KR20070080129A - Optical film assembly and liquid crystal display having the same - Google Patents

Abstract

An optical film assembly and an LCD(Liquid Crystal Display) comprising the same are provided to wide a viewing angle of the LCD, by forming the optical film assembly to include an optical film, a polarizing plate, and a lambda/4 retardation plate properly disposed. An optical film has a first axis and a second axis. The optical film satisfies the following equation; nxny≒nz, wherein, nx denotes a refractive index in the first axis, ny denotes a refractive index in the second axis, and nz denotes a refractive index in a Z-axis. A polarizing plate has a transmission axis and an absorption axis. A lambda/4 retardation plate is positioned between the optical film and the polarizing plate. The lambda/4 retardation plate has the first axis and the second axis. The transmission axis of the polarizing plate and the first axis of the lambda/4 retardation plate make an angle of 35 to 55 degrees.

Description

Optical film assembly and liquid crystal display having the same

1 is a schematic cross-sectional view of a liquid crystal display according to a first embodiment of the present invention.

2 is a schematic plan view illustrating upper and lower substrates of a liquid crystal display according to a first exemplary embodiment of the present invention.

3A to 3C are graphs showing viewing angles of the liquid crystal display according to the first exemplary embodiment of the present invention.

4 is a schematic plan view illustrating upper and lower substrates of a liquid crystal display according to a second exemplary embodiment of the present invention.

5A to 5E are graphs illustrating a viewing angle of the liquid crystal display according to the second exemplary embodiment of the present invention.

6A to 6C are graphs showing light transmittances of the liquid crystal display according to the second exemplary embodiment of the present invention.

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

100: lower substrate 200: upper substrate

110: thin film transistor substrate 210: color filter substrate

120, 220: A plate 130, 230: lambda / 4 phase difference plate

140, 240: polarizer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical film assembly and a liquid crystal display device including the same, and more particularly, to a liquid crystal display device using a optical film assembly including a polarizing plate, a λ / 4 retardation plate, and an A plate.

Liquid crystal displays (LCDs) display a desired image by applying an electric field to a liquid crystal material having an anisotropic dielectric constant injected between two substrates, and controlling the amount of light transmitted through the substrate by adjusting the intensity of the electric field. Device.

The liquid crystal display device according to the related art includes a liquid crystal display panel including a thin film transistor substrate, a color filter substrate, and a liquid crystal layer positioned between the thin film transistor substrate and the color filter substrate, and above and below the liquid crystal display panel. In general, a predetermined optical film including a polarizing plate is positioned.

In this case, as a method for securing a viewing angle of the liquid crystal display, an alignment layer for defining an alignment direction of the liquid crystal material is formed inside the two substrates to rub the alignment layer in a predetermined direction, and the liquid crystal of the liquid crystal display device. Many methods are used to form layers from liquid crystal materials with negative dielectric anisotropy.

In the upper, lower, left and right of the liquid crystal display having such a structure, the contrast ratio is maintained at 1:10 or more even at 80 ° or more, but the contrast ratio is not maintained at 1:10 or more at 45 ° to 50 ° or more in the diagonal direction. .

That is, the liquid crystal display according to the related art as described above has a problem that the viewing angle is narrow in a predetermined direction.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a liquid crystal display device having a wider viewing angle using an optical film assembly including a polarizing plate, a λ / 4 retardation plate, and an A plate.

According to an aspect of the present invention for achieving the object of the present invention, in the optical film assembly used in the vertical alignment mode liquid crystal display panel,

nz(여기서, nx는 제1 축의 광굴절율, ny는 제2 축의 광굴절율, nz는 z축의 광굴절율)을 만족하는 광학 필름; 투과축과 흡수축을 가지는 편광판; 및 상기 광학 필름과 편광판 사이에 위치하며, 제1 축과 제2 축을 가지는 λ/4 위상차판을 포함하고, 상기 편광판의 투과축과 λ/4 위상차판의 제1 축은 35° 내지 55°의 각도를 가지는 것을 특징으로 하는 광학 필름 어셈블리가 제공된다. Having a first axis and a second axis, nx ≠ ny

an optical film satisfying nz (where nx is an optical refractive index on the first axis, ny is an optical refractive index on the second axis, and nz is an optical refractive index on the z axis); A polarizing plate having a transmission axis and an absorption axis; And a [lambda] / 4 retardation plate positioned between the optical film and the polarizing plate and having a first axis and a second axis, wherein the transmission axis of the polarizing plate and the first axis of the [lambda] / 4 retardation plate are angles of 35 [deg.] To 55 [deg.]. There is provided an optical film assembly having a.

The refractive index of the light on the first axis of the optical film and the λ / 4 retardation plate is higher than the refractive index of the light on the second axis of the plate.

The first axis of the λ / 4 retardation plate and the first axis of the optical film have an angle of −5 ° to 5 °, or 85 ° to 95 °.

The retardation value ((nx-ny) x thickness of the optical film) of the said optical film is 100 nm or less, It is characterized by the above-mentioned.

According to another aspect of the present invention for achieving the object of the present invention, there is provided a liquid crystal layer between a pair of substrates and the liquid crystal layer, the liquid crystal layer comprising a liquid crystal material having a negative dielectric anisotropy; A pair of polarizing plates sandwiching the liquid crystal display panel; A pair of λ / 4 retardation plates positioned between the polarizing plate and the liquid crystal display panel and having a first axis and a second axis; And a pair of optical films positioned between the λ / 4 retardation plate and the liquid crystal display panel, respectively, having a first axis and a second axis.

nz(여기서, nx는 제1 축의 광굴절율, ny는 제2 축의 광굴절율, nz는 z축의 광굴절율)을 만족하고, 상기 서로 인접하는 편광판의 투과축과 λ/4 위상차판의 제1 축은 35° 내지 55°의 각도를 가지는 것을 특징으로 하는 액정 표시 장치가 제공된다. The optical film is nx ≠ ny

nz (where nx is the optical refractive index of the first axis, ny is the optical refractive index of the second axis, nz is the optical refractive index of the z axis), and the transmission axis of the adjacent polarizing plates and the first axis of the λ / 4 retardation plate are 35 There is provided a liquid crystal display device having an angle of ° to 55 °.

The refractive index of the light on the first axis of the optical film and the λ / 4 retardation plate is higher than the refractive index of the light on the second axis of the plate.

The pair of substrates are rubbed to define an orientation direction of the liquid crystal material positioned between the substrates, wherein the rubbing axis of the substrate and the first axis of the at least one optical film or the λ / 4 retardation plate are the same. It is done.

The transmission axes of the pair of polarizing plates are orthogonal to each other, the first axis of the pair of optical films is orthogonal to each other, and the first axis of the pair of λ / 4 retardation plates is orthogonal to each other.

The first axis of any one lambda / 4 retardation plate and the first axis of any one of the optical film has an angle of -5 ° to 5 °, or 85 ° to 95 °.

The rubbing axis of the substrate and the transmission axis of any one polarizing plate is characterized by having an angle of 5 ° to 25 °.

The retardation value ((nx-ny) x thickness of the optical film) of the said optical film is 50 nm or less, It is characterized by the above-mentioned.

The rubbing axis of the substrate and the transmission axis of any one polarizing plate is characterized in that the angle of 35 ° to 55 °.

The retardation value ((nx-ny) x thickness of the optical film) of the said optical film is 100 nm or less, It is characterized by the above-mentioned.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Like numbers refer to like elements in the figures.

The present invention relates to a liquid crystal display device that widens the viewing angle by using an optical film assembly including a polarizing plate, a λ / 4 retardation plate, and an A plate.

1 is a schematic cross-sectional view of a liquid crystal display according to a first embodiment of the present invention.

Referring to FIG. 1, the liquid crystal display according to the first exemplary embodiment of the present invention includes a liquid crystal display panel including a thin film transistor substrate 110 and a color filter substrate 210, and an upper portion of the liquid crystal display panel. And a pair of optical film assemblies respectively positioned below. The optical film assembly includes polarizing plates 140 and 240, lambda / 4 phase difference plates 130 and 230, and A plates 120 and 220.

Here, the liquid crystal display panel includes a liquid crystal layer (not shown) between the thin film transistor substrate 110 and the color filter substrate 210, wherein the liquid crystal layer has negative dielectric anisotropy, that is, a dielectric constant in the longitudinal direction. It is preferable that the liquid crystal material has a larger dielectric constant in the thickness direction.

The liquid crystal molecules are in the form of rugby holes, and in particular, liquid crystal molecules having negative dielectric anisotropy lie toward the surface where an electric field is formed, and the liquid crystal molecules transmit light in the thickness direction with little transmission of light in the longitudinal direction. It has a characteristic to make.

That is, when no electric field is formed between the pixel electrode formed on the thin film transistor substrate 110 and the common electrode formed on the color filter substrate 210, the liquid crystal molecules therebetween stand in a direction perpendicular to the substrate to emit light. If the electric field is formed between the pixel electrode and the common electrode, the liquid crystal molecules lie down according to the intensity of the electric field to transmit light.

An alignment layer (not shown) for aligning the liquid crystal material is formed on a surface where the thin film transistor substrate 110 and the color filter substrate 210 face each other. In addition, it is preferable to determine the direction in which the liquid crystal material lies down by performing a rubbing treatment on the alignment layer. That is, in the liquid crystal display, when an electric field is formed between the thin film transistor substrate 110 and the color filter substrate 210, the liquid crystal material is laid down in the rubbing direction according to the strength of the formed electric field.

The polarizing plates 140 and 240 have a transmission axis and an absorption axis, and the polarizing plates 140 and 240 transmit only light that vibrates in the transmission axis. In this case, the transmission axes of the pair of polarizing plates 140 and 240 are configured to be perpendicular to each other.

The λ / 4 retardation plates 130 and 230 have a slow axis having a relatively high refractive index and a fast axis having a relatively low refractive index. The λ / 4 retardation plates 130 and 230 have a function of changing linearly polarized light into circularly polarized light and circularly polarized light into linearly polarized light. At this time, the slow axes of the pair of λ / 4 retardation plates 130 and 230 are configured to be orthogonal to each other.

nz 의 관계를 가진다. 또한, 상기 A 플레이트(120, 220)에서 x축(슬로우축)은 y축(패스트축)에 비해 광의 굴절율이 높다. 상기 A 플레이트(120, 220)는 상기 광굴절율(nx, ny, nz)에 따라 입사된 광을 굴절시키는 기능을 가진다. 이때, 상기 한 쌍의 A 플레이트(120, 220)의 슬로우축은 서로 직교하도록 구성된다. The A plates 120 and 220 have predetermined optical refractive indices nx, ny, and nz, respectively, on the x-axis, the y-axis, and the vertical z-axis of the A plate (where nx is the optical refractive index of the x-axis, and ny is the the optical refractive index of the y-axis, nz is the optical refractive index of the z-axis), nx ≠ ny

has a relationship of nz. In addition, in the A plates 120 and 220, the x-axis (slow axis) has a higher refractive index than the y-axis (fast axis). The A plates 120 and 220 have a function of refracting incident light according to the light refractive indices nx, ny and nz. In this case, the slow axes of the pair of A plates 120 and 220 are configured to be perpendicular to each other.

Next, referring to the upper and lower substrates 100 and 200 illustrated in FIG. 2, the polarizing plates 140 and 240, the λ / 4 retardation plates 130 and 230, and the A plates 120 and 220 are included. The optical film assembly will be described in more detail.

The liquid crystal display according to the first exemplary embodiment of the present invention includes a lower substrate 100 formed of a thin film transistor substrate 110 and an optical film assembly, and an upper substrate 200 formed of a color filter substrate 210 and an optical film assembly. Can be divided into

2, in the upper substrate 200, the rubbing axis of the color filter substrate 210, the transmission axis of the polarizing plate 240, the slow axis of the λ / 4 retardation plate 230, and the slow axis of the A plate 240 are illustrated. In the lower substrate 100, the rubbing axis of the thin film transistor substrate 110, the transmission axis of the polarizing plate 140, the slow axis of the λ / 4 retardation plate 130, and the slow axis of the A plate 140 can be seen. have.

First, the left side of the thin film transistor substrate 110 is rubbed in an upward direction of the substrate, and the right side is rubbed in a downward direction. In addition, the color filter substrate 210 is rubbed in a direction opposite to the thin film transistor substrate 110. That is, the rubbing axes of the thin film transistor substrate 110 and the color filter substrate 210 are vertical.

Here, looking at the upper substrate 200, the transmission axis of the polarizing plate 240 is 15 ± 10 °, preferably 15 ° and the rubbing axis. In addition, the transmission axes of the polarizing plates 140 of the lower substrate 100 paired with the polarizing plates 240 of the upper substrate 200 are perpendicular to each other. That is, the transmission axis of the polarizing plate 140 of the lower substrate 100 is 105 ± 10 °, preferably 105 ° with the rubbing axis.

In addition, the slow axis of the λ / 4 retardation plate 230 in the upper substrate 200 is 45 ± 10 °, preferably 45 ° with the transmission axis of the polarization axis 240. Further, the slow axes of the λ / 4 retardation plate 130 of the lower substrate 100 paired with the λ / 4 retardation plate 230 of the upper substrate 200 are perpendicular to each other. At this time, the slow axis of the λ / 4 retardation plate (130, 230) is expected to greatly improve the viewing angle even if the addition of the A plate (120, 220) in the range other than 45 ± 10 ° and the transmission axis of the polarization axis (140, 240) it's difficult.

Next, light transmittance and color coordinates according to angles of the slow axes of the λ / 4 retardation plates 130 and 230 and the transmission axes of the polarization axes 140 and 240 will be described with reference to Table 1 below.

As shown in Table 1, when the angle between the slow axis of the λ / 4 retardation plates 130 and 230 and the transmission axis of the polarization axes 140 and 240 is an angle other than 45 °, the light transmittance falls and the color coordinates Wx and Wy are decreased. It is greatly outside the normal range of 0.30 to 0.32.

In addition, the slow axis of the A plate 220 in the upper substrate 200 is 0 ± 5 ° or 90 ± 5 °, preferably 0 ° or 90 ° with the slow axis of the λ / 4 retardation plate 230. . In addition, the slow axes of the A plate 120 of the lower substrate 100 paired with the A plate 220 of the upper substrate 200 are perpendicular to each other. In this case, the slow axis of the A plate 220 is in the range other than 0 ± 5 ° or 90 ± 5 ° with the slow axis of the λ / 4 retardation plate 230, so that it is difficult to expect a viewing angle improvement effect.

Next, the change in the viewing angle according to the retardation Δnd of the A plates 120 and 220 will be described in detail with reference to FIGS. 3A to 3C.

3A to 3C are graphs showing viewing angles of the liquid crystal display according to the first exemplary embodiment of the present invention.

The delay values of the A plates 120 and 220 are calculated as (nx −ny) × d, where nx is the optical refractive index of the x axis (slow axis), ny is the optical refractive index of the y axis (fast axis), and d is 3A shows the viewing angle when the delay value of the A plate is 50 nm, and FIG. 3C shows the case where the delay value of the A plate is 75 nm.

Referring to FIG. 3A, the contrast ratio is maintained at 1:10 or more even at 80 ° or more in the up, down, left, and right directions, but the contrast ratio is maintained at 1:10 or more at a viewing angle within approximately 50 ° in the diagonal direction.

Referring to FIG. 3B, the contrast ratio is maintained at 1:10 or more even at 80 ° or more in the up, down, left and right, respectively. At this time, the axis of the wide viewing angle is slightly inclined to the left side as compared with FIG. 3A. In the diagonal direction, the contrast ratio is maintained at 1:10 or more at a viewing angle within approximately 55 °.

Referring to FIG. 3C, the contrast ratio is maintained at 1:10 or more even at 80 ° or more in the diagonal direction. That is, the axis in the direction of wide viewing angle is inclined slightly to the left compared to FIG. 3B. In the up, down, left, and right directions, the contrast ratio is maintained at 1:10 or more at a viewing angle within approximately 60 °.

That is, referring to FIGS. 3A to 3C, it can be seen that the viewing angle gradually increases as the delay value of the A plate increases.

 Next, the light transmittance according to the delay value of the A plate will be described in detail with reference to Table 2.

Referring to Table 2, when the delay value of the A plate exceeds 50 nm, the light transmittance drops sharply, making it difficult to apply to the liquid crystal display device.

nz(여기서, nx는 x축(슬로우축)의 광굴절율, ny는 y축(패스트축)의 광굴절율, nz는 z축의 광굴절율)을 만족하는 A 플레이트와, 투과축과 흡수축을 가지는 편광판과, 상기 A 플레이트와 편광판 사이에 위치하며, 슬로우축과 패스트축을 가지는 λ/4 위상차판을 포함하는 광학 필름 어셈블리를 액정 표시 패널에 위치시켜서 액정 표시 장치의 시야각을 넓힐 수 있다. That is, the liquid crystal display according to the first embodiment of the present invention has a slow axis and a fast axis, and nx ≠ ny

A plate satisfying nz (where nx is the optical refractive index of the x axis (slow axis), ny is the optical refractive index of the y axis (fast axis), nz is the optical refractive index of the z axis), a polarizing plate having a transmission axis and an absorption axis, The optical film assembly including a λ / 4 retardation plate positioned between the A plate and the polarizing plate and having a slow axis and a fast axis may be positioned on the liquid crystal display panel to widen the viewing angle of the liquid crystal display device.

Next, a liquid crystal display according to a second exemplary embodiment of the present invention will be described in detail with reference to FIG. 4.

The liquid crystal display according to the second embodiment of the present invention shown in FIG. 4 differs from the first embodiment only in that the transmission axis of the polarizing plate and the angle of the λ / 4 retardation plate are different. 4 is a schematic plan view illustrating upper and lower substrates of a liquid crystal display according to a second exemplary embodiment of the present invention.

Referring to FIG. 4, in the upper substrate 200, the rubbing axis of the color filter substrate 210, the transmission axis of the polarizing plate 240, the slow axis of the λ / 4 retardation plate 230, and the slow axis of the A plate 240 are illustrated. In the lower substrate 100, the rubbing axis of the thin film transistor substrate 110, the transmission axis of the polarizing plate 140, the slow axis of the λ / 4 retardation plate 130, and the slow axis of the A plate 140 can be seen. have.

The left side of the thin film transistor substrate 110 is rubbed in an upward direction of the substrate, and the right side is rubbed in a downward direction. In addition, the color filter substrate 210 is rubbed in a direction opposite to the thin film transistor substrate 110.

Here, looking at the upper substrate 200, the transmission axis of the polarizing plate 240 is 45 ± 10 °, preferably 45 ° and the rubbing axis. In addition, the transmission axes of the polarizing plates 140 of the lower substrate 100 paired with the polarizing plates 240 of the upper substrate 200 are perpendicular to each other. That is, the transmission axis of the polarizing plate 140 of the lower substrate 100 is 135 ± 10 °, preferably 135 ° with the rubbing axis.

In addition, the slow axis of the λ / 4 retardation plate 230 in the upper substrate 200 is 45 ± 10 °, preferably 45 ° with the transmission axis of the polarization axis 240. Further, the slow axes of the λ / 4 retardation plate 130 of the lower substrate 100 paired with the λ / 4 retardation plate 230 of the upper substrate 200 are perpendicular to each other. At this time, the slow axis of the λ / 4 retardation plate (130, 230) is expected to greatly improve the viewing angle even if the addition of the A plate (120, 220) in the range other than 45 ± 10 ° and the transmission axis of the polarization axis (140, 240) it's difficult.

In addition, the slow axis of the A plate 220 in the upper substrate 200 is 0 ± 5 ° or 90 ± 5 °, preferably 0 ° or 90 ° with the slow axis of the λ / 4 retardation plate 230. . In addition, the slow axes of the A plate 120 of the lower substrate 100 paired with the A plate 220 of the upper substrate 200 are perpendicular to each other. In this case, the slow axis of the A plate 220 is in the range other than 0 ± 5 ° or 90 ± 5 ° with the slow axis of the λ / 4 retardation plate 230, so that it is difficult to expect a viewing angle improvement effect.

Next, the change in the viewing angle according to the retardation Δnd of the A plates 120 and 220 will be described in detail with reference to FIGS. 5A to 5E. 5A to 5E are graphs illustrating a viewing angle of the liquid crystal display according to the second exemplary embodiment of the present invention.

The delay values of the A plates 120 and 220 are calculated as (nx −ny) × d, where nx is the optical refractive index of the x axis (slow axis), ny is the optical refractive index of the y axis (fast axis), and d is 5A shows a case where the A plate has a delay of 50 nm, FIG. 5C shows a case where the A plate has a delay of 75 nm, and FIG. 5D shows a delay of the A plate of 82.5. In the case of nm, FIG. 5E shows the viewing angle when the delay value of the A plate is 100 nm.

Referring to FIG. 5A, when there is no A plate, the contrast ratio is maintained at 1:10 or more even at 80 ° or more in the diagonal direction, and the contrast ratio is 1: 1 only at a viewing angle within about 45 ° in the up, down, left, and right directions. 10 or more is maintained.

Referring to FIG. 5B, when the delay value of the A plate is 50 nm, the contrast ratio is maintained at 1:10 or more even at 80 ° or more in the up, down, left, and right directions, respectively, and the contrast ratio is approximately 55 ° or less in the diagonal direction. It stays above 1:10. At this time, the axis of the wide viewing angle is slightly inclined to the right as compared with FIG. 5A.

Referring to FIG. 5C, when the delay value of the A plate is 75 nm, the contrast ratio is maintained at 1:10 or more even at 80 ° or more in the up, down, left, and right directions, respectively, and at a viewing angle within approximately 65 ° in the diagonal direction. Is kept above 1:10. At this time, the axis of the wide viewing angle is inclined slightly to the right as compared with FIG. 5B.

Referring to FIG. 5D, when the delay value of the A plate is 82.5 nm, the contrast ratio is maintained at 1:10 or more even at 80 ° or more in the up, down, left and right directions, respectively, and the viewing angle within approximately 65 ° in the diagonal direction. The contrast ratio is kept above 1:10. At this time, the axis of the wide viewing angle is inclined slightly to the right as compared with FIG. 5C.

Referring to FIG. 5E, when the delay value of the A plate is 100 nm, the contrast ratio is maintained at 1:10 or more even in the up, down, left, and right directions at 80 ° or more, respectively, and at a viewing angle within approximately 60 ° in the diagonal direction. Contrast ratio is maintained above 1:10. At this time, the axis of the wide viewing angle is inclined slightly to the right as compared with FIG. 5D.

That is, referring to FIGS. 5A to 5E, it can be seen that the viewing angle gradually increases as the delay value of the A plate increases.

Next, the light transmittance according to the delay value of the A plate will be described in detail with reference to FIGS. 6A to 6C. 6A to 6C are graphs showing light transmittances of the liquid crystal display according to the second exemplary embodiment of the present invention.

In the graph, the x axis represents a voltage applied between the pixel electrode of the thin film transistor substrate and the common electrode of the color filter substrate, and the y axis represents the light transmittance of the liquid crystal display according to the second embodiment of the present invention. 6b shows the light transmittance when the delay value of the A plate is 50 nm when there is no A plate, and FIG.

6A to 6C, it can be seen that in the liquid crystal display according to the second exemplary embodiment of the present invention, the light transmittance according to the delay value of the A plate is hardly changed. This is because the rubbing axis coincides with the slow axis of the at least one λ / 4 retardation plate and the A plate, as shown in FIG. 4.

In addition, the light transmittance according to the cell gap, which is the delay value of the A plate and the gap between the thin film transistor substrate 110 and the color filter substrate 210, is hardly changed as shown in Tables 3 to 5. Table 3 shows the absence of the A plate, Table 4 shows the light transmittance when the A plate has a retardation value of 50 nm and Table 5 shows the retardation value of the A plate at 75 nm.

Referring to Tables 3 to 5, it can be seen that in the liquid crystal display according to the second embodiment of the present invention, the light transmittance according to the delay value of the A plate is hardly changed regardless of the change in the cell gap. It can also be seen that the color coordinate also hardly changes in the normal range of 0.30 to 0.32.

As described above, the liquid crystal display according to the second embodiment of the present invention has almost no change in light transmittance according to the delay value of the A plate. Therefore, the delay value of the A plate may be increased to 100 nm or more as necessary.

nz(여기서, nx는 x축(슬로우축)의 광굴절율, ny는 y축(패스트축)의 광굴절율, nz는 z축의 광굴절율)을 만족하는 A 플레이트와, 투과축과 흡수축을 가지는 편광판과, 상기 A 플레이트와 편광판 사이에 위치하며, 슬로우축과 패스트축을 가지는 λ/4 위상차판을 포함하는 광학 필름 어셈블리를 액정 표시 패널에 위치시키며, 상기 편광판의 투과축과 λ/4 위상차판의 슬로우축을 45±10°, 바람직하게는 45°로 하여 액정 표시 장치의 시야각을 넓힐 수 있다. That is, the liquid crystal display according to the second embodiment of the present invention has a slow axis and a fast axis, and nx ≠ ny

A plate satisfying nz (where nx is the optical refractive index of the x axis (slow axis), ny is the optical refractive index of the y axis (fast axis), nz is the optical refractive index of the z axis), a polarizing plate having a transmission axis and an absorption axis, And an optical film assembly positioned between the A plate and the polarizing plate, the optical film assembly including a λ / 4 retardation plate having a slow axis and a fast axis on the liquid crystal display panel, and transmitting the transmission axis of the polarizing plate and the slow axis of the λ / 4 retardation plate. It is possible to widen the viewing angle of the liquid crystal display device by setting it to 45 ± 10 °, preferably 45 °.

The scope of the present invention is not limited to each embodiment described above, but all changes and improvements made by those skilled in the art using the basic concept of the present invention defined in the claims also belong to the scope of the present invention.

nz(여기서, nx는 x축(슬로우축)의 광굴절율, ny는 y축(패스트축)의 광굴절율, nz는 z축의 광굴절율)을 만족하는 A 플레이트와, 투과축과 흡수축을 가지는 편광판과, 상기 A 플레이트와 편광판 사이에 위치하며, 슬로우축과 패스트축을 가지는 λ/4 위상차판을 포함하는 광학 필름 어셈블리를 사용하여 시야각을 높일 수 있다. As described above, the liquid crystal display according to the present invention has a slow axis and a fast axis, and nx ≠ ny

A plate satisfying nz (where nx is the optical refractive index of the x axis (slow axis), ny is the optical refractive index of the y axis (fast axis), nz is the optical refractive index of the z axis), a polarizing plate having a transmission axis and an absorption axis, The viewing angle may be increased by using an optical film assembly positioned between the A plate and the polarizing plate and including a λ / 4 retardation plate having a slow axis and a fast axis.

In addition, the transmission axis of the polarizing plate and the slow axis of the λ / 4 retardation plate may be 45 ± 10 °, and preferably 45 °, thereby widening the viewing angle of the liquid crystal display without changing transmittance and color coordinates.

Claims (13)

In the optical film assembly used for the vertical alignment mode liquid crystal display panel, Having a first axis and a second axis, nx ≠ ny

an optical film satisfying nz (where nx is an optical refractive index on the first axis, ny is an optical refractive index on the second axis, and nz is an optical refractive index on the z axis); A polarizing plate having a transmission axis and an absorption axis; And Located between the optical film and the polarizing plate, including a lambda / 4 phase difference plate having a first axis and a second axis, And a transmission axis of the polarizing plate and a first axis of the λ / 4 phase difference plate have an angle of 35 ° to 55 °. The method according to claim 1, And the refractive index of the light of the first axis of the optical film and the λ / 4 retardation plate is higher than the refractive index of the light of the second axis of the plate. The method according to claim 2, And the first axis of the λ / 4 retardation plate and the first axis of the optical film have an angle of −5 ° to 5 °, or 85 ° to 95 °. The method according to claim 3, The retardation value ((nx-ny) x thickness of an optical film) of the said optical film is 100 nm or less, The optical film assembly characterized by the above-mentioned. A liquid crystal display panel having a pair of substrates and a liquid crystal layer therebetween, the liquid crystal layer comprising a liquid crystal material having negative dielectric anisotropy; A pair of polarizing plates sandwiching the liquid crystal display panel; A pair of λ / 4 retardation plates positioned between the polarizing plate and the liquid crystal display panel and having a first axis and a second axis; And A pair of optical films positioned between the λ / 4 retardation plate and the liquid crystal display panel and having a first axis and a second axis, The optical film is nx ≠ ny

nz (where nx is the optical refractive index of the first axis, ny is the optical refractive index of the second axis, nz is the optical refractive index of the z axis), and the transmission axis of the adjacent polarizing plates and the first axis of the λ / 4 retardation plate are 35 Liquid crystal display device having an angle of ° to 55 °. The method according to claim 5, And a refractive index of light of the first axis of the optical film and the λ / 4 retardation plate is higher than that of the light of the second axis of the plate. The method according to claim 6, The pair of substrates are rubbed to define an orientation direction of the liquid crystal material positioned between the substrates, And a rubbing axis of the substrate and a first axis of at least one optical film or a λ / 4 retardation plate. The method according to claim 6, A transmission axis of the pair of polarizing plates is orthogonal to each other, a first axis of the pair of optical films is orthogonal to each other, and a first axis of the pair of λ / 4 retardation plates is orthogonal to each other. The method according to claim 8, The first axis of any one of the lambda / 4 retardation plate and the first axis of any one of the optical film has an angle of -5 ° to 5 °, or 85 ° to 95 °. The method according to claim 9, The rubbing axis of the substrate and the transmission axis of any one polarizing plate has an angle of 5 ° to 25 °, the liquid crystal display device. The method according to claim 10, The retardation value ((nx-ny) x thickness of an optical film) of the said optical film is 50 nm or less, The liquid crystal display device characterized by the above-mentioned. The method according to claim 9, The rubbing axis of the substrate and the transmission axis of any one polarizing plate has an angle of 35 ° to 55 °, characterized in that the liquid crystal display device. The method according to claim 12, The retardation value ((nx-ny) x thickness of an optical film) of the said optical film is 100 nm or less, The liquid crystal display device characterized by the above-mentioned.

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