JP2011175299A - Optical path-changeable polarizer and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop an optical member capable of forming a liquid crystal display device in which an optical path of the light entering from the side face of a liquid crystal display panel is changed efficiently to the visible direction, and illumination light is hardly colored and which is made thin and lightweight and has a clear and eye-friendly display. <P>SOLUTION: The liquid crystal display device has: the polarizer (1), which is obtained by arranging a plurality of light emission means (A), each of which has an optical path-changeable slope (a) having 35-48° inclined angle with respect to the plane of a polarizer (1C), on the surface of the polarizer (1C) exhibiting ≥0.80 (the maximum value)/(the minimum value) ratio of light transmittance per 10 nm to the light having 450-700 nm wavelength range; and the liquid crystal display panel having the polarizer on at least one surface thereof. Since the polarizer (1) is incorporated in the liquid crystal display panel, the optical path of the light entering the side face of the liquid crystal display panel can be changed to the visible direction efficiently with good directivity through the optical path-changeable slopes of the plurality of light emission means and the illumination light can be restrained from being colored. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polarizing plate capable of forming a liquid crystal display device that is easy to view with a thin, light and bright image with less image disturbance by efficiently changing the optical path of light incident from the side of a liquid crystal display panel in the viewing direction.

  Conventionally, a front light type reflective liquid crystal display device in which a sidelight 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 the side surface direction is reflected through the viewing side cell substrate so that it can be used as illumination light (Patent Document 1).

  However, since the reflected light passing through the rough surface is used as illumination light, there is a problem that it is difficult to obtain a bright display. 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, so that the reflected light is strongly emitted in a direction greatly inclined from the front direction of the liquid crystal display panel. In the normal viewing direction in the front direction, there is a problem that the display is dark.

  In view of the above, an optical film having a light emitting means is bonded to the 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 of the optical film, so that the liquid crystal A method of illuminating a display panel has also been proposed (Patent Document 2). However, there is a problem that the light illuminating the liquid crystal display panel is colored.

Japanese Patent Laid-Open No. 5-158033 JP 2000-147499 A

  The present invention solves the above-described problem of coloring illumination light, and efficiently converts the light incident from the side surface of the liquid crystal display panel in the viewing direction to form a thin, light, bright and easy-to-view liquid crystal display device. The development of a possible optical member is an issue.

  In the present invention, the tilt angle with respect to the plane formed by the polarizing plate is 35 to 48 degrees on the surface of the polarizing plate having a minimum / maximum transmittance of 0.80 or more in a wavelength range of 450 to 700 nm. A polarizing plate comprising a plurality of light emitting means having an optical path changing slope, and a liquid crystal display device comprising the polarizing plate on at least one side of a liquid crystal display panel To do.

  According to the present invention, by incorporating the polarizing plate into the liquid crystal display panel, the light incident from the side of the panel can be optically converted into the viewing direction efficiently and with good directivity through the optical path conversion slope of the light emitting means. Further, coloring of the illumination light can be suppressed, and a thin, light, bright and easy-to-view liquid crystal display device can be formed based on the coloration. The suppression of the coloration is due to the investigation of the cause of coloration according to the prior art and the use of a polarizing plate with little variation in transmittance due to wavelength.

  That is, the cause of coloring in the prior art is due to the large variation in transmittance depending on the wavelength in the polarizing plate. Incidentally, when the difference in transmittance due to the wavelength in the polarizing plate is large, an opening is generated in the amount of transmitted light depending on the wavelength, and the opening (difference) increases every time the light passes through the polarizing plate.

  When the polarizing plate is disposed in a liquid crystal display panel and light is incident from the side of the panel and the inside of the panel is transmitted in the horizontal direction, the ratio of wavelength light having a high transmittance every time the transmitted light passes through the polarizing plate. The ratio of the wavelength light having a low transmittance is reduced, whereby the transmitted light and the illumination light are colored. Accordingly, the coloration increases as the distance from the light source arranged on the side surface of the liquid crystal display panel increases. Therefore, by using a polarizing plate with less variation in transmittance depending on the wavelength, it is possible to suppress coloring of transmitted light, and hence illumination light.

Explanation side view of polarizing plate Description plan view of light emitting means Description plan view of other light emitting means Still another plan view of light emitting means Explanation side view of liquid crystal display

  The polarizing plate according to the present invention has an inclination angle of 35 with respect to a plane formed by the polarizing plate on the surface of the polarizing plate having a minimum / maximum transmittance of 0.80 or more in a wavelength range of 450 to 700 nm of 0.80 or more. A plurality of light emitting means having an optical path changing slope of ˜48 degrees are provided. An example thereof is shown in FIG. 1 is a polarizing plate having a light emitting means, 1A is a light emitting means forming layer, 1C is a polarizing plate, A is a light emitting means, and a is an optical path changing slope. In addition, 1B and 1D are transparent protective layers which form a polarizing plate.

  As the polarizing plate, one having a minimum / maximum transmittance of 0.80 or more, particularly 0.85 or more, particularly 0.90 or more in the wavelength range of 450 to 700 nm is used. Thereby, the difference in transmittance depending on the wavelength can be reduced, the color of light transmitted through the liquid crystal display panel can be made neutral, and coloring of illumination light can be suppressed.

  The polarizing plate exhibiting the above-mentioned properties is, for example, a transmittance of every 10 nm in a wavelength region of 450 to 700 nm, such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, and an ethylene / vinyl acetate copolymer partially saponified film. A hydrophilic polymer film having a minimum / maximum value of 0.80 or more, especially 0.85 or more, particularly 0.90 or more is adsorbed with a dichroic substance such as iodine or a dichroic dye and stretched. Examples thereof include a polarizing film.

  Moreover, the polarizing plate may be provided with transparent protective layers 1B and 1D on one side or both sides of the polarizing film 1C as in the example of FIG. The transparent protective layer can be formed using one or two or more kinds of appropriate materials showing transparency according to the wavelength range of light incident through a light source or the like. The transparency is preferably such that the minimum / maximum transmittance of 10 nm in the wavelength range of 450 to 700 nm is 0.80 or more, especially 0.85 or more, particularly 0.90 or more.

  Incidentally, as a material for the visible light region for forming the transparent protective layer, for example, acrylic resins, polycarbonate resins, cellulose resins, norbornene resins, transparent resins represented by polyolefin resins, heat, ultraviolet rays, electron beams, etc. And a curable resin that can be polymerized by radiation. 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 liquid crystal display device with less display unevenness by suppressing brightness unevenness and color unevenness, a preferable transparent protective layer does not exhibit birefringence or has low birefringence, especially, an in-plane average phase difference. Is 30 nm or less. By using a transparent protective layer having a small phase difference, when linearly polarized light is incident, the polarization state can be maintained well, which is advantageous for preventing deterioration in display quality. From the viewpoint of preventing display unevenness, a preferable average in-plane retardation in the transparent protective layer is 20 nm or less, in particular 15 nm or less, particularly 10 nm or less, and the variation of the retardation in each place is as small as possible. More preferred.

  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, more preferably 30 nm or less, and particularly preferably 20 nm or less from the viewpoint of preventing display 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. 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 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 perpendicular 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.

  Furthermore, from the point of increasing the incident efficiency to the light path changing slope of the light emitting means to obtain a liquid crystal display device that is bright and excellent in its uniformity, its refractive index is equal to or higher than that of the liquid crystal cell, particularly its cell substrate, In particular, a transparent protective layer of 1.49 or more, particularly 1.52 or more is preferably used.

  In the case of using the front light system, the refractive index is preferably 1.6 or less, especially 1.56 or less, particularly 1.54 or less from the viewpoint of suppressing surface reflection. Note that such a refractive index is generally based on D-rays in the visible light region, but is not limited to the above when there is specificity in the wavelength region of incident light, and depends on the wavelength region. Yes (the same applies below).

  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. Incidentally, in the example of FIG. 1, the transparent protective layer on the side having the light emitting means is made of a laminate in which the light emitting means forming layer 1A is integrated with the transparent film 1B, and the transparent protective layer 1D on the other side is made of a single layer. Become.

  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. The transparent protective layer can be bonded to the polarizing film using an appropriate transparent adhesive such as polyvinyl alcohol. In the case where the transparent protective layer has a light emitting means, an adhesion treatment with an appropriate transparent adhesive such as acrylic or rubber is preferable.

  The light emitting means provided on the surface of the polarizing plate can be provided, for example, as a transparent protective layer as described above, or the light emitting means is formed on a transparent film, and the transparent film is adhered to the polarizing plate via an adhesive layer. Can also be provided. In the case where the light emitting means is provided as a transparent protective layer, it can be formed as a transparent protective layer composed of a single layer of only the light emitting means forming layer 1A in the example of FIG. 1, and thus the transparent film 1B can be omitted.

  A general form of the polarizing plate has light emitting means only on one surface as shown in the figure, and the light emitting means is located outside.

  The light emitting means A in the polarizing plate 1 is arranged so that the formation surface of the light emitting means is on the outer side in the direction along the cell plane of the liquid crystal cell having the light source 51 on the side surface as illustrated by the broken line arrow in FIG. Then, the incident light from the side surface by the light source or its transmitted light is reflected through the optical path changing slope a to change the optical path to the back side (polarizing plate side), and accordingly to the viewing direction of the liquid crystal display panel, and to the polarizing plate 1C side. It is an object of the present invention to allow the emitted light to be used as illumination light (display light) for a liquid crystal display panel or the like.

  The light emitting means is provided with an optical path changing inclined surface a having an inclination angle θ1 of 35 to 48 degrees with respect to the plane formed by the polarizing plate as in the example of FIG. Accordingly, the incident light from the side surface direction by the light source arranged on the side surface of the liquid crystal cell or the transmitted light is optically converted to the back surface side, and hence the polarizing plate side through the optical path conversion inclined surface a, and is normal to the liquid crystal cell. The light having excellent directivity can be emitted from the polarizing plate efficiently using the light from the light source.

  When the inclination angle of the optical path conversion slope is less than 35 degrees, when a light reflection layer is disposed on the back side of the liquid crystal cell and the optical path conversion light is reflected, the display light based on the reflected light is emitted from the liquid crystal display panel. The angle exceeds 30 degrees, which is disadvantageous for visual recognition. On the other hand, if the angle of inclination of the optical path conversion slope exceeds 48 degrees, light is not easily reflected and light leakage is likely to occur from the slope, and light utilization efficiency is reduced.

  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 rough surface is used, it is difficult to reflect in the vertical direction, and the direction is greatly inclined from the front direction of the liquid crystal display panel. The liquid crystal display becomes dark and the contrast becomes poor.

  From the point of achieving a bright and easy-to-view liquid crystal display by efficiently totally reflecting through the light path changing slope and emitting from the polarizing plate with good directivity in the normal direction of the plane formed by the polarizing plate. The preferable inclination angle θ1 of the optical path conversion inclined surface is 38 to 45 degrees, especially 40 to 43 degrees.

  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. 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.

  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. In addition, a recessed part means that it is recessed in the polarizing plate (groove), and a convex part means that it protrudes out of the polarizing plate (mountain).

  A plurality of light emitting means are formed for the purpose of downsizing and consequently thinning. In that case, as illustrated as a plan view in FIGS. 2 to 4, a plurality of light emitting means are distributed in a state where light emitting means continuous from one side to the other side are arranged in a stripe shape, or in a discontinuous and intermittent state. Can be formed.

  The light emitting means may be distributed in parallel as shown in the example of FIG. 2 or irregularly distributed as shown in the example of FIG. You may do it. Furthermore, as in the example of FIG. 4, the distribution state may be arranged in a pit shape with respect to the virtual center.

  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 light path conversion inclined surface a reflects the incident light from the side surface direction by the light source in the illumination mode in the direction of the polarizing plate, thereby converting the light path, so that the light emitting means having such an optical path conversion inclined surface is provided. A surface light source that efficiently illuminates the liquid crystal cell by changing the light path from the side direction through the light source by distributing the light so that the total light transmittance is 75 to 92% and the haze is 4 to 20%. To achieve a bright and excellent contrast liquid crystal display.

  Such characteristics of total light transmittance and haze can be achieved by controlling the size and distribution density 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 1/100. ˜1 / 8, especially 1/50 to 1/10, especially 1/30 to 1/15.

  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 for the liquid crystal cell is also liable to be lowered. In consideration of the above, when the continuous light emitting means are distributed in parallel as in the example of FIG. 2, the pitch is 2 mm or less, especially 20 μm to 1 mm, especially 50 to 500 μm, and the optical path conversion with respect to the plane formed by the polarizing plate It is preferable that the projected width of the slope is 40 μm or less, especially 3 to 20 μm, especially 5 to 15 μm.

  Note that the distribution of the continuous light emitting means may be parallel to one side of the polarizing plate, or may be arranged in an intersecting state within 30 degrees. The latter is effective in preventing moire due to interference with the pixels of the liquid crystal cell. Further, moire prevention can also be performed by adjusting the arrangement pitch. Therefore, the pitch may change or may not be constant.

  On the other hand, in the case where discontinuous light emitting means are distributed in parallel or irregularly as shown in the examples of FIGS. Considering the reflection efficiency due to the optical path conversion slope, it is preferable that the length of the optical path conversion slope is not less than 5 times the depth of the light emission means, especially 8 or more, especially 10 or more.

  The length of the optical path conversion 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 μm 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.

  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 emission from the back surface, and it is preferable that display quality, light transmission, and light emission are not affected as much as possible.

  Incidentally, if the inclination angle θ2 of the vertical plane with respect to the plane formed by the polarizing plate is small, the projected area of the vertical plane with respect to the plane becomes large, and as shown in FIG. In the light mode, the surface reflected light from the elevation surface returns to the observation direction, and the display quality tends to be hindered.

  Accordingly, it is advantageous that the inclination angle θ2 such as the vertical surface is larger, and thereby the projected area with respect to the plane formed by the polarizing plate can be reduced, and the decrease in the total light transmittance can be suppressed. Further, 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 polarizing plate, thereby suppressing the influence on the liquid crystal display. 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.

  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 is constant over the entire surface of the sheet, or in response to absorption loss or attenuation of transmitted light due to the previous 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 the light incident side increases.

  Further, the light emitting means with a constant pitch can be used, or as shown in FIGS. 3 and 4, the pitch is gradually narrowed away from the side of the light incident side (arrow) and the distribution density of the light emitting means is increased. It is also possible to increase the number. Furthermore, the light emission on the polarizing plate 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.

  As shown in the example of FIG. 1, it is preferable that the light path changing slope in the light emitting means faces the direction (arrow) of the incident light from the side surface direction of the liquid crystal cell from the viewpoint of improving the emission efficiency. Therefore, when a linear light source is used, it is preferable that the optical path changing slope is oriented in a direction with respect to one side of the polarizing plate or a certain direction as illustrated in FIGS. Further, when a point light source such as a light emitting diode is used, it is preferable that the light path changing inclined surface is directed toward the light emission center of the point light source as in the example of FIG.

  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.

  The surface of the polarizing plate must be a flat surface that is as smooth as possible, except for the light emitting means, and it should be a flat surface with an angle change of ± 2 degrees or less, especially 0 degrees. Is preferred. The angle change is preferably within 1 degree per 5 mm length. By adopting such a flat surface, most of the polarizing plate can be made a smooth surface with an angle change of 2 degrees or less, light transmitted through the liquid crystal cell can be used efficiently, and the image is not disturbed uniformly. Light emission can be achieved.

  As described above, the pit-like arrangement of the light emitting means A as illustrated in FIG. 4 is such that a point light source is arranged on the side surface of the liquid crystal display panel and the radial incident light from the side direction by the point light source or its The transmission light is converted into an optical path through the optical path conversion slope a, and the polarizing plate 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 used for the light source light. It aims at making it radiate | emit from.

  Therefore, the pit arrangement is preferably performed so that a virtual center is formed on the end face of the polarizing plate or on the outside thereof so that the arrangement of the point light sources can be facilitated. The virtual center can form one place or two places or more with respect to the same or different polarizing plate end faces.

  Formation of the layer having the light emitting means can be performed 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.

  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 a polarizing plate having a light emitting means by using a polarizing plate for the transparent film.

  The above-described method is advantageous for forming a transparent protective layer having the light emitting means integrally formed by integrally forming the transparent protective layer having the light emitting means. In particular, the latter method using a transparent film is formed by adding a light emitting means forming layer 1A separately from the transparent protective layer 1B as shown in FIG. In that case, if the difference in refractive index between the light emitting means forming layer to be added and the transparent protective layer is large, the emission efficiency may be greatly reduced due to interface reflection or the like.

  Therefore, from the viewpoint of suppressing the reduction of the emission efficiency, the difference in refractive index between the transparent protective layer and the light emitting means forming layer should be made as small as possible, especially within 0.10, especially within 0.05. It is preferable. In this case, it is preferable from the viewpoint of emission efficiency that the refractive index of the light emitting means forming layer to be added is higher than that of the transparent protective layer. For the formation of the light emitting means forming layer, an appropriate transparent material corresponding to the wavelength range of incident light can be used according to the transparent protective layer.

  In addition, in the method using the said film, the method of isolate | separating the formed light-projection means formation layer and film after the polymerization process using what processed the film with the release agent etc. can also be taken. In that case, the film to be used may not be transparent.

  If necessary, the light emitting means forming surface can be subjected to non-glare treatment, antireflection treatment for preventing visual obstruction due to surface reflection of external light, hard coat treatment for preventing scratches, and the like. A polarizing plate subjected to such treatment can be preferably used particularly for a front light system.

  The non-glare treatment described above can be performed by making the surface fine concavo-convex structure by various methods such as a roughening method such as a sand blast method or an embossing method, or a resin coating method in which transparent particles such as silica are blended. it can. The antireflection treatment can be performed by a method of forming an interfering vapor deposition film. Further, the hard coat treatment can be performed by a method of applying a hard resin such as a curable resin. The non-glare treatment, the antireflection treatment and the hard coat treatment can be applied to a film adhesion method or the like subjected to one or more treatments.

  An adhesive layer for adhering a transparent film or the like having a light emitting means forming surface to a polarizing plate, if necessary, can be provided on one or both of them. The purpose of the bonding process via the bonding layer is to improve the reflection efficiency through the light path changing slope a of the light emitting means A, and consequently the luminance by effective use of incident light from the side surface direction.

  In view of the above-mentioned purpose, it is preferable that the adhesive layer has a small refractive index difference between the transparent film having the light emitting means forming surface and the polarizing plate. The preferred adhesive layer has a light emitting means forming surface from the viewpoint of obtaining a liquid crystal display device that is bright and excellent in uniformity by suppressing the total reflection to increase the incident efficiency of the liquid crystal cell transmission light to the light emitting means. It has a refractive index equal to or higher than the refractive index 0.07 lower than that of a transparent film or the like, and has a refractive index higher or close to that of the cell substrate of the liquid crystal cell.

  Incidentally, when the refractive index is lower than that of the cell substrate of the liquid crystal cell, incident light from the side surface is likely to undergo total reflection during the transmission. Typically, a resin plate or an optical glass plate is used for the cell substrate, and in the case of a non-alkali glass plate, the refractive index is generally about 1.51 to 1.52, so that the refractive index is ideally higher than that. By adhering through an adhesive layer having a surface, most of the transmitted light having an angle that can be incident on the transparent film having the light emitting means forming surface from the cell is not totally reflected at the adhesive interface, and the transparent film is It can be made incident.

  Light transmission optics such as adhesive layers, liquid crystal cells, and transparent protective layers from the standpoint of improving display brightness and in-plane brightness uniformity by suppressing the amount of light that cannot be emitted by confinement based on total reflection. The preferred refractive index difference at each interface between the layers is within 0.15, in particular within 0.10, in particular within 0.05. Therefore, the preferable refractive index of the adhesive layer is 1.49 or more, especially 1.50 or more, particularly 1.51 or more. Therefore, it is preferable that the adhesive layer for adhering the polarizing plate to the liquid crystal cell or the like also satisfies the refractive index condition.

  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 adhesive based on an appropriate polymer such as rubber, acrylic, vinyl alkyl ether, silicone, polyester, polyurethane, polyether, polyamide, styrene, etc. Can be used. 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 adhesive layer includes, for example, inorganic particles such as silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and nonmony oxide, and organic particles such as a crosslinked or uncrosslinked polymer. One kind or two or more kinds of appropriate transparent particles may be contained to obtain a light diffusion type. Such transparent particles can also be used for the non-glare treatment described above.

  A transparent adhesive layer for adhering to other members such as a liquid crystal cell can be provided on the polarizing plate, if necessary. The adhesive layer can conform to the above. It should be noted that it is preferable to temporarily cover the adhesive layer with a release sheet for the purpose of preventing foreign matters from being mixed in until the adhesive layer is put into practical use.

  The polarizing plate according to the present invention has an optical path in the direction (normal direction) excellent in perpendicularity advantageous for visual recognition of incident light from the side surface by the light source or its transmitted light through the light emitting means (optical path changing slope). It converts and emits light efficiently. In addition, it can exhibit good transparency with respect to external light.

  Therefore, for example, various devices such as a bright and easy-to-view thin and light reflective type and transmissive type, or a transflective type liquid crystal display device for both external light and illumination can be formed. An example of the liquid crystal display device is shown in FIG. The figure shows an example of a liquid crystal display device of a reflection type and a front light type, both for external light and illumination. 20 and 30 are cell substrates in the liquid crystal cell, 40 is a liquid crystal layer, and 31 is a light reflecting layer.

  As shown in the figure, the liquid crystal display device can be formed as having the polarizing plate 1 having the light emitting means A on at least one side of the liquid crystal display panel. In that case, the polarizing plate having the light emitting means is generally arranged so that the side having the light emitting means is on the outside. The polarizing plate is preferably bonded to a liquid crystal cell or the like through an adhesive layer from the viewpoint of achieving bright display.

  One or two or more illumination mechanisms are provided on one or more side surfaces of the liquid crystal cell as shown in the figure, particularly on one or more side surfaces of the cell substrate 20 on the side where the polarizing plate 1 having the light emitting means is arranged. The light source 51 can be arranged. In the case of the polarizing plate having the light emitting means having the pit-like arrangement as shown in FIG. 4 at the time of formation, the pit-like arrangement is achieved from the point of achieving a bright display by efficiently using the radial incident light from the point light source. It is preferable to arrange a point light source on the side surface of the liquid crystal cell on the vertical line including the virtual center of the light emitting means.

  In such an arrangement of the point light sources corresponding to the virtual center, depending on whether the virtual center of the light emitting means is on the end face of the polarizing plate or on the outside thereof, the dot shape of the cell substrate 20 is as shown in the example of FIG. Appropriate countermeasures such as a method of projecting the side where the light source is disposed can be taken. The same applies when other light sources such as a linear light source are arranged.

  As the light source disposed on the side surface of the liquid crystal cell, an appropriate light source can be used. For example, in addition to the above-described point light sources such as light-emitting diodes, linear light sources such as (cold, hot) cathode tubes, array bodies in which point light sources are arranged in a line or surface, or point light sources and linear light sources. A combination of light plates and converting incident light from a point light source into a linear light source via a linear light guide plate can be preferably used.

  In addition, it is preferable from the viewpoint of emission efficiency that the light source is disposed on the side surface of the cell where the optical path changing slope of the polarizing plate faces. Including the above-mentioned pit arrangement, the incident light from the side via the light source is efficiently converted to a surface light source by arranging the light path conversion slope to face the light source as vertically as possible. Thus, light can be emitted with high efficiency.

  Therefore, in the case of a polarizing plate having a light emitting means having a plurality of optical path conversion slopes, such as a cross section having two optical path conversion slopes such as an isosceles triangle, both of the opposing side faces of the cell substrate are provided. A number of light sources corresponding to a plurality of optical path changing slopes can also be arranged. In the case of the pit arrangement, the point light sources can be arranged at one place or two or more places corresponding to the virtual center of the light emitting means in the polarizing plate.

  The light source can be viewed in the illumination mode by turning on the light source. In the case of an external light / illumination type liquid crystal display device, the light source does not need to be turned on when viewing in the external light mode by external light. It can be switched on / off. As the switching method, any method can be adopted, and any of the conventional methods can be adopted. The light source may be of a different color light emission type capable of switching the emission color, or may be capable of emitting different color light via different light sources.

  As shown in the example of FIG. 5, the light source 51 may be a combined body in which appropriate auxiliary means such as a reflector 52 surrounding the light source 51 is disposed to guide the divergent light to the side surface of the liquid crystal cell as necessary. As the reflector, an appropriate reflecting 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 light source, such as by bonding its end to the end of a cell substrate or the like.

  In general, a liquid crystal display device appropriately assembles components such as a liquid crystal cell that functions as a liquid crystal shutter, a driving device associated therewith, a front light or a backlight (polarizing plate), and a light reflection layer and a retardation plate as necessary. And so on. In the present invention, there is no particular limitation except that the illumination mechanism is formed using the polarizing plate and the light source described above, and it can be formed according to a conventional front light type or backlight type.

  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.

  Incidentally, as specific examples of the liquid crystal cell, twist type, non-twist type, guest host type 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 a ferroelectric liquid crystal cell 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.

  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. In such a case, the polarizing plate having the light emitting means is generally arranged on the viewing side of the liquid crystal display panel as shown in the figure to form a front light type liquid crystal display device. The liquid crystal is usually driven through electrodes 21 and 31 provided inside the cell substrate as in the example of FIG.

  In the reflective liquid crystal display device, the arrangement of the light reflecting layer is essential. The arrangement position may be provided inside the liquid crystal cell as illustrated in FIG. 5 or may be provided outside the liquid crystal cell. Therefore, in the example of FIG. 5, the electrode 31 also serves as a light reflection layer. The reflection type liquid crystal display device according to the present invention can generally be used as an external light / illumination type.

  As for the light reflection 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 attachment layer of a metal thin film by a vapor deposition method, and the coating layer In addition, it can be formed as an appropriate light reflecting layer according to the prior art, such as a reflective sheet having a supporting layer supported by a base material, a metal foil, a transparent conductive film, or a dielectric multilayer film. In the case of a transmissive liquid crystal display device for both external light and illumination, the light reflecting layer disposed outside the polarizing plate on the back side can also be made appropriate according to the above.

  On the other hand, a transmissive liquid crystal display device can be formed by disposing a polarizing plate having light emitting means on the back side of the liquid crystal cell. In that case, by providing a light reflecting layer on the back side (outside) of the light emitting means, the light leaking from the light path changing slope etc. is reflected and returned to the direction of the liquid crystal cell, so that it can be used for cell lighting, improving the brightness. Can be planned.

  In the above case, by making the light 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 light reflecting layer, the liquid crystal display device can be used as a transmissive liquid crystal display device for both external light and illumination.

  On the other hand, a transflective liquid crystal display device can be formed by using a light-reflecting layer in the above-described reflective type as a semi-transmissive light reflecting layer that reflects and transmits light. In that case, the polarizing plate having the light emitting means can be disposed on the viewing side of the liquid crystal cell, but is generally preferably disposed on the back side. A polarizing plate having light emitting means can be disposed on both the viewing side and the back side.

  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 of having a polarizing plate having a light emitting means on the back side of the liquid crystal display panel and the back side of the liquid crystal display panel, a light reflection layer is disposed on the back side (outside) of the polarizing plate. Thus, the luminance can be further improved. This means that light that has passed through the semi-transmissive light reflecting layer or reflected to reach the back surface of the liquid crystal display panel can be reflected and inverted by the light reflecting layer and re-entered into the liquid crystal cell. by.

  The semi-transmissive light reflecting layer is an appropriate method such as a method in which the above-described light reflecting layer reflects and transmits light like a half mirror, or a method in which a light transmitting opening is provided in the light reflecting layer. It can be carried out. The openings are preferably distributed so as to correspond to the pixels of the liquid crystal cell.

  In the transmissive type and transflective type described above, in addition, in the reflective type in which the light reflecting layer is arranged outside the liquid crystal cell, the cell substrate or electrode is made of a transparent substrate, transparent electrode, etc. in order to enable liquid crystal display. Thus, it is necessary to form it so that light can be transmitted.

  On the other hand, when the electrode 31 serving also as a light reflection layer is provided inside the liquid crystal cell as in the example of FIG. 5, the cell substrate 20 and the electrode 21 on the viewing side are transparent substrates in order to enable liquid crystal display. However, the cell substrate 30 on the back side does not have to be transparent like the light reflection layer 31 and is formed of an opaque body. Also good.

  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 light source 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, from the viewpoint of balance between light transmission efficiency and thin and light weight.

  The thickness of the cell substrate may be different between the side where the light source is arranged and the side where the light source is not arranged, or may be the same thickness. From the viewpoint of improving luminance, it is advantageous to make the cell substrate on the side where the light source is arranged thicker. Therefore, when the light sources are arranged on the side surfaces of both the viewing side and the back side cell substrates, it is advantageous to use cell substrates having the same thickness.

  When forming the liquid crystal cell, as in the example of FIG. 5, as necessary, alignment films 22 and 32 such as a rubbing film for aligning liquid crystals, a color filter 23 for realizing color display, and a low refractive index layer 24. A phase difference plate 25 or the like can be provided. 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.

  For the purpose of controlling the display light via the linearly polarized light, another polarizing plate can be arranged on the liquid crystal cell side that does not have the polarizing plate according to the present invention, if necessary. Therefore, the polarizing plate can be disposed at an appropriate position on one or both of the viewing side and the back side of the liquid crystal cell.

  The low refractive index layer described above efficiently transmits the incident light from the side direction through the light source to the rear in the direction far away from the light source, and the light efficiently enters the light path changing slope behind. Thus, the object is 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.

  The low refractive index layer is disposed on the inner side of the cell substrate 20 on which the light source 51 is disposed as shown in the example of FIG. 5, that is, on the opposite side of the substrate from the side where the polarizing plate is provided, in order to improve the brightness of the cell display. preferable. 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, is preferable from the viewpoint of improving the brightness of the cell display. Accordingly, when light sources are arranged on the side surfaces of both the viewing side and the back side cell substrates, it is preferable to provide a low refractive index layer on both of the cell substrates.

  When forming a liquid crystal display device, if necessary, a liquid crystal display panel having one or more appropriate optical layers such as a light diffusing layer and a retardation plate in addition to the above-described non-glare layer may be used. . Such optical layers such as a light diffusing layer and a retardation plate can be applied to a liquid crystal cell as an integrated body laminated with a polarizing plate having a light emitting means, if necessary, through an adhesive layer or the like.

  The purpose of the light diffusion layer is to expand the display range by diffusing the display light, to make the luminance uniform by leveling the light emission, and to increase the amount of incident light on the polarizing plate by diffusing the transmitted light in the liquid crystal cell. The light diffusing layer can be provided by an appropriate method using a coating layer having a fine surface relief structure according to the non-glare layer, a diffusion sheet, or the like.

  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 and the cell substrate on the viewing side.

  On the other hand, the retardation plate is used for the purpose of forming an antireflection layer composed of a circularly polarizing plate or an elliptically polarizing plate in cooperation with the polarizing plate, expanding the viewing angle by optical compensation, and preventing coloring. As the retardation plate, one layer or two or more layers can be used. Usually, as shown in FIG. 5, the retardation plate is disposed between the polarizing plate on the viewing side and / or the back side and the cell substrate. Therefore, for the polarizing plate having the light emitting means, the retardation plate is disposed on the side not having the light emitting means.

  As the phase difference plate, a plate exhibiting an appropriate phase difference can be used according to the purpose and the type of the liquid crystal cell. In general, those showing a phase difference of 50 to 700 nm are used. Incidentally, the above-described circularly polarizing plate can be formed by using a quarter-wave plate having a phase difference of, for example, 100 to 150 nm. Moreover, in that case, the wavelength range which functions as a circularly-polarizing plate can be expanded by using together the 1/2 wavelength plate whose phase difference is 200-300 nm etc., for example.

  There is no limitation in particular about the angle of the optical axis of a phase difference layer and a polarizing plate. In the case of laminating them via an adhesive layer, it is preferable to use an adhesive layer having a refractive index of 1.49 or more, especially 1.50 or more, particularly 1.51 or more, as described above.

  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 alignment film of an appropriate liquid crystal polymer such as a nematic or discotic type, The alignment layer can be obtained as a material supported by a transparent substrate. It may be one in which the refractive index in the thickness direction is controlled under the action of the heat shrinkage force of the heat-shrinkable film.

  Note that in the reflective liquid crystal display device illustrated in FIG. 5 described above, the light that is emitted from the back surface of the polarizing plate 1 is visible in the illumination mode by turning on the light source 51, as indicated by the arrow in the figure. After being reflected by the light reflecting layer 31 via the liquid crystal cell, the light passes through the liquid crystal cell to reach the polarizing plate, and the display light transmitted from the portion other than the light emitting means A is visually recognized.

  On the other hand, in the external light mode by turning off the light source, the light incident from the portion other than the light emitting means on the light emitting means forming surface of the polarizing plate 1 passes through the light reflecting layer 31 and reversely passes through the liquid crystal cell according to the above. Accordingly, the display light transmitted through the portion other than the light emitting means is visually recognized.

  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 light source is turned on. The display light which permeate | transmitted etc. is visually recognized. In the external light mode by turning off the light source, the external light incident from the viewing side surface passes through the liquid crystal cell and reaches the polarizing plate on the back side, and the light incident from the portion other than the light emitting means on the light emitting means forming surface. Is inverted through the light reflecting layer provided on the back surface, and the display light transmitted through the liquid crystal cell in the reverse direction is visually recognized.

  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. According to the device, visual recognition of the display light in the illumination mode or the external light mode is achieved.

  In the present invention, each component forming the above-described liquid crystal display device may be laminated or integrated as a whole or partially and fixed, or may be arranged in an easily separated state. From the standpoint of preventing a decrease in contrast due to suppression of interface reflection, it is preferable to be in a fixed state, and it is preferable that at least a polarizing plate having a light emitting means and a liquid crystal cell 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.

  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.

Reference Example After depositing magnesium fluoride on a non-alkali glass plate having a refractive index of 1.52 to form a low refractive index layer and performing a plasma treatment in an argon atmosphere, indium tin oxide (ITO) was formed thereon. ) A transparent conductive layer was formed by a sputtering method, a polyvinyl alcohol solution was spin-coated thereon, and the dried film was rubbed to obtain cell substrates on the viewing side and the back side.

  Next, after placing the gap adjusting material made of spherical glass beads with the rubbing surfaces facing each other so that the rubbing surfaces are orthogonal to the cell substrates on the viewing side and the back side, the periphery is sealed with epoxy resin. Liquid crystal (a mixture of 1 part by weight of a chiral agent (Merck, MC-32) was injected into 200 parts by weight of BDH, E-7: 200 parts by weight) to form a liquid crystal cell.

Example 1
A transparent film made of polycarbonate (PC) with a thickness of 60 μm is coated with an ultraviolet curable acrylic resin with a thickness of about 100 μm, and the coated layer is brought into close contact with a mold that has been processed into a predetermined shape with a rubber roller. At the same time, excess resin and bubbles were extruded, and then cured by irradiating with ultraviolet rays with a metal halide lamp, and then peeled off from the mold and cut into a predetermined size to obtain a transparent protective layer equipped with light emitting means. In addition, it was 1.515 when the refractive index of the ultraviolet curable resin after hardening was measured.

  The transparent protective layer is 30 mm square, has a length of about 100 μm, a width of about 10 μm, and a plurality of triangular light emitting means (FIG. 1) are distributed in parallel and irregularly to one side ( 3), the inclination angle of the optical path conversion slope is 43 degrees, and the elevation 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.

  Next, the side having no light emitting means of the transparent protective layer and the polyvinyl alcohol film-type polarizing plate were pressure-bonded with a pressure-bonding roller through an acrylic pressure-sensitive adhesive layer having a refractive index of 1.523 to obtain a polarizing plate. Next, the polarizing plate was bonded to the viewing side of the liquid crystal cell obtained in the reference example through the adhesive layer with the light emitting means forming surface as the outside, and then the polarizing plate provided with the light reflecting layer was similarly applied to the back side of the cell. A reflective liquid crystal display device was obtained by bonding. The minimum value / maximum value (hereinafter the same) of the transmittance for every 10 nm in the wavelength range of 450 to 700 nm is 0.97 for the polarizing plate on the viewing side and 0.79 for the polarizing plate on the back side.

Example 2
A reflective liquid crystal display device was obtained in the same manner as in Example 1 except that a polarizing plate on the viewing side used a transmittance having a minimum value / maximum value of 0.89.

Comparative Example A reflective liquid crystal display device was obtained in the same manner as in Example 1 except that a polarizing plate on the viewing side had a minimum / maximum transmittance of 0.79.

Evaluation test A cold cathode tube is arranged on the side of the viewing side cell substrate of the reflective liquid crystal display device obtained in the examples and comparative examples, and is surrounded by a silver-deposited polyester film. In the case where the cold cathode tube is held and fixed with an adhesive tape, the cold cathode tube is turned on in the dark room without applying a voltage to the liquid crystal cell, and is 5 mm from the incident side surface, 5 mm from the center, and 5 mm from the opposite end. The hue of the outgoing light in the front direction was examined with a luminance meter (Topcon, BM7).

The results are shown in the following table. The hues in the table are indicated by x and y based on the CIE 1931 standard color system.

Hue
Center of incident side face Opposite end
xy xy xy
Example 1 0.312 0.334 0.315 0.348 0.317 0.360
Example 2 0.320 0.347 0.329 0.375 0.335 0.395
Comparative Example 0.333 0.363 0.363 0.411 0.385 0.441

  From the table, it can be seen that the color change of the emitted light is smaller in the example than in the comparative example and is closer to neutral. Further, it can be seen that in Example 1 as compared with Example 2, the better the results are obtained as the color change is smaller and the variation in transmittance is smaller. Visually, almost no color change was perceived in Example 1, but in Example 2, a slight color change was made close, although it was within an allowable range. On the other hand, in the comparative example, the emitted light was colored in yellow, and the color became stronger as the distance from the light source became farther, and was not acceptable.

  Further, in the example, in both the illumination mode and the outside light mode, the display was excellent in brightness and uniformity on the entire surface of the panel. As described above, in the present invention, surface emission is possible by simply providing a light source on the side surface of the liquid crystal display panel on which the polarizing plate is disposed, while avoiding the increase in bulk and weight due to the use of the conventional sidelight type light guide plate It can be seen that a transmissive, reflective, and transflective liquid crystal display device that is thin, light, and has little color change can be formed.

1: Polarizing plate 1A: Light emitting means forming layer A: Light emitting means a: Optical path changing slope)
1B, 1D: Transparent protective layer 1C: Polarizing plate 20, 30: Cell substrate 40: Liquid crystal layer 51: Light source

Claims (18)

An optical path conversion slope having an inclination angle of 35 to 48 degrees with respect to a plane formed by the polarizing plate on the surface of the polarizing plate having a minimum / maximum transmittance of 0.80 or more in a wavelength range of 450 to 700 nm of 0.80 or more. A polarizing plate comprising a plurality of light emitting means comprising: The polarizing plate according to claim 1, wherein the polarizing plate has an adhesive layer on a side not having the light emitting means. The polarizing plate according to claim 2, wherein the adhesive layer is an adhesive layer. 4. The polarizing plate according to claim 1, wherein the light emitting means is a concave portion. 5. The polarizing plate according to claim 4, wherein the concave portion forming the light emitting means has a triangular shape based on a cross section with respect to the optical path changing slope. In claim 4 or 5, the length of the long-side direction of the optical path changing slope in the concave portion forming the light emitting means is 500 μm or less and not less than five times the depth of the concave portion, and the depth of the concave portion is not more than 100 μm, A polarizing plate having a width of 100 μm or less in a direction perpendicular to the long side direction and the depth direction of the optical path conversion slope. 7. The polarizing plate according to claim 4, wherein a surface facing the optical path changing slope in the concave portion forming the light emitting means is an elevation surface having an inclination angle of 60 to 90 degrees with respect to a plane formed by the polarizing plate. 8. The polarizing plate according to claim 4, wherein the concave portion forming the light emitting means is arranged in parallel or irregularly based on the optical path changing slope or in a pit shape with respect to the virtual center. The polarizing plate according to claim 1, wherein the transparent film having the light emitting means is bonded to the polarizing plate through an adhesive layer. The polarizing plate according to claim 9, wherein the transparent film forms a transparent protective layer of the polarizing plate. The polarizing plate according to claim 1, wherein the polarizing plate has one or more retardation plates on the side not having the light emitting means. A liquid crystal display device comprising the polarizing plate according to claim 1 on at least one side of a liquid crystal display panel. 13. The liquid crystal display device according to claim 12, wherein the polarizing plate is bonded via an adhesive layer so that the side having the light emitting means is outside. 14. The liquid crystal display panel according to claim 12 or 13, wherein the liquid crystal display panel comprises a light reflection layer and a reflection type comprising a liquid crystal layer that modulates light through an electric field, and the polarizing plate having the light emitting means is the viewing side of the liquid crystal display panel. A liquid crystal display device disposed on the surface. 14. The liquid crystal display device according to claim 12, wherein the liquid crystal display panel is a transmissive type, and a polarizing plate having a light emitting means is disposed on the back side. 16. The liquid crystal display device according to claim 15, wherein a light reflecting layer is disposed on the back side of the polarizing plate having the light emitting means, and is used for both external light and illumination. The liquid crystal display panel according to claim 12 or 13, wherein the liquid crystal display panel includes a transflective type that includes a transflective light reflecting layer that reflects and transmits light, and the polarizing plate having the light emitting means is provided on the back side or the viewing side. A liquid crystal display device arranged on both the back side. 18. The liquid crystal display device according to claim 17, wherein a light reflecting layer is further disposed on the back side of the back side polarizing plate having light emitting means.

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