KR20000057869A - Polarizing element and liquid crystal display device having the same - Google Patents

Abstract

PURPOSE: A polarization device and a liquid crystal display device having the same are provided to improve the quality of the image displayed on the liquid crystal display device by increasing the efficiency of the light from a back light assembly. CONSTITUTION: A polarization device includes an isotropy member(3) and an anisotropy member(4). The isotropy member(3) and the anisotropy member(4) are accumulated so as to form a geometrical structure on a border of the isotropy member(3) and the anisotropy member(4). The light incident on the surface of the anisotropy member penetrates the border between the isotropy member(3) and the anisotropy member(4) so as to focus the polarization light in parallel at the accumulation direction, and the light of the another polarization direction is reflected on a border member between the isotropy member(3) and the anisotropy member(4).

Description

Polarizing element and liquid crystal display device having the same {POLARIZING ELEMENT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME}

The present invention relates to a polarizing element used in a liquid crystal display device and a liquid crystal display device having the same.

1 is a cross-sectional view showing the structure of a conventional liquid crystal display device. In this conventional liquid crystal display device, as shown in FIG. 1, a prism sheet 105 is provided in front of a backlight 107 in order to improve luminance in a direction perpendicular to the display surface of the liquid crystal panel. . The liquid crystal display panel 102 is provided on the prism sheet 105 opposite to the backlight 107. The polarizing plate 101b is mounted on the surface of the liquid crystal display panel 102 on the prism sheet 105 side, and the polarizing plate 101a is mounted on the surface of the liquid crystal display panel 102 on the opposite side to the prism sheet 105.

Since the prism sheet 105 is provided to the liquid crystal display device in the above manner, utilizing the refractive effect of the prism face of the prism sheet 105 improves the brightness of the light from the backlight 107. However, when the light transmitted through the prism sheet 105 passes through the polarizing plate 101b, the light in the absorption axis direction of the polarizing plate 101b is absorbed by the polarizing plate 101b. As a result, the amount of light from the backlight 107 is no more than half. Increasing the brightness of the backlight 107 in order to increase the brightness of the liquid crystal panel 102 increases the power consumption and the amount of heat generated by the backlight 107, thereby degrading reliability and display image quality.

Conventionally, the liquid crystal display device which uses the light of the absorption axis direction of a polarizing plate as light emitted on a liquid crystal panel was proposed.

For example, Japanese Patent Laid-Open No. 9-326205 discloses a conventional liquid crystal display device. 2 is a cross-sectional view showing the structure of a backlight used in the liquid crystal display device of Japanese Patent Laid-Open No. 9-326205. 3 is a cross-sectional view showing the structure of a sheet polarizing element used in the liquid crystal display device of Japanese Patent Laid-Open No. 9-274109.

As shown in Fig. 2, the backlight used in the liquid crystal display device of Japanese Patent Laid-Open No. 9-326205 has a light source 201, a light source 201 mounted on a side thereof, and reflective dots 221 on its bottom surface. A reflective light guide plate 202 formed thereon, a diffuse reflective film 231 provided on the bottom surface of the reflective light guide plate 202, and a polarizing beam splitter (dielectric multilayer) 230 provided on the top surface of the reflective light guide plate 202. It is composed. Light incident from the light source 201 to the reflective light guide plate 202 is guided to the upper surface of the reflective light guide plate 202 by the diffuse reflection film 231 and the reflection dots 221 to be incident on the polarizing beam splitter 230. do. The light having a specific polarization plane among the light incident on the polarization beam splitter 230 is returned to the reflective light guide plate 202 by the polarization beam splitter 230 so as to be reused as light for illuminating the liquid crystal display element.

In the liquid crystal display device using the backlight shown in FIG. 2, light having a specific polarization plane is reused, and the luminance of the liquid crystal display panel is improved. However, in order to obtain an effect of improving display quality higher than the effect of improving luminance by reusing light, a prism lens or the like for condensing light in a direction perpendicular to the display surface of the liquid crystal display panel should be further provided in the liquid crystal display device. do.

On the other hand, as shown in FIG. 3, the sheet-like polarizing element used in the liquid crystal display device of Japanese Patent Laid-Open No. 9-274109 includes a polarization split prism 320, a right triangle prism 330, and a polarization plane modulator 340. ), And the light scattering unit 350. The polarization splitting prism 320 polarizes and splits the unpolarized light 310. The inclination of the right triangular prism 330 overlaps the inclination of the polarization split prism 320. The polarization plane modulator 340 modulates the phase of the reflected polarized light polarized and divided by the polarization split prism 320. The light scattering unit 350 scatters the light obtained by converting the unpolarized light 310 into polarized light in an arbitrary direction. The sheet polarizing element has a function of scattering light, and has a form configured so that a unit constituting the polarizing element can be processed continuously.

The polarization splitting portion of the sheet-shaped polarizing element includes a high refractive index polarization splitting prism 320 and a low refractive index right-angle triangular prism 330. The polarization split prism 320 has an inclined surface 321 inclined such that the incident angle of the unpolarized light 310 is generally the Brewster angle θ _B , and an emission surface 322 in which the polarized light is emitted in one direction. The right triangular prism 330 has an incidence surface 332 having an angle of incidence of the unpolarized light 320 at right angles and an inclined surface 331 inclined similarly to the inclined surface 321.

The polarization splitter serves as a splitter that splits the unpolarized light 310 into transmitted light and reflected light that the polarization plane intersects at right angles at the interface between the inclined planes 321 and 331. Here, the boundary surface between the inclined surfaces 321 and 331 serves as a division part for dividing the P-polarized light and the S-polarized light in which the vibrating surface crosses each other perpendicularly. More specifically, the interface between the inclined surfaces 321 and 331 transmits the P-polarized light 311 having a vibration plane perpendicular to the interface and reflects the S-polarized light 312 having the vibration plane parallel to the interface.

The reflected light split by the polarization splitter is modulated by the polarization plane modulator 340. On the other hand, the angle of light incident on the inclined surface 323 located on the rear surface of the inclined surface 321 of the polarization split prism 320 is the external medium (right angle triangular prism 330 having a low refractive index) opposite to the polarization split prism 320. Not less than the critical angle with respect to Therefore, the inclined surfaces 323 and 321 serve as total reflection surfaces for total reflection of the reflected light.

The polarization plane modulator 340 is a half wave plate provided between the right triangular prism 330 having a low refractive index and the surfaces 334 and 324 of the polarization split prism 320 parallel to the unpolarized light 310. . The polarization plane modulator 340 serves as a phase modulator for changing the polarization plane of the reflected light reflected from the inclined plane 321 and matching the polarization plane with the polarization plane of the transmitted light. Here, the polarization plane modulator 340 modulates the phase of the reflected S-polarized light having a vibration plane parallel to the inclined plane 321 by 1/2 wavelength in order to convert the S-polarized light into the P-polarized light 313. Therefore, the polarization plane modulator 340 serves as a modulator for converting the phase of the incident linearly polarized light by 1/2 wavelength to modulate the emitted linearly polarized light perpendicular to the polarization plane of the incident light.

The light scattering unit 350 is a light scattering sheet provided to be parallel to the polarization exit surface 322 of the polarization splitting prism 320 and has a nonuniform refractive index structure made of at least two kinds of materials having different refractive indices. The light scattering unit 350 has a function of scattering the polarized light emitted from the polarization exit surface 322 as non-directional polarized light. Here, the P-polarized light incident on the incident surface 351 of the light scattering part 350 is scattered by a nonuniform refractive index structure constituting the light scattering part 350 at a refractive index interface made of materials having different refractive indices. do. Therefore, the light scattering unit 350 has a function of scattering P-polarized light incident on the incident surface 351 as non-directional P-polarized light.

In the polarizing element, since the inclined planes of the prisms are inclined such that the incident light of the unpolarized light 310 is generally the Brewster angle θ _B as the incident light source, any incident polarized light is incident to the P polarized light 311 by the inclined plane 321. S polarized light 312 is divided. Then, only the reflected S-polarized light 312 is converted into P-polarized light by the 1/2 wave plate by the polarization plane modulator 340 parallel to the incident light. The P-polarized light 311 and the converted P-polarized light 313 as transmitted light are incident on the light scattering part 350 to be scattered by the light scattering part 350. As a result, unpolarized light as any polarized light is directed to undirected linearly polarized light polarized in one direction so that it can be used in a liquid crystal display without optical loss.

However, in the sheet-shaped polarizing element shown in FIG. 3, when the unpolarized light 310 is incident on the incidence surface 332, sometimes it does not enter the inclined surface 321 of the prism, but rather to the half wave plate 340. You will join. At this time, the sheet-shaped polarizing element cannot satisfy the function of aligning the light incident on the 1/2 wave plate without being incident on the inclined surface 321 of the prism with the linearly polarized light so as to be emitted from the sheet-shaped polarizing element. For this reason, the problem that the function of a polarizing element falls and the light absorbed in the absorption axis direction of a polarizing element increases. In addition, since the light scattering sheet is used as the light scattering portion 350, the amount of light incident on the light scattering sheet by the light scattering sheet is reduced when light passes through the light scattering sheet.

An object of the present invention is to provide a polarizing element capable of efficiently using light from a backlight of a liquid crystal display device to obtain high display image quality, and to provide a liquid crystal display device including the polarizing element.

In order to achieve the above object, the present invention provides a polarizing element through which the linearly polarized light oscillating in a specific vibration direction of the light emitted from the light source is transmitted, the polarizing element is configured so that the anisotropic body and the anisotropic body are laminated, When light is incident on the anisotropic surface opposite the isotropic body, the geometric surface is formed at the interface between the isotropic body and the anisotropic body, and one linear polarization of the light oscillating in the specific vibration direction is generally parallel to the stacking direction of the isotropic body and the anisotropic body. The other linearly polarized light of the light transmitted through the interface between the isotropic body and the anisotropic body to be condensed in the direction, and at the same time vibrating in the direction perpendicular to the specific vibration direction is reflected from the interface between the isotropic body and the anisotropic body.

According to the above invention, the polarizing element is configured such that an isotropic body and an anisotropic body are laminated, and a geometrical surface is formed at an interface between the isotropic body and the anisotropic body. As a result, when light from the light source enters the surface of the anisotropic layer on the opposite side of the isotropic layer, one linear polarization of the light vibrating in a specific vibration direction is condensed in a direction parallel to the stacking direction of the isotropic body and the anisotropic body. It will penetrate the surface. At the same time, other linearly polarized light of the light incident on the anisotropic body vibrating in a direction perpendicular to the specific vibration direction is reflected from the geometric plane between the isotropic body and the anisotropic body. At this time, since the polarizing element includes an isotropic body and an anisotropic body, one linearly polarized light is transmitted and condensed while little attenuation of light from the light source occurs, and at the same time, the other linearly polarized light can be reflected. For example, when the polarizing element is used to construct a liquid crystal display device, the polarizing element is located in an optical path between the light source and the liquid crystal panel, so that the surface of the polarizing element on the anisotropic side faces the light source, and the surface on the isotropic side is It faces the liquid crystal panel. In this case, when passing through the polarizing element, one linearly polarized light of the light from the light source is condensed by the geometric plane of the polarizing element, and the concentrated linearly polarized light reaches the liquid crystal panel. This effect of the geometry surface for condensing light increases the brightness of the front side of the liquid crystal panel and improves the display quality of the liquid crystal display device. In addition, other linearly polarized light among the light from the light source is reflected by the geometry plane of the polarizing element. Here, for example, the other reflected linearly polarized light is converted into the one linearly polarized light so that it can be incident again on the polarizing element, so that another linearly polarized light of the light from the light source is also used as light for illuminating the liquid crystal panel. Therefore, a polarizing element is used so that two linearly polarized light from light sources vibrating in directions perpendicular to each other can be used as light for illuminating the liquid crystal panel. In addition, since the attenuation of light hardly occurs in this polarizing element, the light utilization efficiency in the liquid crystal display device can be improved.

The polarizing element may be configured such that a plurality of isotropic bodies and anisotropic bodies are alternately stacked to form a plurality of geometric surfaces. More specifically, the geometrical plane is formed such that a plurality of prism faces for condensing linearly polarized light in a direction generally parallel to the lamination direction are continuously arranged in a direction perpendicular to the lamination direction.

In addition, the present invention includes a light source, a polarizing element through which linearly polarized light is transmitted as long as it vibrates in a specific vibration direction among light emitted from the light source, and a liquid crystal panel for displaying an image thereon using linearly polarized light transmitted through the polarizing element. Provided is a liquid crystal display device, wherein the polarizing element is configured such that the isotropic body and the anisotropic body are laminated, the geometric surface is formed at the interface between the isotropic body and the anisotropic body, so that light from the light source from the surface of the polarizing element on the side of the anisotropic body In the case of incident light, one polarization of light vibrating in a specific vibration direction passes through the interface between the isotropic body and the anisotropic body so that the light is focused in a direction substantially parallel to the stacking direction of the isotropic body and the anisotropic body, and at the same time crosses perpendicularly to the specific vibration direction. The other linearly polarized light out of the light oscillating in the direction And it is reflected from the surface.

According to the above invention, the liquid crystal display device is provided with a polarizing element configured such that an isotropic body and an anisotropic body are laminated, and as a result, when light from the light source enters the surface of the polarizing element on the side of the anisotropic body, one of the light vibrates in a specific vibration direction. Linearly polarized light is transmitted through the polarizing element. At this time, this linearly polarized light is collected by the geometrical plane of the polarizing element so as to reach the liquid crystal panel. This effect of the geometric surface for condensing light increases the luminance at the front side of the liquid crystal panel and improves the display quality of the liquid crystal display device. In addition, other linearly polarized light among the light from the light source is reflected by the geometry plane of the polarizing element. Here, for example, the reflected other linearly polarized light is converted into the one linearly polarized light so that it can be incident again into the polarizing element, so that other linearly polarized light among the light from the light source can also be used as light for illuminating the liquid crystal panel. have. Since the attenuation of the light hardly occurs in the polarizing element in which the isotropic body and the anisotropic body are laminated to form a geometrical surface, a liquid crystal display device having high light utilization efficiency and high display image quality can be obtained.

In order to form a plurality of geometrical surfaces on the polarizing element, a plurality of anisotropic bodies and isotropic bodies may be configured to alternately stack a polarizing element. More specifically, the geometric surface is formed such that a plurality of prism faces for condensing linearly polarized light in a direction generally parallel to the lamination direction are arranged continuously in a direction perpendicular to the lamination direction.

1 is a cross-sectional view showing the structure of a conventional liquid crystal display device.

2 is a cross-sectional view showing a structure of a backlight used in a conventional liquid crystal display device.

3 is a cross-sectional view showing the structure of a sheet polarizing element used in a conventional liquid crystal display device.

4 is a cross-sectional view showing a structure of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 5 is a perspective view of the reflective polarizer shown in FIG. 1. FIG.

FIG. 6 is a view for explaining the function of the reflective polarizer for light from the backlight shown in FIG. 1; FIG.

Fig. 7 is a sectional view showing the structure of a reflective polarizing element used in the liquid crystal display device according to the second embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1a, 1b: polarizing plate

2: liquid crystal panel

3: isotropic layer

4: anisotropic layer

5: reflective polarizer

6: backlight

7: unpolarized light

8: P polarized light

9: S polarized light

10: prism face

11: geometric structure surface

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)

4 is a cross-sectional view showing the structure of a liquid crystal display according to a first embodiment of the present invention.

As shown in Fig. 4, in the liquid crystal display device according to the present invention, the polarizing plate 1a is mounted on one surface of the liquid crystal panel 2, and the polarizing plate 1b is mounted on the other surface of the liquid crystal panel. . The reflective polarizing element 5 is provided in the liquid crystal panel 2 on the polarizing plate 1b side. The backlight 6 as a light source is provided to the reflective polarizing element 5 on the opposite side of the liquid crystal panel 2. The reflective polarizing element 5 is composed of an isotropic layer 3 made of a film isotropic member and an anisotropic layer 4 made of a film anisotropic member, and the surfaces of the isotropic layer 3 and the anisotropic layer 4 are stacked on each other. The anisotropic layer 4 is located at the backlight 6 side, and the anisotropic layer 3 is located at the liquid crystal panel 2 side.

The geometric surface 11 composed of a plurality of prism faces 10 to be described later is formed at the interface between the isotropic layer 3 and the anisotropic layer 4. The reflective polarizing element 5 transmits linearly polarized light which vibrates in a specific vibration direction among the light emitted from the backlight 6 in order to obtain linearly polarized light. The front and back surfaces of the reflective polarizing element 5 are planar.

The backlight 6 includes a light guide plate to which light from a cold cathode fluorescent lamp, a cold cathode fluorescent lamp is incident, a reflector for reflecting light incident to the light guide plate toward the reflective polarizing element 5, and a surface uniformly emitted from the light guide plate. And a diffusion sheet for converting the light into a form. A dot pattern for scattering light is printed on the light guide plate of the backlight 6, so that a light source having a uniform surface shape can be obtained. The liquid crystal panel 2 displays an image thereon using P polarized light as linearly polarized light vibrating in a specific vibration direction among the light from the backlight 6.

5 is a perspective view of the reflective polarizing element 5. As shown in FIGS. 4 and 5, the plurality of triangular pyramidal prismatic portions whose cross-sectional shape is an isosceles triangle are aligned on the surface of the anisotropic layer 4 on the side of the isotropic layer 3 so as to be parallel to the anisotropic layer 4. The two side surfaces of each of the prism portions having the same surface area become the prism face 10 at the surface of the anisotropic layer 4 on the side of the isotropic layer 3. Further, the plurality of prism portions are formed on the surface of the isotropic layer on the side of the anisotropic layer 4, and the shape of each prism portion depends on the recess between two adjacent prism portions on the anisotropic layer 4. The isotropic layer 3 and the anisotropic layer 4 are laminated so that the inclined surfaces of the isotropic layer 3 and the prism portion of the anisotropic layer 4 face each other. Therefore, the plurality of prism portions of the isotropic layer 3 and the anisotropic layer 4 are continuously aligned in a direction perpendicular to the stacking direction, and these prism surfaces constitute the geometric surface 11.

The direction parallel to the ridges of the prism portions of the isotropic body 3 and the anisotropic body 4 is the X direction, the direction perpendicular to the X direction, and the directions parallel to the front and back surfaces of the reflective polarizing element 5 are the Y direction. In addition, the direction perpendicular | vertical to the front surface and back surface of the reflective polarizing element 5 is Z direction. When the refractive index in the X direction in the anisotropic layer 4 is N _X1 , the refractive index in the Y direction is N _Y1 , and the refractive index in the Z direction is N _Z1 , these relationships become N _X1 > N _Y1 = N _Z1 . When the refractive index in the isotropic layer 3 is N _X2 , the refractive index in the Y direction is N _Y2 , and the refractive index in the Z direction is N _Z2 , these relations are N _X2 = N _Y2 = N _Z2 . Moreover, the relationship of the refractive index between the isotropic layer 3 and the anisotropic layer 4 becomes _NX1 > _NX2 (= _NY2 = _NZ2 )> _NY1 = _NZ1 . The direction of the ridge line of the prism portion in the reflective polarizing element 5 coincides with the transmission axis of the polarizing plate 1b.

The function of the reflective polarizing element 5 with respect to the light from the backlight 6 will be described below with reference to FIG. 3. 3 is a diagram for explaining the function of the reflective polarizing element 5 with respect to the light from the backlight 6.

As shown in FIG. 6, when the unpolarized light 7 emitted from the backlight 6 enters the reflective polarizing element 5 from the surface of the reflective polarizing element 5 on the side of the anisotropic layer 4, the unpolarized light ( 7) penetrates the anisotropic layer 4 and reaches the geometry surface 11. Here, the P-polarized light 8 vibrating in the plane parallel to the Y-direction and the Z-direction among the unpolarized light 7 is focused in a direction perpendicular to the reflective polarization element 5 by the prism face of the geometric surface 11. It is refracted by the difference between the refractive indices N _Y1 and N _Y2 . The smaller the value of N _Y1 / N _Y2, which is the ratio of the refractive indexes N _Y1 and N _Y2, the stronger the effect of condensing the P polarization 8. In this case, however, the P polarized light 8 is reflected from the prism face, and the amount of light that does not proceed in the direction toward the liquid crystal panel 2 increases. In contrast, as the N _Y1 / N _Y2 value approaches 1, the reflection of the P-polarized light from the prism face of the geometry face 11 decreases. In this case, however, the condensing effect is reduced. The value of N _Y1 / N _Y2 , which sufficiently balances the improvement of the condensing effect of the P polarization 8 due to reflection and the suppression of light attenuation, is 0.75 to 0.95.

Of the light emitted from the backlight 6 in various directions, the propagation direction of the light having the maximum amount of light is generally the vertical direction of the backlight 6. In order to minimize the attenuation of the light due to the reflection of the P-polarized light from the geometry plane 11 of the reflective polarizing element 5, the following equation is satisfied as the vertex angle θ of each prism portion of the anisotropic layer 4. It is preferable.

θ = (90-arctan (N _Y1 / N _Y2 )) × 2

Although the pitch of the prism portion of the isotropic layer 3 and the anisotropic layer 4 may be 30 to 300 µm, in order to prevent moire on the liquid crystal panel 2 with respect to the pixel array, the pitch of the prism portion may be 50 µm. It is preferable not to exceed.

On the other hand, of the unpolarized light 7 reaching the geometric plane 11, the S polarized light 9 oscillating in a plane parallel to the X direction and the Z direction is shown in FIG. 6 due to the difference between the refractive indices N _X1 and N _X2 . As reflected from the geometry surface 11. The value of N _X1 / N _X2 may not be less than 1.03, and the larger this value, the higher the reflection efficiency of the S polarized light 9 on the geometry surface 11. After the reflected S-polarized light 9 is reflected from the reflecting plate of the backlight 6, it is scattered by the dot pattern printed on the light guide plate of the backlight 6 so as to be reused as light for illuminating the liquid crystal panel 2.

In the liquid crystal display device, since the S-polarized component absorbed by the absorption axis of the polarizing plate 1b is reflected from the backlight 6 by the reflective polarizing element 5 and reused, the light utilization efficiency is improved. Further, since the P polarized light 8 is focused in the vertical direction of the liquid crystal panel 2 by the geometric plane 11 of the reflective polarizing element 5, the luminance of the front surface of the liquid crystal panel 2 can be higher.

As a material of the anisotropic layer 4, polymethyl methacrylate or polycarbonate which is excellent in transparency, polystyrene or orfin resin having excellent molding property and mechanical strength and low water absorption is used. As a method of forming the anisotropic layer 4, for example, there is a method of extending the molding material at a temperature not higher than the melting point of the anisotropic layer 4 component in an extrusion process. The molding material is extended in this manner and oriented in the direction of extending the polymer to produce an anisotropic layer 4 where birefringence can occur. In addition, if one of the two rollers which extends the molding material when producing the anisotropic layer 4 is provided with an uneven portion according to the shape of the prism portion of the anisotropic layer 4, the prism portion of the anisotropic layer 4 is formed by molding. It may be formed in the above form.

As another material of the anisotropic layer 4, a liquid crystal compound can be used. In the method of molding the anisotropic layer 4 using the liquid crystal compound, the alignment agent is first applied to a transparent substrate, that is, a cellulose triacetate film to be burned. As the aligning agent, JALS-428 made by JSR can be used. The alignment film formed on the transparent substrate is rubbed in the Y direction, and a mixed solution of nematic liquid crystal and ultraviolet curable resin is applied onto the surface of the alignment film. In the alignment film, since the liquid crystal molecules are aligned in the direction perpendicular to the friction direction and the pretilt angle is 0 °, the above distribution of the refractive index of the anisotropic layer 4 can be maintained. A die in which the ridge direction of the prism portion is arranged in the X direction is pushed against the alignment film, and in such a state, ultraviolet light is emitted from the transparent substrate to cure the mixed solution on the alignment film. As the nematic liquid crystal, any liquid crystal of cyan based, fluorine based or chlorine based can be used. In addition, instead of nematic liquid crystals, polymer liquid crystals may also be used. As the ultraviolet curing resin, a single group acrylic compound, a single group methacrylic compound, a multigroup acrylic compound, a multigroup methacrylic compound, and the like can be used, and only one or two or more of these copolymers can be used. Since ultraviolet curable resin is hard to harden | cure by itself, it is preferable to add a polymerization initiator to ultraviolet curable resin. As the polymerization initiator, polymerization initiators such as thioxaanthones, diazo salts, and selenium salts may be used.

In order to produce the isotropic layer 3 which does not cause birefringence when light enters the isotropic layer 3, it is preferable to use an ultraviolet curable resin as the material of the isotropic layer 3. In the present embodiment, the compounds used as the material of the anisotropic layer 4 except for the liquid crystal are used as the material of the isotropic layer 3, and the step of forming the isotropic layer 3 is omitted. The method of forming the anisotropic layer 4 is used.

When laminating the anisotropic layer 4 and the isotropic layer 3 with each other, an ultraviolet curable transparent adhesive is used. As the ultraviolet curable transparent adhesive, a liquid crystal compound having a low viscosity that an epoxy, an acrylic resin, or the like to which fluorine is added, can be used as the base resin. In the case of using such an adhesive, the refractive index of the adhesive can be controlled by adjusting the content of fluorine in the adhesive. When adjusting the content of fluorine in the adhesive, the refractive index of the adhesive is made equal to the refractive index of the isotropic layer 3 of the reflective polarizing element 5 used in this embodiment. In the method of laminating the isotropic layer 3 and the anisotropic layer 4, first, a transparent adhesive is applied to the surface of the isotropic layer 3 on the prism portion side. Then, the anisotropic layer 4 is disposed on the transparent adhesive applied on the isotropic layer 3, and the ultraviolet is applied to the anisotropic layer 4 or the isotropic layer while applying pressure to the isotropic layer 3 and the anisotropic layer 4. (3) It emits with a transparent adhesive agent from the side.

It is preferable that the thickness of the isotropic layer 3 and the anisotropic layer 4 shall be 50-200 micrometers which can be processed easily.

The geometric surface 11 formed at the interface between the isotropic layer 3 and the anisotropic layer 4 is formed such that the prism faces of the right triangular prisms are continuous. In addition to this configuration, as shown in Figs. 1 and 2, the trapezoid obtained by the manner in which the right angle portions of the right triangular prism portions are cut by planes parallel to the isotropic layer and the anisotropic layer is continued. In this case, the boundary of these surfaces is doubled, and the outer pitch of the prism portion is also doubled. For this reason, the moire of the liquid crystal panel 2 concerning a pixel array hardly arises. Alternatively, the points of the prism portions of the isotropic layer 3 and the anisotropic layer 4 are formed to have curved surfaces. As a result, the isotropic layer 3 and the anisotropic layer 4 are hardly damaged, and the possibility of producing the reflective polarizing element 5 is further improved.

As described above, the liquid crystal display device of the present embodiment is provided with a reflective polarizing element 5 formed by stacking the isotropic layer 3 and the anisotropic layer 4 with each other to form the geometric surface 11. As a result, when the unpolarized light 7 from the backlight 6 enters the surface of the reflective polarizing element 5 on the side of the anisotropic layer 4, the P polarized light in the unpolarized light 7 is reflected polarizing element 5. Penetrates. At this time, the P-polarized light 8 is condensed in the stacking direction of the isotropic layer 3 and the anisotropic layer 4 by the geometric plane 11 to reach the liquid crystal panel 2. The effect of the geometry surface 11 for condensing the P polarization 8 increases the brightness of the front surface of the liquid crystal panel 2 and improves the display quality of the liquid crystal display device. In addition, the S polarized light 9 of the light from the backlight 6 is reflected by the geometry surface 11. Here, for example, the reflected S-polarized light 9 is converted to P-polarized light so that it can be reincident to the polarizing element, so that the S-polarized light 9 in the light from the backlight 6 also illuminates the liquid crystal panel 2. It can be used as light for. Since the light is hardly reduced in the reflective polarizer 5 formed by stacking the isotropic layer 3 and the anisotropic layer 4 so as to form the geometric surface 11, a liquid crystal having high light utilization efficiency and high display image quality. A display device can be obtained.

(2nd Example)

7 is a cross-sectional view showing the structure of a reflective polarizing element used in the liquid crystal display according to the second embodiment of the present invention. In the liquid crystal display device of this embodiment, instead of the reflective polarizer 5 of the liquid crystal display device according to the first embodiment, the reflective polarizer shown in FIG. 7 is used. The following description mainly relates to differences from the first embodiment.

As shown in FIG. 7, the reflective polarizing element 15 used in the liquid crystal display of the present embodiment is configured such that an isotropic layer and an anisotropic layer are alternately stacked. That is, the anisotropic layer 14a, the isotropic layer 13a, the anisotropic layer 14b, the isotropic layer 13b, the anisotropic layer 14c, and the isotropic layer 13c are laminated in order. The geometrical surface 21a is formed between the anisotropic layer 14a and the isotropic layer 13a, and the geometrical surface 21b is formed between the anisotropic layer 14b and the isotropic layer 13b, and the geometrical surface ( 21c is formed between the anisotropic layer 14c and the isotropic layer 13c. The anisotropic layers 14a, 14b, and 14c are made of a film anisotropic member, and the anisotropic layer 13c is made of a film isotropic member.

The geometrical surface 21a is composed of a plurality of prism faces 20a which are continuously arranged in a direction perpendicular to the stacking direction of the isotropic body and the anisotropic body. The geometrical surface 21b is composed of a plurality of prism faces 20b which are continuously arranged in a direction perpendicular to the stacking direction of the isotropic body and the anisotropic body, and the geometrical surface 21c is perpendicular to the stacking direction of the isotropic body and the anisotropic body. It consists of a plurality of prism faces 20c arranged continuously in the direction. Each shape of the prism faces 20a, 20b, and 20c is the same as the shape of the prism face 10 of the first embodiment, and each shape of the geometry faces 21a, 21b, and 21c is the geometry of the first embodiment. It is the same as that of the surface 11.

In each polarizing element 15, when light from the backlight enters the reflective polarizing element 15 from the side of the anisotropic layer 14a, the S polarized light is reflected from the geometry surfaces 21a, 21b, and 21c. . Therefore, when the reflective polarizing element 15 is used in the liquid crystal display device, compared with the liquid crystal display device of the first embodiment, the number of times that the S-polarized light is reflected is increased and the light utilization efficiency is increased.

The anisotropic layers 14a, 14b, and 14c are formed by the same compression molding method and stretching process as the anisotropic layer 4 of the first embodiment. Since the surfaces of each of the anisotropic layers 14b and 14c are in the form of a prism, all the irregularities along the prism portions of the anisotropic layers 14b and 14c are provided to the rollers extending the anisotropic material, so that the anisotropic layers 14b and 14c are provided. Can be formed. As a material of the isotropic layer 13a and 13b, the ultraviolet curable transparent adhesive agent used for bonding the isotropic layer 3 and the anisotropic layer 4 of 1st Example is used.

As described above, in the present invention, one linearly polarized light among the light incident on the surface of the polarizing element obtained by stacking the isotropic body and the anisotropic body on the anisotropic side is condensed by the geometrical surface formed on the interface between the isotropic body and the anisotropic body, and the polarization is performed. When the transmitted light is transmitted and at the same time when other linearly polarized light is reflected from the geometrical plane, the light attenuation of the polarizing element hardly occurs, and as a result, the polarizing element is used for the liquid crystal, so that a high-quality liquid crystal display device having high light utilization efficiency is obtained. Shows the effect of obtaining.

In addition, the present invention includes a liquid crystal panel for displaying an image using a polarizing element and a linear polarized light transmitted through the polarizing element after being emitted from the light source, and consequently the liquid crystal on the geometry of the polarizing element. The image is displayed on the liquid crystal panel by linearly polarized light focused in a direction perpendicular to the panel, so that the luminance of the liquid crystal panel in the front direction is improved, and the display image quality of the liquid crystal display device is improved. In addition, since the optical loss hardly occurs in the polarizing element and converts the linear polarized light reflected from the geometric plane into another linear polarized light for reuse, the light utilization efficiency of the liquid crystal display device can be improved.

Claims (6)

In the polarizing element through which linearly polarized light is transmitted as long as the light emitted from the light source vibrates in a specific vibration direction, Including isotropics and anisotropics, The isotropic body and the anisotropic body are laminated to each other to form a geometrical surface at an interface between the isotropic body and the anisotropic body, and when light from the light source enters the surface of the anisotropic body opposite to the isotropic body, the specific vibration direction The linearly polarized light of the light oscillating in the light passes through the interface between the isotropic body and the anisotropic body so that the linearly polarized light is focused in a direction substantially parallel to the stacking direction of the isotropic body and the anisotropic body, and at the same time, perpendicular to the specific vibration direction. And other linearly polarized light of light oscillating in a direction intersecting with each other is reflected from an interface between the isotropic body and the anisotropic body. The polarizing element according to claim 1, wherein a plurality of isotropic bodies and the anisotropic bodies are alternately stacked to form a plurality of geometric structural surfaces. 3. A shape according to claim 1 or 2, wherein the shape of the geometrical surface is a plurality of prism faces for condensing said linearly polarized light in a direction generally parallel to said lamination direction, arranged continuously in a direction perpendicular to said lamination direction Polarizing element configured to be. In the liquid crystal display device, Light source; A linear polarized light is transmitted as long as the light emitted from the light source vibrates in a specific vibration direction, and includes a isotropic body and an anisotropic body, wherein the isotropic body and the anisotropic body form a geometrical plane on an interface between the isotropic body and the anisotropic body. The linearly polarized light which vibrates in the specific direction when the light from the light source enters the polarizing element from the surface of the polarizing element on the anisotropic side, the stacking direction of the isotropic body and the anisotropic body The linear interface between the isotropic body and the anisotropic body is other linearly polarized light transmitted through the interface between the isotropic body and the anisotropic body so as to be condensed in a direction substantially parallel to the oscillating body, and at the same time vibrating in a direction perpendicular to the specific vibration direction. Reflected from; And Liquid crystal panel for displaying an image thereon using the linear polarized light transmitted through the polarizing element Liquid crystal display comprising a. The liquid crystal display device according to claim 4, wherein the polarizers are formed by alternately stacking a plurality of isotropic bodies and anisotropic bodies so that a plurality of geometrical surfaces are formed on the polarizers. 6. The shape of the geometric surface according to claim 4 or 5, wherein a plurality of prism faces for condensing one linearly polarized light in a direction substantially parallel to the lamination direction are continuously arranged in a direction perpendicular to the lamination direction. And a liquid crystal display device configured to be.