CN114341684A - Retardation plate, and circularly polarizing plate, liquid crystal display device and organic EL display device each having the retardation plate - Google Patents
Retardation plate, and circularly polarizing plate, liquid crystal display device and organic EL display device each having the retardation plate Download PDFInfo
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3083—Birefringent or phase retarding elements
-
- 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
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- 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
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- 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
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
- G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/02—Details
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/80—Constructional details
- H10K59/8791—Arrangements for improving contrast, e.g. preventing reflection of ambient light
Abstract
The present invention provides a phase difference plate, comprising: a first optically anisotropic layer which is an optically anisotropic layer in which a rod-like liquid crystal compound is aligned with a thickness direction thereof being a helical axis and which has an in-plane phase difference value (Re) of substantially 1/2 wavelengths; and a second optically anisotropic layer, wherein the second optically anisotropic layer,an optically anisotropic layer in which a rod-like liquid crystal compound is aligned with a thickness direction thereof being a helical axis and which has an in-plane phase difference value (Re) of substantially 1/4 wavelengths; wherein a third optically anisotropic layer satisfying the following formula (1) is provided between the first and second optically anisotropic layers, and nx≒ny<nz(1) (in the formula, nxAnd nyRepresenting the refractive indices of orthogonal plate plane directions, nzIndicating the refractive index in the direction perpendicular to the plane direction of the plate).
Description
Technical Field
The present invention relates to a retardation plate useful for a liquid crystal display device and an organic EL display device, and a circularly polarizing plate, a liquid crystal display device, and an organic EL display device each having the retardation plate.
Background
A retardation plate for a circularly polarizing plate is used for a wide range of applications in flat panel displays.
Conventionally, in image display panels and the like, a method has been proposed in which a circularly polarizing plate is disposed on the surface of the image display panel, and reflection of external light is reduced by the circularly polarizing plate. The circularly polarizing plate is composed of a linearly polarizing plate and an 1/4 wavelength phase difference plate (hereinafter, also referred to as λ/4 plate), and converts the external light directed to the display surface of the image display panel into linearly polarized light by the linearly polarizing plate and then into circularly polarized light by the 1/4 wavelength phase difference plate. Here, although the external light beams resulting from the circularly polarized light are reflected on the surface of the image display panel, the direction of rotation of the circularly polarized light is reversed when the external light beams are reflected. As a result, the reflected light is converted into linearly polarized light in a direction opposite to the direction of arrival, which can be blocked by the 1/4 wavelength phase difference plate and the linear polarizing plate, and then blocked by the linear polarizing plate, thereby suppressing the reflected light from being exposed to the outside.
The retardation film used for the circularly polarizing plate has the following problems, for example, because of wavelength dependence (wavelength dispersion) of retardation: when the organic EL display device is used for preventing reflection, the device does not function as a λ/4 plate for each wavelength band in the visible light region, and coloring occurs in a dark state (black screen). The above-described problem becomes particularly noticeable when the display device is viewed with an oblique viewing angle. In order to prevent such a problem, a phase difference plate for a circularly polarizing plate is required which can function at a wavelength close to 1/4 in a wide wavelength band and can prevent reflection in a wide viewing angle. The retardation plate is a retardation plate that is uniaxially or biaxially stretched. In addition, a method of using 1 or more twist-aligned nematic liquid crystal layers (twisted nematic liquid crystal layers) is also disclosed.
[ Prior art documents ]
[ patent document ]
[ patent document 1] Japanese patent application laid-open No. 2014-209220
[ patent document 2] Japanese patent application laid-open No. 2014-224837.
Disclosure of Invention
[ problems to be solved by the invention ]
For example, a λ/4 plate obtained by biaxially stretching a modified Polycarbonate (PC) -based film is known as a wide-angle retardation plate. However, in this retardation film and a retardation film obtained by laminating a λ/4 film and the same λ/2 film as described later, the retardation film exhibits reverse wavelength dispersion with respect to the retardation value corresponding to the visible light wavelength region, but the effect of suppressing coloring when viewed from an oblique direction is not sufficient.
Further, there is a wide-angle phase difference plate obtained by laminating a λ/4 plate obtained by uniaxially stretching a Cycloolefin (COP) film and the same λ/2 plate. However, this laminated retardation plate has a problem in productivity because it is necessary to cut each retardation plate at a predetermined optical axis angle with respect to the optical axis of the polarizing plate and then laminate the retardation plates one by one using an adhesive layer or the like.
In order to improve the display property viewed from an oblique direction, it is generally known to add a positive C plate layer having a retardation value in the thickness direction within a predetermined range. For example, patent document 2 attempts to improve the display property viewed from an oblique direction by adding a front C plate layer to the material of the λ/2 plate and the λ/4 plate.
As described above, there has been conventionally known a circular polarizing plate which has a wide-band λ/4 wavelength retardation plate in which only "a structure using a nematic liquid crystal layer having a λ/2 plate function and a λ/4 plate function and a" stretched film "are combined and which further has a front C plate layer, but the circular polarizing plate has not been able to satisfy black color reproducibility (a strong and weak degree of black brightness) of a display device when viewed from an oblique direction and display properties related to coloring, and further improvement has been required. In addition, regarding the positive C plate layer, no discussion has been made regarding the thickness direction retardation value (Rth) and the most preferable arrangement relationship with the retardation plate.
An object of the present invention is to provide a wide-band phase difference plate for a circularly polarizing plate that reduces black luminance (exhibits good black) in a black screen when viewed obliquely, a circularly polarizing plate having the phase difference plate, and a liquid crystal display device and an organic EL display device each including the circularly polarizing plate.
[ means for solving problems ]
The present inventors have studied in detail to solve the above problems. As a result, by using a front C plate layer between 2 liquid crystal layers having a twisted alignment in the thickness direction, the black luminance in the black screen when viewed from an oblique direction was successfully reduced.
That is, the present invention relates to the following inventions, but is not limited to these.
[ invention 1]
A phase difference plate is provided with:
a first optically anisotropic layer which is an optically anisotropic layer in which a rod-like liquid crystal compound is aligned with a thickness direction thereof being a helical axis and which has an in-plane phase difference value (Re) of 1/2 wavelength substantially; and
a second optically anisotropic layer which is an optically anisotropic layer in which a rod-like liquid crystal compound is aligned with a thickness direction thereof being a helical axis and which has an in-plane phase difference value (Re) of 1/4 wavelength; wherein the content of the first and second substances,
a third optically anisotropic layer satisfying the following formula (1) is provided between the first and second optically anisotropic layers,
nx≒ny<nz (1)
(in the formula, nxAnd nyRepresenting the refractive indices of orthogonal plate plane directions, nzIndicating the refractive index in the direction perpendicular to the plate plane direction).
[ invention 2]
The phase difference plate according to invention 1, wherein the twist angle of the first optically anisotropic layer is substantially 26 ° or substantially-26 °, and the twist angle of the second optically anisotropic layer is substantially 78 ° or substantially-78 ° from the twist angle of the first optically anisotropic layer.
[ invention 3]
The phase difference plate according to invention 2, wherein the aforementioned third optically anisotropic layer is a layer having a homeotropically aligned liquid crystal compound, and the thickness direction phase difference value (Rth) is-150 to-80 nm.
[ invention 4]
A circularly polarizing plate comprising a polarizing element and the phase difference plate according to any one of inventions 1 to 3.
[ invention 5]
The circularly polarizing plate according to invention 4, wherein the polarizing element comprises a dichroic azo dye having an achromatic color (achromatic color).
[ invention 6]
An organic EL display device comprising the circularly polarizing plate according to invention 4 or 5.
[ invention 7]
A liquid crystal display device comprising the circularly polarizing plate according to invention 4 or 5.
[ Effect of the invention ]
The present application can provide a wide-band phase difference plate for a circularly polarizing plate that reduces black luminance and/or reduces coloring in a black screen when viewed obliquely, a circularly polarizing plate having the phase difference plate, and a Liquid Crystal Display (LCD) and an organic Electroluminescence (EL) display (organic light emitting diode (OLED) display) each including the circularly polarizing plate. In one aspect, a display device that displays good black in a black screen when viewed from the front can be provided. In one aspect, the present application may provide a thin phase difference plate. In one aspect, the present application achieves lower brightness and minimally colored black in the black screen of LCD and OLED display devices, not only in the head-on (front) direction, but also in a wide range of viewing angles. In one aspect, the present application can provide a method of manufacturing a circular polarizing plate by roll-to-roll lamination without requiring complicated steps such as lamination one by one or oblique stretching.
Drawings
Fig. 1 is a sectional view of a phase difference plate according to an embodiment of the present invention.
Fig. 2 is a cross-sectional view of a circular polarizing plate according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating "example 1" according to the present invention.
Fig. 4 is a contour diagram of luminance corresponding to polar angles of 0 ° to 80 ° and azimuth angles of 0 ° to 360 ° of example 1.
Fig. 5 is a contour diagram of luminance corresponding to polar angles of 0 ° to 80 ° and azimuth angles of 0 ° to 360 ° of example 2.
Fig. 6 is a contour diagram of the luminance corresponding to the polar angle 0 ° to 80 ° and the azimuth angle 0 ° to 360 ° of example 3.
Fig. 7 is a contour diagram of luminance corresponding to polar angles of 0 ° to 80 ° and azimuth angles of 0 ° to 360 ° of comparative example 1.
Fig. 8 is a contour diagram of luminance corresponding to polar angles of 0 ° to 80 ° and azimuth angles of 0 ° to 360 ° of comparative example 2.
Fig. 9 is a contour diagram of luminance corresponding to polar angles 0 ° to 80 ° and azimuth angles 0 ° to 360 ° of comparative example 3.
Fig. 10 is a contour diagram of luminance corresponding to polar angles 0 ° to 80 ° and azimuth angles 0 ° to 360 ° of comparative example 4.
Fig. 11 is a contour diagram of luminance corresponding to polar angles 0 ° to 80 ° and azimuth angles 0 ° to 360 ° of comparative example 5.
Fig. 12 is a contour diagram of luminance corresponding to polar angles of 0 ° to 80 ° and azimuth angles of 0 ° to 360 ° of comparative example 6.
Fig. 13 shows experimental results of the circular polarizing plates of examples 1 to 3 in a polar angle (tilt angle) of 40 ° and an azimuth angle of 0 to 360 ° (in units of 45 °).
Fig. 14 shows experimental results of the circular polarizing plates of examples 1 to 3, which were implemented at a polar angle (tilt angle) of 50 ° and an azimuth angle of 0 to 360 ° (in units of 45 °).
Fig. 15 shows the experimental results of the circular polarizing plates of examples 1 to 3 in a polar angle (tilt angle) of 60 °, an azimuth angle of 0 to 360 ° (in units of 45 °).
Fig. 16 shows the results of experiments on the circular polarizing plates of example 1 and comparative examples 1 to 3 at a polar angle (tilt angle) of 40 ° and an azimuth angle of 0 to 360 ° (in units of 45 °).
Fig. 17 shows experimental results of the circular polarizing plates of example 1 and comparative examples 1 to 3 in a polar angle (tilt angle) of 50 ° and an azimuth angle of 0 to 360 ° (in units of 45 °).
Fig. 18 shows the results of experiments on the circular polarizing plates of example 1 and comparative examples 1 to 3 at a polar angle (tilt angle) of 60 ° and an azimuth angle of 0 to 360 ° (in units of 45 °).
Fig. 19 shows the results of experiments on the circular polarizing plates of example 1 and comparative examples 4 to 6 in the polar angle (tilt angle) of 40 ° and the azimuth angle of 0 to 360 ° (in units of 45 °).
Fig. 20 shows the results of experiments on the circular polarizing plates of example 1 and comparative examples 4 to 6 in a polar angle (tilt angle) of 50 ° and an azimuth angle of 0 to 360 ° (in units of 45 °).
Fig. 21 shows experimental results of the circular polarizing plates of example 1 and comparative examples 4 to 6 in a polar angle (tilt angle) of 60 ° and an azimuth angle of 0 to 360 ° (in units of 45 °).
Detailed Description
The following describes embodiments of the present invention.
(phase difference plate)
A retardation plate (wavelength plate) is an optical element that imparts a predetermined phase difference to incident linearly polarized light. The retardation plate of the present invention includes two optically anisotropic layers (first and second optically anisotropic layers) as a λ/2 plate and a λ/4 plate, respectively, and further includes a third optically anisotropic layer between the first and second optically anisotropic layers for suppressing coloring when viewed from an oblique direction. The phase difference plate is suitable for a circular polarizing plate, and is particularly suitable for a broadband circular polarizing plate. The method for producing the retardation plate of the present invention is not particularly limited, and the retardation plate can be produced by a known method such as roll-to-roll (roll-to-roll).
The wide band is generally a retardation plate that gives a substantially constant retardation at all wavelengths in the visible light region (380nm to 780nm) when linearly polarized light is incident. Therefore, the retardation plate used for producing the circularly polarizing plate provides a retardation close to 1/4 in all wavelengths in the visible light region.
(first and second optically anisotropic layers)
The first optically anisotropic layer of the present invention has an in-plane retardation value (Re) of 1/2 wavelength and functions as a λ/2 plate. The Re of the retardation plate of the present invention may not be completely 1/2 nm as long as it is applied to a circularly polarizing plate. For example, numerical ranges of ± 20%, 15%, 10%, 5%, 2%, or 1% are included.
The second optically anisotropic layer of the present invention has an in-plane retardation value (Re) of substantially 1/4 wavelengths, and functions as a λ/4 plate. The term "substantially" is used in the same way as described above.
The liquid crystal compounds forming the first and second optically anisotropic layers are generally roughly classified into rod-like (rod-like liquid crystal compounds) and disk-like (discotic liquid crystal compounds) by their shapes. The present invention preferably uses a rod-like liquid crystal compound to form a Twisted Nematic (TN) liquid crystal layer. TN liquid crystal layers are nematic liquid crystals in which rod-like and long-sized molecules are aligned in a substantially constant direction, and the nematic liquid crystals are continuously changed into a helical liquid crystal layer in which the molecular direction is twisted due to chirality (chirality).
The TN liquid crystal layer is preferably a layer formed by fixing a rod-like liquid crystal compound having a polymerizable group or the like by polymerization or the like, and in this case, it is not necessary to exhibit liquid crystallinity after forming a layer. The type of the polymerizable group contained in the rod-like liquid crystal compound is not particularly limited, and is preferably a functional group capable of addition polymerization, and is preferably a polymerizable ethylenically unsaturated group or a cyclopolymerizable group. More specifically, preferred examples thereof include (meth) acryloyl group, vinyl group, styryl group, and allyl group, and more preferred is (meth) acryloyl group. In the present invention, a well-known TN liquid crystal material may be used. In addition, when a TN liquid crystal layer is formed, a desired chiral agent may be used together with the liquid crystal compound as needed. The chiral agent is added to twist align the liquid crystal compound.
In addition, by using a polymerizable liquid crystal material as described above for the retardation plate, the thickness can be reduced to 5 μm to 20 μm as compared with a film-shaped retardation plate having a film thickness of 50 μm to 100 μm in general.
The first and second optically anisotropic layers in the retardation plate of the present invention are twisted and aligned with the thickness direction as a spiral axis. In addition, the twist directions of the two liquid crystal layers are the same. In addition, the in-plane slow axis on the third optically-anisotropic layer side of the first optically-anisotropic layer is parallel to the in-plane slow axis on the third optically-anisotropic layer side of the second optically-anisotropic layer. That is, the twist angle of the second optically anisotropic layer is arranged with respect to the twist angle of the first optically anisotropic layer. The plus and minus (minus) of the twist angle indicates a direction of counterclockwise rotation from the absorption axis and a direction of clockwise rotation from the absorption axis, respectively, when the absorption axis direction of the polarizer is set to 0 ° and the polarizer of the circularly polarizing plate is the viewing side.
In one aspect, the twist angle of the first optically anisotropic layer used in the retardation plate of the present invention is substantially 26 °. More specifically, it is preferably 26 ± 10 °, more preferably 26 ± 7 °, and still more preferably 26 ± 5 °. In this case, the twist angle of the second optically anisotropic layer is substantially 78 °. More specifically, it is preferably 78 ± 10 °, more preferably 78 ± 7 °, and still more preferably 78 ± 5 °. Or the twist angle of the first optically anisotropic layer is substantially-26 deg. in another aspect. More specifically, it is preferably-26. + -. 10 °, more preferably-26. + -. 7 °, still more preferably-26. + -. 5 °. In this case, the twist angle of the second optically anisotropic layer is substantially-78 °. More specifically, it is preferably-78. + -. 10 °, more preferably-78. + -. 7 °, still more preferably-78. + -. 5 °. The above-described twist angle can be measured using a film inspection apparatus (RETS-1100A, manufactured by tsukamur electronic corporation).
In the first optically anisotropic layer used in the retardation plate of the present invention, the product (Δ n1 · d1) of the refractive index anisotropy Δ n1 at a wavelength of 550nm and the thickness d1 of the liquid crystal layer, that is, the surface-bond retardation value (Re), is substantially 275nm, and more specifically, the product (Δ n1 · d1) is preferably 275 ± 30nm, more preferably 275 ± 20nm, and still more preferably 275 ± 10 nm.
In the second optically anisotropic layer used in the retardation plate of the present invention, the product (Δ n2 · d2) of the refractive index anisotropy Δ n2 at a wavelength of 550nm and the thickness d2 of the liquid crystal layer, that is, the surface-bond retardation value (Re), is substantially 137.5nm, and more specifically, the product (Δ n2 · d2) is preferably 137.5 ± 15nm, more preferably 137.5 ± 10nm, and still more preferably 137.5 ± 5 nm. The Δ n1 · d1 and Δ n2 · d2 may be measured using a film inspection apparatus (RETS-1100A, manufactured by tsukamur electronic corporation).
(third optically anisotropic layer)
The third optically anisotropic layer provided in the retardation plate of the present invention is one type of retardation plate called a positive C plate, and is a retardation plate described below: when xy orthogonal axis is set on the plate plane and z axis is set in the direction perpendicular to the plate plane, refractive index n in each axis directionx、ny、nzIs nx≒ny<nz. In addition, "n" isx≒ny"denotes nxAnd nySubstantially equal, including completely equal. The aforementioned "nxAnd nySubstantially equal "", n is n as long as it functions as a positive C platexAnd nyMay also be different, for example, one may also see another with a difference of 20%, 15%, 10%, 5%, 2%, or 1%. In addition, the following symbol may be used instead of "≈ z".
[ number 1]
In the present invention, a well-known positive C plate may be used. In one aspect, the third optically anisotropic layer provided in the retardation plate of the present invention is, for example, a liquid crystal layer in which a rod-like liquid crystal compound is vertically aligned with respect to the thickness direction (plate plane). The foregoing homeotropic, direction including the alignment angle of the liquid crystal compound is 90 ° and almost 90 ° (including the difference in the degree to which it affects invisibility, for example, a difference within ± 10 °, ± 5 °, ± 3 °, or ± 1 °) with respect to the plane of the plate. The third optically anisotropic layer is preferably a layer formed by fixing a rod-like liquid crystal compound having a polymerizable group or the like by polymerization or the like, and in this case, it is not necessary to exhibit liquid crystallinity after forming a layer. The type of the polymerizable group contained in the rod-like liquid crystal compound is not particularly limited, and is preferably a functional group capable of addition polymerization, and is preferably a polymerizable ethylenically unsaturated group or a cyclopolymerizable group. More specifically, preferred examples thereof include: (meth) acryloyl, vinyl, styryl, allyl, and the like, and more preferably (meth) acryloyl.
The adjustment of the thickness direction retardation (Rth) of the liquid crystal layer can be performed by adjusting the film thickness. The film thickness is not particularly limited, but may be set in the range of 0.1 μm to 3 μm, and more preferably 0.5 μm to 2 μm.
In another aspect, the cellulose-based resin material disclosed in Japanese patent laid-open publication No. 2016-108536 can be used. From the viewpoint of thinning and productivity, the liquid crystal compound described above is preferably used.
The thickness direction phase difference (Rth) of the third optically anisotropic layer of the present invention is determined according to Poincare sphere (Poincare sphere) theory. In order to minimize the locus of movement from the coordinate on the equator of linearly polarized light on the Poincare sphere to the coordinate on the north pole or the south pole of circularly polarized light, a range of the most preferable value is preferably set, specifically, a range of-150 to-80 nm is preferable, a range of-132 to-112 nm is more preferable, and a range of-126 to-120 nm is even more preferable. The third optically anisotropic layer is preferably disposed between the first optically anisotropic layer and the second optically anisotropic layer. Accordingly, the circularly polarized light of each wavelength generated by the phase difference plate of the present invention is concentrated on the coordinates representing the circularly polarized light on the north pole or the south pole of the poincare sphere, and the circularly polarized light close to the ideal one in each wavelength is formed. Therefore, in a display device or the like to which the circularly polarizing plate of the present invention is attached, coloring when viewed from an oblique direction can be suppressed.
(alignment treatment)
The first and second optically anisotropic layers of the present invention are subjected to a treatment for aligning the liquid crystal compound on the substrate or are provided with an alignment film. The liquid crystal alignment is not particularly limited as long as the alignment direction of the optically anisotropic layer is appropriately defined and does not prevent the present invention from exhibiting the intended performance, and alignment techniques well known in the art may be used. The substrate surface can be physically made anisotropic by using a rubbing roll (rubbing roll) which is rotated in a direction of about 0 to 50 ° with respect to the transport direction of the substrate, the above-mentioned rubbing treatment can be performed on a resin layer provided on the substrate as disclosed in japanese patent application laid-open No. 2003-014935, or a photo-alignment film in which an alignment film having anisotropy due to linearly polarized ultraviolet rays is formed on a polymer film.
(polarizing element)
The polarizing element (which may be referred to as a polarizer or a polarizing film) used for obtaining the circularly polarizing plate, the liquid crystal display device, and the organic EL display device of the present invention is not particularly limited, and a known polarizing element may be appropriately selected and used according to the application. Examples thereof include: a polarizing element obtained by uniaxially stretching a polyvinyl alcohol (PVA) -based film impregnated with a water-soluble dichromatic dye and/or a dichromatic dye such as polyiodide in a boric acid warm water bath, a polarizing element obtained by uniaxially stretching a polyvinyl alcohol film and then forming a polyene structure by a dehydration reaction, a polarizing element obtained by applying a solution containing a dichromatic dye to a base film to orient the dichromatic dye, a base polarizing integrated element obtained by providing a polyvinyl alcohol layer on a protective film, uniaxially stretching the polyvinyl alcohol layer together with the base film, and then impregnating the dichromatic dye, and the like. From the viewpoint of processability and optical characteristics, a polarizing element obtained by uniaxially stretching a PVA film and adsorbing and aligning a dichroic dye is typically preferably used. Examples of commercially available PVA films include: VF-PS (thickness: 75 μm) manufactured by Kuraray, in this case, a polarizing element is generally obtained by subjecting a dichromatic dye to adsorption alignment and then uniaxially stretching to a thickness of 25 μm to 35 μm.
The dichromatic dye is preferably an iodide ion or dichromatic dye, and both can be used to obtain the polarizing element for use in the present invention. Examples of the dichromatic dye include: azo dyes, anthraquinone dyes, tetrazine dyes, and the like are preferably used by blending 2 to 3 or more azo dyes from the viewpoint of hue design and durability against heat. In addition, in the case of using any dichroic dye, the optical characteristics of the polarizing element are preferably high in transmittance and high in polarization degree (also referred to as high dichroism) from the viewpoint of obtaining antireflection ability and excellent black screen property in a mounted display device, and more specifically, the visibility correction monomer transmittance (Ys) is preferably 40% to 45%, and the visibility correction polarization degree (Py) is preferably 99% or more.
In one aspect of the present invention, it is preferable to have an achromatic hue, that is, it is preferable that the monomer transmittance (Ts) of the polarizing element is almost uniform over the entire visible light region (wavelength 400nm to 700nm, more preferably 380nm to 780 nm). In the L a b color system, the absolute values of a and b are all 1 or less when measured with a single polarizing element, and when measured with 2 polarizing elements stacked so that the directions of the absorption axes are orthogonal to each other, the hue in which the absolute value of a is 4 or less and the absolute value of b is 8 or less is more preferable as a specific aspect of the achromatic color. Accordingly, for example, by using the circularly polarizing plate having a broadened band of the retardation plate of the present invention, not only the coloring of the reflected light from the display device but also the coloring of the reflected light from the surface of the polarizer can be suppressed in the entire visible light region.
Examples of the azo dye having dichroism include: c.i. directylower 12, c.i. directylower 28, c.i. directylower 44, c.i. directylower 142, c.i. directornge 26, c.i. directornge 39, c.i. directornge 71, c.i. directornge 107, c.i. directreeded 2, c.i. directreeded 31, c.i. directreeded 79, c.i. directreded 81, c.i. direcdreeded 117, c.i. directreded 247, c.i. directgreen80, c.i. directgreen59, c.i. directblue71, c.i. directylue 78, c.i.i. directyi 168, c.i.directytul 202, c.i. directyi 106, c.i.i.i. directorgetrule 106, c.i.i.i. directorgetriebe 106, c.i.i.i.i.i.i. directorgetriebe 106, c.i.i.i.i.i.i.i. Other dyes which can be produced by known methods may also be used, and as known methods, for example: the method described in Japanese patent laid-open No. 3-12606, the method described in Japanese patent laid-open No. 59-145255, and the like. Further, commercially available dyes include: kayafect Violet P Liquid, Kayafect Yellow Y, Kayafect Orange G, Kayafect Blue KW, and Kayafect Blue Liquid 400 (both manufactured by Nippon chemical Co., Ltd.), and the like. These azo dyes are used by blending 2 to 3 or more kinds so that the respective transmittances in the visible light region become uniform. In the polarizing element of the present invention, in order to obtain an achromatic polarizing element having high transmittance and high polarization degree, an azo dye having improved dichroism for designing an achromatic polarizing element, as disclosed in international publication nos. WO2017/146212 and WO2019/117131, is preferably used.
The polarizing element preferably includes a substrate (also referred to as a support or a support film) for protecting the polarizing element. The base material may be disposed on only one side of the polarizer, or may be disposed on both sides of the polarizer so that 2 sheets of the same or different base materials sandwich the polarizer. The polarizing element having a substrate is called a polarizing plate. In the case where the polarizing element includes a substrate described later, the in-plane retardation value (Re) and the thickness direction retardation value (Rth) of the substrate disposed between the polarizing element and the display device are preferably 0 or almost 0 (the numerical value is not affected by them, and the range of-5 nm to 5nm, for example).
(substrate)
The retardation plate and the circularly polarizing plate of the present invention (hereinafter also referred to as the article of the present invention) may further include a substrate. The substrate is not particularly limited as long as it has desired mechanical strength, thermal stability, and the like and does not interfere with the performance of the present invention, and a substrate well known in the art can be used. The thickness of the substrate can be suitably designed, and is preferably 50 to 200. mu.m, more preferably 10 to 100. mu.m, still more preferably 20 to 80 μm.
In addition, in the case where a substrate is disposed between the polarizing element and the display device, the in-plane retardation value (Re) and the thickness direction retardation value (Rth) of the substrate are preferably 0 or almost 0. As commercially available substrates having the above phase difference value, for example: triacetyl cellulose resin Film Z-TAC (Fuji Film Co., Ltd.), acrylic resin Film OXIS series (Dacron Industrial Co., Ltd.), and the like.
(adhesive and/or bonding agent)
In the article of the present invention, a laminate may be formed by providing a next layer on one layer, or a laminate may be formed by laminating a plurality of layers with an adhesive (also referred to as a pressure sensitive adhesive) and/or an adhesive. The adhesive or bonding agent well known in the art may be used without particular limitation as long as it can function as an adhesive or bonding agent and does not prevent the intended performance of the present invention. As the binder, representatively, there can be mentioned: an acrylic resin. The thickness may be suitably designed, but is preferably 1 to 50 μm, and more preferably 5 to 25 μm from the viewpoint of interlayer adhesiveness and processability in adhesive application and lamination. Examples of the binder include: an aqueous adhesive containing a PVA-based resin as a main component, an adhesive containing a thermosetting or photocurable resin, a method of bonding by plasma, and the like.
The values of the phase difference value and the twist angle of the optically anisotropic layer of the present invention are values that can obtain an optically excellent effect. These values are not particularly limited as long as the alignment properties and the product processability of the actual liquid crystal compound are taken into consideration, and may include a tolerance or a margin (margin).
(circular polarizing plate)
The circular polarizing plate of the present invention is a broadband circular polarizing plate, and includes a polarizing element and the retardation plate of the present invention, and more specifically, includes a polarizing element (or polarizing plate), a first optically anisotropic layer, a third optically anisotropic layer, and a second optically anisotropic layer in this order. In one aspect, each optical axis of the circularly polarizing plate has an absorption axis of the polarizer in a 0 ° direction, and the twist angle of the first optically anisotropic layer is substantially 26 ° with respect to the absorption axis of the polarizer, and the twist angle of the second optically anisotropic layer is substantially 78 ° from the twist angle of the first optically anisotropic layer (that is, 104 ° with respect to the absorption axis of the polarizer).
The method for producing the circularly polarizing plate of the present invention is not particularly limited, and for example, the films or sheets of the respective layers may be laminated one by one, or the respective layers produced in a roll shape may be continuously laminated by roll-to-roll. In particular, the circularly polarizing plate of the present invention can be easily laminated in a roll-to-roll manner without cutting the retardation plate at a predetermined optical axis angle. Therefore, productivity can be improved compared to a conventional method for manufacturing a wide-band circularly polarizing plate in which a uniaxial extended film such as a COP film is laminated.
(method for manufacturing circular polarizing plate)
The methods for producing the retardation plate and the circularly polarizing plate of the present invention are described below by way of examples 1 to 2, but are not limited thereto. The optically anisotropic layers are formed on a substrate on which the cured liquid crystal layer and the substrate can be peeled off, and in the step of sequentially laminating described later, the substrates may be removed to form a circular polarizing plate.
(example of aspect 1)
As the 1 st step, a coating composition comprising a liquid crystal compound exhibiting a polymerizable nematic liquid crystal phase, a chiral agent, a photopolymerization initiator and a diluting solvent is applied onto a rubbing surface of a substrate subjected to rubbing treatment in the 0 ° direction (transport direction), followed by drying step to remove the solvent and irradiation to harden the coating film, thereby obtaining a first optically anisotropic layer having an alignment axis in the 0 ° direction, a twist angle of 26 ° and a retardation value (Re @ 550nm) of 275 nm.
As the 2 nd step, a coating composition containing a composition comprising a liquid crystal compound exhibiting a polymerizable nematic liquid crystal phase, a photopolymerization initiator and a diluting solvent is applied to a substrate, and then a drying step is obtained to remove the solvent and irradiate light to harden the coating film, thereby obtaining a third optically anisotropic layer aligned in a direction perpendicular to the substrate.
In the 3 rd step, a coating composition comprising a TN liquid crystal material, a chiral reagent, a photopolymerization initiator and a diluting solvent was coated on a rubbing surface of a substrate subjected to rubbing treatment in a direction of 26 ° with respect to the conveying direction, followed by drying step to remove the solvent and irradiating to harden the coating film, thereby obtaining a second optical anisotropic layer having an alignment axis in the direction of 26 °, a twist angle of 78 ° and a phase difference value (Re @ 550nm) of 137.5 nm.
As the 4 th step, a polarizing element (or a polarizing plate), a first optically anisotropic layer, a third optically anisotropic layer, and a second optically anisotropic layer are sequentially laminated so as to have the optical axis relationship shown in fig. 3, thereby obtaining a circular polarizing plate of the present invention.
(example of aspect 2)
In the 2 nd step, a coating composition containing a composition comprising a liquid crystal compound exhibiting a polymerizable nematic liquid crystal phase, a photopolymerization initiator and a diluting solvent is applied to the liquid crystal surface of the first optically anisotropic layer obtained in the 1 st step, and then the coating film is cured by irradiation with light after the solvent is removed through a drying step, thereby obtaining a third optically anisotropic layer aligned in a direction perpendicular to the liquid crystal surface. The present invention is similar to the example of the first aspect except that a polarizing element (or a polarizing plate), a first optically anisotropic layer and a second optically anisotropic layer in which a third optically anisotropic layer is laminated are sequentially laminated so as to have the optical axis relationship shown in fig. 3, thereby obtaining a circular polarizing plate of the present invention.
(display device)
The circularly polarizing plate of the present invention is preferably applied to the viewing side of various display devices such as a Liquid Crystal Display (LCD) and an organic Electroluminescence (EL) display device (organic light emitting diode (OLED) display device). The display device may be designed to include a touch screen, an anti-glare layer or an anti-reflection layer, a light-transmitting cover (also referred to as a front panel), and the like. The light-transmitting cover plate may have a planar shape or a curved shape. The method for manufacturing the display device of the present invention is not particularly limited, and the display device can be manufactured by a known method.
The liquid crystal display device of the present invention may be a so-called transmissive or transflective liquid crystal display device including a liquid crystal panel and a backlight unit, or a so-called reflective liquid crystal display device including a liquid crystal panel and a reflective layer.
In general, since the organic EL display device includes a metal electrode in the display panel portion, the OLED (organic EL display device) itself has a higher reflectance than the liquid crystal panel. This is a cause of deterioration in display performance due to reflection of external light from the electrode when used in an environment with a large amount of external light, such as daytime and outdoors. Therefore, in order to suppress reflection of external light, a circularly polarizing plate is generally attached to the viewing side of the organic EL display device. Therefore, the display characteristics of the organic EL display device also depend on the optical characteristics of the circularly polarizing plate. The circularly polarizing plate of the present invention has wider viewing angle characteristics than conventional circularly polarizing plates, and therefore, is preferably used for an organic EL display device requiring a wide viewing angle.
The embodiments of the present invention have been described so far, but the present invention is not limited to the above embodiments, and various changes and modifications can be made according to the technical idea of the present invention.
[ examples ]
The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
Assuming that a circular polarizing plate is attached to an ideal reflection plate, black luminance (normalized value in units) in the following azimuth and inclination angles (polar angles) is calculated using a liquid crystal simulation software LCD master (manufactured by SYMTEC corporation). The configuration and calculation conditions of the circularly polarizing plate are as follows. Table 1 shows a list of the following calculation conditions and the arrangement relationship of the optically anisotropic layers. The in-plane retardation value (Re) and the thickness direction retardation value (Rth) are values at a wavelength of 550 nm. The optically anisotropic layers arranged in table 1 are shown in the columns of the 1 st layer, the 2 nd layer, and the 3 rd layer in this order from the incident light side.
Structure of circular polarizing plate:
example 1: a polarizing element, a first optically anisotropic layer, a third optically anisotropic layer 1, a second optically anisotropic layer, and a reflective plate
Example 2: a polarizing element, a first optically anisotropic layer, a third optically anisotropic layer 2, a second optically anisotropic layer, and a reflective plate
Example 3: a polarizing element, a first optically anisotropic layer, a third optically anisotropic layer 3, a second optically anisotropic layer, and a reflective plate
Example 4: a polarizing element, a first optically anisotropic layer, a third optically anisotropic layer 4, a second optically anisotropic layer, and a reflective plate
Example 5: a polarizing element, a first optically anisotropic layer, a third optically anisotropic layer 5, a second optically anisotropic layer, and a reflective plate
Comparative example 1: a polarizing element, a first optically anisotropic layer, a second optically anisotropic layer, a third optically anisotropic layer 1, and a reflective plate
Comparative example 2: a polarizing element, a third optically anisotropic layer 1, a first optically anisotropic layer, a second optically anisotropic layer, and a reflective plate
Comparative example 3: a polarizing element, a first optically anisotropic layer, a second optically anisotropic layer, and a reflective plate
Comparative example 4: a polarizing element, a general 1/2 wavelength plate 1, a third optically anisotropic layer 6, a general 1/4 wavelength plate 1, and a reflective plate (in order from the incident light side)
Comparative example 5: a polarizing element, a general 1/2 wavelength plate 2, a third optically anisotropic layer 7, a general 1/4 wavelength plate 2, and a reflective plate (in this order from the incident light side)
Comparative example 6: a polarizing element, a general 1/2 wavelength plate 1, a general 1/4 wavelength plate 1, a third optically anisotropic layer 8, and a reflective plate (in order from the incident light side)
First optically anisotropic layer:
a liquid crystal layer: ZLI-4792(Merck Co., Ltd.)
The resulting phase difference is 1/2 lambda
Δn1·d1＝275nm
Pre-torque angle (pre-torque angle) of 0 °
Torsion angle-26 °
Thickness of liquid crystal layer 2.136 μm
Second optically anisotropic layer:
a liquid crystal layer: ZLI-4792(Merck Co., Ltd.)
The phase difference produced is lambda/4
Δn2·d2＝137.5nm
Pre-twisting angle-26 °
Torsion angle-78 °
Thickness of liquid crystal layer 1.068 μm
Third optically anisotropic layer:
a liquid crystal layer: polymerizable Vertically aligned liquid Crystal Compound (Merck Co., Ltd.)
nx＝1.5283
ny＝1.5283
nz＝1.6725
The thickness of the liquid crystal layer is 0.60 μm to 1.45 μm
Rth: are described in the following 1 to 8, respectively
Third optically anisotropic layer 1:
Rth＝-120nm
third optically anisotropic layer 2:
Rth＝-115nm
third optically anisotropic layer 3:
Rth＝-130nm
third optically anisotropic layer 4:
Rth＝-80nm
third optically anisotropic layer 5:
Rth＝-150nm
third optically anisotropic layer 6:
Rth＝-174nm
third optically anisotropic layer 7:
Rth＝-209nm
third optically anisotropic layer 8:
Rth＝-133nm
a polarizing element: JET-12 (manufactured by Polatechno corporation, using spectral data of which visibility-corrected monomer transmittance Ys is 41.5% and visibility-corrected polarization Py is 99.99%, without a support layer)
A reflecting plate:
the material is as follows: ideal reflecting plate
General 1/2 wavelength plate (HWP) 1:
the material is as follows: cycloolefin Polymer (COP)
Nz coefficient 1.0
General 1/4 wavelength plate (QWP) 1:
the material is as follows: cycloolefin Polymer (COP)
Nz coefficient 1.0
General 1/2 wavelength plate (HWP) 2:
the material is as follows: cycloolefin Polymer (COP)
Nz coefficient 1.5
General 1/4 wavelength plate (QWP) 2:
the material is as follows: cycloolefin Polymer (COP)
Nz coefficient 1.5
Incident light: natural light (wavelength range: 380nm to 780nm)
Tilt angles (polar angles) θ of 40 °, 50 °, and 60 °)
Azimuth angle Φ is 0 ° to 360 ° (each 5 ° unit)
In the above test conditions, the nz coefficient is a component representing the refractive index nx、nyAnd nzIs a value represented by the following formula (2).
[ number 2]
Among the above calculation conditions, ZLI-4792 (manufactured by Merck) and cycloolefin polymer (COP) were obtained using standard data attached to LCDmaster. Further, n is an optically anisotropic layer of a third optically anisotropic layer using a polymerizable homeotropic alignment type liquid crystal compound (Merck Co., Ltd.)x、nyAnd nzThe test piece obtained by forming the liquid crystal compound into a film was measured by an Abbe's refractometer (DR-M2 ATAGO Co.).
[ Table 1]
Table 2 shows the evaluation results of the black luminance values of examples 1 to 5 and comparative examples 1 to 6.
In the calculations of examples 1 to 5 and comparative examples 1 to 6, the black luminance value at the polar angle θ of 0 ° (head-on) was 0.1 or less, and it was confirmed that the light incident from the polarizing element was sufficiently suppressed in reflection from the reflective plate by the circular polarizing plate. Evaluation was performed based on the black luminance value in the polar angle θ of 0 °. The black luminance value of 0 or almost 0 indicates that the circularly polarizing plate functions favorably to suppress reflection of incident light.
Using the above calculation results, the distribution of black luminance at an azimuth angle Φ of 0 ° to 360 ° corresponding to a range of a polar angle θ of 0 ° to 80 ° is represented by a contour plot (contour map) with the center as the polar angle θ of 0 ° (head-on). The display black luminance at this time is fixed in a range of a value of minimum 0 to a value of maximum 10. Fig. 4 to 6 show examples 1 to 3, respectively, and fig. 7 to 12 show contour maps of comparative examples 1 to 6, respectively. In the contour diagrams of examples 1 to 3, the contour lines showing the maximum luminance values when the polar angle θ was shifted from 0 ° to 80 ° (from the circle center toward the outer circle end of the diagram) were 1.6 to 1.8, which are smaller values than those of the comparative examples, and thus it was found that they exhibited wider viewing angles. In addition, in the case of comparative example 5, the maximum luminance value exceeded 10.
In order to quantitatively compare the improvement effect of the black luminance when viewed from an oblique direction, the black luminance value was extracted from the above calculation result under the conditions of the polar angle θ and the azimuth angle Φ described below. The results of plotting the black luminance value at this time against the azimuth angle Φ are shown in fig. 13 to 21.
The polar angle θ is 40 °, 50 °, 60 °
The results plotted under the aforementioned conditions are shown in fig. 13 to 15 for examples 1 to 3. In detail, in examples 1 to 3 in which Rth of the third optically anisotropic layer is in the range of-130 nm to-115 nm, there is little difference in black luminance values at polar angles θ of 40 °, 50 ° and 60 °, respectively, and the average value (B) of black luminance at azimuth angles Φ of 0 ° to 360 ° (in 45 °) in the foregoing respective polar angles is 0.26 to 0.68. It is thus estimated that the black luminance increases by 2.7 times to 7.6 times when viewed from oblique angles of 40 °, 50 °, and 60 ° with respect to the polar angle θ of 0 ° (a). In addition, in the case of examples 4 and 5 in which the Rth of the third optically anisotropic layer was in the range of-80 nm and-150 nm, the increase in black luminance was 3.2 times to 10.0 times when calculated in the same manner as described above. From this, it is understood that the range of Rth of the third optically anisotropic layer is preferably from-130 nm to-115 nm, whereby the black luminance when viewed from an oblique direction can be further reduced.
The results are shown in fig. 16 to 18, plotted under the aforementioned conditions for comparative examples 1 to 3. In comparative examples 1 to 3 in which Rth of the third optically anisotropic layer was fixed to-120 nm and the third optically anisotropic layer was disposed after the second optically anisotropic layer or before the first optically anisotropic layer or without the third optically anisotropic layer, the black luminance values of the respective polar angles θ of 40 °, 50 ° and 60 ° showed larger values than those of examples 1 to 5. In addition, the average value (B) of the black luminance of the azimuth angle in each polar angle was determined in the same manner as described above, and was 0.59 to 1.72 in comparative examples 1 to 2 and 1.27 to 3.88 in comparative example 3. From this, it is estimated that the black luminance when viewed from oblique angles of 40 °, 50 ° and 60 ° with respect to the polar angle θ of 0 ° (a) is increased to 6.3 times to 18.2 times in comparative examples 1 to 2 and 13.4 times to 41.1 times in comparative example 3. The results show that the structures of examples 1 to 5 have improved viewing angle characteristics compared to conventional comparative examples 1 to 3.
In comparative examples 4 to 6, the third optically anisotropic layer having the following Rth value was used: rth values at the widest angles of the displays of the circularly polarizing plates having the retardation film under the above conditions (comparative example 4: -174nm, comparative example 5: -209nm, and comparative example 6: -133 nm). In the same manner as in examples 1 to 5, black luminance values at polar angles θ of 40 °, 50 ° and 60 ° were obtained and plotted, and the results are shown in fig. 19 to 21. In any of the conditions, the black luminance values showed large values not only in examples 1 to 5 but also in comparative examples 1 to 3, and in the configurations of comparative examples 4 to 6 using the conventional COP film, a wide angle could not be achieved even if the third optically anisotropic layer was disposed.
[ Table 2]
As a result, in the configuration of the circularly polarizing plate of the present invention, the band can be widened more than that of the circularly polarizing plate of the conventional configuration by selecting the arrangement of the third optically anisotropic layer with respect to the first optically anisotropic layer and the second optically anisotropic layer, as well as by optimizing the presence or absence of the third optically anisotropic layer and the Rth value thereof. Therefore, according to the present invention, for example, a black screen of an organic EL display device or the like can be obtained in which light leakage is small when viewed from an oblique direction.
In addition, the retardation plate of the present invention may further include first and second optically anisotropic layers having the most preferable wavelength dispersion characteristics (i.e., wavelength dependence of retardation) in order to further reduce black luminance at a polar angle of 0 °. Similarly, in the third optically anisotropic layer, by negatively dispersing the wavelength dispersion characteristic (reverse wavelength dispersion), the black luminance in the black screen when viewed from an oblique direction can be further reduced.
[ industrial applicability ]
The present application can provide a retardation plate that reduces coloring or reflectance in a black screen when viewed obliquely, a circularly polarizing plate having the retardation plate, and a liquid crystal display device and an organic EL display device having the circularly polarizing plate. For example, the organic EL display device can provide a wider viewing angle, and therefore, is preferably used for a vehicle in which the installation and viewing position of the display device are fixed. Further, the method for manufacturing a circularly polarizing plate can be provided by roll-to-roll lamination, and thus can be applied to the manufacture of a circularly polarizing plate for a large display device.
Description of the reference numerals
101 phase difference plate of the invention
102 first optically anisotropic layer
103 second optically anisotropic layer
104 third optically anisotropic layer
105 circular polarizing plate of the present invention
106 polarizing element (polarizing plate)
107 twisted nematic liquid crystal
108 base material 1 (alignment film)
109 base material 2 (alignment film)
201 absorb axial direction (0 degree)
202 rubbing direction (alignment direction) (0 degree)
203 direction of torsion angle (26 degree)
204 rubbing direction (alignment direction) (26 deg.)
205 angular direction of twist (104 deg.)
206 is shown parallel to 201.
Claims (7)
1. A phase difference plate is provided with:
a first optically anisotropic layer which is an optically anisotropic layer in which a rod-like liquid crystal compound is aligned with a thickness direction thereof being a helical axis and which has an in-plane phase difference value (Re) of substantially 1/2 wavelengths;
a second optically anisotropic layer which is an optically anisotropic layer in which a rod-like liquid crystal compound is aligned with a thickness direction thereof being a helical axis and which has an in-plane phase difference value (Re) of substantially 1/4 wavelengths; wherein the content of the first and second substances,
a third optically anisotropic layer satisfying the following formula (1) is provided between the first and second optically anisotropic layers,
nx≒ny<nz(1)
in the formula, nxAnd nyRepresenting the refractive indices of orthogonal plate plane directions, nzIndicating the refractive index in the direction perpendicular to the plane direction of the plate.
2. The phase difference plate according to claim 1, wherein a twist angle of the first optically anisotropic layer is substantially 26 ° or substantially-26 °, and a twist angle of the second optically anisotropic layer is substantially 78 ° or substantially-78 ° from the twist angle of the first optically anisotropic layer.
3. The phase difference plate according to claim 1 or 2, wherein the third optically anisotropic layer is a layer having a homeotropically aligned liquid crystal compound, and the thickness direction phase difference value (Rth) is-150 to-80 nm.
4. A circularly polarizing plate comprising a polarizing element and the retardation plate according to any one of claims 1 to 3.
5. The circularly polarizing plate of claim 4, wherein the polarizing element comprises a dichroic azo dye having an achromatic hue.
6. An organic EL display device comprising the circularly polarizing plate according to claim 4 or 5.
7. A liquid crystal display device comprising the circularly polarizing plate according to claim 4 or 5.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2019177691 | 2019-09-27 | ||
| JP2019-177691 | 2019-09-27 | ||
| PCT/JP2020/035704 WO2021060247A1 (en) | 2019-09-27 | 2020-09-23 | Retardation plate, and circular polarization plate, liquid crystal display device, and organic el display device including retardation plate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114341684A true CN114341684A (en) | 2022-04-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202080062441.8A Pending CN114341684A (en) | 2019-09-27 | 2020-09-23 | Retardation plate, and circularly polarizing plate, liquid crystal display device and organic EL display device each having the retardation plate |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPWO2021060247A1 (en) |
| KR (1) | KR20220067538A (en) |
| CN (1) | CN114341684A (en) |
| TW (1) | TW202131031A (en) |
| WO (1) | WO2021060247A1 (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014209220A (en) * | 2013-03-25 | 2014-11-06 | 富士フイルム株式会社 | Retardation plate for circularly polarizing plate, circularly polarizing plate, and organic el (electroluminescence) display device |
| JP2015040904A (en) * | 2013-08-20 | 2015-03-02 | 大日本印刷株式会社 | Optical film, image display device, transfer body for optical film, manufacturing method of optical film, and manufacturing method of transfer body for optical film |
| JP2015079230A (en) * | 2013-09-10 | 2015-04-23 | 住友化学株式会社 | Manufacturing method for laminate |
| CN106461839A (en) * | 2014-04-30 | 2017-02-22 | 日东电工株式会社 | Circular polarizer for organic el display device, and organic EL display device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4737629B2 (en) * | 2005-12-16 | 2011-08-03 | 日東電工株式会社 | Elliptical polarizing plate and image display device using the same |
| JP2007286141A (en) * | 2006-04-13 | 2007-11-01 | Sony Corp | Circularly polarizing element, liquid crystal panel and electronic equipment |
| JP5876440B2 (en) | 2013-04-25 | 2016-03-02 | 大日本印刷株式会社 | Image display device |
| JP6375381B2 (en) * | 2014-09-19 | 2018-08-15 | 富士フイルム株式会社 | Optical film, illumination device and image display device |
-
2020
- 2020-09-23 JP JP2021548915A patent/JPWO2021060247A1/ja active Pending
- 2020-09-23 CN CN202080062441.8A patent/CN114341684A/en active Pending
- 2020-09-23 WO PCT/JP2020/035704 patent/WO2021060247A1/en active Application Filing
- 2020-09-23 KR KR1020227008838A patent/KR20220067538A/en unknown
- 2020-09-25 TW TW109133316A patent/TW202131031A/en unknown
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014209220A (en) * | 2013-03-25 | 2014-11-06 | 富士フイルム株式会社 | Retardation plate for circularly polarizing plate, circularly polarizing plate, and organic el (electroluminescence) display device |
| JP2015040904A (en) * | 2013-08-20 | 2015-03-02 | 大日本印刷株式会社 | Optical film, image display device, transfer body for optical film, manufacturing method of optical film, and manufacturing method of transfer body for optical film |
| JP2015079230A (en) * | 2013-09-10 | 2015-04-23 | 住友化学株式会社 | Manufacturing method for laminate |
| CN106461839A (en) * | 2014-04-30 | 2017-02-22 | 日东电工株式会社 | Circular polarizer for organic el display device, and organic EL display device |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2021060247A1 (en) | 2021-04-01 |
| KR20220067538A (en) | 2022-05-24 |
| JPWO2021060247A1 (en) | 2021-04-01 |
| TW202131031A (en) | 2021-08-16 |
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