KR100925330B1 - Method for manufacturing polarizer of lcd - Google Patents

Abstract

The present invention is to prevent the bending of the AG layer of the polarizing plate used in the liquid crystal display device and to reduce the refractive index of the AG layer and the upper protective layer of the polarizing film to prevent external image rubbing, to reduce the contrast ratio and to reduce the sharpness of the image Disclosed is a method of manufacturing a liquid crystal display polarizing plate which can be used. The present invention discloses a step of forming a polarizing layer through a polyvinyl resin through a crosslinking and uniaxial forming process; Bonding a lower passivation layer and an upper passivation layer having a different refractive index value from the lower passivation layer on one side of the polarizing layer; And forming an AG layer having a curvature of a predetermined width and height on the upper protective layer, wherein the AG layer is formed by mixing a binder and SiO ₂ -based curved particles with each other, and they have the same refractive index. It is characterized by.

Here, the refractive index of the AG layer is in the range of 1.2 ~ 1.45, the refractive index of the upper protective layer is characterized in that it has a value in the range of 1.5 ~ 1.65.

Polarizing plate, refractive index, binder, AG layer, protective layer, contrast, lens effect

Description

Liquid crystal display polarizer manufacturing method {METHOD FOR MANUFACTURING POLARIZER OF LCD}

1 is a view for explaining the appearance of scattering reflection and refraction of the external light on the surface of the AG layer of the polarizing plate according to the prior art.

2 is a view for explaining a problem of the polarizing plate of FIG.

3 is a view for explaining the appearance of scattering reflection and refraction of the external light in the AG layer surface and the inside of the polarizing plate to improve the problem of the polarizing plate according to the prior art.

4 is a view for explaining a problem of the polarizing plate of FIG.

5A and 5B are cross-sectional views showing a polarizing plate manufacturing process according to the present invention.

6 is a view for explaining that the light incident from the backlight is not scattered inside the AG layer in the polarizing plate according to the present invention.

7A and 7B are cross-sectional views illustrating a polarizing plate manufacturing process according to another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

21: lower protective layer 22: upper protective layer

23: polarizing film 24: binder

25: curved particles 32: internal reflection layer

The present invention relates to a method of manufacturing a polarizing plate of a liquid crystal display device, and more particularly, light incident by external light and an internal light source of the liquid crystal display device is reduced inside the AG layer of the polarizing plate while reducing distortion of transmitted light due to bending of the AG layer. The present invention relates to a liquid crystal display device polarizing plate manufacturing method capable of preventing scattering in the light emitting device, thereby reducing contrast ratio and reducing image sharpness.

In general, light may be regarded as the sum of two linearly polarized light having a vertical plane of polarization. The plane containing the traveling direction of the light and the electric field is called a polarization plane, and the polarization plane is limited to one plane called linear polarization or planar polarization. In the present invention, a film-like synthetic resin used to extract linear polarization It relates to a method for producing a polarizing film.

A representative example used to extract linearly polarized light from a light beam is a polarizing prism made using a birefringent crystal such as a crystal.

Recently, as liquid crystal displays have been widely used in industry, thin-film polarizers are already commercialized.

Polarizing Plastic Thin Films require polarization such as sunglasses (sun glass) or display devices such as wrist watches, electronic notebooks, notebook computer camcorders, etc., which use liquid crystal displays (hereinafter referred to as LCDs). It is widely used in the field.

The polarizing plate is more useful for maintaining its polarization performance while maintaining its polarization performance. The polarizing plate is a technology-intensive product that requires high light transmittance, ultraviolet absorbency, water resistance, dimensional stability, and abrasion resistance.

Currently, polarized polyvinyl alcohol (hereinafter referred to as PVA) film treated with iodine or dichroic organic dye is used as a polarizing base film, and has excellent transparency and UV absorption, as well as stability and abrasion resistance against dimensions and deformation. There is a commercially available polarizing plast thin film comprising a durable cellulose triacetate film (hereinafter referred to as CTA) as a protective film for protecting the polarizing base film.

In order to bond a polarizing plate (CTA film / PVA film / CTA film) composed of a conventional CTA film and a polarizing PVA film to the front or rear side of a liquid crystal display, an adhesive layer should be formed on the CTA film layer. .

As a pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, a solvent-type pressure-sensitive adhesive such as an oil-based or aqueous acrylic resin is used, but these must evaporate the solvent after adhesion, so a drying chamber must be provided to evaporate and dry the solvent.

In addition, since the adhesive cannot be directly processed between the polarizing plate and the protective film, it must be adhesively applied to the protective film having a release layer, and then adhered to the polarizing plate. There was a problem. In this case, a polyester (polyethylene terephthalate: PET) film is generally used as a protective film.

That is, the CTA film is used as a protective layer of the polarizing PVA film, the release-treated PET film is used as the protective layer of the entire polarizing film coated with the adhesive, and the PET film is removed when the polarizing film is attached to the liquid crystal display device. .

LCDs are used in personal computers and the like, and their demands are rapidly increasing in recent years. The use of LCDs is widening, and recently, they are also used for monitors.

Polarizing plates used in LCDs are, for example, polyvinyl alcohol (hereinafter abbreviated as PVA) dyeing process of dyeing a film with dichroic iodine or dichroic dye, crosslinking process of crosslinking with boric acid or borax, and uniaxial stretching. It dries after a process and is produced by bonding with protective layers, such as a triacetyl cellulose (it abbreviates as TAC hereafter) film. In addition, each process of dyeing, bridge | crosslinking, and extending | stretching does not need to be performed separately, but may be performed simultaneously, and the order of each process may also be arbitrary.

In the polarizing plate of the liquid crystal display device manufactured as described above, the polarizing plate (decomposer) attached to the color filter substrate forms an AG layer to prevent glare from occurring in the polarizing plate by external light.

The present invention is an invention for improving the image quality of the liquid crystal display device by adjusting the characteristics of the external light and the internal light when manufacturing the AG layer, the polarizing film and the protective layer of the polarizing plate.

1 is a view for explaining the appearance that the external light scattered reflection and refraction on the AG layer surface of the polarizing plate according to the prior art.

In general, a liquid crystal display device in which an array substrate in which a plurality of pixel electrodes are arranged in a matrix form and a color filter substrate in which R, G, and B color filters are formed are combined with reflected light of external light (in the case of a reflective liquid crystal display device) or After polarizing the internal light by the polarizing plate, it is passed through the liquid crystal molecules twisted by the electric field to implement an image.

The polarizer is attached to an outer surface of the array substrate and an outer surface of the color filter substrate, respectively, and a backlight for generating the internal light of the liquid crystal display is first incident on a polarizer attached to the outer surface of the array substrate in a predetermined direction. The polarized light is passed through the liquid crystal and then passes through a decomposer (polarizing plate) attached to the outer surface of the color filter substrate.

Although the said decomposer and a polarizer are the same in the point which polarizes light as the same polarizing plate, they are named as above according to the characteristic of the polarized light.

The present invention relates in particular to a polarizer, i.

As shown in FIG. 1, a polarizer attached to an outer surface of a color filter substrate of a liquid crystal display device has a structure in which two upper and lower polymer protective layers 1a and 1b are bonded to each other with a polarizing film 3 interposed therebetween. In addition, an AG layer is formed on an outer surface of the upper polymer protective layer 1a to prevent an external image from shining and anti-glare.

The AG layer layers a binder (4) mixed with the curved particles (5) of SiO ₂ series material on the upper polymer protective layer (1a), the curved particles (5) of the SiO ₂ system The surface of the binder 4 is formed by a constant surface curvature.

Since the refractive indexes of the binder 4 and SiO ₂ , which are mixed adhesives, have the same value, scattering does not occur in the curved particles 5 of the SiO ₂ system by external light coming from the outside.

  The reason why the AG layer is formed on the surface of the polarizing plate is that since the surface of the polarizing plate has a uniform plane, external light incident in a predetermined direction is reflected at a specific angle, causing glare at a specific viewing angle. .

So the bend in the binder 4 By mixing the particles 5, an AG layer having a constant curvature is formed, and thus light coming from the outside is scattered at the surface in accordance with the curvature formed on the surface of the polarizing plate to prevent glare (Anti-Glare).

However, in order to have a high resolution in order to keep up with the increase in size of the liquid crystal display device, high resolution has been developed. The following problems have occurred due to the bending of the AG layer of the polarizer.

 FIG. 2 is a view for explaining a problem of the polarizing plate of FIG. 1. As illustrated, the polarizing plate having an AG layer is an area where the field of view directly meets when the image is attached to an outer surface of the color filter substrate.

In the color filter substrate, R, G, and B color filters are formed in respective regions where a black matrix having a chromium material is formed. When viewing the R, G, and B color pixels formed on the color filter substrate, the bending of the AG layer formed on the polarizing plate has the same effect as the lens, and thus an optical path difference of the internal light is generated.

As described above, the optical path difference of the external light generated by the bending on the AG layer deteriorates the screen display quality in the case of a highly detailed color filter.

As shown on the right side of FIG. 2, the R, G, and B pixels appear distorted or appear to have irregular curvatures, which causes deterioration of the screen quality.

3 is a view for explaining the appearance of scattering reflection and refraction in the AG layer surface and the inside of the polarizing plate to improve the problem of the polarizing plate according to the prior art.

As shown in FIG. 3, in the flat plate as shown in FIG. 1, the structure of the polarizer is improved to prevent distortion (glitting) of the image as shown in FIG. 2 due to the lens effect of the AG layer.

The width of the bend is reduced to reduce the distortion of the internal light caused by the bend difference in the AG layer.

However, reducing the bending of the AG layer reduces the external anti-glare and anti-glare characteristics, so that the high refractive index particles having a higher refractive index than the binder 14 are mixed and scattered inside the AG layer instead of SiO _2, which has been used for forming bends. Allow reflection to be added.

That is, the binder 14 and the high refractive index particles 15 are mixed on the outer surface of the polarizing plate, and the size and density of the high refractive index particles are adjusted to reduce the bending of the AG layer, and to prevent glare. In the high refractive index curved particle 15, scattering reflection occurs twice.

Therefore, while maintaining the function of the polarizing plate for preventing glare it is possible to reduce the lens effect due to the high definition of the color filters.

Although shown in the figure, 11a and 11b which are not described represent upper and lower protective layers made of a polymer, and 13 represents a polarizing film.

However, in the case of the improved polarizer as described above, the image quality is improved by reducing the occurrence of glittering of the R, G, and B color filter layers by the lens effect, but when the internal light is transmitted by the backlight, the AG layer is The scattering in the frontal direction increases the black luminance, the contrast ratio decreases, and the sharpness of the image is reduced.

4 is a view for explaining a problem of the polarizing plate of FIG.

As shown in FIG. 4, the polarizing plate attached to the outside of the color filter substrate of the liquid crystal display device has a structure in which upper and lower polymer protective layers 11a and 11b are bonded to each other with the polarizing film 13 interposed therebetween. On the outer side surface of the protective layer 11a, the AG layer in which the high refractive index curved particle 15 and the binder 14 are mixed is formed.

The scattering occurs twice outside the AG layer and the high refractive index particles 15 by the incidence of external light, thereby preventing glare and reducing the curvature by adjusting the size and density of the high refractive index curved particles 15. Prevents the effect of glittering.

However, the internal light incident from the backlight passes through the liquid crystal layer through the polarizing plate attached to the outer surface of the array substrate and then enters the upper polarizing plate. When the internal light passes through the upper polarizing plate, the incident light enters the AG layer. The light is scattered by the high refractive index curved particles mixed in the AG layer. There is.

The present invention prevents the glimmering caused by the lens effect caused by the bending of the AG layer of the liquid crystal display device polarizing plate, and also prevents the decrease of contrast due to the scattering of the internal light incident from the backlight and the reduction of the sharpness of the image. An object of the present invention is to provide a method for manufacturing a liquid crystal display polarizing plate capable of improving image quality of a liquid crystal display.

Liquid crystal display device polarizing plate manufacturing method according to the present invention for achieving the above object,
Forming a polarizing layer through the polyvinyl resin through a crosslinking and uniaxial forming process;
Bonding a lower passivation layer and an upper passivation layer having a different refractive index value from the lower passivation layer on one side of the polarizing layer; And
Forming an AG layer having a curvature of a predetermined width and height on the upper protective layer;

The AG layer is formed by mixing a binder and the curved particles of SiO ₂ series with each other, and they have the same refractive index.

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Here, the refractive index of the AG layer is in the range of 1.2 ~ 1.45, the refractive index of the upper protective layer is characterized in that it has a value in the range of 1.5 ~ 1.65.

And the refractive index value of the upper protective layer is always greater than the refractive index of the AG layer, the width of the bend formed in the AG layer is 35 ~ 65㎛, the height of the bend formed in the AG layer is 0.2 ~ 0.4㎛, the upper protection The light source applied inside the liquid crystal display in the layer and the AG layer is characterized in that no scattering occurs.

In addition, the liquid crystal display device manufacturing method according to another embodiment of the present invention,
Forming a polarizing layer through the polyvinyl resin through a crosslinking and uniaxial forming process;
Bonding upper and lower protective layers with the polarizing layer interposed therebetween;
Forming an internal reflective layer having a constant refractive index on the upper protective layer; And
Forming an AG layer having a curvature of a predetermined width and height on the inner reflective layer;

The AG layer is formed by mixing a binder and the curved particles of SiO ₂ series with each other, and they have the same refractive index.

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Here, the refractive index of the AG layer is in the range of 1.5 ~ 1.65, the refractive index of the inner reflective layer is characterized in that it has a value in the range of 1.2 ~ 1.45.

And the refractive index value of the inner reflective layer is always smaller than the refractive index of the AG layer, the width of the bend formed in the AG layer is 35 ~ 65㎛, the height of the bend formed in the AG layer is 0.2 ~ 0.4㎛, and The light source applied inside the liquid crystal display in the AG layer is characterized in that no scattering occurs.

According to the present invention, the upper polymer protective layer has a different refractive index than that of the AG layer while reducing the bending of the AG layer, thereby preventing the lens effect from glittering, so that external light is reflected on the AG layer surface and the AG layer and the upper polymer protective layer. The scattering was made to have a sufficient external phase anti-impregnation effect. At the same time, since the internal light incident from the backlight is not scattered in the AG layer, there is an advantage in that the contrast ratio can be reduced and the sharpness of the image can be prevented.

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

5A and 5B are cross-sectional views showing a polarizing plate manufacturing process according to the present invention.

As illustrated in FIG. 5A, the polarizing plates are bonded to the upper and lower protective layers 22 and 21 with a polarizing film 23 for polarizing light incident from the outside in a predetermined direction. In this case, the lower protective layer 21 attached to the lower portion of the polarizing film 23 uses a polymer as in the prior art, but the upper protective layer 22 attached to the upper portion of the polarizing film 23 is the upper protective layer. A protective layer is formed using a material having a refractive index in a predetermined range based on the refractive index of the AG layer layered on (22).                     

In addition, an AG layer for preventing glare is formed on the upper protective layer 22 in a polarizing plate in which two upper and lower protective layers 22 and 21 are bonded with the polarizing film 23 interposed therebetween.

As shown in Figure 5b, the AG layer is to form a mixture of binder (24) and the curved particles 25 of a material of SiO ₂ type, wherein the curved particle 25 to the SiO ₂ material, the AG layer This is to prevent glare caused by external light by forming a constant bend in the.

In the present invention, the SiO ₂ curved particles 25 are used in the same manner as in the related art, but the size and mixing density of the particles are adjusted to reduce the step of bending.

This has the effect of reducing the glittering effect (FIG. 2) in which the internal light passing through the high-definition color filter layer is distorted by the lens effect caused by the bending of the AG layer.

The width | variety of the curvature formed in the said AG layer in this invention is 35-60 micrometers, and height is about 0.2-0.4 micrometers.

The refractive index n ₁ of the binder 24 and the SiO ₂ particles constituting the AG layer has a value equal to 1.2 to 1.45.

And while the refractive index (n ₂ ) of the upper protective layer 22 formed on the polarizing film 23 has a value larger than the refractive index of the AG layer, the range is to have a value of 1.5 ~ 1.65.

As described above, the refractive index of the binder forming the AG layer and the particles are the same, and the refractive index of the upper protective layer 22 bonded to the polarizing film 23 is larger than the refractive index of the AG layer, so that light applied from the outside is applied to the AG. Scattered reflection is primarily at the surface of the layer, and secondly scattered reflection at the upper protective layer 22 has the effect of preventing glare.

The anti-glare effect by external light is reduced while reducing the bending of the AG layer in order to reduce the glittering, because secondary scattering / reflection is performed in the polarizer upper protective layer 22 having a different refractive index from the AG layer.

6 is a view for explaining the light scattering does not occur by the internal light source generated in the backlight of the polarizing plate according to the present invention.

As shown in FIG. 6, the internal light incident from the backlight of the liquid crystal display is polarized in the lower polarizer attached to the outer surface of the array substrate of the liquid crystal display panel, but not passed through the liquid crystal layer. Then incident on the upper polarizer.

The internal light passing through the polarizing film 23 and the upper protective layer 22 of the upper polarizing plate proceeds without scattering in the AG layer and exits to the outside.

Therefore, without the problem of the glittering by a lens effect like the polarizing plate which used the high refractive index particle conventionally, the fall of contrast ratio which is a problem of the polarizing plate using the conventional high refractive index particle, and the fall of image sharpness do not arise.

7A and 7B are cross-sectional views illustrating a polarizing plate manufacturing process according to another embodiment of the present invention.

As shown in FIG. 7A, upper and lower protective layers 31a and 31b are bonded to each other with a polarizing film 33 for polarizing incident light in a predetermined direction. Before forming the AG layer on the upper protective layer 31a, an inner reflective layer 32 having a refractive index different from that of the AG layer is formed to scatter external light.

That is, the internal reflective layer 32 having a refractive index n ₂ is formed on the upper protective layer 31a, and the refractive index of the internal reflective layer 32 is as described with reference to FIGS. 5A and 5B. It has a range of refractive index values based on the refractive index of the AG layer to be formed on the).

When the internal reflection layer 32 is formed on the upper protective layer 31a to scatter external incident light, as illustrated in FIG. 7B, an AG layer in which the binder 34 and the SiO ₂ curved particles 35 are mixed. To form.

The refractive index n ₁ of the binder 34 and the curved particles 35 SiO ₂ constituting the AG layer has the same value, and the value has a range of 1.5 to 1.65.

The refractive index n ₂ of the inner reflective layer 32 is always smaller than the refractive index of the AG layer, while the range is 1.2 to 1.45.

The width of the bend formed in the AG layer is 35 ~ 60㎛, the height is mixed with the binder 34 to reduce the content of SiO ₂ than conventionally to have about 0.2 ~ 0.4㎛.

As described in detail above, the present invention lowers the bending of the AG layer to improve the problem of glittering due to the lens effect, and by changing the refractive index of the upper protective layer protecting the polarizing layer from the refractive index of the binder of the AG layer, By allowing the external light to go through two scattering processes, it has a sufficient external image shine prevention effect.

In addition, since light generated in the backlight and incident from the inside is not scattered, the contrast ratio and the sharpness of the image may be prevented.

In addition, by forming the internal reflection layer on the upper protective layer of the polarizing layer to have the same effect as above.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

Claims (18)

Forming a polarizing layer through the polyvinyl resin through a crosslinking and uniaxial forming process; Bonding a lower passivation layer and an upper passivation layer having a different refractive index value from the lower passivation layer on one side of the polarizing layer; And Forming an AG layer having a curvature of a predetermined width and height on the upper protective layer; The AG layer is formed by mixing a binder and SiO ₂ series of bent particles with each other, they have the same refractive index manufacturing method of a liquid crystal display device polarizing plate. delete delete The method of claim 1, The refractive index of the AG layer is a method of manufacturing a liquid crystal display device polarizing plate, characterized in that in the range of 1.2 ~ 1.45. The method of claim 1, The refractive index of the upper protective layer is a liquid crystal display device polarizing plate manufacturing method characterized in that it has a range value of 1.5 ~ 1.65. The method of claim 1, The refractive index value of the upper protective layer is always larger than the refractive index of the AG layer. The method of claim 1, The width of the bend formed in the AG layer is a liquid crystal display device polarizing plate manufacturing method, characterized in that 35 ~ 65㎛. The method of claim 1, The height of the bend formed in the AG layer is a liquid crystal display device polarizing plate manufacturing method, characterized in that 0.2 ~ 0.4㎛. The method of claim 1, The light source applied in the liquid crystal display in the upper protective layer and the AG layer does not cause scattering. Forming a polarizing layer through the polyvinyl resin through a crosslinking and uniaxial forming process; Bonding upper and lower protective layers with the polarizing layer interposed therebetween; Forming an internal reflective layer having a constant refractive index on the upper protective layer; And Forming an AG layer having a curvature of a predetermined width and height on the inner reflective layer; The AG layer is formed by mixing a binder and SiO ₂ series of bent particles with each other, they have the same refractive index manufacturing method of a liquid crystal display device polarizing plate. delete delete The method of claim 10, The refractive index of the AG layer is a liquid crystal display device polarizing plate characterized in that the range of 1.5 ~ 1.65. The method of claim 10, And a refractive index of the internal reflective layer has a range of 1.2 to 1.45. The method of claim 10, The refractive index value of the internal reflective layer is always smaller than the refractive index of the AG layer. The method of claim 10, The width of the bend formed in the AG layer is a liquid crystal display device polarizing plate manufacturing method, characterized in that 35 ~ 65㎛. The method of claim 10, The height of the bend formed in the AG layer is a liquid crystal display device polarizing plate manufacturing method, characterized in that 0.2 ~ 0.4㎛. The method of claim 10, The light source applied in the liquid crystal display in the internal reflection layer and the AG layer does not cause scattering.

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