KR20040025862A - New mode liquid crystal display comprising an a plate or o plate retardation film - Google Patents

Abstract

PURPOSE: A new mode LCD(Liquid Crystal Display) having an A-plate or O-plate retardation film is provided to improve gray level stability at a wide viewing angle. CONSTITUTION: A compensator has one or more retardation films(A-plate) having an optical axis actually horizontal to a film plane and one or more retardation films(O-plate) which is slanted at an angle of 0 degree to 90 degrees with respect to the film plane. The slanted angle is changed in a direction vertical to the film plane in two or more O-plates.

Description

NEW MODE LIQUID CRYSTAL DISPLAY COMPRISING AN A PLATE OR O PLATE RETARDATION FILM}

The present invention relates to a compensator for use in a new mode liquid crystal display, comprising an A plate and / or an O plate retardation film, and a new mode liquid crystal display comprising the compensator.

Liquid crystal display (LCD) devices typically used in the prior art are particularly of its particular type, having a low optical retardation (d · Δn) of 150 nm to 600 nm in accordance with DE 30 22 818, for example in Schadt, M. and Helfrich, W. Appl. Phys. Lett. 18 , pp. 127 ff (1974)] for example TN (twisted nematic) LCDs, for example GB 2.123.163, Waters, CM, Brimmel, V, and Raynes, E. Pproc. 3 ^rd Int. Display Research Conference, Kobe 1983, pp. 396 ff and Proc. SID 25/4, pp. 261 ff, 1984, Scheffer, TJ and Nehring, J. Appl. Phys. Lett. 45 , pp. 1021 ff, 1984 and J. Appl. Phys. 58 , pp. 3022 ff, 1985], DE 34 31 871, DE 36 08 911 and EP 0 260 450 STN according to the (second twisted nematic; s uper t wisted n ematic) for LCD, for example, DE 40 00 451 and EP 0 588 568 the IPS, such as those described in (in-plane switching; i n- p lane s witching), for LCD, and for example, literature [Tanaka, Y. et al. Taniguchi, Y., Sasaki, T., Takeda, A., Koibe, Y., and Okamoto, K. SID 99 Digest pp. 206 ff (1999), Koma, N., Noritake, K., Kawabe, M., and Yoneda, K., International Display Workshop (IDW) '97 pp. 789 ff (1997) and Kim, KH, Lee, K., Park, SB, Song, JK, Kim, S., and Suk, JH, Asia Display 98, pp. A; (v ertically a ligned n ematic vertically aligned nematic) 383 ff, (1998)] The VA or VAN as described.

In the known and largely already commercially available LCD devices, the optical aspect was at least insufficient for the required use. In particular, contrast, brightness, color saturation in the case of a colored display, and time (視角) dependence is obviously a need to improve and widely used for a display device CRT of the parameter; performance characteristics of (CRT c athode r ay t ube) If you want to compete with the competition A further disadvantage of the prior art LCD devices is their poor spatial resolution and inadequate response time, especially in the case of STNs, but also in the case of TNs or IPS and VA LCDs, which in the latter case play back video such as computer display screens. It is particularly disadvantageous when it is intended to be used in multimedia applications or in the case of television sets. Especially for this purpose, and also for the display of fast cursor movements, a short reaction time is required.

Recently, a new type of LCD has been reported in the prior art. The display disclosed in, for example, WO 01/07962 is hereafter abbreviated as "new mode" LCD. A new mode LCD has an electro-optical liquid crystal (LC) switching element comprising one or more polarizers, and the LC molecules are aligned essentially parallel to the substrate and not essentially twisted, ie essentially parallel or antiparallel to each other. It contains an LC layer with an initial alignment. Realignment from the initial alignment essentially parallel to the substrate of the LC molecules is caused by the corresponding electric field. For negative dielectric anisotropic LC materials, the electric field is aligned essentially parallel to the substrate. For positive dielectric anisotropic LC materials, the electric field is essentially perpendicular to the substrate. The LC layer has an extremely low optical phase difference (d · Δn) of 0.05 μm to 0.46 μm. The LC switching element preferably contains in addition to the LC layer an additional birefringent layer, preferably a λ / 4 layer or two λ / 4 layers or a λ / 2 layer. Two λ / 4 layers may replace the λ / 2 layers.

The LCD in the new mode has good contrast and at the same time has a good contrast visual dependence, which enables the display of both grayscale and half-tone colors over a wide range of viewing angles, and has a particularly fast response time suitable for video playback. lost. In particular, they are well suited for use with gray shaded displays, for example in television sets, computer monitors and multimedia equipment. Both mains-independent operation and mains operation are possible. Main power operation is often desirable.

New mode LCDs are inter alia television sets, computers such as laptop or desktop computers, central control units and other equipment such as display screens of gambling machines, electro-optical displays such as watches, portable calculators, electronic (portable) games, a portable data banks, such as PDA (p ersonal d igital a ssistants) or display of a portable telephone.

Details regarding the new mode LCD, its assembly and suitable components and the LC media to be used for this are described in WO 01/07962, the entire disclosure of which is incorporated herein by reference.

However, new mode LCDs have in some cases proved to exhibit properties such as visual properties, in particular contrast in different views and directions, and there is still room for further improvement when used in certain applications.

It has been found that the properties of the new mode LCD, in particular the visual properties, can be further improved by using compensators comprising one or more retardation films of a particular type and particular arrangement as described in the invention below.

One object of the present invention is to provide a compensator for LCDs, especially new mode LCDs, which improves the optical performance of LCDs, in particular the gray level stability over a wide range of vision, is easy to manufacture, and enables economic production at large scale.

Another object of the invention is to provide an advantageous use of the compensator according to the invention.

A further object of the invention relates to an LCD, in particular a new mode LCD, comprising the compensator of the invention which exhibits advantageous properties such as good contrast, reduced color shift and wide viewing.

Other objects of the present invention are immediately apparent to those skilled in the art from the following detailed description.

1A shows an arrangement of uncompensated displays of the prior art.

FIG. 1B shows an iso-contrast plot modeled for a V _on value of 7.0 and a V _off value of 0.5 in the display of FIG. 1A.

FIG. 1C shows one actual measurement of the equi-contrast plot for the same values of V _on and V _off (7.0 / 0.5) to demonstrate the accuracy of the modeled results of FIG. 1B.

FIG. 1D shows an iso-contrast plot measured for a V _on value of 5.0 and a V _off value of 0.5 in the display of FIG. 1A.

FIG. 1E shows an iso-contrast plot measured for a V _on value of 4.0 and a V _off value of 1.0 in the display of FIG. 1A.

FIG. 1F shows a gray level diagram of the horizontal orientation of the display of FIG. 1A.

FIG. 1G shows a gray level diagram of the vertical orientation of the display of FIG. 1A.

2a shows an arrangement of a compensated display according to the invention.

FIG. 2B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5 in the display of FIG. 2A.

3A shows an arrangement of another compensated display according to the invention.

FIG. 3B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5 in the display of FIG. 3A.

4a shows an arrangement of another compensated display according to the invention.

FIG. 4B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5 in the display of FIG. 4A.

5a shows an arrangement of another compensated display according to the invention.

FIG. 5B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5 in the display of FIG. 5A.

6a shows an arrangement of another compensated display according to the invention.

FIG. 6B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5 in the display of FIG. 3A.

7a shows an arrangement of another compensated display according to the invention.

FIG. 7B shows an iso-contrast plot modeled for V _on of 4.0 and V _off of 1.0 in the display of FIG. 7A.

FIG. 7C shows a gray level diagram for the horizontal direction in the display of FIG. 7A.

FIG. 7D shows a gray level diagram for the vertical direction in the display of FIG. 7A.

8a shows an arrangement of another compensated display according to the invention.

FIG. 8B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5 in the display of FIG. 8A.

The object of the invention can be achieved by providing a compensator and an LCD according to the invention.

With respect to polarization, compensation and retardation layers, films or plates as described herein, definitions of terms to be used throughout this application are given below.

The term 'film' herein includes self-supported, ie free-standing films, which exhibit somewhat pronounced mechanical stability and flexibility, and a coating or layer on or between the supporting substrates.

The term 'liquid crystal or mesogenic material' or 'liquid crystal or mesogenic compound' refers to one or more rod, board or disc mesogenic groups, i.e. materials comprising groups having the ability to induce liquid crystalline phase behavior. Or a compound. Liquid crystal (LC) compounds having rod or board groups are also known in the art as 'calamitic' liquid crystals. Liquid crystal compounds having discoid groups are also known in the art as 'discotic' liquid crystals. Compounds or materials comprising mesogenic groups do not necessarily represent a liquid crystal phase by themselves. It is also possible that they exhibit liquid crystalline phase behavior only in mixtures with other compounds, or when the mesogenic compound or material, or mixtures thereof, polymerizes.

For the sake of simplicity, the term 'liquid crystal material' is subsequently used for both liquid crystal material and mesogenic material, and the term 'mesogen' is used for the mesogenic group of the material.

The term 'director' is known in the art and means the preferred orientation of the long molecular axis (for calamitic compounds) or the short molecular axis (for discotic compounds) in the liquid crystal material.

The term 'planar structure' or 'planar orientation' refers to a film whose optical axis is substantially parallel to the film plane.

The term 'homeotropic structure' or 'homeotropic orientation' refers to a film whose optical axis is substantially perpendicular to the film plane, ie substantially parallel to the film normal.

The term 'tilted structure' or 'tilt orientation' refers to a film in which the optical axis is inclined at an angle of 0 to 90 ° with respect to the film plane.

The term 'splayed structure' or 'sprayed orientation' is defined above where the tilt angle monotonously additionally varies in the range of 0 to 90 °, preferably minimum to maximum, in the direction perpendicular to the film plane. By diagonal orientation as is meant.

The tilt angle of the wetted film is then given as the average tilt angle θ _ave , unless stated otherwise.

The mean tilt angle θ _ave is defined as follows.

Where [theta] '(d') is the local tilt angle at the thickness d 'in the film and d is the overall thickness of the film.

In planar, homeotropic, and oblique optical films comprising uniaxial positive birefringent liquid crystal materials with uniform orientation, the optical axis of the film is given by the director of the liquid crystal material.

The term 'helical twisted structure' means that at least one of the liquid crystal materials in which the mesogen is oriented with its main molecular axis in a preferred direction in the molecular sublayer, wherein the preferred direction of orientation in the different sublayers is twisted at an angle φ around the helix axis. It relates to a film comprising a layer. The term 'helical twisted structure with planar orientation' means a film having such a spiral twisted structure wherein the helix axis is substantially perpendicular to the film plane, ie substantially parallel to the film normal.

The term 'A plate' means that its ideal axis is oriented parallel to the plane of the layer, and its normal axis (aka 'a-axis') is oriented perpendicular to the plane of the layer, ie parallel to the direction of normal incident light. Refers to an optical retardation plate using a layer of axial birefringent material.

The term 'C plate' refers to an optical retardation plate using a layer of uniaxial birefringent material whose ideal axis (aka 'c-axis') is perpendicular to the plane of the layer, ie parallel to the direction of normal incident light. .

The term 'O plate' refers to an optical retardation plate using a layer of uniaxial birefringent material whose ideal axis is oriented at an o blique angle with respect to the plane of the layer.

In A-, C- and O-plates comprising optical uniaxial birefringent liquid crystal materials in uniform orientation, the optical axis of the film is given by the direction of the ideal axis.

An A plate or C plate comprising an optical uniaxial birefringent material having a positive birefringence is also referred to as a '+ A / C plate' or a 'positive A / C plate'. A plate or C plate comprising a film of optical uniaxial birefringent material with negative birefringence is also referred to as '-A / C plate' or 'negative A / C plate'.

Retardation films having positive or negative birefringence are also abbreviated as 'positive' or 'negative' retardation films, respectively.

The transmissive or translucent LCD according to the invention preferably contains a polarizer and an analyzer, which are arranged on opposite sides of the arrangement of the LC layer and the birefringent layer.

Polarizers and analyzers are referred to herein as "polarizers".

One or more retardation films (A plates) having optical axes substantially parallel to the film plane and / or one or more retardation films (O plates) having an optical axis inclined at an angle θ of 0 ° to 90 ° with respect to the film plane. And a compensator for use in a new mode liquid crystal display.

The invention also relates to a liquid crystal layer having an initial alignment that is essentially parallel and essentially untwisted with respect to the substrate, one or more polarizers, a liquid crystal material that is aligned essentially parallel to the substrate in the case of a negative dielectric anisotropic liquid crystal material Is a liquid crystal display comprising an electric field generating device aligned essentially perpendicular to a substrate, and, if necessary, at least one birefringent layer, wherein the liquid crystal layer has an optical phase difference [(d · Δn) _LC ] of 0.05 μm to 0.46 μm The liquid crystal display comprises a compensator according to the invention as described above and below.

The compensator according to the invention comprises at least one A plate, preferably a positive A plate and / or at least one O plate, preferably a positive O plate. More preferred are compensators comprising at least one C plate, preferably a negative C plate.

Optical films suitable for use as A plate retardation plates are known in the art and include, for example, uniaxially stretched polymer films such as polyethylene terephthalate (PET), polyvinyl alcohol (PVA) or polycarbonate (PC) films. There is this.

Optical films suitable for use as O plate retarders are known in the art and by, for example, oblique deposition of thin films of inorganic materials such as Ta ₂ O ₅ as described in US 5,196,953 and WO 96/10773. Can be obtained. It is also possible to use LC films as O plates, as described in WO 96/10770, from polymeric LC materials having smectic A or C phases and nematic phases at elevated temperatures. The LC material is applied onto a substrate optionally coated with an alignment layer of obliquely deposited SiO, and the temperature is lowered to be the Smectic C phase of the material so that the LC material adopts its natural gradient Smectic C structure, and the LC material It is produced by fixing the inclined structure by the polymerization of.

Optical films suitable for use as negative C plate retardation plates are known in the art and are described, for example, in stretched or uniaxially compressed plastic films such as DAC or TAC as described in US 4,701,028, as described in US 5,196,953. Inorganic thin films obtained by the same physical vapor deposition, or negative birefringent polyimide films as described in US Pat. No. 5,480,964 and US Pat. No. 5,395,918.

Preferably the retardation film comprises a polymerized or crosslinked LC material.

The A plate retardation film preferably comprises a polymerized LC material having a planar structure, for example as described in WO 98/04651, the entire disclosure of which is incorporated herein by reference.

Inclined or watertight O plate retarders are preferably described, for example, in US 5,619,352, WO 97/44409, WO 97/44702, WO 97/44703 or WO 98/12584, the entire disclosures of which are incorporated herein by reference. And polymerized liquid crystal material having an oblique or watertight structure as described above.

Negative C plate retarders preferably have short pitch and reflectivity in the UV range, for example as described in GB 2,315,072, WO 01/20393 and WO 01/20394, the entire disclosure of which is incorporated herein by reference. Polymerized chiral LCs, in particular cholesteric LC (CLC) materials such as UVCLC films or highly twisted A plates.

Especially preferred are the following embodiments:

The compensator comprises at least two O plates (water filled O plates) in which the angle of inclination changes in a direction perpendicular to the film plane,

The compensator comprises at least four A plates,

An aspect in which the compensator comprises at least two O-plates (water-filled O-plates), and at least two A-plates whose tilt angles change in a direction perpendicular to the film plane,

The compensator comprises at least one negative C plate in addition to the A and / or O plate,

An A plate, O plate and / or C plate comprising polymerized or crosslinked LC material,

An embodiment in which the A plate comprises a polymerized or crosslinked achiral LC material with a planar orientation,

The O plate comprises a polymerized or crosslinked achiral LC material with an oblique or watertight orientation,

The negative C plate comprises a polymeric or crosslinked cholesteric LC (CLC) material having a spirally twisted structure and a planar orientation,

The spiral pitch of the CLC material in the negative retardation film is less than 250 nm,

The reflection wavelength of the CLC material in the negative retardation film is less than 375 nm,

An embodiment in which the thickness of the A plate is from 0.1 to 1 μm, preferably from 0.13 to 0.65 μm,

An embodiment wherein the optical phase difference of the A plate is between 12 and 115 nm, preferably between 15 and 75 nm,

An embodiment wherein the thickness of the O plate is between 0.4 and 1.5 μm, preferably between 0.5 and 0.9 μm,

An embodiment wherein the optical retardation of the O plates is between 46 and 173 nm, preferably between 58 and 104 nm,

An embodiment in which the thickness of the negative C plate is from 0.5 to 2 μm, preferably from 1 to 1.5 μm,

The optical phase difference of the negative C plate is between 29 and 116 nm, preferably between 58 and 87 nm.

Particularly preferred compensator stacks are shown in Table 1. Here, LC represents a liquid crystal cell, O represents an oblique or soaked O plate, A represents a flat A plate, and -C represents a negative C plate. If the O plate is a sold O plate, the arrow indicates the preferred direction of increasing tilt angle.

For simplicity, the polarizers are omitted from Table 1. However, the practical display further includes a pair of polarizers sandwiching the stack shown in Table 1.

In the stack format shown in Table 1, the single retarder components are arranged symmetrically, so that incident light can enter the stack from both sides.

The compensators according to the invention and also the single A, O and C plates in the stacks shown in Table 1 can each be laminated directly or isolated by a transparent intermediate film, for example a TAC film. "(TAC)" in Table 1 indicates the preferred location of any TAC film.

Preferred Compensator Stack in Displays of the Invention One) (TAC) O (TAC) A LC A (TAC) O (TAC) 2) (TAC) O A (TAC) LC (TAC) A O (TAC) 3) O (TAC) (TAC) A LC A (TAC) (TAC) O 4) O (TAC) A (TAC) LC (TAC) A (TAC) O 5) (TAC) A (TAC) O LC O (TAC) A (TAC) 6) (TAC) A O (TAC) LC (TAC) O A (TAC) 7) A (TAC) O (TAC) LC (TAC) O (TAC) A 8) A (TAC) (TAC) O LC O (TAC) (TAC) A 9) (TAC) A (TAC) A LC A (TAC) A (TAC) 10) A (TAC) (TAC) A LC A (TAC) (TAC) A 11) (TAC) A A (TAC) LC (TAC) A A (TAC) 12) A (TAC) A (TAC) LC (TAC) A (TAC) A 13) (TAC) O LC O (TAC) 14) O (TAC) LC (TAC) O

Especially preferred are compensator stacks of the type 1) above.

LCDs according to the invention are either polarizers or compensation or retardation films, such as one or more quarter-wave retardation films (QWF, λ / 4 film) or half-wave retardation films (HWF, λ / 2 film), twisted or arced. It may further comprise one or more additional optical components, such as positive or negative A, O or C plates or retardation films having a meotropic, planar, oblique or splashed structure. Especially preferred are optical films comprising polymerized or crosslinked LC materials. Homeotropic LC films are described, for example, in WO 98/00475.

The LCD according to the invention may be a reflective or transmissive display display and may further comprise a light source, such as a reflective layer or a conventional backlight, on the face of the LC cell opposite the first linear polarizer. In the case of a reflective display with a reflective layer on one side of the LC cell, the second linear polarizer can be omitted.

The negative and positive retardation plates and the A, O and C plates of the compensators according to the invention are preferably produced by in situ polymerization from a polymerizable LC material. In a preferred method of preparation, the polymerizable LC material is coated onto a substrate, oriented in the desired orientation, for example as described in WO 01/20394, GB 2,315,072 or WO 98/04651 and then for example heat or actinic radiation. Polymerized by exposure to radiation.

Alternatively, from the LC polymer already synthesized, it is applied onto the substrate, for example at its glass transition temperature or above its melting point, or from, for example, a solution in an organic solvent, aligned in the desired orientation, for example the solvent Retardation films can be prepared by evaporation or by cooling to below the glass temperature or melting point of the LC polymer. For example, when using an LC polymer having a glass temperature higher than the ambient temperature, evaporation or cooling of the solvent leaves a solid LC polymer film. For example, when using an LC polymer with a high melting point, the LC polymer is applied on the substrate as a melt which solidifies upon cooling. LC side chain polymers or LC backbone polymers may be used, preferably LC side chain polymers. The LC polymer should preferably be chosen such that its glass transition or melting temperature is significantly higher than the operating temperature of the retarder. For example, LC side chain polymers can be used that include a polyacrylate, polymethacrylate, polysiloxane, polystyrene, or epoxide backbone with laterally attached mesogenic side chains. The LC polymer may also include side chains with reactive groups that can be crosslinked after or during evaporation of the solvent to permanently fix the orientation. LC polymers can also be applied to a substrate and then mechanically or thermally treated to improve alignment. Such methods and suitable materials are known to those skilled in the art.

The compensators according to the invention are especially suitable for use in LCs in scene mode as described, for example, in WO 01/07962. However, the compensator can also be used in conventional LCDs, in particular in DAP (defromation of aligned phases) or VA (vertical alignment) modes, such as ECB (electrically controlled birefringence), CSH (color seconds). Homeotropic; color super homeotropic, VAN or VAC (vertical alignment nematic or cholesteric) display, MVA (multi-domain vertical alignment) or PVA (patterned vertical alignment) display, bend mode or hybrid Displays such as OCB (optically compensated curved cells or optically compensated birefringence), R-OCB (reflective OCB), HAN (hybrid aligned nematic) or pi-cell (π-cell) displays, also TN (twisted nema) Tick), HTN (High Twisted Nematic) or STN (Super Twisted Nematic) display, AMD-TN (Active Matrix Drive TN) display, or so-called 'second TFT' display, On display It is particularly suitable for use.

The following examples are intended to illustrate the invention without limiting it. Here, the following abbreviations are used:

θ: angle of inclination [degrees]

φ: twist angle [degrees]

p: helix pitch [nm]

n _e : Abnormal refractive index (at 20 ° C. and 589 nm)

n _o : Normal refractive index (at 20 ° C and 589 nm)

ε _∥ : dielectric constant parallel to long molecular axis (at 20 ° C and 1kHz)

ε _⊥ : dielectric constant perpendicular to the long molecular axis (at 20 ° C and 1kHz)

K ₁₁ : first elastic constant

K ₂₂ : second elastic constant

K ₃₃ : third elastic constant

V _on : Threshold voltage [V]

V _off : Saturation voltage [V]

d: layer thickness [μm]

ret. : Phase difference [nm]

Uncompensated and compensated displays described in the Examples below contain the following ingredients, unless explicitly stated otherwise.

A plate

Planar polymerized LC film with the following parameters

n _e : 1.610, n _o : 1.495

d: 0.1-5.0, ret. 12-575

O plate

Waterborne polymerized LC film with the following parameters

θ _min : 2, θ _max : 88

θ _ave : 45, n _e : 1.610

n _o : 1.495, d: 0.1-5.0

ret. 6-300

Negative C Plate (-C Plate)

Highly twisted polymerized LC film with the following parameters

n _e : 1.610, n _o : 1.495

d: 0.1-5.0, p: <250

TAC

Slightly anisotropic TAC film with the following parameters

n _x : 1.48147, n _y : 1.48145

n _z : 1.48108, d: 80

LC cell

Scene mode LC cell with the following parameters

Surface rubbing: anti-parallel, surface pre-tilt: 3 °

d: 4.5, Δn: 0.06

n _e : 1.525, n _o : 1.465

ε _∥ : 15.1, ε _⊥ : 4.8

K ₁₁ : 12.5, K ₂₂ : 6

K ₃₃ : 17.7, V _off : 0.5

V _on : 5

QWF

A planar A plate having a polymerized LC material, typically having a phase difference in the region of 135 nm with respect to visible light, close to a quarter of the wavelength of light passing through the system.

Polarizer

Standard stretched dichroic polarizer, drawing axis indicated by both arrows in the drawing.

The display arrangement shown in the following figures also includes a light source, for example a backlight, on the left side of the display (not shown).

In the examples below, values and plots of iso-contrast and gray levels are obtained by modeling and measuring using the Berreman matrix method for optical simulation and the Eldim EZContrast equipment for visual measurement, respectively. .

Example 1- Comparative Example

Prior art uncompensated new mode displays have an LC cell 1, a quarter-wave wave foil (QWF) 2, and two crossed polarizers 3 arranged as shown in FIG. 1A. It includes. The backlight (not shown) is on the left side of the display.

The orientation of LC molecules in LC cell 1 and QWF 2 is conceptually illustrated by mesogens 1a and 2a. The dotted lines 1b and 2b represent the orientation directions of the mesogens 1a and 2a adjacent to the surfaces of the LC cell 1 and the QWF 2.

1B shows an iso-contrast plot modeled for a V _on value of 7.0 and a V _off value of 0.5. FIG. 1C shows one actual measurement of the equi-contrast plot for the same values of V _on and V _off (7.0 / 0.5) to demonstrate the accuracy of the modeled results.

Figure ID shows an iso-contrast plot measured for a V _on value of 5.0 and a V _off value of 0.5. FIG. 1E shows iso-contrast plots measured for a V _on value of 4.0 and a V _off value of 1.0. For V _on = 5 the on-axis contrast is calculated to be 10-20: 1. The 10: 1 contrast region extends + 10 / -40 ° vertically and + 50 / -50 ° horizontally. For V _on = 4 the _on- axis contrast is calculated to be 10-1: 1. The 10: 1 contrast region extends + 0 / -60 ° vertically and + 60 / -60 ° horizontally.

Gray level diagrams are shown in FIG. 1F for the horizontal direction and FIG. 1G for the vertical direction. Gray scale inversion is present in both the horizontal and vertical directions, especially at the black and lower gray levels.

Example 2

The compensated display according to the invention is an LC cell (1), two smolded O-plates (2,2 ') on a TAC with an optical axis orientation of 125 ° (2) and 235 ° (2') and a phase difference of 732 nm, respectively. ), And two crossed polarizers 3, 3 'oriented at 45 ° (3) and 135 ° (3'), respectively. The arrangement is shown in Figure 2a. 2B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5. On-axis contrast is calculated to be greater than 100: 1. The 10: 1 contrast region extends + 43 / -70 ° vertically and + 60 / -60 ° horizontally. The 100: 1 contrast region extends + 20 / -40 ° vertically and + 33 / -33 ° horizontally.

Example 3

A compensated display according to the invention is an LC cell (1), two splashed O-plates (2,2 ') on a TAC with an optical axis orientation of 142 ° (2) and 218 ° (2') and a phase difference of 636 nm, respectively. ), Two planar A-plates (3,3 ') on TAC with optical axis orientations of 270 ° (3) and 90 ° (3') and phase difference of 239 nm, respectively, and 45 ° (4) and 135 ° ( 4 ') and two crossed polarizers 4,4'. The arrangement is shown in FIG. 3A. FIG. 3B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5. On-axis contrast is calculated to be greater than 100: 1. The 10: 1 contrast region extends + 55 / -70 ° vertically and + 80 / -80 ° horizontally. The 100: 1 contrast region extends + 40 / -40 ° vertically and + 45 / -45 ° horizontally.

Example 4

The compensated display according to the invention comprises an LC cell (1), two splashed O-plates (2, 2 ') on a TAC with an optical axis orientation of 180 ° and a phase difference of 576 nm, 270 ° (3) and 90 ° respectively. Two planar A-plates (3,3 ') on the TAC with an optical axis orientation of (3') and a phase difference of 434 nm, and two crossed polarizers oriented at 45 ° (4) and 135 ° (4 '), respectively (4,4 '). The arrangement is shown in FIG. 4A. 4B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5. On-axis contrast is calculated to be greater than 100: 1. The 10: 1 contrast region extends + 50 / -60 ° vertically and + 60 / -60 ° horizontally. The 100: 1 contrast region extends + 30 / -30 ° vertically and + 30 / -30 ° horizontally.

Example 5

The compensated display according to the invention comprises an LC cell (1), two optically O-plates (2, 2 ') with an optical axis orientation of 180 ° and a phase difference of 545 nm, 270 ° (3) and 90 ° (3), respectively. Two planar A-plates (3,3 ') on a TAC with an optical axis orientation of') and a phase difference of 434 nm, and two crossed polarizers oriented at 45 ° (4) and 135 ° (4 '), respectively , 4 '). The arrangement is shown in FIG. 5A. FIG. 5B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5. On-axis contrast is calculated to be greater than 100: 1. The 10: 1 contrast region extends + 50 / -60 ° vertically and + 60 / -60 ° horizontally. The 100: 1 contrast region extends + 30 / -30 ° vertically and + 30 / -30 ° horizontally.

Example 6

The compensated display according to the invention comprises an LC cell (1), two optically O-plates (2, 2 ') with an optical axis orientation of 180 ° and a phase difference of 545 nm, 270 ° (3) and 90 ° (3), respectively. Two planar A-plates (3,3 ') with an optical axis orientation of') and a phase difference of 434 nm, two negative with an optical axis orientation of 270 ° (4) and 90 ° (4 ') and a phase difference of 1168 nm, respectively. C plates 4, 4 'and two crossed polarizers 5, 5' oriented at 45 ° (5) and 135 ° (5 '), respectively. The arrangement is shown in FIG. 6A. FIG. 6B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5. On-axis contrast is calculated to be greater than 100: 1. The 10: 1 contrast region extends + 50 / -60 ° vertically and + 60 / -60 ° horizontally. The 100: 1 contrast region extends + 35 / -30 ° vertically and + 35 / -35 ° horizontally.

Example 7

The compensated display according to the invention comprises an LC cell (1), two splashed O-plates (2, 2 ') with an optical axis orientation of 180 ° (2) and 218 ° (2') and a phase difference of 827 nm, respectively. Two planar A-plates (3,3 ') on TAC with optical axis orientations of 270 ° (3) and 90 ° (3') and phase difference of 642 nm, respectively, and 45 ° (4) and 135 ° (4 '), respectively ) And two crossed polarizers 4,4 '. The arrangement is shown in FIG. 7A. FIG. 7B shows an iso-contrast plot modeled for V _on of 4.0 and V _off of 1.0. On-axis contrast is calculated to be greater than 100: 1. The 10: 1 contrast region extends + 50 / -60 ° vertically and + 70 / -70 ° horizontally. The 100: 1 contrast region extends + 30 / -30 ° vertically and + 35 / -35 ° horizontally. Gray level diagrams are shown in FIG. 7C for the horizontal direction and FIG. 7D for the vertical direction. There is no black state reversal in the horizontal direction and the degree of gray level reversal in the vertical direction is improved over uncompensated displays.

Example 8

The compensated display according to the invention comprises an LC cell 1, two planar A-plates 2,2 'each having an optical axis orientation of 311 ° (2) and 49 ° (2') and a phase difference of 481 nm, respectively. Two planar A-plates (3,3 ') on TAC with optical axis orientations of 265 ° (3) and 138 ° (3') and phase difference of 138 nm, and 45 ° (4) and 135 ° (4 '), respectively Two intersected polarizers 4, 4 'oriented with. The arrangement is shown in FIG. 8A. FIG. 8B shows an iso-contrast plot modeled for V _on of 5.0 and V _off of 0.5. On-axis contrast is calculated to be greater than 100: 1. The 10: 1 contrast region extends + 50 / -30 ° vertically and + 80 / -80 ° horizontally. The 100: 1 contrast region extends + 15 / -10 degrees vertically and + 55 / -55 degrees horizontally.

The compensator according to the invention improves the optical performance of the LCD, in particular the gray level stability over a wide range of perspectives, is easy to manufacture and economical to manufacture at large scale. In addition, LCDs comprising compensators according to the invention, in particular new mode LCDs, exhibit advantageous properties such as good contrast, reduced color shift and wide viewing.

Claims (7)

As a compensator for use in a new mode liquid crystal display, At least one retardation film (A plate) having an optical axis substantially parallel to the film plane and / or at least one retardation film (O plate) having an optical axis inclined at an angle θ of 0 ° to 90 ° with respect to the film plane. Compensator characterized in that. The method of claim 1, A compensator comprising at least two O plates in which the inclination angle varies in a direction perpendicular to the film plane. The method of claim 1, Compensator comprising at least four A plate. The method according to claim 1 or 2, A compensator comprising at least two O plates and at least two A plates in which the inclination angle changes in a direction perpendicular to the film plane. The method according to any one of claims 1 to 4, And a compensator further comprising at least one negative C plate. The method according to any one of claims 1 to 5, A compensator characterized in that the A plate and / or the O plate and / or the C plate comprise a polymerized or crosslinked liquid crystal material. Liquid crystal layer having an initial alignment essentially parallel to the substrate and essentially untwisted, one or more polarizers, liquid crystal material aligned essentially parallel to the substrate in the case of negative dielectric anisotropy liquid crystal material and essentially in the substrate for positive dielectric anisotropy liquid crystal material A liquid crystal display comprising: an apparatus for generating an electric field aligned vertically with a light; and, if necessary, at least one birefringent layer, wherein the liquid crystal layer has an optical retardation [(d · Δn) _LC ] of 0.05 μm to 0.46 μm, A liquid crystal display, further comprising a compensator according to any one of claims 1 to 6.