JP3930316B2 - Polarized light source device and liquid crystal display device - Google Patents

Description

【０１３３】
表より、実施例では比較例と比べて、正面輝度の減衰率及び色相の変化が小さいことが判る。所定の偏光度と透過率を示す偏光板を用いることにより、光源からの距離が増大するにつれて生じる正面輝度の低下を減少させて輝度の均一性を高めることができ、また所定の平行及び直交のａ値とｂ値を示す偏光板を用いることにより、光源からの距離が増大するにつれて色相が変化する現象を抑制できて色ムラを低減できることが判る。
【図面の簡単な説明】
【図１】実施例の説明側面図
【図２】液晶表示装置の説明側面図
【符号の説明】
１：偏光面光源装置
１Ａ：光路制御層
Ａ：光出射手段
ａ：光路変換斜面
１Ｂ：偏光板
１Ｃ：透明基板
２０、３０：セル基板
４０：液晶層
５１：照明装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polarization plane light source device suitable for forming a liquid crystal display device having excellent luminance uniformity and color characteristics.
[0002]
BACKGROUND OF THE INVENTION
Conventionally, an optical film provided with a light emitting means is adhered to the viewing side surface of the liquid crystal display panel, and incident light from a light source disposed on the side of the panel or its transmitted light is reflected through the light emitting means to obtain a liquid crystal display panel. A liquid crystal display device designed to illuminate has been known (Japanese Patent Laid-Open No. 2000-147499). This overcomes the difficulties of increasing the bulk and weight when using a surface light source device composed of a sidelight type light guide plate, and enables a reduction in thickness and weight, making it easier to reduce the thickness than a transmissive type. This is the advantage of the liquid crystal display device.
[0003]
However, in the form of a polarization plane light source device in which a polarizing plate is disposed between the optical film provided with the light emitting means and the liquid crystal cell, when light is incident from the side of the panel through the light source, the distance from the light source is increased. There is a problem that the front luminance decreases, the hue of the emission color changes, and the display unevenness increases.
[0004]
[Technical Problem of the Invention]
The present invention solves the above-described problem of attenuation of front luminance and display unevenness due to the change in hue of light emission color in a form having a polarizing plate, and efficiently allows light incident from the side surface of the liquid crystal display panel to be in the optical path in the viewing direction. It is an object of the present invention to develop a polarization plane light source device that can be converted into a thin, light, bright, easy-to-view liquid crystal display device.
[0005]
[Means for solving problems]
  The present invention has an optical path control layer on at least a polarizing plate on the surface side of a transparent substrate having a lighting device on a side surface, and the polarizing plate has a transmittance of 45% or more.,sideLuminous intensity 96% or more,flatRow a value -0.4 to -0.3, orthogonal a value 16 to 18, parallel b value -0.7 to 0,as well asOrthogonal b value -57 to -54Satisfactory, the polarization plane light source device characterized in that the optical path control layer has a plurality of light emitting means comprising an optical path conversion slope for reflecting incident light from the side surface of the transparent substrate toward the back surface of the transparent substrate, And a polarizing plane light source device provided on one or both of the viewing side and the back side of the liquid crystal display panel.
[0006]
In the parallel a value, the orthogonal a value, the parallel b value, and the orthogonal b value of the polarizing plate, the parallel indicates that the absorption axes of the pair of polarizing plates are parallel, and the orthogonal indicates that the absorption axes of the pair of polarizing plates are orthogonal. The a value and b value mean the chromaticness index in the color system by Hunter's Lab space.
[0007]
【The invention's effect】
According to the present invention, by using the polarizing plate showing the transmittance and the polarization degree as described above, the further away from the incident side surface of the transparent substrate on which the illumination device is arranged, that is, the incident light or the transmitted light is transmitted through the polarizing plate. As the number of opportunities increases, it is possible to suppress a decrease in front luminance, and it is possible to obtain a polarization plane light source device that is excellent in uniformity of front luminance. Further, by using the polarizing plate showing the parallel and orthogonal a value and b value, it is possible to suppress a change in hue of the emitted color from becoming farther away from the incident side surface, and to obtain a polarization plane light source device with less color unevenness. be able to.
[0008]
Furthermore, the polarization plane light source device of the present invention can also be used as a cell substrate of a liquid crystal cell. By incorporating a polarization plane light source device into a liquid crystal display panel as a cell substrate, light incident from the side surface of the cell substrate is efficiently and highly directional through an optical path conversion slope having a predetermined inclination angle of the optical path control layer. It is possible to form a liquid crystal display device that can change the optical path in the viewing direction, is thin, light and bright, has little display unevenness, and is easy to see.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
  The polarization plane light source device according to the present invention has an optical path control layer at least through a polarizing plate on the surface side of a transparent substrate having a lighting device on a side surface, and the polarizing plate has a transmittance of 45% or more.,sideLuminous intensity 96% or more,flatRow a value -0.4 to -0.3, orthogonal a value 16 to 18, parallel b value -0.7 to 0,as well asOrthogonal b value -57 to -54Satisfied, the optical path control layer comprises a plurality of light emitting means having an optical path converting slope for reflecting incident light from the side surface of the transparent substrate in the back surface direction of the transparent substrate.
[0010]
The above example is shown in FIGS. 1 is a polarization plane light source device, 1C is a transparent substrate, 1B is a polarizing plate, 1A is an optical path control layer, and 51 is an illumination device. A is the light emitting means, and a is the optical path changing slope. FIG. 2 shows a liquid crystal display device.
[0011]
As the transparent substrate, an appropriate one according to a conventional cell substrate or light guide plate made of one kind or two or more kinds of resins or glass can be used, and there is no particular limitation. By the way, examples of the resin include acetate resin, polyester resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, polyether resin, and polyvinyl chloride. Cellulose resins, styrene resins, norbornene resins, acrylic resins, urethane resins, acrylic urethane resins, epoxy resins, silicone resins, etc., and radiation curable resins such as ultraviolet rays and electron beams It is done.
[0012]
Among them, those having excellent transparency such as curable resins such as epoxy resins from the viewpoint of heat resistance and white glass against blue sheet glass are preferable from the viewpoint of transmission of illumination light and transmission of display light. In addition, a resin having a small photoelastic coefficient is preferable. Furthermore, the phase difference is as small as possible, such as optical isotropy and surface smoothness, because birefringence in the light transmission direction and thickness direction is suppressed as much as possible to reduce optical loss and color unevenness. What is excellent in is preferable.
[0013]
The thickness of the transparent substrate is not particularly limited and can be appropriately determined according to the strength according to the purpose of use. In the case of a cell substrate or a light guide plate, a thickness of 20 μm to 5 mm, especially 50 μm to 3 mm, especially 100 μm to 2 mm is generally used from the standpoint of balance between strength of liquid crystal encapsulation, light transmission efficiency and thin and light weight. Is. It is more advantageous that the cross-sectional area is larger than the point of the optical transmission substrate than the point of incidence efficiency, transmission efficiency, and the like. On the other hand, it is more advantageous that it is thinner than the point of reducing the thickness and weight.
[0014]
The transparent substrate may be the same thick plate or may have partially different thicknesses. For example, a part with a partially different thickness, such as a wedge-shaped cross section in the transmission direction, is due to an increase in incident efficiency of transmitted light on the inclined path of the optical path due to the inclined arrangement of the light emitting means. Sometimes it is advantageous.
[0015]
  As a polarizing plate, the transmittance is 45% or more,sideLuminous intensity is 96% or more,flatRow a value is -0.4 to -0.3, orthogonal a value is 16 to 18, parallel b value is -0.7 to 0,as well asThe orthogonal b value is -57 to -54AllThose satisfying the above are used. Thus, as described above, it is possible to suppress the luminance from decreasing or the hue change of the emission color from increasing as the distance from the incident side surface increases, based on absorption by the polarizing plate or the like.The transmittance is preferably 45.2 to 50%, and the polarization degree is preferably 96.5 to 99.999%.
[0016]
Polarizing plates exhibiting the above characteristics include, for example, iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. It can be obtained as a polarizing film stretched by adsorbing the dichroic substance.
[0017]
That is, specifically, for example, a polyvinyl alcohol film is immersed in an aqueous solution of iodine or boric acid / potassium iodide, and is dyed and uniaxially stretched 3 to 7 times the original length. A polarizing plate can be produced. In the production thereof, if necessary, the polyvinyl alcohol film can be immersed in water and washed before dyeing. Washing with water is effective in preventing stain unevenness due to swelling of the film, in addition to cleaning the film surface and removing the blocking inhibitor. The stretching treatment can be performed after dyeing, while dyeing, or in a water bath.
[0018]
The thickness of the polarizing film is generally 5 to 80 μm, but is not limited thereto. A polarizing plate may consist only of a polarizing film, and may provide the transparent protective layer in the single side | surface or both surfaces of the polarizing film. The transparent protective layer can be formed using one or two or more kinds of appropriate materials exhibiting transparency depending on the wavelength range of light incident through an illumination device or the like.
[0019]
Incidentally, as a material for the visible light region for forming the transparent protective layer, for example, resins exemplified in the above-mentioned transparent substrate can be mentioned. Among them, those excellent in transparency, mechanical strength, thermal stability, moisture shielding properties and the like are preferably used. From the viewpoint of obtaining a polarization plane light source device with less luminance unevenness and color unevenness, a preferable transparent protective layer does not exhibit birefringence or has low birefringence, and in particular, has an in-plane average phase difference of 30 nm or less. is there.
[0020]
By using a transparent protective layer having a small phase difference, it is advantageous that the polarization state can be maintained well when linearly polarized light is incident. From the standpoint of preventing color unevenness and the like, a preferable average in-plane retardation in the transparent protective layer is 20 nm or less, especially 15 nm or less, particularly 10 nm or less, and the variation of the retardation in each place is as small as possible. Those are more preferred.
[0021]
A transparent protective layer made of a material having a small photoelastic coefficient is preferred from the viewpoint of suppressing the internal stress that is likely to occur in the transparent protective layer by the adhesion treatment and preventing the occurrence 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, particularly 30 nm or less, particularly 20 nm or less from the viewpoint of preventing color unevenness. Formation of the transparent protective layer having a low retardation can be performed by an appropriate method such as a method of removing an internal optical distortion, for example, by a method of annealing an existing film. A preferred forming method is a method of forming a transparent protective layer having a small phase difference by a casting method.
[0022]
The retardation in the transparent protective layer is preferably based on visible light, particularly light having a wavelength of 550 nm. The in-plane average phase difference is expressed by nx as the average refractive index in the in-plane maximum refractive index direction, ny as the average refractive index in the direction perpendicular to the nx direction in the plane, nz as the average refractive index in the thickness direction, When the average thickness is d, it is defined by (nx−ny) × d, and the average phase difference in the thickness direction is defined by {(nx + ny) / 2−nz} × d.
[0023]
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 may be formed as an optical path control layer. Further, the transparent protective layer may be one that has been subjected to a hard coat treatment, antireflection treatment, sticking prevention treatment, diffusion or antiglare treatment, and the like.
[0024]
The hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, hardness and slipperiness by a suitable curable resin such as acrylic, urethane, and silicone are used. It can be formed by a method of adding a cured film excellent in the above to the surface of the transparent protective layer. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be formed as an antireflection film according to the prior art composed of an interference film or the like.
[0025]
On the other hand, the anti-sticking treatment is performed for the purpose of preventing adhesion to the adjacent layer, and the diffusion or anti-glare treatment prevents the reflection of the light transmitted through the polarizing plate due to reflection of external light on the surface of the polarizing plate. For example, it is formed by applying a fine uneven structure to the surface of the transparent protective layer by an appropriate method such as a roughening method using a sandblasting method or an embossing method, or a blending method of transparent fine particles. can do.
[0026]
Examples of the transparent fine particles include inorganic fine particles having an average particle size of 0.5 to 50 μm, such as silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like. One type or two or more types of organic fine particles composed of a crosslinked or uncrosslinked polymer or the like are used. The amount of transparent fine particles used is generally 2 to 50 parts by weight, especially 5 to 25 parts by weight per 100 parts by weight of the transparent resin.
[0027]
The antiglare layer containing transparent fine particles can be provided as the transparent protective layer itself or as a coating layer on the surface of the transparent protective layer. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle. The antireflection layer, the antisticking layer, the diffusion layer, the antiglare layer, and the like described above can be provided as an optical layer composed of a sheet provided with these layers as a separate body from the transparent protective layer.
[0028]
The thickness of the transparent protective layer is preferably 5 to 500 μm, more preferably 10 to 300 μm, and particularly preferably 20 to 100 μm, including the case of a laminated body from the viewpoint of reduction in thickness and weight. Transparent protective layers made of film include polyvinyl alcohol adhesives, gelatin adhesives, formaldehyde, glutaraldehyde and melamine, which may contain water-soluble crosslinking agents such as boric acid and borax, glutaraldehyde and melamine, and oxalic acid. It is possible to adhere to the polarizing film using an adhesive composed of at least a water-soluble crosslinking agent such as oxalic acid, or an appropriate transparent adhesive such as an adhesive layer.
[0029]
The above-mentioned adhesive layer is formed as a coating / drying film of an aqueous solution. When preparing the aqueous solution, other additives and a catalyst such as an acid can be blended as necessary. In particular, when the transparent protective layer has an optical path control layer, an adhesion treatment with an appropriate transparent adhesive such as acrylic or rubber is preferable.
[0030]
The optical path control layer provided on the upper side (surface side) of the polarizing plate can be provided, for example, as a transparent protective layer in the polarizing plate described above, or a light emitting means is formed on the transparent film, and the transparent film is interposed through the adhesive layer. It can also be provided by adhering to a polarizing plate or the like. When the optical path control layer is provided as a transparent protective layer, the optical path control layer can be formed as a transparent protective layer made of only a single layer of the optical path control layer 1A, and thus the transparent film can be omitted.
[0031]
In the optical path control layer 1A, as exemplified by the broken line arrow α in FIG. 2, the light emitting means A is formed on the surface side of the transparent substrate 1C having the illumination device 51 on the side surface in the direction along the substrate plane. The incident light from the side direction through the illuminating device or its transmitted light is reflected through the optical path conversion inclined surface a to change the optical path to the back side of the transparent substrate, and thus to the viewing direction of the liquid crystal display panel. Then, the light is emitted from the transparent substrate 1C as light exhibiting polarization characteristics through the polarizing plate 1B, and the emitted light can be used as illumination light (display light) for a liquid crystal display panel or the like.
[0032]
The light emitting means A that is more preferable than the transparent substrate for emitting light with good directivity in the front (vertical) direction is an optical path having an inclination angle θ1 of 35 to 48 degrees with respect to the plane formed by the transparent substrate 1C as illustrated in FIG. A conversion slope a is provided. When the inclination angle of the optical path conversion slope is less than 35 degrees, when a reflective layer is disposed on the back side of the liquid crystal cell in the front light system and the optical path conversion light is reflected, the liquid crystal display of the display light based on the reflected light The angle emitted from the panel exceeds 30 degrees, which may be disadvantageous for visual recognition.
[0033]
Also, typically, the liquid crystal display panel is formed so that the display by visual recognition in the front direction is the best, and the display characteristic decreases as the visual angle deviates from the vertical and becomes a perspective, so the emission angle is 30 degrees. If it exceeds, it becomes difficult to obtain good display quality. On the other hand, when the inclination angle of the optical path conversion slope exceeds 48 degrees, light leakage is likely to occur from the slope without being totally reflected by the optical path conversion slope, and the light use efficiency is reduced.
[0034]
Therefore, in the above case, instead of the reflection method by the light path changing slope, when the scattering reflection method by the light emitting means having a roughened surface is used, it is difficult to reflect in the vertical direction, and is largely inclined from the front direction of the liquid crystal display panel. The liquid crystal display is dark and the contrast is poor.
[0035]
The light is efficiently totally reflected through the optical path conversion slope and emitted from the transparent substrate in the normal direction of the plane formed by the directivity to efficiently illuminate the liquid crystal cell, etc., thereby achieving a bright and easy-to-view liquid crystal display, etc. In view of this, the preferred inclination angle θ1 of the optical path conversion slope is 38 to 45 degrees, especially 40 to 44 degrees.
[0036]
The light emitting means may be formed by a concave or convex part having a form such as a triangle to a pentagon based on an appropriate form having one or more optical path conversion slopes, for example, a cross section with respect to the optical path conversion slope. it can. Incidentally, in the example of FIG. 1, the light emitting means having a triangular cross section having the optical path conversion inclined surface a and the elevation surface b having the large inclination angle θ <b> 2 is shown, but the light of the isosceles cross section having the two optical path converting inclined surfaces a is shown. It may be an emission means. Note that the polygon of the cross section is not a strict meaning, and deformation such as a change in the angle of the surface or a rounding of the angle formed by the intersection of the surfaces is allowed.
[0037]
As described above, the light emitting means can be formed as a convex portion, but it is preferable that the light emitting means is formed as a concave portion as shown in the figure from the viewpoints of light utilization efficiency and difficulty in scratching. In particular, a light emitting means composed of a concave portion having a triangular cross section is preferable from the viewpoints of reduction in visibility due to size reduction and manufacturing efficiency. The concave portion means that the light emitting means is recessed (groove) in the optical path control layer, and the convex portion means that the light emitting means protrudes outside the optical path control layer (mountain).
[0038]
Further, a plurality of light emitting means are formed for the purpose of reducing the size and, in turn, reducing the thickness of the optical path control layer. In that case, it is possible to form the light emitting means continuous from one side to the other side arranged in a stripe shape, or a plurality of light emitting means distributed in a discontinuous state. Further, the light emitting means may be distributed in parallel or irregularly based on the optical path changing slope in the above-mentioned continuous or discontinuous state, with respect to the virtual center. You may be in the distribution state arrange | positioned at pit form (concentric form).
[0039]
The arrangement state of the plurality of light emitting means can be appropriately determined according to the form and the like. As described above, the optical path conversion slope a is provided with such an optical path conversion slope because incident light from the side surface direction by the illumination device is reflected in the back surface direction of the transparent substrate in the illumination mode to change the optical path. The light emitting means is distributed so that the total light transmittance is 75 to 92% and the haze is 4 to 20%. This is preferable from the viewpoint of obtaining a polarization plane light source device that efficiently illuminates and achieving a bright and excellent liquid crystal display.
[0040]
Such characteristics of total light transmittance and haze can be achieved by controlling the size, distribution density, etc. of the light emitting means. For example, the occupied area based on the projected area of the light emitting means on the light emitting means forming surface is reduced to 1 / It can be achieved by setting the ratio to 100 to 1/8, especially 1/50 to 1/10, particularly 1/30 to 1/15.
[0041]
More specifically, when the size of the light path conversion slope is large, the presence of the slope is easily recognized by the observer, the display quality is liable to be lowered, and the uniformity of illumination with respect to the liquid crystal cell is also liable to be lowered. If the continuous light emitting means are distributed in parallel, the pitch is set to 2 mm or less, especially 20 μm to 1 mm, especially 50 to 500 μm, and the projection width of the optical path conversion inclined surface with respect to the plane formed by the transparent substrate is set. It is preferably 40 μm or less, especially 3 to 20 μm, particularly 5 to 15 μm.
[0042]
The distribution of the continuous light emitting means may be parallel to one side of the transparent substrate, or may be arranged in an intersecting state within 30 degrees. The latter is effective in preventing moire due to interference with pixels such as a liquid crystal cell. Further, moire can be prevented by adjusting the arrangement pitch. Accordingly, the pitch may change or may be constant.
[0043]
On the other hand, when discontinuous light emitting means are distributed in parallel or irregularly, or when distributed in a pit shape with respect to the virtual center, in addition to achieving the above-described characteristics, the reflection efficiency due to the optical path conversion slope is also high. Considering this, it is preferable to set the length of the light path changing slope to 5 times or more, especially 8 or more, particularly 10 or more of the depth of the light emitting means.
[0044]
Further, the length of the optical path changing slope is 500 μm or less, especially 200 μm or less, particularly 10 to 150 μm, and the depth and width of the light emitting means is 2 to 100 μm, especially 5 to 80 μm, especially 10 to 50 μm. The length is the length in the long side direction of the optical path conversion slope, and the depth is based on the light emitting means forming surface. The width is based on the length in the direction orthogonal to the long side direction and the depth direction of the optical path conversion slope.
[0045]
Note that the surface that forms the light emitting means and does not satisfy the optical path conversion inclined surface a having a predetermined inclination angle, for example, the vertical surface b that faces the optical path conversion inclined surface a in FIG. 1, receives incident light from the cell side surface direction. It does not contribute to the emission from the transparent substrate, and it is preferable that the display quality, light transmission or light emission is not affected as much as possible.
[0046]
Incidentally, when the inclination angle θ2 of the elevation surface with respect to the plane formed by the transparent substrate is small, the projection area of the elevation surface with respect to the plane increases, and the front light system in which the polarization plane light source device 1 is arranged on the viewing side as illustrated in FIG. In the external light mode, the surface reflected light from the elevation surface returns to the observation direction, and the display quality is liable to be hindered.
[0047]
Therefore, it is advantageous that the inclination angle θ2 such as the vertical surface is larger, thereby reducing the projected area with respect to the plane formed by the transparent substrate and suppressing the decrease in the total light transmittance. In addition, the apex angle due to the optical path changing slope and the vertical surface can be reduced, the surface reflected light can be reduced, and the reflected light can be tilted in the plane direction of the transparent substrate, and the influence on the liquid crystal display can be suppressed. From such a point, a preferable inclination angle θ2 such as an elevation is 50 degrees or more, especially 60 degrees or more, particularly 75 to 90 degrees.
[0048]
The slope forming the light emitting means A may be formed in an appropriate surface form such as a straight surface, a refracting surface, or a curved surface. Further, the cross-sectional shape of the light emitting means may be a shape whose inclination angle or the like is constant over the entire surface of the optical path control layer, or on the transparent substrate to cope with absorption loss and attenuation of transmitted light due to the optical path conversion. For the purpose of achieving uniform light emission, the light emitting means may be enlarged as the distance from the side surface on which light enters is further away.
[0049]
Also, the light emitting means with a constant pitch can be used, or the pitch is gradually narrowed away from the side of the light incident side (arrow) to increase the distribution density of the light emitting means. it can. Furthermore, the light emission on the transparent substrate can be made uniform at a random pitch. The random pitch is more advantageous than prevention of moire due to interference with pixels. Therefore, the light emitting means may be composed of a combination of different shapes in addition to the pitch.
[0050]
As shown in the example of FIG. 1, the light path changing slope in the light emitting means is preferably facing the direction (arrow) of the incident light from the side surface of the transparent substrate 1C from the viewpoint of improving the emission efficiency. Therefore, when using a linear illuminating device, it is preferable that the optical path conversion inclined surface is oriented in a direction with respect to one side of the transparent substrate or in a certain direction. Further, when a point illumination device such as a light emitting diode is used, it is preferable that the light path changing slope faces the direction of the light emission center of the point illumination device.
[0051]
The shape of the intermittent end of the light emitting means is not particularly limited, but is 30 degrees or more, especially 45 degrees or more, particularly 60 degrees or more from the viewpoint of suppressing the influence due to the reduction of the incident light to the portion. It is preferable to use the slope.
[0052]
Further, the surface of the optical path control layer is a flat surface as smooth as possible, except for the light emitting means, in particular, an angle change of ± 5 degrees or less, especially ± 2 degrees or less, A flat surface of 0 degree is preferable. The angle change is preferably within 1 degree per 5 mm length, and more preferably within 0.5 degrees. By adopting such a flat surface, most of the optical path control layer can be a smooth surface having an angle change of 5 degrees or less, and light transmitted through the transparent substrate can be efficiently transmitted as indicated by the broken line arrow β illustrated in FIG. It can be used well and can achieve uniform light emission without disturbing the image.
[0053]
As described above, the pit-like arrangement of the light emitting means A uses a point illumination device as the illumination device arranged on the side surface of the transparent substrate, and the radial incident light from the side surface by the point illumination device or its transmitted light is used. By changing the optical path through the optical path changing slope a, the transparent substrate emits light as uniformly as possible, and the light having excellent directivity in the normal direction with respect to the liquid crystal cell or the like is efficiently transmitted from the transparent substrate using the illumination device light. It aims at emitting.
[0054]
Therefore, it is preferable that the pit-shaped arrangement is performed so that a virtual center is formed on the end surface of the transparent substrate or on the outside thereof so that the arrangement of the point lighting device is facilitated. The virtual center can form one place or two places or more with respect to the same or different end faces in the transparent substrate.
[0055]
The optical path control layer can be formed by an appropriate method. As an example, a transparent film made of a thermoplastic resin is pressed against a mold capable of forming a predetermined light emitting means under heating to transfer the shape, a heat-melted thermoplastic resin, or heat or a solvent is used. A resin that has been fluidized through a mold that can form a predetermined light emitting means, a liquid resin, a monomer, an oligomer, or the like that can be polymerized with heat, ultraviolet rays, or radiation such as an electron beam. Examples thereof include a method of filling or casting into a mold capable of forming a light emitting means and performing a polymerization treatment.
[0056]
The transparent film is coated with a liquid resin, monomer, oligomer, or the like that can be polymerized by radiation such as heat, ultraviolet light, or electron beam, and the coating layer is pressed against a mold that can form a predetermined light emitting means. After that, a method of polymerization treatment, filling the above-mentioned liquid resin into a mold capable of forming a predetermined light emitting means, placing a transparent film in close contact on the filling layer, polymerization treatment by irradiation with ultraviolet rays, radiation, etc. And how to do it. These methods can also be applied to the formation of an optical layer integrally having a light emitting means by using an optical layer such as a polarizing plate in which the optical path control layer is adjacent to the transparent film.
[0057]
Therefore, the above-described method is advantageous for forming a transparent protective layer having an optical path control layer and integrally forming a transparent protective layer having a light emitting means. In particular, the latter method using a transparent film is formed by adding a separate optical path control layer 1A to an optical layer such as a transparent protective layer. In that case, if the refractive index difference between the optical path control layer to be added and the optical layer such as the transparent protective layer is large, the emission efficiency may be greatly reduced due to interface reflection or the like.
[0058]
Therefore, from the viewpoint of suppressing the reduction of the emission efficiency, the difference in refractive index between the optical layer such as the transparent protective layer and the optical path control layer should be made as small as possible, especially within 0.10, especially within 0.05. It is preferable that In that case, it is preferable from the viewpoint of emission efficiency that the refractive index of the optical path control layer to be added is higher than that of the optical layer such as the transparent protective layer. For the formation of the optical path control layer, an appropriate transparent material corresponding to the wavelength range of incident light can be used in accordance with the above-described transparent substrate.
[0059]
In addition, in the method using the said film, the method of isolate | separating the formed optical path control layer and film after the polymerization process using what was processed with the release agent etc. as the film can also be taken. In that case, the film to be used may not be transparent. The thickness of the optical path control layer is generally 300 μm or less, especially 5 to 200 μm, particularly 10 to 100 μm.
[0060]
If necessary, at least the light emitting means forming surface of the optical path control layer can be subjected to the above-described antiglare treatment, antireflection treatment, hard coat treatment, and the like. A transparent substrate subjected to such treatment can be preferably used particularly for a front light system. The antiglare treatment, the antireflection treatment and the hard coat treatment can also be applied to a film adhesion method or the like subjected to one or more treatments.
[0061]
An adhesive layer for adhering an optical path control layer made of a transparent film or the like to an adjacent layer such as a polarizing plate, if necessary, can be provided on one or both of them. The purpose of the bonding process through the bonding layer is to improve the reflection efficiency through the light path changing slope a of the light emitting means A, and hence the front luminance by effective use of incident light from the side surface direction.
[0062]
For the formation of the adhesive layer, for example, an appropriate material such as an adhesive that cures by irradiation or heating with ultraviolet rays or radiation can be used, and there is no particular limitation. An adhesive layer can be preferably used from the viewpoints of handleability such as simple adhesiveness and stress relaxation properties that suppress the generation of internal stress. For the formation of the adhesive layer, for example, an appropriate polymer such as rubber, acrylic, vinyl alkyl ether, silicone, polyester, polyurethane, polyether, polyamide, styrene, or fluorine is used as the base polymer. A pressure sensitive adhesive can be used.
[0063]
Among them, those having excellent transparency, weather resistance, heat resistance and the like are preferably used, such as an acrylic pressure-sensitive adhesive mainly composed of a polymer mainly composed of alkyl ester of acrylic acid or methacrylic acid. In addition, the moisture absorption rate is low in terms of preventing foaming and peeling due to moisture absorption, reducing optical properties due to thermal expansion differences, preventing warping of the transparent substrate, and forming high-quality and durable liquid crystal display devices. An adhesive layer that is low and excellent in heat resistance is preferred.
[0064]
Further, the adhesive layer may be of a light diffusion type by containing one or more transparent fine particles exemplified in the above antiglare treatment. The adhesive layer, particularly the adhesive layer, is, for example, a natural or synthetic resin, especially a tackifier resin, a glass fiber or glass bead, a metal powder or other inorganic powder, a pigment, or a colorant. An appropriate additive that may be added to the adhesive layer such as an antioxidant or an antioxidant may be contained.
[0065]
The attachment of the adhesive layer to the optical path control layer is, for example, about 10 to 40% by weight by dissolving or dispersing the adhesive substance or the composition thereof in a solvent composed of an appropriate solvent alone or a mixture such as toluene and ethyl acetate. A pressure-sensitive adhesive liquid is prepared and applied directly on the optical path control layer by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on the separator according to the above and the optical path is provided. It can be performed by an appropriate method such as a method of transferring onto the control layer.
[0066]
The illumination mechanism as the polarization plane light source device 1 can be formed by arranging one or two or more illumination devices 51 on one or more side surfaces of the transparent substrate 1C as in the example of FIG. In the case of the formation, in the case of an optical path control layer having light emitting means arranged in a pit shape, the light emission in the pit shape is achieved from the point of achieving bright surface emission by efficiently using the radial incident light by the point illumination device. It is preferable to arrange the point-like illumination device on the side surface of the transparent substrate on the vertical line including the virtual center of the means.
[0067]
In such an arrangement of the point illumination device corresponding to the virtual center, a polarization plane light source as shown in the example of FIG. 2 according to whether the virtual center of the light emitting means is at the end face of the optical path control layer or outside thereof. Appropriate countermeasures such as a method of projecting the side on which the point illumination device of the cell substrate 20 made of the transparent substrate 1C in the device 1 is arranged can be taken. The same applies when other illumination devices such as a linear illumination device are arranged.
[0068]
An appropriate lighting device can be used as the lighting device disposed on the side surface of the transparent substrate. For example, in addition to the above-described point illumination device such as a light emitting diode, a linear illumination device such as a (cold, hot) cathode tube, an array body in which the point illumination devices are arranged in a linear or planar shape, or a point illumination device And a linear light guide plate that can convert incident light from a point illumination device into a linear illumination device via the linear light guide plate can be preferably used.
[0069]
Moreover, it is preferable from the point of radiation | emission efficiency to arrange | position an illuminating device on the side surface of the transparent substrate from which the optical path conversion inclined surface of an optical path control layer will face. Including the above-mentioned pit arrangement, the incident light from the side surface through the illuminating device is efficiently polarized by arranging the optical path changing slope so as to face the illuminating device as vertically as possible. It can be converted to emit light with high efficiency.
[0070]
Therefore, in the case of an optical path control layer having a light emitting means having a plurality of optical path conversion slopes, such as one having a transverse plane of an isosceles triangle and having two optical path conversion slopes, It is also possible to arrange a number of illumination devices corresponding to a plurality of optical path conversion slopes, such as both. In the case of the pit arrangement, the point illumination devices can be arranged at one place or two places or more corresponding to the virtual center of the light emitting means in the optical path control layer.
[0071]
As shown in the example of FIG. 2, the lighting device 51 may be a combined body in which appropriate auxiliary means such as a reflector 52 surrounding the illuminating device 51 are arranged to guide the diverging light to the side surface of the transparent substrate as necessary. it can. As the reflector, an appropriate reflection sheet such as a resin sheet, a white sheet, or a metal foil provided with a highly reflective metal thin film can be used. The reflector can also be used as a fixing means that also serves as an enclosure for the lighting device, such as by bonding its end to the end of the transparent substrate.
[0072]
The polarization plane light source device can be in a form in which another optical layer is added as necessary in practical use. The optical layer is not particularly limited. For example, a suitable optical layer that may be used for forming a liquid crystal display device such as a reflective layer, a transflective reflective layer, a retardation layer, or a brightness enhancement film. Alternatively, two or more layers can be added.
[0073]
Incidentally, in the example of FIG. 2, a retardation plate 25 is added between the polarizing plate 1B and the transparent substrate 1C. Further, on the opposite side of the transparent substrate, the alignment film 22 for aligning the liquid crystal and the alignment of the liquid crystal are controlled. A transparent electrode 21 for performing color display, a color filter 23 for realizing color display, and a low refractive index layer 24 for efficiently transmitting side incident light or transmitted light to the opposite end side as indicated by a broken line arrow γ. Yes.
[0074]
When the reflection layer described above is disposed outside the optical path control layer and used as a backlight of a liquid crystal display device or the like, it is prevented from leaking light from the optical path control layer or incident from the viewing side of the liquid crystal display device or the like. This is added when external light is reflected and external light / illumination type liquid crystal display devices that can be seen even in the external light mode are formed. The reflection layer can be formed by a reflection sheet according to the prior art, a method in which a foil made of a reflective metal such as aluminum or an adhesion film is attached to the light emitting means forming surface of the optical path control layer.
[0075]
The reflection layer may be a diffuse reflection type having a fine uneven structure on the surface. The reflective layer made of an adhesion film can be formed by, for example, a deposition method such as a vacuum deposition method, an ion plating method, a sputtering method, or a method of attaching a metal film by an appropriate method such as a plating method.
[0076]
On the other hand, the transflective reflective layer is a reflective layer such as a half mirror that reflects and transmits light. The reflective layer is formed into a thin film by making the reflective layer thin, or a light transmitting aperture is formed in the reflective layer. It can be formed by a method in which a large number are distributed and distributed. The semi-transmissive reflective layer is used as a backlight of a liquid crystal display device or the like by placing it between a polarizing plate and an optical compensation layer, and can be seen even in the above-described external light mode. It is added when forming a dual-use liquid crystal display device or the like. The polarization plane light source device can also be used as a cell substrate on the back side.
[0077]
In addition, the retardation layer can change linearly polarized light into elliptically polarized light or circularly polarized light, change elliptically polarized light or circularly polarized light into linearly polarized light, change the polarization direction (vibration direction) of linearly polarized light, or view angle compensation. Used in When changing linearly polarized light to circularly polarized light or when changing circularly polarized light to linearly polarized light, a ¼ wavelength plate is generally used, and when changing the polarization direction of linearly polarized light, a ½ wavelength plate is generally used.
[0078]
On the other hand, an elliptically polarizing plate formed by laminating a retardation layer and a polarizing plate compensates (prevents) coloration (blue or yellow, etc.) caused by birefringence of the liquid crystal layer in a Spirster isometric (STN) type liquid crystal display device. Thus, it is effectively used for achieving monochrome display without coloring. In particular, the one using a phase difference layer in which the refractive index in the three-dimensional direction is controlled is preferable because it can also compensate for coloring that occurs when the liquid crystal display screen is obliquely viewed. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a color display type reflective liquid crystal display device, and can also be used for the purpose of preventing reflection.
[0079]
The retardation layer for viewing angle compensation is intended to widen the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is perspective. One or more layers of the retardation layer are disposed at an appropriate position such as between the optical path control layer and the polarizing plate, or / and between the polarizing plate and the transparent substrate, depending on the purpose of use. The polarization plane light source device to which the retardation layer is added can be used for both the front light and the backlight, and can also be used as a cell substrate on the viewing side or the back side.
[0080]
As the retardation layer, for example, a birefringent film formed by stretching a film made of an appropriate polymer such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefins, polyarylate or polyamide, Examples thereof include a liquid crystal polymer alignment film and a liquid crystal polymer alignment layer supported by a film. The retardation layer may have an appropriate retardation according to the purpose of use, and may be one in which two or more kinds of retardation layers are laminated to control optical characteristics such as retardation.
[0081]
The said extending | stretching process can take appropriate systems, such as a uniaxial and a biaxial. Biaxially stretched films such as biaxially stretched films, birefringent films in which the uniaxially stretched film is further stretched in the thickness direction to control the refractive index in the thickness direction, and tilted orientation films are used for the retardation layer for viewing angle compensation. A film or the like is usually preferably used.
[0082]
Examples of the tilted alignment film include a heat shrinkable film adhered to a polymer film, and the polymer film is stretched or / and contracted under the action of the shrinkage caused by heating, or a liquid crystal polymer is obliquely aligned. And so on. A liquid crystal polymer alignment layer, especially an optically anisotropic layer composed of a discotic liquid crystal polymer gradient alignment layer, supported by a triacetyl cellulose film rather than achieving a wide viewing angle with good visibility. Can be preferably used.
[0083]
The brightness enhancement film exhibits the property of selectively reflecting linearly polarized light with a predetermined polarization axis or circularly polarized light in a predetermined direction and transmitting other light when natural light is incident. In between, it arrange | positions with a quarter wavelength plate as needed. By using the polarization plane light source device to which the brightness enhancement film is added as a backlight, the use efficiency of light through the illumination device can be improved and the brightness can be improved. In that case, a form in which the light reflected by the brightness enhancement film is inverted and the reflection layer for re-entering the brightness enhancement film is disposed outside the optical path control layer is more preferable from the viewpoint of brightness enhancement.
[0084]
Note that the brightness improvement by the addition of the brightness enhancement film described above is based on the reduction of absorption loss due to the supply of polarized light that is not easily absorbed by the polarizing plate. When a reflective layer is further added, the light reflected by the brightness enhancement film is reflected. The amount of light that can be used for liquid crystal displays, etc., based on increasing the amount of transmitted light by transmitting the brightness enhancement film partially or entirely as light in a predetermined polarization state by reversing and re-entering To increase the front luminance and the like.
[0085]
As a brightness enhancement film, for example, a dielectric multilayer thin film or a multilayer laminate of thin film films having different refractive index anisotropy exhibits characteristics of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light. Cholesteric liquid crystal layer, especially the alignment film of cholesteric liquid crystal polymer, or the one in which the alignment liquid crystal layer is supported on the film substrate, reflects either the left-handed or the right-handed circularly polarized light, and the other light An appropriate material such as a material exhibiting a transmitting characteristic can be used.
[0086]
Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, a brightness enhancement film of a type that transmits circularly polarized light, such as a cholesteric liquid crystal layer, can be directly incident on a polarizing plate. However, from the viewpoint of suppressing absorption loss, the circularly polarized light is converted into linearly polarized light through a retardation layer. It is preferable that the light is incident on the polarizing plate. By using a quarter wave plate as the retardation layer, circularly polarized light can be converted into linearly polarized light.
[0087]
In the above, the retardation layer that functions as a quarter-wave plate in a wide wavelength range such as the visible light region is different from the retardation layer that functions as a quarter-wave plate for monochromatic light with a wavelength of 550 nm, for example. It can be obtained by a method of superimposing a phase difference layer exhibiting phase difference characteristics, for example, a phase difference layer functioning as a half-wave plate. Therefore, the retardation layer disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.
[0088]
A cholesteric liquid crystal layer that reflects circularly polarized light in a wide wavelength range such as a visible light region can be formed by combining two or more layers in a combination of those having different wavelength characteristics to reflect. Based on this, it is possible to obtain transmitted circularly polarized light in a wide wavelength range.
[0089]
The polarization plane light source device according to the present invention has a vertical direction (normal direction) that is advantageous for visual recognition of incident light from the side surface direction by the illuminating device or its transmitted light through the light emitting means (optical path changing slope). ) To change the optical path and emit the polarized light through the polarizing plate with high light utilization efficiency. In addition, it can exhibit good transparency with respect to external light.
[0090]
From the viewpoint of uniformity of front luminance and / or reduction of hue change, a preferred polarization plane light source device emits light from the back side of the transparent substrate when light is incident from the side surface of the transparent substrate through the illumination device. The difference between the maximum value and the minimum value of the attenuation factor of polarized light having a polarization attenuation factor of 50% or less, particularly 10 to 45%, or / and polarization of wavelengths 440 nm, 550 nm, and 610 nm is 10% or less, especially 8%. The following is particularly 1 to 7%.
[0091]
The attenuation factor is expressed by the formula: {(front luminance at a position of 5 mm from the incident side surface) − (based on the polarized light emitted from the back surface of the transparent substrate having a length of 40 mm from the incident side surface to the opposite side surface. Front luminance at a position 5 mm from the opposite side surface}} / (Front luminance at a position 5 mm from the incident side surface) × 100 (hereinafter the same).
[0092]
Therefore, the polarization plane light source device according to the present invention is used for, for example, a sidelight type light guide plate, or a front light or a backlight that also serves as a cell substrate on the viewing side or the back side, and is a thin and light reflective type and transmission type that are bright and easy to see. These can form various devices such as a liquid crystal display device for both external light and illumination, or a transflective liquid crystal display device for both external light and illumination.
[0093]
An example of the liquid crystal display device described above is shown in FIG. The figure is an example of a liquid crystal display device of both external light and illumination type by a front light type that also serves as a cell substrate on the reflection side and the viewing side. 20 and 30 are cell substrates in the liquid crystal cell, 40 is a liquid crystal layer, and 31 is a reflective layer. As shown in the figure, the liquid crystal display device can be formed as having the polarization plane light source device 1 on one or both of the viewing side and the back side of the liquid crystal display panel.
[0094]
In addition, as shown in the figure, when the liquid crystal display device is formed, the polarization plane light source device 1 is generally arranged so that the surface having the light emitting means A is on the outside. In this case, the polarization plane light source device may form the liquid crystal display device in a state in which it is completed in advance, or the polarization plane light source device is assembled in the process while forming the liquid crystal display device in an appropriate order. Also good.
[0095]
Furthermore, the lighting device enables visual recognition in an illumination mode by lighting, and in the case of an external light / illumination type liquid crystal display device, it is necessary to be lit when visualizing in an external light mode by external light. Since it is not, it can be switched on / off. As the switching method, any method can be adopted, and any of the conventional methods can be adopted. Note that the illumination device may be of a different color light emission type capable of switching the emission color, or may be capable of emitting different color light through different types of illumination devices.
[0096]
In general, a liquid crystal display device is formed by appropriately assembling a liquid crystal cell that functions as a liquid crystal shutter, a driving device associated therewith, a front light or a backlight, and optional components such as a reflective layer and a retardation plate. The In the present invention, there is no particular limitation except that the illumination mechanism is formed using the above-described polarization plane light source device, and it can be formed according to a conventional front light type or backlight type.
[0097]
Accordingly, the liquid crystal cell to be used is not particularly limited. As shown in the figure, the liquid crystal 40 is sealed between the cell substrates 20 and 30 through the sealing material 41, and display light is obtained through light control by the liquid crystal or the like. An appropriate reflection type, transmission type, or transflective type can be used.
[0098]
Incidentally, specific examples of liquid crystal cells include twisted and non-twisted types such as TN liquid crystal cells, STN liquid crystal cells, IPS liquid crystal cells, HAN liquid crystal cells, OCB liquid crystal cells, VA liquid crystal cells, and π liquid crystal cells. Liquid crystal cells such as a system, a guest host system and a ferroelectric liquid crystal, or a light diffusion type liquid crystal cell such as an internal diffusion type. Also, the liquid crystal driving method may be an appropriate one such as an active matrix method or a passive matrix method.
[0099]
In the reflective liquid crystal display device, a liquid crystal cell having a liquid crystal layer that modulates light via an electric field, such as a TN type or STN type liquid crystal cell, is preferably used. Further, in that case, the polarization plane light source device is generally arranged as a cell substrate 20 or a side light type light guide plate on the viewing side of the liquid crystal display panel as shown in the figure, thereby forming a front light type liquid crystal display device. It is. The liquid crystal is usually driven through electrodes 21 and 31 provided inside the cell substrate as in the example of FIG.
[0100]
In the reflective liquid crystal display device, the arrangement of the reflective layer is essential. The arrangement position can be provided inside the liquid crystal cell as illustrated in FIG. 2, or can be provided outside the liquid crystal cell. Therefore, in the example of FIG. 2, the electrode 31 also serves as a reflective layer. The reflection type liquid crystal display device according to the present invention can generally be used as an external light / illumination type.
[0101]
For the reflective layer, for example, a coating layer containing a high-reflectance metal powder such as aluminum, silver, gold, copper, or chromium in a binder resin, an attachment layer of a metal thin film by a vapor deposition method, the coating layer, It can be formed as an appropriate reflective layer according to the prior art, such as a reflective sheet, a metal foil, a transparent conductive film, or a dielectric multilayer film, in which the attachment layer is supported by a base material. This is the same as the above reflective layer.
[0102]
On the other hand, a transmissive liquid crystal display device is generally a backlight type liquid crystal display device in which a polarization plane light source device is arranged as a cell substrate or a sidelight type light guide plate on the back side of a liquid crystal display panel. It is. In that case, by providing a reflection layer outside the optical path control layer as described above, the light leaking from the optical path conversion slope etc. is reflected and returned to the direction of the liquid crystal cell, so that it can be used for cell illumination, and the front luminance is improved. be able to.
[0103]
In the above case, by making the reflection layer a diffuse reflection surface, the reflected light can be diffused and directed in the front direction, and can be directed in an effective direction by visual recognition. Further, by providing the reflective layer, the liquid crystal display device can be used as a transmissive type and an external light / illumination type liquid crystal display device.
[0104]
On the other hand, a transflective liquid crystal display device can be formed, for example, by using a reflective layer in the reflective type described above as a transflective reflective layer that reflects and transmits light. In this case, the polarization plane light source device can be disposed on the viewing side of the liquid crystal display panel, but generally is preferably disposed on the back side. Moreover, a polarization plane light source device can be arranged on both the viewing side and the back side.
[0105]
The transflective liquid crystal display device according to the present invention can be generally used as an external light / illumination type. Further, in the case where the liquid crystal display panel has a polarization plane light source device on the back side and the back side of the liquid crystal display panel, the front luminance can be further improved by disposing a reflective layer on the outside. . This is because light that has been transmitted through the semi-transmissive reflective layer or reflected to reach the back surface of the liquid crystal display panel can be reflected and inverted by the reflective layer to be incident on the liquid crystal cell again. .
[0106]
In the transmissive type and transflective type described above, the cell substrate and electrode of the reflective type in which the reflective layer is disposed outside the liquid crystal cell are arranged such as a transparent substrate or transparent electrode in order to enable liquid crystal display. It is necessary to form it as a material that can transmit light.
[0107]
On the other hand, as shown in the example of FIG. 2, in the case where the electrode 31 that also serves as a reflective layer is provided inside the liquid crystal cell, the cell substrate 20 and the electrode 21 on the viewing side are transparent substrates, Although it is necessary to form it as a transparent electrode or the like capable of transmitting light, the cell substrate 30 on the back side does not need to be transparent like the reflective layer 31 and may be formed of an opaque body. .
[0108]
The thickness of the cell substrate on which the liquid crystal cell is formed is not particularly limited, and can be appropriately determined according to the sealing strength of the liquid crystal, the size of the lighting device to be arranged, and the like. In general, the thickness is 10 μm to 5 mm, especially 50 μm to 2 mm, particularly 100 μm to 1 mm, in view of the balance between light transmission efficiency and thin and light weight. In addition, the thickness of the cell substrate may be different between the side where the lighting device is disposed and the side where the lighting device is not disposed, or may be the same thickness.
[0109]
In forming the liquid crystal cell, as necessary, alignment films 22 and 32 such as a rubbing film, a color filter 23, a low refractive index layer 24, a retardation plate 25, and the like can be provided as in the example of FIG. 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. As described above, such an optical layer can also be provided as an additional layer for the polarization plane light source device.
[0110]
The low-refractive index layer 24 efficiently reflects the incident light from the side direction through the illumination device to the rear in the direction away from the illumination device, and the light is also transmitted to the rear optical path conversion slope. The object is to efficiently enter and to improve the uniformity of brightness over the entire cell 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 material or an organic material such as a fluorine compound or a silicone-based polymer.
[0111]
The arrangement position of the low refractive index layer is opposite to the inner side of the cell substrate 20 on which the illumination device 51 is arranged as in the example of FIG. 2, that is, the side of the transparent substrate with the optical path control layer, from the viewpoint of improving the brightness of the cell display. This aspect is preferred. In addition, 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, is higher than that of the cell substrate (transparent substrate), which improves the brightness of the cell display. More preferred. Therefore, when the lighting device is disposed on the side surfaces of both the viewing side and the back side cell substrate, it is preferable to provide a low refractive index layer on both of the cell substrates.
[0112]
When forming a liquid crystal display device, a liquid crystal display panel to which one or two or more appropriate optical layers such as a light diffusion layer, a prism sheet, and a lens sheet are added in addition to the above-described anti-glare layer, if necessary. You can also. Such an optical layer to be added can be incorporated into a polarization plane light source device via an adhesive layer or the like as required, and applied to a liquid crystal cell as an integral body.
[0113]
The purpose of the light diffusing layer is to expand the display range by diffusing display light, to equalize the front brightness by leveling light emission, and to increase the amount of light incident on the optical path control layer by diffusing the transmitted light in the transparent substrate. . The light diffusing layer can be provided by an appropriate method using a coating layer having a fine surface relief structure according to the antiglare layer or a diffusion sheet. The light diffusion layer can also be disposed as a layer that also serves as an adhesive layer by blending transparent particles in the adhesive layer. Accordingly, the liquid crystal display device can be thinned. One layer or two or more layers of the light diffusion layer can be disposed at an appropriate position such as between the polarizing plate on the viewing side and the transparent substrate.
[0114]
In the reflective liquid crystal display device illustrated in FIG. 2 described above, visual recognition using both external light and illumination is emitted from the polarization plane light source device 1 as shown by the broken line arrow α in the illumination mode when the illumination device 51 is turned on. The reflected light is reflected by the reflective layer 31 via the liquid crystal cell, then reaches the polarization plane light source device via the liquid crystal cell in the reverse direction, and is transmitted from the portion other than the light emitting means A in the optical path control layer. Is visible.
[0115]
On the other hand, in the external light mode by turning off the illumination device, the light incident from the portion other than the light emitting means A in the optical path control layer 1A of the polarization plane light source device 1 is reversed in the liquid crystal cell according to the above through the reflective layer 31. The display light transmitted through the portion other than the light emitting means is visually recognized through the polarization plane light source device.
[0116]
On the other hand, in the transmissive liquid crystal display device, visual recognition using both external light and illumination is performed in the illumination mode in which the illumination device is turned on, in which the light emitted from the polarization plane light source device arranged on the back side enters the liquid crystal cell, The display light transmitted through the transparent substrate is visually recognized. In the external light mode by turning off the illumination device, external light incident from the viewing surface passes through the liquid crystal cell and reaches the polarizing surface light source device on the back side, and enters from a portion other than the light emitting means of the optical path control layer. The display light that is inverted through the reflective layer provided on the back surface and transmitted through the liquid crystal cell in the reverse direction is visually recognized.
[0117]
Further, in the transflective liquid crystal display device, the visual recognition by both external light and illumination is based on the transmitted light and / or reflected light through the transflective reflection layer, and the above-described transmissive or / and reflective liquid crystal display device. In accordance with the above, visual recognition of the display light in the illumination mode or the external light mode is achieved.
[0118]
In the present invention, each component forming the above-described polarization plane light source device or liquid crystal display device may be laminated or integrated in whole or in part, or may be arranged in an easily separated state. Good. It is preferable to be in a fixed state from the viewpoint of preventing a decrease in contrast due to suppression of interface reflection, and it is preferable that at least the optical path control layer, the polarizing plate, the transparent substrate, and the like are in a fixed contact state. 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 or the like to form an adhesive layer exhibiting a diffusion function.
[0119]
In addition, the above-mentioned formed parts, particularly those on the viewing side, can be treated with ultraviolet absorbers such as salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, etc. Can also be given.
[0120]
The polarizing surface light source device can be provided with a transparent adhesive layer for adhering to other members such as a liquid crystal cell, if necessary. The adhesive layer can conform to the above. The thickness of the adhesive layer can be appropriately determined according to the purpose of use and the adhesive force, and is generally 1 to 500 μm, especially 5 to 200 μm, especially 10 to 100 μm. In addition, it is preferable to temporarily cover the adhesive layer exposed on the surface, in particular, the adhesive layer, with a release sheet temporarily attached for the purpose of preventing foreign matters from being mixed until it is put to practical use.
[0121]
As the release sheet, for example, an appropriate thin leaf body such as a plastic film or rubber sheet, paper or cloth, nonwoven fabric or net, foam sheet or metal foil, or a laminate thereof, silicone-based or long-chain alkyl-based, fluorine An appropriate one according to the prior art, such as a system or one coated with an appropriate release agent such as molybdenum sulfide, can be used.
[0122]
【Example】
Example 1
An ultraviolet curable acrylic resin is dropped onto a mold that has been processed into a predetermined shape with a dropper, and then a saponified triacetyl cellulose film having a thickness of 80 μm is allowed to stand, and the rubber roller is brought into intimate contact with an excess amount. After extruding the resin and bubbles, the resin was irradiated with ultraviolet rays with a metal halide lamp, cured, peeled off from the mold, and cut into a predetermined size to obtain a transparent protective layer with an optical path control layer.
[0123]
The transparent protective layer has a length of about 100 μm, a width of about 10 μm, and a plurality of triangular light emitting means (FIG. 1) distributed irregularly in parallel to one side. The inclination angle is 43 degrees and the elevation inclination angle is 78 degrees. The optical path conversion slope faces the parallel side. Moreover, the area of the flat surface which consists of parts other than the light-projection means in the surface in which the light-projection means was formed is 12 times or more of the sum of an optical path conversion slope and an elevation surface. Furthermore, the total light transmittance and haze of the transparent protective layer were 89% and 7%, respectively.
[0124]
Next, the side having no light emitting means of the transparent protective layer and the polyvinyl alcohol polarizing film are pressure-bonded with a pressure-bonding roller through a previously formed acrylic adhesive layer having a refractive index of 1.53, and the polarizing plate. The side was pressure-bonded to a glass substrate with a pressure roller through a similar acrylic adhesive layer, and was heated and defoamed in an autoclave to be adhered.
[0125]
Next, a cold cathode tube is disposed on the side of the glass substrate facing the optical path changing slope, and is surrounded by a silver-deposited polyester film, and the film ends are adhered to the upper and lower surfaces of the glass substrate with a double-sided adhesive tape. The tube was held and fixed to obtain a polarization plane light source device.
[0126]
The polarizing film used above has a transmittance of 45.37%, a degree of polarization of 96.81%, a parallel a value of −0.380, an orthogonal a value of 17.715, a parallel b value of −0.617, and an orthogonal b value of −56. .163, the x value in the Yxy color system (hereinafter the same) in the region 25 mm from the light source is 0.2970, and the y value is 0.3235. The glass substrate has a thickness of 1.3 mm, a length of 40 mm, and a width of 30 mm.
[0127]
Example 2
As a polarizing film, transmittance 45.43%, polarization degree 96.85%, parallel a value -0.318, orthogonal a value 16.742, parallel b value -0.008, orthogonal b value -54.493, x A polarization plane light source device was obtained in the same manner as in Example 1 except that a value of 0.2934 and a y value of 0.3174 were used.
[0128]
Comparative Example 1
As a polarizing film, transmittance 44.37%, polarization degree 99.21%, parallel a value -2.364, orthogonal a value 3.382, parallel b value 3.573, orthogonal b value -18.994, x value Was obtained in the same manner as in Example 1, except that a material having a y value of 0.4034 was used.
[0129]
Comparative Example 2
As a polarizing film, transmittance 44.90%, polarization degree 98.13%, parallel a value -1.323, orthogonal a value 15.6997, parallel b value 1.193, orthogonal b value -47.791, x value Was obtained in the same manner as in Example 1, except that a sample having a y value of 0.3541 was used.
[0130]
Comparative Example 3
As a polarizing film, transmittance 44.08%, polarization degree 99.90%, parallel a value -1.290, orthogonal a value 0.612, parallel b value 2.783, orthogonal b value -4.706, x value Was obtained in the same manner as in Example 1 except that the one with 0.3480 and the y value of 0.3926 was used.
[0131]
Evaluation test
The cold-cathode tubes of the polarization plane light source devices obtained in the examples and comparative examples were turned on, and the luminance of the emitted light at each position 5 mm from the incident side surface and the opposite side surface and the spectral spectrum were measured by a luminance meter (manufactured by Minolta Co., Ltd. Measured by a radiance meter CS-1000), and the difference between the maximum value and the minimum value (attenuation rate difference) of the attenuation factor of the front luminance in the entire visible light range and the attenuation factors of light having wavelengths of 440 nm, 550 nm and 610 nm was examined. . Further, the hue change was visually observed, and the case where the change was small and good was evaluated as ◯, and the case where the change was large was evaluated as x.
[0132]
The results are shown in the following table.

[0133]
From the table, it can be seen that in the example, the attenuation rate of the front luminance and the change in hue are small compared to the comparative example. By using a polarizing plate exhibiting a predetermined degree of polarization and transmittance, it is possible to increase the uniformity of luminance by reducing the decrease in front luminance that occurs as the distance from the light source increases. It can be seen that by using a polarizing plate showing a value and b value, it is possible to suppress the phenomenon that the hue changes as the distance from the light source increases, and to reduce color unevenness.
[Brief description of the drawings]
FIG. 1 is an explanatory side view of an embodiment.
FIG. 2 is an explanatory side view of a liquid crystal display device.
[Explanation of symbols]
1: Polarized light source device
1A: Optical path control layer
A: Light emitting means
a: Optical path conversion slope
1B: Polarizing plate
1C: Transparent substrate
20, 30: Cell substrate
40: Liquid crystal layer
51: Lighting device

Claims (4)

On the surface of a transparent substrate having an illumination device on the side surface, it has the optical path control layer through at least a polarizing plate, the polarizing plate transmittance of 45% or more, the degree of polarization of 96% or more, a flat row a value -0 .4 to -0.3, orthogonal a value of 16 to 18, parallel b value of -0.7 to 0, and orthogonal b value of -57 to -54 are satisfied, and the optical path control layer is formed from the side surface of the transparent substrate. A polarization plane light source device comprising a plurality of light emitting means including an optical path changing slope that reflects the incident light in the direction of the back surface of the transparent substrate. 2. The illumination device according to claim 1, wherein the inclination angle of the optical path conversion inclined surface is 35 to 48 degrees with respect to the plane formed by the transparent substrate, and the length from the incident side surface to the side surface facing the incident surface is 40 mm. The formula of the polarized light emitted from the back surface of the transparent substrate when light is incident through the surface: {(Front luminance at a position 5 mm from the incident side surface) − (Front luminance at a position 5 mm from the opposite side surface)} / (Polarization surface light source device having an attenuation factor of 50% or less based on (front luminance at a position 5 mm from the incident side surface) × 100. In Claim 1 or 2, when light is incident through the illumination device from the side surface of the transparent substrate having a length of 40 mm from the incident side surface to the opposite side surface, the expression of the polarized light emitted from the back surface of the transparent substrate : {(Front luminance at a position 5 mm from the incident side surface) − (Front luminance at a position 5 mm from the opposite side surface)} / (Front luminance at a position 5 mm from the incident side surface) × 100 A polarizing surface light source device in which the difference between the maximum value and the minimum value of the attenuation rate in polarized light of 440 nm, 550 nm, and 610 nm is 10% or less. The liquid crystal display device characterized by having a polarization plane light source apparatus according to one or both of the visual side or back side of the liquid crystal display panel to one of claims 1 to 3.

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