CN102483537A - In-plane switching mode liquid crystal display - Google Patents

Abstract

The present invention relates to an in-plane switching mode liquid crystal display. More precisely, the present invention relates to an in-plane switching mode liquid crystal display including a first polarizing plate, a second polarizing plate and a liquid crystal cell, designed to have wide viewing angle and to be economical, because the optical properties of the compensation film are determined by changes of the polarization state of liquid crystal alignment on a Poincare Sphere, and the contrast in the inclined visual direction is improved due to a slow axis of a compensation film of the first polarizing plate to be parallel to the liquid crystal alignment and to an absorption axis of a polarizer. The present invention can implement mass production of thin liquid crystal displays with high yield (reducing defect ratio due to foreign substances or impurities) and can provide a very large liquid crystal display with its possibility to produce larger, coupled polarizing plate since it is possible to ensure a wide viewing angle with only one sheet of compensation film for the upper polarizing plate and the lower polarizing plate.

Description

In-plane-switching mode LCD

Technical field

The present invention relates to a kind of in-plane-switching mode LCD, through improving the contrast at the inclination visual direction, it can guarantee wide visual angle.

Background technology

LCD (LCDs) is widely used as the normal image display.Although it has the characteristic of multiple excellence,, narrow visual angle is used as defective and points out.

The pattern of LCD can be classified according to the initial arrangement of liquid crystal cell, the structure of electrode and the performance of liquid crystal, and the pattern of the most frequently used LCD is twisted-nematic (TN) pattern, homeotropic alignment (VA) pattern and face intra (IPS) pattern.

In addition; According to printing opacity whether when not accepting voltage; It is divided into normal black pattern and normal white mode, and according to the zone and the initial arrangement of liquid crystal, the VA pattern is divided into PVA (image homeotropic alignment) pattern, SPVA (super graph is as homeotropic alignment) pattern and MVA (multizone homeotropic alignment) pattern; And the IPS pattern is divided into S-IPS pattern (super intra) pattern or FFS (fringing field switching) pattern.

When liquid crystal molecule was not activated, in-plane-switching mode had evenly and is basically parallel to the arrangement of substrate surface.When the direction of the light transmission shaft of lower polarizing plate and the fast axle of liquid crystal molecule is identical, because the optical property of liquid crystal, even on the inclined-plane; The light transmission shaft of liquid crystal is identical with the direction of fast axle; Therefore, though after light passes lower polarizing plate through liquid crystal, the variation of polarization state can not take place yet; Thereby it can pass liquid crystal layer and not change.Therefore, through can under unactivated state, showing black state to a certain degree at the upper surface of base material and the arrangement of the polarization plates on the lower surface.

Such in-plane-switching mode LCD does not use under the situation of blooming usually just can realize wide visual angle, makes it have and when guaranteeing the transmittance of nature, is provided on the whole screen advantage of image quality and visual angle uniformly.Therefore, said in-plane-switching mode LCD is mainly used in the high-end display more than 18 inches.

Use the LCD of the in-plane-switching mode of correlation technique comprising the liquid crystal cell outside need polarization plates of liquid crystal; So that light polarizationization; And, be set at by the film formed diaphragm of TAC (triacetyl cellulose) on the one or both sides of said polarization plates with the protection polaroid.In this structure, when the liquid crystal display black state, by the light of the institute of the polaroid on lower polarizing plate polarization be not positive but on the inclination visual direction by oval ground of TAC film polarization.The polarized light of ovalization produces a problem: because it has changed polarization in liquid crystal cell, this causes the color change of display.

In addition, in recent years, making big image display device needs wide visual angle, for example, uses the large scale TV of in-plane-switching mode.Therefore; In in-plane-switching mode LCD (IPS-LCD); Prepared display: at liquid crystal cell and be used between the polaroid (polyvinyl alcohol (PVA)) of a polarization plates of two polarization plates of liquid crystal cell through following method; Replace TAC film configuration isotropy protective seam, and, between the polaroid (polyvinyl alcohol (PVA)) of another polarization plates in liquid crystal cell and said two polarization plates; Dispose two or more layer of compensation or Z-axle orientation (along the thickness direction orientation) films, so that guarantee wide visual angle with different optical performance.

In-plane-switching mode LCD has used through having two coupling polarization plates (layers of compensation of the isotropic membrane of a below and two tops) that are stacked in three compensate film types that form on the side of liquid crystal layer layer by layer of different optical performance; Perhaps, owing in manufacturing process, using lower economic benefit and the requisite shrinking process that shrink film caused to be difficult to have large-area Z-axle alignment films.

Therefore, owing to use, be difficult to make thin product by three coupling polarization plates that compensate film is range upon range of; Because the thickness of liquid crystal cell both sides is different, the variation of temperature or humidity also can cause bending; And because the lower price competitiveness of using expensive compensate film to cause, its use is limited to expensive in-plane-switching mode LCD.In addition, owing to be not easy to make the wide polarization plates that comprises polaroid and compensate film, so be difficult to develop large-sized LCD.

Summary of the invention

Technical matters

The invention provides a kind of in-plane-switching mode LCD; It comprises first polarization plates, second polarization plates and liquid crystal cell; Because confirmed the optical property of compensate film according to the variation of the polarization state of the liquid crystal aligning on Poincare sphere; And the absorption axes that is parallel to liquid crystal aligning and polaroid owing to the slow axis of the compensate film of first polarization plates has improved the contrast at the inclination visual direction; Said in-plane-switching mode LCD has wide visual angle; And, make big coupling polarization plates and can be oversimplified, thereby large-scale, economic, thin in-plane-switching mode LCD can be provided owing to the compensate film that can have the particular optical performance through the width tension manufacturing.

Technical scheme

The invention provides in-plane-switching mode LCD, it comprises: first polarization plates, and it has diaphragm, polaroid and first compensate film, and forms by this order from top to bottom; Liquid crystal cell; And; Second polarization plates; It has second compensate film, polaroid, diaphragm; And form by this order from top to bottom, wherein, the absorption axes of the polaroid in first polarization plates is perpendicular to the absorption axes of the polaroid in second polarization plates; First compensate film have postpone in the face of 40nm to 80nm (R0) ,-150nm is to the delay (Rth) of the thickness direction of-60nm and-2 to-1 refractive index ratio (NZ); And its slow axis is parallel to the absorption axes of the polaroid in the liquid crystal aligning and first polarization plates, and second compensate film has the refractive index ratio (NZ) that postpones (R0) and-1 to 0 in the face of 150nm to 270nm, and its slow axis is parallel to the absorption axes of the polaroid in second polarization plates.

Beneficial effect

According to in-plane-switching mode LCD of the present invention, can guarantee with correlation technique in use three layers of wide visual angle of being on close level that compensate film reached.In addition; Owing to only just can guarantee wide visual angle with one deck compensate film to first polarization plates and second polarization plates; The present invention can realize the large-scale production of the thin LCD of high yield (having reduced because the defect rate that foreign matter or impurity cause); And, the ultra-large type LCD can be provided owing to can produce bigger coupling polarization plates.

Description of drawings

In the accompanying drawings:

Fig. 1 and Fig. 2 are for illustrating the skeleton view according to the structure of in-plane-switching mode LCD of the present invention (S-IPS and FFS);

Fig. 3 is the synoptic diagram that illustrates according to the refractive index of compensate film of the present invention;

Fig. 4 is the synoptic diagram of machine direction (MD) that is illustrated in the manufacturing approach of the draw direction that is used for illustrating compensate film and polarization plates;

Fig. 5 is the synoptic diagram that the expression of Φ and θ in the coordinate system of the present invention is shown;

Fig. 6 is the figure that illustrates according to the variation of the polarization state on Poincare sphere on the visual direction of Φ=45 ° and θ=60 ° of example 1 of the present invention;

Fig. 7 is the figure that the analog result of the transmittance on all visual directions of example 1 of the present invention is shown;

Fig. 8 is the figure that the analog result of the transmittance on all visual directions of example 2 of the present invention is shown;

Fig. 9 is the figure that illustrates according to the variation of the polarization state on Poincare sphere on the visual direction of Φ=45 ° and θ=60 ° of example 3 of the present invention;

Figure 10 is the figure that the analog result of the transmittance on all visual directions of example 3 of the present invention is shown;

Figure 11 is the figure that the analog result of the transmittance on all visual directions of example 4 of the present invention is shown.

Embodiment

The present invention relates to a kind of in-plane-switching mode LCD that comprises first polarization plates, second polarization plates and liquid crystal cell; It is designed with wide visual angle and economy; Because confirmed the optical property of compensate film according to the variation of the polarization state of the liquid crystal aligning on Poincare sphere (Poincare Sphere); And, because the slow axis of the compensate film of first polarization plates is parallel to the absorption axes of liquid crystal aligning and polaroid, improved contrast at the inclination visual direction.

Hereinafter, with the embodiment of describing according to in-plane-switching mode LCD of the present invention.

Said in-plane-switching mode LCD comprises first polarization plates, liquid crystal cell and second polarization plates.

First polarization plates comprises first compensate film, polaroid and diaphragm, and begins by this series arrangement from the liquid crystal cell side; And second polarization plates comprises second compensate film, polaroid and diaphragm, and begins by this series arrangement from the liquid crystal cell side.The absorption axes of the polaroid in first polarization plates is perpendicular to the absorption axes of the polaroid in second polarization plates.

The arrangement of first polarization plates and second polarization plates depends on the liquid crystal aligning of liquid crystal cell.

When the right horizontal direction that shows side is counterclockwise measured liquid crystal aligning, if liquid crystal cell has 90 ° liquid crystal aligning (S-IPS), configuration first polarization plates then as shown in Figure 1 is that the lower polarizing plate and second polarization plates are upper deflection board.In this case, at wavelength 589nm, the panel phase differential through following formula 1 determined liquid crystal cell is 300nm to 330nm.

[formula 1]

(Δn×d)＝(ne-no)×d

Wherein, ne is the special ray refractive index of liquid crystal, and no is the ordinary ray refractive index, and d is a cel-gap, and Δ n and d are scalar rather than vector.

In addition, when when the horizontal direction on the right side of display is counterclockwise measured liquid crystal aligning, if liquid crystal cell has 0 ° liquid crystal aligning (FFS), configuration first polarization plates then as shown in Figure 2 is that the upper deflection board and second polarization plates are lower polarizing plate.In this case, at wavelength 589nm, the panel phase differential of liquid crystal cell is 370nm to 400nm.

First compensate film in first polarization plates have postpone in the face of 40nm to 80nm (R0) ,-150nm is to the delay (Rth) of the thickness direction of-60nm and-2 to-1 refractive index ratio (NZ).

Need find the suitable lower limit that postpones (R0) in the face of compensate film, because postpone (R0) in the less face because inhomogeneous causing on the direction of slow axis when making said film from the degradation in contrast of beholder's direction.In the present invention, postpone (R0) preferred 40nm in said.In addition, because the dispersing characteristic of wavelength, interior postpone (R0) of face that surpasses the compensate film of 120nm can cause the color distortion according to visual direction.The scope of refractive index ratio (NZ) be for can constitute the scope according to liquid crystal display device structure of the present invention, and, when refractive index ratio (NZ) is in above-mentioned scope, can stably make said compensate film through stretching.

The slow axis of first compensate film is configured to be parallel to the absorption axes of the polaroid in the liquid crystal aligning and first polarization plates.

Second compensate film in second polarization plates has and postpones (R0) and-1 to 0 refractive index ratio (NZ), the refractive index ratio (NZ) of preferred use-1 to-0.3 in the face of 150nm to 270nm.

In face, postpone in the said scope of (R0), 150nm is the minimum value that postpones in the face of compensation liquid crystal, and 270nm is the maximal value that is used for through the manufacturing compensate film that stretches.In addition, according to the optical property of the liquid crystal and first compensate film, confirm refractive index ratio (NZ).

The slow axis of second compensate film is configured to be parallel to the absorption axes of the polaroid in second polarization plates.

As shown in Figure 1; When from the horizontal direction on the right side that shows the side when counterclockwise measuring liquid crystal aligning; If liquid crystal cell has 90 ° liquid crystal aligning, then disposing first polarization plates is lower polarizing plate, and first compensate film and polaroid in first polarization plates are parallel to 90 ° liquid crystal aligning.

In addition; As shown in Figure 2, when from the horizontal direction on the right side that shows the side when counterclockwise measuring liquid crystal aligning, if liquid crystal cell has 0 ° liquid crystal aligning; Then disposing first polarization plates is upper deflection board, and first compensate film and polaroid in first polarization plates are parallel to 0 ° liquid crystal aligning.

In the present invention, through formula 2 to the formula 4 of hereinafter,, confirm the optical property of first compensate film and second compensate film to all wavelengths in the visible region.

If the wavelength to light source does not have special declaration; What then describe is the optical property at 589nm; Wherein, Nx is the refractive index of the axle that in face, has largest refractive index on the direction, Ny in face on the direction refractive index on the Nx vertical direction and Nz be the refractive index of thickness direction, represent as follows with formula 2:

[formula 2]

Rth＝[(Nx+Ny)/2-Nz]×d

Wherein, Nx and Ny are refractive index in the face, and Nx >=Ny, and Nz is the refractive index of the light that on the thickness direction of film, vibrates, and d is the thickness of film;

[formula 3]

R0＝(Nx-Ny)×d

Wherein, Nx and Ny are refractive index in the face of compensate film, and d is the thickness of film, and Nx >=Ny; And

[formula 4]

NZ＝(Nx-Nz)/(Nx-Ny)＝Rth/R0+0.5

Wherein, Nx and Ny are refractive index in the face, and Nx >=Ny, and Nz is the refractive index of the light that on the thickness direction of film, vibrates.

At this; Rth in the formula 2 is the delay of thickness direction; It is illustrated in the phase differential with respect to mean refractive index in the face on the thickness direction, and the R0 in the formula 3 postpones in the face, postpone in said for when light with normal orientation (vertical direction) phase differential during through film.

In addition, the NZ in the formula 4 is a refractive index ratio, can distinguish the type of the plate of compensate film thus.

The type of the plate of compensate film can be divided into: 1) A-plate, it has the optical axis on the direction in the face of film, 2) the C-plate, it has the optical axis perpendicular to in-plane, and, 3) biaxial plates when having two optical axises.Specifically, 1) during NZ=1, refractive index meets Nx＞Ny=Nz, and is called A-plate, 2) during 1＜NZ; Refractive index meets Nx＞Ny＞Nz, and is called negative twin shaft A-plate, 3) 0＜NZ＜1 o'clock, refractive index meets Nx＞Nz＞Ny, and is called Z-axle alignment films; 4) during NZ=0, refractive index has relational expression Nx=Nz＞Ny, and is called negative A-plate, 5) NZ＜0 o'clock; Refractive index has relational expression Nz＞Nx＞Ny, and is called positive twin shaft A-plate, 6) during NZ=∞, refractive index has relational expression Nx=Ny＞Nz; And be called negative C-plate, 7) during NZ=-∞, refractive index has relational expression Nz＞Nx=Ny, and is called positive C-plate.

Yet,, in the method for real world, can not make the A-plate and the C-plate that meet theoretical definition fully according to the definition of theory.Therefore, in general technology, the predetermined value in the scope that postpones in the approximate range of the refractive index ratio through setting the A-plate and the face of C-plate is distinguished A-plate and C-plate.Yet the setting predetermined value can't be applied in according to stretching to be had on all other materials of different refractive indexes.Therefore, the compensate film that comprises in upper deflection board of the present invention and the lower polarizing plate represented with digital form by NZ, R0 and the Rth etc. as the optical property of plate, rather than according to the isotropy of refractive index.

Can be through first polarization plates among the manufacturing the present invention that stretches and the compensate film of second polarization plates.

These compensate films provide phase differential through stretching, and wherein, the film that increases in the draw direction refractive index has just (+) refractive index performance, and has negative (-) refractive index performance at the film that the draw direction refractive index reduces.Have that just the compensate film of (+) refractive index performance can be by a kind of the processing that is selected from TAC (triacetyl cellulose), COP (cyclic olefin polymer), COC (cyclic olefine copolymer), PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate), PSF (polysulfones) and PMMA (polymethylmethacrylate); And the compensate film with negative (-) refractive index can specifically be processed by modification PS (polystyrene) or modification PC (polycarbonate).

Provide the drawing process of optical property to be divided into stiff end stretching and free end stretching to compensate film.Said stiff end is stretched as, during the stretching of film, and the length of fixing direction except that draw direction, and free end is stretched as in the drawing process of film and on other directions except that draw direction degree of freedom is provided.Generally speaking, in drawing process, film shrinks on the direction except that draw direction, but Z-axle alignment films needs special shrink process rather than stretch processing.

The unreeling direction of coiling film is called MD (machine direction), and is called TD (laterally) perpendicular to the direction of MD.In addition, in this process, free end is stretched as on MD film is stretched, and the stiff end stretching is on TD, film to be stretched.

Confirm the type of NZ and plate according to drawing process (when only using first technology).Especially, 1) stretch through free end and just have the film of (+) refractive index performance and can make positive A-plate; 2) stretch through stiff end and just have the film of (+) refractive index performance and can make negative twin shaft A-plate; 3) stretch to shrink through free end and have the film that (+) refraction performance just or negative (-) reflect performance and can make Z-axle alignment films with follow-up stiff end; 4) can make negative A-plate through free end the film that stretches with negative (-) refraction performance; And 5) can prepare positive twin shaft A-plate through stiff end the film that stretches with negative (-) refraction performance.

Except that above-mentioned first drawing process, for example second stretch or add direction, phase differential and the NZ value that adjuvant can be controlled slow axis through the technology that use to increase.The technology of such increase is not subject to this especially for one of common many technologies that adopt in comprising the field of the invention.。

First compensate film and second compensate film are preferably processed through the film with negative (-) refractive index is implemented the stretching of one or many stiff end.At this moment, should be more in the stretching of implementing on the TD than the stretching of on MD, implementing, make slow axis on MD.This is in order to be easy in application roll pair roller (roll-to-roll) technology when the polarization plates of making according to coupling of the present invention.

The material of any optical property according to the invention can be used as first compensate film and second compensate film.Specifically, can use a kind of material of from PC (polycarbonate), modification PS (polystyrene) and PMMA (polymethylmethacrylate), choosing.

Will be as providing the PVA (polyvinyl alcohol (PVA)) of the polaroid of polarization function layer to be separately positioned on the polaroid of first polarization plates and second polarization plates through stretching and dyeing.The absorption axes of first polarization plates is perpendicular to the absorption axes of second polarization plates.

Diaphragm be separately positioned on the PVA layer of PVA layer and second polarization plates of first polarization plates with the liquid crystal cell opposition side.

In the diaphragm of the diaphragm of first polarization plates and second polarization plates, can not influence the visual angle according to the optical property of the difference of refractive index, therefore do not limit refractive index in the present invention especially.Normally used in the art material can be used for the diaphragm of first polarization plates and second polarization plates; Particularly, can use and be selected from a kind of among TAC (triacetyl cellulose), COP (cyclic olefin polymer), COC (cyclic olefine copolymer), PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate), PSF (polysulfones) and the PMMA (polymethylmethacrylate).

Can prepare first polarization plates and second polarization plates through method commonly used in this area, particularly, can use roll-to-roll method and sheet sheet (sheet-to-sheet) method.Consider productive rate and efficient in the preparation process, preferably use roll-to-roll method.

In the present invention, because the absorption axes of PVA polaroid is fixed on that MD goes up and the slow axis of compensate film perpendicular to the absorption axes of said polarization plates, so can prepare said first polarization plates through the application roll double roll process.When polaroid and compensate film are combined so that the slow axis of compensate film during perpendicular to the absorption axes of polarization plates, preferably uses roll-to-roll method to reduce manufacturing cost.

Fig. 1 illustrates the structure according to in-plane-switching mode LCD of the present invention.

Comprise first polarization plates 10, liquid crystal cell 30 and second polarization plates 20 that begins to be arranged in order from module 40 sides backlight at the in-plane-switching mode LCD shown in Fig. 1.In Fig. 2, described in-plane-switching mode LCD has second polarization plates 20, liquid crystal cell 30 and first polarization plates 10 that begins to be arranged in order from module 40 sides backlight.At the liquid crystal cell shown in Fig. 1 is the S-IPS liquid crystal cell, and is the FFS liquid crystal cell at the liquid crystal cell shown in Fig. 2.

First polarization plates 10 comprises first polarizing coating 14, polaroid 11 and the diaphragm 13 that begins to be arranged in order from said liquid crystal cell side.Second polarization plates 20 comprises second polarizing coating 24, polaroid 21 and the diaphragm 23 that begins to be arranged in order from said liquid crystal cell side.

The absorption axes 12 of polaroid 11 is perpendicular to the absorption axes 22 of polaroid 21, and the slow axis 15 of first compensate film 14 is parallel to the absorption axes 12 and liquid crystal aligning 31 of polaroid 11.

Said first compensate film 14 have postpone in the face of 40nm to 80nm (R0) ,-130nm to-thickness direction retardation (Rth) of 60nm and-2 to-1 refractive index ratio, and said second compensate film 24 has the refractive index ratio (NZ) of delay (R0) in the face of 150nm to 270nm and-1 to 0.

In the present invention, when when the front is seen, the absorption axes of the polaroid of lower polarizing plate should be by vertical placement.Specifically, when the absorption axes near the lower polarizing plate of module backlight was vertical direction, the light that passes lower polarizing plate was in the horizontal direction by polarization.When passing the liquid crystal cell that applies panel voltage and realize white states, said light vertically advances and passes the upper deflection board of the absorption axes with horizontal direction that shows side.Even one has on absorption axes and also can see the light from LCD the people who shows the polarization sunglasses (absorption axes of polarization sunglasses is generally horizontal direction) on the side horizontal direction.If when being horizontal direction near the absorption axes of the lower polarizing plate of module backlight, the people who has on the polarization sunglasses can not see image.

The variation of the polarization state during through each optical layers in light passes through Poincare sphere can be explained the effect of viewing angle compensation of the present invention.

Said Poincare sphere for the variation of the polarization state that is illustrated in certain viewing angles of great use; Therefore when the light that in LCD (it uses polarization to come display image), advances with specific visual angle passed each optical element of LCD inside, it can show the variation of polarization state.

Said certain viewing angles in the present invention is the direction of Φ=45 ° and θ=60 ° in the hemisphere coordinate system shown in Figure 5; And; Through the variation from the polarization state of light on Poincare sphere of this direction with respect to all wavelengths is shown, can find out the Wavelength distribution characteristic.

Fig. 6 shows in Φ=45 ° and the place, visual angle of θ=60 °, according to the polarization state of LCD of the present invention.Specifically, when the surface of said Φ direction is rotated when showing side with the axle of θ angle around Φ+90 ° in the front, it shows the variation of the polarization state of light on Poincare sphere that comes out from the place ahead.When the coordinate of S3 axle on Poincare sphere during for just (+); Right-hand circular polarization has appearred; Wherein, when a certain polarization horizontal component is Ex and polarization orthogonal component when being Ey, right-hand circular polarization is represented: the light of Ex component with respect to the phase delay of the light of Ey component greater than 0 and half the less than wavelength.

The optical parametric that said LCD of the present invention has is: from the maximum transmission rate of all light directions for being less than or equal to 0.2%.

Hereinafter, compared improvement effect through example and comparative example to wide visual angle according to above-mentioned structure.Although the embodiment through hereinafter can be more readily understood the present invention, the embodiment that hereinafter provided is only as example of the present invention, and protection scope of the present invention that also non-limiting aforesaid right requirement is stated.

Example

Wide view effect has been compared in simulation through using TECH WIZ LCD 1D (Sanayi System company limited, Korea S) to carry out, and this instrument is the LCD simulation system in the hereinafter example.

Example 1

To be applied to TECH WIZ LCD 1D (Sanayi System company limited, Korea S) with stepped construction shown in Figure 1 according to the data of the actual measurement of each blooming of the present invention, liquid crystal cell and module backlight.Hereinafter is described the structure of Fig. 1 in detail.

Begin from module 40 sides backlight; Be provided with first polarization plates 10, in-plane-switching mode liquid crystal cell 30 (when the liquid crystal aligning that has 90 ° under the state that does not apply voltage from the right horizontal direction that shows side this liquid crystal cell when counterclockwise measuring liquid crystal aligning) and second polarization plates 20; Wherein, Form first polarization plates 10 through begin range upon range of first compensate film 14, polaroid 11 and diaphragm 13 from liquid crystal cell 30 sides, and begin range upon range of second compensate film 24, polaroid 21 and diaphragm 23 from liquid crystal cell 30 sides and form second polarization plates 20.

With regard to described liquid crystal cell, LG display company limited (LG Display Co., 42 inches panels of the LC420WU5 that Ltd.) produces and do not consider the absorption of said color filter have been used.The actual measurement data of having used 32 inches model to be assembled to module 40 backlight as TV LC320WX4.

Simultaneously, each blooming and the module backlight that are used for this example have following optical property.

At first; Make the polaroid 11 of first polarization plates 10 and second polarization plates 20 have polarization function through the PVA that stretches with iodine staining, and the polarization property of said polaroid is in the visible-range of 370nm to 780nm, to have 99.9% or greater than 99.9% brightness degree of polarization and 41% or greater than 41% brightness group transmittance with polaroid 21.When the transmittance according to the light transmission shaft of wavelength is TD (λ); Transmittance according to the absorption axes of wavelength is MD (λ); And when the luminance compensation value that in JIS Z 8701:1999, defines is

; Brightness degree of polarization and brightness group transmittance are by 9 definition of following formula 5 to formula; Wherein, S (λ) is the light source frequency spectrum, and light source is the C-light source.

[formula 5]

$T_{\mathrm{TD}}=K{\∫}_{380}^{780}S\left(\mathrm{\λ}\right)\stackrel{\‾}{y}\left(\mathrm{\λ}\right)\mathrm{TD}\left(\mathrm{\λ}\right)\mathrm{d\λ}$

[formula 6]

$T_{\mathrm{MD}}=K{\∫}_{380}^{780}S\left(\mathrm{\λ}\right)\stackrel{\‾}{y}\left(\mathrm{\λ}\right)\mathrm{MD}\left(\mathrm{\λ}\right)\mathrm{d\λ}$

[formula 7]

$K=\frac{100}{{\∫}_{380}^{780}S\left(\mathrm{\λ}\right)\stackrel{\‾}{y}\left(\mathrm{\λ}\right)\mathrm{d\λ}}$

[formula 8]

[formula 9]

According on the direction of each film in the optical property that difference produced of the refractive index of inside; For the 589.3nm light source; Used second compensate film 24 that postpones the refractive index ratio (NZ) of (R0) and-0.5 in the face with 180nm; And, have postpone in the face of 52nm (R0) ,-first compensate film 14 of the thickness direction retardation (Rth) of 130nm and-2 refractive index ratio.Stretch through using the one or many stiff end, made first compensate film and second compensate film.Can stretch to stretch (the stiff end extensibility is greater than free-ended extensibility) with free end or to stretch through the application of fixed end and make first compensate film, and, make second compensate film through only application of fixed end stretching through application of fixed end only.

In this case, the absorption axes 12 of polaroid 11 is parallel to the slow axis 15 and liquid crystal aligning 31 of first polarizing coating 14.

In addition, the TAC (triacetyl cellulose) of optical property that has the Rth of 50nm for the incident light of 598.3nm is used to the external protection film 13 and 23 as the protective seam of first polarization plates 10 and second polarization plates 20.

The visual angle that Fig. 6 is illustrated in Φ=45 ° and θ=60 ° is in the variation of the polarization state in the in-plane-switching mode LCD on the Poincare sphere.Particularly; When light polarization state during with the polaroid 11 of wavelength 550nm through first polarization plates 10 on Poincare sphere is the polarization state of said starting point; And after light saw through first compensate film 14, liquid crystal cell 30 and second compensate film 24 successively, polarization state arrived end point.

Fig. 7 shows the transmittance of all light directions of in-plane-switching mode LCD, wherein, and in this proportional range; Transmittance is 0% to 1%; When black state was shown, transmittance was used red display above 1% part, and low-transmittance partly shows with blue.In this case, can find out that wide more at the blue portion of center, the visual angle of guaranteeing broad more easily, and can confirm through Fig. 7 is because at the blue portion broad of center, the visual angle that can guarantee broad.

Example 2

Although it is identical with the configuration in example 1; But second compensate film 24 has the interior refractive index ratio (NZ) that postpones (R0) and-0.5 of the face of 200nm; And; First compensate film 14 has the interior refractive index ratio (NZ) that postpones (R0) and-1.1 of face of 78nm, and said second compensate film 24 and first compensate film 14 are used to make in-plane-switching mode LCD.

According to wavelength, variation and Fig. 6 of the polarization state on Poincare sphere in the in-plane-switching mode LCD are similar, and the transmittance result of all light directions is identical with Fig. 8.Can confirm through Fig. 8, owing to blue portion broad, so can guarantee the visual angle of broad in the center.

Example 3

Although it is identical with configuration in the example 1; In stepped construction shown in Figure 2; Second compensate film 24 has the interior refractive index ratio (NZ) that postpones (R0) and-0.5 of face of 270nm; And, first compensate film 14 have postpone in the face of 60nm (R0) ,-thickness direction retardation (Rth) of 150nm and-2 refractive index ratio (NZ), and use said second compensate film 24 and first compensate film 14 to make in-plane-switching mode LCD.In this case, used when being 0 ° in-plane-switching mode liquid crystal cell 30 (FFS) at the liquid crystal aligning when the right horizontal direction of display is measured liquid crystal aligning counterclockwise under the state of not accepting voltage.

Fig. 9 illustrate according to wavelength in Φ=45 ° and the visual angle of θ=60 ° be in the variation of the polarization state of the in-plane-switching mode LCD on the Poincare sphere, and Figure 10 illustrates the analog result of the transmittance of all light directions.

As shown in Figure 9; Polarization state during the polaroid 21 of second polarization plates of on Poincare sphere, passing through with wavelength 550nm when light 20 is the polarization state of said starting point; And after light saw through second compensate film 24, liquid crystal cell 30 and first compensate film 14 successively, polarization state arrived end point.

Can confirm through Figure 10, owing to blue portion broad, so can guarantee the visual angle of broad in the center.

Example 4

Although it is identical with the configuration in example 3; But second compensate film 24 has the interior refractive index ratio (NZ) that postpones (R0) and-0.3 of the face of 270nm; And; First compensate film 14 have postpone in the face of 45nm (R0) ,-thickness direction retardation (Rth) of 112.5nm and-2 refractive index ratio (NZ), and use said second compensate film 24 and first compensate film 14 to make in-plane-switching mode LCD.

According to wavelength, the variation of the polarization state of in-plane-switching mode LCD and Fig. 9 are similar on Poincare sphere, and the transmittance result of all light directions is identical with Figure 11.Can confirm through Figure 11, owing to blue portion broad, so can guarantee the visual angle of broad in the center.

Industrial applicibility

It as stated, can be applied to according to in-plane-switching mode LCD of the present invention in the large-scale LCD of demanding viewing angle properties, because can provide excellent picture quality to all visual directions.

Claims (8)

1. in-plane-switching mode LCD, it comprises:

First polarization plates, said first polarization plates have diaphragm, polaroid and first compensate film that is arranged in order from top to bottom;

Liquid crystal cell; And

Second polarization plates, said second polarization plates has second compensate film, polaroid and the diaphragm that is arranged in order from top to bottom,

Wherein, the absorption axes of the polaroid in said first polarization plates is perpendicular to the absorption axes of the polaroid in said second polarization plates,

Said first compensate film have postpone in the face of 40nm to 80nm (R0) ,-150nm is to the delay (Rth) of the thickness direction of-60nm and-2 to-1 refractive index ratio (NZ); And the slow axis of said first compensate film is parallel to the absorption axes of the polaroid in liquid crystal aligning and said first polarization plates, and

Said second compensate film has the refractive index ratio (NZ) that postpones (R0) and-1 to 0 in the face of 150nm to 270nm, and the slow axis of said second compensate film is parallel to the absorption axes of the polaroid in said second polarization plates.

2. in-plane-switching mode LCD as claimed in claim 1, wherein, the refractive index ratio of said second compensate film (NZ) is-1 to-0.3.

3. in-plane-switching mode LCD as claimed in claim 1; Wherein, Said first polarization plates is a lower polarizing plate, and said second polarization plates is a upper deflection board, and; When from the right horizontal direction that shows side when counterclockwise measuring liquid crystal aligning, said liquid crystal cell has 90 ° liquid crystal aligning.

4. in-plane-switching mode LCD as claimed in claim 3, wherein, at wavelength 589nm, said liquid crystal cell has the panel phase differential of 300nm to 330nm.

5. in-plane-switching mode LCD as claimed in claim 1; Wherein, Said first polarization plates is a upper deflection board, and said second polarization plates is a lower polarizing plate, and; When from the right horizontal direction that shows side when counterclockwise measuring liquid crystal aligning, said liquid crystal cell has 0 ° liquid crystal aligning.

6. in-plane-switching mode LCD as claimed in claim 5, wherein, at wavelength 589nm, said liquid crystal cell has the panel phase differential of 370nm to 400nm.

7. in-plane-switching mode LCD as claimed in claim 1 wherein, is made said first compensate film and said second compensate film respectively through applying the stretching of one or many stiff end.

8. in-plane-switching mode LCD as claimed in claim 1 wherein, is made said first compensate film through applying the stretching of one or many free end.

Images