JP2007148158A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which minimizes loss of light due to reflection, is free of deterioration such as peeling in a circular polarized light separating layer and free of luminance unevenness and a decrease in display quality, and has superior durability. <P>SOLUTION: The liquid crystal display device has a linear polarizer A(4), a liquid crystal cell, a linear analyzer B(3), an optical anisotropic element C(5) whose retardation Re from a front direction is about 1/4 as large as the wavelength of transmitted light and whose retardation Rth from a thickness direction is ≤0 nm, and a circular polarized light separating element (6) in this order; and the linear polarizer B(3) and optical anisotropic element C(5) are united and arranged forming a space between the united linear polarizer B(3) and the optical anisotropic element C(5) and the circular polarized light separating element (6). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly, minimizes light loss due to reflection, does not cause delamination or warping of a circularly polarized light separating element, and reduces display quality due to occurrence of uneven brightness or moire. The present invention relates to a liquid crystal display device having no durability and excellent durability.

To increase the brightness of the liquid crystal display device, the circularly polarized beam splitter and a quarter-wave plate and _{Rth (= {(n x +} n y) / 2-n z} × d; n x, n y is in the plane in the principal refractive index perpendicular, n _x> n _y a is .n _z is the thickness direction main refractive index, d is what is thickness.) is a combination of a retardation element having a negative value, the liquid crystal It is known to arrange between a panel and a light source.
For example, Patent Document 1 discloses a polarization separation sheet (circular polarization separation element) in which cholesteric liquid crystal layers are disposed on both sides of a light diffusion plate, a retardation element having an Rth of −20 to −2000 nm, and 1 / A liquid crystal display device in which a four-wave plate is disposed is disclosed. In patent document 2, what laminated | stacked the said polarization separation sheet, the phase difference element, and the quarter wavelength plate in this order is called the brightness improvement film.
Patent Document 2 discloses an optical layered body (circularly polarized light separating element) having a cholesteric phase liquid crystal layer having a concavo-convex shape on its surface, a retardation element having an Rth of -20 to -2000 nm, and a quarter-wave plate. A liquid crystal display device in which is arranged is disclosed. In patent document 2, what laminated | stacked the said optical laminated body, the phase difference element, and the quarter wavelength plate in this order directly or through an adhesive etc. is called the brightness improvement film.

  Since the liquid crystal display device is composed of 3 to 4 elements, as described in Paragraph No. (0003) of Patent Document 3, light quantity attenuation occurs due to reflection loss at each interface of the elements, and simple overlay arrangement In the case of, light utilization efficiency of 70 to 80% is obtained by simple calculation. Therefore, in Patent Document 3, when a polarization separation film (circular polarization separation element) composed of a cholesteric liquid crystal layer and a quarter-wave plate are laminated via an adhesive layer having excellent stress relaxation properties, reflection loss is reduced, and light is used. Teaching that efficiency will improve.

JP 2005-91825 A JP-A-2005-37657 JP-A-9-189811

However, according to the study of the present inventor, as described in Patent Documents 1 to 3, when a circularly polarized light separating element and a quarter wavelength plate or a phase difference element are laminated, due to a difference in thermal expansion coefficient or the like, It has been found that stress is unavoidable, and a phenomenon such as peeling of the liquid crystal layer and warping of the brightness enhancement film may occur. These phenomena cause luminance unevenness, moire, and the like, and display quality is significantly impaired.
Therefore, the object of the present invention is to minimize the loss of light due to reflection, do not cause delamination or warping of the circularly polarized light separating element, and do not deteriorate display quality due to occurrence of uneven brightness or moire. An object of the present invention is to provide a liquid crystal display device excellent in the above.

  As a result of intensive studies to achieve the above object, the present inventor has found that the retardation Re in the front direction is transmitted between the linear polarizer B arranged on the light source side of the liquid crystal cell and the circularly polarized light separating element. An optically anisotropic element C having a wavelength of about 1/4 and a retardation Rth in the thickness direction of less than 0 nm is disposed, and the linear polarizer B and the optically anisotropic element C are integrated to form an integrated straight line. By disposing a space between the polarizer B and the optically anisotropic element C and the circularly polarized light separating element, the loss of light due to reflection is minimized and the performance of the circularly polarized light separating element is sufficient. It has been found that a liquid crystal display device with excellent durability can be obtained, in which the light utilization efficiency is greatly improved, the layer separation and warping of the circularly polarized light separating element do not occur, and the display quality is not deteriorated. .

  Furthermore, by providing a concavo-convex shape on at least one of the two faces of the circularly polarized light separating element and the optically anisotropic element, or at least of the circularly polarized light separating element or the optically anisotropic element C By providing light diffusivity on one side, the loss of light due to reflection can be minimized and the performance of the circularly polarized light separating element can be fully exerted, so that the light utilization efficiency can be greatly improved, and circularly polarized light separation is achieved. It has been found that a liquid crystal display device excellent in durability can be obtained without delamination or warping of the element and without deterioration in display quality such as luminance unevenness and moire. The present invention has been completed based on these findings.

Thus, according to the present invention,
(1) Optical anisotropy in which the linear polarizer A, the liquid crystal cell, the linear polarizer B, the retardation Re in the front direction is about 1/4 of the wavelength of transmitted light, and the retardation Rth in the thickness direction is less than 0 nm. Element C and circularly polarized light separating element in this order, linear polarizer B and optically anisotropic element C are integrated, and integrated linear polarizer B and optically anisotropic element C; A liquid crystal display device is provided in which a space is formed between the circularly polarized light separating elements.

Furthermore, according to the present invention, as a preferred embodiment,
(2) The above-mentioned liquid crystal display device in which at least one of the two opposing surfaces between the circularly polarized light separating element and the optically anisotropic element C is provided with an uneven shape,
(3) The liquid crystal display device, wherein a spacer is interposed between the linear polarizer B and the optically anisotropic element C integrated with the circularly polarized light separating element.
(4) The liquid crystal display device, wherein at least one of the circularly polarized light separating element and the optically anisotropic element C has light diffusibility,
(5) The above-mentioned liquid crystal display device, wherein the circularly polarized light separating element has a support base and a resin layer having cholesteric regularity,
(6) The liquid crystal display device, wherein the total thickness of the circularly polarized light separating element is 140 to 350 μm, and the total thickness of the resin layers having cholesteric regularity is 4 to 20 μm,
(7) The above-mentioned liquid crystal display device, wherein the support substrate of the circularly polarized light separating element is formed by molding a material containing a transparent resin and a light diffusing material,

(8) The liquid crystal display device, wherein the resin layer having cholesteric regularity of the circularly polarized light separating element has an alignment defect,
(9) The liquid crystal display device, wherein the resin layer having cholesteric regularity is non-liquid crystalline,
(10) The liquid crystal display device, wherein the resin layer having cholesteric regularity is obtained by polymerizing a polymerizable liquid crystal compound,
(11) The above-mentioned liquid crystal display device further comprising an optical element D having uneven shapes on both sides between the circularly polarized light separating element and the optically anisotropic element C,
(12) The liquid crystal display device, wherein the optically anisotropic element C is a combination of a plurality of optically anisotropic elements,
(13) optically anisotropic element C, and about 1/4 of the optically anisotropic element C ₁ having a wavelength in the front direction of the retardation Re of the transmitted light, and the thickness direction in the front direction of the retardation Re approximately 0nm retardation Rth is composed of the combination of the optically anisotropic element C ₂ of less than 0 nm, the liquid crystal display device, and / or (14) optically anisotropic between the liquid crystal cell and the linear polarizer B The liquid crystal display device is further provided, which further includes a anisotropic element E, and the optically anisotropic element E, the linear polarizer B, and the optically anisotropic element C are integrated in this order.

  In the liquid crystal display device and the polarization illumination device of the present invention, the linear polarizer B and the optically anisotropic element C are integrated, and the integrated linear polarizer B and optically anisotropic element C are circularly polarized. It arrange | positions so that space may be formed between isolation | separation elements. With this arrangement, light loss due to reflection can be minimized. Further, in the liquid crystal display device of the present invention, distortion or the like hardly occurs in the circularly polarized light separating element, so that luminance unevenness and moire do not occur, and durability is further improved. Furthermore, the display images observed from the front direction and from the direction of 60 degrees obliquely have high luminance, no color distribution, and high quality.

  In the liquid crystal display device of the present invention, the linear polarizer A, the liquid crystal cell, the linear polarizer B, the retardation Re in the front direction is about 1/4 of the wavelength of transmitted light, and the retardation Rth in the thickness direction is less than 0 nm. , Optically anisotropic element C and circularly polarized light separating element in this order, linear polarizer B and optically anisotropic element C are integrated, and integrated linear polarizer B and optically anisotropic The space element (or gap) is formed between the active element C and the circularly polarized light separating element.

  The linear polarizer A and the linear polarizer B used in the present invention are known linear polarizers used in liquid crystal display devices and the like. The linear polarizer used in the present invention transmits one of two linearly polarized lights that intersect at right angles. For example, a hydrophilic polymer film such as a polyvinyl alcohol film or an ethylene vinyl acetate partially saponified film adsorbed a dichroic substance such as iodine or a dichroic dye and uniaxially stretched, the hydrophilic polymer film Examples include uniaxially stretched and dichroic substances adsorbed, and polyene oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. In addition, there is a polarizer having a function of separating linearly polarized light such as grid polarizer and multilayer polarizer into reflected light and transmitted light. Of these, a polarizer containing polyvinyl alcohol is preferred.

The degree of polarization of the linear polarizer used in the present invention is not particularly limited, but is preferably 98% or more, more preferably 99% or more. The average thickness of the linear polarizer is preferably 5 to 80 μm.
The polarization transmission axis of the linear polarizer A and the polarization transmission axis of the linear polarizer B are usually arranged so as to sandwich the liquid crystal cell so as to be at right angles. The linear polarizer may change its polarization performance due to moisture absorption. In order to prevent this, a protective film is usually bonded to one or both sides of the linear polarizer A or B.

  As the resin constituting the protective film, norbornene resin, polyester resin, acetate resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, urethane resin, acrylic urethane resin, epoxy resin, silicone resin Etc. The linear polarizer and the protective film are usually brought into close contact with each other via an aqueous adhesive or the like. Examples of water-based adhesives include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, polyurethane adhesives, polyester adhesives, and the like. Layers, such as a hard-coat layer, an antireflection layer, a low reflection layer, an anti-glare layer, and an antifouling layer, may be formed on the side where the protective film is not bonded to the linear polarizer.

In a liquid crystal cell, a liquid crystal material is filled between two glass substrates provided with transparent electrodes facing each other with a gap of several μm, and a voltage is applied to this electrode to change the alignment state of the liquid crystal and pass light. This is to control the amount.
The liquid crystal cell is classified according to a method (operation mode) for changing the alignment state of the liquid crystal substance. For example, a TN (Twisted Nematic) type liquid crystal cell, a STN (Super Twisted Nematic) type liquid crystal cell, or a HAN (Hybrid Alignment Nematic) type. Non-twist type liquid crystal cells such as liquid crystal cells, IPS (In Plane Switching) type liquid crystal cells, VA (Vertical Alignment) type liquid crystal cells, MVA (Multiple Vertical Alignment) type liquid crystal cells, and OCB (Optical Compensated Bend) type liquid crystal cells. Examples thereof include a liquid crystal cell; a ferroelectric liquid crystal cell; or a light diffusion type liquid crystal cell such as an internal diffusion type.

The optically anisotropic element C has a retardation Re in the front direction of about ¼ of the wavelength of transmitted light and a retardation Rth in the thickness direction of less than 0 nm. Here, the transmitted light is light having a wavelength of 550 nm, and each retardation is a value at a wavelength of 550 nm.
Retardation Re _is a value obtained by equation _{(n x -n y) × d} . Retardation Rth _is a value obtained by equation _{{(n x + n y)} / 2-n z} × d. _nx is the maximum in-plane refractive index, _ny is the minimum in-plane refractive index, _nz is the refractive index in the thickness direction, and d is the thickness. The main refractive index can be measured by an automatic birefringence meter [for example, “KOBRA series” manufactured by Oji Scientific Instruments Co., Ltd.].
The retardation Re is about 1/4 of the wavelength of transmitted light, preferably 1/4 ± 10 nm of the wavelength of transmitted light.
The retardation Rth is less than 0 nm, preferably −50 to −1000 nm, more preferably −100 to −500 nm.

The optically anisotropic element C is formed by stretching a layer made of a resin, orienting an optically anisotropic material such as a discotic liquid crystal and stacking it on a support base, or combining a plurality of optically anisotropic elements. Can be obtained.
As the resin used for obtaining the optically anisotropic element C by stretching, a resin exhibiting negative intrinsic birefringence is suitable. When a negative intrinsic birefringence (photoelastic coefficient is negative) stretching a resin that shows a value of n _z is larger than n _y, the Rth is likely negative. Examples of the resin exhibiting negative intrinsic birefringence include styrene polymer, styrene-containing copolymer, acrylonitrile-containing copolymer, methyl methacrylate-containing copolymer, polycarbonate, and cellulose ester polymer.

  The optically anisotropic element C is obtained by stretching a layer formed by laminating a resin layer exhibiting negative intrinsic birefringence and a resin layer exhibiting positive intrinsic birefringence (optical elastic modulus is positive). You can also. Examples of the resin exhibiting positive intrinsic birefringence include a chain olefin polymer, polyester, polyarylene sulfide, polyvinyl alcohol, polycarbonate, polyarylate, cellulose ester polymer, polyethersulfone, polysulfone, polyallylsulfone, polyvinyl chloride, Examples include alicyclic structure-containing polymer resins described below.

The optically anisotropic element C used in the present invention may be a combination of a plurality of optically anisotropic elements. For example, an optically anisotropic element C ₁ having a retardation Re in the front direction of about ¼ of the wavelength of transmitted light and an optical element having a retardation Re in the front direction of approximately 0 nm and a retardation Rth in the thickness direction of less than 0 nm. those comprising a combination of anisotropic element C _2; an optically anisotropic element C ₁₁ front direction retardation Re is about 1/4 of the wavelength of the transmitted light, the front direction retardation Re of transmitted light an optical anisotropic element _{C 12} is about half of the wavelength, the retardation Rth of and the thickness direction in a front direction retardation Re approximately 0nm is a combination of an optically anisotropic element _{C 2} of less than 0nm Things.
Incidentally, the optical anisotropic element C ₁₁ retardation Re in the front direction is about 1/4 of the wavelength of the transmitted light, the optical anisotropic retardation Re in the front direction is approximately half of the wavelength of the transmitted light When the optical element C ₁₂ is combined with the slow axis so that the crossing angle of the slow axis is about 60 degrees, the optically anisotropic element C ₁ (which gives a phase difference of about ¼ wavelength in a wide wavelength region of visible light) Such an element may be referred to as a broadband quarter-wave plate).

  The circularly polarized light separating element used in the present invention reflects the right-handed or left-handed circularly polarized light in a specific wavelength region of incident light and transmits other circularly polarized light (such a property as a circularly polarized light separating function). It may be said that). The specific wavelength range for reflecting circularly polarized light is preferably 380 nm or more including a wide infrared light region, and more preferably a wavelength of 380 to 780 nm in the visible light region. Specifically, it is preferable to have a circularly polarized light separation function for light in any wavelength region of blue (wavelength 410 to 470 nm), green (wavelength 520 to 580 nm), and red (wavelength 600 to 660 nm).

  In the circularly polarized light separating element used in the present invention, the maximum wavelength of circularly polarized light having an incident angle of 0 degree and a reflectance of 30% or more is preferably 700 nm or more, more preferably 730 nm or more. Further, the maximum wavelength of circularly polarized light having an incident angle of 60 degrees with a reflectance of 30% or more is preferably 570 nm or more, more preferably 600 nm or more. When these maximum wavelengths are within the above range, coloring when observed from an oblique direction can be eliminated.

Examples of the circularly polarized light separating element include those having a supporting base and a resin having a cholesteric regularity (hereinafter sometimes referred to as cholesteric resin).
The cholesteric regularity indicates a structure in which the molecular axis angle of the resin is shifted (twisted) one after another as it proceeds in the normal direction of the resin layer plane. Such a structure in which the direction of the molecular axis is twisted is called a helical structure. The normal line (helical axis) of the resin layer plane is preferably substantially parallel to the thickness direction of the cholesteric resin layer.

The total thickness of the circularly polarized light separating element is usually 140 to 350 μm, preferably 200 to 300 μm. The total thickness of the cholesteric resin layer is usually 4 to 20 μm, preferably 4 to 10 μm, more preferably 4 to 4 μm. 7 μm. As the total thickness of the cholesteric resin layer is reduced, the difference in the amount of phase change due to wavelength tends to be reduced.

  The wavelength that exhibits the circularly polarized light separation function depends on the pitch of the helical structure in the cholesteric resin (= period of cholesteric regularity). The pitch of the helical structure is the distance in the helical axis direction until the angle of the molecular axis gradually shifts in the helical structure as it advances along the plane and then returns to the original molecular axis direction again. By changing the pitch of the helical structure, the wavelength at which the circularly polarized light separation function is exhibited can be changed.

  Examples of the cholesteric resin layer that exhibits the circularly polarized light separating function over the entire wavelength region of visible light include (i) a cholesteric resin layer in which the pitch of the helical structure is changed stepwise, and (ii) the pitch of the helical structure. Examples thereof include a cholesteric resin layer in which the size of is continuously changed.

  (I) The cholesteric resin layer in which the pitch of the helical structure is changed stepwise is obtained, for example, by laminating two or more resin layers. Specifically, a cholesteric resin layer having a helical structure pitch that exhibits a circularly polarized light separating function with light in the blue wavelength region, and a cholesteric material having a helical structure pitch that exhibits a circularly polarized light separating function with light in the green wavelength region It can be obtained by laminating a resin layer and a cholesteric resin layer having a helical structure pitch that exhibits a circularly polarized light separation function with light in the red wavelength region. Further, cholesteric resin layers having a central wavelength of reflected circularly polarized light of 470 nm, 550 nm, 640 nm, and 770 nm are respectively produced, and these cholesteric resin layers are arbitrarily selected, and the order of the central wavelengths of reflected light is 3 to 3 It can be obtained by laminating seven layers. When the cholesteric resin layers having different helical structure pitches are laminated, it is preferable that the rotation directions of the circularly polarized light reflected by the cholesteric resin layers are the same. In addition, in order to obtain a liquid crystal display device having a wide viewing angle, the stacking order of the cholesteric resin layers having different helical structure pitches is ascending or descending according to the helical structure pitch. preferable. The lamination of these cholesteric resin layers may be simply overlaid, or may be integrated via an adhesive or an adhesive.

  (Ii) The cholesteric resin layer in which the pitch of the helical structure is continuously changed is not particularly limited by the manufacturing method. For example, it can be obtained by forming a layer comprising a polymerizable liquid crystal compound for forming a cholesteric resin layer, a chiral agent, and a polymerization initiator, and heating this layer by irradiating with ultraviolet rays. . Here, the polymerizable liquid crystal compound and the chiral agent are preferably compounds having different polymerization reactivity in ultraviolet irradiation. A chiral agent is a compound that can give a helical structure to a molecular arrangement.

  Although the mechanism for continuously changing the pitch size by ultraviolet irradiation is not known in detail, it is said that the pitch is inclined by the following mechanism. The light receiving intensity of the ultraviolet rays irradiated to the layer containing the polymerizable liquid crystal compound, the chiral agent, and the polymerization initiator is strong on the surface (ultraviolet irradiation surface) side of the layer. In the layer, ultraviolet rays are absorbed by the ultraviolet absorber, so that the ultraviolet light receiving intensity decreases as the layer depth increases. Therefore, a difference in polymerization degree occurs as the depth of the layer increases from the surface of the layer (ultraviolet irradiation surface). Among the polymerizable liquid crystal compound and the chiral agent, the concentration of the compound having a high degree of polymerization is increased on the surface side of the layer, and the compound having a low degree of polymerization among the polymerizable liquid crystal compound and the chiral agent remaining as unreacted components is diffused. Move to the other side. Eventually, a concentration gradient is formed in which the concentration of the polymerizable liquid crystal compound or the chiral agent continuously changes in the depth direction of the layer. The amount of chiral agent affects the pitch size of the helical structure. Thus, a cholesteric resin layer in which the pitch of the helical structure is continuously changed in the depth direction can be obtained.

  As this type of cholesteric resin layer, for example, SID '95, Asia Display. , P735 (1995); Liquid Crystal, Vol. 2, No. 2, p32-39 (1998); Japanese Patent Publication No. 11-514757, US Publication No. 2001001509, US Pat. No. 6,638,449, US Pat. No. 5,948,831 There are those described in the Gazette.

Examples of the material for forming the cholesteric resin layer include a liquid crystal polymer and a polymerizable liquid crystal compound. Among these, a polymerizable liquid crystal compound is preferable.
A cholesteric resin layer can be formed by applying the liquid crystal polymer or polymerizable liquid crystal compound in a film form.

The liquid crystal polymer used for the material forming the cholesteric resin layer is a polymer having liquid crystallinity. As this liquid crystal polymer, there is a polymer having a mesogenic structure. A mesogen is a conjugated linear atomic group that imparts liquid crystal alignment.
As a polymer having a mesogenic structure, a structure in which a mesogenic group composed of a para-substituted cyclic compound or the like is bonded to a polymer main chain such as polyester, polyamide, polycarbonate, polyesterimide, or the like directly or via a spacer portion imparting flexibility. A low molecular weight crystalline compound (mesogen) composed of a para-substituted cyclic compound or the like directly or via a spacer portion composed of a conjugated atomic group in the polymer main chain, such as polyacrylate, polymethacrylate, polysiloxane, polymalonate, etc. Part) are combined.
Examples of the spacer portion include a polymethylene chain and a polyoxymethylene chain. The number of carbon atoms contained in the structural unit forming the spacer portion is appropriately determined depending on the chemical structure of the mesogen portion, etc. In general, in the case of a polymethylene chain, the number of carbon atoms is 1 to 20, preferably 2 to 12. Yes, in the case of a polyoxymethylene chain, the number of carbon atoms is 1 to 10, preferably 1 to 3.

Other examples of the liquid crystal polymer include a nematic liquid crystal polymer containing a low molecular chiral agent; a liquid crystal polymer incorporating a chiral component; a mixture of a nematic liquid crystal polymer and a cholesteric liquid crystal polymer. The liquid crystal polymer having a chiral component introduced therein is a liquid crystal polymer that itself functions as a chiral agent. The mixture of the nematic liquid crystal polymer and the cholesteric liquid crystal polymer can adjust the helical structure pitch of the nematic liquid crystal polymer by changing the mixing ratio thereof.
Furthermore, para-substituted cyclic compounds that impart nematic orientation, such as azomethine, azo, azoxy, ester, biphenyl, phenylcyclohexane, and bicyclohexane, consisting of para-substituted aromatic units, para-substituted cyclohexyl units, etc. Having cholesteric regularity by a method of introducing an appropriate chiral component composed of a compound having an asymmetric carbon, a low molecular chiral agent, or the like (Japanese Patent Laid-Open No. 55-21479, US Patent) (See Japanese Patent No. 5332522). Examples of the terminal substituent at the para position in the para-substituted cyclic compound include a cyano group, an alkyl group, and an alkoxyl group.

  The liquid crystal polymer is not limited by its production method. The liquid crystal polymer can be obtained, for example, by subjecting a monomer having a mesogenic structure to radical polymerization, cationic polymerization, or anionic polymerization. A monomer having a mesogenic structure can be obtained, for example, by introducing a mesogenic group into a vinyl monomer such as an acrylic ester or a methacrylic ester directly or via a spacer portion by a known method. In addition, the liquid crystal polymer can be obtained by adding a vinyl-substituted mesogenic monomer via the Si-H bond of polyoxymethylsilylene in the presence of a platinum catalyst; and a phase transfer catalyst via a functional group imparted to the main chain polymer. By introducing a mesogenic group by the esterification reaction used; a monomer having a mesogenic group introduced into a part of malonic acid via a spacer group, if necessary, and a diol can be obtained by a polycondensation reaction.

As the chiral agent to be introduced or contained in the liquid crystal polymer, for example, conventionally known ones described in JP-A-6-281814, JP-A-8-209127 and the like can be used.
Further, as the chiral agent, in order to avoid an unintended change of the phase transition temperature due to the addition of the chiral agent, a chiral agent that exhibits liquid crystallinity is preferable. Further, from the viewpoint of economy, those having a large HTP (a value defined by 1 / P · c), which is an index representing the efficiency of twisting the liquid crystal polymer, are preferable. Here, P represents the pitch length of the helical structure, and c represents the concentration of the chiral agent.

The polymerizable liquid crystal compound preferably used for the material forming the cholesteric resin layer is a liquid crystal compound having a polymerizable group. Examples of the polymerizable liquid crystal compound include a rod-like liquid crystal compound.
Examples of the rod-like liquid crystal compound include a compound represented by the formula (1).
R1-B1-A1-B3-M-B4-A2-B2-R2 Formula (1)
In addition, although A1 and A2 in Formula (1) are spacer groups so that it may mention later, this spacer group may be omitted and B1 and B3 or B4 and B2 may be directly bonded.

  In formula (1), R1 and R2 represent a polymerizable group. Specific examples of R1 and R2 that are polymerizable groups include (r-1) to (r-15) shown in Chemical Formula 1, but are not limited thereto.

  B1, B2, B3 and B4 each independently represent a single bond or a divalent linking group. Moreover, it is preferable that at least one of B3 and B4 is -O-CO-O-.

  A1 and A2 represent a spacer group having 1 to 20 carbon atoms. Examples of the spacer group include a polymethylene group and a polyoxymethylene group. The number of carbon atoms contained in the structural unit forming the spacer group is appropriately determined depending on the chemical structure of the mesogenic group, and generally in the case of a polymethylene group, the number of carbon atoms is 1 to 20, preferably 2 to 12. In the case of a polyoxymethylene group, the number of carbon atoms is 1 to 10, preferably 1 to 3.

  M represents a mesogenic group. The material for forming the mesogenic group M is not particularly limited, but azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

  As a more preferable material used for forming the cholesteric resin layer, a polymerizable composition containing the polymerizable liquid crystal compound, preferably a polymerizable composition containing the polymerizable liquid crystal compound, a polymerization initiator, and a chiral agent. Things. Examples of a method for forming a cholesteric resin layer using this material include a coating liquid in which a polymerizable liquid crystal compound, a polymerization initiator, a chiral agent, and a surfactant, an alignment regulator, and the like are dissolved in a solvent as necessary. There is a method in which a polymer liquid crystal compound in the dried film is polymerized by applying it to a support substrate in the form of a film and drying it.

  The cholesteric resin layer used in the present invention is preferably a non-liquid crystalline resin layer. This is because the cholesteric regularity does not change depending on the ambient temperature, electric field, or the like when it is non-liquid crystalline. The non-liquid crystalline cholesteric resin layer can be obtained by selecting a polymerizable composition containing a polymerizable liquid crystal compound having two or more polymerizable groups and polymerizing it. By the polymerizable liquid crystal compound having two or more polymerizable groups, a relatively rigid cross-linked structure is introduced into the cholesteric resin, and a resin that does not produce liquid crystallinity is obtained.

The polymerization initiator includes a thermal polymerization initiator and a photopolymerization initiator, and a photopolymerization initiator is preferred because the polymerization reaction is fast.
Examples of the photopolymerization initiator include polynuclear quinone compounds (US Pat. No. 3,046,127, US Pat. No. 2,951,758), oxadiazole compounds (US Pat. No. 4,212,970), α-carbonyl compounds (US Pat. No. 2,367,661, US Pat. No. 2,367,670). No. 2), acyloin ether (US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin compound (US Pat. No. 2,722,512), combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367). Gazette), acridine and phenazine compounds (Japanese Patent Laid-Open No. 60-105667, US Pat. No. 4,239,850).

The amount of the polymerization initiator is preferably 1 to 10 parts by weight and more preferably 1 to 5 parts by weight with respect to 100 parts by weight of the polymerizable liquid crystal compound. When a photopolymerization initiator is used, it is preferable to use ultraviolet rays as irradiation light, and it is particularly preferable to use ultraviolet rays having a wavelength of 320 to 390 nm (hereinafter sometimes referred to as UV-A). Irradiation energy of UV-A is preferably ^{0.1mJ / cm 2 ~50J / cm 2} , further preferably 0.1~800mJ / cm ^2.

Although the ultraviolet irradiation method is not particularly limited, in order to widen the reflection band, first, the polymerizable liquid crystal compound is irradiated with ultraviolet rays having an irradiation energy that does not cause the polymerization conversion rate to be 100%, and then the pitch of the helical structure. The method of irradiating ultraviolet rays until the polymerization conversion rate reaches 100% is preferred. The irradiation energy at which the polymerization conversion rate of the polymerizable liquid crystal compound does not reach 100% is appropriately selected depending on the type of the polymerizable liquid crystal compound. The UV-A irradiation energy at which the polymerization conversion does not reach 100% is usually 0.1 to 250 mJ / cm ² .

Examples of the method of changing the pitch of the helical structure include a method of heating within a temperature range showing a liquid crystal phase, a method of applying a composition containing a polymerizable liquid crystal compound to a photopolymerized resin layer, and a photopolymerized resin layer And a method of applying a non-liquid crystal compound. Among these, the method of heating within the temperature range showing the liquid crystal phase is preferable. The heating temperature can be appropriately selected depending on the type of the liquid crystal compound, and is usually 65 to 115 ° C. The heating time is usually 0.001 to 20 minutes, preferably 0.001 to 10 minutes, more preferably 0.001 to 5 minutes.
The ultraviolet irradiation energy until the polymerization conversion rate reaches 100% is appropriately selected depending on the kind of the polymerizable liquid crystal compound. The UV-A irradiation energy until the polymerization conversion rate reaches 100% is usually 200 to 1500 mJ / cm ² as a sum of the initial UV-A irradiation energy.

  As the chiral agent, those described in JP-A No. 2003-66214, JP-A No. 2003-313187, US Pat. No. 6,468,444, International Publication No. WO98 / 00428 and the like can be used as appropriate. From the viewpoint of economy, a large HTP that is an index representing the efficiency of twisting the liquid crystal compound is preferable. In order to avoid an unintended change in the phase transition temperature due to the addition of the chiral agent, it is preferable to use a chiral agent that exhibits liquid crystallinity.

  A surfactant can be used to adjust the surface tension of the coating solution applied to the coating solution and the supporting substrate. The surfactant is particularly preferably a nonionic surfactant. Further, it is preferably an oligomer having a molecular weight of about several thousand. Examples of such a surfactant include KH-40 manufactured by Seimi Chemical Co., Ltd.

  The said orientation regulator is for controlling the orientation state of the air side surface of the cholesteric resin layer formed on the support base material. Examples of the alignment modifier include polyvinyl alcohol, polyvinyl butyral, and modified products thereof.

  As the solvent used for preparing the coating solution, an organic solvent is preferably used. Specific examples of the organic solvent include ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, and ethers. In particular, ketones are preferable in consideration of environmental load. Two or more organic solvents may be used in combination.

  In order to apply the coating liquid into a film, a known method such as extrusion coating, direct gravure coating, reverse gravure coating, or die coating is performed.

  The supporting substrate used for applying the coating solution is not particularly limited as long as it is an optically transparent substrate, but is preferably optically isotropic in order to avoid polarization change. Examples of such a supporting substrate include a transparent resin film and a glass substrate, and a long transparent resin film is more preferable. The transparent resin film may be a single layer film or a multilayer film, but preferably has a thickness of 1 mm and a total light transmittance of 80% or more.

  The resin material of the transparent resin film includes an alicyclic structure-containing polymer resin, a chain olefin polymer such as polyethylene and polypropylene, triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, and polyether. Examples include sulfone, amorphous polyolefin, modified acrylic polymer, and epoxy resin. These can be used alone or in combination of two or more. Among these, alicyclic structure-containing polymer resins are preferable from the viewpoints of transparency, low hygroscopicity, dimensional stability, lightness, and the like.

  The alicyclic structure-containing polymer resin has an alicyclic structure in the repeating unit of the polymer resin, and the polymer resin having an alicyclic structure in the main chain and an alicyclic structure in the side chain. Any polymer resin can be used. Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, and a cycloalkane structure is preferable from the viewpoint of thermal stability. Although there is no restriction | limiting in particular in carbon number which comprises an alicyclic structure, Usually, 4-30 pieces, Preferably it is 5-20 pieces, More preferably, it is 6-15 pieces.

  The proportion of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer resin is appropriately selected according to the purpose of use, but is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight. % Or more. When there are too few repeating units having an alicyclic structure, the heat resistance of the film may be reduced.

  Specifically, the alicyclic structure-containing polymer resin includes (1) a norbornene polymer, (2) a monocyclic olefin polymer, (3) a cyclic conjugated diene polymer, and (4) vinyl fat. Examples thereof include cyclic hydrocarbon polymers and hydrogenated products thereof. Among these, norbornene-based polymers are more preferable from the viewpoints of transparency and moldability.

  Examples of the norbornene-based polymer include, for example, a ring-opening polymer of a norbornene-based monomer, a ring-opening copolymer of a norbornene-based monomer and another monomer capable of ring-opening copolymerization, and hydrogenated products thereof; Addition polymers, addition copolymers of norbornene monomers and other monomers capable of addition copolymerization, and the like can be mentioned. Among these, from the viewpoint of transparency, a ring-opening polymer hydrogenated product of a norbornene-based monomer is most preferable. The polymer having the alicyclic structure is selected from known polymers disclosed in, for example, JP-A No. 2002-321302.

  The resin material of the transparent resin film suitable for the present invention has a glass transition temperature of preferably 80 ° C. or higher, more preferably 100 to 250 ° C. A transparent resin film made of a resin material having a glass transition temperature in such a range is excellent in durability without causing deformation or stress during use at high temperatures.

  The resin material of the transparent resin film suitable for the present invention has a molecular weight of gel permeation chromatography (hereinafter abbreviated as “GPC”) using cyclohexane (toluene when the resin material is not dissolved) as a solvent. The measured weight average molecular weight (Mw) in terms of polyisoprene (when the solvent is toluene, in terms of polystyrene) is usually 10,000 to 100,000, preferably 25,000 to 80,000, more preferably 25,000. ~ 50,000. When the weight average molecular weight is in such a range, the mechanical strength and moldability of the film are highly balanced and suitable.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the resin material of the transparent resin film suitable for the present invention is not particularly limited, but is usually 1.0 to 10.0, preferably 1.0 to 4.0, more preferably in the range of 1.2 to 3.5.

  The resin material of the transparent resin film suitable for the present invention has a content of a resin component having a molecular weight of 2,000 or less (that is, an oligomer component), preferably 5% by weight or less, more preferably 3% by weight or less, and still more preferably Is 2% by weight or less. When the amount of the oligomer component is within the above range, fine convex portions are hardly generated on the surface, the thickness unevenness is reduced, and the surface accuracy is improved. In order to reduce the amount of the oligomer component, the selection of the polymerization catalyst and the hydrogenation catalyst, the reaction conditions such as polymerization and hydrogenation, the temperature conditions in the step of pelletizing the resin as a molding material, etc. may be optimized. . The amount of oligomer components can be measured by GPC as described above.

  The support substrate used in the present invention is preferably surface-treated. By performing the surface treatment, it is possible to improve the adhesion between the supporting base material and the alignment film described later. Examples of the surface treatment include glow discharge treatment, corona discharge treatment, ultraviolet treatment, and flame treatment. It is also preferable to provide an adhesive layer (undercoat layer) on the support substrate in order to improve the adhesion between the support substrate and the alignment film.

  In addition, the supporting base material used in the present invention preferably has an alignment film on the surface of the supporting base material in order to adjust the orientation direction of the helical structure of the cholesteric resin layer to be formed.

The alignment film used in the present invention is not particularly limited as long as the alignment direction of the cholesteric resin layer can be adjusted.
For example, the alignment film is formed by laminating a coating liquid mainly composed of a resin such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, or polyetherimide on a supporting substrate, drying the film, and then unidirectionally. Obtained by rubbing. By rubbing the coating layer laminated in a film shape in one direction, an alignment film capable of regulating the alignment of the resin layer having cholesteric regularity in one direction is obtained.

The rubbing method is not particularly limited, and examples thereof include a method of rubbing the alignment film in a fixed direction with a roll made of a synthetic fiber such as nylon or a natural fiber such as cotton or a felt. In order to remove fine powder (foreign matter) generated during rubbing and to clean the surface of the alignment film, it is preferable to clean the formed alignment film with isopropyl alcohol or the like. In order to give the alignment layer a function of regulating the alignment of the resin layer having cholesteric regularity in one direction in the plane, there is a method of irradiating the surface of the alignment film with polarized ultraviolet rays in addition to rubbing.
The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 to 1 μm.

The circularly polarized light separating element used in the present invention is preferably provided with a notch or a hole at the end. Among these, it is particularly preferable that a hole is provided.
For example, as shown in FIG. 8, there may be provided a hole having a circular shape, an oval shape, an elliptical shape or the like, or a notch such as an elliptical shape, a circular shape, an elliptical shape, a rectangular shape, a square shape, or a rhombus shape. These notches and holes are provided in accordance with the shape of the housing side of the liquid crystal display device, and are intended to prevent deviation due to impact or the like when the circularly polarized light separating element is attached. If there is no cutout or hole in the edge of the circularly polarized light separating element, the circularly polarized light separating element will bend due to the weight of the circularly polarized light separating element itself, especially when the liquid crystal display device is enlarged. As a result, the circularly polarized light separating element of the liquid crystal display device may be easily displaced from the mounting position.

  In the liquid crystal display device of the present invention, the linear polarizer B and the optically anisotropic element C are integrated. By being integrated, there is no space between the linear polarizer B and the optically anisotropic element C. The method of uniting is not particularly limited. For example, a method of bonding them using an adhesive or a pressure-sensitive adhesive, a method of bringing plasma into contact with these surfaces, and then crimping them are included. The adhesive or pressure-sensitive adhesive is preferably transparent to visible light, and preferably does not generate an unnecessary phase difference. When the linear polarizer B and the optically anisotropic element C are integrated, the optically anisotropic element C also functions as a protective film for the linear polarizer B. The protective film on the side close to the element C can be omitted.

The liquid crystal display device of the present invention further includes an optical anisotropic element E. As the optically anisotropic element E, an optimal element can be selected as appropriate depending on the display method of the liquid crystal cell. As the optically anisotropic element E, for example, "WV Film" (manufactured by Fuji Photo Film Co., Ltd.) are exemplified in the TN type liquid crystal cell, the IPS-type liquid crystal cell _has the relationship of _{n x =} n z> n _y Examples include a phase compensation film. The optically anisotropic element E, like the optically anisotropic element C, is formed by stretching a layer made of resin and orienting an optically anisotropic material such as a discotic liquid crystal and laminating it on a support substrate. Alternatively, it can be obtained by combining a plurality of optically anisotropic elements.

  In the present invention, it is preferable that the optically anisotropic element E, the linear polarizer B, and the optically anisotropic element C are integrated in this order. The method of uniting is not particularly limited. For example, a method of bonding them using an adhesive or a pressure-sensitive adhesive, a method of bringing plasma into contact with these surfaces, and then crimping them are included. The adhesive or pressure-sensitive adhesive is preferably transparent to visible light, and preferably does not generate an unnecessary phase difference. When the optically anisotropic element E, the linear polarizer B, and the optically anisotropic element C are integrated, the optically anisotropic element E and the optically anisotropic element C can be used as a protective film for the linear polarizer B. Since it functions, the protective films on both sides of the linear polarizer B can be omitted.

The liquid crystal display device of the present invention includes an integrated linear polarizer B and an optically anisotropic element C, or an integrated optically anisotropic element E, a linear polarizer B, an optically anisotropic element C, and circularly polarized light. It arrange | positions so that a space or a clearance gap may be formed between separation elements. By providing the space or the gap, luminance unevenness can be reduced.
As a method for forming a space or a gap, at least one of a method in which a spacer is interposed between the optically anisotropic element C and the circularly polarized light separating element, an optically anisotropic element C or the opposite surface of the circularly polarized light separating element And a method of providing an uneven shape on the surface.

The spacer to be interposed is not particularly limited, and examples thereof include a transparent film (optical element D) having a concavo-convex shape on at least one surface, transparent particles, and a transparent lattice. As a transparent film (optical element D) having an uneven shape, for example, the surface of a resin film is embossed to form an uneven shape, or a liquid containing fine particles is applied to the resin film surface and dried. For example, a concave-convex shape is used. The particle diameter of the fine particles is preferably 0.5 μm to 100 μm, and more preferably 1 μm to 50 μm.
The optical element D preferably has light diffusibility. Examples of the method for imparting light diffusibility include a method of dispersing a light diffusing material, and a method of forming a concavo-convex shape exhibiting light diffusibility on the surface. Examples of the light diffusing material include transparent fine particles such as silicone beads, polystyrene beads, and acrylic resin beads. The particle diameter of the transparent fine particles is preferably 0.5 μm to 100 μm, and more preferably 1 μm to 50 μm. Further, this light diffusing material preferably has a refractive index different from that of the material constituting the optical element D.

  The concave / convex shape provided on at least one surface of the optically anisotropic element C or the circularly polarized light separating element prevents adhesion between the optically anisotropic element C and the circularly polarized light separating element and does not deteriorate the display performance. If it is a simple shape, it will not be restrict | limited in particular. Examples of such an uneven shape include a dot pattern shape having a diameter of 0.5 μm to 500 μm; a line pattern shape having a width of 0.5 μm to 500 μm; or a shape equivalent thereto. The dot pattern shape and line pattern shape may be regular or irregular. Examples of the method for forming the concavo-convex shape include a method of embossing the surface to be formed, a method of applying a liquid containing fine particles to the surface to be formed and drying. The particle diameter of the fine particles is preferably 0.5 μm to 100 μm, and more preferably 1 μm to 50 μm. In the case of a circularly polarized light separating element, the concavo-convex shape can be formed into either a support base material or a cholesteric resin layer.

In the present invention, it is preferable that at least one of the circularly polarized light separating element or the optically anisotropic element C has light diffusibility. By having light diffusibility, chromaticity change, moiré generation, and the like can be suppressed. Haze can be used as an index of light diffusibility. When the haze has a value in a certain range, the light diffusibility becomes high. Specifically, the haze is preferably 5% or more, more preferably 5 to 70%.
Examples of a method for developing light diffusibility include a method of selecting a concavo-convex shape exhibiting light diffusibility in the concavo-convex shape of the concavo-convex shape, and a material including a transparent resin and a light diffusing material as a support base material for a circularly polarized light separating element. A method of forming the optically anisotropic element C with a light diffusing material by disturbing the helical structure of the cholesteric resin layer of the circularly polarized light separating element to cause alignment defects and exhibiting light diffusibility Examples include a method of dispersing. Examples of the light diffusing material include transparent fine particles such as silicone beads, polystyrene beads, and acrylic resin beads. This light diffusing material preferably has a refractive index different from that of the resin constituting the optically anisotropic element C. The particle diameter of the transparent fine particles is preferably 0.5 μm to 100 μm, and more preferably 1 μm to 50 μm. In addition, examples of the method for causing alignment defects include a method of adding an additive or the like to the alignment film to weaken the degree of alignment regulation; a method of disturbing the rubbing direction to partially disturb the alignment direction, and the like. .

  The liquid crystal display device of the present invention can be applied to transmissive, transflective liquid crystal display devices. The transmissive liquid crystal display device includes an illumination device. FIG. 1 shows an example of a transmissive liquid crystal display device. In FIG. 1, 1 is a liquid crystal cell, 2 is an illumination device, 3 is a linear polarizer B, 4 is a linear polarizer A, 5 is an optically anisotropic element C, and 6 is a circularly polarized light separating element.

Examples of the illumination device used in the transmissive liquid crystal display device include a direct backlight illumination device and a sidelight illumination device.
The direct type backlight illuminating device is an illuminating device in which a light source is disposed on the back surface (a side far from the viewing side) of a light emitting surface, and usually includes a light source and a light diffusion plate. The light source only needs to emit white light, and examples thereof include a cold cathode tube, a hot cathode tube, electroluminescence (EL), and a light emitting diode (LED). The light diffusing plate scatters light in order to eliminate unevenness in the in-plane distribution of luminance and generates diffused light. Specifically, what was shape | molded with resin which disperse | distributed light-diffusion materials, such as a silicone bead, is mentioned. On the front surface of the light diffusing plate, a prism array for collecting light and a recess capable of accommodating a light source for reducing the thickness of the apparatus may be formed. Further, in the direct type backlight illumination device, a reflection plate can be provided behind the light source. The reflecting plate is not particularly limited as long as it can reflect light, and specifically includes a plate provided with a reflective metal film or a white film. In addition, in order to further increase the diffusion of light emitted to the front surface, the front surface of the light diffusion plate can be provided with a resin film surface coated with a light diffusion material (sometimes referred to as a light diffusion sheet). . Furthermore, a prism sheet can be provided to collect the traveling direction of light in front.

  The sidelight type illumination device is an illumination device in which a light source is disposed on a side portion of a light emitting surface, and usually includes a light source and a light guide plate. The same light source as described above is used. The light guide plate usually has a function for directing light from a light source provided on the side surface to the front. Examples of the light guide plate include a transparent flat plate or a wedge-shaped plate provided with a projection or a depression for reflecting light, a transparent flat plate or a wedge-shaped plate having a light diffusing material dispersed therein, and the like. It is done. The light guide plate may have a prism row for collecting light on the front surface thereof. In the sidelight type illumination device, a reflection plate can be further provided behind the light source and / or on the back side of the light guide plate. In addition, a light diffusion sheet, a prism sheet, or the like can be provided on the front side of the light guide plate from which light is emitted.

FIG. 1 is a diagram showing an example of a liquid crystal display device of the present invention.
4 is a linear polarizer A, 3 is a linear polarizer B, and 5 is an optically anisotropic element C. In the liquid crystal display device of FIG. 1, a linear polarizer A and a linear polarizer B are disposed on both sides of the liquid crystal cell 1. The linear polarizer B is bonded to and integrated with the optically anisotropic element C by a double-sided adhesive sheet. And it arrange | positions so that the clearance gap may be made between the optically anisotropic element C and the circularly polarized light separation element 6. FIG.

FIG. 2 is a diagram showing another example of the liquid crystal display device of the present invention.
Reference numeral 7 denotes an optical anisotropic element E. In the liquid crystal display device of FIG. 2, the linear polarizer B has an optically anisotropic element E and an optically anisotropic element C bonded to each other by a double-sided pressure-sensitive adhesive sheet. And it arrange | positions so that the clearance gap may be made between the optically anisotropic element C and the circularly polarized light separation element 6. FIG.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Parts and% are based on weight unless otherwise specified.

(Circularly polarized light separating element)
(1) Both surfaces of a supporting substrate (a film made of norbornene polymer (manufactured by Zeon Corporation, trade name “Zeonor film ZF14”, thickness 100 μm)) were plasma-treated. A solution composed of 10 parts of polyvinyl alcohol and 371 parts of water was applied to one side of the support substrate, dried, and then rubbed to form an alignment film having a thickness of 1 μm.
Nematic liquid crystal compound (BASF, trade name “LC242”) 94.13 parts, chiral agent (BASF, trade name “LC756”) 5.87 parts, light absorber (Ciba Specialty Chemicals, 3.1 parts of a trade name “Irgacure 907”) and 0.1 part of a surfactant (trade name “KH-40” manufactured by Seimi Chemical Co., Ltd.) were dissolved in 155 parts of methyl ethyl ketone to obtain a solution. This solution was filtered using a polyfluoroethylene CD / X syringe filter having a pore size of 2 μm to prepare a liquid crystal coating solution.

A liquid crystal coating solution was applied on the alignment film so as to have a dry film thickness of 4 μm. Using an ultraviolet irradiation device [HOYA SCHOTT, device name “EXECURE 3000-W”] and a 313 nm bandpass filter, the coating film was irradiated with 0.2 mW / cm ² of ultraviolet light (UV-A) for 1 second. did. It was left in an oven at 100 ° C. for 2 minutes. Then, ultraviolet rays of 150 mJ / cm ² were irradiated using an ultraviolet irradiation device [manufactured by HOYA SCHOTT, device name “EXECURE 3000-W”]. Through the above steps, a cholesteric resin layer A having a central wavelength of 450 nm in the reflection band was formed on the support substrate.

(2) The center wavelength of the reflection band is 550 nm on another support substrate in the same manner as in (1) except that the amount of the nematic liquid crystal compound is changed to 95.19 parts and the amount of the chiral agent is changed to 4.81 parts. Cholesteric resin layer B was obtained.

(3) The center wavelength of the reflection band is 650 nm on another supporting substrate in the same manner as in (1) except that the amount of the nematic liquid crystal compound is changed to 95.93 parts and the amount of the chiral agent is changed to 4.07 parts. Cholesteric resin layer C was formed.

(4) Optical adhesives for the cholesteric resin layer A / support substrate, cholesteric resin layer B / support substrate and cholesteric resin layer C / support substrate obtained in the above (1) to (3) in order. Were bonded together to obtain a circularly polarized light separating element. The total thickness of the cholesteric resin layer was 12 μm, and the total thickness of the circularly polarized light separating element was 315 μm. Moreover, it had a circularly polarized light separation function for light in the entire visible light range.

(Optically anisotropic element C ^a )
Styrene-maleic anhydride copolymer [manufactured by Nova Chemical Co., Ltd., trade name “DILARK D332”, Tg = 131 ° C., resin exhibiting negative intrinsic birefringence], norbornene resin [manufactured by Nippon Zeon Co., Ltd., trade name “ZEONOR 1020 ”, Tg = 105 ° C., resin exhibiting positive intrinsic birefringence], and a norbornene-based resin layer (thickness 50 μm) / styrene-maleic anhydride copolymer layer (thickness 200 μm) / A laminated film having a three-layer structure of a norbornene resin layer (thickness 50 μm) was obtained.
The laminated film was stretched retardation Re at a wavelength of 550nm is 135 nm, the retardation Rth give an optically anisotropic element ^{C a} of -250Nm.

(Optically anisotropic element C ^b )
Optically anisotropic element C having a retardation Re at 135 nm and a retardation Rth of 70 nm at a wavelength of 550 nm by uniaxially stretching a film made of norbornene-based polymer (manufactured by Nippon Zeon Co., Ltd., trade name “Zeonor film ZF14”, thickness 100 μm). ^b1 was obtained.
A laminated film having a three-layer structure of norbornene-based resin layer (thickness 50 μm) / styrene-maleic anhydride copolymer layer (thickness 200 μm) / norbornene-based resin layer (thickness 50 μm) is simultaneously biaxially stretched, retardation Re at a wavelength of 550nm is 5 nm, the retardation Rth was obtained an optically anisotropic element ^{C b2} of -350 nm.
The optically anisotropic element ^{C b1} and the optically anisotropic element ^{C b2} and a pressure-sensitive adhesive (3M Co., Ltd. under the trade name "8142", thickness of 50μm) attached to each other with the retardation Re is 137nm, retardation Rth is - to obtain an optical anisotropic element ^{C b} of 230 nm.

(Optically anisotropic element F)
Optically anisotropic element F having a retardation Re of 135 nm and a retardation Rth of 70 nm at a wavelength of 550 nm by uniaxially stretching a film made of norbornene-based polymer (manufactured by Zeon Corporation, trade name “Zeonor film ZF14”, thickness 50 μm). Got.

Example 1
An optically anisotropic element Ca, ^a polarizing plate ( ^a protective film is bonded to both sides of a linear polarizer), and a glass plate in this order are adhesives (manufactured by Sumitomo 3M, “8142”, thickness 50 μm). And pasted together.
As shown in FIG. 3, the circularly polarized light separating element 6 and the bonded body of the optically anisotropic element ^Ca , the polarizing plate 3 and the glass plate 9 are sequentially stacked on the backlight illumination device 2. A polarized illumination device was obtained. Circle between the polarization separation element and the optically anisotropic element C ^a is arranged to float so as not to contact.

(Example 2)
To obtain a polarizing illumination device in addition to replacing the optical anisotropic element C ^a optically anisotropic element C ^b in the same manner as in Example 1.

(Example 3)
As shown in FIG. 4, the film 10 having a satin surface (uneven shape having light diffusibility) on one side and the optically anisotropic element C ^a are bonded together with a double-sided pressure-sensitive adhesive sheet with the smooth surfaces aligned. Polarization is performed in the same manner as in Example 1 except that the pear ground faces the polarization separation element side so that ^a gap is formed by the pear ground between the circular polarization separation element and the optically anisotropic element Ca. A lighting device was obtained.

Example 4
As shown in FIG. 5, a film 11 having a satin surface (concavo-convex shape having a light diffusing property) on both sides, it is arranged between the circularly polarized light separation element and the optically anisotropic element C ^a, so a gap Otherwise, a polarized illumination apparatus was obtained in the same manner as in Example 1.

(Example 5)
A film having a satin surface (uneven shape with light diffusibility) on one side, a film made of resin in which silicone beads (light diffusing material) are dispersed, and having a satin surface (uneven shape with light diffusibility) on one side A polarized illuminating device was obtained in the same manner as Example 3 except for the replacement.

(Example 6)
Implemented except that the film with a satin surface (irregular shape with light diffusibility) on both sides was replaced with a film made of resin with dispersed silicone beads and with a satin surface (irregular shape with light diffusibility) on both sides A polarized illumination device was obtained in the same manner as in Example 4.

(Comparative Example 1)
As shown in FIG. 6, the glass plate and the polarizing plate were bonded together with the double-sided adhesive sheet. On the backlight illumination device, the bonded body of the polarizing plate and the glass plate was placed to obtain a polarization illumination device.

(Comparative Example 2)
To obtain a polarizing illumination device in addition to replacing the optical anisotropic element C ^a optically anisotropic element F in the same manner as in Example 1.

(Comparative Example 3)
As shown in FIG. 7, a circularly polarized light separating element, an optically anisotropic element Ca, a polarizing plate ( ^a protective film is bonded to both surfaces of a linear polarizer), and a glass plate in this order, A double-sided PSA sheet (manufactured by Sumitomo 3M, “9483”) was attached and integrated. On the backlight illuminating device, the above-mentioned circularly polarized light separating element, optically anisotropic element Ca, ^a polarizing plate and a glass plate were mounted to obtain a polarized illuminating device.

(Evaluation 1) Luminance The lighting device is turned on, and the luminance in the front direction and the luminance in the direction of 60 degrees (oblique direction) with respect to the front direction are measured using a luminance meter (product name “BM-7” manufactured by TOPCON). It was measured. The results are shown in Table 1.
In Table 1, the luminance in the front direction is a relative value when the luminance of Comparative Example 1 is 1, and the luminance in the oblique direction is a relative value when the luminance of Comparative Example 2 is 1.

(Evaluation 2) Peeling The lighting device was turned on for 8 hours and turned off for 16 hours. And the interface of a cholesteric resin layer and a support base material was observed, and the presence or absence of peeling was investigated. The evaluation results are shown in Table 1.

(Evaluation 3) Luminance unevenness and moire After performing Evaluation 2, the following operations were performed.
The lighting device was turned on and visually observed from the front to check for the presence of uneven brightness and moire. The evaluation results are shown in Table 1.
Luminance unevenness A: The portion where the luminance was lowered was seen as a patch over the entire surface.
Luminance unevenness B: The portion where the luminance was lowered was uniformly seen at the end.

(Measurement method of front-side letter Re and thickness direction retardation Rth)
Obtained using KOBRA (Oji Scientific Instruments).

From the results in Table 1, the following can be understood.
According to the present invention, as shown in Examples 1 to 6, the luminance in the front direction and the oblique direction was good, and no peeling occurred in the cholesteric resin layer constituting the circularly polarized light separating element. Among the examples, those having the film having the uneven shape (Examples 3 to 6) did not have display defects such as luminance unevenness and moire.
On the other hand, Comparative Example 2 using an optically anisotropic element C having an Rth of 70 nm, or Comparative Example in which an optically anisotropic element C and a circularly polarized light separating element are bonded with a double-sided adhesive sheet so that there is no gap For No. 3, peeling occurred in the cholesteric liquid crystal layer, resulting in luminance unevenness and moire.

It is sectional drawing which shows the structure of one example of the liquid crystal display device of this invention. It is sectional drawing which shows the structure of another example of the liquid crystal display device of this invention. It is sectional drawing showing the structure of the polarization illumination apparatus produced in Examples 1-2. It is sectional drawing showing the structure of the polarization illumination apparatus produced in Example 3 and Example 5. FIG. It is sectional drawing showing the structure of the polarization illumination apparatus produced in Example 4 and Example 6. FIG. 10 is a cross-sectional view illustrating a configuration of a polarization illumination device manufactured in Comparative Example 1. FIG. 10 is a cross-sectional view illustrating a configuration of a polarization illumination device manufactured in Comparative Example 3. FIG. It is a figure which shows the example of a shape of a circularly-polarizing element.

Explanation of symbols

1: liquid crystal cell, 2: illumination device, 3: linear polarizer B, 4: linear polarizer A, 5: optically anisotropic element C, 6: circularly polarized light separating element, 7: optically anisotropic element E, 9 : Glass plate, 10: Film with pear ground on one side, 11: Film with pear ground on both sides, A: Double-sided PSA sheet

Claims (14)

  Linear polarizer A; liquid crystal cell; linear polarizer B; optically anisotropic element C having a retardation Re in the front direction of about ¼ of the wavelength of transmitted light and a retardation Rth in the thickness direction of less than 0 nm; And the circularly polarized light separating element in this order, the linear polarizer B and the optically anisotropic element C are integrated, and a space is formed between the optically anisotropic element C and the circularly polarized light separating element. A liquid crystal display device arranged in such a manner.   The liquid crystal display device according to claim 1, wherein at least one of two opposing surfaces between the circularly polarized light separating element and the optically anisotropic element C is provided with an uneven shape.   The liquid crystal display device according to claim 1, wherein a spacer is interposed between the linear polarizer B and the optically anisotropic element C integrated with the circularly polarized light separating element.   The liquid crystal display device according to claim 1, wherein at least one of the circularly polarized light separating element and the optically anisotropic element C has light diffusibility.   The liquid crystal display device according to claim 1, wherein the circularly polarized light separating element has a support base and a resin layer having cholesteric regularity.   6. The liquid crystal display device according to claim 5, wherein the total thickness of the circularly polarized light separating element is 140 to 350 [mu] m, and the total thickness of the resin layers having cholesteric regularity is 4 to 20 [mu] m.   The liquid crystal display device according to claim 5, wherein the support base material of the circularly polarized light separating element is formed by molding a material containing a transparent resin and a light diffusing material.   The liquid crystal display device according to claim 5, wherein the resin layer having cholesteric regularity of the circularly polarized light separating element has an alignment defect.   The liquid crystal display device according to claim 5, wherein the resin layer having cholesteric regularity is non-liquid crystalline.   The liquid crystal display device according to claim 5, wherein the resin layer having cholesteric regularity is obtained by polymerizing a polymerizable liquid crystal compound.   The liquid crystal display device according to any one of claims 1 to 10, further comprising an optical element D having uneven shapes on both sides between the circularly polarized light separating element and the optically anisotropic element C.   The liquid crystal display device according to claim 1, wherein the optically anisotropic element C is a combination of a plurality of optically anisotropic elements. Optically anisotropic element C, the retardation Re in the front direction and approximately 1/4 of the optical anisotropic element C ₁ in the wavelength of the transmitted light, and the thickness direction retardation in the front direction of the retardation Re approximately 0nm The liquid crystal display device according to claim 1, comprising a combination with an optically anisotropic element C ₂ having an Rth of less than 0 nm.   An optical anisotropic element E is further provided between the liquid crystal cell and the linear polarizer B, and the optical anisotropic element E, the linear polarizer B, and the optical anisotropic element C are integrated in this order. The liquid crystal display device according to claim 1.

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