WO2005040870A1 - 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 - Google Patents
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 Download PDFInfo
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- WO2005040870A1 WO2005040870A1 PCT/JP2004/012121 JP2004012121W WO2005040870A1 WO 2005040870 A1 WO2005040870 A1 WO 2005040870A1 JP 2004012121 W JP2004012121 W JP 2004012121W WO 2005040870 A1 WO2005040870 A1 WO 2005040870A1
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- light
- axis
- liquid crystal
- optical element
- linearly polarized
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- 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
- G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
- G02B6/0033—Means for improving the coupling-out of light from the light guide
- G02B6/0056—Means for improving the coupling-out of light from the light guide for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
Definitions
- the present invention relates to an optical element using a polarizing element.
- the present invention relates to a condensing backlight system using the optical element, and a liquid crystal display device using the same.
- Patent Document 15 a method combining polarization and phase difference has been proposed.
- other optical elements comprising a reflective polarizer, a rotary optical plate and a reflective polarizer have been proposed (see Patent Documents 16, 16, 17 and 18).
- Patent Document 19 a proposal using a hologram material has been proposed.
- a half-wave plate is disposed between a reflector obtained by combining a left circularly polarized light separator and a right circularly polarized light separator, or a circularly polarized light separator in the same direction.
- Light is collected in the front direction using a reflector obtained by placing the reflector.
- a reflector obtained by placing the reflector it was necessary to form a layer corresponding to each wavelength of the light source, and three layers were required for colorization. This was complicated and expensive.
- a polarizing element having an angle dependence in transmittance can be manufactured as in Patent Document 15.
- the polarizing element can change the transmittance according to the incident angle. For example, according to such a polarizing element, it is possible to reduce the transmittance of obliquely incident light rays, which increases the transmittance in the front direction.
- Patent Document 17, Patent Document 18, and Patent Document 19 all disclose the productivity and area yield of reflective polarizer laminates for transflective reflectors, which are caused by laminating these at different angles.
- the problem of deterioration has been improved by using a rotator to enable roll-to-roll production.
- a rotator to enable roll-to-roll production.
- the angle dependence of the transmittance did not occur.
- the TN liquid crystal layer functions as an optical rotation plate, it also functions as a 90-degree optical rotator in the oblique incident direction as in the front direction, and there was no particular phenomenon in which the optical rotation angle changes depending on the incident angle. .
- most hologram materials are expensive, have poor mechanical properties, and are soft materials, and have a problem in long-term durability.
- the above-described conventional optical element has problems such as difficulty in manufacturing, difficulty in obtaining desired optical characteristics, and poor reliability.
- Patent Document 1 JP-A-6-235900
- Patent Document 2 JP-A-2-158289
- Patent Document 3 JP-A-10-321025
- Patent Document 4 US Pat. No. 6,307,604
- Patent document 5 German Patent Application Publication No. 3836955
- Patent Document 6 German Patent Application Publication No. 422028
- Patent Document 7 European Patent Application Publication No. 578302
- Patent Document 8 US Patent Application Publication No. 2002/34009
- Patent Document 9 WO 02/25687 pamphlet
- Patent Document 10 U.S. Patent Application Publication No. 2001/521643
- Patent Document 11 U.S. Patent Application Publication No. 2001/516066
- Patent Document 12 US Patent Application Publication No. 2002/036735
- Patent Document 13 JP-A-2002-90535
- Patent Document 14 Japanese Patent Application Laid-Open No. 2002-258048
- Patent Document 15 Patent No. 2561483
- Patent Document 16 U.S. Patent No. 4984872
- Patent Document 17 U.S. Patent Application Publication No. 2003/63236
- Patent Document 18 International Publication No. 03/27731 pamphlet
- Patent Document 19 International Publication No. 03/27756 pamphlet
- Patent Document 20 JP-A-10-321025
- An object of the present invention is to provide an optical element capable of condensing and collimating incident light from a light source, and capable of suppressing transmission of light in an arbitrary direction. It is another object of the present invention to provide a condensing backlight system using the optical element, and further to provide a liquid crystal display device.
- the present inventors have conducted intensive studies to solve the above problems, and as a result, have found the following optical element and have completed the present invention. That is, the present invention is as follows.
- a polarizing element (A) formed of cholesteric liquid crystal, which separates incident light into polarized light and emits the polarized light.
- the outgoing light with respect to the incident light in the normal direction has a distortion rate of 0.5 or more
- the outgoing light with respect to the incident light incident at an angle of 60 ° or more from the normal direction has a distortion rate of 0.2 or less
- a layer (C) having a front phase difference (normal direction) of approximately zero and generating a phase difference with respect to incident light inclined with respect to the normal direction;
- 1/4 wavelength plate (D) is arranged in this order,
- the 1Z4 wavelength plate (D) is provided with a linearly polarized light reflective polarizer (E) that transmits one of the orthogonal linearly polarized light and selectively reflects the other, and the direction of the transmission axis and the polarization direction.
- An optical element characterized by being arranged so that the axis of transmitted light passing through the elements (A) to the quarter-wave plate (D) in this order is in the same direction.
- the polarization element (A) increases the linearly polarized light component of the outgoing light as the incident angle increases, by changing the polarization axis of the linearly polarized light in a direction substantially orthogonal to the normal direction of the polarization element surface.
- the polarization element (A) increases the linearly polarized light component of the outgoing light as the incident angle increases, by changing the polarization axis of the linearly polarized light in a direction substantially parallel to the normal direction of the polarization element surface.
- the direction in which the in-plane refractive index becomes maximum is indicated by the X-axis and the direction perpendicular to the X-axis by the 1Z2 wavelength plate (B).
- the 1Z2 wavelength plate (B) is characterized in that the phase difference in the thickness direction is controlled to reduce the change in the phase difference with respect to the change in the angle.
- Optical element
- An inorganic layered compound having a negative uniaxial property the orientation of which is fixed so that the optical axis is normal to the surface
- the quarter-wave plate (D) according to any one of the above items 11 to 11, wherein the quarter-wave plate (D) is a broadband wave plate that functions as a substantially quarter-wave plate in the entire visible light region. Optical element.
- the direction in which the in-plane refractive index is maximum is the X axis
- the direction perpendicular to the X axis is the Y axis
- the refractive index in each axial direction is nx, ny, and thickness.
- the direction in which the in-plane refractive index is the maximum is the X axis
- the direction perpendicular to the X axis is the Y axis
- the thickness direction of the film is the Z axis.
- Nz coefficient force represented by Nz (nx_nz) / (nx_ny) ⁇ 2.5 ⁇ Nz ⁇ 1.
- the linearly-polarized reflection polarizer (E) is a multilayer thin film laminate of two or more and two or more layers having a difference in refractive index, wherein Optical element.
- a polarizing plate is arranged outside the linearly polarizing and reflecting polarizer (E) so that the polarization transmission axis of the linearly polarizing and reflecting polarizer (E) and the polarization axis direction of the polarizing plate are aligned.
- the optical element according to any one of the above items 119, characterized in that:
- Each of the above-mentioned layers is laminated by using a translucent adhesive or pressure-sensitive adhesive.
- a liquid crystal display device comprising at least a liquid crystal cell arranged in the condensing backlight system described in 22 above.
- the optical element of the present invention includes a polarizing element (A) formed of cholesteric liquid crystal, which polarizes and separates incident light and emits the same, a half-wave plate (B), and a retardation layer ( C), a quarter-wave plate (D), and a linear polarization reflection type polarizer (E) are arranged in this order.
- FIG. 13 shows an example of a sectional view of such an optical element (X) of the present invention.
- the optical element (X) of the present invention utilizes the peculiar phenomenon of the polarizing element (A). That is, in the optical element (X) of the present invention, when the incident angle is increased to a certain degree, the outgoing light is linearly polarized, and even if the incident angle is further increased, the polarization axis direction of the linearly polarized light does not change and the polarization state becomes one. Utilizing the peculiar properties of the polarizing element (A), which is kept constant, this is converted into a half-wave plate (B), a retardation layer (C), a quarter-wave plate (D), By combining with the polarizer (E), the emitted light is controlled to be in a predetermined direction, and the secondary transmission component is suppressed.
- the outgoing light with respect to the incident light in the normal direction has a distortion rate of 0.5 or more, and circularly polarized light is emitted at the perpendicular incident light or at an incident angle close to the perpendicular incidence.
- the ratio of the circularly polarized light increases as the distortion ratio of the outgoing light with respect to the incident light in the normal direction increases, the ratio is preferably 0.7 or more, and more preferably 0.9 or more.
- the outgoing light with respect to the incident light incident at an inclination of 60 ° or more in the normal direction has a distortion rate of 0.2 or less, and emits linearly polarized light at a deep incident angle.
- the polarizing element (A) of the present invention has a feature that the linearly polarized light component of the outgoing light increases as the incident angle increases.
- FIG. 1 (A) shows a polarizing element that is an optical surface (X-axis-y-axis plane).
- FIG. 9 is a conceptual diagram showing that the emitted light (e) transmitted through (Al) has different polarization components depending on the difference in the incident angle of the incident light (i).
- FIG. 1 (B) is a conceptual diagram when the emitted light (e) is viewed as a force in the z-axis direction. As shown in FIG. 3, (i) linearly polarized light, (ii) natural light, (iii) circularly polarized light, and (iv) elliptically polarized light.
- Outgoing light (el) Outgoing light for incident light (il) in the z-axis direction (normal direction) to the polarizing element (A1), and is circularly polarized light.
- the outgoing light (e2) exists on a plane including the z-axis and the y-axis, and is elliptically polarized light having an axis orthogonal to the plane.
- the outgoing light (e4) exists on a plane including the z-axis and the X-axis, and is elliptically polarized light having an axis orthogonal to the plane.
- the emitted light (e3) exists on a plane including the z-axis and the y-axis, and is linearly polarized light having an axis orthogonal to the plane.
- the emitted light (e5) is linearly polarized light that exists on a plane including the z-axis and the X-axis and has an axis orthogonal to the plane.
- the outgoing lights (e3) and (e5) which are linearly polarized light, have their polarization axes in a direction substantially orthogonal to the z-axis, that is, in a direction parallel to the optical surface (the X-axis and y-axis planes). I have.
- FIG. 2 (A) shows that the output light (e) transmitted through the polarizing element (A2), which is the optical surface (X-axis y-axis plane), has different polarization components depending on the incident angle of the incident light (i).
- FIG. FIG. 2 (B) is a conceptual diagram when the emitted light (e) is viewed from the z-axis direction.
- Outgoing light (e41) Outgoing light with respect to incident light (i41) in the z-axis direction (normal direction) to the polarizing element (A2), and is circularly polarized light.
- the outgoing light (e42) exists on a plane including the z-axis and the y-axis, and is elliptically polarized light having an axis parallel to the plane.
- the outgoing light (e44) exists on a plane including the z-axis and the X-axis, and is elliptically polarized light having an axis parallel to the plane.
- the emitted light (e43) exists on a plane including the z-axis and the y-axis, and is linearly polarized light having an axis parallel to the plane.
- the emitted light (e45) is linearly polarized light that exists on a plane including the z axis and the X axis and has an axis parallel to the plane.
- the outgoing light (e43) and (e45), which are linearly polarized light, have their polarization axes in a direction substantially parallel to the z-axis, that is, in a direction orthogonal to the optical surface (X-axis and y-axis plane). I have.
- the polarizing element (A) is formed of a cholesteric liquid crystal layer.
- the reflection bandwidth of the polarizing element is preferably 200 nm or more.
- the cholesteric liquid crystal layer transmits or reflects circularly polarized light regardless of the angle of incidence. See FIG.
- the cholesteric liquid crystal layer having a broadband selective reflection wavelength band has been found to transmit linearly polarized light when the incident angle of incident light is large as described above, and utilizes this phenomenon. That is, this phenomenon cannot be obtained with a single-pitch cholesteric liquid crystal layer having a selective reflection function only at a specific wavelength, but is obtained only with a cholesteric liquid crystal layer having a wider band and a variable pitch length.
- the polarizing element (A) having the above phenomenon can be obtained by, for example, stacking cholesteric liquid crystal layers having different center wavelengths to form a cholesteric liquid crystal layer having a selective reflection wavelength band covering the entire visible light region. Obtainable. See FIG. Fig. 6 shows the case where three layers of R (red wavelength region), G (green wavelength region), and B (blue wavelength region) are laminated. In addition, since the twist pitch length of the cholesteric liquid crystal layer changes in the thickness direction, it is possible to use a broadband type. See FIG. Thus, the polarizing element having the above phenomenon may be a laminated product of cholesteric liquid crystal layers having a plurality of different selective reflection wavelength bands as shown in FIG. 6, and the pitch length in the thickness direction as shown in FIG. Both continuously changing cholesteric liquid crystal layers Can be used, and both have the same effect.
- a sufficiently wide selective reflection bandwidth is required, preferably 200 nm or more, more preferably 300 nm or more, and even more preferably 400 nm or more.
- the visible light range it is necessary to specifically cover the range of 400 to 600 nm. Since the selective reflection wavelength shifts to the shorter wavelength side according to the incident angle, the extended selective reflection wavelength band should be extended to the longer wavelength side to cover the visible light range regardless of the incident angle.
- the present invention is not limited to this.
- the cholesteric liquid crystal layer is preferably sufficiently thick.
- the thickness is several pitches (2 to 3 times the central wavelength of selective reflection), sufficient selective reflection can be obtained.
- the selective reflection center wavelength is in the range of 400 to 600 nm, considering the refractive index of the cholesteric liquid crystal, it functions as a polarizing element with a thickness of about 11.5 / m.
- the cholesteric liquid crystal layer used in the polarizing element of the present invention preferably has a thickness of 2 / im or more because it has a reflection band in a wide band. It is preferably at least 4 / im, more preferably at least 6 / im.
- the polarizing element (A) it is also preferable to use a broadband cholesteric liquid crystal whose selective reflection band covers the visible light region. This is because the broadband cholesteric liquid crystal layer can effectively provide a phase difference having a large layer thickness.
- the polarizing element (A) obtains circularly polarized light from incident light in the front direction (normal direction), and emits linearly polarized light in a direction perpendicular or parallel to the normal line from incident light at a deep incident angle. I do. Therefore, if the selective reflection wavelength band extends sufficiently to the long wavelength side, the reflectivity in the visible light range will be reduced. The change can be visually recognized as a specular reflector without a constant color tone change.
- the optical element (X) of the present invention comprises a polarizing element (A), a half-wave plate (B), a retardation layer (C), a quarter-wave plate (D), The layers are laminated in the order of the linearly polarized light reflective polarizer (E), and the incident light is transmitted in this order.
- the case where the polarizing element (A1) is used as the polarizing element (A) will be described.
- FIG. 15 shows a conceptual diagram in which the polarization is changed by the wavelength plate.
- F fast axis
- S slow axis.
- 15-1 and 15-2 show conversion from linearly polarized light to circularly polarized light using a quarter-wave plate.
- 15-3 and 15-4 show the conversion from circularly polarized light to linearly polarized light using a quarter-wave plate.
- 15-5 and 15-6 show the conversion in the axial or rotational direction using a 1Z2 wave plate.
- the light emitted from the polarizing element (A1) is as shown in FIG.
- the emitted light transmitted through the polarizing element (A1) transmits through the 1Z2 wavelength plate (B)
- the circularly polarized light in the front direction becomes circularly polarized light with the rotation direction reversed, as shown in Fig. 8,
- the linearly polarized light transmitted in the direction rotates the polarization axis by 90 degrees (see Figures 15-5 and 6).
- Outgoing light (el 1) exists on the z-axis. Corresponds to the outgoing light (el) vertically transmitted through the polarizing element (A1). The output light (el) receives the phase difference of the half-wave plate (B) and is circularly polarized light whose rotation direction is reversed.
- Outgoing light (el 2) Outgoing light (e 2) Force The phase angle of the wave plate (B) is received, and the axis angle is rotated by 90 degrees.
- the emitted light (el2) is elliptically polarized light having an axis parallel to a plane including the z-axis and the y-axis.
- Outgoing light (el 3) Outgoing light (e 3) Force The phase angle of the wave plate (B) is received, and the axis angle is rotated by 90 degrees.
- the emitted light (el3) is linearly polarized light having an axis parallel to a plane including the z-axis and the y-axis.
- Emitted light (el4) Emitted light (e4) Force The phase angle of the wave plate (B) is received, and the axis angle is rotated by 90 degrees.
- the emitted light (el4) is elliptically polarized light having an axis parallel to a plane including the z-axis and the X-axis.
- Outgoing light (el 5) receives the phase difference of the half-wave plate (B), and the axis angle is rotated by 90 degrees.
- the emitted light (el5) has a linear polarization with an axis parallel to the plane containing the z-axis and the X-axis. Light.
- the front phase difference (normal direction) is substantially zero, and the light emitted in the front direction is emitted without changing the polarization.
- linearly polarized light is changed to circularly polarized light to generate a phase difference with respect to incident light inclined with respect to the normal direction.
- the emitted light transmitted through the polarizing element (Al), the half-wave plate (B), and the retardation layer (C) in this order is shown in FIG.
- Emitted light (e21) exists on the z-axis.
- the outgoing light (el 1) is a light beam vertically transmitted through the retardation layer (C).
- the retardation layer (C) has the same circularly polarized light as the emitted light (el 1) because the front retardation is substantially zero.
- Emitted light (e22) exists on a plane including the z-axis and the y-axis.
- the emitted light (el2) is a light beam obliquely transmitted through the retardation layer (C). Due to the phase difference of the retardation layer (C), the outgoing light (e22) is a circularly polarized light whose rotation direction is opposite to that of the outgoing light (el2).
- Outgoing light (e23) exists on a plane including the z-axis and the y-axis.
- the emitted light (el3) is a light beam obliquely transmitted through the retardation layer (C). Due to the phase difference of the retardation layer (C), the outgoing light (e23) is a circularly polarized light whose rotation direction is opposite to that of the outgoing light (el2).
- Emitted light (e24) exists on a plane including the z-axis and the x-axis.
- the emitted light (el4) is a light beam obliquely transmitted through the retardation layer (C). Due to the phase difference of the retardation layer (C), the outgoing light (e24) is a circularly polarized light whose rotation direction is opposite to that of the outgoing light (el4).
- Outgoing light (e25) exists on a plane including the z-axis and the x-axis.
- the emitted light (el4) is a light beam obliquely transmitted through the retardation layer (C). Due to the phase difference of the retardation layer (C), the outgoing light (e25) is a circularly polarized light whose rotation direction is opposite to that of the outgoing light (el4).
- the 1Z4 wave plate (D) can convert circularly polarized light emitted from the retardation layer (C) into linearly polarized light (see FIG. 15).
- the quarter-wave plate (D) is preferably arranged so that its axial direction is about 45 degrees with respect to the X axis and the y axis. Note that the axis angle is preferably in a range of about 45 ° ⁇ 5 °.
- the outgoing light transmitted through the polarizing element (Al), the 1Z2 wavelength plate (B), the retardation layer (C), and the 1Z4 wavelength plate (D) in this order is shown in FIG.
- Outgoing light (e31) exists on the z-axis.
- the circularly polarized output light (e21) is generated by the 14-wavelength plate (D).
- the light is linearly polarized light having a polarization axis in the y-axis direction.
- Outgoing light (e32) exists on a plane including the z-axis and the y-axis.
- the circularly polarized outgoing light (e22) is converted into linearly polarized light having a polarization axis in the X-axis direction by the quarter-wave plate (D).
- the circularly polarized light (e23) is converted into linearly polarized light having a polarization axis in the X-axis direction by the 14-wavelength plate (D).
- Outgoing light (e34) exists on a plane including the z-axis and the X-axis.
- the circularly polarized outgoing light (e24) is converted into linearly polarized light having a polarization axis in the y-axis direction by the quarter-wave plate (D).
- Emitted light exists on a plane including the z-axis and the y-axis.
- the circularly polarized light (e25) is converted into linearly polarized light having a polarization axis in the y-axis direction by the 14-wavelength plate (D).
- the outgoing light transmitted through the retardation layer (C) is transmitted through the linear polarization reflection type polarizer (E).
- the linearly polarized light reflection type polarizer (E) transmits one of orthogonal linearly polarized light and selectively reflects the other.
- Figure 8 shows that the outgoing light (e51 to e55) transmitted through the linearly polarized reflective polarizer (E), which is an optical surface (X-axis-y-axis plane), has the same direction regardless of the incident angle of the incident light (i).
- FIG. 3 is a conceptual diagram showing that linearly polarized light is emitted. In FIG. 8, it has a transmission axis in the y-axis direction and a reflection axis in the X-axis direction. FIG. 8 does not show the incident light (i).
- the linearly polarized light orthogonal to the outgoing light (e) is reflected.
- the linearly polarized light reflective polarizer (E) has a transmission axis direction and a transmission axis of transmitted light transmitted through the polarizing element (A) to the quarter-wave plate (D) in this order. Are arranged in the same direction.
- the linearly polarized light reflective polarizer (E) is arranged so that the transmission axis is in the y-axis direction.
- the emitted light transmitted through the polarizing element (Al), the half-wave plate (B), the retardation layer (C), the quarter-wave plate (D), and the linearly-polarized reflection polarizer (E) in this order is That is, the light transmitted through the optical element (X) of the present invention is shown in FIG.
- Emitted light exists on the z-axis.
- the direction of the polarization axis of the output light (e31) of the linearly polarized light and the transmission axis of the linearly polarized light reflective polarizer (E) are both parallel to the y-axis direction, and the linearly polarized light is emitted as it is.
- Non-emitted light (e62): Exists on a plane including the z-axis and the y-axis.
- the linearly polarized outgoing light (e32) is totally reflected and shielded by the linearly polarized light reflective polarizer (E).
- Emission of linearly polarized light The direction of the polarization axis of the light (32) is the y-axis, while the direction of the transmission axis of the linearly-polarized reflective polarizer (E) is Is the X axis because the axis angles of these linearly polarized lights are orthogonal.
- Non-emitted light (e63): Exists on a plane including the z-axis and the y-axis.
- the linearly polarized outgoing light (e33) is all reflected and blocked by the linearly polarized light reflective polarizer (E).
- the direction of the polarization axis of the output light (33) of the linearly polarized light is the y-axis, while the direction of the transmission axis of the linearly-polarized reflective polarizer (E) is the X-axis. That's why.
- Emitted light exists on a plane including the z-axis and the x-axis.
- the direction of the polarization axis of the output light (e34) of the linearly polarized light and the transmission axis of the linearly polarized light reflective polarizer (E) are both parallel to the y-axis direction, and the linearly polarized light is emitted as it is.
- Emitted light exists on a plane including the z-axis and the x-axis.
- the direction of the polarization axis of the linearly polarized output light (35) and the transmission axis of the linearly polarized light reflective polarizer (E) are both parallel to the y-axis direction, and linearly polarized light is emitted as it is.
- FIG. 9 illustrates a case where the polarizing element (A1) is used as the polarizing element (A).
- the polarizing element (A2) is used as the polarizing element (A)
- X in FIG. It is possible to obtain emitted light having a composition in which the relationship between the axis and the y-axis is reversed.
- the light incident on the optical element (X) in the front direction is a circle in the same direction in the polarizing element (A), the half-wave plate (B), and the retardation layer (C).
- the light is transmitted as polarized light and is converted to linearly polarized light by the quarter-wave plate (D). Further, the linearly polarized light passes through the linearly polarized light reflection type polarizer (E) arranged coaxially with the transmission axis of the linearly polarized light as linearly polarized light.
- the light incident in the oblique direction is transmitted through the polarizing element (A), converted by the half-wave plate (B) into linearly polarized light whose axis is rotated by 90 degrees, and converted into circularly polarized light by the retardation layer (C). Convert. Furthermore, since it is converted into linearly polarized light whose axis direction is rotated by 90 degrees by the quarter-wave plate (D), it is shielded and reflected by the linearly polarized light reflective polarizer (E). If the degree of polarization of the polarizing element (A1) and the linearly polarized light reflective polarizer (E) is sufficiently high, highly efficient linearly polarized light can be obtained with little absorption loss.
- the optical element (X) can obtain linearly polarized light as outgoing light, it is arranged on the light source side of the liquid crystal display device to have both functions of improving brightness and condensing light. In addition, since there is essentially no absorption loss, all light rays having an angle that does not enter the liquid crystal display device are reflected toward the light source and re-sent. The light emitted from the light source in the oblique direction is virtually condensed with only an exit in the front direction Because it is done.
- the optical element (X) of the present invention has a light-collecting property that reflects light in only an arbitrary direction and condenses the light in a necessary direction including the front. Specifically, in a notebook computer or the like in which a liquid crystal display is essential, light is not required in the vertical direction of the panel, but only in the horizontal direction. Can be.
- prism sheets In general, by arranging a prism sheet on a surface light source, it becomes possible to collect light in all directions in the front direction.
- prism sheets Conventionally, prism sheets have been used by laminating a vertical prism sheet for condensing light in the horizontal (left / right) direction to the front and a horizontal prism sheet for condensing light in the vertical (up / down) direction to the front. There were many.
- the prism sheet can be removed or only one.
- the present invention By using the present invention, characteristics that cannot be obtained with a conventional optical element can be easily obtained.
- the optical element according to the present invention it is possible to obtain an optical element that has high transmittance in the front direction, has a good shielding effect in the oblique direction, and has no absorption loss in combination with the selective reflection characteristics of the cholesteric liquid crystal. I can do it. Stable performance can be easily obtained without the necessity of secondary transmission in oblique directions or precise adjustment of wavelength characteristics.
- the optical element of the present invention does not require an air interface, so that it can be used as a laminated integrated product with a polarizing plate and the like, and is advantageous in handling. It is. It has a great effect on thinning. Eliminates diffusers that reduce the total light transmittance and reduces haze because it does not have a visible regular structure like a prism structure, which tends to cause moire etc. (In general, the total light transmittance improves Is easily performed. Of course, there is no problem when used in combination with a prism sheet or the like. For example, it is preferable to use a combination in which the light is condensed to a steep front by using prism sheets and the secondary transmission peak appearing at a large exit angle in the prism sheet is blocked by the optical element of the present invention.
- the direction of the emitted light peak tends to be biased in the direction away from the light source cold cathode tube. This is because the light emitted obliquely from the light guide plate is emitted more in the direction away from the light source cold cathode tubes, and it is difficult to position the peak intensity in the direction perpendicular to the screen.
- the emission peak can be easily matched in the front direction.
- a viewing angle expansion system can be constructed by combining a condensing backlight light source using these optical elements with a diffuser plate that does not cause depolarization and has low backscattering.
- the condensing backlight system using the optical element obtained as described above can easily obtain a light source with higher parallelism than the conventional one.
- parallel light can be obtained by reflected polarized light having essentially no absorption loss, the reflected non-parallel light component returns to the backlight side, and only the parallel light component in the reflected non-parallel light component returns to the backlight side.
- the recycling that is taken out is repeated, and substantially high transmittance, high transmittance and light utilization efficiency can be obtained.
- the polarizing element (A) of the present invention can be formed of a cholesteric liquid crystal layer having a reflection bandwidth of 200 nm or more.
- the cholesteric liquid crystal layer can be formed by stacking a cholesteric liquid crystal layer having a plurality of different selective reflection wavelength bands. Further, a cholesteric liquid crystal layer whose pitch length continuously changes in the thickness direction can be used.
- the cholesteric liquid crystal layer is appropriately adjusted. Select and perform.
- the difference in the axial direction of the linearly polarized light of obliquely transmitted light can be arbitrarily prepared depending on the stacking order of the cholesteric liquid crystal layers and the manufacturing method.
- the transmitted light in the oblique direction is uniquely defined, and only those having a polarization axis of linearly polarized light substantially parallel to the normal to the optical surface. I can't get it.
- the selective reflection wavelength band of the polarizing element (A) includes at least 550 nm.
- each cholesteric liquid crystal layer is appropriately provided with a plurality of cholesteric liquid crystal layers so that the reflection bandwidth of the laminate is 200 nm or more. Select and stack layers.
- the cholesteric liquid crystal layer is not particularly limited as long as an appropriate one is used.
- a liquid crystal polymer that exhibits cholesteric liquid crystallinity at high temperature or a liquid crystal monomer and optional Polymerizable liquid crystals obtained by superimposing a chiral agent and an alignment assistant by irradiation with ionizing radiation such as an electron beam or ultraviolet light or heat, or a mixture thereof.
- the liquid crystal properties may be either lyotropic or thermopic, but from the viewpoint of easy control and easy formation of a monodomain, it is desirable that the liquid crystal be thermopic.
- the cholesteric liquid crystal layer can be formed by a method according to a conventional alignment treatment.
- a film of polyimide, polybutyl alcohol, polyester, polyester, polyamide imide, polyether imide, etc. is formed on a support base material such as triacetyl cellulose or amorphous polyolefin having a birefringence retardation as small as possible.
- a fine abrasive such as Bengala and has fine irregularities with a fine alignment control force on the surface, or a liquid crystal control force by irradiating the base film with an azobenzene compound or other light.
- Liquid crystal polymer on an appropriate alignment film consisting of a substrate on which an alignment film that generates It is developed and heated to above the glass transition temperature and below the isotropic phase transition temperature, and cooled to below the glass transition temperature with the liquid crystal polymer molecules in a state of being in a planar alignment, forming a solidified layer in which the orientation is fixed.
- the structure may be fixed by irradiation of energy such as ultraviolet rays or ion beams at the stage when the alignment state is formed.
- the liquid crystal polymer film is formed, for example, by applying a solution of a liquid crystal polymer in a solvent by a spin coating method, a mouth coating method, a flow coating method, a printing method, a dip coating method, a casting film forming method, a bar coating method, a gravure printing method. Etc., and can be carried out by, for example, a method of developing a thin layer and drying it as necessary.
- the solvent examples 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; cycloheptane And N-methylpyrrolidone tetrahydrofuran and the like can be appropriately used.
- chlorinated solvents such as methylene chloride, trichloroethylene and tetrachloroethane
- ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone
- aromatic solvents such as toluene
- cycloheptane And N-methylpyrrolidone tetrahydrofuran and the like can be appropriately used.
- a heated melt of a liquid crystal polymer preferably a heated melt in a state of exhibiting an isotropic phase
- a heated melt of a liquid crystal polymer is developed in accordance with the above, and if necessary, further developed into a thin layer while maintaining its melting temperature, to thereby form a solid.
- a method for causing the above to occur can be adopted. This method does not use a solvent. Therefore, the liquid crystal polymer can be developed by a method with good hygiene of the working environment.
- a cholesteric liquid crystal layer superimposing method with an alignment film interposed therebetween may be used as necessary for the purpose of thinning and the like.
- the cholesteric liquid crystal layer thus obtained can be peeled off from the supporting base material and the Z-oriented base material used during film formation and transferred to another optical material, or used without peeling.
- the method of laminating the cholesteric liquid crystal layers includes a method of bonding a plurality of individually formed cholesteric liquid crystal layers with an adhesive material and an adhesive material, a method of swelling and dissolving the surface with a solvent or the like, and a method of press-fitting, A pressing method may be used while applying ultrasonic waves or the like.
- a method of applying a cholesteric liquid crystal layer having another selective reflection center wavelength on the layer for example, may be used.
- the cholesteric liquid crystal layer in which the pitch length continuously changes in the thickness direction may be obtained by irradiating the composition containing the same liquid crystal monomer as described above with an ionizing radiation such as an electron beam or an ultraviolet ray by the following method.
- an ionizing radiation such as an electron beam or an ultraviolet ray
- a method utilizing the difference in polymerization rate due to a difference in ultraviolet transmittance in the thickness direction Japanese Patent Application Laid-Open No. 2000-95883
- a method of extracting with a solvent to form a concentration difference in the thickness direction Japanese Patent No. 3062150
- the second polymerization by changing the temperature after the first polymerization US Pat. No. 6,057,082.
- a method in which a step of polymerizing and curing by irradiating ultraviolet rays from the substrate side is performed, and a difference in polymerization rate in the thickness direction due to inhibition of oxygen polymerization is increased by irradiating ultraviolet rays from the substrate side JP-A-2000-139953) Etc. are preferably used.
- a cholesteric liquid crystal layer having a wider reflection wavelength band can be obtained by the following method.
- the liquid crystal mixture is brought into contact with a gas containing oxygen at a temperature of 20 ° C. or more at an ultraviolet irradiation intensity of 20 200 mWZcm 2 .
- Step (2) and then, in a state where the liquid crystal layer is in contact with a gas containing oxygen, at a temperature of 20 ° C or more, at a UV irradiation intensity lower than that of Step (1) for 10 seconds or more,
- a method of performing the step of irradiating ultraviolet rays from the alignment substrate side (3), followed by the step of irradiating ultraviolet rays in the absence of oxygen (4) Japanese Patent Application No. 2003-93963.
- the liquid crystal mixture is in contact with a gas containing oxygen, and at a temperature of 20 ° C. or more, an ultraviolet irradiation intensity of 1.1 mW / cm 2 and 0.2 mW / cm 2.
- there is a method of performing the ultraviolet irradiation step (2) in the absence of oxygen Japanese Patent Application No. 2003-94307).
- the liquid crystal mixture is in contact with a gas containing oxygen, at a temperature of 20 ° C. or more, at an ultraviolet irradiation intensity of 20 to 200 mW / cm 2 .
- a method of irradiating with ultraviolet rays (3) can be mentioned (Japanese Patent Application No. 2003-94605).
- a cholesteric liquid crystal layer having a broad reflection wavelength band and excellent heat resistance can be obtained.
- a liquid crystal mixture containing a polymerizable mesogen compound (a), a polymerizable chiral agent (b), and a photopolymerization initiator (c) is subjected to ultraviolet polymerization between two substrates (Japanese Patent Application No. 2003-143,197). -No. 4346, Japanese Patent Application 200
- the polymerizable mesogen compound (a) and the polymerizable chiral agent (b) that form the cholesteric liquid crystal layer will be described below. These materials include a cholesteric liquid crystal layer and a cholesteric liquid crystal layer whose pitch length continuously changes in the thickness direction. Can be used for any of the cholesteric liquid crystal layers to be laminated
- the polymerizable mesogen compound (a) a compound having at least one polymerizable functional group and having a mesogen group composed of a cyclic unit or the like is preferably used.
- the polymerizable functional group include an acryloyl group, a methacryloyl group, an epoxy group, and a butyl ether group. Among them, an atalyloyl group and a methacryloyl group are preferable. Further, by using a compound having two or more polymerizable functional groups, a crosslinked structure can be introduced to improve the durability.
- Examples of the cyclic unit to be a mesogen group include biphenyl, phenylbenzoate, phenylcyclohexane, azoxybenzene, azomethine, azobenzen, phenylpyrimidine, diphenylacetylene, and diphenylbenzoate. And bicyclohexanes, cyclohexylbenzenes and terphenyls.
- the terminal of these cyclic units may have a substituent such as a cyano group, an alkyl group, an alkoxy group, a halogen group, or the like.
- the mesogen group may be bonded via a spacer that imparts flexibility.
- the spacer portion examples include a polymethylene chain and a polyoxymethylene chain.
- the number of repeating structural units forming the spacer portion is appropriately determined by the chemical structure of the mesogenic portion, but the repeating units of the polymethylene chain are 0 to 20, preferably 2 to 12, and the repeating units of the polyoxymethylene chain. Is 0-10, preferably 1-3
- the molar extinction coefficient is 0.1 , 50-1 OOOOdmVol- 1 @ 334 nm, and 10000-SOOOOdmol- 1 @ 314 nm is more preferable.
- the molar extinction coefficient is 0.1 , 100 0- AOOOdm ol- ⁇ is the SS nm, 30000- AOOOOdm ol- 1 ® 314 ⁇ m and more preferably Les,.
- Molar extinction coefficient is 0.1 dm or'cm " 1 @ 365nm, 10dm 3 m It is difficult to widen the bandwidth without a sufficient difference in polymerization rate when the wavelength is smaller than Mnm. on the other hand, 30000dm mol — If it is larger than 14 nm, the polymerization may not completely proceed and the curing may not be completed.
- the molar extinction coefficient is a value obtained by measuring the spectrophotometric spectrum of each material and measuring the resulting absorbance at 365 nm, 334 nm, and 314 nm.
- the polymerizable mesogen compound (a) having one polymerizable functional group is, for example, represented by the following general formula:
- H represents, R represents —H or —CH, and X represents the general formula (2):
- a is an integer of 03
- b is an integer of 0 to 12
- c is 0 or 1
- Examples of the polymerizable chiral agent (b) include LC756 manufactured by BASF.
- the amount of the polymerizable chiral agent (b) to be blended is preferably about 11 to 20 parts by weight based on 100 parts by weight of the polymerizable mesogen compound (a) and the polymerizable chiral agent (b) in total. 3-7 parts by weight are more suitable.
- the helical torsional force (HTP) is controlled by the ratio of the polymerizable mesogen compound (a) and the polymerizable chiral agent (b). By setting the ratio within the above range, the reflection band can be selected so that the reflection spectrum of the obtained cholesteric liquid crystal film can cover a long wavelength region.
- the liquid crystal mixture usually contains a photopolymerization initiator (c).
- a photopolymerization initiator Various photopolymerization initiators (c) can be used without particular limitation.
- photopolymerization initiators c
- the amount of the photopolymerization initiator is preferably about 0.01 to 10 parts by weight, based on 100 parts by weight of the total of the polymerizable mesogen compound (a) and the polymerizable chiral agent (b). Weight parts are more suitable.
- the polymerizable ultraviolet absorber (d) a compound having at least one polymerizable functional group and having an ultraviolet absorbing function can be used without particular limitation.
- Specific examples of such a polymerizable ultraviolet absorber (d) include 1-13 ⁇ 48_93 manufactured by Otsuka Chemical Co., Ltd., and UVA935LH manufactured by BASF.
- the amount of the polymerizable ultraviolet absorber (d) is preferably about 0.01 to 10 parts by weight based on 100 parts by weight of the polymerizable mesogen compound (a) and the polymerizable chiral agent (b) in total. 2-5 parts by weight are more preferred.
- the mixture may be mixed with an ultraviolet absorber to increase the difference in ultraviolet exposure intensity in the thickness direction.
- an ultraviolet absorber having a large molar extinction coefficient.
- the mixture can be used as a solution.
- Solvents used for preparing the solution are usually halogenated hydrocarbons such as chloroform, dichloromethane, dichloroethane, tetrachloroethane, chloroethylene, tetrachloroethylene, and cyclobenzene, phenol, parachlorophenol, and the like.
- Phenols aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene, etc., acetone, methyl ethyl ketone, ethyl acetate, tert-butyl alcohol, glycerin, ethylene glycol Kohl, triethylene glycol, ethylene bricol monomethyl ether, diethylene glycol dimethyl ether, ethylcellosolve, butylcellosolve, 2_pyrrolidone, N_methyl_2_pyrrolidone, pyridine, triethynoleamine, tetrahydride Furan,-dimethylformamide, dimethyl ⁇ Seth, dimethyl sulfoxide, can be used Asetonitoriru, butyronitrile, carbon disulfide, cyclopentanone, and cyclohexanone.
- the solvent to be used is not particularly limited, but methyl ethyl ketone, cyclohexanone, cyclopentanone and the like are preferable.
- the concentration of the solution depends on the solubility of the thermopickable liquid crystal compound and ultimately the thickness of the target cholesteric liquid crystal film, so it cannot be said unconditionally.
- the content is usually about 3 to 50% by weight.
- the above-described alignment base material can be used. The same method can be adopted for the alignment method.
- Examples of the half-wave plate (B) include polyethylene naphthalate, polyethylene terephthalate, polycarbonate, norbornene resins represented by JSR ARTON, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, and others.
- a film obtained by uniaxially stretching a resin film of polyolefin, polyarylate, polyamide, or the like, or a film obtained by improving the viewing angle characteristics by biaxially stretching, or a film in which the nematic alignment state of a rod-like liquid crystal is fixed is used. be able to.
- the half-wave plate (B) is a broadband wave plate having a phase difference characteristic that functions as a substantially half-wave plate in the entire visible light range in order to align the optical characteristics of each color and suppress coloring. Preferably, there is. If the change in the phase difference value for each wavelength is too large, a difference occurs in the polarization characteristics for each wavelength, which affects the shielding performance for each wavelength and is not preferable because it is visually recognized by being colored.
- the half-wave plate (B) that has a strong force has a maximum in-plane refractive index on the X axis, a direction perpendicular to the X axis on the Y axis, and a refractive index in each axial direction of nx, ny and thickness d. (nm), it is preferable that the front phase difference value: ( ⁇ y) X d at each wavelength in the light source wavelength band (420 to 650 nm) is within 1/2 wavelength ⁇ 10%.
- the variation of the phase difference value within the light source wavelength band is preferably as small as possible, preferably within ⁇ 7%, and more preferably within ⁇ 5%.
- the half-wave plate (B) has a phase difference equivalent to a half wavelength irrespective of the wavelength of the incident light by controlling the wavelength dispersion characteristics by off-axis lamination of different types of retardation plates or molecular design. Can be given.
- Such features Polybutyl alcohol is a typical example of a retardation plate that has properties, and materials that are molecularly designed for optics include norbornene-based resin films such as JSR's Arton and Nippon Zeon's Zeonor, and Teijin's Pure Ace WR and the like.
- the 1Z2 wavelength plate (B) functions as a 1Z2 wavelength plate for obliquely incident light.
- the phase difference value changes, and a phenomenon generally occurs that deviates from the originally required phase difference value.
- a phase difference equivalent to a vertically incident light beam can be given to an obliquely incident light beam.
- the control coefficient of the retardation value in the thickness direction is generally defined by the Nz coefficient.
- ⁇ 2.5 and Nz ⁇ l More preferably, _2 ⁇ Nz ⁇ 0.5.
- a typical example of a retardation plate having such a thickness direction control is an NRZ film manufactured by Nitto Denko. It should be noted that the technique disclosed in Patent Document 17 cannot prevent the secondary transmission in the oblique direction. This is because it is impossible to achieve both the manifestation of the phase difference in the oblique direction and the suppression of the increase in the phase difference in the oblique direction. Here is the advantage s of the present invention.
- the half-wave plate (B) can be composed of one retardation plate and can be used by laminating two or more retardation plates so that a desired retardation can be obtained.
- the thickness of the half-wave plate (B) is usually 0.5 to 200 zm, preferably S, and particularly preferably 100 ⁇ ⁇ ⁇ ⁇ .
- the retardation layer (C) has a phase difference of almost zero in the front direction and generates a phase difference with respect to incident light inclined from the normal direction.
- the front phase difference is desirably ⁇ / 10 or less because the purpose is to maintain polarized light that is vertically incident.
- the phase difference layer (C) generates a phase difference with respect to incident light inclined from the normal direction. It is. For incident light from an oblique direction, the angle is appropriately determined by an angle at which total reflection is performed so as to efficiently convert the polarization. For example, in order to completely reflect the light at an angle of about 60 ° from the normal, the phase difference measured at 60 ° should be determined to be about / 4. However, the retardation layer (C): The C-plate and the half-wave plate (B) are combined, and the selective reflection wavelength band of the C-plate is set to a longer wavelength side than the visible light range. The required characteristics can be obtained even when the phase difference of the plate measured at an angle of 30 ° from the normal direction is about 1Z32 wavelength.
- the retardation layer (C) is provided with a normal direction force to the incident light inclined. Those that generate a phase difference are used.
- the phase difference of the retardation layer (C) with respect to the obliquely incident light is appropriately adjusted according to the polarizing element (A).
- the material of the retardation layer (C) is not particularly limited as long as it has the above-mentioned optical characteristics.
- fixed cholesteric liquid crystals having a reflection wavelength outside the visible light range (380 nm to 780 nm), fixed rod-like liquid crystal homeotropic aperture alignment, discotic liquid crystal columnar alignment ⁇ nematic Examples include those utilizing orientation, those in which negative uniaxial crystals are oriented in-plane, and those in which biaxially oriented polymer films are used.
- a film obtained from at least one polymer selected from the group consisting of polyamide, polyimide, polyester, poly (ether ketone), poly (amide-imide), and poly (ester-imide) can be used.
- These films are obtained by applying a solution obtained by dissolving the polymer in a solvent to a substrate, and then subjecting the solution to a drying step.
- the substrate is preferably formed using a substrate having a dimensional change rate of 1% or less in the drying step. Further, there is a liquid crystal in which the alignment direction of the nematic liquid crystal or discotic liquid crystal is fixed so that the alignment direction changes continuously in the thickness direction.
- the C-plate in which the homeotropic opening pick alignment state is fixed, a liquid crystalline thermoplastic resin or liquid crystal monomer that exhibits nematic liquid crystallinity at high temperature, and an alignment aid, if necessary, are irradiated with ionizing radiation such as electron beams or ultraviolet rays.
- ionizing radiation such as electron beams or ultraviolet rays.
- Polymerizable liquid crystal polymerized by heat or heat, or a mixture thereof is used.
- the liquid crystal properties may be either lyotropic or thermopick, but from the viewpoint of easy control and easy formation of a monodomain, it is desirable that the liquid crystal be a thermopick liquid crystal.
- the homeotropic aperture alignment can be obtained, for example, by coating the birefringent material on a film on which a vertical alignment film (such as a long-chain alkylsilane) has been formed, and developing and fixing a liquid crystal state.
- a C-plate using a discotic liquid crystal is a discotic liquid crystal having a negative uniaxial property, such as a phthalocyanine or triphenylene compound having an in-plane molecular force S as a liquid crystal material.
- the material is fixed by developing a nematic phase or a columnar phase.
- the negative uniaxial inorganic layered compound is described in detail in, for example, JP-A-6-82777.
- the C plate utilizing biaxial orientation of the polymer film has a well-balanced biaxial stretching method for a polymer film having a positive refractive index anisotropy, a method of pressing a thermoplastic resin, and a method of performing a parallel orientation. Crystal force can be obtained by a method such as cutting out.
- Each of the retardation layers (C) is composed of one retardation plate, and may be used by laminating two or more retardation plates so that a desired retardation is obtained. it can.
- the 1/4 wavelength plate (D) a material whose phase difference is controlled using the same material as the 1Z2 wavelength plate (B) can be used.
- the 1Z4 wave plate (D) is also an approximately 1Z4 wave plate over the entire visible light range.
- the front-side retardation force at each wavelength in the light source wavelength band (420 to 650 nm), which is preferably a broadband wave plate that functions well, is within 1/4 wavelength ⁇ 10%. Preferably it is within ⁇ 7%, more preferably ⁇ 5% or less.
- Nz ⁇ l More preferably, Nz ⁇ 0.5.
- the quarter-wave plate (D) may be composed of two or more retardation plates so that a desired retardation may be obtained even if the retardation plate is composed of a retardation plate having a profile.
- the thickness of the quarter-wave plate (D) is usually 0.5 to 200 zm, and the thickness is preferably S, particularly preferably 100 ⁇ .
- the linearly polarized light reflective polarizer (E) has different refractive indices used in grid polarizers, multilayer thin film laminates of two or more layers made of two or more materials having a difference in refractive index, beam splitters, etc.
- a material that generates a phase difference by stretching represented by polyethylene naphthalate, polyethylene terephthalate, and polycarbonate, an acryl-based resin represented by polymethyl methacrylate, and norbornene represented by ARTON manufactured by JSR Corporation
- a resin obtained by uniaxially stretching a resin having a small amount of retardation, such as a system resin, as a multilayer laminate can be used.
- Specific examples of the linearly polarized light reflection type polarizer (E) include DBEF manufactured by 3M, PCF manufactured by Nitto Denko Eno Earth, and the like.
- the selective reflection wavelength bandwidth of the linearly polarized light-reflecting polarizer (E) is preferably 200 nm or more, more preferably 300 nm or more, and still more preferably 400 nm or more, as in the case of the polarizing element (A).
- the selective reflection wavelength shifts to the shorter wavelength side according to the angle of incidence, so it is desirable that the expanded selective reflection wavelength band be extended mainly to the longer wavelength side. Is not a limitation.
- the polarizing element (A) and the linearly-polarized reflection polarizer (E) have a selective reflection wavelength band at least. 550 nm, preferably 100 nm or more, more preferably 200 nm or more, and even more preferably 300 nm or more.
- the optical element of the present invention can be used not only by simply arranging it in the optical path but also by bonding. This is because the transmittance is controlled not by the surface shape but by the polarization characteristics of the optical element, so that an air interface is not required.
- the layers are desirably laminated using an adhesive or a pressure-sensitive adhesive from the viewpoints of workability and light use efficiency.
- the adhesive or the pressure-sensitive adhesive is transparent, has no absorption in the visible light region, 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 is 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 base material. It is also possible to form an alignment film or the like as appropriate and directly form each layer sequentially.
- Each layer and the (adhesive) adhesive layer may be provided with isotropic scattering by further adding particles to adjust the degree of diffusion and adjustment as necessary, or may be provided with an ultraviolet absorber, an antioxidant, or the like.
- an ultraviolet absorber for the purpose of imparting leveling property during film formation, a surfactant or the like can be appropriately added.
- 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.
- specular reflectivity of the rear-side reflector is high, the reflection angle is preserved, and light cannot be emitted in the front direction, resulting in light loss. Therefore, it is desirable to dispose a diffuse reflector in order to increase the scattered reflection component in the front direction without preserving the reflection angle of the reflected return light beam.
- the light-collecting characteristics according to the present invention can control light-collecting in the front direction even with a diffusion surface light source such as a direct-type backlight or an inorganic / organic EL element.
- the diffusion plate can be obtained by embedding fine particles having different refractive indices in a resin, in addition to a material having a surface irregularity. This diffusion plate may be sandwiched between the optical element (X) and the backlight, or may be bonded to the optical element (X).
- the optical element (X) is suitably applied to a liquid crystal display device in which polarizing plates (P) are arranged on both sides of a liquid crystal cell (LC), and the optical element (X) is a polarizing plate on a side of a light source of the liquid crystal cell. Applies to (P) side.
- FIG. 14 shows a structure in which a polarizing plate (P) is laminated on a linearly polarized light reflective polarizer (E).
- the optical element (X) is arranged such that the polarizing element (A) is on the light source side.
- FIGS. 16 to 19 illustrate a liquid crystal display device.
- FIGS. 16 to 19 illustrate the case where the optical element (Y) is used.
- the reflector (RF) is shown together with the light source (L).
- FIG. 16 shows a case where a direct-type backlight (L) is used as a light source (L).
- FIG. 17 shows a case where a sidelight type light source (L) is used for the light guide plate (S).
- FIG. 18 shows a case where the planar light source (L) is used.
- FIG. 19 shows a case where a prism sheet (Z) is used.
- a diffusion plate on the liquid crystal cell viewing side with no backscattering and depolarization on the liquid crystal display device combined with the above-mentioned parallelized backlight By stacking a diffusion plate on the liquid crystal cell viewing side with no backscattering and depolarization on the liquid crystal display device combined with the above-mentioned parallelized backlight, a favorable near-front area can be obtained.
- the viewing angle can be expanded by diffusing the light beam having the display characteristics and obtaining uniform and good display characteristics within the entire viewing angle.
- a diffusion plate having substantially no backward scattering is used.
- the diffusion plate can be provided as 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.
- a film that does not substantially eliminate polarized light is desirable.
- JP-A-2000-347006 Japanese Patent Application Laid-Open No. 2000-347007 discloses a fine particle-dispersed diffusion plate.
- the viewing angle widening film When the viewing angle widening film is positioned outside the polarizing plate, the light parallelized to the liquid crystal layer and the polarizing plate is transmitted. Therefore, in the case of a TN liquid crystal cell, a viewing angle compensating retardation plate is particularly used. It is not necessary. In the case of an STN liquid crystal cell, it is only necessary to use a retardation film in which only the front characteristics are well compensated. In this case, since the viewing angle widening film has an air surface, it is possible to adopt a type using a refraction effect due to the surface shape.
- a viewing angle widening film having a regular structure inside such as an existing microlens array film or hologram film, a black matrix of a liquid crystal display device or a conventional parallel light conversion system of a backlight.
- This method interfered with microstructures such as microlens array / prism array / louver / micromirror array and caused moire.
- the regular structure is not 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 film and the arrangement order. Therefore, the viewing angle widening film 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.
- substantially no back scattering, no depolarization, and the like are described in JP-A-2000-347006 and JP-A-2000-347007.
- Haze 80 with a light scattering plate like / o—90. / o is preferably used.
- a primary light condensing means is preferably one that condenses light within ⁇ 60 degrees, and more preferably one that condenses light within ⁇ 50 degrees.
- liquid crystal display device is manufactured by appropriately using various optical layers and the like according to a conventional method.
- a polarizing plate having a protective film on one or both sides of a polarizer is generally used.
- the polarizer is not particularly limited, and various types can be used.
- the polarizer include a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene-butyl acetate copolymer-based partially modified film, and iodine and dichroic dyes. Uniaxially stretched by adsorbing the dichroic substance described above, polyene-based oriented finolems such as dehydration products of polyvinyl alcohol and dehydrochlorination products of polyvinyl chloride, and the like.
- a polarizer composed of a polybutyl alcohol-based film and a dichroic substance such as iodine is preferred.
- the thickness of these polarizers is not particularly limited, but is generally about 5 to 80 ⁇ .
- a polarizer which is obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching is produced by, for example, dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length.
- iodine an aqueous solution of iodine and stretching it to 3 to 7 times its original length.
- washing the polyvinyl alcohol-based film with water not only removes stains and anti-blocking agents on the surface of the polyvinyl alcohol-based film, but also prevents unevenness such as uneven dyeing by swelling the polyvinyl alcohol-based film. There is also an effect. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be stretched and then dyed with iodine. The film can be stretched even in an aqueous solution of boric acid or potassium iodide or in a water bath.
- a material for forming the transparent protective film provided on one or both surfaces of the polarizer a material having excellent transparency, mechanical strength, heat stability, moisture shielding property, isotropy, and the like is preferable.
- polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate
- cenorellose-based polymers such as diacetinoresenorelose and triacetinoresenorelose.
- examples include polymers, acrylic polymers such as polymethyl methacrylate, styrene polymers such as polystyrene and acrylonitrino-styrene copolymer (AS resin), and polycarbonate polymers.
- polyethylene, polypropylene, polyolefin having a cyclo- or norbornene structure polyolefin-based polymers such as ethylene-propylene copolymer, butyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamide, imide-based polymers, and sulfone-based polymers
- Polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, butyl alcohol polymers, vinylidene chloride polymers, butyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers Or blends of the above polymers are also examples of the polymer forming the transparent protective film.
- 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.
- Japanese Patent Application Laid-Open No. 2001-343529 (W01 / 37007) t describes a polymer finolem described herein, such as (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in a side chain. And (B) a resin composition containing 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.
- As the film a film made of a mixed extruded product of a resin composition or the like can be used.
- the thickness of the protective film can be determined as appropriate, but is generally about 500 / im, such as workability such as strength and handleability, and thin layer life. In particular, one 300 ⁇ 300 ⁇ force S is preferable, and 5-200 zm is more preferable.
- nx and ny are the main refractive indices in the film plane, nz is the refractive index in the finolem thickness direction, and d is the film thickness direction
- a protective film having a retardation of 90 nm- + 75 nm is preferably used.
- the difference value (Rth) is more preferably _80 nm- + 60 nm, particularly preferably _70 nm- + 45 nm.
- the protective film a cellulosic polymer such as triacetyl cellulose is preferable in terms of polarization characteristics and durability. Particularly, a triacetyl cellulose film is preferable.
- the same polymer material may be used on both sides of the polarizer, or a protective film made of a different polymer material may be used.
- the polarizer and the protective film are usually in close contact with each other via an aqueous pressure-sensitive adhesive or the like.
- water-based adhesive examples include an isocyanate-based adhesive, a polybutyl alcohol-based adhesive, a gelatin-based adhesive, a bull-based latex-based, a water-based polyurethane, and a water-based polyester.
- 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 sticking, 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.
- a cured film made of an appropriate ultraviolet-curable resin such as an acrylic or silicone resin is excellent in hardness and sliding properties. Can be formed on the surface of the transparent protective 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-sticking treatment is performed for the purpose of preventing adhesion to the adjacent layer.
- the anti-glare treatment is performed for the purpose of preventing external light from being reflected on the surface of the polarizing plate and hindering the visibility of light transmitted through the polarizing plate.
- a sand blasting method and an embossing method are used.
- the transparent protective film can be formed by giving a fine uneven structure to the surface of the transparent protective film by an appropriate method such as a surface roughening method or a method of blending transparent fine particles.
- Examples of the fine particles contained in the formation of the surface fine unevenness include silica, anoremina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle size of 0.5 to 50 ⁇ m.
- Transparent fine particles such as inorganic fine particles that may be conductive and organic fine particles made of a crosslinked or uncrosslinked polymer or the like are used.
- the amount of fine particles used is such that the fine surface unevenness structure is formed.
- 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-staking layer, diffusion layer, anti-glare layer and the like can be provided on the transparent protective film itself, or as a separate optical layer separate from the transparent protective film. It can also be provided.
- a retardation plate is laminated on a polarizing plate as a viewing angle compensation film and used as a wide viewing angle polarizing plate.
- the viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction, not perpendicular to the screen.
- the retardation plate a quarter-wave plate or a half-wave plate appropriate for the purpose of use is used. As these materials, those in which the phase difference is controlled using the same material as the 1Z2 wavelength plate (B) can be used.
- a viewing angle compensating retardation film examples include a biaxially stretched film, a birefringent film stretched in two orthogonal directions, and a bidirectionally stretched film such as an obliquely oriented film.
- a biaxially stretched film examples include a film obtained by bonding a heat shrinkable film to a polymer film and subjecting the polymer film to a stretching treatment and / or shrinkage treatment under the action of the contraction force caused by heating, or a film obtained by obliquely orienting a liquid crystal polymer.
- 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 due to the liquid crystal cell, or expanding the viewing angle for good visibility.
- the triacetyl cellulose film supports the liquid crystal polymer alignment layer, especially the optically anisotropic layer composed of the discotic liquid crystal polymer tilt alignment layer, in view of achieving a wide viewing angle with good visibility.
- the optically-compensated phase difference plate is preferably used.
- the optical layers to be laminated in practical use are not particularly limited.
- one or two optical layers that may be used for forming a liquid crystal display device such as a reflector or a semi-transmission plate are provided.
- the above can be used.
- a reflective polarizing plate or a semi-transmitting polarizing plate in which a reflecting plate or a semi-transmitting reflecting plate is further laminated on an elliptically polarizing plate or a circular polarizing plate is exemplified.
- the reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects and reflects incident light from the 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 is formed by attaching a foil made of a reflective metal such as aluminum or the like to one surface of a protective film that has been mat-treated as necessary.
- a reflective layer is formed by attaching a foil made of a reflective metal such as aluminum or the like to one surface of a protective film that has been mat-treated as necessary.
- a protective film that has been mat-treated as necessary.
- the reflection layer having the fine uneven structure described above has an advantage that the incident light is diffused by irregular reflection to prevent a directional glare and to suppress uneven brightness.
- the protective film containing fine particles also has an advantage that the incident light and its reflected light are diffused when passing through the protective film, so that uneven brightness can be further suppressed.
- the reflection layer having a fine uneven structure reflecting the fine uneven structure on the surface of the protective film is formed by depositing a metal by an appropriate method such as a vapor deposition method such as a vacuum evaporation method, an ion plating method, or a sputtering method or a plating method. It can be carried out by, for example, directly attaching to the surface of the transparent protective layer.
- a vapor deposition method such as a vacuum evaporation method, an ion plating method, or a sputtering method or a plating method. It can be carried out by, for example, directly attaching to the surface of the transparent protective layer.
- the reflective plate can also be used as a reflective sheet in which a reflective layer is provided on an appropriate film according to the transparent film. Since the reflective layer is usually made of a 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 a 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.
- a transflective polarizing plate is usually provided on the back side of a liquid crystal cell.
- a liquid crystal display device or the like When a liquid crystal display device or the like is used in a relatively bright atmosphere, an image is displayed by reflecting incident light from the viewing side (display side). However, in a relatively dark atmosphere, it is possible to form a liquid crystal display device or the like that displays an image using a built-in light source such as a backlight built in the back side of a transflective polarizing plate. .
- the transflective polarizing plate can save energy for using a light source such as a backlight in a bright atmosphere, and can be used to form a liquid crystal display device that can be used with a built-in light source even in a relatively dark atmosphere. Useful.
- the polarizing plate may be formed by laminating a polarizing plate like the above-mentioned polarized light separating type polarizing plate and two or three or more optical layers. Therefore, a reflective elliptically polarizing plate or a transflective elliptically polarizing plate obtained by combining the above-mentioned reflective polarizing plate, transflective polarizing plate and retardation plate may be used.
- the above-mentioned elliptically polarizing plate or reflective elliptically polarizing plate is obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination.
- the elliptically polarizing plate and the like can be formed by sequentially and separately stacking them in the manufacturing process of the liquid crystal display device so as to form a combination of a (reflection type) polarizing plate and a retardation plate.
- An optical film such as an elliptically polarizing plate formed by laminating has an advantage that the stability of quality and the laminating workability are excellent, and the manufacturing efficiency of a liquid crystal display device or the like can be improved.
- 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 arrangement angle according to the target retardation characteristics and the like.
- the adhesive and the pressure-sensitive adhesive are not particularly limited.
- it is based on polymers such as acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / biel chloride copolymers, modified polyolefins, rubbers such as epoxy, fluorine, natural rubber, and synthetic rubber. It is possible to appropriately select and use a polymer.
- those having excellent optical transparency, exhibiting appropriate wettability, cohesiveness and adhesive tackiness, and having excellent weather resistance and heat resistance are 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, in particular, tackifier resins, fillers, pigments, coloring agents made of glass fibers, glass beads, metal powders, and other inorganic powders. An additive such as an inhibitor may be contained. Further, an adhesive layer containing fine particles and exhibiting light diffusibility 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.
- the solvent an organic solvent such as toluene or ethyl acetate or a solvent corresponding to 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 surfaces of a polarizing plate or an optical film as a superposed layer of different compositions or types.
- the thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use, adhesive strength, and the like, and is generally 1 to 500 x m, preferably 5 to 200 zm, more preferably 10 to 100 m.
- a separator is temporarily attached to an exposed surface of the adhesive layer or the like for the purpose of preventing contamination or the like until it is put to practical use, and covered. This can prevent the adhesive layer from coming into contact with the adhesive layer in a normal handling state.
- a suitable thin leaf such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, a net, a foamed sheet, a metal foil, or a laminate thereof may be used as a separator, if necessary, and a silicone-based separator.
- Any suitable material according to the related art such as a material coated with a suitable release agent such as a long mirror alkyl-based or fluorine-based molybdenum sulfide, or the like can be used.
- each layer such as the optical element or the like and the adhesive layer may be, for example, a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex salt compound. And those having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorbent.
- (Distortion rate): In order to evaluate the distortion rate of the polarizing element, the transmission spectrum of the sample was measured using an instantaneous multiphotometer (MCPD-2000, manufactured by Otsuka Electronics Co., Ltd.). When natural light is emitted and the sample is placed perpendicular to the light emission (measured light emitted from the front). In each case where the sample was set at an angle of 60 ° from the vertical direction (measurement of the emitted light at 60 °), the state of the light transmitted through the sample was measured using a polarizing plate arranged on the output side. The transmission spectrum at every turn was measured. The polarizing plate used was a Gram-Thomson prism polarizer manufactured by Sigma Koki (extinction ratio 0.00001 or less). The distortion rate was obtained from the following formula. Distortion minimum transmission / maximum transmission.
- phase difference is defined as the direction of the maximum in-plane refractive index on the X axis, the direction perpendicular to the X axis as the Y axis, and the thickness direction of the film as the Z axis.
- the refractive indices are nx, ny, and nz
- the refractive indices at 550 nm, nx, ny, and nz were measured with an automatic birefringence measurement device (Oji Scientific Instruments Co., Ltd., automatic birefringence meter KOBRA21ADH).
- the front phase difference: (nx—ny) X d was calculated.
- the phase difference measured when tilted can be measured by the automatic birefringence measuring device described above.
- the tilt phase difference is: (nx-ny) X d when tilting.
- Nz coefficients were calculated.
- a light table KLV7000 manufactured by Hakuba was used as a light source device (diffusion light source).
- Other measuring instruments include haze measurement (Murakami Color, Hazemeter HM150), transmission and reflection spectral characteristics (Hitachi, U4100 spectrophotometer), polarizer characteristics (Murakami Color, DOT3), luminance measurement ( Topcon, luminance meter BM7), luminance and color tone angle distribution measuring instrument (ELDIM, Ez-Contrast), and UV irradiator (Disho Electric, UVC321AM1) were used.
- the cholesteric liquid crystal polymer is represented by the following formula 2:
- a polymerizable nematic liquid crystal monomer A represented by the following formula: [0200] [Formula 3]
- the polymerizable chiral agent B represented by the following ratio (weight ratio)
- Selective reflection center wavelength Monomer AZ chiral agent B (mixing ratio): Selective reflection wavelength band (nm)
- Each of the liquid crystal mixtures was made into a 33% by weight solution dissolved in tetrahydrofuran, and then purged with nitrogen under an environment of 60 ° C to obtain a reaction initiator (azobisisobutyronitrile, 0.5% with respect to the mixture). (% By weight) to perform a polymerization treatment.
- the obtained polymer was purified by reprecipitation separation with ethyl ether.
- the cholesteric liquid crystal polymer was dissolved in methylene chloride to prepare a 10% by weight solution.
- the solution was coated on an alignment substrate with a wire bar so that the thickness when dried was about 1.5 zm.
- a polyethylene terephthalate (PET) film having a thickness of 75 xm was used, and a polyimide alignment film was coated on the surface with a thickness of about 0.1 lzm and rubbed with a rayon rubbing cloth. After coating, it was dried at 140 ° C for 15 minutes. After the completion of this heat treatment, the liquid crystal was cooled and fixed at room temperature to obtain a thin film.
- PET polyethylene terephthalate
- the obtained liquid crystal thin film was overcoated with each color through the same process, and was sequentially laminated from the long wavelength side to the short wavelength side.
- a cholesteric liquid crystal laminate having a thickness of about 8 ⁇ m, in which six liquid crystal layers were laminated in order from the short wavelength side, was obtained.
- the obtained cholesteric liquid crystal laminate was peeled off from the PET substrate and used.
- the obtained cholesteric liquid crystal laminate has a thickness of 400 nm-8 It had a selective reflection function at 80 nm. This was designated as a polarizing element (A1-1).
- the distortion rate in the front direction was about 0.55, and the distortion rate in the 60 ° tilt direction was about 0.05.
- the outgoing light transmitted through the polarizing element (A1-1) has a large incident angle.
- the outgoing light is linearly polarized light, and the linearly polarized light is polarized in a direction substantially orthogonal to the normal direction (front) of the polarizing element surface. Had an axis.
- Nitto Denko polycarbonate retardation film (TR film) was used.
- a retardation layer (negative C plate) having a front retardation of almost 0 and generating a retardation in an oblique direction was prepared from a polymerizable liquid crystal.
- the polymerizable mesogen compound LC242 manufactured by BASF was used, and as the polymerizable chiral agent, LC756 manufactured by BASF was used.
- a specific production method is as follows.
- the polymerizable chiral agent and the polymerizable mesogen conjugate were dissolved in toluene (20% by weight), and a reaction initiator (IRGACURE 907 manufactured by Ciba Specialty Chemicals, 1% by weight based on the mixture) was added.
- a solution was prepared.
- the orientation substrate used was a polyethylene terephthalate film manufactured by Toray Industries: Nore Miller (thickness: 75 ⁇ m), which was subjected to orientation treatment with a rubbing cloth.
- the solution was applied with a wire bar at a coating thickness of 4 ⁇ m when dried, dried at 90 ° C for 2 minutes, heated once to an isotropic transition temperature of 130 ° C, and then gradually heated. Cooled down. While maintaining a uniform alignment state, the composition was cured by irradiation with ultraviolet light (10 mWZcm 2 ⁇ 1 minute) in an environment of 80 ° C to obtain a negative C plate. When the phase difference of this negative C plate was measured, 55
- phase difference about 1 when tilted at 30 °
- a polarizing element (A1-1), a half-wave plate (B), a retardation layer (C), a 1Z4 wavelength plate (D), and a linearly-polarized reflective polarizer (E) are arranged in this order.
- An acrylic adhesive (N O. 7) manufactured by Nitto Denko: 25 zm in thickness was used and laminated to obtain an optical element (XI).
- the transmission axis of the linearly polarized light reflection type polarizer (E) was arranged in the same direction as the direction of the linearly polarized light obtained by transmitting through the quarter-wave plate (D).
- the optical element (XI) was placed on a diffused light source with the polarizing element (A1-1) facing down, and emitted light was measured. The results are shown in FIG.
- a cholesteric liquid crystal laminate was obtained in the same manner as in Example 1 except that the polymerizable nematic liquid crystal monomer A and the polymerizable chiral agent B were used in the ratios (weight ratios) shown below. .
- Selective reflection center wavelength Monomer A / Chiral agent B (mixing ratio): Selective reflection wavelength band (nm)
- the obtained cholesteric liquid crystal laminate had a selective reflection function at 400 750 nm. This was designated as a polarizing element (A1-2).
- the polarizing element (A1-2) had a distortion rate of about 0.65 in the front direction and about 0.03 in the 60 ° tilt direction. Outgoing light transmitted through the polarizing element (A1-2) has a large incident angle The emitted light was linearly polarized light, and the linearly polarized light had a polarization axis in a direction substantially perpendicular to the normal direction (front) of the polarizing element surface.
- a polarizing element (A1-2) and a half-wave plate were prepared in the same manner as in Example 1 except that the polarizing element (A1-2) was used instead of the polarizing element (A1-1).
- B retardation layer
- C 1/4 wavelength plate
- D 1/4 wavelength plate
- E linear polarization reflection type polarizer
- NO. 7 Nitto Denko's acrylic adhesive
- the optical element (X2) was placed on a diffused light source with the polarizing element (A1-2) facing down, and emitted light was measured. The results are shown in FIG.
- a cholesteric liquid crystal laminate was obtained in the same manner as in Example 1 except that the polymerizable nematic liquid crystal monomer A and the polymerizable chiral agent B were used in the ratios (weight ratios) shown below. .
- Selective reflection center wavelength Monomer A / Chiral agent B (mixing ratio): Selective reflection wavelength band (nm)
- the obtained cholesteric liquid crystal laminate had a selective reflection function at 400 lOOOnm. This was designated as a polarizing element (A1-3).
- the polarizing element (A1-3) had a distortion rate of about 0.68 in the front direction and about 0.03 in the 60 ° tilt direction.
- the outgoing light transmitted through the polarizing element (A1-3) has a large incident angle, and the outgoing light is linearly polarized light, and the linearly polarized light is polarized in a direction substantially orthogonal to the normal direction (front) of the polarizing element surface. Had an axis.
- Example 1 was repeated except that the mixture ratio (weight ratio) of the polymerizable mesogen compound / polymerizable chiral agent was set to 92/8 so that the selective reflection center wavelength of the obtained cholesteric liquid crystal was about 300 nm.
- a retardation layer (negative C plate) was prepared in the same manner as in 1 using a polymerizable liquid crystal. When the phase difference of this negative C plate was measured, the phase difference was about lnm in the front direction and about 220nm when tilted by 30 ° with respect to light having a wavelength of 550nm. Four of these were laminated using Nitto Denko's acrylic adhesive (NII. 7): Thickness to obtain a negative C plate with high retardation.
- NII. 7 Nitto Denko's acrylic adhesive
- Example 1 in place of the polarizing element (A1-1), a polarizing element (A1-3) was used, and in the same manner as in Example 1 except that the retardation layer (C) was used, Polarizing element (A1-3), 1/2 wavelength plate (B), retardation layer (C), 1/4 wavelength plate (D), linear polarization reflection type polarizer (E), Nitto Denko acrylic Adhesive (NO. 7): laminated using a thickness of 25 / m to obtain an optical element (X2).
- the optical element (X3) was placed on a diffused light source with the polarizing element (A1-3) facing down, and emitted light was measured. The results are shown in FIG.
- a polarizing element (A1-1), a half-wave plate (B), a quarter-wave plate (D) were obtained in the same manner as in Example 1 except that the retardation layer (C) was not used.
- a linearly polarized light-reflecting polarizer (E) were laminated using an acrylic adhesive (No. 7) made by Nitto Denko: 25 / m in thickness to obtain an optical element.
- the optical element was placed on a diffusion light source with the polarizing element (A1-1) facing down, and emission light measurement was performed. The results are shown in FIG.
- Table 1 summarizes the luminance viewing angle characteristics of the optical elements obtained in Examples 13 and 13 and Comparative Example 1. Visual evaluation was performed for oblique coloring.
- a coating solution (solid content: 20% by weight) was prepared by adding 5% by weight of a photopolymerization initiator (Circa Specialty Chemicals Co., Ltd., Irgacure 184) to the solid content.
- the coating liquid was cast on a stretched PET film (oriented substrate), dried at 80 ° C for 2 minutes, and then the other PET substrate was laminated.
- cholesteric liquid crystal layer was 9 ⁇ m in thickness, and the selective reflection band was 430 nm and 860 nm.
- the pitch length was measured by a cross-sectional TEM photograph.
- the cholesteric pitch changed almost continuously in the thickness direction. This was designated as a polarizing element (A1-4).
- the polarizing element (A1-4) had a distortion rate of about 0.99 in the front direction and about 0.10 in the 60 ° tilt direction.
- the outgoing light transmitted through the polarizing element (A1-4) has a large incident angle.
- the outgoing light is linearly polarized light, and the linearly polarized light is polarized in a direction substantially orthogonal to the normal direction (front) of the polarizing element surface. Had an axis.
- An optical element (X4) was obtained in the same manner as in Example 1, except that the polarizing element (A1-4) was used instead of the polarizing element (A1-4).
- the optical element (X4) was placed on a diffusion light source, and emitted light was measured. The result was almost equivalent to that of Example 1.
- a photopolymerization initiator Irgacure 907, manufactured by Ciba-Sharti Chemika Norezu.
- the coating liquid was cast on a stretched PET film (oriented substrate) using a wire bar so that the thickness after drying was 7 / im, and the solvent was dried at 100 ° C for 2 minutes.
- the obtained film was subjected to first UV irradiation at 40 mW / cm 2 for 1.2 seconds in an air atmosphere at 40 ° C. from the PET side.
- the second UV irradiation was performed at 4 mW / cm 2 for 60 seconds in an air atmosphere while increasing the temperature to 90 ° C. at a rate of 3 ° C./sec.
- a third cholesteric liquid crystal layer having a selective reflection band of 425 to 900 nm was obtained by performing a third UV irradiation from the PET side at 60 mW / cm 2 for 10 seconds in a nitrogen atmosphere.
- the pitch length was measured by a cross-sectional TEM photograph.
- the cholesteric pitch changed almost continuously in the thickness direction. This was designated as a polarizing element (A1-5).
- the polarizing element (A1-5) had a distortion rate of about 0.99 in the front direction and about 0.10 in the 60 ° tilt direction.
- the outgoing light that has passed through the polarizing element (A1-5) has a large incident angle, and the outgoing light is linearly polarized light, and the linearly polarized light is polarized in a direction substantially orthogonal to the normal direction (front) of the polarizing element surface. Had an axis.
- the optical element (X5) was placed on a diffusion light source, and emitted light was measured. The result was almost equivalent to that of Example 1.
- a photopolymerizable mesogen compound (polymerizable nematic liquid crystal monomer) represented by the above formula (4) and 4 parts by weight of a polymerizable chiral agent (LC756 manufactured by BASF) and a solvent (cyclobentanone) are selectively reflected at a center wavelength of 550 nm.
- a coating solution (solid content 30% by weight) was added to a solution adjusted and blended so that 3% by weight of a photopolymerization initiator (Circa Specialty Chemanolaz Co., Ltd., Irgacure 907) was added to the solid content.
- a photopolymerization initiator (Circa Specialty Chemanolaz Co., Ltd., Irgacure 907) was added to the solid content.
- the coating liquid was cast on a stretched PET film (oriented substrate) using a wire bar so that the thickness after drying was 6 ⁇ m, and the solvent was dried at 100 ° C. for 2 minutes.
- the obtained film was subjected to a first UV irradiation at 50 mW / cm 2 for 1 second in an air atmosphere at 40 ° C from the PET side. Thereafter, heating was performed at 90 ° C for 1 minute without UV irradiation (the selective reflection band at this time was 420 to 650 nm).
- a second UV irradiation was performed in an air atmosphere at 90 ° C. for 5 seconds at 5 mW / cm 2 (the selective reflection band at this time was 420 to 900 nm).
- a third cholesteric liquid crystal layer having a selective reflection band of 425 to 900 nm was obtained by performing a third UV irradiation from the PET side at 80 mW / cm 2 for 30 seconds in a nitrogen atmosphere.
- the pitch length was measured by a cross-sectional TEM photograph.
- the cholesteric pitch changed almost continuously in the thickness direction. This was designated as a polarizing element (A1-6).
- the polarizing element (A1-6) had a distortion rate of about 0.99 in the front direction and about 0.04 in the 60 ° tilt direction.
- the outgoing light transmitted through the polarizing element (A1-6) has a large incident angle.
- the outgoing light is linearly polarized light, and the linearly polarized light is polarized in a direction substantially orthogonal to the normal direction (front) of the polarizing element surface. Had an axis.
- An optical element (X6) was obtained in the same manner as in Example 1, except that the polarizing element (A1-6) was used instead of the polarizing element (A1-1).
- Band-pass filters having the wavelength transmission characteristics shown in Fig. 24 were fabricated using evaporated thin films.
- the total thickness was about 53 zm.
- the above band-pass filter was arranged on a diffusion light source, and emitted light was measured.
- the light collection characteristics shown in Fig. 25 were obtained.
- the transmission spectrum was measured again after leaving this filter in a room temperature and normal humidity environment for 3 months, the transmission spectrum changed as shown in FIG. This was considered to be due to moisture adsorption to the deposited film due to moisture absorption.
- the light-collecting characteristics of this sample were confirmed in the same manner as described above, a change was observed in the light-collecting characteristics as shown in FIG. Thus, it was considered to be practically difficult to maintain the wavelength characteristics of the bandpass filter for three wavelengths.
- Comparative Example 3 Bandpass filters were fabricated by thin film coating of cholesteric liquid crystal polymer. A three-wavelength bandpass filter that reflects right circularly polarized light and a broadband circularly polarizing plate that reflects left circularly polarized light are combined. Only the intended three wavelengths transmit circularly polarized light in the vicinity of the vertical direction, reflect and recycle inverse circularly polarized light, and reflect all obliquely incident light.
- a selective reflection circularly polarized bandpass filter that reflects right circularly polarized light with a selective reflection wavelength range of S440 490 nm, 540 600 nm, and 615-700 nm for the emission spectra of three-wavelength cold cathode tubes of 435 nm, 535 nm, and 610 nm was fabricated. .
- cholesteric liquid crystal polymers having selective reflection central wavelengths of 480 nm, 550 nm, and 655 nm are produced based on EP0834754A1 similar to that in Example 1 for the liquid crystal material used.
- the cholesteric liquid crystal polymer was prepared by mixing the polymerizable nematic liquid crystal monomer A (formula 2) and the polymerizable chiral agent (enantiomer of formula 3) used in Example 1 in the following ratio (weight ratio).
- AZ chiral agent ⁇ (mixing ratio)
- Each of the liquid crystal mixtures was made into a 33% by weight solution dissolved in tetrahydrofuran, and then purged with nitrogen under an environment of 60 ° C. to react with a reaction initiator (azobisisobutyronitrile, 0% with respect to the mixture). (5% by weight).
- a reaction initiator azobisisobutyronitrile, 0% with respect to the mixture.
- the obtained polymer was purified by reprecipitation separation with ethyl ether.
- the cholesteric liquid crystal polymer was dissolved in methylene chloride to prepare a 10% by weight solution.
- the solution was coated on an alignment substrate with a wire bar so that the thickness when dried was about 1.5 zm.
- a polyethylene terephthalate (PET) film having a thickness of 75 x m was used, and a polybutyl alcohol alignment film was coated on the surface at about 0.1 x m and rubbed with a rayon rubbing cloth. After coating, it was dried at 140 ° C for 15 minutes. After this heat treatment, the liquid crystal was cooled and fixed at room temperature to obtain a thin film.
- PET polyethylene terephthalate
- FIG. 26 shows the transmittance of the obtained cholesteric liquid crystal laminate.
- the cholesteric liquid crystal laminate had a distortion rate of about 0.90 in the front direction and about 0.54 in the 60 ° tilt direction.
- NIPOCS film (with PCF400-SEG1465DU) manufactured by Nitto Denko was laminated on the cholesteric liquid crystal laminate (bandpass filter).
- This film is a polarizing plate with a circularly polarizing reflective polarizing plate used for the purpose of improving brightness, and a 1Z 4 wavelength plate is arranged between the circularly polarizing plate and the polarizing plate.
- the cholesteric liquid crystal surfaces were bonded together in the same manner as described above to obtain an integrated product.
- the above band-pass filter was arranged on a diffusion light source, and emitted light was measured. Although it had a light condensing characteristic with a half-value width of about ⁇ 15 degrees, a change in color tone was noticed with a sharp drop in brightness when observed with the naked eye from an oblique direction. This is probably because the set values of the transmission wavelengths do not exactly match the emission spectrum of the light source, resulting in a difference in the degree of the shielding effect due to the angle change.
- the outgoing light was measured for a Sharp TFT liquid crystal display (model number LQ10 D362 / 10.4 / TFT) using a conventional sidelight type light guide plate. The results are shown in FIG. The outgoing light peak is slightly shifted from the front direction.
- a solvent methyl ethyl ketone
- PET substrate Toray's Lumilar 75 / m thickness
- the thickness of the obtained cured liquid crystal was about 6 zm.
- the optical rotation of this sample was about 85 °.
- the polarizing element obtained by laminating the linearly polarized light reflection type polarizer (E), the optical rotator, and the linearly polarized light reflection type polarizer (E) had a selective reflection function at 380-1 100 nm.
- the cholesteric liquid crystal laminate had a strain rate in the front direction of 0.01 or less and a strain rate of 60 ° or less in the tilt direction of 0.01 or less, and there was no specific incident angle dependence for transmittance. .
- the performance of this polarizing element was almost the same as that of a polarizing element in which DBEF was bonded to DBEF at an axis angle of about 85 °.
- the optical element using the polarizing element of the present invention is suitably used for a condensing backlight system and further for a liquid crystal display device.
- FIG. 1 (A) is a conceptual diagram showing a polarization axis direction of emitted light transmitted through a polarizing element (A1).
- FIG. 1 (B) is a conceptual diagram showing a polarization axis direction of emitted light when FIG. 1 (A) is viewed from the normal direction of the polarizing element (A1).
- FIG. 2 (A) is a conceptual diagram showing a polarization axis direction of emitted light transmitted through a polarizing element (A2).
- FIG. 2 (B) is a conceptual diagram showing the polarization axis direction of emitted light when FIG. 2 (A) is viewed from the direction of the normal to the polarizing element (A2).
- FIG. 3 is a conceptual diagram illustrating polarization components and the like.
- FIG. 4 is a conceptual diagram showing polarization separation by a conventional cholesteric liquid crystal layer.
- FIG. 5 is a conceptual diagram showing polarization separation by a conventional cholesteric liquid crystal layer.
- FIG. 6 is a conceptual diagram showing polarization separation by a polarizing element (A).
- FIG. 7 is a conceptual diagram showing polarization separation by a polarizing element (A).
- FIG. 8 is a conceptual diagram showing a polarization axis direction of emitted light transmitted through a half-wave plate (B) at a polarizing element (A1) and at the next stage.
- FIG. 9 is a conceptual diagram showing a polarization axis direction of emitted light transmitted through a polarizing element (Al), a half-wave plate (B), and then a retardation layer (C).
- Garden 10 is a conceptual diagram showing the polarization axis direction of the outgoing light transmitted through the polarizing element (Al), the half-wave plate (B), the retardation layer (C), and then the quarter-wave plate (D).
- FIG. 14 is an example of a cross-sectional view when a polarizing plate (P) is laminated on the optical element (X) of the present invention.
- FIG. 15 is a conceptual diagram showing conversion of a polarization type by a wavelength plate.
- Garden 16 is an example of a sectional view of a liquid crystal display device using the optical element (X) of the present invention.
- Garden 17 is an example of a sectional view of a liquid crystal display device using the optical element (X) of the present invention.
- FIG. 20 is a diagram showing a transmitted light intensity angular distribution of the optical element (XI) of Example 1.
- FIG. 21 is a diagram showing a transmitted light intensity angle distribution of an optical element (X2) of Example 2.
- FIG. 22 is a diagram showing a transmitted light intensity angular distribution of the optical element (X3) of Example 3.
- FIG. 23 is a diagram illustrating a transmitted light intensity angle distribution of the optical element of Comparative Example 1.
- FIG. 24 is a diagram illustrating a transmission spectrum of a bandpass filter of Comparative Example 2.
- FIG. 25 is a diagram illustrating a light-collecting state of the bandpass filter of Comparative Example 2.
- FIG. 26 is a diagram illustrating a transmission spectrum of a bandpass filter of Comparative Example 3.
- FIG. 27 is a diagram illustrating a transmitted light intensity angle distribution of the liquid crystal display device of Comparative Example 4.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Polarising Elements (AREA)
- Liquid Crystal (AREA)
- Non-Portable Lighting Devices Or Systems Thereof (AREA)
- Planar Illumination Modules (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US10/576,772 US20070064168A1 (en) | 2003-10-23 | 2004-08-24 | Optical element, light condensation backlight system, and liquid crystal display |
Applications Claiming Priority (2)
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JP2003-363241 | 2003-10-23 | ||
JP2003363241A JP4247894B2 (ja) | 2003-10-23 | 2003-10-23 | 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 |
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WO2005040870A1 true WO2005040870A1 (ja) | 2005-05-06 |
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PCT/JP2004/012121 WO2005040870A1 (ja) | 2003-10-23 | 2004-08-24 | 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 |
Country Status (4)
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US (1) | US20070064168A1 (ja) |
JP (1) | JP4247894B2 (ja) |
TW (1) | TW200521501A (ja) |
WO (1) | WO2005040870A1 (ja) |
Families Citing this family (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4714449B2 (ja) * | 2004-10-01 | 2011-06-29 | 矢崎総業株式会社 | 表示装置 |
JP2007026829A (ja) * | 2005-07-14 | 2007-02-01 | Matsushita Electric Works Ltd | 埋込型照明器具 |
US20090122236A1 (en) * | 2005-10-21 | 2009-05-14 | Nitto Denko Corporation | Polarizing plate with an optical compensation layer and image display apparatus using the same |
JP5552728B2 (ja) * | 2007-11-20 | 2014-07-16 | セイコーエプソン株式会社 | 液晶装置、プロジェクタ、液晶装置の光学補償方法及び位相差板 |
JP5262388B2 (ja) * | 2007-11-20 | 2013-08-14 | セイコーエプソン株式会社 | 液晶装置、プロジェクタ及び液晶装置の光学補償方法 |
JP5262387B2 (ja) * | 2007-11-20 | 2013-08-14 | セイコーエプソン株式会社 | 液晶装置、プロジェクタ及び液晶装置の光学補償方法 |
JP5227692B2 (ja) * | 2008-08-05 | 2013-07-03 | 旭化成イーマテリアルズ株式会社 | ワイヤグリッド偏光板の製造方法 |
EP2666039B1 (en) | 2011-01-18 | 2017-06-07 | 3M Innovative Properties Company | Optical film stack |
US9989688B2 (en) * | 2013-03-29 | 2018-06-05 | Dai Nippon Printing Co., Ltd. | Polarizing plate, image display apparatus, and method for improving bright-place contrast in image display apparatus |
WO2015029958A1 (ja) * | 2013-08-26 | 2015-03-05 | 富士フイルム株式会社 | 輝度向上フィルム、光学シート部材および液晶表示装置 |
JP6321052B2 (ja) * | 2014-02-14 | 2018-05-09 | 富士フイルム株式会社 | 輝度向上フィルム、光学シート部材および液晶表示装置 |
US9869809B2 (en) * | 2014-03-12 | 2018-01-16 | Dai Nippon Printing Co., Ltd. | Backlight unit, liquid-crystal display apparatus, and stacked structure |
KR101585334B1 (ko) * | 2014-07-24 | 2016-01-14 | 삼성에스디아이 주식회사 | 액정표시장치용 모듈 및 이를 포함하는 액정표시장치 |
CN104503129B (zh) * | 2014-12-30 | 2018-02-13 | 京东方科技集团股份有限公司 | 一种光学模组和反射型显示装置 |
JP2017009795A (ja) * | 2015-06-22 | 2017-01-12 | 日東電工株式会社 | 偏光板及び偏光板の製造方法 |
CN108885293B (zh) * | 2016-03-28 | 2021-05-07 | 富士胶片株式会社 | 反射层的制造方法及反射层 |
TWI631392B (zh) * | 2017-05-23 | 2018-08-01 | 明基材料股份有限公司 | 背光模組 |
US10989954B2 (en) * | 2018-09-28 | 2021-04-27 | Sharp Kabushiki Kaisha | Liquid crystal display device |
WO2020230698A1 (ja) * | 2019-05-10 | 2020-11-19 | 富士フイルム株式会社 | センサー |
CN111323945A (zh) * | 2020-03-19 | 2020-06-23 | Tcl华星光电技术有限公司 | 一种偏光片贴合设备及其贴合方法 |
JP2022039427A (ja) * | 2020-08-28 | 2022-03-10 | 日東電工株式会社 | 位相差フィルム、積層位相差フィルム、位相差層付偏光板および画像表示装置 |
CN113093412B (zh) * | 2021-04-12 | 2023-11-03 | 武汉天马微电子有限公司 | 显示面板及控制方法、显示装置 |
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JPH11231130A (ja) * | 1998-02-09 | 1999-08-27 | Nitto Denko Corp | 偏光素子、光学素子、照明装置及び液晶表示装置 |
JP2001318230A (ja) * | 2000-03-01 | 2001-11-16 | Nitto Denko Corp | 偏光部材、面光源及び液晶表示装置 |
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- 2003-10-23 JP JP2003363241A patent/JP4247894B2/ja not_active Expired - Fee Related
-
2004
- 2004-08-24 WO PCT/JP2004/012121 patent/WO2005040870A1/ja active Application Filing
- 2004-08-24 US US10/576,772 patent/US20070064168A1/en not_active Abandoned
- 2004-09-06 TW TW093126875A patent/TW200521501A/zh unknown
Patent Citations (2)
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JPH11231130A (ja) * | 1998-02-09 | 1999-08-27 | Nitto Denko Corp | 偏光素子、光学素子、照明装置及び液晶表示装置 |
JP2001318230A (ja) * | 2000-03-01 | 2001-11-16 | Nitto Denko Corp | 偏光部材、面光源及び液晶表示装置 |
Also Published As
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TW200521501A (en) | 2005-07-01 |
JP4247894B2 (ja) | 2009-04-02 |
JP2005128219A (ja) | 2005-05-19 |
US20070064168A1 (en) | 2007-03-22 |
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