JP2004094062A - Optical film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which a light emitting means is hardly scratched, surrounding scenery is not easily reflected, optical path of light beams made incident on a liquid crystal display panel from a side surface is efficiently converted in a visible direction, the thickness and the weight are reduced, luminance is made high, and easily visible display is provided. <P>SOLUTION: In the liquid crystal display device, a light path control layer 13 is made light transmissive and has a light emitting means on one surface. The means is made by discontinuously distributing a plurality of minute recessed sections A which are provided with an optical path converting slope "a" having an inclination angle of 35 to 48 degrees with respect to a flat surface. On the forming surface of the light emitting means, an anti-glare layer 11 is adhered through a transparent adhesive layer 12. An optical film 10 with a light path conversion slope of ≥70% made no contact with the layer 12, is adhered to the visible side of the liquid crystal display panel through the adhesive layer so that the antiglare layer side is exposed to outer side. The liquid crystal display panel is made of a reflection system which is provided with a light reflecting layer and a liquid crystal layer which modulates light beams through electric field. <P>COPYRIGHT: (C)2004,JPO

Description

【０１１０】
表より、例１、２が明るさに優れていることが判る。また光学フィルムにおける光出射手段を形成する微小凹部の断面を顕微鏡で観察したところ、例１ではほぼ溝部分に一致して空気層が観察されて凹部内に粘着層が侵入していないことが判り、例３、４、５では凹部における空気との界面の面積が小さくなっていて粘着層が凹部内に侵入していることが判った。
【０１１１】
一方、例１、３、４、５では外景の映り込みがなくて防眩効果に優れると共に、表面にも傷付きが殆どなくて良好であったが、アンチグレア層のない例２では外景の映り込みで液晶表示が非常に見にくく、表面の傷付きも激しくて液晶表示の判読が困難であった。
【０１１２】
また例１では照明・外光の両モードにおいて、パネル全面での明るさ及びその均一性に優れる表示であった。以上より、本発明にて従来のサイドライト型導光板の使用による嵩高化、高重量化を回避しつつ、光学フィルムを配置した液晶表示パネルの側面に光源を設けるだけで、面発光が可能な薄型軽量で、かつ防眩性や耐擦傷性が良好な液晶表示装置を形成できることがわかる。
【図面の簡単な説明】
【図１】光学フィルムの説明側面図
【図２】光出射手段の説明平面図
【図３】他の光出射手段の説明平面図
【図４】液晶表示装置の説明側面図
【符号の説明】
１０：光学フィルム
１１：アンチグレア層
１２：接着層
１３：光路制御層
Ａ：微小凹部
ａ：光路変換斜面
１４：支持フィルム
２０、３０：セル基板
４０：液晶層
５１：光源[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical film capable of efficiently changing the optical path of light incident from a side surface of a liquid crystal display panel in a viewing direction to form a liquid crystal display device that is thin, lightweight, bright, has little image disturbance, and is easy to view.
[0002]
BACKGROUND OF THE INVENTION
Conventionally, a reflection type liquid crystal display device of a front light type in which a side light type light guide plate is arranged on the viewing side of a liquid crystal display panel causes an increase in thickness and weight. There has been known a reflection type liquid crystal display device in which incident light from a side surface direction is reflected through a rough surface through a viewing-side cell substrate and can be used as illumination light (JP-A-5-158033).
[0003]
However, there is a problem that it is difficult to obtain a bright display because the reflected light through the rough surface is used as illumination light. That is, such reflected light is strongly reflected in the regular reflection direction with respect to the light transmission direction, and the light intensity decreases in a normal distribution with respect to the angle. Therefore, the reflected light is strongly emitted in a direction greatly inclined from the front direction of the liquid crystal display panel. However, there is a problem that the display is dark in the normal viewing direction in the front direction.
[0004]
In view of the above, an optical film having light emitting means in which continuous prism-shaped concave portions are arranged in a stripe shape is adhered to the surface of the liquid crystal display panel, and incident light or light transmitted from a light source disposed on the side of the panel is transmitted. A method of illuminating a liquid crystal display panel by reflecting the light through the light emitting means has also been proposed (Japanese Patent Application Laid-Open No. 2000-147499). However, there is a problem that the light emitting means is easily scratched at the time of panel manufacture or the like, and a view of the external light such as a fluorescent lamp is reflected to lower the visibility of the liquid crystal display.
[0005]
Technical Problems of the Invention
The present invention is directed to a liquid crystal display device in which the light emitting means is not easily scratched and the scene is hardly reflected, and the light incident from the side of the liquid crystal display panel is efficiently converted in the optical path in the viewing direction to be thin, light, bright, and easy to view. It is an object of the present invention to develop an optical member capable of forming the optical member.
[0006]
[Means for solving the problem]
The present invention relates to a light-transmitting light-path control layer having a light-transmitting means on one side, wherein a plurality of minute concave portions having an optical path changing slope having an inclination angle of 35 to 48 degrees with respect to a plane are discontinuously distributed. An optical film, characterized in that an anti-glare layer is adhered to the surface on which the means is formed via a transparent adhesive layer, and 70% or more of the optical path conversion slope is not in contact with the adhesive layer, and an optical film thereof. The film is bonded to the viewing side of the liquid crystal display panel via an adhesive layer such that the anti-glare layer side is on the outside, and the liquid crystal display panel includes a light reflection layer and a liquid crystal layer that modulates light through an electric field. It is an object of the present invention to provide a liquid crystal display device comprising a reflection type provided.
[0007]
【The invention's effect】
According to the present invention, by incorporating the optical film into the liquid crystal display panel, it is possible to prevent the reflection of the scenery due to external light such as a fluorescent lamp or the like, and light incident from the side of the panel can be efficiently transmitted through the optical path changing slope of the light emitting means. In addition, the optical path can be changed in the panel direction with good directivity, and based on this, a liquid crystal display device can be formed that is thin, light, bright, and has a surface that is not easily damaged and is easy to see.
[0008]
That is, the anti-glare layer prevents the light emitting means from being scratched at the time of manufacturing or using the panel, and also prevents the minute concave portion from being clogged with foreign matter and the scene due to external light being reflected. Further, the light path-converted light passing through the light emitting means is incident on the panel without passing through the anti-glare layer and maintains its directivity at a high level. Further, it is possible to suppress the adhesive layer from entering the minute recesses forming the light emitting means, and the reflection of the side incident light or the transmitted light through the optical path changing slope is maintained at a high level, and the brightness is hardly reduced, and the liquid crystal display Is prevented from becoming dark.
[0009]
If the anti-glare layer is not provided in the above, the light emitting means is easily damaged by scratching the surface at the time of manufacture or the like, and foreign matter is easily clogged in the concave portion forming the light emitting means. The scratches and clogging of foreign matter change the total reflection condition of the optical path conversion slope, lower the directivity of the reflected light, and darken the liquid crystal display. If the anti-glare layer is not provided, the visibility of the liquid crystal display is reduced due to the reflection of the scenery due to external light such as a fluorescent lamp. Further, when the light path-converted light passing through the light emitting means enters the panel via the antiglare layer, the directivity is greatly reduced due to the diffusion of the light, and the luminance in the front direction is reduced.
[0010]
In addition, even if the adhesive layer adheres to the concave portion forming the light emitting means, the total reflection condition of the optical path conversion slope changes, and the directivity of the reflected light decreases, and the liquid crystal display becomes dark. When the size of the concave portion forming the light emitting means and the angle of the slope thereof are large, the adhesive layer for bonding the anti-glare layer tends to enter. By the way, in the light emitting means having the prism-shaped concave portions whose slopes have the apex angle of about 135 degrees adjacent to each other in the form of stripes, the above-mentioned problem occurs because the adhesive layer easily penetrates.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The optical film according to the present invention is a light-transmissive optical path control layer having a light emitting means on one side in which a plurality of minute concave portions having an optical path conversion slope having an inclination angle of 35 to 48 degrees with respect to a plane are discontinuously distributed. An anti-glare layer is adhered to the surface on which the light emitting means is formed via a transparent adhesive layer, and 70% or more of the optical path conversion slope is not in contact with the adhesive layer. An example is shown in FIG. Reference numeral 10 denotes an optical film, 11 denotes an antiglare layer, 12 denotes an adhesive layer, 13 denotes an optical path control layer, A denotes a minute concave portion, and a denotes an optical path conversion slope. 14 is a transparent support film, 15 is an adhesive layer, and 16 is a release sheet.
[0012]
The optical path control layer 13 has its anti-glare layer 11 in the direction along the panel plane of the liquid crystal display panel having the light source 51 on the side face, as illustrated by the polygonal arrow α in FIG. The incident light or the transmitted light from the side by the light source is reflected through the optical path changing slope a, and the light path is changed to the panel side, that is, the viewing direction of the liquid crystal display panel, and the light is emitted. An object of the present invention is to make it possible to use emitted light as illumination light (display light) for a liquid crystal display panel or the like.
[0013]
For the purpose of obtaining the above-described emission characteristics, the optical path control layer is provided with an optical path conversion slope a having an inclination angle θ1 of 35 to 48 degrees with respect to the plane formed by the optical film as in the example of FIG. Thus, the incident light or the transmitted light (arrow) from the side direction by the light source disposed on the side surface of the liquid crystal cell or the like is converted into the optical path to the back side through the optical path changing slope a to direct the light in the normal direction to the liquid crystal cell or the like. Light having excellent properties can be emitted from the optical film with good utilization efficiency of light from the light source.
[0014]
If the inclination angle of the light path conversion slope is less than 35 degrees, when a light reflection layer is arranged on the back side of a liquid crystal cell or the like and the light path conversion light is reflected, display light based on the reflected light is emitted from the liquid crystal display panel. The angle is more than 30 degrees, which is disadvantageous for visual recognition. On the other hand, when the inclination angle of the optical path conversion slope exceeds 48 degrees, light is easily leaked from the slope without being totally reflected, and the light use efficiency is reduced.
[0015]
In the above case, when the scattering method using the light emitting means having a roughened surface is used instead of the reflection method using the optical path conversion slope, the light is hardly reflected in the vertical direction, and the direction is greatly inclined from the front direction of the liquid crystal display panel. And the liquid crystal display is dark and the contrast is poor.
[0016]
Efficient total reflection of the side incident light or its transmission light through the optical path changing slope, and the direct emission from the optical film in the direction of the normal to the plane formed by the optical film. From the viewpoint of achieving the liquid crystal display, the preferable inclination angle θ1 of the optical path conversion slope is 38 to 45 degrees, particularly 40 to 44 degrees.
[0017]
The surface that forms the minute concave portion and does not satisfy the optical path conversion slope a having a predetermined inclination angle, for example, the upright surface b facing the optical path conversion slope a in FIG. It does not contribute to emission from the back surface, and preferably does not affect display quality, light transmission or light emission as much as possible. Incidentally, when the inclination angle θ2 of the upright surface with respect to the plane formed by the optical film is small, the projected area of the upright surface with respect to the plane becomes large, and as shown in FIG. In the light mode, surface reflected light from the upright surface returns to the viewing direction, which tends to impair display quality.
[0018]
Therefore, the larger the inclination angle θ2 of the vertical surface or the like is, the more advantageous it is. As a result, the projection area with respect to the plane formed by the optical film can be reduced, and the decrease in the total light transmittance can be suppressed. Also, the apex angle due to the optical path changing slope and the upright surface can be reduced, the surface reflected light can be reduced, and the reflected light can be inclined in the plane direction of the optical film, thereby suppressing the influence on the liquid crystal display. From such a point, the preferable inclination angle θ2 of the upright surface or the like is 50 degrees or more, particularly 60 degrees or more, particularly 70 to 90 degrees.
[0019]
The shape or the like of the intermittent end of the minute concave portion is not particularly limited, but from the viewpoint of suppressing the influence of the reduction of the incident light to the portion, ± 30 degrees or more, particularly ± 45 degrees or more with respect to the plane. In particular, it is preferable to form a slope (including a vertical plane) inclined at ± 60 to 90 degrees.
[0020]
The minute concave portion can be formed in an appropriate form having one or two or more optical path changing slopes, for example, a minute concave part having a form such as a triangle to a pentagon based on a cross section with respect to the optical path changing slope. By the way, in the example of FIG. 1, the small concave portion having the triangular cross section including the optical path changing slope a and the vertical surface b having the large inclination angle θ2 is shown, but the small concave portion having the isosceles triangular cross section having the two light path converting slopes a. And so on. It should be noted that the polygon of the cross section is not strictly meaning, and deformations such as a change in the angle of the surface and a circularization of the angle formed by the intersection of the surfaces are allowed.
[0021]
The concave shape is advantageous from the viewpoints of the utilization efficiency of the side incident light and the difficulty of damage. Further, the triangular form is advantageous based on the cross section with respect to the optical path conversion slope from the viewpoint of reduction in visibility due to miniaturization of the size and reduction in manufacturing efficiency. Note that the minute concave portion means a concave portion (groove) in the optical path control layer.
[0022]
As illustrated in the plan views of FIGS. 2 and 3, the plurality of minute concave portions are formed for the purpose of miniaturization and further thinning of the optical path control layer, and the plurality of minute concave portions are distributed in a discontinuous and intermittent manner. Light emitting means is provided on one side of the optical path control layer. With the single-sided arrangement, the side-incident light can be intensively emitted from the side of the optical path control layer having no light emitting means via the optical path conversion slope.
[0023]
The distribution state of the plurality of minute recesses forming the light emitting means can be appropriately determined according to the form of the minute recesses and the like, and may be distributed in parallel based on, for example, the optical path conversion slope. , May be irregularly distributed as in the example of FIG. Further, as shown in the example of FIG. 3, the distribution may be arranged concentrically with respect to the virtual center.
[0024]
When the size of the micro-recess is large, such as the optical path conversion slope, the existence of the slope can be easily recognized by an observer, the display quality can be easily reduced, and the uniformity of illumination with respect to the liquid crystal cell can be easily reduced. Further, since the adhesive layer for bonding the anti-glare layer also easily penetrates, the length of the optical path conversion slope is 10 to 500 μm, especially 20 to 350 μm, particularly 50 to 200 μm, and the depth and width of the minute concave portion are 2 to 100 μm. It is preferably from 4 to 70 μm, particularly preferably from 10 to 40 μm.
[0025]
Further, from the viewpoint of the reflection efficiency by the optical path conversion slope, the length of the optical path conversion slope is preferably 5 times or more, more preferably 8 times or more, and particularly preferably 10 to 100 times the depth of the minute recess. The length is the length in the long side direction of the optical path conversion slope, and the depth is based on the surface on which the light emitting means is formed. The width is based on the length in a direction orthogonal to the long side direction and the depth direction of the optical path conversion slope.
[0026]
The slope forming the minute concave portion A may be formed in an appropriate surface form such as a straight surface, a refraction surface, and a curved surface. Also, the cross-sectional shape of the minute concave portion may be such that the inclination angle or the like is constant throughout the light emitting means, or may be reduced on the optical film by coping with absorption loss and attenuation of transmitted light due to previous optical path conversion. For the purpose of making the light emission uniform, the minute concave portion may be made larger as the distance from the side surface on the light incident side increases.
[0027]
In addition, it is also possible to form minute concave portions with a constant pitch, and as shown in FIGS. 2 and 3, the pitch is gradually narrowed as the distance from the side on which light is incident (arrow) increases, so that the distribution density of the minute concave portions increases. It can also be done. Furthermore, the light emission on the optical film can be made uniform at a random pitch. The random pitch is more advantageous than preventing moiré due to interference with pixels. Therefore, the minute concave portion may be formed of a combination of components having different shapes and the like in addition to the pitch.
[0028]
The distribution density of the minute concave portions forming the light emitting means is such that the light path changing slope a reflects the incident light from the side direction by the light source in the illumination mode and changes the light path, so that the total light transmittance is increased. Is 75% to 92% and the haze is 4% to 20%. When the haze is 4% to 20%, the light from the side direction through the light source is converted into an optical path to obtain a surface light source that efficiently illuminates the liquid crystal cell, and is bright and excellent in contrast. It is more preferable to achieve a liquid crystal display.
[0029]
The characteristics of the total light transmittance and the haze are, for example, that the occupied area on the light emitting means forming surface based on the projected area of all the minute concave portions is 1/100 to 1/8, especially 1/50 to 1/10, especially It can be achieved by setting the ratio to 1/30 to 1/15. Further, the area of the light path conversion slope occupying the light emitting means forming surface is 1 to 20%, particularly 3 to 18%, from the viewpoint of the incidence rate of the external light in the external light mode and the prevention of disturbance of the display image by the light emitting means. Particularly, 5 to 15% is preferable.
[0030]
In the above description, it is preferable that the light path conversion slope in the minute concave portion faces the direction (arrow) of light to be incident from the side of the liquid crystal display panel or the like, as shown in FIG. Therefore, when a linear light source is used, it is preferable that the optical path conversion slope is directed to one side of the optical film or a fixed direction as illustrated in FIG. When a point light source such as a light emitting diode is used, it is preferable that the optical path conversion slope faces the direction of the light emission center of the point light source as in the example of FIG.
[0031]
The front surface and the back surface of the optical path control layer are flat surfaces B as smooth as possible except for the minute concave portions as shown in the example of FIG. Is preferably a flat surface. It is preferable that the angle change is within 1 degree per 5 mm in length. By using such a flat surface B, most of the optical path control layer can be made a smooth surface with an angle change of 2 degrees or less, and the efficiency of light transmitted inside the liquid crystal display panel can be improved as indicated by the broken line arrow γ in FIG. It can be used well and achieve uniform light emission without disturbing the image.
[0032]
As described above, the light emitting means in which the minute concave portions A are concentrically arranged as illustrated in FIG. 3 is such that a point light source is disposed on a side surface or a corner of a liquid crystal display panel, and a side surface formed by the point light source. Radial incident light from the same direction or its transmitted light is subjected to optical path conversion through the optical path conversion slope a to make the optical film emit light as uniformly as possible, and has excellent directivity in the normal direction to the liquid crystal cell and the like. An object of the present invention is to emit light from an optical film with high efficiency of using light from a light source.
[0033]
Therefore, the concentric arrangement is preferably performed such that a virtual center is formed on the end face or corner of the optical path control layer or on the outside thereof so that the point light source can be easily arranged. One or more virtual centers can be formed on the same or different end faces or corners of the optical path control layer. The corners of the liquid crystal display panel, the liquid crystal cell, and the cell substrate on which the point light sources are arranged may be subjected to a chamfering process in order to facilitate the arrangement.
[0034]
The optical path control layer can be formed by an appropriate method using a light-transmitting material. By the way, as an example, a method of transferring a shape by pressing a transparent film made of a thermoplastic resin under heating to a mold capable of forming a predetermined light emitting means, a thermoplastic resin heated and melted, or a heat or solvent A method of filling a transparent resin fluidized through a mold into a mold capable of forming a predetermined light emitting means, a transparent liquid resin, a monomer or an oligomer which can be polymerized with heat, ultraviolet rays, or radiation such as an electron beam. And a method of filling or casting into a mold capable of forming a predetermined light emitting means and performing a polymerization treatment.
[0035]
In addition, a transparent liquid resin or a monomer or oligomer which can be polymerized by heat, ultraviolet rays, or radiation such as an electron beam is coated on a transparent film, and the coated layer is pressed against a mold capable of forming a predetermined light emitting means. A method of performing a polymerization treatment after molding, filling the above-mentioned liquid resin or the like into a mold capable of forming a predetermined light emitting means, placing a transparent film in close contact with the filling layer, and irradiating with ultraviolet light or radiation. A method of performing a polymerization treatment is also included.
[0036]
In the method using the transparent film described above, a transparent support film 14 and a separate optical path control layer 13 added thereto are formed as shown in the example of FIG. In this case, if the refractive index difference between the added optical path control layer and the support film is large, the emission efficiency may be greatly reduced due to interface reflection or the like.
[0037]
Therefore, from the viewpoint of suppressing the decrease in the emission efficiency, it is preferable that the difference in the refractive index between the optical path control layer and the support film is made as small as possible, preferably within 0.10, particularly within 0.05. . In that case, it is preferable to make the refractive index of the optical path control layer added higher than that of the support film from the viewpoint of emission efficiency.
[0038]
For forming the optical path control layer, an appropriate light transmitting material according to the wavelength range of the incident light, for example, a transparent resin represented by an acrylic resin, a polycarbonate resin, a cellulose resin, a norbornene resin, a polyolefin resin, or the like. For example, a curable resin that can be polymerized by heat such as acrylic, urethane, acrylic urethane, or silicone, or by radiation such as ultraviolet rays or electron beams can be used.
[0039]
In the method using a film, a method in which the formed optical path control layer and the film are separated from each other after a polymerization treatment using a film treated with a release agent or the like can also be employed. In that case, the film used need not be transparent. The thickness of the optical path control layer is preferably 5 to 300 μm, more preferably 10 to 200 μm, and particularly preferably 20 to 100 μm, from the viewpoint of reducing the thickness and weight. The optical path control layer may be subjected to anti-reflection treatment or the like as necessary.
[0040]
As shown in the example of FIG. 1, the anti-glare layer 11 adhered to the light path control layer 13 on the surface on which the light emitting means is formed via the transparent adhesive layer 12 has the object of preventing visual impairment due to surface reflection of external light. It also functions as a protective layer for preventing the means from being damaged. As the antiglare layer, an appropriate one according to the related art can be used, and there is no particular limitation.
[0041]
Therefore, a film whose surface is roughened by an appropriate roughening method such as a sand blasting method or an embossing method can be used, but a method in which a resin containing transparent particles is coated on the film from the viewpoint of production efficiency and the like. A film in which the surface has a fine uneven structure by a method of forming a resin containing transparent particles into a film or the like can be preferably used.
[0042]
The transparent particles, for example, silica and alumina, titania and zirconia, tin oxide and indium oxide, inorganic particles that may also be conductive such as cadmium oxide and antimony oxide, and organic particles such as a crosslinked or uncrosslinked polymer One or more suitable materials such as the above may be used. The average particle size is generally 0.01 to 20 μm, but is not limited thereto.
[0043]
The antiglare layer is preferably made of an optically isotropic material from the viewpoint of preventing optical influence on transmitted light. Further, it is preferable that the refractive index is lower than that of suppressing the surface reflection and suppressing the incidence of transmission light in the optical path control layer. The thickness of the antiglare layer is preferably from 5 to 300 μm, more preferably from 10 to 200 μm, particularly preferably from 20 to 100 μm, from the viewpoint of reducing the thickness and weight. The anti-glare layer can be subjected to anti-reflection treatment or the like.
[0044]
Preferably, a low refractive index layer is interposed between the antiglare layer and the optical path control layer. With the interposition of the low refractive index layer, it is possible to suppress the incident light from the side direction or the transmitted light from entering the anti-glare layer from the optical path control layer, and to suppress the influence on the illumination light and the decrease in the contrast to visually recognize the liquid crystal display. Performance can be improved. The low refractive index layer has a refractive index smaller than the refractive index of the optical path control layer, and has a refractive index difference of 0.02 or more, preferably 0.03 to 0.15, particularly 0.05 to 0.10. Preferably, it can be formed of an appropriate substance such as a fluorine compound.
[0045]
Further, the low refractive index layer can also serve as a transparent adhesive layer for bonding the antiglare layer and the optical path control layer. The adhesive layer can be provided on one or both of the antiglare layer and the optical path control layer. For forming the adhesive layer, for example, an appropriate material such as an adhesive that is cured by irradiation with ultraviolet rays or radiation or by heating can be used, and there is no particular limitation.
[0046]
An adhesive layer can be preferably used from the viewpoint of handleability such as simple adhesiveness and stress relaxation property for suppressing generation of internal stress. In particular, the pressure-sensitive adhesive layer can be preferably used for adhesion treatment between the optical path control layer made of a film and the anti-glare layer.
[0047]
For forming the adhesive layer, for example, an adhesive using a suitable polymer as a base polymer such as a rubber-based, acrylic-based, vinyl alkyl ether-based or silicone-based, polyester-based or polyurethane-based, polyether-based, polyamide-based, or styrene-based polymer Can be used. Among them, those excellent in transparency, weather resistance, heat resistance and the like, such as an acrylic pressure-sensitive adhesive containing a polymer mainly containing an alkyl ester of acrylic acid or methacrylic acid as a base polymer, are preferably used.
[0048]
The bonding treatment between the antiglare layer and the optical path control layer is performed such that 70% or more of the optical path conversion slope of the minute concave portion forming the light emitting means is not in contact with the adhesive layer. This is to maintain the function of the light path conversion slope, and when the light path conversion slope comes into contact with the adhesive layer, the total reflection condition of the light path conversion slope changes, and the directivity when the incident light from the side direction or its transmitted light is reflected. And the liquid crystal display becomes dark. Therefore, the non-contact state preferably has a value as high as 80% or more, particularly 90% or more, of the optical path conversion slope.
[0049]
The non-contact can be achieved by preventing or suppressing the intrusion of the adhesive layer into the minute concave portion forming the light emitting means.From that point, in particular, from the point of suppressing the intrusion by pressure during bonding. Means that the storage elastic modulus at 20 ° C. is 5 × 10 ⁴ N / m ² Above, especially 10 ⁵ N / m ² Above, especially 10 ⁶ -10 ¹⁰ N / m ² An adhesive layer, particularly an adhesive layer, can be advantageously used. In addition, it is preferable that the adhesive layer has a large loss modulus of elasticity, in order to prevent intrusion in a long-time adhesive state.
[0050]
Further, the thickness of the adhesive layer is preferably 25 μm or less, more preferably 1 to 20 μm, particularly preferably 5 to 15 μm, from the viewpoint of the balance between the prevention of intrusion and the adhesive strength. The elastic modulus of the adhesive layer or the adhesive layer can be controlled by, for example, the degree of crosslinking with a crosslinking agent. In some cases, the adhesive layer is cured by, for example, a method of irradiating an ultraviolet ray, an electron beam, or the like, and the elastic modulus can be increased to stabilize the adhesive layer.
[0051]
Therefore, in the case of the adhesive layer, the one whose elastic modulus is hardly reduced by heating or the like or the one whose elastic modulus is high even at high temperature can be preferably used. The adhesive layer may be of a light diffusion type by containing one or more suitable transparent particles such as those exemplified above.
[0052]
As shown in the example of FIG. 1, a transparent adhesive layer 15 for adhering to another member such as a liquid crystal cell, in particular, an adhesive layer can be provided on the optical film on the side having no anti-glare layer 11 as necessary. The adhesive layer or pressure-sensitive adhesive layer can conform to the above. It is preferable to temporarily cover the adhesive layer with a release film 16 for the purpose of preventing foreign matter from entering, as shown in the figure, until the adhesive layer is put to practical use.
[0053]
Further, the optical film may have a form in which a polarizing plate or the like is laminated via an adhesive layer on a side having no antiglare layer. In this case, it is preferable that the optical path control layer is formed of a transparent film from the viewpoint of adhesive treatment properties and the like. Examples of the polarizing plate include a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, an ethylene-vinyl acetate copolymer-based partially saponified film, and a dichroic property such as iodine or a dichroic dye. Examples include a polarizing film that is drawn by adsorbing a substance.
[0054]
A polarizing plate that can be preferably used from the viewpoint of reducing the difference in transmittance depending on the wavelength and neutralizing the color of light transmitted inside the liquid crystal display panel to suppress coloring of illumination light has a wavelength range of 450 to 700 nm. The minimum value / maximum value of the transmittance at every 10 nm is 0.80 or more, especially 0.85 or more, particularly 0.90 or more.
[0055]
The polarizing plate may be provided with a transparent protective layer on one or both sides of a polarizing film. The transparent protective layer can be formed using one or two or more kinds of appropriate materials exhibiting transparency according to the wavelength range of light incident via a light source or the like. Incidentally, as the material for visible light, those exemplified for the above-mentioned optical path control layer, among which those having excellent transparency, mechanical strength, heat stability, moisture shielding property, etc., are preferably used.
[0056]
From the standpoint of obtaining a liquid crystal display device with less display unevenness by suppressing luminance unevenness and color unevenness, preferred transparent protective layers do not show birefringence or have low birefringence, especially, the average in-plane retardation. Is 30 nm or less. By using a transparent protective layer having a small retardation, when linearly polarized light is incident, its polarization state can be favorably maintained, which is advantageous for preventing deterioration of display quality. From the viewpoint of preventing display unevenness, the in-plane preferable average retardation of the transparent protective layer is 20 nm or less, particularly 15 nm or less, and particularly 10 nm or less, and the dispersion of the retardation at each location is as small as possible. More preferred.
[0057]
Further, a transparent protective layer made of a material having a small photoelastic coefficient is preferable from the viewpoint of suppressing internal stress which is likely to be generated in the transparent protective layer by the bonding treatment and preventing generation of a phase difference due to the internal stress. Further, the average retardation in the thickness direction of the transparent protective layer is preferably 50 nm or less, more preferably 30 nm or less, and particularly preferably 20 nm or less from the viewpoint of preventing display unevenness and the like.
[0058]
The transparent protective layer having a low retardation can be formed by an appropriate method such as a method of annealing an existing film or a method of removing internal optical distortion. A preferred forming method is a method of forming a transparent protective layer having a small retardation by a casting method. The retardation in the transparent protective layer is preferably based on light in the visible region, particularly light having a wavelength of 550 nm.
[0059]
The above-mentioned average phase difference in the plane is defined by (nx−ny) × d, and the average phase difference in the thickness direction is defined by {(nx + ny) / 2−nz} × d. Where nx is the average refractive index in the in-plane maximum refractive index direction, ny is the average refractive index in the direction orthogonal to the nx direction in the plane, nz is the average refractive index in the thickness direction of the transparent protective layer, and d is transparent. It means the average thickness of the protective layer.
[0060]
The transparent protective layer may be formed as a single layer, or may be formed as a laminate made of the same or different materials. The transparent protective layer can also be used as a support film for integrating the optical path control layer. The transparent protective layer provided with the light emitting means is integrally formed, and the transparent protective layer having the light emitting means in the same body is advantageous for reducing the thickness of the optical film.
[0061]
The thickness of the transparent protective layer is from 5 to 300 μm, preferably from 10 to 200 μm, particularly preferably from 20 to 100 μm, from the viewpoint of reducing the thickness and weight. The transparent protective layer can be bonded to the polarizing film using an appropriate transparent adhesive such as a polyvinyl alcohol-based one. In the case where the transparent protective layer has a light emitting means, an adhesive treatment with an appropriate transparent pressure-sensitive adhesive such as acrylic or rubber is preferable.
[0062]
The optical film according to the present invention is arranged such that, through the light emitting means (optical path changing slope), the incident light from the side direction by the light source or the transmitted light is transmitted through the optical path in a direction (normal direction) excellent in verticality advantageous for visual recognition. The light is converted and emitted with high light use efficiency. In addition, it can exhibit good transparency to external light. Furthermore, it has excellent scratch resistance.
[0063]
Accordingly, for example, various devices such as a bright and easy-to-view thin and light reflective type, particularly a liquid crystal display device of a front light type for both external light and illumination can be formed. FIG. 4 shows an example of the reflection type and front light type liquid crystal display device. Reference numerals 20 and 30 denote cell substrates in a liquid crystal cell, 40 denotes a liquid crystal layer, and 31 denotes a light reflection layer.
[0064]
As shown in the figure, the front light type liquid crystal display device can be formed as having the optical film 10 on the viewing side of the liquid crystal display panel 100 such that the antiglare layer side is on the outside. In that case, it is preferable that the optical film adheres to a liquid crystal cell or the like via an adhesive layer from the viewpoint of achieving a bright display.
[0065]
As shown in the drawing, one or two or more illuminating mechanisms are provided on one or more side surfaces or corners of the liquid crystal display panel, particularly on one or more side surfaces or corners of the cell substrate 20 on which the optical film 10 is disposed. It can be formed by arranging more than two light sources 51. In the case of an optical film having a light emitting means composed of minute concavities arranged in a concentric arrangement in the formation thereof, the light emission in a concentric arrangement is achieved from the point that a bright display is achieved by efficiently utilizing radial incident light from a point light source. It is preferable to arrange a point light source on the side of the liquid crystal display panel on a vertical line including the virtual center of the means.
[0066]
In such an arrangement of the point light source corresponding to the virtual center, the point light source of the cell substrate 20 as shown in the example of FIG. 4 depends on whether the virtual center of the light emitting means is located at the end face of the optical film or outside thereof. An appropriate countermeasure such as a method of protruding the side on which the light source is arranged can be adopted. The same applies to the case where another light source such as a linear light source is arranged.
[0067]
As a light source arranged on the side surface of the liquid crystal display panel, an appropriate light source can be used. For example, in addition to the above-mentioned point light sources such as light-emitting diodes, linear light sources such as (cold and hot) cathode tubes, arrays of point light sources arranged in a line or a plane, or point light sources and linear conductors A combination of light plates for converting incident light from a point light source into a linear light source via a linear light guide plate can be preferably used.
[0068]
The light source is preferably disposed on the side of the panel where the optical path conversion slope of the optical film faces, from the viewpoint of emission efficiency. Including the concentric arrangement described above, by arranging the optical path conversion slope so as to face the light source as perpendicularly as possible, the incident light from the side surface via the light source can be efficiently converted to a surface light source. As a result, light can be emitted with high efficiency.
[0069]
Therefore, in the case of an optical film having light emitting means composed of minute concave portions having a plurality of optical path conversion slopes, such as an optical film having two optical path conversion slopes such as an isosceles triangle in cross section, the cell substrate is opposed to the cell substrate. It is also possible to arrange a number of light sources corresponding to a plurality of optical path changing slopes, such as both side surfaces. In the case of the concentric arrangement, a point light source may be arranged at one or more positions corresponding to the virtual center of the light emitting means on the optical film.
[0070]
The light source enables visual recognition in an illumination mode by lighting the light source. In the case of a liquid crystal display device for both external light and illumination, there is no need to turn on the light source when viewing in the external light mode using external light. , Can be switched on and off. An arbitrary method can be adopted as the switching method, and any of the conventional methods can be adopted. Note that the light source may be of a different color emission type capable of switching emission colors, or may be of a type capable of emitting different colors through different types of light sources.
[0071]
As shown in the example of FIG. 4, the light source 51 may be a combination body in which appropriate auxiliary means such as a reflector 52 surrounding the light source 51 are arranged to guide the divergent light to the side surface of the liquid crystal display panel, if necessary. . As the reflector, an appropriate reflection sheet such as a resin sheet, a white sheet, or a metal foil provided with a metal thin film having a high reflectance can be used. The reflector can also be used as a fixing means that also serves as a surrounding of the light source by a method in which the end is bonded to an end of a cell substrate or the like.
[0072]
In general, a liquid crystal display device appropriately assembles components such as a liquid crystal cell functioning as a liquid crystal shutter, a driving device associated therewith, a front light or a backlight (optical film), and a light reflection layer and a retardation plate as necessary. It is formed by things. In the present invention, there is no particular limitation except that an illumination mechanism is formed by using the above-described optical film and light source, and it can be formed according to a conventional front light type or backlight type.
[0073]
Therefore, the liquid crystal cell to be used is not particularly limited, and the liquid crystal 40 is sealed between the cell substrates 20 and 30 through the sealing material 41 as shown in the figure, and display light is obtained through light control by the liquid crystal and the like. A suitable reflection type, transmission type, semi-transmission type, or the like can be used.
[0074]
Incidentally, specific examples of the liquid crystal cell include twisted and non-twisted types such as TN type liquid crystal cell, STN type liquid crystal cell, IPS type liquid crystal cell, HAN type liquid crystal cell, OCB type liquid crystal cell and VA type liquid crystal cell, and guest host type. And a ferroelectric liquid crystal cell or a light diffusion type liquid crystal cell such as an internal diffusion type. The liquid crystal driving system may be an appropriate one such as an active matrix system or a passive matrix system.
[0075]
In a reflection type liquid crystal display device, a device having a liquid crystal layer that modulates light through an electric field, such as a TN type or STN type liquid crystal cell, is preferably used. In this case, the optical film having the light emitting means is generally disposed on the viewing side of the liquid crystal display panel as in the example of FIG. 4 to form a front light type liquid crystal display device. Driving of the liquid crystal is usually performed through electrodes 21 and 31 provided inside the cell substrate as in the example of FIG.
[0076]
In a reflection type liquid crystal display device, the arrangement of a light reflection layer is essential. Regarding the disposition position, it can be provided inside the liquid crystal cell as illustrated in FIG. 4 or can be provided outside the liquid crystal cell. Therefore, in the example of FIG. 4, the electrode 31 also serves as a light reflection layer. The reflection type liquid crystal display device according to the present invention can be generally used as an external light / illumination type.
[0077]
For the light reflecting layer, for example, a coating layer containing a powder of a high-reflectance metal such as aluminum, silver, gold, copper, or chromium in a binder resin, an attached layer of a metal thin film by a vapor deposition method, or the like, It can be formed as an appropriate light reflecting layer according to the related art, such as a reflection sheet in which the base layer supports the additional layer, a metal foil, a transparent conductive film, and a dielectric multilayer film.
[0078]
When an electrode 31 serving also as a light reflection layer is provided inside a liquid crystal cell as in the example of FIG. 4, in order to enable liquid crystal display, the cell substrate 20 and the electrode 21 on the viewing side are made of a transparent substrate or a transparent substrate. Although it is necessary to form the electrodes and the like so as to transmit light, the cell substrate 30 on the back side does not need to be transparent like the light reflection layer 31, and may be formed of an opaque body. . In the case where a light reflection layer is provided outside the liquid crystal cell, it is a rear-side cell substrate provided with a transparent electrode on a transparent substrate in order to enable liquid crystal display.
[0079]
The thickness of the cell substrate forming the liquid crystal cell is not particularly limited, and can be appropriately determined according to the sealing strength of the liquid crystal, the size of the light source to be arranged, and the like. Generally, the thickness is set to 10 μm to 5 mm, particularly 50 μm to 2 mm, particularly 100 μm to 1 mm from the viewpoint of the balance between light transmission efficiency and thinness and lightness.
[0080]
The thickness of the cell substrate may be different between the side where the light source is disposed and the side where the light source is not disposed, or may be the same thickness. It is advantageous to increase the thickness of the cell substrate on which the light source is arranged, rather than to improve the luminance. Therefore, when the light sources are arranged on the side surfaces of the cell substrates on the viewing side and the back side, it is advantageous to use the same thickness of the cell substrates.
[0081]
When forming a liquid crystal cell, as necessary, as shown in the example of FIG. 4, alignment films 22, 32 such as a rubbing film for aligning liquid crystal, a color filter 23 for realizing color display, and a low refractive index layer 24. And a polarizing plate 25, a retardation plate 26, and the like. In general, the alignment film is disposed adjacent to the liquid crystal layer, and the color filter is disposed between the cell substrate and the electrode.
[0082]
The low-refractive-index layer described above interfacially reflects the incident light from the side direction through the light source as illustrated by the broken line β in FIG. 4 and efficiently transmits the light in the direction away from the light source, and changes the optical path at the rear. Light is efficiently incident on the slope, and the object is to improve the brightness uniformity over the entire panel display surface. The low-refractive-index layer can be formed as a transparent layer made of an appropriate low-refractive-index material made of an inorganic or organic substance such as a fluorine compound or a silicone-based polymer.
[0083]
The position of the low-refractive-index layer is preferably on the inside of the cell substrate 20 where the light source 51 is disposed as shown in the example of FIG. 4, that is, on the surface opposite to the optical film-attached side of the substrate, from the viewpoint of improving display brightness. . Further, a low refractive index layer having a refractive index of 0.01 or more, especially 0.02 to 0.15, particularly 0.05 to 0.10 lower than that of the cell substrate is preferable from the viewpoint of improving display brightness. Therefore, when light sources are disposed on the side surfaces of both the cell substrate on the viewing side and the rear surface side, it is preferable to provide a low refractive index layer on both of the cell substrates.
[0084]
When forming the liquid crystal display device, a liquid crystal display panel to which one or more appropriate optical layers such as a polarizing plate, a light diffusion layer, and a retardation plate are added can be provided as necessary. Such an additional optical layer such as a polarizing plate, a light diffusing layer, or a retardation plate can be applied to a liquid crystal cell as an integral body laminated with an optical film via an adhesive layer, if necessary.
[0085]
The above-mentioned polarizing plate can be arranged at an appropriate position on one or both of the viewing side and the back side of the liquid crystal cell for the purpose of controlling display light via linearly polarized light. The light diffusion layer aims at expanding the display range by diffusing the display light, making the luminance uniform by leveling the emission, and increasing the amount of light incident on the optical film by diffusing the transmission light in the liquid crystal cell. The light diffusion layer can be provided by an appropriate method such as a coating layer having a surface fine unevenness conforming to the above anti-glare layer, a diffusion sheet, or the like.
[0086]
In addition, the light diffusion layer may be provided as a layer also serving as an adhesive layer by blending transparent particles into the adhesive layer. According to this, the thickness of the liquid crystal display device can be reduced. One or two or more light diffusion layers can be arranged at appropriate positions such as between the optical film and the cell substrate on the viewing side.
[0087]
On the other hand, the phase difference plate aims at forming an antireflection layer composed of a circularly polarizing plate or an elliptically polarizing plate in cooperation with the polarizing plate, and for expanding the viewing angle and preventing coloring by optical compensation. The retardation plate may be composed of one or more layers, and is usually arranged between the polarizing plate on the viewing side and / or the back side and the cell substrate as shown in FIG.
[0088]
As the retardation plate, a retardation plate exhibiting an appropriate retardation according to the above-mentioned purpose or the type of the liquid crystal cell can be used. Generally, a material exhibiting a phase difference of 50 to 700 nm is used. Incidentally, by using a quarter-wave plate having a phase difference of, for example, 100 to 150 nm, the above-mentioned circularly polarizing plate can be formed. In this case, the wavelength region functioning as a circularly polarizing plate can be expanded by using a half-wave plate having a phase difference of, for example, 200 to 300 nm.
[0089]
The retardation plate is, for example, a birefringent film obtained by stretching a film made of an appropriate transparent polymer by an appropriate method such as uniaxial or biaxial, an oriented film of an appropriate liquid crystal polymer such as a nematic or discotic or The alignment layer can be obtained as one supported on a transparent substrate. A film in which the refractive index in the thickness direction is controlled under the action of the heat shrink force of the heat shrinkable film may be used.
[0090]
When forming the liquid crystal display device, the optical film is formed through the transparent adhesive layer from the viewpoint of the reflection efficiency through the optical path changing slope a of the minute concave portion A, and the improvement of the luminance by the effective use of the incident light from the side direction. It is preferably bonded to an adjacent member such as a substrate. In this case, when another optical layer is positioned between the optical film and the cell substrate, it is necessary that those optical layers are also tightly integrated with an adjacent member via an adhesive layer or the like in view of the above-described improvement in brightness and the like. More preferred.
[0091]
From the viewpoint of suppressing the total reflection and increasing the incidence efficiency of the cell substrate transmission light to the light emitting means in the above, and obtaining a liquid crystal display device that is bright and has excellent uniformity, a preferable adhesive layer is more preferable than an optical path control layer. It has a refractive index of 0.02 or more and a refractive index higher or close to that of the cell substrate of the liquid crystal cell.
[0092]
Incidentally, when the refractive index is lower than that of the cell substrate of the liquid crystal cell, the incident light from the side surface is easily subjected to total reflection during the transmission. As the cell substrate, a resin plate is generally used as an optical glass plate, and its refractive index is about 1.51 to 1.52 in the case of an alkali-free glass plate, and about 1.50 to 1.51 in the case of an epoxy resin plate. Ideally, most of the transmitted light having an angle that can enter the optical path control layer from the cell is totally reflected at the bonding interface by ideally bonding through an adhesive layer having a higher refractive index. It is possible to make it incident without making it.
[0093]
From the standpoint of improving the display brightness and the uniformity of in-plane brightness by suppressing the loss of light that cannot be emitted by the confinement effect based on total reflection, between the light-transmitting optical layers such as the adhesive layer and the cell substrate, etc. The preferred refractive index difference at each interface is within 0.15, preferably within 0.10, especially within 0.05. Therefore, the preferable refractive index of the adhesive layer is 1.49 or more, preferably 1.50 or more, particularly 1.51 or more. Therefore, it is preferable that the adhesive layer for adhering the optical film to the liquid crystal cell or the like also satisfies the above-mentioned refractive index condition.
[0094]
In the reflection type liquid crystal display device illustrated in FIG. 4 described above, the visual recognition by both external light and illumination is performed by the light emitted from the back surface of the optical film 10 as indicated by an arrow α in the illumination mode in which the light source 51 is turned on. Is reflected by the light reflection layer 31 through the liquid crystal cell, then passes through the inside of the liquid crystal cell in reverse to reach the optical film, and display light transmitted from portions other than the minute concave portions A (light emitting means) is visually recognized. You.
[0095]
On the other hand, in the external light mode by turning off the light source, light incident from a portion other than the light emitting means of the optical film 10 reaches the optical film via the light reflecting layer 31 and reversely through the liquid crystal cell according to the above. Display light transmitted through portions other than the light emitting means is visually recognized.
[0096]
In the present invention, the components forming the above-described liquid crystal display device may be wholly or partially laminated and integrated and fixed, or may be arranged in an easily separable state. It is preferable that the optical film and the liquid crystal cell are in a fixed and adhered state, at least from the viewpoint of preventing a decrease in contrast by suppressing interfacial reflection and the like. An appropriate transparent adhesive such as a pressure-sensitive adhesive can be used for the fixing treatment, and the transparent adhesive layer can contain transparent particles and the like to form an adhesive layer having a diffusion function.
[0097]
In addition, the above-mentioned formed parts, especially those on the viewing side, are treated with an ultraviolet absorbent such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, a nickel complex salt compound, etc. Can also be provided.
[0098]
【Example】
Reference example
Magnesium fluoride is deposited on a non-alkali glass plate having a refractive index of 1.52 to form a low-refractive-index layer, plasma-treated in an argon atmosphere, and then indium-tin-oxide (ITO) transparent thereon A conductive layer was formed by a sputtering method, a polyvinyl alcohol solution was spin-coated thereon, and the dried film was subjected to a rubbing treatment to obtain a cell substrate on the viewing side and the back side.
[0099]
Then, the cell substrates on the viewing side and the back side are opposed to each other so that the rubbing surfaces thereof are orthogonal to each other in a rubbing direction, and a gap adjusting material made of spherical glass beads is provided. Liquid crystal (a mixture of 1 part by weight of a chiral agent (MC-32, manufactured by Merck) into 200 parts by weight of E-7: 200 parts by weight, manufactured by BDH) was formed to form a liquid crystal cell.
[0100]
Example 1
An ultraviolet-curable acrylic resin is applied to a thickness of about 100 μm on a 60 μm-thick transparent film made of polycarbonate (PC), and the applied layer is brought into close contact with a mold previously processed into a predetermined shape by a rubber roller. At the same time, after extruding excess resin and air bubbles, the resin was irradiated with ultraviolet rays from a metal halide lamp, cured, peeled from the mold and cut into a predetermined size, and the PC film was peeled to obtain an optical path control layer. Its refractive index was 1.515.
[0101]
The light path control layer is a 30 mm square light having a length of about 100 μm, a width of about 10 μm, and a plurality of small triangular recesses (FIG. 1) having a triangular cross section that are distributed in parallel and irregularly with one side. It has an emission means (FIG. 2), and the inclination angle of the optical path changing slope is 41 degrees, and the inclination angle of the upright surface is 78 degrees. The optical path conversion slope faces the parallel side. In addition, the area of the flat surface formed by portions other than the light emitting means is 12 times or more the sum of the optical path changing slope and the vertical surface. Further, the total light transmittance and haze of the optical path control layer were 89% and 7%, respectively.
[0102]
Next, the storage elastic modulus at 20 ° C. was 1.8 × 10 4 on the light emitting means forming surface of the optical path control layer. ⁵ N / m ² After bonding an anti-glare layer via an acrylic adhesive having a refractive index of 1.468, a polyvinyl alcohol film-based polarizing plate is pressure-bonded to the side having no anti-glare layer via an acrylic adhesive layer having a refractive index of 1.523. It was pressure-bonded with a roller to obtain an optical film with a polarizing plate. The anti-glare layer had a haze of 20%, and was formed by applying an ultraviolet-curable resin containing silica having an average particle diameter of 3 μm to one surface of a triacetyl cellulose film, and curing the resin with ultraviolet light. Things.
[0103]
Then, the optical film was bonded to the viewing side of the liquid crystal cell obtained in Reference Example via the adhesive layer having a refractive index of 1.523 with the anti-glare layer side as the outside, and then the polarization having a light reflection layer on the back side of the cell was obtained. The plates were similarly bonded to obtain a reflective liquid crystal display device. In the above, no intrusion of the adhesive layer was found in the minute concave portions forming the light emitting means.
[0104]
Example 2
A reflective liquid crystal display device was obtained according to Example 1, except that an optical film to which an antiglare layer was not adhered was used.
[0105]
Example 3
The storage elastic modulus at 20 ° C. is 3 × 10 on the light emitting means forming surface of the optical path control layer. ⁴ N / m ² A reflective liquid crystal display device was obtained in the same manner as in Example 1 except that an optical film having an antiglare layer bonded thereto via an acrylic adhesive having a refractive index of 1.468 was used.
[0106]
Example 4
A reflective liquid crystal display device was obtained in the same manner as in Example 1, except that an optical path control layer having an inclination angle of the optical path conversion slope of 33 degrees was used.
[0107]
Example 5
A reflection type liquid crystal display device was obtained in the same manner as in Example 1, except that an optical path control layer having a width of the minute concave portion of about 30 μm was used.
[0108]
Evaluation test
A cold cathode tube is arranged on the side of the cell substrate on the viewing side of the reflection type liquid crystal display device obtained in the above example, surrounded by a polyester film of silver deposition, and the film end is adhered to the upper and lower surfaces of the cell substrate with a double-sided adhesive tape. With the cold-cathode tube held and fixed, the cold-cathode tube is turned on in a dark room with no voltage applied to the liquid crystal cell, and the luminance at the angle showing the maximum luminance at a position 15 mm from the incident side surface is measured with a luminance meter (Topcon And BM7). In addition, the presence or absence of reflection of the scenery due to external light on the surface of the liquid crystal display device, and the surface of the liquid crystal display device (antiglare layer surface) were abraded, and the surface was observed to determine whether or not there was any damage.
[0109]
The results are shown in the following table.

[0110]
From the table, it can be seen that Examples 1 and 2 are excellent in brightness. In addition, when the cross section of the minute concave portion forming the light emitting means in the optical film was observed with a microscope, it was found that in Example 1, the air layer was observed almost in line with the groove portion, and the adhesive layer did not enter the concave portion. In Examples 3, 4 and 5, it was found that the area of the interface with the air in the concave portion was small, and the adhesive layer had penetrated into the concave portion.
[0111]
On the other hand, in Examples 1, 3, 4, and 5, there was no reflection of the outside scene and the anti-glare effect was excellent, and the surface was scarcely damaged. As a result, the liquid crystal display was very difficult to see and the surface was severely scratched, making it difficult to read the liquid crystal display.
[0112]
In Example 1, the display was excellent in brightness and uniformity over the entire panel in both the illumination mode and the external light mode. As described above, according to the present invention, bulk lightening by using the conventional sidelight type light guide plate, while avoiding weight increase, only by providing a light source on the side surface of the liquid crystal display panel on which the optical film is disposed, surface light emission is possible. It can be seen that a liquid crystal display device which is thin and lightweight and has good anti-glare properties and scratch resistance can be formed.
[Brief description of the drawings]
FIG. 1 is an explanatory side view of an optical film.
FIG. 2 is an explanatory plan view of a light emitting unit.
FIG. 3 is an explanatory plan view of another light emitting unit.
FIG. 4 is an explanatory side view of a liquid crystal display device.
[Explanation of symbols]
10: Optical film
11: Anti-glare layer
12: adhesive layer
13: Optical path control layer
A: Micro concave
a: Optical path conversion slope
14: Support film
20, 30: Cell substrate
40: Liquid crystal layer
51: Light source

Claims (13)

Forming surface of the light emitting means in a light transmitting optical path control layer having on one side a light emitting means in which a plurality of minute concave portions having an optical path changing slope having an inclination angle of 35 to 48 degrees with respect to a plane are discontinuously distributed. An optical film comprising an antiglare layer adhered thereon via a transparent adhesive layer, and 70% or more of the optical path conversion slope is not in contact with the adhesive layer. The optical film according to claim 1, further comprising an adhesive layer on a side having no antiglare layer. The optical film according to claim 2, wherein the adhesive layer is an adhesive layer. The optical film according to any one of claims 1 to 3, wherein the minute concave portion forming the light emitting means has a triangular shape based on a cross section of the light path changing slope. The length of the optical path changing slope in the long side direction of the minute concave part forming the light emitting means is 10 to 500 μm, 5 times or more the depth of the minute concave part, and the depth and width of the minute concave part are two or more. An optical film having a thickness of 100 μm. The optical film according to claim 4 or 5, wherein a surface facing the optical path changing slope in the minute concave portion forming the light emitting means is an upright surface having an inclination angle of 60 to 90 degrees with respect to a plane. 7. An optical film according to claim 4, wherein the minute recesses forming the light emitting means are arranged in parallel or irregularly based on the optical path changing slope, or concentrically with respect to the virtual center. The optical film according to any one of claims 1 to 7, wherein the adhesive layer for bonding the optical path control layer and the anti-glare layer comprises an adhesive layer. The optical film according to claim 1, further comprising a low refractive index layer having a refractive index smaller than that of the optical path control layer by 0.02 or more between the optical path control layer and the antiglare layer. The optical film according to claim 9, wherein the low refractive index layer is an adhesive layer. The optical film according to claim 1, wherein a storage elastic modulus at 20 ° C. of an adhesive layer that bonds the optical path control layer and the antiglare layer is 5 × 10 ⁴ N / m ² or more. The optical film according to any one of claims 1 to 11, wherein the optical path control layer is made of a transparent film, and has a polarizing plate via an adhesive layer on a side having no antiglare layer. The optical film according to any one of claims 1 to 12, which is adhered to a viewing side of a liquid crystal display panel via an adhesive layer such that an antiglare layer side thereof is on the outside, wherein the liquid crystal display panel has a light reflection layer and an electric field. A liquid crystal display device comprising a reflection type having a liquid crystal layer that modulates light through the liquid crystal layer.

Images