TWI810353B - Polarizing plate and liquid crystal display comprising the same - Google Patents

Abstract

A polarizing plate and a liquid crystal display including the same. The polarizing plate includes: a polarizer; and a pattern layer formed on a light exit surface of the polarizer, wherein the pattern layer includes a first resin layer and a second resin layer sequentially formed on the polarizer; a pattern portion is formed at an interface between the first resin layer and the second resin layer and is composed of at least two pattern groups repeatedly arranged therein, each of the pattern groups including at least two engraved optical patterns; and at least two of the engraved optical patterns in each of the pattern groups have different aspect ratios and different base angles.

Description

Polarizing plate and liquid crystal display including same

[Cross Reference to Related Application]

This application claims Korean Patent Application No. 10-2018-0104006 filed with the Korean Intellectual Property Office on August 31, 2018 and Korean Patent Application No. 10-2019-0096380 filed with the Korean Intellectual Property Office on August 7, 2019 , the entire disclosure of which is incorporated herein by reference.

The invention relates to a polarizing plate and a liquid crystal display containing it.

The liquid crystal display is operated to allow light emitted from the backlight unit to sequentially pass through the light source side polarizing plate, the liquid crystal panel, and the viewer side polarizing plate. Light emitted from the light source is diffused while passing through the backlight unit and then enters the light source side polarizing plate. Therefore, when the light passes through the polarizing plate on the light source side, the liquid crystal panel and the polarizing plate on the viewer side, the liquid crystal display suffers from gradual degradation of contrast ratio and color deviation from the front side to the lateral side. In order to solve such a problem, a retardation film may be applied to a light source side polarizing plate or a viewer side polarizing plate. However, it is difficult for the retardation film to achieve light alignment from the front side to the lateral side Full compensation is made and it is difficult to prevent light leakage especially in the diagonal direction.

In order to solve the foregoing problems, it is proposed to use a light-condensing backlight unit. The condensing backlight unit uses an inverted prism condensing sheet instead of a typical ordinary prism diffusing sheet. A general prism diffusing sheet is a sheet having prisms formed on the light exit surface of the sheet member, and an inverted prism collecting sheet is a sheet having prisms on the light incident surface of the sheet member. This technology minimizes the difference in contrast ratio depending on the viewing angle by allowing the light emitted from the light-condensing backlight unit to pass through the liquid crystal panel via light-condensing, and by scattering the light at the outermost surface of the viewer's side polarizing plate A light collecting-scattering system to ensure viewing angle. For this purpose, it is necessary to develop an optical device in consideration of a light-condensing backlight unit. Although the scattering particle-containing film can be used as an optical device to be disposed on the outermost surface of the viewer's side polarizing plate, there are limitations in enlarging the viewing angle and/or improving the appearance of the scattering particle-containing film.

The background art of the present invention is disclosed in Japanese Unexamined Patent Publication No. 2006-251659.

An aspect of the present invention is to provide a polarizing plate capable of improving brightness, viewing angle, and contrast ratio at front and side sides when applied to a liquid crystal display including a light-condensing backlight unit.

Another aspect of the present invention is to provide a polarizing plate capable of improving a front contrast ratio, a side contrast ratio, and an appearance when applied to a liquid crystal display including a light-condensing backlight unit.

Still another aspect of the present invention provides a polarizing plate capable of reducing the brightness at the lateral side and the brightness at the front side depending on the angle of the lateral side when applied to a liquid crystal display including a light-condensing backlight unit The deviation of the ratio.

Yet another aspect of the present invention provides a liquid crystal display including a light-condensing backlight unit, which can improve brightness, viewing angle, and contrast ratio at the front side and lateral side, and can reduce the brightness depending on the angle of the lateral side. The deviation of the ratio of the luminance at the lateral side to the luminance at the positive side is small.

1. According to one aspect of the present invention, a polarizer comprises: a polarizer; and a pattern layer formed on the light exit surface of the polarizer, wherein the pattern layer comprises a first resin layer and a second resin formed sequentially on the polarizer layer; the pattern portion is formed at the interface between the first resin layer and the second resin layer, and is composed of at least two pattern groups repeatedly arranged in the pattern portion, each pattern group comprising at least two engraved optical patterns ; and at least two of the engraved optical patterns in each of the pattern groups have different aspect ratios and different bottom angles.

2. In paragraph 1, the aspect ratio of the engraved optical pattern may be from about 0.3 to about 3.0.

3. In segments 1 and 2, the difference between the largest and smallest aspect ratios of the engraved optical patterns in the pattern set may be about 0.5 or greater than 0.5.

4. In paragraphs 1 to 3, the base angle of the engraved optical pattern may be from about 60° to about 90°.

5. In paragraphs 1 to 4, the difference between the maximum base angle and the minimum base angle of the engraved optical patterns in the pattern set may be about 5° or greater.

6. In paragraphs 1 to 5, the engraved optical pattern may have at its top portion The flat surface and N-sided polygon (N is an integer from 4 to 10) cross-sectional shape.

7. In paragraphs 1 to 6, the engraved optical patterns in the pattern group may be arranged continuously without flat sections in between.

8. In segments 1 to 7, a flat segment may not exist or may otherwise be formed between two immediately adjacent pattern groups.

9. In paragraphs 1 to 8, the engraved optical pattern may extend in a stripe shape in its longitudinal direction.

10. In paragraphs 1 to 9, assuming that the polarizer has an absorption axis of 0°, the angle defined between the longitudinal direction of the engraved optical pattern and the absorption axis of the polarizer may be from about -20° to about 20°, From about 70° to about 110° or from about -70° to about -110°.

11. In Paragraph 1 to Paragraph 10, the refractive index of the first resin layer may be higher than the refractive index of the second resin layer.

12. In Paragraph 1 to Paragraph 11, the absolute value of the difference in refractive index between the first resin layer and the second resin layer may be about 0.05 or more.

13. In paragraphs 1 to 12, the number of engraved optical patterns in each pattern group may range from 2 to 10.

14. In paragraphs 1 to 13, each of the pattern groups may be composed of a total of two optical patterns including a first pattern and a second pattern as engraved optical patterns, and the first pattern and the second pattern have different bases angles and different aspect ratios.

15. In paragraphs 1 to 14, each of the pattern groups may be composed of a total of a first pattern, a second pattern, and a third pattern arranged continuously without a flat section in between as engraved optical patterns Three optical patterns are constructed, and the first At least two of the pattern, the second pattern, and the third pattern may have different bottom angles and different aspect ratios.

16. In paragraphs 1 to 15, the first resin layer may be a filling portion filling at least part of the engraved optical pattern or a layer including the filling portion.

17. In Paragraph 1 to Paragraph 16, the polarizing plate may further include: a protective film stacked on at least one of the light exit surface and the light incident surface of the pattern layer.

18. In paragraphs 1 to 17, the polarizing plate may further comprise: at least one surface treatment layer selected from a hard coating layer on at least one surface of the protective film, a scattering layer, a low reflectivity layer, an ultra-low reflectivity layer, Base coat, anti-fingerprint layer, anti-reflection layer and anti-glare layer.

19. According to another aspect of the present invention, a liquid crystal display comprises the polarizing plate according to the present invention.

20. In paragraph 19, the liquid crystal display may include: a backlight unit, a polarizing plate on the light source side, a liquid crystal panel, and a polarizing plate stacked sequentially in the stated order, the backlight unit may include a concentrating backlight unit, and the concentrating backlight unit may include an inverted Prism flakes.

21. In paragraphs 19 and 20, in the white mode of the concentrating backlight unit, the brightness (L30°) at the lateral side (30° or -30°) and the brightness (L0°) at the front side (0°) °) ratio (W30°=L30°/L0°) can be in the range of about 0.1 to about 0.5, and the brightness (L60°) at the lateral side (60° or -60°) is the same as the positive side (0°) A ratio (W60°=L60°/L0°) of luminance (L0°) at , may range from about 0 to about 0.1.

10, 20, 30: polarizer

100: Polarizer

200, 260, 270, 400: pattern layer

210, 420: the first resin layer

220, 410: the second resin layer

230, 240, 250, 280: pattern group

230A, 240A, 280A: the first pattern

230B, 240B, 280B: second pattern

230C: The third pattern

231, 232, 233, 241, 242: inclined surface

251, 252, 261, 262: flat section

280C: The third pattern

300: protective film

600: spotlight backlight unit

610: light source

620: light guide plate

630: Concentrating sheet

α1, α2, α3: bottom angle

h1, h2, h3: maximum height

L, W1, W2, W3: Maximum width

FIG. 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a pattern group of the polarizing plate of FIG. 1 .

3 is a cross-sectional view of a pattern group of a polarizing plate according to another embodiment of the present invention.

4 is a cross-sectional view of a pattern group of a polarizing plate according to still another embodiment of the present invention.

FIG. 5 is a cross-sectional view of a polarizing plate according to still another embodiment of the present invention.

FIG. 6 is a cross-sectional view of a polarizing plate according to still another embodiment of the present invention.

7 is a cross-sectional view of a pattern group of a polarizing plate according to still another embodiment of the present invention.

8 shows a luminance curve depicting the ratio of luminance at the lateral side to luminance at the positive side (0°) (L0°) relative to light emitted from a concentrating backlight unit in white mode and a typical backlight unit.

9 is a cross-sectional view of a concentrating backlight unit according to one embodiment of the present invention.

10 is a cross-sectional view of a polarizing plate of Comparative Example 4. FIG.

FIGS. 11 to 18 show the luminance curve (solid line) of the condensing backlight unit and the luminance curve (dashed line) when the polarizing plate of the example is applied to the condensing backlight unit.

19 to 22 show the luminance curve (solid line) of the condensing backlight unit and the luminance curve (dashed line) when the polarizer of the comparative example is applied to the condensing backlight unit.

FIG. 23 illustrates brightness at the lateral side relative to light emitted from a typical backlight unit. The ratio of brightness to the brightness at the positive side (solid line) and the brightness curve (dashed line) when the polarizing plate of Example 4 is applied to a typical backlight unit.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can thoroughly understand the present invention. It should be understood that the present invention can be embodied in various ways and is not limited to the following examples. In the drawings, parts irrelevant to the description will be omitted for clarity. Throughout this specification, the same components will be designated by the same reference numerals.

Herein, spatially relative terms such as "upper" and "lower" are defined with reference to the accompanying drawings. Accordingly, it should be understood that the term "upper surface" is used interchangeably with the term "lower surface" and that when an element such as a layer or film is referred to as being placed "on" another element, the element may be placed directly on On another element, or there may be intervening elements. On the other hand, when an element is referred to as being placed "directly on" another element, there are no intervening elements present.

Herein, the terms "horizontal direction" and "vertical direction" mean the longitudinal direction and the lateral direction of the rectangular screen of the liquid crystal display, respectively. Herein, with reference to the horizontal direction, "lateral side" means -30°, -45°, -60 °, 30°, 45° or 60°.

Herein, "top portion" refers to the highest point of the engraved optical pattern.

Herein, "aspect ratio" refers to the ratio of the maximum height of the engraved optical pattern to its maximum width (maximum height/maximum width).

In this paper, "bottom angle" means the maximum width of the optical pattern and the direct connection Angle defined between sloped surfaces up to their greatest width. For example, referring to FIG. 2 , the base angle means an angle α1 defined between the maximum width W1 of the optical pattern 230A and the inclined surface 231 directly connected to the maximum width W1 of the optical pattern 230A. For example, referring to FIG. 3 , the base angle means an angle α1 defined between the maximum width W1 of the optical pattern 240A and the inclined surface 241 directly connected to the maximum width W1 of the optical pattern 240A.

Herein, "in-plane retardation (Re)" is a value measured at a wavelength of 550 nm and expressed by Equation A: [Equation A] Re=(nx-ny)×d, where nx and ny are respectively The refractive index on the slow axis and the fast axis of the protective layer at a wavelength of 550 nm, and d is the thickness of the protective layer (unit: nanometer).

Herein, the term "(meth)acryl" refers to acryl and/or methacryl.

Unless specifically stated otherwise, lateral side (30°) may mean at least one of a lateral side of 30° and a lateral side of -30°, lateral side (45°) may mean a lateral side of 45° At least one of the side and the lateral side of -45°, and the lateral side (60°) may mean at least one of the lateral side of 60° and the lateral side of -60°.

FIG. 8 shows a luminance curve depicting the ratio of the luminance at the lateral side to the luminance (L 0° ) at the positive side (0 _° ) with respect to light emitted from a concentrator backlight unit in white mode (in FIG. 8 ), and a luminance curve depicting the ratio of the luminance at the lateral side to the luminance (L 0° ) at the positive side (0 _° ) relative to light emitted from a typical backlight unit in white mode (Fig. solid line in 8).

For a spotlight backlight unit, in white mode, the ratio of the luminance (L 30° ) at the lateral side (30° or -30 _° ) to the luminance (L 0° ) at the positive side ( ₀ °) ( W _30° =L _30° /L _0° ) can be about 0.1 to about 0.5, specifically 0.1 to 0.15, more specifically 0.11, and the brightness (L _60° ) to the brightness (L _0° ) at the positive side (0°) (W _60° = L _60° /L _0° ) may be about 0 to about 0.1, specifically about 0 to about 0.05, More specifically about 0.

For _a typical backlight unit, in white mode, the _ratio (W _30° =L _30° /L _0° ) can be 0.5 to 0.6, such as greater than 0.5 to about 0.6 or less than 0.6, and the brightness (L 60° ) at the lateral side (60° or -60 _° ) is the same as that of the positive side A ratio (W _60° =L _60° /L 0 _° ) of luminance (L _0° ) at (0°) may be about 0.1 to about 0.2.

Therefore, the concentrated backlight unit exhibits a completely different luminance curve from the typical backlight unit, as shown in FIG. 8 . "Typical backlight unit" means a backlight unit that does not include an inverted prismatic light-condensing sheet, and specifically, a backlight unit that includes an ordinary prism-diffusing sheet.

The inventors completed the present invention based on the finding that, when applied to a liquid crystal display including a light-condensing backlight unit, since the viewer-side polarizing plate is configured to emit light received from the light-condensing backlight unit including an inverted prism, the viewer The side polarizer includes a polarizer and a pattern layer formed on the light-emitting surface of the polarizer, wherein the pattern layer includes a first resin layer, a second resin layer, and a pattern part, and the pattern part has a structure between the first resin layer and the second resin layer. Groups of patterns repeated at the interface between the resin layers, The brightness, viewing angle, and contrast ratio at the front side and the side side are thereby improved, while reducing the deviation of the ratio of the brightness at the side side to the brightness at the front side depending on the angle of the side side.

The pattern set consists of at least two engraved optical patterns, wherein at least two of the engraved optical patterns have different aspect ratios and different base angles.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2 . FIG. 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of a pattern group of the polarizing plate of FIG. 1 .

Referring to FIG. 1 , the polarizer 10 includes a polarizer 100 , a pattern layer 200 formed on a light exit surface (upper surface) of the polarizer 100 , and a protective film 300 formed on the upper surface of the pattern layer 200 .

Since the purpose of simplifying the manufacturing process and reducing the thickness is not to include the protective film 300, the polarizing plate including the pattern layer 200 formed only on the upper surface of the polarizer 100 without the protective film 300 can also be used in this paper. within the scope of the invention.

In an alternative embodiment, the protective film 300 may be interposed between the polarizer 100 and the pattern layer 200 . That is, according to the present invention, the position of the protective film in the polarizing plate is not particularly limited.

pattern layer

The pattern layer 200 is formed between the polarizer 100 and the protective film 300 to allow polarized light received from the polarizer 100 to enter the protective film 300 through the pattern layer.

The pattern layer 200 may include a first resin layer 210 and a second resin layer 220 disposed to face the first resin layer 210 . In one embodiment, the pattern layer 200 can be made of The direct contacting first resin layer 210 and the second resin layer 220 are composed.

The first resin layer 210 is formed on the light incident surface of the second resin layer 220 . A pattern portion described hereinafter may be formed at an interface between the first resin layer 210 and the second resin layer 220 .

The pattern part is composed of at least two pattern groups 230 repeatedly arranged. In the pattern part, the pattern groups 230 may be the same as each other or may be different from each other.

Although FIG. 1 illustrates a polarizing plate in which no flat section is formed between the pattern groups 230 , a flat section may be formed between the pattern groups 230 . The structure will be described in detail below.

The pattern group 230 is composed of at least two engraved optical patterns arranged continuously without a flat section therebetween, wherein at least two of the engraved optical patterns have different aspect ratios and different base angles. With a structure in which at least two of the engraved optical patterns have the same aspect ratio but have different base angles, the polarizer may suffer from improved viewing angles at all lateral sides 30°, 45° and 60°. Problems with abnormally high or low brightness at small or specific corners, resulting in uneven image quality at lateral sides. In the case of having a structure in which at least two of the engraved optical patterns have the same bottom angle but different aspect ratios, the polarizing plate may suffer from the same problem.

Referring to FIG. 2 , the pattern group 230 includes three optical patterns, ie, a first pattern 230A, a second pattern 230B, and a third pattern 230C, arranged continuously without a flat section therebetween. At least two of the first pattern 230A, the second pattern 230B and the third pattern 230C have different aspect ratios and different bottom angles.

Herein, as shown in FIG. 2, although any bottom angle may be defined as the bottom angle in the case where the two bottom angles of each of the first pattern 230A, the second pattern 230B, and the third pattern 230C are the same, In a case where the two bottom angles of each of the first pattern 230A, the second pattern 230B, and the third pattern 230C are different, a larger bottom angle among the two bottom angles may be defined as the bottom angle.

1 and 2 illustrate polarizing plates in which engraved optical patterns are continuously arranged in each pattern group without flat sections in between. However, in other embodiments, the set of patterns may include flat segments between engraved optical patterns, as described in detail below.

In one embodiment, the first pattern, the second pattern and the third pattern may have different bottom angles and different aspect ratios.

In another embodiment, the first pattern and the second pattern may have different bottom angles and different aspect ratios.

In yet another embodiment, the first pattern and the third pattern may have different bottom angles and different aspect ratios.

In yet another embodiment, the second pattern and the third pattern may have different bottom angles and different aspect ratios.

In one embodiment, the optical patterns are successively arranged in the pattern group in the order of increasing base angle. That is, referring to FIG. 2 , the bottom angle (α1) of the first pattern 230A is smaller than the bottom angle (α2) of the second pattern 230B which is smaller than the bottom angle (α3) of the third pattern 230C. In one embodiment, the aspect ratio of the first pattern 230A may be smaller than the aspect ratio of the second pattern 230B; the aspect ratio of the third pattern 230C may be less than or equal to the aspect ratio of the second pattern 230B; and the aspect ratio of the first pattern 230A may be less than or equal to the aspect ratio of the third pattern 230C.

Although FIG. 2 depicts a pattern group 230 comprising three engraved optical patterns, the number of optical patterns in each pattern group may depend on the degree of collection of light emitted from the concentrating backlight unit, the brightness, the thickness of the polarizer and similar to adjust. For example, the number of engraved optical patterns in each pattern group may be about 2 to about 10, specifically from 2 to 5, more specifically from 2 to 3.

In one embodiment, interface points between the first pattern 230A, the second pattern 230B, and the third pattern 230C provided as engraved optical patterns in the pattern set may contact each other and may be coplanar with each other.

The aspect ratio of each of the first pattern 230A, the second pattern 230B, and the third pattern 230C or the average aspect ratio of the patterns in the pattern group may be about 0.3 to about 3.0, for example, about 0.3, 0.4, 0.5, 0.6 ,0.7,0.8,0.9,1.0,1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9,2.0,2.1,2.2,2.3,2.4,2.5,2.6,2.7,2.8,2.9,3.0, specifically Specifically, from about 1.0 to about 3.0, more specifically from about 1.0 to about 2.0. Within this range, the polarizing plate may have an improved viewing angle and may exhibit uniform lateral brightness.

In one embodiment, the difference between the maximum aspect ratio and the minimum aspect ratio of the engraved optical patterns in the pattern set (ie, the first pattern, the second pattern, and the third pattern) may be about 0.5 or greater than 0.5, For example about 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, specifically about 0.5 to about 2.5, more specifically about 0.5 to about 1.0. In this range, polarizers can achieve improved viewing angles and uniform lateral brightness°

The base angle α1, α2, or α3 of each of the first pattern 230A, the second pattern 230B, and the third pattern 230C or the average value of the base angles of the patterns in the pattern group may be about 60° to about 90°. °, such as about 60°, about 65°, about 70°, about 75°, about 80°, about 85°, about 90°, specifically about 60° to less than about 90°, more specifically about 75° to about 85°. Within this range, the polarizing plate can achieve an improvement in viewing angle and uniform lateral brightness.

In one embodiment, the difference between the maximum base angle and the minimum base angle of the optical patterns in the pattern group (that is, the first pattern, the second pattern, and the third pattern) may be about 5° or greater than 5°, for example Approx. 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, 21 °, 22°, 23°, 24°, 25°, specifically about 5° to about 25°, more specifically about 5° to about 10°. Within this range, the polarizing plate can achieve an improvement in viewing angle and uniform lateral brightness.

Two bottom corners of each of the first pattern, the second pattern, and the third pattern may be the same or different. Preferably, two bottom corners of each of the first pattern, the second pattern and the third pattern are the same.

The maximum width W1 , the maximum width W2 , and the maximum width W3 of the first pattern 230A, the second pattern 230B, and the third pattern 230C may be the same or different. For example, each of maximum width W1 , maximum width W2 , maximum width W3 may be about 1 micron to about 50 microns, such as about 1 micron to about 20 microns. In this range, the polarizer can achieve an improved viewing angle and uniform lateral brightness, and can prevent The phenomenon of Moire fringe (Moiré) with LCD panel.

The maximum height h1 , the maximum height h2 , and the maximum height h3 of the first pattern 230A, the second pattern 230B, and the third pattern 230C may be the same or different. For example, each of the maximum height h1 , the maximum height h2 , the maximum height h3 may be about 1 micron to about 50 microns, such as about 1 micron to about 20 microns. Within this range, the polarizing plate can achieve improved viewing angle and uniform lateral brightness, and can prevent the phenomenon of moiré fringe with the picture element of the liquid crystal panel.

2 illustrates a first pattern 230A, a second pattern 230B, and a third pattern 230C each having a trapezoidal cross-sectional shape, wherein an inclined surface 231, an inclined surface 232, or an inclined surface 233 is connected to a flat surface at a top portion of each pattern. . However, it should be understood that the present invention is not limited thereto. While planar surfaces can be modified to have surface roughness or curved surfaces, planar surfaces are preferably free of such modifications.

The engraved optical pattern may have a flat inclined surface or an angular inclined surface, and may be a pattern having an N-sided polygon (N is an integer of 4 to 10) cross-sectional shape including a Triangular cross-sectional shape or trapezoidal cross-sectional shape for flat surfaces. This will be described in detail below. Preferably, the optical pattern may have a trapezoidal cross-section.

In each of the pattern groups, the optical patterns may have the same shape or different shapes. Preferably, the optical patterns have the same shape in order to facilitate the process of manufacturing the polarizing plate.

In FIG. 2 , the flat surfaces of the first pattern 230A, the second pattern 230B, and the third pattern 230C may have the same width or different widths, and the width may be greater than 0 micron and about 50 micron or less than 50 micron, for example about 1 micron to about 20 micron, specifically about 1 micron to about 10 micron. Within this range, the polarizing plate can achieve improved viewing angle and uniform lateral brightness, and can prevent the phenomenon of moiré fringe with the picture element of the liquid crystal panel.

Referring again to FIG. 1 , the pattern portion is composed of pattern groups 230 repeatedly arranged therein. FIG. 1 illustrates a polarizing plate in which a first pattern, a second pattern, and a third pattern are arranged in the same order in each of the pattern groups. However, it should be understood that the arrangement order of these optical patterns in adjacent pattern groups may be the same or different.

Although not shown in FIG. 1 , each of the optical patterns in the pattern group may have a strip shape extending in the longitudinal direction of the optical patterns. With this structure, the polarizing plate can achieve good improvement in viewing angle at the lateral sides. Herein, "the longitudinal direction of the optical pattern" means a direction different from the direction of the maximum width of the optical pattern, that is, a direction intersecting the direction of the maximum width.

In one embodiment, assuming that the polarizer has an absorption axis of 0°, the angle defined between the longitudinal direction of the optical pattern and the absorption angle of the polarizer 100 may be from about -20° to about 20°, from about 70° to About 110° or in the range of about -70° to about -110°. In this range, the polarizing plate can prevent the phenomenon of moiré fringe with the picture element of the liquid crystal panel. Preferably, the angle defined therebetween is in the range of about 90° or about -90°.

The first resin layer 210 may be a high refractive index pattern layer having a higher refractive index than the second resin layer 220 .

The absolute value of the difference in refractive index between the first resin layer 210 and the second resin layer 220 may be about 0.05 or greater than 0.05, specifically about 0.1 or greater than 0.1, more preferably Typically from about 0.1 to about 0.3, from about 0.1 to about 0.2 or from about 0.15 to about 0.2. Within this range, the polarizing plate can achieve good improvement in viewing angle.

The refractive index of the first resin layer 210 may be about 1.50 to about 1.70, specifically about 1.55 to about 1.70, more specifically about 1.60 to about 1.70. Within this range, the polarizing plate can have a high light-diffusing effect, can be easily manufactured, and can achieve improvements in polarized light diffusion and viewing angle.

The first resin layer 210 may include a filling part or a layer having a filling part filling at least part of the engraved optical pattern. Preferably, the filled portion completely fills the engraved optical pattern. In a structure in which the filling portion partially fills the engraved optical pattern, the remainder of the engraved optical pattern may be filled with air.

The first resin layer 210 may be formed of a composition for the first resin layer including a curable resin. The curable resin may include at least one selected from UV curable resins and heat curable resins, but is not limited thereto. The composition for the first resin layer may further include at least one selected from initiators and additives. The initiator may include at least one selected from photocurable initiators and thermally curable initiators, but is not limited thereto. Additives may comprise any typical additives known to those of ordinary skill in the art. For example, the additive may include at least one selected from a leveling agent, a surface conditioner, an antioxidant, an antifoaming agent, a UV absorber, and a light stabilizer, but is not limited thereto. The composition for the first resin layer may further include typical solvents for coatability such as ethanol, propylene glycol monomethyletheracetate, methyl ethyl ketone, and methyl isobutyl ketone, but are not limited thereto.

In one embodiment, the first resin layer 210 may be a non-adhesive layer. when When the first resin layer 210 is non-adhesive, the pattern layer can be stacked on the adherend (that is, on the polarizer) via an adhesive, an adhesive or an adhesive/adhesive.

In another embodiment, the first resin layer 210 may be an adhesive layer. When the first resin layer 210 is an adhesive layer, the pattern layer can be stacked on the adherend without additional adhesive, adhesive, or adhesive/adhesive, thereby allowing the thickness of the polarizing plate to be reduced.

The upper surface of the second resin layer 220 may be a plane adjacent to the protection film 300, and the lower surface thereof may be formed with engraved optical patterns corresponding to the pattern group.

The second resin layer 220 may be a low refractive index pattern layer having a refractive index of about 1.3 to less than about 1.50 (specifically, about 1.3 to about 1.49). Within this range, the polarizing plate can achieve good improvement in viewing angle.

The second resin layer 220 may be formed of a composition for the second resin layer including a curable resin. The curable resin may include at least one selected from UV curable resins and heat curable resins, but is not limited thereto. The composition for the second resin layer may contain at least one selected from the initiators, additives, and solvents described above.

The maximum thickness of the second resin layer 220 may be greater than 0 micrometers to about 50 micrometers or less than 50 micrometers, for example greater than 0 micrometers to about 30 micrometers or less than 30 micrometers. Within this range, the polarizing plate can prevent warping such as curling.

The value obtained by subtracting the maximum height of the optical pattern from the maximum thickness of the second resin layer 220 (maximum thickness of the second resin layer−maximum height of the optical pattern) (also referred to as “net thickness”) may be greater than 0 μm to about 30 microns or less, For example, greater than 0 microns to about 20 microns or less than 20 microns, or greater than 0 microns to about 10 microns or less than 10 microns. Within this range, the second resin layer may provide an effect of increasing surface hardness and may exhibit sufficient adhesion to the protective film.

protective film

A protective film 300 is formed on the light exit surface of the pattern layer 200 to allow light that has passed through the pattern layer 200 to be emitted through the protective film. The protection film 300 may support the pattern layer 200 .

In one embodiment, the protective film 300 may be directly formed on the second resin layer 220 of the pattern layer 200 , thereby allowing the thickness of the polarizing plate 10 to be reduced. Herein, the expression “formed directly on” means that no adhesive layer, adhesive layer or adhesive/adhesive layer is interposed between the protective film 300 and the pattern layer 200 .

The total light transmittance of the protective film 300 in the wavelength band of visible light may be 90% or greater, for example, 90% to 100%. Within this range, the protective layer allows light to be transmitted therethrough without affecting light incident thereon.

The protective film 300 may include an optically transparent resin film including a light incident surface and a light exit surface facing the light incident surface. The protective film may consist of a single layer of the resin film or may consist of a plurality of layers of the resin film. The resin may contain at least one selected from the group consisting of cellulose ester resins containing triacetylcellulose (triacetylcellulose; TAC), cyclic polyolefin resins containing amorphous cyclic olefin polymers (cyclicoolefin polymers; COP), polycarbonate resins, Polyester resins containing polyethylene terephthalate (polyethyleneterephthalate; PET), polyether resins, polyester resins, polyamide resins, polyimide resins, acyclic polyolefin resins, containing Poly(meth)acrylic resins of poly(methyl methacrylate), polyvinyl alcohol resins, polyvinyl chloride resins, and polyvinylidene chloride resins, but not limited thereto.

The protective film may be a non-stretched film, a retardation film obtained by stretching a resin by a certain method to have a certain retardation range, or an isotropic optical film. In one embodiment, the protective film may be an isotropic optical film having a Re of about 0 nm to about 60 nm, specifically about 40 nm to about 60 nm. In this range of Re, the protective film can provide good image quality by compensating the viewing angle. Herein, the term "isotropic optical film" means a film having substantially the same nx, ny, and nz (nz means the refractive index of the film in the thickness direction of the film), and the expression "substantially the same" includes not only The cases where nx, ny, and nz are identical, also include cases where there is an acceptable tolerance. In another embodiment, the protective film may be a retardation film having a Re of about 60 nm or less. For example, Re of the protection film may be about 60 nm to about 500 nm, or about 60 nm to about 300 nm. Alternatively, the protective film may have an Re of about 6,000 nm or greater, about 8,000 nm or greater, specifically about 10,000 nm or greater, more specifically greater than about 10,000 nanometers, more specifically from about 10,100 nanometers to about 30,000 nanometers, more specifically from about 10,100 nanometers to about 15,000 nanometers. Within this range, the protective film can prevent generation of rainbow spots while further diffusing light diffused by the contrast-improving layer.

The protective layer 300 may have a thickness of about 5 microns to about 200 microns, for example, about 30 microns to about 120 microns. Within this thickness range, the protective layer 300 can be used in a polarizing plate.

Although not shown in FIG. 1 , a surface treatment layer, such as a hard coat layer, a scattering layer, may be further formed on at least one surface (at least one of the upper surface and the lower surface) of the protective film 300. , low reflectivity layer, ultra-low reflectivity layer, primer layer, anti-fingerprint layer, anti-reflection layer and anti-glare layer. The surface treatment layer can provide additional functions for the polarizer.

In the case of having a pattern layer on the upper surface of the polarizer, the total light transmittance of the polarizer 10 may be about 40% or more, specifically about 40% to about 50%, and the degree of polarization may be about 95% or greater than 95%, specifically about 95% to about 100%. Within this range, the polarizing plate can be suitably used in a liquid crystal display.

Polarizer

The polarizer 100 may polarize light received from the liquid crystal panel and allow the polarized light to travel to the pattern layer 200 after passing through the polarizer. The polarizer 100 is formed on the light incident surface of the pattern layer 200 .

The polarizer 100 may include a polyvinyl alcohol polarizer obtained by uniaxially stretching a polyvinyl alcohol film, or a polyene-based polarizer obtained by dehydrating a polyvinyl alcohol film. The thickness of the polarizer 100 may be about 5 microns to about 40 microns. Within this range, the polarizer 100 can be used for optical displays.

The polarizer may include a polarizer 100 and a protective film formed on at least one surface of the polarizer. The protective film protects the polarizer, thereby improving the reliability and mechanical strength of the polarizer. The protective film may include a film including the resins mentioned above in the description of the protective film 300 .

Although not shown in Figure 1, an adhesive layer can be further formed on polarized light On the lower surface of the sheet 100 to attach the polarizing plate to the liquid crystal panel.

In one embodiment, the polarizing plate is configured to satisfy the following relationship when applied to a light-condensing backlight unit, thereby ensuring brightness uniformity while improving viewing angles at lateral sides.

<Relationship 1>W _30° >W _45° >W _60°

<Relationship 2>W _60° >0.2

where W _30° is the ratio of the luminance (L 30° ) at the lateral side (30° or -30 _° ) to the luminance (L 0 _° ) at the positive side (0°) in white mode; W _45° is Ratio of luminance (L 45° ) at the lateral side (45° or -45 _° ) to luminance (L 0° ) at the positive side ( ₀ °) in white mode; and W _60° is in white mode The ratio of the luminance (L 60° ) at the lateral side (60° or -60 _° ) to the luminance (L 0° ) at the positive side ( _0° ).

Next, a polarizing plate according to another embodiment of the present invention will be described with reference to FIG. 3 . 3 is a cross-sectional view of a pattern group of a polarizing plate according to another embodiment of the present invention.

Referring to FIG. 3 , the polarizing plate according to this embodiment is substantially the same as the polarizing plate of FIG. 1 except that the pattern portion of the pattern group 240 instead of the pattern group 230 arranged repeatedly is included therein.

The pattern group 240 is composed of a total of two engraved optical patterns including a first pattern 240A and a second pattern 240B, the two engraved optical patterns having no In the case of flat sections, they are arranged continuously. The first pattern 240A and the second pattern 240B have different bottom angles and different aspect ratios.

Referring to FIG. 3 , each of the first pattern 240A and the second pattern 240B has a trapezoidal shape in which inclined planes 241 , 242 are connected to each other by a flat surface at a top portion thereof. However, it should be understood that the present invention is not limited thereto. Alternatively, the engraved optical pattern according to this embodiment may have an N-sided polygonal cross-sectional shape, as described above.

The shape, base angle α1, maximum width W1, maximum height h1, and material of the first pattern 240A may be changed, as described with reference to FIGS. 1 and 2 . The shape, base angle α2, maximum width W2, maximum height h2, and material of the second pattern 240B may be changed, as described with reference to FIGS. 1 and 2 .

Next, a polarizing plate according to still another embodiment of the present invention will be described with reference to FIG. 4 . 4 is a cross-sectional view of a pattern group of a polarizing plate according to still another embodiment of the present invention.

Referring to FIG. 4 , the polarizing plate according to this embodiment is substantially the same as the polarizing plate of FIG. 1 except that the pattern portion of the pattern group 250 instead of the pattern group 230 arranged repeatedly is included therein.

The pattern set 250 further includes a flat segment 251 , a flat segment 252 between the engraved optical pattern 230A, the engraved optical pattern 230B, and the engraved optical pattern 230C. The flat section 251 and the flat section 252 are used to improve the transmittance by suppressing the deterioration of the front brightness.

The flat section 251 and the flat section 252 can be arranged at a periodic interval in the pattern group (that is, the sum of the maximum width of a flat segment and the maximum width of the engraved optical pattern next to the flat segment), the periodic pitch is about 1 micron to about 100 microns, specifically about 3 microns to about 50 Microns. In this range, the polarizing plate can prevent the phenomenon of moiré fringe with the picture element of the liquid crystal panel.

In the pattern set, the ratio of the sum of the maximum widths of the flat segments to the sum of the maximum widths of the engraved optical patterns (W1+W2+W3) may be from about 0 to about 2, for example 0, 0.1, 0.2, 0.3, 0.4 , 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, specifically greater than about 0 to about 2, about 0 to about 1 or greater than about 0 to about 1. Within this range, the polarizing plate can achieve an improvement in the lateral viewing angle.

The maximum width of the flat section 251 and the flat section 252 may be about 1 micron to about 20 microns, specifically about 1 micron to about 10 microns. Within this range, optical patterns may be easily formed while ensuring appropriate transmittance and improvement in viewing angle.

Although FIG. 4 illustrates a polarizing plate in which flat sections 251, 252 are formed between the engraved optical pattern 230A and the engraved optical pattern 230B and between the engraved optical pattern 230B and the engraved optical pattern 230C, the flat sections may be formed in at least one of these regions.

Next, a polarizing plate according to still another embodiment of the present invention will be described with reference to FIG. 5 . FIG. 5 is a cross-sectional view of a polarizing plate according to still another embodiment of the present invention.

Referring to FIG. 5 , the polarizing plate 20 according to this embodiment is substantially the same as the polarizing plate according to the above embodiments except that a pattern layer 260 is included instead of the pattern layer 200 .

In the pattern layer 260, each of the flat section 261 and the flat section 262 are formed between adjacent pattern groups 230 . The flat sections 261, 262 may facilitate pattern formability and may ensure proper transmittance.

In the pattern set 230, the ratio of the width L of the flat section 261, the flat section 262 to the sum (W1+W2+W3) of the maximum width of the engraved optical pattern or the total width of the pattern set 230 may be about 0 to about 1 , such as 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, specifically greater than about 0 to about 1. Within this range, the flat sections 261, 262 may contribute to pattern formability and may secure appropriate transmittance.

In one embodiment, the maximum width (L) of each of the flat sections 261, 262 may be greater than 0 microns to about 200 microns or less than 200 microns, specifically greater than 0 microns to about 100 microns or less than 100 microns. Within this range, the flat sections 261, 262 may contribute to pattern formability and may secure appropriate transmittance.

Next, a polarizing plate according to still another embodiment of the present invention will be described with reference to FIG. 6 . FIG. 6 is a cross-sectional view of a polarizing plate according to still another embodiment of the present invention.

Referring to FIG. 6 , the polarizing plate 30 according to this embodiment is substantially the same as the polarizing plate according to the above embodiments except that a pattern layer 270 is included instead of the pattern layer 200 .

The pattern layer 270 is substantially the same as that of the polarizing plate according to the above embodiment, except that the first resin layer of the pattern layer 270 includes a filling portion at least partially filling the engraved optical pattern. Therefore, the maximum thickness of the first resin layer is greater than the maximum value of the engraved optical patterns in the pattern group.

Next, a bias according to yet another embodiment of the present invention will be described with reference to FIG. 7 Light board. FIG. 7 is a cross-sectional view of a polarizing plate according to still another embodiment of the present invention.

Referring to FIG. 7, the pattern group 280 is composed of at least three optical patterns (ie, a first pattern 280A, a second pattern 280B, and a third pattern 280C) without having a flat section therebetween. arranged continuously. At least two of the first pattern 280A, the second pattern 280B and the third pattern 280C have different base angles α1, α2, α3 and different aspect ratios h1/W1, aspect ratios h2/W2, Aspect ratio h3/W3.

Each of the first pattern 280A, the second pattern 280B, and the third pattern 280C has an inclined surface, wherein the inclined surface 281, the inclined surface 282, and the inclined surface 283 are connected to both the top portion thereof and the maximum width thereof, and are formed by Two planes forming an angle to each other. Although FIG. 7 illustrates an engraved pattern with a hexagonal cross-section, it should be understood that the present invention is not limited thereto.

Although not shown in FIG. 7 , the polarizing plate shown in FIG. 7 may further include such flat sections between pattern groups or inside pattern groups.

Next, a polarizing plate according to still another embodiment will be described.

The polarizing plate according to this embodiment is substantially the same as the polarizing plate according to the above embodiments except that the first resin layer according to this embodiment is a low-refractive index pattern layer having a refractive index lower than that of the second resin layer. same. For a description of the refractive index, refer to FIG. 1 .

A liquid crystal display according to the present invention includes the polarizing plate according to the present invention.

In one embodiment, a liquid crystal display according to the present invention may include a polarizing plate as a viewer disposed at the viewer's side with respect to the liquid crystal panel. side polarizer. The "viewer's side polarizing plate" is a polarizing plate placed on the screen side, that is, a polarizing plate placed on the side opposite to the light source with respect to the liquid crystal panel.

In one embodiment, a liquid crystal display includes a light-concentrating backlight unit, a light source-side polarizer, a liquid crystal panel, and a viewer-side polarizer stacked sequentially in the stated order, wherein the viewer-side polarizer may include a polarizer according to the present invention . The "light source side polarizing plate" is a polarizing plate placed on the light source side.

The light concentrating backlight unit can be composed of a light source, a light guide plate and a light concentrating sheet. In one embodiment, referring to FIG. 9 , the concentrating backlight unit 600 may be composed of a light source 610 , a light guide plate 620 and a concentrating sheet 630 .

The light source 610 and the light guide plate 620 may be light sources and light guide plates commonly used in liquid crystal displays. The light collecting sheet 630 may include a base film and an inverted prism formed on a light incident surface of the base film. The inverted prism may improve light efficiency by totally reflecting light emitted from the light guide plate through a pattern shape. The light collecting sheet may be integrally attached to the light source side polarizing plate of the liquid crystal display.

Although not shown in FIG. 9 , reflective sheets can be further formed on the lower surface of the light guide plate 620 to further improve the luminous efficiency.

The liquid crystal panel can adopt vertical alignment (vertical alignment; VA) mode, IPS mode, patterned vertical alignment (patterned vertical alignment; PVA) mode or super-patterned vertical alignment (super-patterned vertical alignment; S-PVA) mode , but not limited to this.

Next, the present invention will be described in more detail with reference to some examples. It should be noted, however, that these examples are provided for illustration only and should not be construed as limiting in any way make the present invention.

Example 1

The first resin layer (high refractive index layer) was formed of a composition including a UV curable resin (SHIN-AT & C Co., Ltd.) with a refractive index of 1.62. The second resin layer (low-refractive index layer) was formed of a composition including a UV curable resin (Xin'an Chemical Industry) with a refractive index of 1.47.

The coating layer permeates one surface of a polyethylene terephthalate (PET) film (TA044, thickness: 80 μm, Toyobo Co., Ltd.) using the composition for the second resin layer (light incident surface) to a predetermined thickness to form a protective film. The second resin layer is formed on the coating layer by applying an optical pattern to the coating layer using a film having an optical pattern formed thereon, and then performing the process at 500 millijoules/square centimeter (mJ/cm ² ). UV curing. Next, the first resin layer was formed on one surface of the second resin layer by coating the composition for the first resin layer and then UV curing at 500 mJ/cm2. Next, a polarizer having a three-layer structure of PET/PVA/COP was attached to one surface of the first resin layer, thereby preparing a polarizing plate.

Table 1 below shows a pattern group of pattern parts formed at the interface between the first resin layer and the second resin layer. In the pattern section, pattern groups are repeatedly arranged without flat sections, as depicted in FIG. 1 .

Referring to Table 1, the pattern group is composed of a total of three patterns (i.e., a first pattern, a second pattern, and a third pattern), which are sequentially arranged in the stated order without having a flat section in between . The first pattern, the second pattern and the Each of the three patterns is an engraved optical pattern having a trapezoidal cross-section. Each of the first pattern, the second pattern and the third pattern has a bottom corner and an aspect ratio as shown in Table 1. The two bottom corners of each of the first pattern, the second pattern and the third pattern are the same.

Example 2 and Example 3

In the same manner as Example 1, except that the pattern group is composed of three patterns (that is, the first pattern, the second pattern, and the third pattern) arranged sequentially in the stated order without having a flat section A polarizing plate was manufactured, and each of the first pattern, the second pattern, and the third pattern was an engraved trapezoidal pattern and had a base angle and an aspect ratio, as shown in Table 1.

Example 4

A polarizing plate was manufactured in the same manner as in Example 1, except that the pattern group consisted of two patterns, that is, a first pattern and a second pattern sequentially arranged in the stated order without having a flat section, And each of the first pattern and the second pattern is an engraved trapezoidal pattern and has a base angle and an aspect ratio, as shown in Table 1.

Example 5

A polarizing plate was manufactured in the same manner as in Example 1 except that a flat section was formed between the engraved optical patterns in each pattern group. The width of the flat section is 5 microns.

Example 6

A polarizing plate was manufactured in the same manner as in Example 1 except that flat sections were formed between the pattern groups. The width of the flat section is 5 microns.

Example 7

Except that the flat section is formed between the engraved optical patterns in each pattern group (the width of the flat section is 5 micrometers), the flat section is formed between the pattern groups (the width of the flat section is 5 micrometers), and the first A polarizing plate was fabricated in the same manner as in Example 1 except that the refractive indices of the resin layer and the second resin layer were changed (as listed in Table 1).

Example 8

A polarizing plate was manufactured in the same manner as in Example 1 except that the refractive indices of the first resin layer and the second resin layer were changed (as listed in Table 1).

Comparative Example 1 and Comparative Example 2

In the same manner as Example 1, except that the pattern group is composed of three patterns (that is, the first pattern, the second pattern, and the third pattern) arranged sequentially in the stated order without having a flat section A polarizing plate was manufactured, and each of the first pattern, the second pattern, and the third pattern was an engraved trapezoidal pattern and had a base angle and an aspect ratio, as shown in Table 1.

In Comparative Example 1, the aspect ratio of the first pattern, the second pattern and the third pattern is 1.0 and have different base angles. In Comparative Example 2, the base angles of the first pattern, the second pattern and the third pattern are 80° and have different aspect ratios.

Comparative example 3

In the same manner as in Example 1, except that a trapezoidal pattern with an aspect ratio of 1.0 and a base angle of 85° was formed at the interface between the first resin layer and the second resin layer without a flat section Manufacturing polarizers.

Comparative example 4

The first resin layer (low refractive index layer) was formed of a composition including a UV curable resin (Xin'an Chemical Industry) with a refractive index of 1.47. The second resin layer (high refractive index layer) was formed of a composition including a UV curable resin (Shin'an Chemical Industry) with a refractive index of 1.62.

Manufactured in the same manner as Example 1, except that trapezoidal patterns and flat sections each having an aspect ratio of 1.0 and a base angle of 85° were alternately formed at the interface between the first resin layer and the second resin layer polarizer. Trapezoidal patterns have the same aspect ratio and the same base corners. 10 is a cross-sectional view of a polarizing plate of Comparative Example 4. FIG. Referring to FIG. 10 , the polarizer includes a polarizer 100 sequentially stacked in the stated order, a pattern layer 400 including a first resin layer 420 and a second resin layer 410, and a protective film 300, wherein trapezoidal patterns and flat sections are alternately formed At the interface between the first resin layer 420 and the second resin layer 410 .

Models for measuring viewing angles of the polarizing plates of Examples and Comparative Examples were fabricated and viewing angle characteristics were measured at lateral angles shown in Table 1.

Light source side polarizer

Polarizers were fabricated by stretching a polyvinyl alcohol film to three times its original length at 60°C, then dyed with iodine and stretching the dyed film to 2.5 times in a boric acid solution at 40°C. Next, a triacetyl cellulose film (thickness: 80 μm) was bonded to both sides of the polarizer through an adhesive (Z-200, Nippon Goshei Co., Ltd.) for polarizers. surface to make polarizers. The manufactured polarizing plate was used as a light source side polarizing plate.

Viewer side polarizer

As the viewer-side polarizing plate, each of the polarizing plates produced in Examples and Comparative Examples was used.

Modules for LCD Displays

A light source side polarizing plate is attached to the lower surface of the liquid crystal panel and a viewer side polarizing plate is attached to the upper surface thereof. Here, the viewer-side polarizing plate was disposed such that the protective film of the viewer-side polarizing plate was placed at the outermost periphery from the upper surface of the liquid crystal panel. Next, a module for a liquid crystal display was manufactured by placing a light-condensing backlight unit including an inverted prism optical sheet at the lower side of the light source-side polarizing plate. In the white mode, the ratio of the luminance at the lateral side to the luminance at the positive side (0 ^° ) with respect to the light emitted from the concentrating backlight unit can be obtained as shown in the dot-dash diagram of FIG. 8 . The brightness curve indicated by the line. Referring to FIG. 8 , the percentage (W 30° ) of the brightness (L _{30° ) at the lateral side (30°} ) to the brightness (L 0° ) at the positive side ( _{0° )} is 11%, and the lateral side ( The percentage (W 60° ) of the luminance (L _60° ) at 60°) to the luminance (L 0° ) at the positive side ( _{0 °} ) is 0%.

Measured from positive side (0°) to right lateral side (90°) and left lateral side (-90°) in white mode using EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM Co., Ltd.) brightness value.

The ratio of the luminance at the lateral side to the luminance at the positive side (0°) in the white mode was calculated and the results are plotted in FIGS. 11 to 22 .

In white mode, calculate the percentage of the brightness at the lateral side (30°) to the brightness at the positive side (0°), the ratio of the brightness at the lateral side (45°) to the brightness at the positive side (0°) Percentage and the ratio of the brightness at the lateral side (60°) to the brightness at the positive side (0°) The percentages are shown in Table 1.

As shown in Table 1 and FIG. 11 to FIG. 18, the polarizing plate according to the present invention realizes viewing at all lateral sides (30°, 45°, 60°) when applied to a liquid crystal display including a light-concentrating backlight unit Angle improvement with low deviation of viewing angle characteristics at lateral sides (30°, 45°, 60°).

In contrast, the polarizing plate of Comparative Example 1 (in which at least two patterns of the pattern group have different bottom angles and the same aspect ratio) failed to improve viewing angle characteristics at lateral sides (30°, 45°, 60°) , as shown in Table 1 and Figure 19. In addition, the polarizing plate of Comparative Example 2 (in which at least two patterns of the pattern group have different aspect ratios and the same base angle) failed to improve viewing angle characteristics at the lateral side (60°), and at the lateral side (60°) exhibits a larger deviation of the viewing angle characteristics than at the lateral side (30°) and lateral side (45°), as shown in Table 1 and FIG. 20 .

In addition, the polarizing plate of Comparative Example 3 (in which each pattern of the pattern group has the same aspect ratio and the same bottom angle) failed to improve the viewing angle characteristics at the lateral sides (30°, 45°, 60°), And especially at the lateral side (60°), no brightness is exhibited, as shown in Table 1 and FIG. 21 . In addition, the polarizing plate of Comparative Example 4 (in which each pattern of the pattern group has the same aspect ratio and the same bottom angle with a flat section in between) failed to improve the lateral side (30°, 45°, 60° ), and especially at the lateral side (60°), no luminance is exhibited, as shown in Table 1 and FIG. 22 .

(1) A module for a liquid crystal display was fabricated using the polarizing plate of Example 4 in the same manner as the viewing angle in Table 1 was measured. The brightness at the positive side (0°) of the spherical coordinate system was measured in white mode and black mode using EZCONTRASTX88RC (EZXL-176R-F422A4, ELDIM Corporation). Calculated in white mode Ratio of brightness to brightness in black mode (A1).

The ratio of the luminance in the white mode to the luminance in the black mode was calculated in the same manner with respect to a module for a liquid crystal display manufactured in the same manner except that a light source side polarizing plate was attached to both sides of the liquid crystal panel (A2 ).

The percentage (comparison ratio) of A1 and A2 was calculated and shown in Table 2.

As obtained by measuring the luminance values at the lateral side (30°) and the lateral side (60°) instead of measuring the luminance at the positive side (0°), calculate the percentage (contrast ratio) of A1 and A2 and are shown in Table 2.

(2) A module for a liquid crystal display was manufactured using the polarizing plate of Example 4 in the same manner as in Table 1 except that a typical backlight unit including a general prism optical sheet was provided to the lower side of the light source side polarizing plate. In white mode, it can be obtained by calculating and plotting the ratio of the luminance at the lateral side to the luminance at the positive side (0°) with respect to the light emitted from a typical backlight unit, as shown by the solid line of FIG. Indicated brightness curve. Referring to FIG. 8 , the percentage (W 30° ) of the brightness at the lateral side ( _30° ) to the brightness at the positive side (0°) is about 52%, and the brightness at the lateral side (60°) is the same as that at the positive side. The percentage (W _60° ) of brightness at (0°) is about 13%.

W _30° , W _45° and W _60° were calculated in the same manner and shown in Table 2 below and FIG. 23 .

The percentages of A1 and A2 at the positive side (0°), at the lateral side (30°) and at the lateral side (60°) were calculated in the same manner as in (1) and are shown in Table 2 below.

Table 3 shows the percentage values of W _30° and W _60° of the concentrated backlight unit and typical backlight units.

As shown in Table 3, it can be seen that the concentrated backlight unit and the typical backlight unit exhibit completely different luminance curves at 30° laterally and 60° laterally.

As shown in Table 2, it can be seen that when the polarizing plate according to the present invention is applied to a liquid crystal display comprising a light concentrating backlight unit, the liquid crystal display improves Excellent viewing angle characteristics, while improving frontal contrast and lateral contrast.

On the contrary, as shown in Table 2 and FIG. 23 , when the polarizing plate according to the present invention is applied to a liquid crystal display including a typical backlight unit, the liquid crystal display suffers from a reduction in front contrast and presents a side-to-side display compared to a liquid crystal display using a concentrating backlight unit. Towards a smaller improvement in contrast. This result means that the polarizing plate according to the present invention operates efficiently when applied to a liquid crystal display including a light-condensing backlight unit.

Accordingly, the present invention provides a polarizing plate capable of improving brightness, viewing angle, and contrast ratio at front and side sides when applied to a liquid crystal display including a light-condensing backlight unit.

The present invention provides a polarizing plate capable of improving front contrast ratio, side contrast ratio, and appearance when applied to a liquid crystal display including a light-condensing backlight unit.

The present invention provides a polarizing plate capable of reducing the deviation of the ratio of the luminance at the lateral side to the luminance at the positive side depending on the angle of the lateral side when applied to a liquid crystal display including a condensing backlight unit .

The present invention provides a liquid crystal display that includes a light-concentrating backlight unit that can improve brightness, viewing angle, and contrast ratio at the front and lateral sides, and can reduce the lateral side angle depending on the angle of the lateral side. The deviation of the ratio of the luminance at the positive side to the luminance at the positive side.

It should be understood that those skilled in the art can make various modifications, changes, alterations and equivalent embodiments without departing from the spirit and scope of the present invention

10: polarizer

100: Polarizer

200: pattern layer

210: first resin layer

220: second resin layer

230: pattern group

300: protective film

Claims (19)

A polarizer, comprising: a polarizer; and a pattern layer formed on a light exit surface of the polarizer, wherein the pattern layer includes a first resin layer and a second resin layer sequentially formed on the polarizer; The pattern part is formed at the interface between the first resin layer and the second resin layer, and is composed of at least two pattern groups repeatedly arranged in the pattern part, and the at least two pattern groups in the at least two pattern groups are Each includes at least two engraved optical patterns; and the at least two engraved optical patterns in each of the at least two pattern groups have different aspect ratios and different bottom angles, wherein the at least two The aspect ratio of the engraved optical pattern is about 0.3 to about 3.0, the engraved optical pattern extends in a stripe shape in a longitudinal direction thereof, and the pattern groups are identical to each other in the pattern portion. The polarizing plate as described in item 1 of the scope of the patent application, wherein the difference between the maximum aspect ratio and the minimum aspect ratio of the at least two engraved optical patterns in the at least two pattern groups is about 0.5 or greater 0.5. The polarizing plate as described in item 1 of the patent claims, wherein the bottom angle of the at least two engraved optical patterns is about 60° to about 90°. The polarizing plate as described in item 1 of the patent scope of the application, wherein the difference between the maximum base angle and the minimum base angle of the at least two engraved optical patterns in the at least two pattern groups is about 5° or greater than 5° °. The polarizing plate according to claim 1, wherein the at least two engraved optical patterns have a flat surface at a top portion thereof and an N-sided polygon (N is an integer of 4 to 10) cross-sectional shape. The polarizing plate according to claim 1, wherein the at least two engraved optical patterns in the at least two pattern groups are continuously arranged without a flat section therebetween. The polarizing plate as described in claim 1, wherein the flat section does not exist or is otherwise formed between two adjacent pattern groups. The polarizing plate as described in item 1 of the patent scope of the application, wherein when the polarizing plate has an absorption axis of 0°, the distance defined between the longitudinal direction of the at least two engraved optical patterns and the absorption axis of the polarizing plate The angle is in the range of about -20° to about 20°, about 70° to about 110°, or about -70° to about -110°. The polarizing plate according to claim 1, wherein the refractive index of the first resin layer is higher than that of the second resin layer. The polarizing plate according to claim 1, wherein the absolute value of the difference in refractive index between the first resin layer and the second resin layer is about 0.05 or greater than 0.05. The polarizing plate as described in claim 1 of the patent application, wherein the number of the at least two engraved optical patterns in each pattern group is in the range of 2 to 10. The polarizing plate as described in item 1 of the scope of the patent application, wherein each of the at least two pattern groups is composed of the first of the at least two engraved optical patterns The first pattern and the second pattern are composed of a total of two optical patterns, and the first pattern and the second pattern have different bottom angles and different aspect ratios. The polarizing plate according to claim 1, wherein each of the at least two pattern groups is continuously arranged without a flat section therebetween as the at least two engraved optical patterns A total of three optical patterns of the first pattern, the second pattern and the third pattern, and at least two of the first pattern, the second pattern and the third pattern may have different bottom angles and different aspect ratios. The polarizing plate according to claim 1, wherein the first resin layer is a filling portion filling at least part of the at least two engraved optical patterns or a layer including the filling portion. The polarizing plate according to claim 1 of the scope of the patent application further includes: a protective film stacked on at least one of the light exiting surface and the light incident surface of the pattern layer. The polarizing plate as described in item 15 of the scope of the patent application, further comprising: at least one surface treatment layer selected from a hard coating layer, a scattering layer, a low reflectivity layer, and an ultra-low reflectivity layer on at least one surface of the protective film. layer, primer layer, anti-fingerprint layer, anti-reflection layer and anti-glare layer. A liquid crystal display, comprising the polarizing plate described in any one of the first to sixteenth items in the scope of the patent application. The liquid crystal display described in item 17 of the scope of the patent application includes: a backlight unit, a polarizer on the light source side, a liquid crystal panel and The polarizing plate, wherein the backlight unit includes a light-condensing backlight unit, and the light-condensing backlight unit includes an inverted prism sheet. The liquid crystal display as described in item 18 of the patent scope of the application, wherein, in the white mode of the light concentrating backlight unit, the brightness (L _{30° ) at the lateral side (30° or -30°} ) is different from that of the positive side ( The ratio of the brightness (L _0° ) at 0°) (W _30° = L _30° /L _0° ) is in the range of about 0.1 to about 0.5, and the brightness at the lateral side (60° or -60°) The ratio (W _{60 ° =L 60°} /L _{0 °} ) of (L ₆₀ ° ) to the luminance (L 0° ) at the positive side (0°) is in the range of about 0 to about 0.1.