JP2008020780A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which exhibits satisfactory color hue by using a polarizing plate having one sheet of optical compensation film without increasing a thickness of the polarizing plate in order to make the device low-cost. <P>SOLUTION: The liquid crystal display device is provided with: a liquid crystal cell which forms a multi-gap structure in which an interval between a pixel electrode and a counter electrode facing the pixel electrode is different every color corresponding to the pixel electrode; and a polarizing plate in which one sheet of optical compensation film having at least an optical anisotropic layer is disposed, whereby the liquid crystal display device expresses such an optical characteristic that both of retardation Re in the in-plane direction and retardation Rth in the thickness direction of the optical anisotropic layer are inversely dispersed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device including a bend alignment mode or vertical alignment mode liquid crystal cell.

  Conventionally, liquid crystal display devices have been applied to various fields by taking advantage of features such as light weight, thinness, and low power consumption.

  Currently, a twisted nematic (TN) type liquid crystal display device widely used in the market is configured by arranging liquid crystal molecules having optically positive refractive index anisotropy by twisting approximately 90 ° between a pair of substrates. The optical rotation of the light incident on the liquid crystal layer is adjusted by controlling the twisted arrangement. Although this TN liquid crystal display device can be manufactured relatively easily, its viewing angle is narrow and its response speed is slow, so that it is not particularly suitable for displaying moving images such as TV images.

  On the other hand, an OCB (Optically Compensatory Bend) type liquid crystal display device has attracted attention as a liquid crystal display device capable of improving the viewing angle and the response speed. In the OCB type liquid crystal display device, a liquid crystal layer having liquid crystal molecules capable of bend alignment is sandwiched between a pair of substrates. This OCB type liquid crystal display device has an improved response speed by an order of magnitude compared to the TN type liquid crystal display device, and can optically self-compensate for the influence of birefringence of light passing through the liquid crystal layer depending on the alignment state of the liquid crystal molecules. Therefore, there is an advantage that the viewing angle is wide.

  When displaying an image using such an OCB type liquid crystal display device, the birefringence is controlled and combined with a polarizing plate, for example, black is displayed by blocking light when a high voltage is applied, and light is displayed when a low voltage is applied. It is conceivable that white is displayed through the screen.

  However, when displaying black, the majority of liquid crystal molecules are aligned along the direction of the electric field by applying a high voltage (that is, aligned in the normal direction of the substrate), but the liquid crystal molecules near the substrate are aligned with the alignment film. The light is affected by the phase difference in a predetermined direction without being arranged in the normal direction due to the interaction. For this reason, when observed from the front direction of the screen (that is, the normal direction of the substrate), the transmittance during black display cannot be sufficiently reduced, leading to a decrease in contrast.

  Therefore, for example, it is known to combine the uniaxial retardation plate to compensate for the retardation of the liquid crystal layer during black display and to sufficiently reduce the transmittance. Further, as a technique for realizing black display with sufficiently low transmittance even when observing from an oblique direction of the screen or compensating for gradation characteristics, for example, as disclosed in Patent Document 1, a hybrid array optical is used. It is also known to combine a retardation plate having a negative optical anisotropic body.

  However, the configuration of the conventional OCB type liquid crystal display device has a problem that coloring occurs when the screen is observed from an oblique direction. This tint occurs at any wavelength of light, but it is recognized as bluish when the screen is observed from an oblique direction, especially in the direction perpendicular to the rubbing direction of the alignment film (liquid crystal alignment direction) when displaying black. There is a problem.

Moreover, when optical compensation is performed by a polarizing plate provided with one optical compensation film, the color is not good. This is because both the retardation Re in the plane direction and the retardation Rth in the thickness direction in the optically anisotropic layer constituting the optical compensation film are both forward-dispersed (wavelength that falls to the right toward the long wavelength side). This is due to being distributed.
Therefore, when optical compensation is performed using a polarizing plate provided with two or more optical compensation films, Re is inversely dispersed (wavelength dispersion that rises to the right toward the long wavelength side), and Rth is controlled to be forwardly dispersed. Can improve the color.
However, in such a configuration, by providing the polarizing plate with a plurality of optical compensation films, not only the thickness of the polarizing plate installed in the liquid crystal cell increases, but also costs increase. There has been a demand for the development of a liquid crystal display device exhibiting a good color with a polarizing plate provided.

By the way, in general, the in-plane direction retardation Re and the thickness direction retardation Rth of the film change as shown in FIG. 4 according to the distance between the electrodes of the liquid crystal cell.
Therefore, by appropriately changing the distance between the pixel electrodes corresponding to the red, blue, and green pixels in the liquid crystal cell, chromatic dispersion characteristics that have no other means depending on the film can be obtained with a single electrode distance. To inverse dispersion or vice versa.

Japanese Patent Laid-Open No. 10-197862

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a liquid crystal display device exhibiting a good color with a polarizing plate provided with one optical compensation film in order to reduce the cost without increasing the thickness of the polarizing plate. To do.

  The inventors pay attention to this characteristic, and change the Re and Rth characteristics of a single film by adding an additive or a stretching process, and changing the interval between pixel electrodes of a liquid crystal cell in which the film is incorporated. By adjusting appropriately, it came to provide the liquid crystal display device which exhibits a favorable color.

Means for solving the above-mentioned problems are as follows. That is,
<1> One substrate on which pixel electrodes are disposed corresponding to a plurality of color pixels, another substrate on which counter electrodes are disposed so as to face the pixel electrodes, the one substrate, and the other A liquid crystal cell constituted by a liquid crystal layer sandwiched between the substrate and
A polarizing film and one optical compensation film having an optically anisotropic layer, wherein the one substrate and the other substrate are arranged so that the optical compensation film faces the one substrate and the other substrate. A polarizing plate installed on each of the substrates, and a liquid crystal display device comprising:
In the liquid crystal cell, an interval between the pixel electrode and the counter electrode facing the pixel electrode is different for each color pixel corresponding to the pixel electrode,
In-plane retardations Re ₍₄₅₀₎ , Re ₍₅₅₀₎ , and Re ₍₆₃₀₎ for light having wavelengths of 450 nm, 550 nm, and 630 nm in the optically anisotropic layer, and retardation Rth ₍ thickness direction _{) 450)} , Rth ₍₅₅₀₎ , and Rth ₍₆₃₀₎ satisfy the following formulas (1) to (4).
Re ₍₄₅₀₎ / Re ₍₅₅₀₎ <1 ... Formula (1)
Re ₍₆₃₀₎ / Re ₍₅₅₀₎ > 1 ..... Formula (2)
Rth ₍₄₅₀₎ / Rth ₍₅₅₀₎ <1 Equation (3)
Rth ₍₆₃₀₎ / Rth ₍₅₅₀₎ > 1 formula (4)
In the above formulas (1) to (4), Re and Rth are defined as the refractive index in the slow axis direction (direction in which the refractive index becomes maximum) in the plane of the optically anisotropic layer is nx, and the optical The refractive index in the fast axis direction (direction in which the refractive index is minimum) in the plane of the anisotropic layer is ny, the refractive index in the thickness direction of the optical anisotropic layer is nz, and the optical anisotropic layer Is the value represented by Re = (nx−ny) × d, and Rth = {(nx + ny) / 2−nz} × d.
<2> The color pixel includes a red pixel, a green pixel, and a blue pixel, and a distance between a pixel electrode corresponding to the blue pixel and a counter electrode facing the pixel electrode corresponds to the red pixel; The liquid crystal display device according to <1>, wherein the distance between the counter electrode facing the pixel electrode and the distance between the pixel electrode corresponding to the green pixel and the counter electrode facing the pixel electrode is smaller.
<3> From <1> to <2 above, the interval between the pixel electrode corresponding to the green pixel and the counter electrode facing it is smaller than the interval between the pixel electrode corresponding to the red pixel and the counter electrode facing it. > A liquid crystal display device according to any one of the above.
<4> An interval between a pixel electrode corresponding to one color pixel and a counter electrode facing the pixel electrode, and an interval between a pixel electrode corresponding to another color pixel adjacent to the one color pixel and the counter electrode facing the pixel electrode. Is a liquid crystal display device according to any one of <1> to <3>, wherein the difference is 0.3 to 1.0 μm.
<5> The liquid crystal display device according to any one of <1> to <4>, wherein the liquid crystal molecules contained in the liquid crystal layer are bend aligned or vertically aligned.
<6> The liquid crystal display device according to any one of <1> to <5>, wherein the optically anisotropic layer is a cellulose acetate film.
<7> The liquid crystal display device according to any one of <1> to <6>, further including another optically anisotropic layer, wherein the other optically anisotropic layer includes a discotic compound. .

  According to the present invention, in order to reduce the cost without increasing the thickness of the polarizing plate, it is possible to provide a liquid crystal display device exhibiting a good color with the polarizing plate provided with one optical compensation film.

The liquid crystal display device according to the present invention will be described in detail below.
In the description of the present embodiment, “45 °”, “parallel” or “orthogonal” means that the angle is within a range of strictly less than ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °. Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction. Further, the “slow axis” means a direction in which the refractive index is maximized. The “visible light region” means 380 to 780 nm. Further, the refractive index measurement wavelength is a value in the visible light region (λ = 550 nm) unless otherwise specified.

In the description of the present embodiment, the term “polarizing plate” is used to include both a long polarizing plate and a polarizing plate cut into a size incorporated in a liquid crystal device unless otherwise specified. Yes. Here, “cutting” includes “punching” and “cutting out”.
In the description of the present embodiment, “polarizing film” and “polarizing plate” are distinguished from each other. However, “polarizing plate” is a laminate having a transparent protective film that protects the polarizing film on at least one side of “polarizing film”. It shall mean the body.

In the description of the present embodiment, the “molecular symmetry axis” refers to a symmetry axis when the molecule has a rotational symmetry axis, but strictly requires that the molecule is rotationally symmetric. is not.
In general, in a discotic liquid crystalline compound, the molecular symmetry axis coincides with an axis perpendicular to the disc surface passing through the center of the disc surface, and in a rod-like liquid crystalline compound, the molecular symmetry axis is the major axis of the molecule. Match.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (if there is no slow axis, any in-plane film The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (A) and (B).
... Formula (A)
However, Re (θ) represents the retardation value in the direction inclined by the angle θ from the normal direction.
Further, nx in the formula (A) represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz represents the refraction in the direction orthogonal to nx and ny. Represents a rate.
Rth = ((nx + ny) / 2−nz) × d (Equation (B)
When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is the above-mentioned Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotary axis), and −50 degrees to +50 degrees with respect to the film normal direction. Measured at 11 points by making light of wavelength λ nm incident from each tilted direction in 10 degree steps, and based on the measured retardation value, assumed value of average refractive index, and input film thickness value KOBRA 21ADH or WR is calculated.
In the above measurement, as the assumed value of the average refractive index, the values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used.
Moreover, about the thing whose average refractive index value is not known, it can measure with an Abbe refractometer. The average refractive index values of the main optical films are exemplified below: cellulose acetate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  Moreover, in this specification, "~" shall be used in the meaning which contains the numerical value described before and behind as a lower limit and an upper limit.

(Configuration of liquid crystal display device and polarizing plate)
The liquid crystal display device of the present invention is preferably a bend alignment mode liquid crystal display device. Hereinafter, a bend alignment mode liquid crystal display device will be described.
FIG. 1 is a cross-sectional view schematically showing the alignment of the liquid crystal compound in the bend alignment liquid crystal cell.
As shown in FIG. 1, the bend alignment liquid crystal cell has a structure in which a liquid crystal compound 11 is sealed between an upper substrate 14a and a lower substrate 14b. The liquid crystal compound 11 used in the bend alignment liquid crystal cell generally has a positive dielectric anisotropy.
The upper substrate 14a and the lower substrate 14b of the liquid crystal cell have alignment films 12a and 12b and electrode layers 13a and 13b, respectively.
The alignment film has a function of aligning the rod-like liquid crystal molecules 11a to 11j. Note that RD is the rubbing direction of the alignment film. The electrode layer has a function of applying a voltage to the rod-like liquid crystal molecules 11a to 11j.

When the applied voltage of the bend alignment liquid crystal cell is low, as shown in the off of FIG. 1, the rod-like liquid crystalline molecules 11a to 11e on the upper substrate 14a side of the liquid crystal cell and the rod-like liquid crystalline molecules 11f to 11j on the lower substrate 14b side Are oriented in the opposite direction (vertically symmetrical).
Further, the rod-like liquid crystalline molecules 11a, 11b, 11i, 11j in the vicinity of the substrates 14a, 14b are aligned in a substantially horizontal direction, and the rod-like liquid crystalline molecules 11d to 11g in the center of the liquid crystal cell are aligned in a substantially vertical direction.

On the other hand, as shown in on of FIG. 1, when the applied voltage is high, the rod-like liquid crystal molecules 11a and 11j in the vicinity of the substrates 14a and 14b remain substantially horizontally aligned.
Further, the rod-like liquid crystal molecules 11e and 11f at the center of the liquid crystal cell remain aligned substantially vertically. The alignment changes with increasing voltage in the rod-like liquid crystal molecules 11b, 11c, 11d, 11g, 11h, and 11i located between the substrate and the center of the liquid crystal cell, which are perpendicular to the off state. Orient.
However, it is off that the rod-like liquid crystalline molecules 11a to 11e on the upper substrate 14a side of the liquid crystal cell and the rod-like liquid crystalline molecules 11f to 11j on the lower substrate 14b side are oriented in opposite directions (vertically symmetrical). It is the same as the state.

FIG. 2 is a schematic diagram showing a polarizing plate.
As shown in FIG. 2, the polarizing plate of the present invention includes a first optical anisotropic layer 31 containing discotic compounds 31a to 31e and a second optical anisotropic layer 33 containing at least one cellulose acetate film. And a laminated body of the polarizing film 34.
The polarizing plate shown in FIG. 2 has an alignment film 32 between the first optical anisotropic layer 31 and the second optical anisotropic layer 33.
The discotic compounds 31a to 31e of the first optically anisotropic layer 31 are planar molecules.
The discotic compounds 31a to 31e have only one plane, that is, a disk plane in the molecule. The disk surface is inclined with respect to the surface of the second optical anisotropic layer 33.
The angle (tilt angle) between the disk surface and the surface of the second optically anisotropic layer increases as the distance from the discotic compound and the alignment film increases. The average inclination angle is preferably in the range of 15 to 50 °.
As shown in FIG. 2, when the tilt angle is changed, the viewing angle expansion function of the polarizing plate is remarkably improved.
Further, the polarizing plate with the tilt angle changed has a function of preventing the reversal of the display image, the gradation change, or the occurrence of coloring. The average of the direction PL in which the normal NL of the disc surface of the discotic compounds 31a to 31e is orthogonally projected onto the second optical anisotropic layer 33 has an antiparallel relationship with the rubbing direction RD of the alignment film 32.

The preferred functions of the present invention are the average direction of orthogonal projection of the discotic normal of the disc surface to the second optical anisotropic layer 33, and the in-plane slow axis of the second optical anisotropic layer 33. The angle with SA is substantially 45 °. Therefore, in the manufacturing process of the polarizing plate, if the angle θ between the rubbing direction RD of the alignment film 32 and the in-plane slow axis SA of the second optical anisotropic layer is adjusted to be substantially 45 °, Good.
Furthermore, in the present invention, the second in-plane slow axis SA of the second optical anisotropic layer 33 and the in-plane transmission axis TA of the polarizing film 34 are substantially parallel or substantially perpendicular to each other. The optically anisotropic layer 33 and a polarizing film are disposed.
In the polarizing plate shown in FIG. 2, one second optically anisotropic layer is arranged in parallel. The in-plane slow axis SA of the second optical anisotropic layer 33 corresponds to the extending direction of the second optical anisotropic layer 33 in principle. The in-plane transmission axis TA of the polarizing film 34 corresponds in principle to a direction perpendicular to the extending direction of the polarizing film.

FIG. 3 is a schematic view showing a bend alignment type liquid crystal display device which is preferable in the present invention.
As shown in FIG. 3, the liquid crystal display device of the present invention includes a bend alignment liquid crystal cell 10, a pair of polarizing plates disposed on both sides of the liquid crystal cell, and a backlight BL. The bend alignment liquid crystal cell 10 corresponds to the liquid crystal cell shown in FIG.
The upper and lower rubbing directions RD2 and RD3 of the liquid crystal cell 10 are the same direction (parallel).
The polarizing plate includes a first optically anisotropic layer 31A (31B), a second optically anisotropic layer 33A (33B), and a polarizing film 34A (34B) stacked in this order from the liquid crystal cell 10 side. Become.
The rubbing directions RD1 and RD4 of the discotic compound of the first optically anisotropic layers 31A and 31B are in an antiparallel relationship with the rubbing directions RD2 and RD3 of the liquid crystal cell 10 facing each other.
As described above, the rubbing directions RD <b> 1 and RD <b> 4 of the discotic compound are antiparallel to the average direction obtained by orthogonally projecting the normal line of the disc surface to the second optical anisotropic layer 33.
The in-plane slow axes SA1 and SA2 of the second optical anisotropic layers 33A and 33B and the in-plane transmission axes TA1 and TA2 of the polarizing films 34A and 34B are in the same plane as the discotic compound rubbing directions RD1 and RD4. The angle is substantially 45 °.
The two polarizing films 34A and 34B are arranged so that the in-plane transmission axes TA1 and TA2 are orthogonal to each other (crossed Nicols).

<Liquid crystal cell>
FIG. 5 is a cross-sectional view showing the configuration of the liquid crystal cell of the liquid crystal display device of the present invention.
As shown in FIG. 5, in the liquid crystal cell 11, one substrate (upper substrate 14 a) and another substrate (lower substrate 14 b) are arranged to face each other at a predetermined interval (cell gap) via a spacer 60. The liquid crystal layer 11a is sealed in the formed space.
A plurality of color pixels 51 are arranged in a grid pattern on the surface of the upper substrate 14 a on the lower substrate 14 b side, and a transparent electrode film (ITO film) is used as the counter electrode 52 so as to cover the plurality of color pixels 51. An alignment film 53 for aligning the liquid crystal molecules 11 included in the liquid crystal layer 11 a is formed on the counter electrode 52. A black matrix BM is formed between the color pixels 51.
On the other hand, on the surface of the lower substrate 14b on the upper substrate 14a side, pixel electrodes 54 are arranged corresponding to the arrangement of the color pixels 51, and the liquid crystal molecules contained in the liquid crystal layer 11a are also on the pixel electrodes 54. An alignment film 55 for aligning 11 is formed.
In the liquid crystal cell 10 used in the liquid crystal display device of the present invention, the distance S between the pixel electrode 54 and the counter electrode 52 facing the pixel electrode 54 is different for each color pixel 51 corresponding to the pixel electrode 54. “Multi-gap structure” is adopted.
For example, the distance between the pixel electrode 54 corresponding to the red pixel 51R and the region of the counter electrode 52 facing the pixel electrode 54 and the red pixel 51R is S _R (μm), and the pixel electrode 54 corresponding to the green pixel 51G The spacing between the pixel electrode 54 and the region of the counter electrode 52 facing the green pixel 51G is S _G (μm), and the pixel electrode 54 corresponding to the blue pixel 51B is opposed to the pixel electrode 54 and the blue pixel 51B. The dimensions of S _R , S _G , and S _B are designed so that S _R > S _G > S _B , where S _B (μm) is the distance from the counter electrode 52 region.

As a method for measuring the distance S between the pixel electrode 54 and the counter electrode 52 facing the pixel electrode 54, an OPTIPRO (manufactured by SHINTTECH) measurement apparatus was used.
The difference between S _R , S _G , and S _B was determined by measuring the steps between the red, green, and blue pixels of the counter electrode using a micromap measuring device.

Here, these intervals do not necessarily satisfy the relationship S _R > S _G > S _B , and it is sufficient that each of S _R , S _G , and S _B is different, and S _R > S _B and S _G > S _B are more preferably satisfied, and S _R > S _R > S _R is particularly preferable.

  As a structure in which the interval S between the pixel electrode 54 and the counter electrode 52 facing the pixel electrode 54 is different, as shown in FIG. 5, the thickness of each color pixel 51 (upper substrate 14a and lower substrate 14b) The distance between the counter electrode 52 formed in a substantially uniform thickness and each pixel electrode 54 is different depending on the arrangement of the color pixels 51 by changing Alternatively, as shown in FIG. 6, a structure in which the thickness of each color pixel 51 is made uniform and the thickness of the counter electrode 52 is changed in a region corresponding to the color pixel 51 may be adopted.

Further, the distance between the pixel electrode 54 corresponding to one color pixel 51 and the counter electrode 52 facing the pixel electrode 54, and the pixel electrode 54 corresponding to another color pixel 51 adjacent to the one color pixel 51 and the counter electrode facing it. The difference from the gap with the electrode 52 is preferably 0.3 to 1.0 μm. Specifically, the difference between adjacent S _R and S _G , the difference between adjacent S _G and S _B , or the difference between adjacent S _B and S _R is 0.3 to 1.0 μm. It is preferable.

<Polarizing plate>
The polarizing plate is configured by bonding the first optical anisotropic layer and the second optical anisotropic layer to a polarizing film.

<< Polarizing film >>
The polarizing film includes an orientation type polarizing film or a coating type polarizing film (manufactured by Optiva Inc.).
The oriented polarizing film preferably contains a binder and iodine or a dichroic dye.
Iodine and dichroic dyes exhibit deflection performance by being oriented in the binder.
It is preferable that the iodine and the dichroic dye are aligned along the binder molecule, or the dichroic dye is aligned in one direction by self-assembly like a liquid crystalline compound.
A commercially available oriented polarizing film is produced by immersing a stretched polymer in iodine or a dichroic dye solution in a bath, and allowing the iodine or dichroic dye to penetrate into the binder. Yes.
In addition, the commercially available polarizing film has iodine or dichroic dye distributed about 4 μm (about 8 μm on both sides) from the polymer surface, and in order to obtain sufficient polarization performance, the thickness should be 10 μm or more. Is preferred.
The degree of penetration can be controlled by the solution concentration of iodine or dichroic dye, the bath temperature and the immersion time.
The thickness of the polarizing film is preferably not more than a commercially available polarizing plate (30 μm), more preferably 25 μm or less, and particularly preferably 20 μm or less. If it is 20 μm or less, the light leakage phenomenon is not observed in a 17-inch liquid crystal display device.

The binder of the polarizing film may be cross-linked. As the binder for the polarizing film, a polymer that can be crosslinked by itself may be used. Applying light, heat, or pH change to a polymer having a functional group, or a polymer obtained by introducing a functional group into the polymer, reacting the functional group to crosslink between the polymers to form a polarizing film it can.
Moreover, you may introduce | transduce a crosslinked structure into a polymer with a crosslinking agent. It can be formed by cross-linking between binders by introducing a bonding group derived from the cross-linking agent between binders using a cross-linking agent which is a compound having high reaction activity.
In general, the crosslinking can be performed by applying a coating liquid containing a crosslinkable polymer or a mixture of a polymer and a crosslinking agent on a transparent support and then heating.
Since it is only necessary to ensure durability at the product stage, the crosslinking treatment may be performed at any stage until a polarizing plate as a product is obtained.

As the binder of the polarizing film, a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be preferably used.
Examples of such polymers include polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, polystyrene, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylolacrylamide), polyvinyltoluene, chlorosulfonated polyethylene, nitrocellulose, chlorine Polyolefin (eg, polyvinyl chloride), polyester, polyimide, polyvinyl acetate, polyethylene, carboxymethyl cellulose, polypropylene, polycarbonate, and copolymers thereof (eg, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer) Styrene / vinyltoluene copolymer, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer).
Moreover, you may use a silane coupling agent as a polymer. Water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are particularly preferable. preferable.

The saponification degree of polyvinyl alcohol and modified polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%, and particularly preferably 95 to 100%. The polymerization degree of polyvinyl alcohol is preferably 100 to 5,000.
Modified polyvinyl alcohol is obtained by introducing a modifying group into polyvinyl alcohol by copolymerization modification, chain transfer modification or block polymerization modification.
Examples of the modifying group to be introduced in _{copolymerization, -COONa, -Si (OX) 3} (X is a hydrogen atom or an alkyl _{group), - N (CH 3)} 3 · Cl, -C 9 H 19, -COO , _-SO 3 _Na, includes _-C 12 _{H 25.}
Examples of the modifying group to be introduced in the chain transfer include -COONa, _-SH, a _-SC 12 _{H 25.}
The degree of polymerization of the modified polyvinyl alcohol is preferably 100 to 3,000.
The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509, and JP-A-9-316127.
Unmodified polyvinyl alcohol having a saponification degree of 85 to 95% and alkylthio-modified polyvinyl alcohol are particularly preferable.
Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (eg, boric acid, borax) can also be used as cross-linking agents.
When a large amount of the crosslinking agent for the binder is added, the heat and humidity resistance of the polarizing film can be improved.
Moreover, it can suppress more effectively that the orientation of an iodine or a dichroic dye falls by making a crosslinking agent into 50 mass% or less with respect to a binder. 0.1-20 mass% is preferable with respect to a binder, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable.
The binder contains some crosslinking agent that has not reacted even after the crosslinking reaction has been completed. However, the amount of the remaining crosslinking agent is preferably 1.0% by mass or less and more preferably 0.5% by mass or less in the binder. By setting the content to 1.0% by mass or less, durability can be further increased. That is, it is possible to more effectively prevent a decrease in the degree of polarization when a polarizing film having a large amount of residual crosslinking agent is incorporated in a liquid crystal display device and used for a long time or left in a high temperature and high humidity atmosphere for a long time.

The dichroic dye includes an azo dye, a stilbene dye, a pyrazolone dye, a triphenylmethane dye, a quinoline dye, an oxazine dye, a thiazine dye, or an anthraquinone dye. The dichroic dye is preferably water-soluble.
The dichroic dye preferably has a hydrophilic substituent (for example, a sulfo group, an amino group, or a hydroxyl group).
Examples of dichroic dyes include C.I. I. Direct Yellow 12, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Direct Violet 48, C.I. I. Direct Blue 67, C.I. I. Direct Blue 90, C.I. I. Direct Green 59, C.I. I. Acid Red 37 is included.
Regarding the dichroic dyes, JP-A-1-161202, JP-A-1-172906, JP-A-1-172907, JP-A-1-183602, JP-A-1-248105, JP-A-1 -265205 and JP-A-7-261024. In the present invention, the dichroic dyes described therein can be employed.

The dichroic dye is used as a free acid or a salt (for example, an alkali metal salt, an ammonium salt, or an amine salt).
Moreover, the polarizing film which has various hues can be manufactured by mix | blending two or more types of dichroic dyes.
A polarizing film using a compound (pigment) that exhibits a black color when the polarization axes are orthogonal to each other, or a polarizing film that is blended with various dichroic molecules so as to exhibit a black color, has excellent single-plate transmittance and polarizability. Yes.

The polarizing film stretches the binder in the longitudinal direction (MD direction) of the polarizing film (stretching method). Or after rubbing, it dye | stains with an iodine and a dichroic dye (rubbing method).
In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times.
Stretching can be preferably carried out by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water.
The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times.
The stretching step may be performed in several steps. By dividing into several times, it is possible to stretch more uniformly even at high magnification.
Before stretching, some stretching may be performed horizontally or vertically (a degree that prevents shrinkage in the width direction).

From the viewpoint of yield, it is preferable that the film is stretched with an inclination of 10 to 80 ° relative to the longitudinal direction. In that case, stretching can be performed by performing tenter stretching in biaxial stretching in different steps.
The biaxial stretching is the same as the stretching method performed in normal film formation.
In biaxial stretching, stretching is performed at different speeds on the left and right, so that the thickness of the binder film before stretching must be different on the left and right.
In casting film formation, the flow rate of the binder solution can be differentiated between the left and right sides by tapering the die.
The tilt angle is preferably stretched so as to match the angle formed between the transmission axes of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the liquid crystal display device and the vertical or horizontal direction of the liquid crystal cell. A normal inclination angle is 45 °.
However, recently, transmissive, reflective, and transflective liquid crystal display devices have been developed that are not necessarily 45 °, and it is preferable that the stretching direction can be arbitrarily adjusted according to the design of the liquid crystal display device.
As described above, a binder film obliquely stretched by 10 to 80 degrees with respect to the MD direction of the polarizing film is produced.

In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment process of the liquid crystal display device can be applied. That is, the orientation is obtained by rubbing the surface of the film in a certain direction using paper, gauze, felt, rubber, nylon, or polyester fiber.
Generally, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are planted on average.
It is preferable to carry out using a rubbing roll in which the roundness, cylindricity, and deflection (eccentricity) of the roll itself are all 30 μm or less.
The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more.
When rubbing a long film, it is preferable to transport the film at a speed of 1 to 100 m / min with a constant tension by a transport device.
The rubbing roll is preferably rotatable in the horizontal direction with respect to the film traveling direction for setting an arbitrary rubbing angle. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used in a liquid crystal display device, 40 to 50 ° is more preferable, and 45 ° is particularly preferable.

It is preferable to arrange protective films on both surfaces of the polarizing film, and it is preferable to use a part of the roll-shaped optical compensation film as the protective film on one surface.
For example, protective film / polarizing film / second optical anisotropic layer / first optical anisotropic layer, or protective film / polarizing film / second optical anisotropic layer / alignment film / first optical The laminated body laminated | stacked in order of the anisotropic layer is preferable.
The polarizing film and the surface side of the first optical anisotropic layer may be bonded together. An adhesive can be used for bonding, and the adhesive is preferably a polyvinyl alcohol resin (including modified polyvinyl alcohol by acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) or an aqueous boron compound solution. Can be used. Among these, polyvinyl alcohol resin is particularly preferable.
The thickness of the adhesive layer is preferably in the range of 0.01 to 10 μm after drying, and more preferably in the range of 0.05 to 5 μm.
A light diffusion film or an antiglare film may be bonded to the surface of the polarizing plate.

When the polarizing film is used in a liquid crystal display device, it is preferable to provide an antireflection layer on the viewing side surface. The antireflection layer may also be used as a protective layer on the viewing side of the polarizing film. From the viewpoint of suppressing a change in tint depending on the viewing angle of the liquid crystal display device, the internal haze of the antireflection layer is preferably 50% or more.
The antireflection layer is described in JP-A No. 2001-33783, JP-A No. 2001-343646, and JP-A No. 2002-328228.

<First optically anisotropic layer>
The first optically anisotropic layer preferably contains a liquid crystalline compound or a discotic compound, and more preferably contains a discotic compound exhibiting liquid crystallinity. The first optically anisotropic layer is “another optically anisotropic layer” in the claims.
The Re value measured from the film normal direction of the first optically anisotropic layer is preferably 0 to 40 nm, more preferably 20 to 40 nm, and particularly preferably 25 to 40 nm.
The first optically anisotropic layer is preferably designed so as to compensate for the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device.
The alignment state of the liquid crystal compound in the liquid crystal cell is described in IDW'00, FMC7-2, P411 to 414.
The discotic compound is preferably a high-molecular liquid crystalline compound or a low-molecular liquid crystalline compound having a discotic molecular structure. Furthermore, a compound that does not exhibit liquid crystallinity by polymerizing or crosslinking these liquid crystalline compounds may be used.

<< discotic compound >>
Discotic compounds include benzene derivatives (reported in C. Destrade et al., Mol. Cryst. 71, 111 (1981)), truxene derivatives (C. Destrade et al., Mol. Cryst. 122). 141 (1985), Physics lett, A, 78, 82 (1990)), cyclohexane derivatives (B. Kohne, et al., Angew. Chem. 96, 70 (1984). And azacrown- or phenylacetylene-based macrocycles (J.M. Lehn et al., J. Chem. Commun., 1,794 (1985)), J. Zhang et al., J. Chem. Am. Chem. Soc. 116, 2,655 (1994)) .

The discotic compound generally has a structure in which a linear alkyl group, an alkoxy group, or a substituted benzoyloxy group is radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule.
It is preferable that the molecule or the assembly of molecules has rotational symmetry and can give a certain orientation.
Although the first optically anisotropic layer is formed from a discotic compound, the compound contained in the first optically anisotropic layer does not necessarily need to be a compound exhibiting liquid crystallinity.
For example, low-molecular liquid crystalline discotic compounds have groups that react with heat and light, and as a result, include compounds that are polymerized or cross-linked by reaction with heat and light, resulting in high molecular weight and loss of liquid crystallinity. .
The discotic compound is described in JP-A-8-50206, and the polymerization of the discotic compound is described in JP-A-8-27284.

As a means for fixing the discotic compound by polymerization, a polymerizable group may be bonded as a substituent to the discotic core of the discotic compound.
The disk-shaped core and the polymerizable group can be kept in an oriented state even after the polymerization reaction by being bonded via a linking group.
The discotic compound having a polymerizable group is described in paragraph numbers [0151] to [0168] of JP-A No. 2000-155216.

[Alignment film]
The alignment film can be used, for example, as one having a function of defining the alignment direction of the liquid crystalline molecules of the first optically anisotropic layer.
If the alignment state is fixed after aligning the liquid crystalline compound, the alignment film terminates its role. Therefore, the alignment film is not essential as a component of the manufactured liquid crystal display device.
For example, by transferring the first optical anisotropic layer with the alignment state fixed onto the second optical anisotropic layer, the first optical anisotropic layer and the second optical anisotropic layer In the meantime, a liquid crystal display device without an alignment film can be manufactured.
However, generally, an alignment film is provided between the first optical anisotropic layer and the second optical anisotropic layer.

The alignment film is an organic compound (for example, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodget method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate).
Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

The alignment film is preferably formed by polymer rubbing treatment. The rubbing treatment is the same as the treatment method widely adopted as the liquid crystal alignment treatment process of LCD.
That is, the orientation is obtained by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, or polyester fiber.
In general, rubbing is performed several times on a fiber having a uniform length and thickness using a cloth that is flocked on average.
In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
The polymer used for the alignment film preferably has a function of fixing the alignment of the liquid crystalline molecules in addition to the function of aligning the liquid crystalline molecules. For example, a side chain having a crosslinkable functional group (for example, a double bond) is bonded to the main chain of the polymer, or a crosslinkable functional group having a function of aligning liquid crystal molecules is introduced into the polymer side chain. It is preferable.
The polymer used for the alignment film is preferably crosslinkable per se or can be crosslinked by the use of a crosslinking agent.
Crosslinkable polymers are described in paragraph [0022] of JP-A-8-338913.

<Second optically anisotropic layer>
The second optical anisotropic layer is composed of at least one polymer film. Here, the term “consisting of a polymer film” means that the film contains not only a polymer but also various additives (plasticizer, retardation increasing agent, etc.) in addition to the polymer. Further, the second optical anisotropic layer can be constituted by a plurality of polymer films to achieve the optical anisotropy defined by the present invention. However, the optical anisotropy defined by the present invention can be realized by a single polymer film. Therefore, the second optically anisotropic layer is particularly preferably composed of a single polymer film.

Here, in-plane retardations Re ₍₄₅₀₎ , Re ₍₅₅₀₎ , and Re ₍₆₃₀₎ with respect to light having wavelengths of 450 nm, 550 nm, and 630 nm in the second optical anisotropic layer, and the thickness direction The retardations Rth ₍₄₅₀₎ , Rth ₍₅₅₀₎ , and Rth ₍₆₃₀₎ satisfy the following formulas (1) to (4).
Re ₍₄₅₀₎ / Re ₍₅₅₀₎ <1 ... Formula (1)
Re ₍₆₃₀₎ / Re ₍₅₅₀₎ > 1 ..... Formula (2)
Rth ₍₄₅₀₎ / Rth ₍₅₅₀₎ <1 Equation (3)
Rth ₍₆₃₀₎ / Rth ₍₅₅₀₎ > 1 formula (4)
In the above formulas (1) to (4), Re and Rth are the refractive index in the slow axis direction (direction in which the refractive index is maximum) in the plane of the second optical anisotropic layer, and nx, The refractive index in the fast axis direction (direction in which the refractive index is minimum) in the plane of the second optical anisotropic layer is ny, the refractive index in the thickness direction of the second optical anisotropic layer is nz, When the thickness of the second optical anisotropic layer is d (nm), it is a value represented by Re = (nx−ny) × d, and Rth = {(nx + ny) / 2−nz} × d The value represented.

In addition, the second optically anisotropic layer specifically has an Rth value measured with light having a wavelength of 550 nm, preferably in the range of 100 to 300 nm, and more preferably in the range of 100 to 165 nm.
Further, the Re value of the second optically anisotropic layer is preferably 20 to 60 nm, and more preferably 20 to 50 nm.

  The polymer film is preferably a cellulose polymer, more preferably a cellulose ester, and particularly preferably a lower fatty acid ester of cellulose. Lower fatty acid means a fatty acid having 6 or less carbon atoms. Cellulose acetate having 2 to 4 carbon atoms is preferable, and cellulose acetate is more preferable. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may be used.

  Further, the viscosity average polymerization degree (DP) of the polymer film (hereinafter sometimes referred to as cellulose acetate (film)) is preferably 250 or more, and more preferably 290 or more. The cellulose acetate preferably has a narrow molecular weight distribution of Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) by gel permeation chromatography. The specific value of Mw / Mn is preferably 1.00 to 1.70, more preferably 1.30 to 1.65, and particularly preferably 1.40 to 1.60. .

The acetylation degree of the cellulose acetate is preferably 55.0 to 62.5%, more preferably 57.0 to 62.0%.
The degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The degree of acetylation is determined by measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like).
For example, in cellulose acetate, the hydroxyl groups at the 2-position, 3-position, and 6-position of cellulose are not evenly substituted but the degree of substitution at the 6-position tends to be small. In the cellulose acetate used for the second optically anisotropic layer, it is preferable that the degree of substitution at the 6-position of cellulose is the same or higher than that at the 2- and 3-positions.
The ratio of the substitution degree at the 6-position to the total substitution degree at the 2-position, the 3-position, and the 6-position is preferably 30 to 40%, more preferably 31 to 40%, and more preferably 32 to 40%. It is particularly preferred. The substitution degree at the 6-position is preferably 0.88 or more.
The cellulose acetate and a method for synthesizing the same are described on page 9 of JIII Journal of Technical Disclosure No. 2001-1745.

<< Retardation adjustment >>
In order to adjust the retardation of the cellulose acetate, a method of applying an external force such as stretching is generally used, but a retardation increasing agent may be added to adjust the optical anisotropy.

<< Retardation raising agent >>
[Retardation increasing agent for controlling Re]
In order to control the absolute value of Re of the protective film (optical compensation film) of the present invention, a compound having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution is used as a retardation increasing agent. Is preferred.
By using such a compound, the absolute value can be controlled without substantially changing the wavelength dependency of Re in the visible region.
In addition, from the viewpoint of the function of the retardation increasing agent, a rod-like compound is preferable, preferably having at least one aromatic ring, and more preferably having at least two aromatic rings.
The rod-shaped compound preferably has a linear molecular structure. The linear molecular structure means that the molecular structure of the rod-shaped compound is linear in the thermodynamically most stable structure.
The thermodynamically most stable structure can be obtained by crystal structure analysis or molecular orbital calculation.
For example, molecular orbital calculation is performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited), and a molecular structure that minimizes the heat of formation of a compound can be obtained.
Here, the molecular structure being linear means that the angle of the molecular structure is 140 ° or more in the thermodynamically most stable structure obtained by calculation as described above.
The rod-like compound preferably exhibits liquid crystallinity. More preferably, the rod-like compound exhibits liquid crystallinity upon heating (has thermotropic liquid crystallinity). The liquid crystal phase is preferably a nematic phase or a smectic phase.

As a preferable compound of the rod-like compound, a compound described in JP-A-2004-4550 can be employed, but is not limited thereto. Two or more rod-shaped compounds having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.
The rod-like compound can be synthesized with reference to methods described in literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 pages (1979), 89, 93 pages (1982), 145, 111 pages (1987), 170, 43 pages (1989), J. Am. Am. Chem. Soc. 113, 1,349 (1991), 118, 5,346 (1996), 92, 1,582 (1970); Org. Chem. , 40, 420 pages (1975), Tetrahedron, 48, No. 16, 3,437 pages (1992).
In addition, it is preferable that the addition amount of a retardation raising agent is 0.1-30 mass% of the quantity of a polymer, and it is still more preferable that it is 0.5-20 mass%.

[Retardation increasing agent for controlling Rth]
In order to express desired Rth, it is preferable to use a retardation increasing agent.
Here, “retardation increasing agent” in the present specification was prepared in exactly the same manner except that the Re retardation value measured at a wavelength of 550 nm of a cellulose acylate film containing an additive did not contain the additive. It means an “additive” that is 20 nm or more higher than the Rth retardation value measured at a wavelength of 550 nm of the cellulose acylate film.
The increase in retardation value is preferably 30 nm or more, more preferably 40 nm or more, and further preferably 60 nm or more.

The retardation increasing agent is preferably a compound having at least two aromatic rings. The retardation increasing agent is preferably used in the range of 0.01 to 20 parts by mass, more preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the polymer. It is more preferable to use in the range of -5 mass parts, and it is especially preferable to use in the range of 0.5-2 mass parts. Two or more retardation increasing agents may be used in combination.
The retardation increasing agent preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.
The retardation increasing agent for controlling Rth preferably does not affect Re expressed by stretching, and is preferably a discotic compound.
The discotic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring, and the aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).

<Stretching method>
The cellulose acylate film of the present invention also exhibits functions by stretching as described above.
The following is a preferred stretching method for the present invention, and the cellulose acylate film of the present invention is preferably stretched in the width direction when applied to a polarizing plate. About this stretching method, for example, in JP-A-62-115035, JP-A-4-152125, JP-A-4-284221, JP-A-4-298310, JP-A-11-48271, etc. Are listed.
In addition, the cellulose acylate film of the present invention is stretched under the conditions of 25 to 100 ° C., which is the Tg of the film, as described above.
The cellulose acylate film of the present invention may be stretched uniaxially or biaxially.
Moreover, the cellulose acylate film of the present invention can be stretched by a treatment during drying, and is particularly effective when a solvent remains. For example, when the speed of the cellulose acylate film is adjusted so that the take-up speed of the cellulose acylate film is higher than the peel-off speed of the cellulose acylate film, the cellulose acylate film is stretched.
The cellulose acylate film can also be stretched by conveying the cellulose acylate film while holding it with a tenter and gradually widening the width of the tenter.
Furthermore, after the cellulose acylate film is dried, it can be stretched using a stretching machine (preferably uniaxial stretching using a long stretching machine).
The stretching ratio of the cellulose acylate film of the present invention (ratio of increase due to stretching relative to the original length) is preferably 0.5 to 300%, more preferably 1 to 200%, and more preferably 1 to 100%. % Stretching is more preferred.

The cellulose acetate hygroscopic expansion coefficient is preferably 30 × 10 ⁻⁵ /% relative humidity or less, more preferably 15 × 10 ⁻⁵ /% relative humidity or less, and particularly preferably 10 × 10 ⁻⁵ /% relative humidity or less.
The hygroscopic expansion coefficient is preferably as small as possible, but is usually a value of 1.0 × 10 ⁻⁵ /% relative humidity or more. The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature. By adjusting the hygroscopic expansion coefficient, it is possible to prevent frame-like transmittance increase (light leakage due to distortion) while maintaining the optical compensation function of the optical compensation film.

  In order to reduce the dimensional change due to moisture absorption of the cellulose acetate, it is preferable to add a hydrophobic compound. The hydrophobic compound may be in the form of fine particles.

Examples of polymer film additives include UV inhibitors, release agents, antistatic agents, degradation inhibitors (eg, antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers). , Amines) and infrared absorbers.
When the polymer film is formed from multiple layers, the type and amount of additive in each layer may be different. The additives are described on pages 16 to 22 of the Japan Society for Invention and Innovation Technical Bulletin No. 2001-1745. The amount of additive used is generally in the range of 0.001 to 25% by weight of the polymer film.

The cellulose acetate is preferably produced by a solvend casting method. In the solvbend casting method, a film is produced using a solution (dope) in which a polymer material is dissolved in an organic solvent.
The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO—, and —COO—) can also be used as the organic solvent.
The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

The cellulose acetate can be prepared by a general method. Here, the general method means processing at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvend casting method.
The casting and drying methods in the sorbend casting method are described in US Pat. No. 2,336,310, US Pat. No. 2,367,603, US Pat. No. 2,429,078, US Pat. No. 2,429,297, US Pat. Specification, US Pat. No. 2,607,704, US Pat. No. 2,739,069, US Pat. No. 2,739,070, British Patent No. 6,407,731, and British Patent No. 7,368,922, Japanese Patent Publication No. 45-4554 JP-A-49-5614, JP-A-60-176834, JP-A-60-203430, JP-A-62-115035.
The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more.
The obtained film can be peeled off from the drum or band, and further dried by high-temperature air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent.
The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

  It is also possible to form a film by casting two or more layers using the prepared cellulose acetate solution (dope). In this case, it is preferable to produce a cellulose acetate film by a solvend casting method.

When casting a plurality of cellulose acetate liquids of two or more layers, it is possible to cast a plurality of cellulose acetate solutions, and cellulose acetate is supplied from a plurality of casting openings provided at intervals in the traveling direction of the support. Films may be produced while casting and laminating the solutions that contain them. For example, the methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be used. Adaptable.
Further, it may be formed into a film by casting a cellulose acetate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245. This method can be carried out by the methods described in JP-A No. 61-104413, JP-A No. 61-158413, and JP-A No. 6-134933. Further, a flow of a high-viscosity cellulose acetate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acetate solution, and the high-viscosity cellulose acetate solution and the low-viscosity cellulose acetate solution are simultaneously mixed. An extruded cellulose acetate film may be used.

Also, using two casting ports, the film cast on the support is peeled off by the first casting port, and the second casting is performed on the side that is in contact with the support surface to produce a film. May be.
This production method is, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose acetate solutions to be cast may be the same solution or different cellulose acetate solutions and are not particularly limited. In order to give a function to a plurality of cellulose acetate layers, a cellulose acetate solution corresponding to the function may be extruded from each casting port.
Furthermore, the cellulose acetate solution of the present invention can be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer).

In the conventional monolayer liquid, it is necessary to extrude a cellulose acetate solution having a high concentration and a high viscosity in order to obtain a necessary film thickness. In many cases, such a problem occurs due to a failure or flatness.
As a solution to this, by adopting a method of casting a plurality of cellulose acetate solutions from the casting port, it is possible to extrude a highly viscous solution onto the support at the same time, improving the flatness and improving the surface shape. Not only can the film be produced, but also the use of a concentrated cellulose acetate solution can reduce the drying load and increase the production speed of the film.

<< Plasticizer >>
A plasticizer can be added to the cellulose acetate film in order to improve mechanical properties or to increase the drying speed.
As the plasticizer, phosphoric acid ester or carboxylic acid ester is used.
Moreover, it is preferable that the addition amount of a plasticizer is 0.1-25 mass% of the quantity of a cellulose ester, It is more preferable that it is 1-20 mass%, It is especially preferable that it is 3-15 mass%. .

<< Surface treatment >>
The cellulose acetate film is preferably subjected to a surface treatment. Examples of the surface treatment method include corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali saponification treatment, and ultraviolet irradiation treatment. The surface treatment is described on pages 30 to 32 of the Japan Society for Invention and Innovation Technical Bulletin No. 2001-1745.

Instead of or in addition to the surface treatment, an undercoat layer (described in JP-A-7-333433) may be provided, and a plurality of undercoat layers may be provided.
For example, a polymer layer containing both a hydrophobic group and a hydrophilic group is provided as a first undercoat layer, and a hydrophilic polymer layer that adheres well to the alignment film is provided thereon as a second undercoat layer (Japanese Patent Laid-Open No. Hei. 11-248940).

(Liquid crystal display device)
The polarizing plate obtained by laminating the optical compensation film or the optical compensation film and the polarizing film is advantageously used for a liquid crystal display device, particularly a transmissive liquid crystal display device. The transmissive liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides thereof.
The polarizing plate includes a polarizing film and at least two transparent protective films disposed on both sides of the polarizing film. Further, the liquid crystal cell carries a liquid crystal between two electrode substrates.
One optical compensation film of the present invention is disposed between the liquid crystal cell and one polarizing plate, or two optical compensation films are disposed between the liquid crystal cell and both polarizing plates.
The polarizing plate of the present invention may be used as at least one of the two polarizing plates disposed on both sides of the liquid crystal cell. In this case, the polarizing plate of the present invention is arranged so that the optical compensation film is on the liquid crystal cell side.
The liquid crystal cell is preferably in a VA mode or an OCB mode.

(VA mode liquid crystal display device)
In a VA mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). (2) Liquid crystal cell (SID97, Digest of tech. Papers (Proceedings) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) in order to enlarge the viewing angle. (3) A liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary Collection 58- 59 (1998)), and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

(OCB mode liquid crystal display device)
The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell.
A liquid crystal display device using a bend alignment mode liquid crystal cell is disclosed in US Pat. No. 4,583,825 and US Pat. No. 5,410,422.
Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function.
For this reason, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode.
Similarly to the TN mode, the liquid crystal cell in the OCB mode is in the black display, and the alignment state in the liquid crystal cell is such that a rod-like liquid crystal molecule rises at the center of the liquid crystal cell and the rod-like liquid crystal molecule lies in the vicinity of the substrate of the liquid crystal cell. Is in a state.
The value of Δn × d of the liquid crystal cell is preferably 50 to 1,000 nm, and more preferably 500 to 1,000 nm.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Example 1)
<Production of cellulose acetate film>
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose triacetate (triacetyl cellulose: TAC) solution.

[Material / solvent composition]
・ Cellulose acetate (acetylation degree 60.2%) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 100 parts by mass ・ Triphenyl phosphate (plasticizer) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・-6.5 parts by mass-Biphenyl diphenyl phosphate (plasticizer)-5.2 parts by weight-Methylene chloride (first solvent)- ... 633 parts by mass Methanol (second solvent) ... 95 parts by mass
-Retardation increasing agent represented by the following structural formula (A): 3 parts by mass

The obtained dope was cast using a casting machine having a band having a width of 2 m and a length of 65 m. After the film surface temperature on the band reached 40 ° C., the film was dried for 1 minute, peeled off, and further dried with 135 ° C. drying air for 20 minutes to produce a film. Thereafter, this film was uniaxially stretched to 110% under a temperature condition of 175 ° C. to prepare a cellulose acetate film. In addition, Tg of the used cellulose acetate is 148 degreeC.
The thickness of the produced cellulose acetate film was 90 μm.

<Measurement of optical characteristics>
About the produced cellulose acetate film, Re value of wavelength 450nm, 550nm, and 630nm was measured using the automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd. product).
In addition, the Re value was measured with the slow axis in the plane as the tilt axis and tilt angles of 40 ° and −40 ° (Table 1). Using the film thickness and the refractive index nx in the slow axis direction as parameters, the refractive index ny in the fast axis direction and fitting to these measured values Re (550 nm), Re (40 °), and Re (−40 °) The refractive index nz in the thickness direction was obtained by calculation, and the Rth value was determined. The results are shown in Tables 2 and 3.

<Saponification treatment of cellulose acetate film>
On one side (band side) of the prepared cellulose acetate film, 1.5N potassium hydroxide in isopropyl alcohol was applied at 25 mL / m ² and left at 25 ° C. for 5 seconds. The surface of the film was dried by washing with running water for 10 seconds and blowing air at 25 ° C. In this way, only one surface of the cellulose acetate film was saponified.

<Formation of alignment film>
An alignment film coating solution having the following composition was applied to one surface (saponified surface) of the cellulose acetate film (second optically anisotropic layer) with a # 14 wire bar coater at 24 mL / m ² . Thereafter, the film was dried with warm air at 60 ° C. for 60 seconds and further with warm air at 90 ° C. for 150 seconds to form an alignment film.
Next, rubbing treatment was performed on the formed alignment film in the direction of 45 ° with the stretching direction of the second optically anisotropic layer (substantially coincident with the slow axis).

[Alignment film coating solution composition]
・ Modified polyvinyl alcohol represented by the following structural formula (B): 10 parts by mass, water: 371 parts by mass, methanol ... 119 parts by mass
・ Glutaraldehyde (crosslinking agent) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 0.5 parts by mass

<Formation of first optically anisotropic layer>
In 204.0 parts by mass of methyl ethyl ketone, 91 parts by mass of a discotic compound represented by the following structural formula (C), 9 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), cellulose 1.5 parts by mass of acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co., Ltd.), 0.91 parts by mass of a mixture of monoethyl citrate and diethyl citrate, photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) ) 3 parts by mass and 1 part by mass of a sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) were dissolved to prepare a coating solution.
The coating solution was applied onto the alignment film by 4.7 mL / m ² using a # 2.7 wire bar. Thereafter, this was affixed to a metal frame and heated in a thermostat at 130 ° C. for 2 minutes to orient the discotic compound.
Next, using a 120 W / cm high-pressure mercury lamp at 90 ° C., the discotic compound was polymerized by irradiation with ultraviolet rays for 1 minute, and then allowed to cool to room temperature. Thus, an optical compensation film in which the first optical anisotropic layer was formed on the cellulose acetate film (second optical anisotropic layer) through the alignment film was produced.

<Measurement of optical characteristics of first optical anisotropic layer>
Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments), the Re value of the first optically anisotropic layer was measured at wavelengths of 450 nm, 550 nm, and 630 nm. The measurement results are shown in Table 1.

<Production of elliptically polarizing plate>
A polarizing film was prepared by adsorbing iodine to a stretched polyvinyl alcohol film.
Next, the second optical anisotropic layer side of the produced optical compensation film was attached to one surface of the polarizing film using a polyvinyl alcohol-based adhesive. At this time, the slow axis of the second optically anisotropic layer and the transmission axis of the polarizing film were arranged in parallel.
Thereafter, in the same manner as described above, the saponified surface side of a commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) having one surface saponified was treated with the polarization using a polyvinyl alcohol adhesive. Affixed to the other side of the membrane. In this manner, an elliptically polarizing plate was produced.

<Preparation of multi-gap bend alignment liquid crystal cell>
A polyimide film was provided as an alignment film on an opposing glass substrate with an ITO electrode, and the alignment film was rubbed. The obtained two glass substrates were opposed to each other in an arrangement in which the rubbing directions were parallel.
A liquid crystal compound (ZLI1132, manufactured by Merck & Co., Inc.) having a Δn of 0.1396 was injected into the thickness of the liquid crystal cell to produce a bend alignment liquid crystal cell. The created liquid crystal cell has a red pixel, a green pixel, and a blue pixel as color pixels of a plurality of colors. The green pixel and the red pixel include a green color filter having a predetermined thickness on the counter glass substrate.
On the other hand, the blue pixel includes a blue color filter having a thickness larger than that of the green color filter on the counter glass substrate. On the other hand, the red pixel includes a red color filter having a thickness smaller than that of the green color filter on the counter glass substrate.

  As a result, when the array substrate and the counter substrate are bonded in parallel, a predetermined gap is formed in the green pixel, while a cell gap that is smaller than the green pixel is formed in the blue pixel and larger than the green pixel in the red pixel. The

  In the bend alignment liquid crystal cell applied here, the distance between the blue pixel (450 nm) and the counter electrode facing it is 4.4 μm, and the distance between the green pixel (550 nm) and the counter electrode facing it is 4.5 μm. The distance between the red pixel (630 nm) and the counter electrode facing it was set to 4.6 μm.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device in which the liquid crystal cell is sandwiched between the two polarizing plates so that the side on which the second optically anisotropic layer is disposed in the polarizing plate is opposed to the glass substrate of the liquid crystal cell. Was made.
The liquid crystal cell and the two polarizing plates were arranged such that the rubbing direction of the liquid crystal cell and the rubbing direction of the second optically anisotropic layer facing it were antiparallel.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted by 60 ° clockwise from the normal direction of the liquid crystal cell in the azimuth direction of 45 ° with respect to the transmission axis of the polarizing plate when displaying black (see FIG. 7) a, b, c, d) and the respective color u′v ′ were measured. The results are shown in Table 5.
In Table 5, Δu′v ′ indicates a distance in chromaticity from “u ₀ ′ = 0.210526” and “v ₀ ′ = 0.4733684” where the color is neutral, and Δu 'v' = ((u′−u ₀ ′) ² + (v′−v ₀ ′) ² ) ^(1/2) .
Delta] u ', Delta] v' represents the difference between the respective _{u 0 ', v 0',} u 0 described in Table 5 ', v _0' color closer to a value of indicates to become neutral. If Δu ′ and Δv ′ are both greater than 0.03, the color will clearly change.

(Example 2)
<Production of cellulose acetate film>
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose triacetate (triacetyl cellulose: TAC) solution.

[Material / solvent composition]
・ Cellulose acetate (acetylation degree 60.2%) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 100 parts by mass ・ Triphenyl phosphate (plasticizer) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・-6.5 parts by mass-Biphenyl diphenyl phosphate (plasticizer)-5.2 parts by weight-Methylene chloride (first solvent)- ... 633 parts by mass Methanol (second solvent) ... 95 parts by mass
-Retardation increasing agent of structural formula (A) ... 3 parts by mass

The obtained dope was cast using a casting machine having a band having a width of 2 m and a length of 65 m. After the film surface temperature on the band reached 40 ° C., the film was dried for 1 minute, peeled off, and further dried with 135 ° C. drying air for 20 minutes. Thereafter, this film was uniaxially stretched to 105% under a temperature condition of 185 ° C. to prepare a cellulose acetate film. In addition, Tg of the used cellulose acetate is 148 degreeC.
The thickness of the produced cellulose acetate film was 130 μm.

<Measurement of optical characteristics>
About the produced cellulose acetate film, Re value and Rth value of wavelength 450nm, 550nm, and 630nm were measured using the automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd. product). The results are shown in Tables 2 and 3.

<Saponification treatment of cellulose acetate film>
Only one side of the cellulose acetate film was saponified in the same manner as in Example 1 except that the cellulose acetate film prepared in Example 2 was used.

<Formation of alignment film>
An alignment film was formed on one surface (surface saponified) of the cellulose acetate film in the same manner as in Example 1 except that the cellulose acetate film prepared in Example 2 was adopted. A rubbing treatment was performed.

<Formation of first optically anisotropic layer>
Except for employing the cellulose acetate film prepared in Example 2, the same procedure as in Example 1 was carried out, and the first optical difference was formed on the cellulose acetate film (second optically anisotropic layer) via the alignment film. An isotropic layer was formed to produce the optical compensation film of Example 2.

<Measurement of optical characteristics of first optical anisotropic layer>
Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments), the Re value of the first optically anisotropic layer was measured at wavelengths of 450 nm, 550 nm, and 630 nm. The measurement results are shown in Table 1.

<Production of elliptically polarizing plate>
A polarizing film was prepared in the same manner as in Example 1 except that the optical compensation film prepared in Example 2 was adopted, and an elliptically polarizing plate of Example 2 was prepared.

<Preparation of multi-gap bend alignment liquid crystal cell>
In the same manner as in Example 1, the interval between each color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing it was set, and a bend alignment liquid crystal cell was manufactured. Table 4 shows the distance between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device of Example 2 was produced in the same manner as Example 1.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

(Example 3)
<Production of cellulose acetate film>
A cellulose acetate film was produced in the same manner as in Example 1.

<Production of elliptically polarizing plate>
A polarizing film was produced in the same manner as in Example 1, and an elliptically polarizing plate of Example 3 was produced.

<Mounting evaluation with liquid crystal display devices>
<< Preparation of liquid crystal display device provided with VA alignment type liquid crystal cell >>
The liquid crystal cell has a cell gap between the substrates of 4.4 μm, and a liquid crystal material having negative dielectric anisotropy (“MLC6608”, manufactured by Merck & Co., Inc.) is dropped and sealed between the substrates. Prepared by forming a layer. The retardation of the liquid crystal layer (that is, the product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn) was set to 300 nm. The liquid crystal material was aligned so as to be vertically aligned.
Further, the interval between each color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing it was set to be different. Table 4 shows the distance between each set pixel and the counter electrode facing it.

  The polarizing plate produced in Example 1 is applied to the upper and lower polarizing plates of the liquid crystal display device using the above vertical alignment type liquid crystal cell, and the adhesive is applied so that the optical compensation film of Example 1 is on the liquid crystal cell side. Then, one sheet was attached to the observer side and the backlight side. The crossed Nicols were arranged so that the transmission axis of the polarizing plate on the viewer side was in the vertical direction and the transmission axis of the polarizing plate on the backlight side was in the horizontal direction.

<< Measurement of color >>
The prepared liquid crystal display device was placed on a backlight, and a voltage was applied to the vertically aligned liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

Example 4
<Preparation of optical compensation film and elliptically polarizing plate>
An optical compensation film was produced in the same manner as in Example 1, and an elliptically polarizing plate was produced using the optical compensation film and a polarizing film produced in the same manner as in Example 1.

<Preparation of multi-gap bend alignment liquid crystal cell>
A green pixel, a blue pixel, and a red pixel, and a counter electrode opposed to each color pixel so that the distance between the color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing them is approximately the same size. The bend alignment liquid crystal cell was prepared. Table 4 shows the value of the interval between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device was produced in the same manner as in Example 1.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

(Example 5)
<Preparation of optical compensation film and elliptically polarizing plate>
An optical compensation film was produced in the same manner as in Example 1, and an elliptically polarizing plate was produced using the optical compensation film and a polarizing film produced in the same manner as in Example 1.

<Preparation of multi-gap bend alignment liquid crystal cell>
A green pixel, a blue pixel, and a red pixel, and a counter electrode opposed to each color pixel so that the distance between the color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing them is approximately the same size. The bend alignment liquid crystal cell was prepared. Table 4 shows the value of the interval between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device was produced in the same manner as in Example 1.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

(Example 6)
<Preparation of optical compensation film and elliptically polarizing plate>
An optical compensation film was produced in the same manner as in Example 1, and an elliptically polarizing plate was produced using the optical compensation film and a polarizing film produced in the same manner as in Example 1.

<Preparation of multi-gap bend alignment liquid crystal cell>
A green pixel, a blue pixel, and a red pixel, and a counter electrode opposed to each color pixel so that the distance between the color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing them is approximately the same size. The bend alignment liquid crystal cell was prepared. Table 4 shows the value of the interval between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device was produced in the same manner as in Example 1.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

(Example 7)
<Preparation of optical compensation film and elliptically polarizing plate>
An optical compensation film was produced in the same manner as in Example 1, and an elliptically polarizing plate was produced using the optical compensation film and a polarizing film produced in the same manner as in Example 1.

<Preparation of multi-gap bend alignment liquid crystal cell>
A green pixel, a blue pixel, and a red pixel, and a counter electrode opposed to each color pixel so that the distance between the color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing them is approximately the same size. The bend alignment liquid crystal cell was prepared. Table 4 shows the value of the interval between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device was produced in the same manner as in Example 1.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

(Comparative Example 1)
<Preparation of cellulose acetate solution>
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

[Cellulose acetate solution composition]
・ Cellulose acetate with an acetylation degree of 60.9% ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 100 parts by mass ・ Triphenyl phosphate ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・-7.8 parts by mass-Biphenyl diphenyl phosphate ... 3.9 parts by mass-Methylene chloride ... ... 300 parts by mass
・ Methanol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 45 parts by mass

<Preparation of retardation increasing agent solution>
In another mixing tank, 4 parts by mass of cellulose acetate (linter) having an acetylation degree of 60.9%, 25 parts by mass of a retardation increasing agent of structural formula (A), and 0.5 parts by mass of silica fine particles (average particle size: 20 nm) Part, 80 parts by mass of methylene chloride, and 20 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution.

<Production of cellulose acetate film>
14.7 parts by mass of the retardation increasing agent solution was mixed with 470 parts by mass of the cellulose acetate solution, and the dope was prepared by sufficiently stirring. The mass ratio of the retardation increasing agent to cellulose acetate was 3.5%.
After the film having a residual solvent amount of 35% by mass was peeled from the band, it was stretched at a temperature of 140 ° C. using a film tenter at a stretching ratio of 38%, and then the clip was removed and the film was dried at 130 ° C. for 45 seconds. To produce a cellulose acetate film (second optically anisotropic layer). The produced cellulose acetate film had a residual solvent amount of 0.2% by mass and a film thickness of 92 μm.

<Measurement of optical properties of cellulose acetate film>
About the produced said cellulose acetate film, Re value and Rth value in wavelength 450nm, 550nm, and 630nm light were measured using the automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd. product). The results are shown in Tables 2 and 3.

<Saponification treatment of cellulose acetate film>
Only one side of the cellulose acetate film was saponified in the same manner as in Example 1 except that the cellulose acetate film prepared in Comparative Example 1 was employed.

<Formation of alignment film>
An alignment film was formed on one side (saponified surface) of the cellulose acetate film in the same manner as in Example 1 except that the cellulose acetate film prepared in this Comparative Example 1 was adopted. A rubbing treatment was performed.

<Formation of first optically anisotropic layer>
Except for employing the cellulose acetate film prepared in Comparative Example 1, the same procedure as in Example 1 was carried out using the first optical film on the cellulose acetate film (second optically anisotropic layer) through the alignment film. An isotropic layer was formed to produce the optical compensation film of Comparative Example 1.

<Measurement of optical characteristics of first optical anisotropic layer>
Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments), the Re value of the first optically anisotropic layer was measured at wavelengths of 450 nm, 550 nm, and 630 nm. The measurement results are shown in Table 1.

<Production of elliptically polarizing plate>
A polarizing film was prepared and an elliptically polarizing plate was prepared in the same manner as in Example 1 except that the optical compensation film prepared in Comparative Example 1 was used.

<Preparation of multi-gap bend alignment liquid crystal cell>
In the same manner as in Example 1, the interval between each color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing it was set, and a bend alignment liquid crystal cell was manufactured. Table 4 shows the distance between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device was produced in the same manner as in Example 1.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

(Comparative Example 2)
<Production of cellulose acetate film>
A cellulose acetate film was produced in the same manner as in Example 1.

<Saponification treatment of cellulose acetate film>
In the same manner as in Example 1, only one surface of the cellulose acetate film was saponified.

<Formation of alignment film>
In the same manner as in Example 1, an alignment film was formed on one surface (saponified surface) of the cellulose acetate film, and the alignment film was rubbed.

<Formation of first optically anisotropic layer>
In the same manner as in Example 1, the first optical anisotropic layer was formed on the cellulose acetate film (second optical anisotropic layer) through the alignment film, and the optical compensation film of Comparative Example 2 was produced. did.

<Production of elliptically polarizing plate>
A polarizing film was prepared and an elliptically polarizing plate was prepared in the same manner as in Example 1 except that the optical compensation film prepared in Comparative Example 2 was used.

<Preparation of multi-gap bend alignment liquid crystal cell>
A green pixel, a blue pixel, and a red pixel, and a counter electrode opposed to each color pixel so that the distance between the color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing them is approximately the same size. The bend alignment liquid crystal cell was prepared. Table 4 shows the value of the interval between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device was produced in the same manner as in Example 1.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

(Comparative Example 3)
<Production of cellulose acetate film>
A cellulose acetate film was produced in the same manner as in Example 1.

<Saponification treatment of cellulose acetate film>
In the same manner as in Example 1, only one surface of the cellulose acetate film was saponified.

<Formation of alignment film>
In the same manner as in Example 1, an alignment film was formed on one surface (saponified surface) of the cellulose acetate film, and the alignment film was rubbed.

<Formation of first optically anisotropic layer>
In the same manner as in Example 1, the first optical anisotropic layer was formed on the cellulose acetate film (second optical anisotropic layer) through the alignment film. A compensation film was prepared.

<Production of elliptically polarizing plate>
A polarizing film was prepared and an elliptically polarizing plate was prepared in the same manner as in Example 1 except that the optical compensation film prepared in Comparative Example 3 was used.

<Preparation of multi-gap bend alignment liquid crystal cell>
The green pixel, the blue pixel, and the red pixel are similar to the comparative example 2 except that the interval between the color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing them is different from that of the comparative example 2. A bend alignment liquid crystal cell was fabricated by setting the interval between each color pixel of the red pixel and the counter electrode facing it. Table 4 shows the value of the interval between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device was produced in the same manner as in Example 1.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

(Comparative Example 4)
<Production of first optical compensation film>
In the same manner as in Example 1, a first optical compensation film was produced.

<Production of second optical compensation film>
<Production of Cellulose Acetate Film (Third Optical Anisotropic Layer)>
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose triacetate (triacetyl cellulose: TAC) solution.

[Material / solvent composition]
・ Cellulose acetate (Substitution degree: 2.81 Acetylation degree: 60.2%) ・ ・ ・ 100 parts by mass ・ Triphenyl phosphate (plasticizer) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 6 .5 parts by mass-biphenyl diphenyl phosphate (plasticizer) ... 5.2 parts by mass-methylene chloride (first solvent) ... ... 630 parts by mass, methanol (second solvent) ... 95 parts by mass
-Retardation increasing agent shown in structural formula (A) ... 3 parts by mass

  The obtained dope was cast using a casting machine having a band having a width of 2 m and a length of 65 m. After the film surface temperature on the band reached 40 ° C., the film was dried for 1 minute, peeled off, and further dried with 135 ° C. drying air for 20 minutes to produce a film. Thereafter, this film was uniaxially stretched to 120% under a temperature condition of 190 ° C. to prepare a cellulose acetate film (third optically anisotropic layer). In addition, Tg of the used cellulose acetate is 148 degreeC.

<Measurement of optical characteristics>
About the produced cellulose acetate film (third optically anisotropic layer), an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments) was used in the same manner as the “second optically anisotropic layer”. Was used to measure Re and Rth values at wavelengths of 450 nm, 550 nm, and 630 nm. The measurement results are shown in Tables 2 and 3.

<Saponification treatment of cellulose acetate film>
On one side (band side) of the produced cellulose acetate film, a 1.0 N potassium hydroxide solution (solvent: water / isopropyl alcohol / propylene glycol = 69.2 parts by mass / 15 parts by mass / 15.8 parts by mass). Part) was applied at 10 mL / m ² and kept at a temperature of about 40 ° C. for 30 seconds, and then the alkaline liquid was scraped off, washed with pure water, and water droplets were removed with an air knife. Then, it dried at 100 degreeC for 15 second. The contact angle with respect to pure water of the treated surface of this support was determined to be 42 °.

<Formation of alignment film>
On one surface (saponified surface) of the cellulose acetate film, an alignment film coating solution having the following composition was applied at 28 mL / m ² with a # 16 wire bar coater, heated at 60 ° C. for 60 seconds, and further 90 The film was dried for 150 seconds with warm air at 0 ° C. to form an alignment film. The alignment film thickness after drying was 1.1 μm. Further, the surface roughness of the alignment film was measured with an atomic force microscope (AFM: Atomic Force Microscope, SPI3800N, manufactured by Seiko Instruments Inc.), and found to be 1.147 nm.

[Alignment film coating solution composition]
・ Modified polyvinyl alcohol shown in structural formula (B) ... 10 parts by mass, water ... ········· 371 parts by mass · Methanol ··································································· (Crosslinking agent) ... 0.5 parts by mass
・ Citrate ester (AS3, Sankyo Chemical Co., Ltd.) 0.35 parts by mass

<Preparation of Fourth Optically Anisotropic Layer (Horizontal Alignment Discotic Liquid Crystal Layer)>
On the alignment film, a coating liquid containing a discotic liquid crystal having the following composition is conveyed at 20 m / min by rotating a wire bar of # 2.4 in 391 rotations in the same direction as the conveying direction of the cellulose acetate film. The cellulose acetate film was continuously applied to the alignment film surface.

[Coating liquid composition of discotic liquid crystal layer]
-Discotic liquid crystalline compound represented by structural formula (C) ... 32.6 parts by mass-Compound represented by structural formula (D) below (addition for orienting the disk surface within 5 degrees) Agent) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 0.1 parts by mass ・ Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 3.2 parts by mass / sensitizer (Kayacure DETX, Japan) Kayaku Co., Ltd.) ······ 0.4 parts by mass · Photopolymerization initiator (Irgacure 907, Ciba Geigy Corp.) ··· 1.1 parts by mass
・ Methyl ethyl ketone ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 62.0 parts by mass

In the step of continuously heating from room temperature to 100 ° C., the solvent is dried, and thereafter, the film surface wind speed of the discotic liquid crystal compound layer is about 90 m so as to be 2.5 m / sec in the 130 ° C. drying zone. The discotic liquid crystal compound was aligned by heating for 2 seconds. Next, with the surface temperature of the film being about 130 ° C., an ultraviolet irradiation device (ultraviolet lamp: output 120 W / cm) is irradiated with ultraviolet rays for 4 seconds to advance the crosslinking reaction, and the discotic liquid crystal compound is aligned. Fixed to. Then, it was allowed to cool to room temperature and wound into a cylindrical shape to form a roll. In this way, a roll-shaped optical compensation film was produced.
The angle between the disc surface of the discotic liquid crystal compound and the film surface of the support was 0 degree.

<Measurement of optical characteristics of fourth optical anisotropic layer>
Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments), the Re and Rth values of the fourth optical anisotropic layer at the wavelengths of 450 nm, 550 nm, and 630 nm It measured similarly to the anisotropic layer. The measurement results are shown in Tables 2 and 3.

<Production of elliptically polarizing plate>
In the same manner as in Example 1, except that a polarizing film was prepared and the first optical compensation film and the second optical compensation film were attached to both surfaces of the polarizing film, respectively. The elliptically polarizing plate of this comparative example 4 was created.

<Production of bend alignment liquid crystal cell>
In the same manner as in Example 1, the interval between each color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing it was set, and a bend alignment liquid crystal cell was manufactured. Table 4 shows the distance between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
A liquid crystal display device of Comparative Example 4 was produced in the same manner as Example 1.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

(Comparative Example 5)
<Preparation of optical compensation film and elliptically polarizing plate>
In the same manner as in Comparative Example 4, a first optical compensation film and a second optical compensation film were produced. Using the two optical compensation films and a polarizing film produced in the same manner as in Example 1, An elliptically polarizing plate was created.

<Production of bend alignment liquid crystal cell>
In the same manner as in Example 1, the interval between each color pixel of the green pixel, the blue pixel, and the red pixel and the counter electrode facing it was set, and a bend alignment liquid crystal cell was manufactured. Table 4 shows the distance between each set pixel and the counter electrode facing it.

<Production of liquid crystal display device>
<< Production of Liquid Crystal Display >>
In the same manner as in Example 1, a liquid crystal display device of Comparative Example 5 was produced.

<< Measurement of color >>
The produced liquid crystal display device was placed on a backlight, and a voltage was applied to the bend alignment liquid crystal cell with a 55 Hz rectangular wave. A luminance meter (BM-5 manufactured by TOPCON) was used while adjusting the voltage, and the voltage with the smallest black luminance (front luminance) was defined as the black voltage.
Using a luminance meter (TOPCON BM-5), an angle tilted 60 ° clockwise from the normal direction of the liquid crystal cell in the direction perpendicular to the rubbing direction (liquid crystal alignment direction) of the alignment film when displaying black, left The angle tilted by 60 ° around each and the hue u′v ′ of each were measured. The results are shown in Table 5.

  As shown in Tables 1 to 5, Examples 1 to 7 have smaller Δu′v ′ and closer to the neutral color than Comparative Examples 1 to 5, and therefore, in the vertical alignment mode and the bend alignment mode. Providing a liquid crystal display device that exhibits a good color with a polarizing plate having a single optical compensation film in order to optically compensate the liquid crystal cell and reduce the cost without increasing the thickness of the polarizing plate. can do. In addition, the correlation diagram with Re and Rth in the optical compensation films of Examples 1 to 3 and Example 7 is shown as one-dot chain lines in FIG.

  Since the liquid crystal display device of the present invention optically compensates for the liquid crystal cell and exhibits a good color, it can be suitably used for mobile phones, personal computer monitors, televisions, liquid crystal projectors, and the like.

FIG. 1 is a cross-sectional view schematically showing the alignment of the liquid crystal compound in the bend alignment liquid crystal cell. FIG. 2 is a schematic diagram showing a polarizing plate. FIG. 3 is a schematic view showing a bend alignment type liquid crystal display device of the present invention. FIG. 4 is a correlation diagram between the electrode spacing in the optical compensation film and Re and Rth. FIG. 5 is a cross-sectional view showing the configuration of the liquid crystal cell. FIG. 6 is a cross-sectional view showing the configuration of the liquid crystal cell. FIG. 7 is a conceptual diagram showing an evaluation model for color measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal cell 10a Liquid crystal layer 11 Liquid crystalline compound 11a-11j Rod-like liquid crystalline molecule | numerator 12a, 12b Alignment film | membrane 13a, 13b Electrode layer 14a Upper substrate 14b Lower substrate 20 Light diffusion film 21 Transparent base film 30 Light diffusion layers 31, 31A, 31B First optically anisotropic layers 31a to 31e Discotic compound 32 Alignment films 33, 33A, 33B Second optically anisotropic layers 34, 34A, 34B Polarizing film 41 First transmissive fine particles 42 Second transmission Fine particles 44 Translucent resin 51 Color pixel 51R Color pixel (red)
51G color pixel (green)
51B color pixel (blue)
52 Counter electrode 53 Alignment film 54 Pixel electrode 55 Alignment film 60 Spacer NL Disc surface normal plane PL Normal direction of disc plane normal projection onto second optical anisotropic layer surface RD Rubbing direction SA In plane Slow axis TA In-plane transmission axis BL Backlight BM Black matrix

Claims (7)

One substrate on which pixel electrodes are disposed corresponding to a plurality of color pixels, another substrate on which counter electrodes are disposed to face the pixel electrodes, the one substrate, and the other substrates, A liquid crystal cell constituted by a liquid crystal layer sandwiched between,
A polarizing film and one optical compensation film having an optically anisotropic layer, wherein the one substrate and the other substrate are arranged so that the optical compensation film faces the one substrate and the other substrate. A polarizing plate installed on each of the substrates, and a liquid crystal display device comprising:
In the liquid crystal cell, an interval between the pixel electrode and the counter electrode facing the pixel electrode is different for each color pixel corresponding to the pixel electrode,
In-plane retardations Re ₍₄₅₀₎ , Re ₍₅₅₀₎ , and Re ₍₆₃₀₎ with respect to light having wavelengths of 450 nm, 550 nm, and 630 nm in the optically anisotropic layer, and retardation Rth ₍ thickness direction _{) 450)} , Rth ₍₅₅₀₎ , and Rth ₍₆₃₀₎ satisfy the following formulas (1) to (4).
Re ₍₄₅₀₎ / Re ₍₅₅₀₎ <1 ... Formula (1)
Re ₍₆₃₀₎ / Re ₍₅₅₀₎ > 1 ..... Formula (2)
Rth ₍₄₅₀₎ / Rth ₍₅₅₀₎ <1 Equation (3)
Rth ₍₆₃₀₎ / Rth ₍₅₅₀₎ > 1 formula (4)
In the above formulas (1) to (4), Re and Rth are defined as the refractive index in the slow axis direction (direction in which the refractive index becomes maximum) in the plane of the optically anisotropic layer is nx, and the optical The refractive index in the fast axis direction (direction in which the refractive index is minimum) in the plane of the anisotropic layer is ny, the refractive index in the thickness direction of the optical anisotropic layer is nz, and the optical anisotropic layer Is the value represented by Re = (nx−ny) × d, and Rth = {(nx + ny) / 2−nz} × d.   The color pixel has a red pixel, a green pixel, and a blue pixel, and an interval between a pixel electrode corresponding to the blue pixel and a counter electrode facing the pixel electrode is opposed to the pixel electrode corresponding to the red pixel. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is smaller than a distance between the counter electrode and a distance between the pixel electrode corresponding to the green pixel and the counter electrode facing the pixel electrode.   The distance between the pixel electrode corresponding to the green pixel and the counter electrode facing the pixel electrode is smaller than the distance between the pixel electrode corresponding to the red pixel and the counter electrode facing the pixel electrode. Liquid crystal display device.   There is a difference between a distance between a pixel electrode corresponding to one color pixel and a counter electrode facing the pixel electrode, and a distance between a pixel electrode corresponding to another color pixel adjacent to the one color pixel and the counter electrode facing the pixel electrode. The liquid crystal display device according to claim 1, which has a thickness of 0.3 to 1.0 μm.   The liquid crystal display device according to claim 1, wherein the liquid crystal molecules contained in the liquid crystal layer are bend aligned or vertically aligned.   The liquid crystal display device according to claim 1, wherein the optically anisotropic layer is a cellulose acetate film. The liquid crystal display device according to claim 1, further comprising another optically anisotropic layer, wherein the other optically anisotropic layer contains a discotic compound.