阅读说明：本技术 液晶显示装置 (Liquid crystal display device having a plurality of pixel electrodes ) 是由 岩崎达也 铃木雅明 大室克文 于 2018-05-08 设计创作，主要内容包括：本发明提供一种即使在起偏器与光学补偿层的贴合角度有偏差的情况下,黑色显示时从倾斜方向视觉辨认时的色调变化也得到了抑制的液晶显示装置。本发明的液晶显示装置至少包含液晶单元及夹持液晶单元而配置的一对偏振片,该液晶显示装置中,液晶性化合物的倾斜角为1.0°以下,在一对偏振片之间,在比液晶单元更靠视觉辨认侧包含配置于液晶单元的各像素区域上的各滤色器,各滤色器的Rth满足规定的要件,一对偏振片中配置于视觉辨认侧的偏振片从液晶单元侧包含光学补偿层及起偏器,光学补偿层满足规定的要件。(The invention provides a liquid crystal display device which can restrain the color tone change when the liquid crystal display device is viewed from the inclined direction in the black display even if the adhering angle between a polarizer and an optical compensation layer is deviated. A liquid crystal display device of the present invention includes at least a liquid crystal cell and a pair of polarizing plates disposed so as to sandwich the liquid crystal cell, wherein an inclination angle of a liquid crystalline compound is 1.0 DEG or less, each color filter disposed in each pixel region of the liquid crystal cell is included between the pair of polarizing plates on a viewing side of the liquid crystal cell, Rth of each color filter satisfies a predetermined requirement, the polarizing plate disposed on the viewing side of the pair of polarizing plates includes an optical compensation layer and a polarizer from the liquid crystal cell side, and the optical compensation layer satisfies the predetermined requirement.)

1. A liquid crystal display device, comprising: a liquid crystal cell including a pair of substrates, at least one of the pair of substrates having an electrode and the pair of substrates being arranged to face each other, and a liquid crystal layer, the liquid crystal layer being arranged between the pair of substrates and containing a liquid crystalline compound whose orientation is controlled, the liquid crystal cell forming an electric field having a component parallel to the substrate having the electrode via the electrode; and

A pair of polarizing plates disposed so as to sandwich the liquid crystal cell,

The tilt angle of the liquid crystalline compound is 1.0 DEG or less,

the liquid crystal unit at least comprises a1 st pixel area, a2 nd pixel area and a3 rd pixel area,

A1 st color filter disposed on the 1 st pixel region of the liquid crystal cell, a2 nd color filter disposed on the 2 nd pixel region of the liquid crystal cell, and a3 rd color filter disposed on the 3 rd pixel region of the liquid crystal cell are included between the pair of polarizing plates on a viewing side of the liquid crystal cell,

λ is a wavelength at which the maximum transmittance of the 1 st color filter is displayed₁And λ is a wavelength at which the maximum transmittance of the 2 nd color filter is displayed₂And setting a wavelength for displaying a maximum transmittance of the 3 rd color filter to λ₃When, λ is satisfied₁＜λ₂＜λ₃In the context of (a) or (b),

Wavelength λ of the 1 st color filter₁retardation in the thickness direction Rth (. lamda.)₁) Wavelength lambda of the 2 nd color filter₂Retardation in the thickness direction Rth (. lamda.)₂) And the wavelength lambda of the 3 rd color filter₃Retardation in the thickness direction Rth (. lamda.)₃) Satisfies the requirements of the formulas (1) to (3),

Formula (1) (Rth (lambda)₁)-5nm)≤Rth(λ₂)≤Rth(λ₃)

Rth (lambda) of formula (2) -5nm ≤₂)≤25nm

Formula (3) -10nm ≤ Rth (lambda)₁)≤25nm

The polarizing plate disposed on the viewing side of the pair of polarizing plates includes an optical compensation layer and a polarizer from the liquid crystal cell side,

The in-plane slow axis of the optical compensation layer is parallel to the absorption axis of the polarizer,

the optical compensation layer has an in-plane retardation Re (450) at a wavelength of 450nm, an in-plane retardation Re (550) at a wavelength of 550nm, and an in-plane retardation Re (650) at a wavelength of 650nm, which satisfy the requirements of the formulae (5) and (6),

Re (450)/Re (550) of 0.95-1.10 of the formula (4)

The formula (5) Re (550)/Re (650) is not less than 0.95 and not more than 1.10.

2. the liquid crystal display device according to claim 1, which satisfies the requirement of formula (1-1),

Rth (lambda) of the formula (1-1)₁)≤Rth(λ₂)≤Rth(λ₃)。

3. The liquid crystal display device according to claim 1 or 2,

The optical compensation layer is 1 layer,

The optical compensation layer has an in-plane retardation Re1(550) at a wavelength of 550nm and a thickness-direction retardation Rth1(550) at a wavelength of 550nm satisfying the requirements of the formulae (6) and (7),

Formula (6) 200 nm-Re 1(550) -320 nm

The Rth1(550) is more than or equal to 40nm and more than or equal to 40nm in the formula (7).

4. the liquid crystal display device according to claim 1 or 2,

The optical compensation layer comprises a1 st optical compensation layer and a2 nd optical compensation layer in this order from the liquid crystal cell side,

The 1 st optical compensation layer has an in-plane retardation Re1(550) at a wavelength of 550nm and a thickness-direction retardation Rth1(550) at a wavelength of 550nm satisfying the requirements of the formulae (8) and (9),

formula (8) Re1(550) is not less than 80nm and not more than 200nm

Formula (9) 20 nm-Rth 1(550) -150 nm

The 2 nd optical compensation layer has an in-plane retardation Re2(550) at a wavelength of 550nm and a thickness-direction retardation Rth2(550) at a wavelength of 550nm satisfying the requirements of the formulae (10) and (11),

Formula (10) Re2(550) is not less than 0nm and not more than 40nm

The Rth2(550) is more than or equal to 160nm and less than or equal to-40 nm in the formula (11).

5. The liquid crystal display device according to claim 4,

The 1 st optical compensation layer is a positive A plate, and the 2 nd optical compensation layer is a positive C plate.

6. The liquid crystal display device according to claim 5,

The 1 st optical compensation layer is a lambda/4 layer.

7. the liquid crystal display device according to any one of claims 4 to 6,

The 2 nd optical compensation layer satisfies the requirement of formula (12) with respect to retardation in the thickness direction at a wavelength of 450nm Rth2(450) and retardation in the thickness direction at a wavelength of 550nm Rth2(550),

The Rth2(450)/Rth2(550) of the formula (12) is less than or equal to 1.00.

8. The liquid crystal display device according to any one of claims 4 to 7,

The 2 nd optical compensation layer is a film in which a liquid crystalline compound is immobilized in an aligned state.

9. The liquid crystal display device according to claim 8,

The 2 nd optical compensation layer is a film in which a rod-like liquid crystalline compound is immobilized in a state of being aligned in a direction perpendicular to a substrate surface.

10. the liquid crystal display device according to any one of claims 4 to 9,

The 1 st optical compensation layer is a cycloolefin polymer film.

11. The liquid crystal display device according to any one of claims 1 to 10,

The polarizing plate located on the non-viewing side of the liquid crystal cell includes a polarizer,

The refractive index is substantially isotropic between the polarizer and the liquid crystal layer.

12. The liquid crystal display device according to any one of claims 1 to 11,

The optical compensation layer is bonded to the polarizer via a polyvinyl alcohol-based adhesive.

13. The liquid crystal display device according to any one of claims 1 to 11,

the optical compensation layer is bonded to the polarizer via a curable adhesive composition cured by irradiation of an active energy ray or heating.

14. The liquid crystal display device according to any one of claims 1 to 13, which satisfies the requirement of formula (1-2),

Rth (lambda) of the formula (1-2)₁)＜Rth(λ₂)＜Rth(λ₃)。

Technical Field

The present invention relates to a liquid crystal display device.

background

An IPS (In-Plane Switching) type and an FFS (Fringe Field Switching) type liquid crystal display device are a so-called lateral electric Field type (mode) In which a liquid crystal compound responds In a substrate In-Plane direction by an electric Field containing a component substantially parallel to a substrate surface, rather than a mode In which an electric Field is applied between upper and lower substrates and driven by the rising of the liquid crystal compound as In TN (Twisted Nematic) type and VA (Vertical Alignment) type.

Further, the IPS type and the FFS type are systems that are less restricted in viewing angle in principle due to their structures, and therefore are known as driving systems having characteristics such as less chromaticity shift and less change in color tone in addition to a wide viewing angle.

As for these lateral electric field type liquid crystal display devices, patent document 1 discloses a configuration in which a polarizing plate, a liquid crystal layer, a color filter, and an optical compensation member are combined in order to reduce a change in color tone in an oblique direction of black display.

Prior art documents

Patent document

patent document 1: japanese patent laid-open No. 2014-16642

Disclosure of Invention

Technical problem to be solved by the invention

in manufacturing a liquid crystal display device, various members are generally bonded to each other. In this case, for example, the absorption axis of the polarizer and the in-plane slow axis of the optical compensation layer are bonded so as to have a predetermined angular relationship.

As a result of studies on the liquid crystal display device of patent document 1, the present inventors have found the following problems: if the angle formed by the absorption axis of the polarizer and the in-plane slow axis of the optical compensation layer is slightly out of a predetermined range, the change in color tone in the oblique direction during black display increases. If the above-described problem occurs, the desired effect cannot be exhibited if the bonding angle between the polarizer and the optical compensation layer is slightly deviated when the liquid crystal display device is manufactured, and thus the yield is likely to be lowered.

In view of the above circumstances, an object of the present invention is to provide a liquid crystal display device in which even when the bonding angle between a polarizer and an optical compensation layer is deviated, a change in color tone when viewed from an oblique direction in black display is suppressed.

Means for solving the technical problem

The present inventors have intensively studied the problems of the prior art and found that the above problems can be solved by a liquid crystal display device having a predetermined structure.

That is, it was found that the above object can be achieved by the following structure.

(1) A liquid crystal display device has: a pair of substrates arranged to face each other, at least one of the substrates having an electrode; and a liquid crystal layer which is disposed between the pair of substrates, contains a liquid crystalline compound whose orientation is controlled, and at least includes: a liquid crystal cell in which an electric field having a component parallel to a substrate having an electrode is formed by the electrode; and

A pair of polarizing plates disposed so as to sandwich the liquid crystal cell,

the tilt angle of the liquid crystalline compound is 1.0 DEG or less,

The liquid crystal unit at least comprises a1 st pixel region, a2 nd pixel region and a3 rd pixel region,

Between the pair of polarizing plates, a1 st color filter disposed on a1 st pixel region of the liquid crystal cell, a2 nd color filter disposed on a2 nd pixel region of the liquid crystal cell, and a3 rd color filter disposed on a3 rd pixel region of the liquid crystal cell are included on a side of the liquid crystal cell to be visually recognized,

λ is the wavelength at which the maximum transmittance of the 1 st color filter is displayed₁And λ is the wavelength at which the maximum transmittance of the 2 nd color filter is displayed₂And setting the wavelength for displaying the maximum transmittance of the 3 rd color filter as lambda₃When, λ is satisfied₁＜λ₂＜λ₃In the context of (a) or (b),

Wavelength λ of 1 st color filter₁retardation in the thickness direction Rth (. lamda.)₁) 2 nd wavelength of color filter₂Retardation in the thickness direction Rth (. lamda.)₂) And wavelength lambda of the 3 rd color filter₃Retardation in the thickness direction Rth (. lamda.)₃) Satisfies the requirements of the following equations (1) to (3),

The polarizing plate disposed on the viewing side of the pair of polarizing plates includes an optical compensation layer and a polarizer from the liquid crystal cell side,

The in-plane slow axis of the optical compensation layer is parallel to the absorption axis of the polarizer,

The optical compensation layer satisfies the requirements of the following equations (5) and (6) for an in-plane retardation Re (450) at a wavelength of 450nm, an in-plane retardation Re (550) at a wavelength of 550nm, and an in-plane retardation Re (650) at a wavelength of 650nm,

(2) The liquid crystal display device according to (1) satisfies the requirements of the following expression (1-1).

(3) The liquid crystal display device according to (1) or (2), wherein the optical compensation layer is 1 layer,

the in-plane retardation Re1(550) at a wavelength of 550nm and the retardation Rth1(550) in the thickness direction at a wavelength of 550nm of the optical compensation layer satisfy the requirements of the following equations (6) and (7).

(4) The liquid crystal display device according to (1) or (2), wherein the optical compensation layer comprises a1 st optical compensation layer and a2 nd optical compensation layer in this order from the liquid crystal cell side,

The 1 st optical compensation layer has an in-plane retardation Re1(550) at a wavelength of 550nm and a thickness-direction retardation Rth1(550) at a wavelength of 550nm satisfying the requirements of the following equations (8) and (9),

The 2 nd optical compensation layer satisfies the requirements of the following equations (10) and (11) for the in-plane retardation Re2(550) at a wavelength of 550nm and the retardation Rth2(550) in the thickness direction at a wavelength of 550 nm.

(5) The liquid crystal display device according to (4), wherein the 1 st optical compensation layer is a positive A plate and the 2 nd optical compensation layer is a positive C plate.

(6) The liquid crystal display device according to (5), wherein the 1 st optical compensation layer is a λ/4 layer.

(7) The liquid crystal display device according to any one of (4) to (6), wherein the 2 nd optical compensation layer has a retardation in the thickness direction at a wavelength of 450nm of Rth2(450) and a retardation in the thickness direction at a wavelength of 550nm of Rth2(550) satisfying the requirement of the following expression (12),

(8) The liquid crystal display device according to any one of (4) to (7), wherein the 2 nd optical compensation layer is a film in which a liquid crystalline compound is immobilized in an aligned state.

(9) The liquid crystal display device according to item (8), wherein the 2 nd optical compensation layer is a film in which a rod-like liquid crystalline compound is immobilized in a state of being aligned in a direction perpendicular to the substrate surface.

(10) The liquid crystal display device according to any one of (4) to (9), wherein the 1 st optical compensation layer is a cycloolefin-based polymer film.

(11) The liquid crystal display device according to any one of (1) to (10), wherein a refractive index is substantially isotropic between the polarizer located on the non-viewing side of the liquid crystal cell and the liquid crystal layer.

(12) the liquid crystal display device according to any one of (1) to (11), wherein the optical compensation layer is bonded to the polarizer via a polyvinyl alcohol-based adhesive.

(13) The liquid crystal display device according to any one of (1) to (11), wherein the optical compensation layer is adhered to the polarizer via a curable adhesive composition cured by irradiation of an active energy ray or heating.

(14) The liquid crystal display device according to any one of (1) to (13), which satisfies the requirements of the following expression (1-2).

Effects of the invention

According to the present invention, it is possible to provide a liquid crystal display device in which even when the angle of adhesion between the polarizer and the optical compensation layer is deviated, the change in color tone when viewed from the oblique direction during black display is suppressed.

Drawings

fig. 1 is a schematic diagram showing an example of an embodiment of the present invention.

Detailed Description

The present invention will be described in detail below.

The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.

In the present specification, a numerical range expressed by using "to" means a range in which numerical values described before and after "to" are included as a lower limit value and an upper limit value.

In the present specification, the polarizing plate refers to a member in which a protective layer or a functional layer is disposed on at least one surface of a polarizer, and the polarizer and the polarizing plate are used separately.

In the present specification, the terms parallel and orthogonal mean a range of ± 5 ° parallel or orthogonal, respectively, and do not mean parallel and orthogonal in a strict sense.

In the present specification, "(meth) acrylate" is a label indicating any one of acrylate and methacrylate, "(meth) acrylic acid" is a label indicating any one of acrylic acid and methacrylic acid, and "(meth) acryloyl group" is a label indicating any one of acryloyl group and methacryloyl group.

In the present specification, Re (λ) and Rth (λ) represent an in-plane retardation and a thickness-direction retardation, respectively, at a wavelength λ. When not specifically mentioned, the wavelength λ is 550 nm.

In the present invention, Re (. lamda.) and Rth (. lamda.) are values measured at a wavelength of λ in Axoscan OPMF-1 (manufactured by Opto Science, Inc.). The following was calculated by using the AxoSacan input average refractive index ((nx + ny + nz)/3) and film thickness (d (μm)):

Slow axis direction in plane (degree)

Re(λ)＝R0(λ)

Rth(λ)＝((nx+ny)/2-nz)×d。

In the present invention, Nz is defined by an in-plane retardation Re (550) of the retardation layer having a wavelength of 550nm and a retardation Rth (550) in the thickness direction as an Nz coefficient of Rth (550)/Re (550) + 0.5.

In the present invention, as for the refractive indices nx, ny, and nz, an abbe refractometer (NAR-4T, ATAGO co., LTD, manufactured) was used, and measurement was performed using a sodium lamp (λ 589nm) as a light source.

When the wavelength dependence is measured, the measurement can be performed by a combination with an interference filter using a multi-wavelength abbe refractometer DR-M2(ATAGO co., LTD).

Further, a polymer handbook (JOHN company & SONS, INC), and the values of the product catalog of various optical films can also be used.

The values of the average refractive index of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49) and polystyrene (1.59).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The liquid crystal display device shown in fig. 1 includes a backlight unit 14 in the outermost of a liquid crystal cell (7 to 9), an upper polarizing plate 16(1 to 6) and a lower polarizing plate 17(10 to 13) disposed so as to sandwich the liquid crystal cell, and the lower polarizing plate 17. The liquid crystal cells (7-9) include a liquid crystal cell upper substrate 7, a liquid crystal cell lower substrate 9, and a liquid crystal layer 8 sandwiched therebetween. The lower substrate 9 has an electrode layer (not shown in fig. 1) on its opposite surface, and the electrode layer is configured to be able to supply an electric field parallel to the surface of the substrate 9 to the liquid crystal layer. Typically, the electrode layer comprises transparent Indium Tin Oxide (ITO). An alignment layer (not shown in fig. 1) for controlling the alignment of the liquid crystalline compound 8 is formed on the electrode layer of the substrate 9 and on the surface opposite to the substrate 7, and the alignment direction of the liquid crystalline compound 8 is controlled. In order to maintain the display symmetry, the alignment layer is preferably an UV (ultra violet: ultraviolet) alignment layer.

In fig. 1, the liquid crystal cell is disposed between an upper polarizing plate 16 and a lower polarizing plate 17. The upper polarizing plate 16 includes a protective film 1, a polarizer 2, and optical compensation layers 15(4 to 5). The lower polarizing plate 17 includes a polarizer 11, and protective films 10 and 13 disposed on both surfaces thereof.

The upper polarizing plate 16 and the lower polarizing plate 17 are arranged so that the absorption axis 3 of the polarizer 2 in the upper polarizing plate 16 and the absorption axis 12 of the polarizer 11 in the lower polarizing plate 17 are orthogonal to each other. When the upper polarizing plate 16 is a viewing-side polarizing plate, the absorption axis 3 of the polarizer 2 in the upper polarizing plate 16 is preferably laminated so as to be orthogonal to the extraordinary ray refractive index direction of the liquid crystalline compound 8 in the liquid crystal cell when no voltage is applied (OFF state).

Although not shown in fig. 1, a blue color filter (hereinafter, also referred to as "BCF"), a green color filter (hereinafter, also referred to as "GCF"), and a red color filter (hereinafter, also referred to as "RCF") are disposed on the liquid crystal cell upper substrate 7 (on the surface of the liquid crystal cell upper substrate 7 on the viewing side (upper polarizer side)).

The liquid crystal cell includes 3 pixel regions in which the BCF, the GCF, and the RCF are respectively disposed.

The BCF, GCF, and RCF correspond to the 1 st color filter, the 2 nd color filter, and the 3 rd color filter of the liquid crystal display device of the present invention, respectively. The 3 pixel regions in the liquid crystal cell correspond to the 1 st pixel region, the 2 nd pixel region, and the 3 rd pixel region included in the liquid crystal cell in the liquid crystal display device of the present invention, respectively.

in fig. 1, a case where light enters from the backlight unit 14 disposed outside the lower polarizing plate 22 is considered. In a non-drive state (OFF state) in which no drive voltage is applied to the electrodes (not shown in fig. 1), the liquid crystalline compound 8 in the liquid crystal layer is aligned so as to be substantially parallel to the surfaces of the liquid crystal cell upper substrate 7 and the liquid crystal cell lower substrate 9, and so as to have a long axis thereof substantially parallel to the absorption axis 12 of the polarizer 11. In this state, light having passed through the polarizer 11 in a predetermined polarization state is not affected by the birefringence effect of the liquid crystal compound 8, and as a result, is absorbed by the absorption axis 3 of the polarizer 2. At this time, black display is performed. ON the other hand, in a driving state (ON state) in which a driving voltage is applied to an electrode (not shown in fig. 1), an electric field containing a component parallel to the substrate is formed, and the liquid crystalline compound 8 is aligned such that the long axis thereof coincides with the direction of the electric field. As a result, the light having passed through the polarizer 11 in a predetermined polarization state changes its polarization state due to the birefringence effect of the liquid crystalline compound 8, and as a result, passes through the polarizer 2. In this case, white display is performed.

In the liquid crystal display device of the present invention, by controlling the retardation Rth in the thickness direction of the BCF, the GCF and the RCF for each pixel region and setting the phase difference and the wavelength dispersion of the optical compensation layer within predetermined ranges, even when the bonding angle between the polarizer and the optical compensation layer is deviated, the change in color tone when viewed from the oblique direction in black display is suppressed.

In the liquid crystal display device of the present invention, even when the bonding angle between the polarizer and the optical compensation layer is not substantially changed, the color tone change in the case of viewing from the oblique direction in the black display is suppressed, and the light leakage in the oblique viewing field generated in the black display is suppressed.

Hereinafter, each member included in the liquid crystal display device will be described in detail.

< liquid crystal cell >

The liquid crystal cell in the liquid crystal display device shown in fig. 1 has: a pair of substrates arranged to face each other, at least one of the substrates having an electrode; and a liquid crystal layer disposed between the substrates and containing a liquid crystalline compound whose orientation is controlled.

Alignment layers for aligning the liquid crystalline compound are preferably disposed on both inner facing surfaces of the substrates (corresponding to the upper substrate and the lower substrate of the liquid crystal cell). In general, columnar or spherical spacers for maintaining the distance (cell gap) between the 2 substrates are arranged in the liquid crystal layer.

In addition, a reflective plate, a condenser lens, a brightness enhancement film, a luminescent layer, a fluorescent layer, a phosphorescent layer, an antireflection film, an antifouling film, a hard coat film, and the like may be disposed in the liquid crystal cell.

As the substrate, a transparent glass substrate is preferable. As the substrate for a liquid crystal cell, a hard and high-temperature-resistant silica glass substrate or a plastic substrate can be used.

The type of the liquid crystalline compound constituting the liquid crystal layer is not particularly limited. For example, a nematic liquid crystal compound (for example, a nematic liquid crystal compound having a positive dielectric anisotropy Δ ∈) can be used as the liquid crystal compound. In addition, the dielectric anisotropy Δ ∈ of the nematic liquid crystal compound can be reduced in driving voltage under a large value, and the thickness (gap) of the liquid crystal layer can be increased under a small value of the refractive index anisotropy Δ n, so that the time for enclosing the liquid crystal compound can be shortened, and the gap variation can be reduced.

The thickness (gap) of the liquid crystal layer is preferably more than 2.8 μm and less than 4.5 μm.

When the retardation (Δ n · d) of the liquid crystal layer is made to exceed 0.25 μm and be less than 0.40 μm, the transmittance characteristic with almost no wavelength dependence in the visible light range can be more easily obtained.

When the liquid crystalline compound is rotated by 45 ° from the initial alignment direction to the horizontal direction, the maximum transmittance can be obtained.

In addition, the thickness (gap) of the liquid crystal layer can be controlled by polymer beads in general. In addition to the polymer beads, glass beads, fibers, and resin columnar spacers can be used.

In general, in the IPS system, unlike the longitudinal electric field system represented by the conventional TN system, the interface tilt with the substrate surface is not required in principle, and it is known that the smaller the interface tilt angle is, the better the viewing angle characteristic is.

In the liquid crystal layer in the liquid crystal display device of the present invention, the tilt angle of the liquid crystalline compound is 1.0 ° or less. The lower limit is not particularly limited, but may be 0 °. The tilt angle is an angle formed by the long axis of the liquid crystalline compound and the surface of the substrate.

In order to realize the above-mentioned tilt angle, an embodiment using an alignment layer is exemplified as described above. In the conventional mass production technique, an alignment layer is formed by rubbing an alignment control layer of a polymer film made of polyimide or the like to impart liquid crystal alignment ability (initial alignment). On the other hand, the rubbing cloth is formed by binding fine fibers having a thickness of about 10 to 30 μm, and a treatment for imparting a liquid crystal aligning ability is performed by applying a shearing force in a certain direction to a local portion of the alignment layer substantially every fine fiber. In the IPS method, since the electrode gap is about 10 to 30 μm which is about the same as the diameter of the fiber, the friction near the step is insufficient, and the alignment is likely to be disturbed. This disturbance in orientation causes a decrease in contrast ratio and a decrease in image quality such as unevenness in brightness and color tone. As a method for solving the problem of the rubbing alignment treatment, a photo-alignment method has been proposed in which a surface of a polymer film is irradiated with polarized ultraviolet rays or the like to align a liquid crystalline compound without rubbing treatment. For example, jp 2005-351924 a describes that the tilt angle of the liquid crystalline compound is 1.0 ° or less by using a photo-alignment method, and a photo-alignment method is also preferably used in the present invention.

As described above, the liquid crystal cell has BCF, GCF, and RCF disposed on its surface, and includes a pixel region corresponding to each color filter. In other words, the liquid crystal cell includes a plurality of pixel regions, and the BCF, the GCF, and the RCF are arranged on the liquid crystal cell so as to correspond to each pixel region.

In general, in a liquid crystal display device that performs color display, 1 group of sub-pixels (pixel regions) of three primary colors (red, green, and blue) of light is formed, and 1 pixel is formed. Further, 1 pixel may be formed by 3 or more sub-pixels.

< color filter >

The liquid crystal display device shown in fig. 1 includes a color filter disposed on each pixel region of a liquid crystal cell between a pair of polarizing plates. More specifically, BCF, GCF, and RCF are disposed on the upper substrate of the liquid crystal cell in the liquid crystal cell. Further, the BCF, GCF, and RCF are all disposed on the viewing side (upper polarizer side).

Further, BCF is a color filter showing the maximum transmittance in a blue region (wavelength of 420 to 490nm), GCF is a color filter showing the maximum transmittance in a green region (wavelength of 495 to 570nm), and RCF is a color filter showing the maximum transmittance in a blue region (wavelength of 580 to 700 nm).

In the present specification, the term "maximum transmittance" refers to the maximum transmittance in the visible light region (400 to 700 nm).

Let λ be the wavelength at which the maximum transmittance of BCF is exhibited₁(nm) and λ is the wavelength at which the maximum transmittance of GCF is exhibited₂(nm) and λ is the wavelength at which the maximum transmittance of RCF is exhibited₃(nm) satisfies lambda₁＜λ₂＜λ₃the relationship (2) of (c).

And, the wavelength λ of BCF₁Retardation in the thickness direction Rth (. lamda.)₁) Wavelength lambda of GCF₂retardation in the thickness direction Rth (. lamda.)₂) And wavelength λ of RCF₃Retardation in the thickness direction Rth (. lamda.)₃) Satisfies the requirements of the formulas (1) to (3).

Formula (1) (Rth (lambda)₁)-5nm)≤Rth(λ₂)≤Rth(λ₃)

Rth (lambda) of formula (2) -5nm ≤₂)≤25nm

Formula (3) -10nm ≤ Rth (lambda)₁)≤25nm

Among them, the requirement of the formula (1-1) is preferably satisfied, and the requirement of the formula (1-2) is more preferably satisfied.

Rth (lambda) of the formula (1-1)₁)≤Rth(λ₂)≤Rth(λ₃)。

Rth (lambda) of the formula (1-2)₁)＜Rth(λ₂)＜Rth(λ₃)。

Furthermore, the requirement of the formula (2-1) is preferably satisfied, and the requirement of the formula (2-2) is preferably satisfied.

Formula (2-1) -5nm ≤ Rth (lambda)₂)≤20nm

Formula (2-2)0nm ≤ Rth (λ)₂)≤15nm

Furthermore, the requirement of the formula (3-1) is preferably satisfied, and the requirement of the formula (3-2) is preferably satisfied.

Formula (3-1) -10nm ≤ Rth (lambda)₁)≤15nm

Formula (3-2) -5nm ≤ Rth (lambda)₁)≤10nm

with respect to Rth (λ)₃) The particle size is not particularly limited as long as the requirement of the formula (1) is satisfied, but is preferably 0 to 35nm, and more preferably 10 to 25 nm.

The method for realizing the above requirement is not particularly limited, but for example, as a method satisfying the requirement of the formula (1), a method of adjusting Rth of each color filter by changing the thickness of the color filter is exemplified.

further, the Rth of the color filter can be adjusted by adding a retardation raising agent or a retardation lowering agent to the color filter.

Examples of the retardation enhancer include compounds represented by the general formula (X) and compounds similar thereto.

[ chemical formula 1]

General formula (X)

Examples of the retardation reducing agent include compounds represented by the general formula (XI).

[ chemical formula 2]

General formula (XI)

In the above general formula (XI), R¹¹Represents alkyl or aryl, R¹²And R¹³Each independently represents a hydrogen atom, an alkyl group or an aryl group. And, R¹¹、R¹²And R¹³The total number of carbon atoms of (a) is preferably 10 or more. R¹¹、R¹²And R¹³The compound may have a substituent, and as the substituent, a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group or a sulfonamide group is preferable, and an alkyl group, an aryl group, an alkoxy group, a sulfone group or a sulfonamide group is more preferable.

The alkyl group may be linear, branched, or cyclic. The number of carbon atoms of the alkyl group is preferably 1 to 25, more preferably 6 to 25, and still more preferably 6 to 20. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a tert-pentyl group, a hexyl group, a cyclohexyl group, a heptyl group, an octyl group, a bicyclooctyl group, a nonyl group, an adamantyl group, a decyl group, a tert-octyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group.

The number of carbon atoms of the aryl group is preferably 6 to 30, more preferably 6 to 24. As aryl, preference is given to phenyl, biphenyl, terphenyl, naphthyl, binaphthyl or triphenylphenyl.

The method for producing the color filter (BCF, GCF, RCF) is not particularly limited, and examples thereof include a colored resist method and a lamination method in which a colored photosensitive resin composition is applied by a spin coater or the like and then patterned by a photolithography step. In a forming method including a coating step such as a colored resist method, color filters having different thicknesses can be formed by adjusting the amount of coating. In the lamination method, color filters having different thicknesses can be formed by using transfer materials having different thicknesses.

Further, a black matrix may be disposed between the color filters as necessary. The method for producing the black matrix is not particularly limited, and known methods can be exemplified.

Although the BCF, GCF, and RCF included in the liquid crystal display device shown in fig. 1 have been mainly described in detail above, the present invention is not limited to this embodiment, and the BCF, GCF, and RCF may be color filters of other colors. That is, the liquid crystal display device of the present invention includes at least the 1 st color filter, the 2 nd color filter, and the 3 rd color filter arranged in each pixel region (the 1 st pixel region to the 3 rd pixel region) of the liquid crystal cell, and the wavelength λ of the 1 st color filter is set as long as the wavelength λ of the 1 st color filter₁Retardation in the thickness direction Rth (. lamda.)₁) 2 nd wavelength of color filter₂Retardation in the thickness direction Rth (. lamda.)₂) And wavelength lambda of the 3 rd color filter₃retardation in the thickness direction Rth (. lamda.)₃) The color filter satisfying the requirements of the expressions (1) to (3) may be a color filter of a color other than BCF, GCF, and RCF.

Formula (1) (Rth (lambda)₁)-5nm)≤Rth(λ₂)≤Rth(λ₃)

Rth (lambda) of formula (2) -5nm ≤₂)≤25nm

Formula (3) -10nm ≤ Rth (lambda)₁)≤25nm

< polarizing plate >

The liquid crystal display device shown in fig. 1 includes a pair of polarizing plates.

Of the pair of polarizing plates, the polarizing plate disposed on the viewing side (upper polarizing plate) includes an optical compensation layer and a polarizer from the liquid crystal cell side. In addition, the absorption axis of the polarizer and the in-plane slow axis of the optical compensation layer are arranged in parallel.

As described above, the upper polarizing plate in fig. 1 includes the protective film on the surface of the polarizer opposite to the optical compensation layer. In addition, a cured resin layer may be disposed instead of the protective film.

Of the pair of polarizing plates, the polarizing plate disposed on the side opposite to the viewing side (lower polarizing plate) includes a polarizer and protective films disposed on both surfaces thereof.

The protective film is an arbitrary member, and may not be included in the liquid crystal display device.

The respective members will be described in detail below.

(optical Compensation layer)

The optical compensation layer is composed of 1 layer or 2 or more layers, and has substantially flat dispersion of Re wavelength as shown in the following formulae (4) and (5). The optical compensation layer has the following functions: the light leakage when viewed from the oblique side is reduced by eliminating the viewing angle dependence of a pair of polarizers arranged so that the respective absorption axes are orthogonal with respect to the G light (550 nm). The optical compensation layer can have any phase difference as long as it has an effect of reducing light leakage.

The optical compensation layer has an in-plane retardation Re (450) at a wavelength of 450nm, an in-plane retardation Re (550) at a wavelength of 550nm, and an in-plane retardation Re (650) at a wavelength of 650nm, which satisfy the requirements of the formulae (5) and (6).

Re (450)/Re (550) of 0.95-1.10 of the formula (4)

The formula (5) Re (550)/Re (650) is not less than 0.95 and not more than 1.10.

as described above, the optical compensation layer may be composed of 1 layer, or 2 or more layers. In the present invention, it is preferable that the optical compensation layer is composed of 1 or 2 layers.

Only the 1 st optical compensation layer is included in the case of a single-layer structure, and the 1 st and 2 nd optical compensation layers are included in the case of a 2-layer structure. In any layer structure, the above-described equations (4) and (5) are satisfied for the entire optical compensation layer, and the in-plane slow axis of the optical compensation layer is parallel to the absorption axis of the polarizer disposed on the same side as the liquid crystal cell (the absorption axis of the polarizer in the viewing-side polarizing plate).

The optical compensation layer is preferably a polymer film or a film formed using a liquid crystalline composition, from the viewpoint of ease of production and the like.

The polymer film is preferably a cellulose acylate film, a cycloolefin polymer film (a polymer film using a cycloolefin polymer), or an acrylic polymer film. The acrylic polymer film preferably includes an acrylic polymer containing at least 1 unit selected from a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit.

the thickness of the polymer film is preferably thin, more specifically, 1 to 150 μm, more preferably 1 to 70 μm, and still more preferably 1 to 30 μm, from the viewpoint of thinning of the liquid crystal display device, as long as the optical properties, mechanical properties, and manufacturing applicability are not impaired.

The film formed using the liquid crystalline composition is a film formed using a composition containing a liquid crystalline compound, and is preferably a film in which the liquid crystalline compound is immobilized in an aligned state. Among these, a film in which a composition containing a liquid crystalline compound having a polymerizable group is applied to form a coating film, the liquid crystalline compound in the coating film is aligned, and curing treatment is performed to fix the alignment of the liquid crystalline compound is more preferable.

The liquid crystalline compound includes rod-like liquid crystalline compounds and disk-like liquid crystalline compounds, and preferably has a polymerizable group for fixing the alignment state.

Hereinafter, specific embodiments of the optical compensation layer will be described in detail.

(case where the optical compensation layer is composed of 1 layer)

When the optical compensation layer is composed of 1 layer, it is preferably formed only of the 1 st optical compensation layer, and in the 1 st optical compensation layer, the in-plane retardation Re1(550) at a wavelength of 550nm and the retardation Rth1(550) in the thickness direction at a wavelength of 550nm satisfy the requirements of the formulae (6) and (7).

Formula (6) 200 nm-Re 1(550) -320 nm

The Rth1(550) is more than or equal to 40nm and more than or equal to 40nm in the formula (7).

The 1 st optical compensation layer is obtained, for example, by largely stretching a film of a polymer characterized by nz > nx.

As a production method, for example, in the case of using a film of cellulose acetate benzoate which is a cellulose acylate obtained by substitution with an aromatic acyl group, a dope obtained by dissolving cellulose acetate benzoate in a solvent is cast on a metal support for film formation, the solvent is dried to obtain a film, and the obtained film is stretched at a large stretch ratio of about 1.3 to 1.9 times to orient cellulose molecular chains.

Further, for example, as described in Japanese patent application laid-open Nos. 5-157911 and 2006-072309, a shrinkable film can be produced by bonding one surface or both surfaces of a polymer film and then stretching the film by heating.

The thickness of the 1 st optical compensation layer is preferably 1 to 150 μm, more preferably 1 to 70 μm, and further preferably 1 to 30 μm.

(Structure in which the optical compensation layer is composed of 2 layers)

In the case where the optical compensation layer is composed of 2 layers, 2-layer structures of a biaxial film (B-plate or positive A-plate) in which the 1 st optical compensation layer is nx > ny ≧ nz, and a [ quasi ] uniaxial film (positive [ quasi ] C-plate) in which the 2 nd optical compensation layer is nx ≈ ny < nz are preferable. Specifically, the 1 st optical compensation layer satisfies the requirements of the formulae (8) and (9) for the in-plane retardation Re1(550) at a wavelength of 550nm and the retardation Rth1(550) in the thickness direction at a wavelength of 550nm,

Formula (8) Re1(550) is not less than 80nm and not more than 200nm

Formula (9) 20 nm-Rth 1(550) -150 nm

It is preferable that the 2 nd optical compensation layer satisfy the requirements of the formulae (10) and (11) for the in-plane retardation Re2(550) at a wavelength of 550nm and the retardation Rth2(550) in the thickness direction at a wavelength of 550 nm.

Formula (10) Re2(550) is not less than 0nm and not more than 40nm

The Rth2(550) is more than or equal to 160nm and less than or equal to-40 nm in the formula (11).

In this embodiment, the 1 st optical compensation layer is disposed on the liquid crystal cell side, and the 2 nd optical compensation layer is disposed on the polarizer side.

More preferably, the 1 st optical compensation layer satisfies the following.

100nm≤Re1(550)≤150nm

50nm≤Rth1(550)≤120nm

The 1 st optical compensation layer can be obtained by: for example, a polymer film (for example, a cellulose acylate film, a cyclic polyolefin film, and a polycarbonate film) produced by an appropriate method such as a melt film-forming method and a solution film-forming method is subjected to a stretching treatment by a longitudinal stretching method based on circumferential speed control of a roller, a transverse stretching method based on a tenter, a biaxial stretching method, or the like. More specifically, reference can be made to the description of Japanese patent application laid-open No. 2005-338767. Further, a polymer formed from a liquid crystalline composition containing a liquid crystalline compound having a polymerizable group which exhibits biaxiality by alignment can also be used.

When the optical compensation layer is composed of 2 layers, the thickness of the 1 st optical compensation layer is preferably 1 to 80 μm, more preferably 1 to 40 μm, and particularly preferably 1 to 25 μm.

In the case where the optical compensation layer is composed of 2 layers, the 1 st optical compensation layer is preferably a positive a plate.

For example, the method of manufacturing the front a plate can be described in japanese patent application laid-open nos. 2008-225281 and 2008-026730.

In the present specification, the positive a plate is defined as follows. When the refractive index in the in-plane slow axis direction (the direction in which the in-plane refractive index is maximized) of the film is nx, the refractive index in the in-plane direction orthogonal to the in-plane slow axis is ny, and the refractive index in the thickness direction is nz, the positive a plate (positive a plate) satisfies the relationship of formula (a 1). In addition, Rth of the positive a plate shows a positive value.

Formula (A1) nx > ny ≈ nz

The term "substantially" as used herein includes not only the case where both are completely identical but also the case where both are substantially identical. The term "substantially the same" is included in "ny ≈ nz" even when (ny-nz). times.d (where d is the thickness of the thin film) is-10 to 10nm, preferably-5 to 5nm, for example.

And, according to the above definition, the positive a plate satisfies Nz ═ Rth (550)/Re (550) +0.5 ≈ 1.0.

The positive A plate is preferably a lambda/4 layer.

the λ/4 layer is a plate (retardation film) having an in-plane retardation Re (λ) at a specific wavelength λ nm satisfying Re (λ) ≈ λ/4.

In the formula, it can be achieved at any wavelength in the visible light region (for example, 550nm), but it is preferable that the in-plane retardation Re (550) at a wavelength of 550nm satisfies the relationship of 110 nm. ltoreq. Re (550). ltoreq.160 nm, and more preferably, 110 nm. ltoreq. Re (550). ltoreq.150 nm.

More preferably, the 2 nd optical compensation layer satisfies the following.

0nm≤Re2(550)≤20nm

-140nm≤Rth2(550)≤-80nm

It is preferable that the 2 nd optical compensation layer satisfy the requirement of formula (12) with respect to retardation in the thickness direction at a wavelength of 450nm Rth2(450) and retardation in the thickness direction at a wavelength of 550nm Rth2 (550).

The Rth2(450)/Rth2(550) of the formula (12) is less than or equal to 1.00.

The Rth2(450)/Rth2(550) is more preferably less than 0.95, and still more preferably 0.90 or less. The lower limit is not particularly limited, but is usually 0.75 or more.

The 2 nd optical compensation layer can be obtained by: the film is formed so as not to exhibit in-plane retardation of a polymer film (for example, a cellulose acylate film, a cyclic polyolefin film, and a polycarbonate film), and is stretched in the thickness (nz) direction using a heat-shrinkable film or the like.

Further, it is also possible to form a layer having a desired retardation by fixing the alignment state of the liquid crystalline compound. That is, the 2 nd optical compensation layer is preferably a film in which the liquid crystalline compound is immobilized in an aligned state, and more preferably a film in which the rod-like liquid crystalline compound is immobilized in a state in which the rod-like liquid crystalline compound is aligned in a direction perpendicular to the substrate surface.

As the liquid crystalline compound, a liquid crystalline compound exhibiting wavelength dispersibility of inverse dispersion is also preferably used. For example, a liquid crystalline compound showing wavelength dispersibility in reverse dispersion as described in WO2017/043438 pamphlet is mentioned.

The thickness of the 2 nd optical compensation layer is preferably 1 to 80 μm, more preferably 1 to 40 μm, and further preferably 1 to 25 μm.

The 2 nd optical compensation layer is preferably a positive C plate.

For example, the methods for producing the front C plate can be described in japanese patent application laid-open nos. 2017-187732, 2016-053709, and 2015-200861.

In the present specification, the positive C plate is defined as follows. The positive C plate (positive C plate) satisfies the relationship of formula (a2) where nx is the refractive index in the in-plane slow axis direction (the direction in which the in-plane refractive index is maximum) of the film, ny is the refractive index in the in-plane direction orthogonal to the in-plane slow axis, and nz is the refractive index in the thickness direction. In addition, Rth of the positive C plate shows a negative value.

formula (A2) nx ≈ ny < nz

The term "substantially" as used herein includes not only the case where both are completely identical but also the case where both are substantially identical. The term "substantially the same" is included in "nx ≈ ny" even when (nx-ny) × d (where d is the thickness of the thin film) is-10 to 10nm, preferably-5 to 5nm, for example.

In the positive C plate, Re ≈ 0 according to the above definition.

The optical compensation layer also preferably has a 2-layer structure including a cycloolefin polymer film and a film which is provided adjacent to the polymer film and is formed using a composition containing a liquid crystalline compound.

(polarizer)

The type of polarizer is not particularly limited, and may be a so-called linear polarizer having a function of converting natural light into specific linearly polarized light.

Examples of the polarizer include an absorption type polarizer, and more specifically, an iodine type polarizer, a dye type polarizer using a dichroic dye, and a polyene type polarizer.

The thickness of the polarizer is preferably 3 to 60 μm, more preferably 5 to 30 μm, and further preferably 5 to 15 μm.

(protective film)

The protective film is not particularly limited, and examples thereof include cellulose acylate films (e.g., cellulose triacetate film, cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), polyacrylic resin films such as polymethyl methacrylate, polyolefin films such as polyethylene and polypropylene, polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone film, polyurethane resin film, polyester film, polycarbonate film, polysulfone film, polyether film, polymethylpentene film, polyether ketone film, (meth) acrylonitrile film, cycloolefin polymer film (norbornene resin (ARTON: trade name, manufactured by JSR Corporation), and amorphous polyolefin (ZEONEX: trade name, manufactured by Zeon Corporation)). Among them, cellulose acylate films are preferable.

the optical properties of the protective film preferably satisfy the following formula.

0nm≤Re3(550)≤10nm

-40nm≤Rth3(550)≤40nm

In addition, as in the case of the protective film 10 shown in fig. 1, when the protective film is disposed between the polarizer and the liquid crystal cell, it is preferable to use a protective film having a substantially isotropic refractive index, and more specifically, it is preferable to satisfy the following expression.

0nm≤Re3(550)≤5nm

-10nm≤Rth3(550)≤10nm

an adhesive can be used for lamination of the polarizer and the optical compensation layer and lamination of the polarizer and the protective film. The thickness of the adhesive layer is preferably 0.01 to 30 μm, more preferably 0.01 to 10 μm, and still more preferably 0.05 to 5 μm.

Examples of the binder include water-based binders, i.e., binders in which a binder component is dissolved or dispersed in water, and polyvinyl alcohol-based binders are preferable. As the polyvinyl alcohol-based adhesive, an adhesive containing an aqueous solution of a polyvinyl alcohol-based resin is preferable.

Examples of the polyvinyl alcohol resin in the polyvinyl alcohol adhesive include, in addition to a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, a vinyl alcohol copolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith, and a modified polyvinyl alcohol polymer obtained by partially modifying hydroxyl groups of the copolymer.

The polyvinyl alcohol-based binder may further contain a polyaldehyde, a water-soluble epoxy compound, a melamine-based compound, a zirconium oxide compound, a zinc compound, a glyoxylate, or the like as a crosslinking agent.

In the case of using a polyvinyl alcohol-based adhesive, the thickness of the adhesive layer obtained therefrom is usually 1 μm or less.

Examples of the adhesive include a curable adhesive composition which is cured by irradiation with an active energy ray or heating. More specifically, examples thereof include a curable adhesive composition containing a cationically polymerizable compound and a curable adhesive composition containing a radically polymerizable compound, which are cured by irradiation with an active energy ray or heating. Examples of the cationically polymerizable compound include compounds having an epoxy group or an oxetanyl group. The epoxy compound is not particularly limited as long as it has at least 2 epoxy groups in the molecule, and examples thereof include those described in detail in Japanese patent laid-open No. 2004-24925.

The radical polymerizable compound is not particularly limited as long as it is a radical polymerizable compound having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and monofunctional radical polymerizable compounds, polyfunctional radical polymerizable compounds having 2 or more polymerizable groups in the molecule, hydroxyl group-containing (meth) acrylates, acrylamides, acryloylmorpholines, and the like can be used alone or in combination. For example, a compound described in detail in Japanese patent laid-open No. 2015-011094 can be used. Further, a radical polymerizable compound and a cation polymerizable compound can be combined and used.

in the case of using the curable adhesive composition, after a film is laminated by using a laminating roller, the film is dried as necessary, and the curable adhesive composition is cured by irradiation with an active energy ray or heating. The light source of the active energy ray is not particularly limited, but an active energy ray having an emission distribution under a wavelength of 400nm or less is preferable, and specifically, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, or a metal halide lamp is more preferable.

When the polarizer and the optical compensation layer or the protective film are bonded with an adhesive, the surface of the optical compensation layer or the protective film facing the polarizer may be subjected to a surface treatment (for example, glow discharge treatment, corona discharge treatment, or UV treatment) to improve the adhesion strength and the wettability of the adhesive, or an easy adhesion layer may be formed.

As the easy adhesion layer and the method for producing the same, reference can be made to the descriptions of japanese patent application laid-open nos. 2007-127893 and 2007-127893.