KR20100048187A - Liquid crystal display - Google Patents

Abstract

PURPOSE: A liquid crystal display is provided to not apply limit to a polarization axis of polarization sunglasses. CONSTITUTION: A liquid crystal panel(710) displays an image. A composite polarizing plate(724) is arranged on the liquid crystal panel. The composite polarizing plate polarizes light emitted from the liquid crystal panel. The composite polarizing plate comprises a base layer(310), a polarizer layer(320), a phase difference layer(330) and the first layer(340).

Description

Liquid crystal display

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device which may not be restricted by the polarization axis of polarized sunglasses.

The liquid crystal display device includes a liquid crystal panel for displaying an image, a first polarizing plate disposed under the liquid crystal panel, a second polarizing plate disposed over the liquid crystal panel, and a backlight unit for supplying light to the liquid crystal panel.

The liquid crystal panel includes a first substrate on which a field generating electrode such as a pixel electrode and a common electrode are formed, a second substrate, and a liquid crystal molecular layer interposed therebetween. A voltage is applied to the field generating electrode to generate an electric field in the liquid crystal molecule layer, thereby determining the orientation of the liquid crystal molecules to control the polarization of the incident light to display an image. The liquid crystal panel is composed of a non-light emitting device that does not emit light by itself.

The first polarizer polarizes light incident on the liquid crystal panel, and the second polarizer polarizes light emitted from the liquid crystal panel. The first polarizing plate and the second polarizing plate are each made of poly vinyl alcohol (PVA), and include a polarizer layer having polarization axes in directions perpendicular to each other.

The backlight unit supplies light to the liquid crystal panel composed of non-light emitting elements.

In such a liquid crystal display device, polarized sunglasses have been recently used to remove components that are diffusely reflected from surrounding objects so that the user can see a clear image by receiving only the direct light component of the object that the user wants to see.

However, when the polarization axis of the polarized sunglasses and the absorption axis of the polarizer layer included in the second polarizing plate of the liquid crystal display are similar, the user cannot see an image displayed on the screen of the liquid crystal display.

Accordingly, when manufacturing the liquid crystal display device, considering the polarization axis of the polarized sunglasses, design restrictions occur. In addition, if the liquid crystal display device is designed in accordance with the polarization axis of the polarized sunglasses, for example, the light transmission characteristics of the liquid crystal display device may be inferior and display quality may be degraded.

Accordingly, an object of the present invention is to provide a liquid crystal display device which may not be restricted by the polarization axis of the polarized sunglasses.

Problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The liquid crystal display device according to the exemplary embodiment of the present invention for achieving the above object includes a liquid crystal panel displaying an image, and a composite polarizing plate disposed on the liquid crystal panel and polarizing light emitted from the liquid crystal panel. The composite polarizer includes a base layer, a polarizer layer disposed on the base layer and having a polarization axis in the first direction, a phase difference layer disposed on the polarizer layer and retarding the phase of light passing through the polarizer layer, and one surface of the phase difference layer. And a first layer formed on and comprising a sunscreen material.

A liquid crystal display device according to another embodiment of the present invention for achieving the above object is a liquid crystal panel for displaying an image, a base layer, a polarizer layer disposed on the base layer and having a polarization axis in the first direction, and a polarizer layer A composite comprising: a first support disposed on and supporting a polarizer layer; and a PSA layer (pressure sensitive adhesive layer) disposed on the first support; And a cover member attached to the composite polarizing plate via the PSA layer and having a phase retardation characteristic for retarding the phase of light passing through the polarizer layer.

According to still another aspect of the present invention, there is provided a liquid crystal display device including: a first substrate including a pixel electrode, a second substrate including a common electrode having an opening formed in a region corresponding to the pixel electrode, and And a liquid crystal panel including liquid crystal molecules interposed between the first substrate and the second substrate, a first polarizing plate disposed below the liquid crystal panel, and a second polarizing plate disposed above the liquid crystal panel. The first polarizer includes a first polarizer layer having a polarization axis in a first direction, and a first phase difference layer disposed on the first polarizer layer and circularly polarizing light passing through the first polarizer layer. The second polarizer includes a second retardation layer for linearly polarizing circularly polarized light, a second polarizer layer disposed on the second retardation layer and having a polarization axis orthogonal to the first direction, and a second polarizer disposed on the second polarization axis. And a third retardation layer for circularly polarizing light passing through the layer.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but only the embodiments to complete the disclosure of the present invention, the scope of the invention to those skilled in the art to which the present invention pertains. It is provided for the purpose of clarity, and the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout. "And / or" also includes each and all combinations of one or more of the items mentioned.

Although the first, second, etc. are used to describe various elements, components and / or sections, these elements, components and / or sections are of course not limited by these terms. These terms are only used to distinguish one element, component or section from another element, component or section. Therefore, the first device, the first component, or the first section mentioned below may be a second device, a second component, or a second section within the technical spirit of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, “comprises” and / or “comprising” refers to the presence of one or more other components, steps, operations and / or elements. Or does not exclude additions.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. In addition, the terms defined in the commonly used dictionaries are not ideally or excessively interpreted unless they are specifically defined clearly.

Hereinafter, a liquid crystal display according to embodiments of the present invention will be described with reference to the accompanying drawings.

1 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the liquid crystal display 600 includes a liquid crystal panel 710 for displaying an image, a first polarizing plate 722 disposed under the liquid crystal panel 710, and an upper portion of the liquid crystal panel 710. A display unit 750 including a second polarizing plate 724 disposed, a driving circuit unit 716 driving the liquid crystal panel 710, and a backlight unit 100 for supplying light to the liquid crystal panel 710. can do.

The liquid crystal panel 710 may include a first substrate 712, a second substrate 714 facing the first substrate 712, and a liquid crystal molecule layer interposed between the first substrate 712 and the second substrate 714. Not shown).

The first substrate 712 may be a TFT substrate in which a thin film transistor (hereinafter, TFT, not shown), which is a switching element, is formed in a matrix form. A data line (not shown) and a gate line (not shown) are respectively connected to the source terminal and the gate terminal of the TFTs, and a pixel electrode is connected to the drain terminal.

The second substrate 714 may be a color filter substrate in which RGB pixels (not shown) for implementing colors are formed in a thin film form. A common electrode (not shown) made of a transparent conductive material may be formed on the second substrate 714.

The liquid crystal molecular layer is interposed between the first substrate 712 and the second substrate 714, and its arrangement is changed according to an electric field formed between the first substrate 712 and the second substrate 714. The first polarizer 722 is disposed under the first substrate 712 and has a polarization axis in the first direction. Light passing through the first polarizing plate 722 is polarized in the first direction and is incident on the liquid crystal molecular layer. The second polarizer 724 is disposed on the second substrate 714 and has a polarization axis in a second direction. Light passing through the liquid crystal molecule layer is determined whether the second polarizing plate 724 passes according to whether the polarization direction coincides with the second direction.

In the liquid crystal panel 710 having such a configuration, when power is applied to the gate terminal of the TFT and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode. The arrangement of the liquid crystal molecules interposed between the first substrate 712 and the second substrate 714 is changed by this electric field. The transmittance of light supplied from the backlight unit 100 is changed according to the arrangement of the liquid crystal molecules to display an image having a desired gray scale.

The driving circuit unit 716 includes a gate driver (not shown) for generating a plurality of gate signals and providing the gate lines to each gate line, and a data driver (not shown) for generating an image data voltage and providing the data data voltages to each data line. .

The backlight unit 100 may include a light source 110 generating light, a light source cover 112 protecting the light source 110, a light guide plate 200 guiding a path of light generated from the light source 110, and a light guide plate 200. The reflective sheet 120 may be disposed below the light guide plate, and one or more optical sheets 130 may be disposed on the light guide plate 200.

The light source 110 is disposed at one side of the light guide plate 200. The light source 110 generates light in response to driving power applied from the outside. The light source cover 112 covers the three surfaces of the light source 110 to protect the light source 110. The light source cover 112 may also reflect light generated from the light source 110 toward the light guide plate 200 to improve light utilization efficiency.

The light guide plate 200 guides a traveling path of light incident from the light source 110. The light guide plate 200 has an incident surface 210 to which light from the light source 110 is incident, an upper surface 220 in contact with the incident surface, and a lower surface 260 in contact with the upper surface 220 in contact with the incident surface 210. It may include.

The reflective sheet 120 reflects light leaking to the outside through the lower portion of the light guide plate 200 to be incident again into the light guide plate 200.

One or more optical sheets 130 are disposed on the light guide plate 200 in order to improve brightness or improve appearance quality of light emitted from the light guide plate 200. The one or more optical sheets 130 may include at least one of a diffusion sheet (not shown), a prism sheet (not shown), and a protective sheet (not shown).

Since the diffusion sheet has a haze, appearance quality problems such as bright lines, dark lines, and corner arms can be improved. The prism sheet has prism patterns formed on one surface thereof, and may serve to collect light emitted from the light guide plate 200. The protective sheet may be disposed on the prism sheet to protect the prism sheet, and at the same time, to prevent adhesion to the liquid crystal panel 710 disposed thereon, thereby further improving the reliability of appearance quality.

2 to 8, a composite polarizer (see 724 of FIG. 1) and a cover member (not shown in FIG. 1) included in the liquid crystal display (600 of FIG. 1) according to the exemplary embodiments of the present invention. Explain. The second polarizer 724 in FIG. 1 is also referred to as a composite polarizer hereinafter. The composite polarizing plate is disposed above the liquid crystal panel (see 710 of FIG. 1) to polarize light emitted from the liquid crystal panel (see 710 of FIG. 1).

2 is a cross-sectional view of the composite polarizing plate 724 included in the liquid crystal display according to the first embodiment of the present invention.

Referring to FIG. 2, the composite polarizer 724 is disposed on the base layer 310, the polarizer layer 320 disposed on the base layer 310 and having the polarization axis in the first direction, and the polarizer layer 320. And a phase difference layer 330 for retarding a phase of light passing through the polarizer layer 320, and a first layer 340 and a base layer 310 formed on one surface of the phase difference layer 330 and including an ultraviolet blocking material. It may include a PSA layer 350 disposed below.

The base layer 310 may be a support for supporting and protecting the polarizer layer. The composite polarizer 724, in which the base layer 310 is a support, may be applied, for example, in a mode in which the arrangement of liquid crystal molecules of the liquid crystal molecule layer changes predominantly on the xy plane of FIG. 1. Like the twisted nematic (TN) mode, a liquid crystal display device employing a mode in which a pixel electrode is positioned on the first substrate 712 and a common electrode is positioned on the second substrate 714, an in-plane switching (IPS) mode, The present invention may also be applied to a liquid crystal display device employing a co-planar electrode (CE) mode in which a common electrode and a pixel electrode are positioned on one display panel, such as a fringe field switching (FFS) mode and a plane to line switching (PLS) mode.

Such a support may be made of, for example, Tri-Acetyl Cellulose (TAC). TAC is durable and has a constant mechanical strength.

Alternatively, the base layer 310 may be a viewing angle compensation layer that compensates for the viewing angle of the liquid crystal panel (see 710 of FIG. 1).

The composite polarizing plate 724 in which the base layer 310 is a viewing angle compensation layer is, for example, in a mode in which the arrangement of liquid crystal molecules of the liquid crystal molecule layer changes predominantly on a plane including a vertical direction (the z-axis direction in FIG. 1). Can be applied. An example of such a mode is VA (Vertical Alignmnet) mode.

The viewing angle compensation layer may serve to compensate the viewing angle with respect to the liquid crystal molecules arranged in a vertical direction (the z-axis direction of FIG. 1) by arranging molecules in a direction present on the xy plane of FIG. 1.

As such, the viewing angle compensation layer may be made of, for example, n-TAC, new n-TAC, or COP (cyclic amorphous polyolefin).

The polarizer layer 320 has a polarization axis in the first direction. The polarizer layer 320 may be obtained by adsorbing iodine or dichroic dye on a poly-vinyl alcohol (PVA) layer having a polarization axis in a first direction. The polarizer layer 320 divides light incident on the polarizer layer 320 into, for example, two components orthogonal to each other, and transmits components that vibrate in a direction parallel to the first direction, and absorbs or disperses the remaining components. Can be.

The retardation layer 330 is a birefringent film or liquid crystal obtained by stretching a film made of a suitable polymer such as polycarbonate, polyvinyl alcohol, polystyrene or polymethyl methacrylate, polypropylene or other polyolefin, polyarylate or polyamide. The orientation film of a polymer and the orientation layer of a liquid crystal polymer may be supported by the film. The retardation layer 330 may also consist of a uniaxial film or a biaxial film.

In particular, the retardation layer 330 may be made of norbornene-based COP (cyclic amorphous polyolefin). The retardation layer 330 made of COP has a relatively high light transmittance, heat resistance, and strength, and has low water absorption, compared to TAC, which is advantageous for high humidity testing. For example, since the strength is high, the surface strength of the liquid crystal display may be improved. May be scratch resistant soon. On the other hand, the norbornene-based COP is excellent in surface coating property, it may be easy to coating treatment such as hard coating (Hard Coating) or AG (Anti Glare) coating to be described later.

The retardation layer 330 may have a λ / 4 phase delay characteristic.

In this case, the first direction of the polarization axis of the polarizer layer 320 and the second direction in which the retardation layer 330 is stretched may cross each other at an angle of approximately 45 ° or 45 ± 10 ° when viewed on a plane. The retardation layer 330 has an optical axis in the stretched direction. When the retardation layer 330 has a λ / 4 phase retardation characteristic, light linearly polarized in the polarizer layer 320 may be circularly or elliptically polarized while passing through the retardation layer 330. Accordingly, since circularly polarized or elliptically polarized light is emitted from the liquid crystal display, the polarization axis of the polarized sunglasses (not shown) may not be taken into consideration when setting the polarization axis of the composite polarizer 724, that is, the second polarizer.

Alternatively, the retardation layer 330 may have a phase delay characteristic of 2000 nm or more. When the retardation layer 330 has a phase retardation characteristic of 2000 nm or more, light that has been linearly polarized in the polarizer layer 320 and then passed through the retardation layer 330 is circularly polarized or elliptically polarized light, as well as linearly polarized light vibrating in various directions. It may include. Therefore, since the circularly polarized or elliptically polarized light is emitted from the liquid crystal display, the polarization axis of the polarized sunglasses (not shown) may not be taken into consideration when setting the polarization axis of the composite polarizing plate 724, that is, the second polarizing plate. In addition, color shifhing, which may occur when light passes through the retardation layer 330, may be reduced, thereby improving display quality of the liquid crystal display.

The first layer 340 is formed on one surface of the phase difference layer 330. Although the first layer 340 is formed on the phase difference layer 330 in FIG. 2, the phase difference layer 330 may be formed between the polarizer layer 320 and the phase difference layer 330.

The first layer 340 may include a sunscreen material.

Examples of sunscreen substances include cericylpava, drometrizole, digaloylthiolate, 3- (4-methylbenzyladen) -campa, methylanthranilate, benzophenone-3, benzophenone-4, benzophenone- 8, Butylmethoxydibenzoylmethane, synoxate, octyltrizone, octogrylene, octyldimethylmethyl, octylmethoxycinnamate, octylsalicylate, paraanimobenzoic acid, 2-phenylbenzimidazole-5- Sulfonic acid, homosalate, zinc oxide, titanium oxide, isoamyl-p-methoxycinnamate, bisethylhexyloxyphenolmethoxyphenyltriazine, disoniumphenyldibenzimidazoletesulfonate, drometrizoltri Siloxane and the like.

The UV blocking material may reduce ultraviolet rays that may be incident on the liquid crystal display from the outside, thereby increasing reliability of the operation of the liquid crystal display.

In particular, the first layer 340 may be a hard coat layer coated on the retardation layer 330. That is, when the hard coat layer is coated on the retardation layer 330, the above-described UV blocking material may be mixed with the coating material and formed together. In this case, since the hard coat layer including the UV blocking material can be formed in one step, it can be advantageous in terms of process efficiency and thickness of the liquid crystal display device.

Herein, the hard coat layer will be described in more detail. For example, as shown in FIG. 2, the hard coat layer coated on the surface of the composite polarizing plate 724 may improve the surface hardness of the liquid crystal display device. You can. In other words, damage and deformation of the retardation layer 330 can be reduced.

This heartcoat layer can be a single layer or composed of multiple layers. The single layer refers to the hard coat layer formed of the same curable composition, and may be formed by a plurality of coatings if the composition after application and drying can be the same. A plurality of layers refers to a hard coat layer formed of a plurality of curable compositions having different compositions. However, the present invention is not limited thereto, and the hard coat layer may be manufactured in the form of a film and attached to the surface of the composite polarizing plate 724.

The curable composition of the hard coat layer may be a curable resin cured by an active energy ray. In addition, the curable composition may be a polymer compound or a monomer compound, and for example, an acrylic polymer, a urethane polymer, an epoxy polymer, a silicone polymer or a silica compound may be used, and in particular, an ethylene such as an acryl group may be used. Curable resins containing a unsaturated unsaturated group can be used.

Specifically, polyol acrylic, such as trimethylol propane triacrylate, ditrimethylol propane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate And urethane acrylates obtained by the reaction of hydroxyl group-containing acrylates such as acrylates, polyisocyanates and hydroxyethyl acrylate.

In order to increase the hardness of the hard coat layer, the resin-forming component of the layer may be a polyfunctional acrylic ester monomer, and may contain a powdered inorganic filler such as alumina, silica, titania, zirconia, or crosslinked organic fine particles. Moreover, in order to improve affinity of a polyfunctional acrylate ester monomer and an inorganic filler, an inorganic filler can also be surface-treated with an alkoxysilane.

Moreover, the curable composition for hard-coat layers may contain curable resin containing a ring-opening polymeric group in addition to curable resin containing two or more ethylenically unsaturated groups in the same molecule. Curable resin containing a ring-opening polymerizable group is curable resin which has ring structure which ring-opening polymerization advances by action of a cation, an anion, a radical, etc. Among these, heterocyclic group containing curable resin can be used. As such a curable resin, cyclic imino ethers, such as an epoxy derivative, an oxetane derivative, a tetrahydrofuran derivative, a cyclic lactone derivative, a cyclic carbonate derivative, an oxazoline derivative, etc. are mentioned, Especially an epoxy derivative and an oxetane derivative Oxazoline derivatives may be used.

The pressure sensitive adhesive layer 350 may attach the composite polarizer 724 to the top surface of the liquid crystal panel (see 710 of FIG. 1). The PSA layer 350 may be in the form of a film including an adhesive, and performs an adhesive operation in response to a pressure provided from the outside. Here, as an adhesive, the adhesive which contained microparticles | fine-particles, such as an acryl-type and rubber-type adhesive whose refractive index exists in the range of 1.46-1.52, or the zirconia for adjusting the refractive index of an adhesive can be used.

Although not shown, the surface of the composite polarizing plate 724 included in the liquid crystal display according to the exemplary embodiment of the present invention may have an anti-glare (AG) coating for preventing glare, an anti reflection (AR) coating for preventing reflection, and an LR ( Low Reflection (AS) coating, or anti static (AS) coating for antistatic. Here, the AR coating treatment is performed to absorb most of the light from the coating film made of a special material, and LR coating is performed to absorb a considerable part of the light from the coating film made of the special material and reflect the rest. Such coating treatments may be carried out in duplicate of one or more.

When the AG coating treatment is described in more detail, the AG coating treatment reflects light provided from the outside on the surface of the composite polarizing plate 724 to prevent the light passing through the composite polarizing plate 724 from being viewed. Can be implemented. In other words, if the AG coating treatment, it is possible to reflect and diffuse the light provided from the outside to prevent the glare that the user feels. For example, the surface may be formed by giving a fine concavo-convex structure to the surface by a suitable method such as a coarse cotton method or a method of blending transparent fine particles by a sand blast method, an embossing method, or the like. Examples of the transparent fine particles include silica, alumina, titania, zirconia, stone oxide, indium oxide, cadmium oxide, ammonium oxide, etc. having an average particle diameter, and inorganic fine particles having conductivity may be used. And organic fine particles made of a crosslinked or uncrosslinked polymer particulate matter or the like.

3 is a conceptual diagram illustrating a polarization process in the liquid crystal display according to the first embodiment of the present invention. The polarization process illustrated in FIG. 3 may be applied when the arrangement of liquid crystal molecules changes predominantly on the xy plane of FIG. 1. That is, the polarization process illustrated in FIG. 3 may be applied to a liquid crystal display device employing a TN mode, an IPS mode, an FFS mode, and a PLS mode. In the liquid crystal display according to the first exemplary embodiment of the present invention, the case where the phase difference layer 330 has a λ / 4 phase delay characteristic is mainly described. The same principle can be applied.

It is assumed that the liquid crystal molecules 730 are in the TN mode, and the polarization axis of the first polarizing plate 722 is 0 ° and the polarization axis of the polarizer layer 320 is 90 ° (ie, the first direction). do. Since the polarization axis of the first polarizing plate 722 and the polarization axis of the polarizer layer 320 are perpendicular to each other, the liquid crystal display normally displays a black screen in a state where no electric field is applied to the liquid crystal molecules 730. mode).

Light provided from the backlight unit (see 100 of FIG. 1) is incident on the first polarizer 722 in a non-polarized state. Since the first polarizing plate 722 functions as a linear polarizer, the light passing through the first polarizing plate 722 is polarized in the direction of the polarization axis of the first polarizing plate (that is, becomes 0 ° linearly polarized) and thus the liquid crystal molecular layer 730 Incident.

While the light incident on the liquid crystal molecule layer 730 passes through the liquid crystal molecule layer 730, the polarization direction of the light may change due to retardation due to refractive index anisotropy of the liquid crystal molecules 730. For example, when the liquid crystal molecules 730 are in the TN mode, the polarization direction of the light may rotate 90 °.

In detail, when an electric field is formed in the liquid crystal molecule layer 730 (ON state), the polarization direction of the light may rotate 90 ° while the light having the 0 ° linear polarization state passes through the liquid crystal molecule layer 730. On the other hand, when no electric field is formed in the liquid crystal molecule layer 730 (OFF state), even if light having a 0 ° linear polarization state passes through the liquid crystal molecule layer 730, no phase difference occurs, thereby maintaining a 0 ° linear polarization state.

Since the polarizer layer 320 included in the second polarizing plate (see 724 of FIG. 2) has a polarization axis in the first direction, only the light component oscillating in the first direction passes.

Specifically, when an electric field is formed in the liquid crystal molecule layer 730 (ON state), light 90 ° linearly flattened while passing through the liquid crystal molecule layer 730 vibrates in the first direction, which is the direction of the polarization axis of the polarizer layer 320. Therefore, the light may pass through the polarizer layer 320. On the other hand, when no electric field is formed in the liquid crystal molecule layer 730 (OFF state), the linear polarization state is maintained even when passing through the liquid crystal molecule layer 730, which is the direction of the polarization axis of the polarizer layer 320. Since it is orthogonal to one direction, it cannot pass through the polarizer layer 320.

Light linearly polarized in the first direction in the polarizer layer 320 is polarized again in the retardation layer 330. When the retardation layer 330 has a λ / 4 phase delay property, the retardation layer 330 may have a delay value in a range of 120 to 180 nm based on light having a wavelength of 550 nm. When an electric field is formed in the liquid crystal molecule layer 730 (ON state), light linearly polarized (ie, 90 ° linearly polarized) in the first direction while passing through the polarizer layer 320 may have a retardation layer having the retardation value. It may be circularly polarized or elliptically polarized while passing through 330. If the angle between the optical axis of the retardation layer 330 and the polarization axis of the polarizer layer 320 is 45 °, the circularly polarized light is emitted, and if the angle is between 45-10 ° and 45 + 10 °, the elliptical polarization is performed. The light is emitted.

On the other hand, when the retardation layer 330 has a phase retardation characteristic of 2000 nm or more, the circularly polarized or elliptically polarized light as well as the linearly polarized light vibrating in various directions may be emitted.

As described above, when circularly polarized or elliptically polarized light is emitted from the liquid crystal display, the polarization axis of the polarized sunglasses (not shown) may not be taken into consideration when setting the polarization axis of the composite polarizing plate, that is, the second polarizing plate.

4 is a cross-sectional view of a first polarizing plate, a second polarizing plate, and a liquid crystal panel included in the liquid crystal display according to the second exemplary embodiment of the present invention.

Referring to FIG. 4, in this case, the first polarizer 722 may include a base layer 510, a polarizer layer 520 disposed on the base layer 510, and having a polarization axis perpendicular to the polarization axis of the polarizer layer 320. The phase shift layer 530 disposed on the polarizer layer 520 and retarding the phase of light passing through the polarizer layer 520 and the PSA layer 550 disposed on the phase difference layer 530 may be included.

The base layer 510 may be a support for supporting and protecting the polarizer layer 520. Such a support may be made of, for example, TAC. The polarizer layer 520 has a polarization axis orthogonal to the direction of the polarization axis of the polarizer layer 320. The retardation layer 530 may be made of substantially the same material as the retardation layer 330. In particular, the retardation layer 530 may be made of norbornene-based COP. The retardation layer 530 may also have a λ / 4 phase delay characteristic. When the retardation layer 530 has a λ / 4 phase retardation characteristic, the direction of the polarization axis of the polarizer layer 520 and the optical axis of the retardation layer 530 may cross each other at an angle of about 45 ° when viewed on a plane. In this case, the linearly polarized light in the polarizer layer 520 may be circularly polarized while passing through the phase difference layer 530. The PSA layer 550 may attach the first polarizer 722 to the bottom surface of the liquid crystal panel (see 710 of FIG. 1).

The second polarizer 724 may include the base layer 310, the polarizer layer 320, the retardation layer 330, the first layer 340, and the PSA layer 350 described with reference to FIG. 2. The base layer 310 may be a viewing angle compensation layer, and in particular, may be made of COP. Base layer 310 may also have a λ / 4 phase delay characteristic. When the base layer 310 has a λ / 4 phase retardation property, the direction of the polarization axis of the polarizer layer 320 and the optical axis of the base layer 310 may cross at an angle of about 45 ° when viewed on a plane. In this case, circularly polarized light passing through the retardation layer 530 may be linearly polarized while passing through the base layer 310.

FIG. 5 is a cross-sectional view for describing the liquid crystal panel of FIG. 4 in detail, and FIG. 6 is a view illustrating a cutting pattern and liquid crystal molecules viewed in the direction A of FIG. 5.

Referring to FIG. 5, the liquid crystal panel 710 may include a first substrate 712 having a thin film transistor array, a second substrate 714 facing the common electrode 90, and two display panels 712 and 714. It includes a liquid crystal molecular layer 300 interposed therebetween.

First, the first substrate 712 will be described. A gate electrode 26 protruding from a gate line (not shown) that mainly extends in the horizontal direction is formed on an insulating substrate 10 made of transparent glass or the like. In addition, a storage electrode 29 protruding from a storage line (not shown) extending in the horizontal direction substantially parallel to the gate line is formed on the insulating substrate 10. The storage line and the storage electrode 29 may overlap the pixel electrode 82, which will be described later, to form storage capacitance.

A gate insulating film 30 is formed on the gate electrode 26 and the storage electrode 29, and a semiconductor layer 40 made of hydrogenated amorphous silicon, polycrystalline silicon, or the like is formed on the gate insulating film 30. have. In addition, ohmic contact layers 55 and 56 made of a material such as n + hydrogenated amorphous silicon doped with a high concentration of silicide or n-type impurities are formed on the semiconductor layer 40. . The ohmic contact layers 55 and 56 are disposed on the semiconductor layer 40 in pairs.

The data line 62 and the drain electrode 66 corresponding to the data line 62 are formed on the ohmic contact layers 55 and 56 and the gate insulating layer 30. The data line 62 mainly extends in the vertical direction and crosses the gate line, and a source electrode 65 extending toward the drain electrode 66 is formed in the data line 62. The source electrode 65 overlaps at least a portion of the semiconductor layer 40, and the drain electrode 66 faces the source electrode 65 around the gate electrode 26 and at least partially overlaps the semiconductor layer 40. do. Meanwhile, the drain electrode 66 may be formed so that one end thereof faces the source electrode 65 and the other end thereof is wide (shown as 67 in the drawing) to overlap the pixel electrode 82 which will be described later.

A passivation layer 70 is formed on the data line 62, the source electrode 65, the drain electrode 66, and the exposed semiconductor layer 40. The passivation layer 70 is an inorganic material made of silicon nitride or silicon oxide, an organic material having excellent planarization characteristics and photosensitivity, or a-Si: C: O formed by plasma enhanced chemical vapor deposition (PECVD), It consists of low dielectric constant insulating materials, such as a-Si: O: F. A contact hole 76 is formed in the passivation layer 70, and the pixel electrode 82 may be physically and electrically connected to the drain electrode 66 through the contact hole 76.

Next, the second substrate 714 will be described. A black matrix 94 is formed on the insulating substrate 96 made of transparent glass or the like to prevent light leakage and define the pixel region. The black matrix 94 may be formed at a portion corresponding to the gate line (not shown) and the data line 62 and at a portion corresponding to the thin film transistor.

Red, green, and blue color filters 98 may be sequentially arranged in the pixel region between the black matrices 94. An overcoat layer (not shown) may be formed on the color filter to planarize these steps.

A common electrode 90 made of a transparent conductive material such as ITO or IZO is formed on the overcoat layer (not shown). The common electrode 90 is disposed to face the pixel electrode 82, and the liquid crystal molecular layer 300 is interposed between the common electrode 90 and the pixel electrode 82.

The common electrode 90 may include an opening 92 at a portion overlapping the pixel electrode 82. The opening 92 may be formed at a portion corresponding to the central portion of the pixel electrode 82, and may have a hole-shaped cutout pattern. The hole shape refers to a portion where a portion of the common electrode 90 is indented in a curved line. The opening 92 may be circular in particular, as shown in FIG. 6.

When a voltage is applied between the pixel electrode 82 and the common electrode 90, the opening 92 may deform an electric field to impart direction to the movement of liquid crystal molecules. Specifically, when a voltage is applied to the common electrode 90 and the pixel electrode 82, since no voltage is directly applied to the opening 92, a lateral electric field is formed around the opening 92. Therefore, the liquid crystal molecules are inclined toward the opening 92, and thus are inclined radially toward the opening 92 as a whole. In particular, when the opening 92 is circular as shown in FIG. 6, the liquid crystal molecules included in the liquid crystal molecule layer 300 may correspond to 360 ° with respect to the opening 92 as shown in FIG. 6. It will tilt in all directions.

In the liquid crystal display device including the liquid crystal panel 710 illustrated in FIGS. 5 and 6, when a voltage is applied between the pixel electrode 82 and the common electrode 90, linearly polarized light is applied to the liquid crystal molecular layer 300. When light is incident, a region in which the directions of the liquid crystal molecules are inclined and the direction of the polarization axis of the first polarizer (see 722 of FIG. 4) coincide, and the direction in which the liquid crystal molecules are inclined and the second polarizer (see 724 in FIG. 4) In the region coinciding with the polarization axis of, light does not pass through the liquid crystal molecule layer 300. In particular, when the opening 92 is circular as shown in FIG. 6, since the liquid crystal molecules are inclined over the entire direction corresponding to 360 ° about the opening 92, the directions of the polarization axes of the first and second polarizing plates are different. In any direction, a region in which the direction of the polarization axis of the first or second polarizing plate coincides with the direction in which the liquid crystal molecules are inclined is generated.

However, in the liquid crystal display according to the second exemplary embodiment of the present invention, light is circularly polarized while passing through the phase difference layer 530 of the first polarizing plate 722, and then enters the liquid crystal molecular layer 300. . Therefore, the phenomenon as described above does not appear.

7 is a conceptual diagram illustrating a polarization process in the liquid crystal display illustrated in FIGS. 4 to 6. In the liquid crystal display according to the second exemplary embodiment of the present invention, the case where the phase difference layer 330 has a λ / 4 phase delay characteristic is mainly described. However, even when the phase difference layer 330 has a phase delay characteristic of 2000 nm or more, The same principle can be applied.

Hereinafter, in the state in which no electric field is applied to the liquid crystal molecules 730, the long axes of the liquid crystal molecules 730 may correspond to the first and second substrates (see 712 of FIG. 1) of the liquid crystal panel (see 710 of FIG. 1). The case perpendicular to the surface of FIG. 1 (see 714 of FIG. 1) will be described as an example. Also, when the direction of the polarization axis of the polarizer layer 520 of the first polarizing plate 722 is 0 ° and the direction of the polarization axis of the polarizer layer 320 of the second polarizing plate 724 (ie, the first direction) is 90 °. As an example. Since the polarization axis of the polarizer layer 520 and the polarization axis of the polarizer layer 320 are perpendicular to each other, the liquid crystal display operates in a normally black mode in which a black screen is displayed in a state where no electric field is applied to the liquid crystal molecules 730.

The distance between the first substrate (see 712 of FIG. 1) and the second substrate (see 714 of FIG. 1), ie, the thickness of the liquid crystal molecules 730, is defined as a cell gap. When an electric field is applied to the liquid crystal molecules 730, the cell gap and the refractive indexes of the liquid crystal molecules 730 are adjusted such that the liquid crystal molecules 730 have a phase difference of λ / 2. In addition, when no electric field is applied to the liquid crystal molecules 730, a phase difference does not occur because the directors of the liquid crystal molecules 730 are perpendicular to the first substrate and the second substrate.

When an electric field is applied to the liquid crystal molecules 730 (ON state), the non-polarized backlight passes through the polarizer layer 520 to become a 0 ° linearly polarized state and has a λ / 4 phase delay characteristic 530. Pass through) and becomes starboard polarized light. Light entering the starboard circularly polarized state passes through the liquid crystal molecules 730 having a phase difference of λ / 2 and becomes a port circularly polarized state. Ported circularly polarized light passes through a base layer 310 made of a material having a λ / 4 phase retardation property, for example, COP, and is in a 90 ° linearly polarized state. When the light is in the 90 ° linearly polarized state, since the polarization direction of the light coincides with the polarization axis of the polarizer layer 320, the light may pass through the polarizer layer 320.

Here, the left-circular polarization state is rotated clockwise based on the direction of light travel, and the right-circular polarization state is counterclockwise based on the light direction. It means to rotate.

The light passing through the polarizer layer 320 passes through the retardation layer 330 to be circularly or elliptically polarized. If the angle between the optical axis of the retardation layer 330 and the polarization axis of the polarizer layer 320 is 45 °, circularly polarized light is emitted, and if the angle is between 45-10 ° and 45 + 10 °, the elliptical polarization is performed. The light is emitted. As such, when the circularly polarized or elliptically polarized light is emitted from the liquid crystal display, the polarization axis of the polarized sunglasses (not shown) may not be taken into consideration when setting the polarization axis of the composite polarizing plate, that is, the second polarizing plate.

When no electric field is applied to the liquid crystal molecules (730), the non-polarized backlight passes through the polarizer layer 520 and becomes a 0 ° linearly polarized state, and has a phase difference layer having a λ / 4 phase delay characteristic ( Passing through 530, the star is in a circular polarization state. Light in starboard circularly polarized state maintains starboard circularly polarized state because phase difference does not occur even though it passes through liquid crystal molecules 730. Star-shaped circularly polarized light passes through a base layer 310 made of a material having a λ / 4 phase retardation property, for example, COP, and becomes a 0 ° linearly polarized state. When the light is in the 0 ° linearly polarized state, since the light is perpendicular to the polarization axis of the polarizer layer 320, the light does not pass through the polarizer layer 320, thereby implementing a black screen.

In the above-described second embodiment of the present invention, in addition to the liquid crystal display device having the liquid crystal panel shown in FIGS. The present invention can be applied to any liquid crystal display device employing a dominantly changing mode. For example, the structure described with reference to FIG. 4 and the polarization process illustrated in FIG. 7 may be applied to the liquid crystal display adopting the general VA mode.

8 is a cross-sectional view of the composite polarizing plate and the cover member included in the liquid crystal display according to the third exemplary embodiment of the present invention. The same reference numerals are used for the same components as those in the first embodiment of the present invention, and for convenience of description, descriptions substantially overlapping with the first embodiment of the present invention will be omitted.

Referring to FIG. 8, the composite polarizer 324 is disposed on the base layer 310, the polarizer layer 320 disposed on the base layer 310 and having the polarization axis in the first direction, and the polarizer layer 320. And a phase difference layer 330 for retarding a phase of light passing through the polarizer layer 320, and a first layer 340 and a base layer 310 formed on one surface of the phase difference layer 330 and including an ultraviolet blocking material. It may include a PSA layer 350 and a PSA layer 352 formed on the upper surface of the composite polarizing plate 324 disposed below.

The PSA layer 352 formed on the upper surface of the composite polarizing plate 324 may be made of the same material as the PSA layer 350 disposed below the base layer 310, and the composite polarizing plate 324 may be formed through the PSA layer 352. The cover member 360, which will be described later, may be attached to an upper surface of the cover.

The cover member 360 may be an impact resistant sheet, a transparent cover, or a touch screen panel.

The anti-shock sheet is applied to i-lens technology. i-lens technology is a technology that can reduce the thickness of the liquid crystal display while preventing impact resistance by removing the conventional reinforced plastic and directly attaching the anti-shock sheet to the composite polarizing plate 324. This technology also improves outdoor visibility by addressing the sun reflection problem previously caused by reinforced plastics.

The transparent cover is, for example, an acrylic protective cover for protecting the liquid crystal display device.

The touch screen panel is for a user to easily input information by touching a screen. The touch screen panel will be described later with reference to FIG. 10.

9 is a cross-sectional view of a composite polarizing plate and a cover member included in the liquid crystal display according to the fourth exemplary embodiment of the present invention. The same reference numerals are used for the same components as those in the third embodiment of the present invention, and for convenience of description, descriptions substantially overlapping with the third embodiment of the present invention will be omitted.

9, the composite polarizing plate 424 is disposed on the base layer 310, the polarizer layer 320 disposed on the base layer 310 and having the polarization axis in the first direction, and the polarizer layer 320. And a first support 430 supporting the polarizer layer 320, a PSA layer 350 disposed below the base layer 310, and a PSA layer 352 formed on an upper surface of the composite polarizer 424. Can be.

The base layer 410 may be a second support that supports and protects the polarizer layer together with the first support 430. Since the mode of the liquid crystal display device to which the composite polarizer 424 having the base layer 410 is the second support, the material of the second support, and the like are substantially the same as the case where the base layer 310 is the support while referring to FIG. 2. Detailed description thereof will be omitted.

Alternatively, the base layer 410 may be a viewing angle compensation layer that compensates for the viewing angle of the liquid crystal panel (see 710 of FIG. 1). The mode and the material of the viewing angle compensation layer to which the composite polarizing plate 424 is applied, in which the base layer 410 is the viewing angle compensation layer, are substantially the same as in the case where the base layer 310 is the support while referring to FIG. 2. Therefore, detailed description thereof will be omitted.

The first support 430 supports and protects the polarizer layer, and may be made of triacyl cellulose (TAC). TAC is durable and has a constant mechanical strength. In addition, the second support 430 made of TAC may have a UV blocking function.

The cover member 460 may be an impact resistant sheet, a transparent cover, or a touch screen panel. The cover member 460 may be attached onto the composite polarizing plate 424 via the PSA layer 352 formed on the upper surface of the composite polarizing plate 424, and may retard the phase of light passing through the polarizer layer 320. It may have a delay characteristic.

The cover member 460 may be formed of the same material as that of the phase difference layer 330 of FIG. 2, and may have the same phase delay characteristic as that of the phase difference layer 330 of FIG. 2. That is, the cover member 460 may have a λ / 4 phase delay characteristic or may have a phase delay characteristic of 2000 nm or more. Therefore, as in the first embodiment of the present invention, in setting the polarization axis of the composite polarizing tube or the second polarizing plate 424, the polarization axis of the polarized sunglasses (not shown) may not be considered.

In addition, the surface of the cover member 460 may be coated with a hard coat layer or may be AG coated, AR coated, LR coated, or AS coated.

10 is a cross-sectional view illustrating a touch screen panel in a fourth embodiment of the present invention.

Referring to FIG. 10, a case in which the cover member 460 included in the liquid crystal display according to the fourth exemplary embodiment of the present invention is the touch screen panel 462 will be described in more detail. One surface of the touch screen panel 462 may have a phase delay characteristic.

Referring to FIG. 10, the touch screen panel 462 may include a first conductive layer 464, a second conductive layer 462, a first surface layer 461, a second surface layer 463, and a spacer 465. Can be.

When the user touches an arbitrary point of the second surface layer 463 with a predetermined pressure or more, the point of the second conductive layer 464 and the first conductive layer 462 corresponding to the arbitrary point through the spacer 465. ) Meets and is electrically energized. As a result of the energization, an electrical signal is generated, and a calculation unit (not shown) calculates the coordinates of the touched point from the electrical signal and transfers the value to the liquid crystal display, thereby allowing a user to easily input information.

The first surface layer 461 and the second surface layer 463 support the touch screen panel 462. At least one of the first surface layer 461 or the second surface layer 463 may include a material such as the phase difference layer 330 of FIG. 2, and also may have a phase delay characteristic such as the phase difference layer 330 of FIG. 2. May have Accordingly, the touch screen panel 462 may have the phase delay characteristic of the cover member 460 described above. Likewise, the surface of the second surface layer 463 may be coated with a hard coat layer or treated with AG coating, AR coating, LR coating, or AS coating.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a cross-sectional view of a composite polarizing plate included in the liquid crystal display according to the first exemplary embodiment of the present invention.

3 is a conceptual diagram illustrating a polarization process in the liquid crystal display according to the first embodiment of the present invention.

4 is a cross-sectional view of a first polarizing plate, a second polarizing plate, and a liquid crystal panel included in the liquid crystal display according to the second exemplary embodiment of the present invention.

5 is a cross-sectional view for describing the liquid crystal panel of FIG. 4 in detail.

FIG. 6 is a view illustrating an incision pattern and liquid crystal molecules viewed in the direction A of FIG. 5.

FIG. 7 is a conceptual diagram illustrating a polarization process in the liquid crystal display illustrated in FIGS. 4 to 6.

8 is a cross-sectional view of the composite polarizing plate and the cover member included in the liquid crystal display according to the third exemplary embodiment of the present invention.

9 is a cross-sectional view of a composite polarizing plate and a cover member included in the liquid crystal display according to the fourth exemplary embodiment of the present invention.

10 is a cross-sectional view illustrating a touch screen panel in a fourth embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

100: backlight unit 110: light source

112: light source cover 120: reflective sheet

130: optical sheet 140: protective sheet

310: base layer 320: polarizer layer

330: phase difference layer 340: first layer

350: PSA layer 360: cover member

600: liquid crystal display device 710: liquid crystal panel

712: first substrate 714: second substrate

722: first polarizing plate 724: second polarizing plate

716: driving circuit portion 730: liquid crystal molecular layer

Claims (20)

A liquid crystal panel displaying an image; And It is disposed on the liquid crystal panel and includes a composite polarizing plate for polarizing the light emitted from the liquid crystal panel, The composite polarizing plate includes a base layer, a polarizer layer disposed on the base layer and having a polarization axis in a first direction, a phase difference layer disposed on the polarizer layer and retarding a phase of light passing through the polarizer layer; A liquid crystal display device comprising a first layer formed on one surface of a retardation layer and comprising a UV blocking material. According to claim 1, And the first layer is a hard coat layer coated on the retardation layer. According to claim 1, The retardation layer has a λ / 4 phase delay characteristic. The method of claim 3, The angle between the optical axis of the retardation layer and the polarization axis in the first direction has a value between 35 ° and 55 °. According to claim 1, The retardation layer is a liquid crystal display device made of COP (cyclic amorphous polyolefin). According to claim 1, The liquid crystal panel includes a first substrate and a second substrate and liquid crystal molecules interposed between the first substrate and the second substrate, The liquid crystal molecules dominantly change on a plane parallel to the first substrate and the second substrate, The base layer is a liquid crystal display device supporting the polarizer layer. According to claim 1, The liquid crystal panel includes a first substrate and a second substrate and liquid crystal molecules interposed between the first substrate and the second substrate, The liquid crystal molecules dominantly change on a plane perpendicular to the first substrate and the second substrate, And the base layer is a viewing angle compensation layer for compensating a viewing angle of the liquid crystal panel. The method of claim 7, wherein The viewing angle compensation layer has a λ / 4 phase delay characteristic. A liquid crystal panel displaying an image; A base layer, a polarizer layer disposed on the base layer and having a polarization axis in a first direction, a first support disposed on the polarizer layer to support the polarizer layer, and a PSA layer disposed on the first support A composite polarizing plate including a pressure-sensitive adhesive layer, wherein the composite polarizing plate is disposed on the liquid crystal panel and polarizes light emitted from the liquid crystal panel; And And a cover member attached to the composite polarizing plate via the PSA layer and having a phase retardation characteristic for retarding a phase of light passing through the polarizer layer. The method of claim 9, And the cover member is an impact resistant sheet, a transparent cover, or a touch screen panel on which one surface has the phase delay characteristics. The method of claim 9, The cover member has a λ / 4 phase delay characteristic. The method of claim 9, And the base layer is a second support for supporting the polarizer layer. A liquid crystal comprising a first substrate including a pixel electrode and a second substrate including a common electrode having an opening formed in a region corresponding to the pixel electrode, and liquid crystal molecules interposed between the first substrate and the second substrate. panel; A first polarizer disposed under the liquid crystal panel; And Including a second polarizing plate disposed on the liquid crystal panel, The first polarizer includes a first polarizer layer having a polarization axis in a first direction, and a first retardation layer disposed on the first polarizer layer and circularly polarizing light passing through the first polarizer layer, The second polarizing plate may include a second retardation layer for linearly polarizing the circularly polarized light, a second polarizer layer disposed on the second retardation layer and having a polarization axis orthogonal to the first direction, and on the second polarization axis. And a third retardation layer arranged to circularly polarize the light passing through the second polarizer layer. The method of claim 13, The opening is a liquid crystal display device having a hole-shaped cut pattern. The method of claim 13, And the liquid crystal molecules dominantly change on a plane perpendicular to the first substrate and the second substrate. The method of claim 13, When an electric field is applied to the liquid crystal molecules, The liquid crystal molecules have a phase difference of λ / 2. The method of claim 13, And at least one of the first retardation layer, the second retardation layer, and the third retardation layer has a λ / 4 phase delay characteristic. 18. The method of claim 17, The angle between the optical axis of the third retardation layer and the polarization axis of the second polarizer layer has a value between 35 ° and 55 °. The method of claim 13, And at least one of the first retardation layer, the second retardation layer, and the third retardation layer is made of COP (cyclic amorphous polyolefin). The method of claim 13, The second retardation layer is n-TAC, new n-TAC or COP (cyclic amorphous polyolefin).

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