Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/13363—Birefringent elements, e.g. for optical compensation
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
  • G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
  • G02B5/0257—Diffusing elements; Afocal elements characterised by the diffusing properties creating an anisotropic diffusion characteristic, i.e. distributing output differently in two perpendicular axes
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
  • G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/133504—Diffusing, scattering, diffracting elements

Definitions

• the present invention relates to a light diffusion film having controlled scattering characteristics, an optical element and a liquid crystal display device using the same.
• the present invention relates to a light diffusion film having controlled scattering characteristics, an optical element using the same, and a liquid crystal display device.
• a reflective liquid crystal display device or a transflective liquid crystal display device in general, when incident light passes through the liquid crystal layer, is reflected by the reflective film, passes through the liquid crystal layer again, and enters a display image to the eyes of a viewer.
• a light scattering film on the surface of the liquid crystal layer and / or between the liquid crystal layer and the reflection film to scatter light, it is possible to view an image with a wide viewing angle. Light scattering is also called light diffusion.
• Typical methods for obtaining light scattering include, for example, a method in which transparent fine particles are dispersed and contained in a plastic film to scatter light, and a method in which light is scattered by roughening the surface of a plastic film.
• a method has been proposed in which a birefringent film is made of a superimposed body of birefringent films formed by dispersing and distributing minute regions having different birefringence characteristics, and light is scattered by using a refractive index difference between the birefringent film and the minute regions. (Japanese Patent Application Laid-Open No. 11-174214).
• a light diffusion film in which a large number of regions having a high refractive index are formed in a polymer film in a columnar shape in the thickness direction of the film is sold. According to this diffusion film, it is claimed that both the scattering in one direction and the transparency in the opposite direction are compatible, and that it is also possible to realize selective viewing angle / diffusion performance.
• this diffusion film a relatively bright image can be obtained at a specific viewing angle as compared with a conventional scattering film of the isotropic scattering type.
• the present invention has been made to solve such problems of the prior art, and has a light diffusion film having a selective light diffusing property and a light condensing property which provide a brighter image at a viewing angle than before. It is an object of the present invention to provide an optical film and a liquid crystal display device using the same. Disclosure of the invention
• the present invention provides the following to achieve the above object.
• one phase having a large refractive index includes a plurality of regions having a columnar structure extending in a thickness direction of the film.
• the region includes a region where the cross-sectional shape of the columnar structure is elongated, and the elongated region is A light-diffusing film, which is oriented in a specific direction of the film.
• the liquid crystal display device includes a polarizing film, and the polarizing axis of the polarizing film is installed so as to be inclined leftward or rightward when viewed from the viewing direction of the liquid crystal display screen, and the cross section of the region of the light diffusing film is provided.
• the short axis direction is deviated
• Figure 1 A-1D is a cross-sectional view of a diffusion film having a high refractive index region with a cylindrical structure in a polymer film, and a diffusion film in which a filler is filled in a polymer film, and a transmission scattering characteristic diagram of vertically incident light.
• Fig. 2 is an incident angle-dependent transmission-scattering characteristic diagram of a diffusion film having a high refractive index region with a cylindrical structure in the polymer film in the normal direction of the polymer film.
• Figs. 3A and 3B show the cylindrical structure in the polymer film.
• 3A and 3B are a cross-sectional view of a diffusion film having a high refractive index region of FIG. 1 inclined with respect to the normal direction of the film and a diagram of transmission scattering characteristics depending on an incident angle.
• FIG. 4 is a plan view of a diffusion film having a high refractive index region having a columnar structure with an elliptical cross section in a polymer film.
• Figures 5A and 5B show a cross-sectional view of a diffusion film having a high refractive index region with a columnar structure with an elliptical cross section in a polymer film inclined with respect to the normal direction of the film, and a diagram of transmission scattering characteristics depending on the incident angle. It is.
• FIGS. 6A and 6B are a cross-sectional view of a diffusion film having a high refractive index region having a columnar structure with an elliptical cross section in the polymer film in the normal direction of the polymer film, and a transmission scattering characteristic diagram depending on the incident angle.
• FIG. 7 is a schematic sectional view of a liquid crystal display device.
• FIG. 8 is a schematic sectional view of another liquid crystal display device.
• FIG. 9 is an explanatory diagram for explaining light diffusion / transmission characteristics of a laminated film of an optical film and a reflective polarizer.
• FIG. 10 shows a laminated finolem of the optical film of the present invention and an isotropic light diffusion film.
• FIG. 11A and FIG. 11B are a front view and a partial side view showing an example in which a diffusion film is used for a mobile phone.
• FIG. 12 shows an example in which the present invention is applied to a liquid crystal display device using a polarizing film.
• FIG. 13 is a view for explaining a photosensitive polymer exposure method in the example.
• FIG. 14 is a diagram illustrating a method for evaluating the transmission and scattering characteristics of a diffusion film in an example.
• FIG. 1A is a cross-sectional view of a conventional light diffusion film 1 in which a high refractive index region is formed in a cylindrical shape.
• a columnar high refractive index region 3 having a diameter close to the wavelength of light is formed perpendicular to the film surface.
• Such a cylindrical high refractive index region 3 functions as a cylindrical lens, and light incident perpendicular to the film, that is, parallel to the axis of the cylinder, scatters a Gaussian distribution having a half width of about 10 to 20 degrees, for example. Can be shown.
• FIG. 1B shows the intensity of transmitted light at an outgoing angle of 0 when light incident on the film surface at a perpendicular angle (zero incident angle) is transmitted through the film.
• the transmitted light intensity has a Gaussian distribution, the spread of scattering and the selectivity can be expressed by this half width.
• the half width is 10 ° It is.
• FIG. 1C shows a schematic cross section of a conventional scattering film of a type in which a filler is dispersed in a polymer film
• FIG. 1D shows the same scattering intensity of the transmitted light as in FIG. 1B. Comparing FIG. 1B with FIG. 1D, it is shown that the light diffusion film 1 of FIG. 1A shows selective scattering characteristics (scattering within a specific width).
• Figure 2 shows the scattering characteristics of the diffusion film of Figure 1A depending on the direction and angle of incident light.
• the center of the coordinates represents the case where light is incident perpendicular to the film surface.
• the figure drawn at this coordinate center (circle 4) shows the directivity of transmitted scattered light when light is incident perpendicular to the film surface. Indicates strength.
• the circle 4 indicates that the scattered light is isotropically scattered, and the size of the circle indicates that the scattered light has a large scattering intensity. Therefore, the outgoing light has a relatively small angle with respect to the incident optical axis (for example, 10 to 2). 0 °) strongly scattered.
• the elliptical figures 5 and 6 on the X axis of the coordinate axes are inclined at an angle of 0 (X) from the direction perpendicular to the film surface to the X axis direction of the film (the direction of the drawing normal in Fig. 1 is the X axis direction).
• This shows the directivity and intensity of transmitted scattered light when light is incident. It can be seen that the transmitted scattered light 5 and 6 have weaker scattering intensity as a whole than at normal incidence and less scattering in the X-axis direction than in the y-axis direction.
• circles or ellipses 7 and 8 on the y axis of the coordinate axis are inclined at an angle of 0 (y) from the direction perpendicular to the film surface to the y axis perpendicular to the X axis on the film.
• 2 shows the directivity and intensity of the transmitted scattered light when is incident. It can be seen that the transmitted scattered light 7, 8 has weaker scattering intensity as a whole than in the case of normal incidence, and less scattering in the y-axis direction than in the x-axis direction.
• Fig. 2 when light is incident from a direction perpendicular to the film surface (incident angle is 0 degree), a strong scattering in a certain range is observed. The diameter is small That is, it can be read that light scattering is reduced and most light is transmitted. It is also shown that when the light is incident at an angle 5 to 8, the light is scattered more laterally than in the direction parallel to the incident direction.
• Fig. 3A shows the same cylindrical area (cylindrical lens) 23 as in Fig. 1A, but not the normal direction to the surface of the polymer film 22 but the y-axis direction of the film (leftward in Fig. 3A). Is the positive direction of the y-axis).
• 1 shows a cross section of a diffusion film 21 formed with only an inclination.
• the light scattering of this film shows characteristics corresponding to the case where the light is incident from the axis direction of the cylindrical region 23 when the light is incident from the normal direction of the diffusion film in FIG. 1A.
• FIG. 3'B shows the same cylindrical area (cylindrical lens) 23 as in Fig. 1A, but not the normal direction to the surface of the polymer film 22 but the y-axis direction of the film (leftward in Fig. 3A). Is the positive direction of the y-axis).
• 1 shows a cross section of a diffusion film 21 formed with only an inclination.
• the angle of the film in the positive y-axis direction ⁇ corresponds to the case where the light enters from the normal direction of the film in FIG. 1B, and thus shows circular scattering.
• the transmitted light 25 when incident from the normal direction of the film is equivalent to that when incident from the y-axis minus angle ⁇ 0 of the film in FIG. 2, and the scattering intensity is smaller than the transmitted light 24 but X It shows elliptical scattering with strong directivity in the axial direction.
• the film's negative y-axis angle is 0.
• the transmitted light 26 when incident from an angle of incidence is greatly inclined with respect to the axis of the cylindrical lens and is incident from the transverse direction of the cylindrical lens, so that the scattering (intensity) is reduced.
• the transmitted light 27 and 28 when incident from the X-axis direction of the film show an inclined elliptical scattering characteristic as shown in Fig. 3B. It shows a tendency that the directivity in the y-axis direction becomes stronger.
• the diffuser films shown in FIGS. 3A and 3B are used in combination with a reflective film, the light incident from the front (positive y-axis direction) is It is strongly scattered in a certain angle range, so there is also a certain strong scatter in the direction of the viewer, and the reflected light has little scatter. No.
• incident light from the left and right (positive and negative directions of the X-axis) is scattered at a constant intensity, and has a light-gathering effect in the direction of the viewer. From the above, when viewing the display screen of a liquid crystal display device, for example, a mobile phone, having the diffusion film shown in FIGS.
• the diffusion film of the embodiment of FIG. 3A has superior selective scattering characteristics and light-collecting effect as compared with other diffusion films including the diffusion film of FIG. Have not been reported.
• embodiments of the disclosure of the prior art include disclosure that a cylindrical region can be formed in a polymer film at an angle to be used as a diffusion film. If the inclination directions are all the same, the diffusion film in the embodiment of FIG. 3A is obtained.
• a large number of high refractive index regions having a columnar structure having a long cross section are formed in a polymer film so as to extend in the film thickness direction, and
• the present invention provides a diffusion film in which regions are oriented in a specific direction of the film, preferably a diffusion film in which a long columnar structure is formed in parallel to the film surface so as to be inclined to the film surface. It is not disclosed or suggested in the prior art.
• FIG. 4 shows a film surface of one example of such a diffusion film of the present invention.
• the diffusion film 31 has many high-refractive-index regions 33 formed by being dispersed in the polymer film 32, and the high-refractive-index regions 33 of the parentheses are long and in a specific direction of the film. Oriented.
• the long axis of the long region of high refractive index 33 The direction is the x-axis direction of the film, and the short axis direction is the y-axis direction of the film.
• the inclination direction is preferably the y-axis direction.
• FIG. 5B shows a long region having a surface pattern as shown in FIG. 4 and being inclined at an angle of 0 (approximately 20 °) in the y-axis direction as shown in FIG. 5A (an aspect ratio of about 2: 1).
• FIG. 3 schematically shows the same scattering characteristics as in FIG. 2 for a diffusion film having 33.
• the long-axis direction of the high-refractive-index long region 33 is more than the short-axis direction. Due to the high light transmittance, the scattering characteristics of the light transmitted through the film show strong scattering in the y-axis direction as shown by the ellipse 34. This is a directional scattering characteristic in the y-axis direction more than when transmitted through a columnar structure. Even when the light enters from the normal direction of the film, the directional scattering characteristic 35 in the y-axis direction can still be exhibited.
• FIG. 5B also shows the transmission and scattering characteristics 38 of incident light from the directions of the first and second quadrants of the xy coordinate. These transmission scattering characteristics 38 also show strong scattered light intensity in the viewing angle direction (y-axis negative direction).
• the diffusion film is used as the display screen, the light (illumination light) from a wide angle in all directions except the back of the viewer, especially in the frontal direction, will have a columnar structure for the viewer. It is shown that the light is scattered and collected in the viewing angle direction (y-axis negative direction) more strongly than in the case. Furthermore, the transmission and scattering characteristics 39 in the viewing angle direction (negative y-axis direction) tend to be shorter in the y-axis direction. It can be interpreted as having high transmittance, and as described above, light selectively scattered and collected from all directions except behind the viewer is reflected by the reflective film and then reflected at the viewing angle without being scattered wastefully. It means to come. Therefore, this point also contributes to the improvement of the brightness of the reflection image.
• the columnar structure is inclined with respect to the film surface, but it is not necessary that the columnar structure be inclined, and the diffusion structure may be formed in the normal direction of the film. Les ,.
• FIG. 6B shows a diffusion film 4 in which a high refractive index region 43 is formed in a polymer film 42 in a surface pattern as shown in FIG. 4 and a columnar structure is formed in the normal direction of the film as shown in FIG. 6A.
• FIG. 1 schematically shows the same scattering characteristics as in FIG.
• the light vertically incident on the film has a higher light transmittance in the major axis direction of the ellipse than in the minor axis direction, as described above, so that the minor axis direction of the ellipse, that is, the y-axis direction of the film (in the figure)
• the light is scattered more in the right and left directions (transmitted light scattering characteristics 44).
• Light scattered in the y-axis direction in the direction inclined in the y-axis direction is less scattered in the y-axis direction than in the case of normal incidence, because it is obliquely incident on the columnar structure.
• the scattering characteristics show that the high refractive index region changes from a circular shape to an elongated shape, so that scattering in the viewing angle direction is large, especially incidence from the front to the viewer. Scattering characteristics 44 and 45 with high selective light scattering are obtained.
• the method for forming the columnar structure having a long cross-sectional shape in the diffusion film of the present invention is not particularly limited, and may be selected from all conventionally known methods. Although it can be adopted, a method of forming a columnar structure having a high refractive index by selectively irradiating a radiation sensitive polymer film with radiation is preferable.
• the polymer film may be a prepolymer or a monomer before the irradiation, and may be polymerized by heating or the like as necessary after the irradiation.
• Forming a columnar structure in the radiation-sensitive polymer film involves forming a layer serving as a mask on the surface of the radiation-sensitive polymer film, forming a long hole pattern in this mask layer, The irradiation can be performed by irradiating the radiation-sensitive polymer film with radiation at a predetermined angle through the hole pattern.
• a method of forming a mask is known by photolithography.
• the radiation-sensitive polymer film may be directly irradiated with radiation to form a radiation-sensitive area by scanning.
• a method may be used in which a polymer film is perforated with a laser beam or another method to fill the holes with a high refractive index material.
• the material of the radiation-sensitive polymer film that forms a high refractive index region upon irradiation is not particularly limited.
• those commercially available from DuPont as 0MNIDE X (registered trademark), HRF150, and HRF600 Can be used.
• the refractive index of the polymer film base material and the high refractive index region is not particularly limited in the present invention, and is determined in consideration of matching with other members such as an optical element to be used.
• a refractive index around 8 is preferably used. If it has a birefringent index, it is colored, which is not preferable. However, a birefringent index may be present as long as the application allows the birefringent index.
• the high molecular film base material and the high refractive index region itself have high light transmittance. The larger the difference between the refractive indices of the polymer film base material and the high refractive index region is, the more preferable it is. However, in general, the refractive index difference is set in the range of 0.05 to 0.2. If the refractive index difference is less than 0.05, it is not easy to obtain sufficient scattering characteristics. Preferably 0.005 to 0.1 Is within the range.
• the refractive indices of the polymer film base material and the high refractive index region may change abruptly at the interface between these two phases, but it is preferable that the refractive index change gradually so as to obtain desirable scattering characteristics.
• the dimension (dimension on the film surface) of the long high-refractive-index region formed in the diffusion film of the present invention is from several 100 nm to several 100 nm for both the short axis and the long axis in view of the relationship with the wavelength of light. / xm, preferably 5 O nm to 100 ⁇ m, especially 100 ⁇ ⁇ ! ⁇ 50 ⁇ . If this dimension is too large or too small, light will be transmitted and the desired scattering properties will not be obtained.
• the average dimension ratio (average aspect ratio) between the major axis and the minor axis of the cross section of the long high refractive index region formed in the diffusion film of the present invention is larger than 1: 1. However, it is usually selected from the range of 1.2: 1 to 10: 1, preferably within the range of 1.5: 1 to 5: 1, especially around 2: 1. If the average aspect ratio exceeds 10: 1, the scattering characteristics deteriorate.
• the shape of the long high refractive index region is preferably an ellipse, but may be a rectangle, a bar, an egg, or the like.
• the high refractive index region formed in the diffusion film of the present invention may include an equiaxial region, typically a circular region, together with the long region.
• the average of the cross section of the high refractive index region in a specific direction of the film is obtained. It is preferable that the dimensional ratio (average aspect ratio) between the long axis and the short axis is within the above range.
• the dimensions and the aspect ratio of the long high refractive index regions formed in the diffusion film of the present invention may be different for each long high refractive index region, or all may be the same. However, it is preferable to make the dimensions and the aspect ratio random because they have the effect of preventing moiré and improving the scattering characteristics.
• the elongated high refractive index region formed in the diffusion film of the present invention is characterized in that it is oriented in a specific direction of the film, but all the elongated high refractive index regions need to be oriented in the same direction. However, a desired scattering effect can be obtained if the particles are oriented on average.
• the inclination angle of the long high refractive index region formed in the diffusion film of the present invention with respect to the film having the columnar structure is generally in the range of 0 to 50 degrees, preferably in the range of 10 to 20 degrees. is there. As described above with reference to the drawings, it is preferable that the long high refractive index region be inclined from the normal direction of the film because the selective scattering and light condensing characteristics are excellent.
• the inclination angle of the long high refractive index region, that is, the inclination angle of the columnar structure is generally preferable from the viewpoint of scattering characteristics and also because it is easy to make the same in terms of the manufacturing method, but the inclination angle is different.
• the scattering characteristics can be roughly expressed by the average inclination angle, and the dispersion of the inclination angle makes the selective scattering light-condensing characteristic dependent on the viewing angle wider and the viewing angle. It may be desirable because it has the desired effect. Furthermore, a specific scattering characteristic may be obtained by intentionally combining long high refractive index regions with a columnar structure having two or more different inclination angles (for example, a cross shape).
• the thickness of the diffusion film of the present invention is not limited, but is generally in the range of about 2 tm to about 100 ⁇ .
• the diffusion film of the present invention is preferably useful as a diffusion film of a liquid crystal display device, particularly, a reflection type and a transflective type liquid crystal display device.
• FIG. 7 and 8 show examples of a liquid crystal display device.
• a liquid crystal layer 63 exists between the glass substrates 61, 65 on which the electrodes 62, 64 are formed, and the diffusion film 66 is generally disposed on the glass substrate 65 on the light incident side. (FIG. 7), or placed on the surface of the reflection film 67 below the glass substrate 61 on the light reflection side (FIG. 8).
• Use retarder 68 and polarizing film 69 In this case, it is generally installed outside the diffusion film 66 (not shown, but the same applies to FIG. 8).
• the diffusion films 66 may be disposed on both sides, and the configuration of the liquid crystal display device is not limited to the illustrated example.
• FIG. 9 shows an example in which the optical film of the present invention and a reflective polarizer are combined in a pack-light type liquid crystal display device.
• a reflective polarizer In order to use a reflective polarizer in a liquid crystal display device such as a mobile phone and a PDA, it is necessary to ensure brightness at the time of reflection. In the case of using a reflective polarizer, increasing the luminance at the time of transmission reduces the luminance at the time of reflection. In a liquid crystal display device such as a mobile phone and a PDA, an optical film functioning as a light diffusion film capable of realizing a bright image with excellent visibility even in both a transmission state and a reflection state is preferable.
• reference numeral 71 denotes a light diffusion film
• 72 denotes a reflective polarizer
• 73 denotes an acrylic adhesive
• 74 denotes a light guide plate
• 75 denotes a light source.
• Light from the light guide plate 74 is condensed by a BEF (light collecting sheet) (not shown) and is incident on the reflective polarizer 72. In the incident light, only the P wave is transmitted and the S wave is reflected by the reflective polarizer 72. Furthermore, it transmits the P wave of the light reflected by the BEF and reflects the S wave. By repeating this, the S wave is converted into a P wave, and the S wave that has not been used before can be used.
• BEF light collecting sheet
• the S film is cut by the polarizing film normally provided in the liquid crystal display device, but there is also the S wave that was conventionally cut by the polarizing film by using a reflective polarizer. Can be used effectively.
• it is not always necessary to use BEF for the pack light, and it is not necessary to use condensed light.
• the reflective polarizer has the function of the reflective film, its performance is slightly lower than that of a reflective film such as a total reflective film, but the reflective polarizer is sufficiently reflective. It can be used as a liquid crystal display device.
• the optical film of the present invention As shown in FIG. 10, by using the optical film of the present invention as a light diffusion film 76 and combining it with a conventionally known isotropic scattering light diffusion film 77, It is possible to obtain a liquid crystal display device having a bright direction and a wide viewing angle.
• the isotropic scattering light diffusion film does not have to be a film.
• an adhesive or a pressure-sensitive adhesive containing, for example, a spherical filler having a different refractive index from that of the base polymer is used.
• An adhesive may be used, and the optical film may be adhered or adhered to a reflective film, a glass substrate, or the like using the adhesive to form a light diffusing adhesive layer or an adhesive layer.
• a diffusion film as shown in FIGS. 4 and 5 is used, and as shown in FIG.
• the long axis direction of the long high refractive index area 8 3 is oriented in the left and right direction of the display screen 8 2 of the telephone 8 1, and the inclination of the columnar structure 8 3 is such that the end of the columnar structure film surface side is above the screen
• a viewer 86 views the mobile phone 81
• light entering from a wide range from above the viewer to above the viewer is reflected by the liquid crystal display element.
• the light can be selectively scattered, condensed and reflected mainly in the direction of the viewer 86.
• Such a scattered reflection characteristic is to improve the brightness of an image in the most frequent use mode when viewing a display screen of a mobile phone or the like.
• FIG. 12 shows another example of the liquid crystal display device of the present invention.
• the liquid crystal display device 91 includes a polarizing plate (see 69 in FIG. 7).
• the polarizing plate displays the direction 93 3 of the polarizing axis in the vertical direction 9 4 when viewed from the viewer of the display screen 92. It is often installed at an angle of 0 (eg, about 35 to 45 °) to the left or right.
• the scattering film of the present invention also has a long region (transverse cross section of a columnar structure) 95 in the short axis direction of the polarizing plate so that the scattering in the direction of the polarization axis is strong. It is desirable to set in the direction of the polarization axis. In this case as well, it is preferable that the alignment of the elongated region and the polarization axis be perfectly aligned, but it is sufficient if it is substantial.
• the characteristics described above are the same when the irradiation light is incident on the liquid crystal display device from the pack light, and therefore, a bright image with excellent visibility can be realized in both the transmission and reflection states. Further, as described above, when a reflective polarizer or an isotropic scattering light-diffusing film is used together with the light-diffusing film of the present invention, compared to the case where a conventional light-diffusing film is used in the front direction. Bright display images can be obtained And display with a wide viewing angle can be performed.
• the photosensitive polymer OMNIDEX, HRF600 manufactured by DuP0nt with a thickness of 50 ⁇ applied on a polyethylene terephthalate film 101, and the surface of the photosensitive polymer layer 102 is used. Then, a mask 103 having an elliptical hole pattern as shown in FIG. 4 was adhered by a hard contact method. However, the elliptical hole pattern of the mask has a major axis to minor axis ratio of 2: 1 and a major axis dimension of 500 ⁇ ⁇ ! The average was 2 / m within the range of 330 ⁇ m. The oval holes were oriented in the -axis direction.
• the irradiation time was from a few seconds to a few minutes. Thereafter, heat treatment was performed at 120 ° C. for 1 hour.
• a diffusion film having a high refractive index region having a cross-sectional structure according to the hole pattern of the mask and a columnar structure having a predetermined inclination angle with respect to the film normal direction was obtained.
• the refractive index of the polymer matrix in the diffusion film was 1.47, and the refractive index in the high refractive index region was 1.52.
• the transmission and scattering characteristics of the diffusion film thus obtained were made incident from one side of the diffusion film 105, and the optical detector 107 was placed on the opposite side of the film. It was arranged and the position of the light detector 107 was changed to determine the relationship between the direction and angle of the emitted light (the direction and angle with respect to the traveling direction of the incident light) and the transmitted light intensity. Also, the incident light The relationship between the direction and angle of the outgoing light (the direction and angle with respect to the traveling direction of the incident light) and the intensity of the transmitted light was similarly determined for each of the different incident directions and angles. The directions and angles of the incident light and the outgoing light are defined as described above with reference to FIGS.
• the obtained transmission scattering characteristics are shown in FIG. 5B.
• the major axis of the ellipse is the X-axis direction and the direction of incidence in the axis direction of the columnar structure is the positive y-axis direction, there is almost no scattering in the negative y-axis direction.
• the upper half of the light from the positive direction of the X axis to the negative direction of the X axis via the positive direction of the y axis has anisotropic scattering so that the scattering is concentrated in the front direction. For this reason, the incident light was efficiently converged on the front, and the front brightness was improved.
• Example 2 Diffusion film in the same manner as in Example 1 except that the same photosensitive polymer as in Example 1 was used, and a mask having an elliptical shape with a major axis ratio of 1.5: 1 was used and the light irradiation angle 0 was set to 20 degrees. It was created.
• Example 3 As in Example 1, the incident light could be efficiently condensed on the front.
• a diffusion film was prepared in the same manner as in Example 1 except that the same photosensitive polymer as in Example 1 was used, and a mask having an elliptical shape with a major axis ratio of 2: 1 was used and the light irradiation angle 0 was set to 10 degrees. did.
• Example 4 As in Example 1, the incident light could be efficiently condensed on the front.
• Example 2 The same photosensitive polymer as in Example 1 was used except that an elliptical mask having a major / minor axis ratio of 1.5: 1 was used and the light irradiation angle 0 was set to 10 degrees.
• a diffusion film was prepared in the same manner as in 1.
• Example 5 As in Example 1, the incident light could be efficiently condensed on the front.
• a diffusion film was prepared in the same manner as in Example 1 except that the same photosensitive polymer as in Example 1 was used except that an elliptical mask having a major axis ratio of 1.5: 1 was used, and the light irradiation angle 0 was 0 degree. Created.
• FIG. 6B shows the obtained transmission scattering characteristics. That is, light incident on the film surface from the elliptical minor axis direction (film y-axis direction) was scattered extending in the film y-axis direction. Light in this direction can efficiently converge light to the front.
• the point of the liquid crystal display of a small information device of a mobile phone is to efficiently condense light from the front, so the diffusion film of Example 5 can efficiently condense light in this direction.
• a diffusion film in which a high refractive index region having a columnar structure having a long cross section is formed in a polymer film, and anisotropic scattering occurs such that the scattering is concentrated on the front. This is effective, and furthermore, since the frontal viewing angle direction is transparent, when used as a diffusion film in a liquid crystal display panel or the like, the frontal luminance in the viewing angle direction is improved. Also provided are an optical element and a liquid crystal display device using a diffusion film having such an effect.

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• 2002
  • 2002-05-16 JP JP2003500607A patent/JP4317006B2/ja not_active Expired - Lifetime
  • 2002-05-16 CN CNB028102371A patent/CN1235066C/zh not_active Expired - Fee Related
  • 2002-05-16 WO PCT/JP2002/004749 patent/WO2002097483A1/ja active Application Filing
  • 2002-05-16 KR KR10-2003-7015620A patent/KR20040004671A/ko not_active Application Discontinuation
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