JP2003307735A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a gradation inverting phenomenon without depending on observing direction in a liquid crystal display device having liquid crystal regions where liquid crystal molecules are axis-symmetrically aligned in every pixel region, excellent visual field angle characteristics and high contrast. <P>SOLUTION: A phase difference compensation element having negative double refractivity and the relation n<SB>x</SB>>n<SB>y</SB>>n<SB>z</SB>about main refractive indices n<SB>x</SB>and n<SB>y</SB>in an intra-surface direction and the main refractive index n<SB>z</SB>in the thickness direction is disposed between a liquid crystal cell wherein liquid crystal molecules are nearly vertically aligned when no voltage is applied and liquid crystal molecules are axis-symmetrically aligned in every liquid crystal region and a polarizing plate disposed in a orthogonally crossed nicols state. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal display device. In particular, the present invention relates to a liquid crystal display device having a wide viewing angle characteristic, which is suitably used for a flat display such as a personal computer, a word processor, an amusement machine, a television device, a display device utilizing a shutter effect, and the like.

[0002]

2. Description of the Related Art As a liquid crystal display device having the above-mentioned wide viewing angle characteristics, the present inventors have proposed a display mode (axially symmetry) in which liquid crystal molecules are oriented in axial symmetry for each picture element.
etric Aligned Microcell M
The mode: ASM mode) is disclosed in Japanese Patent Laid-Open No. 7-120728. This method is a technique for orienting liquid crystal molecules in an axially symmetric manner from a mixture of liquid crystal and a photocurable resin by using phase separation. Vertically oriented Np
It is a display mode using a liquid crystal material.

In this conventional ASM mode liquid crystal display device, a liquid crystal material having a positive dielectric anisotropy Δε is used. This display mode has excellent display characteristics in all directions because the liquid crystal molecules are oriented in axial symmetry,
When the absorption axis of the polarizing plate is in a crossed crossed Nicol state, the viewing angle characteristics tend to deteriorate. In addition, there is a problem that the area of the light shielding portion of the BM (black matrix) must be set large in order to prevent light leakage when the voltage is turned off. Furthermore, this conventional ASM mode is difficult to manufacture because it uses a phase separation process that requires complicated temperature control to obtain an axially symmetric alignment of liquid crystal molecules.
Further, there is a problem in that the obtained axially symmetric orientation is unstable, and the reliability is low especially at high temperatures.

As a means for solving these problems, the inventors of the present invention have disclosed in Japanese Patent Application No. 8-341590 that each pixel region has a liquid crystal region in which liquid crystal molecules are axisymmetrically aligned, and an omnidirectional viewing angle is set. It proposes a high-contrast liquid crystal display device having excellent characteristics and a manufacturing method capable of manufacturing the liquid crystal display device relatively easily.

In the proposed liquid crystal display device, a liquid crystal layer composed of liquid crystal molecules having a negative dielectric anisotropy (Δε <0) is sandwiched between a pair of substrates and is perpendicular to the surfaces of both substrates in contact with the liquid crystal layer. An alignment layer is provided. Moreover, at least one of the substrates is provided with a convex portion so as to surround the pixel region. Further, a pair of polarizing plates are arranged with a pair of substrates sandwiched therebetween so that their absorption axes are orthogonal to each other. According to this liquid crystal display device, the liquid crystal molecules are aligned substantially perpendicular to the pair of substrates when no voltage is applied, and the liquid crystal molecules are aligned in each pixel area when a voltage is applied, without requiring a particularly complicated manufacturing process. It is possible to realize an orientation state in which the orientation is axially symmetrical.

[0006]

According to the above proposed liquid crystal display device, the liquid crystal molecules are aligned in a direction substantially perpendicular to the pair of substrates when no voltage is applied. A good black state can be obtained in the viewing angle direction parallel to, and a high-contrast display can be obtained. However, in the case of observing while changing the viewing angle, (i) the viewing angle dependence is caused by the characteristics of the polarizing plate itself, and (ii) the retardation value of the liquid crystal molecules aligned vertically changes depending on the direction. Due to the fact that the retardation value of the liquid crystal layer depends on the viewing angle, light leakage is observed and the contrast ratio decreases.

Among these, the viewing angle dependency due to the characteristics of the polarizing plate itself is as follows. In the wide viewing angle mode liquid crystal display device, when light incident from the polarization axis (transmission axis) direction of the polarizing plate traverses the index ellipsoid of the liquid crystal layer, it has only ordinary light or extraordinary light components. However, when light incident from an oblique direction whose azimuth angle is deviated from the absorption axis of the polarizing plate by 45 ° crosses the refractive index ellipsoid of the liquid crystal layer, it has both ordinary and extraordinary light components and thus becomes elliptically polarized light. Apparently, light leakage becomes noticeable in a state where the absorption axes of the polarizing plates which are orthogonal to each other are opened.

The viewing angle dependence of the retardation value of the liquid crystal layer is as follows. In the above liquid crystal display device, since liquid crystal molecules are aligned in a direction substantially perpendicular to the pair of substrates when no voltage is applied, the retardation value varies depending on the viewing angle when observed obliquely, and the viewing angle dependence is observed. Will be done.

Due to the synergistic effect of the viewing angle dependency of the polarizing plate itself and the viewing angle dependency of the liquid crystal layer, there is a particularly bad viewing angle characteristic in a direction deviated by 45 ° from the absorption axis of the polarizing plates which are orthogonal to each other. It happens. For example, in the direction of 45 ° with respect to the absorption axis direction of the polarizing plate, there is a problem that the contrast remarkably decreases at a constant viewing angle, for example, about 35 ° to 50 °, and the gradation characteristic is reversed. In particular, the display characteristics were greatly deteriorated during the halftone display.

The present invention has been made to solve the above-mentioned problems of the prior art, and solves the deterioration of the viewing angle characteristics due to the deviation from the absorption axis, and has a liquid crystal display having a viewing angle characteristic of substantially axial symmetry. The purpose is to provide a device.

[0011]

A liquid crystal display device according to the present invention includes a liquid crystal cell sandwiched between a pair of substrates and having a liquid crystal layer composed of liquid crystal molecules having negative dielectric anisotropy, and the liquid crystal cell sandwiched therebetween. A pair of polarizing plates whose absorption axes are orthogonal to each other, and a phase difference compensating element provided at least at least between the pair of polarizing plates and the liquid crystal cell. A liquid crystal display device in which the pair of substrates have a vertical alignment layer on the surface on the liquid crystal layer side, and the liquid crystal molecules are aligned in axial symmetry in each of the plurality of liquid crystal regions when a voltage is applied. And the phase difference compensating element has a negative birefringence,
X orthogonal to each other respectively, y, and z-axis to the three principal refractive indices n _x, n _y, has a n _z, and the main refractive index in the plane direction of the liquid crystal cell n _x, and n _y, wherein the principal refractive index in the thickness direction of the liquid crystal cell when a n _z, has a relation of _{n x> n y> n z} ,
Thereby, the above object is achieved.

The phase difference compensating element may be provided between the pair of polarizing plates and the liquid crystal cell.

The retardation compensating element comprises a biaxial film having retardation in the in-plane direction and a thickness direction, or a uniaxial film having retardation in the in-plane direction and a uniaxial film having retardation in the thickness direction. It may consist of laminated films laminated together.

The x-axis direction of the phase difference compensating element is preferably arranged so as to be substantially orthogonal to the absorption axis of the polarizing plate adjacent to the phase difference compensating element.

The shift between the x-axis direction of the phase difference compensating element and the direction orthogonal to the absorption axis of the polarizing plate is preferably 1 ° or less.

When the birefringence of the liquid crystal molecules is Δn, the average thickness of the liquid crystal layer is d _LC , and the thickness of the retardation compensation element is d _f , the in-plane direction of the retardation compensation element is it is preferable retardation value d _f (n _x -n _y) is smaller than the retardation value d _LC · [Delta] n of the liquid crystal layer.

The phase difference compensating element is 0.035 ≦ {d
_{f (n x -n y)}} / It is preferable to satisfy the _{(d LC · Δn) ≦ 0.15} .

When the birefringence of the liquid crystal molecules is Δn, the average thickness of the liquid crystal layer is d _LC , and the thickness of the phase difference compensating element is d _f , the thickness direction of the phase difference compensating element is The retardation value d _f (n _x −n _z ) is preferably smaller than the retardation value d _LC · Δn of the liquid crystal layer.

The retardation value d _f (n _x −n _z ) in the thickness direction of the phase difference compensating element is preferably larger than 0. Furthermore, it is preferable that the ratio between the in-plane direction of the retardation compensation element retardation value d _f (n _x -n _y) and thickness direction retardation values d _f (n _x -n _z) is 2 or more the in-plane direction of the retardation compensation element retardation value d _f (n _x -n _y) and thickness direction retardation values d _f (n
It is even more preferable that the ratio of ( _{x- nz} ) is 3 or more and 6 or less.

The average refractive index of the phase difference compensating element is 1.4
It is preferable that it is 1.7 or less.

Retardation value d _LC · Δn of the liquid crystal layer
Is preferably in the range of 300 to 550 nm.

Of the pair of polarizing plates, an antireflection film or an antiglare antiglare layer may be provided on the surface of the polarizing plate on the viewer side. An antireflection film is preferably provided on the surface of the antiglare antiglare layer.

The operation of the present invention will be described below.

According to the present invention, in a liquid crystal display device in which liquid crystal molecules are vertically aligned when a voltage is not applied and are axially symmetrical or concentric in each pixel region when a voltage is applied, a pair of liquid crystal display devices arranged in an orthogonal crossed Nicol state. Has a negative birefringence between at least one of the polarizing plates and the substrate adjacent thereto, and has a principal refractive index n _x , n _y in the in-plane direction and a principal refractive index in the thickness direction. the n _x> n _y> be provided (retardation film or the retardation plate typically) retardation compensation element having a relationship of n _z for n _z, the viewing angle dependence and the liquid crystal layer due to the characteristics of the polarizing plate itself By compensating for the viewing angle dependence of the retardation value, it is possible to make the isocontrast contour curve circular regardless of the observation direction. Further, the liquid crystal layer has an excellent viewing angle characteristic because it changes between the vertical alignment and the axisymmetric alignment depending on the voltage. Furthermore, since a normally black mode display in which a liquid crystal material having a negative dielectric anisotropy is used to achieve a vertical alignment state when no voltage is applied, high contrast display is possible.

This phase difference compensating element may be provided between one of the pair of polarizing plates and the substrate adjacent thereto, and between each of the pair of polarizing plates and the substrate adjacent thereto. You may provide one piece at a time.

This retardation compensating element may be a biaxial film having retardations in the in-plane direction and the thickness direction, a laminated film of two biaxial films, or an in-plane direction. A laminated structure having a uniaxial film having retardation and a uniaxial film having retardation in the thickness direction can be similarly used.

In this phase difference compensating element, the n _x direction of the main refractive index is arranged so as to be substantially orthogonal to the absorption axis of the polarizing plate adjacent to the phase difference compensating element,
The compensating function of the viewing angle dependency can be sufficiently exerted.

As described in the embodiments described later, if the deviation between the slow axis of the phase difference compensating element and the direction orthogonal to the absorption axis of the polarizing plate is larger than 1 °, the polarized light under the polarizing plate crossed Nicols is polarized. Performance is degraded and light leakage occurs, and a sufficient black level and contrast cannot be obtained. Therefore, there is a deviation of 1 between the slow axis of the phase difference compensation element and the direction orthogonal to the absorption axis of the polarizing plate.
It is desirable that the angle is not more than °.

With respect to the birefringence Δn of the liquid crystal molecules, the average thickness d _LC of the liquid crystal layer, and the thickness d _f of the retardation compensation element, the in-plane retardation value d _f (n _x -n) of the retardation compensation element _y )
Is smaller than the retardation value d _LC · Δn of the liquid crystal layer, the effect of compensating for the viewing angle dependency can be increased. In particular, the retardation value d _LC of the in-plane retardation value d _f of the phase difference compensating element (n _x -n _y) liquid crystal layer,
By setting the range of 3.5% to 15% of Δn, as shown in FIG.
It is possible to obtain a high-contrast display as shown in FIG.

With respect to the birefringence Δn of the liquid crystal molecules, the average thickness d _LC of the liquid crystal layer, and the thickness d _f of the retardation compensation element, the retardation value d _f (n _{x in} the thickness direction of the retardation compensation element −
By making _nz ) smaller than the retardation value d _LC · Δn of the liquid crystal layer, the effect of compensating for the viewing angle dependency can be increased. In particular, when the retardation value d _f (n _x −n _z ) in the thickness direction of the phase difference compensating element is set within the range of 30% to 80% of the retardation value d _LC · Δn of the liquid crystal layer, the effect of the phase difference compensating element is obtained. It is possible to obtain a display with good color characteristics while increasing the display size.

The in-plane direction of the retardation compensation element retardation value d _f (n _x -n _y) and thickness direction retardation values d _f
(N _x -n _z) and of the ratio (or refractive index difference ratio) is desirably greater than 0. This is because, as shown in an embodiment described later, when the ratio of both retardation values is larger than 0, that is, when the retardation value in the thickness direction is not 0, the viewing angle compensation effect occurs. In particular, when the ratio of both retardation values is 2 or more, the contrast ratio is 10 and the viewing angle is 60.
It is possible to realize a good display state of ≧ °. Further, when the ratio of both retardation values is 3 or more and 6 or less,
With a contrast ratio of 20, a more excellent display state with a viewing angle of 60 ° or more can be realized. As the material of the phase difference compensating element, a polymer material such as polycarbonate having an average refractive index of 1.4 or more and 1.7 or less can be used,
A retardation compensating element which is transparent (transmittance of 90% or more) in the visible light region can be obtained.

Here, the retardation value d _LC ·
By setting Δn in the range of 300 to 550 nm, it is possible to improve the viewing angle characteristics at the time of applying a voltage and prevent grayscale inversion, and as shown in an embodiment described later, the contrast ratio is 10 and the viewing angle is 60 ° or more. A good display state of is obtained.

By providing an antireflection film or an antiglare antiglare layer on the surface of the front polarizing plate of the pair of polarizing plates, the effect of compensating for the viewing angle dependency can be enhanced. Further, by providing an antireflection film on it, the effect of compensating the viewing angle dependency can be further enhanced.

When a phase difference compensating element is provided, coloring may occur in the wide viewing angle direction, but an antiglare antiglare layer is provided on the surface of the polarizing plate on the front side, and an antireflection film is further provided on the surface. By providing, it is possible to compensate for this coloring.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. (Basic Operation) The operation principle of the liquid crystal display device 100 according to the present invention will be described with reference to FIG. 1A and 1B show a state when no voltage is applied, and FIGS. 1C and 1D show a state when a voltage is applied. Note that FIG.
1A and 1C are cross-sectional views, and FIGS. 1B and 1D are views showing the results of observing the upper surface with a polarization microscope in a crossed Nicols state.

The liquid crystal display device 100 includes a pair of substrates 3
A liquid crystal layer 40 composed of liquid crystal molecules 42 having a negative (Nn-type) dielectric anisotropy (Δε) is sandwiched between 2 and 34. Vertical alignment layers 38a and 38b are formed on the surfaces of the pair of substrates 32 and 34 in contact with the liquid crystal layer 40. A convex portion 36 is formed on the surface of at least one of the pair of substrates 32 and 34 on the liquid crystal layer 40 side. Due to this convex portion 36, the liquid crystal layer 40 has two different thicknesses, dout and din. As a result, as will be described later, the liquid crystal region that exhibits an axially symmetric orientation when a voltage is applied is defined as a region surrounded by the convex portions 36. Note that, in FIG. 1, the electrodes formed on the pair of substrates 32 and 34 for applying a voltage to the liquid crystal layer 40 are omitted.

In this liquid crystal display device 100, when no voltage is applied, as shown in FIG. 1A, the liquid crystal molecules 42 are aligned in the direction perpendicular to the substrate by the alignment regulating force of the vertical alignment layers 38a and 38b. When observing the pixel area without voltage applied with a crossed Nicols polarization microscope,
A dark field is exhibited as shown in (b) (normally black mode).

On the other hand, when a voltage is applied to the liquid crystal display device 100, a force acts on the liquid crystal molecules 42 having negative dielectric anisotropy so that the long axes of the liquid crystal molecules are aligned perpendicular to the direction of the electric field. As shown in FIG. 1 (c), it is tilted from the direction perpendicular to the substrate (halftone display state). In addition, in this FIG.1 (c), 44 shows a central axis. When the picture element region in this state is observed with a polarization microscope in the crossed Nicols state, an extinction pattern is observed in the direction along the absorption axis as shown in FIG.

FIG. 2 shows a liquid crystal display device 100 according to the present invention.
3 shows the voltage transmittance curve of The horizontal axis represents the voltage applied to the liquid crystal layer, and the vertical axis represents the relative transmittance.

When the voltage is increased from the normally black state when no voltage is applied, the transmittance gradually increases. Here, the voltage at which the relative transmittance becomes 10% is called Vth (threshold voltage). When the voltage is further increased, the transmittance further increases and reaches saturation. The voltage at which this transmittance is saturated is Vst
Call. The voltage applied to the liquid crystal layer 40 is from 1/2 Vth to V
When it is between st, the transmittance reversibly changes within the operation range shown in FIG. When a voltage near 1/2 Vth is applied, the liquid crystal molecules are almost vertically aligned with respect to the substrate, but the symmetry with respect to the central axis of the axisymmetric alignment is noted, and the voltage exceeding 1/2 Vth is recorded. It is considered that the reversible state reverts to the axially symmetric orientation state by applying. However, when the applied voltage becomes lower than 1/2 Vth, the liquid crystal molecules return to a substantially vertical alignment state. Therefore, when the voltage is applied again, the tilt direction of the liquid crystal molecules cannot be uniquely determined. Since it exists, the transmittance is not stable.

At the stage of injecting the Nn type liquid crystal material into the liquid crystal cell, the same behavior as when the applied voltage is lower than 1/2 Vth is obtained. Therefore, once a voltage of 1/2 Vth or more is applied, the plurality of central axes becomes one in the area surrounded by the convex portion 36 (corresponding to the pixel area), and the voltage transmission shown in FIG. It exhibits a rate characteristic.

The "picture element" is generally defined as the minimum unit for displaying, and in the present specification, the "picture element area" means a partial area of the liquid crystal display element corresponding to the "picture element". Point to. In the case of a picture element with a large aspect ratio (long picture element), a plurality of picture element regions may be formed for one long picture element,
The number of picture element regions formed corresponding to each picture element is preferably as small as possible as long as the axially symmetric orientation can be stably formed. Further, in the present specification, the “axially symmetric orientation” refers to an orientation state such as a radial shape, a concentric circular shape (tangential shape), and a spiral shape.

(Liquid Crystal Material) The liquid crystal material used in the present invention is a so-called Nn type liquid crystal material having a negative dielectric anisotropy (Δε <0). The magnitude of the absolute value of Δε can be appropriately set depending on the application, and generally, it is preferable to have a large absolute value from the viewpoint of reducing the driving voltage.

D _LC · Δn (retardation) when a voltage is applied is an important factor that influences important characteristics of the apparatus such as transmittance and viewing angle characteristics of the apparatus. In the display mode of the present invention, it is not always necessary to limit the retardation peculiar to the liquid crystal cell determined by the product of Δn peculiar to the liquid crystal material and the liquid crystal layer thickness d _LC to the optimum value.

FIG. 3 shows the optimum value of retardation (first minimum condition for maximum transmittance: d _LC · Δn = 55).
3 shows a voltage transmittance curve of a liquid crystal display device having a retardation value larger than 0 nm).

In such a liquid crystal display device, it is not necessary to use a region beyond the maximum point of relative transmittance, and the liquid crystal display device may be driven in a region where the relative transmittance monotonously increases. That is, the voltage at which the relative transmittance becomes maximum in FIG. 3 may be set as the maximum drive voltage (Vmax).

In the present invention, the retardation value at the maximum driving voltage used is important. Here, the apparent Δn (refractive index anisotropy: value at the maximum driving voltage) of liquid crystal molecules and the average thickness d _{LC of the} liquid crystal layer when the liquid crystal cell was manufactured.
Product d _LC · Δn (retardation value) of about 300 nm ~
550 nm is preferable, and further 300 nm
It is preferably ˜500 nm. In this range, the transmittance when voltage is applied and the viewing angle characteristic when no voltage is applied are good, and the so-called gradation inversion (contrast inversion) phenomenon in which the relationship between the magnitude of the applied voltage and the transmittance is reversed depending on the viewing angle does not occur.

On the other hand, the point at which the transmittance becomes maximum is the second minimum condition (retardation value: 1000 nm to
1400 nm), but in this range, the viewing angle characteristics when no voltage is applied are inferior, and a gradation inversion (contrast inversion) phenomenon may occur.

Hereinafter, d _LC · Δn will be described in more detail with reference to two simulation results performed by the present inventors.

(1) First, Δn of the liquid crystal material is about 0.08.
In order to optimize the biaxial retardation compensator so that the liquid crystal cell thickness is changed from 4 μm to 8 μm and the equal contour viewing angle characteristics are maximized for each d _LC · Δn. , An electro-optical experiment (simulation) was performed.
Then, the relationship between the viewing angle characteristics, the gradation inversion, the transmittance, and the retardation was evaluated. In calculating the contrast ratio, 1 is applied when the applied voltage (10 V) at which the transmittance is saturated.
The voltage with a transmittance of 0.1% was used for the black level, and the voltage with a transmittance of 95% was used for the white level.

4 and 5 show contrast ratios 10 and 20.
Viewing angle θ, FIG. 6 shows contrast reversal angle θ, and FIG. 7 shows 10
The transmittance at the time of applying V is the retardation d of each liquid crystal cell.
It is the figure plotted with respect to _LC * (DELTA) n. Here, as the phase difference compensating element, one having a ratio of the in-plane refractive index difference to the refractive index difference in the thickness direction (normal direction) of 4.5 was used. Here, the azimuth angle Φ = 0 is the absorption axis direction of the lower polarizing plate.

From the results shown in FIG. 4, when the contrast ratio is 10, d _LC having a characteristic that the viewing angle in all directions is 60 ° or more.
The region of Δn is 300 nm to 550 nm, and d _LC
It can be seen that Δn is preferably within this range.

Further, as shown in FIG. 5, when the contrast ratio is 20, it can be seen that the viewing angle decreases as d _LC · Δn increases. Further, it can be seen from FIG. 6 that the reversal angle is 60 ° or more in all directions and the range in which a substantially circular viewing angle characteristic is obtained is in the range of 300 nm to 400 nm. Therefore, as a preferable range for a case where a contrast ratio of 20 is required or a case where a substantially circular viewing angle characteristic is required, d _LC · Δn is 300 nm to 40 nm.
It is 0 nm.

On the other hand, it is generally known that when the retardation of the liquid crystal cell exceeds the first minimum condition, the display performance (viewing angle and reversal angle characteristic) is remarkably reduced, but as shown in FIG. D _LC · Δ for which the transmittance is obtained
n is 550 nm. Therefore, this point is the first minimum of the liquid crystal material, and it is understood that sufficient display performance cannot be obtained under the condition of the liquid crystal cell exceeding 550 nm.

(2) Next, the cell thickness of the liquid crystal cell is fixed at 5 μm, and Δn of the material is changed from 0.07 to 0.1,
An electro-optical experiment (simulation) was performed in order to optimize the biaxial retardation compensation element so that the equal contour viewing angle characteristic was maximized for each d _LC · Δn. Then, the relationship between the viewing angle characteristics, the gradation inversion, the transmittance and the retardation was evaluated. In the calculation of the contrast ratio, the applied voltage (10 V) at which the transmittance saturates is 100%.
A voltage with a transmittance of 0.1% was used for the black level, and a voltage with a transmittance of 95% was used for the white level.

8 and 9 show contrast ratios 10 and 20.
Viewing angle θ, FIG. 10 shows the contrast reversal angle θ, and FIG. 11 shows
The transmittance when 10 V is applied is measured by the retardation of each liquid crystal cell.
Nd _LC-It is the figure plotted with respect to (DELTA) n. here,
As the phase difference compensating element, the in-plane refractive index difference and the thickness direction (method
The ratio to the refractive index difference in the (line direction) was set to 4.5.
It was

From the results of FIG. 8, when the contrast ratio is 10, d _LC having the characteristic that the viewing angle in all directions is 60 ° or more.
The region of Δn is 300 nm to 550 nm, and d _LC
It is preferable that Δn is within this range.

Further, as shown in FIG. 9, it can be seen that when the contrast ratio is 20, the viewing angle decreases as d _LC · Δn increases. Further, it can be seen from FIG. 10 that the reversal angle is 60 ° or more in all directions and the range in which a substantially circular viewing angle characteristic is obtained is in the range of 300 nm to 400 nm. Therefore, as a preferable range for a case where a contrast ratio of 20 is required or an application where a substantially circular viewing angle characteristic is required, d _LC · Δn is 300 nm to 4 nm.
00 nm.

On the other hand, as shown in FIG. 11, as the retardation of the liquid crystal cell increases, the transmittance when 10 V is applied increases.

From the above simulation results of (1) and (2), the optimum d _LC in the liquid crystal display device of the present invention is obtained.
It can be said that the region of Δn is 300 nm to 550 nm, and more preferably 300 nm to 400 nm.

The twist angle of the liquid crystal molecules in the liquid crystal layer is also one of the important factors determining the transmittance of the liquid crystal display device, and the twist angle at the maximum drive voltage is as important as the retardation value in the present invention.

When the maximum drive voltage is applied, the twist angle is 45 to
It is preferably 110 °, and is 10 from the viewpoint of transmittance.
It is more preferably 0 °.

Since the present invention uses Nn type liquid crystal molecules, the apparent twist angle of the liquid crystal molecules depends on the voltage. The twist angle when no voltage is applied is almost 0 °, and the twist angle increases as the voltage increases. When a sufficient voltage is applied, the twist angle approaches the twist angle inherent to the liquid crystal material.

Both the twist angle and the retardation value at the maximum drive voltage are preferably within the preferable ranges, and in this case, the transmittance can be more effectively brought close to the maximum value.

(Photocurable Resin) As described above with reference to FIG. 2, it is preferable to always apply a voltage of 1/2 Vth or more to the liquid crystal display device of the present invention.

When a voltage is applied to the liquid crystal molecules aligned perpendicular to the substrate, the direction in which the liquid crystal molecules fall is not uniquely determined, and as a result, a phenomenon in which a plurality of central axes are transiently formed occurs. On the other hand, when the voltage is continuously applied, the only central axis is formed in the region defined by the convex portion, and this state is stable as long as the voltage of 1/2 Vth or more is applied.

Therefore, in order to stabilize the axially symmetric orientation, 1
By applying a voltage of / 2Vth or more, by curing the photo-curable resin mixed in the liquid crystal material in advance, an axisymmetric alignment fixed layer can be formed on the surface in contact with the liquid crystal layer. This makes it possible to stabilize the axially symmetrical alignment of liquid crystal molecules. After curing the photocurable resin, 1
Even if a voltage of / 2Vth or more is removed, a plurality of central axes are not formed, and an axisymmetric orientation is formed with good reproducibility.

As the photocurable resin, acrylate type, methacrylate type, styrene type and derivatives thereof can be used. By adding a photopolymerization initiator to these resins, the photocurable resin can be cured more efficiently. A thermosetting resin can also be used.

Since the optimum amount of the curable resin varies depending on the material, it is not particularly limited in the present invention, but the resin content (% to the total weight including the liquid crystal material) is about 0.1.
% To 5% is preferable. If it is less than about 0.1%, the axially symmetric alignment state cannot be stabilized by the cured resin, and if it exceeds about 5%, the effect of the vertical alignment layer is obstructed and the liquid crystal molecules are displaced from the vertical alignment. The rate is increased (light is emitted) and the black state is deteriorated when the voltage is OFF.

(Phase Difference Compensation Element) As described in the section of the prior art, when a vertically aligned liquid crystal material is sandwiched between two orthogonal polarizing plates, a good black state can be obtained in the front direction, and A display of contrast is obtained. However, when observed by changing the viewing angle, light leakage is observed due to (i) the viewing angle dependency due to the characteristics of the polarizing plate itself and (ii) the viewing angle dependency due to the retardation of the liquid crystal layer, and the contrast ratio decreases. Happens.

Therefore, in the present invention, the phase difference compensating element is arranged between at least one of the pair of polarizing plates and the substrate adjacent thereto. The retardation compensation element is composed of a retardation plate or a plurality of retardation plates. Also,
The retardation plate includes a retardation film.

FIG. 12 is a perspective view showing the direction of the main refractive index of the phase difference compensating element used in the present invention. Here, an orthogonal coordinate system in which a plane parallel to the surface of the phase difference compensating element is defined as an xy plane is defined, and the three main refractive indices of the index ellipsoid of the phase difference compensating element are defined as n _x , n _y , and n. _{Let z} . The principal refractive index in the in-plane direction is defined as n _x and n _y, and the principal refractive index in the thickness direction is defined as n _z . This phase difference compensating element has a negative birefringence index, and has a relationship of n _x > n _y > n _z with respect to principal refractive indices n _x and n _y in the in-plane direction and principal refractive index n _{z in the} thickness direction. . In the phase difference compensating element satisfying this relationship, the direction of the maximum principal refractive index n _x (x-axis direction) is the slow axis direction.

Examples of the material of such a phase difference compensating element or the phase difference plate or the phase difference film constituting the phase difference compensating element include polycarbonate, polyvinyl alcohol,
Polystyrene, polymethylmethacrylate (PMM
A), liquid crystalline polymers, cellulose triacetate, and other polymeric materials that are transparent (transmittance 90% or more) in the visible light region, and the average refractive index of these materials is about 1.4 or more and about 1.
It is 7 or less.

For this retardation compensating element, a laminated retardation film or the like in which a plurality of retardation films are laminated with different azimuth angles of the respective optical axes may be used. Even when a laminated retardation film obtained by laminating a uniaxial film having retardation in the in-plane direction and a uniaxial film having retardation in the thickness direction is used, it has retardation in the in-plane direction and the thickness direction 2 Even when an axial film is used, the effect of improving the viewing angle characteristics can be similarly obtained. Alternatively, it may be a film in which two biaxial retardation films are laminated.

As shown in FIG. 13A, the liquid crystal cell 13
Polarizing plates 132a and 132b are arranged so as to sandwich both sides of 4,
2 between the polarizing plates 132a and 132b and the liquid crystal cell 134.
The liquid crystal display device in which the axial retardation films 133a and 133b are arranged and the backlight 131 is arranged on the back side of the polarizing plate 132a may have the following configuration, for example.

As shown in FIGS. 13B and 13C, at least one of the polarizing plates 132a and 132b is
The polarizing layers 136a and 136b are respectively a pair of support films 135a and 137a, or a support film 135b.
And 137b sandwiched and supported, and the polarizing plates 132a and 132b have retardation in the in-plane or in the normal direction of the plane, which are generally commercially available (for example, Nitto Denko Corporation or Sumitomo Chemical). (Available from Kogyo Co., Ltd.) may be used. In this case, the retardation of the phase difference compensating element used for the viewing angle compensation in the liquid crystal display device of the present invention includes the retardations of the polarizing plates 132a and 132b, and the viewing angle characteristic is improved by adjusting the value of the retardation according to the present invention. The effect is obtained. Although the support films are provided on both sides of the polarizing layer in the above example, they may be provided on one side.

As the supporting film, for example, TAC
(Triacetic acid cellulos
e), PET (polyethylene teleph)
thalate), PETG (polyethylen)
Eglycol), PMMA (polymethyl)
Methacrylate), PC (polycarb)
onate), ARTON, ZENOX, etc., uniaxial or biaxial film can be used. In particular, TAC is harder than a retardation film, and thus is suitably used as a support film. The support film made of TAC has, for example, a retardation of about 50 to about 60 nm in the normal direction and a retardation of about 5 to about 10 nm in the in-plane direction.

This phase difference compensating element may be provided between one of the polarizing plates and the substrate adjacent thereto, or may be provided between both of the polarizing plates and the substrate adjacent thereto.

Of the main refractive index of this phase difference compensating element, n
The direction of _x and the absorption axis of the polarizing plate adjacent to the phase difference compensating element are preferably arranged at an angle of 45 ° to 135 °.
It is more preferable to arrange at an angle of 7 ° to 113 °.
Further, it is preferable that the both are orthogonal to each other because the function of compensating for the viewing angle dependency due to the characteristics of the polarizing plate itself and the viewing angle dependency due to the retardation of the liquid crystal layer can be sufficiently exhibited.

When evaluated under a crossed Nicols polarizing plate, as shown in FIG. 14, when the orthogonal accuracy of the slow axis of the phase difference compensating element and the absorption axis of the polarizing plate is larger than 1 °, the polarization The polarization degree performance under the plate crossed Nicols deteriorated to cause light leakage, and sufficient black level and contrast could not be obtained. Therefore, it is desirable that the deviation between the direction of the main refractive index n _x of the phase difference compensation element and the direction orthogonal to the absorption axis of the polarizing plate is 1 ° or less.

When the birefringence Δn of the liquid crystal molecules, the average thickness d _LC of the liquid crystal layer, and the thickness d _f of the retardation compensating element, the in-plane retardation value d _f (n _x −n _y ) of the retardation compensating element is given. Is preferably smaller than the retardation value d _LC · Δn of the liquid crystal layer. More preferably, the retardation value d of the liquid crystal layer
It is in the range of 3.5% to 15% of _LC · Δn. If it is less than 3.5%, the effect of improving the viewing angle characteristics may be low, and if it exceeds 15%, the change in color tone may be large when the viewing angle is tilted.

Further, it is preferable that the retardation value d _f (n _x −n _z ) of the retardation compensation element in the thickness direction is smaller than the retardation value d _LC · Δn of the liquid crystal layer. More preferably, the retardation value d _LC · Δn of the liquid crystal layer is 30% to
It is in the range of 80%. If it is less than 30%, the effect of the phase difference compensating element is small, and if it exceeds 80%, coloring may become large in the wide viewing angle direction.

The mechanism of viewing angle compensation by the phase difference compensating element will be described below by taking the case of the normally black mode as an example.

Generally, from the polarization characteristics of the polarizing plate and the optical characteristics of the axisymmetric alignment of the liquid crystal molecules, the viewing angle characteristics are deteriorated in the azimuth angle of 45 ° with respect to the absorption axis of the polarizing plate as compared with the axial direction. I know.

As shown in FIG. 15, for a liquid crystal cell in which only a polarizing plate is arranged without providing a phase difference compensating element,
When the viewing angle is tilted diagonally from the front when the voltage is off,
As shown in FIG. 16, the apparent refractive index changes due to the index ellipsoid. Therefore, the optical characteristics change and good viewing angle characteristics cannot be obtained.

On the other hand, as shown in FIG. 17, with respect to a liquid crystal cell provided with a phase difference compensating element, even when the viewing angle is inclined obliquely from the front in the direction of 45 ° with respect to the absorption axis of the polarizing plate when the voltage is off. As shown in FIG. 18, since the apparent refractive index ellipsoid is almost spherical, the optical characteristics hardly change even when the liquid crystal cell is viewed obliquely. Therefore, as shown in FIGS. 19 and 20, even when the viewing angle is tilted when the voltage is off and the voltage is on, the black display and the white display are apparently the same as when viewed from the front. The angular characteristics are well compensated. Further, as for the absorption axis direction of the polarizing plate, FIG.
As shown in FIG. 24, the original viewing angle characteristics are not deteriorated even if the phase difference compensation element is provided. Therefore, good viewing angle characteristics can be obtained in all directions.

In the above simulations (1) and (2), the ratio of the refractive index difference in the in-plane direction of the phase difference compensating element (retardation film) to the refractive index difference in the thickness direction was set to 4.
The results of evaluating the relationship between the retardation in the in-plane and normal directions of the optimal retardation film of No. 5 and the retardation of the liquid crystal cell are shown in FIGS. 25 and 26, respectively. From these figures, it can be seen that the optimal retardations in the in-plane direction and the thickness direction increase as d _LC · Δn increases.

[0088] Incidentally, the ratio between the retardation value of the in-plane direction of the retardation compensation element d _f (n _x -n _y) and thickness direction retardation values _{d f (n x -n z)} ( or the refractive index difference ratio )
Is preferably larger than 0 as shown in FIGS. This is because when the ratio of the two retardation values is not 0, that is, when the retardation value in the thickness direction (normal direction) is not 0, the viewing angle compensation effect occurs.

Further, as shown in FIGS. 27 and 29,
Refractive index difference ratio between in-plane direction and thickness direction (retardation ratio)
When 2 is 2 or more, a good display state with a contrast ratio of 10 and a viewing angle of 60 ° or more can be realized.

Here, the viewing angle of 60 ° or more is defined because the viewing angle of a TN mode liquid crystal display device which is generally used at present is 60 °. On the other hand, the contrast ratio of 10 is specified because the contrast ratio of a general wide viewing angle mode is about 10. Further, in order to realize a viewing angle of 70 ° or more in consideration of a liquid crystal display mode such as IPS or VA with a contrast ratio of 10, it is preferable that the refractive index difference ratio is 2.5 or more.

In particular, as shown in FIG. 28, the refractive index difference ratio 3
When the ratio is 6 or less, a more excellent viewing angle compensation effect with a contrast ratio of 20 and a viewing angle of 60 ° or more can be obtained. In this graph, the portion with a refractive index difference ratio of 3 to 6 has a viewing angle of 45.
This is the part where the characteristics in the ° and 135 ° directions exceed the characteristics in the other directions. Therefore, in the range of the refractive index difference ratio of 3 or more and 6 or less, the viewing angle characteristics in the 45 ° and 135 ° directions are improved, and substantially circular viewing angle characteristics are obtained.

Here, the viewing angle of 60 ° or more is defined because the viewing angle of the TN mode liquid crystal display device which is generally used at present is 60 °. On the other hand, the reason why the contrast ratio 20 is defined is that good display characteristics can be realized under more severe conditions than in the general wide viewing angle mode.

(Vertical Alignment Layer) The vertical alignment layer may have a surface for vertically aligning liquid crystal molecules, and the material may be an inorganic material or an organic material. For example, polyimide type (JALS204 (Japan Synthetic Rubber) or 121
1 (Nissan Chemical Co., Ltd.) and inorganic compounds (EXP-OA003 (Nissan Chemical Co., Ltd.)) can be used.

(Polarizing Plate) By arranging the polarizing plates in the crossed Nicols state, a favorable black state in the normally black mode can be obtained when a vertically aligned liquid crystal material is sandwiched, and a high contrast display can be obtained. As this polarizing plate,
For example, polyvinyl alcohol film, polyvinyl formal film, polyvinyl acetal film,
Dehydration of iodine-based polarizing film, dye-based polarizing film, etc. in which iodine or hydrophilic polymer is adsorbed and oriented on a hydrophilic polymer film such as poly (ethylene-acetic acid) copolymer saponified film, and polyvinyl alcohol film It is possible to use a polyene-based polarizing film or the like in which polyene is oriented by treatment or dehydrochlorination of a polyvinyl chloride film.

Further, by providing an antireflection film or an antiglare antiglare layer on the surface of the polarizing plate, the viewing angle characteristics in the direction shifted by 45 ° with respect to the absorption axis direction can be further improved. In particular, this antiglare antiglare layer is a hardcoat layer that is antiglare treated. As the binder resin used in the hard coat layer, any resin can be used as long as it has a hard property and is transparent, and examples thereof include a thermosetting resin and an ionizing radiation curable resin. In the present invention, “having hard performance” or “hard coat” means JISK.
5400 shows a hardness of H or higher by the pencil hardness test.

Examples of the thermosetting resin include phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine-urea co-condensation resin, Silicon resin, polysiloxane resin, or the like can be used.

The ionizing radiation-curable resin can be cured by irradiation with an electron beam or ultraviolet rays. The ionizing radiation curable resin preferably has an acrylate-based functional group, for example, a relatively low molecular weight polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, spiro acetal resin, polybutadiene resin, Oligomers or prepolymers such as polythiol polyene resins and polyfunctional compound acrylates or methacrylates such as polyhydric alcohols can be used. Particularly preferred is a mixture of polyester acrylate and polyurethane acrylate.

The antiglare treatment applied to the hard coat layer is a treatment for forming external irregularities on the surface to scatter external light so that the reflected light does not directly enter the eyes of the observer. There are a method of using a mold film, a method of adding fine particles to a binder resin, and the like.

The method of using the shaped film is performed as follows, for example. First, an ionizing radiation curable resin composition is applied to the surface of a polarizing plate, and a mat-shaped patterning film having fine irregularities on the surface is laminated on the uncured coating film. Next, the laminated coating material is irradiated with ionizing radiation to completely cure the coating film, and then the patterning film is peeled off to form an antiglare layer having fine irregularities formed on the surface. It

Examples of the fine particles added to the binder resin include beads and fillers such as amorphous silica powder, polycarbonate particles, acrylate resin beads, and methacrylate resin beads.

Further, by providing an antireflection film (antireflection coating layer) on the surface of the polarizing plate in addition to the above antiglare antiglare layer, it is possible to obtain 4
It is possible to further improve the viewing angle characteristics in the direction shifted by 5 °. This antireflection film is for reducing reflected light by utilizing light interference, and for example, a film in which dielectric thin films made of an inorganic material are laminated can be used. As the inorganic material, for example, LiF, MgF ₂ , 3NaF · Al
F ₃ , AlF ₃ , SiO _x (x: 1.8 <x <2.2) and the like can be mentioned. The method of forming a thin film made of an inorganic material is preferably a vapor phase method, for example, vacuum deposition method, sputtering method,
An ion plating method, a plasma CVD method and the like can be mentioned.

Hereinafter, the embodiments of the present invention will be described more specifically, but the present invention is not limited thereto.

(Embodiment 1) A method of manufacturing the liquid crystal display device of Embodiment 1 will be described with reference to FIG. FIG. 31A is a sectional view of the liquid crystal display device of the first embodiment, and FIG. 31B is a plan view thereof.

First, the transparent electrode 63 (ITO: 10
A spacer 65 having a height of about 5 μm was formed outside the picture element region on the substrate 62 on which 0 nm) was formed using photosensitive polyimide. Next, a convex portion 66 having a height of about 3 μm was formed using an acrylic negative resist. Here, the size of the area surrounded by the convex portion 66, that is, the size of the picture element area is 100 μm.
× 100 μm. JALS204 (Nippon Synthetic Rubber) was spin-coated thereon to form a vertical alignment layer 68. Furthermore, a transparent electrode 64 (ITO: 100 μm) is formed on the surface.
The vertical alignment layer 67 was formed using the same material on the other substrate 61 on which m) was formed. After that, the both were stuck together to produce a liquid crystal cell.

Nn type liquid crystal material (Δε
= -4.0, Δn = 0.08, 9 with a cell gap of 5 μm
The twist angle peculiar to the liquid crystal material was set so that the twist was 0 °, the retardation value d _LC · Δn = 400 nm was injected, and a voltage of 7 V was applied. Immediately after the voltage application, in the initial state, a plurality of axially symmetric orientation axes existed, and when the voltage application state was continued, one axially symmetric orientation region (monodomain) was formed for each pixel region.

Next, as shown in FIG. 32, the liquid crystal cell 10
The polarizing plates 101 and 102 and the phase difference compensation elements 103 and 104 are arranged on both sides of 0 to complete the liquid crystal display device. FIG. 32 (a) is a layout view of the liquid crystal cell, the polarizing plate and the phase difference compensating element in the present embodiment, and FIG. 32 (b) shows the absorption axis direction of the polarizing plate and the three main refractive indices of the phase difference compensating element. It is a figure which shows the relationship with the direction of the nx which is the maximum of these, ie, the slow axis direction. As shown in FIG. 32, the upper polarizing plate 101 and the lower polarizing plate 102 were arranged on both outer sides of the liquid crystal cell 100 so that their absorption axes were orthogonal to each other. Further, the first retardation compensation element 103 is arranged between the upper polarizing plate 101 and the liquid crystal cell 100, and the lower polarizing plate 1
02 and the liquid crystal cell 100 between the second phase difference compensating element 1
04 was placed. Both the first phase difference compensating element 103 and the second phase difference compensating element 104 are phase difference compensating elements as shown in FIG. 12, and here, in-plane retardation value d _f (n _x −n _y ). the 42 nm, and the thickness direction retardation value d _f (n _x -n _z) and 170 nm.

In the structure of the obtained liquid crystal display device, the cross-sectional shape of the vertical alignment layer 68 is a mortar shape as shown in FIG. 31, and its thickness position (from the center of the pixel to the peripheral portion). The differential coefficient of the curve showing the change due to is positive, and the differential coefficient of the curve showing the change of the liquid crystal layer thickness in the pixel region is negative.

The axially symmetric orientation of the liquid crystal cell of the first embodiment is stable when a voltage of 1/2 Vth or more is applied, and when the voltage is lower than 1/2 Vth, the state of the axially symmetric orientation collapses and the initial state is obtained. I have returned to the state. When the voltage was applied again, the initial axially symmetric orientation had a plurality of central axes, and then an axially symmetric orientation having one central axis for each pixel region was obtained. This phenomenon did not change even after 20 times. Here, in order to measure the electro-optical characteristics of the liquid crystal cell of Embodiment 1, after applying a voltage of 1/2 Vth or more to form an axially symmetric state, the axially symmetric orientation is stable during the measurement of the electro-optical characteristics. It was measured in the voltage range (1/2 Vth or more).

FIG. 33 shows the electro-optical characteristics of the liquid crystal display device according to the first embodiment. As is clear from FIG. 33, in the liquid crystal display device of the first embodiment, the transmittance in the OFF state is low and the favorable contrast ratio (CR = 300:
1,5V) was obtained.

Further, FIG. 34 shows the viewing angle characteristic of contrast in the liquid crystal display device of the first embodiment. In FIG. 34, Φ is an azimuth angle (angle in the display surface: the absorption axis of the lower polarizing plate is 0 °), and θ is a viewing angle (tilt angle from the normal to the display surface).
And hatching indicates a region where the contrast ratio is 20: 1 or more. As shown in FIG. 34, in the conventional liquid crystal display device, a high contrast ratio is obtained in a wide viewing angle range including a direction deviated by 45 ° from the absorption axis of the polarizing plate, which is a particularly poor viewing angle characteristic. It was possible to obtain an almost circular viewing angle characteristic.

(Embodiment 2) In Embodiment 2, the liquid crystal cell shown in FIG. 31 is manufactured in the same manner as in Embodiment 1, and the liquid crystal cell is arranged in the arrangement shown in FIG. 32 as in Embodiment 1. Polarizing plates 101 and 102 and retardation compensation elements 103 and 104 are arranged on both sides of 100 to complete a liquid crystal display device. However, in the second embodiment, the Nn-type liquid crystal material (Δε
= -3.3, Δn = 0.0773, cell gap 6 μm
The twist angle peculiar to the liquid crystal material is set so that the twist becomes 90 ° at, and the retardation value d _LC · Δn = 450 nm)
Was injected.

FIG. 35 shows the results of measurement of the electro-optical characteristics of the liquid crystal display device of Embodiment 2 as in Embodiment 1. Here, viewing angle θ = 40 °, azimuth angle Φ = 4
It was fixed at 5 ° and measured by changing the in-plane retardation value d _f (n _x −n _y ) of the phase difference compensating element. As shown in FIG. 35, the in-plane retardation value d _f (n _x −n _y ) of the retardation compensation element having a contrast ratio of 10 or more has a range of 16.0 nm to 65.0 nm, and the retardation of the liquid crystal layer is It was 3.5% to 15% of the value d _LC · Δn. Also, is when the retardation value in the plane of the contrast ratio is maximized _{(n x -n y) · d} f has a value of about 42.5 nm, about the retardation value d _LC · [Delta] n of the liquid crystal layer 9 It was 0.5%. Furthermore, viewing angle θ = 40 °, azimuth angle Φ
= 135 ° is fixed, the retardation value in the plane of the phase compensation element (n _x -n _y) even when measured with varying · d _f, the same results as FIG. 35 were obtained.

Comparative Example 1 In Comparative Example 1, the liquid crystal cell shown in FIG. 31 was prepared in the same manner as in Embodiment 1, and a pair of polarizing plates were provided on both sides of the liquid crystal cell so that their absorption axes were orthogonal to each other. Arranged to complete the liquid crystal display device. However, this comparative example 1
However, no phase difference compensating element was provided. FIG. 36 shows the viewing angle characteristics of contrast in the liquid crystal display device of Comparative Example 1. In FIG. 36, Φ is an azimuth angle (angle within the display surface),
θ is a viewing angle (angle of inclination from the normal to the display surface), and hatching indicates a region where the contrast ratio is 10: 1 or more. Figure 3
As shown in FIG. 6, the viewing angle characteristics in the direction deviated from the absorption axis of the polarizing plate by 45 ° (the direction shown in (a) or (b) of FIG. 36) are poor, and the contrast is remarkably reduced when the viewing angle becomes 35 ° or more. Was.

(Comparative Example 2) In Comparative Example 2, the liquid crystal cell shown in FIG. 31 was prepared in the same manner as in Embodiment 1, and the upper polarizing plate and the lower polarizing plate were provided on both sides of the liquid crystal cell with their absorption axes being It was arranged so as to be orthogonal. Further, the first retardation compensation element was placed between the upper polarizing plate and the liquid crystal cell, and the second retardation compensation element was placed between the lower polarizing plate and the liquid crystal cell. However, in this Comparative Example 2, both the first phase difference compensating element and the second phase difference compensating element are phase difference compensating elements called a Frisbee type, n _x = n _y , and the retardation value d in the thickness direction is _f (n _x -n _z) was 150nm.

FIG. 37 shows the viewing angle characteristics of contrast in the liquid crystal display device of Comparative Example 2. In FIG. 37, Φ is an azimuth angle (angle within the display surface), θ is a viewing angle (tilt angle from the display surface normal), and hatching indicates a contrast ratio of 1
A region of 0: 1 or more is shown. Compared with Comparative Example 1 in which no phase difference compensating element was provided, although the viewing angle characteristics in the direction deviated by 45 ° from the absorption axis of the polarizing plate were somewhat improved, the contrast was still remarkable especially at a viewing angle of 40 ° or more. It was falling.

(Third Embodiment) In the third embodiment, the liquid crystal cell shown in FIG. 31 is manufactured in the same manner as in the first embodiment, and the liquid crystal cell is arranged in the arrangement shown in FIG. 32 as in the first embodiment. Polarizing plates 101 and 102 and retardation compensation elements 103 and 104 are arranged on both sides of 100 to complete a liquid crystal display device. However, in the third embodiment, an antiglare antiglare layer having a haze of 3.5% and a gloss of 80% is provided on the surface of the upper polarizing plate 101.

FIG. 38 shows the liquid crystal display device according to the third embodiment with four gradations (liquid crystal drive voltage: 2.77V, 3.74).
V, 4.8V, 7.77V) gradation characteristics are shown. Figure 38
38A shows gradation characteristics in the absorption axis direction of the upper polarizing plate 101, and FIG. 38B shows gradation characteristics in the direction shifted by 45 ° from the absorption axis of the upper polarizing plate 101. For comparison, FIG. 39 shows four gradations (liquid crystal drive voltage: 2.77V, 3.74V, 4.8) of the liquid crystal display device of the first embodiment.
V, 7.77 V). FIG. 39A shows gradation characteristics in the absorption axis direction of the upper polarizing plate 101,
FIG. 39B shows the gradation characteristics in the direction shifted by 45 ° from the absorption axis of the upper polarizing plate 101.

As shown in FIGS. 38 and 39, by providing the polarizing plate with the antiglare antiglare layer, it was possible to suppress an increase in the black level that would appear as the viewing angle was reduced. In particular, the black level was remarkably suppressed from increasing at the viewing angle of 60 ° in the direction deviated from the absorption axis by 45 °, and the contrast ratio was improved and the viewing angle characteristics could be improved.

(Embodiment 4) In Embodiment 4, the liquid crystal cell shown in FIG. 31 is manufactured in the same manner as in Embodiment 3, and the liquid crystal cell is arranged in the arrangement shown in FIG. 32 as in Embodiment 3. Polarizing plates 101 and 102 and retardation compensation elements 103 and 104 are arranged on both sides of 100 to complete a liquid crystal display device. However, in this Embodiment 4, an antiglare antiglare layer having a haze of 13% and a gloss of 40% was provided on the surface of the upper polarizing plate 101.

FIG. 40 shows four gradations (liquid crystal driving voltage: 2.77V, 3.74) of the liquid crystal display device of the fourth embodiment.
V, 4.8V, 7.77V) gradation characteristics are shown. Figure 40
40A shows the gradation characteristic in the absorption axis direction of the upper polarizing plate 101, and FIG. 40B shows the gradation characteristic in the direction shifted by 45 ° from the absorption axis of the upper polarizing plate 101.

As shown in FIG. 40, similarly to the third embodiment, by providing the polarizing plate with the antiglare antiglare layer, it was possible to suppress the increase in the black level that would appear as the viewing angle was tilted. Further, in the fourth embodiment, by increasing the haze, the black level is remarkably suppressed from increasing at the viewing angle of 60 °, particularly in the direction deviated from the absorption axis by 45 ° as compared with the third embodiment, and the contrast is further reduced. The viewing angle characteristics could be improved by increasing the ratio.

(Fifth Embodiment) In the fifth embodiment, the liquid crystal cell shown in FIG. 31 is manufactured in the same manner as in the third embodiment, and the liquid crystal cell is arranged in the arrangement shown in FIG. 32 as in the third embodiment. Polarizing plates 101 and 102 and retardation compensation elements 103 and 104 are arranged on both sides of 100 to complete a liquid crystal display device. However, in this Embodiment 5, an anti-glare anti-glare layer having a haze of 3.5% and a gloss level of 80% was provided on the surface of the upper polarizing plate 101, and further an antireflection film was provided.

FIG. 41 shows four gradations (liquid crystal driving voltage: 2.77V, 3.74) of the liquid crystal display device of the fifth embodiment.
V, 4.8V, 7.77V) gradation characteristics are shown. Figure 41
41A shows the gradation characteristics in the absorption axis direction of the upper polarizing plate 101, and FIG. 41B shows the gradation characteristics in the direction shifted by 45 ° from the absorption axis of the upper polarizing plate 101.

As shown in FIG. 41, by providing the antireflection film, it is possible to further suppress the increase in the black level, which appears when the viewing angle is tilted, as compared with the third embodiment.
Furthermore, the contrast ratio was improved and the viewing angle characteristics could be improved.

(Embodiment 6) In Embodiment 6, the liquid crystal cell shown in FIG. 31 is manufactured in the same manner as in Embodiment 3, and the liquid crystal cell is arranged in the arrangement shown in FIG. 32 as in Embodiment 3. Polarizing plates 101 and 102 and retardation compensation elements 103 and 104 are arranged on both sides of 100 to complete a liquid crystal display device. However, in this Embodiment 6, the anti-glare anti-glare layer having a haze of 13% and a gloss of 40% was provided on the surface of the upper polarizing plate 101, and further an antireflection film was provided.

FIG. 42 shows four gradations (liquid crystal driving voltage: 2.77V, 3.74) for the liquid crystal display device of the sixth embodiment.
V, 4.8V, 7.77V) gradation characteristics are shown. FIG. 42
42A shows the gradation characteristic in the absorption axis direction of the upper polarizing plate 101, and FIG. 42B shows the gradation characteristic in the direction shifted by 45 ° from the absorption axis of the upper polarizing plate 101.

As shown in FIG. 42, by providing the antireflection film, it is possible to further suppress the increase in the black level, which appears when the viewing angle is tilted, as compared with the fourth embodiment.
Furthermore, the contrast ratio was improved and the viewing angle characteristics could be improved.

(Embodiment 7) A method of manufacturing a liquid crystal display device of Embodiment 7 will be described with reference to FIG.
Since the liquid crystal cell of the liquid crystal display device of the present embodiment has the same structure as the liquid crystal cell of FIG. 31, it will be described with reference to FIG.

First, a transparent electrode (for example, about 100
A spacer having a height of about 6 μm was formed outside the pixel region using a photosensitive polyimide on a substrate on which an ITO film having a thickness of nm was formed. Next, a convex portion 66 having a height of about 3 μm was formed using an acrylic negative resist. Here, the convex portion 66
The size of the area surrounded by
It was set to μm × 100 μm. On top of that, JALS204
A vertical alignment layer 68 was formed by spin coating (Japan Synthetic Rubber). Furthermore, the transparent electrode 64 (ITO: 10
The vertical alignment layer 67 was formed using the same material on the other substrate 61 on which 0 μm) was formed. After that, the both were stuck together to produce a liquid crystal cell.

Nn type liquid crystal material (Δε
= −3.0, Δn = 0.073, twist angle specific to the liquid crystal material was set so that the twist was 90 ° at a cell gap of 6 μm, retardation value d _LC · Δn = 450 nm was injected, and a voltage of 7 V was applied. . Immediately after the voltage application, in the initial state, a plurality of axially symmetric orientation axes existed, and when the voltage application state was continued, one axially symmetric orientation region (monodomain) was formed for each pixel region.

Next, as shown in FIG. 43, a polarizing plate and a retardation compensating element were arranged on both sides of the liquid crystal cell to complete a liquid crystal display device. FIG. 43 shows a liquid crystal cell according to the present embodiment,
FIG. 3 is a layout view of a polarizing plate and a phase difference compensating element, showing the absorption axis direction of the polarizing plate and the direction of nx which is the maximum main refractive index of the three main refractive indexes of the phase difference compensating element, that is, the slow axis direction. It is a figure which shows the relationship of. As shown in FIG. 43, the upper polarizing plate and the lower polarizing plate were arranged on both outer sides of the liquid crystal cell so that their absorption axes were orthogonal to each other. Further, a phase difference compensating element was arranged between the upper polarizing plate and the liquid crystal cell. The retardation compensation element of this embodiment is formed by a biaxial stretching method using a polycarbonate material. Here, the in-plane retardation value d _f (n _x −n _y ) was 42 nm, and the thickness direction retardation value d _f (n _x −n _z ) was 191 nm.

The difference from the other embodiments is that the phase difference compensating element is provided only on one side (one side) of the liquid crystal cell. As the phase difference compensating element, a single phase difference compensating element having retardation in the biaxial directions is used in this embodiment, but the invention is not limited to this, and the liquid crystal display device as a whole has biaxial directions. Having a retardation of, that is, refractive indices nx, n in the x-, y-, and z-axis directions.
Similar to the other embodiments, y and nz only need to satisfy the condition of nx>ny> nz.

FIG. 44 shows the viewing angle characteristics of the contrast ratio of the liquid crystal display device of this embodiment. Hatching indicates a region where the contrast ratio is 10: 1 or more. In the liquid crystal display device of the present embodiment, when there is no phase difference compensating element in the 45 ° direction sandwiched by the absorption axes of both polarizing plates, which is a region where the viewing angle characteristics are poor, due to the influence of the polarizing plates arranged in the crossed Nicols state. The viewing angle of the contrast ratio of 10 was 1.7 times wider than that of, and a high contrast ratio could be obtained in all directions. In the seventh embodiment, the retardation compensation element is arranged between the polarizing plate on the front surface side and the liquid crystal cell, but the same viewing angle characteristics can be obtained even if it is arranged between the polarizing plate on the rear surface side and the liquid crystal cell. Was given.

In addition, in the viewing angle compensation in the direction of 45 ° with respect to the absorption axis of the polarizing plate, a phase difference compensating element having a viewing angle compensating effect wider than 1 times as compared with the case without the phase difference compensating element is obtained. The conditions for the in-plane and normal retardation are
About 5 nm to about 70 nm, about 60 nm to about 28 nm, respectively
It was in the range of 0 nm.

(Embodiment 8) In this embodiment, using the same liquid crystal cell as in Embodiment 7, two retardation plates manufactured by the biaxial stretching method as two retardation compensating elements are used as two polarizing plates. A liquid crystal display device having one liquid crystal cell and one liquid crystal cell will be described. The phase difference compensating element in accordance with the present embodiment, the retardation value d _f in the plane (n _x -n _y) is 43n
m, the retardation value d _f (n _x −n _z ) in the thickness direction is 1
A retardation compensation element made of a 91 nm polycarbonate material was used. The liquid crystal cell in the present embodiment also has a liquid crystal layer in which liquid crystal molecules are substantially vertically aligned with respect to the substrate when no voltage is applied, and are axially symmetrically aligned about an axis perpendicular to the substrate when voltage is applied.

FIG. 45 shows the configuration of the liquid crystal display device of this embodiment.
Shown in. The pair of phase difference compensating elements are arranged so that their respective slow axes are orthogonal to each other. Further, the polarizing plate is arranged such that the slow axis of one of the phase difference compensating elements is orthogonal to the absorption axis of the polarizing plate, and the pair of polarizing plates is arranged so that their absorption axes are orthogonal to each other. (Cross Nicol state)

FIG. 46 shows the viewing angle characteristics of the contrast ratio of the liquid crystal display device of this embodiment. Hatching indicates a region where the contrast ratio is 10: 1 or more. In the liquid crystal display device of the present embodiment, when there is no phase difference compensating element in the 45 ° direction sandwiched by the absorption axes of both polarizing plates, which is a region where the viewing angle characteristics are poor, due to the influence of the polarizing plates arranged in the crossed Nicols state. The viewing angle of the contrast ratio 10 was 2.3 times wider than that of, and a high contrast ratio could be obtained in all directions.

Further, in the viewing angle compensation in the direction of 45 ° with respect to the absorption axis of the polarizing plate, a phase difference compensating element which has a viewing angle compensating effect wider than 1 times as compared with the case without the phase difference compensating element is obtained. The conditions for the in-plane and normal retardation are
About 5 nm to about 70 nm, about 60 nm to about 28 nm, respectively
It was in the range of 0 nm.

[0139]

As described in detail above, according to the present invention,
In a liquid crystal display device having a liquid crystal region in which liquid crystal molecules are aligned substantially perpendicular to the substrate when no voltage is applied and liquid crystal molecules are aligned in axisymmetric or concentric circles for each pixel when a voltage is applied, regardless of the viewing direction. Since the gradation inversion phenomenon can be prevented, it is possible to obtain a high-contrast display in a wide viewing angle region. Although the liquid crystal region is typically formed for each picture element, a plurality of liquid crystal regions may be formed within the picture element.

The liquid crystal display device of the present invention having such excellent characteristics is a flat panel display such as a personal computer, a word processor, an amusement machine or a television set, or a display plate utilizing the shutter effect,
It is preferably used for windows, doors, walls, etc.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an operation principle of a liquid crystal display device according to the present invention. (A) and (b) show the state when no voltage is applied, (c) and (d) show the state when voltage is applied,
(A) and (c) show sectional views, and (b) and (d) show the results of observing the upper surface with a polarization microscope in a crossed Nicol state.

FIG. 2 is a diagram showing a voltage transmittance curve of a liquid crystal display device.

FIG. 3 is a diagram showing a voltage transmittance curve of a liquid crystal display device having a retardation value larger than an optimum retardation value.

FIG. 4 shows d _LC of 4 μm when Δn of liquid crystal is 0.0773.
D _LC · Δn changed to ˜8 μm and Φ = 0 °, 45
It is a figure which shows the relationship with the viewing angle of contrast ratio 10 in (degrees), 90 degrees, and 135 degrees.

FIG. 5: d _LC of liquid crystal Δn is 0.0773 and d _LC is 4 μm.
D _LC · Δn changed to ˜8 μm and Φ = 0 °, 45
It is a figure which shows the relationship with the viewing angle of the contrast ratio 20 in (degree), 90 degree, and 135 degree.

FIG. 6 shows a liquid crystal Δn of 0.0773 and d _LC of 4 μm.
D _LC · Δn changed to ˜8 μm and Φ = 0 °, 45
It is a figure which shows the relationship with the inversion angle in (degree), 90 degree, and 135 degree.

FIG. 7: d _LC of liquid crystal Δn is 0.0773 and d _LC is 4 μm
And d _LC · [Delta] n was changed to ～8Myuemu, a diagram illustrating the relationship between the transmittance when a voltage 10V is applied.

FIG. 8 shows a liquid crystal layer thickness d _LC of 5 μm and Δn of 0.0.
D _LC · Δn changed from 7 to 0.1 and Φ = 0 °, 45
It is a figure which shows the relationship with the viewing angle of contrast ratio 10 in (degrees), 90 degrees, and 135 degrees.

FIG. 9 shows a liquid crystal layer thickness d _LC of 5 μm and Δn of 0.0
D _LC · Δn changed from 7 to 0.1 and Φ = 0 °, 45
It is a figure which shows the relationship with the viewing angle of the contrast ratio 20 in (degree), 90 degree, and 135 degree.

FIG. 10 shows a liquid crystal layer thickness d _LC of 5 μm and Δn of 0.
D _LC · Δn changed from 07 to 0.1 and Φ = 0 °, 4
It is a figure which shows the relationship with the inversion angle in 5 degrees, 90 degrees, and 135 degrees.

FIG. 11 shows a liquid crystal layer thickness d _LC of 5 μm and Δn of 0.
And d _LC · [Delta] n was changed to 07 to 0.1, a diagram illustrating the relationship between the transmittance when a voltage 10V is applied.

FIG. 12 is a perspective view showing the direction of the main refractive index of the phase difference compensating element used in the present invention.

13 (a) to 13 (c) are cross-sectional views showing examples of other retardation compensation elements usable in the present invention.

FIG. 14 is a diagram showing the relationship between the deviation of the slow axis of the phase difference compensating element and the absorption axis of the polarizing plate from the orthogonal direction and the amount of light leakage.

FIG. 15 is a diagram for explaining the mechanism of viewing angle compensation by the phase difference compensating element, and is a diagram showing the absorption axis direction of the polarizing plate.

FIG. 16 is a diagram for explaining the mechanism of viewing angle compensation by the phase difference compensating element, and is a diagram showing an image of a refractive index ellipsoid in the absorption axis direction of the polarizing plate.

FIG. 17 is a diagram for explaining the mechanism of viewing angle compensation by the phase difference compensating element, which is 4 in the absorption axis direction of the polarizing plate.
It is a figure which shows a 5 degree direction.

FIG. 18 is a diagram for explaining the mechanism of viewing angle compensation by the phase difference compensating element, which is 4 in the absorption axis direction of the polarizing plate.
It is a figure which shows the image of a refractive index ellipsoid in a 5 degree direction.

19 is a diagram for explaining the mechanism of view angle compensation by the phase difference compensating element, and is a diagram showing a case where the screen of FIG. 17 is viewed obliquely when the voltage is off.

20 is a diagram for explaining the mechanism of viewing angle compensation by the phase difference compensating element, and is a diagram showing a case where the screen of FIG. 17 is viewed obliquely when the voltage is on.

FIG. 21 is a diagram for explaining the mechanism of viewing angle compensation by the phase difference compensating element, and is a diagram showing the absorption axis direction of the polarizing plate.

FIG. 22 is a diagram for explaining the mechanism of viewing angle compensation by the phase difference compensating element, and is a diagram showing an image of a refractive index ellipsoid in the absorption axis direction of the polarizing plate.

23 is a diagram for explaining the mechanism of viewing angle compensation by the phase difference compensating element, and is a diagram showing a case where the screen of FIG. 21 is viewed obliquely when the voltage is off.

FIG. 24 is a diagram for explaining the mechanism of viewing angle compensation by the phase difference compensating element, and is a diagram showing a case where the screen of FIG. 21 is viewed obliquely when the voltage is on.

FIG. 25 shows d _LC of 4μ with Δn of liquid crystal set to 0.0773.
and d _LC · [Delta] n was changed to M～8myuemu, the refractive index difference of the in-plane refractive index difference and the thickness direction ratio of 4.5 and was in-plane and normal to the direction of the retardation of the optimum phase difference film It is a figure which shows a relationship.

FIG. 26 shows a liquid crystal layer thickness d _LC of 5 μm and Δn of 0.
In-plane and normal-direction retardation of the optimum retardation film in which the ratio of d _LC · Δn changed from 07 to 0.1 and the in-plane refractive index difference and the refractive index difference in the thickness direction is 4.5. It is a figure which shows the relationship with.

FIG. 27 is an in-plane refractive index difference (0.00
The refractive index difference ratio in the normal direction to 1) and Φ = 0 °, 45
It is a figure which shows the relationship with the viewing angle of contrast ratio 10 in (degrees), 90 degrees, and 135 degrees.

FIG. 28 is an in-plane refractive index difference (0.00
The refractive index difference ratio in the normal direction to 1) and Φ = 0 °, 45
It is a figure which shows the relationship with the viewing angle of the contrast ratio 20 in (degree), 90 degree, and 135 degree.

FIG. 29 is a diagram showing an in-plane refractive index difference (0.00
The refractive index difference ratio in the normal direction to 1) and Φ = 0 °, 45
It is a figure which shows the relationship with the inversion angle in (degree), 90 degree, and 135 degree.

FIG. 30: Phase difference compensation in the liquid crystal cell having d _LC · Δn of 390 nm when the refractive index difference ratio in the normal direction is changed with respect to the in-plane refractive index difference (0.001) of the phase difference compensating element. It is a figure which shows the relationship of the in-plane of the element and the retardation of a normal direction.

31A is a cross-sectional view of the liquid crystal display device of Embodiment 1, and FIG. 31B is a plan view thereof.

32A is a layout view of a liquid crystal cell, a polarizing plate and a retardation compensation element in Embodiment 1, and FIG. 32B is an absorption axis direction of the polarizing plate and a maximum main refractive index of the retardation compensation element. is a diagram showing the relationship between the direction of a n _x.

FIG. 33 is a diagram showing electro-optical characteristics of the liquid crystal display device of Embodiment 1.

FIG. 34 is a diagram showing a viewing angle characteristic of contrast in the liquid crystal display device of the first embodiment.

FIG. 35 is a diagram showing electro-optical characteristics of the liquid crystal display device of the second embodiment.

36 is a diagram showing contrast viewing angle characteristics in the liquid crystal display device of Comparative Example 1. FIG.

37 is a diagram showing contrast viewing angle characteristics in the liquid crystal display device of Comparative Example 2. FIG.

FIG. 38 is a diagram showing gradation characteristics of four gradations in the liquid crystal display device of the third embodiment. (A) is a gradation characteristic in the absorption axis direction of the upper polarizing plate, and (b) is a gradation characteristic in a direction shifted by 45 ° from the absorption axis of the upper polarizing plate.

FIG. 39 is a diagram showing gradation characteristics of four gradations in the liquid crystal display device of the first embodiment. (A) is a gradation characteristic in the absorption axis direction of the upper polarizing plate, and (b) is a gradation characteristic in a direction shifted by 45 ° from the absorption axis of the upper polarizing plate.

FIG. 40 is a diagram showing gradation characteristics of four gradations in the liquid crystal display device according to the fourth embodiment. (A) is a gradation characteristic in the absorption axis direction of the upper polarizing plate, and (b) is a gradation characteristic in a direction shifted by 45 ° from the absorption axis of the upper polarizing plate.

FIG. 41 is a diagram showing gradation characteristics of four gradations in the liquid crystal display device of the fifth embodiment. (A) is a gradation characteristic in the absorption axis direction of the upper polarizing plate, and (b) is a gradation characteristic in a direction shifted by 45 ° from the absorption axis of the upper polarizing plate.

FIG. 42 is a diagram showing gradation characteristics of four gradations in the liquid crystal display device of the sixth embodiment. (A) is a gradation characteristic in the absorption axis direction of the upper polarizing plate, and (b) is a gradation characteristic in a direction shifted by 45 ° from the absorption axis of the upper polarizing plate.

FIG. 43 is a layout view of a liquid crystal cell, a polarizing plate and a phase difference compensating element in the seventh embodiment.

FIG. 44 is a diagram showing contrast viewing angle characteristics in the liquid crystal display device of the seventh embodiment.

FIG. 45 is a layout view of a liquid crystal cell, a polarizing plate, and a phase difference compensating element in Embodiment 8.

FIG. 46 is a diagram showing a viewing angle characteristic of contrast in the liquid crystal display device of the eighth embodiment.

[Explanation of symbols]

100 Liquid crystal display device, liquid crystal cell 101, 102 Polarizing plate 103, 104 Phase difference compensating element 32, 34, 61, 62 substrate 38a, 38b, 67, 68 Vertical alignment layer 36, 66 convex 40 Liquid crystal layer 42 Liquid crystal molecule 63, 64 transparent electrode 65 Spacer

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 12, 2003 (2003.6.1)
2)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

A liquid crystal display device of the present invention
Is sandwiched between a pair of substrates and has a negative dielectric anisotropy
A liquid crystal cell having a liquid crystal layer composed of liquid crystal molecules, and the liquid crystal cell
And the absorption axes of the polarizing plates are perpendicular to each other.
An optical plate, at least a space between the pair of polarizing plates and the liquid crystal cell.
Also with the phase difference compensation element provided on one sideLCD display with
A device,The liquid crystal layer has a plurality of liquid crystal regions.
The pair of substrates has a vertical alignment layer on the surface of the liquid crystal layer side.
The crystal molecules are axisymmetric in each of the liquid crystal regions when a voltage is applied.
OrientationHowever, the liquid crystal molecules are opposed to the pair of substrates when no voltage is applied.
And is oriented almost vertically,The phase difference compensation element is negative
X, y, and
And three principal refractive indices n in the z-axis direction_x, N_y, N_zHaving the
The principal refractive index in the in-plane direction of the liquid crystal cell is n_x, N_yAnd the liquid crystal
The main refractive index in the thickness direction of the cell is n_zAnd n_x> N _y
> N_zHave a relationship ofThe in-plane re-direction of the phase difference compensation element
Tardation value d _f (n _x −n _y ) and retardation in the thickness direction
The ratio to the application value d _f (n _x −n _z ) is 2 or more,That
By doing so, the above object is achieved.Another liquid crystal of the present invention
The display device is sandwiched between a pair of substrates and has a negative dielectric anisotropy.
A liquid crystal cell having a liquid crystal layer composed of liquid crystal molecules having
The liquid crystal cell is sandwiched and the absorption axes of the polarizing plates are orthogonal to each other.
A pair of polarizing plates, and between the pair of polarizing plates and the liquid crystal cell
And a phase difference compensation element provided on at least one side
A liquid crystal display device, wherein the liquid crystal molecules are
Aligning in a direction almost perpendicular to the pair of substrates, the phase difference
The compensating elements have negative birefringence and are orthogonal to each other.
The three main refractive indices n _x , n _y , in the x-, y-, and z-axis directions are
n _z , and the principal refractive index in the in-plane direction of the liquid crystal cell is n _x , n
Let _y be the main refractive index in the thickness direction of the liquid crystal cell be n _z
The phase difference compensating element has a relationship of n _x > n _y > _nz .
Plane direction retardation values d _f (n _x -n _y) and towards thickness
The retardation value d _f (n _x −n _z ) is 2 or more.
Therefore, the above object is achieved.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014] The phase difference compensating element is preferably x-axis direction of the retardation compensation element is arranged so as to be substantially perpendicular to the absorption axis of the polarizing plate adjacent to the phase difference compensating element.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

Of the pair of polarizing plates, an antireflection film or an antiglare antiglare layer may be provided on the surface of the polarizing plate on the viewer side. An antireflection film is preferably provided on the surface of the antiglare antiglare layer. The phase difference
Retardation value d _f (n _x − in the thickness direction of the compensation element
_nz ) is 3 which is the retardation value d _LC · Δn of the liquid crystal layer.
It is preferably 0% to 80%.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1335 G02F 1/1337 510 G02B 1/10 A 1/1337 Z (72) Inventor Shuichi Kanzaki Osaka Prefecture 22-22 Nagaike-cho, Abeno-ku, Osaka City, F-term in SHARP Co., Ltd. (reference) 2H042 BA02 BA03 BA13 BA15 BA20 2H049 BA02 BA06 BA42 BB03 BB63 BB65 BC22 2H090 JB13 LA01 LA02 LA05 LA06 LA09 MA01 2H091 FA08X FA08Z FA11XFB04Z FC02 FC08 FC09 FC23 FD01 FD06 GA01 GA02 GA03 GA06 GA08 KA01 KA02 LA17 LA19 LA30 2K009 AA02 AA12 EE00

Claims (16)

[Claims] 1. A liquid crystal cell sandwiched between a pair of substrates and having a liquid crystal layer composed of liquid crystal molecules having negative dielectric anisotropy, and a pair sandwiching the liquid crystal cell and having absorption axes of polarizing plates orthogonal to each other. And a retardation compensating element provided on at least one of the pair of polarizing plates and the liquid crystal cell, wherein the liquid crystal layer has a plurality of liquid crystal regions. , The pair of substrates has a vertical alignment layer on the surface on the liquid crystal layer side, the liquid crystal molecules are aligned in axial symmetry in each of the plurality of liquid crystal regions when a voltage is applied, and the phase difference compensating element is negative. It has a birefringence index and has three main refraction indexes n in the x-, y-, and z-axis directions that are orthogonal to each other
_x, n _y, has a n _z, the main refractive index n _x in the plane direction of the liquid crystal cell, and n _y, the main refractive index in the thickness direction of the liquid crystal cell n
_z , the relationship of n _x > n _y > n _z , and the retardation value d in the in-plane direction of the phase difference compensating element.
_f (n _x -n _y) and thickness direction retardation values d _f (n _x
The ratio of the -n _z) is 2 or more, a liquid crystal display device. 2. A liquid crystal cell sandwiched between a pair of substrates and having a liquid crystal layer composed of liquid crystal molecules having negative dielectric anisotropy, and a pair sandwiching the liquid crystal cell and having absorption axes of polarizing plates orthogonal to each other. And a retardation compensation element provided on at least one of the pair of polarizing plates and the liquid crystal cell, wherein the liquid crystal molecules are provided on the pair of substrates when a voltage is applied. The phase difference compensating element has a negative birefringence index, and has three main refractive indexes n in the x, y, and z axis directions which are orthogonal to each other.
_x, n _y, has a n _z, the main refractive index n _x in the plane direction of the liquid crystal cell, and n _y, the main refractive index in the thickness direction of the liquid crystal cell n
_z , the relationship of n _x > n _y > n _z , and the retardation value d in the in-plane direction of the phase difference compensating element.
_f (n _x -n _y) and thickness direction retardation values d _f (n _x
The ratio of the -n _z) is 2 or more, a liquid crystal display device. 3. The liquid crystal display device according to claim 1, wherein each of the phase difference compensation elements is provided between the pair of polarizing plates and the liquid crystal cell. 4. The biaxial film having retardation in the in-plane direction and the thickness direction, or the uniaxial film having retardation in the in-plane direction and the uniaxial film having retardation in the thickness direction. The liquid crystal display device according to claim 1 or 2, which is composed of a laminated film obtained by laminating and. 5. The phase difference compensating element is arranged so that the x-axis direction of the phase difference compensating element is substantially orthogonal to the absorption axis of a polarizing plate adjacent to the phase difference compensating element. The liquid crystal display device according to item 1. 6. The liquid crystal display device according to claim 5, wherein a shift between the x-axis direction of the phase difference compensation element and a direction orthogonal to the absorption axis of the polarizing plate is 1 ° or less. 7. The birefringence of the liquid crystal molecules is Δn, the liquid
The average thickness of the crystal layer is d _LCAnd the thickness of the phase difference compensation element
Sa d_fWhen In-plane retardation value d of the phase difference compensation element
_f(N_x-N_y) Is the retardation value d of the liquid crystal layer_LC・ Δ
The liquid crystal display device according to claim 1, which is smaller than n. Wherein said phase _{compensator, 0.035 ≦ {d f (n} x -n y)} / (d LC · Δn) ≦
The liquid crystal display device according to claim 7, which satisfies 0.15. 9. The birefringence of the liquid crystal molecule is Δn, the liquid
The average thickness of the crystal layer is d _LCAnd the thickness of the phase difference compensation element
Sa d_fWhen Retardation value d in the thickness direction of the phase difference compensation element
_f(N_x-N_z) Is the retardation value d of the liquid crystal layer_LC・ Δ
The liquid crystal display device according to claim 1, which is smaller than n. 10. The liquid crystal display device according to claim 1, wherein a retardation value d _f (n _x −n _z ) in the thickness direction of the phase difference compensation element is larger than 0. 11. The ratio of the in-plane direction of the retardation compensation element retardation value d _f (n _x -n _y) and thickness direction retardation values d _f (n _x -n _z) is 3 to 6 The liquid crystal display device according to claim 1 or 2. 12. The liquid crystal display device according to claim 1, wherein the phase difference compensation element has an average refractive index of 1.4 or more and 1.7 or less. 13. A retardation value d _LC · of the liquid crystal layer.
Δn is in the range of 300 to 550 nm.
8. The liquid crystal display device according to any one of 8 and 9. 14. The liquid crystal display device according to claim 1, wherein an antiglare antiglare layer is provided on the surface of the polarizing plate on the viewer side of the pair of polarizing plates. 15. The liquid crystal display device according to claim 14, wherein an antireflection film is provided on the surface of the antiglare antiglare layer. 16. The retardation value d _f (n _x −n _z ) in the thickness direction of the phase difference compensating element is 30% to 80% of the retardation value d _LC · Δn of the liquid crystal layer. Liquid crystal display device.