JP2003186009A - Polarizing surface light source device and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing surface light source device which has a small attenuation of front luminance and a small hue variation of an illumination color in a form using a polarizing plate and efficiently converts the optical path of light made incident from the side face of a liquid crystal display panel to a visual recognition, thereby makes it possible to form a thin and lightweight liquid crystal display device with bright and easy-to-see display. <P>SOLUTION: The polarizing surface light source device (1) has an optical path control layer (1A) on the surface side of a transparent substrate (1C) having an illuminator on its side face, across at least a polarizing plate (1B), the polarizing plate satisfies the condition of transmissivity of ≥45% and a polarization degree of ≥96%, and/or the condition of a parallel (a pair of absorption axes are parallel) (a) value of -0.4 to -0.3, an orthogonal (a pair of absorption axes cross orthogonally) (a) value of 16 to 18, a parallel (b) value of -0.7 to 0, and an orthogonal (b) value of -57 to -54, and the optical path control layer has a plurality of light emission means each having an optical path conversion surface which reflects incident light from the side face of the transparent substrate to the back of the transparent substrate. The liquid crystal display device has the polarizing surface light source device on one or both of the visual recognition side and back side of the liquid crystal panel. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarized light source device suitable for forming a liquid crystal display device having excellent brightness uniformity and color characteristics.

[0002]

BACKGROUND OF THE INVENTION Conventionally, an optical film having a light emitting means is adhered to a surface of a liquid crystal display panel on the viewing side, and incident light from a light source arranged on the side surface of the panel or transmitted light thereof is reflected through the light emitting means. , A liquid crystal display device in which a liquid crystal display panel is illuminated has been known (Japanese Patent Laid-Open No. 2000-1.
47499 publication). This overcomes the difficulties of bulkiness and weight increase when using a surface light source device consisting of a sidelight type light guide plate, enables thinning and weight reduction, and is a reflection type that is easier to reduce in thickness than a transmissive type. Type liquid crystal display device is utilized.

However, in the form of a polarization plane light source device in which a polarizing plate is arranged between the optical film having the light emitting means and the liquid crystal cell, when light is incident from the side surface of the panel via the light source, As the distance from the light source increases, the front luminance decreases, and the hue of the emitted color changes, which causes a problem of uneven display.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-described problem of attenuation of front luminance and display unevenness due to hue change of emission color in a form having a polarizing plate, and makes light incident from a side surface of a liquid crystal display panel. It is an object of the present invention to develop a polarization plane light source device capable of efficiently forming a liquid crystal display device that is thin, lightweight, bright, and easy to view by efficiently changing the optical path to the viewing direction.

[0005]

According to the present invention, an optical path control layer is provided on a front surface side of a transparent substrate having an illuminating device on a side surface thereof at least through a polarizing plate, and the polarizing plate has a transmittance of 45% or more and a polarized light. 96% or more, or parallel a value −0.4 to −0.
3, the orthogonal a value of 16 to 18, the parallel b value of −0.7 to 0, and the orthogonal b value of −57 to −54, or both of them, and the optical path control layer has incident light from the side surface of the transparent substrate. A polarizing plane light source device characterized by having a plurality of light emitting means having an optical path converting slope for reflecting in the back surface direction of the transparent substrate, and the polarizing plane light source device on the viewing side or the back side of the liquid crystal display panel. The present invention provides a liquid crystal display device characterized by having one or both of them.

In the parallel a-value, the orthogonal a-value, the parallel b-value, and the orthogonal b-value of the above-mentioned polarizing plates, parallel means that the absorption axes of the pair of polarizing plates are parallel, and orthogonal means that of the pair of polarizing plates. Are orthogonalized, and the a value and the b value mean the chromaticness index in the color system of the Hunter's Lab space.

[0007]

According to the present invention, by using the polarizing plate exhibiting the above-mentioned transmittance and polarization degree, the farther from the incident side surface of the transparent substrate on which the illuminating device is arranged, that is, the incident light or its transmitted light is It is possible to suppress a decrease in frontal brightness as the number of opportunities for transmission through the polarizing plate increases, and to obtain a polarized light source device having excellent uniformity of frontal brightness. Further, by using the above-mentioned polarizing plates exhibiting parallel and orthogonal a values and b values, it is possible to suppress an increase in the hue change of the emission color as the distance from the incident side surface increases, and to obtain a polarized light source device with less color unevenness. be able to.

Further, the polarized surface light source device of the present invention can be used as a cell substrate of a liquid crystal cell. By incorporating the polarized surface light source device into the liquid crystal display panel as a cell substrate, the light incident from the side surface of the cell substrate can be efficiently and easily directed through the 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 which can change the optical path in the viewing direction, is thin and lightweight, is bright, has less display unevenness, and is easy to see.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polarized surface light source device according to the present invention comprises an optical path control layer on the front surface side of a transparent substrate having an illuminating device on its side surface via at least a polarizing plate, and the polarizing plate has a transmittance of 45. % Or more and polarization degree 96% or more, or parallel a
Value-0.4 to -0.3, orthogonal a value 16 to 18, parallel b value -0.7 to 0, and orthogonal b value -57 to -54, or both, and the above-mentioned optical path control layer is satisfied. Includes a plurality of light emitting means having an optical path changing slope for reflecting incident light from the side surface of the transparent substrate toward the back surface of the transparent substrate.

The above example is shown in FIGS. Reference numeral 1 is a polarized light source device, 1C is a transparent substrate, 1B is a polarizing plate, and 1A.
Is an optical path control layer, and 51 is an illuminating device. Further, A is a light emitting means, and a is an optical path conversion slope. Note that FIG. 2 shows a liquid crystal display device.

As the transparent substrate, any suitable one can be used according to the conventional cell substrate or light guide plate made of one or more kinds of resin or glass, and is not particularly limited. Incidentally, 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 resin, styrene resin, norbornene resin, thermosetting resin such as acrylic resin, urethane resin, acrylic urethane resin, epoxy resin, silicone resin, or radiation curing resin such as ultraviolet ray and electron beam. To be

Among them, a curable resin such as an epoxy resin is preferable in terms of heat resistance, and a material having excellent transparency such as white sheet glass for blue sheet glass is preferable in terms of transmission of illumination light and transmission of display light. preferable. Further, it is preferable that the resin has a small photoelastic coefficient. Furthermore, from the point that birefringence in the light transmission direction and thickness direction is suppressed as much as possible to reduce light loss and color unevenness, the phase difference is as small as possible and optical isotropy and surface smoothness etc. It is preferable that it is excellent.

The thickness of the transparent substrate is not particularly limited and can be appropriately determined according to the strength and the like according to the purpose of use. When using a cell substrate or light guide plate, considering the balance of strength such as liquid crystal encapsulation, light transmission efficiency and thinness and lightness,
20μm-5mm, especially 50μm-3mm, especially 100μm-
A thickness of 2 mm is common. It is more advantageous that the cross-sectional area is larger than the light transmission substrate in terms of incidence efficiency, transmission efficiency, etc. Therefore, the thicker is preferable. On the other hand, it is more advantageous in terms of thinness and lighter weight than that.

The transparent substrate may be the same thickness plate or may be partially different in thickness. For example, in the case where the thickness is partially different, such as a wedge-shaped cross section in the transmission direction, the inclined arrangement of the light emitting means improves the incidence efficiency of the transmitted light on the optical path conversion slope. Sometimes it is advantageous.

The polarizing plate has a transmittance of 45% or more, preferably 45.2 to 50%, and a polarization degree of 96% or more, particularly 96.5 to 99.999%, or a parallel a. Value is −
Those satisfying one or both of 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. Used. As a result, as described above, it is possible to prevent the luminance from decreasing and the hue change of the emission color from increasing as the distance from the incident side surface increases, which is caused by absorption by the polarizing plate.

A polarizing plate exhibiting the above-mentioned characteristics can be obtained by adding iodine or a dichroic dye to a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film or an ethylene / vinyl acetate copolymer partially saponified film. It can be obtained as a polarizing film or the like which is adsorbed with a dichroic substance such as a functional dye and stretched.

That is, specifically, for example, the polyvinyl alcohol film is dipped in an aqueous solution of iodine or boric acid / potassium iodide for dyeing, and uniaxially stretched to 3 to 7 times the original length. A polarizing plate exhibiting characteristics can be manufactured. When producing the polyvinyl alcohol-based film, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. The washing with water is effective for preventing stains on the film surface and washing and removal of the antiblocking agent, and also for preventing uneven dyeing due to swelling of the film. The stretching treatment can be performed after dyeing, while dyeing, or in a water bath.

The thickness of the polarizing film is generally 5 to 80 μm, but is not limited to this. The polarizing plate may consist of a polarizing film only, or may have a transparent protective layer provided on one side or both sides of the polarizing film. The transparent protective layer can be formed by using one or two or more kinds of appropriate materials exhibiting transparency depending on the wavelength range of light incident through the illumination device or the like.

Incidentally, examples of the material for the visible light region for forming the transparent protective layer include the resins exemplified for the above-mentioned transparent substrate. Above all, those having excellent transparency, mechanical strength, thermal stability and moisture shielding property are preferably used. From the viewpoint of obtaining a polarized light source device with less unevenness in brightness and color, a preferable transparent protective layer is one that does not exhibit birefringence or has small birefringence, and in particular, an average in-plane retardation of 30 nm or less. is there.

By using a transparent protective layer having a small retardation, it is advantageous that the polarization state of linearly polarized light can be favorably maintained when it is incident. From the viewpoint of preventing color unevenness, the average in-plane retardation in the transparent protective layer is 20 nm or less, preferably 15 nm or less, and particularly 10 nm or less, and the variation in each retardation location is as small as possible. The thing is more preferable.

A transparent protective layer made of a material having a small photoelastic coefficient is preferable from the viewpoint of suppressing the internal stress that tends to occur in the transparent protective layer by the adhesive 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 50 nm or less, preferably 30 nm or less, especially 20 nm.
It is preferably not more than nm from the viewpoint of preventing color unevenness. The transparent protective layer having a low retardation can be formed by an appropriate method such as a method of annealing an existing film and a method of removing internal optical strain. A preferable forming method is a method of forming a transparent protective layer having a small retardation by a casting method.

The above-mentioned retardation in the transparent protective layer is preferably based on light in the visible region, particularly light having a wavelength of 550 nm. The above-mentioned in-plane average retardation is the average refractive index in the in-plane maximum refractive index direction nx, the average refractive index in the direction orthogonal to the nx direction ny, the average refractive index in the thickness direction nz, When the average thickness is d, it is defined by (nx−ny) × d, and the average phase difference in the thickness direction is {(nx + ny) /
2-nz} × d.

The transparent protective layer may be formed as a single layer or as a laminated body 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 which has been subjected to a hard coat treatment, an antireflection treatment, a sticking prevention treatment, a diffusion or an antiglare treatment.

The above-mentioned hard coat treatment is carried out for the purpose of preventing scratches on the surface of the polarizing plate. For example, the hardness is set by a suitable curable resin such as an acrylic, urethane, or silicone type ultraviolet ray. It can be formed by a method of adding a cured film having excellent slipperiness and the like 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 a conventional antireflection film such as an interference film.

On the other hand, the sticking prevention treatment is carried out for the purpose of preventing adhesion with the adjacent layer, and the diffusion or anti-glare treatment prevents external light from being reflected on the surface of the polarizing plate and hinders visual recognition of light transmitted through the polarizing plate. It is provided for the purpose of prevention, and for example, a fine concavo-convex structure is provided on the surface of the transparent protective layer by an appropriate method such as a surface roughening method by a sand blast method or an embossing method, or a method of compounding transparent fine particles. Can be formed.

The transparent fine particles may be conductive, for example, silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, etc. having an average particle size of 0.5 to 50 μm. One type or two or more types of inorganic fine particles, organic fine particles made of a crosslinked or uncrosslinked polymer and the like are used. The amount of the transparent fine particles used is generally 2 to 50 parts by weight, preferably 5 to 25 parts by weight, per 100 parts by weight of the transparent resin.

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 anti-glare layer may also serve as a diffusion layer (such as a viewing angle expanding function) for diffusing light transmitted through the polarizing plate and expanding the viewing angle. The antireflection layer, the antisticking layer, the diffusion layer, the antiglare layer, and the like described above may be provided as an optical layer made of a sheet or the like provided with these layers, separately from the transparent protective layer.

The thickness of the transparent protective layer is preferably from 5 to 500 μm, especially from 10 to 300 μm, and particularly preferably from 20 to 100 μm, including the case where the transparent protective layer is made of a laminated body, from the viewpoint of reduction in thickness and weight. The transparent protective layer made of a film is, for example, boric acid or borax,
A polyvinyl alcohol-based adhesive that may contain a water-soluble crosslinking agent such as glutaraldehyde, melamine, and oxalic acid,
The polarizing film can be bonded using a gelatin-based adhesive, an adhesive containing at least a water-soluble crosslinking agent such as formaldehyde, glutaraldehyde, melamine, or oxalic acid, or an appropriate transparent adhesive such as an adhesive layer.

The above-mentioned adhesive layer is formed as a coating and drying film of an aqueous solution, but other additives and a catalyst such as an acid may be blended if necessary when preparing the aqueous solution. In particular, when the transparent protective layer has an optical path control layer, an adhesive treatment with an appropriate transparent pressure-sensitive adhesive such as acrylic or rubber is preferable.

The optical path control layer provided on the upper side (front surface side) of the polarizing plate can be provided as, for example, a transparent protective layer in the above-mentioned polarizing plate, or a light emitting means is formed on the transparent film and the transparent film is bonded. It can also be provided by adhering to a polarizing plate or the like via a layer. When the optical path control layer is provided as a transparent protective layer, it may be formed as a transparent protective layer consisting of a single layer of only the optical path control layer 1A, and therefore the transparent film may be omitted.

The optical path control layer 1A is a transparent substrate 1C having an illuminating device 51 on the side surface, as illustrated by the broken line arrow α in FIG.
Is disposed on the surface side of the substrate in the direction along the plane of the substrate so that the surface on which the light emitting means A is formed is on the outside, and the incident light or the transmitted light from the side direction through the lighting device is converted into an optical path conversion slope. The light is reflected via a to change the optical path to the rear surface side of the transparent substrate, that is, in the viewing direction of the liquid crystal display panel, and is emitted from the transparent substrate 1C as light having polarization characteristics via the polarizing plate 1B, and the emitted light is displayed on the liquid crystal display panel. Illumination light (display light)
The purpose is to be available as.

As shown in FIG. 1, the light emitting means A, which is preferable in terms of directing light from the transparent substrate in the front (vertical) direction with good directivity, has an inclination angle θ1 of 35 to 48 with respect to the plane formed by the transparent substrate 1C. The optical path changing slope a is provided. When the inclination angle of the optical path conversion slope is less than 35 degrees, when a reflection layer is arranged on the back side of the liquid crystal cell in the front light system to reflect the optical path conversion light,
The angle at which the display light based on the reflected light is emitted from the liquid crystal display panel exceeds 30 degrees, which may be disadvantageous for visual recognition.

Further, since the liquid crystal display panel is usually formed so as to provide the best display by visual recognition in the front direction, and the display characteristic is deteriorated as the viewing angle deviates from the vertical and becomes oblique, the emission angle is If it exceeds 30 degrees, 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 is apt to leak from the slope without being totally reflected by the optical path conversion slope, and the light utilization efficiency decreases.

Therefore, when the scattering method of the light emitting means having a roughened surface is used instead of the reflection method of the optical path changing slope in the above description, it is difficult to reflect in the vertical direction, and it is difficult to reflect from the front direction of the liquid crystal display panel. The liquid crystal is emitted in a direction that is greatly inclined, and the liquid crystal display is dark and the contrast is poor.

A liquid crystal display, etc. which is bright and easy to see by efficiently totally reflecting the light through the optical path changing slope and emitting it from the transparent substrate in a direction normal to the plane formed by the light, and illuminating liquid crystal cells efficiently. From the point of achieving the above, the preferable inclination angle θ1 of the optical path conversion slope is 38 to 45 degrees, and especially 40 degrees.
~ 44 degrees.

The light emitting means is formed of a suitable shape having one or more of the above-mentioned optical path changing slopes, for example, a concave portion or a convex portion having a shape such as a triangle to a pentagon based on the cross section with respect to the optical path changing slope. can do. By the way, in the example of FIG. 1, the light emitting means having the triangular section is provided, which has the optical path changing slope a and the vertical surface b having the large inclination angle θ2. It may be an emitting means or the like. It should be noted that the polygonal shape of the cross section is not strictly defined, and deformations such as a change in the angle of the surface and a circle formed by the intersection points of the surfaces are allowed.

As described above, the light emitting means may be formed as a convex portion, but in terms of light utilization efficiency and scratch resistance, it is preferably formed as a concave portion as shown in the figure. preferable. In particular, the light emitting means formed 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 in the optical path control layer (groove), and the convex portion means that the light emitting means projects outside the optical path control layer (mountain).

Further, a plurality of light emitting means are formed for the purpose of downsizing and further thinning of the optical path control layer. In that case, it can be formed as a continuous light emitting means arranged from one side to the other side in a stripe shape, or as a plurality of light emitting means distributed in a discontinuously intermittent state. Further, the light emitting means may be distributed in parallel or irregularly based on the optical path conversion slope in the above continuous or discontinuous state, and with respect to the virtual center. It may be in a distributed state of being arranged in a pit shape (concentric shape).

The arrangement state of the plurality of light emitting means can be appropriately determined according to its form and the like. As described above, the optical-path changing slope a is provided with such an optical-path changing slope because it reflects incident light from the side surface of the illuminating device in the illumination mode toward the rear surface of the transparent substrate to change the optical path. The light emitting means has a total light transmittance of 75 to 9
Distributing so that the haze is 4% to 20% at 2% obtains a polarized surface light source device for efficiently illuminating a liquid crystal cell or the like by optical path conversion of light from the side direction through the lighting device, It is preferable in terms of achieving a bright and excellent contrast liquid crystal display.

The characteristics of total light transmittance and haze can be achieved by controlling the size and distribution density of the light emitting means, and for example, the occupied area based on the projected area of the light emitting means on the light emitting means forming surface can be determined. , 1/100 to 1/8, especially 1/50
It can be achieved by setting the ratio to 1/10, particularly 1/30 to 1/15.

More specifically, if the size of the optical path changing slope is large, it is easy for an observer to recognize the existence of the slope, the display quality is likely to be deteriorated, and the uniformity of illumination for the liquid crystal cell is also deteriorated. When the continuous light emitting means are distributed in parallel in consideration of the ease of use, the pitch is 2 mm or less, preferably 20 μm to 1 mm, particularly 50 to 5 mm.
It is preferable that the projection width of the optical path conversion slope with respect to the plane formed by the transparent substrate is 40 μm or less, especially 3 to 20 μm, and particularly 5 to 15 μm.

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 liquid crystal cells. Further, the moire can be prevented also by adjusting the arrangement pitch. Therefore, the pitch may be changing or may be constant.

On the other hand, when the discontinuous light emitting means is distributed in parallel or irregularly, or when distributed in a pit shape with respect to the virtual center, in addition to the achievement of the above-mentioned characteristics, the optical path conversion slopes are used. In consideration of the reflection efficiency, it is preferable that the length of the optical path changing slope is 5 times or more the depth of the light emitting means, particularly 8 or more, especially 10 or more.

The length of the optical path changing slope is 500 μm or less, especially 200 μm or less, especially 10 to 150 μm, and the depth and width of the light emitting means are 2 to 100 μm, especially 5 to 80 μm,
In particular, it is preferably 10 to 50 μm. The above length is the length in the long side direction of the optical path changing slope, and the depth is based on the light emitting means forming surface. The width is based on the length of the optical path conversion slope in the direction orthogonal to the long side direction and the depth direction.

A surface which forms the light emitting means and which does not satisfy the optical path changing slope a having a predetermined inclination angle, for example, FIG.
The vertical surface b and the like facing the optical path changing slope a in FIG. 2 do not contribute to the emission of the incident light from the side surface of the cell from the transparent substrate, and do not affect display quality or light transmission or light emission as much as possible. It is preferable.

Incidentally, when the inclination angle θ2 of the elevation with respect to the plane formed by the transparent substrate is small, the projected area of the elevation with respect to the plane becomes large, and the polarized surface light source device 1 is arranged on the viewing side as illustrated in FIG. In the outside light mode of the front light system, the surface reflected light from the elevation surface returns to the viewing direction and the display quality is likely to be impaired.

Therefore, the larger the inclination angle θ2 of the vertical surface is, the more advantageous it is. Therefore, the projected area on the plane formed by the transparent substrate can be reduced, and the reduction of the total light transmittance can be suppressed. Further, the apex angle due to the optical path changing slope and the elevation 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, so that the influence on the liquid crystal display can be suppressed. From such a point, the preferable inclination angle θ2 of the elevation or the like is 50 degrees or more, preferably 60 degrees or more, and particularly 75 to 90 degrees.

The inclined surface forming the light emitting means A may be formed in an appropriate surface form such as a straight surface, a refraction surface, or a curved surface. In addition, the cross-sectional shape of the light emitting means may be such that the inclination angle and the like are constant over the entire surface of the optical path control layer. For the purpose of achieving uniform emission of light, the light emitting means may be made larger as the distance from the side surface on the light incident side increases.

Alternatively, the light emitting means may have a constant pitch, or the pitch may be gradually narrowed as the distance from the side surface of the light incident side (arrow) is increased to increase the distribution density of the light emitting means. You can also do it. Further, it is possible to achieve uniform light emission on the transparent substrate 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 and the like in addition to the pitch.

The optical path changing slope in the light emitting means is shown in FIG.
It is preferable to face the direction (arrow) of the incident light from the side surface of the transparent substrate 1C in order to improve the emission efficiency. Therefore, when the linear illumination device is used, it is preferable that the optical path conversion slope faces a direction with respect to one side of the transparent substrate or a fixed direction. Further, when a point illumination device such as a light emitting diode is used, it is preferable that the optical path conversion slope faces the direction of the light emission center of the point illumination device.

Regarding the shape of the intermittent end of the light emitting means,
Although there is no particular limitation, from the viewpoint of suppressing the influence of the incident light on that portion, etc., it is 30 degrees or more, especially 45 degrees or more,
Particularly, it is preferable that the slope is 60 degrees or more.

The surface of the optical path control layer, except for the light emitting means, is a flat surface whose front and back surfaces are as smooth as possible. In particular, the angle change is ± 5 degrees or less, especially ± 2 degrees or less. Further, it is preferable that the surface is a flat surface of 0 degree. Further, it is preferable that the angle change is within 1 degree per 5 mm in length, and especially within 0.5 degree. With such a flat surface, most of the optical path control layer can be a smooth surface with an angle change of 5 degrees or less, and the light transmitted through the transparent substrate can be efficiently transmitted as indicated by the broken line arrow β illustrated in FIG. It is well available and can achieve uniform light emission without disturbing the image.

As described above, the pit-like arrangement of the light emitting means A uses a point-like illuminating device as an illuminating device arranged on the side surface of the transparent substrate, and the radial incident light from the side surface by the point-like illuminating device or its The transmitted light is subjected to an optical path conversion through the optical path conversion slope a so that the transparent substrate emits light as uniformly as possible, and the light having excellent directivity in the normal direction to the liquid crystal cell or the like is efficiently used in the illumination device light. The purpose is to emit light from the transparent substrate.

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 outer side thereof so that the point-shaped illumination device can be arranged easily. The virtual center can be formed at one place or two or more places on the same or different end faces of the transparent substrate.

The optical path control layer can be formed by an appropriate method. By the way, as an example, a transparent film made of a thermoplastic resin, a method of pressing the shape under heating to a mold capable of forming a predetermined light emitting means, transferring the shape, a heat-melted thermoplastic resin, or heat or solvent. The resin fluidized via a method of filling a mold capable of forming a predetermined light emitting means, a liquid resin capable of being polymerized by heat, ultraviolet rays, or radiation such as an electron beam, a monomer, an oligomer, etc. There is a method in which a mold capable of forming a light emitting means is filled or cast and polymerized.

Further, a transparent resin is coated with a liquid resin, a monomer, an oligomer or the like which can be polymerized by radiation such as heat, ultraviolet rays or electron rays, and the coating layer is formed into a mold capable of forming a predetermined light emitting means. A method of polymerizing after pressing and molding, filling the mold capable of forming a predetermined light emitting means with the above liquid resin, etc., placing a transparent film in close contact with the filling layer, and irradiating with ultraviolet rays, radiation, etc. There is also a method of polymerizing with. 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 to which the optical path control layer is adjacent to the transparent film.

Therefore, the above-mentioned method is advantageous for integrally forming the transparent protective layer having the optical path control layer to form the transparent protective layer having the light emitting means in the same body. Particularly, in the latter method using a transparent film, an optical layer such as a transparent protective layer to which an optical path control layer 1A which is a separate body is added is formed. In that case, if the refractive index difference between the optical path control layer and the optical layer such as a transparent protective layer to be added is large, the emission efficiency may be significantly reduced due to interface reflection or the like.

Therefore, from the viewpoint of suppressing the above-mentioned decrease in 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, preferably 0.10 or less, particularly 0. It is preferably within 0.05. In that case, it is preferable from the viewpoint of emission efficiency that the optical path control layer to be added has a higher refractive index than the optical layer such as the transparent protective layer. For forming the optical path control layer, an appropriate transparent material according to the wavelength range of incident light can be used in accordance with the above-mentioned transparent substrate.

In the method using the above-mentioned film, a method of separating the formed optical path control layer from the film after the polymerization treatment using a film treated with a release agent or the like can also be adopted. In that case, the film used need not be transparent. The thickness of the optical path control layer is 300 μm or less, especially 5 to 200 μm, especially 10 to 1
00 μm is common.

At least the light emitting means forming surface of the optical path control layer may be subjected to the above-mentioned antiglare treatment, antireflection treatment, hard coat treatment and the like, if necessary. The transparent substrate subjected to such a treatment can be preferably used especially for a front light system. The anti-glare treatment, anti-reflection treatment and hard coat treatment can be carried out by a method of adhering a film which has been subjected to one or more treatments.

An adhesive layer for adhering the 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 the adhering treated surfaces. The purpose of the adhesion treatment via the adhesive layer is to improve the reflection efficiency of the light emitting means A through the optical path conversion slope a, and to improve the front brightness by effectively using the incident light from the side surface direction.

For the formation of the adhesive layer, an appropriate adhesive such as an adhesive which is cured by irradiation with ultraviolet rays or radiation or heating can be used without any particular limitation. An adhesive layer can be preferably used from the viewpoints of handleability such as simple adhesiveness and stress relaxation property of suppressing generation of internal stress. To form the adhesive layer, for example, an appropriate polymer such as rubber-based or acrylic-based, vinyl alkyl ether-based or silicone-based, polyester-based or polyurethane-based, polyether-based or polyamide-based, styrene-based or fluorine-based is used as a base polymer. An adhesive or the like can be used.

Among them, those having excellent transparency, weather resistance and heat resistance are preferably used, such as an acrylic pressure-sensitive adhesive having a base polymer of a polymer mainly containing an alkyl ester of acrylic acid or methacrylic acid. In addition, from the viewpoints of prevention of foaming phenomenon and peeling phenomenon due to moisture absorption, deterioration of optical characteristics due to thermal expansion difference and the like, prevention of warpage of a transparent substrate, and further, formability of a liquid crystal display device having high quality and excellent durability.
An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferable.

Further, the adhesive layer may be of a light-diffusing type by incorporating therein one kind or two or more kinds of the transparent fine particles exemplified in the above antiglare treatment. Further, the adhesive layer, particularly the adhesive layer, is made of, for example, a natural or synthetic resin,
Especially, suitable additives that may be added to the adhesive layer such as tackifier resin, glass fiber or glass beads, fillers or pigments made of metal powder or other inorganic powder, colorants or antioxidants. May be contained.

The adhesion of the adhesive layer to the optical path control layer is carried out by dissolving or dispersing the adhesive substance or its composition in a solvent consisting of a proper solvent such as toluene or ethyl acetate, or a mixture thereof, for 10 to 40. A pressure-sensitive adhesive liquid of about% by weight is prepared, and a method of directly attaching it to the optical path control layer by an appropriate developing method such as a casting method or a coating method, or by forming an adhesive layer on the separator according to the above It can be carried out by an appropriate method such as a method of transferring it onto the optical path control layer.

The illumination mechanism as the polarization plane light source device 1 is provided on one or more side surfaces of the transparent substrate 1C as shown in the example of FIG.
It can be formed by arranging one or two or more lighting devices 51. When forming the optical path control layer having the pit-shaped light emitting means, the pit-shaped light is emitted from the point that the radial incident light from the point illumination device is efficiently used to achieve bright surface emission. It is preferable to arrange the point illumination device on the side surface of the transparent substrate on the vertical line including the virtual center of the means.

In such arrangement of the point illumination device corresponding to the virtual center, as shown in the example of FIG. 2, depending on whether the virtual center of the light emitting means is on the end face of the optical path control layer or on the outside thereof. Appropriate countermeasures such as a method of projecting the side of the cell substrate 20 formed of the transparent substrate 1C in the polarization plane light source device 1 on which the point illumination device is arranged can be adopted. The same applies when other illumination devices such as a linear illumination device are arranged.

As the illuminating device arranged on the side surface of the transparent substrate, an appropriate illuminating device can be used. For example, in addition to the point illumination device such as the light emitting diode described above, a linear illumination device such as a (cold, heat) cathode tube, an array body in which the point illumination device is arranged in a line or a plane, or a point illumination device And a linear light guide plate are combined to convert the incident light from the point illumination device into the linear illumination device via the linear light guide plate.

Further, it is preferable from the standpoint of emission efficiency that the illuminating device is arranged on the side surface of the transparent substrate which the optical path conversion slope of the optical path control layer faces. By including the pit-like arrangement described above so that the optical path conversion slope faces the illuminating device as perpendicularly as possible, the incident light from the side surface through the illuminating device can be efficiently polarized. It can be converted to emit light with high efficiency.

Therefore, in the case of an optical path control layer having a light emitting means having a plurality of optical path changing slopes, such as one having a two-sided optical path converting slope like a cross section of an isosceles triangle, the transparent substrates are opposed to each other. It is also possible to arrange a number of illumination devices corresponding to a plurality of optical path conversion slopes, such as both of the side surfaces to be illuminated. Further, in the case of the pit-shaped arrangement, the point illumination device can be arranged at one or two or more positions corresponding to the virtual center of the light emitting means in the optical path control layer.

For the lighting device 51 as in the example of FIG.
In order to guide the divergent light to the side surface of the transparent substrate, if necessary, it may be a combination body in which appropriate auxiliary means such as a reflector 52 surrounding the transparent substrate is arranged. As the reflector, a suitable reflection sheet such as a resin sheet or a white sheet or a metal foil provided with a high reflectance metal thin film may be used. The reflector can also be used as a fixing means that doubles as an enclosure of the lighting device by a method of adhering the end portion to the end portion of the transparent substrate.

The polarized surface light source device may have a form in which other optical layers are added, if necessary, in practical use. The optical layer is not particularly limited, and is one layer of an appropriate optical layer that may be used for forming a liquid crystal display device such as a reflective layer, a semi-transmissive reflective layer, a retardation layer or a brightness enhancement film. Alternatively, two or more layers can be added.

By the way, in the example of FIG. 2, a retardation plate 25 is added between the polarizing plate 1B and the transparent substrate 1C, and on the opposite side of the transparent substrate, an alignment film 2 for aligning liquid crystal is formed.
2, transparent electrode 21 for controlling the alignment of liquid crystal, color filter 23 for realizing color display, broken line arrow γ
As described above, the low refractive index layer 24 for efficiently transmitting the side incident light or the transmitted light thereof is added to the opposite end side.

When the above-mentioned reflective layer is arranged outside the optical path control layer and is used as a backlight of a liquid crystal display device or the like, it prevents leakage of light from the optical path control layer or the viewing side of the liquid crystal display device or the like. It is added in the case of forming an external light / illumination type liquid crystal display device or the like that is more visible in the external light mode by reflecting more incident external light. The reflection layer can be formed by a conventional reflection sheet, a method in which a foil or a contact film made of a reflective metal such as aluminum is attached to the surface of the optical path control layer on which the light emitting means is formed.

The reflective layer may be of a diffuse reflection type having a fine concavo-convex structure on the surface. The reflective layer made of an adhesion film can be formed by a vapor deposition method such as a vacuum vapor 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.

On the other hand, the semi-transmissive reflection layer is a reflection layer such as a half mirror that reflects and transmits light. The above-mentioned reflection layer is made thin to make it light transmissive, or light is transmitted to the reflection layer. It can be formed by a method in which a large number of openings for use are dispersed and provided. The semi-transmissive reflective layer is used as a backlight of a liquid crystal display device by being disposed between a polarizing plate and an optical compensation layer, and is visible even in the external light mode described above. It is added when forming a dual-purpose liquid crystal display device or the like. The polarized surface light source device can also be used as a back side cell substrate.

The retardation layer changes linearly polarized light into elliptically polarized light or circularly polarized light, changes elliptically polarized light or circularly polarized light into linearly polarized light, or changes the polarization direction (vibration direction) of linearly polarized light, or compensates for viewing angle. Used for purposes such as. A ¼ wavelength plate is generally used to change linearly polarized light into circularly polarized light or circularly polarized light into linearly polarized light, and a ½ wavelength plate is generally used to change the polarization direction of linearly polarized light.

On the other hand, the elliptically polarizing plate obtained by laminating the retardation layer and the polarizing plate compensates for the coloring (blue or yellow etc.) caused by the birefringence of the liquid crystal layer in the spurts twist nematic (STN) type liquid crystal display device ( (Prevention) and achieve black and white display without coloring. In particular, the one using a retardation layer in which the refractive index in the three-dimensional direction is controlled is preferable because it can compensate the coloring that occurs when the liquid crystal display screen is viewed obliquely. Further, the circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image in a color display type reflective liquid crystal display device, and can also be used for the purpose of antireflection.

The retardation layer for compensating the viewing angle is intended to widen the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is obliquely viewed. The retardation layer may be one layer or two layers at an appropriate position such as between the optical path control layer and the polarizing plate, and / or between the polarizing plate and the transparent substrate, depending on the purpose of use.
Layers or more are arranged. The polarizing surface light source device to which the retardation layer is added can be used for both a front light and a back light, and can also be used as a cell substrate on the viewing side or the back side.

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, polymethylmethacrylate, polypropylene or other polyolefin, polyarylate or polyamide. Examples include a film, an alignment film of a liquid crystal polymer, and a film in which an alignment layer of a liquid crystal polymer is supported by the film. The retardation layer may have an appropriate retardation depending on the purpose of use, or may be one in which two or more types of retardation layers are laminated to control optical properties such as retardation.

The above stretching treatment can be carried out by an appropriate method such as uniaxial or biaxial. In the retardation layer for viewing angle compensation,
Usually, a biaxially stretched film, a birefringent film in which a uniaxially stretched film is further stretched in the thickness direction to control the refractive index in the thickness direction, and a bidirectionally stretched film such as an inclined orientation film are preferably used.

Examples of the above-mentioned inclined orientation film include those obtained by adhering a heat-shrinkable film to a polymer film and subjecting the polymer film to a stretching treatment and / or a shrinking treatment under the action of heat-shrinking film, or a liquid crystal polymer. Examples include those oriented obliquely. Rather than achieving a wide viewing angle for good visibility, a triacetyl cellulose film supporting an optically anisotropic layer consisting of a liquid crystal polymer alignment layer, especially a discotic liquid crystal polymer tilt alignment layer, etc. Can be preferably used.

The brightness enhancement film has a property of selectively reflecting, when natural light enters, linearly polarized light having a predetermined polarization axis or circularly polarized light having a predetermined direction and transmitting other light. It is arranged between the control layers together with a quarter-wave plate as required. By using the polarization plane light source device to which the brightness enhancement film is added as a backlight, it is possible to enhance the utilization efficiency of light through the illumination device and improve the brightness. In that case, it is more preferable from the viewpoint of improving the brightness that the reflection layer for inverting the light reflected by the brightness enhancement film and re-incident on the brightness enhancement film is arranged outside the optical path control layer.

The above-mentioned improvement in brightness by adding the brightness-improving film is based on the reduction of absorption loss due to the supply of polarized light which is difficult to be absorbed by the polarizing plate, and when the reflective layer is further added, the brightness-improving film is reflected. By reflecting and inverting the light and making it incident again, part or all of it is transmitted as light in a predetermined polarization state through the brightness enhancement film, and the amount of transmitted light is increased. The amount of light that can be emitted can be increased to improve the front brightness and the like.

As the brightness enhancement film, for example, a linear multi-layer thin film of a dielectric material or a multi-layer laminate of thin film films having different refractive index anisotropies is transmitted and linearly polarized light of a predetermined polarization axis is transmitted while other light is reflected. Characteristic, cholesteric liquid crystal layer, especially alignment film of cholesteric liquid crystal polymer, such as those supporting the alignment liquid crystal layer on the film substrate, such as one that reflects the left-handed or right-handed circularly polarized light to other As for the light, an appropriate one such as one showing a characteristic of transmitting can be used.

Therefore, in the brightness enhancement film of the type which transmits the linearly polarized light of the predetermined polarization axis, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby suppressing the absorption loss by the polarizing plate. It can be efficiently transmitted. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light like a cholesteric liquid crystal layer, it can be directly incident on a polarizing plate, but from the viewpoint of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation layer. It is preferable that the light is incident on the polarizing plate. Circularly polarized light can be converted into linearly polarized light by using a quarter-wave plate as the retardation layer.

In the above description, the retardation layer that functions as a quarter-wave plate in a wide wavelength range such as a visible light region is a retardation layer that functions as a quarter-wave plate for monochromatic light having a wavelength of 550 nm, for example. Retardation layer showing other retardation characteristics, for example, 1
It can be obtained by a method of superposing a retardation layer functioning as a / 2 wavelength plate. Therefore, the retardation layer disposed between the polarizing plate and the brightness enhancement film may be one layer or two or more layers.

As for the cholesteric liquid crystal layer, the combination of two layers or three layers having different reflection wavelength characteristics is used.
By arranging the layers and layers so as to overlap each other, it is possible to obtain an element that reflects circularly polarized light in a wide wavelength range such as a visible light region, and based on that, it is possible to obtain transmitted circularly polarized light in a wide wavelength range.

In the polarized surface light source device according to the present invention, the incident light or the transmitted light from the side surface of the illuminating device is transmitted through the light emitting means (optical path conversion slope) in a direction having excellent verticality which is advantageous for visual recognition ( The optical path is changed to the normal direction, and the polarized light through the polarizing plate is efficiently emitted using light. Further, it can have good transparency to external light.

From the viewpoint of the uniformity of front luminance and / or the reduction of hue change, a preferable polarized light source device is a back surface side of the transparent substrate when light is incident from the side surface of the transparent substrate through the illumination device. Attenuation rate of polarized light emitted more is 50% or less, especially 10 to 45%, and / or wavelength 44
The difference between the maximum and minimum attenuation factors for polarized light of 0 nm, 550 nm and 610 nm is 10% or less, especially 8% or less, especially 1.
~ 7%.

The above-mentioned attenuation factor is based on the polarized light emitted from the rear surface of the transparent substrate having a length of 40 mm from the incident side surface to the side surface opposite thereto, and is expressed by the formula: {(front luminance at a position 5 mm from the incident side surface. )-(Front luminance at a position 5 mm from the facing side surface)} / (Front luminance at a position 5 mm from the incident side surface)
Calculated as × 100 (the same applies below).

Therefore, the polarized surface light source device according to the present invention is used, for example, in a sidelight type light guide plate or a frontlight or a backlight which also serves as a cell substrate on the viewing side or the backside,
Form various devices such as thin and light reflective and transmissive liquid crystal display devices that are bright and easy to see, and those external light / illumination type liquid crystal display devices or semi-transmissive type external light / illumination type liquid crystal display devices. be able to.

An example of the above-mentioned liquid crystal display device is shown in FIG. The figure shows an example of a liquid crystal display device of both a reflection type and a front light type that also serves as a cell substrate on the viewing side, for both external light and illumination. 20, 30 are cell substrates in a liquid crystal cell, 40
Is a liquid crystal layer, and 31 is a reflective layer. As shown in the drawing, 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.

Further, as shown in the drawing, when forming a liquid crystal display device, the polarized light source device 1 is generally arranged so that the surface having the light emitting means A is on the outside. In that case, the polarization plane light source device may be formed into a liquid crystal display device in a completed state in advance, or the polarization plane light source device may be assembled in the process while forming the liquid crystal display device in an appropriate order. Good.

Further, the lighting device enables visual recognition in the lighting mode by turning on the lighting device. In the case of an external light / illumination type liquid crystal display device, the lighting device is turned on when viewed in the external light mode by external light. Since it is not necessary, it is possible to switch on and off. As the switching method, any method can be adopted, and any conventional method can be adopted. The illuminating device may be of a different color emission type capable of switching emission colors, or may be of a type capable of emitting different color light through different types of illuminating devices.

In general, a liquid crystal display device includes a liquid crystal cell functioning as a liquid crystal shutter, an associated driving device, a front light or a back light, and optional components such as a reflection layer and a retardation plate, which are assembled appropriately. Is formed by. In the present invention, there is no particular limitation except that an illumination mechanism is formed using the above-mentioned polarized surface light source device,
It can be formed according to a conventional front light type or backlight type.

Therefore, the liquid crystal cell used is not particularly limited, and the sealing material 4 is provided between the cell substrates 20 and 30 as shown in the figure.
A suitable reflection type or transmission type, in which a liquid crystal 40 is enclosed via 1 and display light is obtained through light control by the liquid crystal or the like.
A semi-transmissive type can be used.

Incidentally, as a concrete example of the liquid crystal cell, TN
Type liquid crystal cell, STN type liquid crystal cell, IPS type liquid crystal cell and H
AN type liquid crystal cell, OCB type liquid crystal cell or VA type liquid crystal cell,
Examples thereof include twist type and non-twist type liquid crystal cells such as π type liquid crystal cells, guest host type and ferroelectric liquid crystal type liquid crystal cells, and light diffusion type liquid crystal cells such as internal diffusion type. Further, the liquid crystal driving method may be an appropriate method such as an active matrix method or a passive matrix method.

In the reflection type liquid crystal display device, the TN type or the ST type is used.
A liquid crystal cell such as an N type liquid crystal cell having a liquid crystal layer that modulates light through an electric field is preferably used. In that case, the polarized surface 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 to form a front light type liquid crystal display device. Is. The liquid crystal is usually driven through electrodes 21 and 31 provided inside the cell substrate as shown in FIG.

In the reflective liquid crystal display device, the arrangement of the reflective layer is essential. The arrangement position may be provided inside the liquid crystal cell as illustrated in FIG. 2 or may be provided outside the liquid crystal cell. Therefore, in the example of FIG.
1 also serves as a reflective layer. The reflection type liquid crystal display device according to the present invention can be generally used as an external light / illumination type.

The reflective layer may be, 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, a layer provided with a metal thin film by a vapor deposition method or the like. It can be formed as an appropriate reflective layer according to the conventional method such as a reflective sheet in which a working layer or an attached layer is supported by a base material, a metal foil, a transparent conductive film, a dielectric multilayer film, or the like. This point is the same as the above-mentioned reflective layer.

On the other hand, in the transmissive liquid crystal display device, the polarization plane light source device is arranged on the back side of the liquid crystal display panel as a cell substrate or as a side light type light guide plate to form a backlight type liquid crystal display device. Is common. In that case, as described above, by providing a reflection layer outside the optical path control layer, light leaking from the optical path conversion slope or the like is reflected and returned to the direction of the liquid crystal cell, which can be used for cell illumination, and the front brightness is improved. be able to.

In the above case, by forming the reflecting layer as a diffusive reflecting 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 above-mentioned reflective layer, it can be used as a transmissive liquid crystal display device for both external light and illumination.

On the other hand, a semi-transmissive liquid crystal display device can be formed, for example, by forming the reflective layer in the above-mentioned reflective type as a semi-transmissive reflective layer that reflects and transmits light. In that case, the polarization plane light source device can be arranged on the viewing side of the liquid crystal display panel, but it is generally preferable to arrange it on the back side. It is also possible to dispose the polarization plane light source device 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, according to the above-mentioned transmission type, in the case of having a polarization plane light source device on the back side of the liquid crystal display panel, the back side,
By arranging the reflective layer on the outer side, the front luminance can be further improved. This is because it is possible for light that has passed through the semi-transmissive reflective layer or is reflected by it to reach the back surface of the liquid crystal display panel, is reflected and inverted by the reflective layer, and re-enters the liquid crystal cell. .

In the above-mentioned transmissive type or semi-transmissive type, and in the reflective type in which a reflective layer is arranged outside the liquid crystal cell, the cell substrate or electrode is a transparent substrate or a transparent electrode in order to enable liquid crystal display. For example, it is necessary to form it as a material that can transmit light.

On the other hand, when the electrode 31 also serving as a reflection layer is provided inside the liquid crystal cell as in the example of FIG. 2, the cell substrate 20 and the electrode 2 on the viewing side are provided in order to enable liquid crystal display.
1 needs to be formed as a transparent substrate, a transparent electrode, or the like that can transmit light, but the cell substrate 30 on the back side does not need to be transparent like the reflective layer 31 thereof.
It may be formed of an opaque body.

The thickness of the cell substrate forming the liquid crystal cell is not particularly limited and can be appropriately determined according to the strength of liquid crystal filling and the size of the illuminating device to be arranged. Generally, it is 10 in terms of the balance between optical transmission efficiency and thinness and lightness.
μm-5mm, especially 50μm-2mm, especially 100μm-1mm
The thickness of The thickness of the cell substrate may be different between the side where the lighting device is arranged and the side where the lighting device is not arranged,
It may have the same thickness.

When forming a liquid crystal cell, alignment films 22, 32 such as a rubbing film, a color filter 23, a low refractive index layer 24, a retardation film 25, etc. may be provided, if necessary, as shown in FIG. it can. Generally, the alignment film is arranged adjacent to the liquid crystal layer, and the color filter is arranged between the cell substrate and the electrodes. As described above, such an optical layer can be provided as an additional layer to the polarized light source device.

The low-refractive index layer 24 interface-reflects the incident light from the side direction through the illuminating device and efficiently transmits it to the rear in the direction away from the illuminating device, and to the rear optical path conversion slope. In order to improve the uniformity of brightness on the entire cell display surface, light is efficiently incident. The low-refractive-index layer can be formed as a transparent layer made of an appropriate low-refractive-index material made of an inorganic or organic material such as a fluorine compound or a silicone-based polymer.

From the viewpoint of improving the brightness of the cell display, the arrangement position of the low refractive index layer is inside the cell substrate 20 on which the illuminating device 51 is arranged as in the example of FIG. 2, that is, on the side where the optical path control layer of the transparent substrate is provided. The side opposite to is preferred. The refractive index is 0.01 or more than that of the cell substrate (transparent substrate), especially 0.02
A low refractive index layer having a lower value of 0.15, particularly 0.05 to 0.10, is preferable from the viewpoint of improving the brightness of cell display. Therefore, when illuminating devices are arranged on the side surfaces of both the cell substrate on the viewing side and the cell surface on the back side, it is preferable to provide the low refractive index layer on both cell substrates.

When forming a liquid crystal display device, a liquid crystal display panel in which one 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-mentioned anti-glare layer, etc., if necessary. Can also be Such an additional optical layer can be incorporated into a polarization plane light source device through an adhesive layer or the like, if necessary, and applied to the liquid crystal cell as an integrated body.

The light diffusing layer is used for expanding the display range by diffusing the display light, making the front luminance uniform by leveling the light emission, and increasing the amount of light incident on the optical path control layer by diffusing the transmitted light in the transparent substrate. To aim. The light diffusion layer can be provided by an appropriate method using a coating layer having a surface fine uneven structure similar to the above antiglare layer or a diffusion sheet.
Further, the light diffusion layer may be arranged as a layer which also functions as an adhesive layer by blending transparent particles in the adhesive layer. According to this, it is possible to reduce the thickness of the liquid crystal display device. The light-diffusing layer can be arranged in one layer or two or more layers at an appropriate position such as between the polarizing plate on the viewing side and the transparent substrate.

In the reflection type liquid crystal display device illustrated in FIG. 2 described above, the visual recognition by both external light and illumination is performed in the illumination mode by turning on the illumination device 51, as indicated by the broken line arrow α in the figure, and the polarization plane light source device. The light emitted from No. 1 is reflected by the reflection layer 31 via the liquid crystal cell, then passes through the inside of the liquid crystal cell to reach the polarization plane light source device, and is transmitted from a portion other than the light emitting means A in the optical path control layer. The displayed light is visually recognized.

On the other hand, in the external light mode in which the illumination device is turned off, 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 passes through the reflection layer 31 and the liquid crystal cell according to the above. The display light which has passed through the inside to reach the polarized light source device is visually recognized from the portion other than the light emitting means.

On the other hand, in the visual recognition of the transmissive liquid crystal display device for both external light and illumination, in the illumination mode in which the illumination device is turned on, 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 on the viewing side is viewed. Further, in the external light mode when the lighting device is turned off, the external light that has entered from the surface on the viewing side passes through the liquid crystal cell to reach the polarized surface light source device on the back side, and enters from the part other than the light emitting means of the optical path control layer. The light is inverted through the reflection 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 semi-transmissive liquid crystal display device, the visual recognition by both external light and illumination is based on the transmitted light and / or the reflected light through the semi-transmissive reflective layer. According to the liquid crystal display device, the visibility of the display light in the illumination mode or the external light mode is achieved.

In the present invention, the respective components forming the polarized light source device and the liquid crystal display device described above may be wholly or partially integrally laminated and fixed, or may be arranged in an easily separable state. May be. From the viewpoint of preventing reduction in contrast due to suppression of interface reflection, it is preferable that they are in a fixed state. An appropriate transparent adhesive such as a pressure-sensitive adhesive may be used for the fixing treatment, and the transparent adhesive layer may contain transparent particles or the like to form an adhesive layer having a diffusion function.

The above-mentioned formed parts, particularly those on the visible side, are treated with an ultraviolet absorber such as a salicylate compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, a nickel complex salt compound or the like. It can also have ultraviolet absorption ability.

If necessary, the polarization plane light source device may be provided with a transparent adhesive layer for adhering to other members such as a liquid crystal cell. The adhesive layer can be based on the above. The thickness of the adhesive layer can be appropriately determined according to the purpose of use and the adhesive force, etc., and is generally 1 to 500 μm, especially 5 to 2
The thickness is 00 μm, particularly 10 to 100 μm. It is preferable that the adhesive layer exposed on the surface, especially the adhesive layer, is temporarily covered with a release sheet for the purpose of preventing entry of foreign matters until the adhesive layer is put into practical use.

As the release sheet, for example, a suitable thin film such as a plastic film or a rubber sheet, a paper, a cloth, a non-woven fabric, a net, a foamed sheet or a metal foil, or a laminated body thereof may be used. Appropriate ones conventionally used, such as those coated with a suitable release agent such as a fluorine-based, fluorine-based or molybdenum sulfide, may be used.

[0122]

Example 1 A UV-curable acrylic resin was dropped into a mold previously processed into a predetermined shape with a dropper, and then a saponified triacetyl cellulose film having a thickness of 80 μm was left still.
After sticking with a rubber roller and pushing out excess resin and bubbles, irradiate ultraviolet rays with a metal halide lamp to cure it, peel it from the mold and cut it into a predetermined size,
A transparent protective layer having an optical path control layer was obtained.

The transparent protective layer has a length of about 100 μm,
A plurality of light emitting means (FIG. 1) each having a width of about 10 μm and having a triangular cross section are distributed in parallel and irregularly with respect to one side, and the inclination angle of the optical path changing slope is 43 degrees and the inclination angle of the elevation surface. Is 7
It is 8 degrees. The optical path conversion slope faces the parallel side. Further, the area of the flat surface formed of the portion other than the light emitting means in the surface on which the light emitting means is formed is 12 times or more the sum of the optical path changing slope and the vertical surface. Furthermore, the total light transmittance and haze of the transparent protective layer were 89% and 7%, respectively.

Next, the side of the transparent protective layer having no light emitting means and the polyvinyl alcohol-based polarizing film were pressure-bonded with a pressure-bonding roller via an acrylic pressure-sensitive adhesive layer having a refractive index of 1.53 which was formed into a film beforehand. The polarizing plate side was pressure-bonded to the glass substrate with a pressure roller via the same acrylic pressure-sensitive adhesive layer, and was heated and defoamed in an autoclave to be in close contact.

Then, a cold cathode tube was placed on the side of the glass substrate facing the optical path changing slope, surrounded by a silver vapor-deposited polyester film, and the film edges were bonded to the upper and lower surfaces of the glass substrate with double-sided adhesive tape. The cold cathode tube was held and fixed to obtain a polarized light source device.

The polarizing film used above had a transmittance of 45.37%, a polarization degree of 96.81% and a parallel a value of −0.
380, orthogonal a value 17.715, parallel b value -0.61
7, orthogonal b value −56.163, x value in the Yxy color system (hereinafter the same) in the area of 25 mm from the light source is 0.297
0, 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.

Example 2 A polarizing film having a transmittance of 45.43% and a polarization degree of 9
6.85%, parallel a value -0.318, orthogonal a value 16.7
42, parallel b-value -0.008, orthogonal b-value -54.49
3, a polarized surface light source device was obtained in the same manner as in Example 1 except that an x value of 0.2934 and ay value of 0.3174 were used.

Comparative Example 1 As a polarizing film, the transmittance was 44.37% and the polarization degree was 9
9.21%, parallel a value -2.364, orthogonal a value 3.38
2, parallel b value 3.573, orthogonal b value -18.994, x
A polarized light source device was obtained in the same manner as in Example 1 except that the one having a value of 0.3311 and the y value of 0.4034 was used.

Comparative Example 2 A polarizing film having a transmittance of 44.90% and a polarization degree of 9
8.13%, parallel a value-1.323, orthogonal a value 15.6.
97, parallel b value 1.193, orthogonal b value −47.791,
A polarization plane light source device was obtained in the same manner as in Example 1 except that the one having the x value of 0.3099 and the y value of 0.3541 was used.

Comparative Example 3 A polarizing film having a transmittance of 44.08% and a polarization degree of 9
9.90%, parallel a value-1.290, orthogonal a value 0.61
2, a parallel b-value of 2.783, an orthogonal b-value of −4.706, an x-value of 0.3480, and a y-value of 0.3926 were used, and a polarized surface light source device was obtained according to Example 1. It was

Evaluation test The cold cathode tubes of the polarized surface light source devices obtained in the examples and comparative examples were turned on, and the front luminance of the emitted light at each position of 5 mm from the incident side surface and the opposite side surface and the spectral spectrum were measured with a luminance meter ( A spectral radiance meter CS-1000 manufactured by Minolta Co., Ltd., and the attenuation factor of the front luminance over the entire visible light range and the wavelengths of 440 nm and 550
The difference between the maximum value and the minimum value (attenuation rate difference) in the attenuation rate of light of nm and 610 nm was examined. Further, the hue change was visually observed, and when the change was small and good, it was evaluated as ◯, and when the change was large, it was evaluated as x.

The above results are shown in the following table. Attenuation rate (%) at each wavelength (nm) of front luminance Hue attenuation rate (%) 440 550 610 Attenuation rate difference change Example 1 37.13 44.30 39.76 45.45 5.69 ○ Example 2 50.00 57.23 52.28 56.85 4.99 ○ Comparative Example 1 60.67 82.73 63.17 67.24 19.56 × Comparative Example 2 53.96 66.00 53.01 57.85 12.99 × Comparative Example 3 57.71 82.80 67.59 66.44 16.36 ×

From the table, it can be seen that the examples show smaller changes in front luminance attenuation and hue than the comparative examples. By using a polarizing plate exhibiting a predetermined degree of polarization and transmittance, it is possible to reduce the decrease in frontal brightness that occurs as the distance from the light source increases, and to improve the uniformity of brightness, and to achieve a predetermined parallel and orthogonality. It can be seen that by using a polarizing plate exhibiting 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 the color unevenness.

[Brief description of drawings]

FIG. 1 is a side view illustrating an embodiment.

FIG. 2 is an explanatory side view of a liquid crystal display device.

[Explanation of symbols]

1: Polarization plane 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

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideyuki Usui             Nittoden 1-2, Shimohozumi, Ibaraki City, Osaka Prefecture             Within Kou Co., Ltd. (72) Inventor Seiji Umemoto             Nittoden 1-2, Shimohozumi, Ibaraki City, Osaka Prefecture             Within Kou Co., Ltd. F-term (reference) 2H042 BA04 BA12 BA14 BA20                 2H049 BA02 BA26 BB43 BB52 BB63                       BC14 BC22                 2H091 FA08X FA14X FA16X FA16Z                       FA23X FA23Z FA41X FA41Z                       FD06 FD22 LA11 LA18

Claims (4)

[Claims] 1. A transparent substrate having an illuminating device on its side surface has an optical path control layer at least through a polarizing plate, and the polarizing plate has a transmittance of 45% or more and a polarization degree of 96%.
Or more, parallel a value -0.4 to -0.3, orthogonal a value 16
-18, parallel b-value -0.7-0, and orthogonal b-value -57-
-54 is satisfied, and the optical path control layer has a plurality of light emitting means having an optical path converting slope for reflecting the incident light from the side surface of the transparent substrate toward the back surface of the transparent substrate. And a polarized light source device. 2. The tilt angle of the optical-path changing slope 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 opposite to the incident side surface is 4.
When light is incident from the side surface of the transparent substrate of 0 mm through the illuminating device, the formula of the polarized light emitted from the back surface of the transparent substrate is:
{(Front luminance at a position 5 mm from the incident side surface)-(front luminance at a position 5 mm from the opposite side surface)} / (5 from the incident side surface)
The front-end luminance at the position of mm) x 100 has an attenuation factor of 50
% Or less polarized plane light source device. 3. The light emitting device according to claim 1, wherein when light is incident from a side surface of the transparent substrate having a length of 40 mm from an incident side surface to a side surface facing the incident side through an illumination device, the light is emitted from a rear surface of the transparent substrate. The formula for the polarization to be: {(5
front luminance at a position of mm)-(front luminance at a position of 5 mm from the opposing side surface)} / (front luminance at a position of 5 mm from the incident side surface) x 100 at an attenuation factor of 440 nm,
A polarization plane light source device in which the difference between the maximum value and the minimum value of the attenuation rate in polarized light of 550 nm and 610 nm is 10% or less. 4. A liquid crystal display device comprising the polarized surface light source device according to claim 1 on one or both of a viewing side and a back side of a liquid crystal display panel.