KR20070082645A - Light diffusing film, manufacturing method thereof and display device having same - Google Patents

Abstract

Disclosed are a light diffusing film, a method of manufacturing the same, and a display device having the same, which can improve display quality. The light diffusion film includes a base film, a light diffusion layer having first beads coated on the top surface of the base film, an antistatic layer having an antistatic agent coated on the bottom surface of the base film, and an adhesion layer having second beads coated on the antistatic layer. Include. Antistatic agents are hydrophilic surfactants. Accordingly, it is possible to prevent moisture permeation and to minimize display point defects of the display device to improve display quality.

Description

LIGHT DIFFUSER FILM, METHOD FOR MANUFACTURING THE SAME AND DISPLAY APPARATUS HAVING THE SAME

1 is a cross-sectional view of a light diffusing film according to an embodiment of the present invention.

2 is a flowchart illustrating a method of manufacturing a light diffusing film according to an embodiment of the present invention.

3 is an exploded perspective view illustrating a display device according to an exemplary embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100: backlight assembly 200: light source

300: light guide plate 400: diffusion sheet

410: base film 420: light diffusion layer

430: antistatic layer 440: adhesion preventing layer

510: reflective sheet 520: brightness enhancement film

700: display device 800: display unit

The present invention relates to a light diffusing film, a manufacturing method thereof, and a display device having the same, and more particularly, to a light diffusing film, a manufacturing method thereof, and a display device having the same, which can improve display quality.

In general, the liquid crystal display is a flat panel display that displays an image using liquid crystal, and is thin, light, and has a low driving voltage and low power consumption.

Since a liquid crystal display device is a non-light emitting device in which a display panel displaying an image does not emit light by itself, it requires a backlight assembly for supplying light to the display panel.

The backlight assembly further includes a light guide plate for guiding light supplied from a light source for generating light toward the display panel, and a light diffusion film positioned on the light guide plate to diffuse the light.

On the surface where the light diffusing film is in contact with the light guide plate, an adhesion preventing layer in which an antistatic agent and beads are mixed is formed. The adhesion preventing layer reduces optical defects caused by the adhesion between the light guide plate and the light diffusing film, and prevents foreign substances such as dust from adhering to the light diffusion film due to the antistatic agent.

The antistatic agent used for the light diffusing film mostly consists of hydrophilic surfactants. When the surfactant comes out of the surface of the light diffusing film by the surrounding moisture and absorbs the moisture, the absorbed moisture causes the light diffusing film and the light guide plate to be in close contact with each other, resulting in a bright spot shape defect.

Therefore, the technical problem of the present invention is to solve such a conventional problem, and an object of the present invention is to prevent light-permeable and to minimize the white point defect of the display device to improve the display quality, a light diffusion film, and a manufacturing method thereof It is to provide a display device having the same.

The light diffusing film according to an aspect of the present invention is a base film, a light diffusing layer having first beads coated on the upper surface of the base film, an antistatic layer having an antistatic agent coated on the lower surface of the base film, the antistatic layer And an anti-stick layer having second beads coated thereon.

The antistatic agent is a hydrophilic surfactant.

In addition, the method of manufacturing a light diffusing film according to an aspect of the present invention comprises the steps of coating a light diffusion layer having a first bead on the upper surface of the base film, coating an antistatic layer having an antistatic agent on the lower surface of the base film, Coating an anti-stick layer having second beads on the antistatic layer.

In addition, the display device according to an aspect of the present invention is a light source for generating light, a light guide plate for guiding light from the light source, a light diffusion film disposed on the light guide plate, the light diffusion film is disposed on the display to display an image And a display panel.

The light diffusion film is an antistatic layer having a base film, a light diffusion layer having first beads coated on an upper surface of the base film, an antistatic layer coated on a lower surface of the base film, and made of a hydrophilic surfactant, and on the antistatic layer And an anti-stick layer having second beads coated thereon.

According to such a light diffusing film, a manufacturing method thereof, and a display device having the same, the lower surface of the light diffusing film has a structure in which an anti-adhesive layer is coated on the antistatic layer twice, thereby preventing moisture permeation and minimizing defects in the white point of the display device. Can improve.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention.

1 is a cross-sectional view of a light diffusing film according to an embodiment of the present invention.

Referring to FIG. 1, the light diffusing film 400 according to an embodiment of the present invention includes a base film 410, a light diffusing layer 420, an antistatic layer 430, and an adhesion preventing layer 440.

The base film 410 is made of a transparent material for transmitting light. For example, the base film 410 is formed of polyethylene terephthalate (PET) material.

The light diffusing layer 420 is coated on the upper surface of the base film 410, and scatters and refracts incident light so as to spread evenly over the entire surface.

The light diffusion layer 420 includes first beads 422 having a fine bead shape and a first coating layer 424 for fixing the first beads.

The first beads 422 are irregularly distributed on the top surface of the base film 410, and have a particle size of about 5 μm to about 20 μm. The light diffusion layer 420 is a layer in which the first beads 422 having a particle size of about 5 μm to about 20 μm are mixed, and exhibit light diffusion characteristics by surface curvature of the particles.

As the first beads 422, transparent particles or white particles formed of polymethyl methacrylate (PMMA), which is an acrylic material, may be used.

The first coating layer 424 of the light diffusion layer 420 is transparent and fixes the first beads 422 to the top surface of the base film 410. For example, the first coating film 424 is made of a thermosetting resin or an ultraviolet curable resin cured by heat or ultraviolet rays.

The antistatic layer 430 is coated on the lower surface of the base film 410 and includes an antistatic agent and a binder resin.

The antistatic agent lowers the surface resistance of the light diffusing film 400 to prevent foreign matter from being mixed due to static electricity in the assembling process of the display device 700 (see FIG. 3) using the light diffusing film 400.

Surfactant is used as said antistatic agent. The surfactant is a hydrophilic material to absorb the moisture in the air to reduce the surface resistance of the light diffusion film 400 to prevent the charging phenomenon that causes the generation of static electricity.

The binder resin fixes the antistatic agent to the bottom surface of the base film 410. For example, the binder resin is composed of a thermosetting resin or an ultraviolet curable resin cured by heat or ultraviolet rays.

The adhesion preventing layer 440 is formed on the bottom surface of the base film 410 in contact with the light guide plate 300 in order to prevent adhesion between the light diffusion film 400 and the light guide plate 300 (see FIG. 3).

The adhesion preventing layer 440 is coated on the antistatic layer 430, and is formed of the second beads 442 and the second coating layer 444 for fixing the fine beads. .

The second beads 442 are irregularly distributed in the adhesion preventing layer 440 and are formed of polymethyl methacrylate (PMMA), which is an acrylic material. Alternatively, the second beads 442 may be formed of a nylon material having a lower hardness than the acrylic material.

If the size of the second beads 442 is too small, the ability to prevent adhesion may be reduced. If the size of the second beads 442 is too large, the light guide plate 300 may be scratched. Accordingly, the size of the second beads 442 preferably has a particle size of about 3 μm to about 5 μm to prevent adhesion and at the same time to prevent scratches of the light guide plate 300.

The second coating layer 444 fixes the second beads 442 on the antistatic layer 430. For example, the second coating film 444 is made of a thermosetting resin or an ultraviolet curable resin cured by heat or ultraviolet rays.

2 is a flowchart illustrating a method of manufacturing a light diffusing film according to an embodiment of the present invention.

1 and 2, the light diffusion layer 420 having the first beads 422 on the top surface of the base film 410 to manufacture the light diffusion film 400 according to an embodiment of the present invention. Coating (S10). In addition, an antistatic layer 430 having an antistatic agent is coated on the lower surface of the base film 410 (S20), and the anti-stick layer 440 having second beads 442 is coated on the antistatic layer 430. (S30).

In addition, the antistatic layer 430 and the adhesion preventing layer 440 may be first coated on the lower surface of the base film 410, and the light diffusion layer 420 may be coated on the upper surface of the base film 410.

The antistatic agent included in the antistatic layer 430 is a hydrophilic surfactant.

<Table 1-Surface resistance before and after high reliability test>

I'm after Comparative example 3.2E10 Ω 6.7E8 Ω Example 1.1E10 Ω 3.5E10 Ω

Table 1 is a result of measuring the surface resistance of the light diffusion film before and after the test of high reliability conditions (85 ° C / 85% 120hr).

The comparative example uses a method of coating by mixing the second beads and the antistatic agent on the lower surface of the light diffusing film. In the course of the high reliability test, the surfactant is released to the coating surface by moisture, and absorbs moisture excessively. The absorbed moisture causes the surface resistance of the light-diffusion film to change significantly from 3.2E10 Ω to 6.7E8 Ω before and after the high reliability test.

In an embodiment, an antistatic layer 430 having an antistatic agent is coated on a lower surface of the light diffusion film 400 (S20), and the anti-adhesion layer 440 having second beads 442 is disposed on the antistatic layer 430. By coating (S30), the lower surface of the light diffusing film 400 has a structure that is double coated.

Since the adhesion preventing layer 440 covers the surface of the antistatic layer 430, the surfactant is prevented from coming out of the surface of the light diffusion film 400 by moisture in the process of undergoing the high reliability test, It can prevent excessive absorption of moisture. Therefore, the surface resistance of the light diffusion film 400 is hardly changed before and after the high reliability test from 1.1E10 Ω to 3.5E10 Ω.

That is, although the surface resistance of the light-diffusion film of the comparative example changes before and after a test, the surface resistance of the light-diffusion film 400 of an Example does not change before and after a test.

3 is an exploded perspective view illustrating a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the display apparatus 700 according to an exemplary embodiment of the present invention may include a backlight assembly 100 for supplying light and a display unit 800 for displaying an image using light supplied from the backlight assembly 100. ).

The backlight assembly 100 includes a light source 200 for generating light, a light guide plate 300 for guiding light generated from the light source 200, and a light diffusion film 400 disposed on the light guide plate 300.

One or more light sources 200 are disposed adjacent to one side of the light guide plate 300 to generate light. For example, the light source 200 is made of a light emitting diode that generates white light.

The light guide plate 300 guides a traveling path of light incident from the light source 200, and changes the light in the form of a point light source to the light in the form of a surface light source.

The light guide plate 300 is made of a transparent material to minimize the loss of light. For example, the light guide plate 300 is formed of polymethyl methacrylate (PMMA) material.

Since the light diffusion film 400 has the same configuration as that shown in FIG. 1, detailed description thereof will be omitted.

The display unit 800 includes a display panel 810 for displaying an image, a driving chip 820 for driving the display panel 810, and a flexible circuit board 830 for supplying various control signals to the display panel 810. It includes.

The display panel 810 includes a first substrate 812, a second substrate 814 that is coupled to face the first substrate 812, and a liquid crystal layer interposed between the first substrate 812 and the second substrate 814. (Not shown).

The first substrate 812 is a TFT substrate in which a thin film transistor (TFT), which is a switching element, is formed in a matrix form. A data line and a gate line are respectively connected to the source terminal and the gate terminal of the TFTs, and a pixel electrode made of a transparent conductive material is connected to the drain terminal.

The second substrate 814 is a color filter substrate in which RGB pixels for implementing colors are formed in a thin film form. A common electrode made of a transparent conductive material is formed on the second substrate 814 to face the pixel electrode formed on the first substrate 812.

The driving chip 820 is formed on the first substrate 812, and generates a driving signal for driving the display panel 810 in response to a control signal applied through the flexible circuit board 830. The driving signal generated from the driving chip 820 is applied to the gate line and the data line of the first substrate 812 to drive the display panel 810.

The flexible circuit board 830 is connected to one side of the first substrate 812 on which the driving chip 820 is mounted, and includes a timing controller for controlling driving timing of the driving chip 820, a memory for storing data signals, and the like. It includes. For example, the flexible circuit board 830 is electrically connected to the first substrate 812 through an anisotropic conductive film (ACF).

According to such a light diffusing film, a method of manufacturing the same, and a display device having the same, due to the double coating structure in which the antistatic layer covers the surface of the antistatic layer, the surfactant included in the antistatic layer is coated with moisture in an external environment of high temperature and high humidity. Prevent it from coming off the surface.

 In addition, it is possible to prevent moisture permeation into the light diffusion film, to minimize white point defects due to the adhesion of the light diffusion film and the light guide plate when water is excessively absorbed, and improve display quality.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (8)

Base film; A light diffusion layer having first beads coated on an upper surface of the base film; An antistatic layer having an antistatic agent coated on a lower surface of the base film; And A light diffusion film comprising an adhesion layer having second beads coated on the antistatic layer. The light diffusing film of claim 1, wherein the antistatic agent is a hydrophilic surfactant. The light diffusing film of claim 2, wherein the first beads have a size of 5 μm to 20 μm, and the second beads have a size of 5 μm or less. The light diffusing film of claim 1, wherein the base film is formed of polyethylene terephthalate (PET) material. The light diffusing film of claim 1, wherein the first and second beads are formed of a polymethyl methacrylate (PMMA) material. Coating a light diffusing layer having first beads on the top surface of the base film; Coating an antistatic layer having an antistatic agent on a lower surface of the base film; And A method of manufacturing a light diffusing film comprising coating an adhesion layer having second beads on the antistatic layer. The method of claim 6, wherein the antistatic agent is a hydrophilic surfactant. A light source for generating light; A light guide plate for guiding light from the light source; A light diffusing film disposed on the light guide plate; And A display panel disposed on the light diffusion film to display an image; The light diffusion film is Base film; A light diffusion layer having first beads coated on an upper surface of the base film; An antistatic layer coated on a lower surface of the base film and having an antistatic agent made of a hydrophilic surfactant; And And an anti-stick layer having second beads coated on the antistatic layer.

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