CN116819830A - Liquid crystal panel and liquid crystal display device - Google Patents
Liquid crystal panel and liquid crystal display device Download PDFInfo
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- CN116819830A CN116819830A CN202310842279.7A CN202310842279A CN116819830A CN 116819830 A CN116819830 A CN 116819830A CN 202310842279 A CN202310842279 A CN 202310842279A CN 116819830 A CN116819830 A CN 116819830A
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Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/13363—Birefringent elements, e.g. for optical compensation
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
Abstract
The liquid crystal panel (101) is provided with a liquid crystal cell (20), a first polarizer (30), a second polarizer (40), and an optically anisotropic element (50). The liquid crystal cell includes a liquid crystal layer including liquid crystal molecules that are horizontally aligned in a non-electric field state, and a color filter (22) disposed on a first main surface of the liquid crystal layer. The slow axis direction (53) of the optically anisotropic element (50) is parallel to the absorption axis direction (45) of the second polarizer. The retardation in the thickness direction of the optically anisotropic element and the retardation in the thickness direction of the color filter of the liquid crystal cell satisfy a specific relationship between each of the wavelength 550nm and the wavelength 650 nm.
Description
The application relates to a divisional application of Chinese patent application with the application date of 2019, 5 month and 17 days, the application number of 201980039432.4 and the name of liquid crystal panel and liquid crystal display device.
Technical Field
The present application relates to a liquid crystal panel including an optically anisotropic element between a liquid crystal cell and a polarizer. In addition, the present application relates to a liquid crystal display device using the above liquid crystal panel.
Background
The liquid crystal panel includes a liquid crystal cell between a pair of polarizers. In a typical liquid crystal cell, a color filter is provided on a substrate (color filter substrate) disposed on a visual inspection side of the liquid crystal layer, and a pixel electrode, a TFT (thin film transistor) module, and the like are provided on a substrate (TFT) disposed on a light source side.
In a liquid crystal cell of an In-Plane Switching (IPS) mode, in a non-electric field state, liquid crystal molecules are horizontally aligned In a direction substantially parallel to a substrate surface, and the liquid crystal molecules are rotated In a Plane parallel to the substrate surface by applying an electric field In the lateral direction, so that light transmission (white display) and shielding (black display) are controlled. As in the IPS mode, the transverse electric field mode liquid crystal panel in which liquid crystal molecules are horizontally aligned in a no-electric field state is excellent in viewing angle characteristics.
IPS mode liquid crystal display devices are roughly classified into O-mode and E-mode according to the relationship between the alignment direction of liquid crystal molecules in the no-electric-field state of a liquid crystal cell (hereinafter, referred to as "initial alignment direction") and the absorption axis direction of polarizers disposed on the front and back sides of the liquid crystal cell. In the O-mode, the absorption axis direction of the polarizer disposed on the light source side of the liquid crystal cell is parallel to the initial alignment direction of the liquid crystal. In the E mode, the absorption axis direction of the polarizer disposed on the light source side of the liquid crystal cell is orthogonal to the initial alignment direction of the liquid crystal.
In IPS mode liquid crystal display devices, when the liquid crystal display device is visually confirmed from an oblique direction at an angle of 45 degrees (azimuth angle of 45 degrees, 135 degrees, 225 degrees, 315 degrees) with respect to the absorption axis of the polarizer, light leakage in black display is large, and reduction in contrast and color shift are likely to occur. This light leakage is caused by the fact that the angle formed by the "exhibited absorption axis direction" of the polarizers disposed on the front and back sides of the liquid crystal cell is shifted from 90 ° when visually confirmed from the oblique direction.
To reduce light leakage in visual inspection from an oblique direction, a method of disposing an optically anisotropic element (retardation plate) between a liquid crystal cell and a polarizer has been proposed. For example, patent document 1 proposes that an optically anisotropic element having refractive index anisotropy of nx > nz > ny is disposed between a liquid crystal cell and a polarizer. nx is the refractive index in the in-plane slow axis direction, ny is the refractive index in the in-plane slow axis direction, and nz is the refractive index in the thickness direction (normal direction).
In terms of compensating for the angular shift in the absorption axis direction exhibited by the polarizer, it is preferable that the retardation of the optically anisotropic element is 1/2 of the wavelength and that the Nz coefficient expressed as nz= (nx-Nz)/(nx-ny) be 0.5 (see poincare sphere of fig. 5). The retardation of the optically anisotropic element varies depending on the wavelength. In optical compensation of a liquid crystal display device using an optically anisotropic element, optical design is generally performed such that light leakage of green light (around wavelength 550 nm) having a high luminosity function is reduced. Therefore, in order to compensate for the angular shift in the axial direction of the polarizer, an optically anisotropic element having a retardation of about 275nm at a wavelength of 550nm may be used.
In addition to the shift in the axial direction exhibited by the polarizer, the characteristics of other optical components also cause light leakage during black display. For example, patent document 2 proposes to adjust optical characteristics of an optically anisotropic element for optical compensation in consideration of birefringence of a triacetyl cellulose (TAC) film provided as a protective film on a liquid crystal cell side surface of a polarizer. Patent document 3 proposes to use a low birefringent film such as a norbornene-based resin film as a protective film provided on the surface of a polarizer.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 4-371903
Patent document 2: japanese patent laid-open No. 2001-258041
Patent document 3: japanese patent laid-open No. 2004-4641
Disclosure of Invention
Problems to be solved by the invention
The in-plane retardation of the color filter provided on the substrate of the liquid crystal cell is substantially 0, but has a retardation of several nm to several tens nm in the thickness direction. As described above, in the case where the optical element disposed between the polarizer and the liquid crystal cell has birefringence, light leakage in visual confirmation from the oblique direction can be further reduced by adjusting the optical characteristics of the optically anisotropic element in consideration of the optical characteristics thereof.
As described above, the optical compensation of the liquid crystal panel is optimized for green (around 550nm wavelength) light with a high luminosity function. Therefore, in the black display, light of a wavelength at which the optical design is greatly shifted from the optimum value leaks, and the screen is visually confirmed by coloring. In the optical design, it is difficult to make the hue completely neutral when visually confirmed from the oblique direction, so that the screen is slightly colored and visually confirmed at the wavelength of light causing light leakage in the black display. Since the luminosity function of blue (around 450 nm) is lower than that of red (around 650 nm), the hue of black display tends to be shifted to blue.
According to the studies by the inventors, in the case of designing an optically anisotropic element so as to minimize green light leakage in consideration of the influence of retardation in the thickness direction of a color filter in a liquid crystal panel having a specific structure, it was found that red light leakage tends to be large, and a black-displayed screen is visually confirmed as a red-based hue when visually confirmed from an oblique direction. Specifically, it has been found that, when the absorption axis direction of the polarizer disposed on the light source side of the liquid crystal cell is orthogonal to the slow axis direction of the optically anisotropic element, there is a tendency that red light leakage is suppressed even if the optical design is performed so that green light leakage becomes small in consideration of the influence of retardation in the thickness direction of the color filter. On the other hand, when the absorption axis direction of the polarizer disposed on the light source side of the liquid crystal cell is parallel to the slow axis direction of the optically anisotropic element, if the optical design is performed so that the light leakage of green is minimized in consideration of the influence of the retardation in the thickness direction of the color filter, the light leakage of red is large and black display is likely to be a hue of red.
The invention aims to provide an image display device, which is capable of reducing light leakage of black display in visual confirmation from an oblique direction and reducing red coloring in black display in consideration of the influence of a color filter in a liquid crystal panel in which an absorption axis direction of a light source side polarizer is arranged in parallel with a slow phase axis direction of an optical anisotropic component, and is excellent in visual confirmation.
Technical means for solving the problems
The liquid crystal panel of the invention comprises: a liquid crystal cell including a liquid crystal layer including liquid crystal molecules that are horizontally aligned in a non-electric field state, and a color filter disposed on a first main surface (visual confirmation side) of the liquid crystal layer; a first polarizer disposed on a first main surface (visual confirmation side) of the liquid crystal cell; and a second polarizer disposed on a second main surface (light source side) of the liquid crystal cell. The absorption axis direction of the first polarizer is orthogonal to the absorption axis direction of the second polarizer.
The color filter has at least a green transmission region and a red transmission region. The green transmission region of the color filter preferably has a thickness direction retardation Ct of 550nm 550 Is 50nm or less. The red region of the color filter preferably has a thickness direction retardation Ct of 650nm 650 Is 50nm or less. Ct is (Ct) 550 Ct is as follows 650 Are all greater than 0.Ct is (Ct) 550 Ct is as follows 650 For example, the wavelength may be 1nm or more, 3nm or more, or 5nm or more.
The liquid crystal panel of the present invention includes an optically anisotropic element disposed between a first polarizer and a second polarizer. The slow axis direction of the optically anisotropic element is parallel to the absorption axis direction of the second polarizer. Front retardation Re of optically anisotropic component with wavelength of 650nm 650 Retardation Rt in the thickness direction 650 Ratio Rt of (1) 650 /Re 650 0.2 to 0.8.
Preferably, the thickness direction retardation Rt of the optically anisotropic element has a wavelength of 650nm 650 (nm) and the thickness direction of the red transmission region of the color filter, which is 650nm in wavelengthLate Ct 650 (nm) satisfies the following formula (1 a) or (2 a):
Rt 650 ≥0.37(Ct 650 )+116...(1a)
Rt 650 ≤-0.44(Ct 650 )+116...(2a)。
the liquid crystal panel according to the first embodiment of the present invention is in the O-mode, and the alignment direction (initial alignment direction) of the liquid crystal molecules of the liquid crystal cell in the no-electric-field state is parallel to the absorption axis direction of the second polarizer. In the O-mode liquid crystal panel, an optically anisotropic element is disposed between the liquid crystal cell and the first polarizer, that is, on the visual confirmation side of the liquid crystal cell.
In the first embodiment, it is preferable that the retardation Rt in the thickness direction of the optically anisotropic element has a wavelength of 550nm 550 (nm) and a thickness-direction retardation Ct of 550nm wavelength in a green transmission region of a color filter 550 (nm) satisfies the following formula (3 a):
0.97(Ct 550 )+73≤Rt 550 ≤0.49(Ct 550 )+205...(3a)。
the liquid crystal panel according to the second embodiment of the present invention is in E-mode, and the initial alignment direction of the liquid crystal molecules of the liquid crystal cell is perpendicular to the absorption axis direction of the second polarizer. In the E-mode liquid crystal panel, an optically anisotropic element is disposed between the liquid crystal cell and the second polarizer, that is, on the light source side of the liquid crystal cell.
In the second embodiment, it is preferable that the retardation Rt in the thickness direction of the optically anisotropic element has a wavelength of 550nm 550 (nm) and a thickness-direction retardation Ct of 550nm wavelength in a green transmission region of a color filter 550 (nm) satisfies the following formula (8 a):
0.69(Ct 550 )+70≤Rt 550 ≤1.35(Ct 550 )+200...(8a)。
the liquid crystal display device of the present invention includes a light source disposed on the second main surface side of the liquid crystal panel.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to provide a liquid crystal display device capable of reducing black brightness at the time of visual confirmation from an oblique direction and suppressing red coloring of black display by performing optical design in consideration of birefringence of a color filter, and excellent in visual confirmation.
Drawings
Fig. 1 is a conceptual diagram of the structure of a liquid crystal panel (O-mode) of the first embodiment.
Fig. 2 is a schematic cross-sectional view of the liquid crystal display device (O mode) of the first embodiment.
Fig. 3 is a conceptual diagram of the structure of a liquid crystal panel (E-mode) of the second embodiment.
Fig. 4 is a schematic cross-sectional view of a liquid crystal display device (E-mode) of the second embodiment.
Fig. 5 is an explanatory diagram illustrating a state in which the optical anisotropic element optically compensates for the axial direction shift exhibited by the polarizer by using the poincare sphere.
Fig. 6 is a conceptual diagram of the structure of a liquid crystal panel (O-mode) of the reference example.
Fig. 7 is a conceptual diagram of the structure of a liquid crystal panel (E-mode) of the reference example.
Fig. 8 is an explanatory diagram illustrating a state of optical compensation of the liquid crystal panel of the O-mode using poincare balls.
Fig. 9 is an explanatory diagram illustrating a state of optical compensation of the liquid crystal panel in the E-mode using poincare balls.
Fig. 10 is a simulation result of chromaticity of black display of the liquid crystal display device of O mode.
Fig. 11 is a simulation result of chromaticity of black display of the E-mode liquid crystal display device.
Fig. 12 is a graph plotting conditions under which chromaticity u' of black display of the liquid crystal display device of the O mode becomes a specific value.
Fig. 13 is a graph plotting conditions under which the luminance of black display of the liquid crystal display device of the O mode becomes a specific value.
Fig. 14 is a graph plotting conditions under which chromaticity u' of black display of the liquid crystal display device of the E mode becomes a specific value.
Fig. 15 is a graph plotting a condition that the brightness of black display of the liquid crystal display device of the E mode becomes a specific value or less.
Detailed Description
[ outline of the entire liquid Crystal Panel ]
Fig. 1 is a conceptual diagram showing the arrangement of optical components in a liquid crystal panel 101 according to the first embodiment. Fig. 2 is a schematic cross-sectional view of a liquid crystal display device 201 including a liquid crystal panel 101 and a light source 110. Fig. 3 is a conceptual diagram showing the arrangement of optical components in the liquid crystal panel 102 according to the second embodiment. Fig. 4 is a schematic cross-sectional view of a liquid crystal display device 202 including the liquid crystal panel 102 and the light source 110.
The liquid crystal panel includes a first polarizer 30 disposed on a first main surface (visual inspection side) of the liquid crystal cell 20, and a second polarizer 40 disposed on a second main surface (light source side) of the liquid crystal cell 20. The absorption axis direction 35 of the first polarizer 30 is orthogonal to the absorption axis direction 45 of the second polarizer 40.
The liquid crystal panel 101 and the liquid crystal display device 201 of the first embodiment are in the O-mode, and the absorption axis direction 45 of the second polarizer 40 disposed on the light source 110 side of the liquid crystal cell 20 is parallel to the initial alignment direction 11 of the liquid crystal molecules of the liquid crystal layer 10. The liquid crystal panel 102 and the liquid crystal display device 202 of the second embodiment are in the E-mode, and the absorption axis direction 45 of the second polarizer 40 disposed on the light source 110 side of the liquid crystal cell 20 is orthogonal to the initial alignment direction 11 of the liquid crystal molecules of the liquid crystal layer 10.
The liquid crystal panel of the present invention includes an optically anisotropic element between the first polarizer 30 and the second polarizer 40. The O-mode liquid crystal panel 101 of the first embodiment includes the optically anisotropic element 50 between the liquid crystal cell 20 and the first polarizer 30. The E-mode liquid crystal panel 102 of the second embodiment includes the optically anisotropic element 60 between the liquid crystal cell 20 and the second polarizer 40. In either mode, the absorption axis direction 45 of the second polarizer 40 is parallel to the slow axis directions 53, 63 of the optically anisotropic elements 50, 60.
In the present specification, "orthogonal" means not only a case of being completely orthogonal but also a case of being substantially orthogonal, and an angle thereof is generally in a range of 90±2°, preferably 90±1°, more preferably 90±0.5. Likewise, "parallel" means not only perfectly parallel but also substantially parallel, and its angle is usually within ±2°, preferably within ±1°, more preferably within ±0.5°.
[ liquid Crystal cell ]
The liquid crystal cell 20 includes a liquid crystal layer 10 between a first substrate 21 and a second substrate 25. A color filter 22 is provided on a first substrate 21 (color filter substrate) disposed on the visual inspection side of the liquid crystal layer. The color filter 22 has at least a green transmission region 22G and a red transmission region 22R. A switching element (typically, a TFT element) for controlling the alignment direction of the liquid crystal is provided on the second substrate 25 (TFT substrate) disposed on the light source side of the liquid crystal layer 10.
In the green transmission region 22G of the color filter 22, a green filter having a relatively high transmittance for light having a wavelength of around 500 to 600nm is provided. The green filter preferably has a maximum transmittance at a wavelength of about 500 to 600 nm. The transmittance of the green transmission region at a wavelength of 550nm is, for example, 30% or more. The transmittance of the green transmission region at a wavelength of 450nm is preferably 10% or less. The transmittance of the green transmission region at a wavelength of 650nm is preferably 10% or less, more preferably 5% or less.
In the red transmission region 22R, a red filter having a relatively high transmittance for visible light having a wavelength longer than 600nm is provided. The transmittance of the red light transmission region at a wavelength of 650nm is, for example, 30% or more. The transmittance at a wavelength of 550nm and the transmittance at a wavelength of 450nm in the red transmission region are each preferably 10% or less, more preferably 5% or less.
The color filter 22 may include a region other than the green transmission region 22G and the red transmission region 22R, and generally includes a blue transmission region 22B. The blue transmission region 22B is provided with a blue filter having a relatively high transmittance for visible light having a wavelength shorter than 500 nm. The transmittance of the blue transmission region at a wavelength of 450nm is, for example, 30% or more. The transmittance at a wavelength of 550nm and the transmittance at a wavelength of 650nm in the blue transmission region are each preferably 10% or less, more preferably 5% or less.
The color filter may further have a light-transmitting region having a relatively high light transmittance with respect to a specific wavelength region other than the above. Preferably, a black matrix is provided at the boundary between adjacent transmission regions.
The liquid crystal layer 10 includes liquid crystal molecules that are horizontally aligned in a non-electric field state. The horizontally aligned liquid crystal molecules refer to a state in which alignment vectors of the liquid crystal molecules are aligned parallel and uniformly with respect to a substrate plane. The alignment vector of the liquid crystal molecules may be slightly tilted (pre-tilted) with respect to the substrate plane. The pretilt angle of the liquid crystal cell is usually 3 ° or less, preferably 1 ° or less, and more preferably 0.5 ° or less.
As a liquid crystal cell including liquid crystal molecules which are horizontally aligned in an electroless state, a transverse electric field effect (IPS) mode, a Fringe-field Switching (FFS) mode, a ferroelectric liquid crystal (FLC, ferroelectric Liquid Crystal) mode, and the like can be cited. As the liquid crystal molecules, nematic liquid crystal, smectic liquid crystal, or the like can be used. In general, nematic liquid crystal is used for IPS mode and FFS mode liquid crystal cells, and smectic liquid crystal is used for FLC mode liquid crystal cells.
[ polarizing Member ]
The first polarizer 30 is disposed on the first principal surface side of the liquid crystal cell 20, and the second polarizer 40 is disposed on the second principal surface side. The polarizer converts natural light or arbitrary polarized light into linear polarized light. As the first polarizer 30 and the second polarizer 40, any appropriate polarizers may be used according to purposes. Examples of the polarizing member include a polarizing member obtained by uniaxially stretching a dichroic substance such as iodine or a dichroic dye by adsorbing the substance to a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film or an ethylene-vinyl acetate copolymer partially saponified film, a polyvinyl alcohol dehydration product, a polyvinyl chloride dehydrochlorination product, and the like.
Among these polarizers, from the viewpoint of having high polarization intensity, a polyvinyl alcohol (PVA, polyvinyl alcohol) based polarizer in which a dichroic substance such as iodine or a dichroic dye is adsorbed to a polyvinyl alcohol film such as polyvinyl alcohol or partially formalized polyvinyl alcohol and oriented in a specific direction is preferably used. For example, a PVA-based polarizing material can be obtained by iodine dyeing and stretching a polyvinyl alcohol film.
As the PVA-based polarizing material, a thin polarizing material having a thickness of 10 μm or less may be used. Examples of the thin polarizing material include thin polarizing films described in Japanese patent application laid-open No. 51-069644, japanese patent application laid-open No. 2000-338329, WO2010/100917 handbook, japanese patent application No. 4691205 and Japanese patent application No. 4751481. Such a thin polarizer is obtained, for example, by a method including a step of stretching a PVA-based resin layer and a stretching resin base material in a laminate, and a step of iodine dyeing.
[ optically Anisotropic component ]
The optically anisotropic elements 50 and 60 are retardation films having refractive index nx in the slow axis direction in the plane, refractive index ny in the slow axis direction in the plane, and refractive index nz in the thickness direction satisfying nx > nz > ny. The polarizers 30, 40 disposed above and below the liquid crystal cell 20 are disposed so that the absorption axis directions 35, 45 are orthogonal, but when the liquid crystal panel is visually confirmed from an oblique direction, the angle formed by the polarizers 30, 40 in the expressed absorption axis direction is greater than 90 ° (a shift from orthogonal polarization occurs), and thus light leakage occurs.
By disposing a retardation film satisfying nx > nz > ny between the liquid crystal cell 20 and the polarizers 30, 40, it is possible to compensate for the axial misalignment exhibited by the polarizers, and to reduce light leakage when visually confirming the screen from an oblique direction. In particular, the black brightness at an angle of 45 degrees (azimuth angle of 45 degrees, 135 degrees, 225 degrees, 315 degrees) with respect to the absorption axis of the polarizer is reduced, and the contrast is improved.
In the O-mode liquid crystal panel 101 of the first embodiment, the optically anisotropic element 50 is disposed between the liquid crystal cell 20 and the first polarizer 30 on the visual confirmation side. In the E-mode liquid crystal panel 102 of the second embodiment, the optically anisotropic element 60 is disposed between the liquid crystal cell 20 and the second polarizer 40 on the light source side.
Front retardation Re of 550nm wavelength of optically anisotropic components 50, 60 550 Preferably 150 to 400nm, more preferably 180 to 370nm, and even more preferably 200 to 350nm. Thickness direction retardation Rt of optical anisotropic component with wavelength of 550nm 550 Preferably 75The wavelength is from about 200nm, more preferably from about 90 to 185nm, still more preferably from about 100 to 175nm. The front retardation Re and the thickness retardation Rt are defined by the following expressions, using the refractive index nx in the slow axis direction in the plane, the refractive index ny in the slow axis direction in the plane, and the refractive index nz in the thickness direction:
Re＝(nx－ny)×d
Rt＝(nx－nz)×d。
The ranges of Re and Rt of the optically anisotropic element in consideration of retardation in the thickness direction of the color filter will be described in detail below.
The optically anisotropic members 50, 60 preferably have Nz coefficients defined as nz= (nx-Nz)/(nx-ny) of 0.2 to 0.8. According to the definition of Re and Rt above, it may also be expressed as nz=rt/Re. In the present specification, the Nz coefficient is calculated from the refractive index at a wavelength of 650 nm. That is, the Nz coefficient is the front retardation Re of 650nm 650 Retardation Rt in the thickness direction 650 Ratio Rt of (1) 650 /Re 650 . Therefore, the optically anisotropic member preferably has Rt 650 /Re 650 0.2 to 0.8. In the retardation film produced by stretching the polymer film, generally, the Nz coefficient calculated from the refractive index at a wavelength of 550nm is substantially the same as the Nz coefficient calculated from the refractive index at a wavelength of 650 nm.
The Nz coefficient of the optically anisotropic element is more preferably 0.3 to 0.7, and still more preferably 0.4 to 0.6. The closer the Nz coefficient is to 0.5, the lower the light leakage in a wide viewing angle range tends to be.
Examples of the material constituting the optically anisotropic member include polycarbonate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyarylate resins, sulfone resins such as polysulfone and polyethersulfone, sulfur resins such as polyphenylene sulfide, polyimide resins, cyclic polyolefin (polynorbornene) resins, polyamide resins, polyolefin resins such as polyethylene and polypropylene, cellulose esters, and the like. Liquid crystal materials may also be used as the material of the optically anisotropic component.
In the case of using a polymer material, the molecular orientation in a specific direction can be improved by extending or contracting the polymer film in at least one direction, thereby producing an optically anisotropic device (retardation film). An optically anisotropic element having refractive index anisotropy of nx > nz > ny can be obtained by stretching a polymer film and a heat-shrinkable film in one direction while the film is shrunk in a direction orthogonal to the stretching direction by a shrinkage force of the heat-shrinkable film in a state where the polymer film and the heat-shrinkable film are laminated.
The thickness of the optically anisotropic element may be appropriately selected depending on the material constituting the optically anisotropic element, and the like. When a polymer material is used, the thickness of the optically anisotropic element is usually about 3 μm to 200 μm. When a liquid crystal material is used, the thickness of the optically anisotropic element (thickness of the liquid crystal layer) is usually about 0.1 μm to 20 μm.
The optically anisotropic element may have specific Re and Rt, and the material, thickness, and manufacturing method of the optically anisotropic element are not limited to the above.
[ principle of optical Compensation of optically Anisotropic component ]
In the present invention, by setting the optical characteristics of the optically anisotropic element according to the birefringence of the color filter, both the shift in the axial direction of the polarizer and the influence of the birefringence of the color filter can be optically compensated, and a liquid crystal display device with less light leakage in visual confirmation from the oblique direction and a neutral black display hue can be obtained. Specifically, the optical characteristics of the optically anisotropic element are set in such a manner that the thickness direction retardation Ct of the green transmission region 22G of the color filter 22 at a wavelength of 550nm 550 Retardation Rt in thickness direction of wavelength 550nm of optically anisotropic members 50, 60 550 Satisfy a specific relationship; and the thickness direction retardation Ct of the red transmission region 22R of the color filter 22 with a wavelength of 650nm 650 Retardation Rt in thickness direction of 650nm with wavelength of optical anisotropic members 50, 60 650 Satisfying a specific relationship.
Optical Compensation without considering the birefringence of the color Filter
First, a principle of compensating for the axial direction shift exhibited by the polarizer using an optical anisotropic element having refractive index anisotropy of nx > nz > ny will be described with reference to fig. 5. In fig. 5, the state of compensating the axial direction shift exhibited by the polarizers 30, 40 of the liquid crystal panel 101 of the O-mode shown in fig. 1 by the optically anisotropic element 50 is described using poincare spheres.
When the liquid crystal display device is visually confirmed from the front, the light transmitted through the light source-side polarizer 40 is linearly polarized, and the light transmitted through the polarizer passes through a point P on the equator of the poincare sphere 0 And (3) representing. Since the absorption axis direction 35 of the visual inspection side polarizer 30 is orthogonal to the absorption axis direction 45 of the light source side polarizer 40, the light transmitted through the visual inspection side polarizer 30 passes through the point P on the equator of poincare sphere 1 And (3) representing.
Since the initial alignment direction 11 of the liquid crystal molecules in the liquid crystal cell 20 is parallel to the absorption axis direction 45 of the polarizer 40, the polarization state of the light transmitted through the polarizer 40 does not change even after the light is transmitted through the liquid crystal cell. That is, the polarized state of the light transmitted through the liquid crystal cell does not go from the point P on the Poincar sphere 0 And (5) moving. Light P transmitted through liquid crystal cell 20 0 And light P transmitted through the visual inspection side polarizer 30 1 Since the linear polarizations are orthogonal to each other, all the light transmitted through the liquid crystal cell 20 is absorbed by the visual inspection side polarizer 30, and black display can be realized.
If the liquid crystal display device is visually confirmed from the direction of the slope (polar angle) θ of 45 ° from the azimuth angle with reference to the absorption axis direction of the polarizer and with reference to the normal direction of the screen, the represented axis direction of the light source side polarizer 40 is from P 0 Move to P' 0 The apparent axial direction of the visual confirmation-side polarizer 30 is from P 1 Move to P' 1 . The larger the polar angle θ, the larger the variation in the axial direction exhibited by the polarizer.
Light P 'transmitted through the light source-side polarizer 40' 0 And light P 'transmitted through the visual inspection side polarizer 30' 1 There is no orthogonal relationship, and thus light leakage of black display occurs. In order to prevent light leakage due to such a shift in the axial direction, it is necessary to set the polarization state of the light transmitted through the liquid crystal cell 20 to be equal to the light P 'transmitted through the visual inspection side polarizer 30' 1 Orthogonal linear polarization P A 。
In the O-mode liquid crystal panel 101 shown in fig. 1, the absorption axis direction 45 of the light source side polarizer 40 is parallel to the initial alignment direction 11 of the liquid crystal cell 20, and therefore the initial alignment direction 11 that appears when visually confirmed from the oblique direction moves similarly to the absorption axis direction 45 of the light source side polarizer. Therefore, the polarization state of the light transmitted through the polarizer 40 is not changed even after the light is transmitted through the liquid crystal cell, and is not changed from the point P 'on the poincare sphere' 0 And (5) moving.
The light transmitted through the liquid crystal cell 20 is incident on the optically anisotropic element 50. The optical anisotropic element 50 having an Nz coefficient of 0.5 was visually confirmed from any angle, and the optical axis direction was not changed, and was connected to P 0 And P 1 There is a slow axis on the line of (a). The front retardation (retardation of light with respect to the normal direction) Re of the optically anisotropic element 50 is 1/2 of the wavelength λ. In the case of nz=0.5, even if the transmission direction of light is changed, the retardation to be displayed is not changed and is fixed at λ/2. The retardation of lambda/2 corresponds to the phase difference pi, and therefore the light P 'transmitted through the liquid crystal cell 20' 0 By passing through the optically anisotropic element 50 with axis P 0 -P 1 Rotated 180 ° clockwise on the poincare sphere for the centre, moved to point P A 。
As described above, the linearly polarized light P A Light P 'transmitted through the visual inspection side polarizer 30' 1 Orthogonal linear polarization, so that the polarization state of light P is changed by the optical anisotropic element 50 A The black display can be realized by the absorption by the visual confirmation-side polarizing element 30.
As shown in fig. 6, in the O-mode liquid crystal panel 106 in which the absorption axis direction 45 of the second polarizer 40 is orthogonal to the slow axis direction 53 of the optically anisotropic element 50, the polarization state is converted by the optically anisotropic element 50 to a half turn clockwise on the poincare sphere, and therefore, as shown by the one-dot chain line in fig. 5, the locus on the poincare sphere passes through the southern hemisphere. Since the rotation angle is 180 °, the polarized light state of the light transmitted through the optically anisotropic element 50 is changed from the point on the poincare sphere as in the case of the liquid crystal panel shown in fig. 1P A Indicating and being absorbed by the visual confirmation side polarizer 30, black display can be realized.
In the E-mode liquid crystal panel 102 shown in fig. 3, the initial alignment direction 11 of the liquid crystal molecules of the liquid crystal cell 20 is orthogonal to the absorption axis direction 45 of the light source side polarizer 40, and therefore, the initial alignment direction 11 exhibited upon visual confirmation from the oblique direction is offset from the absorption axis direction 45 of the light source side polarizer 40 by 90 °. Therefore, the optically anisotropic element 60 is disposed between the light source-side polarizer 40 and the liquid crystal cell 20, so that the linear polarization P 'passing through the light source-side polarizer 40 is achieved' 0 Moved to a point P on poincare sphere by an optically anisotropic element 60 A . Thus, the linearly polarized light P 'from the light source-side polarizer 40' 0 Conversion to linearly polarized light P by optically anisotropic component 60 A Then is incident on the liquid crystal cell 20, whereby the polarized light of the light transmitted through the liquid crystal cell is not transmitted from P A The change is absorbed by the visual confirmation-side polarizing element 30, and thus black display can be realized.
As shown in fig. 7, in the E-mode liquid crystal panel 107 in which the absorption axis direction 45 of the second polarizer 40 is orthogonal to the slow axis direction 63 of the optically anisotropic element 60, the path on the poincare sphere for the conversion of the polarization state by the optically anisotropic element 60 is different from the northern hemisphere or the southern hemisphere, but the principle of optical compensation is the same as that of the liquid crystal panel 102 shown in fig. 3.
As described above, the optical design of the optically anisotropic element is independent of the angle (parallel or orthogonal) between the optical axis direction of the optically anisotropic element and the optical axis direction of the polarizer, and the angle (O-mode or E-mode) between the initial alignment direction of the liquid crystal cell and the optical axis direction of the polarizer, regardless of the influence of the birefringence of the color filter.
< thickness direction retardation of color Filter >)
As described above, the retardation in the plane of the color filter 22 provided on the visual inspection side of the liquid crystal layer 10 in the liquid crystal cell 20 is substantially 0, but the retardation in the thickness direction is several nm to several tens nm. In the green transmission region 22G, the transmittance is highestThe thickness-direction retardation of light in the vicinity of 550nm affects visibility. For the same reason, in the red transmission region 22R, retardation in the thickness direction of light in the vicinity of 650nm, which has a high transmittance, affects visibility. Therefore, in evaluating the retardation in the thickness direction of the color filter, it is appropriate to use the retardation Ct in the thickness direction of 550nm for the green transmission region (green color filter) 550 Evaluation was made by using a thickness direction retardation Ct having a wavelength of 650nm for a red transmission region (red color filter) 650 An evaluation is performed.
In order to suppress light leakage in visual confirmation from an oblique direction, it is preferable that the retardation in the thickness direction of the color filter is small. Thickness direction retardation Ct of green transmission region with wavelength of 550nm 550 Preferably 50nm or less, more preferably 40nm or less, further preferably 35nm or less, particularly preferably 30nm or less. Thickness direction retardation Ct of red region of color filter with wavelength of 650nm 650 Preferably 50nm or less, more preferably 40nm or less, further preferably 35nm or less, particularly preferably 30nm or less. The thickness direction retardation of the color filter is preferably 0, but it is difficult to make the thickness direction retardation of the color filter completely 0. Thus Ct is 550 Ct is as follows 650 Greater than 0.Ct is (Ct) 550 Ct is as follows 650 For example, the wavelength may be 1nm or more, 3nm or more, or 5nm or more.
< principle of optical Compensation taking into account birefringence of color Filter >
First, with reference to a of fig. 8, an influence of retardation in the thickness direction of the color filter of the O-mode liquid crystal panel 101 shown in fig. 1 and optical compensation taking this influence into consideration will be described. In the case of visual confirmation from the oblique direction, the polarization state of the light after passing through the liquid crystal layer 10 of the liquid crystal cell 20 is determined by the point P 'on the poincare sphere' 0 This means that the same is true for the case where the birefringence of the color filter is not considered (fig. 5).
The light transmitted through the liquid crystal layer is incident on the color filter 22. The front retardation of the color filter is approximately 0 and has a specific thickness direction retardation, and thus can be approximated as a negative C plate having refractive index anisotropy of nx=ny > nz.Light in an oblique direction changes polarization state due to the influence of retardation in the thickness direction of the negative C plate, and the meridian on the Poincare sphere passes from point P' 0 Move south down to point P C 。
In the same way as in the case of fig. 5, when the phase difference of the optically anisotropic element is pi (when rotated 180 ° on the poincare sphere), the polarization state of the light transmitted through the optically anisotropic element is changed from point P 'of a of fig. 8' A Indicating being located in the northern hemisphere of the poincare sphere. In order to make the light transmitted through the optically anisotropic element 50 become a point P on the equator A The linear polarization represented must be such that the rotation angle on the poincare sphere due to the optically anisotropic element is greater than 180 °. That is, considering the influence of birefringence of the color filter, in the O-mode liquid crystal panel 101 shown in fig. 1, in order to make the light transmitted through the optically anisotropic element 50 linearly polarized, it is necessary to make the phase difference of the optically anisotropic element 50 larger than pi.
Fig. 8B shows a state of optical compensation of the O-mode liquid crystal panel 106 of fig. 6 in which the absorption axis direction 45 of the second polarizer 40 is orthogonal to the slow axis direction 53 of the optically anisotropic element 50. The polarized light state of the light transmitted through the color filter 22, which is a negative C plate approximation, is represented by point P of the southern hemisphere of the poincare sphere, as in the case of a of fig. 8 C And (3) representing. If the phase difference of the optically anisotropic element is pi, the optical element is formed from point P C By rotating 180 ° by half a turn clockwise on the poincare sphere, the point P 'of the northern hemisphere is reached by the equator' A . In order to make the light transmitted through the optically anisotropic element 50 become a point P on the equator A The linear polarization represented must be such that the rotation angle on the poincare sphere due to the optically anisotropic element is less than 180 °. That is, considering the influence of birefringence of the color filter, in the O-mode liquid crystal panel 106 shown in fig. 6, in order to make the light transmitted through the optically anisotropic element 50 linearly polarized, it is necessary to make the phase difference of the optically anisotropic element 50 smaller than pi.
Fig. 9 a shows the E-mode of fig. 7 in which the absorption axis direction 45 of the second polarizer 40 is orthogonal to the slow axis direction 63 of the optically anisotropic element 60The optical compensation of the liquid crystal panel 107. As in the case of fig. 8 a and 8B, the light P after passing through the liquid crystal cell L The polarization state changes by passing through the color filter 22, which is a negative C-plate approximation, down the meridian on the poincare sphere. In order to make the light after passing through the color filter become linear polarized light P A And is absorbed by the visual inspection side polarizer 30, it is necessary to make the light P after passing through the liquid crystal cell L A northern hemisphere located on the poincare sphere.
As in the case of FIG. 5, if the retardation of the optically anisotropic element is pi, the linearly polarized light P 'transmitted through the light source-side polarizer is made' 0 Moved to a point P on poincare sphere by an optically anisotropic component A The polarized state of the light transmitted through the liquid crystal cell is not changed from P A And (3) a change. However, since the light transmitted through the liquid crystal cell goes down along the meridian on the poincare sphere due to the influence of the retardation in the thickness direction of the color filter, the light transmitted through the color filter becomes elliptical polarized light located in the southern hemisphere, and the light not absorbed by the visual-confirmation-side polarizing element 30 is visually confirmed as light leakage.
In the E-mode liquid crystal panel 107 shown in fig. 7, as shown in a of fig. 9, appropriate optical compensation can be performed by making the phase difference of the optically anisotropic element 60 smaller than pi (making the rotation angle on the poincare sphere by the optically anisotropic element smaller than 180 °). The polarization state of light transmitted through an optically anisotropic element having a phase difference of less than pi is determined by point P on the southern hemisphere of poincare sphere R And (3) representing. The polarization state is switched by the influence of the phase difference of the liquid crystal layer 10, with axis P A -P' 1 The polarization state of the light after passing through the liquid crystal layer 10 is changed from the point P on the northern hemisphere of the poincare sphere by rotating the center clockwise on the poincare sphere L And (3) representing. As described above, if the light P after passing through the liquid crystal cell L Through the color filter 22, the point P on the equator is reached along the meridian south of the Poincare sphere A . Therefore, the light P after passing through the color filter A The light leakage can be prevented by the proper absorption by the visual confirmation-side polarizing element 30.
B of FIG. 9 shows a second biasThe absorption axis direction 45 of the optical element 40 is parallel to the slow axis direction 63 of the optically anisotropic element 60, and the E-mode liquid crystal panel 102 of fig. 3 is optically compensated. In the liquid crystal panel 102, if the phase difference of the optically anisotropic element 60 is made larger than pi (the rotation angle on the poincare sphere by the optically anisotropic element is made larger than 180 °), the polarization state of the light after passing through the optically anisotropic element is located at a point P on the southern hemisphere of the poincare sphere R . Thereafter, as in the case of a of fig. 9, the liquid crystal layer 10 is transmitted to the point P on the northern hemisphere L Through the color filter 22 to the point P on the equator A Therefore, the light P after passing through the color filter A Is properly absorbed by the visual confirmation side polarizer 30.
As described above, in order to optically compensate for the influence of birefringence of the color filter by the optically anisotropic element, it is necessary to adjust the phase difference of the optically anisotropic element according to the magnitude of the retardation in the thickness direction of the color filter. In the case where the absorption axis direction of the light source-side polarizer is parallel to the slow axis direction of the optically anisotropic element, that is, in the O-mode liquid crystal panel 101 (see a of fig. 8) shown in fig. 1 and the E-mode liquid crystal panel 102 (see B of fig. 9) shown in fig. 3, in order to perform appropriate optical compensation, it is necessary to make the phase difference of the optically anisotropic element larger than pi (make the retardation larger than λ/2). On the other hand, in the case where the absorption axis direction of the light source-side polarizer is orthogonal to the slow axis direction of the optically anisotropic element, that is, in the O-mode liquid crystal panel 106 (see B of fig. 8) shown in fig. 6 and the E-mode liquid crystal panel 107 (see a of fig. 9) shown in fig. 7, in order to perform appropriate optical compensation, it is necessary to make the phase difference of the optically anisotropic element smaller than pi (to make the retardation smaller than λ/2).
[ optical design of optically Anisotropic component ]
Hereinafter, preferable optical characteristics of the optically anisotropic element corresponding to the retardation in the thickness direction of the color filter of the liquid crystal cell will be described, together with the results of the optical simulation.
In the optical simulation, luminance of black display and chromaticity (u ', v') of CIE1976 color space of black display in the azimuth angle of 45 ° and the polar angle of 60 ° were obtained by using a simulator "LCD MASTER ver.8.1.0.3" for liquid crystal display manufactured by Shintec corporation and using an extended function of LCD Master.
In the simulation of the O-mode liquid crystal display device, as shown in fig. 2, a model in which a light source side polarizer 40, an IPS liquid crystal cell 20 having a color filter 22 on the visual inspection side of a liquid crystal layer 10, an optically anisotropic element 50, and a visual inspection side polarizer 30 are laminated in this order from the light source 110 side was used as a simulation model. In the simulation of the E-mode liquid crystal display device, as shown in fig. 4, a model in which a light source side polarizer 40, an optically anisotropic element 60, an IPS liquid crystal cell 20 having a color filter 22 on the visual inspection side of a liquid crystal layer 10, and a visual inspection side polarizer 30 are laminated in this order from the light source 110 side was used as a simulation model.
In the simulation, the front retardation of the liquid crystal layer of the IPS liquid crystal cell was set to 339nm, and the pretilt angle was set to 0 °. The Nz coefficient of the optically anisotropic element was 0.5, and the delayed wavelength dispersion was Re 650 /Re 550 ＝Rt 650 /Rt 550 =0.95, rt is given 650 Changing to various values. The color filter changes the thickness direction retardation Ct of the green transmission region with the wavelength of 550nm according to the 5nm scale in the range of 0-60 nm 550 And a thickness direction retardation Ct of the red transmission region at a wavelength of 650nm 650 。
In the liquid crystal panel of O mode, ct will be caused 650 Rt (Rt) 650 Chromaticity of black display when changing to various values is shown in fig. 10 a and 10B. In the E-mode liquid crystal panel, ct will be caused 650 Rt (Rt) 650 Chromaticity of black display when changing to various values is shown in fig. 11 a and 11B.
Fig. 10 a shows simulation results of a liquid crystal panel 101 (see fig. 8 a for the optical compensation principle) in which the absorption axis direction 45 of the light source-side polarizer 40 and the slow axis direction 53 of the optically anisotropic element 50 are parallel to each other as shown in fig. 1. Fig. 10B shows simulation results of a liquid crystal panel 106 (see fig. 8B for the optical compensation principle) in which the absorption axis direction 45 of the light source-side polarizer 40 is orthogonal to the slow axis direction 53 of the optically anisotropic element 50 as shown in fig. 6. Fig. 11 a shows simulation results of a liquid crystal panel 107 (see fig. 9 a for the optical compensation principle) in which the absorption axis direction 45 of the light source-side polarizer 40 is orthogonal to the slow axis direction 63 of the optically anisotropic element 60 as shown in fig. 7. Fig. 11B shows simulation results of the liquid crystal panel 102 (see fig. 9B for the optical compensation principle) in which the absorption axis direction 45 of the light source-side polarizer 40 is parallel to the slow axis direction 63 of the optically anisotropic element 60 as shown in fig. 3.
As shown in fig. 10B and 11 a, when the absorption axis direction of the light source-side polarizer is orthogonal to the slow axis direction of the optically anisotropic element, it was found that retardation Ct was generated in the thickness direction of the red transmission region of the color filter 650 Becomes larger, and the thickness direction retardation Rt of the optical anisotropic component is increased 650 The maximum value of u' at the time of change tends to become smaller. In addition, at Ct 650 In the range of 0 to 60nm, regardless of the thickness-direction retardation Rt of the optically anisotropic member 650 No more than 0.35. That is, it is understood that when the absorption axis direction of the light source-side polarizer is orthogonal to the slow axis direction of the optically anisotropic element, neither the O-mode liquid crystal panel 106 shown in fig. 6 nor the E-mode liquid crystal panel 107 shown in fig. 7 is significantly colored red in the black display screen when visually confirmed from the oblique direction.
On the other hand, as shown in fig. 10 a and 11B, when the absorption axis direction of the light source-side polarizer is parallel to the slow axis direction of the optically anisotropic element, it was found that the retardation Ct was in accordance with the thickness direction of the red transmission region of the color filter 650 Becomes larger, and the thickness direction retardation Rt of the optical anisotropic component is increased 650 The maximum value of u' at the time of change becomes larger in the direction of inclination. In addition, in fig. 10 a and 11B, u' is delayed by Ct in the thickness direction of the red transmission region of the color filter, as compared with fig. 10B and 11 a 650 Thickness-direction retardation Rt of optically anisotropic member 650 But vary considerably and situations exceeding 0.35 are also found.
From these results, it is clear that when the absorption axis direction of the light source-side polarizer is parallel to the slow axis direction of the optically anisotropic element, both the O-mode liquid crystal panel 101 shown in fig. 1 and the E-mode liquid crystal panel 102 shown in fig. 3 are visually confirmed from the oblique direction due to the influence of the birefringence of the red transmission region of the color filter, and black display is colored red. That is, it is known that in a liquid crystal panel in which the absorption axis direction of the light source-side polarizer is parallel to the slow axis direction of the optically anisotropic element, when the optical compensation is performed in consideration of the influence of the birefringence of the color filter, it is necessary to perform the optical design of the optically anisotropic element so as to reduce the coloring of black display due to the light leakage of red as well as to reduce the light leakage of green and to improve the contrast.
< first embodiment: optical design of liquid crystal panel in O-mode
(adjustment of chromaticity)
Fig. 12 is a graph plotting conditions under which chromaticity of black display becomes a specific value, based on simulation results of the O-mode liquid crystal panel 101 shown in fig. 1. The horizontal axis represents the thickness direction retardation Ct of 650nm of the red transmission region of the color filter 650 The longitudinal axis is the thickness direction retardation Rt of the optically anisotropic component at a wavelength of 650nm 650 . At each Ct 650 The black color u 'in the azimuth angle of 45 ° and the polar angle of 60 ° is represented by a black circle mark and a black triangle mark at a point where the chromaticity u' is 0.35. At Rt 650 In the case of being located between the black circle mark and the black triangle mark, u' exceeds 0.35, and the black display is colored red to be visually confirmed. At Rt 650 When u' is less than 0.35, the black display can be suppressed from being colored in red, if it is positioned on the upper side of the black circle mark or on the lower side of the black triangle mark.
As can be seen from fig. 12, both the upper limit side and the lower limit side of the boundary where u' =0.35 can be approximated by straight lines. The straight line in the graph is represented by the following formulas (1) and (2):
Rt 650 ＝0.37(Ct 650 )+116...(1)
Rt 650 ＝-0.44(Ct 650 )+116...(2)。
thus, color filteringThe thickness direction retardation Ct of the red transmission region 22R of the sheet 22 at a wavelength of 650nm 650 Thickness direction retardation Rt with wavelength 650nm of optically anisotropic element 50 650 When the following expression (1 a) or (2 a) is satisfied, u' is 0.35 or less, and black display with reduced red tone can be realized.
Rt 650 ≥0.37(Ct 650 )+116...(1a)
Rt 650 ≤-0.44(Ct 650 )+116...(2a)。
The white circle mark and the white triangle mark in fig. 12 indicate a point where the chromaticity u' of the black display becomes 0.314. At Rt 650 In the case of being located between the white circle mark and the black circle mark, u' is 0.314 to 0.35, and Rt is 650 In the case of being located further up than the whiter circular marks, u' is smaller than 0.314. Similarly, at Rt 650 In the case of being located between the white triangle mark and the black triangle mark, u' is 0.314 to 0.35, at Rt 650 In the case of a lower side than the whitewashed triangular mark, u' is less than 0.314.
The boundary of u' =0.314, represented by the whited circle mark, can be in a straight line parallel to the above formula (1): rt (Rt) 650 ＝0.37(Ct 650 ) +121 approximation. The demarcation of u' =0.314, represented by the whited triangle mark, can be in a straight line parallel to the above formula (2): rt (Rt) 650 ＝-0.44(Ct 650 ) +108 approximation.
Therefore, the retardation Ct in the thickness direction of the red transmission region of the color filter at a wavelength of 650nm 650 Thickness direction retardation Rt with wavelength 650nm of optically anisotropic element 650 When the following expression (1 b) or (2 b) is satisfied, u' is 0.314 or less, and black display with a further reduced red tone can be realized.
Rt 650 ≥0.37(Ct 650 )+121...(1b)
Rt 650 ≤-0.44(Ct 650 )+108...(2b)。
From the above results, it is considered that in the liquid crystal panel of the O-mode shown in fig. 1, ct 650 And Rt 650 When the following formula (1 c) or (2 c) is satisfied, a black display with reduced red tone can be achievedShown.
Rt 650 ≥0.37(Ct 650 )+C 1 ...(1c)
Rt 650 ≤-0.44(Ct 650 )+C 2 ...(2c)。
As described above, with u' =0.35 as the boundary, C of formula (1C) 1 116nm, C of the formula (2C) 2 116nm. In other words, when the condition is set so as to satisfy u'. Ltoreq.0.35, C is set as in the above-mentioned formulas (1 a) and (2 a) 1 ＝116nm、C 2 =116 nm. From the same point of view, when the conditions are set so as to satisfy u'. Ltoreq.0.314, C is set as in the above-mentioned formulae (1 b) and (2 b) 1 ＝121nm、C 2 =108 nm. To further reduce u' of the black display, C will be 1 Set large and C 2 The setting may be small.
C of formula (1C) 1 And may be any number above 116. C (C) 1 May be 116nm, 121nm, 124nm, 126nm, 128nm, 130nm, 132nm, 134nm, 136nm, 138nm, or 140nm. Similarly, C of formula (2C) 2 May be any number 116 or less. C (C) 2 May be 116nm, 112nm, 108nm, 105nm, 102nm, 100nm, 98nm, 96nm, 94nm, 92nm, or 90nm.
From the viewpoint of reducing chromaticity u' of black display upon visual confirmation from oblique directions, rt of the optical anisotropic assembly 50 at wavelength 650nm 650 The upper limit or the lower limit is not particularly limited as long as the above formula (1 c) or (2 c) is satisfied. However, as described below, if Rt for reducing the black luminance is considered 550 Range of (d) and retardation of optically anisotropic element 50, wavelength dispersion Rt 650 /Rt 550 Rt is then 650 The upper and lower limits of (2) are automatically determined.
(adjustment of brightness)
As described above, by delaying Ct according to the thickness direction of the color filter 650 Rt for adjusting optically anisotropic component 650 And the red light leakage is suppressed, so that u' of black display can be reduced. On the other hand, in order to reduce the amount of light leakage (black luminance) at the time of black display, it is preferable to change the amount of light leakage of green light having a high luminance functionThe optical design is performed in a small manner.
Fig. 13 is a graph plotting conditions under which the black luminance becomes a specific value, based on the simulation result of the O-mode liquid crystal panel 101 shown in fig. 1. The horizontal axis represents the thickness direction retardation Ct of 550nm wavelength of the green transmission region of the color filter 550 The longitudinal axis is the thickness direction retardation Rt of the optically anisotropic element with a wavelength of 550nm 550 . At each Ct 550 The black brightness in the directions of the azimuth angle of 45 degrees and the polar angle of 60 degrees is provided with the same Ct 550 And the points which become half of the liquid crystal display device without using the optically anisotropic element are indicated by black circle marks and black triangle marks. At Rt 550 In the case of being located between the blackened round marks and the blackened triangular marks, the black brightness upon visual confirmation from the oblique direction is reduced to half or less as compared with the case of not having the optically anisotropic component.
As is clear from fig. 13, both the upper limit side and the lower limit side of the boundary of the region having the black luminance of 1/2 can be approximated by straight lines, as compared with the case where the optically anisotropic element is not used. The straight line in the graph is represented by the following formula (3) and formula (4):
Rt 550 ＝0.97(Ct 550 )+73...(3)
Rt 550 ＝0.49(Ct 550 )+205...(4)。
therefore, the retardation Ct is set in the thickness direction of the green transmission region 22G of the color filter 22 at a wavelength of 550nm 550 Thickness direction retardation Rt with wavelength 550nm of optically anisotropic element 50 550 When the following formula (3 a) is satisfied, the black brightness in the oblique direction is 1/2 or less as compared with the case where the optically anisotropic element is not used.
0.97(Ct 550 )+73≤Rt 550 ≤0.49(Ct 550 )+205...(3a)。
The white circle mark and the white triangle mark of fig. 13 represent points where the black luminance becomes 1/5 of the black luminance of the liquid crystal display device without using the optically anisotropic element. At Rt 550 Between the whited circle mark and the whited triangle mark, and without optically anisotropic componentsIn contrast, the black brightness is reduced to less than 1/5.
The demarcation represented by the whited circle marks can be in a straight line parallel to the above formula (3): rt (Rt) 550 ＝0.97(Ct 550 ) +98 approximation. The demarcation represented by the white triangle mark can be in a straight line parallel to the above formula (4): rt (Rt) 550 ＝0.49(Ct 550 ) +180 approximation. Therefore, the retardation Ct in the thickness direction of the wavelength 550nm in the green transmission region of the color filter 550 Thickness-direction retardation Rt with wavelength 550nm of optically anisotropic member 550 When the following expression (3 b) is satisfied, the black brightness can be reduced to 1/5 or less, and display with high contrast can be realized, as compared with the case where an optically anisotropic element is not used.
0.97(Ct 550 )+98≤Rt 550 ≤0.49(Ct 550 )+180...(3b)。
From the above results, it is considered that in the liquid crystal panel of the O-mode shown in fig. 1, ct 550 And Rt 550 When the following expression (3 c) is satisfied, the influence of birefringence of the color filter can be eliminated, and display with reduced black luminance in the oblique direction can be realized.
0.97(Ct 550 )+C 3 ≤Rt 550 ≤0.49(Ct 550 )+C 4 ...(3c)
As described above, when the black luminance is 1/2 or less of the black luminance of the liquid crystal display device not using the optically anisotropic element, C is set as in the above formula (3 a) 3 ＝73nm、C 4 =205 nm. From the same point of view, when the black luminance is 1/5 or less of the black luminance of the liquid crystal display device not using the optically anisotropic element, the black luminance is C as in the above formula (3 b) 3 ＝98、C 4 And=180 nm. To further reduce the black brightness in the oblique direction, C is 3 Set large and C 4 The setting may be small. C of formula (3C) 3 Any number of 73 or more may be used. C (C) 3 May be 73nm, 88nm, 98nm, 108nm, 113nm, 118nm, 123nm, or 128nm. Similarly, C of formula (3C) 4 May be any number below 205. C (C) 4 Can be 205nm, 190nm, 180nm, 173nm, 168nm,163nm, 158nm, 153nm, or 148nm.
As shown in fig. 13, the thickness direction retardation Ct of the color filter 550 Larger Rt of optically anisotropic element for reducing black brightness upon visual confirmation from oblique direction 550 The greater the optimum value of (2). This can also be understood from the principle of optical compensation shown in fig. 8 a. Thickness direction retardation Ct of color filter 550 Large, this corresponds to P 'in A of FIG. 8' 0 And P C Is large (P) C Large south latitude). P (P) C The greater the south latitude from the equator, the greater the phase difference of the optically anisotropic element must be in order to move the light after passing through the optically anisotropic element 50 to the equator of the poincare sphere. Thus, as shown in FIG. 13, ct 550 The larger the amount, the more Rt must be required to reduce the black brightness 550 The larger.
(compromise of Black Brightness reduction and chromaticity)
In order to reduce the black brightness in visual confirmation from the oblique direction, the Ct is delayed according to the thickness direction of the color filter 550 Rt of the optically anisotropic element is set so as to satisfy the above formula (3 c) 550 And Rt of the optically anisotropic member is set so as to satisfy the above formula (1 c) or (2 c) 650 And (3) obtaining the product. However, rt 550 Rt (Rt) 650 Rt cannot be set individually 650 /Rt 550 Is a fixed value corresponding to the delayed wavelength dispersion of the optically anisotropic component.
For example, the retardation Ct in the thickness direction of the green transmission region of the color filter 550 In the case of 10nm, rt of the optically anisotropic component 550 When 130nm is used, the black brightness is small when visually confirmed from the oblique direction, and high contrast display can be realized. As set in the above simulation, the optically anisotropic element has Rt 650 /Rt 550 In the case of wavelength dispersion of=0.95, if Rt 550 =130 nm, then Rt 650 ＝124nm。
Since the red color filter and the green color filter are made of different materials, rth of the two are different, and Ct of the red color filter is the same 650 Is more than greenCt of color filter 550 Is the case for (a). For example, if the thickness direction retardation Ct of the red transmission region 22R of the color filter 22 650 At Rt of 30nm 650 When =124 nm, neither of the above formulas (1 a) and (1 b) is satisfied, and the chromaticity u' when visually confirmed from the oblique direction exceeds 0.35, and the black display is colored red and visually confirmed.
As is clear from the above examples, in the O-mode liquid crystal panel shown in fig. 1, even if the optical design of the optically anisotropic element is performed so that the black luminance is reduced, the chromaticity u' of the black display may be increased, and the black display may be colored red. On the other hand, the thickness direction retardation Ct of the color filter is considered 550 Ct is as follows 650 And retardation of optically anisotropic component, wavelength dispersion Rt 650 /Rt 550 To satisfy the above formula (3C) (here, C 3 73nm or more, C 4 205nm or less) and satisfies the above-described formula (1C) or (2C) (here, C 1 At least 116nm, C 2 116nm or less) to set the retardation in the thickness direction of the optically anisotropic element.
Further, the retardation film has a retardation in the thickness direction of the wavelength dispersion Rt 650 /Rt 550 Wavelength dispersion Re, typically delayed from the front 650 /Re 550 Approximately equal, in the range of 0.8 to 1.2. Considering the range of normal chromatic dispersion, the ratio of Ct is 650 When the particle diameter is 10nm or more, rt 550 Satisfies formula (3 c) and Rt 650 The case where the formula (2 c) is satisfied is less. Therefore, it is preferable to let Rt 550 Satisfies the above formula (3 c) and Rt 650 The retardation of the optically anisotropic element is set so as to satisfy the above formula (1 c).
Front retardation Re of optically anisotropic component 50 550 Re and Re 650 So as to Rt 550 Rt (Rt) 650 The above range may be set. As described above, the ratio nz=rt/Re of the thickness direction retardation Rt of the optically anisotropic member 50 to the front retardation Re is 0.2 to 0.8, and therefore, under this constraint, the thickness direction retardation Rt of the optically anisotropic member is determined 550 Rt (Rt) 650 Set by Nz coefficientFront retardation Re 550 Re and Re 650 。
Specifically, the front retardation Re of the optically anisotropic component 50 at a wavelength of 650nm 650 Preferably Rt 650 About 2 times as large as the above. Thus, re 650 Preferably, the following formula (1 d) or (2 d) is satisfied.
Re 650 ≥0.74(Ct 650 )+C 11 ...(1d)
Re 650 ≤-0.88(Ct 650 )+C 12 ...(2d)。
C 11 Is C 1 2 times, in particular C 11 Is 232nm or more. C (C) 11 May be 232nm, 236nm, 242nm, 248nm, 252nm, 256nm, 260nm, 264nm, 268nm, 272nm, 276nm, or 280nm. C (C) 12 Is C 2 2 times, in particular C 12 Is 232nm or less. C (C) 12 May be 232nm, 224nm, 216nm, 210nm, 204nm, 200nm, 196nm, 192nm, 188nm, 184nm, or 180nm. Considering the delayed wavelength dispersion of the optically anisotropic element, re of the optically anisotropic element 50 650 Preferably, the above formula (1 d) is satisfied.
Front retardation Re of optically anisotropic component 50 at wavelength 550nm 550 Preferably Rt 550 About 2 times as large as the above. Thus, re 550 Preferably, the following formula (3 d) is satisfied:
1.94(Ct 550 )+C 13 ≤Re 550 ≤0.98(Ct 550 )+C 14 ...(3d)。
C 13 is C 3 2 times, in particular C 13 Is 146nm or more. C (C) 13 May be 145nm, 175nm, 185nm, 215nm, 225nm, 235nm, 245nm, or 255nm. C (C) 14 Is C 4 2 times, in particular C 14 Is 410nm or less. C (C) 14 May be 410nm, 380nm, 360nm, 345nm, 335nm, 325nm, 315nm, 305nm, or 295nm.
< second embodiment: optical design of E-mode liquid crystal panel
Fig. 14 is a graph plotting conditions under which chromaticity of black display becomes a specific value, based on simulation results of the E-mode liquid crystal panel 102 shown in fig. 3. Similarly to fig. 12, a point where the chromaticity u 'of the black display in the direction of the azimuth angle 45 ° and the polar angle 60 ° becomes 0.35 is indicated by a black circle mark and a black triangle mark, and a point where the chromaticity u' of the black display becomes 0.314 is indicated by a white circle mark and a white triangle mark.
As in the case of fig. 12, the boundary of u' =0.35 in fig. 14 can be approximated by a straight line represented by the following formulas (6) and (7):
Rt 650 ＝0.37(Ct 650 )+116...(6)
Rt 650 ＝-0.44(Ct 650 )+120...(7)。
accordingly, in the liquid crystal panel 102, the retardation Ct in the thickness direction of the red transmission region 22R of the color filter 22 at a wavelength of 650nm 650 Thickness direction retardation Rt with wavelength 650nm of optically anisotropic element 50 650 When the following expression (6 a) or (7 a) is satisfied, u' is 0.35 or less, and black display with reduced red tone can be realized.
Rt 650 ≥0.37(Ct 650 )+116...(6a)
Rt 650 ≤-0.44(Ct 650 )+120...(7a)。
Equation (6) is the same as equation (1) for the O-mode liquid crystal panel 101. Equation (7) is represented by a straight line parallel to equation (2) for the O-mode liquid crystal panel 101. In fig. 14, for reference, a straight line of formula (2) is indicated by a broken line.
The boundary of u' =0.314, which is represented by a white circle mark, can be a straight line parallel to the above formula (6): rt (Rt) 650 ＝0.37(Ct 650 ) +121 approximation. The boundary of u' =0.314, represented by the white triangle mark, can be in a straight line parallel to the above formula (2): rt (Rt) 650 ＝-0.44(Ct 650 ) +108 approximation.
Therefore, the retardation Ct in the thickness direction of the red transmission region of the color filter at a wavelength of 650nm 650 Thickness direction retardation Rt with wavelength 650nm of optically anisotropic element 650 When the following expression (6 b) or (7 b) is satisfied, u' is 0.314 or less, and black display with a further reduced red tone can be realized.
Rt 650 ≥0.37(Ct 650 )+121...(6b)
Rt 650 ≤-0.44(Ct 650 )+108...(7b)。
From the above results, it can be considered that in the E-mode liquid crystal panel 102 shown in fig. 3, ct is 650 And Rt 650 When the following expression (6 c) or (7 c) is satisfied, a black display with reduced red tone can be realized.
Rt 650 ≥0.37(Ct 650 )+C 6 ...(6c)
Rt 650 ≤-0.44(Ct 650 )+C 7 ...(7c)。
When the conditions are set so as to satisfy u'. Ltoreq.0.35, C is set as in the above-mentioned formulae (6 a) and (7 a) 6 ＝116nm、C 7 When conditions are set so as to satisfy u'. Ltoreq.0.314, C may be set as in the above-described formulae (6 b) and (7 b) 6 ＝121nm、C 7 =108 nm. To further reduce u' of the black display, C will be 6 Set large and C 7 The setting may be small.
C of formula (6C) 6 And may be any number above 116. C (C) 6 Can be the same as the C 1 Equivalent numerical value, C 6 May be 116nm, 118nm, 121nm, 124nm, 126nm, 128nm, 130nm, 132nm, 134nm, 136nm, 138nm, or 140nm. Similarly, C of formula (7C) 7 May be any number of 120 or less. C (C) 7 Can be the same as the C 2 The equivalent value may be 121nm, 116nm, 112nm, 108nm, 105nm, 102nm, 100nm, 98nm, 96nm, 94nm, 92nm, or 90nm. Considering the retardation of the optically anisotropic element, rt of the optically anisotropic element 60 650 Preferably, the above formula (6 c) is satisfied.
From the viewpoint of reducing chromaticity u' of black display upon visual confirmation from oblique directions, rt of wavelength 650nm of optically anisotropic element 60 650 The upper limit or the lower limit is not particularly limited as long as the above formula (6 c) or (7 c) is satisfied. However, as described above with respect to the first embodiment, if Rt for reducing the black luminance is considered 550 Range of (c), and retardation of optically anisotropic member 60Wavelength dispersion Rt 650 /Rt 550 Rt is then 650 The upper and lower limits of (2) are automatically determined.
Fig. 15 is a graph plotting conditions under which the black luminance becomes a specific value, based on the simulation result of the E-mode liquid crystal panel 102 shown in fig. 3. As in fig. 13, the points where the black luminance in the azimuth angle 45 ° and the polar angle 60 ° is half of the liquid crystal display device without using the optical anisotropic element are indicated by the black circle marks and the black triangle marks, and the points where the black luminance is 1/5 of the liquid crystal display device without using the optical anisotropic element are indicated by the white circle marks and the white triangle marks.
In fig. 15, as in the case of fig. 13, the boundary between the areas having a black luminance of 1/2 can be approximated by a straight line, and the straight line in the graph is represented by the following formulas (8) and (9), as compared with the case where the optically anisotropic element is not used:
Rt 550 ＝0.69(Ct 550 )+70...(8)
Rt 550 ＝1.35(Ct 550 )+200...(9)。
accordingly, in the liquid crystal panel 102, the retardation Ct is set in the thickness direction of the green transmission region 22G of the color filter 22 at a wavelength of 550nm 550 Thickness direction retardation Rt with wavelength 550nm of optically anisotropic element 50 550 When the following formula (8 a) is satisfied, the black brightness is 1/2 or less as compared with the case where the optically anisotropic element is not used.
0.69(Ct 550 )+70≤Rt 550 ≤1.35(Ct 550 )+200...(8a)。
The points represented by the white triangle marks can be in a straight line parallel to the above formula (8): rt (Rt) 550 ＝0.69(Ct 550 ) +98 approximation. The points indicated by the white circle marks can be in a straight line parallel to the above formula (9): rt (Rt) 550 ＝1.35(Ct 550 ) +180 approximation. Thus, at Ct 550 And Rt 550 When the following formula (8 b) is satisfied, the black brightness is 1/5 or less as compared with the case where the optically anisotropic element is not used.
0.69(Ct 550 )+98≤Rt 550 ≤1.35(Ct 550 )+171...(8b)。
From the above results, it can be considered that in the E-mode liquid crystal panel 102 shown in fig. 3, ct is 550 And Rt 550 When the following expression (8 c) is satisfied, the influence of birefringence of the color filter can be eliminated, and display of a reduction in black luminance in visual confirmation from an oblique direction can be realized.
0.69(Ct 550 )+C 8 ≤Rt 550 ≤1.35(Ct 550 )+C 9 ...(8c)。
When the black brightness in the oblique direction is 1/2 or less of that when the optically anisotropic element is not used, C is set as in the above formula (8 a) 8 ＝70nm、C 9 And 200 nm. From the same point of view, when the black brightness in the oblique direction is 1/5 or less of that of the case where the optically anisotropic element is not used, C is set as in the above formula (8 b) 3 ＝98、C 4 =171 nm. To further reduce the black brightness in the oblique direction, C is 8 Set large and C 9 The setting may be small.
C of formula (8C) 8 Any number of 70 or more may be used. C (C) 8 May be 78nm, 88nm, 98nm, 108nm, 113nm, 118nm, 123nm, or 128nm. Similarly, C of formula (8C) 9 Any number below 200 is possible. C (C) 9 May be 200nm, 190nm, 180nm, 173nm, 168nm, 163nm, 158nm, 153nm, or 148nm.
As shown in fig. 15, the thickness direction retardation Ct of the color filter 550 Larger Rt of optically anisotropic element for reducing black brightness upon visual confirmation from oblique direction 550 The greater the optimum value of (2). This can also be understood from the principle of optical compensation shown in B of fig. 9.
In the E-mode liquid crystal panel 102 shown in fig. 3, in order to reduce the black luminance upon visual confirmation from the oblique direction, the retardation Ct is set according to the thickness direction of the color filter 550 Rt of the optically anisotropic element is set so as to satisfy the above formula (8 c) 550 And Rt of the optically anisotropic member is set so as to satisfy the above formula (6 c) or (7 c) 650 And (3) obtaining the product.
As described for the example of the liquid crystal panel of the O-mode, the wavelength dispersion Rt of the optically anisotropic element is considered 650 /Rt 550 Then at Ct 650 When the particle diameter is 10nm or more, rt 550 Satisfies formula (8 c) and Rt 650 The case where the formula (7 c) is satisfied is less. Therefore, it is preferable to let Rt 550 Satisfies the above formula (8 c) and Rt 650 The retardation of the optically anisotropic element 60 is set so as to satisfy the above formula (6 c).
Front retardation Re of optically anisotropic component 60 550 Re and Re 650 So as to Rt 550 Rt (Rt) 650 The above range may be set. Front retardation Re of optically anisotropic component 60 at wavelength 650nm 650 Preferably Rt 650 About 2 times as large as the above. Thus, re 650 Preferably, the following formula (6 d) or (7 d) is satisfied:
Re 650 ≥0.74(Ct 650 )+C 16 ...(6d)
Re 650 ≤-0.88(Ct 650 )+C 17 ...(7d)。
C 16 is C 6 2 times, in particular C 16 Is 232nm or more. C (C) 16 May be 232nm, 236nm, 242nm, 248nm, 252nm, 256nm, 260nm, 264nm, 268nm, 272nm, 276nm, or 280nm. C (C) 17 Is C 7 2 times, in particular C 17 Is 240nm or less. C (C) 12 May be 240nm, 232nm, 224nm, 216nm, 210nm, 204nm, 200nm, 196nm, 192nm, 188nm, 184nm, or 180nm. Considering the delayed wavelength dispersion of the optically anisotropic element, re of the optically anisotropic element 60 650 Preferably, the above formula (6 d) is satisfied.
Front retardation Re of optically anisotropic component 60 at wavelength 550nm 550 Preferably Rt 550 About 2 times as large as the above. Thus, re 550 Preferably, the following formula (8 d) is satisfied:
1.38(Ct 550 )+C 18 ≤Re 550 ≤2.70(Ct 550 )+C 19 ...(8d)。
C 18 is C 8 2 times, in particular C 18 Is 140nm or more。C 18 May be 155nm, 175nm, 185nm, 215nm, 225nm, 235nm, 245nm, or 255nm. C (C) 19 Is C 9 2 times, in particular C 19 Is 400nm or less. C (C) 19 May be 400nm, 380nm, 360nm, 345nm, 335nm, 325nm, 315nm, 305nm, or 295nm.
[ arrangement of optical Components ]
As described above, the liquid crystal panel 101 of the first embodiment is configured such that the optical anisotropic element 50 disposed on the visual confirmation side of the liquid crystal cell 20 corresponds to the thickness direction retardation Ct of the color filter 22 550 Ct is as follows 650 And is optically designed in such a way as to have specific optical characteristics. The liquid crystal panel 102 of the second embodiment is configured such that the optically anisotropic element 60 disposed on the light source side of the liquid crystal cell 20 corresponds to Ct 550 Ct is as follows 650 And is optically designed in such a way as to have specific optical characteristics.
The liquid crystal panel 101 of the first embodiment may include an optically isotropic film as a polarizer protective film between the visual inspection side polarizer 30 and the optically anisotropic element 50 or between the light source side polarizer 40 and the liquid crystal cell 20. The liquid crystal panel 102 of the second embodiment may include an optically isotropic film as a polarizer protective film between the visual inspection side polarizer 30 and the liquid crystal cell 20 or between the light source side polarizer 40 and the optically anisotropic element 60. The durability of the polarizer can be improved by providing a polarizer protective film on the surface of the polarizer.
The optically isotropic film used as the polarizer protective film is a film that does not substantially convert the polarized light state of light transmitted in either the normal direction or the oblique direction. Specifically, in the optically isotropic film, the front retardation Re is preferably 10nm or less, and the thickness retardation Rt is preferably 20nm or less. The front retardation of the optically isotropic film is more preferably 5nm or less. The retardation in the thickness direction of the optically isotropic film is more preferably 10nm or less, and still more preferably 5nm or less.
The liquid crystal panel may also include an optical layer or other members other than those described above. For example, it is preferable to provide a polarizer protective film on the outer surfaces (surfaces not facing the liquid crystal cell 20) of the polarizers 30, 40. The polarizer protective film provided on the outer surface of the polarizer may have optical isotropy or optical anisotropy. On the other hand, the polarizer protective film provided on the liquid crystal cell 20 side surface of the visual inspection side polarizer 30 and the liquid crystal cell 20 side surface of the light source side polarizer 40 is required to be optically isotropic as described above.
The liquid crystal panel 101 of the first embodiment preferably contains no optically anisotropic element other than the optically anisotropic element 50 between the visual inspection side polarizer and the liquid crystal cell 20, and preferably contains no optically anisotropic element between the light source side polarizer 40 and the liquid crystal cell 20. The liquid crystal panel 102 of the second embodiment preferably does not include an optically anisotropic element other than the optically anisotropic element 60 between the light source side polarizer and the liquid crystal cell 20, and preferably does not include an optically anisotropic element between the visual confirmation side polarizer 30 and the liquid crystal cell 20.
The liquid crystal cell is laminated with the optical members to form a liquid crystal panel. In the formation process, the respective members may be stacked on the liquid crystal cell individually in order, or a structure in which a plurality of members are stacked in advance may be used. The lamination order of these optical members is not particularly limited. The polarizing material and the optically anisotropic element may be laminated to form a laminated polarizing plate in advance, and the laminated polarizing plate may be bonded to the liquid crystal cell via an adhesive (not shown). As described above, a polarizer protective film may be provided on the surface of the polarizer. An optically isotropic film may be provided as a polarizer protective film between the polarizer and the optically anisotropic element.
In the lamination of the respective members, an adhesive or an adhesive may be preferably used. As the adhesive or pressure-sensitive adhesive, an adhesive or pressure-sensitive adhesive using an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyvinyl ether, a vinyl acetate/vinyl chloride polymer, a modified polyolefin, an epoxy polymer, a fluorine polymer, a rubber polymer, or the like as a base polymer can be appropriately selected.
[ liquid Crystal display device ]
The liquid crystal display device is formed by disposing the light source 110 on the second main surface side (polarizer 40 side) of the liquid crystal panel. A brightness enhancement film (not shown) may be provided between the liquid crystal panel and the light source. The brightness enhancement film may be integrally provided with the light source-side polarizing member. For example, a structure may be used in which a brightness enhancement film is bonded to the outer surface (light source side surface) of the second polarizer via an adhesive layer. In addition, a polarizer protective film may be provided between the polarizer and the brightness enhancing film.
Description of the reference numerals
10. Liquid crystal layer
11. Initial orientation direction
20. Liquid crystal cell
21. Color filter substrate
22 TFT substrate
30. 40 polarizer
35. 45 absorption axis (direction)
50. 60 optical anisotropic component (phase difference plate)
53. 63 slow phase shaft (direction)
101. 102 liquid crystal panel
110. Light source
201. 202 liquid crystal display device
Claims (4)
1. A liquid crystal panel is provided with:
a liquid crystal cell including a liquid crystal layer including liquid crystal molecules that are horizontally aligned in a non-electric field state, and a color filter disposed on a first main surface of the liquid crystal layer and having at least a green transmission region and a red transmission region;
a first polarizer disposed on a first main surface of the liquid crystal cell;
a second polarizer disposed on a second main surface of the liquid crystal cell; a kind of electronic device with high-pressure air-conditioning system
An optically anisotropic element disposed between the first and second polarizers,
the pretilt angle of the liquid crystal cell is 1 DEG or less,
the absorption axis direction of the first polarizer is orthogonal to the absorption axis direction of the second polarizer,
the slow axis direction of the optically anisotropic element is parallel to the absorption axis direction of the second polarizer,
For the optically anisotropic component, the front retardation Re at a wavelength of 650nm 650 Retardation Rt in the thickness direction 650 Ratio Rt of (1) 650 /Re 650 Is 0.4 to 0.6 percent,
for the green transmission region of the color filter, the thickness direction retardation Ct of 550nm 550 Is at most 50nm in length and has a specific wavelength,
for the red transmission region of the color filter, the thickness direction retardation Ct of the wavelength of 650nm 650 More than 0 and less than 50nm,
the alignment direction of the liquid crystal molecules of the liquid crystal cell in the no-electric-field state is orthogonal to the absorption axis direction of the second polarizer,
the optically anisotropic element is disposed between the liquid crystal cell and the second polarizer,
the thickness direction retardation Rt of the optically anisotropic component having a wavelength of 550nm 550 And the Ct is as follows 550 Satisfies the following formula (8 a):
0.69(Ct 550 )+70≤Rt 550 ≤1.35(Ct 550 )+200...(8a)
wherein said Rt 550 And the Ct is 550 Is expressed in units of nm and is used,
the Rt is 650 And the Ct is as follows 650 Satisfies the following formula (6 a) or (7 a):
Rt 650 ≥0.37(Ct 650 )+116...(6a)
Rt 650 ≤-0.44(Ct 650 )+120...(7a)
wherein said Rt 650 And the Ct is 650 In nm.
2. The liquid crystal panel of claim 1, wherein,
the Rt is 550 And the Ct is as follows 550 Satisfies the following formula (8 b):
0.69(Ct 550 )+98≤Rt 550 ≤1.35(Ct 550 )+171...(8b)。
3. the liquid crystal panel according to claim 1 or 2, wherein,
the Rt is 650 And the Ct is as follows 650 Satisfies the following formula (6 b) or (7 b):
Rt 650 ≥0.37(Ct 650 )+121...(6b)
Rt 650 ≤-0.44(Ct 650 )+108...(7b)。
4. a liquid crystal display device is provided with: the liquid crystal panel according to any one of claims 1 to 3, and a light source disposed on a second main surface side of the liquid crystal panel.
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| JP2018113193A JP7139161B2 (en) | 2018-06-13 | 2018-06-13 | Liquid crystal panel and liquid crystal display device |
| JP2018-113193 | 2018-06-13 | ||
| PCT/JP2019/019813 WO2019239794A1 (en) | 2018-06-13 | 2019-05-17 | Liquid crystal panel and liquid crystal display device |
| CN201980039432.4A CN112313570B (en) | 2018-06-13 | 2019-05-17 | Liquid crystal panel and liquid crystal display device |
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| TWI798019B (en) * | 2022-03-09 | 2023-04-01 | 友達光電股份有限公司 | Display device |
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| JP3165178B2 (en) | 1991-06-19 | 2001-05-14 | 日東電工株式会社 | Polarizing plate and liquid crystal display |
| JP2001258041A (en) | 2000-03-10 | 2001-09-21 | Sony Corp | Electron beam position detector and cathode-ray tube |
| JP2004004641A (en) | 2002-04-01 | 2004-01-08 | Nitto Denko Corp | Optical film and picture display device |
| JP4640929B2 (en) * | 2004-11-09 | 2011-03-02 | 日東電工株式会社 | Liquid crystal display device |
| JP4807774B2 (en) * | 2005-10-20 | 2011-11-02 | 日東電工株式会社 | Liquid crystal panel and liquid crystal display device |
| JP2007163894A (en) * | 2005-12-14 | 2007-06-28 | Fujifilm Corp | Liquid crystal display device |
| JP4726130B2 (en) * | 2006-02-08 | 2011-07-20 | 日東電工株式会社 | Liquid crystal display |
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| CN101361020B (en) * | 2006-05-16 | 2010-04-07 | 日东电工株式会社 | Liquid crystal panel and liquid crystal display device |
| JP2008040486A (en) * | 2006-07-11 | 2008-02-21 | Fujifilm Corp | Color filter, process of producing color filter, and liquid crystal display device |
| JP2008058612A (en) * | 2006-08-31 | 2008-03-13 | Sony Corp | Liquid crystal cell and liquid crystal display device |
| JP2009048157A (en) * | 2006-12-21 | 2009-03-05 | Fujifilm Corp | Liquid crystal display |
| JP5308063B2 (en) * | 2007-07-12 | 2013-10-09 | 日東電工株式会社 | Liquid crystal panel and liquid crystal display device |
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| JP2015143790A (en) * | 2014-01-31 | 2015-08-06 | 住友化学株式会社 | Optical anisotropic sheet for transfer |
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