HK1142961B

HK1142961B - Liquid crystal display device

Info

Publication number: HK1142961B
Application number: HK10109208.7A
Authority: HK
Inventors: 大泽和彦; 吉田哲志
Original assignee: 卡西欧计算机株式会社
Priority date: 2007-01-26
Filing date: 2010-09-27
Publication date: 2012-06-01

Description

Liquid crystal display element

The invention is a divisional application of the following applications, and the original application information is as follows:

application date: 2007, 05 and 29 days

Application No.: 200710146448.4

The invention name is as follows: liquid crystal display element

Technical Field

The present invention relates to a TN (twisted nematic) liquid crystal display device.

Background

As a TN-mode liquid crystal display device, a liquid crystal display device is known which includes a liquid crystal cell having a liquid crystal layer in which liquid crystal molecules are twisted and aligned substantially at a twist angle of 90 ° and a pair of polarizing plates, the liquid crystal cell being interposed between a pair of substrates; the pair of polarizing plates are disposed so as to sandwich the liquid crystal cell; one of the pair of polarizing plates is arranged in a direction crossing at 45 ° parallel to the direction of alignment treatment of one substrate in the liquid crystal cell (japanese laid-open patent publication No. 2006-285220).

The liquid crystal display element can improve contrast and improve gray inversion in intermediate gray. In this liquid crystal display device, viewing angle compensation plates and retardation plates may be provided between the liquid crystal cell and the pair of polarizing plates, respectively, so that viewing angle characteristics can be improved.

However, the TN liquid crystal display element cannot sufficiently compensate for the viewing angle dependence of the transmittance, and cannot obtain sufficiently wide viewing angle characteristics.

Disclosure of Invention

The invention aims to provide a TN type liquid crystal display element with a wide viewing angle, which improves the angle dependence of transmittance.

In order to achieve the above object, a liquid crystal display element according to a first aspect of the present invention includes:

a liquid crystal cell configured by sandwiching a liquid crystal layer in which liquid crystal molecules are twisted and aligned substantially at 90 ° between a pair of substrates (substrates) each having at least 1 electrode and an alignment film covering the electrode formed on each of inner surfaces facing each other;

first and second polarizing plates disposed on both sides of the liquid crystal cell, each polarizing plate comprising a polarizing layer and at least 1 substrate supporting the polarizing layer, the polarizing layer having a transmission axis through which linearly polarized light is transmitted and an absorption axis in a direction perpendicular to the transmission axis; and

first and second viewing angle compensation layers respectively disposed between the liquid crystal cell and the first and second polarizing plates, each having a phase difference in a plane parallel to a substrate surface of the liquid crystal cell and a phase difference in a plane perpendicular to the substrate surface;

a total value of the retardation in the thickness direction, which is formed by a product of a phase difference in a plane perpendicular to the substrate surface and a layer thickness of each of the optical layers between the first polarizing layer and the second polarizing layer, including at least the first and second viewing angle compensating layers, and excluding the liquid crystal layer, is set to a value as follows: this value can cancel out the retardation in the thickness direction of the liquid crystal layer formed by the product of the in-plane phase difference of the liquid crystal layer perpendicular to the substrate surface and the thickness of the liquid crystal layer when a high voltage sufficient to cause the liquid crystal molecules to be oriented in an upright state with respect to the substrate surface is applied between the electrodes of the first and second substrates.

In addition, a liquid crystal display element according to a second aspect of the present invention includes:

a first substrate on one surface of which at least 1 first electrode and a first alignment film that is provided so as to cover the first electrode and is subjected to an alignment treatment in a predetermined first direction are formed;

a second substrate arranged to face the electrode formation surface of the first substrate, wherein at least 1 second electrode and a second alignment film are formed on the surface of the second substrate facing the first electrode, the second alignment film being provided so as to cover the second electrode and being subjected to an alignment treatment in a second direction intersecting the first direction at an angle of substantially 90 °;

a liquid crystal layer sandwiched between the first alignment film of the first substrate and the second alignment film of the second substrate, the liquid crystal molecules being twisted and aligned between the first alignment film and the second alignment film at a twist angle of substantially 90 °;

a first polarizing plate including a first polarizing layer provided so as to face an outer surface of the first substrate on the opposite side of the electrode formation surface and having an absorption axis in a direction substantially intersecting with an orientation treatment direction of the first alignment film at an angle of 45 °, and a base material made of a resin film provided on at least a surface of the first polarizing layer facing the first substrate and having a thickness direction retardation formed by a product of a phase difference and a layer thickness in a plane perpendicular to the substrate surfaces of the first and second substrates;

a second polarizing plate including a second polarizing layer and a base material made of a resin film, the second polarizing layer being disposed so as to face an outer surface of the second substrate on the opposite side of the electrode-formed surface and having an absorption axis in a direction substantially perpendicular to or substantially parallel to the absorption axis of the first polarizing layer, the base material being provided on at least a surface of the second polarizing layer facing the second substrate and having a thickness-direction retardation formed by a product of a phase difference and a layer thickness in a plane perpendicular to the substrate surface;

first and second viewing angle compensating plates disposed between the substrate 1 and the first polarizing plate and between the second substrate and the second polarizing plate, each having a viewing angle compensating layer having a phase difference in a plane parallel to the substrate surface and a phase difference in a plane perpendicular to the substrate surface and a base material made of a resin film, the base material being provided on at least one surface of the viewing angle compensating layer and having a thickness direction retardation formed by a product of the phase difference in the plane perpendicular to the substrate surface and a layer thickness;

a total value of a thickness direction retardation formed by a product of a phase difference in a plane perpendicular to the substrate surface of each of the plurality of optical layers and a thickness of each of the plurality of optical layers between the first polarizing layer of the first polarizing plate and the second polarizing layer of the second polarizing plate and a value of a liquid crystal layer thickness direction retardation formed by a product of a phase difference in a plane perpendicular to the substrate surface of the liquid crystal layer and a liquid crystal layer thickness when a high voltage sufficient to cause the liquid crystal molecules to be oriented in an upright state with respect to the substrate surface is applied between electrodes of the first and second substrates is set in a range of-80 nm to +80nm, and the plurality of optical layers include at least the substrate on a surface of the first and second polarizing plates facing the first and second substrates, each viewing angle compensating layer of the first and second viewing angle compensating plates, and the substrate of the first and second viewing angle compensating plates, and the above liquid crystal layer is excluded.

Further, a liquid crystal display device according to a third aspect of the present invention includes:

a first substrate having at least 1 first electrode and a first alignment film formed on one surface thereof and arranged to cover the first electrode and subjected to an alignment treatment in a predetermined first direction;

a second substrate provided so as to face the electrode formation surface of the first substrate, wherein at least 1 second electrode and a second alignment film are formed on the surface facing the first substrate, the second electrode facing the first electrode, and the second alignment film is provided so as to cover the second electrode and is subjected to an alignment treatment in a second direction that substantially intersects the first direction at an angle of 90 °;

a first polarizing layer disposed so as to face an outer surface of the first substrate on the opposite side of the electrode formation surface, the first polarizing layer having an absorption axis in a direction substantially intersecting with an orientation treatment direction of the first alignment film at an angle of 45 °;

a second polarizing layer that is disposed so as to face an outer surface of the second substrate on the opposite side of the electrode formation surface and has an absorption axis in a direction substantially perpendicular to or substantially parallel to the absorption axis of the first polarizing layer;

first and second viewing angle compensating layers respectively disposed between the first substrate and the first polarizing layer and between the second substrate and the second polarizing layer, each viewing angle compensating layer having a phase difference in a plane parallel to substrate surfaces of the first and second substrates and a phase difference in a plane perpendicular to the substrate surfaces;

in the case where one and the other of 2 mutually perpendicular directions in a plane parallel to the substrate surface are defined as an X axis and a Y axis, a thickness direction perpendicular to the substrate surface is defined as a Z axis, a refractive index in the X axis direction is defined as nx, a refractive index in the Y axis direction is defined as ny, a refractive index in the Z axis direction is defined as nz, a layer thickness of the optical layer is defined as d, a thickness direction retardation of each optical layer represented by { (nx + ny)/2-nz } dis defined as Rthi, a thickness direction retardation obtained by adding values of the thickness direction retardations Rthi of the optical layers is defined as Rth, and a product of a refractive index anisotropy Δ n of a liquid crystal material constituting the liquid crystal layer and a liquid crystal layer thickness d is defined as Δ nd, for each of the plurality of optical layers other than the liquid crystal layer, the plurality of optical layers including at least the first and second viewing angle compensation layers being disposed between the first polarizing layer and the second polarizing layer, the above thickness direction retardation Rth is set in a range satisfying-80 nm < Rth-0.83. delta. nd < 80 nm.

A liquid crystal display element, comprising: a first polarizing layer (12) and a second polarizing layer (16), the transmission axis of the first polarizing layer (12) and the transmission axis of the second polarizing layer (16) being perpendicular to each other; a liquid crystal cell (1) disposed between the first polarizing layer (12) and the second polarizing layer (16); a first viewing angle compensation plate (19) disposed between the first polarizing layer (12) and the liquid crystal cell (1); a second viewing angle compensation plate (22) disposed between the second polarizing layer (16) and the liquid crystal cell (1); a first base material (14) that is disposed between the first polarizing layer (12) and the first viewing angle compensating plate (19), and supports the first polarizing layer (12); and a second base (18) that is disposed between the second polarizing layer (16) and the second viewing angle compensating plate (22), and supports the second polarizing layer (16), wherein the liquid crystal cell (1) includes: a first substrate (2) on which a first electrode (4) is formed; a second substrate (3) on which a second electrode (5) is formed; and a liquid crystal layer (10) disposed between the first electrode (4) and the second electrode (5), wherein the liquid crystal layer (10) is twisted and oriented at a twist angle of 90 DEG when no voltage is applied between the first electrode (4) and the second electrode (5), and wherein retardation remaining in the substrate surface in the liquid crystal layer (10) when a predetermined saturation voltage is applied between the first electrode (4) and the second electrode (5), wherein the total value of retardation in a surface perpendicular to the substrate surface of each optical layer disposed between the first polarizing layer (12) and the liquid crystal cell (1) and retardation in each optical layer disposed between the second polarizing layer (16) and the liquid crystal cell (1) is set to be equal to, The retardation value of the liquid crystal layer (10) in a plane perpendicular to the substrate surface is of the opposite value.

According to the liquid crystal display element of the above aspects of the present invention, the angle dependence of the transmittance can be improved, and display with a wide viewing angle can be performed.

Description of the drawings:

fig. 1 is a schematic cross-sectional view showing a liquid crystal display element according to a first embodiment of the present invention;

FIG. 2 is an enlarged cross-sectional view of a portion of a liquid crystal cell;

fig. 3 is an enlarged sectional view of a part of the viewing angle compensating plate;

fig. 4 is a view showing the alignment treatment direction of the first and second alignment films, the direction of the absorption axes of the first and second polarizing layers, and the direction of the optical axes of the first and second viewing angle compensating layers in the first embodiment;

FIG. 5The thickness d of the liquid crystal layer in each pixel portion of red, green and blue colors in the liquid crystal display element of the first embodiment is shown_R、d_G、d_BA graph of the ratio of (a) to (b) and a relation between display chromaticity when white is displayed;

FIG. 6 shows Δ nd of the liquid crystal layer of the liquid crystal display element of the first embodiment, and a retardation Rth in the thickness direction of the liquid crystal layer when a saturation voltage is applied_LCA graph of the relationship of (a);

fig. 7 is a view showing the relationship between the in-plane retardation Ro, which is the sum of the in-plane retardation values of the substrates of the plurality of optical layers other than the liquid crystal layer between the first polarizing layer and the second polarizing layer of the liquid crystal display element of the first embodiment, and Δ nd of the liquid crystal layer and the transmittance;

FIGS. 8A to 8D show a white display T in the liquid crystal display device of the first embodiment_WBlack display T_BT is displayed in 50% gray scale (gray scale of 50% of brightness in white display)₅₀And a 20% gradation (gradation of 20% of luminance in white display) display T₂₀A time field angle characteristic diagram;

FIG. 9 shows a white display T in each of the liquid crystal display elements according to the modified example of the first embodiment_WBlack display T_BT is displayed in 50% gray scale (gray scale of 50% of brightness in white display)₅₀And a 20% gradation (gradation of 20% of brightness in white display) display T₂₀A time field angle characteristic diagram;

fig. 10 is a schematic cross-sectional view showing a liquid crystal display element according to a second embodiment of the present invention;

fig. 11 is a view showing the alignment treatment direction of the first and second alignment films, the direction of the absorption axes of the first and second polarizing layers, the direction of the optical axes of the first and second viewing angle compensating layers, and the direction of the slow axis of the first and second phase plates in the liquid crystal display device according to the second embodiment;

FIGS. 12A to 12D are views showing a liquid crystal display element according to a second embodimentDisplaying T separately in white_WBlack display T_BT is displayed in 50% gray scale (gray scale of 50% of brightness in white display)₅₀And a 20% gradation (gradation of 20% of luminance in white display) display T₂₀A time field angle characteristic diagram;

fig. 13 is a schematic cross-sectional view showing a liquid crystal display element according to a third embodiment of the present invention;

fig. 14 is a perspective view for explaining characteristics of an optical film in a liquid crystal display element;

fig. 15 is a view showing the alignment treatment direction of the first and second alignment films, the direction of the absorption axes of the first and second polarizing layers, the direction of the optical axes of the first and second viewing angle compensating layers, the direction of the slow axis of the first and second phase plates, and the direction of the optical axes of the first and second optical films of the liquid crystal display device according to the third embodiment;

FIGS. 16A to 16D show a white display T in the liquid crystal display device of the third embodiment_WBlack display T_BT is displayed in 50% gray scale (gray scale of 50% of brightness in white display)₅₀And a 20% gradation (gradation of 20% of luminance in white display) display T₂₀A time field angle characteristic diagram;

fig. 17 is a schematic cross-sectional view showing a liquid crystal display element according to a fourth embodiment of the present invention;

fig. 18 is a view showing the alignment treatment direction of the first and second alignment films, the direction of the absorption axes of the first and second polarizing layers, the direction of the optical axes of the first and second viewing angle compensating layers, the direction of the slow axis of the first and second phase plates, and the direction of the optical axis of the optical film in the liquid crystal display device according to the fourth embodiment;

FIGS. 19A to 19D show a white display T in the liquid crystal display device of the fourth embodiment_WBlack display T_BT is displayed in 50% gray scale (gray scale of 50% of brightness in white display)₅₀And 20% gray (20% of white display)Gradation of luminance) display T₂₀A time field angle characteristic diagram;

FIG. 20 is a schematic sectional view showing a liquid crystal display device according to embodiment 5 of the present invention;

fig. 21 is a view showing the alignment treatment direction of the first and second alignment films, the direction of the absorption axes of the first and second polarizing layers, the direction of the optical axes of the first and second viewing angle compensating layers, and the direction of the slow axis of the first and second phase plates according to example 5;

FIGS. 22A to 22D show a white display T in the liquid crystal display device of example 5_WBlack display T_BT is displayed in 50% gray scale (gray scale of 50% of brightness in white display)₅₀And a 20% gradation (gradation of 20% of luminance in white display) display T₂₀A time field angle characteristic diagram;

FIG. 23 is a schematic sectional view showing a liquid crystal display device according to embodiment 6 of the invention;

fig. 24 is a view showing the alignment treatment direction of the first and second alignment films, the direction of the absorption axes of the first and second polarizing layers, the direction of the optical axes of the first and second viewing angle compensating layers, and the direction of the slow axis of the first and second phase plates in the liquid crystal display device according to example 6;

FIGS. 25A to 25D show a white display T in the liquid crystal display device of example 6_WBlack display T_BT is displayed in 50% gray scale (gray scale of 50% of brightness in white display)₅₀And a 20% gradation (gradation of 20% of luminance in white display) display T₂₀A time field angle characteristic diagram;

fig. 26 is a schematic sectional view showing a liquid crystal display element according to embodiment 7 of the present invention;

fig. 27 is a view showing the alignment treatment direction of the first and second alignment films, the direction of the absorption axes of the first and second polarizing layers, the direction of the optical axes of the first and second viewing angle compensating layers, and the direction of the slow axis of the first and second phase plates in the liquid crystal display device according to example 7;

FIGS. 28A to 28D show a white display T in the liquid crystal display device of example 7_WBlack display T_BT is displayed in 50% gray scale (gray scale of 50% of brightness in white display)₅₀And a 20% gradation (gradation of 20% of luminance in white display) display T₂₀View angle characteristic diagram of time.

Detailed Description

(first embodiment)

Fig. 1 to 8 show a first embodiment of the present invention, and fig. 1 is a schematic sectional view of a liquid crystal display device.

The liquid crystal display element is a TN type liquid crystal display element, and includes: a liquid crystal cell 1 in which a nematic liquid crystal layer 10 in which liquid crystal molecules are twisted and aligned at a twist angle of substantially 90 ° is sandwiched between a pair of transparent substrates 2 and 3; a pair of first and second polarizing plates 11 and 15 disposed so as to sandwich the liquid crystal cell 1; and first and second viewing angle compensation plates 19 and 22 respectively provided between the liquid crystal cell 1 and the pair of polarizing plates 11 and 15.

Fig. 2 is an enlarged cross-sectional view of a part of the liquid crystal cell 1. The liquid crystal cell 1 includes a first substrate 2, a second substrate 3 disposed to face the first substrate 2, and a liquid crystal layer 10 disposed between the first and second substrates 2 and 3. In the first substrate 2, at least 1 first transparent electrode 4 and a first alignment film 7 are formed on one surface, and the first alignment film 7 is provided so as to cover the first electrode 4 and subjected to an alignment treatment in a predetermined first direction. The second substrate 3 is provided so as to face the electrode formation surface of the first substrate 2, and at least 1 second transparent electrode 5 and a second alignment film 8 are formed on the surface facing the first substrate 2 so as to face the first electrode 4, and the second alignment film 8 is provided so as to cover the second electrode and subjected to alignment treatment in a second direction substantially intersecting the first direction at an angle of 90 °. The liquid crystal layer 10 is sandwiched between the first alignment film 7 and the second alignment film 8, and the liquid crystal molecules 10a are twisted and aligned at a twist angle of substantially 90 ° between the first alignment film 7 and the second alignment film 8. The liquid crystal layer 10 rotates polarized light incident in an initial alignment state of twist alignment by 90 °. The liquid crystal layer 10 is observed based on the alignment state of the liquid crystal molecules 10a, and the retardation value with respect to the transmitted light substantially changes within a range of λ/2.

The liquid crystal cell 1 is an active matrix liquid crystal cell, and the electrode 4 provided on the substrate (hereinafter referred to as "rear substrate") 2 on the opposite side of the first and second substrates 2 and 3 from the observation side of display is constituted by a plurality of pixel electrodes formed in a matrix arrangement in the row direction (left-right direction of the screen) and the column direction (left-right direction of the screen). The electrode 5 provided on the other substrate (hereinafter referred to as "front substrate") 3 on the observation side is a single film-like counter electrode formed to face the entire region of the arrangement region of the plurality of pixel electrodes 4.

Although not shown in fig. 2, a plurality of TFTs (thin film transistors) provided corresponding to the plurality of pixel electrodes 4, respectively, a plurality of scanning lines for supplying gate signals to the plurality of TFTs in each row, and a plurality of signal lines for supplying data signals to the plurality of TFTs in each column are provided on the surface of the rear substrate 2 facing the front substrate 3.

The TFT includes a gate electrode formed on the rear substrate 2, a gate insulating film formed to cover the gate electrode, and an i-type semiconductor film formed on the gate insulating film to face the gate electrode; and a drain electrode and a source electrode formed on both side portions of the i-type semiconductor film with the n-type semiconductor film interposed therebetween. The gate electrode is connected to the scanning line, the drain electrode is connected to the signal line, and the source electrode is connected to the corresponding pixel electrode 4.

On the surface of the front substrate 3 facing the rear substrate 2, color filters 6R, 6G, and 6B of 3 colors of red, green, and blue are formed corresponding to the plurality of pixels formed by the regions where the plurality of pixel electrodes 4 and the counter electrode 5 face each other, respectively, and the counter electrode 5 is formed so as to cover the color filters 6R, 6G, and 6B.

The pair of substrates 2 and 3 are opposed to each other with a predetermined gap therebetween, and are bonded to each other with a frame-shaped sealing material 9 (see fig. 1) formed to surround the arrangement region of the plurality of pixel electrodes 4. The liquid crystal layer 10 is sealed in a region surrounded by the sealing material 9 between the pair of substrates 2 and 3.

In the color filters 6R, 6G, and 6B of 3 colors of red, green, and blue, the liquid crystal layer thickness d of the pixel in which the red filter 6R is provided is set to be equal to each of the plurality of pixels_RAnd a liquid crystal layer thickness d of the pixel having the green filter 6G_GAnd a liquid crystal layer thickness d of the pixel provided with the blue filter 6R_BIs formed as d_R＞d_G＞d_BIn the relationship of (1), the green filter 6G is formed to have a larger thickness than the red filter 6R, and the blue filter 6B is formed to have a larger thickness than the green filter 6G.

The liquid crystal layer thickness d of the pixel provided with the red filter 6R_RAnd a liquid crystal layer thickness d of the pixel having the green filter 6G_GAnd a liquid crystal layer thickness d of the pixel provided with the blue filter 6B_BIs set to d_R∶d_G∶d_B＝1.1∶1.0∶0.9。

Further, of the pair of polarizing plates disposed so as to sandwich the liquid crystal cell 1, the first polarizing plate 11 disposed so as to face the outer surface of the liquid crystal cell 1 on the opposite side to the electrode formation surface of the rear substrate 2 is disposed so that the absorption axis thereof is oriented in a direction substantially intersecting the alignment treatment direction of the first alignment film 7 formed on the rear substrate 2 at an angle of 45 °. The second polarizing plate 15 disposed to face the outer surface of the liquid crystal cell 1 on the opposite side of the electrode formation surface of the front substrate 3 is disposed so that the absorption axis thereof is oriented in a direction substantially intersecting the alignment treatment direction of the second alignment film 8 formed on the front substrate 3 at an angle of 45 °. That is, the absorption axes of the first polarizing plate 11 and the second polarizing plate 15 are perpendicular to each other.

The first polarizing plate 11 is composed of a first polarizing layer 12 and a pair of substrates 13 and 14, the first polarizing layer 12 having an absorption axis in a direction substantially intersecting the orientation treatment direction of the first orientation film 7 at an angle of 45 °, the pair of substrates 13 and 14 being formed of a transparent resin film such as TAC (triacetyl cellulose) film or the like, and being provided on both surfaces thereof with the first polarizing layer 12 interposed therebetween, and having a phase difference in a plane parallel to the substrate surfaces of the pair of substrates 2 and 3 of substantially zero and a phase difference in a plane perpendicular to the substrates of the pair of substrates 2 and 3 (hereinafter referred to as "phase difference in the thickness direction"). The second polarizing plate 15 is composed of a first polarizing layer 16 and a pair of substrates 17 and 18, the first polarizing layer 16 has an absorption axis in a direction substantially intersecting with the orientation treatment direction of the second orientation film 8 formed on the front substrate 3 at an angle of 45 °, the pair of substrates 17 and 18 are formed of a transparent resin film such as TAC film and are provided on both surfaces thereof with the second polarizing layer 16 interposed therebetween, and the retardation in a plane parallel to the substrate surface is substantially zero and has the retardation in a plane perpendicular to the substrate surface (retardation in the thickness direction).

The first and second viewing angle compensating plates 19 and 22 provided between the Liquid Crystal cell 1 and the pair of polarizing plates 11 and 15 are each formed of a viewing angle compensating layer 20 or 23 and a pair of substrates 21 and 24, the viewing angle compensating layers 20 and 23 are each formed of a Discotic Liquid Crystal (Discotic Liquid Crystal) layer in which nematic Liquid Crystal molecules are mixedly aligned, and the pair of substrates 21 and 24 are each formed of a transparent resin film such as the TAC film and provided on at least one surface of the viewing angle compensating layers 20 and 23. The viewing angle compensating layers 20 and 23 have a phase difference in a plane parallel to the substrate surface and a phase difference in a plane perpendicular to the substrate surface (phase difference in the thickness direction), respectively. The pair of substrates 21 and 24 have substantially zero phase difference in a plane parallel to the substrate surface and have a phase difference in a plane perpendicular to the substrate surface (phase difference in the thickness direction).

The first and second viewing angle compensating plates 19 and 22 used in the present embodiment are each provided with the base materials 21 and 24 on one surface of the viewing angle compensating layers 22 and 23.

Fig. 3 is an enlarged cross-sectional view of a part of the first and second viewing angle compensating plates 19 and 22, in which the viewing angle compensating plates 19 and 22 are formed with alignment films 21a and 24a on one surface of the substrates 21 and 24, respectively, and the alignment films 21a and 24a are provided with viewing angle compensating layers 20 and 23 formed of discotic liquid crystal layers. The discotic liquid crystal layer has a molecular axis perpendicular to the discotic surface of the discotic liquid crystal molecules 25 on a plane perpendicular to the film surface of the substrate 21 and parallel to the orientation treatment direction of the orientation film 21a, and the discotic liquid crystal molecules 25 are mixedly oriented so that the tilt angle (tilt angle) with respect to the substrate 21 increases from the substrate 21 side toward the opposite side.

The viewing angle compensating layers 20 and 23 of the first and second viewing angle compensating plates 19 and 22 have negative optical anisotropy in which the refractive index is the smallest in the average tilt direction of the molecular axes on the surface where the molecular axes of the hybrid aligned discotic liquid crystal molecules 25 are located. Here, a line in which a plane on which the molecular axis of the discotic liquid crystal molecules 25 is located and the planes of the viewing angle compensating layers 20 and 23 intersect is referred to as an optical axis direction.

In the first viewing angle compensating plate 19, the surface of the first viewing angle compensating layer 20 on the side where the tilt angle of the discotic liquid crystal molecules 25 is large (the surface on the opposite side to the substrate 21 side) is provided to face the outer surface of the rear substrate 2 in the liquid crystal cell 1. The optical axis direction of the first viewing angle compensating layer 20 is set to be parallel to a direction substantially parallel to the alignment treatment direction of the first alignment film 7 formed on the rear substrate 2 or a direction substantially perpendicular thereto. In the second viewing angle compensating plate 22, the surface of the second viewing angle compensating layer 23 on the side where the tilt angle of the discotic liquid crystal molecules is large (the surface on the opposite side to the substrate 24 side) is provided to face the outer surface of the front substrate 3 of the liquid crystal cell 1. The optical axis direction of the second viewing angle compensating layer 23 is set to be parallel to a direction substantially parallel to the alignment treatment direction of the second alignment film 8 formed on the front substrate 3 or substantially perpendicular to the same.

Fig. 4 shows the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1, the directions of the absorption layers 12a and 16a of the polarizing layers 12 and 16 of the first and second polarizing plates 11 and 15, and the directions of the optical axis directions 20a and 23a of the viewing angle compensating layers 20 and 23 of the first and second viewing angle compensating plates 19 and 22.

As shown in fig. 4, the first alignment film 7 formed on the rear substrate 2 of the liquid crystal cell 1 is subjected to alignment treatment in a first direction in which a rightward direction viewed from the observation side intersects a transverse axis direction (a direction indicated by a chain line in the drawing) of a screen of the liquid crystal display element at an angle of substantially 45 °. The second alignment film 8 formed on the front substrate 3 is subjected to alignment treatment in a second direction (a direction in which a left-hand direction intersects a horizontal axis direction of the screen at an angle of substantially 45 ° when viewed from the observation side) which substantially intersects the first direction at an angle of 90 °. The liquid crystal molecules 10a of the liquid crystal layer 10 sandwiched between the first alignment film 7 of the rear substrate 2 and the second alignment film 8 of the front substrate 3 are twisted and aligned at a twist angle of substantially 90 ° in the layer thickness direction of the liquid crystal layer 10 between the first alignment film 7 and the second alignment film 8, as indicated by a broken line arrow indicating the twist direction of the molecular alignment.

The retardation value of the liquid crystal layer 10 of the liquid crystal cell 1 changes substantially within a range of λ/2 with respect to the transmitted light in accordance with the alignment state of the liquid crystal molecules 10a which changes in accordance with the voltage applied between the electrodes 4, 5 of the pair of substrates 2, 3.

In the first polarizing plate 11 facing the outer surface of the rear substrate 2 in the liquid crystal cell 1, the absorption axis 12a of the first polarizing layer 12 of the polarizing plate 11 is arranged in a direction parallel to the transverse axis direction of the screen as viewed from the observation side, that is, in a direction crossing the alignment treatment direction 7a of the first alignment film 7 of the rear substrate 2 at an angle of substantially 45 ° in a leftward direction as viewed from the observation side. In the second polarizing plate 15 facing the outer surface of the front substrate 3 in the liquid crystal cell 1, the absorption axis 16a of the second polarizing layer 16 of the polarizing plate 15 is arranged in parallel to the direction substantially perpendicular to the absorption axis 12a of the polarizing layer 12 of the first polarizing plate 11 (direction substantially perpendicular to the transverse axis direction of the screen).

In the first viewing angle compensating plate 19 between the rear substrate 2 of the liquid crystal cell 1 and the first polarizing plate 11, the optical axis direction 20a of the first viewing angle compensating layer 20 of the viewing angle compensating plate 19 is arranged in a direction substantially parallel to the alignment treatment direction 7a of the first alignment film 7 of the rear substrate 2. In the second viewing angle compensating plate 22 between the front substrate 3 of the liquid crystal cell 1 and the second polarizing plate 15, the optical axis direction 23a of the second viewing angle compensating layer 23 of the viewing angle compensating plate 22 is arranged in a direction substantially parallel to the alignment treatment direction 8a of the second alignment film 8 of the front substrate 3, that is, in a direction substantially perpendicular to the optical axis direction 20a of the viewing angle compensating layer 20 of the first viewing angle compensating plate 19.

In the liquid crystal display device, a voltage is applied between the electrodes 4 and 5 to control transmission of white illumination light emitted from a surface light source (not shown) provided on the rear side (the side opposite to the observation side) of each of the plurality of pixel portions, and red, green, and blue 3-color light colored by the red, green, and blue 3-color filters 6R, 6G, and 6B corresponding to the plurality of pixel portions is emitted to the observation side, thereby displaying a color image.

In this liquid crystal display element, the liquid crystal layer thickness d of the pixel portion (hereinafter referred to as red pixel portion) of the liquid crystal cell 1 provided with the red filter 6R is set to be larger than the liquid crystal layer thickness d of the pixel portion_RAnd a liquid crystal layer thickness d of a pixel portion (hereinafter referred to as a green pixel portion) provided with the green filter 6G_GAnd a pixel portion provided with a blue filter 6B (hereinafter referred to as blue image)Pixel portion) of the liquid crystal layer thickness d_RIs set as d_R∶d_G∶d_B1.1: 1.0: 0.9, and therefore, a color image with good color balance can be displayed.

That is, fig. 5 shows the liquid crystal layer thickness d of the pixel portion of each of the red, green, and blue colors_R∶d_G∶d_BThe ratio of (a) to (b) and the chromaticity of display when light is emitted from each pixel of red, green, and blue to display white.

As shown in FIG. 5, the liquid crystal layer thicknesses d of the pixel portions for red, green and blue colors are compared_R、d_G、d_BIs set as d_R∶d_G∶d_B＝0.9∶1.0∶1.1，d_R∶d_G∶d_B＝1.0∶1.0∶1.0，d_R∶d_G∶d_BIn the case of 3 systems of 1.1: 1.0: 0.9, the liquid crystal layer thickness d of the pixel portion of each color is set to be 1.1: 1.0: 0.9_R、d_G、d_BIs set as d_R∶d_G∶d_BChromaticity of white display at 1.1: 1.0: 0.9, and liquid crystal layer thickness d_R、d_G、d_BThe chromaticity comparison of the white display when the ratio of (a) is set to another value is close to the chromaticity of the light source light (white illumination light from the surface light source), and therefore, a color image with good color balance can be displayed.

In the liquid crystal display device, the first polarizing plate 11 and the second polarizing plate 15 are arranged in a normally white type in which the absorption axes 12a and 16a of the polarizing layers 12 and 16 are substantially perpendicular to each other, and when no voltage is applied between the electrodes 4 and 5 of each pixel, white is displayed, and when a high voltage (referred to as a saturation voltage) sufficient to vertically align substantially the entire liquid crystal molecules 10a in the thickness direction of the liquid crystal layer 10 with respect to the substrate surface is applied between the electrodes 4 and 5 of each pixel, black is displayed.

The liquid crystal cell 1 includes a liquid crystal layer 10 in which liquid crystal molecules 10a are twisted and aligned between a pair of substrates 2 and 3 at a twist angle of substantially 90 °, and the behavior of the liquid crystal molecules 10a in the vicinity of the pair of substrates 2 and 3 of the liquid crystal layer 10 is suppressed by an anchoring effect of the alignment films 7 and 8. Accordingly, when the saturation voltage is applied between the electrodes 4 and 5, the liquid crystal molecules 10a near the pair of substrates 2 and 3 are not aligned vertically, and an in-plane retardation (hereinafter referred to as a residual retardation) of the liquid crystal molecules 10a near the substrates 2 and 3 of the liquid crystal layer 10 is present.

When the saturation voltage is applied between the electrodes 4 and 5, the liquid crystal layer 10 has a negative phase difference in a plane perpendicular to the substrate surface (hereinafter referred to as a phase difference in a liquid crystal layer thickness direction).

In particular, the absorption axes 12a and 16a of the polarizing layers 12 and 16 of the first and second polarizing plates 11 and 15 are arranged in the liquid crystal display element substantially parallel to the alignment treatment directions 7a and 8a of the alignment films 7 and 8 at 45 °, and the retardation in the liquid crystal layer thickness direction greatly acts on light obliquely incident on the substrate surface, thereby degrading the viewing angle characteristics.

In the liquid crystal display device of the present embodiment, the first and second viewing angle compensating plates 19 and 22 are disposed between the first and second polarizing plates 11 and 15 disposed in front and rear of the liquid crystal cell 1 and the rear substrate 2 and the front substrate 3 of the liquid crystal cell 1, respectively, and the residual retardation is cancelled by the first and second viewing angle compensating plates 19 and 22. Further, a phase difference in a plane perpendicular to the substrate surface of the liquid crystal layer 10 when the saturation voltage (a high voltage sufficient to cause the liquid crystal molecules 10a to be vertically aligned) is applied between the electrodes 4 and 5 of the liquid crystal cell 1 is offset by a phase difference in a plane perpendicular to the substrate surface of each of a plurality of optical layers between the first polarizing layer 12 of the first polarizing plate 11 and the second polarizing layer 16 of the second polarizing plate 15, the plurality of optical layers including: substrates 14 and 18 on the surfaces of the first and second polarizing plates 11 and 15 facing the liquid crystal cell 1; the viewing angle compensation layers 20 and 23 of the first and second viewing angle compensation plates 19 and 22; and base materials 21 and 24 of the first and second viewing angle compensation plates 19 and 22.

That is, the phase difference in the liquid crystal layer thickness direction of the liquid crystal layer 10 and the liquid crystal layer thickness (the liquid crystal layer thickness d of the pixel portion of each color of the red, green, and blue color filters 6R, 6G, and 6B) are set to be equal to each other_R、d_G、d_BThe average value of (d) is defined as a liquid crystal layer thickness direction retardation, and when the value of the product of the phase difference in the thickness direction of each of the plurality of optical layers and the thickness of each layer is defined as a thickness direction retardation, the total value of the liquid crystal layer thickness direction retardation and the thickness direction retardation of the plurality of optical layers is set to a range of-80 nm to +80nm (0 ± 80nm), preferably 0nm, thereby canceling the retardation in the thickness direction of the liquid crystal layer 10 when the saturation voltage is applied.

FIG. 6 shows a product Δ nd of refractive index anisotropy Δ n and liquid crystal layer thickness d of a liquid crystal material constituting the liquid crystal layer 10 and a liquid crystal layer thickness Rth in the liquid crystal layer thickness direction of the liquid crystal layer 10 when the pretilt angle of the liquid crystal molecules 10a is 5.5 ° and the saturation voltage is 4V, respectively_LCThe relationship between them. A liquid crystal layer thickness direction retardation Rth of the liquid crystal layer 10 when the saturation voltage is applied_LCThe value of the product Δ nd of the liquid crystal layer 10 changes as shown in the figure. Namely, retardation Rth in the thickness direction of the liquid crystal layer_LCThe change in the value of the product Δ nd with respect to the liquid crystal layer 10 changes linearly. Thus, the retardation Rth_LCIt can be obtained by multiplying a coefficient corresponding to the slope of the straight line shown in fig. 6 by the value of the product Δ nd of the liquid crystal layer 10.

Then, the total absolute value of the retardation values in the thickness direction of each of the plurality of optical layers other than the liquid crystal layer 10 between the first polarizing layer 12 of the first polarizing plate 11 and the second polarizing layer 16 of the second polarizing plate 15 is set to be equal to the absolute value of Δ nd of the liquid crystal layer 10 multiplied by a coefficient preset from the pretilt angle of the liquid crystal molecules 10a and the saturation voltage, or the difference between the absolute values is set to be in the range of-80 nm to +80 nm.

The followingTable 1 shows the liquid crystal layer direction retardation Rth of the liquid crystal layer 10 in which the pretilt angle and the saturation voltage of the liquid crystal molecules 10a are different_LCAnd a coefficient value obtained by multiplying a value of Δ nd of the liquid crystal layer to calculate a value of retardation in the thickness direction of each of the plurality of optical layers.

TABLE 1

Pretilt angle	Saturation voltage	Rth_LC	Coefficient of performance
				0.5°	3V	-299.43	0.72
5.5°	3V	-311.03	0.75
				10.5°	3V	-321.85	0.77
0.5°	4V	-338.46	0.81
				5.5°	4V	-345.40	0.83
10.5°	4V	-352.11	0.85
				0.5°	5V	-358.35	0.86
5.5°	5V	-363.41	0.87
				10.5°	5V	-368.32	0.86

As shown in table 1, the pretilt angle of the liquid crystal molecules 10a is in the range of 0.5 ° to 10.5 ° and the saturation voltage is in the range of 3V to 5V, and the retardation value in the liquid crystal layer thickness direction of the liquid crystal layer 10 when the saturation voltage is applied can be calculated by multiplying a coefficient in the range of 0.72 to 0.86 by the value Δ nd of the liquid crystal layer. Here, the value of the liquid crystal layer thickness direction retardation of the liquid crystal layer 10 when the saturation voltage is applied and the total value of the thickness direction retardations of the plurality of optical layers other than the liquid crystal layer 10 are values that are substantially equal in absolute value and opposite in positive and negative.

Thus, in the present embodiment, the total value of the retardation in the thickness direction of each of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 other than the liquid crystal layer 10 is set to a value obtained by multiplying the value Δ nd of the liquid crystal layer 10 by a coefficient in the range of 0.72 to 0.86, and the total value of the retardation in the thickness direction of each of the plurality of optical layers other than the liquid crystal layer 10 and the retardation in the thickness direction of the liquid crystal layer 10 when the saturation voltage is applied is in the range of 0 ± 80nm (-80nm to +80 nm). In this case, it is preferable that the value of the retardation in the liquid crystal layer thickness direction of the liquid crystal layer 10 when the saturation voltage is applied is a value calculated by multiplying a value Δ nd of the liquid crystal layer 10 by a coefficient of 0.83.

Fig. 7 shows the transmittance of the liquid crystal display element with respect to the total value Ro + Δ nd of the product Δ nd of the in-plane retardation Ro obtained by adding the values of the in-plane retardations of the plurality of optical layers other than the liquid crystal layer 10 between the first polarizing layer 12 of the first polarizing plate 11 and the second polarizing layer of the second polarizing plate of the liquid crystal layer display element and the liquid crystal layer 10. The plurality of optical layers include: substrates 14 and 18 on the surfaces facing the liquid crystal cell 1 of the first and second polarizing plates 11 and 15, viewing angle compensating layers 20 and 23 of the first and second viewing angle compensating plates 19 and 22, and substrates 21 and 24 of the first and second viewing angle compensating plates 19 and 22. The liquid crystal display element exhibits a high transmittance in the range of 350nm to 600nm at a value of Ro + Δ nd, and particularly exhibits a peak at a value of 480nm at a value of Ro + Δ nd.

In the present embodiment, the total value of in-plane retardations, which is the product of the in-plane retardation on the surface parallel to the substrate surface and the layer thickness of the optical layer, of each of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 is added to Δ nd of the liquid crystal layer 10, and the sum is preferably set to be in the range of 350 to 600nm, more preferably 480 nm.

In addition, if specifically described, in the liquid crystal display element of the present embodiment, the optical functions of the respective substrates 13 and 17 located outside the first and second polarizing layers 12 and 16 of the first and second polarizing plates 11 and 15 are not related to the visibility of the observer. Also, the visibility of the observer is related to a plurality of optical layers including the substrates 14 and 18 of the first and second polarizing plates 11 and 15, the first and 2 viewing angle compensating layers 20 and 23 of the first and second viewing angle compensating plates 19 and 22, the substrates 21 and 24 thereof, and the liquid crystal layer 10 between the first polarizing layer 12 and the second polarizing layer 16.

As shown in FIG. 14 showing X, Y, the Z coordinate of the optical medium 100 and the refractive index in each coordinate axis direction thereof, in each of the plurality of optical layers as the optical medium 100, one and the other of 2 directions perpendicular to each other on a plane parallel to the substrate surface are respectively defined as an X axis and a Y axis, the thickness direction perpendicular to the substrate surface is defined as a Z axis, the refractive index in the X axis direction is nx, the refractive index in the Y axis direction is ny, the refractive index in the Z axis direction is nz, the layer thickness of the optical layer is d, and the thickness direction retardation Rthi of each optical layer is represented by { (nx + ny)/2-nz } d. When a total thickness direction retardation obtained by adding values of the retardations Rthi in the thickness direction of the respective optical layers is Rth and a product of a refractive index anisotropy Δ n of a liquid crystal material constituting the liquid crystal layer 10 and an average liquid crystal layer thickness d is Δ nd, the total thickness direction retardation Rth is set so as to satisfy:

Rth＝0.83Δnd±8nm

the range of (1). That is, the total thickness direction retardation Rth is set in the range of 0.83. DELTA. nd-80nm to 0.83. DELTA. nd +80 nm.

In addition, when the in-plane retardation of each optical layer represented by (nx-ny) · d is Roi and the in-plane retardation added by the value of the in-plane retardation Roi of each optical layer is Ro in a plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16, the added in-plane retardation Ro is set to satisfy:

Ro+Δnd＝350nm～600nm

within the range of (1).

In the liquid crystal display device of the present embodiment, Δ nd of the liquid crystal layer 10 of the liquid crystal cell 1 is 380nm, the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second viewing angle compensation layers 20 and 23 are respectively Rthi 70nm and Roi 47nm, and the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the substrates 14 and 18 on the surfaces facing the liquid crystal cell 1 of the first and second polarizing layers 16 and the substrates 21 and 24 of the first and second viewing angle compensation layers 20 and 23 are respectively Rthi 89nm and Roi 9 nm.

Then, the thickness direction retardation Rth obtained by adding the values of the thickness direction retardations Rth represented by { (nx + ny)/2-nz } · d of the plurality of optical layers other than the liquid crystal layer 10 between the first polarizing layer 12 and the second polarizing layer 16 is 353nm, and the in-plane retardation Ro obtained by adding the values of the in-plane retardations Roi of the plurality of optical layers is 12 nm. Then, a value 0.83 Δ nd obtained by multiplying the preferable coefficient 0.83 by a value Δ nd of the liquid crystal layer 10 is 315nm, and 353nm which is a thickness direction retardation Rth after addition is in a range of 315 plus and minus 80nm which is the value of the preferable coefficient 0.83 Δ nd. The total value of the in-plane retardations Ro and Δ nd obtained by the addition is 392nm, and is within a range of 350nm to 600nm where Ro + Δ nd is defined.

Since the liquid crystal display element has the above-described structure, the angle dependence of the transmittance can be improved, and the wide viewing angle of the display can be enlarged.

FIGS. 8A to 8D are white displays T of the liquid crystal display device_WBlack display T_BT is displayed in 50% gray scale (gray scale of 50% of brightness in white display)₅₀And a 20% gradation (gradation of 20% of luminance in white display) display T₂₀A view angle characteristic diagram, and FIG. 8A shows a drawingThe characteristic of the angle of view in the left-right direction of the surface, fig. 8B shows the characteristic of the angle of view in the down-up direction of the screen, fig. 8C shows the characteristic of the angle of view in the down-left-right direction of the screen, and fig. 8D shows the characteristic of the angle of view in the down-right-up direction of the screen.

In fig. 8A, a negative angle is an angle in the left direction, and a positive angle is an angle in the right direction. In fig. 8B, the negative angle is the angle in the downward direction, and the positive angle is the angle in the upward direction. In fig. 8C, the negative angle is the angle in the lower left direction, and the positive angle is the angle in the upper right direction. In fig. 8D, the negative angle is the angle in the lower right direction, and the positive angle is the angle in the upper left direction.

As shown in fig. 8A to 8D, the liquid crystal display element has a viewing angle characteristic in which the angle dependence of the transmittance in each of the left-right direction, the down-up direction, the down-left-down direction, and the down-right-up direction of the screen is improved, and the gray scale is not inverted over a wide angle range in each of the directions.

(modified example of the first embodiment)

In the liquid crystal display device of the first embodiment, the value Δ nd of the liquid crystal layer 10 of the liquid crystal cell 1 is set to 380nm, but the value Δ nd of the liquid crystal layer 10 may be set to other values.

FIGS. 9A to 9D show white display T in a liquid crystal display element having a liquid crystal layer 10 with a Δ nd value of 505nm and the other structures similar to those of the above-described embodiment_wBlack display T_B50% gray scale display T₅₀And 20% gray scale display T₂₀View angle characteristic diagram of time. Fig. 9A shows the characteristic of the angle of view in the left-right direction of the screen, fig. 9B shows the characteristic of the angle of view in the down-up direction of the screen, fig. 9C shows the characteristic of the angle of view in the down-left-right direction of the screen, and fig. 9D shows the characteristic of the angle of view in the down-right-up direction of the screen.

As shown in fig. 9A to 9D, the liquid crystal display element of this modified example has a viewing angle characteristic in which the angle dependence of the transmittance in each of the left-right direction, the down-up direction, the down-left-right direction, and the down-right-up direction of the screen is improved, and there is no inversion of the halftone over a wide angle range in each of the directions, and the contrast is higher than that of the liquid crystal display element of the above embodiment.

(second embodiment)

Fig. 10 to 12 show a second embodiment of the present invention, and fig. 10 is a schematic sectional view of a liquid crystal display element.

The liquid crystal display element of the present embodiment is an element as follows: in the liquid crystal display device of the first embodiment, the first phase difference plate 26 is provided between the first polarizing plate 11 and the first viewing angle compensating plate 19, and the second phase difference plate 27 is provided between the second polarizing plate 15 and the second viewing angle compensating plate 22. The plurality of optical layers between the first and second polarizing layers 12 and 16 other than the liquid crystal layer 10 include: base materials 14 and 18 on surfaces opposed to the pair of substrates 2 and 3 of the liquid crystal cell 1 of the first and second polarizing layers 12 and 16; the first and second viewing angle compensating layers 20 and 23 and the substrates 21 and 24 thereof; and the first and second phase plates 26, 27. In addition, other structures of the liquid crystal display element of the present embodiment are substantially the same as those of the first embodiment.

Fig. 11 shows the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1, the directions of the absorption axes 12a and 16 of the polarizing layers 12 and 16 of the first and second polarizing plates 11 and 15, the directions of the optical axis directions 20a and 23a of the viewing angle compensating layers 20 and 23 of the first and second viewing angle compensating plates 19 and 22, and the directions of the slow axes 26a and 27a of the first and second retardation plates 26 and 27 in the liquid crystal display device according to this embodiment.

As shown in fig. 11, the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1; the orientation of the absorption layers 12a, 16a of the polarizing layers 12, 16 of the first and second polarizers 11, 15; the directions of the optical axis directions 20a and 23a of the viewing angle compensating layers 20 and 23 of the first and second viewing angle compensating plates 19 and 22 are the same as those of the first embodiment. The slow axis 26a of the first retardation plate 26 is arranged in a direction substantially parallel to the optical axis direction 20a of the first viewing angle compensating layer 20 of the first viewing angle compensating plate 19. The slow axis 27a of the second retardation plate 27 is arranged in a direction substantially parallel to the optical axis direction 23a of the second viewing angle compensating layer 23 of the second viewing angle compensating plate 22.

In the present embodiment, the value of Δ nd of the liquid crystal layer 10 of the liquid crystal cell 1 is set to 420nm, and the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second viewing angle compensating layers 20 and 23 are set to Rthi of 70nm and Roi of-47 nm, respectively. In addition, the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the substrates 14 and 18 of the first and second polarizing layers 12 and 16 on the surfaces facing the liquid crystal cell 1 and the substrates 21 and 24 of the first and second viewing angle compensating layers 20 and 23 are set to 89nm and 9nm, respectively. The values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second retardation plates 26 and 27 are respectively set to 175nm for Rthi and 35nm for Roi. In this way, the total value of the retardation value in the thickness direction of each of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 except for the liquid crystal layer 10 and the retardation value in the liquid crystal layer direction of the liquid crystal layer 10 when a voltage is applied is set to be in the range of-80 nm to +80 nm.

FIGS. 12A to 12D show a white display T of the liquid crystal display element of the present embodiment_WBlack display of T_B50% gray scale display T₅₀And 20% gray scale display T₂₀View angle characteristic diagram of time. Fig. 12A shows the characteristic of the angle of view in the left-right direction of the screen, fig. 12B shows the characteristic of the angle of view in the down-up direction of the screen, fig. 12C shows the characteristic of the angle of view in the down-left-right direction of the screen, and fig. 12D shows the characteristic of the angle of view in the down-right-up direction of the screen.

As shown in fig. 12A to 12D, in the liquid crystal display element of the present embodiment, the angle dependence of the transmittance in each of the left-right direction, the down-up direction, the left-down-right direction, and the right-down-left-up direction of the screen is improved. In addition, the liquid crystal display device has a viewing angle characteristic that the halftone inversion is not generated over the wide angle range in each of the above directions, and particularly, the viewing angles in the left-right direction, the left-lower-right direction, and the right-lower-upper-left direction are high, and the contrast is high.

(third embodiment)

Fig. 13 to 16 show a third embodiment of the present invention, and fig. 13 shows a schematic cross-sectional view of a liquid crystal display element.

The liquid crystal display element of the present embodiment is an element as follows: in the liquid crystal display device of the second embodiment, the first and second optical films 28 and 29 having a phase difference are respectively provided between the first retardation plate 26 and the first viewing angle compensating plate 19, and between the second retardation plate 27 and the second viewing angle compensating plate 22. The plurality of optical layers between the first and second polarizing layers 12 and 16 other than the liquid crystal layer 10 include: base materials 14 and 18 on surfaces of the first and second polarizing layers 12 and 16 facing the pair of substrates 2 and 3 of the liquid crystal cell 1; the first and second viewing angle compensating layers 20 and 23 and the substrates 21 and 24 thereof; the first and second phase difference plates 26, 27; and the above-described first and second optical films 28, 29. In addition, other structures of the liquid crystal display element of the present embodiment are substantially the same as those of the second embodiment.

As shown in fig. 14, in the first and second optical films 28 and 29 as the optical medium 100, one refractive index nx and the other refractive index nx in 2 directions x and y perpendicular to each other on a plane parallel to the film surface thereof, that is, the substrate surface of the liquid crystal cell 1, and a refractive index nz in a thickness direction z perpendicular to the film surface (the substrate surface of the liquid crystal cell 1) are in a relationship of nx > ny > nz.

That is, the first and second optical films 28 and 29 are retardation films each having an optical axis in the thickness direction z perpendicular to the film surface.

Fig. 15 shows the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1 in the liquid crystal display device of the present embodiment; the directions of the absorption axes 12a, 16a of the polarizing layers 12, 16 of the first and second polarizing plates 11, 15; directions of optical axis directions 20a and 23a of the viewing angle compensation layers 20 and 23 of the first and second viewing angle compensation plates 19 and 22; the directions of the slow axes 26a, 27a of the first and second phase plates 26, 27; and the direction of the optical axes 28a, 29a of the first and second optical films 28, 29.

As shown in fig. 15, the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1; the directions of the absorption axes 12a, 16a of the polarizing layers 12, 16 of the first and second polarizing plates 11, 15; the directions of the optical axis directions 20a and 23a of the viewing angle compensating layers 20 and 23 of the first and second viewing angle compensating plates 19 and 22 are the same as those of the first and second embodiments.

On the other hand, the first phase difference plate 26 is disposed such that the slow axis 26a is parallel to a direction intersecting a transverse axis direction (a direction indicated by a chain line in the drawing) of the screen at an angle of substantially 110 ° in a leftward direction as viewed from the observation side. The second phase difference plate 27 is disposed such that the slow axis 27a is parallel to a direction in which a left turn direction viewed from the observation side substantially intersects with the horizontal axis direction of the screen at an angle of 20 °, that is, parallel to a direction substantially perpendicular to the slow axis 26a of the first phase difference plate 26. The directions of the optical axes 28a and 29a of the first and second optical films 28 and 29 are perpendicular to the substrate surface of the liquid crystal cell 1.

In the present embodiment, the value of Δ nd of the liquid crystal layer 10 of the liquid crystal cell 1 is 385nm, and the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second viewing angle compensating layers 20 and 23 are respectively set to Rthi 159nm and Roi-38 nm. In addition, the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the substrates 14 and 18 of the first and second polarizing layers 12 and 16 facing the liquid crystal cell 1, and the substrates 21 and 24 of the first and 2 viewing angle compensating layers 20 and 23 are set to Rthi 89nm and Roi 9nm, respectively. The values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second phase plates 26 and 27 are set to 50nm for Rthi and 64nm for Roi, respectively. The first and second optical films 28 and 29 have a thickness direction retardation Rthi of-160 nm (in-plane retardation Roi of each of the optical films 28 and 29 is 0). In this way, the total value of the retardation in the thickness direction of each of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 except for the liquid crystal layer 10 and the value of the retardation in the thickness direction of the liquid crystal layer 10 is set to be in the range of 0 ± 80 nm.

FIGS. 16A to 16D show white display T of the liquid crystal display element of the present embodiment_WBlack display of T_B50% gray scale display T₅₀And 20% gray scale display T₂₀Fig. 16A shows the viewing angle characteristics in the left-right direction of the screen, fig. 16B shows the viewing angle characteristics in the down-up direction of the screen, fig. 16C shows the viewing angle characteristics in the down-left-right direction of the screen, and fig. 16D shows the viewing angle characteristics in the down-right-up direction of the screen.

As shown in fig. 16A to 16D, the liquid crystal display device of the present embodiment has a viewing angle characteristic in which the angle dependence of the transmittance in each of the left-right direction, the down-up direction, the down-left-right direction, and the down-right-up direction of the screen is improved, and the gray scale is not inverted over a wide angle range in each of the directions, and particularly, the viewing angles in the left-right direction, the down-left direction, and the down-right-up direction are wide and the contrast is high.

(fourth embodiment)

Fig. 17 to 19 show a fourth embodiment of the present invention, and fig. 17 is a schematic cross-sectional view of a liquid crystal display element.

The liquid crystal display element of the present embodiment is an element as follows: in the liquid crystal display device according to the second embodiment, the optical film 29 provided in the third embodiment is further provided between the first retardation plate 26 and the first viewing angle compensation plate 19, and between the second retardation plate 27 and the second viewing angle compensation plate 22, for example, between the first retardation plate 26 and the first viewing angle compensation plate 19. The plurality of optical layers between the first and second polarizing layers 12 and 16 other than the liquid crystal layer 10 include: base materials 14 and 18 on surfaces of the first and second polarizing layers 12 and 16 facing the pair of substrates 2 and 3 of the liquid crystal cell 1; first and second viewing angle compensating layers 20 and 23 and substrates 21 and 24 thereof; first and second phase difference plates 26, 27; and the optical film 29 described above. In addition, other structures of the liquid crystal display device of the present embodiment are substantially the same as those of the third embodiment.

Fig. 18 shows the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1, the directions of the absorption layers 12a and 16a of the polarizing layers 12 and 16 of the first and second polarizing plates 11 and 15, the directions of the optical axis directions 20a and 23a of the viewing angle compensating layers 20 and 23 of the first and second viewing angle compensating plates 19 and 22, the directions of the slow axes 26a and 27a of the first and second retardation plates 26 and 27, and the direction of the optical axis 29a of the optical film 29 in the liquid crystal display device according to the present embodiment.

As shown in fig. 18, the orientation treatment directions 7a and 8a of the first and second orientation films 7 and 8 of the liquid crystal cell 1, the directions of the absorption axes 12a and 16a of the polarizing layers 12 and 16 of the first and second polarizing plates 11 and 15, and the directions of the optical axis directions 20a and 23a of the viewing angle compensating layers 20 and 23 of the first and second viewing angle compensating plates 19 and 22 are the same as those of the first and second embodiments. The direction of the slow axis 26a of the first phase plate 26 and the direction of the slow axis 27a of the second phase plate 27 are the same as those in the third embodiment. The optical axis 29a of the optical film 29 is oriented perpendicular to the substrate surface of the liquid crystal cell 1.

In this embodiment, the value of Δ nd of the liquid crystal layer 10 of the liquid crystal cell 1 is set to 386nm, and the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second viewing angle compensating layers 20 and 23 are set to rth ═ 159nm and Roi ═ 38nm, respectively. In addition, the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the substrates 14 and 18 of the first and second polarizing layers 12 and 16 on the surfaces facing the liquid crystal cell 1 and the substrates 21 and 24 of the first and second viewing angle compensating layers 20 and 23 are set to 89nm and 9nm, respectively. The values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second phase plates 26 and 27 are set to Rthi 50nm and Roi 64nm, respectively. The thickness direction retardation Rthi of the optical film 28 was set to-160 nm (the in-plane retardation Roi of the optical film 28 was 0). In this way, the total value of the retardation in the thickness direction of each of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 except for the liquid crystal layer 10 and the retardation in the thickness direction of the liquid crystal layer 10 is set to be in the range of 0 ± 80 nm.

FIGS. 19A to 19D are diagrams showing a white display T of the liquid crystal display device of the present embodiment_WBlack display T_B50% gray scale display T₅₀And 20% gray scale display T₂₀Fig. 19A shows a view angle characteristic in the left-right direction of the screen, fig. 19B shows a view angle characteristic in the lower-upper direction of the screen, fig. 19C shows a view angle characteristic in the lower-left-lower direction of the screen, and fig. 19D shows a view angle characteristic in the lower-right-upper direction of the screen.

As shown in fig. 19A to 19D, the liquid crystal display device of the present embodiment has a viewing angle characteristic in which the angle dependence of the transmittance in each of the left-right direction, the down-up direction, the down-left-right direction, and the down-right-up direction of the screen is improved, and the halftone is not inverted over a wide angle range in each of the directions, and in particular, the viewing angles in the left-right direction, the down-left direction, and the down-right-up direction are wide and the contrast is high.

(embodiment 5)

Fig. 20 to 22 show embodiment 5 of the present invention, and fig. 20 is a schematic sectional view of a liquid crystal display element.

The liquid crystal display element of the present embodiment is an element as follows: in the liquid crystal display device of the second embodiment, the first and second viewing angle compensating layers 20 and 23 are formed on the plate surfaces of the first and second phase plates 26 and 27. The plurality of optical layers between the first and second polarizing layers 12 and 16, except for the liquid crystal layer 10, includes: substrates 14 and 18 on surfaces of the first and second polarizing plates 12 and 16 facing the pair of substrates 2 and 3 of the liquid crystal cell 1; the first and second viewing angle compensating layers 20 and 23; and the first and second phase plates 26, 27. In addition, other structures of the liquid crystal display element of the present embodiment are substantially the same as those of the second embodiment.

Fig. 21 shows the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1, the directions of the absorption axes 12a and 16a of the polarizing layers 12 and 16 of the first and second polarizing plates 11 and 15, the directions of the optical axis directions 20a and 23a of the first and second viewing angle compensating layers 20 and 23, and the directions of the slow axes 26a and 27a of the first and second retardation plates 26 and 27 in the liquid crystal display device according to this embodiment.

As shown in fig. 21, the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1, the directions of the absorption axes 12a and 16a of the polarizing layers 12 and 16 of the first and second polarizing plates 11 and 15, and the directions of the optical axis directions 20a and 23a of the first and second viewing angle compensating layers 20 and 23 are the same as those of the first embodiment. The direction of the slow axis 26a of the first phase plate 26 and the direction of the slow axis 27a of the second phase plate 27 are the same as those in the third embodiment.

In this embodiment, the value Δ nd of the liquid crystal layer 10 of the liquid crystal cell 1 is 385nm, and the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second viewing angle compensating layers 20 and 23 are respectively set as follows: rthi 70nm, Roi-47 nm. In addition, the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the substrates 14 and 18 on the surfaces of the first and second polarizing layers 12 and 16 facing the liquid crystal cell 1 are respectively set as follows: rthi is 89nm, Roi is 9 nm. The values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second retardation plates 26, 27 are set to: rthi 55nm, Roi 71 nm. In this way, the total value of the retardation in the thickness direction of each of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 excluding the liquid crystal layer 10 and the retardation in the thickness direction of the liquid crystal layer 10 is set to be in the range of 0 ± 80 nm.

In the liquid crystal display device of the present embodiment, the first and second viewing angle compensation layers 20 and 23 are formed on the plate surfaces of the first and second phase difference plates 26 and 27, and the substrates having retardation in the thickness direction of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 are only the substrates 14 and 18 on the surface of the first and second polarizing layers 12 and 16 facing the liquid crystal cell 1. Thus, since the number of substrates having retardation in the thickness direction can be reduced, the angle dependence of the transmittance can be more effectively improved.

FIGS. 22A to 22D show white display T of the liquid crystal display element of the present embodiment_WBlack display T_B50% gray scale display T₅₀And 20% gray scale display T₂₀Fig. 22A shows the viewing angle characteristics in the left-right direction of the screen, fig. 22B shows the viewing angle characteristics in the down-up direction of the screen, fig. 22C shows the viewing angle characteristics in the down-left-right direction of the screen, and fig. 22D shows the viewing angle characteristics in the down-right-up direction of the screen.

As shown in fig. 22A to 22D, the liquid crystal display device of the present embodiment has a viewing angle characteristic in which the angle dependence of the transmittance in each of the left-right direction, the down-up direction, the down-left-down direction, and the down-right-up direction of the screen is improved, and the halftone is not inverted over a wide angle range in each of the directions, and particularly, the viewing angles in the left-right direction, the down-left-down direction, and the down-right-up direction are wide and the contrast is high.

(embodiment 6)

Fig. 23 to 25 show embodiment 6 of the present invention, and fig. 23 is a schematic cross-sectional view of a liquid crystal display element.

The liquid crystal display element of the present embodiment is an element as follows: in the liquid crystal display device of the second embodiment, the base materials 13 and 17 are provided only on the outer surfaces of the first and second polarizing layers 12 and 16 on the opposite sides of the surfaces facing the pair of substrates 2 and 3 of the liquid crystal cell 1, and the first and second phase difference plates 26 and 27 are laminated on the surfaces facing the liquid crystal cell 1 of the first and second polarizing layers 12 and 16, respectively. The plurality of optical layers between the first and second polarizing layers 12 and 16 other than the liquid crystal layer 10 include: the first and second phase plates 26 and 27, the first and second viewing angle compensating layers 20 and 23, and the substrates 21 and 24 of the viewing angle compensating layers 20 and 23. Other structures of the liquid crystal display device of this embodiment are substantially the same as those of the second embodiment.

Fig. 24 shows the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1, the directions of the absorption axes 12a and 16a of the first and second polarizing layers 12 and 16, the directions of the optical axes 20a and 23a of the first and second viewing angle compensating layers 20 and 23, and the directions of the slow axes 26a and 27a of the first and second retardation plates 26 and 27 in the liquid crystal display device according to this embodiment.

As shown in fig. 24, the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1, the directions of the absorption axes 12a and 16a of the first and second polarizing layers 12 and 16, the directions of the optical axis directions 20a and 23a of the first and second viewing angle compensating layers 20 and 23, and the directions of the slow axes 26a and 27a of the first and second retardation plates 26 and 27 are the same as those of the first embodiment.

In this embodiment, the value Δ nd of the liquid crystal layer 10 of the liquid crystal cell 1 is set to 420nm, and the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second viewing angle compensating layers 20 and 23 are set to: rthi 159nm, Roi-38 nm. The values of the thickness direction retardation Rthi and the in-plane retardation Roi of the substrates 21 and 24 of the first and second viewing angle compensating layers 20 and 23 are set to: rthi is 89nm, Roi is 9 nm. The values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second retardation plates 26, 27 are set to: and Rthi is 175nm, and Roi is 35 nm. In this way, the total value of the retardation in the thickness direction of each of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 except for the liquid crystal layer 10 and the value of the retardation in the thickness direction of the liquid crystal layer 10 is set to be within the range of 0 ± 80 nm.

In the liquid crystal display device of the present embodiment, the substrates 13 and 17 are provided only on the outer surfaces of the first and second polarizing layers 12 and 16, the first and second retardation plates 26 and 27 are laminated on the surfaces of the first and second polarizing layers 12 and 16 facing the liquid crystal cell 1, and the substrates having retardation in the thickness direction of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 are only the substrates 21 and 24 of the first and second viewing angle compensating layers 20 and 23. Thus, since the number of substrates having retardation in the thickness direction can be reduced, the angle dependence of the transmittance can be more effectively improved.

FIGS. 25A to 25D show white display T of the liquid crystal display element of the present embodiment_WBlack display of T_B50% gray scale display T₅₀And 20% gray scale display T₂₀Fig. 25A shows a view angle characteristic in the left-right direction of the screen, fig. 25B shows a view angle characteristic in the lower-upper direction of the screen, fig. 25C shows a view angle characteristic in the lower-left-lower-right direction of the screen, and fig. 25D shows a view angle characteristic in the lower-right-upper-right direction of the screen.

As shown in fig. 25A to 25D, the liquid crystal display device of the present embodiment has a viewing angle characteristic in which the angle dependence of the transmittance in each of the left-right direction, the down-up direction, the down-left-right direction, and the down-right-up direction of the screen is improved, and the halftone is not inverted over a wide angle range in each of the above-mentioned directions, and particularly, the viewing angles in each of the left-right direction, the down-left direction, and the down-right-up direction are wide and the contrast is high.

(7 th embodiment)

Fig. 26 to 28 show embodiment 7 of the present invention, and fig. 26 is a schematic sectional view of a liquid crystal display element.

The liquid crystal display element of the present embodiment is an element as follows: in the liquid crystal display device of the second embodiment, the base materials 13 and 17 are provided only on the outer surfaces of the first and second polarizing layers 12 and 16 on the opposite sides of the surfaces facing the pair of substrates 2 and 3 of the liquid crystal cell 1, the first and second retardation plates 26 and 27 are laminated on the surfaces of the first and second polarizing layers 12 and 16 facing the liquid crystal cell 1, respectively, and the first and second viewing angle compensating layers 20 and 23 are formed on the surfaces of the first and second retardation plates 26 and 27 facing the liquid crystal cell 1, respectively. The plurality of optical layers between the first and second polarizing layers 12 and 16 other than the liquid crystal layer 10 include: the first and second phase difference plates 26, 27; and first and second viewing angle compensation layers 20 and 23. In addition, other structures of the liquid crystal display element of the present embodiment are substantially the same as those of the second embodiment.

Fig. 27 shows the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8 of the liquid crystal cell 1, the directions of the absorption axes 12a and 16a of the first and second polarizing layers 12 and 16, the directions of the optical axis directions 20a and 23a of the first and second viewing angle compensating layers 20 and 23, and the directions of the slow axes 26a and 27a of the first and second phase difference plates 26 and 27 in the liquid crystal display device according to this embodiment.

As shown in fig. 27, the alignment treatment directions 7a and 8a of the first and second alignment films 7 and 8, the directions of the absorption axes 12a and 16a of the first and second polarizing layers 12 and 16, and the directions of the optical axis directions 20a and 23a of the first and second viewing angle compensating layers 20 and 23 of the liquid crystal cell 1 are the same as those of the first embodiment. The first phase difference plate 26 is disposed such that the slow axis 26a thereof is parallel to a direction in which a leftward turning direction viewed from the observation side substantially intersects with the horizontal axis direction of the screen at an angle of 100 °. The second phase plate 27 is disposed so that the slow axis 27a thereof is parallel to a direction in which a left turn direction viewed from the observation side substantially crosses the horizontal axis direction of the screen at an angle of 10 °, that is, parallel to a direction substantially perpendicular to the retardation axis 26a of the first phase plate 26.

In the present embodiment, the value Δ nd of the liquid crystal layer 10 of the liquid crystal cell 1 is set to 430nm, and the values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second viewing angle compensating layers 20 and 23 are set to: rthi 70nm, Roi-47 nm. The values of the thickness direction retardation Rthi and the in-plane retardation Roi of the first and second retardation plates 26, 27 are set to: rthi 70nm, Roi 48 nm. In this way, the total value of the retardation in the thickness direction of each of the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16 except for the liquid crystal layer 10 and the value of the retardation in the thickness direction of the liquid crystal layer 10 is set to be in the range of 0 ± 80 nm.

In the liquid crystal display device of the present embodiment, the substrates 13 and 17 are provided only on the outer surfaces of the first and second polarizing layers 12 and 16, the first and second phase difference plates 26 and 27 are laminated on the surfaces of the first and second polarizing layers 12 and 16 facing the liquid crystal cell 1, and the first and second viewing angle compensating layers 20 and 23 are formed on the surfaces of the first and second phase difference plates 26 and 27 facing the liquid crystal cell 1, whereby the substrate having retardation in the thickness direction is removed from the plurality of optical layers between the first polarizing layer 12 and the second polarizing layer 16, and only the substrates 21 and 24 of the first and second viewing angle compensating layers 20 and 23 are formed. Thus, since the number of substrates having the above thickness direction retardation can be reduced, the angle dependence of the transmittance can be more effectively improved.

FIGS. 28A to 28D show white display T of the liquid crystal display element of the present embodiment_WBlack display of T_B50% gray scale display T₅₀And 20% gray scale display T₂₀Fig. 28A shows the viewing angle characteristics in the left-right direction of the screen, fig. 28B shows the viewing angle characteristics in the down-up direction of the screen, fig. 28C shows the viewing angle characteristics in the down-left-right direction of the screen, and fig. 28D shows the viewing angle characteristics in the down-right-up direction of the screen.

As shown in fig. 28A to 28D, the liquid crystal display device of the present embodiment has a viewing angle characteristic in which the angle dependence of the transmittance in each of the left-right direction, the down-up direction, the down-left-right direction, and the down-right-up direction of the screen is improved, and the halftone is not inverted over a wide angle range in each of the directions, and particularly, the viewing angles in each of the left-right direction, the down-left direction, and the down-right-up direction are wide and the contrast is high.

(Another embodiment)

The first and second viewing angle compensating layers 20 and 23 of the above embodiments are formed of discotic liquid crystal layers in which discotic liquid crystal molecules 25 are mixedly aligned, but the first and second viewing angle compensating layers are not limited to the discotic liquid crystal layers, and may be formed of liquid crystal layers in which liquid crystal molecules in a shape of an elongated sphere are aligned obliquely with respect to a direction in which the plane parallel to the substrate surface of the liquid crystal cell 1 is tilted in one direction.

Further, although the liquid crystal display element of each of the above embodiments is of a standard white type in which the first polarizing layer 12 and the second polarizing layer 16 are disposed so that the absorption axes 12a and 16a are substantially perpendicular to each other, the liquid crystal display element may be of a standard white type in which the first polarizing layer 12 and the second polarizing layer 16 are disposed so that the absorption axes 12a and 16a are substantially parallel to each other.

As described above, the liquid crystal display device of the present invention includes: a liquid crystal cell configured by sandwiching a liquid crystal layer in which liquid crystal molecules are twisted and aligned substantially at 90 ° between a pair of substrates (substrates) each having at least 1 electrode and an alignment film covering the electrode formed on each of inner surfaces facing each other; first and second polarizing plates disposed on both sides of the liquid crystal cell, each polarizing plate comprising a polarizing layer and at least 1 substrate supporting the polarizing layer, the polarizing layer having a transmission axis through which linearly polarized light is transmitted and an absorption axis in a direction perpendicular to the transmission axis; and first and second viewing angle compensation layers respectively disposed between the liquid crystal cell and the first and second polarizing plates, each viewing angle compensation layer having a phase difference in a plane parallel to a substrate surface of the liquid crystal cell and a phase difference in a plane perpendicular to the substrate surface; a total value of the retardation in the thickness direction, which is formed by a product of a phase difference in a plane perpendicular to the substrate surface and a layer thickness of each of the optical layers between the first polarizing layer and the second polarizing layer, including at least the first and second viewing angle compensating layers, and excluding the liquid crystal layer, is set to a value as follows: this value can cancel out the retardation in the thickness direction of the liquid crystal layer formed by the product of the in-plane phase difference of the liquid crystal layer perpendicular to the substrate surface and the thickness of the liquid crystal layer when a high voltage sufficient to cause the liquid crystal molecules to be oriented in an upright state with respect to the substrate surface is applied between the electrodes of the first and second substrates.

In the liquid crystal display device, the thickness direction retardation of each of the plurality of optical layers and the liquid crystal layer thickness direction retardation of the liquid crystal layer are preferably set so that a sum of a total value of the thickness direction retardations of each of the plurality of optical layers and a value of the liquid crystal layer thickness direction retardation of the liquid crystal layer is in a range of-80 nm to +80 nm.

In the liquid crystal display device, it is preferable that a total value of a liquid crystal layer thickness direction retardation of the liquid crystal layer when a high voltage sufficient for the liquid crystal molecules to be oriented in a standing state is applied and a value of a total thickness direction retardation of each of the plurality of optical layers other than the liquid crystal layer between the first polarizing layer and the second polarizing layer is set such that a difference between absolute values is 80nm or less and positive and negative are opposite. In this case, the retardation in the thickness direction of the liquid crystal layer is preferably a value as follows: the value of the product Δ nd of the refractive index anisotropy Δ n of the liquid crystal material constituting the liquid crystal layer and the liquid crystal layer thickness d is multiplied by a coefficient in the range of 0.72 to 0.89 selected from the pretilt angle of the liquid crystal molecules with respect to the substrate surface and a high voltage value sufficient for the liquid crystal molecules to be aligned in a standing state. In addition, for each of the plurality of optical layers other than the liquid crystal layer between the first polarizing layer and the second polarizing layer, when one direction and the other direction of 2 mutually perpendicular directions in a plane parallel to the substrate surface are respectively an X axis and a Y axis, a thickness direction perpendicular to the substrate surface is a Z axis, a refractive index in the X axis direction is nx, a refractive index in the Y axis direction is ny, a refractive index in the Z axis direction is nz, and a layer thickness of the optical layer is d, a total value of retardation in the thickness direction of each optical layer represented by { (nx + ny)/2-nz } & d is set to a value substantially equal to: the value of the product Δ nd of the refractive index anisotropy Δ n of the liquid crystal material constituting the liquid crystal layer and the liquid crystal layer d is multiplied by a coefficient in the range of 0.72 to 0.89, which is selected from the pretilt angle of the liquid crystal molecules with respect to the substrate surface and a high voltage value sufficient for the liquid crystal molecules to be aligned in a standing state. Further, a total value of the thickness direction retardation values of the plurality of optical layers between the first polarizing layer and the second polarizing layer other than the liquid crystal layer is set to be substantially equal to a value calculated by multiplying a value Δ nd, which is a product of the refractive index anisotropy Δ n of a liquid crystal material constituting the liquid crystal layer and the liquid crystal layer thickness d, by a coefficient of 0.83.

In the liquid crystal display device according to the present invention, it is preferable that a total value of in-plane retardation formed by a product of an in-plane retardation in a plane parallel to a substrate surface of each of a plurality of optical layers including the liquid crystal layer between the first polarizing layer and the second polarizing layer and a layer thickness of each of the plurality of optical layers is set to be in a range of 350 to 600 nm.

In the liquid crystal display device of the present invention, it is preferable that the liquid crystal cell includes: a first substrate on one surface of which at least 1 first electrode and a first alignment film that is provided so as to cover the first electrode and is subjected to an alignment treatment in a predetermined first direction are formed; a second substrate arranged to face the electrode formation surface of the first substrate, wherein at least 1 second electrode and a second alignment film are formed on the surface of the second substrate facing the first electrode, the second alignment film being provided so as to cover the second electrode and being subjected to an alignment treatment in a second direction intersecting the first direction at an angle of substantially 90 °; a liquid crystal layer that is twisted and aligned at a twist angle of substantially 90 ° and is sandwiched between the 1 st alignment film of the first substrate and the second alignment film of the second substrate; the first polarizing plate has a first polarizing layer having an absorption axis in a direction substantially intersecting with an orientation treatment direction of the first alignment film at an angle of 45 °; the second polarizing plate has a second polarizing layer having an absorption axis in a direction substantially perpendicular or substantially parallel to the absorption axis of the first polarizing layer.

In the liquid crystal display device of the present invention, the first and second polarizing layers each include a base material made of a resin film, the base material being provided on at least surfaces of the polarizing layers facing the first and second substrates and having a retardation in a thickness direction formed by a product of a phase difference and a layer thickness in a plane perpendicular to the substrate surfaces; the first and second viewing angle compensation layers each include a base material made of a resin film, the base material being provided on at least one surface of the viewing angle compensation layers and having a retardation in a thickness direction formed by a product of a phase difference and a layer thickness in a plane perpendicular to the substrate surface; the plurality of optical layers between the first polarizing layer and the second polarizing layer, excluding the liquid crystal layer, are composed of at least a base material of surfaces of the first and second polarizing layers facing the first and second substrates, the first and second viewing angle compensating layers, and the base material of the viewing angle compensating layers.

In the liquid crystal display device according to the present invention, it is preferable that a first retardation plate is further provided between the first polarizing layer and the first viewing angle compensating layer, and a second retardation plate is further provided between the second polarizing layer and the second viewing angle compensating layer. In this case, it is preferable that each of the first and second polarizing layers includes a base material made of a resin film, the base material being provided on at least surfaces of the polarizing layers facing the first and second substrates and having a thickness-direction retardation formed by a product of a phase difference and a layer thickness in a plane perpendicular to the substrate surfaces; the first and second viewing angle compensating layers are formed on the plate surfaces of the first phase difference plate and the second phase difference plate, respectively. Further, it is preferable that the first and second polarizing layers each include a base material made of a resin film, the base material being provided on an outer surface of the polarizing layer opposite to a surface thereof facing the first and second substrates; the first and second viewing angle compensation layers each include a base material made of a resin film, the base material being provided on at least one surface of the viewing angle compensation layers and having a retardation in a thickness direction formed by a product of a phase difference and a layer thickness on a surface perpendicular to a substrate surface; the first and second phase difference plates are laminated on surfaces of the first and second polarizing layers facing the first and second substrates, respectively. Preferably, the first and second polarizing layers each have a base material made of a resin film, the base material being provided on an outer surface of the polarizing layer opposite to a surface thereof facing the first and second substrates; the first and second phase difference plates are laminated on surfaces of the first and second polarizing layers facing the first and second substrates, respectively; the first and second viewing angle compensating layers are formed on the plate surfaces of the first and second phase difference plates, respectively. Further, it is preferable that an optical film having a refractive index nx in one direction and a refractive index ny in the other direction among 2 directions perpendicular to each other in a plane parallel to the substrate surface and a refractive index nz in a thickness direction perpendicular to the substrate surface be provided between the first phase difference plate and the first viewing angle compensation layer and at least one of the second phase difference plate and the second viewing angle compensation layer, the refractive index nx being in a relationship of ny > nz.

The liquid crystal display element of the present invention includes: a first substrate on one surface of which at least 1 first electrode and a first alignment film that is provided so as to cover the first electrode and is subjected to an alignment treatment in a predetermined first direction are formed; a second substrate arranged to face the electrode formation surface of the first substrate, wherein at least 1 second electrode and a second alignment film are formed on the surface of the second substrate facing the first electrode, the second alignment film being provided so as to cover the second electrode and being subjected to an alignment treatment in a second direction intersecting the first direction at an angle of substantially 90 °; a liquid crystal layer sandwiched between the first alignment film of the first substrate and the second alignment film of the second substrate, the liquid crystal molecules being twisted and aligned between the first alignment film and the second alignment film at a twist angle of substantially 90 °; a first polarizing plate including a first polarizing layer provided so as to face an outer surface of the first substrate on the opposite side of the electrode formation surface and having an absorption axis in a direction substantially intersecting with an orientation treatment direction of the first alignment film at an angle of 45 °, and a base material made of a resin film provided on at least a surface of the first polarizing layer facing the first substrate and having a thickness direction retardation formed by a product of a phase difference and a layer thickness in a plane perpendicular to the substrate surfaces of the first and second substrates; a second polarizing plate including a second polarizing layer and a base material made of a resin film, the second polarizing layer being disposed so as to face an outer surface of the second substrate on the opposite side of the electrode-formed surface and having an absorption axis in a direction substantially perpendicular to or substantially parallel to the absorption axis of the first polarizing layer, the base material being provided on at least a surface of the second polarizing layer facing the second substrate and having a thickness-direction retardation formed by a product of a phase difference and a layer thickness in a plane perpendicular to the substrate surface; first and second viewing angle compensating plates disposed between the substrate 1 and the first polarizing plate and between the second substrate and the second polarizing plate, each having a viewing angle compensating layer having a phase difference in a plane parallel to the substrate surface and a phase difference in a plane perpendicular to the substrate surface and a base material made of a resin film, the base material being provided on at least one surface of the viewing angle compensating layer and having a thickness direction retardation formed by a product of the phase difference in the plane perpendicular to the substrate surface and a layer thickness; a total value of a thickness direction retardation formed by a product of a phase difference in a plane perpendicular to the substrate surface of each of the plurality of optical layers and a thickness of each of the plurality of optical layers between the first polarizing layer of the first polarizing plate and the second polarizing layer of the second polarizing plate and a value of a liquid crystal layer thickness direction retardation formed by a product of a phase difference in a plane perpendicular to the substrate surface of the liquid crystal layer and a liquid crystal layer thickness when a high voltage sufficient to cause the liquid crystal molecules to be oriented in an upright state with respect to the substrate surface is applied between electrodes of the first and second substrates is set in a range of-80 nm to +80nm, and the plurality of optical layers include at least the substrate on a surface of the first and second polarizing plates facing the first and second substrates, each viewing angle compensating layer of the first and second viewing angle compensating plates, and the substrate of the first and second viewing angle compensating plates, and the above liquid crystal layer is excluded.

In the liquid crystal display element, the liquid crystal layer thickness direction retardation is preferably a value of: the value of the product Δ nd of the refractive index anisotropy Δ n of the liquid crystal material constituting the liquid crystal layer and the liquid crystal layer thickness d is multiplied by a value calculated by a coefficient in the range of 0.72 to 0.89 selected from the value of the pretilt angle of the liquid crystal molecules with respect to the substrate surface and the value of a high voltage sufficient to cause the liquid crystal molecules to be in the vertical alignment.

The total value of in-plane retardation formed by the product of the in-plane retardation in a plane parallel to the substrate surface of each of the plurality of optical layers including the plurality of base materials, the plurality of viewing angle compensation layers, and the liquid crystal layer between the first polarizing layer and the second polarizing layer and the layer thickness of each of the plurality of optical layers is set to be in the range of 350nm to 600 nm.

Preferably, a first retardation plate is further provided between the first polarizing layer and the first viewing angle compensating layer, and a second retardation plate is further provided between the second polarizing layer and the second viewing angle compensating layer.

The liquid crystal display element of the present invention includes: a first substrate having at least 1 first electrode and a first alignment film formed on one surface thereof and arranged to cover the first electrode and subjected to an alignment treatment in a predetermined first direction; a second substrate provided so as to face the electrode formation surface of the first substrate, wherein at least 1 second electrode and a second alignment film are formed on the surface facing the first substrate, the second electrode facing the first electrode, and the second alignment film is provided so as to cover the second electrode and is subjected to an alignment treatment in a second direction that substantially intersects the first direction at an angle of 90 °; a liquid crystal layer sandwiched between the first alignment film of the first substrate and the second alignment film of the second substrate, the liquid crystal molecules being twisted and aligned between the first alignment film and the second alignment film at a twist angle of substantially 90 °; a first polarizing layer disposed so as to face an outer surface of the first substrate on the opposite side of the electrode formation surface, the first polarizing layer having an absorption axis in a direction substantially intersecting with an orientation treatment direction of the first alignment film at an angle of 45 °; a second polarizing layer that is disposed so as to face an outer surface of the second substrate on the opposite side of the electrode formation surface and has an absorption axis in a direction substantially perpendicular to or substantially parallel to the absorption axis of the first polarizing layer; first and second viewing angle compensating layers respectively disposed between the first substrate and the first polarizing layer and between the second substrate and the second polarizing layer, each viewing angle compensating layer having a phase difference in a plane parallel to substrate surfaces of the first and second substrates and a phase difference in a plane perpendicular to the substrate surfaces; in the case where one and the other of 2 mutually perpendicular directions in a plane parallel to the substrate surface are defined as an X axis and a Y axis, a thickness direction perpendicular to the substrate surface is defined as a Z axis, a refractive index in the X axis direction is defined as nx, a refractive index in the Y axis direction is defined as ny, a refractive index in the Z axis direction is defined as nz, a layer thickness of the optical layer is defined as d, a thickness direction retardation of each optical layer represented by { (nx + ny)/2-nz } dis defined as Rthi, a thickness direction retardation obtained by adding values of the thickness direction retardations Rthi of the optical layers is defined as Rth, and a product of a refractive index anisotropy Δ n of a liquid crystal material constituting the liquid crystal layer and a liquid crystal layer thickness d is defined as Δ nd, for each of the plurality of optical layers other than the liquid crystal layer, the plurality of optical layers including at least the first and second viewing angle compensation layers being disposed between the first polarizing layer and the second polarizing layer, the above thickness direction retardation Rth is set in a range satisfying-80 nm < Rth-0.83. delta. nd < 80 nm.

In the liquid crystal display element, when an in-plane retardation of each optical layer represented by (nx-ny) · d is Roi and an in-plane retardation obtained by adding values of the in-plane retardations Roi of the optical layers is Ro, the in-plane retardation Ro and a Δ nd of the liquid crystal layer are set to satisfy the ranges of Ro + Δ nd from 350nm to 600nm, respectively, for the plurality of optical layers between the first polarizing layer and the second polarizing layer.

Claims

1. A liquid crystal display element, comprising:

a first polarizing layer (12) and a second polarizing layer (16), a transmission axis of the first polarizing layer (12) and a transmission axis of the second polarizing layer (16) being perpendicular to each other;

a liquid crystal cell (1) disposed between the first polarizing layer (12) and the second polarizing layer (16);

a first viewing angle compensation plate (19) disposed between the first polarizing layer (12) and the liquid crystal cell (1);

a second viewing angle compensation plate (22) disposed between the second polarizing layer (16) and the liquid crystal cell (1);

a first base material (14) that is disposed between the first polarizing layer (12) and the first viewing angle compensating plate (19), and supports the first polarizing layer (12); and

a second base material (18) disposed between the second polarizing layer (16) and the second viewing angle compensating plate (22) and supporting the second polarizing layer (16),

the liquid crystal cell (1) includes:

a first substrate (2) on which a first electrode (4) is formed;

a second substrate (3) on which a second electrode (5) is formed; and

a liquid crystal layer (10) disposed between the first electrode (4) and the second electrode (5), wherein the liquid crystal layer (10) is twisted and oriented at a twist angle of 90 DEG when no voltage is applied between the first electrode (4) and the second electrode (5), and retardation in the substrate plane remains in the liquid crystal layer (10) when a predetermined saturation voltage is applied between the first electrode (4) and the second electrode (5),

the total value of retardations in a plane perpendicular to the substrate surface of each optical layer disposed between the first polarizing layer (12) and the liquid crystal cell (1) and each optical layer disposed between the second polarizing layer (16) and the liquid crystal cell (1) is set to a value that is equal to a value that is opposite in sign to a value of retardation in a plane perpendicular to the substrate surface of the liquid crystal layer (10) when the saturation voltage is applied between the first electrode (4) and the second electrode (5).

2. The liquid crystal display element according to claim 1,

the first viewing angle compensating plate (19) and the second viewing angle compensating plate (22) compensate for retardation remaining in the liquid crystal layer in the substrate surface when the saturation voltage is applied.

3. The liquid crystal display element according to claim 1,

the 2-fold bisector of the twist angle of the liquid crystal layer when no voltage is applied between the first electrode (4) and the second electrode (5) is set to be parallel to the transmission axis of the first polarizing layer (12) or the transmission axis of the second polarizing layer (16).

4. The liquid crystal display element according to claim 1,

the first viewing angle compensation plate (19) has a compensation layer (20) formed of a discotic liquid crystal of hybrid orientation,

the tilt direction of the discotic liquid crystal as the optical axis (20a) is set to be parallel to the orientation treatment direction (7a) of the orientation film (7) provided on the first substrate (2).

5. The liquid crystal display element according to claim 1,

the second viewing angle compensation plate (22) has a compensation layer (23) formed of a discotic liquid crystal of hybrid orientation,

the tilt direction of the discotic liquid crystal as the optical axis (23a) is set to be parallel to the orientation treatment direction (8a) of the orientation film (8) provided on the second substrate (3).

6. The liquid crystal display element according to claim 1,

a first phase difference plate (26) is disposed between the first base material (14) and the first viewing angle compensating plate (19),

a second phase difference plate (27) is disposed between the second base material (18) and the second viewing angle compensating plate (22).

7. The liquid crystal display element according to claim 6,

a first optical film (28) is disposed between the first retardation plate (26) and the first viewing angle compensation plate (19), and the refractive index of the first optical film (28) in each direction in the substrate plane is the same and the refractive index in the substrate thickness direction is different from the refractive index in the substrate.

8. The liquid crystal display element according to claim 7,

a second optical film (29) is disposed between the second retardation plate (27) and the second viewing angle compensating plate (22), and the refractive index of the second optical film (29) in each direction in the substrate plane is the same and the refractive index in the substrate thickness direction is different from the refractive index in the substrate.

9. The liquid crystal display element according to claim 1,

the liquid crystal layer has a pretilt angle.

10. The liquid crystal display element according to claim 1,

the liquid crystal cell (1) includes:

a pixel having a red filter (6R) formed thereon;

a pixel in which a green filter (6G) is formed; and

a pixel formed with a blue filter (6B),

the liquid crystal layer has a different thickness between the pixels.

11. The liquid crystal display element according to claim 10,

when the wavelength of the color component corresponding to each pixel is λ, Δ nd of the liquid crystal layer of each pixel is set to λ/2 equally.

12. The liquid crystal display element according to claim 10,

the liquid crystal layer is twisted clockwise with respect to the traveling direction of light.

13. The liquid crystal display element according to claim 1,

the first substrate and the second substrate are formed of triacetyl cellulose.

14. The liquid crystal display element according to claim 1,

the first viewing angle compensation plate (19) has a compensation layer (20) and a base material (21),

the compensation layer (20) is formed by a discotic liquid crystal of hybrid orientation,

the base material (21) is formed of triacetyl cellulose, and supports the compensation layer (20).

15. The liquid crystal display element according to claim 14,

the second viewing angle compensation plate (22) has a compensation layer (23) and a base material (24),

the compensation layer (23) is formed by discotic liquid crystals of hybrid orientation,

the base material (24) is formed of triacetyl cellulose, and supports the compensation layer (23).