WO2003091794A1 - Systeme de convergence lumineuse et affichage a cristaux liquides de transmission - Google Patents
Systeme de convergence lumineuse et affichage a cristaux liquides de transmission Download PDFInfo
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- WO2003091794A1 WO2003091794A1 PCT/JP2003/004945 JP0304945W WO03091794A1 WO 2003091794 A1 WO2003091794 A1 WO 2003091794A1 JP 0304945 W JP0304945 W JP 0304945W WO 03091794 A1 WO03091794 A1 WO 03091794A1
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- layer
- liquid crystal
- film
- reflective polarizer
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Classifications
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- 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
- G02F1/1336—Illuminating devices
- G02F1/13362—Illuminating devices providing polarized light, e.g. by converting a polarisation component into another one
-
- 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
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
-
- 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
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members
- G02F1/133607—Direct backlight including a specially adapted diffusing, scattering or light controlling members the light controlling member including light directing or refracting elements, e.g. prisms or lenses
-
- 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
- G02F1/133634—Birefringent elements, e.g. for optical compensation the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
Definitions
- the present invention relates to a light collection system and a transmission type liquid crystal display device.
- Such as the selective reflection characteristics of a cholesteric liquid crystal using Bragg reflection and a vapor deposition type bandpass filter using Brewster's angle see, for example, German Patent Application Publication No. 3833695.
- optical films having an angle dependence with respect to transmittance and reflectance for example, Japanese Patent Application Laid-Open Nos. 2-158289, 6-235900, and There is known a technique of condensing a diffused light source in the front direction by using).
- the reflectance changes depending on the incident angle, and a filter that transmits light only to the front can be manufactured by appropriate optical design. Light that cannot be transmitted is reflected without being absorbed and returned to the light source side, recycled, and highly efficient light-collecting characteristics can be obtained.
- the parallel light of these systems can be designed to have high parallelism, and can be condensed and collimated in a narrow range of ⁇ 20 ° or less from the front direction. This is a difficult level for a conventional backlight system using a prism sheet and a microdot array alone.
- the shielding ratio of these light-collecting films was not perfect, and residual transmitted light in an oblique direction was observed. If the wavelength bandwidth to be shielded is narrow, secondary transmission appears in the oblique direction, which is wasted as a result of dropping in the oblique direction, and there are problems such as coloring due to the different transmittance for each wavelength. was there.
- a bright line condensing element that combines a band-pass filter and a bright line light source
- only the front needs to transmit the required bright line and shields the oblique direction, but there are three wavelengths that can be transmitted.
- the area that transmits green light is blue in front .
- blue light is transmitted by shifting to the bright line region.
- a region transmitting the red light is shifted to a green bright line region and the green light is transmitted.
- An object of the present invention is to provide a light-collecting system that can effectively block oblique dropouts, suppress unpleasant coloring, have good display, and reduce costs. .
- Still another object of the present invention is to provide a transmission type liquid crystal display device using the light collection system. Disclosure of the invention
- the present inventors have conducted intensive studies to solve the above problems, and as a result, have found the following transmissive liquid crystal display device, and have completed the present invention. That is, the present invention is as follows.
- a backlight system having a light source and a primary condensing part (X) capable of condensing light emitted from the light source within ⁇ 60 ° with respect to the front direction,
- a light-collecting system comprising a light-collecting film having no pattern structure as a secondary light-collecting element (Y).
- Microscope in which a backlight system with a primary concentrator (X) is combined with a light source.
- the light-condensing film used as the secondary light-condensing element (Y) does not have a pattern structure, when the light-condensing film is applied to a liquid crystal cell and optically observed from the front side (viewing side), 5.
- the light-collecting system according to any one of the above items 1 to 4, wherein a moiré or interference fringe does not occur with a regular pattern of another optical member.
- the light-condensing film used as the secondary light-condensing element (Y) has a retardation layer between at least two reflective polarizers (a) whose selective reflection wavelength bands overlap each other.
- the light-collecting system according to any one of the above items 1 to 5, wherein the light-collecting system is a polarizing element (A) in which (b) is arranged.
- the reflective polarizer (a) is a circularly polarized reflective polarizer (a 1) that transmits certain circularly polarized light and selectively reflects the opposite circularly polarized light,
- the phase difference layer (b) has a front phase difference (normal direction) of almost zero, and is incident on light incident at an angle of 30 ° or more with respect to the normal direction; )
- the reflective polarizer (a) is a linear polarization type reflective polarizer (a 2) that transmits one of the orthogonal linearly polarized light and selectively reflects the other, and
- the phase difference layer (b) has a front phase difference (normal direction) of substantially zero, and is incident on light incident at an angle of 30 ° or more with respect to the normal direction; On both sides of the retardation layer (b 1), there is a layer (b 2) having a front phase difference of about 4 between the linearly polarizing reflective polarizer (a 2) and the linearly polarizing reflective polarizer (a 2). ,
- the incident-side layer (b 2) is at an angle of 45 ° (—45 °) ⁇ 5 ° with respect to the polarization axis of the incident-side linear polarizer (a 2).
- the outgoing side layer (b 2) is at an angle of 45 ° (+ 45 °) ⁇ 5 ° with respect to the polarization axis of the outgoing side linear polarization type reflective polarizer 2).
- the incident side layer (b 2) and the outgoing side layer (b 2) have an arbitrary angle formed by their slow axes.
- the reflective polarizer (a) is a linear polarization type reflective polarizer (a 2) that transmits one of the orthogonal linearly polarized lights and selectively reflects the other, and
- the retardation layer (b) has two biaxial retardation layers (b 3) having a front retardation of approximately / 4 and an Nz coefficient of 2 or more,
- the angle of the slow axis of the incident side layer (b 3) is 45 ° (—45 °) ⁇ 5 ° with respect to the polarization axis of the linearly polarizing reflective polarizer (a 2) on the incident side.
- the direction of the slow layer axis of the output side layer (b 3) is 1 45 ° (+ 45 °) ⁇ 5 ° with respect to the polarization axis of the output side linear polarization type reflective polarizer (a 2). At an angle,
- the incident side layer (b 3) and the exit side layer (b 3) have an arbitrary angle between their slow axes
- the reflection polarizer (a) is a linear polarization type reflection polarizer (a 2) that transmits one of orthogonal linearly polarized lights and selectively reflects the other, and
- the retardation layer (b) has one biaxial retardation layer (b4) having a front retardation of approximately / 2 and an Nz coefficient of 1.5 or more,
- the slow axis direction of the incident side layer is at an angle of 45 ° (—45 °) ⁇ 5 ° with respect to the polarization axis of the linear polarization type reflective polarizer (a2) on the incident side.
- the direction of the slow axis of the layer on the emission side is at an angle of 1 45 ° (+ 45 °) ⁇ 5 ° with respect to the polarization axis of the linearly polarizing reflective polarizer (a 2) on the emission side.
- the polarization axes of the two linearly polarizing reflective polarizers (a 2) are substantially orthogonal
- the light-collecting film used as the secondary light-collecting element (Y) is a band-pass filter, and the light source has an emission line spectrum. Light collection system.
- the band-pass filter is a band-pass filter composed of a multilayer laminated extruded base material of resin materials having different refractive indices.
- the band-pass filter is a band-pass filter made of a multilayer thin film precision coating film of resin materials having different refractive indexes.
- a liquid crystal cell through which the collimated light passes
- the above-mentioned condensing system converges the light emitted from the light source with a primary condensing part (X) within ⁇ 60 ° with respect to the front direction, and condenses the light more than the primary condensing part (X).
- a secondary light-collecting element ( ⁇ ) with a strong aperture, the transmission component at large angles can be dramatically reduced, and unpleasant coloring can be eliminated.
- a secondary condensing element ( ⁇ ) combining an emission line type light source and an interference filter
- the second-order transmission of the secondary light-collecting element (Y) using the polarizing element (A) that combines the polarizer (a) and the retardation layer (b) occurs at a large angle when viewed from the normal direction. Therefore, in the present invention, as shown in Figs. 11 and 12, a condensing system combining a backlight system (BLS) with a primary condensing part (X) and a secondary condensing element (Y) Yes.
- the primary condensing part (X) is provided separately from the light source (L).
- the primary concentrator (X) is integrated into the light source (L) to form a backlight (BLS).
- BSS backlight
- the primary condensing part (X) the light emitted from the light source is partially and partially condensed, and the incident light from a large oblique angle is reduced.
- the secondary light-collecting element (Y) is less susceptible to the leaked light in the area where the shielding ability is insufficient, and it is possible to reduce unpleasant coloring in an oblique direction.
- the secondary focusing by the secondary focusing element (Y) it is possible to further narrow down the partially condensed light in the highly parallel region near the front to obtain high-purity parallel light.
- FIGS. 13 and 14 show transmissive liquid crystal display devices using the light-collecting systems of FIGS. 11 and 12 described above.
- Polarizers (PL) are arranged on both sides of the liquid crystal cell (LC).
- the light collection system is arranged such that the secondary light collection element (Y) is on the liquid crystal cell (LC) side.
- the secondary light-collecting element (Y) is bonded to the liquid crystal cell (LC).
- the conventional primary light condensing means has a pattern structure, and the light can be condensed within a range of about ⁇ 50 °.
- the secondary focusing means was sharply stopped down, but leakage of secondary peaks was observed.
- the primary light collection required for the primary light collection part (X) is within ⁇ 60 °, more preferably within 50 ° of the earth.
- the secondary transmission of the light-collecting film used as the secondary light-collecting element (Y) is generally 60 to 70. Because it appears in By combining a light source that does not substantially generate an outgoing light beam at an angle at which the secondary transmission component occurs, the secondary transmission can be effectively blocked, and it can be out of the display viewing angle range originally required for the secondary transmission. The emitted light can be efficiently reused.
- the graph shown in Fig. 21 shows the structure of Fig. 15 with the cholesteric liquid crystal bandpass filter described in the examples as the secondary light-collecting element (Y).
- FIG. 1 is a conceptual diagram showing an example of the basic principle of making the polarizing element (A) parallel light.
- FIG. 2 illustrates the state of each light beam shown in FIGS. 3, 4, 6, and 8.
- FIG. 3 is a conceptual diagram showing the conversion of linearly polarized light into circularly polarized light.
- FIG. 4 is a conceptual diagram showing an example of a basic principle of parallel light shading of the polarizing element (A).
- FIG. 5 is an example showing an arrangement angle of each layer of the parallel light beam using the linear polarization type reflection polarizing element (a 2).
- FIG. 6 is a conceptual diagram showing an example of the basic principle of the parallel light of the polarizing element (A).
- FIG. 7 is an example showing an arrangement angle of each layer of the parallel light conversion using the linear polarization type reflection polarizing element (a 2).
- FIG. 8 is a conceptual diagram showing an example of the basic principle of the parallel light conversion of the polarizing element (A).
- FIG. 9 is an example showing an arrangement angle of each layer of the parallel light conversion using the linear polarization type reflection polarization element (a 2).
- FIG. 10 is a conceptual diagram showing a direct moire solution.
- FIG. 11 is an example of a schematic diagram of the light collection system of the present invention.
- FIG. 12 is an example of a schematic diagram of the light collection system of the present invention.
- FIG. 13 is an example of a schematic view of a transmission type liquid crystal display device of the present invention.
- FIG. 14 is an example of a schematic view of a transmission type liquid crystal display device of the present invention.
- FIG. 15 is a schematic diagram of a transmissive liquid crystal display device when the light-collecting characteristics of the secondary light-collecting element (Y) alone in Examples 1 and 2 were measured.
- FIG. 16 is a schematic diagram of the transmission type liquid crystal display devices of Examples 1 and 2.
- FIG. 17 shows the light-collecting characteristics measured by the secondary light-collecting element (Y) alone in Example 3.
- FIG. 3 is a schematic view of a transmission type liquid crystal display device when the display is performed.
- FIG. 18 is a schematic diagram of a transmission type liquid crystal display device of Example 3.
- FIG. 19 is a schematic diagram of a transmission type liquid crystal display device when the light-collecting characteristics of the secondary light-collecting element (Y) alone were measured in Example 4.
- FIG. 20 is a schematic diagram of a transmission type liquid crystal display device of Example 4.
- FIG. 21 is a graph showing the light-collecting characteristics of the secondary light-collecting element (Y) of Example 2 alone.
- FIG. 22 is a graph illustrating a wavelength characteristic of the secondary light-collecting element (Y) of the first embodiment.
- FIG. 23 is a graph showing light-collecting characteristics of the secondary light-collecting element (Y) of Example 1 alone.
- FIG. 24 is a graph showing light-collecting characteristics when the backlight system having the primary light-collecting portion (X) and the secondary light-collecting element (Y) according to the first embodiment are combined.
- FIG. 25 is a graph illustrating a wavelength characteristic of the secondary light-collecting element (Y) according to the second embodiment.
- FIG. 26 is a graph showing the light-collecting characteristics when the backlight system having the primary light-collecting portion (X) and the secondary light-collecting element (Y) in Example 2 are combined.
- FIG. 27 is a graph showing the wavelength characteristics of the secondary light-collecting device (Y) of Example 3.
- FIG. 28 is a graph showing light collecting characteristics when the backlight system having the primary light collecting portion (X) and the secondary light collecting element (Y) in Example 3 are combined.
- FIG. 29 is a graph illustrating a wavelength characteristic of the secondary light-collecting element (Y) of the fourth embodiment.
- FIG. 30 is a graph showing the light-collecting characteristics when the backlight system having the primary light-collecting portion (X) and the secondary light-collecting element (Y) in Example 4 are combined.
- the light collection system of the present invention has a backlight system having a light source (L) and a partial light collection part (X).
- a light source either a direct type backlight or a side type backlight can be adopted.
- the side-type backlight has a light guide plate.
- the primary condensing part (X) may be arranged on the light source (L) or may be incorporated in the light source (L).
- the primary condensing part (X) is, for example, a micro prism sheet array.
- a microprism processed light guide combined with a light source a microdot processed light guide combined with a light source, and the like can be given. These can be combined.
- a knock light system having a primary condensing part (X) for example, a microprism array and a microdot array are engraved on the surface of a wedge-shaped light guide, and the range of emitted light is narrowed to the vicinity of the front.
- a light guide plate having high directivity and a backlight system in which emitted light is narrowed in the front direction by a microprism sheet are preferably used.
- the backlight system having the primary condensing portion (X) is not particularly limited as long as it has a characteristic of condensing the light emitted from the light source within ⁇ 60 ° with respect to the front direction. Therefore, if the backlight system having the primary condensing part (X) has the above-described condensing characteristics, the prism condensing part which becomes the light source, the light guide plate, and the primary condensing part (X)
- the material and the like of the sheet and the like are not particularly limited, and the arrangement and the like can be appropriately set.
- the backlight system having the secondary light condensing part (X) determines whether or not the backlight system having the secondary light condensing part (X) has the characteristic of condensing the emitted light from the light source within ⁇ 60 ° with respect to the frontal direction, as follows: Is determined. That is, for a backlight system having a secondary light-collecting part (X), the light-collecting characteristics are measured in the same manner as described above (however, the primary light-collecting part ( ⁇ ) is used instead of the secondary light-collecting element ( ⁇ )). X)).
- the light-collecting film used as the secondary light-collecting element ( ⁇ ) has no pattern structure. Since the light-condensing film has no pattern structure, when the light-condensing film is applied to a liquid crystal cell and optically observed from the front side (viewing side), the light-condensing film will not have the regular pattern of other optical members. Does not generate moiré interference fringes.
- the light-condensing film used as the secondary light-condensing element ( ⁇ ) is optically observed from the front side (viewing side), it is determined whether or not regular patterns of other optical members and moiré interference fringes are generated.
- a polarizing plate is attached to both sides of a liquid crystal cell (TFT—liquid crystal display cell), and the light-collecting film is attached to a member attached to the backlight side. Then, it can be determined by rotating the member and visually observing it.
- the material of the light-condensing film used as the secondary light-condensing element ( ⁇ ) is not particularly limited.
- a bandpass filter is used as the til self-condensing film.
- the light-collecting film may include a retardation layer (a) between at least two reflective polarizers (a) in which the wavelength bands of selective reflection of polarized light overlap each other.
- the polarizing element (A) in which b) is disposed can be used. Both of these are optical systems in which secondary transmission occurs near 60 to 70 °, but the structure of the present invention can prevent secondary transmission.
- the band-pass filter examples include a vapor-deposited multilayer film band-pass filter, a cholesteric liquid crystal band-pass filter, a band-pass filter composed of a multilayer laminated extruded base material of resin materials having different refractive indexes, and a band-pass filter composed of a stretched base material.
- a band pass filter made of a multilayer thin film precision coated film of a different resin material is preferably used.
- the polarizing element (A) will be described.
- the present invention will be described below with reference to an ideal model for the mechanism of simultaneously exhibiting the light-collecting property and the improvement in brightness when the polarizing element (A) is used.
- FIG. 1 is an explanatory view showing the principle when a circularly polarizing reflective polarizer (a 1) is used as the reflective polarizer (a).
- a circularly polarizing reflective polarizer (a 1) As the polarizing element (A), a circularly polarizing reflective polarizer (a 1), a retardation layer (b 1), and a circularly polarizing reflective polarizer (a 1) are arranged from the backlight side (lower side). They are arranged in this order.
- the operating principle is as described in 1) to 3).
- Circularly polarized reflective polarizer (a1) which separates polarized light by reflection, separates incident light into transmitted light and reflected light according to the direction of polarization. Therefore, there is no absorption loss.
- Incident light rays in oblique directions are not absorbed but returned as reflected light.
- the reflected light is repeatedly reflected until it becomes a transmitted light ray.
- the retardation plate (b 1) used here is a negative C plate (negative retardation plate) or Also commonly referred to as a positive c-plate (positive retarder). These retardation plates (b1) have a property that the phase difference is close to 0 in the vertical direction (normal direction) and a phase difference occurs when tilted.
- Typical negative C plates are, for example, a biaxially stretched polycarbonate film, polyethylene terephthalate film, or a cholesteric liquid crystal film or disc with a selective reflection wavelength band shorter than visible light. Examples thereof include a film obtained by aligning a tic liquid crystal in parallel with a plane, and a film obtained by in-plane aligning an inorganic crystal compound having a negative retardation.
- a typical positive C plate is, for example, a liquid crystal film having a homeotropic aperture.
- Circularly polarized reflective polarizers (a1) mainly align cholesteric liquid crystals and adjust the twist pitch so that the selective reflection wavelength band covers the visible light region / light source emission wavelength band (for example, the selective reflection center).
- a stack of a plurality of films having different wavelengths or a single layer in which the pitch is changed in the thickness direction is fixed.
- the circularly polarizing reflective polarizer (a1) arranged on both sides of the phase difference plate (b1) in FIG. 1 those having the same direction of transmitted circularly polarized light are preferably used.
- the circularly polarizing reflective polarizer (a 1) and the retardation layer (b 1) can be used without specifying the bonding direction because there is almost no axis in the in-plane direction. For this reason, the narrowing angle range of the parallel light conversion has isotropic / symmetric characteristics.
- the one that is perpendicularly incident on the circularly polarized reflective polarizer (a 1) is polarized and separated into transmitted light (r 3) and reflected light (r 2). It is.
- the directions of rotation of the transmitted light and the reflected light are opposite to each other.
- the transmitted light (r4) passes through the circularly-polarized reflection polarizer (a1).
- the transmitted light (r5) is used for a liquid crystal display device disposed thereon.
- the transmitted light (r 8) is affected by the phase difference when passing through the phase difference layer (b ⁇ ). Given a phase difference value of one or two wavelengths, the circularly polarized light turns in the opposite direction and becomes the opposite direction. Therefore, the transmitted light (r 8) rotates through the phase difference layer (b 1) and then reverses its rotation.
- the transmitted light (r9) is emitted with its rotation inverted due to the phase difference.
- the reflected light (r10) is affected by the phase difference when passing through the phase difference layer (b1)
- the reflected light (r2, r7, ⁇ 12) returns to the backlight side and is recycled. These return light rays are repeatedly reflected by a diffuser placed in the backlight while randomly changing the direction of travel and the direction of polarization until they become light rays that can pass through near the normal direction of the polarizing element ( ⁇ ⁇ ). Contribute to improvement.
- the transmitted circularly polarized light (r5) can be converted into linearly polarized light by disposing the IZ4 plate, and can be used without causing absorption loss in the liquid crystal display device.
- the wavelength characteristic of the transmitted light shifts to the shorter wavelength side with respect to the obliquely incident light. Obedience Therefore, it is necessary to have sufficient polarization characteristics / phase difference characteristics on the long wavelength side outside the visible light range in order to function sufficiently for light rays incident at a deep angle.
- the retardation layer (b 1) used should have exactly a half-wave retardation in the oblique direction.
- the polarizer (a 1: cholesteric liquid crystal layer) has some properties as a negative retardation plate. Therefore, in order to obtain the function of the present invention, the optical function can be exhibited if the retardation layer (b1) has a retardation of about 1/8 wavelength or more in the oblique direction.
- the reflection polarizer (a) is a linear polarization type reflection polarizer (a 2)
- a C plate phase difference layer (b 1)
- the optical axis for a light beam incident on the C-plate obliquely is always orthogonal to the light beam direction. Therefore, no phase difference is exhibited and no polarization conversion is performed. Therefore, when using a linear polarization type reflection polarizer (a 2), the angle of 45 ° or 1 45 ° with respect to the polarization axis of the linear polarization type reflection polarizer (a 2) on both sides of the C plate. It has a slow axis direction; 1/4 plate (b 2) is arranged.
- the linearly polarized light is converted into circularly polarized light by the ⁇ plate (b 2), and then converted into inverse circularly polarized light by the phase difference of the C plate, and the circularly polarized light is again converted into the 1 plate (b 2).
- FIG. 3 is a conceptual diagram in which natural light is polarization-separated into linearly polarized light by a linearly polarized reflective polarizer (a 2), and is further converted into circularly polarized light by a quarter plate (b 2).
- FIG. 4 is a conceptual diagram when a linear polarization type reflection polarizer (a2) is used as the reflection polarizer).
- a linear polarization type reflective polarizer (a 2), a quarter-wave plate (b 2), a retardation layer (b 1), A / 4 plate (b 2) and a linear polarization type reflective polarizer (a 2) are arranged in this order.
- FIG. 5 is an example of a bonding angle of each film in the parallel light mirror system shown in FIG.
- the double-headed arrow shown on the linearly polarized reflective polarizer (a 2) is the polarization axis
- the double-headed arrow shown on the quarter-wave plate (b 2) is the slow axis.
- the angle formed by the axis of the 1/4 plate (b 2) on the incident side and the exit side is arbitrary.
- C plate The retardation layer (b1) can be placed without specifying the angle because there is no axial direction in the plane.
- the linearly polarized reflective polarizer (a2) transmits linearly polarized light (r15) and reflects linearly polarized light (r16) in the orthogonal direction.
- Circularly polarized light (r17) passes through the retardation layer (b1).
- Circularly polarized light (r 18) is transmitted through the L / 4 plate (b 2) and converted to linearly polarized light (r 19).
- the linearly polarized light (r 19) passes through the linearly polarized reflective polarizer (a 2).
- the linearly polarized light O 20) enters the liquid crystal display device disposed thereon and is transmitted without loss.
- part of the natural light (r 21) supplied from the backlight is obliquely incident on the linear polarization type reflective polarizer (a 2).
- the linearly polarized reflective polarizer (a 2) transmits linearly polarized light (r 2 2) and reflects linearly polarized light (r 2 3) in the orthogonal direction.
- the linearly polarized light (r2 2) passes through the / 4 plate (b2) and is converted to circularly polarized light (r24).
- the circularly polarized light (r 24) receives a phase difference of ⁇ wavelength and the rotation is reversed.
- the linearly polarized light (r26) is reflected by the linearly polarized reflective polarizer (a2) and becomes linearly polarized light (r27).
- W linearly polarized light
- the linearly polarized light (r27) is transmitted through the quarter-plate (b2) and converted to circularly polarized light (r28).
- the circularly polarized light ⁇ 28 receives a phase difference of ⁇ wavelength and the rotation is reversed.
- the inverted circularly polarized light (r29) passes through the Z4 plate (b2) and is converted into linearly polarized light (r30).
- the linearly polarized light (r 30) passes through the linearly polarized reflective polarizer (a 2).
- the angle between the slow axis of the / 4 plate (b 2) and the polarization axis of the linear polarization type reflective polarizer (a 2) is 45 °.
- the characteristics of the actual linearly polarized reflective polarizer (a2) and the 1/4 plate (b2) are not perfect in the visible light range, and there are subtle changes for each wavelength. When disregarding this and laminating at 45 °, coloring may be observed.
- the transmittance and reflectivity of the linearly polarized reflective polarizer (a2) are such that the wavelength characteristic of the transmitted light shifts to the shorter wavelength side with respect to the incident light in the oblique direction. Same as polarizer (a 1). Therefore, it is necessary to have sufficient polarization characteristics / phase difference characteristics on the long wavelength side outside the visible light range in order to function sufficiently for light rays incident at a deep angle.
- the linear polarization type reflection polarizer (a 2) has a smaller negative phase difference characteristic than the cholesteric liquid crystal. Therefore, the phase difference in the oblique direction (30 ° inclination) of the retardation layer (b 1) used sandwiched between the linear polarization type reflection polarizers 2) is the same as the circular polarization type reflection polarizer (a 1) using a cholesteric liquid crystal. ) Is slightly larger than that in the case of), and is preferably 1/4 wavelength or more.
- the reflection polarizer (a) is a linear polarization type reflection polarizer (a 2)
- the two L / 4 plates (b 2) and the C plate the retardation layer (b 1 )
- the two biaxial retardation layers (b 3) having a front retardation of approximately 1/4 and a thickness retardation of approximately ⁇ / 2 or more are similarly arranged. 3 ⁇ 4The effect can be obtained.
- Such a biaxial retardation layer (b3) satisfies the above requirements if the Nz coefficient is 2 or more.
- FIG. 6 is a conceptual diagram in a case where a linear polarization type reflection polarizer (a 2) is used as the reflection polarizer (a) and a biaxial retardation layer (b 3) is used.
- a linear polarization type reflection polarizer (a 2) is used as the reflection polarizer (a) and a biaxial retardation layer (b 3) is used.
- a linear polarization type reflective polarizer (a2) is arranged in order.
- FIG. 7 is an example of a bonding angle of each film in the parallel light mirror system shown in FIG.
- the double-headed arrow shown in the linear polarization type reflection polarizer (a 2) is the polarization axis
- the double-headed arrow shown in the retardation layer (b 1) is the slow axis.
- the polarization axis of the linear polarization type reflection polarizer (a 2) and the slow axis of the biaxial retardation layer (b 3) are arranged at an angle of 45 ° ( ⁇ 45 °) ⁇ 5 °. These threads are shown as set 1 and set 2 respectively.
- the polarization axes of the upper and lower linear polarization type reflection polarizers 2) are parallel, and the slow axes of the biaxial retardation layer (b3) are orthogonal.
- the angle formed by the slow axes of the upper and lower biaxial retardation layers (b3) is arbitrary. If the angle between the polarization axis of the linear polarization type reflective polarizer (a 2) and the slow axis of the biaxial retardation layer (b 3) is maintained at 45 ° (—45 °), set 1 , Set 2 may be rotated.
- the linear polarization type reflective polarizer (a2) transmits linearly polarized light (r33) and reflects linearly polarized light (r34) in the orthogonal direction.
- the linearly polarized light (r33) passes through two biaxial retardation layers (b3) having a front phase difference of about 1/4 wavelength.
- the front and rear biaxial retardation layers (b 3) have zero front phase difference because their slow axes are orthogonal to each other at 90 °. Therefore, the linearly polarized light (r35) passes through.
- Linearly polarized light passes through the linearly polarized reflective polarizer (a2).
- 5 Linearly polarized light enters the liquid crystal display and is transmitted without loss.
- part of the natural light (r37) supplied from the backlight is obliquely incident on the linear polarization type reflective polarizer (a2).
- the linearly polarized reflective polarizer (a 2) transmits linearly polarized light (r 38) and reflects linearly polarized light (r 39) in the orthogonal direction.
- the linearly polarized light (r38) is obliquely incident on the two biaxial retardation layers (b3). Since the biaxial retardation layer (b 3) has a front retardation of 1/4 wavelength and an Nz coefficient of 2 or more, the biaxial retardation layer (b 3) Linearly polarized light transmitted through
- the linearly polarized light (r40) enters the linearly polarized reflective polarizer (a2).
- the linearly polarized light (r42) passes through the linearly polarized reflective polarizer (a2).
- the reflected light (r34, ⁇ 39, r43) is returned to the backlight side and recycled.
- the polarizing element (A) shown in FIGS. 6 and 7 has a biaxial retardation layer (b 3) with a front phase difference of approximately 1/4 wavelength and an Nz coefficient of 2 or more.
- a C-plate is sandwiched between two 1/4 plates (b2): a three-layer laminate with a retardation layer (b1) sandwiched between them Almost the same characteristics can be generated. Therefore, the number of layers is smaller than that of the polarizing element (A), and the productivity is slightly better.
- the angle between the slow axis of the retardation layer (b 3) described here and the polarization axis of the linear polarization type reflective polarizer 2) is 45 ° in theory in an ideal system
- the characteristics of the actual linear polarization type reflective polarizer (a 2) and retardation layer (b 3) are not perfect in the visible light range, and there are subtle changes for each wavelength. When disregarding this and laminating at 45 °, coloring may be observed. Therefore, if the color is compensated by slightly changing the angle, the whole system can be optimized rationally. On the other hand, if the angle deviates greatly, other problems such as a decrease in transmittance occur. Therefore, in practice, it is desirable to limit the adjustment to a range of about 5 °.
- the transmittance and reflectivity of the linear polarization type reflection polarizer (a2) are such that the wavelength characteristic of the transmitted light shifts to the shorter wavelength side with respect to the incident light in the oblique direction. Same as polarizer (a 1). Therefore, it is necessary to have sufficient polarization characteristics / phase difference characteristics on the long wavelength side outside the visible light range in order to function sufficiently for light rays incident at a deep angle.
- the retardation layer (b) When the reflective polarizer (a) is a linearly polarized reflective polarizer 2), the retardation layer (b) has a front phase difference of approximately 1/2 and a thickness direction retardation of 1 / The same effect can be obtained by arranging a biaxial retardation layer (b4) having two or more layers. Such a biaxial retardation layer (b4) satisfies the above requirements if the Nz coefficient is 1.5 or more.
- FIG. 8 is a conceptual diagram in the case where a linear polarization type reflection polarizer (a 2) is used as the reflection polarizer (a) and a biaxial retardation layer (b 4) is used.
- a linear polarization type reflection polarizer (a 2) is used as the reflection polarizer (a) and a biaxial retardation layer (b 4) is used.
- a linear polarization type reflection polarizer (a 2) from the backlight side (lower side
- a biaxial retardation layer (b 4) a linear polarization type reflection polarizer
- FIG. 9 is an example of a bonding angle of each film in the parallel light conversion system shown in FIG.
- the double-headed arrow shown in the linear polarization type reflective polarizer (a 2) is the polarization axis
- the rain arrow shown in the retardation layer (b 4) is the slow axis.
- the polarization axes of the upper and lower linear polarization type reflection polarizers (a 2) are arranged substantially orthogonally.
- the slow axis of the biaxial retardation layer (b 4) and the polarization axis of the linear polarization type reflective polarizer (a 2) are arranged at an angle of 45 ° ( ⁇ 45 °) ⁇ 5 °.
- the linear polarization type reflective polarizer (a2) transmits linearly polarized light (r48) and reflects linearly polarized light (r49) in the orthogonal direction.
- Linearly polarized light (r48) is a biaxial retardation layer with a front retardation of approximately 1/2 wavelength (b4) And is converted to linearly polarized light (r50), and the direction of the polarization axis is rotated by 90 °.
- the transmitted linearly polarized light (r51) enters the liquid crystal display and is transmitted without loss
- the linearly polarized reflective polarizer (a 2) transmits linearly polarized light (r 53) and reflects linearly polarized light (r 54) in the orthogonal direction.
- the linearly polarized light (r53) is obliquely incident on the biaxial retardation layer (b4). Since the biaxial retardation layer (b 4) has a front retardation of approximately ⁇ wavelength and an Nz coefficient of 2 or more, the direction of the polarization axis is linearly polarized (r 5 3 The light is transmitted with the linearly polarized light (r55) in the same state as in ()).
- the reflected light (r56) enters the retardation layer (b4). This also transmits without changing the axial direction.
- the transmitted linearly polarized light (r57) passes through the linearly polarized reflective polarizer (a2) to become linearly polarized light (r58).
- the reflected light (r49, r54, r58) is returned to the backlight side and recycled.
- the polarizer (A) shown in FIGS. 8 and 9 has a front phase difference of about 1/4 wavelength and a biaxial phase difference layer (b 4) having an Nz coefficient of 1.5 or more.
- a biaxial phase difference layer (b 4) having an Nz coefficient of 1.5 or more.
- two plates are arranged; C plate is sandwiched by 1/4 plate (b2): three-layer laminate with a structure in which a retardation layer (b1) is sandwiched Almost the same characteristics can be generated as in the case of using. Therefore, the number of layers is smaller than that of the polarizing element (A), and the productivity is slightly better. Furthermore, the productivity is higher than when using a two-layer laminate as shown in FIGS.
- the angle between the slow axis of the retardation layer (b 4) described here and the polarization axis of the linear polarizing reflective polarizer (a 2) is 45 °.
- the characteristics of the linear polarization type reflection polarizer (a 2) and the retardation layer (b 4) are not perfect in the visible light range, and there are subtle changes for each wavelength. If this is ignored and laminated at 45 °, coloring may be observed.
- the transmittance and reflectivity of the linear polarization type reflective polarizer (a 2) are as follows.
- the point that the wavelength characteristic of the transmitted light shifts to the shorter wavelength side with respect to the incident light in the oblique direction is a circularly polarized light using a cholesteric liquid crystal.
- the polarizing element (A) converts a light beam incident at an incident angle of 30 ° from the normal direction into an axially polarized light reflected by two reflective polarizers).
- the polarizing element (A) has a total reflection function at an incident angle of 30 °, and does not transmit light near the incident angle of 30 °.
- the polarizing element (A) has a high transmittance in the range of about 15 to 20 ° from the normal direction, and light rays having an incident angle higher than that are reflected and reused. For this reason, the transmitted light from the light source is concentrated in the above range, and is condensed and parallelized.
- the collimated backlight thus obtained is thinner than the conventional technology, and has a feature that a light source with high parallelism can be easily obtained.
- the light is parallelized by polarized light reflection, which has essentially no absorption loss, the reflected non-parallel light component returns to the backlight side, is scattered and reflected, and is recycled, in which only the parallel light component is extracted. Repeatedly, substantially high transmittance and high light use efficiency can be obtained.
- the phase difference anisotropy control type parallel light means used in the present invention is used for liquid crystal pixels, black matrices, and parallel light means without observing the in-plane fine structure when viewed from the surface direction by optical observation. There is no interference with the film having a fine structure, the outermost surface of the liquid crystal display device such as the gray-treated surface, and it has features that do not cause moiré.
- Moiré as shown in Figure 10, is a light and shade pattern that has a lower frequency than the grid that is visible when grids formed in different layers are superimposed at an angle.
- the pitch of the stripe is
- Equation 1 S 1 is the first grating pitch, S 2 is the second grating pitch, S 3 is the moire fringe pitch, and a is the angle between the first and second gratings.
- the angle of light emitted from the light guide plate is about 60 ° from the normal direction.
- the amount of blue shift at this angle extends to about 100 nm. Therefore, when a 3-wavelength cold cathode tube is used for the backlight, the selective reflection wavelength must reach at least the longer wavelength side than 710 nm because the red emission line spectrum is 61 O nm. I understand.
- the selective reflection wavelength bandwidth required on the long wavelength side largely depends on the angle and wavelength of the incident light beam from the light source, so the long wavelength end is arbitrarily set according to the required specifications. ⁇
- the backlight light source emits only a specific wavelength, for example, in the case of a colored cold-cathode tube, it is sufficient that only the obtained bright line can be shielded. Also, if the light emitted from the backlight is narrowed down from the beginning to some extent from the beginning due to the design of microlenses ⁇ dots and prisms processed on the surface of the body, transmitted light at a large incident angle can be ignored. It is not necessary to extend the selective reflection wavelength to a longer wavelength side.
- Combination members ⁇ Can be designed appropriately according to the type of light source. From this point of view, the reflective polarizers (a) may be in exactly the same combination, or one may have reflection at all visible light wavelengths and the other may partially reflect.
- the circular polarization type reflective polarizer (a 1) for example, a cholesteric liquid crystal material is used.
- the selective reflection wavelength shifts by one, so the overlapping wavelength region is preferably wider.
- the circularly polarized reflective polarizer (a 1) is a cholesteric material. (Right-handed and left-handed) in the same way, the front phase difference can be obtained in the same way; if tilted by 1/2, the same polarizer can be obtained if the phase difference is zero or, but the tilt angle of the tilting axis This is not preferable because problems such as anisotropy and coloring are caused. From this point of view, combinations of the same type (right-twisted, left-twisted) are preferred. However, coloring can also be suppressed by canceling out the combination of cholesteric liquid crystal molecules at the top and bottom or those with different wavelength dispersion characteristics of the C plate. it can.
- the cholesteric liquid crystal constituting the circular polarization type reflective polarizer (a 1) an appropriate one may be used, and there is no particular limitation.
- a liquid crystal polymer that exhibits cholesteric liquid crystallinity at high temperatures or a polymerizable liquid crystal obtained by polymerizing a liquid crystal monomer and, if necessary, a chiral agent and an alignment aid by irradiation with ionizing radiation such as electron beams or ultraviolet rays or heat, or And mixtures thereof.
- the liquid crystal properties may be either lyotropic or thermotropic. However, from the viewpoints of easy control and low formation of monodomain, it is desirable that the liquid crystal be a liquid crystal having a single mouth opening.
- the cholesteric liquid crystal layer can be formed by a method according to a conventional alignment treatment.
- a support substrate such as triacetyl cellulose or amorphous polyolefin, which has a birefringence retardation as small as possible.
- Polyester, polyarylate, polyamide Doimi de alignment film was rubbed with a rayon cloth to form a film such as polyether imide or S i 0 2 obliquely vapor sealable layer, or polyethylene terephthalate, polyethylene naphthalate,
- a substrate that uses the surface properties of an extended substrate, such as a base material, as an alignment film, or the surface of the above-mentioned substrate is treated with a fine abrasive such as rubbing cloth or bengaler, and has a fine alignment regulating force on the surface.
- the liquid crystal is formed on an appropriate alignment film composed of a base material having fine irregularities formed thereon, or a base material having an alignment film which generates a liquid crystal regulating force by light irradiation such as an azobenzene compound on the base film.
- the polymer is developed and heated to a temperature equal to or higher than the glass transition temperature and lower than the isotropic phase transition temperature.
- Las state the orientation Nadogaa be up method of forming a solidified layer that has been immobilized.
- the structure may be fixed by irradiating energy such as ultraviolet rays or ion beams at the stage when the alignment state is formed.
- the substrate having a small birefringence may be used as it is as a liquid crystal layer support. If the birefringence is large or the requirement for the thickness of the polarizing element (A) is severe, the liquid crystal layer can be separated from the alignment base material and used appropriately.
- a solution of a liquid crystal polymer in a solvent is spin-coated, roll-coated, flow-coated, printed, dip-coated, cast-film, vacuum-coated, gravure printing, etc. It can be carried out by a method of developing a thin layer with the above, and further drying it as necessary.
- the solvent include chlorinated solvents such as methylene chloride, trichloroethylene and tetrachloroethane; ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone; aromatic solvents such as toluene. Ring like cycloheptane ⁇ ! Dog alkanes; or N-methylpyrrolidone tetrahydrofuran and the like can be used as appropriate.
- a method in which a heated melt of a liquid crystal polymer, preferably a heated melt in a state exhibiting an isotropic phase, is developed in accordance with the above, and, if necessary, is further developed into a thin layer and solidified while maintaining the melting temperature. can do.
- This method is a method that does not use a solvent, and therefore the liquid crystal polymer can be spread even by a method with good hygiene of the working environment.
- the aim was to reduce the thickness If necessary, a method of superposing a cholesteric liquid crystal layer via an alignment film can be employed.
- these optical layers can be separated from the supporting base material / alignment base material used at the time of film formation and transferred to another optical material for use.
- Examples of the linearly polarizing reflective polarizer (a 2) include a grid type polarizer, a multilayer thin film laminate of two or more layers made of two or more materials having a difference in refractive index, and a different refractive index used for a beam splitter.
- materials that generate phase difference by stretching such as polyethylene naphthalate, polyethylene terephthalate, and polycarbonate, acryl-based resins, such as polymethyl methacrylate, and polyester made by JSR Corporation
- a resin obtained by alternately uniaxially stretching a resin having a small amount of retardation, such as a typical norporene resin, as a multilayer laminate can be used.
- the retardation layer (b 1) disposed between the circular polarization type reflection polarizer (a 1) or the linear polarization type reflection polarizer (a 2) has almost zero front-side phase difference, and It has a phase difference of 1/8 or more with respect to incident light at an angle of 30 °.
- the front phase difference is desirably equal to or smaller than S / 10 because the purpose is to maintain polarized light that is vertically incident.
- the incident light from the oblique direction is appropriately determined by the angle of total reflection so as to be efficiently converted in polarization.
- the phase difference when measured at 60 ° may be determined so as to be about ⁇ / 2.
- the transmitted light by the circularly polarized reflective polarizer (a 1) changes its polarization state due to the birefringence of the circularly polarized reflective polarizer (a 1) itself, like a C plate,
- the phase difference measured at that angle of the normally introduced C plate may be smaller than ⁇ / 2.
- phase difference of the C plate increases monotonically as the incident light tilts Therefore, as a guide to cause effective total reflection when the light is inclined at an angle of 30 ° or more, it is sufficient to have ⁇ / 8 or more for incident light at an angle of 30 °.
- the polarizing element ( ⁇ ) of the present invention is designed so as to be able to effectively block light rays having an incident angle of 30 ° from the front, substantially sufficient light can be obtained in a region having an incident angle of about 20 °. Transmitted light is low. When limited to light rays in this area, only light rays in an area showing good display of a general liquid crystal display device are transmitted. Used ⁇ ⁇ ⁇ Fluctuations occur due to conditions such as the type of liquid crystal in the cell, alignment state, and pretilt angle of the liquid crystal display device, but they do not cause gradation inversion or sharp deterioration of contrast. Level. Use a larger retardation value of the retardation layer to narrow down to only the front light, or use a gentler focusing with a smaller retardation value assuming that a liquid crystal is combined with a compensating retardation plate. Is also good.
- the material of the retardation layer (b 1) is not particularly limited as long as it has the above-mentioned optical properties.
- a fixed cholesteric liquid crystal having a selective reflection wavelength outside the visible light region (380 nm to 780 nm) a fixed cholesteric liquid crystal, a rod-shaped liquid crystal with a fixed homeotropic alignment, a discotic
- the liquid crystal includes one using a lambda uniaxial nematic alignment, one in which a negative uniaxial crystal is oriented in a plane, and a biaxially oriented polymer film.
- a C plate for example, a C plate in which the planar alignment state of a cholesteric liquid crystal having a selective reflection wavelength outside the visible light region (380 nm to 780 nm) is fixed is considered as the selective reflection wavelength of the cholesteric liquid crystal. It is desirable that there is no coloration in the visible light region. Therefore, the selective reflection light must not be in the visible region.
- the selective reflection is uniquely determined by the cholesteric chiral pitch and the refractive index of the liquid crystal.
- the value of the central wavelength of selective reflection may be in the near-infrared region, but it is more desirable to be in the ultraviolet region of 35 O nm or less because it is affected by optical rotation and causes a somewhat complicated phenomenon. .
- the formation of the cholesteric liquid crystal layer is performed in the same manner as the formation of the cholesteric layer in the reflective polarizer described above.
- a C-plate with a fixed homeotropic orbital alignment state is formed by polymerizing a liquid crystalline thermoplastic resin or liquid crystal monomer that exhibits nematic liquid crystallinity at high temperature and an alignment aid, if necessary, by irradiation with ionizing radiation such as electron beams or ultraviolet rays, or by heat. Polymerized liquid crystal, or it These mixtures are used.
- the liquid crystal properties may be either lyotropic or single-mouthed. However, from the viewpoint of easy control and easy formation of a monodomain, it is preferable that the liquid crystal be a single-mouthed liquid crystal.
- the homeotropic aperture pick alignment can be obtained, for example, by coating the birefringent material on a film on which a vertical alignment film (such as long-chain alkylsilane) has been formed, and developing and fixing a liquid crystal state.
- a discotic liquid crystal material having a negative uniaxial property such as a phthalocyanine-triphenylene compound having an in-plane molecular spread is used as a liquid crystal material. It is the one that expresses one phase of columna and is fixed.
- the negative uniaxial inorganic layered compound is described in detail in, for example, Japanese Patent Publication No. Hei 6—8277777.
- C-plates utilizing the biaxial orientation of polymer films can be obtained by a method of biaxially stretching a polymer film with positive refractive index anisotropy, a method of pressing a thermoplastic resin, a crystal with parallel orientation It can be obtained by a method such as cutting out from the product.
- the retardation layer (b 1) When a linear polarization type reflection polarizer (a 2) is used, the retardation layer (b 1) has a phase difference of almost zero in the front direction and is incident on the incident light at an angle of 30 ° from the normal direction. The one having a phase difference of ⁇ / 4 or more is used. On both sides of the phase difference layer (b 1), the front phase difference is approximately L / 4, and the linearly polarized light is once converted into circularly polarized light by using the / 4 plate (b 2). Parallel light can be obtained in a similar manner.
- the configuration cross section and the arrangement of each layer in this case are as shown in FIGS. 3, 4, and 5.
- the angle formed by the slow axis of the Z 4 plate (b 2) and the polarization axis of the linear polarization type reflective polarizer (a 2) is as described above, and the axis of the / plate (b 2)
- the angle can be set arbitrarily.
- a quarter-wave plate is used as the retardation layer (b 2).
- the ⁇ / 4 plate an appropriate retardation plate according to the purpose of use is used.
- two or more kinds of phase difference plates can be laminated to control optical properties such as phase difference.
- the retardation film is formed by stretching a film made of an appropriate polymer such as polycarbonate, norbornene-based resin, polybutyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, and other polyolefins, polyarylates, and polyamides.
- Birefringent film an alignment film made of a liquid crystal material such as a liquid crystal polymer, and an alignment layer of a liquid crystal material supported by a film.
- a retardation plate functioning as an L / 4 plate is, for example, a retardation layer functioning as a ⁇ / 4 plate for light color light having a wavelength of 55 nm and other retardation characteristics.
- the retardation plate provided between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.
- a similar effect can be obtained by arranging two axial retardation layers (b 3) such that the front retardation is approximately ⁇ / 4 and the thickness direction retardation is more than // 2.
- the biaxial retardation layer (b 3) satisfies the above requirements if the Nz coefficient is approximately 2 or more.
- the configuration cross section and the arrangement of each layer in this case are as shown in FIGS.
- the slow axis of the biaxial retardation layer (b 3) and the polarization axis of the linear polarization type reflection polarizer (a 2) are as described above, and the biaxial retardation layers (b 3)
- the front phase difference is approximately ⁇ / 4, which means that ⁇ / 4 ⁇ 4 O nm for light with a wavelength of 550 nm, and a range of ⁇ 15 nm
- one biaxial retardation layer (b 4) having a front phase difference of approximately 1/2 and a thickness direction retardation of 1/2 or more is used. The same effect can be obtained by doing so.
- the biaxial retardation layer (b 4) satisfies the above requirements if the Nz coefficient is approximately 1.5 or more.
- each layer in this case is as shown in FIGS.
- the relationship between the upper and lower linearly polarized reflective polarizers (a 2) and the central biaxial retardation layer (b 4) is the specified angle, and is uniquely determined.
- the fact that the front phase difference is approximately; 1/2 means that light having a wavelength of 550 nm is within a range of about 1/2 ⁇ 40 nm, and more preferably ⁇ 15 nm.
- the biaxial retardation layers (b 3) and (b 4) may be biaxially stretched birefringent plastic materials such as polycarbonate and polyethylene terephthalate, or a liquid crystal material in the planar direction.
- a uniaxially oriented one and a hybrid oriented one further oriented in the thickness direction are used.
- a liquid crystal material having a uniaxial homeotropic alignment is also possible, and is performed in the same manner as the method of forming a cholesteric liquid crystal film.
- use nematic liquid crystal material instead of cholesteric liquid crystal. Must be used.
- a diffuse reflection plate below the light guide plate (the side opposite to the liquid crystal cell arrangement surface) as the light source.
- the main component of the light beam reflected by the collimating film is an oblique incident component, which is specularly reflected by the collimating film and returned toward the backlight.
- the rear-side reflector has high specularity, the reflection angle is preserved, and the light cannot be emitted in the front direction, resulting in loss light. Therefore, it is desirable to provide a diffuse reflector in order to increase the diffuse reflection component in the front direction without preserving the reflection angle of the reflected return light beam.
- the diffusion plate to be used can be obtained by embedding fine particles having different refractive indices in a resin, in addition to a material having a surface irregular shape. This diffusion plate may be sandwiched between the collimating film and the backlight, or may be bonded to the collimating film.
- a Newton ring may be generated in the gap between the film surface and the backlight.
- a diffusion plate having surface irregularities on the side surface the generation of Newton rings can be suppressed.
- a layer having both the concavo-convex structure and the light diffusion structure may be formed on the surface of the parallel light conversion film in the present invention.
- the viewing angle expansion of the liquid crystal display device of the present invention is achieved by diffusing light beams having good display characteristics near the front obtained from the liquid crystal display device, which are combined with a parallelized backlight, so as to be uniform within the entire viewing angle. It is obtained by obtaining good display characteristics.
- a diffusion plate having substantially no backscattering is used as the viewing angle widening layer used here.
- the diffusion plate can be provided by a diffusion adhesive. The placement location is on the viewing side of the liquid crystal display device, but it can be used either above or below the polarizing plate.
- pixel blur In order to prevent the influence of the light or the like and the decrease in contrast due to slightly remaining back scattering, it is desirable to provide the layer as close to the cell as possible, such as between the polarizing plate and the liquid crystal cell. In this case, a film that does not substantially eliminate polarized light is desirable.
- a fine particle-dispersed diffusion plate as disclosed in JP-A-2000-347706 and JP-A-2007-40707 is preferably used. .
- the viewing angle enlarging layer is located outside the polarizing plate on the viewing side of the liquid crystal cell, the collimated light will pass through to the liquid crystal cell polarizing plate. It is not necessary to use a plate. In the case of the STN liquid crystal cell, it is only necessary to use a retardation film that is well compensated for only the front characteristics. In this case, since the viewing angle widening layer has an air surface, it is possible to adopt a type using a refraction effect due to the surface shape.
- the light is diffused at the stage of passing through the polarizing plate.
- the viewing angle characteristics of the polarizer itself need to be compensated.
- the black matrix of liquid crystal display devices and the conventional backlight collimating system have It interfered with microstructures such as micro lens array / prism array / louver / micro mirror array and caused moire.
- microstructures such as micro lens array / prism array / louver / micro mirror array and caused moire.
- the parallel light film according to the present invention no regular structure is visually recognized in the plane, and there is no regular modulation in the emitted light. Therefore, it is not necessary to consider the compatibility with the viewing angle widening layer and the arrangement order. Therefore, the viewing angle widening layer is not particularly limited as long as it does not cause interference / moire with the pixel black matrix of the liquid crystal display device, and the options are wide.
- the viewing angle widening layer has substantially no back scattering, does not cancel polarized light, and is disclosed in Japanese Patent Application Laid-Open Nos. 2000-34067 and 2000-34.
- even if it has a regular structure inside, such as a hologram sheet, a microprism array, or a microlens array it can be used as long as it does not form interference / moire with the pixel black matrix of the liquid crystal display device.
- the above-mentioned layers may be simply laminated, but it is desirable to laminate each layer using an adhesive or a pressure-sensitive adhesive from the viewpoint of workability and light use efficiency.
- the adhesive or pressure-sensitive adhesive is transparent, has no absorption in the visible light range, and the refractive index is preferably as close as possible to the refractive index of each layer from the viewpoint of suppressing surface reflection.
- an acrylic pressure-sensitive adhesive can be preferably used.
- a monodomain is separately formed in the form of an alignment film, and the layers are sequentially laminated by a method such as transfer to a light-transmissive substrate, or an alignment film is provided for alignment without providing an adhesive layer or the like. It is also possible to form the respective layers sequentially and directly.
- Particles may be added to each layer and the (viscosity) adhesive layer to adjust the degree of diffusion, if necessary, to provide isotropic scattering, or to use an ultraviolet absorber, an antioxidant, A surfactant or the like can be appropriately added for the purpose of imparting a leveling property.
- liquid crystal display device is manufactured by appropriately using various optical layers and the like according to an ordinary method.
- Polarizers (PL) are arranged on both sides of the liquid crystal cell.
- the polarizing plates (PL) arranged on both sides of the liquid crystal cell are arranged such that their polarization axes are substantially orthogonal to each other.
- the polarizing plate (P L) on the incident side is arranged so that the direction of its polarization axis and the axis direction of linearly polarized light obtained by transmission from the light source side are aligned.
- a polarizing plate having a protective film on one side or the rain side of the polarizer is generally used.
- the polarizer is not particularly limited, and various types can be used.
- polarizers include iodine and dichroic polymers, such as hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and ethylene-butyl acetate copolymer-based partially saponified films. Uniaxially stretched by adsorbing dichroic substances such as dyes, dehydrated polyvinyl alcohol, dehydrochlorinated polychlorinated vinyl, etc. Polyene-based oriented films and the like can be mentioned. Among them, a polar alcohol-based film and a polarizer made of a dichroic substance such as iodine are preferable.
- the thickness of these polarizers is not particularly limited, but is generally about 5 to 80 m.
- a polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching is produced, for example, by dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine, and stretching the film to 3 to 7 times its original length.
- iodine a polyvinyl alcohol-based film
- it can be immersed in an aqueous solution such as boric acid, zinc sulphate, zinc chloride or the like, which may contain iodinated lime.
- the polyvinyl alcohol-based film may be soaked in water and washed with water before dyeing.
- Rinsing the polyvinyl alcohol-based film with water not only removes stains on the surface of the polyvinyl alcohol-based film and anti-blocking agents, but also reduces uneven dyeing by removing the polyvinyl alcohol-based film. It also has the effect of preventing non-uniformity. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or lithium iodide or in a water bath.
- polyester polymers such as polyethylene terephthalate and polyethylene naphthalate
- cellulosic polymers such as diacetyl cellulose and triacetyl cellulose
- acrylic polymers such as polymethyl methacrylate, polystyrene and atalonitrile / styrene copolymer Styrene polymers such as (AS resin) and polycarbonate polymers.
- polyamides such as polyethylene, polypropylene, polyolefins having a cyclo- or norbornene structure, polyolefin polymers such as ethylene-propylene copolymers, vinyl chloride polymers, and polyamides such as aromatic polyamides.
- the transparent protective film can also be formed as a cured layer of a thermosetting or ultraviolet curable resin such as an acrylic, urethane, acrylic urethane, epoxy or silicone resin.
- a polymer film described in JP-A-2001-343529 for example, (A) a side chain having a substituted and / or unsubstituted imide group And (B) a thermoplastic resin having a substituted and / or unsubstituted phenyl and a nitrile group in a side chain.
- a specific example is a film of a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer.
- a film formed by mixing and displaying a resin composition can be used.
- the thickness of the protective film can be determined as appropriate, but is generally about 1 to 500 Am in terms of strength, workability and other workability, and thinness. Particularly, 1 to 300 is preferable, and 5 to 20 Ox / rn is more preferable.
- a protective film having a retardation value in the thickness direction of the film represented by) of from 190 nm to +75 nm is preferably used.
- the thickness direction retardation value (Rth) is more preferably from 180 nm to 160 nm, particularly preferably from 170 nm to 45 nm.
- a cellulosic polymer such as triacetyl cellulose is preferable from the viewpoint of polarization characteristics and durability. Particularly, triacetyl cellulose film is preferable.
- a protective film made of the same polymer material may be used on both sides thereof, or a protective film made of a different polymer material may be used.
- the polarizer and the protective film are in close contact with each other via an aqueous adhesive or the like.
- an aqueous adhesive isocyanate adhesive Agents, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based, water-based polyurethane, 7_ 7-based polyester, and the like.
- the surface of the transparent protective film on which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, a treatment for preventing stateing, and a treatment for diffusion or antiglare.
- the hard coat treatment is performed for the purpose of preventing the surface of the polarizing plate from being scratched, and for example, transparently protects a cured film having an excellent hardness and a sliding property by a suitable ultraviolet curable resin such as an acryl-based or silicone-based resin. It can be formed by a method of adding to the surface of the film.
- the anti-reflection treatment is performed for the purpose of preventing reflection of external light on the polarizing plate surface, and can be achieved by forming an anti-reflection film or the like according to the related art.
- the anti-stating treatment is performed to prevent adhesion to the adjacent layer.
- the anti-glare treatment is performed to prevent external light from being reflected on the surface of the polarizing plate and hindering the visibility of light transmitted through the polarizing plate. It is formed by imparting a fine uneven structure to the surface of the transparent protective film by an appropriate method such as a rough surface method using a sandplast method or an embossing method, or a method of blending transparent fine particles. be able to.
- the fine particles to be included in the formation of the surface fine unevenness include silica, alumina, titania, zirconia, tin oxide, indium oxide, dicadmium oxide, and antimony oxide having an average particle size of 0.5 to 50 ⁇ m.
- Transparent fine particles such as inorganic fine particles which may be conductive and organic fine particles made of a crosslinked or uncrosslinked polymer are used.
- the amount of the fine particles used is generally about 2 to 50 parts by weight with respect to 100 parts by weight of the transparent resin forming the fine surface unevenness structure, and 5 to 25 parts by weight. Parts by weight are preferred.
- the anti-glare layer may also serve as a diffusion layer (such as a viewing angle enlargement function) for diffusing light transmitted through the polarizing plate to increase the viewing angle and the like.
- the anti-reflection layer, anti-stating layer, diffusion layer, anti-glare layer, and the like can be provided on the transparent protective film itself, or can be provided as an optical layer separately from the transparent protective film. .
- the retardation plate is laminated on a polarizing plate as a viewing angle compensating film, and is used as a wide viewing angle polarizing plate.
- the viewing angle compensation film is a film for widening the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a direction slightly oblique to the screen rather than perpendicularly.
- a biaxially stretched film As such a viewing angle compensating retardation film, a biaxially stretched film, a bidirectionally stretched film such as an obliquely oriented film, or the like, which has been biaxially stretched or stretched in two orthogonal directions, or the like, may be used.
- the obliquely oriented film include, for example, a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the shrinkage force caused by heat, or obliquely aligning a liquid crystal polymer. And the like.
- the viewing angle compensation film can be appropriately combined for the purpose of preventing coloring or the like due to a change in the viewing angle based on the phase difference between the liquid crystal cells and expanding the viewing angle for good visibility.
- the optical compensation by supporting the alignment layer of the liquid crystal polymer, especially the optically anisotropic layer consisting of the tilted alignment layer of the discotic liquid crystal polymer, with a triacetyl cellulose film.
- a retardation plate can be preferably used.
- the optical layer to be laminated in practical use is not particularly limited.For example, one or two or more optical layers which may be used for forming a liquid crystal display device such as a reflector or a transflector are used. be able to. In particular, a reflective polarizing plate or a transflective polarizing plate obtained by laminating a reflecting plate or a transflective reflecting plate on an elliptically polarizing plate or a circularly polarizing plate can be used.
- the reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device of a sunset type that reflects an incident light from a viewing side (display side) and displays the reflected light.
- a viewing side display side
- the reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is provided on one side of the polarizing plate via a transparent protective layer or the like as necessary.
- the reflective polarizing plate include those in which a reflective layer formed by attaching a foil made of a reflective metal such as aluminum to a vapor deposition film is provided on one side of a protective film that has been subjected to a matte treatment as required.
- the protective film may contain fine particles to form a fine surface irregularity structure, on which a reflective layer having a fine irregularity structure is provided. .
- the reflective layer having the fine uneven structure described above has an advantage that the incident light is diffused by irregular reflection to prevent directivity and glare, and that unevenness of light and darkness can be suppressed.
- the protective film containing fine particles has an advantage that the incident light and its reflected light are diffused when transmitted through the protective film, so that unevenness in brightness and darkness can be further suppressed.
- the reflective layer having a fine uneven structure reflecting the fine uneven structure on the surface of the protective film can be formed by, for example, making the metal transparent by an appropriate method such as an evaporation method such as a vacuum evaporation method, an ion plating method, or a sputtering method, or a plating method. It can be performed by a method of directly attaching to the surface of the protective layer.
- a reflection sheet in which a reflection layer is provided on an appropriate film corresponding to the transparent film can be used. Since the reflective layer is usually made of metal, its use in a state where the reflective surface is covered with a protective film, a polarizing plate, or the like is intended to prevent the decrease in reflectance due to oxidation and to maintain the initial reflectance over a long period of time. It is more preferable to avoid separately providing a protective layer.
- the transflective polarizing plate can be obtained by forming a transflective reflective layer such as a half mirror that reflects and transmits light with the reflective layer in the above.
- a transflective polarizing plate is usually provided on the back side of a liquid crystal cell.
- a liquid crystal display device When a liquid crystal display device is used in a relatively bright atmosphere, an image is displayed by reflecting incident light from the viewing side (display side). In a relatively dark atmosphere, a liquid crystal display device of a type that displays an image using a built-in light source such as a backlight built in the back side of a transflective polarizing plate can be formed.
- a transflective polarizing plate can save energy for using a light source such as a backlight in a bright atmosphere, and is useful for forming a liquid crystal display device of a type that can be used with a built-in light source even in a relatively dark atmosphere.
- the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers as in the above-mentioned polarizing beam splitter I polarizing plate. Therefore, a reflective elliptically polarizing plate or a transflective elliptically polarizing plate obtained by combining the above-mentioned reflective polarizing plate, semi-transmissive polarizing plate and retardation plate may be used.
- the polarizing plate and the retardation plate and the like can be formed by sequentially and separately laminating in the manufacturing process of the liquid crystal display device. This has the advantage that it is excellent in quality stability and laminating workability, and can improve the production efficiency of liquid crystal display devices and the like.
- the optical element of the present invention may be provided with an adhesive layer or an adhesive layer.
- the adhesive layer can be used for attaching to a liquid crystal cell and also for laminating an optical layer.
- their optical axes can be set at an appropriate angle depending on the intended retardation characteristics and the like.
- the adhesive and the pressure-sensitive adhesive are not particularly limited.
- a polymer such as a rubber-based polymer can be appropriately selected and used.
- those having excellent optical transparency, exhibiting appropriate wettability, cohesiveness and adhesive adhesive properties and having excellent weather resistance and heat resistance can be preferably used.
- the adhesive or pressure-sensitive adhesive may contain a crosslinking agent according to the base polymer.
- Adhesives include, for example, natural and synthetic resins, especially tackifier resins, fillers, pigments, colorants, and oxidants composed of glass fibers, glass beads, metal powders, and other inorganic powders.
- An additive such as an inhibitor may be contained.
- an adhesive layer containing fine particles and exhibiting light diffusing properties may be used.
- the adhesive or pressure-sensitive adhesive is usually used as an adhesive solution having a solid content concentration of about 10 to 50% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent.
- a solvent an organic solvent such as toluene or ethyl acetate or a solvent depending on the kind of the adhesive such as water can be appropriately selected and used.
- the pressure-sensitive adhesive layer and the adhesive layer may be provided on one or both sides of a polarizing plate or an optical film as a superposed layer of different compositions or the like.
- the thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, and the like, and is generally from 1 to 500 m, preferably from 5 to 200 m, particularly preferably from 10 to L; m is preferred.
- the exposed surface of the adhesive layer, etc. is temporarily covered with separee for the purpose of preventing contamination, etc. until it is practically used. This can prevent the adhesive layer from coming into contact with the adhesive layer in a normal handling state.
- plastic sheets, rubber sheets, paper, cloth, non-woven fabrics, nets, foamed sheets, metal foils, laminates of these materials, etc. as appropriate, silicone-based, long mirror alkyl-based, fluorine-based, molybdenum sulfide, etc.
- An appropriate material according to the related art such as a material coated with an appropriate release agent, can be used.
- each layer such as the optical element and the adhesive layer may include, for example, a salicylate compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, and nickel.
- a material having an ultraviolet absorbing ability by a method such as a treatment with an ultraviolet absorbent such as a complex salt compound may be used.
- the front phase difference is defined as the X-axis in the direction in which the in-plane refractive index is the maximum, the Y-axis in the direction perpendicular to the X-axis, and the Z-axis in the thickness direction of the film.
- the refractive index at 550 nm, nx, ny, and nz, as ny and nz, were measured with an automatic birefringence measurement device (Oji Scientific Instruments, KOBRA2 1 ADH) and the thickness of the retardation layer. From d (nm), the front phase difference: (nx—ny) Xd and the phase difference in the thickness direction: (nx—nz) Xd were calculated.
- the phase difference measured when tilted can be measured by the automatic birefringence measuring device.
- the tilt phase difference is: (nx-ny) Xd when tilted.
- Nz (nx-nz) / (nx-ny).
- the reflection spectrum is measured with a spectrophotometer (Otsuka Electronics Co., Ltd., instantaneous multi-photometry system MCPD-2000), and the reflection wavelength band with half the maximum reflectance is measured.
- the base material is polyethylene terephthalate with a thickness of 50 m.
- the total thickness was about 53 m using Tofilm.
- Table 1 below shows the design drawing of the thickness of the deposited thin film.
- Backlight (Stanley Electric) 10.4 inch type using a sidelight type light guide (light guide whose cross section is a ⁇ edge type and dot printing is performed on the back side) as the bright line light source (L) was used.
- a three-wavelength cold-cathode tube was used as the light source.
- the wavelength characteristics of the cold-cathode tube as the light source and the vapor-deposited multilayer bandpass filter as the secondary light-collecting element (Y) are as shown in FIG. Measurement of wavelength characteristics The measurement was carried out using an in-house spectrophotometer U4100.
- the graph shown in FIG. 23 is obtained by measuring the light-collecting characteristics of the structure shown in FIG. 15 using only the vapor-deposited multilayer film band-pass filter which is the secondary light-collecting element (Y).
- Y secondary light-collecting element
- a secondary peak is seen around 70 °. This is because the deposited multilayer band-pass filter (Y) shifts blue due to oblique incidence, the transmission region for green light shows transmission for blue light, and the transmission region for red light shows transmission for green light. That's why. For this reason, strong coloring of the emitted light from oblique directions was observed. Furthermore, since the emitted light distribution of the backlight system used emitted a strong luminous flux at an angle 60 ° or more away from the front, the coloring was conspicuous.
- a prism sheet was used as the primary condensing part (X).
- the prism sheets used were two 3M BEF films (thickness: about 180 m, polyethylene terephthalate film, apex angle: about 90 °, prism pitch: 50 m).
- a backlight system (BLS) having a prism sheet as the primary light condensing part (X) has a characteristic of condensing light within ⁇ 50 ° with respect to the front direction.
- a liquid crystal cell (LC) a 10.4 inch TFT cell manufactured by Sharp Corporation was used.
- the polarizing plate (PL) is SEG manufactured by Nitto Denko Corporation.
- the liquid crystal cell (LC) was ft-aligned so as to be orthogonal to both sides.
- the secondary condensing element (Y) was bonded to a polarizing plate (PL).
- PL polarizing plate
- a cholesteric liquid crystal bandpass filter manufactured by thin film coating of a cholesteric liquid crystal polymer was used as the secondary condensing element (Y). This is a combination of a bandpass filter for right-handed circularly polarized light reflection for three wavelengths and a bandpass filter for left-handed circularly polarized light reflection for three wavelengths. Obliquely incident light is reflected.
- the front transmitted light beam is non-polarized light. This is because the liquid crystal layer is used as a bandpass filter, and transmitted light from an area where polarization separation by cholesteric reflection is not transmitted is transmitted in the front direction. Therefore, in measuring the light-collecting characteristics, the secondary light-collecting element ( ⁇ ⁇ ) and the polarizing plate (PL) were laminated without providing a retardation layer.
- the selective reflection wavelength range is from 450 nm to 490 nm and from 550 nm to 550 nm, 545 nm and 6,10 nm for the emission spectrum of a three-wavelength cold cathode tube.
- a selective reflection circularly polarized bandpass filter that reflects right circularly polarized light with a wavelength of 600 nm and a wavelength of 61 to 70 O nm was prepared.
- the liquid crystal material used was based on the specification of EP-A-0 83 4 754, and based on the specification, three types of cholesteric liquid crystal polymers having a selective reflection center wavelength of 480 nm. 570 nm. Produced.
- Cholesteric liquid crystal polymers are as follows:
- the cholesteric liquid crystal polymer was dissolved in dimethyl chloride to prepare a 10% by weight solution.
- the solution was applied to an alignment substrate with a wire bar so that the thickness when dried was about 1 m.
- a polyethylene terephthalate film having a thickness of 75 ⁇ m was used as an alignment substrate, and a polybutyl alcohol layer was coated on the surface of the film with a thickness of about 0.1 ⁇ m and rubbed with a rayon rubbing cloth. After coating, it was dried at 140 ° C for 15 minutes. After the completion of the heat treatment, the liquid crystal was cooled and fixed at room temperature to obtain a thin film.
- a liquid crystal thin film of each color was produced through the same steps as described above, and then bonded together with an isocyanate adhesive. Thereafter, the polyethylene terephthalate base material was removed, and three liquid crystal layers were stacked in order from the short wavelength side to obtain a liquid crystal composite layer having a thickness of about 5 ⁇ m.
- the wavelength characteristic of the cholesteric liquid crystal bandpass filter which is the secondary condensing element (Y) is as shown in Fig. 25.
- the graph shown in FIG. 21 is obtained by measuring the light-collecting characteristics of the structure shown in FIG. 15 using the cholesteric liquid crystal bandpass filter as the secondary light-collecting element (Y) alone.
- Example 1 a backlight system (BLS) in which two prism sheets were stacked was used as the partially condensing portion (X).
- a polarizing element with a retardation plate (b 1) provided between two circularly-polarizing reflective polarizers (a 1) where the wavelength bands of polarized light selective reflection overlap each other is used.
- a difference layer (b 1: negative C plate) was prepared from a polymerizable liquid crystal.
- LC 242 manufactured by BASF was used as the polymerizable mesogen compound, and LC756 manufactured by BASF was used as the polymerizable chiral agent.
- the mixing ratio (weight ratio) of the polymerizable mesogen compound and the polymerizable chiral agent is 1 such that the selective reflection center wavelength of the obtained cholesteric liquid crystal is about 35 O nm. 1/8 8
- the center wavelength of selective reflection of the obtained cholesteric liquid crystal was 350 nm.
- the specific manufacturing method is as follows.
- a polymerizable chiral agent and a polymerizable mesogen compound are dissolved in cyclopentane (30% by weight), and a reaction initiator (Irgacure 907 manufactured by Ciba Specialty Chemicals, 1% by weight based on the mixture) is added.
- a prepared solution was prepared.
- a surfactant BYK-361 manufactured by Big Chemi Japan
- the oriented substrate used was a polyethylene terephthalate film manufactured by Toray: Lumirror (thickness: 75 ⁇ m), which had been rubbed with a rubbing cloth.
- the solution was applied with a wire bar to a thickness of 7 ⁇ m when dried, dried at 90 ° C. for 2 minutes, heated once to an isotropic transition temperature of 130 ° C., and then gradually cooled. While maintaining a uniform alignment state, the composition was cured by ultraviolet irradiation (1 OmWZ square cm ⁇ 1 minute) at 80 ° C. to obtain a negative C plate (bl).
- the phase difference of this negative C plate (b 1) was measured, the phase difference when tilted by 2 nm and 30 ° in front of the light at a wavelength of 550 nm was about 19 O nm (> ⁇ / 8).
- a translucent acrylic adhesive Nito Denko Corporation, NO. 7, 25 umW-
- a negative C plate b 1
- a circular polarization type reflective polarizer (a1) was further laminated and transferred to obtain a polarizing element.
- the polarizing element was designated as a secondary light-collecting element (Y).
- the secondary light condensing element (Y) of Example 3 Since the secondary light condensing element (Y) of Example 3 has a polarization separation function over the entire visible light band, the front transmitted light is circularly polarized by the polarization separation function of the cholesteric liquid crystal. Therefore, a quarter-wave plate (B) is placed between the polarizing plate (PL) on the backlight side of the liquid crystal cell (LC) and the secondary light-collecting element (Y) with respect to the polarizing axis of the polarizing plate (PL).
- a quarter-wave plate (B) is placed between the polarizing plate (PL) on the backlight side of the liquid crystal cell (LC) and the secondary light-collecting element (Y) with respect to the polarizing axis of the polarizing plate (PL).
- a translucent acryl-based adhesive N0.7, 25 urn manufactured by Nitto Denko. This is for converting circularly polarized light into linearly polarized light and improving transmission characteristics to the polarizing plate.
- a prism sheet was used as the partial light condensing part (X).
- the prism sheets used were two 3M BEF films (thickness: about 180 m, polyethylene terephthalate film, apex angle: about 90 °, prism pitch: 50 mm).
- a backlight system having a prism sheet as such a partial light condensing part (X) has a characteristic of condensing light within ⁇ 55 °.
- the graph shown in FIG. 27 is obtained by measuring the light condensing characteristics using the polarizing element (A) as the secondary light condensing element (Y) in the structure of FIG. 17 alone. In the graph shown in Fig. 27, leaked light is observed outside of 50 ° or more.
- a backlight system (BLS) having the primary condensing section (X) and a secondary condensing element (Y) were arranged in the structure shown in FIG. Fig. 28 shows the measurement of the light-collecting characteristics of the structure shown in Fig. 18.
- the measurement of the light-collecting characteristics in FIGS. 27 and 28 was performed using Ez-Contrast, manufactured by ELDIM.
- the primary condensing part (X) reduces the rays emitted from the light source at an angle of 50 ° or more, eliminates the rays passing through the secondary condensing element (Y), and leaves only the central secondary condensing part. That is, only the front looks bright, and the diagonal direction is jet black and no coloring is visible.
- a retardation plate (b 1) is provided between two linearly-polarizing reflection polarizers 2) in which the wavelength bands of polarized light selective reflection overlap each other. (b On both sides of 1), a polarizing element having a layer (b 2) having a front retardation of approximately 1/4 was used.
- the retardation plate (b1) was produced according to the method for producing a negative C plate in Example 3.
- the thickness of the obtained negative C plate (b1) was 8 ⁇ m, and the phase difference was measured. was about 220 nm (> ⁇ / 4).
- the upper and lower linear polarization type reflective polarizers (a 2) were laminated at an angle of 45 ° (—45 °) with the shaft, and five sheets were laminated.
- the laminate was bonded with a translucent acrylic adhesive (No. 7, 25 um manufactured by Todenko).
- a backlight system having a primary light condensing part (X), a cross-sectional wedge-type acryl light guide with a micro aperture prism array on the surface and a sidelight-type backlight (IBM notebook PC TinPad Taken out from the product).
- the backlight system (BLS) with the primary condensing part (X) focused the light emitted from the light source primary within ⁇ 50 ° with respect to the front direction.
- the graph shown in FIG. 29 is obtained by measuring the light condensing characteristics of the polarizing element (A) alone as the secondary light condensing element (Y) in the structure of FIG.
- a leaked light beam is observed outside ⁇ 50 ° or more with respect to the front direction.
- the light source and (L) used a light box made by Hakuba (direct backlight, diffused light source).
- FIG. 30 shows the measured light-collecting characteristics of the structure shown in FIG.
- the cholesteric liquid crystal bandpass filter of Example 2 was used as a light-condensing film. It was placed on a dot printed light guide plate. The light collection characteristics are as shown in Fig. 2, and a strong peak of secondary transmission is observed. Industrial applicability '
- the light-collecting system of the present invention can effectively block the oblique dropout, suppress unpleasant coloring, have good display, and can reduce the cost. It can be suitably applied.
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Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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KR10-2004-7017087A KR20040102166A (ko) | 2002-04-24 | 2003-04-18 | 집광 시스템 및 투과형 액정표시장치 |
US10/512,049 US20050180017A1 (en) | 2002-04-24 | 2003-04-18 | Light converging system and transmission liquid crystal display |
EP03725599A EP1498768A4 (en) | 2002-04-24 | 2003-04-18 | LIGHT CONVERGING SYSTEM AND TRANSMISSION LIQUID CRYSTAL DISPLAY |
Applications Claiming Priority (2)
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JP2002122723 | 2002-04-24 | ||
JP2002-122723 | 2002-04-24 |
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WO2003091794A1 true WO2003091794A1 (fr) | 2003-11-06 |
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PCT/JP2003/004945 WO2003091794A1 (fr) | 2002-04-24 | 2003-04-18 | Systeme de convergence lumineuse et affichage a cristaux liquides de transmission |
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Country | Link |
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US (1) | US20050180017A1 (ja) |
EP (1) | EP1498768A4 (ja) |
KR (1) | KR20040102166A (ja) |
CN (1) | CN100359387C (ja) |
TW (1) | TW200307160A (ja) |
WO (1) | WO2003091794A1 (ja) |
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US11703622B2 (en) | 2018-10-12 | 2023-07-18 | Meta Platforms Technologies, Llc | Polarization-based filters with angle-sensitive transmission having circular polarizers |
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WO2003091766A1 (en) * | 2002-04-23 | 2003-11-06 | Nitto Denko Corporation | Polarizer, polarization light source and image displayunit using them |
JP4251483B2 (ja) * | 2003-06-24 | 2009-04-08 | 日東電工株式会社 | 光学素子、集光バックライトシステムおよび液晶表示装置 |
JP4889239B2 (ja) | 2005-05-18 | 2012-03-07 | チェイル インダストリーズ インコーポレイテッド | バックライトユニットおよび液晶表示装置 |
JP5393048B2 (ja) | 2007-06-29 | 2014-01-22 | 日東電工株式会社 | 液晶表示装置および積層偏光板ならびに偏光光源装置 |
US20090309838A1 (en) * | 2008-06-11 | 2009-12-17 | Microsoft Corporation | Use of separation elements with rear projection screen |
JP2010085627A (ja) * | 2008-09-30 | 2010-04-15 | Sumitomo Chemical Co Ltd | 偏光板、ならびにそれを用いた液晶パネルおよび液晶表示装置 |
US10114162B2 (en) | 2011-01-18 | 2018-10-30 | 3M Innovative Properties Company | Optical film stack with retardance layer having in-plane retardance of greater than 2.0 microns |
CN104848092A (zh) * | 2015-05-22 | 2015-08-19 | 深圳市华星光电技术有限公司 | 背光模组和液晶显示器 |
JP6344527B2 (ja) * | 2016-03-25 | 2018-06-20 | 東レ株式会社 | 光源ユニット、積層部材ならびにそれらを用いたディスプレイおよび照明装置 |
JP6671494B2 (ja) | 2016-09-28 | 2020-03-25 | 富士フイルム株式会社 | 光学積層体 |
JP2019028373A (ja) | 2017-08-02 | 2019-02-21 | スリーエム イノベイティブ プロパティズ カンパニー | 表示装置、及び赤外光カットフィルム |
KR20190077970A (ko) | 2017-12-26 | 2019-07-04 | 주식회사 엘지화학 | 편광판 및 이를 포함하는 액정 표시 장치 |
JP2022553201A (ja) * | 2019-10-17 | 2022-12-22 | マジック リープ, インコーポレイテッド | ウェアラブルディスプレイ内の光透過率アーチファクトの減衰 |
CN113050283B (zh) * | 2021-03-18 | 2022-07-22 | 歌尔股份有限公司 | 光线偏转结构和头戴显示设备 |
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- 2003-04-18 WO PCT/JP2003/004945 patent/WO2003091794A1/ja not_active Application Discontinuation
- 2003-04-18 EP EP03725599A patent/EP1498768A4/en not_active Withdrawn
- 2003-04-18 KR KR10-2004-7017087A patent/KR20040102166A/ko not_active Application Discontinuation
- 2003-04-18 US US10/512,049 patent/US20050180017A1/en not_active Abandoned
- 2003-04-18 CN CNB038088940A patent/CN100359387C/zh not_active Expired - Fee Related
- 2003-04-23 TW TW092109495A patent/TW200307160A/zh unknown
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US11703622B2 (en) | 2018-10-12 | 2023-07-18 | Meta Platforms Technologies, Llc | Polarization-based filters with angle-sensitive transmission having circular polarizers |
Also Published As
Publication number | Publication date |
---|---|
EP1498768A1 (en) | 2005-01-19 |
CN1646975A (zh) | 2005-07-27 |
EP1498768A4 (en) | 2005-08-31 |
US20050180017A1 (en) | 2005-08-18 |
KR20040102166A (ko) | 2004-12-03 |
TW200307160A (en) | 2003-12-01 |
CN100359387C (zh) | 2008-01-02 |
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