JP2003337326A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying an image with a wide viewing angle and a high color reproducibility. <P>SOLUTION: The liquid crystal display device includes; a liquid crystal cell 1; polarizers 4 and 5 provided so as to oppose each other via the liquid crystal cell 1 therebetween; a phase compensation element 2 (and 3) provided between the liquid crystal cell 1 and at least one of the polarizers 4 and 5; and an antiglare layer 16 provided on the viewer side of the polarizer 4 provided on the viewer side. The antiglare layer 16 has an internal scattering layer and a scattering surface and has a haze value of ≥15. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having excellent display quality when viewed from an oblique direction.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device using a nematic liquid crystal has been widely used as a numerical segment type display device such as a watch and a calculator. Further, in recent years, it has been widely used for word processors, notebook type personal computers, car navigation systems, and recently, it has also been used for 20- to 30-inch class direct-view large-scale televisions, etc. Is expanding.

This liquid crystal display device generally has a pair of substrates which are opposed to each other with a liquid crystal layer interposed therebetween, and electrodes and wirings for turning on / off pixels are formed on the substrates. ing. For example, in an active matrix type liquid crystal display device, pixel electrodes for applying a voltage to a liquid crystal layer are provided in a matrix, and active elements such as field effect transistors are used as switching means for selectively applying a potential to each pixel electrode. The element is provided on the substrate together with the electrodes and wiring. Furthermore, in a liquid crystal display device that performs color display, color filter layers of red, green, blue, etc. are provided on a substrate. In such a liquid crystal display device, the following display methods are known according to the twist angle of nematic liquid crystal molecules.

(1) Twisted nematic liquid crystal display system (hereinafter referred to as TN system) in which the twist angle of nematic liquid crystal molecules is 90 ° between a pair of substrates.

(2) A super twist nematic liquid crystal display system (hereinafter referred to as STN system) in which the twist angle of nematic liquid crystal molecules is larger than 90 ° between a pair of substrates.

In the liquid crystal display device of the above display system,
The direction in which the observer looks at the display surface (azimuth: direction within the display surface)
The viewing angle dependence (including both the azimuth angle dependence and the viewing angle dependence) in which the contrast ratio of the display image changes or the reversal phenomenon occurs depending on the viewing angle (viewing angle: direction with respect to the display surface normal). Therefore, there is a problem that a wide-angle viewing angle characteristic cannot be obtained. For example, in the 6 o'clock direction of the display surface (the direction when the display surface is regarded as a clock face, the 6 o'clock direction is downward), the gradation inversion phenomenon occurs only by slightly tilting the viewing angle, and the 12 o'clock direction ( In the (upward direction), the contrast ratio cannot be obtained and the overall image becomes whitish. Further, the gradation inversion phenomenon occurs also in the 3 o'clock direction and the 9 o'clock direction (horizontal direction), and the display quality is degraded.

In order to solve this problem, for example, Patent Document 1 and Patent Document 2 describe a liquid crystal display device in which a retardation compensating element having a tilted refractive index ellipsoid is combined with the above-mentioned TN type liquid crystal cell. Disclosure. In the liquid crystal display device disclosed in this publication, the pretilt direction of the liquid crystal molecules in the vicinity of the alignment film in each pixel and the tilt direction of the main axis of the refractive index ellipsoid of the phase difference compensating element are opposite to each other. The liquid crystal cell and the phase difference compensating element are arranged in the. Therefore, the positive uniaxial refractive index anisotropy of the liquid crystal molecules rising with voltage application in each pixel is compensated by the negative uniaxial refractive index anisotropy of the retardation compensation element. That is, the refractive index anisotropy of the liquid crystal molecules, which does not rise near the substrate interface when a voltage is applied, is effectively optically compensated. As a result, the inversion phenomenon of the gradation is suppressed in the 6 o'clock direction (downward direction), and at the same time, the contrast ratio in the 12 o'clock direction (upward direction) is improved and the viewing angle is expanded. In addition, the inversion phenomenon disappears in the 3 o'clock direction and the 9 o'clock direction (lateral direction), and the viewing angle also expands in these directions. In this way, by using the phase difference compensating element having the tilted refractive index ellipsoid, the viewing angle in the vertical direction (vertical direction) and the viewing angle in the horizontal direction (horizontal direction) are simultaneously widened when viewed from the observer. be able to.

In the TN type liquid crystal display device, the above viewing angle dependency is directed downward (6 o'clock direction) in the pretilt direction (so-called normal viewing angle direction) of liquid crystal molecules located near the center in the thickness direction of the liquid crystal layer. ) Is observed in the configuration set to). In a general TN type liquid crystal display device, the normal viewing angle direction is set as described above so that the maximum contrast ratio is obtained when the viewing angle is tilted downward (6 o'clock direction) with respect to the display surface normal. Has been done. In the present specification, unless otherwise specified, the liquid crystal layer of the exemplified TN liquid crystal display device is arranged as described above. That is, the vertical direction is a direction including the normal viewing angle direction, and the horizontal direction is a direction orthogonal to the normal viewing angle direction.

[0009]

[Patent Document 1] Japanese Patent No. 2866540

[Patent Document 2] Japanese Patent Application Laid-Open No. 9-120005

[0010]

However, under the circumstances where a liquid crystal display device having a further wide viewing angle, a high display quality and excellent color reproducibility is demanded as in the present day, as described above, the TN system is used. Just by combining the liquid crystal cell with a retardation compensator with an inclined refractive index ellipsoid,
It is hard to say that sufficient display characteristics were obtained.

In the above conventional liquid crystal display device, the alignment state of the liquid crystal layer is changed by the application of a voltage, the transmittance of light incident on the liquid crystal layer from the light source is changed, and black, white, and any luminance in between are changed. To get the image displayed. As described above, in the conventional liquid crystal display device, the apparent retardation value of the liquid crystal layer changes depending on the viewing angle, so that the viewing angle dependence occurs, and the phase difference compensating element compensates the viewing angle dependence.

However, the retardation of the liquid crystal layer and the retardation compensating element have wavelength dispersibility (wavelength dependence), and generally, their wavelength dispersibility is different from each other. Therefore, in the above-mentioned conventional liquid crystal display device, in white display and halftone display, even in the front direction (display surface normal direction), the retardation value of the liquid crystal layer and the retardation value of the phase difference compensation element are optimized. However, when viewed from an oblique direction (direction inclined from the normal to the display surface), coloring occurs due to the difference in retardation wavelength dispersion of the liquid crystal layer and the retardation compensation element. In particular, when the viewing direction is tilted in the 3 o'clock direction or the 9 o'clock direction (horizontal direction), there is a problem that a yellowish tint occurs.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal display device capable of realizing display with a wide viewing angle and high color reproducibility.

[0014]

A liquid crystal display device of the present invention includes a liquid crystal cell having a pair of substrates and a liquid crystal layer provided between the pair of substrates, and facing each other with the liquid crystal cell interposed therebetween. A pair of polarizers arranged so that a retardation compensation element provided in at least one of each of the pair of polarizers and the liquid crystal cell, and an observer of the pair of polarizers The antiglare layer provided on the observer side of the polarizer provided on the side, the antiglare layer has an internal scattering layer and a scattering surface, the haze value of the antiglare layer is 15 or more. There, the above-mentioned object is achieved by that.

In the phase difference compensating element, when the three principal axes of the refractive index ellipsoid orthogonal to each other are a-axis, b-axis and c-axis, and the principal refractive indices are na, nb and nc, na is
= Nc> nb, the a-axis is substantially parallel to the layer surface of the liquid crystal layer, and the b-axis is inclined with respect to the layer normal of the liquid crystal layer. It is preferable.

The internal scattering layer includes a polymer matrix and particles dispersed in the polymer matrix, and
It is preferable that the particles and the polymer matrix have different refractive indices.

The haze value of the antiglare layer is preferably 40 or more, more preferably 50 or more.

The anti-glare layer has an optical skewer width of 0.
The value of the transmitted image sharpness measured by a 5 mm image clarity measuring device is preferably 10 or more, and more preferably 15 or more.

The refractive index anisotropy Δn (550) of the liquid crystal material of the liquid crystal layer with respect to light having a wavelength of 550 nm is 0.060.
It is preferably in the range of <Δn (550) <0.120, and more preferably in the range of 0.070 ≦ Δn (550) ≦ 0.095.

It is preferable that the retardation compensation element is arranged so that the b axis forms an angle within the range of 15 ° to 75 ° with respect to the layer normal to the liquid crystal layer.

When the thickness of the liquid crystal layer of the retardation compensation element in the layer normal direction is d, (na−nb) × d is 80.
It is preferably in the range of nm to 250 nm.

The phase difference compensating element comprises a support made of a crosslinked transparent organic polymer, and the support held by the support.
It may have a discotic liquid crystal having a tilt alignment or a hybrid alignment.

The liquid crystal layer may be a twist-aligned liquid crystal layer.

The operation of the present invention will be described below.

In the liquid crystal display device of the present invention, the retardation compensating element can compensate the refractive index anisotropy of the liquid crystal layer, and the polarizer ("front polarizer") provided on the viewer side. The anti-glare layer provided on the viewer side of the polarizer includes a polarizing plate and a polarizing film.) The anti-glare layer is a coloring (yellowing or blue color) peculiar to the structure using the retardation compensation element. It suppresses the occurrence of the (taste) phenomenon, that is, the deterioration of color reproducibility.

The anti-glare layer scatters the light transmitted through the anti-glare layer forward by the internal scattering layer and / or the scattering surface, and suppresses the coloring phenomenon by mixing colored lights in various directions. In particular, when an internal scattering layer including a polymer matrix and particles dispersed in the polymer matrix and having different refractive indices between the particles and the polymer matrix is used, the specular reflection characteristic and the specular reflection property are reduced. It is possible to realize an anti-glare layer that has an excellent balance with the transmission characteristics. Furthermore, the antiglare layer can be easily formed by using a polymer as a matrix.

The anti-glare layer is set so that the regular reflection characteristic with respect to the light incident from the observer side and the regular transmission characteristic with respect to the light transmitted from the liquid crystal layer to the observer side satisfy a predetermined relationship. While suppressing the reflection of the surrounding image due to regular reflection of outside light, while maintaining high image clarity of transmitted light in the front direction, coloring of the image when viewed from an oblique direction is suppressed, wide field of view A high quality display image is realized in the corner.

The anti-glare layer having the internal scattering layer and the scattering surface is excellent in the balance between the regular reflection characteristic for the light incident from the observer side and the regular transmission characteristic for the light transmitted from the liquid crystal layer to the observer side. The antiglare layer having a haze value of 15 or more has regular reflection characteristics and specular transmission characteristics in a suitable range, and the above characteristics of the antiglare layer having a haze value of 25 or more are more excellent.

In particular, the gradation inversion phenomenon observed when the liquid crystal display device of the TN system or the STN system is observed from the direction tilted in the normal viewing angle direction is sufficient even if a phase difference compensating element having a tilted main axis is used. Cannot be reduced to For example,
When the viewing angle is tilted from the normal direction of the display surface to the normal viewing angle direction,
The display quality deteriorates from around a viewing angle of 30 °. The haze value of the anti-glare layer is preferably 40 or more, and more preferably 50 or more in order to suppress the deterioration of the display quality in the normal viewing angle direction.

The optical characteristics (the specular reflection characteristics and specular transmission characteristics) of the antiglare layer suitably used in the liquid crystal display device of the present invention are evaluated by the transmitted image sharpness measured by the image clarity measuring device, and the optical characteristics are evaluated. The width of the skewer is 0.5 mm
When the value of the transmitted image sharpness measured using the image clarity measuring device of No. 10 is 10 or more, the sharpness of the image due to the transmitted light in the front direction is kept high. Especially, the value of transmitted image sharpness is 1
When an antiglare of 5 or more is used, the sharpness of the image due to the transmitted light in the front direction is further improved.

The refractive index anisotropy Δn (550) of the liquid crystal material for light having a wavelength of 550 nm is 0.060 <Δn (55
0) <0.120 is preferably set. When the refractive index anisotropy Δn (550) of the liquid crystal material with respect to the light with the wavelength of 550 nm, which has the highest visibility, is out of this range,
An inversion phenomenon or a decrease in contrast ratio may occur depending on the viewing angle. The refractive index anisotropy Δn (550) of the liquid crystal material with respect to light having a wavelength of 550 nm is larger than 0.060,
By setting the range smaller than 0.120, it is possible to suppress the change in the phase difference depending on the viewing angle.
It is possible to further improve the change in contrast ratio and the inversion phenomenon in the lateral direction. Furthermore, the refractive index anisotropy Δn (550) of the liquid crystal material with respect to light having a wavelength of 550 nm is 0.
By setting in the range of 070 ≦ Δn (550) ≦ 0.095, the phase difference depending on the viewing angle can be more effectively and surely eliminated, so that the change of the contrast ratio and the inversion phenomenon in the lateral direction can be achieved. Can be improved more reliably. Further, in order to suppress the deterioration of the display quality in the normal viewing angle direction in the configuration using the antiglare layer having a haze value of 40 or more, Δn (550) is set to a range larger than 0.060 and smaller than 0.120. It is preferable that Δn (550) is 0.070 ≦ Δn (550)
It is more preferable to set it within the range of ≦ 0.095.

The phase difference compensating element has a refractive index ellipsoid of 3
The two mutually orthogonal main axes are a-axis, b-axis and c-axis,
When the main refractive indices are na, nb, and nc, na = n
A phase difference compensating element having a relationship of c> nb, in which the a axis is substantially parallel to the layer surface of the liquid crystal layer and the b axis is inclined with respect to the layer normal of the liquid crystal layer, It is preferable in combination with a liquid crystal layer having a positive uniaxial optical anisotropy.

At this time, the inclination angle of the b axis of the refractive index ellipsoid of the phase difference compensating element with respect to the layer normal to the liquid crystal layer is preferably set in the range of 15 ° to 75 °. By setting the tilt angle of the refractive index ellipsoid in this way, it is possible to effectively compensate for the phase difference due to the liquid crystal molecules. It is preferable to set the product (na−nb) × d of the difference between the main refractive indices na and nb of the phase difference compensation element and the thickness d in the range of 80 nm to 250 nm. By thus setting the product of the difference between the main refractive indices na and nb of the phase difference compensating element and the thickness d, the compensation effect of the phase difference compensating element can be reliably obtained.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments below.

FIG. 1 is a sectional view showing the structure of a liquid crystal display device 100 which is an embodiment of the present invention. The liquid crystal display device 100 is a normally white mode TN liquid crystal display device.

The liquid crystal display device 100 comprises a liquid crystal cell 1, polarizing plates 4 and 5 arranged so as to face each other with the liquid crystal cell 1 interposed therebetween, and between the polarizing plates 4 and 5 and the liquid crystal cell 1. And the anti-glare layer 16 provided on the observer side of the polarizer 4 provided on the observer side. Liquid crystal display device 100
Are driven by the drive circuit 17. Further, a backlight (not shown) provided below the polarizing plate 5 in FIG.
Display is performed using light from.

The liquid crystal cell 1 has electrode substrates 6 and 7 and a liquid crystal layer 8 provided between the electrode substrates 6 and 7. In the electrode substrate 6, a transparent electrode 10 made of ITO (indium tin oxide) is formed on a surface of a glass substrate (translucent substrate) 9 serving as a base on the liquid crystal layer 8 side, and an alignment film 11 is formed thereon. ing. The electrode substrate 7 is formed on the surface of the glass substrate (translucent substrate) 12 serving as a base on the liquid crystal layer 8 side.
A transparent electrode 13 made of TO is formed, and an alignment film 14 is formed thereon. Both transparent electrodes 10 and 13 are connected to a drive circuit 17.

Although FIG. 1 shows the structure for one pixel for simplification, almost all of the display portion of the liquid crystal cell 1 has the strip-shaped transparent electrodes 10 and 13 having a predetermined width and the glass substrate 9 and. The transparent electrode 10 on one glass substrate 9 and the transparent electrode 13 on the other glass substrate 12 are provided on the glass substrate 12 at predetermined intervals and intersect each other when viewed from a direction perpendicular to the substrate surface (here, orthogonal to each other). ) Is formed. The intersections of both transparent electrodes 10 and 13 correspond to pixel regions (regions corresponding to display pixels), and these pixel regions are arranged in a matrix on the entire surface of the liquid crystal display device.

Both electrode substrates 6 and 7 are attached to each other by a seal resin 15, and a liquid crystal layer 8 is enclosed in a space surrounded by the electrode substrates 6 and 7 and the seal resin 15. A voltage based on display data is applied to the liquid crystal layer 8 from the drive circuit 17 via the transparent electrodes 10 and 13.

The structure of the phase difference compensating elements 2 and 3 will be described with reference to FIG.

As shown in FIG. 2, the phase difference compensating elements 2 and 3 have three main refractive indices na, nb, in the directions of three axes a, b and c (principal axes of the index ellipsoid) orthogonal to each other.
nc. The coordinate axis xyz coordinate system in FIG. 2 is the phase difference compensating element 2 in the state of being arranged in the liquid crystal display device 100.
Is a coordinate system defined with respect to 3 and 3, the xy plane defines a plane parallel to the layer surface of the liquid crystal layer 8 (generally parallel to the substrate surface), and the z axis represents the layer normal of the liquid crystal layer 8 (generally displayed It is parallel to the surface normal). As shown in the drawing, the phase difference compensating elements 2 and 3 are generally flat plates (referred to as “phase difference compensating plate”), and their main surfaces are arranged parallel to the layer surface (or the substrate surface) of the liquid crystal layer 8. It In the following, for simplicity of description, a case will be described in which the phase difference compensating plates 2 and 3 are arranged such that their principal surfaces are parallel to the layer surface of the liquid crystal layer 8.

The phase difference compensating plates 2 and 3 are arranged so that the a-axis coincides with the y-axis as shown in FIG. 2, for example. The b-axes of the phase difference compensation plates 2 and 3 are inclined by θ from the z-axis in the direction of arrow A (counterclockwise in this case) with the a-axis as the central axis. The c-axis direction is the direction of arrow B from the x-axis direction (here, counterclockwise) with the a-axis as the central axis.
Is inclined to θ. In FIG. 2, the direction in which the b-axis tilted in the direction that gives anisotropy to the phase difference compensation plates 2 and 3 is projected on the xy plane is D.

The three main refractive indices na, nb and nc of the phase difference compensating plates 2 and 3 used in the liquid crystal display device 100.
Have a relationship of na = nc> nb. Therefore, the phase difference compensating plates 2 and 3 are uniaxial phase difference compensating plates having negative refractive index anisotropy. A first product represented by the product (nc-na) × d of the difference (refractive index anisotropy Δn) between the main refractive indexes na and nc of the phase difference compensating plates 2 and 3 and the thickness d of the phase difference compensating plate. Retardation value of is approximately 0 nm because na = nc. The product of the difference between the main refractive indices na and nb (refractive index anisotropy Δn) and the thickness d of the retardation compensating plate (na-nb).
The second retardation value represented by × d is 80n.
It is preferable to set in the range of m to 250 nm.
By setting this range, the phase difference compensating function of the phase difference compensating plates 2 and 3 can be surely obtained. Here, the thickness of the phase difference compensating plates 2 and 3 means a direction parallel to the layer normal line of the liquid crystal layer 8, that is, a direction normal to the display surface and the main surfaces of the phase difference compensating plates 2 and 3. The thickness in the direction is shown.

In the liquid crystal display device 100 of this embodiment, the liquid crystal cell 1, the phase difference compensating plates 2 and 3, and the polarizing plates 4 and 5 are arranged as shown in FIG. An absorption axis (also referred to as a polarization axis) AX1 of the polarizing plate 4 is an alignment film 1 provided on the same side as the polarizing plate 4 as viewed from the liquid crystal layer 8.
The rubbing direction P1 is parallel to the rubbing direction P1. Similarly, the absorption axis AX2 of the polarizing plate 5 is arranged so as to be parallel to the rubbing direction P2 of the alignment film 14 provided on the same side as the polarizing plate 5 as viewed from the liquid crystal layer 8.

The phase difference compensating plate 2 is arranged in the direction D shown in FIG.
(D1) is arranged so as to be parallel to the rubbing direction P1 on the alignment film 11 side, and in the phase difference compensating plate 3, the direction D (D2) shown in FIG. 2 is parallel to the rubbing direction P2 on the alignment film 14 side. It is arranged to be. Rubbing directions P1 and P
2, and the polarization axes AX1 and AX2 are orthogonal to each other.

The retardation compensating plates 2 and 3 are, for example, held on a matrix (also referred to as a support) made of a transparent organic polymer cross-linked with discotic liquid crystals that are tilted or hybrid-aligned. . As the matrix material of the phase difference compensating plates 2 and 3, triacetyl cellulose (TA
C) is most suitable, and a phase difference compensator having high reliability can be obtained. Other materials are polycarbonate (PC) and polyethylene terephthalate (PET)
Suitable is an organic polymer film with excellent environmental resistance and chemical resistance.

Next, the structure and function of the anti-glare layer 16 will be described with reference to FIG.

The anti-glare layer 16 suppresses the occurrence of a coloring phenomenon (typically, yellowing or bluing), that is, a reduction in color reproducibility, in the structure using the phase difference compensating element. The anti-glare layer 16 is set so that the regular reflection characteristic with respect to the light incident from the observer side and the regular transmission characteristic with respect to the light transmitted from the liquid crystal layer 8 to the observer side satisfy a predetermined relationship. While suppressing the reflection of the surrounding image due to regular reflection of light, the sharpness of the image of the transmitted light in the front direction is maintained high. As a result, coloring of the image when viewed from an oblique direction in the lateral direction (direction orthogonal to the normal viewing angle direction) is suppressed, and a high-quality display image with a wide viewing angle is realized.

The antiglare layer 16 has, for example, as shown in FIG. 4, an internal scattering layer 16a and a scattering surface 16b. The internal scattering layer 16a is formed of, for example, a material in which fine particles (filler) having a refractive index different from the refractive index of the polymer matrix are dispersed and mixed in a polymer matrix. Scatter (or diffusely reflect). The scattering surface 16b is a surface having an uneven shape, and mainly scatters external light (ambient light) incident from the observer side. The scattering surface 16b can be obtained by forming irregularities on the surface of the internal scattering layer 16a, or, as shown in FIG. 4, the internal scattering layer 16b.
It is also possible to form another film on the surface of a and to form irregularities on the surface of the film.

The internal scattering layer 16a contains, for example, an ultraviolet curable resin (for example, an acrylate monomer, a cellulose derivative or a mixture thereof) and about 10 to 30 parts by weight of a filler (for example, silica fine particles having a uniform particle size). It is obtained by curing a dispersion and mixture.

As described above, the anti-glare layer 16 having the internal scattering layer 16a and the scattering surface 16b has the specular reflection characteristic for the light incident from the observer side and the specular transmission characteristic for the light transmitted from the liquid crystal layer to the observer side. Excellent balance with. When the regular reflection light from the surface of the liquid crystal display device 100 is strong, the surrounding image due to the external light becomes visible like a mirror surface. Further, if the intensity of the regular transmitted light that is transmitted through the liquid crystal layer 8 in parallel with the layer normal is weak, the display by the liquid crystal layer 8 will be blurred. By controlling the above-mentioned characteristics of the anti-glare layer 16 in a well-balanced manner, high display quality can be realized.

The function of the antiglare layer 16 according to the present invention will be described in more detail.

The liquid crystal molecules in the liquid crystal layer, whether no voltage is applied or when an appropriate voltage is applied,
Except for the liquid crystal molecules near the inner surface of the liquid crystal cell, they are aligned at a certain angle with respect to the inner surface of the liquid crystal cell. Here, “aligning at a certain fixed angle” may include not only a tilted state but also an alignment substantially parallel to or perpendicular to the inner surface of the liquid crystal cell.

The observer observes the liquid crystal layer from a viewing angle α which is a direction oblique to the surface of the liquid crystal cell (a direction inclined from the direction normal to the display surface). When the anti-glare layer is not provided, the observer only observes, of the light entering the liquid crystal cell from the light source, only the light passing through the liquid crystal layer in the oblique direction from the normal direction by the viewing angle α. Therefore, the retardation value of the liquid crystal layer with respect to the light observed by the observer becomes a constant value. Therefore, a coloring phenomenon occurs due to the difference in the wavelength dispersion of the retardation values of the retardation compensation element and the liquid crystal layer.

On the other hand, when the anti-glare layer is provided, the light passing through the liquid crystal layer is forward-scattered by the anti-glare layer, so that the observer who observes the liquid crystal layer from the direction of the visual angle α sees the liquid crystal layer. Not only the light passing obliquely by the viewing angle α from the line direction, but also the light passing through the liquid crystal layer at various angles other than the viewing angle α are simultaneously observed.
Since the retardation values of the liquid crystal layer with respect to the light passing through the liquid crystal layer at different angles are different depending on the angles, the tint of the light passing through each angle (the chromaticity value in the chromaticity diagram) is also different. Therefore, when the anti-glare layer is provided, even if the liquid crystal layer is observed from a certain viewing angle α, a plurality of lights passing through the liquid crystal layer are observed at different angles, which results in a plurality of different tints (colors). The chromaticity values (chromaticity values in the chromaticity diagram) are averaged to observe light (chromaticity values in the chromaticity diagram).

Therefore, a retardation compensating element capable of improving the viewing angle characteristics of the liquid crystal display device is selected according to the display mode and application, and the wavelength dispersion of retardation values of the selected retardation compensating element and the liquid crystal layer is taken into consideration. By properly setting the regular reflection characteristic and the regular transmission characteristic of the anti-glare layer, it has a high contrast and a wide viewing angle characteristic, and at the same time, there is no coloring in the oblique direction (direction inclined from the normal direction to the display surface). It is possible to realize a liquid crystal display device having a good white balance and excellent color reproducibility.

Antiglare layer 16 having a haze value of 15 or more
Has a specular reflection property and a specular transmission property in a preferable range, and the above property of the antiglare layer having a haze value of 25 or more is further excellent. In particular, it is possible to effectively suppress the coloring phenomenon that occurs when the viewing angle is inclined in the lateral direction in the TN type or STN type liquid crystal display device. Furthermore, when the anti-glare layer 16 having a haze value of 40 or more is used, the display quality deteriorates when the viewing angle is tilted in the normal viewing angle direction in a TN or STN liquid crystal display device (typically in black display). Gradation inversion) can be suppressed. In order to suppress the viewing angle dependence of the display quality in the normal viewing angle direction, the antiglare layer 1 having a haze value of 50 or more is used.
It is more preferable to use 6.

The optical characteristics (the specular reflection characteristic and the specular transmission characteristic) of the anti-glare layer 16 preferably used in the liquid crystal display device 100 are evaluated by the transmitted image sharpness measured by the image clarity measuring device, and the optical skew is obtained. Width of 0.5m
When the value of the transmitted image sharpness measured using the image clarity measuring machine of m is 10 or more, the sharpness of the image due to the transmitted light in the front direction is kept high. In particular, when antiglare having a transmitted image sharpness value of 15 or more is used, the sharpness of the image due to the transmitted light in the front direction is further improved.

The liquid crystal material contained in the liquid crystal layer 8 has a wavelength of 550.
The refractive index anisotropy Δn (550) with respect to light having a wavelength of 0.
It is preferably in the range of 060 <Δn (550) <0.120. If the refractive index anisotropy Δn (550) of the liquid crystal material with respect to light having a wavelength of 550 nm, which has the highest visibility, is out of this range, an inversion phenomenon or a decrease in contrast ratio may occur depending on the viewing angle direction. When the refractive index anisotropy Δn (550) of the liquid crystal material with respect to light having a wavelength of 550 nm is in the range of 0.060 <Δn (550) <0.120, the phase difference depending on the viewing angle can be reduced. Therefore, the change of the contrast ratio and the inversion phenomenon in the lateral direction can be suppressed more effectively. Furthermore, wavelength 550n
Refractive index anisotropy of liquid crystal material with respect to m light Δn (550)
Is within the range of 0.070 ≦ Δn (550) ≦ 0.095, the phase difference depending on the viewing angle can be further effectively and surely reduced, so that the change of the contrast ratio,
It is possible to more reliably suppress the inversion phenomenon in the lateral direction and the normal viewing angle direction.

The liquid crystal material used in this embodiment is a nematic liquid crystal material having positive dielectric anisotropy and positive refractive index anisotropy, and constitutes a horizontal alignment type liquid crystal layer. The horizontal alignment type liquid crystal layer is a liquid crystal layer in which liquid crystal molecules are aligned parallel to the surface of the substrate (ignoring a small pretilt angle) when no voltage is applied, and is not limited to the above-mentioned TN system or STN system. However, like the TN method and the STN method,
By applying the present invention to a liquid crystal display device having a twisted liquid crystal layer, a remarkable effect can be obtained.

Of the b axis of the refractive index ellipsoid of the phase difference compensating element,
It is preferable to set the tilt angle of the liquid crystal layer with respect to the layer normal in the range of 15 ° or more and 75 ° or less. By setting the tilt angle of the refractive index ellipsoid in this way, it is possible to effectively compensate for the phase difference due to the liquid crystal molecules. The product of the difference between the main refractive indices na and nb of the phase difference compensation element and the thickness d (na-n
It is preferable to set b) × d in the range of 80 nm to 250 nm. By thus setting the product of the difference between the main refractive indices na and nb of the phase difference compensating element and the thickness d, the compensation function of the phase difference compensating element can be reliably obtained.

The liquid crystal display device of the present invention will be described below.
A more specific embodiment will be described.

(Embodiment 1) In Embodiment 1, in the liquid crystal display device 100 shown in FIG. 1, the anti-glare layer 1 is used.
As No. 6, samples (specific examples) A11 to A14 in which the antiglare layer 16 having the haze value shown in Table 1 was provided on the observer side of the polarizing plate 4 were prepared. An Optomer AL manufactured by JSR was used as the alignment films 11 and 14 of the liquid crystal cell 1, and the cell thickness of the liquid crystal cell 1 (thickness of the liquid crystal layer 8) was 5 μm.
And A liquid crystal material having a refractive index anisotropy Δn (550) of 0.080 with respect to light having a wavelength of 550 nm was used for the liquid crystal layer 8. Further, as reference examples, samples A201 and A202 using the anti-glare layer 16 having the values shown in Table 1 were used.
Prepared. The haze value is defined as the ratio of the diffused light transmittance to the total light transmittance expressed as a percentage. Here, the value obtained by the haze meter manufactured by Nippon Denshoku Industries Co., Ltd. is used.

As the phase difference compensating plates 2 and 3,
A retardation compensator in which a discotic liquid crystal is tilted is used. The first retardation value (nc-na) × d is 0 nm, the second retardation value (na-nb) × d is 100 nm, and the direction of the main refractive index nb shown in FIG. 2 is the z-axis in the xyz coordinate system. 2 from the direction of arrow A
The tilt angle θ of the index ellipsoid is 0 ° and the main refractive index nc is tilted about 20 ° from the x-axis direction in the direction of arrow B to about 20 °.
The one having a degree of ° was prepared and used. In addition, Embodiment 2 described later
The same phase difference compensating element was used also in and.

[Table 1] Sample A11 A12 A13 A14 A201 A202 Haze value 15.5 25.0 30.3 38.7 0.40 9.05

Table 2 shows the results of visual evaluation of the samples A11 to A14 and the reference samples A201 and A202 with respect to the reflection preventing property of reflected light and the coloring of the image in the lateral direction.

[Table 2] Sample A11 A12 A13 A14 A201 A202 Reflected light reflection preventive property 4 4 5 5 1 3 Image coloring ○ ◎ ◎ ◎ ◎ × △

The reflection preventing property of reflected light in Table 2 is
The criteria for the visual evaluation regarding the coloring of the image are as follows.

<Prevention of reflection of reflected light> 5: No reflected image is visible 4: Reflected image is not visible 3: Some blurring, but you can see what looks like a reflection image 2: Slightly blurred, but reflected image is visible 1: The reflected image is clearly visible <Coloring of image> ◎: No coloring ○: Little coloring △: colored ×: Large coloring

Further, in the liquid crystal display devices of Samples A11 and A14 and Reference Sample A202, the color reproducibility of the display image when the viewing angle is tilted to 50 ° and 60 ° in the lateral direction is represented by the chromaticity value (x, The results evaluated in y) are shown in Table 3. The chromaticity value was measured using BM-7 manufactured by Topcon.

[Table 3] Sample A11 A14 A202 Chromaticity value xy xy xy 50 ° 0.3581 0.3675 0.3558 0.3647 0.3609 0.3695 60 ° 0.3647 0.3650 0.3587 0.3612 0.3700 0.3696

From Table 3, the viewing angles are 50 ° and 6 in the lateral direction.
The chromaticity values (x, y) when tilted to 0 ° are the same as those of the reference sample A in the samples A11 and A14 of this embodiment.
Compared to 202, both x and y values are smaller. The direction in which the x and y values are large is the yellow direction on the chromaticity diagram,
Since the direction in which the x and y values are small is the blue direction on the chromaticity diagram, it can be seen that the sample of this embodiment suppresses the yellow tint when the viewing angle is tilted in the horizontal direction. That is, it can be seen that the color reproducibility does not decrease even if the viewing angle is tilted.

The sample A14 is the sample A11.
It can be seen that the yellow tint is further suppressed compared to. Since human eyes can recognize that the difference in x and y values is 0.005 as a difference in color tone, the samples A11 and A14 of the present embodiment suppress yellowishness when the viewing angle is tilted in the lateral direction. Can be said to have been. Especially sample A
It can be seen that in No. 14, the yellow tint is further suppressed.

As can be seen from Tables 2 and 3, the samples A11 to A14 of the first embodiment were confirmed visually and by measurement that the coloring of the image when observed in the lateral direction was suppressed, It can be seen that the quality is good. In particular, in Samples A12 to A14, it can be seen that the coloring of the image is further suppressed and a higher quality display is realized.

As described above, in order to suppress the coloring (horizontal direction) of the image which is peculiar to the case where the retardation compensating plate is used, the anti-glare layer 16 provided on the surface of the front polarizing plate 4 has a haze value of 15 or more. It is understood that the above is preferable, and the number of 25 or more is more preferable.

Further, it will be described that the display quality in the normal viewing angle direction can be improved by manufacturing the liquid crystal display device 100 using the antiglare layer 16 having a haze value of 40 or more.

Samples B11 to B15 were prepared in the same manner as described above except that the antiglare layer 16 having the haze value shown in Table 4 was used as the antiglare layer 16. Further, for comparison, reference samples B201 and B202 provided with the antiglare layer 16 having a haze value of 40 or less were prepared.

[Table 4] Sample B11 B12 B13 B14 B15 B201 B202 Haze value 41.0 45.5 50.1 63.7 70.8 10.5 35.3

The results of visual evaluation of the coloring of the images of the samples B11 to B15 and the reference samples B201 and B202 observed at the viewing angles of 50 °, 60 ° and 70 ° in the normal viewing angle direction (downward). Is shown in Table 5. Table 6 shows the results of evaluation of the color reproducibility of the display image at the viewing angle of 60 ° by the chromaticity value (x, y).
In Table 5, ∘ indicates no coloration, Δ indicates coloration is recognized but within an allowable range, and x indicates coloration exceeding the allowable range. In addition, the sample B1
FIG. 5 shows applied voltage-transmittance characteristics (VT characteristics) at the viewing angle of 50 ° in the normal viewing angle direction for Sample Nos. 2 and B15 and the reference sample B201.

[Table 5] Samples B11 B12 B13 B14 B15 B201 B202 50 ° ○ ○ ○ ○ ○ × × 60 ° × △ ○ ○ ○ × × 70 ° × × ○ ○ ○ × ×

[Table 6] Samples B11 B12 B13 B14 B15 B201 B202 x 0.3610 0.3602 0.3584 0.3543 0.3512 0.3696 0.3661 y 0.3650 0.3643 0.3637 0.3600 0.3579 0.3710 0.3703

From Table 5, samples B11 to B15 were not colored even when the viewing angle was tilted to 50 ° in the normal viewing angle direction, and the display quality was good. In particular, sample B1
Regarding 3 to B15, coloring was not confirmed even when the viewing angle was tilted down to 70 °, and the viewing angle characteristics in the normal viewing angle direction were also very good. On the other hand, in reference samples B201 and B202, when the viewing angle is tilted down to 50 °, coloring is severe, and the viewing angle dependence of the display quality in the normal viewing angle direction is not sufficiently suppressed.

Further, from Table 6, samples B11 to B15
Compared to the reference sample B201, the chromaticity value x was 0.
0086 or more, and the chromaticity value y is reduced by 0.0060 or more, and it can be seen that the yellow tint is suppressed. Compared with the reference sample B201, the samples B11 to B15 of the present embodiment have a smaller chromaticity value x of 0.0051 or more and a smaller chromaticity value y of 0.0053 or more, and the yellowness is suppressed. I understand.

Especially, the samples B13 to B15 are 0.0112 in chromaticity value x when compared with the reference sample B202.
As described above, the chromaticity value y is reduced by 0.0073 or more,
Further, as compared with the reference sample B202, the chromaticity value x is 0.0077 or more, and the chromaticity value y is 0.0066 or more, which shows that the yellow tint is further suppressed.

Further, from FIG. 5, samples B12 and B
It can be said that in No. 15, the inversion phenomenon of the gradation in the normal viewing angle direction is suppressed as compared with the reference sample B201. In particular, in Sample B15, almost no floating (local increase) in transmittance due to voltage application was observed from around the halftone voltage to near the black display voltage, and it was found that the gradation inversion phenomenon was further suppressed. .

As described above, when the antiglare layer 16 having a haze value of 40 or more is used (B11 to B15), the viewing angle dependence of the display quality in the normal viewing angle direction (gradation inversion or coloring) can be effectively suppressed. Haze value is 50 or more (Sample B
13 to B15) is preferable, and 70 or more (Sample B1
5) is more preferable.

(Embodiment 2) As described above, by providing the antiglare layer having a large haze value, the viewing angle dependency of display quality can be reduced. However, depending on the anti-glare layer, the displayed image may be blurred and observed. In the second embodiment, an anti-glare layer that can maintain the image sharpness sufficiently high will be described.

Similar to the first embodiment, in the liquid crystal display device 100 shown in FIG. 1, as the anti-glare layer 16, the anti-glare layer 1 having the values of the transmitted image sharpness shown in Table 7 is used.
Sample 6 in which 6 is provided on the observer side of the polarizing plate 4 (specific example) A
21 to A24 were prepared. As a reference example, Sample A using the anti-glare layer 16 having the values shown in Table 7
301 and A302 were prepared. The haze value of the anti-glare layer used in these samples is 10 or more and 40
Is less than.

The transmitted image sharpness was measured using an image clarity measuring machine (manufactured by Suga Test Instruments Co., Ltd.) having an optical skewer width of 0.5 mm. The measuring method will be described below.

The image clarity measuring device records the light transmitted through the slit as parallel light rays to the sample perpendicularly and detects the transmitted light through the moving optical skewer, and the fluctuation of the detected light quantity as a waveform. Measurement system device. The optical skewer has a ratio of the widths of the dark portion and the light portion of 1: 1 and the widths thereof are 0.125 mm, 0.25 mm, 0.5 mm,
There are five types, 1.0 mm and 2.0 mm, and the moving speed is about 10 mm / min. When the maximum value of the transmitted light intensity when the optical skewer is the light portion is M and the minimum value of the transmitted light intensity when the optical skewer is the dark portion is m, the transmitted image sharpness C (%) is given by the following equation. .

[0091] C = {(M−m) / (M + m)} × 100

The transmitted image sharpness in the present invention is
The value when the width of the optical skewer is 0.5 mm is used. In addition, it was experimentally confirmed that the value at this time had the highest consistency with the result of the visual evaluation of observing the liquid crystal panel with a magnifying glass.

[Table 7] Sample A21 A22 A23 A24 A301 A302 Transmission image sharpness 10.5 15.0 23.8 64.5 4.0 7.5

Table 8 shows the results of visual evaluation of the samples A21 to A24 and the reference samples A301 and A302 with respect to the reflection preventing property of reflected light and the sharpness of the image of transmitted light in the front direction.

[Table 8] Sample A21 A22 A23 A24 A301 A302 Reflected light reflection preventing property 5 4 3 2 5 5 Transmission image sharpness ○ ◎ ◎ ◎ ◎ × △

The criteria for preventing reflected light reflection in Table 8 are the same as those described in the first embodiment, and the criteria for visual evaluation regarding transmitted image sharpness are as follows.

<Transparent image sharpness> The results of observing the pixels of the liquid crystal display device with a magnifying glass or the like were classified into the following four stages.

[0098] ◎: The outline of the pixel can be confirmed ○: Some blurring, but the outline of pixels can be confirmed △: Pixel outline cannot be confirmed due to slight blurring ×: The contour of the pixel cannot be confirmed

Although the magnification of observation depends on the resolution of the liquid crystal display device, for example, in the case of XGA, the observation magnification is about 100 times.

As can be seen from Table 8, in the samples A21 to A24 of the second embodiment, the contour of the pixel can be confirmed even by visually observing the transmitted light in the front direction with a loupe, etc. The sharpness of the image is maintained.
In particular, for samples A22 to A24, the transmitted light in the front direction can be visually confirmed with a loupe or the like without blurring the pixel outlines, and the sharpness of the image due to the transmitted light in the front direction can be kept higher. Is dripping From this fact, in order to keep the image sharpness due to the transmitted light in the front direction high, the value of the transmitted image sharpness measured by the image clarity measuring instrument when the width of the optical skew is 0.5 mm. It is understood that it is preferable to use the above antiglare layer, and it is more preferable to use 15 or more antiglare layers.

Further, the result of the similar evaluation of the transmitted image sharpness when the antiglare layer 16 having a haze value of 40 or more is used will be described below. Concrete samples B21 and B21 having the same structure as the above sample except that the antiglare layer 16 having the transmitted image sharpness shown in Table 9 was used.
22, B23, B24 and B25 and reference samples B301 and B302 were prepared.

[Table 9] Samples B21 B22 B23 B24 B25 B301 B302 Transmission image sharpness 10.2 13.6 15.0 28.9 39.5 3.4 7.8

Table 10 shows the results of visual evaluation of the sharpness of the image by the transmitted light in the front direction of the samples B21 to B25 and the reference samples B301 and B302.

The visual evaluation judgment conditions are as follows: 6: the contour of the pixel can be clearly confirmed, 5: the pixel can be confirmed, 4: the pixel contour is slightly blurred but the pixel contour can be confirmed, 3: the pixel contour is slightly blurred, and the pixel contour can be confirmed. No, 2: Pixels cannot be confirmed,
1: Pixels could not be confirmed at all.

[Table 10] Samples B21 B22 B23 B24 B25 B301 B302 Transmission image sharpness 4 5 6 6 6 1 2

From Table 10, sample B21 of this embodiment is shown.
From -B25, the contour of the pixel can be confirmed, and the sharpness of the transmitted image is maintained. In particular, in the samples B23 to B25 of this embodiment, the contours of the pixels can be clearly confirmed, and the transparency of the transmitted image is high. On the other hand, in the reference samples B301 and B302, the contour of the pixel cannot be confirmed, and the transparency of the transmitted image is low.

Therefore, in order to maintain high image clarity due to transmitted light in the front direction, the transmitted image sharpness value should be 10 or more even when an antiglare layer having a haze value of 40 or more is used. It can be seen that it is preferably 15 or more, and more preferably 15.

(Third Embodiment) In the third embodiment, in the liquid crystal display device 100 shown in FIG. 1, as alignment films 11 and 14 of the liquid crystal cell 1, Optomer AL manufactured by JSR Corporation is used.
And the cell thickness of the liquid crystal cell 1 (thickness of the liquid crystal layer 8) is 5 μm.
m. The liquid crystal layer 8 has a refractive index anisotropy Δn (550) of 0.070 for light having a wavelength of 550 nm, respectively.
3 using liquid crystal materials that are 0.080 and 0.095
One example sample, A31, A32 and A33, was made. In addition, specific example samples A31, A32 and A3
For No. 3, the antiglare layer 16 having the haze value and the transmitted image sharpness shown in Table 11 was used.

For comparison, in the liquid crystal display device 100 shown in FIG. 1, the liquid crystal material of the liquid crystal layer 8 has a refractive index anisotropy Δn (550) of 0.060 and 0.120 with respect to light having a wavelength of 550 nm. The reference samples A401 and A402 set to No. 1 were produced. In addition, the anti-glare layer 16 having the haze value and the transmitted image sharpness shown in Table 11 was used for the reference samples A401 and A402.

[Table 11] Sample A31 A32 A33 A401 A402 Haze value 30.3 25.0 15.4 10.3 7.0 Transmission image sharpness 15.0 23.8 30.3 4.0 7.5

With respect to the samples A31 to A33 and the reference samples A401 and A402, the viewing angle characteristics of the respective liquid crystal display devices were evaluated using a measurement system as shown in FIG.

The viewing angle characteristic evaluation shown in FIG. 6 includes a light receiving element 18, an amplifier 19 and a recording device 20. In this measurement system, the observer-side surface 100a of the liquid crystal display device 100 is installed so as to be parallel to the xy plane of the orthogonal coordinate axes xyz (the orthogonal coordinate system of this measurement system is the xyz coordinate system shown in FIG. 2). Matches.).

Light receiving element 1 that receives light at a fixed stereoscopic light receiving angle
The reference numeral 8 is arranged at a position a predetermined distance from the coordinate origin in a direction that forms an angle φ (visual angle) with respect to the z direction that is the normal direction of the viewer-side surface 100a of the liquid crystal display device 100.
At the time of measurement, the liquid crystal display device 100 installed in the measurement system is irradiated with monochromatic light having a wavelength of 550 nm from the surface opposite to the surface 100a. As a result, part of the monochromatic light transmitted through the liquid crystal display device 100 enters the light receiving element 18. Then, the output of the light receiving element 18 is amplified to a predetermined level by the amplifier 19, and then recorded by the recording device 20 including a waveform memory, a recorder, and the like.

Sample A3 of the third embodiment is applied to this measurement system.
1 to A33 and reference samples A401 and A4
No. 02 was installed to measure the relationship between the voltage applied to each liquid crystal display device and the output level of the light receiving element 18 when the light receiving element 18 was fixed at a constant angle φ. Here, the angle φ is 5
Arrangement of the light-receiving element 18 on the assumption that the light-receiving element 18 is arranged at 0 °, the x-axis direction is the lower side of the display surface (normal viewing angle direction), and the y-axis direction is the left side of the display surface. The measurement was performed by changing the position in the upward direction (counter-viewing angle direction) and the lateral direction.

The measurement results of samples A31 to A33 of this embodiment are shown in FIGS. 7A to 7C, and the measurement results of reference samples A401 and A402 are shown in FIG.
It shows in (a)-(c). 7 (a) to (c) and FIG.
FIGS. 7A to 7C are graphs showing the light transmittance (applied voltage-transmittance characteristic) with respect to the voltage applied to each liquid crystal display device, and FIG. 7A and FIG. 7 (b) and 8 (b) are the results of measurement from the right direction, and FIGS. 7 (c) and 8 (c) are measurement results from the left direction. This is the result.

In FIGS. 7A to 7C, the curves L31a, L31b, and L31c shown by the alternate long and short dash lines show the results of the sample A31 in which the liquid crystal material of Δn (550) = 0.070 is used for the liquid crystal layer 8. The solid lines L32a, L32b, and L32c indicate Δn (550) = 0.080 in the liquid crystal layer 8.
The results of Sample A32 using the liquid crystal material of No. 3 are shown, and the curves L33a, L33b and L33c shown by the broken lines show the results of Sample A33 using the liquid crystal material of Δn (550) = 0.095 in the liquid crystal layer 8. In FIGS. 8A to 8C, curves L401a, L401b, and L401c shown by solid lines show the results of the reference sample A401 using the liquid crystal material of Δn (550) = 0.060 for the liquid crystal layer 8, Curves L402a, L402b and L shown by broken lines
402c shows the result of the reference sample A402 in which the liquid crystal material of Δn (550) = 0.120 is used for the liquid crystal layer 8.

Regarding the applied voltage-transmittance characteristic in the upward direction, the samples A31 to A33 of this embodiment are shown in FIG.
As indicated by L31a, L32a, and L33a in (a), it was confirmed that the transmittance was sufficiently reduced as the voltage was increased. On the other hand, reference sample A40
In Example 2, as shown by L402a in FIG. 8 (a), the transmittance did not decrease sufficiently even when the voltage was increased.
In 401, as shown by L401a in FIG. 8A, there was observed a contrast ratio inversion phenomenon in which the transmittance once decreased as the voltage increased and then increased again.

Similarly, regarding the applied voltage-transmittance characteristic in the right direction, in the samples A31 to A33 of the present embodiment, the voltage becomes high as shown by L31b, L32b and L33b in FIG. 7B. It was confirmed that the transmittance decreased to almost 0 with the increase. On the other hand, in the sample A401 for reference, as shown by L401b in FIG. 8B, the transmittance decreases to almost 0 as the voltage increases, but in the sample A402 for reference,
As indicated by L402b in (b), there was observed a contrast ratio inversion phenomenon in which the transmittance once decreased and then increased again as the voltage became higher.

Similarly, regarding the applied voltage-transmittance characteristic in the leftward direction, in the samples A31 to A33 of the present embodiment, the voltage becomes higher as shown by L31c, L32c and L33c in FIG. 7C. It was confirmed that the transmittance decreased to almost 0 with the increase. On the other hand, in the sample A401 for reference, as shown by L401c in FIG. 8C, the transmittance decreases to nearly 0 as the voltage increases, but in the sample A402 for reference,
As indicated by L402c in (c), there was observed an inversion phenomenon of the contrast ratio in which the transmittance once decreased as the voltage increased and then increased again.

From the above results, as the liquid crystal material of the liquid crystal layer 8, the refractive index anisotropy Δn (55
0) is set to 0.060 and 0.120, respectively, in the liquid crystal display devices of the reference samples A401 and A402, as shown in FIG. 8A to FIG. It can be seen that, in practice, sufficient display quality cannot be obtained because the transmittance during application does not decrease sufficiently.

Further, the results of examining the influence of the retardation value of the liquid crystal layer 8 on the viewing angle characteristics of the liquid crystal display device 100 using the antiglare layer 16 having a haze value of 40 or more will be described.

Samples B31 to B33 were prepared in the same manner as the samples A31 to A33 in the above-described embodiment except that the antiglare layer 16 was different, and the reference samples B401 and B402 were prepared in the same manner as the reference samples A401 and A402. Was produced. Table 12 shows the haze value and transmitted image sharpness of the anti-glare layer 16 used for each sample.

[Table 12] Sample B31 B32 B33 B401 B402 Haze value 41.0 50.1 70.8 10.5 35.3 Transmission image sharpness 28.0 20.4 15.2 3.4 5.9 nm 1.50 1.48 1.50 1.50 1.50 np 1.47 1.43 1.40 1.50 1.50 | nm-np | 0.03 0.05 0.10 0.00 0.00

Further, here, as the anti-glare layer 16, one formed by using a material in which plastic beads having scattering centers are dispersed in a polymer matrix is used. The refractive index nm of the polymer matrix of the anti-glare layer 16 used in each sample, the refractive index np of the plastic beads, and the absolute value of the difference between them are shown in Table 1.
2 shows.

For the samples B31 to B33 and the reference samples B401 and B402, the applied voltage-transmittance characteristic of each liquid crystal display device was measured using the measurement system shown in FIG. The viewing angle characteristics were evaluated. For samples B31 to B33,
7A to 7C, similar to Samples A31 to 33.
The results shown in are obtained. Regarding the reference samples B401 and B402, the reference samples A401 and A402 are obtained.
Similar to 402, the results shown in FIGS. 8A to 8C were obtained.

From the above results, even when the antiglare layer having a haze value of 40 or more is used, the refractive index anisotropy Δ with respect to the light having the wavelength of 550 nm as the liquid crystal material of the liquid crystal layer 8 is Δ.
In the liquid crystal display devices of the reference samples B401 and B402 in which n (550) was set to 0.060 and 0.120, respectively, as shown in FIGS. 8 (a) to 8 (c), the inversion phenomenon occurred. It can be seen that, in practice, sufficient display quality cannot be obtained because the transmittance when a voltage is applied does not decrease sufficiently. Furthermore, in the liquid crystal display devices B31 to 33 using the anti-glare layer having a haze value of 40 or more,
The gradation inversion phenomenon was suppressed even in the normal viewing angle direction, and excellent viewing angle characteristics were exhibited.

Table 13 shows the results of measuring the chromaticity values of Samples B31 to B33 and Reference Sample B401. The measurement of the chromaticity value was performed using the above-mentioned device.

[Table 13] Samples B31 B32 B33 B401 x 0.3606 0.3578 0.3504 0.3696 y 0.3656 0.3649 0.3561 0.3710

As can be seen from Table 13, sample B31
To B33 are chromaticity values x as compared with the reference sample 401.
It is 0.0090 or more and the chromaticity value y is 0.0054 or more, which indicates that the yellow tint is suppressed.
As a result of various studies, it was found that the coloring phenomenon can be suppressed by using an internal scattering layer in which particles having scattering centers are dispersed in a matrix and using particles having a refractive index different from that of the matrix.

Furthermore, the tilt angle θ of the refractive index ellipsoids of the phase difference compensating plates 2 and 3 of the liquid crystal display device 100 having the antiglare layer having a haze value of 15 or more and 40 or more (FIG. 2).
As a result of investigating the dependency of the applied voltage-transmittance characteristic on the inclination angle θ by changing the reference voltage), when the angle is within the range of 15 ° ≦ θ ≦ 75 °, the retardation compensation plates 2 and 3 with respect to the liquid crystal layer 8 are examined. It was found that the optical compensation effect becomes reliable and a wide viewing angle liquid crystal display device can be realized. On the contrary,
With a retardation compensator having an inclination angle of less than 15 ° or more than 75 °, the viewing angle was not widened and sufficient viewing angle characteristics could not be obtained. In the phase difference compensating plate having an inclination angle of less than 15 ° or more than 75 °, it was observed that the viewing angle in the anti-viewing angle direction tends to be narrowed.

Furthermore, the second retardation values (na-n) of the phase difference compensating plates 2 and 3 of the liquid crystal display device 100 are used.
As a result of investigating the influence on the viewing angle characteristics by changing b) × d, when this value is in the range of 80 nm or more and 250 nm or less, the optical compensation effect on the liquid crystal layer 8 of the phase difference compensating plates 2 and 3 is surely obtained. It was found that a liquid crystal display device having a wide viewing angle can be realized. On the other hand, the second retardation value (na−nb) × d is less than 80 nm or more than 250 nm, the phase difference compensating plate is particularly
The viewing angle in the lateral direction tended to be narrowed.

In the above-mentioned embodiment, the two retardation compensating plates 2 and 3 are arranged on both sides of the liquid crystal cell 1. However, even if only one of them is arranged on one side of the liquid crystal cell 1, it is as described above. It is possible to obtain various viewing angle characteristics. However, when one phase difference compensating plate is used, the vertical viewing angle characteristics are balanced and improved, but the horizontal viewing angle characteristics may become asymmetric. On the other hand, when two sheets are provided, the vertical viewing angle characteristics are improved as in the case of one sheet, and the horizontal viewing angle characteristics are symmetrical, so that the vertical viewing angle characteristics are improved. It Furthermore, when two retardation compensation plates are arranged, both may be arranged on one side of the liquid crystal cell 1 in an overlapping manner. Furthermore, 3
It is also possible to use more than one phase difference compensating plate.

The phase difference compensating element that can obtain the effects of the present invention is not limited to the phase difference compensating element exemplified in the above embodiment. In the above embodiment, the preferred retardation compensating element has been described by taking the liquid crystal layer (TN system or STN system) having positive uniaxial optical anisotropy as an example. However, depending on the display mode of the liquid crystal display device, Any phase difference compensating element capable of compensating for the viewing angle dependency may be used. It is also possible to use a phase difference compensating element in which the principal axis of the index ellipsoid of the phase difference compensating element is substantially parallel to the normal direction of the surface of the phase difference compensating element. Further, the phase difference compensating element capable of obtaining the effect of the present invention is not limited to a uniaxial phase difference compensating element having a negative optical anisotropy, but a phase difference compensating element having a positive optical anisotropy or a biaxial property. It is also possible to use a retardation compensation element having the above optical anisotropy.

The present invention is not limited to the TN mode and the STN mode, but can be turned on / off by utilizing the electro-optical characteristics of liquid crystal.
It can be applied to all display modes in which OFF display operation is performed.

[0135]

According to the present invention, there is provided a liquid crystal display device capable of realizing display with a wide viewing angle and high color reproducibility.

By providing an anti-glare layer on the observer side of the liquid crystal display device and setting its regular reflection characteristic and regular transmission characteristic in desired ranges, reflection of reflected light is suppressed and transmitted light in the front direction is suppressed. While maintaining high image sharpness, it is possible to suppress the occurrence of image coloring (yellowing or bluing) that is peculiar to using a retardation compensator when viewed from an oblique direction. As a result, it is possible to realize a liquid crystal display device having a high-quality display image with a wide viewing angle in which the image is not colored from any direction.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a liquid crystal display device 100 according to an embodiment of the present invention.

FIG. 2 is a phase difference compensating element 2 in the liquid crystal display device 100.
It is a perspective view which shows the direction of the main refractive indexes of 3 and 3.

3 is a perspective view showing an optical arrangement of a liquid crystal cell 1, retardation compensation elements 2 and 3, and polarizing plates 4 and 5 in a liquid crystal display device 100. FIG.

FIG. 4 is an anti-glare layer 1 in the liquid crystal display device 100.
It is sectional drawing which shows the structure of 6.

FIG. 5 is a graph showing applied voltage-transmittance characteristics of the liquid crystal display device of the embodiment according to the present invention and the liquid crystal display device of the reference example.

FIG. 6 is a perspective view showing a measurement system for evaluating the viewing angle dependency of the liquid crystal display device.

7A to 7C are graphs showing applied voltage-transmittance characteristics of the liquid crystal display device according to the third embodiment.

8A to 8C are graphs showing applied voltage-transmittance characteristics of the liquid crystal display device of the reference example.

[Explanation of symbols]

1 Liquid crystal cell 2, 3 Phase difference compensator (Phase difference compensator) 4 Front polarizing plate 5 Back polarizing plate 6, 7 electrode substrate 8 Liquid crystal layer 9, 12 translucent substrate 10, 13 Transparent electrode 11, 14 Alignment film 15 Seal resin 16a Anti-glare internal scattering layer 16b Anti-glare scattering surface 17 Drive circuit 18 Light receiving element 19 amplifier 20 recording device 100 liquid crystal display 100a Observer-side surface of liquid crystal display device

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H049 BA02 BA06 BA42 BB03 BB63                       BB65                 2H091 FA08X FA08Z FA11X FA11Z                       FA37X FA41Z FB02 FB13                       FD16 HA07 KA02 KA10 LA16                       MA10

Claims (9)

[Claims] 1. A liquid crystal cell having a pair of substrates and a liquid crystal layer provided between the pair of substrates, and a pair of polarizers disposed so as to face each other with the liquid crystal cell interposed therebetween. A retardation compensation element provided on at least one of the pair of polarizers and the liquid crystal cell, and an observer side of the polarizer provided on the observer side of the pair of polarizers. An antiglare layer provided, wherein the antiglare layer has an internal scattering layer and a scattering surface, and the haze value of the antiglare layer is 15 or more. 2. The phase difference compensating element has three main axes of the refractive index ellipsoid that are orthogonal to each other as a-axis, b-axis and c-axis, and when the main refractive indices are na, nb and nc,
a phase difference compensating element having a relationship of a = nc> nb, in which the a axis is substantially parallel to the layer surface of the liquid crystal layer and the b axis is inclined with respect to the layer normal of the liquid crystal layer. Yes, claim 1
The liquid crystal display device according to item 1. 3. The internal scattering layer includes a polymer matrix and particles dispersed in the polymer matrix, and the particles and the polymer matrix have different refractive indices from each other. The liquid crystal display device according to item 1. 4. The haze value of the anti-glare layer is 40.
It is above, The liquid crystal display device in any one of Claim 1 to 3. 5. The liquid crystal according to claim 1, wherein the anti-glare layer has a transmitted image sharpness value of 10 or more measured by an image clarity measuring device having an optical skewer width of 0.5 mm. Display device. 6. The retardation compensation element is arranged so that the b axis forms an angle within the range of 15 ° to 75 ° with respect to the layer normal of the liquid crystal layer. The liquid crystal display device according to claim 1. 7. When the thickness of the liquid crystal layer of the phase difference compensating element in the layer normal direction is d, (na−nb) × d is 8
The liquid crystal display device according to claim 1, wherein the liquid crystal display device is in a range of 0 nm to 250 nm. 8. The retardation compensating element comprises a support made of a cross-linked transparent organic polymer, and a discotic liquid crystal held by the support and having a tilt alignment or a hybrid alignment. 7. The liquid crystal display device according to any one of 7. 9. The liquid crystal display device according to claim 1, wherein the liquid crystal layer is a twist-aligned liquid crystal layer.