WO2009123114A1 - Liquid crystal display device - Google Patents

Abstract

A liquid crystal cell (1), a backlight device (2), a first light diffusion layer (3), a first polarizing plate (4), and a second light diffusion layer (5) are provided. The first light diffusion layer (3) has a light diffusion plate (31) and a prism sheet (32), and a luminous intensity distribution characteristic thereof is such that a brightness value in the 70°direction with respect to the normal line on a plane of light incidence of the liquid crystal cell is no more than 20% of the brightness value in the normal direction and that emitted light from the first light diffusion layer (3) contains non-parallel light. The second light diffusion layer (5) comprises a second polarizing plate (51) and a glare-proof layer (52). A light diffusion characteristic of the layer (52) is such that a light emission angle of laser light emitted from the glare-proof layer (52) having relative intensity of 0.0008% for intensity of laser light with a wavelength of 549 nm incident from the normal direction on the rear surface of the layer (52) is 40°or larger with respect to the normal direction on the rear surface of the layer (52).

Description

Liquid crystal display

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having excellent viewing angle characteristics.

In recent years, liquid crystal display devices have been widely used from portable small electronic devices such as mobile phones and PDAs (Personal Digital Assistants) to large electric devices such as personal computers and televisions, and their applications are expanding. Yes.

Unlike a self-luminous display device such as a CRT or PDP (plasma display panel), a liquid crystal display device does not emit light. For this reason, in a transmissive liquid crystal display device, a backlight device is provided on the back side of the liquid crystal display element, and the liquid crystal display element controls the transmitted light amount of illumination light from the backlight device for each pixel. An image is displayed.

There are various types of liquid crystal display devices such as TN (Twisted Nematic), STN (Super Twisted Nematic), VA (Vertical Alignmen), and IPS (In-plane Switching). A narrow viewing angle direction (azimuth angle) exists due to light leakage due to the liquid crystal molecules having a retardation value, a shift of the axial angle of the polarizing plate when it is oblique, and the like.

Therefore, as a method of expanding the viewing angle, a method of optical compensation to a liquid crystal cell or a polarizing plate using a retardation plate is widely adopted (see, for example, Patent Document 1 and Patent Document 2).
JP-A-4-29828 Japanese Unexamined Patent Publication No. H4-258923

An object of the present invention is to provide a liquid crystal display device capable of realizing a display with a wide viewing angle and high color reproducibility.

Another object of the present invention is to provide a liquid crystal display device capable of expanding the viewing angle without using a retardation plate, that is, without increasing the number of components.

A liquid crystal display device according to the present invention includes a liquid crystal cell in which a liquid crystal layer is provided between a pair of substrates, a backlight device provided on the back side of the liquid crystal cell, and the backlight device and the liquid crystal cell. A first light diffusion layer, a first polarizing plate disposed between the first light diffusion layer and the liquid crystal cell, and a second light diffusion layer disposed on the front side of the liquid crystal cell. The first light diffusion layer has both or both of a light diffusion function and a light deflection function. The light emitted from the first light diffusion layer has (i) a luminance value in the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell, that is, the luminance in the normal direction of the light incident surface of the liquid crystal cell. And (ii) includes non-parallel light. The second light diffusion layer is composed of a second polarizing plate and an antiglare layer provided on the front side of the second polarizing plate. The light diffusing characteristic of the antiglare layer is that the laser emitted from the antiglare layer has a relative intensity of 0.0008% with respect to the intensity of the laser light having a wavelength of 549 nm incident from the normal direction of the back surface of the antiglare layer. The light emission angle of light with respect to the normal direction of the back surface of the antiglare layer is 40 ° or more. In the present specification, the side to be the display screen of the liquid crystal display device is referred to as “front side”, and the opposite side is referred to as “back side”.

Here, the first light diffusion layer may have both a light diffusion function and a light deflection function.

The first light diffusion layer includes a light diffusion plate that performs the light diffusion function and a light deflection structure plate that performs the light deflection function, and the light deflection structure plate is disposed on the front side of the light diffusion plate. The provided structure may be sufficient.

The liquid crystal cell is preferably a TN liquid crystal, IPS liquid crystal, or VA liquid crystal.

Further, from the viewpoint of further improving viewing angle characteristics and color reproducibility, it is preferable to further dispose a retardation plate on the back side and / or front side of the liquid crystal cell.

On the other hand, the retardation plate may not be provided from the viewpoint of reducing the number of parts, improving the assembly of the apparatus and increasing the productivity.

Further, the liquid crystal cell may be a TN liquid crystal and may not include a retardation plate.

As the light emitted from the first light diffusion layer, the light emitted from a circle having a diameter of 1 cm on the emission surface of the first light diffusion layer is parallel to the emission surface, which is 1 m away from the normal direction of the emission surface. When the projection image on a flat plane is observed, it is preferably light having an emission characteristic such that the minimum half-value width of the in-plane luminance distribution of the projection image is 30 cm or more.

In the liquid crystal display device of the present invention, a wide viewing angle, high display quality, and excellent color reproducibility can be obtained. Further, viewing angle characteristics that do not hinder actual use can be obtained without using a retardation plate.

It is a schematic diagram which shows an example of the liquid crystal display device which concerns on this invention. It is a schematic diagram which shows an example of a 1st light-diffusion layer. It is an outline figure showing other examples of the 1st light diffusion layer. It is an example of the method of measuring the luminance value in the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell for the first diffusion layer. It is a figure explaining the definition of non-parallel light. It is a schematic diagram which shows the structural example of a 2nd light-diffusion layer. It is the figure which represented typically the incident direction and emitting direction of the laser beam in a 2nd light-diffusion layer. It is an example of the graph which plotted the relative intensity | strength of the laser beam radiate | emitted from a 2nd light-diffusion layer with respect to the outgoing angle. It is a schematic diagram which shows the other example of the liquid crystal display device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal cell 2 Backlight apparatus 3 1st light-diffusion layer 4 1st polarizing plate 5 2nd light-diffusion layer 6 Phase difference plate 31 Light-diffusion plate 32 Prism sheet (light-deflection structure board)
51 Second polarizing plate 52 Antiglare layer 522 Filler

Hereinafter, the liquid crystal display device according to the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

FIG. 1 is a schematic diagram showing an embodiment of a liquid crystal display device according to the present invention. The liquid crystal display device of FIG. 1 is a normally white mode TN liquid crystal display device, and includes a liquid crystal cell 1 in which a liquid crystal layer 12 is provided between a pair of transparent substrates 11a and 11b, and a back surface of the liquid crystal cell 1. A direct-type backlight device 2 provided with a plurality of cold-cathode tubes 21 provided in parallel at predetermined intervals is provided. A first light diffusion layer 3 and a first polarizing plate 4 are disposed between the backlight device 2 and the liquid crystal cell 1 in this order from the backlight device side, and a second light diffusion layer 5 is disposed on the front side surface of the liquid crystal cell 1. Is arranged. The first light diffusing layer 3 includes a light diffusing plate 31 having a light diffusing function, and a prism sheet (light deflecting structure plate) 32 having a light deflecting function provided on the front side surface of the light diffusing plate 31. . The second light diffusion layer 5 includes a second polarizing plate 51 and an antiglare layer 52 provided on the front side surface of the second polarizing plate 51.

In the liquid crystal display device having such a configuration, the light emitted from the backlight device 2 is diffused by the light diffusion plate 31 of the first light diffusion layer 3, and then the light incident surface of the liquid crystal cell 1 by the prism sheet 32. Predetermined directivity with respect to the normal direction is given. The directivity with respect to the normal direction is set to be lower than that of the conventional apparatus. The light imparted with a predetermined directivity is changed from circularly polarized light to linearly polarized light by the first polarizing plate 4 and enters the liquid crystal cell 1. The light incident on the liquid crystal cell 1 is emitted from the liquid crystal cell 1 with its polarization plane controlled for each pixel by the orientation of the liquid crystal layer 12 controlled by the electric field. The light emitted from the liquid crystal cell 1 is imaged and diffused by the second light diffusion layer 5.

Thus, in the liquid crystal display device of the present invention, the directivity in the normal direction of the light incident on the liquid crystal cell 1 in the first light diffusion layer 3 is made lower than that in the conventional case, that is, the incident light on the liquid crystal cell 1. The light emitted from the liquid crystal cell 1 is further diffused by the second light diffusion layer 5. As a result, a wide viewing angle and excellent color reproducibility can be obtained as compared with the conventional apparatus.

Hereinafter, each member of the liquid crystal display device of the present invention will be described. First, in the liquid crystal cell 1 used in the present invention, a liquid crystal is sealed between a pair of transparent substrates 11a and 11b arranged to face each other at a predetermined distance by a spacer (not shown), and the pair of transparent substrates 11a and 11b. The liquid crystal layer 12 is provided. Although not shown in the figure, a transparent electrode and an alignment film are laminated on each of the pair of transparent substrates 11a and 11b, and the liquid crystal is formed by applying a voltage based on display data between the transparent electrodes. Orient. Here, the display method of the liquid crystal cell 1 is the TN method, but a display method such as an IPS method or a VA method may be adopted.

The backlight device 2 used in the present invention is not limited to the direct type shown in FIG. 1, but is a side-ride type in which a linear light source or a point light source is arranged on the side surface of the light guide plate, or a light source itself. Conventionally known ones such as a planar light source type can be used.

The first light diffusion layer 3 includes a light diffusion plate 31 and a prism sheet 32. Specifically, as shown in FIG. 2, the first light diffusion layer 3 has a configuration in which a prism sheet 32 is provided on the front side of the light diffusion plate 31. As the base material 311 of the light diffusion plate 31, polycarbonate, methacrylic resin, methyl methacrylate-styrene copolymer resin, acrylonitrile-styrene copolymer resin, methacrylic acid-styrene copolymer resin, polystyrene, polyvinyl chloride, polypropylene Polyolefins such as polymethylpentene, cyclic polyolefins, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamide resins, polyarylate, polyimide, and the like can be used. Further, the diffusing agent 312 mixed and dispersed in the base material 311 is fine particles made of a substance having a refractive index different from that of the material to be the base material 311, and specific examples include acrylic resin of a type different from the base material, Organic fine particles such as melamine resin, polyethylene, polystyrene, organic silicone resin, acrylic-styrene copolymer, and inorganic fine particles such as calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, glass, etc. One or more of these are mixed and used. Organic polymer balloons and glass hollow beads can also be used as the diffusing agent 312. The average particle diameter of the diffusing agent 312 is preferably in the range of 0.5 μm to 30 μm. Further, the shape of the diffusing agent 312 may be not only spherical but also flat, plate-shaped, and needle-shaped.

On the other hand, the prism sheet 32 has a flat light incident surface, and the light output surface is a prism surface formed by arranging V-shaped linear grooves in parallel. Examples of the material of the prism sheet 32 include polycarbonate resin, ABS resin, methacrylic resin, methyl methacrylate-styrene copolymer resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyolefin resin such as polyethylene and polypropylene. It is done. As a manufacturing method of the prism sheet 32, a normal thermoplastic resin molding method can be used. For example, the prism sheet 32 may be manufactured by hot press molding using a mold. A light diffusing agent may be dispersed in the prism sheet 32. The thickness of the prism sheet 32 is usually 0.1 to 15 mm, preferably 0.5 to 10 mm.

The light diffusing plate 31 and the prism sheet 32 may be formed integrally, or may be formed separately and then joined. Moreover, when producing and joining as a different body, you may make it contact between the light-diffusion plate 31 and the prism sheet 32 via an air layer.

As a different embodiment of the first light diffusing layer 3, as shown in FIG. 3, a diffusing agent 312 is dispersed and mixed in a prism sheet 32 having a light deflecting function so as to have a light diffusing function. There may be.

The light distribution characteristic of light that has passed through the first light diffusion layer 3 is that the luminance value in the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell 1 is the front luminance value, that is, the light incident surface of the liquid crystal cell 1 The emission light from the first light diffusion layer includes non-parallel light.
A more preferable light distribution characteristic is to prevent light exceeding 60 ° from the normal line of the light incident surface of the liquid crystal cell 1. Normally, as shown in FIG. 1, the back surface of the first light diffusion layer 3 and the light incident surface of the liquid crystal cell 1 are arranged in parallel, so that it is 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell 1. The luminance value in the direction is, for example, as shown in FIG. 4 when the longitudinal direction of the first light diffusion layer 3 is the x direction and the plane parallel to the back surface of the first light diffusion layer 3 is the xy plane. The luminance value is in the direction of 70 ° with respect to the z axis, which is the normal to the xy plane, and preferably the luminance value in the direction in which the angle formed with the z axis on the xz plane is 70 °. In order to obtain such a light distribution characteristic, for example, the shape of the prism portion having a triangular cross section of the prism sheet 32 may be adjusted. The apex angle θ (shown in FIG. 2) of the prism portion having a triangular cross section is preferably in the range of 60 to 120 °, and the shape of the triangle may be any of the equal side and the unequal side. An isosceles triangle is preferable when concentrating in the line direction, and adjacent isosceles triangles are arranged sequentially adjacent to the base opposite to the apex angle so that the apex angle column becomes a major axis and is substantially parallel to each other. It is preferable to have a structure as described above. In this case, the apex angle and the base angle may have curvature unless the light collecting ability is significantly reduced. The distance d between the apex angles (shown in FIG. 2) is usually in the range of 10 μm to 500 μm, and preferably in the range of 30 μm to 200 μm. Here, as shown in FIG. 5, the non-parallel light means that light emitted from a circle having a diameter of 1 cm on the emission surface of the first light diffusion layer 3 is separated by 1 m in the normal direction of the emission surface. When observed as a projection image on an observation surface parallel to the emission surface, the light has emission characteristics such that the minimum half-value width of the in-plane luminance distribution of the projection image is 30 cm or more.

As the first polarizing plate 4 used in the present invention, one obtained by bonding a support film on both sides of a polarizer is usually used. As the polarizer, for example, a dichroic dye or iodine is adsorbed and oriented on a polarizer substrate such as a polyvinyl alcohol resin, polyvinyl acetate resin, ethylene / vinyl acetate (EVA) resin, polyamide resin, or polyester resin. And a polyvinyl alcohol / polyvinylene copolymer containing a molecular chain oriented with a dichroic dehydrated product of polyvinyl alcohol (polyvinylene) in a molecularly oriented polyvinyl alcohol film. In particular, a polarizer substrate made of polyvinyl alcohol resin obtained by adsorbing and orienting a dichroic dye or iodine is preferably used as the polarizer. The thickness of the polarizer is not particularly limited, but in general, it is preferably 100 μm or less, more preferably in the range of 10 to 50 μm, still more preferably in the range of 25 to 35 μm for the purpose of reducing the thickness of the polarizing plate.

As the support film for supporting and protecting the polarizer, a film made of a polymer having low birefringence, excellent transparency, mechanical strength, thermal stability, moisture shielding property and the like is preferable. Examples of such films include cellulose acetate resins such as TAC (triacetylcellulose), acrylic resins, fluorine resins such as tetrafluoroethylene / hexafluoropropylene copolymers, polycarbonate resins, and polyethylene. Polyester resin such as terephthalate, polyimide resin, polysulfone resin, polyethersulfone resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyolefin resin or polyamide resin, etc. are formed into a film. What was processed is mentioned. Among these, a triacetyl cellulose film or a norbornene-based thermoplastic resin film whose surface is saponified with an alkali or the like can be preferably used from the viewpoints of polarization characteristics and durability. The norbornene-based thermoplastic resin film is particularly suitable because the film becomes a good barrier from heat and wet heat, so that the durability of the polarizing plate 4 is greatly improved and the dimensional stability is greatly improved because of its low moisture absorption rate. Can be used for For forming into a film, conventionally known methods such as a casting method, a calendar method, and an extrusion method can be used. The thickness of the support film is not limited, but is usually preferably 500 μm or less, more preferably in the range of 5 to 300 μm, and still more preferably in the range of 5 to 150 μm, from the viewpoint of reducing the thickness of the polarizing plate 4.

The second light diffusion layer 5 includes a second polarizing plate 51 and an antiglare layer 52 provided on the front side surface of the second polarizing plate 51. The second polarizing plate 51 used here is a pair with the first polarizing plate 4 disposed on the back side of the liquid crystal cell 1, and the one exemplified by the first polarizing plate 4 is also suitable here. Can be used. However, the second deflection plate 51 is arranged so that its deflection surface is orthogonal to the deflection surface of the first polarizing plate 4. When the liquid crystal display device is normally black, the first polarizing plate and the second polarizing plate may be installed so as to be parallel to each other.

FIG. 6 shows a schematic diagram of the second light diffusion layer 5. The second light diffusion layer 5 in FIG. 6A is arranged in the liquid crystal display device in FIG. 1, and a resin solution 521 in which minute fillers 522 are dispersed is placed on the second polarizing plate 51. Coating is performed, and the coating film thickness is adjusted so that the filler 522 appears on the surface of the coating film, and fine irregularities are formed on the surface of the substrate. In this case, the dispersion of the filler 522 is preferably isotropic dispersion.

FIG. 6B shows a case where fine irregularities are formed on the surface of the base film 523 as the antiglare layer 52 without using a filler. In order to form fine irregularities on the surface of the base film 523, a method of surface-treating the base film 523 by sandblasting, embossing or the like, or a mold or embossing roll having a mold surface with the irregularities reversed. And a method of forming fine irregularities in the production process of the base film may be used. When the base film 523 as the antiglare layer 52 is produced, the base film 523 and the second polarizing plate 51 are bonded to form the second light diffusion layer 5. It is preferable that the base film 523 and the second polarizing plate 51 are directly brought into contact with each other without using an adhesive layer.

The antiglare layer 52 has a structure in which, for example, as shown in FIGS. 6C, 6 </ b> D, and 6 </ b> E, the filler 522 is dispersed and mixed in the base film 523 and is formed on the surface of the base film 523. A structure in which fine irregularities are formed may be used. The antiglare layer 52 in FIG. 6C is formed by forming fine irregularities on the surface of the base film 523 in which the filler 522 is dispersed and mixed by sandblasting or the like. The anti-glare layer 52 in FIG. 6D is obtained by bonding a base film 523b having fine irregularities formed on the surface to a base film 523a in which a filler 522 is dispersed and mixed. The anti-glare layer 52 in FIG. 6 (e) is obtained by bonding a base film 523b, in which filler 522 is dispersed and mixed, and fine irregularities are formed on the surface thereof, to the base film 523a. As the second polarizing plate 51, a film in which a support film is bonded to both sides of a polarizer is usually used. Therefore, a support film for a polarizer is used as the base film 523a in FIG. It doesn't matter if you do. The surface of the antiglare layer 52 usually has fine irregularities, but there may be no fine irregularities. That is, the antiglare layer 52 may be light diffusion only by internal diffusion (internal haze), light diffusion by both internal diffusion (internal haze) and surface diffusion (external haze / unevenness), or surface diffusion ( Light diffusion only by external haze and unevenness may be used.

The antiglare layer 52 having such a structure has a light diffusion property of 0.0008% relative to the intensity of laser light having a wavelength of 549 nm incident from the normal direction of the back surface of the antiglare layer 52. The light emission angle of the laser light emitted from the antiglare layer 52 with respect to the normal direction of the back surface of the antiglare layer 52 (hereinafter sometimes referred to as the light emission angle of the antiglare layer) is 40 ° or more. This is very important. Thereby, the light transmitted from the liquid crystal cell 1 to the front side is scattered forward, and the viewing angle is suppressed while coloring of the image viewed from an oblique direction is suppressed while maintaining the sharpness of the image of the transmitted light in the front direction. Becomes wider. In order to control the light diffusion characteristics of the antiglare layer 52 in this way, for example, when the filler 522 is dispersed and mixed, the shape, particle size, and addition amount of the filler 522, and the base material of the filler 522 and the antiglare layer A difference in refractive index with the film 523 may be adjusted. In the case where the filler 522 is not used, the material of the antiglare layer 52 and the shape of the surface irregularities may be adjusted. Usually, the light emission surface of the liquid crystal cell 1 and the back surface of the antiglare layer are arranged in parallel.

Examples of the base film 523 of the antiglare layer 52 include cellulose acetate resins such as TAC (triacetyl cellulose), acrylic resins, polycarbonate resins, polyester resins such as polyethylene terephthalate, and the like. The filler 522 is a fine particle made of a material having a refractive index different from that of the base film 523, for example, an organic fine particle such as an acrylic resin, a melamine resin, polyethylene, polystyrene, an organic silicone resin, an acrylic-styrene copolymer, and the like. Examples thereof include inorganic fine particles such as calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, and glass, and one or more of these are used in combination. Organic polymer balloons and glass hollow beads can also be used. The average particle diameter of the filler 522 is preferably in the range of 1 μm to 25 μm. The filler 522 may have any shape such as a spherical shape, a flat shape, a plate shape, or a needle shape, but a spherical shape is particularly desirable.

Hereinafter, a method for measuring the relative intensity of the laser light emitted from the antiglare layer 52 when the laser light is incident from the normal direction of the back surface of the antiglare layer 52 will be described. The “normal direction of the back surface of the antiglare layer 52” refers to the normal direction to the flat back surface of the antiglare layer 52, and the antiglare layer 52 is as shown in FIGS. 6B to 6E. In the case where the base films 523, 523a, and 523b are included, the direction overlaps with the normal line of the base film 523.

FIG. 7 schematically shows the incident direction and the emission direction of the laser beam when the laser beam is incident from the normal direction of the back surface of the anti-glare layer 52 and the relative intensity of the laser beam emitted from the anti-glare layer is measured. It is the perspective view shown in. In FIG. 7, with respect to the laser beam 93 incident in the normal direction 92 from the back side of the anti-glare layer 91 (below the anti-glare layer 91), the laser beam emitted from the normal direction 92 in the direction of angle θ. Measure the strength of 94. The relative intensity is obtained by dividing the measured intensity at each angle by the intensity of the incident laser beam. The emitted light 94, the normal direction 92, and the light 93 incident from the back side of the antiglare layer 52 are all measured so as to be on the same plane (plane 95 in FIG. 7).

Next, by plotting the relative intensity measured in this manner against the angle, the light emission angle at which the relative intensity with respect to the intensity of the light incident from the normal direction 92 becomes 0.0008% is obtained. FIG. 8 is an example of a graph in which the relative intensity of laser light emitted from the antiglare layer 52 is plotted against the light emission angle. As shown in this graph, the relative intensity has a peak in the light emission angle of 0 °, that is, the normal direction 92 on the back surface of the antiglare layer 52, and the relative intensity tends to decrease as the angle deviates from the normal direction 92. is there. In the example shown in FIG. 8, it is understood that the relative intensity is 0.0008% when the light emission angle is 46 °.

FIG. 9 shows another embodiment of the liquid crystal display device of the present invention. The liquid crystal display device of FIG. 9 is different from the liquid crystal display device of FIG. 1 in that a phase difference plate 6 is disposed between the first polarizing plate 4 and the liquid crystal cell 1. This phase difference plate 6 has a phase difference of almost zero in a direction perpendicular to the surface of the liquid crystal cell 1, has no optical effect from the front, and has a phase difference when viewed from an oblique direction. It is intended to compensate for the phase difference that occurs and occurs in the liquid crystal cell 1. As a result, a wider viewing angle can be obtained, and better display quality and color reproducibility can be obtained. The retardation film 6 can be disposed between the first polarizing plate 4 and the liquid crystal cell 1 and at one or both of the second light diffusion layer 5 and the liquid crystal cell 1.

As the phase difference plate 6, for example, a polycarbonate resin or a cyclic olefin polymer resin is used as a film and the film is further biaxially stretched, or a liquid crystal monomer is fixed in a molecular arrangement by a photopolymerization reaction. Can be mentioned. Since the phase difference plate 6 optically compensates for the alignment of the liquid crystal, one having a refractive index characteristic opposite to that of the liquid crystal alignment is used. Specifically, for a TN mode liquid crystal display cell, for example, “WV film” (manufactured by Fuji Film), for an STN mode liquid crystal display cell, for example, “LC film” (manufactured by Nippon Oil Corporation), IPS mode For example, for a liquid crystal cell, a biaxial retardation film is used. For a VA mode liquid crystal cell, for example, a retardation plate combined with an A plate and a C-plate, a biaxial retardation film, a π cell mode liquid crystal cell is used. For example, “OCB WV film” (manufactured by Fuji Film Co., Ltd.) can be suitably used.

[Production Example of First Light Diffusing Layer] (1) Production of Light Diffusing Plate 74.5 parts by mass of styrene-methyl methacrylate copolymer resin (refractive index 1.57), crosslinked polymethyl methacrylate resin particles (refractive index) 1.49, weight average particle diameter 30 μm) 25 parts by mass, benzotriazole-based UV absorber (“SUMISOB 200” manufactured by Sumitomo Chemical Co., Ltd.) 0.5 parts by mass, hindered phenol-based antioxidant (thermal stabilizer) ) ("IRGANOX1010" manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.2 parts by mass was mixed with a Henschel mixer, melt-kneaded with a second extruder, and supplied to the feed block.
On the other hand, 99.5 parts by mass of a styrene resin (refractive index 1.59), 0.07 parts by mass of a benzotriazole-based ultraviolet absorber (“Sumisorb 200” manufactured by Sumitomo Chemical Co., Ltd.), a light stabilizer (Ciba Specialty) After mixing 0.13 parts by mass of “Chinuvin 770” manufactured by Chemicals Co., Ltd. with a Henschel mixer, crosslinked siloxane-based resin particles (“Trefill DY33-719” manufactured by Toray Dow Corning Silicone Co., Ltd., refractive index of 1.42, Together with a weight average particle diameter of 2 μm), the mixture was melt kneaded by a first extruder and supplied to a feed block. By adjusting the addition amount of the crosslinked siloxane-based resin particles, the total light transmittance Tt of the diffusion plate was adjusted, and a light diffusion plate having a total light transmittance Tt of 65% was produced.
In the light diffusing plate, the resin supplied from the first extruder to the feed block becomes an intermediate layer (base layer), and the resin supplied from the second extruder to the feed block becomes a surface layer (both sides). The laminate is made of three layers having a thickness of 2 mm (intermediate layer 1.90 mm, surface layer 0.05 mm × 2). The total light transmittance Tt was measured using a haze transmittance meter (HR-100 manufactured by Murakami Color Research Laboratory) in accordance with JIS K 7361.

(2) Production of prism sheet (light deflection structure plate) A styrene resin (refractive index 1.59) was press-molded to produce a 1 mm thick flat plate. Further, the styrene resin plate is re-press-molded using a metal mold in which V-shaped linear grooves having a cross section of an apex angle θ and a distance between apex angles of 50 μm are isosceles triangles are arranged in parallel. This produced a prism sheet. Note that the apex angle θ is the normal direction of the light incident surface of the liquid crystal cell in the light emitted from the first light diffusing layer when the first light diffusing layer is incorporated in the liquid crystal display device used in the examples described later. The brightness values in the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell were adjusted to 0%, 10%, and 20%, respectively.

(3) Production of Liquid Crystal Display Device Having First Light Diffusing Layer The light diffusing plate and the prism sheet were laminated as shown in FIG. 1 on the backlight of the liquid crystal display device used in Examples described later. In this case, the prism sheet was laminated so that the linear groove of the prism sheet and the cold cathode tube of the backlight were parallel to each other.

[Production Example 1 of Antiglare Layer for Second Light Diffusion Layer] (1) Production of Embossing Mold A surface of an iron roll having a diameter of 200 mm (STKM13A by JIS) was provided with copper ballad plating. Copper ballad plating consists of a copper plating layer / thin silver plating layer / surface copper plating layer, and the thickness of the entire plating layer was about 200 μm. The copper-plated surface is mirror-polished, and a blasting device (manufactured by Fuji Seisakusho) is used on the polished surface, and zirconia beads TZ-B125 (manufactured by Tosoh Corp., average particle diameter) are used as the first fine particles. : 125 μm) was blasted at a blast pressure of 0.05 MPa (gauge pressure, the same applies hereinafter) and a fine particle usage of 16 g / cm ² (a used amount per 1 cm ² of surface area of the roll, the same applies hereinafter) to form irregularities on the surface. A blasting device (manufactured by Fuji Seisakusho Co., Ltd.) was used on the uneven surface, and zirconia beads TZ-SX-17 (manufactured by Tosoh Corp., average particle size: 20 μm) were used as the second fine particles. The surface unevenness was finely adjusted by blasting at 1 MPa and a fine particle usage amount of 4 g / cm ² . The resulting copper-plated iron roll with unevenness was etched with a cupric chloride solution. The etching amount at that time was set to 3 μm. Thereafter, chromium plating was performed to produce a mold. At this time, the chromium plating thickness was set to 4 μm. The Vickers hardness of the chromium plating surface of the obtained mold was 1000. The Vickers hardness was measured according to JIS Z 2244 using an ultrasonic hardness tester MIC10 (manufactured by Krautkramer) (the measurement method for Vickers hardness is the same in the following examples).

(2) Preparation of an antiglare layer comprising a layer having fine irregularities and a base film Pentaerythritol triacrylate (60 parts by mass) and polyfunctional urethanized acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate, 0 (Part by mass) was mixed with an ethyl acetate solution and adjusted to a solid content concentration of 60% to obtain an ultraviolet curable resin composition. The refractive index of the cured product after removing ethyl acetate from the composition and curing with ultraviolet rays was 1.53.
Next, 40 parts by mass of polystyrene particles “XX-282K” (manufactured by Sekisui Plastics Co., Ltd., weight average particle diameter of 2.0 μm) as a filler with respect to 100 parts by mass of the solid content of the ultraviolet curable resin composition. 5 parts by weight of a photopolymerization initiator “Lucirin TPO” (manufactured by BASF, chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) was added so that the solid content was 50%. A coating solution was prepared by diluting with ethyl acetate.
This coating solution was applied onto a triacetyl cellulose (TAC) film (base film) having a thickness of 80 μm so that the coating thickness after drying was 12.6 μm, and 1 in a dryer set at 80 ° C. Let dry for minutes. The base film after drying was brought into close contact with the uneven surface of the mold produced in (1) by pressing with a rubber roll so that the ultraviolet curable resin composition layer was on the mold side. In this state, the ultraviolet ray curable resin composition layer is cured by irradiating light from a high-pressure mercury lamp having an intensity of 20 mW / cm ² from the base film side so that the amount of light in terms of h-line is 300 mJ / cm ^2. An antiglare layer having a structure shown in FIG. 6 (e), comprising a layer having an unevenness (thickness 12.6 μm) and a base film was obtained.

(3) Measurement of light diffusion characteristics of antiglare layer The base film of the antiglare layer obtained in (2) and a glass substrate are bonded together, and the method of the back surface of the base film on the glass surface side of the antiglare layer Laser with a predetermined angle of 0 ° to 90 ° from the normal direction with respect to light emitted from a layer having irregularities on the surface of the antiglare layer by irradiating parallel light from a 549 nm He—Ne laser from the direction of the line The light intensity was measured. The results are shown in FIG. From FIG. 8, the light emission angle at which the relative intensity with respect to the intensity of light incident from the normal direction is 0.0008% is 46 degrees.
For measurement, “3292 03 optical power sensor” and “3292 optical power meter” manufactured by Yokogawa Electric Corporation were used.

[Production Example 2 of Antiglare Layer for Second Light Diffusion Layer]
10 parts by weight of silicone-based particles “Tospearl 120” (Momentive Performance Materials Japan Godo Kaisha, Ltd., weight average particle diameter 2.0 μm) with respect to 100 parts by weight of the solid content of the ultraviolet curable resin composition, An antiglare layer was produced in the same manner as in Example 1 except that the thickness of the layer having irregularities on the surface was 8.4 μm. The light diffusion characteristics of the obtained antiglare layer were measured in the same manner as in [Production Example 1 of second light diffusion layer]. The results are summarized in Table 1.

[Production Example 3 of Antiglare Layer for Second Light Diffusion Layer]
35 parts by weight of silicone-based particles “Tospearl 145” (Momentive Performance Materials Japan Godo Kaisha, Ltd., weight average particle size 4.5 μm) with respect to 100 parts by weight of the solid content of the ultraviolet curable resin composition, An antiglare layer was produced in the same manner as in Example 1 except that the thickness of the layer having irregularities on the surface was 9.9 μm. The light diffusion characteristics of the obtained antiglare layer were measured in the same manner as in [Production Example 1 of second light diffusion layer]. The results are summarized in Table 1.

＊１：紫外線硬化性樹脂組成物の固形分１００質量部に対する使用量（質量部）

* 1: Use amount (parts by mass) with respect to 100 parts by mass of the solid content of the ultraviolet curable resin composition.

Example 1
As a liquid crystal display device having a first light diffusing layer, a backlight of a VA mode SHARP 32-inch liquid crystal television LC-32D10-B has a light incident surface of a liquid crystal cell in the light emitted from the first light diffusing layer. A liquid crystal display device having a first light diffusion layer whose luminance value in the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell with respect to the luminance value in the normal direction is 10% was used. Next, the polarizing plate and the retardation plate on both sides of the liquid crystal cell of the liquid crystal display device are peeled off, and the iodine-based normal polarizing plate TRW842AP7 manufactured by Sumitomo Chemical Co., Ltd. is bonded to the front and back so as to be crossed Nicol, Bonding was performed so that the absorption axis was parallel to the short side and the long side of the liquid crystal cell. Finally, an antiglare layer having a light emission angle of 46 ° with respect to the normal direction where the relative intensity to the intensity of light incident from the normal direction is 0.0008% is bonded to the surface of the second polarizing plate. From the surface, a second light diffusing layer (antiglare layer, second polarizing plate), a liquid crystal cell, a first polarizing plate, a second light diffusing layer (prism sheet, light diffusing plate) and a backlight device are provided (FIG. 1). Configuration) A liquid crystal display device was prepared and visually evaluated.
From a viewing angle of 0 ° (front) to 60 °, no inversion was observed in gradation reversal, gradation collapse, color tone, white floating of black display, and luminance change, and all were good. The results are shown in Table 2.

(Examples 2 and 3)
The luminance value in the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell is 0% and 20% with respect to the normal value of the light incident surface of the liquid crystal cell in the light emitted from the first light diffusion layer, respectively. %, Except that it was%. The results are shown in Table 2.

(Examples 4 and 5)
The same procedure as in Example 1 was performed except that the light emission angles of the antiglare layer were 42 ° and 58 °, respectively. The results are shown in Table 2.

＊１：第１光拡散層からの出射光における、液晶セルの光入射面の法線方向の輝度値に対する、この法線に対して７０°方向の輝度値
＊２：防眩層の背面の法線方向から入射する波長５４９ｎｍのレーザ光の強度に対して相対強度が０．０００８％となる、防眩層から出射するレーザ光の、防眩層の背面の法線方向に対しての光出射角度
　なお、＊１、＊２は、表３及び表４も同様である。
　◎：異常が全く認められない。
　○：異常がほとんど認められない。
　×：異常が認められる。

* 1: Luminance value in the direction of 70 ° with respect to the normal value of the light emitted from the first light diffusion layer in the normal direction of the light incident surface of the liquid crystal cell * 2: On the back surface of the antiglare layer Light with a relative intensity of 0.0008% with respect to the intensity of laser light having a wavelength of 549 nm incident from the normal direction, the light emitted from the antiglare layer in the normal direction on the back side of the antiglare layer Output angle Note that * 1 and * 2 are the same in Table 3 and Table 4.
A: No abnormality is observed.
○: Almost no abnormality is observed.
X: Abnormality is observed.

(Examples 6 to 10)
As the liquid crystal display device, after peeling off the polarizing plate on the surface side in the liquid crystal cell, the liquid crystal display device to which the iodine-based polarizing plate “TRW842AP7” manufactured by Sumitomo Chemical Co., Ltd. was bonded, that is, from the surface, the second light diffusion layer ( Anti-glare layer, second polarizing plate), liquid crystal cell, retardation plate, first polarizing plate, first light diffusing layer (prism sheet, light diffusing plate) and backlight device (configuration of FIG. 9) liquid crystal display device In the light emitted from the first light diffusion layer, the luminance value in the direction of 70 ° with respect to the normal value of the light incident surface of the liquid crystal cell relative to the luminance value in the normal direction of the light incident surface of the liquid crystal cell, anti-glare The same operation as in Example 1 was performed except that the light emission angle of the layer showed values shown in Table 3. The results are shown in Table 3.

　◎：異常が全く認められない。
　○：異常がほとんど認められない。
　×：異常が認められる。

A: No abnormality is observed.
○: Almost no abnormality is observed.
X: Abnormality is observed.

(Example 11)
As a liquid crystal display device having a first light diffusion layer, a backlight of a TN mode 26-type liquid crystal television TL2686TW manufactured by TECO is used in the normal direction of the light incident surface of the liquid crystal cell in the light emitted from the first light diffusion layer. A liquid crystal display device having a first light diffusion layer whose luminance value in the direction of 70 ° with respect to the normal value of the light incident surface of the liquid crystal cell with respect to the luminance value is 10% was used. Next, the polarizing plate and the retardation plate on both sides of the liquid crystal cell of the liquid crystal display device are peeled off, and the iodine-based normal polarizing plate TRW842AP7 manufactured by Sumitomo Chemical Co., Ltd. is bonded to the front and back so as to be crossed Nicol, Bonding was performed so that the absorption axis was parallel to the short side and the long side of the liquid crystal cell. Finally, an antiglare layer having a light emission angle of 46 ° relative to the normal direction with a relative intensity of 0.0008% is bonded to the surface of the second polarizing plate, and the second light diffusion layer is formed from the surface. (Anti-glare layer, second polarizing plate), liquid crystal cell, first polarizing plate, second light diffusion layer (prism sheet, light diffusion plate) having a backlight device (configuration in FIG. 1), a liquid crystal display device is produced, Visual evaluation was performed.
From a viewing angle of 0 ° (front) to 60 °, no inversion was observed in gradation reversal, gradation collapse, color tone, white floating of black display, and luminance change, and all were good. The results are shown in Table 4.

(Examples 12 and 13)
Luminance values in the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell in the light emitted from the first light diffusion layer with respect to the normal value of the light incident surface of the liquid crystal cell are 0% and 20%, respectively. Except that, it was carried out in the same manner as in Example 1. The results are shown in Table 4.

(Examples 14 and 15)
The same procedure as in Example 1 was performed except that the light emission angles of the antiglare layer were 42 ° and 58 °, respectively. The results are shown in Table 4.

　◎：異常が全く認められない。
　○：異常がほとんど認められない。
　×：異常が認められる。

A: No abnormality is observed.
○: Almost no abnormality is observed.
X: Abnormality is observed.

In the liquid crystal display device of the present invention, a wide viewing angle, high display quality, and excellent color reproducibility can be obtained. Further, the viewing angle can be expanded without using a retardation plate, and the number of parts can be reduced.

Claims (8)

A liquid crystal cell in which a liquid crystal layer is provided between a pair of substrates, a backlight device provided on the back side of the liquid crystal cell, and a first light disposed between the backlight device and the liquid crystal cell A diffusion layer, a first polarizing plate disposed between the first light diffusion layer and the liquid crystal cell, and a second light diffusion layer disposed on the front side of the liquid crystal cell,
The first light diffusing layer has a light diffusing function and / or a light deflecting function, and light emitted from the first light diffusing layer is (i) light incident on the liquid crystal cell. Having a light distribution characteristic in which the luminance value in the direction of 70 ° with respect to the normal of the surface is 20% or less with respect to the luminance value in the normal direction, and (ii) includes non-parallel light,
The second light diffusion layer is composed of a second polarizing plate and an antiglare layer provided on the front side of the second polarizing plate, and the light diffusion characteristic of the antiglare layer is the back surface of the antiglare layer. The relative intensity is 0.0008% with respect to the intensity of the laser beam having a wavelength of 549 nm incident from the normal line direction of the laser beam emitted from the antiglare layer with respect to the normal direction of the back surface of the antiglare layer. Liquid crystal display device whose light emission angle is 40 ° or more. The liquid crystal display device according to claim 1, wherein the first light diffusion layer has both a light diffusion function and a light deflection function. The first light diffusion layer includes a light diffusion plate that performs the light diffusion function and a light deflection structure plate that performs the light deflection function, and the light deflection structure plate is provided on a front side of the light diffusion plate. The liquid crystal display device according to claim 2. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal cell is one of a TN liquid crystal, an IPS liquid crystal, and a VA liquid crystal. The liquid crystal display device according to any one of claims 1 to 4, further comprising a retardation plate disposed on the back side and / or the front side of the liquid crystal cell. 5. The liquid crystal display device according to claim 1, wherein the liquid crystal display device does not include a retardation plate. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal cell is a TN liquid crystal and does not include a retardation plate. The light emitted from the first light diffusion layer is emitted from a circle having a diameter of 1 cm on the emission surface of the first light diffusion layer to the emission surface, which is 1 m away from the normal direction of the emission surface. The liquid crystal display device according to any one of claims 1 to 7, wherein the liquid crystal display device has light emission characteristics such that when a projected image on a parallel plane is observed, the minimum half-value width of the in-plane luminance distribution of the projected image is 30 cm or more. .

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