CN102460285A - Liquid crystal display device - Google Patents

Abstract

Provided is a liquid crystal display device with high luminance and contrast and excellent display characteristics. The liquid crystal display device is configured from a surface light source (20), and a liquid crystal panel (10) disposed above the surface light source and provided with a liquid crystal cell (3) and a polarizing plate stacked on a surface on the surface light source side of the liquid crystal cell. The polarizing plate is provided with a polarizing film (12) and a prism sheet (13) having the surface thereof configured from prism-shaped protrusions (13a), the prism sheet (13) is disposed such that the surface thereof configured from the prism-shaped protrusions faces the surface light source, and the light intensity distribution indicating the emission angle dependence of the light intensity of emitted light from the surface light source (20) satisfies the following (1) and (2). (1) The maximum value of the light intensity has the highest peak in the range of -80 DEG =<-40 DEG or 40 DEG <=80 DEG . (2) The following expression is satisfied: a-b<30 DEG where a is an angle at which the maximum value of the light intensity at the peak is shown, and b is an angle at which a half of the maximum value of the light intensity at the peak is shown.

Description

Liquid crystal display device

technical field

The present invention relates to liquid crystal display devices used in liquid crystal televisions, liquid crystal monitors, personal computers, and the like.

Background technique

Liquid crystal display devices are rapidly expanding as thin display devices used in liquid crystal televisions, liquid crystal monitors, personal computers, and the like. In particular, the market for LCD TVs is expanding remarkably, and there is also a very high demand for achieving low costs.

A general liquid crystal display device is composed of a surface light source using cold cathode tubes or LEDs, a light diffusion plate, one or more diffusion sheets, a light concentrating sheet, and a liquid crystal panel to which a polarizing plate is bonded. In recent years, thinning of liquid crystal display devices has been urgently demanded for applications such as wall-mountable large-screen liquid crystal televisions. In this case, corresponding to the thinning of liquid crystal display devices, it is necessary to Reduce the number of components.

For this requirement, known following technology, promptly, by the method (for example JPH11- 295714-A and JP2008-262132-A), a method of using a light-condensing prism sheet as a protective film of a polarizer disposed on the surface light source side of a liquid crystal panel (for example, JP2008-262132-A and JP2005-17355-A), This eliminates one or more components and reduces the number of components.

As described in the above-mentioned Patent Documents 1 to 3, liquid crystal display devices using polarizing plates equipped with sheet members such as prism sheets do not fully exhibit the desired light-condensing function of the sheet members due to the light emission characteristics of the surface light source used, resulting in When display characteristics such as brightness and contrast are degraded.

Contents of the invention

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a liquid crystal display device having high luminance and contrast and excellent display characteristics.

The present invention relates to a liquid crystal display device comprising a surface light source and a liquid crystal panel disposed on the surface light source and including a liquid crystal cell and a polarizing plate laminated on a surface of the liquid crystal cell on the surface light source side. In the liquid crystal display device of the present invention, the above-mentioned polarizer includes a polarizing film and a prism sheet, the prism sheet is laminated on the surface of the polarizing film through an adhesive layer and has a surface composed of prism-shaped protrusions, and the prism sheet is configured The surface made of prism-shaped protrusions faces the surface light source. In addition, in the liquid crystal display device of the present invention, the angle formed by the normal direction of the light exit surface of the surface light source and the exit direction of the exit light of the surface light source in a plane perpendicular to the ridgeline direction of the prism-shaped protrusions is defined as the output At the angle θ (where -90°≦θ≦90°), the light intensity distribution of the surface light source representing the output angle dependence of the light intensity of emitted light satisfies the following (1) and (2).

(1) In the range of -80°θ<-40° or 40°<θ≤80°, the maximum value of the light intensity has the highest peak.

(2) When the angle of the light intensity maximum value in the highest peak showing the above-mentioned light intensity maximum value is θa, and the angle showing 1/2 of the light intensity maximum value in the peak is θb, Satisfy the following formula [1]:

|θa-θb|＜30° [1].

In the liquid crystal display device of the present invention, the surface light source preferably includes a light guide plate and a light source device disposed on a side of the light guide plate. In addition, the light source device is a light source device in which point light sources are arranged in a line or a light source device including rod light sources. The light source device and the prism sheet are preferably arranged so that the light source device is parallel or substantially parallel to the ridgeline of the prism-shaped protrusions.

In the liquid crystal display device of the present invention, the surface light source preferably has one light source device arranged on one side of the light guide plate or two light source devices arranged on opposite sides of the light guide plate.

The apex angle α of the prism-shaped protrusions is preferably 60° or more. In addition, the cross-sectional shape of the prism-shaped protrusion is preferably an isosceles triangle.

The liquid crystal display device of the present invention is thin, has high brightness and contrast, and has excellent display characteristics. The liquid crystal display device of the present invention can be suitably used as a liquid crystal display device for a large-screen liquid crystal television, particularly a liquid crystal display device for a wall-mountable liquid crystal television, and the like.

Description of drawings

[ Fig. 1 ] is a schematic cross-sectional view showing a preferred example of the liquid crystal display device of the present invention.

[ Fig. 2 ] is a schematic cross-sectional view showing a preferred example of a rear-side polarizing plate used in the present invention.

[FIG. 3] It is a schematic perspective view which shows an example of the surface shape of a prism sheet.

[ Fig. 4 ] is a schematic perspective view for explaining light emission characteristics of a surface light source used in the present invention.

[FIG. 5] It is a schematic diagram for demonstrating the path of the light which enters the prism-shaped protrusion which a prism sheet has.

[ FIG. 6 ] is a diagram showing the light intensity distribution of the surface light source A used in Examples 1 and 2. [ FIG.

[FIG. 7] It is a figure which shows the light intensity distribution of the surface light source B used in the comparative examples 1 and 2. [FIG.

[ FIG. 8 ] is a graph showing the light intensity distribution (brightness distribution) of the liquid crystal display device produced in Example 1. [ FIG.

[ FIG. 9 ] is a graph showing the light intensity distribution (brightness distribution) of the liquid crystal display device produced in Comparative Example 1. [ FIG.

Detailed ways

FIG. 1 is a schematic cross-sectional view showing a preferred example of the liquid crystal display device of the present invention. The liquid crystal display device 100 shown in FIG. 1 of the present invention is composed of a surface light source 20 and a liquid crystal panel 10 arranged on the surface light source 20. The surface light source 20 is equipped with a light guide plate 22 and a light guide plate along the side of the light guide plate 22. The light source device 21 is arranged in a manner of 22 on one side. The liquid crystal panel 10 includes a liquid crystal cell 3, a polarizing plate 1 as a rear polarizing plate laminated on the surface of the liquid crystal cell 3 on the side of the surface light source 20, and a polarizing plate 1 as a front polarizing plate laminated on the surface of the liquid crystal cell 3 on the viewing side. Sheet polarizer 2. The polarizing plate 1 and the polarizing plate 2 are bonded to the liquid crystal cell 3 through the adhesive layer 17 .

The polarizing plate 1 as the backside polarizing plate is provided with a polarizing film 12, and a surface (hereinafter also referred to as a prism surface) that is formed of prism-like protrusions 13a and is laminated on the surface light source 20 side surface of the polarizing film 12 via an adhesive layer 14. ) of the prism sheet 13 and the resin film 15 laminated on the viewing side surface of the polarizing film 12 through the adhesive layer 16 . The polarizing plate 1 is bonded to the liquid crystal cell 3 on the side of the resin film 15 . More specifically, the liquid crystal cell 3 and the polarizer 1 are bonded together so that the surface of the polarizing film 12 opposite to the surface on which the prism sheet 13 is laminated faces the liquid crystal cell 3 , that is, the prism sheet 13 The prism surface forms the surface light source side surface of the liquid crystal panel 10 , and the prism surface faces the surface light source 20 . It should be noted that, in the present invention, the rear polarizing plate may not have such a resin film, and the polarizing film 12 may be directly bonded to the liquid crystal cell 3 via an adhesive layer or the like.

As shown in FIG. 1, the liquid crystal display device of the present invention is a liquid crystal display device that has used a backside polarizing plate having a prism sheet laminated on the surface of a polarizing film through an adhesive layer. As will be described in detail later, using this A liquid crystal display device having a rear-side polarizing plate of a prism sheet is characterized by using a surface light source having a specific light emission characteristic, specifically, a light distribution characteristic (light of which intensity is emitted in which direction). According to the present invention, it is possible to provide a liquid crystal display device that uses a rear-side polarizing plate having a prism sheet, has high brightness and contrast, and has excellent display characteristics. In addition, the liquid crystal display device of the present invention has a sufficient mechanical strength corresponding to the thickness reduction by including a liquid crystal panel on which a thinned polarizing plate is bonded to the back side of the liquid crystal cell, and since the prism Since the sheet is arranged on the back side of the liquid crystal panel, close contact between the liquid crystal panel and the surface light source is prevented, thereby also achieving improvement in display characteristics. Hereinafter, the liquid crystal display device of the present invention will be described in detail with reference to appropriate drawings.

<Rear side polarizing plate>

FIG. 2 is a schematic cross-sectional view showing a preferred example of a rear-side polarizing plate used in the present invention, and its configuration is the same as that of the polarizing plate 1 in FIG. 1 (the reference numerals are also the same). As shown in FIG. 2 , the back side polarizing plate used in the present invention at least has a polarizing film 12, is laminated on one surface (surface light source side surface) of the polarizing film 12 through an adhesive layer 14, and has prism-shaped protrusions 13a. The surface (prism surface) of the prism sheet 13 is formed. Like the polarizing plate 1 shown in FIG. 2 , the back side polarizing plate may include a resin film laminated on the surface opposite to the surface on which the prism sheet 13 is laminated (the surface on the liquid crystal cell side) via an adhesive layer 16. 15.

(polarizing film)

Specifically, the polarizing film 12 used for the back polarizing plate is a polarizing film in which a dichroic dye is adsorbed on a uniaxially stretched polyvinyl alcohol-based resin film and the dichroic dye is oriented. As a polyvinyl-alcohol-type resin which comprises a polyvinyl-alcohol-type resin film, what saponified polyvinyl acetate-type resin can be used. Examples of polyvinyl acetate-based resins include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers that can be copolymerized therewith, such as ethylene-vinyl acetate copolymers. things etc. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of polyvinyl alcohol-type resin is about 85-100 mol% normally, Preferably it is 98 mol% or more. The polyvinyl alcohol-based resin may be modified. For example, polyvinyl formal, polyvinyl acetal, and polyvinyl butyral modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

Such a polyvinyl alcohol-based resin is formed into a film and used as an original film (original reverse film) of a polarizing film. The method of forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a conventionally known appropriate method can be used to form a film. The film thickness of the raw film formed of polyvinyl alcohol-based resin is not particularly limited, but is, for example, about 10 to 150 μm.

A polarizing film is usually produced through the steps of dyeing the above-mentioned raw film formed of a polyvinyl alcohol-based resin with a dichroic dye to adsorb the dichroic dye (dyeing treatment step), and absorbing the dichroic dye. A step of treating the polyvinyl alcohol-based resin film of the color dye with a boric acid aqueous solution (boric acid treatment step), and a step of washing with water after the treatment with the boric acid aqueous solution (water washing treatment step).

In addition, when producing a polarizing film, the polyvinyl alcohol-based resin film is usually uniaxially stretched, but this uniaxial stretching may be performed before the dyeing treatment process, may be performed during the dyeing treatment process, or may be performed after the dyeing treatment process. conduct. When performing uniaxial stretching after the dyeing treatment process, this uniaxial stretching may be performed before the boric acid treatment process or may be performed during the boric acid treatment process. Of course, uniaxial stretching can also be performed in these multiple steps. The uniaxial stretching may be performed between rolls having different peripheral speeds, or may be uniaxially stretched using heated rolls. In addition, dry stretching in which stretching is performed in the air may be used, or wet stretching in which stretching is performed in a state of being swollen with a solvent. The draw ratio is usually about 3 to 8 times.

The dyeing of the polyvinyl alcohol-based resin film with a dichroic dye in the dyeing treatment step is performed, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. As a dichroic dye, iodine, a dichroic dye, etc. can be used, for example. Dichroic dyes include, for example, dichroic direct dyes composed of disazo compounds such as C.I. Direct Red 39, dichroic direct dyes composed of trisazo, tetrasazo compounds, and the like. In addition, it is preferable that the polyvinyl-alcohol-type resin film performs the immersion process in water before dyeing process previously.

When using iodine as a dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide to dye it is generally employed. Content of iodine in this aqueous solution is 0.01-1 weight part per 100 weight part of water normally, and content of potassium iodide is 0.5-20 weight part per 100 weight part of water normally. When using iodine as a dichroic dye, the temperature of the aqueous solution used for dyeing is normally 20-40 degreeC, and the immersion time (dyeing time) in this aqueous solution is normally 20-1800 second.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye and dyeing is generally employed. The content of the dichroic dye in the aqueous solution is usually 1×10 ^-4 to 10 parts by weight, preferably 1×10 ^-3 to 1 part by weight, particularly preferably 1×10 ^-3 to 100 parts by weight of water. 1×10 ^-2 parts by weight. The aqueous solution may contain inorganic salts such as sodium sulfate as dyeing aids. When a dichroic dye is used as the dichroic dye, the temperature of the aqueous dye solution used for dyeing is usually 20 to 80° C., and the immersion time (dyeing time) in the aqueous solution is usually 10 to 1800 seconds.

The boric acid treatment step is performed by immersing the polyvinyl alcohol-based resin film dyed with a dichroic dye in a boric acid-containing aqueous solution. The quantity of the boric acid in a boric-acid-containing aqueous solution is 2-15 weight part normally per 100 weight part of water, Preferably it is 5-12 weight part. When using iodine as the dichroic dye in the dyeing treatment step, it is preferable that the boric acid-containing aqueous solution used in the boric acid treatment step contains potassium iodide. In this case, the quantity of potassium iodide in boric-acid-containing aqueous solution is 0.1-15 weight part normally per 100 weight part of water, Preferably it is 5-12 weight part. The immersion time in the boric acid-containing aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50°C or higher, preferably 50 to 85°C, more preferably 60 to 80°C.

In the subsequent water washing treatment step, the water washing treatment is performed by immersing the boric acid-treated polyvinyl alcohol-based resin film in, for example, water. The temperature of water in the water washing treatment is usually 5 to 40°C, and the immersion time is usually 1 to 120 seconds. Drying treatment is usually performed after water washing treatment to obtain a polarizing film. The drying treatment can be performed using, for example, a hot air dryer, a far-infrared heater, or the like. The temperature of the drying treatment is usually 30 to 100°C, preferably 50 to 80°C. The drying treatment time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

Thus, the polyvinyl alcohol-type resin film was subjected to uniaxial stretching, dyeing with a dichroic dye, boric acid treatment, and water washing treatment to obtain a polarizing film. The thickness of the polarizing film is usually in the range of 5 to 40 μm.

(prism sheet)

The prism sheet 13 used for the rear-side polarizing plate has a surface (prism surface) composed of prism-shaped protrusions (prism-shaped protrusions 13 a ). The prism sheet 13 is laminated on the polarizing film 12 so that the surface opposite to the prism surface faces the polarizing film 12 . A prism sheet 13 having a prism surface is arranged on the surface of the backside polarizing plate, and the prism surface is opposed to a surface light source described later, thereby changing (deflecting) the light exit surface (with the prism surface) from the surface light source intentionally. The direction of light emitted from the surface on the opposite side). According to the present invention, the emitted light from the surface light source, especially the directional emitted light [the main emission direction is different from the normal direction of the light emitting surface of the surface light source (the front direction of the liquid crystal display device) can be utilized by utilizing the above-mentioned prism sheet. The direction of the emitted light] is deflected to the front direction of the liquid crystal display device, thereby improving the brightness and contrast of the front face of the liquid crystal display device. It should be noted that the prism sheet 13 also functions as a protective film for the polarizing film 12 .

Here, the "prism-shaped protrusion" refers to a columnar body represented by a trajectory obtained by moving a triangular shape (substantially triangular shape partially including a curved line, zigzag shape, etc.) in parallel with the surface of the triangular shape perpendicular to the surface. , the portion of the edge (ridgeline) clamped by the two sides that do not form the bottom surface (the diagonal track of the bottom edge of the triangle shape), the prism surface is a plurality of the columnar bodies in the columnar body and The opposite surfaces of the prism-shaped protrusions (the locus of the base of the triangle shape) are arranged in parallel close contact as the bottom surface, and a plurality of prism-shaped protrusions are arranged in one direction (in such a way that the ridgelines of each prism-shaped protrusion become parallel or approximately parallel) ) to arrange. 3 is a schematic perspective view showing an example of the surface shape of a prism sheet, in which the cross-sectional shape of the prism-shaped protrusions is an isosceles triangle.

The vertex angle (angle of the vertex) of the prism-shaped protrusion 13a that the prism sheet 13 has can be set to, for example, 30 to 100°. In order to efficiently deflect to the front direction of the liquid crystal display device, it is especially preferable to set it as 60°-100°, and it is more preferable to set it as 60°-80°.

The height of the prism-shaped protrusion 13a can be set to 10-200 micrometers, for example. In addition, the pitch of the prism-shaped protrusions 13a (the distance between the ridgelines of adjacent protrusions) can be appropriately determined in consideration of the apex angle and height of the prism-shaped protrusions 13a, and can be, for example, 5 to 300 μm.

The two sides of the protrusions in the triangular cross-section constituting the prism-like protrusions 13a may have the same length or different lengths, but at least when the light source devices of the surface light source used are arranged on opposite sides of the light guide plate, it is preferable that the two sides be Therefore, the cross-sectional shape of the prism-shaped protrusion 13a is preferably an isosceles triangle. The heights of the plurality of prism-shaped protrusions 13a may all be the same or different. In addition, the shape of the groove formed between the protrusions may be straight or curved.

Various known materials can be used as the material of the prism sheet 13 . For example, polyolefin-based resins such as polyethylene and polypropylene; polyester-based resins such as polyethylene terephthalate resins and polyethylene naphthalate resins; polyvinyl chloride resins; polycarbonate-based resins; Resin; norbornene resin; polyurethane resin; acrylic resin; polymethyl methacrylate resin; polystyrene resin; methyl methacrylate-styrene copolymer, acrylonitrile-butadiene-benzene Synthetic polymers such as ethylene copolymers and acrylonitrile-styrene copolymers; natural polymers such as cellulose diacetate resins and cellulose triacetate resins. Among them, polyolefin-based resins, polyacrylic resins, polycarbonate-based resins, polyester-based resins, polystyrene-based resins, methyl methacrylate-styrene resins are preferable from the viewpoint of transparency, moisture permeability, and productivity. Any one of thermoplastic resins among copolymers, acrylonitrile-butadiene-styrene copolymers, and acrylonitrile-styrene copolymers. In addition, these polymer materials may contain additives such as ultraviolet absorbers, antioxidants, and plasticizers as necessary.

Prism sheet 13 can use above-mentioned transparent macromolecule material as base material, by photopolymer processing method, profiled extrusion method, compression molding method, injection molding method, roll transfer printing method, laser ablation method, mechanical cutting method, mechanical It can be produced by a known method such as a grinding method. These methods may be used alone, or two or more methods may be combined.

The thickness of the prism sheet 13 is not particularly limited, but is preferably about 20 μm to 200 μm, more preferably 30 μm to 100 μm, from the viewpoint of thinning the thickness of the polarizing plate.

(resin film)

As an example shown in FIG. 2 , a resin film 15 such as a protective film or an optical compensation film may be laminated on the surface of the polarizing film 12 opposite to the surface on which the prism sheet is laminated. In this case, the polarizing plate 1 is bonded to the liquid crystal cell through an adhesive layer laminated on the resin film 15 . In addition, an optically functional film described later may be laminated on the polarizing film 12 , a protective film, or an optical compensation film via an adhesive layer or an adhesive layer.

Examples of the resin film 15 include cellulose-based resin films such as triacetyl cellulose films (TAC films), polyolefin-based resin films, acrylic resin films, and polyester-based resin films such as polyethylene terephthalate. wait.

As the cellulose-based resin constituting the above-mentioned cellulose-based resin film, partially or completely esterified products of cellulose are mentioned, for example, acetates, propionates, butyrates of cellulose, and their mixed esters etc. More specifically, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, etc. are mentioned. When forming such a cellulose-based resin into a film to form a film, known methods such as a solvent casting method and a melt extrusion method can be appropriately used. Examples of commercially available cellulose ester resin films include "Fijitac TD80" (manufactured by Fujifilm Co., Ltd.), "Fijitac TD80UF" (manufactured by Fujifilm Co., Ltd.), "Fijitac TD80UZ" (manufactured by Fujifilm Co., Ltd. ), "KC8UX2M" (manufactured by Konica Minolta Opto Co., Ltd.), "KC8UY" (manufactured by Konica Minolta Opto Co., Ltd.), etc.

In addition, as an optical compensation film formed of a cellulose-based resin film, for example, a film in which the above-mentioned cellulose-based resin film contains a compound having a retardation function; A film made of a compound having a poor adjustment function; a film obtained by uniaxially stretching or biaxially stretching a cellulose-based resin film; and the like.

As a commercially available optical compensation film formed of a cellulose-based resin film, for example, "WV BZ 438" and "WV EA" manufactured by Fujifilm Co., Ltd., "KC4FR-1" manufactured by Konica Minolta Opto Co., Ltd. , "KC4HR-1" and so on.

The thickness of the protective film or optical compensation film made of a cellulose-based resin film is not particularly limited, but is preferably within a range of 20 to 90 μm, more preferably within a range of 30 to 90 μm. When the thickness is less than 20 μm, the handling of the film is difficult. On the other hand, when the thickness exceeds 90 μm, the processability is deteriorated, and it is disadvantageous in terms of thinning and weight reduction of the obtained polarizing plate.

As an optical compensation film formed from the said polyolefin resin film, the uniaxially stretched or biaxially stretched cycloolefin resin film is mentioned, for example. When applied to a liquid crystal panel for a large liquid crystal television, especially a liquid crystal panel having a liquid crystal cell in a vertical alignment (VA) mode, as the above-mentioned optical compensation film, a cycloolefin-based resin film is also preferable from the viewpoint of optical characteristics and durability. Stretch. Here, the cycloolefin-based resin film is, for example, a film made of a thermoplastic resin having a monomer unit formed of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene-based monomer. The cycloolefin-based resin film may be a hydrogenated product of a ring-opening polymer using a single cycloolefin, a hydrogenated product of a ring-opening copolymer using two or more cycloolefins, or a hydrogenated product of a cycloolefin and an alkene and/or a vinyl group. Addition copolymers of aromatic compounds, etc. In addition, those having polar groups introduced into the main chain or side chain are also effective.

Commercially available thermoplastic cycloolefin-based resins include "Topas" sold by TOPAS ADVANCED POLYMERS GmbH in Germany, "ARTON" sold by JSR Corporation, "ZEONOR" and "ZEONEX" sold by Nippon Zeon Co., Ltd., "Apel" (both are trade names) and the like sold by Mitsui Chemicals, Ltd., etc., and these resins can be preferably used.

Such a cycloolefin-based resin can be formed into a film to obtain a cycloolefin-based resin film. As a film forming method, well-known methods, such as a solvent casting method and a melt extrusion method, can be used suitably. In addition, "S-SINA" and "SCA40" sold by Sekisui Chemical Industry Co., Ltd., "ZEONOR film" sold by Nippon Zeon Co., Ltd., "ARTON film" sold by JSR Corporation ( Both are trade names) and other cycloolefin-based resin films can be preferably used.

If the thickness of the optical compensation film formed by the stretched cycloolefin-based resin film is too thick, the workability will be deteriorated, and the transparency will be reduced, which is disadvantageous in terms of thinning and weight reduction of the polarizing plate, so it is preferably About 20-80 μm.

The rear-side polarizing plate used in the present invention can be obtained by bonding the above-mentioned prism sheet to one surface of the above-mentioned polarizing film using an adhesive. Thereby, referring FIG. 2, the polarizing plate which laminated|stacked the prism sheet 13 on the surface of the polarizing film 12 via the adhesive layer 14 is obtained. When laminating the resin film 15 on the other surface of the polarizing film 12, the bonding of the polarizing film 12 and the resin film 15 is performed similarly using an adhesive. The adhesive forms the adhesive layer 16 . When the resin film 15 is pasted on the polarizing film 12, the adhesive used for pasting the prism sheet 13 and the adhesive used for pasting the resin film 15 can be the same kind of adhesive or different kinds of adhesives. mixture. Examples of the adhesive used to bond these films include water-based adhesives, that is, adhesives obtained by dissolving or dispersing adhesive components in water, and photocurable adhesives.

It is preferable to use the above-mentioned water-based adhesive at the point that the adhesive layer can be thinned. As a water-based adhesive, the water-based adhesive which uses a polyvinyl-alcohol-type resin or a polyurethane resin as an adhesive component is mentioned, for example.

When using polyvinyl alcohol-based resin as the binder component, the polyvinyl alcohol-based resin can be partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, in addition, carboxy-modified polyvinyl alcohol, acetyl Modified polyvinyl alcohol-based resins such as acetyl-modified polyvinyl alcohol, methylol-modified polyvinyl alcohol, and amino-modified polyvinyl alcohol. Usually, a water-based adhesive comprising a polyvinyl alcohol-based resin as a binder component is prepared as an aqueous solution of a polyvinyl alcohol-based resin. The density|concentration of the polyvinyl-alcohol-type resin in a binder is about 1-10 weight part normally with respect to 100 weight part of water, Preferably it is about 1-5 weight part.

In an adhesive comprising a polyvinyl alcohol-based resin as an adhesive component, it is preferable to add a curable component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent in order to improve adhesiveness. As the water-soluble epoxy resin, for example, polyamide polyamine epoxy resin obtained by reacting epichlorohydrin with polyamide polyamine obtained by diethylenetriamine, triethylene It is obtained by reacting polyalkylenepolyamines such as tetramines with dicarboxylic acids such as adipic acid. Commercially available polyamide polyamine epoxy resins include "SUMIREZ RESIN 650" and "SUMIREZ RESIN 675" sold by Sumika Chemtex Co., Ltd., "WS-525" sold by Japan PMC Corporation, and the like. The added amount of these curable components or crosslinking agents (the total amount when both are added) is usually 1 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the polyvinyl alcohol-based resin. When the addition amount of the curable component and the crosslinking agent is less than 1 part by weight relative to 100 parts by weight of the polyvinyl alcohol-based resin, the effect of improving the adhesion tends to be small. When the addition amount exceeds 100 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin, the adhesive layer tends to become brittle.

Moreover, when using a polyurethane resin as an adhesive component, the mixture of a polyester ionomer type polyurethane resin and the compound which has a glycidyloxy group is mentioned as an example of a suitable adhesive composition. Here, the polyester-based ionomer type polyurethane resin is a polyurethane resin having a polyester skeleton into which a small amount of ionic components (hydrophilic components) is introduced. Since this ionomer type polyurethane resin is directly emulsified in water to form an emulsion without using an emulsifier, it is suitable as a water-based adhesive.

The polyester-based ionomer type polyurethane resin itself is known, for example, in JP-A No. 7-97504, it is described as an example of a polymer dispersant for dispersing a phenolic resin in an aqueous medium, and in JP-A-2005-070140 and JP-A-2005-181817 disclose the following content: a mixture of a polyester-based ionomer polyurethane resin and a compound having a glycidyloxy group is used as a binder, and a cycloolefin-based resin The film is bonded to a polarizing film made of polyvinyl alcohol-based resin.

As the method of applying the adhesive to the polarizing film and/or the member (prism sheet, protective film or optical compensation film) bonded thereto, it can be a generally known method, for example, casting method, Meyer rod coating method, gravure coating method, comma coater method, doctor blade method, die coating method, dip coating method, spray method, etc. The casting method is a method in which a film to be coated is moved in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two, and the adhesive is flowed and spread on the surface of the film.

After the adhesive is applied, the polarizing film and the member to be bonded are superimposed on each other, and the film is bonded by nipping with nip rolls or the like. The lamination of the film using the nip roll can adopt the following methods, for example, after the adhesive is applied, the method of applying pressure with a roller or the like to spread it evenly; A method of spreading between rolls by applying pressure. In the former case, metal, rubber, or the like can be used as the material of the roller. In addition, in the latter case, the plurality of rollers may be made of the same material or different materials.

After the above bonding, the adhesive layer is cured by drying to obtain a polarizing plate. This drying treatment is performed by, for example, blowing hot air, and the temperature thereof is usually in the range of 40 to 100°C, preferably in the range of 60 to 100°C. In addition, the drying time is usually 20 to 1200 seconds.

The thickness of the adhesive layer after drying is usually 0.001 to 5 μm, preferably 0.01 to 2 μm, more preferably 0.01 to 1 μm. When the thickness of the adhesive layer after drying is less than 0.001 μm, adhesion may become insufficient, and when the thickness of the adhesive layer after drying exceeds 5 μm, the appearance of the polarizing plate may be poor. It should be noted that the thickness of the pressure-sensitive adhesive layer bonded by the above-mentioned nip roll or the like before drying and curing is preferably 5 μm or less, and preferably 0.01 μm or more.

After the drying treatment, aging can be carried out at a temperature higher than room temperature for at least half a day, usually more than one day to obtain sufficient adhesive strength. This aging is typically performed in the state wound up into a roll. A preferable aging temperature is the range of 30-50 degreeC, More preferably, it is 35-45 degreeC. When the aging temperature exceeds 50° C., so-called “coil tightness (卷きるまり)” tends to occur in the rolled state. In addition, the humidity at the time of aging is not specifically limited, However, It is preferable to select so that a relative humidity may fall into the range of about 0%RH - 70%RH. The aging time is usually about 1 day to 10 days, preferably about 2 days to 7 days.

Moreover, as said photocurable adhesive agent, the mixture etc. of a photocurable epoxy resin and a photocationic polymerization initiator are mentioned, for example. As a photocurable epoxy resin, an alicyclic epoxy resin, the epoxy resin which does not have an alicyclic structure, and these mixtures etc. are mentioned, for example. In addition to photocurable epoxy resins, the photocurable adhesive may also contain acrylic resins, oxetane resins, polyurethane resins, polyvinyl alcohol resins, etc., and may also contain photocationic polymerization initiators at the same time. Alternatively, a photoradical polymerization initiator may be included instead of the photocationic polymerization initiator.

When using a photocurable adhesive, apply the photocurable adhesive to the polarizing film and/or the member (prism sheet, protective film or optical compensation film) attached to it, and then apply the polarizing film and After bonding the members together, the photocurable adhesive is cured by irradiating active energy rays. The coating method of the photocurable adhesive and the lamination method of the film may be the same as that of the water-based adhesive. The light source of active energy rays is not particularly limited, but active energy rays having a luminescence distribution below a wavelength of 400 nm are preferred. Specifically, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultrahigh-pressure mercury lamps, chemical lamps, Black light lamps, microwave excited mercury lamps, metal halide lamps, etc.

The intensity of light irradiation to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive, and is not particularly limited, but the irradiation intensity in the wavelength region effective for activation of the polymerization initiator is preferably 0.1 to 6000 mW/cm ² . When the irradiation intensity is 0.1mW/ ^cm2 or more, the reaction time will not be too long, and when it is 6000mW/ ^cm2 or less, the heat radiated from the light source and the heat generated during the curing of the photocurable adhesive will cause the epoxy resin to burn. There is little possibility of yellowing and deterioration of the polarizing film. The light irradiation time to the photocurable adhesive is controlled for each photocurable adhesive that is cured, and is not particularly limited, but it is preferable to set the cumulative light amount expressed as the product of the above-mentioned irradiation intensity and irradiation time as 10～10000mJ/m ² . When the cumulative amount of light to the photocurable adhesive is 10mJ/m2 ^or more, a sufficient amount of active species from the polymerization initiator can be generated to make the curing reaction more reliable. In addition, when it is 10000mJ/ ^m2 or less, irradiation Does not take too long to maintain good productivity.

When the photocurable adhesive is cured by irradiating active energy rays, it is preferable that the various functions of the polarizing plate such as the degree of polarization, transmittance and color tone of the polarizing film, and the transparency of the prism sheet, protective film, and optical compensation film are not deteriorated. curing under conditions.

It should be noted that before the prism sheet and the protective film or the optical compensation film are bonded to the polarizing film, in order to improve the adhesion, the polarizing film and/or the adhesive surface of the member bonded thereto can be subjected to plasma treatment, electrolysis, etc. Halo treatment, ultraviolet irradiation treatment, flame treatment, saponification treatment and other surface treatments. As a saponification process, the method of immersing in alkaline aqueous solutions, such as sodium hydroxide and potassium hydroxide, is mentioned.

In addition, as described above, the back side polarizing plate may have an optical functional film laminated on the surface of the polarizing film 12 opposite to the surface on which the prism sheet 13 is laminated. As an optical functional film, for example, an optical compensation film in which a liquid crystalline compound is coated on the surface of a substrate and the liquid crystalline compound is oriented; transmits a certain polarized light, and reflects polarized light exhibiting the opposite property Reflective polarizing film; Retardation film formed of polycarbonate resin; Retardation film formed of cycloolefin resin film; Film with anti-glare function having concave-convex shape on the surface; Film with surface anti-reflection function ; a reflective film with a reflective function on the surface; and a semi-transmissive reflective film with both reflective and transmissive functions. As a commercially available product equivalent to an optical compensation film in which a liquid crystalline compound is coated on the surface of a substrate and the liquid crystalline compound is oriented, "WV film" (manufactured by Fujifilm Co., Ltd.), "NH film" (New Nippon Oil Co., Ltd.), "NR membrane" (Nippon Oil Co., Ltd.), etc. As a commercially available product equivalent to a reflective polarizing film that transmits a certain polarized light and reflects polarized light that exhibits the opposite property, for example, "DBEF" (manufactured by 3M Co., Ltd., available in Japan from Sumitomo 3M Co., Ltd.) got) and so on. In addition, examples of commercially available products corresponding to retardation films made of cycloolefin-based resin films include "ARTON Film" (manufactured by JSR Corporation), "S-SINA" (manufactured by Sekisui Chemical Industry Co., Ltd.), "ZEONOR film" (Japan ZEONOR Co., Ltd.), etc.

It is preferable that the back-side polarizing plate has an adhesive layer for bonding to a liquid crystal cell on the surface opposite to the prism sheet. As an adhesive used for such an adhesive layer, a conventionally well-known suitable adhesive can be used, For example, an acrylic adhesive, a polyurethane adhesive, a silicone adhesive, etc. are mentioned. Among these, an acrylic adhesive is preferably used from the viewpoints of transparency, adhesive force, reliability, reworkability, and the like. The adhesive layer can be formed by making such an adhesive into an organic solvent solution, applying it on a base film (eg, a polarizing film, etc.) with a die coater, a gravure coater, etc., and drying it. In addition, it can also be provided by a method of transferring a sheet-shaped adhesive formed on a plastic film (referred to as a separator) subjected to mold release treatment to a base film. The thickness of the adhesive layer is not particularly limited, but is preferably within a range of 2 to 40 μm.

<Front side polarizer>

The front-side polarizing plate (polarizing plate 2 in FIG. 1 ) is a polarizing plate arranged on the side opposite to the surface light source (viewing side) based on the liquid crystal cell. As the front-side polarizing plate, a conventionally known appropriate polarizing plate can be used. For example, in addition to polarizers obtained by laminating a protective film made of triacetyl cellulose or the like on one or both sides of a polarizing film, polarizers treated with antiglare treatment, hard coat treatment, or antireflection treatment can also be used. wait. In addition, it may be a polarizing plate in which a protective film or an optical compensation film formed of a polyethylene terephthalate film, an acrylic film, a polypropylene film, or the like is laminated on one surface of a polarizing film.

<Surface light source>

The liquid crystal display device of the present invention includes a surface light source 20 for uniformly illuminating a liquid crystal panel. In the present invention, as the surface light source 20, in order to maximize the function of the prism sheet (the function of deflecting the emitted light from the surface light source and correcting the direction of the emitted light from the prism-shaped protrusions to the front direction of the liquid crystal display device) ), using a surface light source with specific light emission characteristics (light distribution characteristics).

More specifically, with reference to FIG. 4 , the surface light source used in the present invention will be in the plane W perpendicular to the ridge line direction of the prism-shaped protrusions that the prism sheet has, the normal direction T of the light exit surface of the surface light source and When the angle formed by the emission direction M of the emitted light of the surface light source is defined as the emission angle θ (where -90°≤θ≤90°), the light intensity of the surface light source that represents the emission angle dependence of the light intensity of the emitted light The distribution satisfies the following (1) and (2).

(1) In the range of -80°≤θ<-40° or 40°<θ≤80°, the maximum value of the light intensity has the highest peak.

(2) When the angle of the maximum value of the light intensity in the highest peak showing the maximum value of the above-mentioned light intensity is θa, and the angle showing 1/2 of the maximum value of the light intensity in the above-mentioned peak is θb, Satisfy the following formula [1]:

|θa-θb|<30° [1].

It should be noted that the range that the emission angle θ can adopt is -90°≤θ≤90°. The so-called θ=0° means that the direction M of the emitted light from the surface light source is the same direction as the normal direction T of the light emitting surface of the surface light source. The so-called θ=-90° means that in the plane W, the direction M of the emitted light from the surface light source forms an angle of 90° counterclockwise (or clockwise) with respect to the normal direction T, and the so-called θ=90° means In the plane W, the direction M of the emitted light from the surface light source forms an angle of 90° clockwise (or counterclockwise) with respect to the normal direction T. FIG.

When the light with the emission direction M (the absolute value of the emission angle θ is relatively large) that deviates greatly from the normal direction T of the light exit surface of the surface light source enters into the prism-shaped protrusion 13a that the prism sheet has, as in FIG. 5 It is schematically shown that the incident light reaches the hypotenuse P of the prism-shaped protrusion 13a, is reflected by the hypotenuse P, and thus can be focused on the front direction of the liquid crystal display device (the normal direction T of the light exit surface of the surface light source). ). That is, in a liquid crystal display device using a rear side polarizing plate provided with a prism sheet, such a device having an emission direction M that deviates greatly from the normal direction T of the light emission surface of the surface light source (the absolute value of the emission angle θ is relatively large) ) light contributes to greatly improving the brightness and contrast in the front direction of the liquid crystal display device.

The present inventors found that: especially in the plane W, in the range of -80°≤θ<-40° or 40°<θ≤80° (that is, the absolute value |θ| of the emission angle θ is 40°<| θ|≤80°), the surface light source that shows the maximum value of the light intensity has the light intensity distribution characteristic of the highest peak [satisfying the above condition (1)], and the light constituting the peak is effectively concentrated on the liquid crystal by the prism sheet The front direction of the display device (the normal direction T of the light exit surface of the surface light source), so it is extremely effective to improve the brightness and contrast of the front direction of the liquid crystal display device. It should be noted that the lower limit and upper limit of the emission angle θ considered in the above condition (1) are respectively set to -80° and 80° because it is difficult to accurately measure the light intensity at an angle exceeding the lower limit and the upper limit. Useful.

The highest peak of the maximum value of the above-mentioned light intensity is preferably located within the range of 50°≤|θ|≤80°, more preferably within the range of 60°≤|θ|≤80°.

On the other hand, the inventors of the present invention also found that the width (width) of the highest peak of the maximum value of the above-mentioned light intensity also affects the brightness and contrast in the front direction of the liquid crystal display device. That is, in the light intensity distribution of the surface light source on the plane W, the angle of the light intensity maximum value displayed in the highest peak of the above-mentioned light intensity maximum value is θa, and the light intensity maximum value in the peak is shown as When the angle of 1/2 of the value is set to θb, if the half-value width |θa-θb| is less than 30° [the above condition (2) is satisfied], it will not be greatly affected by light with a relatively small absolute value of the angle θ The luminance and contrast in the front direction of the liquid crystal display device can be improved by condensing light whose emission angle is in the vicinity of θa as the main emitted light. On the other hand, when the half-value width |θa-θb| is 30° or more or when θb does not exist (for example, the peak is extremely gentle and becomes a maximum value in the range of -80°≤θ≤80° 1/2 dots do not exist on the peak), light components with a relatively small absolute value of the emission angle θ near the foot of the highest peak constituting the maximum value of the above-mentioned light intensity increase, and as a result, the prism sheet is bent to The light components in directions other than the front direction of the liquid crystal display device (the normal direction T of the light exit surface of the surface light source) increase, so there is a tendency that the brightness and contrast in the front direction of the liquid crystal display device cannot be sufficiently improved. The half-value width |θa-θb| is preferably 25° or less.

The light intensity distribution of the surface light source in the plane W may have any light distribution characteristics as long as it satisfies the above (1) and (2), but preferably there is no significant peak in the range of the emission angle -40° to 40°. This is because there is a tendency that such peaks are not properly collected by the prism sheet in the front direction of the liquid crystal display device.

Here, a plurality of planes may be used as the plane W perpendicular to the ridgeline direction of the prism-shaped protrusions, but in the present invention, at least one of the planes W may satisfy the above (1) and (2). However, in order to achieve sufficiently high brightness and contrast over the entire surface of the liquid crystal display device, it is preferable to satisfy the above (1) and (2) in any two or more planes W perpendicular to the ridgeline direction of the prism-shaped protrusions.

The light intensity distribution of the surface light source can be obtained by measuring the luminance of the surface light source using a commercially available luminance measuring device.

As the surface light source, a direct type light source using a diffuser plate, an edge type light source using a light guide plate, etc. can be used, but in order to realize the above-mentioned light distribution characteristics, it is preferable to use a light source with a light guide plate 22 and a light source as shown in FIG. 1 . The edge type light source (surface light source 20 ) of the light source device 21 arranged on the side of the light guide plate 22 . As the light guide plate 22 , for example, a plate-shaped or wedge-shaped member formed of transparent resin such as acrylic resin can be used. A pattern is added to the back surface or both surfaces of the light guide plate by screen printing using ink, etching, or jetting. In addition, microreflective elements, microrefractive elements, etc. having a reflective function may be formed on the back surface or both surfaces of the light guide plate. Desired light distribution characteristics can be obtained by appropriately adjusting the shapes or elements of the back surface or both surfaces of these light guide plates. More specifically, for example, "Chapter 4 of the Latest Technology of Liquid Crystal Backlight" published by Toray Research Center Co., Ltd. and "Backlight Technology for Liquid Crystal Display Part 2, Chapter 1, Chapter 4" published by CMC Publishing Co., Ltd. The light source device described in Chapter 1 of this chapter.

As the light source device 21 , a light source device in which point light sources such as LEDs are arranged in a line, or a light source device including rod-shaped light sources such as cold cathode tubes, can be used. In the liquid crystal display device of the present invention, the surface light source may have one light source device disposed on one side of the light guide plate, or two light source devices disposed on opposite sides of the light guide plate.

The edge-type light source is preferably arranged parallel or substantially parallel to the ridgelines of the prism-shaped protrusions of the prism sheet. With such an arrangement, the light emitted by the edge-type light source is most effectively collected by the prism sheet.

In the liquid crystal display device of the present invention, for configurations other than those described above, conventionally known appropriate configurations can be employed. For example, the liquid crystal display device of the present invention may further include a light diffusion plate, a light diffusion sheet, a reflection plate, and the like.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples.

(Manufacturing example 1: Production of polarizing film)

A polyvinyl alcohol film with an average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more, and a thickness of 75 μm is immersed in pure water at 30°C, and then immersed in pure water at a weight ratio of iodine/potassium iodide/water of 0.02 at 30°C. /2/100 in the aqueous solution. Then, it immersed in the aqueous solution whose weight ratio of potassium iodide/boric acid/water was 12/5/100 at 56.5 degreeC. Next, after washing|cleaning with 8 degreeC pure water, it dried at 65 degreeC, and obtained the polarizing film which polyvinyl alcohol adsorb|sucked iodine and orientated iodine. Stretching is mainly carried out in the process of iodine dyeing and boric acid treatment, and the total stretching ratio is 5.3 times.

(Manufacturing example 2: Preparation of ultraviolet curable adhesive)

10.0 g of hydrogenated epoxy resin-trade name "EPIKOTEYX8000" produced by Japan Epoxy Resin Co., Ltd. (diglycidyl ether of nuclear hydrogenated bisphenol A, with an epoxy equivalent of about 205 g/equivalent), Nippon Soda Co., Ltd. Take 4.0 g of the photocationic polymerization initiator-trade name "CI5102" manufactured by the company, and 1.0 g of the photosensitizer-trade name "CS7001" manufactured by Nippon Soda Co., Ltd. into a 100-ml disposable cup, mix and defoam , so as to prepare a UV-curable adhesive.

(Manufacturing example 3: Production of prism sheet 1)

On a mold designed in advance to form prism-shaped protrusions (isosceles triangle in cross-sectional shape) with a pitch of 50 μm and an apex angle of 65°, molten polypropylene resin was applied, and pressure was applied while heating. Next, it cooled to 60 degreeC immediately after peeling off from a mold, and obtained the prism sheet 1 which consists of polypropylene resin. All prism-like protrusions have the same shape as designed. The refractive index of the prism sheet 1 is 1.49.

(Manufacturing example 4: Production of prism sheet 2)

The pitch of the prism-shaped protrusions (isosceles triangle shape in cross-section) designed to be molded in advance is 50 μm, and the prism apex angle is 65° on the mold, and the ultraviolet curable resin composition having the composition shown below is coated, After smoothing the surface, a polyethylene terephthalate film having a thickness of 188 μm was superimposed on the layer formed of the ultraviolet curable resin composition. Next, ultraviolet rays having a wavelength of 320 to 390 nm were irradiated so that the cumulative irradiation amount became 1000 mJ/cm ² to cure the ultraviolet curable resin composition. Thereafter, the prism sheet 2 in which the cured product layer of the ultraviolet curable resin composition having prism-shaped protrusions was laminated on a polyethylene terephthalate film was obtained by peeling from the mold. All prism-like protrusions have the same shape as designed. The refractive index of the prism-shaped protrusions of the prism sheet 2 is 1.54.

[Composition of the ultraviolet curable resin composition used in Production Example 4]

FANCRYL FA-321M (Ethylene oxide modified bisphenol A methacrylate manufactured by Hitachi Chemical Co., Ltd.) 45 parts by weight

NK ESTER A-BPE-4 (ethylene oxide modified bisphenol A diacrylate manufactured by Shin Nakamura Chemical Co., Ltd.) 25 parts by weight

Sartomer 285 (tetrahydrofurfuryl acrylate manufactured by Sartomer Company) 30 parts by weight

Darocur 1173 (2-hydroxyl-2-methyl-1-phenylpropane-1-one manufactured by Ciba company) 3 parts by weight

<Example 1>

(A) Production of polarizers

On one side of the polarizing film obtained in Production Example 1, the prism sheet 1 obtained in Production Example 3 was bonded with the surface opposite to the prism surface through the ultraviolet curable adhesive obtained in Production Example 2. to fit. In addition, a triacetyl cellulose film (80 μm, manufactured by Konica Minolta Opto Co., Ltd.) was bonded to the other surface of the polarizing film via the ultraviolet curable adhesive obtained in Production Example 2. Next, it was passed through an ultraviolet irradiation device manufactured by Nippon Battery Co., Ltd. (the ultraviolet lamp uses "HAL400NL" at 80 W, and the irradiation distance is 50 cm) once at a linear velocity of 1.0 m/min to obtain a polarizing plate with a good appearance. The curability of the ultraviolet curable adhesive which is an epoxy resin composition is good. In addition, the adhesiveness of the prism sheet 1 was evaluated by the checkerboard method described in JIS K 5400. As a result, the number of non-peeling checkerboards was 100/100 with respect to the number of checkerboards formed, showing good adhesiveness. A layer of an acrylic adhesive having a thickness of 25 μm was provided on the outer surface of the triacetyl cellulose film of the polarizing plate.

(B) Fabrication of liquid crystal display device

The above-mentioned polarizing plate was arranged on the back surface of the liquid crystal cell through an acrylic adhesive layer, and a commercially available polarizing plate was arranged on the front surface of the liquid crystal cell to assemble a liquid crystal panel. This liquid crystal panel was combined with a surface light source A (used in VAIO VGN-FE32B/W manufactured by Sony Corporation) of a light guide plate type (edge light source) to prepare a liquid crystal display device. When the display of the liquid crystal display device was observed visually, a bright image was seen from the front, and the visibility was good. The light intensity distribution of the surface light source A measured using EZContrast (LX88W manufactured by ELDIM) is shown in FIG. 6 .

<Example 2>

A polarizing plate was produced in the same manner as in Example 1 except that the prism sheet 2 obtained in Production Example 4 was used instead of the prism sheet 1 obtained in Production Example 3, and a liquid crystal display device was produced next.

When the display of the liquid crystal display device was observed visually, a bright image was seen from the front, and the visibility was good.

<Comparative example 1>

A liquid crystal display device was produced in the same manner as in Example 1 except that surface light source B (used in Flexscan EV2411W-H manufactured by NANAO Co., Ltd.) was used instead of surface light source A using a light guide plate method (edge light source). When the display of the liquid crystal display device was observed visually, the image viewed from the front was dark, the contrast was low, and the visibility was poor. The light intensity distribution of the surface light source B measured with EZContrast (LX88W manufactured by ELDIM) is shown in FIG. 7 .

<Comparative example 2>

Except having used the prism sheet 2 obtained by the manufacture example 4 instead of the prism sheet 1 obtained by the manufacture example 3, it carried out similarly to the comparative example 1, and produced the liquid crystal display device. When the display of the liquid crystal display device was observed visually, the image viewed from the front was dark, the contrast was low, and the visibility was poor.

Table 1 summarizes the θa, θb and |θa-θb| values obtained from the light intensity distribution of the surface light sources used in the above Examples and Comparative Examples, and the visibility evaluation results of the manufactured liquid crystal display devices. The brightness and contrast of the liquid crystal display device were obtained by measuring the central portion of the liquid crystal display device from the front using EZContrast (LX88W manufactured by ELDIM) in a dark room. The light intensity distribution (brightness distribution) of the liquid crystal display devices produced in Example 1 and Comparative Example 1 is shown in FIG. 8 and FIG. 9 . It should be noted that "-" in the "θb" column of Table 1 means that in the highest peak of the maximum value of the light intensity, there is no 1 that becomes the maximum value within the range of -80°≤θ≤80°. /2 points.

[Table 1]

It should be understood that the embodiment and Examples disclosed this time are illustrative and not restrictive in any points. The scope of the present invention is indicated by the claims rather than the above description, and all changes within the technical solutions and protection scope equivalent to the claims are included in the scope.

Symbol Description

1, 2: Polarizer

3: LCD unit

10: LCD panel

12: Polarizing film

13: Prism sheet

13a: Prism protrusions

14, 16: Adhesive layer

15: resin film

17: Adhesive layer

20: surface light source

21: Light source device

22: Light guide plate

100: liquid crystal display device

W: A plane perpendicular to the ridgeline direction of the prism-shaped protrusions

T: the normal direction of the light exit surface of the surface light source

M: The direction of the light emitted by the surface light source

θ: The angle formed by the normal direction of the light exit surface of the surface light source and the emission direction of the light emitted by the surface light source (exit angle)

P: Hypotenuse of prism-like protrusions

α: Vertex angle of prism-like protrusions

Claims (5)

1. a liquid crystal indicator is made up of area source and liquid crystal panel, and said liquid crystal panel is disposed on the said area source and possesses liquid crystal cells and be laminated in the polaroid on the face of area source side of said liquid crystal cells,

Said polaroid possesses light polarizing film and prismatic lens, and said prismatic lens is situated between and is laminated in the surface of said light polarizing film and is had the surface that is made up of the prism-like projection by adhesive phase,

It is opposed that said prismatic lens is configured to said surface and the said area source that is made up of the prism-like projection,

Will with the crest line direction plane orthogonal of said prism-like projection in, when angle that the ejaculation direction of the ejaculation light of the normal direction of the light emergence face of said area source and said area source forms is made as and penetrates angle θ; The light intensity distributions of the dependent said area source of ejaculation angle of representing the light intensity of said ejaculation light satisfies following (1) and (2); Wherein,-90 ° of θ≤90 °

(1) in the scope of-80 ° of θ＜-40 ° or 40 °＜θ≤80 °, the maximum value of light intensity has the top,

When 1/2 the angle that the angle that (2) will show the light intensity maximum value in the said peak is made as θ a, will show light intensity maximum value in the said peak is made as θ b, satisfy following formula [1]:

|θa-θb|＜30° [1]。

2. liquid crystal indicator according to claim 1, wherein, said area source comprises LGP and the light supply apparatus that is configured in the side of said LGP.

3. liquid crystal indicator according to claim 2, wherein, said light supply apparatus is that point source of light is arranged in the light supply apparatus of wire or comprises the light supply apparatus of bar-shaped light source,

Said light supply apparatus is configured to said prismatic lens: said light supply apparatus or almost parallel parallel with the crest line of said prism-like projection.

4. according to each described liquid crystal indicator in the claim 1～3, wherein, said light supply apparatus is configured in one side of said LGP or relative both sides.

5. according to each described liquid crystal indicator in the claim 1～4, wherein, the apex of said prism-like projection is more than 60 °.

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