JP2001350016A - Polarizing plate for conversion of optical path - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical member which efficiently converts the optical path of the incident light through the side face to the observation direction and with which a thin, lightweight and bright transmission type or reflection and transmission type liquid crystal display device, having easily visible display, can be formed. SOLUTION: The optical path converting polarizing plate (1) comprises a polarizing plate (P) having transparent protective layers (12, 14) on at least one face of a polarizer (13), an adhesive layer (15) applied on one face of the plate (P), and repeated structure (A) of recesses and projections on the other face of the polarizing plate, with the structure (A) having optical path converting slopes (A1) almost in one direction, with 35 to 48 deg. inclination angle with respect to the face of the polarizing plate. The refractive indices of the adhesive layer and the material of the optical path converting slopes are equal to or higher than the refractive index of the polarizer or the transparent protective layers. By adhering the optical path converting polarizing plate to a liquid crystal cell, the optical path of the incident light through the side face of the cell can be converted efficiently to the viewing direction of the cell, and the liquid crystal display is superior in brightness and its uniformity in the transmission mode. Or liquid crystal display in a reflection mode by external light is also possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical path-changing polarized light capable of efficiently converting a side incident light into an optical path in a viewing direction to form a thin, light-weight, bright and easy-to-view display transmissive or reflective / transmissive liquid crystal display device. Regarding the board.

[0002]

BACKGROUND OF THE INVENTION In order to suppress the weight increase due to the enlargement of TV and personal computer screens and to reduce the size and weight of portable personal computers and mobile phones, further reduction in the thickness and weight of transmissive liquid crystal display devices is required. It is difficult to reduce the thickness and weight of a conventional backlight provided with a direct type or a sidelight type light guide plate. By the way, in the direct type backlight, the light diffusion plate and the reflection plate are arranged together with the illuminating device directly below the liquid crystal display panel, so that the thickness is usually 4 mm or more. Even for the sidelight type light guide plate, the plate thickness is 1 mm or more due to the need for light transmission. When a light diffusing plate, a reflecting plate, a prism sheet, or the like is disposed thereon, the thickness usually becomes 3 mm or more.

Also, a transflective liquid crystal display device in which a transflective reflector is disposed between the transmissive liquid crystal display panel and the backlight so that the transflective plate can be viewed even in a reflection mode by external light is known. Had been. The arrangement of the semi-transmissive reflector is intended to enable visibility in the reflection mode, without which the visibility in the reflection mode by external light is dark, and it is difficult to substantially function as a reflective liquid crystal display device. However, in addition to adding bulkiness and weight by adding a transflective reflector, the transflective reflector disperses the transmitted light and reflected light, so that the visibility in the transmission mode is darkened, and the visibility in the reflection mode is also reduced. There is a problem that it is difficult to make the brightness darker than that of a light reflection layer having a high reflectivity only for reflection.

[0004]

SUMMARY OF THE INVENTION The present invention provides an optical member capable of efficiently changing the optical path of side-incident light in the viewing direction to form a thin, lightweight, bright and easy-to-view transmissive or reflective / transmissive liquid crystal display device. The task is to develop

[0005]

According to the present invention, a polarizing plate having a transparent protective layer on at least one side of a polarizer has an adhesive layer on one surface, and the other side of the polarizing plate has an inclination angle of 35 to 35 with respect to the polarizing plate surface. It has a repeating structure of irregularities having an optical path changing slope that faces a substantially constant direction at 48 degrees, and the refractive index of the adhesive layer and the optical path changing slope forming material is the refractive index of the polarizer or the transparent protective layer. It is intended to provide an optical path-changing polarizing plate characterized by being equal to or more than.

[0006]

According to the optical path-changing polarizing plate of the present invention, by arranging it along the viewing surface of the liquid crystal cell having the illuminating device on the side surface, the incident light from the side surface or the transmitted light thereof is polarized. A transmissive liquid crystal display device that can efficiently convert the optical path in the viewing direction of the liquid crystal cell through the optical path conversion slope provided on the plate and can be used for liquid crystal display in transmission mode, and is excellent in thinness and lightness, is bright, and has excellent display quality. Can be formed.
In addition, by providing a flat surface portion between the optical path changing slopes of the polarizing plate, external light can be efficiently incident, and the incident light can be reflected through the light reflection layer and used for a liquid crystal display in a reflection mode. A reflective mode mechanism can be formed in addition to a transmissive mode mechanism, so that a reflective / transmissive liquid crystal display device which is excellent in thinness, lightness, brightness, and display quality can be formed.

[0007] The above-mentioned effect is mainly due to the use of an optical path control type polarizing plate by oblique reflection. That is, by reflecting the incident light from the side surface or the transmitted light from the side surface through the optical path conversion slope, the optical path can be changed with good directivity, and good visibility in the transmission mode is achieved, and a flat surface can be easily formed between the optical path conversion slopes. It can be arranged and allows external light to pass through the flat surface to ensure sufficient external light incidence, and good visibility in the reflection mode is achieved.
Even if the scattering type polarizing plate 6 in which the scattering layer such as the anti-glare layer 61 is provided on the polarizing plate P as shown in FIG. 9 is bonded to the liquid crystal cell 2 via the adhesive layer 62, the light for illuminating the liquid crystal cell described above is obtained. Is not substantially obtained, and it is difficult to achieve the above-mentioned effect by a scattering reflection method through a rough surface such as a scattering sheet. Incidentally, in Japanese Patent Application Laid-Open No. 5-158033, a reflection type liquid crystal display is used in which illumination light is incident from the side of a liquid crystal cell, totally reflected by a cell substrate on the viewing side, and the reflected light is scattered by a rough-surface type reflection plate to be used for display. Teaching device.

However, in the above case, the light available for display is light that is emitted from the panel out of the condition of total reflection due to scattering. Generally, the scattered light has a normal distribution having a peak in the regular reflection direction. Proceedings of the 20th LCD Symposium 3
G510, Tohoku University; Uchida, etc.), the display light is light inclined at a greater angle than the front (vertical) direction and is difficult to use effectively for display, and becomes dark in the front direction. If the scattering by the rough reflector is increased, the amount of light in the front direction in the reflection mode is reduced, which is disadvantageous for display (SID 96).
DIGEST 2149-152). Therefore, in the rough surface scattering / reflection method, since the scattering intensity required for both the transmission mode and the reflection mode is in a trade-off relationship, it is difficult to make the scattering intensity advantageous for both modes.

On the other hand, the polarizing plate of the present invention, which controls the optical path by oblique reflection, mainly uses the light in the specular reflection direction showing a peak, and controls the optical path of the reflected light. In particular, the directivity in the front direction can be easily provided, and a bright transmission mode can be achieved. In addition, even in the reflection mode, it is possible to secure efficient incidence and reflection / transmission of external light by using a flat part other than the optical path conversion slope of the polarizing plate, and to easily balance to a state advantageous for both the reflection and transmission modes. Can be. Further, in the case of the above-mentioned transmission mode, the adhesive layer for bonding the optical path conversion polarizing plate to the liquid crystal cell or the like and the optical path conversion slope forming material have a refractive index equal to or higher than that of the polarizer or its transparent protective layer. The incident light from the side surface or the transmission light thereof can be prevented from being totally reflected by the adhesive layer or the polarizing plate, and the incident light on the side surface can be efficiently made incident on the optical path conversion slope, particularly with respect to the liquid crystal cell surface. It is possible to efficiently suppress the total reflection of the incident light on the side surface which should be transmitted to a position far from the incident side surface due to a small angle (close to parallel), thereby improving the brightness and uniformity of the entire screen. it can.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An optical path-changing polarizing plate according to the present invention has an adhesive layer on one surface of a polarizing plate having a transparent protective layer on at least one side of a polarizer, and has a polarizing plate on the other side. It has a repeating structure of irregularities having an optical path changing slope having an inclination angle of 35 to 48 degrees and facing a substantially constant direction, and the refractive index of the adhesive layer and the optical path changing slope forming material is the polarizer or the transparent material. It consists of what is more than equivalent to the refractive index of a protective layer. An example is shown in FIG. 1 is an optical path conversion polarizing plate, and 11 and 11a are optical path conversion slopes A1.
, That is, a repetitive structure layer of the optical path changing means A. Further, 12 and 14 are transparent protective layers, 13 is a polarizer, they form a polarizing plate P, 15 is a surface adhesive layer, and 11b is a second adhesive layer. Further, reference numeral 16 denotes a release sheet.

As the polarizing plate, an appropriate polarizing plate having a transparent protective layer on at least one side of the polarizer can be used, and there is no particular limitation. Generally, as shown in the figure, a transparent protective layer 12, 1 is provided on one or both sides of a polarizer 13 made of a polarizing film or the like.
For example, a polarizing plate P having the transparent protective layer 4 adhered thereto, a transparent protective layer as a support, and a polarizing layer (polarizer) made of liquid crystal or the like provided on the support may be used. Rather than obtaining a display with a good contrast ratio due to the incidence of highly linearly polarized light, for example, a highly hydrophilic film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film is used. Those having a high degree of polarization, such as those using an absorption type polarizing film obtained by adsorbing a dichroic substance such as iodine or a dichroic dye on a molecular film and stretching the same, can be preferably used.

For the formation of the above-mentioned transparent protective layer, those having excellent transparency, mechanical strength, heat stability and moisture shielding property are preferably used. Examples include acetate resins, polyester resins, polyethersulfone resins and polycarbonate resins, polyamide resins and polyimide resins, polyolefin resins and acrylic resins, polyether resins and polyvinyl chloride, and styrene resins. And a thermosetting resin or an ultraviolet curing resin such as an acrylic resin, a urethane resin, an acrylic urethane resin, an epoxy resin, or a silicone resin. The transparent protective layer can be provided by a bonding method or a coating method of a polymer liquid or the like in the form of a film. When the polarizing layer is formed by a coating method or the like, a transparent protective layer formed of a film or the like is used as a support. Is used.

As illustrated in FIG. 7, the optical path-changing polarizing plate 1 is
The liquid crystal cell 2 having the illuminating device 5 on the side face is arranged in a direction along the viewing surface, and the incident light from the illuminating device or the transmitted light from the side direction is reflected via the optical path changing slope A1 as shown by the arrow, and the polarizing plate P The purpose of which is to convert the optical path to the surface side having no inclined surface, that is, in the viewing direction of the liquid crystal cell 2 and emit the light from the polarizing plate, and use the emitted light as illumination light (display light) for the liquid crystal cell or the like. It is.

In order to achieve the above object, an optical path changing polarizing plate 1 is provided with a slope A for reflecting an incident light from the side or a transmission light thereof in a predetermined direction to convert the optical path as shown in FIG.
1 on one side of the polarizing plate P. In that case,
According to the present invention, as shown in FIG. 1, the polarizing plate surface A is used for obtaining illumination light having excellent directivity in the front direction through optical path conversion.
4 has an inclination angle θ1 of 35 to 48 degrees, and has an unevenness having an optical path changing slope A1 oriented in a substantially constant direction, that is, a repeating structure of the optical path changing means A.

FIGS. 1A to 1G show examples of the optical path changing means A having the above-described optical path changing slope A1. In (a) to (c) and (g), the optical path changing means A has a substantially triangular cross section, (d) and (e) have a substantially quadrangular cross section, and (f) has a substantially pentagonal cross section. Further, (a) and (g) show an optical path conversion means A having two optical path conversion slopes A1 by isosceles triangles, and (b) an optical path conversion means A having an optical path conversion slope A1 and a steep slope A2 having a larger inclination angle than the slope A1. Consisting of On the other hand, in (c), the optical path changing means A having the optical path changing slope A1 and the gentle slope A3 having a small inclination angle as a unit is formed on the entire surface of one side of the polarizing plate as a repetitive structure of an adjacent continuous state. (A) ~
(C), (e) and (g) have optical path conversion means A composed of concave portions (grooves), and (d) and (f) have optical path conversion means A composed of convex parts (projections). Consists of

Therefore, as in the above-described example, the optical path changing means can be formed on a convex portion or a concave portion having an equilateral surface or a slope having the same inclination angle, and the optical path conversion slope is different from a steep slope or a gentle slope or an inclination angle. It can also be formed in a convex portion or a concave portion formed of a slope, and the form of the slope can be appropriately determined by the number and position of the side direction in which light is incident. Rather than maintaining the slope function by improving the scratch resistance, it is advantageous to form the optical path conversion means having a concave portion (groove structure) rather than a convex portion because the slope and the like are less likely to be damaged.

An optical path-changing polarizing plate that is more preferable, for example, in achieving the above-described characteristics such as directivity in the front direction, is such that the substantially constant direction in which the optical path-changing slope A1 faces is a direction facing the side direction on which light is incident. It is. Therefore, for example, when light is incident from two or more side surfaces of the optical path conversion polarizing plate 1 as shown in FIG. 8, an optical path conversion polarizing plate having an optical path conversion slope A1 corresponding to the number and position is preferably used. Used.

When the two opposing sides of the optical path changing polarizing plate are set to the side direction on which light is incident as shown in FIG. 8, an optical path conversion having an approximately isosceles triangle in cross section as shown in FIGS. 1 (a) and 1 (g). FIG. 1 shows two optical path changing slopes A1 by means A;
(D) As shown in (e) and (f), two optical path conversion slopes A1 by the optical path conversion means A having a substantially trapezoidal or quadrangular or substantially pentagonal cross section are formed in such a state that the ridge lines thereof are in the direction along the side direction. The optical path-changing polarizing plate 1 having two or more optical path-changing slopes having a substantially constant direction and including a surface facing in the opposite direction with respect to one surface is preferably used.

When two vertically and horizontally adjacent side surfaces of the optical path-changing polarizing plate are set to the side surfaces on which light is incident, an optical path having an optical path changing slope A1 with ridges corresponding to the side surfaces in both the vertical and horizontal directions. Conversion polarizing plates are preferably used. Further, when three or more side surfaces including the opposing and vertical and horizontal sides are the side directions on which light is incident, an optical path-changing polarizing plate having an optical path-changing slope A1 composed of the above combination is preferably used.

As described above, the optical path changing slope A1 plays a role of reflecting the light incident on the surface A1 out of the incident light from the side direction or the transmitted light, and changing the optical path. In this case, as shown in FIG. 1 (a), by setting the inclination angle θ1 of the optical path changing slope A1 with respect to the polarizing plate surface to 35 to 48 degrees, incident light from the side direction or its transmitted light is perpendicular to the polarizing plate surface. By efficiently changing the optical path, it is possible to efficiently obtain illumination light having excellent directivity toward the front.

If the inclination angle θ1 is less than 35 degrees, the optical path of the reflected light is greatly deviated in the direction of 30 degrees or more from the front direction, and it is difficult to effectively use for display, and the brightness in the front direction is poor.
When the angle exceeds 48 degrees, the condition for totally reflecting the incident light or the transmitted light from the side direction is deviated, and the leakage light from the optical path conversion slope increases, resulting in poor light utilization efficiency of the incident light from the side direction. A preferable inclination angle θ1 of the optical path conversion slope A1 from the viewpoint of optical path conversion having excellent directivity to the front and suppression of leak light.
Is 38 to 45 degrees, especially 40 to 44 degrees, considering the total reflection condition based on refraction of transmission light according to Snell's law.

The optical path changing means A having the above-described optical path changing slope A1 is formed as a repeating structure of irregularities for the purpose of reducing the thickness of the optical path changing polarizing plate. In this case, rather than reflecting the incident light from the side direction backward and transmitting it efficiently to the opposing side surface to emit light as uniformly as possible on the entire surface of the polarizing plate, the inclination with respect to the polarizing plate surface as illustrated in FIG. Angle less than 5 degrees, especially 4
It is preferable to adopt a structure including a gentle slope A3 of less than or equal to 3 degrees, particularly a flat surface composed of a polarizing plate surface A4 of which the inclination angle is about 0 degrees. Therefore, in the optical path changing means A including the steep slope A2 illustrated in FIGS. 1B and 1E, the angle of the steep slope is 35 degrees or more, particularly 50 degrees or more, and particularly 60 degrees or more, and the width of the polarizing plate surface A4 is set. It is preferable that the structure can be widened.

The flat surface composed of the gentle slope A3 and the polarizing plate surface A4 serves to prevent external light when the light reflecting layer 4 is disposed on the back side of the optical path changing polarizing plate 1 as shown in FIGS. It can function as an incident portion and a transmitting portion of the incident light reflected by the light reflection layer 4 through the light reflection layer 4, thereby enabling a display in a reflection mode by external light with the lighting device turned off, and a reflection / transmission type. A liquid crystal display device can be formed.

In the above case, in particular, the slope A as shown in FIG.
1. When the optical path converting means A is formed by a repetitive structure adjacent to the optical path converting means A3, the angle difference of the inclination angle of the gentle slope A3 with respect to the polarizing plate surface should be within 5 degrees, particularly within 4 degrees, especially 3 degrees. It is preferable that the difference between the inclination angles of the nearest gentle slopes is within 1 degree, more preferably within 0.3 degree, especially within 0.1 degree. The purpose of this is to prevent the reflected light path through the gentle slope A3 from largely changing, particularly not to change greatly between the nearest gentle slopes. The case of the optical path changing means A using the slopes A1 and A3 as shown in FIG.

Also, rather than obtaining a bright display in the external light mode, the gentle slope A having an inclination angle of 5 degrees or less with respect to the polarizing plate surface is preferred.
The occupied area or width of the flat surface composed of the polarizing plate surface 3 and the polarizing plate surface A4 is at least 10 times as large as that of the inclined surfaces A1 and A2 having the inclination angle of 35 degrees or more based on one surface of the polarizing plate on which the optical path conversion means A is formed, especially. It is preferably at least 12 times, particularly preferably at least 15 times. This aims at improving the incident efficiency of external light and the transmission efficiency of reflected light through the light reflecting layer.

As shown in FIGS. 2 to 4, the optical path changing means A is provided so that its ridge line is parallel or inclined along the side of the light incident side. May be formed continuously from one end to the other end of the optical path conversion polarizing plate 1, or may be formed discontinuously and discontinuously as in the example of FIG. When formed discontinuously, the length in the direction along the side surface direction of the unevenness formed by the groove or the protrusion may be set to 5 times or more the depth or the height in terms of the incident efficiency of the transmission light and the optical path conversion efficiency. Preferably
Further, the length is set to 500 from the viewpoint of uniform light emission on a polarizing plate.
μm or less, especially 10 to 480 μm, especially 50 to 450 μm
It is preferable that

The slope forming the optical path conversion means A may be formed in an appropriate surface form such as a straight surface, a refraction surface, a curved surface, etc., and the cross-sectional shape of the optical path conversion means A and the optical path conversion slope A1 through the same. Is not particularly limited. Since the optical path conversion slope A1 is a factor in determining the luminance in the transmission (lighting) mode, the light emission uniformity on the polarizing plate, and the uniformity of the light emission in the external light mode for the reflection / transmission type are appropriately determined. And the distribution path density can be used to control the optical path conversion light quantity.

Therefore, the inclination angles of the slopes A1, 2, and 3 may be constant over the entire surface of the sheet, or the slopes A1, 2 and 3 may be fixed on the polarizing plate to cope with absorption loss and attenuation of transmitted light due to optical path conversion. For the purpose of achieving uniform light emission, the optical path changing means A may be made larger as the distance from the side surface on which light enters as shown in FIG. The optical path conversion means A may have a constant pitch as shown in the examples of FIGS. 2 and 3. Alternatively, as shown in FIGS. 4 and 6, the pitch may be gradually reduced as the distance from the light incident side increases. The distribution density of the conversion means A may be increased.

Further, by arranging the optical path changing means A at a random pitch, the light emission on the polarizing plate can be made uniform. The random pitch is more advantageous than preventing moiré due to interference with pixels. Therefore, the optical path conversion means A may be composed of a combination of irregularities having different shapes and the like in addition to the pitch. In particular, when the optical path conversion means A has irregularities formed of discontinuous grooves or projections, the size and shape of the irregularities, the distribution density and the direction of the ridgeline, and the like are irregular, or the irregular or regular or irregular Uniform unevenness can be randomly arranged to make light emission uniform on the panel display surface. Therefore, uniform light emission on the panel display surface as in the above-described example can be achieved by applying an appropriate method to the optical path conversion means A. 2 to 6, the direction of the arrow is the transmission direction of the incident light from the incident side surface.

In the case of a reflection / transmission type liquid crystal display device, if the optical path conversion slope A1 overlaps the pixels of the liquid crystal cell, the display light may be insufficiently transmitted, resulting in an unnatural display. It is preferable to make the overlap area as small as possible to secure sufficient light transmittance through the flat surfaces A3 and A4. From this point, considering that the pixel pitch of the liquid crystal cell is generally 100 to 300 μm, the optical path conversion slope A1 is 40 μm or less, particularly 3 to 20 μm, based on the projection width to the polarizing plate surface.
In particular, it is preferable that the thickness be 5 to 15 μm. Such a projection width is more preferable than the point where the coherent length of the fluorescent tube is generally set to about 20 μm, and the like, from the viewpoint of preventing the deterioration of display quality due to diffraction.

On the other hand, it is preferable that the distance between the optical path changing slopes A1 is larger than the above-mentioned point. On the other hand, the optical path changing slope A1 substantially forms the illumination light by the light path changing of the incident light from the side as described above. Since it is a functional part, if the interval is too wide, the lighting at the time of lighting may be sparse and unnatural display may occur. In view of them, the repetition pitch of the optical path conversion slope A1 is 5 mm or less, especially It is preferably from 20 μm to 3 mm, particularly preferably from 50 μm to 2 mm.

In the case of an optical path changing means having a repeating structure of irregularities, moire may occur due to interference with pixels of a liquid crystal cell. Moire can be prevented by adjusting the pitch of the repeating structure, but as described above, the pitch of the repeating structure has a preferable range. Therefore, a solution for a case where moire occurs in the pitch range becomes a problem. In the present invention, as shown in the example of FIG. 3, it is preferable to form a ridge line of the unevenness so as to be inclined with respect to the lateral direction so that the repeating structure of the unevenness can be arranged in an intersecting state with respect to the pixel to prevent moire.

In the above case, the inclination angle θ2 with respect to the side surface direction
Is too large, the reflection via the optical path conversion slope A1 is deflected, and a large deviation occurs in the direction of the optical path conversion, which tends to deteriorate the display quality. Therefore, the inclination angle θ2 of the ridge line with respect to the side surface direction is ± 30. It is preferable that the temperature be within ± 25 degrees, particularly within ± 25 degrees, and within ± 20 degrees. The sign of ± means the inclination direction of the ridgeline with respect to the side direction. In the case where the resolution of the liquid crystal cell is low and moiré does not occur, or when moiré can be neglected, it is preferable that such a ridge line is parallel to the side surface direction.

The optical path changing means may be, for example, a method of transferring a shape by pressing a thermoplastic resin into a mold capable of forming a predetermined shape while heating, a method of fluidizing a heat-melted thermoplastic resin or heat or a solvent. A method of filling the resin into a mold that can be molded into a predetermined shape, filling or casting a liquid resin that can be polymerized by radiation such as heat, ultraviolet light, or electronicity into a mold capable of forming a predetermined shape. It can be formed by an appropriate method such as a method of performing a polymerization treatment by using the method.

A preferred method of forming the optical path changing means is, for example, to apply a curable resin which can be polymerized by ultraviolet rays or radiation or the like to one surface of a transparent film, and apply the coating layer to the surface of the mold having a predetermined uneven structure. After being cured by irradiation with ultraviolet light or radiation or the like in close contact, a transparent film is provided with an optical path conversion slope on one side of the transparent film through a mold having a predetermined uneven structure, such as a method of peeling and collecting the film from the mold. This is a method of adding a repeating structure of irregularities.

Accordingly, the optical path changing polarizing plate is, for example, as shown in FIG.
As shown in (a) to (f), the transparent protective layer 12 of the polarizing plate P is provided with a layer 11 made of the same or different resin having the optical path changing means A, or the transparent protective layer 12 of the polarizing plate P is provided. Of the polarizing plate P, especially its transparent protective layer 12
1g, or a transparent film 11a having an optical path changing means A formed on one side as shown in FIG. 1 (g), and a second adhesive layer 11b attached to the polarizing plate P via the side having no optical path changing means. Polarizing plate P
May be formed to have an appropriate form of the structure including the optical path conversion means A on one side.

In the case of the above-mentioned method of adding to the transparent protective layer or the method of bonding through a transparent film, the optical path changing means layer 11 or the transparent film is transparent according to the wavelength range of light incident through an illuminating device or the like. It can be formed of an appropriate material that exhibits properties and satisfies a predetermined refractive index. By the way, in the visible light range, for example, acrylic resins and polycarbonate resins, transparent resins represented by cellulose resins and norbornene resins, heat and ultraviolet rays, the above-mentioned curable resins that can be polymerized by radiation such as electron beams, etc. And the like for the transparent protective layer. Especially, do not show birefringence,
It is preferable that a layer having a small phase difference be formed using a material having a small birefringence.

In the case of performing the bonding treatment, an internal stress may be generated in the optical path conversion means layer in the processing, and a material having a small photoelastic coefficient is used in order to prevent the occurrence of a phase difference due to the internal stress. Is preferred. Furthermore, if the optical path conversion means layer to be added to the polarizing plate has a large refractive index difference from the polarizer or the transparent protective layer of the polarizing plate, the emission efficiency may be greatly reduced due to interface reflection or the like. In order to improve the optical path conversion slope, a material having a refractive index equal to or higher than the refractive index of the polarizer of the polarizing plate and / or the transparent protective layer is used. In particular, a material whose refractive index is larger than 0.02, especially larger than 0.05 is preferably used. The thickness of the optical path conversion means layer can be determined as appropriate, but is generally 300 μm or less from the viewpoint of thinning and the like.
Especially, it is 5 to 200 μm, especially 10 to 100 μm.

The optical path-changing polarizing plate is provided with an adhesive layer 15 for bonding the optical path-changing polarizing plate to a supporting member such as a liquid crystal cell, on the surface of the polarizing plate P having no repeating structure 11 as shown in FIG. It is provided on the surface. Such an adhesive layer is formed as a layer having a refractive index equal to or higher than the refractive index of the polarizer of the polarizing plate and / or the transparent protective layer. This makes it difficult for total reflection to occur at the interface between the adhesive layer and the polarizer or the like, and makes the incident light from the side direction or the transmitted light into the optical path changing means A.
Can be efficiently incident on the optical path conversion slope A1 of
The luminance can be improved by the effective use of the side incident light and the like.

From the viewpoint of the incidence efficiency of the side incident light or the transmitted light on the optical path changing slope, the refractive index of the polarizer of the polarizing plate and / or the transparent protective layer is 0.01 or more, especially 0.0
It is preferable that the adhesive layer has a refractive index of 2 or more, particularly 0.05 or more. For the same reason, the refractive index of the polarizer of the polarizing plate and / or the refractive index of the transparent protective layer of the second adhesive layer for bonding the transparent film on which the optical path changing means is formed to the polarizing plate is also preferably equal to or more than 0.02. As described above, it is particularly preferable to have a refractive index larger than 0.05.

The surface or the second adhesive layer can be formed with an appropriate adhesive exhibiting the above-mentioned refractive index characteristics. An adhesive layer can be preferably used from the viewpoint of handleability such as simplicity of an adhesive treatment. For forming the adhesive layer, for example, rubber-based or acrylic-based, vinyl alkyl ether-based or silicone-based,
An adhesive having a base polymer of an appropriate polymer such as polyester, polyurethane, polyether, polyamide, or styrene can be used. Among them, those excellent in transparency, weather resistance, heat resistance and the like, such as an acrylic pressure-sensitive adhesive having a polymer mainly composed of an alkyl ester of acrylic acid or methacrylic acid as a base polymer, are preferably used.

The adhesive layer includes, for example, silica, alumina, titania, zirconia, tin oxide, indium oxide,
Light diffusion type by containing one or more suitable transparent particles such as inorganic particles that may be conductive such as cadmium oxide or antimony oxide, and organic particles such as a crosslinked or uncrosslinked polymer. You can also. When the adhesive layer as the adhesive layer is exposed on the surface, a release sheet as shown in FIG. 1 is applied to the exposed surface for the purpose of preventing contamination due to adhesion of foreign substances or the like until the adhesive layer is put to practical use. It is preferable that the cover 16 is temporarily attached. In addition, the above-mentioned surface adhesive layer and an adherend such as a liquid crystal cell to which the surface adhesive layer is adhered, in particular, suppresses total reflection at an interface with a liquid crystal cell substrate so that side incident light or its transmission light is efficiently incident on an optical path changing polarizing plate. It is preferable that the difference in the refractive index between the adhesive layer and the liquid crystal cell substrate or the like is as small as possible, preferably within 0.15, particularly preferably within 0.10.

The optical path-changing polarizing plate may be one in which a substrate such as a sheet for protecting the optical path-changing slope is adhered to the surface on which the optical path-changing means is formed. Further, the optical path conversion polarizing plate may be one in which the light reflection layer 4 is disposed in close contact with the surface of the polarizing plate P on which the optical path conversion means is formed, as illustrated in FIGS. Such a light reflecting layer is intended to improve the light use efficiency by inverting and reentering the leakage light from the surface of the polarizing plate on which the optical path conversion slope is formed, and to form a reflection-transmission type liquid crystal display device. I do.

The light reflecting layer can be formed of an appropriate material such as a conventional white sheet. Above all, for example, a coating layer containing a powder of a high reflectivity metal such as aluminum, silver, gold, copper, chromium, or an alloy thereof in a binder resin, the above-mentioned metal, etc. and a dielectric multilayer film are formed by a vacuum deposition method. Layer formed by an appropriate thin film forming method such as sputtering or sputtering, a reflection sheet in which the coating layer or the added layer is supported by a base material such as a polarizing plate, and high-reflectance light reflection formed of a metal foil or the like. Layers are preferable, and particularly preferable when a liquid crystal display device of a reflection / transmission type is formed.

The light reflecting layer to be formed may have a light diffusing function. By diffusing the reflected light on the diffuse reflection surface, the directivity in the front direction can be improved, and in the case of roughening, the visibility can be improved by preventing the occurrence of Newton rings due to close contact. Can be.

The light-diffusing type light-reflecting layer is formed on a film substrate or the like having a fine uneven structure on the surface by an appropriate method such as a surface roughening method by sandblasting or matting or a particle addition method. It can be performed by a method of providing a light reflection layer reflecting the fine uneven structure. The formation of the light reflecting layer of the fine uneven structure reflecting the fine uneven structure of the surface is performed by, for example, using a film-based metal by an appropriate method such as a vacuum evaporation method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of attaching to the surface of a material or the like.

The optical path-changing polarizing plate according to the present invention converts the incident light or the transmitted light from the side direction by the illumination device or the like through the optical path-changing slope to the direction having excellent perpendicularity, which is advantageous for visual recognition. It emits well and shows good transparency to external light, as shown in FIGS.
The reflection type which is bright and easy to see and is excellent in low power consumption by being arranged on the viewing back side (back) or the viewing side (front) of the liquid crystal cell 2 in which the illuminating devices 5 and 51 are arranged on the side surfaces described above.
Various devices such as a transmissive liquid crystal display device can be formed.

By the way, according to the above-mentioned liquid crystal display device,
Most of the incident light from the side direction via the illuminating devices 5 and 51 is transmitted rearward via the upper and lower cell substrates 21 and 28 via reflection based on the law of refraction based on the thickness ratio of each layer in the liquid crystal cell 2. The light incident on the light path changing slope A1 of the light path changing polarizing plate 1 is efficiently converted in the viewing direction, particularly the front direction, while preventing emission (leakage) from the cell surface, and other light is totally reflected. The light is transmitted backward, is incident on the optical path changing slope A1 on the rear side, is efficiently optically changed in the viewing direction, and a display with excellent brightness can be achieved on the entire surface of the cell display surface.

In the above description, the liquid crystal cell 2 is of an appropriate transmission type, that is, as shown in FIGS.
A liquid crystal 25 is sealed between the first and the second 28 via a sealing material 24, and the incident light from the side where the optical path-changing polarizing plate 1 is disposed is turned into the display light through the control by the liquid crystal or the like from the other side. A type that emits light can be used, and the type is not particularly limited.

Incidentally, specific examples of the above-mentioned liquid crystal cell include twisted and non-twisted types such as TN liquid crystal cell, STN liquid crystal cell, IPS liquid crystal cell, HAN liquid crystal cell, OCB liquid crystal cell and VA liquid crystal cell, guest host type, and the like. Examples thereof include a ferroelectric liquid crystal type and a light diffusion type, and a liquid crystal driving method may be an appropriate method such as an active matrix method or a passive matrix method. The driving of the liquid crystal is usually performed by using transparent electrodes 22, 2 provided inside a pair of cell substrates 21, 28 as illustrated in FIGS.
7 is performed.

As the cell substrate, an appropriate transparent substrate made of glass, resin, or the like can be used. In particular, a substrate made of an optically isotropic material is preferable from the viewpoint of display quality and the like. Further, a material having excellent colorless transparency such as a non-alkali glass plate with respect to a blue glass plate is preferable in terms of improvement of luminance and display quality, and a resin substrate is more preferable in terms of lightness and the like. The thickness of the cell substrate is not particularly limited, and can be appropriately determined according to the sealing strength of the liquid crystal and the like. Generally, it is 10μ from the point of balance between light transmission efficiency and thin and light weight.
m to 5 mm, preferably 50 μm to 2 mm, especially 100 μm to 1 mm.

In forming a liquid crystal cell, if necessary, one or two or more appropriate functional layers such as an alignment film such as a rubbing film for aligning liquid crystal and a color filter for color display are provided. be able to. As shown in the figure, the alignment films 23 and 26 usually have transparent electrodes 22 and 27.
And a color filter (not shown) is usually provided between one of the cell substrates 21 and 28 and the transparent electrode.

When forming the liquid crystal display device, if necessary, as shown in FIGS. 7 and 8, the polarization on the opposite side of the liquid crystal cell 2 on which the retardation plates 31 and 32, the light diffusion layer 33, and the optical path conversion polarizing plate 1 are arranged. One or more appropriate optical layers such as the plate 34 can be added. A polarizing plate aims at achieving display using linearly polarized light, and a retardation plate aims at improving display quality by compensating for a phase difference due to birefringence of liquid crystal and the like. In addition, the light diffusion layer expands the display range by diffusing the display light, equalizes the luminance by leveling the bright line emission through the light path conversion slope, and enters the light path conversion polarizing plate by diffusing the transmission light in the liquid crystal cell. The purpose is to increase the amount of light.

The polarizing plate disposed on the viewing side of the liquid crystal cell may have been subjected to a non-glare treatment or an anti-reflection treatment for the purpose of preventing the visibility from being hindered by surface reflection of external light. Non-glare treatment can be performed by forming a fine uneven structure on the surface by various methods such as a roughening method such as a sand blast method or an embossing method, a method of blending transparent particles such as silica, etc. It can be applied by a method of forming a coherent vapor deposition film. The non-glare treatment and the anti-reflection treatment can also be applied to the above-mentioned method of bonding a film provided with a fine surface unevenness structure or an interference film. The polarizing plate can be provided on both sides of the liquid crystal cell as shown in the figure, but in this case, the optical path conversion polarizing plate according to the present invention is provided only on one side of the liquid crystal cell with the surface on which the optical path converting means is formed outside.

On the other hand, as a retardation plate, a birefringent film obtained by stretching a polarizing plate made of a suitable polymer such as those exemplified in the transparent protective layer by a suitable method such as uniaxial or biaxial, An appropriate film such as an alignment film of a suitable liquid crystal polymer such as a nematic system or a discotic system or a structure in which the alignment layer is supported by a transparent substrate can be used, and under the action of the heat shrinkage force of the heat shrinkable film. It may be one in which the refractive index in the thickness direction is controlled.

As shown in the figure, the compensating retarders 31 and 32 are usually arranged as necessary between the viewing side and / or back side polarizing plates P and 34 and the liquid crystal cell, and the retarder Can be appropriately selected depending on the wavelength range or the like. Further, the retardation plate may be used by superposing two or more layers for the purpose of controlling optical characteristics such as retardation.

The light diffusion layer can also be provided by an appropriate method using a coating layer or a diffusion sheet having a fine surface irregularity structure according to the non-glare layer. The light diffusion layer can be disposed as an adhesive layer 33 also serving as an adhesive between the polarizing plate 34 and the retardation plate 32 as shown in the figure according to the adhesive layer 15 containing the transparent particles described above, thereby achieving a reduction in thickness. be able to. The light diffusion layer can be arranged on the outer side (viewing side) of the polarizing plate. However, by arranging the light diffusion layer on the liquid crystal cell side of the polarizing plate 34 as shown in the figure, light is absorbed after external light is absorbed by the polarizing plate. Since the light is incident on the diffusion layer, reflection loss due to back scattering through the light diffusion layer can be advantageously suppressed.

On the other hand, the illumination device arranged on the side surface of the liquid crystal cell aims to make light used as illumination light for the liquid crystal display device enter from the side surface of the liquid crystal cell. This makes it possible to reduce the thickness and weight of the liquid crystal display device in combination with an optical path changing polarizer disposed at the back or front of the liquid crystal cell. Any suitable lighting device can be used. For example, a linear light source such as a (cold or hot) cathode tube, a point light source such as a light-emitting diode, or an array in which the light sources are arranged linearly or in a plane, or a point light source An illumination device or the like in which a light source and a linear light guide plate are combined to convert incident light from a point light source into a linear light source via the linear light guide plate can be preferably used.

As shown in the examples of FIGS.
It can be arranged on one or more side surfaces of the liquid crystal cell 2. When the lighting device is arranged on two or more side surfaces, the plurality of side surfaces may be a combination of opposing side surfaces as in the example of FIG. 8, or may be a combination of side surfaces that cross vertically and horizontally. A combination of three or more sides may be used.

The illuminating device enables visual recognition in the transmission mode by turning on the light. In the case of a reflective / transmission type liquid crystal display device, it is not necessary to turn on the light when viewing in the reflection mode by external light. Therefore, it can be switched between lighting and extinguishing. An arbitrary method can be adopted as the switching method, and any of the conventional methods can be adopted. Note that the illumination device may be of a different color emission type capable of switching the emission color, or may be of a different color emission type through different types of illumination devices.

As shown in the figure, for the lighting devices 5 and 51,
In order to guide the divergent light to the side surface of the liquid crystal cell 2 as needed, it may be a combination body in which appropriate auxiliary means such as a reflector 52 surrounding the liquid crystal cell 2 are arranged. As the reflector, a suitable reflection sheet such as a resin sheet, a white sheet, or a metal foil provided with a high-reflectance metal thin film can be used. The reflector can also be used as a fixing means that also surrounds the lighting device by, for example, bonding the end to an end of a liquid crystal cell such as a cell substrate.

In the present invention, optical elements or components such as a liquid crystal cell, a polarizing plate, and a retardation plate forming the liquid crystal display device described above may be entirely or partially laminated and integrated and fixed. , May be arranged in an easily separable state. It is preferable to be in a fixed state rather than to prevent reduction in contrast by suppressing interface reflection. An appropriate transparent adhesive such as a pressure-sensitive adhesive can be used in the adhesion and adhesion treatment, and the transparent adhesive layer can be made to contain the above-mentioned transparent particles and the like to form an adhesive layer having a diffusion function.

The above-mentioned optical element or component, particularly on the visual side, is 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. UV absorption ability can be imparted by such means.

[0064]

Example 1 Acrylic UV-curable resin (Aronix UV-3701 manufactured by Toagosei Co., Ltd.) was placed in a mold previously processed into a predetermined shape.
Was dropped and filled with a dropper, and an 80 μm-thick triacetyl cellulose (TAC) film (surface saponified product) was allowed to stand still, and was adhered tightly with a rubber roller to remove excess resin and air bubbles. Then, a metal halide lamp was used. After curing by irradiation with ultraviolet rays, the film was peeled from the mold and cut into a predetermined size to obtain a transparent protective film having a TAC film having a refractive index of 1.49 and an optical path changing means layer having a refractive index of 1.52.

Next, the transparent protective film was placed on one side of a polyvinyl alcohol-based polarizing film (refractive index: 1.5) via a polyvinyl alcohol-based adhesive so that the optical path conversion means layer was on the outer surface, and the ridge line was predetermined. And an 80 μm thick T on the other surface of the polarizing film.
An AC film was similarly adhered, and a phenoxyethyl acrylate-containing acrylic adhesive layer having a refractive index of 1.51 was attached to a surface having no optical path changing means, and covered with a release sheet to obtain an optical path changing polarizing plate. .

The above-mentioned optical path-changing polarizing plate has a width of 60 mm and a depth of 45 mm, and has prism-shaped concave portions whose ridge lines are parallel and continuous in the width direction at a pitch of 210 μm (FIG. 1c). The inclination angle is 42 degrees, the inclination angle of the gentle slope A3 changes in the range of 1.8 to 3.5 degrees, the change of the inclination angle of the nearest gentle slope is within 0.1 degrees, and the polarizing plate of the optical path changing slope is used. The projection width on the surface is 10 to 16 μm, and the projection area ratio of the gentle slope / optical path conversion slope to the polarizing plate surface is 12 times or more.

Then, the above-mentioned optical path-changing polarizing plate is adhered to the visible rear side of a commercially available TN type liquid crystal cell via the adhesive layer,
A cold-cathode tube is placed on the side of the cell, surrounded by a reflector made of a silver-evaporated reflection sheet, and both ends are adhered to the upper and lower surfaces of the cell to fix the cold-cathode tube. Normally white transmission type TN
A liquid crystal panel was obtained, and a reflection plate made of a white polyester film was disposed on the back surface of the liquid crystal panel to obtain a reflection / transmission type liquid crystal display device. In addition, the optical path conversion polarizing plate was arranged so that the optical path conversion slope faced parallel to the cold cathode tube.

Example 2 Instead of the TAC film, a 75 μm-thick polycarbonate (PC) film was used to form an optical path changing means layer according to Example 1 and then peeled off from the PC film to obtain an optical path changing film. A TAC film having a thickness of 80 μm is adhered to both sides of a polyvinyl alcohol-based polarizing film via a polyvinyl alcohol-based adhesive so that the refractive index is 1.51 on one side of the polarizing plate so that the optical path changing means layer is on the outer side. And an acrylic pressure-sensitive adhesive layer having a refractive index of 1.51 was attached to the other surface of the polarizing plate, covered with a release sheet, and the obtained optical path-changing polarizing plate was used as an example. A reflective / transmission type liquid crystal display device was obtained according to 1.

Example 3 Using different molds, the inclination angle of the optical path changing slope A1 was about 4
At 2 degrees, the projection width on the polarizing plate surface is 10 to 16 μm,
A prism-shaped recess having an apex angle of 70 degrees with the steep slope A2
An optical path conversion film having a pitch of μm and having an optical path conversion means (FIG. 1b) having a flat surface A4 having an area of 10 times or more the total projected area of the optical path conversion slope and the steep slope to the polarizing plate surface was obtained. Was used to obtain an optical path-changing polarizing plate and a reflective / transmissive liquid crystal display device according to Example 2.

Example 4 Using different molds, the inclination angle to the polarizing plate surface was about 42
An optical path changing means (FIG. 1b) having a length of 80 .mu.m and comprising a light path changing slope A1 having a projection width of 10 .mu.m and a steep slope A2 having an inclination angle of about 55 degrees, the length direction of which is substantially parallel to the width direction. And an optical path conversion film (FIG. 6) in which the optical path conversion means is gradually arranged at a higher density as the distance from the light incident side in the depth direction increases, is used. A polarizing plate and a reflection / transmission type liquid crystal display device were obtained. The area of the flat surface A4 is at least 10 times the total projected area of the optical path conversion slope and the steep slope on the polarizing plate surface.

Example 5 An optical path-changing polarizing plate and a reflection / transmission type liquid crystal display device were obtained in the same manner as in Example 2 except that the refractive index of the surface and the second adhesive layer was 1.52.

Example 6 Using different molds, the inclination angle with respect to the polarizing plate surface was about 42
80 μm long optical path converting means consisting of an isosceles triangle with an optical path converting slope A1 having a projection width of 10 μm in degrees (FIG. 1a)
Having a length direction parallel to the width direction, and randomly arranging the optical path changing means such that the density gradually increases from the light incident side in the depth direction toward the center. A film (FIG. 4) was obtained, and an optical path-changing polarizing plate was formed using the film according to Example 2, and the opposing 2
Reflection / reflection is the same as in Example 2 except that a cold cathode tube is placed on the side.
A transmissive liquid crystal display device was obtained. The area of the flat surface A4 is at least 10 times the total area of the two optical path changing slopes.

COMPARATIVE EXAMPLE 1 Instead of the optical path conversion film, a scattering sheet whose surface was roughened by sandblasting was obtained.
A light-scattering type polarizing plate and a reflection / transmission type liquid crystal display device (FIG. 9) were obtained according to the method described above. In addition, the scattering sheet was arranged with the rough surface as the visible back side.

Comparative Example 2 An optical path-changing polarizing plate and a reflective / transmissive liquid crystal display device were obtained in the same manner as in Example 2 except that the surface and the second adhesive layer had a refractive index of 1.46.

Comparative Example 3 An optical path-changing polarizing plate and a reflective / transmissive liquid crystal display device were obtained in the same manner as in Example 2 except that the surface and the second adhesive layer had a refractive index of 1.48.

Comparative Example 4 Using different molds, the inclination angle of the optical path changing slope A1 was about 3
At 0 degree, the projection width on the polarizing plate surface is 10 to 16 μm,
A prism-shaped recess having an apex angle of 70 degrees with the steep slope A2
An optical path conversion film having a pitch of μm and having an optical path conversion means (FIG. 1b) having a flat surface A4 having an area of 10 times or more the total projected area of the optical path conversion slope and the steep slope to the polarizing plate surface was obtained. Was used to obtain an optical path-changing polarizing plate and a reflective / transmissive liquid crystal display device according to Example 2.

Comparative Example 5 An optical path-changing polarizing plate and a reflection / transmission type liquid crystal display device were obtained in the same manner as in Example 6, except that the surface and the second adhesive layer had a refractive index of 1.46.

Evaluation Test For the reflection / transmission type liquid crystal display devices obtained in the examples and comparative examples, the cold cathode tube was turned on without applying a voltage to the liquid crystal cell, and the incidence part, the central part and the The front luminance at the opposite end is measured by a luminance meter (BM, manufactured by Topcon Corporation).
7). In Example 6 and Comparative Example 5, one of the cold-cathode tubes was arranged as the incident portion, and the other side was defined as the opposite end.

The above results are shown in the following table. Front luminance (cd / m ² ) Incident part Central part Opposite end Example 1 28 30 32 Example 2 27 29 29 Example 3 25 26 28 Example 4 27 27 27 Example 5 24 27 26 Example 6 53 58 50 Comparative Example 1 6 5 5 Comparative Example 2 26 20 13 Comparative Example 3 28 22 18 Comparative Example 4 21 14 11 Comparative Example 5 55 46 56

From the table, it can be seen that in the embodiment, in the transmissive mode, superior front luminance was achieved as compared with Comparative Examples 1 and 4. This is because in Comparative Examples 1 and 4, light was emitted in the direction opposite to the light source in the transmission mode, and the emitted light was poor in brightness in the front direction and hardly contributed to display. In particular, in Comparative Example 1, the emitted light was poor in any direction. In the transmission mode of the embodiment, it can be seen that a substantially uniform luminance distribution is achieved at the incident portion, the central portion, and the opposite end portion. However, in Comparative Examples 2 and 3, the farther away from the light source, the darker and the light is opposed to the incident portion. It can be seen that the brightness difference at the end is large and the uniform brightness distribution is poor, and the brightness difference is particularly remarkable in Comparative Example 2.

In comparison between the embodiment 6 and the comparative example 5 using the two-lamp system, the improvement of the luminance by the two-lamp system was remarkable in the embodiment 6, and the luminance distribution was almost uniform at the incident portion, the central portion and the opposite end portion. It can be seen that the state of the emitted light was almost uniform, whereas the brightness of the central part was lower in Comparative Example 5 and the overall brightness was lower than in Example 6. Further, in the transmission mode, there was no problem in visual recognition in a state where a voltage was applied to the liquid crystal cell, and the display quality was good.

On the other hand, even in the reflection mode in which external light is incident at an angle of 15 degrees by the ring-shaped illumination with the cold-cathode tube turned off, in the embodiment, good display without image disturbance or the like is obtained in the state where voltage is applied to the liquid crystal cell. Met. As described above, in the embodiment, a bright display is achieved in both the transmission mode and the reflection mode. Accordingly, in the present invention, the light guide plate avoids the bulkiness and weight increase, and the light path conversion type polarizing plate is used to reduce the thickness and weight. It can be seen that a transmission-type or reflection / transmission-type liquid crystal display device with good display quality can be formed while achieving the display quality.

[Brief description of the drawings]

FIG. 1 is an explanatory side view of an example of an optical path conversion polarizing plate (optical path conversion slope).

FIG. 2 is an explanatory plan view of an optical path changing slope;

FIG. 3 is an explanatory plan view of another optical path changing slope;

FIG. 4 is an explanatory plan view of still another optical path conversion slope;

FIG. 5 is an explanatory side view of another example of the optical path changing polarizing plate.

FIG. 6 is an explanatory side view of still another example of the optical path conversion polarizing plate.

FIG. 7 is an explanatory sectional view of an example of a transmissive (reflective / transmissive) liquid crystal display device.

FIG. 8 is an explanatory sectional view of another example of a transmissive (reflective / transmissive) liquid crystal display device.

FIG. 9 is an explanatory sectional view of an example of a conventional transmission type liquid crystal display device.

[Explanation of symbols]

1: Optical path conversion polarizer P: Polarizer 11, 11a: Optical path conversion means layer A: Optical path conversion means (A1: Optical path conversion slope, A3, 4: flat surface) 12, 14: Transparent protective layer 13: Polarizer 11b 15: Adhesive layer 2: Liquid crystal cell 21, 28: Cell substrate 25: Liquid crystal layer 31, 3
2: phase difference plate 34: polarizing plate 5, 51: lighting device 4: light reflection layer

Continuation of front page (72) Inventor Takao Suzuki 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 2H042 BA04 BA14 BA16 2H049 BA02 BB33 BB43 BB51 BB63 BC09 BC14 BC22

Claims (17)

[Claims] 1. A polarizing plate having a transparent protective layer on at least one side of a polarizer, having an adhesive layer on one surface, and the other side of the polarizing plate having an inclination angle of 35 to 4 with respect to the polarizing plate surface.
The adhesive layer and the optical path changing slope forming material have a refractive index of the polarizer or the transparent protective layer, which has a repeating structure of irregularities having an optical path changing slope which is oriented at a substantially constant direction at 8 degrees. An optical path-changing polarizing plate, which is equal to or more than. 2. The optical path-changing polarizing plate according to claim 1, wherein the optical path-changing slope having a substantially constant direction includes two or more surfaces including one surface or a surface facing the opposite direction with respect to one surface. 3. The film according to claim 1, wherein a repeating structure of irregularities having an optical path changing slope is formed on an outer surface of a film adhered to the other side of the polarizing plate via a second adhesive layer, An optical path-changing polarizing plate wherein the refractive index of the second adhesive layer is also equal to or greater than the refractive index of the polarizer or the transparent protective layer. 4. The optical path-changing polarizing plate according to claim 1, wherein at least the adhesive layer on the surface is an adhesive layer. 5. The optical path-changing polarizing plate according to claim 4, wherein the exposed surface of the adhesive layer on the surface is covered with a release sheet. 6. The optical path-changing polarizing plate according to claim 1, wherein the inclination angle of the optical path-changing slope with respect to the polarizing plate surface is 38 to 45 degrees. 7. An optical path-changing polarizing plate according to claim 1, wherein the optical path-changing slope is based on a groove structure having a substantially isosceles triangle in cross section or another triangle in cross section. 8. The optical path-changing polarizing plate according to claim 1, wherein the optical path-changing slope is based on a groove or projection structure having a substantially quadrangular or pentagonal cross section. 9. The optical path according to claim 1, wherein a flat surface having an inclination angle of not more than 5 degrees with respect to the polarizing plate surface is at least 10 times as large as an inclined surface having an inclination angle of not less than 35 degrees based on an occupied area on one surface of the polarizing plate. Conversion polarizer. 10. The uneven structure according to claim 1, wherein the concavo-convex structure having the optical path changing slope has an inclination angle of 3 with respect to the polarizing plate surface.
An optical path changing slope of 8 to 45 degrees, a flat surface having an inclination angle of 5 degrees or less and a width of 10 times or more of the optical path changing slope, and being based on a continuous groove having a substantially triangular cross section extending from one end to the other end of the polarizing plate. An optical path changing polarizing plate. 11. The uneven structure according to claim 1, wherein the concave / convex structure having the optical path changing slope is based on a polygonal discontinuous groove having a cross section of approximately three to five, and the length of the discontinuous groove is five times the depth. Above,
An optical path-changing polarizing plate, wherein an optical path changing slope is formed in the length direction of the groove at an inclination angle of 38 to 45 degrees with respect to the polarizing plate surface, and the area of the discontinuous groove portion on one side of the polarizing plate is 10% or less. 12. The optical path-changing polarizing plate according to claim 11, wherein discontinuous grooves having an optical path-changing slope are randomly arranged. 13. An optical path-changing polarizing plate according to claim 1, 2 or 4 to 12, wherein a repeating structure of irregularities having an optical path-changing slope is formed in the same manner as the transparent protective layer of the polarizing plate. 14. An optical path-changing polarizing plate according to claim 1, wherein a light reflecting layer is disposed in close contact with a surface having an uneven structure having an optical path-changing slope. 15. The optical path-changing polarizing plate according to claim 1, wherein the ridge line of the optical path-changing slope is parallel to one side of the polarizing plate or inclined within ± 30 degrees. 16. The optical path-changing polarizing plate according to claim 1, wherein the adhesive layer is of a light diffusion type. 17. The optical path-changing polarizing plate according to claim 16, wherein the light diffusion type adhesive layer is provided on the surface of the polarizing plate.