JP2004227006A - Liquid crystal display device - Google Patents

Abstract

An object of the present invention is to provide a liquid crystal display device having a uniform display quality without luminance unevenness caused by stress in a configuration in which a phase difference compensating element is bonded to a polarizing plate or in a configuration in which it is bonded to a liquid crystal panel.
A phase difference compensating element having a photoelastic coefficient of 10 × 10 ⁻¹³ cm ² / dyne or less is used. The liquid crystal layer includes a nematic liquid crystal material having negative anisotropy, and liquid crystal molecules of the nematic liquid crystal material are aligned substantially perpendicular to the surface of each substrate when no voltage is applied. The liquid crystal cell has a plurality of picture element regions each having two or more liquid crystal regions different from each other.
[Selection diagram] Fig. 4

Description

  The present invention relates to a computer monitor display and a liquid crystal display device that displays video images and the like, and more particularly to a liquid crystal display device having excellent viewing angle characteristics.

  As a method of wide viewing angle of the liquid crystal display device, there are a method of changing the alignment direction of the liquid crystal molecules in a plane substantially parallel to the substrate surface, and a method of changing the alignment direction of the liquid crystal molecules in a direction perpendicular to the substrate surface. In the mode, there is a method in which liquid crystal molecules are divided into regions having different alignment directions (azimuth directions) in a plane parallel to the substrate surface. A typical example of the former is an IPS (In-Plane-Switching) mode. As an example of the latter, (1) a liquid crystal region in which Np-type liquid crystal (nematic liquid crystal having a positive dielectric anisotropy) that is horizontally oriented with respect to the substrate surface when no voltage is applied is oriented in an axially symmetric manner. A wide viewing angle liquid crystal display mode provided for each element (Japanese Unexamined Patent Publication No. Hei 7-120728, Patent Document 1); (2) Nn-type liquid crystal that is oriented substantially perpendicular to the substrate surface when no voltage is applied (negative dielectric anisotropy) A wide viewing angle liquid crystal display mode in which a nematic liquid crystal having the following characteristics is divided into a plurality of regions having different directions of tilt when an electric field is applied (Japanese Patent Laid-Open No. 7-64089, Patent Document 2), and (3) AM-LCD '96. , P. 185 (1996) (Non-Patent Document 1) has proposed a wide viewing angle liquid crystal display mode in which an Np-type liquid crystal is divided into approximately four in a picture element and horizontally aligned. Further, in the latter method, a phase difference compensating element is required in principle in order to compensate the viewing angle in the direction of 45 ° with respect to the absorption axis of the polarizing element.

  In this specification, the retardation compensating element refers to a plate-like, sheet-like, or film-like optical element having birefringence. In addition, the polarizing element refers to an optical element that absorbs one of two linearly polarized lights orthogonal to each other and transmits the other. The absorption axis and the transmission axis (polarization axis) of the polarizing plate are orthogonal to each other.

  At present, polyvinyl alcohol (PVA) or polycarbonate (PC) is generally used as a resin material of a stretched film used for a retardation film. Characteristics required for the retardation film are roughly classified into optical characteristics and mechanical characteristics. The required optical characteristics include a small phase difference unevenness, a matching property of the birefringence of the liquid crystal layer with the wavelength dispersion property, high heat resistance and moisture resistance, no optical axis disturbance and optical defects such as foreign matter, and a high level. Transmittance, a small photoelastic coefficient, and light transmittance deterioration resistance performance due to ultraviolet rays. The required mechanical properties include high elastic modulus, high tensile strength, and high yield strength. Further, processability such as stretchability in the production process of the retardation film is also important. Among the above required characteristics, characteristics that are particularly important in practical use are small phase difference unevenness, matching characteristics of the birefringence of the liquid crystal layer with the wavelength dispersion characteristics, and small photoelastic coefficient.

Japanese Patent Application Laid-Open No. 6-3524 (Patent Document 3) discloses that substantially one crystalline copolymer composed of ethylene trifluoride ethylene (80 to 98% by weight) and vinylidene fluoride (2 to 20% by weight) is formed. A uniaxial optical retardation film oriented in a direction is disclosed.
JP-A-7-120728 JP-A-7-64089 JP-A-6-3524 AM-LCD '96, p. 185 (1996)

  However, the present inventor has found that the above-described conventional liquid crystal display device using a retardation plate has the following problems.

  A retardation plate disclosed in Japanese Patent Application Laid-Open No. 6-3524 discloses, for example, a liquid crystal layer in which each of a plurality of picture element regions includes two or more liquid crystal regions having different initial alignment states, or the alignment of liquid crystal molecules. The retardation condition required for improving the display quality of a liquid crystal display device including a liquid crystal layer having a liquid crystal region whose direction changes continuously or a large-screen (for example, 42-inch) liquid crystal display device cannot be satisfied. That is, even when applied to these liquid crystal display devices, there was a problem that a sufficient viewing angle compensation effect was not obtained, the viewing angle was narrow, and the color was yellow when observed from an oblique direction. In addition, it has been difficult to manufacture a retardation plate having a size applicable to a large-screen (for example, 42-inch) liquid crystal display device and having no color unevenness. Hereinafter, the problems found by the present inventors will be specifically described with reference to the drawings.

  In a large-sized display device, for example, a 42-inch liquid crystal display device, stress is generated by bonding a polarizing plate and a phase difference compensating element, bonding a polarizing plate with a phase difference compensating element to a liquid crystal cell, and a backlight. The applied heat causes stress to be applied to the phase difference compensation element. As a result, retardation due to the local stress occurs in the phase difference compensating element, and this state is fixed by the adhesive, and the transmittance under the polarizing plate crossed Nicols increases locally, resulting in uneven brightness. And the display quality is extremely impaired.

  FIG. 1 schematically shows locations where local transmittance increases (light leakage) in the black display state due to the above-described stress.

  FIG. 1 schematically shows a display surface 10 of a large-sized liquid crystal display device. Light leakage (type 1) due to stress caused by bonding a polarizing plate and a phase difference compensating element is often observed near the center of the four sides of the display surface. In addition, light leakage (type 2) caused by stress due to heat from the backlight occurs at four corners of the display surface. The degree of light leakage due to these stresses depends on the magnitude of the stress and the magnitude of the photoelastic coefficient of the material of the phase difference compensating element.

  In the above-described display mode in which the orientation of liquid crystal molecules in the pixel region is divided, the axis direction (polarization direction) that bisects the absorption axis of the upper polarizing plate and the absorption axis of the lower polarizing plate provided with the liquid crystal cell in between. There was a problem that the viewing angle characteristics at a direction of 45 ° with respect to the absorption axis of the plate were significantly worse than the viewing angle characteristics in the direction of the absorption axis (for example, the equal contrast contour of Comparative Example 1 described later). FIG. 14 showing the curve).

  Here, in order to explain the viewing angle characteristics of the liquid crystal display device, the arrangement of the polarizing plate in the liquid crystal display device and the definition of the viewing angle direction will be described with reference to FIGS. 2A and 2B.

  FIG. 2A schematically shows the configuration of a liquid crystal display device having a crossed Nicol polarizing plate arrangement. An absorption axis 22a of a polarizing plate (referred to as an upper polarizing plate) disposed on the viewer side of the liquid crystal cell 20 and an absorption axis 22b of a polarizing plate (referred to as a lower polarizing plate) disposed on the backlight side of the liquid crystal cell 20. Are arranged so as to be orthogonal to each other. As shown in FIG. 2B, the viewing angle direction (direction of the observer's line of sight) is the angle (viewing angle θ) from the normal 26 to the virtual plane 24 parallel to the display surface of the liquid crystal display device, and the absorption of the upper polarizing plate. The angle from the axis direction 28 (azimuth angle Ф: positive in the counterclockwise direction). By evaluating the contrast ratio with respect to θ-Φ, an equal contrast contour curve can be obtained regardless of the display mode. In this specification, as a rectangular coordinate system for defining the anisotropy of the optical characteristics of the liquid crystal display device, the direction of the normal 26 to the virtual plane 24 is defined as the z-axis, and Φ = 270 within the virtual plane 24. An xyz coordinate system is used in which the x direction is the x axis and the Φ = 0 direction is the y axis.

  Further, as shown in FIG. 3A, a commercially available polarizing plate 30 has a structure in which a polarizing layer 32 is sandwiched between support films 34 and 36. Since the polarizing layer 32 (for example, made of PVA) has low strength, it is supported by the support films 34 and 36 (for example, made of triacetyl cellulose: TAC). As shown in FIG. 3B, the absorption axis direction 32a of the polarizing layer 32 substantially coincides with the slow axis directions 34a and 36a of the support films 34 and 36.

  The present invention has been made in order to solve the above-described problems, and has a structure in which a phase difference compensating element and a polarizing plate are bonded to each other, and a structure in which the liquid crystal panel is bonded to the liquid crystal panel has uniform brightness without stress. It is an object to provide a liquid crystal display device having a high display quality.

A liquid crystal display device according to the present invention includes a liquid crystal cell having a pair of substrates and a liquid crystal layer sandwiched between the pair of substrates, a pair of polarizing elements sandwiching the liquid crystal cell, the pair of polarizing elements, and the liquid crystal cell. And a phase difference compensating element provided on at least one of the phase difference compensating elements, wherein the phase difference compensating element has a photoelastic coefficient of 10 × 10 ⁻¹³ cm ² / dyne or less. Achieved.

The phase compensator, x orthogonal to each other, respectively, y, and z-axis to the three refractive indices n _x, n _y, has a n _z, the main refraction of the said inner surface in a parallel plane of the liquid crystal cell rates and _{n x} and _{n y,} when a principal refractive index in the thickness direction of the liquid crystal cell and _{n z,} it is preferable to satisfy the relation of _{n z <n y <n x} .

  The liquid crystal cell has a plurality of picture element regions, and each of the plurality of picture element regions has at least two liquid crystal regions having different alignment states or a liquid crystal region in which the alignment direction of liquid crystal molecules changes continuously. The retardation compensation element has a retardation film, the retardation film has a slow axis in a plane parallel to the surface of the liquid crystal cell, and the pair of polarizing elements and the liquid crystal cell It is preferable that the phase difference compensating element is provided between the two and the slow axes in the plane parallel to the surface of the liquid crystal cell of the phase difference compensating element are orthogonal to each other.

  The phase difference compensating element is provided between the pair of polarizing elements and the liquid crystal cell, and each of the phase difference compensating elements has a slow axis in a plane parallel to the surface of the liquid crystal cell. It is preferable that the slow axis of each of the phase difference compensating elements is orthogonal to the absorption axis of the polarizing element provided on the same side of the one polarizing element with respect to the liquid crystal cell. .

  The liquid crystal layer may include a nematic liquid crystal material, and liquid crystal molecules of the nematic liquid crystal material may be oriented substantially perpendicular to the surfaces of the pair of substrates during black display.

  The liquid crystal layer includes a nematic liquid crystal material having a negative dielectric anisotropy, and liquid crystal molecules of the nematic liquid crystal material are substantially vertically aligned with respect to the surfaces of the pair of substrates when no voltage is applied. It may be.

When the thickness of the d _f of the birefringence of the liquid crystal molecules of the liquid crystal layer [Delta] n, the thickness of d _LC of the average of the liquid crystal _layer, and the retardation compensation element, 0.11 <{d f _· ( and _{n x -n z)} / (} d LC · Δn) <0.75 and _{0 <{d f · (n} x -n y)} / (d LC · Δn) satisfying <0.26 configuration Is preferred.

  Each of the pair of polarizing elements may be a polarizing layer formed on a support film, and the support film may function as the retardation compensating element.

  The phase difference compensating element may be configured to include a liquid crystalline polymer.

  The liquid crystal cell has a plurality of picture element regions, and each of the plurality of picture element regions includes two or more liquid crystal regions having different initial alignment states or a liquid crystal region in which the alignment direction of liquid crystal molecules continuously changes. The retardation compensating element has a plurality of laminated retardation films, each of the retardation films has a slow axis in a plane parallel to the surface of the liquid crystal cell; Between the polarizing element and the liquid crystal cell, each having the phase difference compensating element, and having a structure in which the slow axes in a plane parallel to the surface of the liquid crystal cell of the phase difference compensating element are orthogonal to each other. Is also good.

  The retardation film may have a laminated structure in which two or more uniaxial films having retardation in the plane and in the normal direction are bonded together.

  The retardation film may have a structure in which a refractive index anisotropic material is laminated on a support substrate.

  Hereinafter, the operation of the present invention will be described.

By using a phase difference compensating element having a photoelastic coefficient of 10 × 10 ⁻¹³ cm ² / dyne or less, a lamination structure with a polarizing plate or an integrated product of a polarizing plate and a phase difference compensating element is stuck on a liquid crystal cell surface. In the combined configuration, it is possible to suppress the occurrence of unevenness in the degree of polarization, so that uniform display quality can be obtained. The phase difference compensating element of the present invention preferably has a non-zero birefringence and an average refractive index in the range of 1.4 to 1.7.

X respectively orthogonal to each other of the phase difference compensating element, y, and a refractive indices _n x a z-axis direction in _{3, n} y, _{n z is,} by satisfying _{n z <n y <n x} , a polarizing plate absorption axis , The viewing angle dependency in the 45 ° direction can be improved.

  In order to improve the azimuth angle dependence of the viewing angle characteristics, it is effective to reduce the refractive index anisotropy of the liquid crystal molecules of the liquid crystal material in the minor axis direction. By providing the above liquid crystal region, the effect can be obtained. Furthermore, the liquid crystal alignment state changes continuously within one picture element region (axially symmetric or radial alignment), thereby minimizing the refractive index anisotropy in the short axis direction of the liquid crystal molecules of the liquid crystal material. The effect to be obtained is obtained. Therefore, it is possible to maximize the azimuth angle dependency of the viewing angle characteristics. The retardation compensating element is preferably composed of one retardation film in terms of cost and manufacturing process, but may be composed of a plurality of retardation films.

  Further, when one phase difference compensating element is disposed between each of the pair of polarizing plates and the liquid crystal cell, the slow axes of the pair of phase difference compensating elements are made orthogonal to each other so that Since no in-plane phase difference occurs between the cell and the cell, a decrease in the contrast ratio can be suppressed. By making the absorption axis of the polarizing plate orthogonal to the slow axis of the phase difference compensating element, a viewing angle compensation effect in the direction of 45 ° from the absorption axis of the polarizing plate can be more effectively obtained.

  When the liquid crystal molecules are vertically oriented with respect to the substrate, the viewing angle is tilted at 45 ° to the absorption axis of the polarizing plate because the refractive index anisotropy of the liquid crystal layer in the liquid crystal cell plane is small. In this case, light leakage at the black level can be suppressed, and a decrease in contrast can be prevented, so that further compensation for the viewing angle can be achieved. This effect is remarkable in a normally black mode display device using an Nn liquid crystal material having negative dielectric anisotropy.

Further, specifically, when the birefringence of the liquid crystal molecules of the liquid crystal layer [Delta] n, the thickness d _LC of the average liquid crystal _layer, the thickness of the retardation compensation element and d _f, 0.11 <{d satisfies _{f · (n x -n z)} } / (d LC · Δn) <0.75 and _{0 <{d f · (n} x -n y)} / (d LC · Δn) <0.26 In the configuration, a remarkable effect is obtained.

  The support film of the polarizing plate has a retardation in the film plane and in the normal direction, and in consideration of the retardation, the retardation of the phase difference compensating element to be further added is designed so that the viewing angle compensation effect is improved. The maximum optimal retardation is obtained. In the manufacturing process of the polarizing plate, the phase difference compensating element can be employed as a support film of the polarizing plate. Therefore, it is advantageous in terms of cost and in the process of attaching to a liquid crystal panel.

  Since liquid crystalline polymers have molecules with optical anisotropy aligned on the alignment layer of the substrate (or substrate), they can be easily applied to a substrate such as a support substrate instead of stretching the film. A desired retardation can be obtained, and there is a possibility of cost reduction. Further, by controlling the orientation of the liquid crystalline polymer, films having various refractive index anisotropies can be formed.

According to the present invention, in a direct-view type ultra-large liquid crystal display device such as a 42-inch type, a material having a photoelastic coefficient of 10 × 10 ⁻¹³ cm ² / dyne or less is used as a phase difference compensating element, so that it is bonded to a polarizing plate. In a configuration in which the polarizing plate is bonded to a liquid crystal panel, the transmittance under a polarizing plate crossed Nicols can be suppressed to 0.04% or less, and the degree of polarization can be 99.9% or more. Since the luminance distribution of the display can be set to satisfy the condition of Lmax / Lavage <2, uniform display quality can be obtained without unevenness of the degree of polarization.

  Furthermore, the deterioration of the viewing angle characteristic in the direction of 45 ° with respect to the absorption axis of the polarizing plate is eliminated, and the liquid crystal molecules are vertically aligned during black display or when no voltage is applied. In a configuration having a liquid crystal region having a different alignment region or more in a division or an axially symmetric alignment in which the alignment is continuously changed, the slow axis thereof is made orthogonal to the absorption axis of the polarizing plate by using a biaxial phase difference compensating element. Thus, it is possible to provide a high-contrast liquid crystal display device having excellent viewing angle characteristics, in which the viewing angle can be significantly expanded and the characteristics are almost isotropic in all directions.

  INDUSTRIAL APPLICABILITY The liquid crystal display device of the present invention is suitably used for a direct-view type flat display such as a personal computer, a word processor, an amusement device, and a television device, a display plate using a shutter effect, a window, and a wall.

  Hereinafter, embodiments of the present invention will be described. First, the principle of the present invention will be described.

  FIG. 4 is an exploded perspective view schematically showing the configuration of the liquid crystal display device 100 of the present invention. The liquid crystal display device 100 of the present invention includes a liquid crystal cell 40, polarizing plates 42 and 44 as a pair of polarizing elements sandwiching the liquid crystal cell 40, and a position provided between the liquid crystal cell 40 and the polarizing plates 42 and 44. It has phase difference compensating elements 46 and 48. One of the phase difference compensating elements 46 and 48 may be omitted. The polarizing plate 42 and the phase difference compensating element 46 arranged on the viewer side of the liquid crystal cell 40 are called an upper polarizing plate and an upper phase difference compensating element, respectively. The polarizing plate 44 and the phase difference compensating element 48 disposed on the (illustrated) side are called a lower polarizing plate and a lower phase difference compensating element, respectively.

In this specification, the orthogonal coordinate system shown in FIG. 5A is used to define the refractive index anisotropy of the phase difference compensating elements (for example, the phase difference compensating elements 46 and 48 shown in FIG. 4). The z axis is taken in a direction perpendicular to the surfaces of the phase difference compensating elements 46 and 48, and of the x and y axes in a plane parallel to the surfaces of the phase difference compensating elements 46 and 48, the slow axis of the phase difference compensating element is Let the direction be the x-axis. Three principal refractive indices of the index ellipsoid of the phase difference compensating element 46 and 48 _{n x,} n y, When _{n z,} satisfying the relation of _{n x> n y> n z} .

  As shown in FIGS. 4 and 5B, the absorption axis 42a of the upper polarizing plate 42 and the absorption axis 44a of the lower polarizing plate 44 are orthogonal to each other, and the slow axis 46a of the upper phase difference compensating element 46 and the lower phase difference compensating element 48 Are also orthogonal to each other. The absorption axis 42a of the upper polarizing plate 42 and the slow axis 48a of the lower phase difference compensating element 48, and the absorption axis 44a of the lower polarizing plate 44 and the slow axis 46a of the upper phase difference compensating element 46 match.

  Further, by providing an anti-glare anti-glare layer coated with an anti-reflection film (AR coat) or a hard coat scattering layer on the surfaces of the polarizing plates 42 and 44, the effect of further improving the viewing angle characteristics in the direction of 45 ° with respect to the absorption axis direction is provided. Is demonstrated.

  A description will be given of a reduction in light leakage that occurs when stress is applied to the phase difference compensating elements 46 and 48.

  When a stress such as a compressive force, a tensile force, or heat is applied to a substance, specific gravity changes, coordination or orientation occurs in atoms or molecules, and anisotropy occurs in the refractive index. An isotropic substance having a zero birefringence has a non-zero birefringence due to stress, and an optically anisotropic substance having a non-zero birefringence changes the birefringence due to stress. This is the so-called stress birefringence. The birefringence index per unit stress, that is, the value obtained by dividing the birefringence index (or change in birefringence index) generated when a stress is applied to a material by the stress is called a photoelastic coefficient. The photoelastic coefficient is obtained by measuring the stress birefringence generated by changing the stress, plotting the stress birefringence generated with respect to the stress, and calculating the slope of the straight line.

  FIG. 6A shows the photoelastic coefficient of the phase difference compensating element, the amount of light leakage (transmittance) under a polarizing plate crossed Nicols when a tensile stress is applied in a configuration in which the phase difference compensating element is bonded to a 42-type glass plate, and Shows the relationship. As is clear from FIG. 6A, the light leakage amount increases almost linearly with an increase in the photoelastic modulus.

  The transmittance was measured using the optical system shown in FIG. 6B. The polarizing plate 42 and the phase compensating element 46 (or the polarizing plate 44 and the phase difference compensating element 48) in FIG. 4 are attached to a glass plate 62 (considered as a liquid crystal cell) with a predetermined adhesive used in an actual manufacturing process. Match. To this, light is irradiated from a backlight 66, and a polarizing plate 44 or 42 arranged so as to form a cross Nicol with the polarizing plate 42 or 44 attached to the phase difference compensating element 46 or 48 to be measured. The amount of light passing therethrough was measured and calculated using a luminance meter 68 (for example, BM5A: manufactured by TOPCON).

  FIG. 6C shows a result obtained by determining the relationship between the transmittance and the degree of polarization under crossed Nicols from the relationship of the following equation.

Degree of polarization (%) = {(P _// −P⊥) / (P _// + P⊥)} · 100
Here, P _// : transmittance under parallel Nicols (43%) with air as 100%, and P⊥: transmittance under cross Nicols.

  Since the liquid crystal display is a non-light-emitting type, it is required that the display is bright, high-contrast, and easy to see. Therefore, a polarizing plate is required to be bright and have high polarization. The polarization performance of the polarizing plate (WA Shucliff; polarized light and its application, Kyoritsu Shuppan, 9 (1965)) is a theoretical value, and the maximum value is a transmittance of a single substance of 50% and a degree of polarization of 100%. The closer to the theoretical value, the easier to see the liquid crystal display. However, a polarizing plate having a degree of polarization of 99.9% alone has a very general specification commercially available from a manufacturer. Therefore, the target value of the degree of polarization when the phase difference compensating element of the present invention is added to the polarizing plate is 99.9%. However, it is preferable that the degree of polarization be 99.9% or more, since the display becomes easier to see (the contrast ratio is higher).

  In a general high-contrast liquid crystal display device, in order to obtain a sufficient polarization degree characteristic of the polarizing plate at the time of crossed Nicols, for example, 99.9%, the relationship between the transmittance under the crossed Nicols and the degree of polarization in FIG. The amount of light leakage (transmittance) needs to be 0.04% or less for the entire phase difference compensating element.

  On the other hand, as shown in FIG. 7, the light leakage amount (Δ) due to the stress applied to the phase difference compensating element at the time of bonding can be roughly approximated by the following equation.

Δ = cd | σx−σy |
Here, c: photoelastic coefficient, d: thickness of the phase difference compensating element, σx: stress vector in the x-axis direction, σy: stress vector in the y-axis direction.
Accordingly, it can be seen that the light leakage amount (display quality) when the polarizing plate and the phase difference compensating element are provided in the liquid crystal cell is determined by the photoelastic coefficient and the magnitude of the stress of the phase difference compensating element. Further, assuming that the stress generated at the time of bonding or heating is substantially constant irrespective of the material, the light leakage amount (transmittance) under the polarizing plate crossed Nicols of the phase difference compensating element is set to 0.04% or less as described above. It can be seen that, in order to achieve this, the photoelastic coefficient of the phase difference compensating element needs to be 10 × 10 ⁻¹³ cm ² / dyne or less.

The materials used for the polarizing plate and the phase difference compensating element having a photoelastic coefficient of 10 × 10 ⁻¹³ cm ² / dyne or less are liquid crystalline polymer (discotic type, etc.), ARTON (norbornene resin), TAC (triacetyl cellulose). And the like. As a method of manufacturing the retardation compensating element, a laminated structure of a plurality of retardation films may be used in order to obtain a film stretching technique and a desired retardation. Furthermore, a refractive index anisotropic material such as a liquid crystalline polymer is applied to the support substrate so as to have a negative retardation in the normal direction of the film, and another retardation film is adhered to the material application surface to obtain a desired retardation. A phase difference compensating element can be obtained. At this time, TAC is preferably used as a material for the support substrate. Further, the support substrate has a function of a positive uniaxial retardation compensating element, and a retardation film having a negative birefringence using a liquid crystalline polymer is laminated to obtain a retardation compensating element having a desired retardation. be able to.

  Further, as an adhesive for bonding a polarizing plate and a phase difference compensating element, and for bonding an integrated product thereof to a liquid crystal panel surface, a material having high stress relaxation property and heat relaxation property (physical properties include adhesive strength). It is preferable to use a material having a relatively low thickness) or a layer thickness.

  Further, the present invention can be suitably applied to a display mode in which black is displayed in a state where liquid crystal molecules are vertically aligned with the substrate. That is, the director of the liquid crystal molecules during black display is in a direction perpendicular to the substrate regardless of the orientation division method, and the function of the present invention to suppress the increase in the transmittance of the black level in the black display state is the present invention. Is a phase difference compensating element. More strictly, as shown in FIG. 8, a state in which liquid crystal molecules are aligned substantially perpendicular to the surface of the substrate when no voltage is applied by using an Nn-type liquid crystal, and as shown in FIG. The viewing angle compensation effect is large in a state where the liquid crystal molecules are aligned vertically to the substrate when a saturation voltage is applied using the liquid crystal. However, in a liquid crystal display mode in which the value of the refractive index anisotropy in a plane substantially parallel to the liquid crystal cell surface is smaller in black display than in white display, a liquid crystal cell using any display mode is used. Is also good.

(Embodiment)
In embodiments of the present invention, as shown in FIG. 4, the average in-plane refractive index (n _{x, n y)} is larger than the refractive index in the thickness direction (n _z), and refracted plane By inserting phase difference compensating elements 46 and 48 having ratio anisotropy between the liquid crystal cell 40 and the polarizing plates 42 and 44, the viewing angle is shifted from the polarizing plate absorption axes 42a and 44a. The deterioration of the characteristics is eliminated. The material of the polarizing plate and the phase difference compensator has a photoelastic coefficient of 10 × 10 ⁻¹³ cm ² / dyne or less. It is preferable that the phase difference compensating element has a non-zero birefringence and an average refractive index in a range of 1.4 to 1.7.

  As the polarizing plate used in the present embodiment and the examples described below, a support film of high dimensionally stable TAC commercially available from Sanritsu Co., Ltd., Nitto Denko Corporation or Sumitomo Chemical Co., Ltd. was used. A polarizing plate was used. However, as described above, since the TAC film has retardation, in the present invention, the retardation of the polarizing plate is considered in the design of the retardation of the phase difference compensating element.

Conditions of the refractive index of the phase compensation element used in the present invention, as described above, a condition of _{n z <n y <n x} . The above-described retardation compensating element formed using a laminated retardation plate (or retardation film) or a retardation film having a negative birefringence made of a polymer liquid crystal coating film also has a retardation compensation. It suffices that the above conditions are satisfied for the entire device.

FIG. 9 shows that the birefringence of the liquid crystal material Δn = 0.073, the thickness of the liquid crystal layer (cell thickness): 6 μm (that is, the retardation d _LC · Δn = 438 nm of the liquid crystal cell), and the orientation of the liquid crystal molecules is as axisymmetric alignment state in each liquid crystal region, the retardation _d f _· a phase compensator _{(n x = n y> n} z) and _{(n x -n z) (d} f is the thickness of the retardation compensation element) 0 nm Φ = 45 °, 135 °, 225 °, 315 ° (the absorption axis of the lower polarizing plate on the light source side is Φ = 0 °) and Φ = 0 °, 90 °, 180 °, 270 FIG. 6 shows the results of measuring the contrast ratio at θ (direction parallel or perpendicular to the polarization axes of the upper and lower polarizers) and θ = 40 °.

  The viewing angle characteristics of transmittance when the liquid crystal display device of the present embodiment is displayed in black at a drive voltage Voff = 2.2 V using an optical property evaluation device LCD5000 manufactured by Otsuka Electronics Co., Ltd. The viewing angle characteristics of the transmittance when white display was performed at a drive voltage of Von = 7 V were measured, and the transmittance during white display was divided by the transmittance of black display to obtain the viewing angle characteristics of contrast.

As shown in FIG. 9, Φ = 0 °, 90 °, 180 °, the contrast ratio of 270 ° _was almost regardless of the value of _{d f · (n x -n z} ) constant. On the other hand, Φ = 45 °, 135 ° , 225 °, 315 ° contrast ratio _increases as the value of _{d f · (n x -n z} ) increases from _{0, d f · (n x} -n z ) = Maximum at 146 nm.

However, the actual the refractive index of the phase difference compensating element in a plane to obtain an n _{x =} n _y becomes retardation compensation element difficult. _Thus, with reference to conditions of _{n x =} n y> n _z More actual _element, and _{n z <n y <n x} , by using the retardation compensation element of the desired retardation, Φ = 45 ° (polarization The maximum value of the contrast ratio in the direction in which the absorption axis orthogonal to the plate is bisected) can be further increased. retardation compensation element satisfy the relation: _n z _<n y _{<n x} is, for example, a small photoelastic coefficient, a process such as coating the refractive anisotropy is small material on a molecular minor axis direction of the polymer liquid crystal materials , A desired retardation can be obtained. Alternatively, a film (for example, TAC) may be formed from a material having a small photoelastic coefficient, and the film may be stretched or formed by a composite technique in which the film is combined with a coating film of a polymer liquid crystal.

Figure 10A is a refractive index of the conditions of the retardation compensation element as _{n z <n y <n x} , while maintaining _{d f · (n x -n z} ) = 12nm, d f · (n x -n z) Is changed from 0 nm to 280 nm, and the results of measuring the contrast ratio at Φ = 45 ° and = 90 ° and θ = 40 °. Contrast ratio [Phi = 90 ° was constant regardless of the value of _{· d f (n x -n z} ). On the other hand, the contrast ratio of [Phi = 45 _°, the value of _{d f · (n x -n z} ) is, increases as increases from 0 _nm, when _{d f · (n x -n z} ) = 142nm, the maximum value Got. That is, only by the _0nm retardation compensation element from FIG. _{10A <d f · (n x} -n z) <280nm, when the normal direction of the retardation 50nm of TAC film of a polarizer to consider the phase difference compensating element, 50nm <d in _{f · (n x -n z)} < range of 330 nm, with respect to the absorption axis direction of the polarizing plate, there is the effect of improving the 45 ° direction contrast ratio.

The retardation value of the phase difference compensating element described above _{{d f · (n x -n} z)} is, _{d LC} · Δn value of the liquid crystal cell to be compensated (cell thickness _{d LC} of the liquid crystal of Δn = _(| n e -n _o When expressed as a relative value to the product d _LC · Δn = 438 nm with |), as shown in FIG. 10B, the range in which the viewing angle compensation effect on the retardation (d _LC · Δn) of the liquid crystal layer can be expected is as follows. _{0.11 <{d f · (n} x -n z)} / (d LC · Δn) < 0.75.

Also, the retardation _d f · plane direction _(n x -n _y) is the larger than 12nm are expected to be obtained more viewing angle compensation effect. As shown in Example 2 described later, a more preferable range of the in-plane retardation is 47 nm to 85 nm. When the viewing angle is tilted from the normal direction of the display surface, the liquid crystal molecules aligned perpendicular to the substrate appear to tilt from the normal direction of the substrate by an angle corresponding to the tilt angle of the viewing angle. Therefore, retardation occurs in a virtual plane including the viewing angle direction. As described above, by using the phase difference compensating element having in-plane retardation, it is possible to compensate for the retardation that occurs when the viewing angle is reduced.

  In the present embodiment, the case where the phase difference compensating elements are arranged on both sides of the liquid crystal cell is exemplified. However, when the retardation values are substantially doubled when one of them is arranged on one side, the viewing angle compensating effect can be obtained.

  As shown in FIGS. 4 and 5B, in the present embodiment, the slow axes 46a and 48a of the phase difference compensating elements 46 and 48 arranged above and below the liquid crystal cell are orthogonal to each other. The reason is to avoid a decrease in the contrast ratio when the liquid crystal display device 100 is viewed from the front (normal direction of the display surface).

  If the slow axes 46a and 48a of the two phase difference compensating elements 46 and 48 are not orthogonal to each other, an in-plane phase difference occurs in the entire phase difference compensating element, so that a good black display cannot be obtained and the contrast is low. The ratio has dropped. In the present embodiment, since the display mode of the axially symmetric alignment in which the alignment of the liquid crystal molecules is continuously changed is used, the visual field in the direction shifted by 45 ° from the absorption axes 42a and 44a of the polarizing plates 42 and 44 is used. By improving the angular characteristics, it is possible to obtain isotropic viewing angle characteristics in all directions. Similarly, in one picture element, even when the liquid crystal orientation state is divided into two or more, a viewing angle characteristic in a direction shifted by 45 ° from the absorption axis of the polarizing plate can be improved. In the liquid crystal display mode, the liquid crystal has two or more different alignment regions or the liquid crystal alignment is continuously changed, and the liquid crystal is aligned in an axially symmetric manner. Thus, an increase in the transmittance of the black level is suppressed, and an improvement in the contrast ratio, that is, a viewing angle compensation effect is obtained.

As the photoelastic coefficient of the phase difference compensating element is smaller than 10 × 10 ⁻¹³ cm ² / dyne, unevenness does not occur at the time of bonding with a polarizing plate or a liquid crystal cell, light leakage is suppressed, and uniform display quality is achieved. Can be improved. In particular, in order to realize high-quality display, the photoelastic coefficient of the phase difference compensating element is more preferably 5 × 10 ⁻¹³ cm ² / dyne or less.

  The retardation compensating elements can be manufactured by a film stretching technique, and can be formed in a laminated structure to obtain a desired retardation. Further, for example, a discotic liquid crystalline polymer is applied to a supporting substrate, and the coated surface is laminated with another supporting substrate or a polarizing plate (a polarizing plate is used as a supporting substrate). The use of a positive uniaxial retardation element having a retardation in the film plane as the supporting substrate, or changing the alignment state of the liquid crystalline polymer in the layer thickness direction, An axial retardation element can be manufactured.

  The driving method of the liquid crystal display device of the present invention can be applied to any driving method such as passive matrix driving, active matrix driving using thin film transistors and the like, and plasma address driving (PALC) using plasma discharge.

(Example 1)
With reference to FIG. 11A, a method for manufacturing the liquid crystal display device 200 of the present embodiment will be described. On the substrate 210 having a transparent electrode (ITO: 100 nm) formed on the surface, a convex portion 212 having a height of about 3 μm was formed outside the pixel region using photosensitive polyimide. Further, a convex portion (not shown) having a width smaller than the convex portion 212 and having a height of about 3 μm was formed on some of the convex portions 212 using photosensitive polyimide. The sum of the height of the protrusion 212 and the height of the protrusion formed on the protrusion 212 determines the cell thickness.

  The size of the area surrounded by the convex portion 212, that is, the size of the picture element area was 100 μm × 100 μm. On top of this, JALS204 (Japanese synthetic rubber) was spin-coated to form a vertical alignment layer 214a. Further, a vertical alignment layer 214b was formed on the transparent electrode (not shown) of the other substrate 220 using the same material. The two were bonded together to complete a liquid crystal cell.

In the manufactured liquid crystal cell, a twist angle specific to the liquid crystal material is set so that an Nn-type liquid crystal material (Δε = −4.0, Δn = 0.073, 90 ° twist at a cell gap of 6 μm) (that is, d _LC · Δn = 438 nm)), and a voltage of 7 V was applied. Immediately after the application of the voltage, in an initial state, there is a state in which a plurality of orientation axes having an axially symmetric orientation exist. When the voltage application state was further continued, one axially symmetric alignment region (monodomain) was formed for each picture element region, as shown in FIG. 11B. FIGS. 11C and 11D show the results of observing this picture element region under crossed Nicols. When no voltage is applied, a good black display is obtained as shown in FIG. 11C, and when a voltage is applied, an extinction pattern as shown in FIG. 11D is observed, and the orientation of the liquid crystal molecules changes continuously in the picture element region. Axisymmetric orientation.

Three-dimensional refractive indexes of the TAC used as both sides polarizing layer supporting film of the polarizing plate on the 42-inch liquid crystal cell of this example _{n x = 1.4952, n y =} 1.4951, with n z = 1.4964, thickness is is 80 [mu] m, the retardation was almost _{d f · (n x -n y} ) = 5nm, d f · (n x -n z) = 50nm. Further, each of the three-dimensional refractive indexes of the retardation compensation element _n x ₌ 1.50058 of the present invention, n _{y =} 1.50043, with n z = 1.49881, and the thickness was 80 [mu] m. Thus, _{retardation, d f · (n x -n} y) = 12nm, d f · (n x -n z) = a 142 nm, were arranged as shown in FIG. Since the absorption axis of the polarizing plate and the slow axis of the phase difference compensating element have an orthogonal relationship, the slow axis of the TAC of the polarizing plate support film and the slow axis of the phase difference compensating element also have an orthogonal relationship.

  The viewing angle characteristics of the transmittance when the liquid crystal display device 200 of this example was displayed in black at a drive voltage Voff = 2.2 V using an optical property evaluation device LCD5000 manufactured by Otsuka Electronics Co., Ltd. were measured. Next, the viewing angle characteristics of the transmittance at the time of white display at the drive voltage Von = 7 V were measured, and the transmittance at the time of white display was divided by the transmittance of black display to obtain the viewing angle characteristics of the contrast ratio. . As a result, an equal contrast contour curve having a contrast ratio of 10 similar to that of FIG. 12 was obtained.

The material of the support film of the polarizing plate used in this example was TAC, the photoelastic coefficient was 5 × 10 ⁻¹³ cm ² / dyne, and the photoelastic coefficient of the phase difference compensating element was 5 × 10 ^−13. cm ² / dyne. The phase difference compensating element was produced by coating a discotic liquid crystal polymer on a supporting substrate made of TAC with a controlled thickness so as to obtain a desired retardation, and then heating and cooling. The obtained retardation compensating element was bonded to and integrated with the above-mentioned polarizing plate using an adhesive. The integrated retardation compensator and polarizing plate were bonded to a liquid crystal cell using an adhesive.

  When the entire 42-inch liquid crystal display device performs black display and when the liquid crystal cell is heated to about 45 ° C. ± 5 ° C. by the backlight system, unevenness due to light leakage due to the polarizing plate and the phase difference compensating element is not observed. And excellent display quality.

  The degree of the luminance distribution on the display surface of the liquid crystal panel, which is not recognized by the observer as luminance unevenness, is based on the rule of luminance discrimination, that the ratio between the maximum luminance Lmax and the average luminance Laverage is Lmax / Laverage <2. It was confirmed from the luminance measurement or the transmittance measurement that it was sufficient. In addition, the apparatus as shown in FIG. 6B was used for the measurement. The phase difference compensation element used in the first embodiment has Lmax / Lavage = 1.5, and it is considered that no unevenness was recognized. At this time, the transmittance was 0.04% or less.

  It is desirable that d · Δn (retardation) of the liquid crystal layer be in the range of 300 to 500 nm. Further, the twist angle of the liquid crystal layer is desirably in the range of 45 ° to 110 °.

(Example 2)
In the second embodiment, a biaxial phase difference compensating element made of ARTON (norbornene resin), in which a viewing angle compensation effect is remarkably obtained instead of the liquid crystal polymer phase difference compensating element described in the first embodiment, is shown in FIG. An example in which the liquid crystal cell is used on both sides will be described.

  ARTON has a characteristic that the wavelength dispersion characteristic is flat in the wavelength region of visible light. In general, it is preferable that the retardation film has smaller and flat wavelength dispersion characteristics so that the viewing angle compensation effect at each of the RGB wavelengths becomes more equivalent.

The photoelastic coefficient of the phase difference compensating element manufactured by the biaxial stretching method of ARTON was 4 × 10 ⁻¹³ cm ² / dyne. When the entire 42-inch liquid crystal display device performs black display and when the panel is heated to about 45 ° C. ± 5 ° C. by the backlight system, unevenness due to light leakage due to the polarizing plate and the phase difference compensating element is not observed. Excellent display quality. The phase difference compensating element used in Example 2 had Lmax / Lavage = 1.4, and no unevenness was recognized. Therefore, from Examples 1 and 2, it was shown that when the optical elastic coefficient of the phase difference compensating element was smaller than 5 × 10 ⁻¹³ cm ² / dyne, unevenness was more unlikely to occur.

Table 1 summarizes the viewing angle characteristics and the results of visual check for visual appearance at a contrast ratio CR = 20. Polarizer retardation _{d f · (n x -n y} ) of the absorption phase viewing angle compensation effect can be obtained in the 45 ° direction with respect to the axis compensating element plane is 0nm~116nm more preferably 47Nm～85nm, the normal direction · retardation _d f _(n x -n _z) is 122Nm～208nm, more preferably could be obtained when 147Nm～198nm, a good viewing angle characteristic over all directions.

And _{d LC} · [Delta] n values (cell thickness d _LC of the liquid crystal cell retardation value of the retardation compensation element _{{d f · (n x -n} z)} is to be compensated, the liquid crystal used Δn _(| n e _-n o | ) expressed as a relative value to the product i.e. _{d LC} · _Δn = _438nm) with, it must be considered in the normal direction of the retardation 50nm of TAC film of the polarizing plate support film. Further, it is not necessary to consider the in-plane of the film because the retardation value is as small as 5 nm. Retardation of _n x -n _y-direction is in the film plane is _{0 <{d f · (n} x -n y)} / (d LC · Δn) <0.26, n z the direction of the retardation is a normal direction 0.39 _<when satisfying _{{d f · (n x -n} z)} / (d LC · Δn) <0.59, improved viewing angle compensation effect of the 45 ° direction with respect to the absorption axis of the polarizing plate I do. Further preferred conditions are isocontrast contour curve becomes _{isotropic, 0.1 <{d f · (} n x -n y)} / (d LC · Δn) <0.2,0.44 <{( _{n x -n z) · d f} } / (d LC · Δn) < 0.57.

(Example 3)
The 42-type liquid crystal cell of the first embodiment is provided with the phase difference compensating elements of the first and second embodiments and the phase difference compensating element having twice the retardation between the upper and lower polarizers 42 and 44 and the liquid crystal cell in FIG. Only one of them was arranged. FIG. 13 is a diagram showing an iso-contrast contour curve of the liquid crystal display device with a contrast ratio of 10 measured in the same manner as in the first embodiment. The viewing angle characteristics in the polarizing plate absorption axis direction (Φ = 0 °, 90 °, 180 ° and 270 °) are almost the same and good. However, in a 45 ° direction (Φ = 45 °, 135 °, 225 °, 315 °) with respect to the absorption axis of the polarizing plate, the viewing angle characteristics are slightly inferior to those of the first embodiment (FIG. 12). Occasionally, unevenness in light leakage due to the polarizing plate was not observed. Arranging the phase difference compensating element in one place is advantageous in cost and process.

(Example 4)
In the fourth embodiment, a biaxial retardation compensating element having a structure in which a uniaxial retardation film (TAC) 75 is added to ARTON (norbornene resin) 74 as shown in FIG. 15B, and each optical axis is set as shown in FIG. 15A An example in which the liquid crystal cell is used on both sides will be described. With respect to the iso-contour characteristics at a contrast ratio of 20, the same characteristics as in Example 2 were obtained. In addition, it was confirmed that the change in the tint of the black level when the viewing angle in the 45-degree direction was reduced was smaller. Further, no unevenness in light leakage due to the polarizing plate was observed during black display. Table 2 below shows the viewing angle characteristics and the results of the visual confirmation of Example 4.

(Comparative Example 1)
In Comparative Example 1, as in Example 1, a device having the same configuration as the liquid crystal display device shown in FIG. 4 was used. However, in Comparative Example 1, no phase difference compensating element was used.

  FIG. 14 is a diagram showing an equal-contrast contour curve with a contrast ratio of 10 obtained by measuring the liquid crystal display device in the same manner as in the first embodiment. The viewing angle characteristics in the polarizing plate absorption axis direction (Φ = 0 °, 90 °, 180 ° and 270 °) are almost the same and good. However, in the 45 ° direction (Φ = 45 °, 135 °, 225 °, 315 °) with respect to the absorption axis of the polarizing plate, the viewing angle characteristics are significantly inferior. Not observed. Therefore, since light leakage does not occur only with the polarizing plate, when the polarizing plate and the phase difference compensating element are bonded, unevenness occurs due to the configuration in which the phase difference compensating element and the liquid crystal cell are bonded. At this time, the luminance unevenness was Lmax / Lavage <1.2, and no unevenness was recognized.

(Comparative Example 2)
42-inch liquid crystal cell of Example _{1, d f · (n x} -n y) = 12nm, d f · (n x -n z) = at 142 nm, the photoelastic coefficient of 70~90 × ¹⁰ -13 cm ² / Dyne phase difference compensating elements 46 and 48 were provided. As a result of measuring the viewing angle characteristics of the liquid crystal display device, the isocontrast contour curve of the liquid crystal display device of Comparative Example 2 was the same as that of the liquid crystal display device of Example 1 (FIG. 12). The unevenness of light leakage due to the polarizing plate and the phase difference compensating element was observed. The luminance unevenness at this time is Lmax / Lavage ≧ 2, and it is considered that the unevenness was recognized.

It is a figure which shows typically the type of the light leakage caused by the stress in a liquid crystal display device, and its generation place. FIG. 4 is a diagram schematically illustrating an arrangement relationship of absorption axes of a polarizing plate in a liquid crystal display device. FIG. 3 is a diagram illustrating definitions of an azimuth angle and a viewing angle for evaluating a viewing angle characteristic of a liquid crystal display device. It is sectional drawing of a polarizing plate. FIG. 3 is a diagram illustrating an orthogonal coordinate system for defining optical characteristics of a polarizing plate. FIG. 1 is a schematic exploded perspective view of a liquid crystal display device according to an embodiment of the present invention. FIG. 3 is a diagram illustrating an orthogonal coordinate system for defining optical characteristics of a phase difference compensating element. FIG. 4 is a diagram illustrating an arrangement relationship between an absorption axis of a polarizing plate and a slow axis of a phase difference compensating element in a liquid crystal display device according to an embodiment of the present invention. 4 shows the relationship between the photoelastic coefficient of the phase difference compensating element and the amount of light leakage (transmittance) under crossed Nicols of the polarizing plate when a tensile stress is applied in a configuration in which the phase difference compensating element is bonded to a 42-type glass plate. It is a graph. It is a schematic diagram which shows the optical system for evaluating light leakage. It is a graph which shows the relationship between the transmittance of a crossed Nicols arrangement, and the degree of polarization. FIG. 4 is a schematic diagram for explaining a model stress applied to a phase difference compensation element and a mechanism of light leakage. FIG. 3 is a schematic diagram illustrating an alignment state of liquid crystal molecules in a black display state. Is a graph showing the relationship between the retardation _{d f · (n x -n z} ) and contrast ratio of the phase compensation element _{(n x = n y> n} z). It is a graph showing the relationship between the retardation _{d f · (n x -n z} ) and contrast ratio of the phase compensation element _{(n z <n y <n} x). A graph showing the relationship between the retardation _{d f · (n x -n z} ) and contrast ratio of the retardation compensation element, expressed in relative values for the retardation _{d LC} · [Delta] n of the liquid crystal layer _{(n z <n y <n} x) is there. FIG. 3 is a cross-sectional view schematically illustrating a state when no voltage is applied to the liquid crystal display device according to the embodiment of the present invention. FIG. 3 is a cross-sectional view schematically illustrating a state when a saturation voltage is applied to the liquid crystal display device according to the embodiment of the present invention. FIG. 4 is a cross-sectional view schematically showing a result of observing a picture element region of the liquid crystal display device according to an embodiment of the present invention when no voltage is applied under crossed Nicols. FIG. 6 is a cross-sectional view schematically showing a result of observing a picture element region under crossed Nicols when a saturation voltage is applied to the liquid crystal display device according to the embodiment of the present invention. 5 is an iso-contrast contour curve with a contrast ratio of 10 for a liquid crystal display device according to an embodiment of the present invention. 7 is an iso-contrast contour curve with a contrast ratio of 10 for a liquid crystal display according to another embodiment of the present invention. 7 is an iso-contrast contour curve with a contrast ratio of 10 of the liquid crystal display device of Comparative Example 1. FIG. 13 is a schematic exploded perspective view of a liquid crystal display device according to an embodiment of Example 4. FIG. 9 is a cross-sectional view of a retardation film and a polarizing plate used in Example 4.

Explanation of reference numerals

Reference Signs List 40 liquid crystal cell 42, 44 polarizing plate 42a, 44a absorption axis of polarizing plate 46, 48 phase difference compensation element 46a, 48a slow axis of phase difference compensation element 71 backlight 72 lower polarizing plate 73 absorption axis 74 ARTON
75 TAC
76 slow axis 77 liquid crystal cell 78 upper polarizing plate 79 retardation film 80 adhesive layer

Claims (9)

A liquid crystal cell having a pair of substrates and a liquid crystal layer sandwiched between the pair of substrates,
A pair of polarizing elements sandwiching the liquid crystal cell,
Having a phase difference compensating element provided on at least one of the pair of polarizing elements and the liquid crystal cell,
The phase difference compensating element has a photoelastic coefficient of 10 × 10 ⁻¹³ cm ² / dyne or less,
The liquid crystal layer includes a nematic liquid crystal material having a negative dielectric anisotropy, and liquid crystal molecules of the nematic liquid crystal material are aligned substantially perpendicular to the surfaces of the pair of substrates when no voltage is applied,
A liquid crystal display device, wherein the liquid crystal cell has a plurality of picture element regions, and each of the plurality of picture element regions has two or more different liquid crystal regions. The phase compensator, x orthogonal to each other, respectively, y, and z-axis to the three refractive indices n _x, n _y, has a n _z, the main refraction of the said inner surface in a parallel plane of the liquid crystal cell rates and _{n x} and _{n y,} when a principal refractive index in the thickness direction of the liquid crystal cell and _{n z,} satisfies the relationship of _{n z <n y <n x} , a liquid crystal display device according to claim 1. Each of the plurality of picture element regions has two or more liquid crystal regions having different initial alignment states or a liquid crystal region in which the alignment direction of liquid crystal molecules changes continuously,
The retardation compensation element has a retardation film, the retardation film has a slow axis in a plane parallel to the surface of the liquid crystal cell,
The phase difference compensating element is provided between the pair of polarizing elements and the liquid crystal cell, and the slow axes of the phase difference compensating element in a plane parallel to the surface of the liquid crystal cell are orthogonal to each other. The liquid crystal display device according to claim 1. Having the phase difference compensating element between the pair of polarizing elements and the liquid crystal cell,
Each of the phase difference compensating elements has a slow axis in a plane parallel to the surface of the liquid crystal cell, and each slow axis of the phase difference compensating element corresponds to the liquid crystal cell of the one polarizing element. The liquid crystal display device according to any one of claims 1 to 3, wherein the liquid crystal display device is orthogonal to an absorption axis of a polarizing element provided on the same side of the liquid crystal display. When the birefringence of the liquid crystal molecules of the liquid crystal layer [Delta] n, the thickness of the average of the liquid crystal layer d _LC, and the thickness of the retardation compensation element and d _{f,
0.11 <{d f · (n} x -n z)} / (d LC · Δn) <0.75, and _{0 <{d f · (n} x -n y)} / (d LC · Δn) <0.26
The liquid crystal display device according to any one of claims 1 to 4, which satisfies the following relationship.   6. The liquid crystal display device according to claim 1, wherein each of the pair of polarizing elements is a polarizing layer formed on a support film, and the support film functions as the retardation compensating element. .   The liquid crystal display device according to claim 1, wherein the phase difference compensating element includes a liquid crystalline polymer. 4. The liquid crystal display device according to claim 3, wherein the retardation film has a laminated structure in which two or more uniaxial films having retardation in a plane and in a normal direction are bonded. The liquid crystal display device according to claim 3, wherein the retardation film has a structure in which a refractive index anisotropic material is laminated on a support substrate.

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