Phase difference plate, circular polarizing plate, liquid crystal display device and organic EL display device having the phase difference plate

Abstract

The present invention provides a phase difference plate, comprising: a first optical anisotropic layer, which is a rod-like liquid crystal compound oriented with the thickness direction as the spiral axis and having an in-plane phase difference value (Re) of substantially 1 / 2 wavelength; and a second optical anisotropic layer, which is a rod-like liquid crystal compound oriented with the thickness direction as the spiral axis and having an in-plane phase difference value (Re) of substantially 1 / 4 wavelength; wherein a third optical anisotropic layer satisfying the following formula (1) is provided between the first and second optical anisotropic layers, n x ≒ y <n z (1)(where n x and n y represents the refractive index in the direction orthogonal to the plate plane, n z Represents the refractive index in the direction perpendicular to the plate plane).

Description

Technical Field

[0001] The present invention relates to a phase difference 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 having the phase difference plate. Background Art

[0002] The retardation plate for circularly polarizing plates is used in a wide range of applications in flat-panel displays.

[0003] In the past, regarding image display panels, etc., it has been proposed to configure a circular polarizer on the surface of the image display panel, and to reduce the reflection of external light by this circular polarizer. This circular polarizer is composed of a linear polarizer and a 1 / 4 wavelength phase difference plate (hereinafter also referred to as a λ / 4 plate), and the external light toward the display surface of the image display panel is converted into linear polarization by the linear polarizer, and then converted into circular polarization by the 1 / 4 wavelength phase difference plate. Here, although the external light from the circular polarization is reflected on the surface of the image display panel, the rotation direction of the circular polarization will be reversed at the time of this reflection. As a result, the reflected light is converted into linear polarization in the opposite direction to the direction when it arrives and can be shielded by the 1 / 4 wavelength phase difference plate and the linear polarizer, and then shielded by the linear polarizer, thereby suppressing the reflected light from being exposed to the outside.

[0004] The phase difference plate used in this circular polarizer has the following problems in the past due to the wavelength dependence (wavelength dispersion) of the phase difference value: when used to prevent reflection of an organic EL display device, it does not function as a λ / 4 plate for each wavelength band in the visible light region, and produces coloration in a dark state (black screen). The above-mentioned problem becomes particularly obvious when the display device is viewed at an oblique viewing angle. In order to prevent this problem, a phase difference plate for a circular polarizer is required that can function close to 1 / 4 wavelength in a wide wavelength band and can prevent reflection over a wide range of viewing angles. The above-mentioned phase difference plate uses a phase difference plate that has been stretched uniaxially or biaxially. In addition, a method of using more than one layer of twisted nematic liquid crystal layer (twisted nematic liquid crystal layer) is also disclosed.

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2014-209220

[0008] [Patent Document 2] Japanese Patent Application Publication No. 2014-224837. Summary of the invention

[0009] [Problems to be solved by the invention]

[0010] For example, a λ / 4 plate formed by biaxially stretching a modified polycarbonate (PC) film is known to be used as a phase difference plate for widening the angle. However, the phase difference plate and the phase difference plate formed by laminating a λ / 4 plate with the same λ / 2 plate described later show reverse wavelength dispersion for the phase difference value corresponding to the visible light wavelength region, but the effect of suppressing coloration when viewed from an oblique direction is not sufficient.

[0011] In addition, there is a wide-angle phase difference plate, which is formed by laminating a λ / 4 plate formed by uniaxially stretching a cycloolefin (COP) film with the same λ / 2 plate. However, the laminated phase difference plate must be cut in such a way that each phase difference plate has a predetermined optical axis angle relative to the optical axis of the polarizing plate, and then laminated one by one using an adhesive layer, etc., which has problems in productivity.

[0012] In addition, Patent Document 1 states that a wideband λ / 4 plate is realized by controlling the twist angle and Δnd (the product of the refractive index difference (Δn) and the film thickness (d)) through two consecutive layers of twist-aligned nematic liquid crystals, which can convert linear polarization with a wider wavelength into more complete circular polarization than the well-known uniaxially stretched λ / 4 plate and λ / 2 plate phase difference plate. However, the circular polarizer using this λ / 4 plate is limited to the results observed from the direction directly above, and the display performance (reproducibility and coloring of black) when viewed from an oblique direction has not been fully discussed.

[0013] In addition, it is known that, in order to improve the display performance when viewed from an oblique direction, a positive C plate layer having a phase difference value in a thickness direction within a predetermined range is generally added to the phase difference plate. For example, Patent Document 2 attempts to improve the display performance when viewed from an oblique direction by adding a positive C plate layer to the materials of a λ / 2 plate and a λ / 4 plate.

[0014] As mentioned above, there has been a circular polarizing plate in the past, which has a wide-band λ / 4 wavelength phase difference plate composed of only "a structure using a double-layer twisted nematic liquid crystal layer having the functions of a λ / 2 plate and a λ / 4 plate" and a "stretched film", and further has a positive C plate layer, but this circular polarizing plate cannot meet the black reproducibility (the intensity of black brightness) and coloring-related display performance of the display device when viewed from an oblique direction, and further improvement is required. In addition, with respect to the positive C plate layer, there has been no discussion on the thickness direction phase difference value (Rth) and its optimal configuration relationship with the phase difference plate.

[0015] The purpose of the present application is to provide a wide-band phase difference plate for a circularly polarizing plate that reduces the black brightness in a black screen when viewed from an oblique direction (displays good black), a circularly polarizing plate having the phase difference plate, and a liquid crystal display device and an organic EL display device having the aforementioned circularly polarizing plate.

[0016] [Methods to solve the problem]

[0017] The inventors of the present application conducted detailed studies to solve the above-mentioned problems and found that they succeeded in reducing the black brightness of a black screen when viewed from an oblique direction by using a positive C plate layer between two liquid crystal layers having a twisted alignment in the thickness direction.

[0018] That is, the present invention relates to the following inventions, but is not limited thereto.

[0019] [Invention 1]

[0020] A phase difference plate, comprising:

[0021] The first optically anisotropic layer is an optically anisotropic layer in which a rod-like liquid crystal compound is aligned with the thickness direction as a helical axis and has an in-plane retardation value (Re) of substantially 1 / 2 wavelength; and

[0022] The second optically anisotropic layer is an optically anisotropic layer in which the rod-like liquid crystal compound is aligned with the thickness direction as the helical axis and has an in-plane phase difference (Re) of substantially 1 / 4 wavelength; wherein,

[0023] A third optically anisotropic layer satisfying the following formula (1) is provided between the first and second optically anisotropic layers:

[0024] n x ≒ y <n z (1)

[0025] (where n x and n y represents the refractive index in the direction orthogonal to the plate plane, n z represents the refractive index in the direction perpendicular to the plate plane).

[0026] [Invention 2]

[0027] In the phase difference plate of Invention 1, the twist angle of the first optical anisotropic layer is substantially 26° or substantially -26°, and the twist angle of the second optical anisotropic layer is substantially 78° or substantially -78° from the twist angle of the first optical anisotropic layer.

[0028] [Invention 3]

[0029] In the phase difference plate according to Invention 2, the third optically anisotropic layer is a layer having a vertically aligned liquid crystal compound, and the thickness direction phase difference value (Rth) is -150 to -80 nm.

[0030] [Invention 4]

[0031] A circularly polarizing plate comprises a polarizing element and the phase difference plate according to any one of Inventions 1 to 3.

[0032] [Invention 5]

[0033] In the circularly polarizing plate according to Invention 4, the polarizing element comprises a dichroic azo dye, and the hue thereof is an achromatic color.

[0034] [Invention 6]

[0035] An organic EL display device comprises the circularly polarizing plate according to Invention 4 or 5.

[0036] [Invention 7]

[0037] A liquid crystal display device comprises the circularly polarizing plate according to Invention 4 or 5.

[0038] [Effects of the Invention]

[0039] The present application may provide a wide-band phase difference plate for a circular polarizer that reduces the black brightness and / or reduces coloring in a black screen when viewed from an oblique direction, and a circular polarizer having the phase difference plate, and a liquid crystal display device (LCD) and an organic electroluminescent (EL) display device (organic light-emitting diode (OLED) display device) having the aforementioned circular polarizer. 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 very little coloring in the black screen of LCD and OLED display devices not only in the head-on (front) direction, but also in a wide direction of changing viewing angles. In one aspect, the present application may provide a manufacturing method that does not require complex steps such as piece-by-piece lamination or oblique extension, and circular polarizers can be made only by roll-to-roll lamination. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a cross-sectional view of a phase difference plate according to one embodiment of the present invention.

[0041] Figure 2 This is a cross-sectional view of a circularly polarizing plate according to one embodiment of the present invention.

[0042] Figure 3 This is an explanatory diagram of the "first aspect example" of the present invention.

[0043] Figure 4 This is a contour map of brightness corresponding to polar angles of 0° to 80° and azimuth angles of 0° to 360° in Example 1.

[0044] Figure 5This is a contour map of brightness corresponding to polar angles of 0° to 80° and azimuth angles of 0° to 360° in Example 2.

[0045] Figure 6 This is a contour map of brightness corresponding to polar angles of 0° to 80° and azimuth angles of 0° to 360° in Example 3.

[0046] Figure 7 It is a contour map of brightness corresponding to polar angles of 0° to 80° and azimuth angles of 0° to 360° of Comparative Example 1.

[0047] Figure 8 This is a contour map of brightness corresponding to polar angles of 0° to 80° and azimuth angles of 0° to 360° in Comparative Example 2.

[0048] Fig. 9 It is a contour map of brightness corresponding to polar angles of 0° to 80° and azimuth angles of 0° to 360° of Comparative Example 3.

[0049] Fig.10 It is a contour map of brightness corresponding to polar angles of 0° to 80° and azimuth angles of 0° to 360° of Comparative Example 4.

[0050] Fig.11 It is a contour map of brightness corresponding to polar angles of 0° to 80° and azimuth angles of 0° to 360° of Comparative Example 5.

[0051] Fig.12 This is a contour map of brightness corresponding to polar angles of 0° to 80° and azimuth angles of 0° to 360° in Comparative Example 6.

[0052] Fig.13 The experimental results of the circularly polarizing plates of Examples 1 to 3 are shown in FIG. 1 and FIG. 2 at a polar angle (tilt angle) of 40° and an azimuth angle of 0 to 360° (in units of 45°).

[0053] Fig.14 These are the experimental results of the circularly polarizing plates of Examples 1 to 3 at a polar angle (tilt angle) of 50° and an azimuth angle of 0 to 360° (in units of 45°).

[0054] Fig.15 These are the experimental results of the circularly polarizing plates of Examples 1 to 3 at a polar angle (tilt angle) of 60° and an azimuth angle of 0 to 360° (in units of 45°).

[0055] Fig.16 The experimental results of the circularly polarizing plates of Example 1 and Comparative Examples 1 to 3 are shown in FIG. 1 and FIG. 2 at a polar angle (tilt angle) of 40° and an azimuth angle of 0 to 360° (in units of 45°).

[0056] Fig.17The experimental results of the circularly polarizing plates of Example 1 and Comparative Examples 1 to 3 are shown in FIG. 1 and FIG. 2 at a polar angle (tilt angle) of 50° and an azimuth angle of 0 to 360° (in units of 45°).

[0057] Fig.18 The experimental results of the circularly polarizing plates of Example 1 and Comparative Examples 1 to 3 are shown in FIG. 1 and FIG. 2 at a polar angle (tilt angle) of 60° and an azimuth angle of 0 to 360° (in units of 45°).

[0058] Fig.19 The experimental results of the circularly polarizing plates of Example 1 and Comparative Examples 4 to 6 are shown in FIG. 1 and FIG. 2 at a polar angle (tilt angle) of 40° and an azimuth angle of 0 to 360° (in units of 45°).

[0059] Fig. 20 The experimental results of the circularly polarizing plates of Example 1 and Comparative Examples 4 to 6 are shown in FIG. 1 and FIG. 2 at a polar angle (tilt angle) of 50° and an azimuth angle of 0 to 360° (in units of 45°).

[0060] Fig.21 The experimental results of the circularly polarizing plates of Example 1 and Comparative Examples 4 to 6 are shown in FIG. 1 and FIG. 2 at a polar angle (tilt angle) of 60° and an azimuth angle of 0 to 360° (in units of 45°). DETAILED DESCRIPTION

[0061] Embodiments of the present invention are described below.

[0062] (Phase difference plate)

[0063] Phase difference plate (wavelength plate) refers to an optical element that gives a predetermined phase difference to incident linear polarization. The phase difference plate of the present invention has two optical anisotropic layers (first and second optical anisotropic layers) as a λ / 2 plate and a λ / 4 plate, respectively, and between the first and second optical anisotropic layers, a third optical anisotropic layer is provided to suppress coloring when viewed from an oblique direction. The phase difference plate of the present invention is suitable for circular polarizing plates, especially for broadband circular polarizing plates. The method for making the phase difference plate of the present invention is not particularly limited, and for example, it can be made by a well-known method such as roll-to-roll.

[0064] In the phase difference plate, a broadband is generally a phase difference plate that gives a nearly fixed phase difference in all wavelengths in the visible light region (380nm to 780nm) when incident linear polarization. Therefore, the phase difference plate used in the production of circular polarizers gives a phase difference close to 1 / 4 wavelength in all wavelengths in the visible light region.

[0065] (First and second optically anisotropic layers)

[0066] The first optical anisotropic layer of the present invention has a substantially in-plane phase difference value (Re) of 1 / 2 wavelength, and functions as a λ / 2 plate. As long as the phase difference plate of the present invention is applicable to a circular polarizer, the aforementioned Re may not be completely 1 / 2 wavelength. For example, it includes a numerical range of ±20%, 15%, 10%, 5%, 2% or 1%.

[0067] The second optically anisotropic layer of the present invention has an in-plane retardation value (Re) of substantially 1 / 4 wavelength, and functions as a λ / 4 plate. The term "substantially" is the same as described above.

[0068] Liquid crystal compounds forming the first and second optical anisotropic layers are generally classified into rod-shaped (rod-shaped liquid crystal compounds) and disc-shaped (disc-shaped liquid crystal compounds) according to their shapes. In the present invention, it is preferred to use rod-shaped liquid crystal compounds to form a twisted nematic (TN) liquid crystal layer. A TN liquid crystal layer is a liquid crystal layer in which nematic liquid crystals, in which rod-shaped elongated molecules are arranged in a roughly fixed direction, continuously change into a helical shape in which the molecular direction is twisted due to chirality.

[0069] The TN liquid crystal layer is preferably a layer formed by fixing a rod-shaped liquid crystal compound having a polymerizable group by polymerization, etc. In this case, it is not necessary to show liquid crystal properties after forming a layer. The type of polymerizable group contained in the rod-shaped liquid crystal compound is not particularly limited, and is preferably a functional group that can undergo addition polymerization, preferably a polymerizable ethylenically unsaturated group or a cyclic polymerizable group. More specifically, preferably (meth)acryloyl, vinyl, styryl, allyl, etc. can be listed, and (meth)acryloyl is more preferably used. In the present invention, well-known TN liquid crystal materials can be used. In addition, when forming a TN liquid crystal layer, an expected chiral reagent can also be used together with the above-mentioned liquid crystal compound as needed. The chiral reagent is added to cause the liquid crystal compound to undergo a twisted orientation.

[0070] Furthermore, by using the polymerizable liquid crystal material as described above in the phase difference plate, the thickness of the film-like phase difference plate can be reduced to 5 μm to 20 μm, compared with the film thickness of 50 μm to 100 μm in general.

[0071] The first and second optical anisotropic layers in the phase difference plate of the present invention are twisted and aligned with the thickness direction as the spiral axis. In addition, the twisting directions of the two liquid crystal layers are the same. In addition, the in-plane slow axis of the third optical anisotropic layer side of the first optical anisotropic layer is parallel to the in-plane slow axis of the third optical anisotropic layer side of the second optical anisotropic layer. That is, the twist angle of the second optical anisotropic layer is configured based on the twist angle of the first optical anisotropic layer. The positive and negative (minus: -) of the twist angle are when the absorption axis direction of the polarizing element is set to 0° and the polarizing element of the circular polarizer is on the viewing side, with positive indicating the direction of counterclockwise rotation from the absorption axis, and negative indicating the direction of clockwise rotation from the absorption axis.

[0072] The torsion angle of the first optical anisotropic layer used in the phase difference plate of the present invention is substantially 26° in one aspect. More specifically, it is preferably 26±10°, more preferably 26±7°, and more preferably 26±5°. In this case, the torsion angle of the second optical anisotropic layer is substantially 78°. More specifically, it is preferably 78±10°, more preferably 78±7°, and more preferably 78±5°. Or the torsion angle of the first optical anisotropic layer is substantially -26° in another aspect. More specifically, it is preferably -26±10°, more preferably -26±7°, and more preferably -26±5°. In this case, the torsion angle of the second optical anisotropic layer is substantially -78°. More specifically, it is preferably -78±10°, more preferably -78±7°, and more preferably -78±5°. The above torsion angle can be measured using a film inspection device (RETS-1100A, manufactured by Otsuka Electronics Co., Ltd.).

[0073] In the first optical anisotropic layer used in the phase difference plate of the present invention, the product (Δn1·d1) of the refractive index anisotropy Δn1 at a wavelength of 550nm and the thickness d1 of the liquid crystal layer, that is, the in-plane phase difference value (Re) is substantially 275nm. More specifically, the aforementioned product (Δn1·d1) is preferably 275±30nm, more preferably 275±20nm, and even more preferably 275±10nm.

[0074] In addition, in the second optical anisotropic layer used in the phase difference plate of the present invention, the product (Δn2·d2) of the refractive index anisotropy Δn2 at a wavelength of 550nm and the thickness d2 of the liquid crystal layer, that is, the in-plane phase difference value (Re) is substantially 137.5nm, and more specifically, the aforementioned product (Δn2·d2) is preferably 137.5±15nm, more preferably 137.5±10nm, and more preferably 137.5±5nm. The above-mentioned Δn1·d1 and Δn2·d2 can be measured using a film inspection device (RETS-1100A, manufactured by Otsuka Electronics Co., Ltd.).

[0075] (Third Optically Anisotropic Layer)

[0076] The third optical anisotropic layer of the phase difference plate of the present invention is a type of phase difference plate called a positive C plate, which refers to the following phase difference plate: when the xy orthogonal axes are set on the plate plane and the z axis is set in a direction perpendicular to the plate plane, the refractive index n in each axis direction is x 、n y 、n z Become x ≒ y <n z In addition, "n x ≒ y " indicates n x With n y Substantially equal also includes completely equal. x With n y Substantially equal", as long as it functions as a positive C plate, then n x With n y They may be different, for example, one may be 20%, 15%, 10%, 5%, 2%, or 1% different from the other. In addition, the following symbols may be used instead of "≒".

[0077] [Number 1]

[0078]

[0079] In the present invention, a well-known positive C plate can be used. In one aspect, the third optical anisotropic layer of the phase difference plate of the present invention is, for example, a liquid crystal layer in which a rod-like liquid crystal compound is vertically aligned relative to the thickness direction (plane of the plate). The aforementioned verticality includes directions in which the alignment angle of the liquid crystal compound is 90° and almost 90° relative to the plane of the plate (including differences in the extent to which its influence can be ignored, such as differences within ±10°, ±5°, ±3° or ±1°). The third optical anisotropic layer is preferably a layer formed by fixing a rod-like liquid crystal compound having a polymerizable group by polymerization, etc. In this case, after becoming a layer, it is not necessary to show liquid crystal properties. The type of polymerizable group contained in the rod-like liquid crystal compound is not particularly limited, and is preferably a functional group that can undergo addition polymerization, preferably a polymerizable ethylenically unsaturated group or a cyclic polymerizable group. More specifically, preferably, (meth)acryloyl, vinyl, styryl, allyl, etc., more preferably (meth)acryloyl.

[0080] The thickness direction retardation (Rth) of the liquid crystal layer can be adjusted by adjusting the film thickness. The film thickness is not particularly limited, but is generally preferably set within the range of 0.1 μm to 3 μm, more preferably 0.5 μm to 2 μm.

[0081] In another aspect, the cellulose resin material of Japanese Patent Application Laid-Open No. 2016-108536 can be used. From the viewpoint of thinning and productivity, it is preferable to use the aforementioned liquid crystal compound.

[0082] The thickness direction phase difference (Rth) of the third optical anisotropic layer of the present invention is determined according to the Poincare sphere theory. In order to make the coordinates on the equator representing linear polarization on the Poincare sphere to the coordinates representing circular polarization on the North Pole or the South Pole move to the minimum value, it is preferred to set the range of the most preferred value, specifically, preferably in the range of -150 to -80nm, more preferably in the range of -132 to -112nm, and more preferably in the range of -126 to -120nm. In addition, the third optical anisotropic layer is preferably arranged between the first optical anisotropic layer and the second optical anisotropic layer. Accordingly, the circularly polarized light of each wavelength generated by the phase difference plate of the present invention will be concentrated on the coordinates representing circular polarization on the North Pole or the South Pole in the Poincare sphere, and form a circularly polarized light close to the ideal in each wavelength. Therefore, in a display device etc. equipped with a circularly polarizing plate of the present invention, coloring when viewed from an oblique direction can be suppressed.

[0083] (Orientation Processing)

[0084] The first and second optical anisotropic layers of the present invention are treated to align the liquid crystal compound on the substrate, or an alignment film is provided. The liquid crystal alignment is not particularly limited as long as the alignment direction of the optical anisotropic layer is appropriately specified and does not hinder the expected performance of the present invention, and the alignment technology well known in the art can be used. A rubbing roll rotated about 0 to 50° relative to the conveying direction of the substrate can be used to physically form anisotropy on the substrate surface, or the method disclosed in Japanese Patent Publication No. 2003-014935 for performing the above-mentioned rubbing treatment on the resin layer provided on the substrate can be used, or a light alignment film can be formed on a polymer film to form an anisotropic alignment film due to linearly polarized ultraviolet rays.

[0085] (Polarizing element)

[0086] As a polarizing element (sometimes also referred to as a polarizer or polarizing film) used to obtain the circular polarizing plate, liquid crystal display device and organic EL display device of the present invention, it is not particularly limited, and a well-known polarizing element can be appropriately selected for use. For example, a polarizing element obtained by uniaxially stretching a polyvinyl alcohol (PVA) film impregnated with a water-soluble dichroic dye and / or a dichroic pigment such as polyiodide ions 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 dichroic pigment on a substrate film and aligning the dichroic pigment, a substrate integrated polarizing element obtained by arranging a polyvinyl alcohol layer on a protective film and uniaxially stretching the dichroic pigment together with the substrate film, etc. From the viewpoint of processability and optical properties, representatively, a polarizing element formed by uniaxially stretching a PVA film and adsorbing and aligning the dichroic pigment can be ideally 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 adsorbing and aligning a dichroic dye and then uniaxially stretching the film to a thickness of 25 μm to 35 μm.

[0087] The dichroic pigment is preferably an iodine ion or a dichroic dye, both of which can be used to obtain the polarizing element used in the present invention. As dichroic dyes, azo dyes, anthraquinone dyes and tetrazine dyes can be listed. From the perspective of hue design and thermal durability, it is preferred to blend 2 to 3 or more azo dyes for use. In addition, when any dichroic pigment is used, the optical properties of the polarizing element preferably have high transmittance and high polarization (also called high dichroism) from the perspective of obtaining anti-reflection ability and excellent black screen performance in the installed display device. In more detail, the sensitivity correction monomer transmittance (Ys) is preferably 40% to 45%, and the sensitivity correction polarization (Py) is preferably 99% or more.

[0088] In one aspect of the present invention, it is preferred to have an achromatic hue, that is, the monomer transmittance (Ts) of the polarizing element is preferably almost uniform throughout the visible light region (wavelength 400nm to 700nm, more preferably 380nm to 780nm). The absolute values ​​of a* and b* values ​​in the L*a*b* color system are all less than 1 when measured with a polarizing element monomer, and when the two aforementioned polarizing elements are overlapped and measured in a manner orthogonal to each other in the absorption axis direction, the absolute value of the a* value is less than 4 and the absolute value of the b* value is less than 8. The hue is also preferred as a specific aspect of the achromatic color. Accordingly, for example, by having a circular polarizer with a broadband phase difference plate of the present invention, not only can the reflected light from the display device be suppressed from coloring in the entire visible light region, but also the reflected light from the surface of the polarizing element can be suppressed from coloring in the entire visible light region.

[0089] Examples of azo dyes having dichroic properties include CIDirect Yellow 12, CIDirect Yellow 28, CIDirect Yellow 44, CIDirect Yellow 142, CIDirect Orange 26, CIDirect Orange 39, CIDirect Orange 71, CIDirect Orange 107, CIDirect Red 2, CIDirect Red 31, CIDirect Red 79, CIDirect Red 81, CIDirect Red 117, CIDirect Red 247, CIDirect Green 80, CIDirect Green 59, CIDirect Blue 71, CIDirect Blue 78, CIDirect Blue 168, CIDirect Blue 202, CIDirect Violet 9, CIDirect Violet 51, CIDirect Brown 106, and CIDirect Brown 223. Other dyes that can be produced by a known method may be used, and examples of the known method include the method described in Japanese Patent Application Laid-Open No. 3-12606 and the method described in Japanese Patent Application Laid-Open No. 59-145255. In addition, commercially available dyes include Kayafect Violet P Liquid, Kayafect Yellow Y and Kayafect Orange G, Kayafect Blue KW and Kayafect Blue Liquid 400 (all manufactured by Nippon Kayaku Co., Ltd.). Two to three or more of these azo dyes are blended in a manner that makes the transmittance of each of these azo dyes in the visible light region uniform and used. In addition, in the polarizing element of the present invention, in order to obtain a colorless polarizing element with high transmittance and high polarization, it is ideal to use the azo dyes disclosed in the International Publication WO2017 / 146212 Gazette, the International Publication WO2019 / 117131 Gazette, etc., which are improved in dichroicity for designing a colorless polarizing element.

[0090] The polarizing element preferably includes a substrate (also referred to as a support or a supporting film) for protecting the polarizing element. The substrate may be disposed only on one side of the polarizing element, or may be disposed on both sides of the polarizing element in a manner that two identical or different substrates sandwich the polarizing element. The structure having a substrate in the polarizing element is called a polarizing plate. In the case where the polarizing element has the substrate described later, the substrate disposed between the polarizing element and the display device, the in-plane phase difference value (Re) and the thickness direction phase difference (Rth) are preferably 0 or almost 0 (as a numerical value, the degree of influence thereof can be ignored, for example, in the range of -5nm to 5nm).

[0091] (Base material)

[0092] The phase difference plate and circular polarizing plate of the present invention (hereinafter also referred to as the article of the present invention) may also have a substrate. As a substrate, as long as it has the expected mechanical strength and thermal stability and does not hinder the present invention from exerting the expected performance, it is not particularly limited, and a substrate well known in the art can be used. The thickness of the substrate can be appropriately designed, preferably 50 to 200 μm, more preferably 10 to 100 μm, and more preferably 20 to 80 μm.

[0093] In addition, when a substrate is arranged between the polarizing element and the display device, the in-plane phase difference value (Re) and the thickness direction phase difference value (Rth) of the substrate are preferably 0 or almost 0. As commercially available substrates having the above-mentioned phase difference values, for example, triacetyl cellulose resin film Z-TAC (manufactured by Fuji Film Co., Ltd.), acrylic resin film OXIS series (manufactured by Okura Industry Co., Ltd.), etc. can be cited.

[0094] (Adhesive and / or bonding agent)

[0095] In the article of the present invention, a stack can also be formed by setting a next layer on a certain layer, or a stack can be formed by bonding multiple layers with an adhesive (pressure sensitive adhesive, also called pressure-sensitive adhesive) and / or an adhesive. As long as it can function as an adhesive or adhesive and does not hinder the expected performance of the present invention, it is not particularly limited, and an adhesive or adhesive well known in the art can be used. As an adhesive, representatively, acrylic resins can be listed. The thickness can be appropriately designed, but is preferably 1 to 50 μm, and from the viewpoint of interlayer adhesion and adhesive coating and processability of stacking, 5 to 25 μm is more preferred. As an adhesive, for example: a water-based adhesive with PVA-based resin as the main component, an adhesive containing a thermosetting or light-curing resin, a method performed by plasma bonding, etc. can be listed.

[0096] The phase difference and twist angle of the optically anisotropic layer of the present invention are values ​​that can achieve good optical effects. These values ​​are not particularly limited as long as the alignment characteristics of the actual liquid crystal compound and the processability of the product are taken into consideration, and may also include tolerances or margins.

[0097] (Circular polarizing plate)

[0098] The circular polarizer of the present invention is a broadband circular polarizer, and is provided with a polarizing element and a phase difference plate of the present invention, and in detail, is provided with a polarizing element (or polarizing plate), a first optical anisotropic layer, a third optical anisotropic layer and a second optical anisotropic layer in sequence. In addition, in one aspect, the optical axes of the circular polarizer are such that the absorption axis of the polarizing element is located in the direction of 0°, and the torsion angle of the first optical anisotropic layer is substantially located in the direction of 26° relative to the absorption axis of the aforementioned polarizing element, and the torsion angle of the second optical anisotropic layer is substantially in the direction of 78° (that is, the direction of 104° relative to the absorption axis of the aforementioned polarizing element).

[0099] The method for making the circular polarizing plate of the present invention is not particularly limited. For example, the films or sheets of the above-mentioned layers may be stacked one by one, or the above-mentioned layers made into a roll shape may be stacked continuously by roll-to-roll. In particular, the circular polarizing plate of the present invention does not need to be cut to match the predetermined optical axis angle to the phase difference plate, and can be easily stacked by the latter roll-to-roll. Therefore, compared with the previous method for making a broadband circular polarizing plate in which a uniaxially stretched film such as a COP film is stacked, productivity can be improved.

[0100] (Method for manufacturing circularly polarizing plate)

[0101] The manufacturing method of the phase difference plate and circular polarizing plate of the present invention can be described by the following first and second examples, but is not limited to these. In addition, each optically anisotropic layer is formed on a substrate from which the liquid crystal layer and the substrate can be peeled off after curing, and in the subsequent lamination steps described later, each substrate can also be removed to form a circular polarizing plate.

[0102] (First aspect example)

[0103] As the first step, a coating composition comprising a liquid crystal compound exhibiting a polymerizable nematic liquid crystal phase, a chiral agent, a photopolymerization initiator and a diluent solvent is applied to the friction surface of the substrate that has been friction-treated in the 0° direction (transport direction), and then the solvent is removed through a drying step, and the coating is hardened by irradiation, thereby obtaining a first optically anisotropic layer having an alignment axis in the 0° direction, a twist angle of 26° and a phase difference value (Re@550nm) of 275nm.

[0104] As a second step, a coating composition comprising a liquid crystal compound exhibiting a polymerizable nematic liquid crystal phase, a photopolymerization initiator and a diluent solvent is applied onto a substrate, followed by a drying step to remove the solvent, and irradiation to harden the coating film, thereby obtaining a third optically anisotropic layer oriented in a direction perpendicular to the substrate.

[0105] In the third step, a coating composition comprising a TN liquid crystal material, a chiral agent, a photopolymerization initiator and a diluent solvent is coated on the friction surface of the substrate that has been friction-treated in a direction of 26° relative to the conveying direction. The solvent is then removed through a drying step, and the coating is hardened by irradiation, thereby obtaining a second optically anisotropic layer having an alignment axis in a direction of 26°, a twist angle of 78° and a phase difference value (Re@550nm) of 137.5nm.

[0106] As a fourth step, to become Figure 3 The circularly polarizing plate of the present invention is obtained by laminating a polarizing element (or a polarizing plate), a first optically anisotropic layer, a third optically anisotropic layer, and a second optically anisotropic layer in sequence in the manner of the optical axis relationship shown in FIG.

[0107] (Second aspect example)

[0108] In the second step, a coating composition comprising a liquid crystal compound exhibiting a polymerizable nematic liquid crystal phase, a photopolymerization initiator, and a diluent solvent is applied to the liquid crystal surface of the first optically anisotropic layer obtained in the first step, and then a drying step is performed to remove the solvent, and the coating film is cured by irradiation, thereby obtaining a third optically anisotropic layer aligned in a direction perpendicular to the liquid crystal surface. Figure 3 The circularly polarizing plate of the present invention is obtained by laminating a polarizing element (or polarizing plate), a first optically anisotropic layer laminated with a third optically anisotropic layer, and a second optically anisotropic layer in sequence, and the like in the same manner as in the first embodiment except that the polarizing element (or polarizing plate) has the optical axis relationship shown in FIG.

[0109] (Display device)

[0110] The circular polarizer of the present invention is preferably applied to the viewing side of various display devices such as a liquid crystal display device (LCD), an organic electroluminescent (EL) display device (organic light emitting diode (OLED) display device). In addition, the display device may also be designed to include a touch screen, an anti-glare layer or an anti-reflection layer, a light-transmitting cover plate (also called a front panel), etc. In addition, the aforementioned light-transmitting cover plate may be in a flat shape or in a curved shape. The method for manufacturing the display device of the present invention is not particularly limited and can be manufactured by a well-known method.

[0111] The liquid crystal display device of the present invention may be a so-called transmissive or semi-transmissive type having a liquid crystal panel and a backlight unit, or may be a so-called reflective type having a liquid crystal panel and a reflective layer.

[0112] In addition, generally speaking, since an organic EL display device has a metal electrode in the display panel portion, the OLED (organic EL display device) itself has a higher reflectivity than a liquid crystal panel. This is the reason why, when used in an environment with a lot of external light, such as outdoors during the day, the display performance is impaired due to the reflection of external light from the electrode. Therefore, in order to suppress the reflection of external light, a circular 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 are also dependent on the optical characteristics of the circular polarizing plate. The circular polarizing plate of the present invention has a wider viewing angle characteristic than conventional circular polarizing plates, and therefore can be ideally used in organic EL display devices that require a wide range of viewing angles.

[0113] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various changes and modifications can be made based on the technical concept of the present invention.

[0114] [Example]

[0115] The present invention is specifically described below by way of examples, but the present invention is not limited by these examples.

[0116] Assuming that the circular polarizer is attached to an ideal reflector, the liquid crystal simulation software LCD master (manufactured by SYMTEC) is used to calculate the black brightness (units are standardized values) at the following azimuth angles and tilt angles (polar angles). The composition and calculation conditions of the circular polarizer are as follows. Table 1 shows an overview of the relationship between the following calculation conditions and the configuration of the optical anisotropic layer. The in-plane phase difference value (Re) and the thickness direction phase difference value (Rth) are values ​​expressed at a wavelength of 550nm. In addition, the optical anisotropic layers configured in Table 1 are shown in the columns of the 1st layer, the 2nd layer, and the 3rd layer in order from the incident light side.

[0117] The structure of circular polarizer:

[0118] Example 1: (from the incident light side) polarizing element, first optical anisotropic layer, third optical anisotropic layer 1, second optical anisotropic layer, reflecting plate

[0119] Example 2: (from the incident light side) polarizing element, first optical anisotropic layer, third optical anisotropic layer 2, second optical anisotropic layer, reflecting plate

[0120] Example 3: (from the incident light side) polarizing element, first optical anisotropic layer, third optical anisotropic layer 3, second optical anisotropic layer, reflecting plate

[0121] Example 4: (from the incident light side) polarizing element, first optical anisotropic layer, third optical anisotropic layer 4, second optical anisotropic layer, reflecting plate

[0122] Example 5: (from the incident light side) polarizing element, first optical anisotropic layer, third optical anisotropic layer 5, second optical anisotropic layer, reflecting plate

[0123] Comparative Example 1: (from the incident light side) polarizing element, first optical anisotropic layer, second optical anisotropic layer, third optical anisotropic layer 1, reflecting plate

[0124] Comparative Example 2: (from the incident light side) polarizing element, third optical anisotropic layer 1, first optical anisotropic layer, second optical anisotropic layer, reflecting plate

[0125] Comparative Example 3: (from the incident light side) polarizing element, first optical anisotropic layer, second optical anisotropic layer, reflecting plate

[0126] Comparative Example 4: (from the incident light side) polarizing element, general 1 / 2 wavelength plate 1, third optical anisotropic layer 6, general 1 / 4 wavelength plate 1, reflecting plate

[0127] Comparative Example 5: (from the incident light side) polarizing element, general 1 / 2 wavelength plate 2, third optical anisotropic layer 7, general 1 / 4 wavelength plate 2, reflecting plate

[0128] Comparative Example 6: (from the incident light side) polarizing element, general 1 / 2 wavelength plate 1, general 1 / 4 wavelength plate 1, third optical anisotropic layer 8, reflecting plate

[0129] First optically anisotropic layer:

[0130] Liquid crystal layer: ZLI-4792 (Merck)

[0131] The resulting phase difference = 1 / 2λ

[0132] Δn1·d1=275nm

[0133] Pre-twist angle = 0°

[0134] Torsion angle = -26°

[0135] Thickness of liquid crystal layer = 2.136 μm

[0136] Second optically anisotropic layer:

[0137] Liquid crystal layer: ZLI-4792 (Merck)

[0138] The resulting phase difference = λ / 4

[0139] Δn2·d2=137.5nm

[0140] Pre-twist angle = -26°

[0141] Torsion angle = -78°

[0142] Thickness of liquid crystal layer = 1.068 μm

[0143] Third optical anisotropic layer:

[0144] Liquid crystal layer: polymerizable vertical alignment type liquid crystal compound (manufactured by Merck)

[0145] n x =1.5283

[0146] n y =1.5283

[0147] n z =1.6725

[0148] Thickness of liquid crystal layer = 0.60 μm to 1.45 μm

[0149] Rth: listed in 1 to 8 below

[0150] Third optically anisotropic layer 1:

[0151] Rth=-120nm

[0152] Third optically anisotropic layer 2:

[0153] Rth=-115nm

[0154] Third optically anisotropic layer 3:

[0155] Rth=-130nm

[0156] Third optically anisotropic layer 4:

[0157] Rth=-80nm

[0158] Third optically anisotropic layer 5:

[0159] Rth=-150nm

[0160] Third optically anisotropic layer 6:

[0161] Rth=-174nm

[0162] Third optically anisotropic layer 7:

[0163] Rth=-209nm

[0164] Third optically anisotropic layer 8:

[0165] Rth=-133nm

[0166] Polarizing element: JET-12 (manufactured by Polatechno, using spectral data with sensitivity correction single unit transmittance Ys=41.5% and sensitivity correction polarization Py=99.99%, without a support layer)

[0167] Reflector:

[0168] Material: Ideal reflector

[0169] General 1 / 2 Wavelength Plate (HWP)1:

[0170] Material: Cyclic Olefin Polymer (COP)

[0171] Nz factor = 1.0

[0172] General 1 / 4 Wavelength Plate (QWP)1:

[0173] Material: Cyclic Olefin Polymer (COP)

[0174] Nz factor = 1.0

[0175] General 1 / 2 Wavelength Plate (HWP)2:

[0176] Material: Cyclic Olefin Polymer (COP)

[0177] Nz factor = 1.5

[0178] General 1 / 4 Wavelength Plate (QWP)2:

[0179] Material: Cyclic Olefin Polymer (COP)

[0180] Nz factor = 1.5

[0181] Incident light: natural light (wavelength range: 380nm to 780nm)

[0182] Tilt angle (polar angle) θ = 40°, 50° and 60°)

[0183] Azimuth Φ = 0° to 360° (in units of 5°)

[0184] In the above test conditions, the nz coefficient is used to represent the refractive index component n x 、n y and n zOne of the indicators of the size relationship of , which is the value shown in the following formula (2).

[0185] [Number 2]

[0186]

[0187] In the above calculation conditions, ZLI-4792 (Merck) and cycloolefin polymer (COP) are standard data attached to LCDmaster. In addition, the third optical anisotropic layer of polymerizable vertical alignment type liquid crystal compound (Merck) is used. x 、n y and n z , is measured using an Abbe's refractometer (DR-M2, manufactured by ATAGO Corporation) on a test piece obtained by film-forming the liquid crystal compound.

[0188] [Table 1]

[0189]

[0190] Table 2 shows the evaluation results of the black brightness values ​​of Examples 1 to 5 and Comparative Examples 1 to 6.

[0191] In the calculations of Examples 1 to 5 and Comparative Examples 1 to 6, the black brightness value at the polar angle θ = 0° (head-on) is shown to be less than 0.1, confirming that the light incident from the polarizing element is fully suppressed by the circular polarizing plate and the reflection from the reflector. The evaluation is based on the black brightness value at this polar angle θ = 0°. In addition, this black brightness value is 0 or almost 0, indicating that the circular polarizing plate suppresses the reflection of the incident light and functions ideally.

[0192] Using the above calculation results, the center is set to the polar angle θ = 0° (head-on), and the distribution of black brightness at azimuth angles Φ = 0° to 360° corresponding to the range of polar angles θ = 0° to 80° is represented by a contour diagram. At this time, the black brightness is fixed in the range of a minimum value of 0 to a maximum value of 10. Figures 4 to 6 Examples 1 to 3 are shown respectively, and Figures 7 to 12 The contour diagrams of Comparative Examples 1 to 6 are shown respectively. In the contour diagrams of Examples 1 to 3, the contour lines showing the maximum brightness value when the polar angle θ is shifted from 0° to 80° (from the center of the circle of the figure to the outer circle end) are 1.6 to 1.8, which is smaller than the values ​​of each comparative example, so it is known that it presents a wider viewing angle. In addition, in the case of Comparative Example 5, the maximum brightness value exceeds 10.

[0193] In order to quantitatively compare the improvement effect of black brightness when viewed from an oblique direction, black brightness values ​​were selected from the above calculation results under the conditions of the polar angle θ and the azimuth angle Φ described below. The results of plotting the black brightness values ​​against the azimuth angle Φ at this time are shown in Figures 13 to 21 .

[0194] Polar angle θ = θ = 40°, 50°, 60°

[0195] Azimuth Φ = 0° to 360° (in units of 45°)

[0196] For Examples 1 to 3, the results of plotting under the above conditions are shown in Figures 13 to 15 . In detail, in Examples 1 to 3 where the Rth of the third optical anisotropic layer ranges from -130nm to -115nm, there is almost no difference in the black brightness values ​​at polar angles θ=40°, 50° and 60°, respectively, and the average value (B) of the black brightness at azimuth angles Φ=0° to 360° (in units of 45°) in the aforementioned polar angles is 0.26 to 0.68. It can be estimated that the black brightness will increase by 2.7 to 7.6 times when viewed from an oblique direction at polar angles θ=40°, 50° and 60° relative to the polar angle θ=0° (A). In addition, for Examples 4 and 5 where the Rth of the third optical anisotropic layer ranges from -80nm and -150nm, when calculated in the same manner as above, the increase in black brightness is 3.2 to 10.0 times. It can be seen from this that the Rth of the third optically anisotropic layer is preferably in the range of -130 nm to -115 nm, whereby the black brightness when viewed from an oblique direction can be further reduced.

[0197] For Comparative Examples 1 to 3, the above conditions were used to plot the results. Figures 16 to 18 . In Comparative Examples 1 to 3, in which the Rth of the third optical anisotropic layer is fixed at -120 nm and the third optical anisotropic layer is disposed after the second optical anisotropic layer or before the first optical anisotropic layer, or in the absence of the third optical anisotropic layer, the black brightness values ​​at the respective polar angles θ=40°, 50°, and 60° all show larger values ​​than those of Examples 1 to 5. In addition, the average value (B) of the black brightness at the azimuth angle in each polar angle is obtained in the same manner as described above, and is 0.59 to 1.72 in Comparative Examples 1 to 2, and 1.27 to 3.88 in Comparative Example 3. It can be estimated that the black brightness when viewed obliquely at polar angles θ=40°, 50°, and 60° increases by 6.3 to 18.2 times in Comparative Examples 1 to 2, and increases by 13.4 to 41.1 times in Comparative Example 3 relative to the polar angle θ=0° (A). These results show that the configurations of Examples 1 to 5 have improved viewing angle characteristics compared to the conventional Comparative Examples 1 to 3.

[0198] In Comparative Examples 4 to 6, a third optical anisotropic layer having the following Rth values ​​was used: the Rth values ​​of the display body having a circular polarizing plate with a phase difference plate having the conditions at the widest angle (Comparative Example 4: -174nm, Comparative Example 5: -209nm, and Comparative Example 6: -133nm). As in Examples 1 to 5, the black brightness values ​​at polar angles θ = 40°, 50°, and 60° were obtained and plotted, and the results are shown in Figures 19 to 21 In any of the conditions, the black brightness value showed a larger value not only than Examples 1 to 5 but also compared with Comparative Examples 1 to 3. In the configurations of Comparative Examples 4 to 6 using the conventional COP film, even if the third optical anisotropic layer was arranged, a wide angle could not be achieved.

[0199] [Table 2]

[0200]

[0201] From the above results, in the configuration of the circular polarizing plate of the present invention, the broadband of the circular polarizing plate can be achieved not only by optimizing the presence or absence of the third optical anisotropic layer and its Rth value, but also by selecting the configuration of the third optical anisotropic layer relative to the first optical anisotropic layer and the second optical anisotropic layer, and the broadband is further achieved compared with the circular polarizing plate of the conventional configuration. Therefore, according to the present invention, for example, in the black screen of an organic EL display device, a black screen with less light leakage when viewed from an oblique direction can be obtained.

[0202] In addition, in the phase difference plate of the present invention, in order to further reduce the black brightness at the polar angle 0°, the first and second optical anisotropic layers having the most preferred wavelength dispersion characteristics (meaning the wavelength dependence of the phase difference) may also be provided. Similarly, in the third optical anisotropic layer, by making the wavelength dispersion characteristics negatively dispersed (reverse wavelength dispersion), the black brightness in the black screen when viewed from an oblique direction can be further reduced.

[0203] [Industrial Applicability]

[0204] The present application can provide a phase difference plate that reduces the coloring or reflectivity in a black screen when viewed from an oblique direction, a circular polarizing plate having the phase difference plate, and a liquid crystal display device and an organic EL display device having the aforementioned circular polarizing plate. For example, an organic EL display device can provide a wider range of viewing angles, so it can be ideally used for the setting of a display device and a vehicle with a fixed viewing position. In addition, a manufacturing method for producing a circular polarizing plate by only roll-to-roll bonding can be provided, so it can also correspond to the manufacture of circular polarizing plates for large display devices.

[0205] Description of Reference Numerals

[0206] 101 Phase difference plate of the present invention

[0207] 102 first optically anisotropic layer

[0208] 103 Second optically anisotropic layer

[0209] 104 third optically anisotropic layer

[0210] 105 Circular polarizing plate of the present invention

[0211] 106 Polarizing element (polarizing plate)

[0212] 107 Twisted Nematic Liquid Crystal

[0213] 108 Substrate 1 (Alignment Film)

[0214] 109 Substrate 2 (Alignment Film)

[0215] 201 Absorption axis direction (0°)

[0216] 202 Rubbing direction (alignment direction) (0°)

[0217] 203 Torsion angle direction (26°)

[0218] 204 Rubbing direction (alignment direction) (26°)

[0219] 205 Torsion angle direction (104°)

[0220] 206 means parallel to 201.

Claims

1. A phase difference plate, comprising: The first optically anisotropic layer is an optically anisotropic layer in which a rod-like liquid crystal compound is aligned with the thickness direction as a helical axis and has an in-plane retardation value (Re) of substantially 1 / 2 wavelength; The second optically anisotropic layer is an optically anisotropic layer in which the rod-like liquid crystal compound is aligned with the thickness direction as the helical axis and has an in-plane phase difference (Re) of substantially 1 / 4 wavelength; wherein, A third optically anisotropic layer satisfying the following formula (1) is provided between the first and second optically anisotropic layers: n x ≈n y <n z (1) Where n x and n y represents the refractive index in the direction orthogonal to the plate plane, n z Represents the refractive index in the direction perpendicular to the plate plane, The third optically anisotropic layer is a layer having a vertically aligned liquid crystal compound, and the thickness direction retardation value (Rth) is -150 to -80 nm.

2. The phase difference plate according to claim 1, wherein the twist angle of the first optical anisotropic layer is substantially 26° or substantially -26°, and the twist angle of the second optical anisotropic layer is substantially 78° or substantially -78° calculated from the twist angle of the first optical anisotropic layer.

3. A circular polarizing plate comprising a polarizing element and the phase difference plate according to claim 1 or 2. 4 . The circularly polarizing plate according to claim 3 , wherein the polarizing element comprises a dichroic azo dye whose hue is achromatic. 5 . An organic EL display device comprising the circularly polarizing plate according to claim 3 . 6 . A liquid crystal display device comprising the circularly polarizing plate according to claim 3 .

Images