JP2003279985A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To convert the color tone of the light emitted from a backlight without increasing the number of members or member costs and to achieve miniaturization and cost reduction. <P>SOLUTION: A liquid crystal display device is composed of a liquid crystal display part 11 and an LED backlight 12. The LED backlight 12 is provided with a light guide plate 13, and an LED 14 is arranged on the side face of the light guide plate 13. A reflection sheet 18 is provided on one principal surface of the light guide plate 13, and a light diffusion plate 16 for uniformly diffusing light emitted from the surface of the light guide plate 13 is further arranged. A coloring layer 19 including a pigment is provided on the surface of the light diffusion plate 16. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a liquid crystal display device having a backlight.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device is provided with a so-called backlight for illuminating a display section for displaying an image. Then, in response to the market demand for low power consumption in the liquid crystal market in recent years, a light emitting diode capable of significantly reducing the electric power in the light source of this backlight as compared with the conventional cold cathode fluorescent lamp (hereinafter, this light emitting diode is abbreviated as LED). The liquid crystal display device which mounted is emerging. In particular, most of the backlights of small liquid crystal panels for mobile phones and the like currently employ LED backlights.

A conventional LED backlight type liquid crystal display device will be described with reference to the drawings. FIG. 2 is a schematic sectional view of this device.

The LED backlight type liquid crystal display device protects the liquid crystal display section 11 for displaying an image, the LED backlight 12 for emitting light to the liquid crystal display section 11, and the liquid crystal display section 11 and the LED backlight 12. And bezel 10 for holding and holding.

Liquid crystal display section 11 and LED backlight 12
And are arranged so as to be parallel to each other on the display surface. And according to the LED backlight 12,
A transparent light guide plate 13 made of synthetic resin is provided, and LEDs 14 are arranged so as to face the side surfaces of the light guide plate 13. Further, a reflection sheet 18 made of a light-scattering resin or the like is provided on one main surface of the light guide plate 13, light emitted from the LEDs 14 enters the light guide plate 13, and the reflection sheet 18 causes the liquid crystal display unit 11 to display. The light is emitted toward it.

The LED 14 is fixed by a reflector 15, and the reflector 15 reflects the light traveling from the LED 14 toward the opposite side of the light guide plate 13 and the light guide plate 13 is reflected.
It is provided to guide inside.

Further, a light diffusing plate 16 for diffusing the emitted light is provided on the light emitting surface of the light guide plate 13, and a lens sheet 17 for converging the diffusing light on the light diffusing plate 16 is provided. 1 or 2 are arranged.

However, according to the liquid crystal display device having the above-described structure, the emission color of the LED cannot be freely changed, and thus the emitted light of the LED backlight cannot be set to a desired chromaticity value. was there.

In order to solve this problem, a technique of providing a colored sheet has been proposed (Japanese Patent Laid-Open No. 1996-1462).
No. 28).

This technique will be described with reference to FIG. The figure is a schematic sectional view of a liquid crystal display device. The same parts as those of the liquid crystal display device shown in FIG. 2 are designated by the same reference numerals.

According to this liquid crystal display device, the coloring sheet 20 is stacked on the diffusion plate 16.

As described above, the light transmitted through the diffuser plate 16 passes through the coloring sheet 20 to be colored, whereby the color tone of the light emitted from the LED backlight 12 can be converted.

[0013]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
As proposed in Japanese Patent Laid-Open No. 996-146228, the liquid crystal display device provided with the coloring sheet has a configuration in which the coloring sheet is further added, which leads to an increase in the number of members and the cost of the member. The total thickness of the LED backlight increased by the thickness of the coloring sheet.

Therefore, particularly in recent years, it has not been possible to meet the strict market demand for thinning and lightening, and in the small liquid crystal module market, even if the thickness is increased by one coloring sheet, it may lead to defects. It's by no means unusual.

As a result of intensive research in view of the above circumstances, the present invention has been accomplished by creatively devising various coloring techniques by coloring the light diffusing member itself.

Therefore, the object of the present invention has been completed in view of the above findings, and the object is a liquid crystal display capable of converting the color tone of the light emitted from the backlight without increasing the number of members and the cost of members. To provide a device.

Another object of the present invention is to provide a liquid crystal display device which has been downsized and reduced in cost.

[0018]

In the liquid crystal display device of the present invention, a light source is arranged on the end surface of a flat or wedge-shaped light guide plate made of a transparent material, and the light from the light source is placed on one main surface of the light guide plate. A backlight having a light-reflecting layer for guiding the light to the light-emitting surface and further having a light-scattering member for diffusing the emitted light on the light-emitting surface, and a liquid crystal display section on the light-diffusing member of the backlight. The light diffusing member is arranged and colored with a pigment.

Another liquid crystal display device of the present invention is characterized in that a synthetic resin material containing a pigment is applied in layers on the surface of the light diffusing member for coloring.

Still another liquid crystal display device of the present invention is characterized in that the synthetic resin material forming the light diffusing member contains a pigment in advance.

Another liquid crystal display device of the present invention is characterized in that a pigment is printed on the surface of the light diffusing member by using a color printer or a color copying machine.

[0022]

DETAILED DESCRIPTION OF THE INVENTION A liquid crystal display device of the present invention will be described below with reference to the drawings.

(Example 1) FIG. 4 is a schematic sectional view of a liquid crystal display device, and the same parts as those of the liquid crystal display device shown in FIGS.

This liquid crystal display device is composed of a liquid crystal display section 11 for displaying an image and an LED backlight 12 arranged in parallel on the back surface side of the liquid crystal display section 11, and if necessary, it is arranged. The bezel 10 protects and holds the liquid crystal display unit 11 and the LED backlight 12.

The liquid crystal display section 11 is formed by bonding two glass substrates patterned as electrodes to each other through an adhesive as a sealing material, enclosing the liquid crystal therein, and cutting it into a predetermined size. . An alignment film is formed on the electrodes, and functional plates such as a color filter, a polarizing plate, a retardation plate, a reflection plate, and a semi-transmission plate are further provided.

The liquid crystal display unit 11 may be a simple matrix type liquid crystal display unit such as TN or STN, or an active type liquid crystal display unit such as TFT.

The LED backlight 12 is provided with a transparent light guide plate 13 made of synthetic resin.
The LED 14 is arranged on the side surface of the. In addition, the light guide plate 13
A reflection sheet 1 made of a light scattering resin or the like on one main surface
8 are provided. The reflection sheet 18 is also arranged on the side surface of the light guide plate 13. The light emitted from the LED 14 enters the light guide plate 13 and is emitted by the reflection sheet 18 toward the liquid crystal display unit 11.

The LED 14 is fixed by a reflector 15, and the reflector 15 reflects the light traveling from the LED 14 to the opposite side of the light guide plate 13, and the light guide plate 13 is reflected.
It is provided to guide inside.

The light guide plate 13 is made of, for example, a transparent acrylic resin, and is molded into a flat plate or a wedge shape by molding.

Then, the light diffusing plate 16 which is the light diffusing member for uniformly diffusing the light emitted from the surface of the light guide plate 13 is arranged. Further, a lens sheet 17 for collecting the diffused light may be stacked on it.

According to the present invention, in the backlight 12 having such a configuration, the surface of the light diffusion plate 16 is coated with a synthetic resin material containing a pigment in a layered manner to be colored,
The light diffusing plate 16 is colored with a pigment.

In order to apply and color the layers as described above, the coloring layer 19 is provided on the surface of the light diffusing plate 16 by spray painting or an air brush.

Thus, according to the liquid crystal display device of the present embodiment, the coloring layer 19 is provided on the surface of the light diffusing plate 16 so as to be integrated, so that a coloring sheet is not used separately as in the conventional case.
By this, without increasing the number of parts and the cost of parts,
The color tone of the light emitted from the backlight could be changed. In addition, it has become a liquid crystal display device that has been downsized and reduced in cost.

(Example 2) FIG. 5 is a schematic sectional view of a liquid crystal display device, and FIG. 6 is an enlarged view of a main part A of the device shown in FIG. The same parts as those of the liquid crystal display device shown in FIG. 4 described above are designated by the same reference numerals.

According to the backlight 12 of this example, the pigment 21 is preliminarily contained in the synthetic resin material forming the light diffusing plate 16 which is the light diffusing member used therein.

In such a structure, the pigment 21 is added to the light diffusion plate 16
The material itself may be kneaded and a molding technique such as injection molding may be used.

Thus, according to the liquid crystal display device of this example, the light diffusing plate 16 itself is colored, so that the conventional
It was possible to change the color tone of the light emitted from the backlight without using a separate coloring sheet and similarly increasing the number of members and the cost of members. In addition, it has become a liquid crystal display device that has been downsized and reduced in cost.

(Example 3) The liquid crystal display device of this example is a further improvement of each of the liquid crystal display devices of (Example 1) and (Example 2) described above.

According to the liquid crystal display device shown in (Example 1), it is difficult to make the coating film thickness of the colored layer 19 uniform when the colored layer 19 is provided and integrated on the surface of the light diffusion plate 16. Therefore, due to the variation in film thickness,
Color unevenness may occur on the backlight.

Moreover, when the light diffusing plate 16 is attached to the light guide plate 13 or when the light guide plate 13 is incorporated into the backlight 12, the coating film surface of the coloring layer 19 may be rubbed against other members, twisting of the light diffusing plate itself, or the like. May be peeled off, and the debris may be visible on the liquid crystal screen, degrading the display quality.

Further, according to the liquid crystal display device shown in (Example 2), it is difficult to uniformly disperse the pigment 21 in the diffusion plate material, which may cause coloring unevenness. In addition, the work of setting the content of the pigment 21 and the mixing work for obtaining a desired color require delicate adjustment, which is a very difficult work, and a large amount of experimentation and material amount are required to obtain a desired coloring state. It is necessary, which increases the unit price of the diffuser plate. Moreover, it can be said that it is difficult to easily change the color of the diffuser plate once completed.

Therefore, the liquid crystal display device of this example is an improved type of liquid crystal display device which can solve such problems, and this device is shown in FIG.

FIG. 1 is a schematic sectional view of a liquid crystal display device.
The same parts as those of the liquid crystal display devices of (Example 1) and (Example 2) shown in FIGS. 4 and 5 are designated by the same reference numerals.

According to this example, the coloring layer 19 is formed by printing the pigment on the surface of the light diffusion plate 16 which is the light diffusion member using a color printer or a color copying machine.
The light diffusing plate 16 is colored with a pigment.

The coloring layer 19 is thus provided by using a general-purpose color printer or color copying machine, and a specific method will be described below.

The color of the colored layer 19 to be printed on the light diffusing plate 16 is set on a personal computer connected to a color printer or a color copying machine by using commercially available image processing software (eg Adobe Photoshop etc.).

The print color can be freely set on the image processing software, and a desired color can be arbitrarily set.
Further, it is possible to perform trial printing using paper before actually printing the colored layer 19 on the light diffusion plate 16. It is possible to easily change the color setting of the colored layer 19 again by judging the print color condition of the test printing.

Furthermore, an example of image processing software is given.
For Adobe Photoshop, color transparency (0-100
%) Can be set arbitrarily.

This transparency can be explained by expressing the degree of shading of the printing color and replacing it with the degree of the thickness of the printed film.

For example, when the printed film thickness seems to be too thick when the transparency is 40%, the printed density can be made light and the printed film thickness can be made thin by setting the transparency to 80%. In this way, the degree of color tone conversion when the light emitted from the light guide plate 13 passes through the diffusion plate 16 can be adjusted.

As described above, the characteristics of the image processing software are effectively used, the trial printing and the color setting are changed several times, and the final color of the colored layer 19 is determined. After the desired color of the colored layer 19 is obtained, the required number of light diffusion plates 16 may be continuously printed thereafter. In recent years, due to the improvement in printing processing speed of a general-purpose color printer or a color copying machine, mass production can be easily performed by using this method.

Moreover, the colored layer 19 according to the present invention adheres to the surface of the diffuser plate more firmly than in the case of the coating method as shown in (Example 1), which eliminates the problem of dust due to ink peeling or the like. It was

Further, as compared with the case where the pigment is kneaded into the diffuser plate material itself (Example 2), the color setting of the coloring layer is very easy, and the amount of experiment can be suppressed to a very small amount. The cost could be reduced to about 1/10 to 1/15.

In addition, according to the liquid crystal display device of the present embodiment, the coloring layer 19 is provided on the surface of the light diffusing plate 16 so as to be integrated, so that a coloring sheet is not used separately as in the conventional case.
By this, without increasing the number of parts and the cost of parts,
The color tone of the light emitted from the backlight could be changed. In addition, it has become a liquid crystal display device that has been downsized and reduced in cost.

In the case of the colored layer 19 printed on the light diffusing plate 16 as described above, the light emitted from the light guide plate 13 is emitted from the light diffusing plate 1.
When the color tone of the emitted light can be converted when passing through 6, and the desired color tone is yellowish, the yellow colored layer 1
9 or, if it has a blue tint, a blue-based coloring layer 19
May be provided on the surface of the diffusion plate 16.

[0056]

As described above, according to the liquid crystal display device of the present invention, the light source is arranged on the end surface of the flat or wedge-shaped light guide plate made of a transparent material, and the light source is arranged on one main surface of the light guide plate. A light reflecting layer for guiding light to the light emitting surface is formed, and a backlight having a light scattering member for diffusing emitted light on the light emitting surface is further provided, and a pigment is used for the light diffusing member. By coloring, the color tone of the light emitted from the backlight can be converted without increasing the number of members and the cost of members. Moreover, according to this liquid crystal display device, downsizing and cost reduction can be achieved.

[Brief description of drawings]

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

FIG. 2 is a schematic cross-sectional view of a conventional liquid crystal display device.

FIG. 3 is a schematic cross-sectional view of another conventional liquid crystal display device.

FIG. 4 is a schematic cross-sectional view of another liquid crystal display device of the present invention.

FIG. 5 is a schematic cross-sectional view of still another liquid crystal display device of the present invention.

6 is an enlarged view of a main part A of the device shown in FIG.

[Explanation of symbols]

10: bezel 11: Liquid crystal display section 12: LED backlight 13: Light guide plate 14: LED 15: Reflector 16: Diffuser 17: Lens sheet 18: Reflective sheet 19: Colored layer 20: Coloring sheet 21: Pigment

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1335 520 G02F 1/1335 520 // F21Y 101: 02 F21Y 101: 02

Claims (4)

[Claims] 1. A light source is arranged on an end surface of a flat plate or wedge-shaped light guide plate made of a transparent material, and a light reflection layer for guiding light from the light source to a light emission surface is formed on one main surface of the light guide plate. And a liquid crystal display device in which a light scattering member for diffusing the emitted light is further arranged on the light emitting surface and a liquid crystal display unit is arranged on the light diffusing member of the backlight. On the other hand, a liquid crystal display device characterized by being colored with a pigment. 2. The liquid crystal display device according to claim 1, wherein a synthetic resin material containing a pigment is applied in layers on the surface of the light diffusing member for coloring. 3. A synthetic resin material forming the light diffusing member,
The liquid crystal display device according to claim 1, wherein the liquid crystal display device contains a pigment in advance. 4. The liquid crystal display device according to claim 1, wherein a pigment is printed on the surface of the light diffusing member by using a color printer or a color copying machine.