminance.

In the liquid crystal display device 12 having the above structure, when the light-shielding sheet 14 is extended from one main surface of the light guide plate 6 and its end is brought into contact with the surface of the housing 5, the light-emitting area c Irradiation is even more uniform over the surface of the
The brightness of the light emitting area c of the backlight 13 is most improved.

Further, the thickness t1 of the light-shielding sheet 14
Should be set to be equal to or greater than the thickness t2 of the lens sheet 11, and in that case, it is desirable in that light leakage from the end face of the lens sheet 11 can be prevented. For example, when the thickness t2 of the lens sheet 11 formed by stacking two lens sheets is 0.34 to 0.46 mm, the thickness t1 of the light-shielding sheet 14 is 0.1 to 0.2 mm larger than the thickness t2. I'm making it big.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the scope of the present invention.

[0023]

As described above, according to the liquid crystal display device of the present invention, the light-shielding sheet is provided over the end face where the long light source of the light guide plate is not provided and around the light-emitting area on the other main face. Or, by further extending the light-shielding sheet from one main surface of the light guide plate to the housing, light is uniformly irradiated over the surface of the light emitting region of the backlight, and
Brightness can be increased.

Further, according to the present invention, a light-shielding sheet can be provided by the same process in place of the light-reflecting sheet used in the conventional liquid crystal display device. , The number of working processes does not increase,
A high-performance backlight-type liquid crystal display device can be provided without reducing manufacturing efficiency.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view of the liquid crystal display device of the present invention.

FIG. 3 is a plan view of a backlight according to the present invention.

FIG. 4 is a right side view of the backlight according to the present invention.

FIG. 5 is a cross-sectional view of the backlight of FIG. 3 taken along line XX.

FIG. 6 is a perspective view of a portion Y of the backlight in FIG. 3;

FIG. 7 is an enlarged view of a portion Z of the backlight in FIG. 4;

FIG. 8 is a schematic sectional view of a conventional liquid crystal display device.

FIG. 9 is a schematic sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 2 fluorescent lamp 3 liquid crystal panel 5 housing 6 light guide plate 8 light reflection plate 9 light reflection sheet 10 light diffusion plate 11 lens sheet 12 liquid crystal display device 13 backlight 14 light shielding sheet 15 double-sided tape a opening b display area c light emission area

Claims (1)

(57) [Claims] 1. A white PET film or polyester film is provided on one main surface of a light guide plate having a long light source disposed on an end surface.
A light reflecting means is provided by a light source, a light diffusing plate is arranged on the other main surface side, and the long light source is covered with a reflecting member, and the light emitted from the long light source is reflected by the reflecting member to the light guide plate. A backlight, which is introduced and emits light from a light emitting area on the other main surface, and a liquid crystal panel disposed on a light diffusion plate of the backlight are housed in a housing, and the liquid crystal panel has the light emitting area. Table of the substantially display area of the same shape is provided, housing a large opening in comparison with the display region
A liquid crystal display device provided示面side, provided with a light-shielding sheet across the end face of the elongated light source of the light guide plate is not provided and in the light-emitting area around the other main surface, further the shielding
Extend the light sheet from one main surface of the light guide plate to the housing.
The liquid crystal display device, characterized in that was fit.