CN104516043A - Polarizing plate, image display device, and improvement method of photopic contrast in image display device - Google Patents

Polarizing plate, image display device, and improvement method of photopic contrast in image display device Download PDF

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Publication number
CN104516043A
CN104516043A CN201410498557.2A CN201410498557A CN104516043A CN 104516043 A CN104516043 A CN 104516043A CN 201410498557 A CN201410498557 A CN 201410498557A CN 104516043 A CN104516043 A CN 104516043A
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CN
China
Prior art keywords
light transmissive
polaroid
polarizer
transmissive film
display device
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CN201410498557.2A
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Chinese (zh)
Inventor
黑田刚志
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Dai Nippon Printing Co Ltd
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Dai Nippon Printing Co Ltd
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Publication of CN104516043A publication Critical patent/CN104516043A/en
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3083—Birefringent or phase retarding elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • 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
    • G02B27/32—Fiducial marks and measuring scales within the optical system
    • G02B27/36—Fiducial marks and measuring scales within the optical system adjustable
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133502—Antiglare, refractive index matching layers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G02F1/133638—Waveplates, i.e. plates with a retardation value of lambda/n

Abstract

The invention provides a polarizing plate, an image display device, and improvement method of photopic contrast in the image display device. When a viewer watches images displayed on a liquid crystal display device through polarized sunglasses, a certain degree of visibility under an orthogonal Nicole state can be ensured. Compared with the condition that a transparent film having birefringence disposed in a surface according to the angle being 45 DEG of a fast axis direction with respect to the absorption axis direction of a polarization element, the transmittance under a parallel Nicole state suitable for common observation can be improved, and the photopic contract when a viewer watches the image display device with eyes without wearing the polarized sunglasses can be improved.

Description

The ameliorative way of the daylight contrast of polaroid, image display device and image display device
Technical field
The present invention relates to the ameliorative way of the daylight contrast of polaroid, image display device and image display device.
Background technology
In liquid crystal indicator, be usually configured with polaroid (upper polarizer) in the picture display face side of liquid crystal cell.Upper polarizer is made up of the diaphragm for the protection of polarizer of polarizer and the one side that is fitted in polarizer usually, and above-mentioned polarizer is utilize iodine etc. to carry out dyeing and the polyvinyl alcohol film etc. that obtains of drawn.
In the past, as diaphragm, use the film be made up of the cellulose esters taking triacetyl cellulose as representative.This is based on such as inferior advantage: because the transparency of cellulose esters, optical isotropy are excellent, and having the water permeability of appropriateness, thus the moisture remained in polarizer can be made to carry out drying through cellulose ester membrane when manufacturing polaroid.
But the moisture permeability of cellulose esters is too high, therefore exists when carrying out humidity test and cause transmitance to rise or degradation problem under degree of polarization because fading.In order to solve this problem, propose the polaroid (see the flat 6-51117 publication of Japanese Laid-Open) using cyclic olefin resins as diaphragm.In addition; in order to improve permanance; also expect to use than cellulose ester membrane cheap and in the market the easy versatility film obtaining or can obtain with easy method manufacture as diaphragm; such as; as the substitute of cellulose ester membrane, attempt make use of the polyester films such as polyethylene terephthalate (for example, see Japanese Laid-Open 27-279243 publication).
But, the liquid crystal indicator of subnotebook PC etc. not only for indoor, sometimes also in outdoor application.In outdoor, observer wears polarized sunglasses sometimes, when observer watches the display image of liquid crystal indicator through polarized sunglasses, due to the absorption axle of upper polarizer and the absorption axle angulation of polarized sunglasses, likely make display image dimmed and be difficult to see, visually decline.Herein, " visuality " in this instructions refers to, for representing whether observer is difficult to see the index showing image because of viewing angle through during polarized sunglasses viewing display image.
In order to solve this problem, proposing according to fast axle (Jin Xiang Shaft) direction is the observer side (for example, see Japanese Laid-Open 2009-122454 publication) that λ/4 phase retardation film is configured in upper polarizer by the mode of 45 degree relative to the axial angle of the absorption of the polarizer of upper polarizer.
In addition, also proposed the slow axis (Rather-late Xiang Shaft of the polyethylene terephthalate film according to the delay making to have 3000nm ~ 30000nm) being 45 degree with the absorption axle angulation of polaroid, mode is configured (for example, see Japanese Unexamined Patent Publication 2011-107198 publication).
Summary of the invention
The problem that invention will solve
For the image display device that can use at indoor and outdoors, when observer watches the display image of liquid crystal indicator through polarized sunglasses, certain expectation is guaranteed good visuality and is not limited to viewing angle, especially expects to improve daylight contrast when observing image display device in indoor with visual (not wearing the state of polarized sunglasses).Herein; the polaroid possessing the diaphragm be made up of various material is attempted to be used for image display device; found that; use by polyester film, be typically protective film for polarizing plate that polyethylene terephthalate forms time, the daylight contrast of image display device is increased to can with the degree of visual perception.The present inventor conducts in-depth research repeatedly to this phenomenon, found that, the raising of the fast axle of the diaphragm relevant to the birefraction that polyester film has usually and the daylight contrast of image display device has correlationship.In more detail, find that the quick shaft direction being assembled in the diaphragm under the state in image display device can bring very large impact to the daylight contrast of image display device.
In addition, as polarisation of light component, there is P polarized light and S polarized light, but P polarized light exists the Brewster angle that reflectivity is 0%, when therefore light is reflected, P polarized light reduces, and result S polarized light increases.Therefore, if polarized sunglasses can be utilized to absorb S polarized light, then reflected light can be ended.For this reason, the absorption axle of polarized sunglasses is present on left and right directions usually.Therefore, observer wear polarized sunglasses and be the display image of the image display device of horizontal direction with the absorption direction of principal axis that the posture (the absorption direction of principal axis of polarized sunglasses is the posture of general horizontal direction) being applicable to usually observing display image watches the upper polarizer of VA pattern or IPS pattern and so on time, polarized sunglasses and upper polarizer are in the state of parallel-nicol.Transmittance when the present inventor is in the state of parallel-nicol to polarized sunglasses and upper polarizer conducts in-depth research repeatedly, and found that, the quick shaft direction of diaphragm brings very large impact to transmittance.
The present invention is based on this opinion of the present inventor, its object is to provide a kind of polaroid and image display device, wherein, when observer watches the display image of liquid crystal indicator through polarized sunglasses, the visuality under crossed Nicol state to a certain degree can be guaranteed, and compared to being configured in face the situation of the light transmissive film with birefringence relative to the mode that the axial angle of the absorption of polarizer is 45 degree according to quick shaft direction, the transmittance under the parallel-nicol state being applicable to usually observing can be improved, and the daylight contrast can improved when observing image display device with visual (not wearing the state of polarized sunglasses).
For the means of dealing with problems
According to a scheme of the present invention, a kind of polaroid is provided, it possesses polarizer, with the polaroid of light transmissive film in face of observer side being arranged at above-mentioned polarizer, this light transmissive film has birefringence in face, the feature of above-mentioned polaroid is, above-mentioned polarizer is configured according to the light absorption direction of principal axis mode in the horizontal direction of above-mentioned polarizer, and using direction maximum for the refractive index in the face of above-mentioned light transmissive film as slow-axis direction, during using the direction intersected vertically with above-mentioned slow-axis direction in above-mentioned as quick shaft direction, above-mentioned light transmissive film is more than 5 degree according to above-mentioned quick shaft direction relative to the axial angle of above-mentioned absorption and the mode of less than 40 degree is configured.
According to another aspect of the present invention, provide a kind of image display device, it possesses above-mentioned polaroid, and above-mentioned polaroid is configured according to the absorption direction of principal axis mode in the horizontal direction of above-mentioned polarizer.
According to another aspect of the present invention, a kind of ameliorative way of daylight contrast of image display device is provided, it is characterized in that, above-mentioned polaroid is configured at image display device according to the absorption direction of principal axis mode in the horizontal direction of the above-mentioned polarizer in above-mentioned polaroid.
Invention effect
According to the polaroid of a scheme of the present invention, use the light transmissive film with birefringence consciously, the configuration of polarizer is carried out according to the absorption direction of principal axis mode in the horizontal direction of polarizer, and be more than 5 degree according to the quick shaft direction of light transmissive film relative to the axial angle of the absorption of polarizer and the mode of less than 40 degree carries out the configuration of light transmissive film, thus the visuality under crossed Nicol state to a certain degree can be guaranteed when the display image of observer through polarized sunglasses viewing liquid crystal indicator, and compared to being configured in face the situation of the light transmissive film with birefringence relative to the mode that the axial angle of the absorption of polarizer is 45 degree according to quick shaft direction, the transmittance under the parallel-nicol state being applicable to usually observing can be improved, and the daylight contrast that can improve when observing image display device with visual (not wearing the state of polarized sunglasses).
Image display device according to another aspect of the present invention, polarizer is configured according to the absorption direction of principal axis mode in the horizontal direction of polarizer, and light transmissive film is more than 5 degree according to the quick shaft direction of light transmissive film relative to the axial angle of the absorption of polarizer and the mode of less than 40 degree is configured, thus the visuality under crossed Nicol state to a certain degree can be guaranteed when the display image of observer through polarized sunglasses viewing liquid crystal indicator, and compared to being configured in face the situation of the light transmissive film with birefringence relative to the mode that the axial angle of the absorption of polarizer is 45 degree according to quick shaft direction, the transmittance under the parallel-nicol state being applicable to usually observing can be improved, and the daylight contrast that can improve when observing image display device with visual (not wearing the state of polarized sunglasses).
The ameliorative way of the daylight contrast of image display device according to another aspect of the present invention, polarizer is configured according to the absorption direction of principal axis mode in the horizontal direction of polarizer, and light transmissive film is more than 5 degree according to the quick shaft direction of light transmissive film relative to the axial angle of the absorption of polarizer and the mode of less than 40 degree is configured, thus the visuality under crossed Nicol state to a certain degree can be guaranteed when the display image of observer through polarized sunglasses viewing liquid crystal indicator, and compared to being configured in face the situation of the light transmissive film with birefringence relative to the mode that the axial angle of the absorption of polarizer is 45 degree according to quick shaft direction, the transmittance under the parallel-nicol state being applicable to usually observing can be improved, and the daylight contrast that can improve when observing image display device with visual (not wearing the state of polarized sunglasses).
Accompanying drawing explanation
Fig. 1 is the longitudinal section of the polaroid that embodiment relates to.
Fig. 2 is the figure of the display polaroid that relates to of embodiment and the configuration relation of polarized sunglasses and the polarisation of light state through polaroid.
Fig. 3 is the schematic pie graph of the liquid crystal display of an example of the image display device related to as embodiment.
Embodiment
Below, with reference to accompanying drawing, the polaroid that embodiments of the present invention relate to is described.Fig. 1 is the longitudinal section of polaroid of the present embodiment, and Fig. 2 is the figure of display polaroid of the present embodiment and the configuration relation of polarized sunglasses and the polarisation of light state through polaroid.It should be noted that, in this manual, the term such as " film ", " sheet ", " plate " is only the difference based on address, is not want Xiang Hu Qu Do.Therefore, such as " film " is the concept of the parts also comprising and can be referred to as sheet or plate.As a concrete example, in " light transmissive film ", also comprise the parts being referred to as " light transmission sheet " or " light transmission plate ".In this manual, " weight-average molecular weight " to be dissolved in tetrahydrofuran (THF) equal solvent by known gel permeation chromatography (GPC) method and the value obtained according to polystyrene conversion.
" polaroid "
As shown in Figure 1, polaroid 10 possesses polarizer 11, is arranged at the light transmissive film 12 in the face of the observer side of polarizer 11 and is arranged at the functional layer 13 in face of the side contrary with the face being provided with polarizer 11 of light transmissive film 12.As long as polaroid of the present invention possesses polarizer and light transmissive film, also functional layer can not be possessed.
< polarizer >
Polarizer 11 has absorption axle, and as shown in Figure 2, polarizer 11 is configured according to the absorption direction of principal axis 11A mode in the horizontal direction of polarizer 11." the absorption direction of principal axis of polarizer is in the horizontal direction " refers to, the absorption direction of principal axis of polarizer be in relative to horizontal direction be less than ± scope of 10 ° in.Polarizer 11 preferably according to the absorption direction of principal axis 11A of polarizer 11 relative to horizontal direction for being less than ± scope of 5 ° in mode be configured.
As polarizer 11, can enumerate and such as utilize iodine etc. to carry out dyeing and the polyvinyl alcohol film of drawn, polyvinyl formal film, Polyvinyl acetal film, vinyl-vinyl acetate copolymer system saponification film etc.
< light transmissive film >
Light transmissive film 12 plays function as the diaphragm for the protection of polarizer 11.Light transmissive film 12 has birefringence in face.Whether have in face in the judgement of birefringence in light transmissive film, for the refractive index of wavelength 550nm, by Δ n (Δ n=n x-n ythe situation of)>=0.0005 is considered as having birefringence, and the situation of Δ n<0.0005 is considered as not having birefringence.The KOBRA-WR that birefraction can use prince to measure machine society to manufacture, set and measure angle and be 0 ° and mensuration wavelength measures as 552.1nm.Now, the calculating of birefraction needs thickness, mean refractive index.Thickness can use such as milscale (manufacture of Digimatic Micrometer, Mitutoyo company) or electronic microcalliper (manufacture of Anritsu company) to measure.Mean refractive index can use Abbe refractomecer or ellipsometer to measure.
Be respectively 0.0000375,0.00005 usually used as the known TD80UL-M (manufacture of Fujiphoto society) be made up of triacetyl cellulose of isotropic material, the Δ n of ZF160-100 (Nippon Zeon's manufacture) that is made up of cyclic olefin polymer according to said determination method, be judged as that not there is birefringence (isotropy).
In addition, as the birefringent method of mensuration, two pieces of polaroids can be used, obtain the axis of orientation direction (direction of main shaft) of Mght-transmitting base material, utilize Abbe refractomecer (NAR-4T that Atago company manufactures) to obtain the refractive index (n of two axles intersected vertically relative to axis of orientation direction x, n y); Also can to fit overleaf black pvc insulating tape (such as Yamato Vinyl Tape N0200-38-2138mm is wide), then spectrophotometer (V7100 type, automatically absolute reflectance determination unit, light splitting society of VAR-7010 Japan system) is used, utilize polarimetry: S polarized light, for S polarized light, 5 degree of corner reflection rates when measuring parallel with making fast axle when making slow axis parallel, calculate the refractive index (n of each wavelength of slow axis and fast axle according to following formula (1) x, n y).
R (%)=(1-n) 2/ (1+n) 2formula (1)
The length of delay of light transmissive film 12 is just not particularly limited so long as not 0.Above-mentioned " delay " refers to the refractive index n according to the slow-axis direction in the face of light transmissive film x, light transmissive film face in the refractive index n of quick shaft direction ywith the value that the thickness d of light transmissive film is represented by following formula (2).
Postpone (Re)=(n x-n y) × d ... formula (2)
For length of delay, as the length of delay of the light for wavelength 550nm, be preferably 80nm ~ 150nm or more than 3000nm.If length of delay is less than 80nm, then sometimes fully cannot guarantee visuality when observer observes the display image of display device through polarized sunglasses.Further, its reason is also, when being less than 3000nm, sometimes observes interference color, see the color different from the tone of the display image of reality at length of delay more than 150nm.In addition, never require that the viewpoint of thickness precision is set out, compared to 80nm ~ 150nm, length of delay is particularly preferably more than 3000nm.Specifically, this is because, when such as using Δ n to be the material of 0.1, if length of delay is 80nm ~ 150nm, then needing according to thickness d is that 0.8 μm ~ 1.5 μm (within deviations 0.7 μm) make, and when length of delay is more than 3000nm, as long as thickness d is more than 30 μm.
Above-mentioned delay such as can measure by prince the KOBRA-WR that machine society manufactures and carry out measuring (measure 0 °, angle, measure wavelength 589.3nm).In addition, Abbe refractomecer (NAR-4T that Atago company manufactures) is utilized to measure the slow axis of light transmissive film and the refractive index (n of fast axle x, n y), and utilize electronic microcalliper (manufacture of Anritsu company) to measure light transmissive film thickness d (μm), be nm by unit conversion.Further, calculated refractive index (n can be used x, n y) and thickness d obtain delay according to formula (2).In addition, delay can be obtained as described above, and for S polarized light, 5 degree of corner reflection rates when measuring parallel with making fast axle when making slow axis parallel, obtain n by above formula (1) xand n y, the n obtained by this xand n ydifference and the product of light transmissive film thickness obtain delay.
Using direction maximum for the refractive index in the face of light transmissive film 12 as slow-axis direction 12A, using the direction intersected vertically with slow-axis direction 12A in this face as quick shaft direction 12B time, as shown in Figure 2, light transmissive film 12 is more than 5 degree according to the quick shaft direction 12B of light transmissive film 12 relative to the angle [alpha] of the absorption direction of principal axis 11A of polarizer 11 and the mode of less than 40 degree is configured.Therefore, the position of the quick shaft direction 12B of light transmissive film 12 determines relative to the absorption direction of principal axis 11A of polarizer 11.From the view point of guarantee through polarized sunglasses visuality and improve the balance of daylight contrast, the quick shaft direction 12B of light transmissive film 12 be preferably more than 10 degree relative to the angle [alpha] of the absorption direction of principal axis 11A of polarizer 11 and less than 35 degree, be more preferably more than 15 degree and less than 30 degree.
For light transmissive film 12, the refractive index n of the slow-axis direction 12A of light transmissive film 12 xwith the refractive index n of the quick shaft direction 12B as the direction intersected vertically with slow-axis direction 12A ydifference Δ n be preferably more than 0.01 and less than 0.30.If refractive indices n is less than 0.01, reflection differences when slow axis and fast axle being arranged at horizontal direction diminishes, and the effect of the raising daylight contrast obtained diminishes.On the other hand, if refractive indices n is more than 0.30, then causes needing excessively to improve stretching ratio, thus easily produce cracking, breakage etc., make the practicality as industrial materials significantly decline sometimes.The lower limit of refractive indices n is preferably 0.05, is more preferably 0.07.The preferred upper limit of refractive indices n is 0.27.It should be noted that, when refractive indices n is more than 0.27, according to the kind of light transmissive film, the permanance of light transmissive film in humidity resistance test is deteriorated sometimes.From the view point of the excellent durability guaranteed in humidity resistance test, the preferred upper limit of refractive indices n is 0.25.
As light transmissive film 12, as long as the light transmissive film in face with birefringence is just not particularly limited.As this light transmissive film, such as polyester film, polycarbonate membrane, cyclo-olefin-polymer films, acrylic acid mesentery etc. can be enumerated.Among them, the effect of the daylight contrast that greatly, is easily improved from the view point of the expression power of refractive indices n, preferred polyester film, polycarbonate membrane.It should be noted that, even cellulose ester membrane, as long as carry out stretching and the face Inner of making has the cellulose ester membrane of birefringence, then also can use.
As polyester film, polyethylene terephthalate, polyethylene glycol isophthalate, polybutylene terephthalate, poly-(1 can be enumerated, 4-cyclohexene dimethylene terephthalate), PEN (tygon-2,6-naphthalate, tygon-1,4-naphthalate, tygon-1,5-naphthalate, tygon-2,7-naphthalate, tygon-2,3-naphthalate) etc.
The polyester used in polyester film both can be the multipolymer of these above-mentioned polyester, also can be based on the material of above-mentioned polyester (such as the composition of more than 80 % by mole) with the mixed with resin of other kind of low ratio (such as less than 20 % by mole).As polyester, because the balance of the mechanics physical property, optics physical property etc. of polyethylene terephthalate (PET) or tygon-NDA ester (PEN) is good, because of but particularly preferred.Especially preferably containing polyethylene terephthalate.The versatility of polyethylene terephthalate is high, easily obtains, and can increase birefringence.
As polycarbonate membrane, the fatty poly-ester carbonate such as aromatic carbonate film, the diethylene glycol bis-allyl carbonate film etc. such as based on bisphenols (bisphenol-A etc.) can be enumerated.
As cyclo-olefin-polymer films, the film be such as made up of polymkeric substance such as norborneol alkene monomer and monocyclic cycloalkenyl hydrocarbon monomers can be enumerated.
As acrylic acid mesentery, such as poly-(methyl) methyl acrylate film, poly-(methyl) ethyl acrylate film, (methyl) methyl acrylate-(methyl) butyl acrylate copolymer film etc. can be enumerated.
As cellulose ester membrane, such as tri acetyl cellulose membrane, diacetyl cellulose film can be enumerated.The light transmission of cellulose ester membrane is excellent, preferred tri acetyl cellulose membrane (TAC film) among cellulose acylate film.Tri acetyl cellulose membrane be can visible region 380 ~ 780nm make average transmittance be more than 50% light transmissive film.The average transmittance of tri acetyl cellulose membrane is preferably more than 70%, more preferably 85%.
It should be noted that, as tri acetyl cellulose membrane, except pure triacetyl cellulose, it also can be the material share the composition beyond acetic acid with the form forming the fatty acid of ester with cellulose of cellulose acetate propionate, cellulose acetate butyrate and so on.In addition, also the various adjuvants such as other cellulose lower fatty acid ester or plastifier, ultraviolet light absorber, anticlogging agent etc. such as diacetyl cellulose can be added as required in these triacetyl celluloses.
As the thickness of light transmissive film 12, be preferably more than 5 μm and in the scope of less than 300 μm.If be less than 5 μm, then the anisotropy of mechanical characteristic becomes remarkable, easily produces cracking, breakage etc., makes the practicality as industrial materials significantly decline sometimes.On the other hand, if more than 300 μm, then the rigidity of light transmissive film is very high, and the distinctive flexibility of polymeric membrane declines, and the practicality as industrial materials still can be made to decline, because of but not preferred.The preferred lower limit of above-mentioned light transmissive film thickness is 10 μm, and the preferred upper limit is 200 μm, preferably the upper limit is 150 μm further.
In addition, for light transmissive film 12, the transmitance of visible region is preferably more than 80%, is more preferably more than 84%.It should be noted that, above-mentioned transmitance can measure according to JIS K7361-1 (test method of the total light transmittance of plastics-transparent material).
It should be noted that, without departing from the scope of spirit of the present invention, also can carry out the surface treatments such as saponification process, glow discharge process, Corona discharge Treatment, ultraviolet (UV) process and flame treatment to light transmissive film.
Light transmissive film 12 can use the light transmissive film after vertical unilateral stretching, stenter stretching, successively two-way stretch and two-way stretch simultaneously.Wherein, preferred oblique extension, wherein, stretches according to making not parallel with Width with the direct of travel of the light transmissive film mode of the direction of orientation of molecule.The polarizer of roll manufactures to obtain its stretch processing being carried out to very high-precision management while, therefore except special circumstances, absorb axle to exist along its length, thus the light transmissive film after oblique extension and polarizer are fitted by volume to volume method, the absorption direction of principal axis that can form polarizer thus and the angulation of the quick shaft direction of light transmissive film have parallel with intersect vertically beyond the polaroid of angulation.
< functional layer >
As mentioned above, functional layer 13 is arranged at the face of the side contrary with the face being provided with polarizer 11 of light transmissive film 12.Functional layer 13 refers to that intention plays the layer of certain function, specifically, can enumerate the layer of performance such as more than one functions such as painting property, anti-glare, antireflection, antistatic behaviour or soil resistance firmly.For functional layer 13, the refractive index in the direction parallel with quick shaft direction 12B of light transmissive film 12 is lower than the refractive index of the quick shaft direction 12B of light transmissive film 12.It should be noted that, when the functional layer using the refractive index in the direction parallel with slow-axis direction of light transmissive film higher than the refractive index of the slow-axis direction of light transmissive film, light transmissive film is preferably configured according to the slow-axis direction mode in the horizontal direction of light transmissive film.
It should be noted that, in the side contrary with being provided with light transmissive film 12 side of functional layer 13, also can be provided with other functional layer of more than one deck.As other functional layer, the layer of the performance same with above-mentioned functions layer 13 more than one functions such as painting property, anti-glare, antireflection, antistatic behaviour or soil resistance firmly can be exemplified.
(hard conating)
Hard conating is the layer playing hard painting property, specifically, has the hardness of more than " H " in the pencil hardness test specified by JIS K 5600-5-4 (1999) (4.9N load).
The thickness of hard conating is preferably more than 1.0 μm and less than 10.0 μm.As long as the thickness of hard conating is within the scope of this, then can obtain desired hardness.In addition, the filming of hard conating can be realized, on the other hand, hard conating can be suppressed to produce and break and warpage.The thickness of hard conating can be observed the cross section of (multiplying power is preferably more than 10,000 times) hard conating by utilizing transmission electron microscope (TEM, STEM) thus obtain.Specifically, use the image of transmission electron microscope, in piece image, measure the thickness of the 1st hyaline layer of three positions, this measurement is carried out to five width images, calculates the mean value of measured thickness.The lower limit of the thickness of hard conating is more preferably more than 1.5 μm, and the upper limit is more preferably less than 7.0 μm, the thickness of hard conating more preferably more than 2.0 μm and less than 5.0 μm.
Hard conating is such as at least containing adhesive resin.Adhesive resin is penetrated by illumination and is made photopolymerizable compound be polymerized (being cross-linked) and obtain.Photopolymerizable compound has at least one optical polymerism functional group.In this instructions " optical polymerism functional group " refers to that penetrated by illumination can the functional group of polymerization reaction take place.As optical polymerism functional group, the ethylenic double bonds such as (methyl) acryloyl group, vinyl, allyl can be enumerated such as.It should be noted that, " (methyl) acryloyl group " refers to and comprises both " acryloyl group " and " methacryl ".In addition, the light irradiated when being polymerized as making photopolymerizable compound, can enumerate the ionising radiation ray of visible ray and ultraviolet, X ray, electron ray, alpha ray, β ray and gamma-rays and so on.
As photopolymerizable compound, photopolymerization monomer, optical polymerism oligomer or optical polymerism polymkeric substance can be enumerated, use after suitably adjustment can being carried out to them.As photopolymerizable compound, be preferably the combination of photopolymerization monomer and optical polymerism oligomer or optical polymerism polymkeric substance.
photopolymerization monomer
The weight-average molecular weight of photopolymerization monomer is less than 1000.As photopolymerization monomer, preferably there is the polyfunctional monomer of two (i.e. two senses) above optical polymerism functional groups.In this instructions, " weight-average molecular weight " to be dissolved in tetrahydrofuran (THF) equal solvent by known gel permeation chromatography (GPC) method and the value obtained according to polystyrene conversion.
As monomers more than two senses, such as trimethylolpropane tris (methyl) acrylate can be enumerated, tripropylene glycol two (methyl) acrylate, diethylene glycol two (methyl) acrylate, dipropylene glycol two (methyl) acrylate, pentaerythrite three (methyl) acrylate, pentaerythrite four (methyl) acrylate, dipentaerythritol six (methyl) acrylate, 1,6-hexanediol two (methyl) acrylate, neopentyl glycol two (methyl) acrylate, trimethylolpropane tris (methyl) acrylate, double trimethylolpropane four (methyl) acrylate, dipentaerythritol five (methyl) acrylate, tripentaerythritol eight (methyl) acrylate, tetrapentaerythritol ten (methyl) acrylate, isocyanuric acid three (methyl) acrylate, isocyanuric acid two (methyl) acrylate, polyester three (methyl) acrylate, polyester two (methyl) acrylate, bis-phenol two (methyl) acrylate, two glycerine four (methyl) acrylate, adamantyl two (methyl) acrylate, isobornyl two (methyl) acrylate, bicyclopentane two (methyl) acrylate, tristane two (methyl) acrylate, double trimethylolpropane four (methyl) acrylate and utilize PO, EO etc. carry out the material of modification to above-mentioned example.
From the view point of obtaining the high hard conating of hardness, preferred pentaerythritol triacrylate (PETA), dipentaerythritol acrylate (DPHA), tetramethylol methane tetraacrylate (PETTA), Dipentaerythritol Pentaacrylate (DPPA) etc. among them.
optical polymerism oligomer
The weight-average molecular weight of optical polymerism oligomer is more than 1000 and is less than 10000.As optical polymerism oligomer, the multifunctional oligomer preferably more than two senses.As multifunctional oligomer, polyester (methyl) acrylate, polyurethane (methyl) acrylate, polyester-polyurethane (methyl) acrylate, polyethers (methyl) acrylate, polyvalent alcohol (methyl) acrylate, melamine (methyl) acrylate, isocyanuric acid ester (methyl) acrylate, epoxy (methyl) acrylate etc. can be enumerated.
optical polymerism polymkeric substance
The weight-average molecular weight of optical polymerism polymkeric substance is more than 10000, be preferably more than 10000 as weight-average molecular weight and less than 80000, be more preferably less than more than 10,000 40000.When weight-average molecular weight is more than 80000, because viscosity is high, coating adaptability declines, and the outward appearance of the blooming obtained likely is deteriorated.As above-mentioned multifunctional polymkeric substance, polyurethane (methyl) acrylate, isocyanuric acid ester (methyl) acrylate, polyester-polyurethane (methyl) acrylate, epoxy (methyl) acrylate etc. can be enumerated.
In addition, solvent-dry type resin (as long as the solvent seasoning that thermoplastic resin etc. adjust solid constituent when being coated with by being used for and add can form the resin of overlay film), thermoset resin can also be added as required in hard conating.
When with the addition of solvent-dry type resin, effectively can prevent the overlay film defect of the coated face of coating fluid when forming hard conating.Be not particularly limited as solvent-dry type resin, usually can use thermoplastic resin.As thermoplastic resin, such as phenylethylene resin series, (methyl) acrylic resin, vinyl acetate system resin, vinyl ether system resin, Halogen resin, ester ring type ethylene series resin, polycarbonate-based resin, polyester based resin, polyamide series resin, cellulose derivative, silicon-type resin and rubber or elastic body etc. can be enumerated.
Thermoplastic resin is preferably amorphism and dissolves in organic solvent (especially can dissolve the general solvent of two or more polymkeric substance or curability compound).Especially, from the view point of the transparency, weatherability and so on, optimization styrene system resin, (methyl) acrylic resin, ester ring type ethylene series resin, polyester based resin, cellulose derivative (cellulose esters etc.) etc.
As the thermoset resin that can add in hard conating, be not particularly limited, such as phenolics, Lauxite, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, urethane resin, epoxy resin, amino-alkyd resin, melamine-urea aldehyde condensation copolymerization resin, silicones, polyorganosiloxane resin etc. can be enumerated.
Hard conating can be formed: the composition for hard coat containing above-mentioned photopolymerizable compound is applied to light transmissive film, carry out drying, then to being coated with the light such as membranaceous composition for hard coat irradiation ultraviolet radiation, making photopolymerizable compound be polymerized (being cross-linked), forming hard conating thus.
Except above-mentioned photopolymerizable compound, above-mentioned thermoplastic resin, thermoset resin, solvent, polymerization initiator can also be added as required in composition for hard coat.Further, according to raising hard conating hardness, suppress the object such as cure shrinkage, control refractive index, known spreading agent, surfactant, antistatic agent, silane coupling agent, thickening agent, anti-coloring agent, colorant (pigment, dyestuff), defoamer, levelling agent, fire retardant, ultraviolet light absorber, adhesion promoters, polymerization inhibitor, antioxidant, surface modifier, anticlogging agent etc. can also be added in composition for hard coat.
As the method for coating composition for hard coat, the known coating processes such as spin-coating method, dip coating, spraying process, flow coat method, stick coating method, rolling method, gravure coating process, mould Tu Fa can be enumerated.
Light when solidifying as making composition for hard coat, when using ultraviolet, can utilize the ultraviolet etc. sent by ultrahigh pressure mercury lamp, high-pressure sodium lamp, low pressure mercury lamp, carbon arc lamp, xenon arc lamp, metal halide lamp etc.In addition, as ultraviolet wavelength, the wave band of 190nm ~ 380nm can be used.As the concrete example of electronic radial source, can enumerate croft-Wa Erdun (Cockcroft-Walton) type of examining, Vandegrift (バ Application デ グ ラ Off ト) type, resonance transformer type, insulating core transformer type or linear pattern, various electron ray accelerator such as that rice (Dynamitron) type, high-frequency type etc.
(antiglare layer)
Antiglare layer is the layer playing anti-glare.The surface of antiglare layer forms male and fomale(M&F).By making the surface of antiglare layer form male and fomale(M&F), exterior light generation diffuse reflection can be made.It should be noted that, " surface of antiglare layer " refer to antiglare layer with the face of face (back side) opposite side of light transmissive film side.Antiglare layer can by being formed containing for the formation of the organic fine particles of male and fomale(M&F) or inorganic particles in above-mentioned composition for hard coat.
(antistatic layer)
Antistatic layer is the layer playing antistatic behaviour.Antistatic layer can by being formed containing antistatic agent in above-mentioned composition for hard coat.Known antistatic agent can be used as above-mentioned antistatic agent, particulate or the electroconductive polymer etc. such as the cationic antistatic agent such as such as quaternary ammonium salt, tin-doped indium oxide (ITO) can be used.When using above-mentioned antistatic agent, its content elects 1 quality % ~ 30 quality % as relative to the total Functionality, quality and appealing design of total solid composition.
(stain-proofing layer)
Stain-proofing layer is the layer playing soil resistance, specifically, be the layer bearing following effect: dirt (the ink class, pencil etc. of fingerprint, water-based or oiliness) is even if be difficult to also can easily wipe when the outmost surface of image display device is adhered to or adhered to.In addition, by forming above-mentioned stain-proofing layer, the improvement of soil resistance and mar resistance also can be realized for liquid crystal indicator.Stain-proofing layer such as can utilize the composition containing anti fouling agent and resin to be formed.
The fundamental purpose of above-mentioned anti fouling agent is the pollution preventing image display device outmost surface, also can give mar resistance to liquid crystal indicator.As above-mentioned anti fouling agent, such as fluorine based compound, silicon based compound or their mixing cpd can be enumerated.More particularly, the silane coupling agent etc. that 2-perfluorooctylethyl group triamido silane etc. has fluoro-alkyl can be enumerated, especially preferably can use and there is amino silane coupling agent.
Stain-proofing layer is particularly preferably formed in the mode as outmost surface.Also stain-proofing layer can be replaced by such as giving antifouling property to hard conating self.
Preferably in hard conating, antiglare layer, form low-index layer.
(low-index layer)
Low-index layer is used for reducing its reflectivity when reflection occurs on the surface of polaroid the light (such as fluorescent light, natural light etc.) from outside.Low-index layer has than hard conating, refractive index that antiglare layer is lower.Specifically, such as low-index layer preferably have less than 1.45 refractive index, more preferably have less than 1.42 refractive index.
The thickness of low-index layer is not limited, usually suitably sets in the scope about 30nm ~ 1 μm.The thickness of low-index layer can be obtained by the cross section utilizing transmission electron microscope (TEM, STEM) to observe (multiplying power is preferably more than 10,000 times) low-index layer.Specifically, use the image of transmission electron microscope, in piece image, measure the thickness of the 1st low-index layer at three positions, this measurement is carried out to five width images, calculates the mean value of measured thickness.The thickness d of low-index layer a(nm) following formula (3) is preferably met.
d A＝mλ/(4n Α)…(3)
In above-mentioned formula, n Αrepresent the refractive index of low-index layer, m represents positive odd number, and being preferably 1, λ is wavelength, is preferably more than 480nm and the value of the scope of below 580nm.
From the view point of antiradar reflectivity, low-index layer preferably meets following formula (4).
120<n Ad A<145…(4)
Low-index layer can obtain effect with individual layer, but for adjusting the object of lower minimum reflectivity or higher minimum reflectivity, also suitably can arrange two-layer above low-index layer.When two-layer above low-index layer is set, the refractive index of each low-index layer and thickness is preferably made to there are differences.
As low-index layer, preferably by 1) resin, 2 containing the low-refraction such as silicon dioxide, magnesium fluoride particle) belong to the fluorine resin, 3 of low refractive index resin) fluorine resin, 4 containing silicon dioxide or magnesium fluoride) low-refraction such as silicon dioxide, magnesium fluoride material film etc. in any one form.For the resin beyond fluorine resin, the resin identical with the adhesive resin of above-mentioned formation hard conating can be used.
Silicon dioxide is preferably hollow silica particles, and this hollow silica particles can utilize the manufacture method recorded in the embodiment of such as Japanese Unexamined Patent Publication 2005-099778 publication to make.
< utilizes polaroid to improve daylight contrast >
In present embodiment, polaroid 10 possesses: polarizer 11, and it configures according to the absorption direction of principal axis 11A mode in the horizontal direction of polarizer 11; Light transmissive film 12, its quick shaft direction 12B according to light transmissive film 12 is more than 5 degree relative to the angle [alpha] of the absorption direction of principal axis 11A of polarizer 11 and the mode of less than 40 degree configures.Present inventor has performed confirmation, its result is, by by this polaroid 10 as polaroid, the i.e. so-called upper polarizer of observer side being positioned at display device, can effectively make daylight contrast rise to the degree that visually can perceive improvement degree.Produce the detailed reason of this phenomenon and indefinite, but following content can be considered to one of the main reasons.But the present invention is not by the constraint of following presumption.
First, daylight contrast calculates with the form of { (brightness+external light reflection of white displays)/(brightness+external light reflection of black display) }, and the higher then contrast of the contrast value obtained is more excellent.Therefore, if the reflection of exterior light on the surface of light transmissive film 12 can be reduced, then daylight contrast can be improved.On the other hand, expect that each layer contained in polaroid shows various function, certainly can produce restriction to the setting of the refractive index of the material used in each layer and each layer determined by this material.Therefore, except special circumstances, inevitably refringence can be produced between light transmissive film 12 and functional layer 13.In addition, although also the situation different from illustrated form can be considered, namely layer such as functional layer 13 grade is not set in the observer side of light transmissive film 12, but even in this case, between air and light transmissive film 12, still can produces the refractive index interfaces causing reflection.This refractive index missionary society causes the reflection on the interface of exterior light between light transmissive film 12 and functional layer 13, becomes one of reason of display device daylight contrast decline.
On the other hand, as can incident display device and cause the polarisation of light component of daylight contrast, P polarized light and S polarized light be had.Further, P polarization light reflectance is lower than S polarization light reflectance, and P polarized light exists the Brewster angle that reflectivity is 0%.Therefore, ground or end face reflected and inject in the light of the picture display face of image display device the polarized component (S polarized light) that will inevitably stress containing vibrating in the horizontal direction.For the above reasons, even if depend on that the mean refractive index of material therefor is different between light transmissive film 12 and functional layer 13, as long as refractive index is close to refractive index in the face in the horizontal direction of functional layer 13 in the face in the horizontal direction making light transmissive film 12, the reflection of exterior light between light transmissive film 12 and functional layer 13 that daylight contrast can be caused to decline just effectively can be prevented.
Therefore, in the polaroid 10 of present embodiment, while allowing the mean refraction rate variance between light transmissive film 12 and functional layer 13 that will inevitably be produced by the restriction of Material selec-tion, by using the light transmissive film 12 with birefraction, birefraction is given consciously further to by being usually taken as the light transmissive film 12 that material that optical isotropy treats forms, thus slightly can be reduced in the refringence of the horizontal direction between light transmissive film 12 and functional layer 13, this refringence can arrange the reflectivity of the polarized component vibrated in the horizontal direction.More particularly, the mean refractive index of light transmissive film 12 is usually above the mean refractive index of functional layer 13, thus the quick shaft direction 12B that in the face of light transmissive film 12, in refractive index, refractive index is minimum is made to be more than 5 degree relative to the absorption direction of principal axis 11A of polarizer 11 and in the scope of less than 40 degree, to reduce refringence in the horizontal direction between light transmissive film 12 and functional layer 13.So, be more than 5 degree and the scope of less than 40 degree by making the quick shaft direction 12B of the light transmissive film 12 contained in polaroid 10 relative to the absorption direction of principal axis 11A of polarizer 11, allow and in mean refractive index, produce refringence between light transmissive film 12 and functional layer 13 thus guarantee for the degree of freedom of light transmissive film 12 with the Material selec-tion of functional layer 13, reduce refringence in the horizontal direction on the interface between light transmissive film 12 and functional layer 13 simultaneously, and the reflection on the interface of the polarized component vibrated in the horizontal direction effectively reduced as the main cause causing daylight contrast to decline when visual (not wearing the state of polarized sunglasses) observes this image display device between light transmissive film 12 and functional layer 13.Herein, light transmissive film is configured relative to the mode that the axial angle of the absorption of polarizer is 45 degree compared to according to quick shaft direction, be more than 5 degree according to fast axle 12B relative to the angle of the absorption direction of principal axis 11A of polarizer 11 as in this embodiment and the mode of less than 40 degree configures light transmissive film 12, refringence in the horizontal direction on the interface between light transmissive film 12 and functional layer 13 can be reduced further, thus effectively can be reduced in the polarized component of horizontal direction vibration in light transmissive film 12 and the reflection on the interface of functional layer 13.It should be noted that, when not having functional layer 13, Mght-transmitting base material 12 contacts with air, thus by making the quick shaft direction 12B that in the face of light transmissive film 12, in refractive index, refractive index is minimum be more than 5 degree and the scope of less than 40 degree relative to the absorption direction of principal axis 11A of polarizer 11, the refringence between air can be reduced.Thus, as described above, the reflection of the polarized component vibrated in the horizontal direction as the main cause causing daylight contrast to reduce can effectively be reduced.
In addition, can also reduce polarized component (S polarized light) reflection in light transmissive film 12 vibrated in the horizontal direction that the ratio that is incident to picture display face is more, but result causes the polarized component vibrated in the horizontal direction in a large number through light transmissive film 12.Usually, the polarized component vibrated in the horizontal direction through light transmissive film is absorbed in image display device inside, or becomes parasitic light and return to observer side.The parasitic light returning to observer side produces the Luminance Distribution different from display image, therefore becomes the one of the main reasons that daylight contrast is declined.About this point, in the present embodiment, polarizer 11 configures according to the absorption direction of principal axis 11A mode in the horizontal direction of polarizer 11, and polarizer 11 thus can be utilized to absorb the polarized component vibrated in the horizontal direction through light transmissive film 12.Thus, the light quantity through the polarized component vibrated in the horizontal direction returning to observer side after light transmissive film 12 can be reduced, thus effectively can prevent the generation of parasitic light, daylight contrast when visual (not wearing the state of polarized sunglasses) observes image display device can be improved.
Thus, light transmissive film is configured relative to the mode that the axial angle of the absorption of polarizer is 45 degree compared to according to quick shaft direction, according to the present embodiment, polarized component (S polarized light) reflection on the surface of light transmissive film 12 of horizontal direction vibration can be reduced in, thus configure light transmissive film compared to according to quick shaft direction relative to the mode that the axial angle of the absorption of polarizer is 45 degree, can more effectively improve daylight contrast.Further, can utilize polarizer absorb as through light transmission film the polarized component (S polarized light) vibrated in the horizontal direction and return the parasitic light of observer side, thus can suppress the deterioration of image quality thus realize the further improvement of daylight contrast.
In addition, as shown in Figure 2, the absorption direction of principal axis 11A of polarizer 11 is horizontal direction, thus with the rectilinearly polarized light absorbing the parallel direction of the axis of homology that axle intersects vertically in polarizer 11 through.Polarization state through the rectilinearly polarized light of polarizer 11 changes due to the birefringence of light transmissive film 12, becomes elliptically polarized light, penetrates with the state of this elliptically polarized light from light transmissive film 12.Further, penetrate from polaroid 10 through functional layer 13 under the state keeping this elliptically polarized light.
On the other hand, as mentioned above, observer wears polarized sunglasses with when applicable posture (the absorption direction of principal axis posture roughly in horizontal direction of polarized sunglasses) of observing display image watches the display image of absorption direction of principal axis image display device in horizontal direction of the polarizer of VA pattern or IPS pattern and so on usually, as shown in Figure 2, the absorption direction of principal axis 11A of the absorption direction of principal axis 14A of polarized sunglasses 14 and the polarizer 11 of polaroid 10 is in parallel-nicol state, but observer in the lateral direction inclination neck time and observer when lying down, polarized sunglasses and polaroid can not be parallel-nicol state.Particularly, when observer shows image with the state viewing roughly in vertical direction of the absorption axle of polarized sunglasses, polarized sunglasses and the orthogonal thereto Niccol state of polaroid.
When the absorption axle (direction of vibration of rectilinearly polarized light) of polarizer is 0 with the slow axis angulation of the light transmissive film in face with birefringence, what observe under crossed Nicol is represented by following formula (5) through light intensity.
I=I 0sin z(2 θ) sin 2(π Re/ λ) ... formula (5)
In above-mentioned formula (5), I is intensity, the I of the light through crossed Nicol 0for the wavelength being incident to the intensity of the light of the light transmissive film in face with birefringence, λ is light, Re are the delay of light transmissive film.
When arranging light transmissive film 12, the sin in above-mentioned formula (5) 2(2 θ) is 0, and light is not through polarized sunglasses, therefore visual low.On the other hand, in present embodiment, be provided with light transmissive film 12, the sin thus in above-mentioned formula (5) 2(2 θ) gets the value being greater than 0.Thus, even if polarized sunglasses and the orthogonal thereto Niccol state of polaroid, visuality to a certain degree can also be guaranteed.
Further, when polarized sunglasses and polaroid are parallel-nicol state, for the situation being configured in face λ/4 phase retardation film with birefringence according to quick shaft direction relative to the mode that the axial angle of the absorption of polarizer is 45 degree, with be more than 5 degree according to quick shaft direction relative to the axial angle of the absorption of polarizer and the mode of less than 40 degree is configured in face the situation of the light transmissive film with birefringence, two kinds of situations are compared, compared to the situation configuring λ/4 phase retardation film according to quick shaft direction relative to the mode that the axial angle of the absorption of polarizer is 45 degree, when being more than 5 degree according to quick shaft direction relative to the axial angle of the absorption of polarizer and the mode of less than 40 degree is configured in face the light transmissive film with birefringence, transmitance is higher.This is due to following reason.When configuring λ/4 phase retardation film according to fast axle relative to the mode that the axial angle of the absorption of polarizer is 45 degree, become circularly polarized light by the polarization state of the rectilinearly polarized light of the axis of homology of polarizer.The state of this circularly polarized light refers to the state identical with following state: namely can by the rectilinearly polarized light of the axis of homology of polarizer and state just in time each half of the rectilinearly polarized light vibrated in the direction vertical with this linear polarization optical vibration direction (rectilinearly polarized light that the absorption axle being polarized element absorbs).Therefore, even if do not reflecting or absorbing ideally, when the absorption axle of polarized sunglasses and the absorption axle of polaroid are parallel-nicol state, transmitance reduces by half.In contrast to this, be more than 5 degree according to fast axle relative to the axial angle of the absorption of polarizer and the mode of less than 40 degree is configured in face the light transmissive film with birefringence time, the polarization state through the rectilinearly polarized light of the axis of homology of polarizer becomes elliptically polarized light.The state of this elliptically polarized light refers to the state identical with following state: namely existing compared to the rectilinearly polarized light vibrated in the direction vertical with the direction of vibration of this rectilinearly polarized light (rectilinearly polarized light that the absorption axle being polarized element absorbs) component more can through the linear polarization component of the axis of homology of polarizer.Therefore, when the absorption axle of polarized sunglasses and the absorption axle of polaroid are the state of parallel-nicol, transmitance can not be reduced to below half, and transmitance is higher than the situation configuring λ/4 phase retardation film according to quick shaft direction relative to the mode that the axial angle of the absorption of polarizer is 45 degree.In present embodiment, light transmissive film 12 is more than 5 degree according to quick shaft direction 12B relative to the angle of the absorption direction of principal axis 11A of polarizer 11 and the mode of less than 40 degree configures, and thus transmitance is higher than the situation configuring λ/4 phase retardation film according to quick shaft direction relative to the mode that the axial angle of the absorption of polarizer is 45 degree.
" ameliorative way of the daylight contrast of image display device and image display device "
Polaroid 10 can be assembled in image display device and use.As image display device, such as liquid crystal display (LCD), leonard's tube display device (CRT), plasma scope (PDP), electroluminescent display (ELD), Field Emission Display (FED), contact panel, dull and stereotyped PC, Electronic Paper etc. can be enumerated.Fig. 3 is the schematic pie graph of the liquid crystal display of an example as the image display device being provided with blooming of the present embodiment.
Image display device 20 is as shown in Figure 3 liquid crystal display.Image display device 20 is made up of the liquid crystal panel 40 possessing polaroid 10 of back light unit 30 with the observer side being configured in back light unit 30.
Back light unit 30 preferably possesses white light-emitting diode (White LED) as backlight.Above-mentioned White LED refers to fluorophor mode, namely by will the transmitting blue light of compound semiconductor or the light emitting diode of ultraviolet light and fluorophor be used to combine the element carrying out transmitting white.Wherein, white light-emitting diode containing the light-emitting component by using the blue LED of compound semiconductor and the yellow fluorophor combination of yttrium aluminum garnet system is owing to having continuously and the luminescent spectrum of wide cut, to improving, daylight contrast is effective, and luminescence efficiency is also excellent, be therefore suitable as the above-mentioned backlight in the present invention.In addition, the little White LED of power consumption can extensively be utilized, and thus also can play the effect of energy-saving.
Liquid crystal panel 40 as shown in Figure 3 has following structure: from back light unit 30 side, be laminated with tri acetyl cellulose membrane (TAC film) etc. towards observer side successively diaphragm 41, polarizer 42, phase retardation film 43, cement layers 44, liquid crystal cell 45, cement layers 46, phase retardation film 47, polaroid 10.In liquid crystal cell 45, between two pieces of glass baseplates, be configured with liquid crystal layer, alignment films, electrode layer, color filter etc.
Polaroid 10 is configured in image display device 20 according to the absorption direction of principal axis 11A mode in the horizontal direction of polarizer 11.It should be noted that, the light transmissive film 12 of polaroid 10 is more than 5 degree according to the quick shaft direction 12B of light transmissive film 12 relative to the angle [alpha] of the absorption axle of polarizer 11 and the mode of less than 40 degree is configured, and this is from need not.
Image display device 20 is preferably the liquid crystal indicator of VA pattern or IPS pattern.Above-mentioned VA (VerticalAlignment) pattern refers to, when not applying voltage, liquid crystal molecule is orientated according to the mode vertical with the substrate of liquid crystal cell and demonstrates and show slinkingly picture, by liquid crystal molecule being poured into the pattern demonstrating bright video picture under applying voltage.In addition, above-mentioned IP S (In-Plane Switching) pattern refers to, the comb poles to the side substrate being arranged at liquid crystal cell applies transverse electric field, utilizes this transverse electric field to make liquid crystal carry out rotating in real estate thus carries out the mode that shows.
Image display device is preferably VA pattern or IPS pattern, this is because the absorption axle of the polarizer arranged in the observer side of liquid crystal cell in VA pattern or IPS pattern in the horizontal direction.
Image display device also can be the display of organic electroluminescence (OLED display) that polarizer absorbs that axle is set to horizontal direction.Now, also can from observer side the above-mentioned polaroid of lamination, λ/4 polarizer, organic EL successively.As the image display pattern of OLED display, can enumerate and use white light-emitting layer and the color filter mode obtaining colored display through color filter; Use blue light-emitting layer and make a part for its luminescence obtain the look conversion regime of colored display thus through color converting layer; Use three look modes of the luminescent layer of red-green-blue; The mode of color filter is share in this three looks mode; Etc..As the material of luminescent layer, both can be low molecule, also can be macromolecule.
[embodiment]
In order to describe the present invention in detail, enumerating embodiment below and being described, but the invention is not restricted to these records.
< daylight contrast >
, each polaroid obtained is carried out to the evaluation of daylight contrast in embodiment and comparative example below, the evaluation of daylight contrast is carried out in the following manner.Replace the polaroid arranged in the observer side of liquid crystal display (FLATORON IPS226V (manufacture of LG ElectronicsJapan company)), be horizontal direction by the polaroid of embodiment and comparative example according to making the absorption direction of principal axis of polarizer, and make the TD80UL-M side described later of polaroid be that the mode of liquid crystal panel side is through pressure-sensitive cement (P-3132, Lintec company manufactures) arrange, be under the condition of 400 luxs (daylight) in ambient light illumination, 15 testees carry out image viewing by visual (not wearing the state of polarized sunglasses) to this black display from the position of liquid crystal display 50cm ~ about the 60cm apart from black display, evaluate according to following standard.In evaluation, the polaroid using same material to be formed for every block is evaluated, and the quick shaft direction of light transmissive film is arranged to the polaroid of 45 degree as reference relative to the axial angle of the absorption of polarizer.
A: seem more black than reference, daylight contrast is very excellent.
B: seem more black than reference, daylight contrast is excellent.
C: only slightly more black than reference, but daylight contrast is excellent.
D: the equal or daylight poor contrast with reference.
Daylight contrast: CR=LW/LB
Daylight white luminance (LW): make in the daylight (ambient light illumination 400 lux) that there is exterior light display device carry out white display time brightness
Daylight black luminance (LB): make in the daylight (ambient light illumination 400 lux) that there is exterior light display device carry out black display time brightness
< reflectivity >
, each polaroid obtained is carried out to the mensuration of reflectivity in embodiment and comparative example below, the mensuration of reflectivity is carried out in the following manner.Behind opposition side laminating black pvc adhesive tape (Yamatovinyl tape N Ο 200-38-2138mm is wide) of the light transmissive film side of polaroid, use spectrophotometer (V7100 type, automatically light splitting society of absolute reflectance determination unit VAR-7010 Japan manufacture), for S polarized light, measure 5 degree of corner reflection rates when being be arranged in parallel by the absorption axle of polarizer.
< Visualization Evaluation >
, carry out visual evaluation for each polaroid obtained in embodiment and comparative example below, visual evaluation is carried out in the following manner.Replace the polaroid in the setting of the observer side of liquid crystal display (FLATORON IPS226V (manufactures of LG Electronics Japan company)), the polaroid of embodiment and comparative example is horizontal direction according to the absorption direction of principal axis of polarizer and the mode that the TD80UL-M side described later of polaroid is liquid crystal panel side is arranged through pressure-sensitive cement (manufacture of P-3132, Lintec company).In darkroom, liquid crystal indicator is made to be white display, and according to making the absorption axle angulation of the absorption axle of polarized sunglasses and polarizer be rotated by 0 ° (parallel-nicol) mode to 90 ° (crossed Nicol), evaluate according to following standard.
A: no matter all can identify display image (can corresponding polarized sunglasses) in any angle.
B: along with the difference of angle, visuality declines slightly, but still be unchallenged level in actual use.
C: along with the difference of angle, visual decline, but display image can be identified.
, there is the angle (cannot corresponding polarized sunglasses) of None-identified display image in D: along with the difference of angle.
The transmittance > of < parallel-nicol state
Below, for each polaroid obtained in embodiment and comparative example, measure the transmittance of parallel-nicol state in the following manner.Replace the polaroid arranged in the observer side of liquid crystal display (FLATORON IPS226V (manufacture of LG Electronics Japan company)), be horizontal direction by the polaroid of embodiment and comparative example according to the absorption direction of principal axis of polarizer, and the TD80UL-M side described later of polaroid is that the mode of liquid crystal panel side is through pressure-sensitive cement (P-3132, Lintec company manufactures) arrange, white display is carried out in darkroom, front face brightness when utilizing nitometer BM-5A (manufacture of Topcon company) the mensuration absorption axle of polarized sunglasses and the absorption axle angulation of polarizer to be 0 ° (parallel-nicol).For transmitance, be considered as 100% with the transmitance of polaroid TD80UL-M described later being arranged on polarizer two sides.
< comprehensive evaluation >
Comprehensive evaluation is carried out according to following standard.
◎: for more than B evaluation in contrast evaluation in the open, Visualization Evaluation.
Zero: for more than C evaluation in contrast evaluation in the open, Visualization Evaluation.
×: there is D in contrast evaluation in the open, Visualization Evaluation and evaluate.
< embodiment 1>
(making of light transmissive film)
By pet material 290 DEG C of meltings, extruded with sheet by film die, be close to and cool on the rotation quenching rotary drum of cooling by water, make and obtain unstretching film.Utilize bidirectional tensile tester (Toyo Seiki manufacture), by this unstretching film 120 DEG C of preheatings 1 minute, then carry out 4.0 times of stiff end unilateral stretchings at 120 DEG C, make and obtain the light transmissive film in face with birefringence.This light transmissive film is at the refractive index n at wavelength 550nm place x=1.701, n y=l.6015, Δ n=0.0995.The thickness of this light transmissive film is 75 μm, Re=7500nm.
(making of polaroid)
Average degree of polymerization is about 2400, saponification degree is more than 99.9 % by mole and the polyvinyl alcohol film that thickness is 75 μm is immersed in the pure water of 30 DEG C, the weight ratio that then impregnated in iodine/potassium iodide/water at 30 DEG C is the aqueous solution of 0.02/2/100.Afterwards, the weight ratio that impregnated in potassium iodide/boric acid/water at 56.5 DEG C is the aqueous solution of 12/5/100.Then clean with the pure water of 8 DEG C, then carry out drying at 65 DEG C, obtain the polarizer that gas absorption quantity in polyvinyl alcohol (PVA) has iodine.Stretch and mainly carry out in iodine staining and the acid-treated operation of boron, total stretching ratio is 5.3 times.
By the solvent-free active energy ray curable cement containing cycloaliphatic epoxy, the mode being 5 degree according to the absorption axle of polarizer and the fast axle angulation of light transmissive film carries out bonding laminating in the side in a face of obtained polarizer.Then, by the solvent-free active energy ray curable cement containing cycloaliphatic epoxy, polarizer with the TD80UL-M (Fuji Photo Film Co., Ltd. manufacture) of the bonding laminating in face as isotropic membrane being laminated with light transmissive film side opposite side, make and obtain the polaroid of embodiment 1.
< embodiment 2>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 10 degree, in addition, has made the polaroid of embodiment 2 according to method similarly to Example 1.
< embodiment 3>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 15 degree, in addition, has made the polaroid of embodiment 3 according to method similarly to Example 1.
< embodiment 4>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 30 degree, in addition, has made the polaroid of embodiment 4 according to method similarly to Example 1.
< embodiment 5>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 35 degree, in addition, has made the polaroid of embodiment 5 according to method similarly to Example 1.
< embodiment 6>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 40 degree, in addition, has made the polaroid of embodiment 6 according to method similarly to Example 1.
< comparative example 1>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 0 degree, in addition, has made the polaroid of comparative example 1 according to method similarly to Example 1.
< comparative example 2>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 45 degree, in addition, has made the polaroid of comparative example 2 according to method similarly to Example 1.
< comparative example 3>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 60 degree, in addition, has made the polaroid of comparative example 3 according to method similarly to Example 1.
< comparative example 4>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 75 degree, in addition, has made the polaroid of comparative example 4 according to method similarly to Example 1.
< comparative example 5>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 90 degree, in addition, has made the polaroid of comparative example 5 according to method similarly to Example 1.
< embodiment 7>
Pentaerythritol triacrylate (PETA) is dissolved in methyl isobutyl ketone (Μ BK) solvent according to 30 quality %, the Photoepolymerizationinitiater initiater (IRGACURE 184, BASF AG manufacture) that further interpolation is 5 quality % relative to solid constituent obtains composition for hard coat, utilize bar coater to be coated with according to the mode that dried thickness is 5 μm by this composition for hard coat, thus the light transmissive film made in embodiment 1 forms film.Then, by formed film 70 DEG C of heating 1 minute, except desolventizing, to coated face irradiation ultraviolet radiation, being thus fixed, obtaining and there is the light transmissive film that refractive index is the band hard conating of the hard conating of 1.53.
According to the mode that absorption axle and the fast axle angulation of light transmissive film of band hard conating of polarizer are 15 degree, light transmissive film with bonding laminating polarizer on the face of the face opposite side of hard conating side, in addition, the polaroid of embodiment 7 has been made according to method similarly to Example 1.
< embodiment 8>
Make the absorption axle of polarizer be 30 degree with the fast axle angulation of the light transmissive film of band hard conating, in addition, make the polaroid of embodiment 8 according to method similarly to Example 7.
< comparative example 6>
Make the absorption axle of polarizer be 0 degree with the fast axle angulation of the light transmissive film of band hard conating, in addition, make the polaroid of comparative example 6 according to method similarly to Example 7.
< comparative example 7>
Make the absorption axle of polarizer be 45 degree with the fast axle angulation of the light transmissive film of band hard conating, in addition, make the polaroid of comparative example 7 according to method similarly to Example 7.
< comparative example 8>
Make the absorption axle of polarizer be 60 degree with the fast axle angulation of the light transmissive film of band hard conating, in addition, make the polaroid of comparative example 8 according to method similarly to Example 7.
< comparative example 9>
Make the absorption axle of polarizer be 90 degree with the fast axle angulation of the light transmissive film of band hard conating, in addition, make the polaroid of comparative example 9 according to method similarly to Example 7.
< embodiment 9>
The thickness of adjustment unstretching film, carries out 3.0 times of stiff end unilateral stretchings at 120 DEG C, in addition, has made the light transmissive film in face with birefringence according to method similarly to Example 1.This light transmissive film is at the refractive index n at wavelength 550nm place x=1.6922, n y=l.613, Δ n=0.0799.The thickness of this light transmissive film is 36 μm, Re=2900nm.
Use this light transmissive film, the fast axle angulation making the absorption axle of polarizer and light transmissive film is 15 degree, in addition, has made the polaroid of embodiment 9 according to method similarly to Example 1.
< embodiment 10>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 30 degree, in addition, has made the polaroid of embodiment 10 according to method similarly to Example 9.
< comparative example 10>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 0 degree, in addition, has made the polaroid of comparative example 10 according to method similarly to Example 9.
< comparative example 11>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 45 degree, in addition, has made the polaroid of comparative example 11 according to method similarly to Example 9.
< comparative example 12>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 60 degree, in addition, has made the polaroid of comparative example 12 according to method similarly to Example 9.
< comparative example 13>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 90 degree, in addition, has made the polaroid of comparative example 13 according to method similarly to Example 9.
< embodiment 11>
After to take methylene chloride as solvent be the mode dissolving cellulos acetate propionate (CAP504-0.2 that Eastman Chemical company manufactures) of 15% according to solid component concentration, be cast on glass, carry out drying, obtain unstretching film.Utilize bidirectional tensile tester (Toyo Seiki manufacture), at 160 DEG C, 1.5 times of free end unilateral stretchings are carried out to this unstretching film, make and obtain the light transmissive film in face with birefringence.This light transmissive film is at the refractive index n at wavelength 550nm place x=l.4845, n y=l.4835, Δ n=0.001.The thickness of this light transmissive film is 138 μm, Re=138nm.
Use light transmissive film, the fast axle angulation making the absorption axle of polarizer and light transmissive film is 15 degree, in addition, has made the polaroid of embodiment 11 according to method similarly to Example 1.
< embodiment 12>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 30 degree, in addition, has made the polaroid of embodiment 12 according to method similarly to Example 11.
< comparative example 14>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 0 degree, in addition, has made the polaroid of comparative example 14 according to method similarly to Example 11.
< comparative example 15>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 45 degree, in addition, has made the polaroid of comparative example 15 according to method similarly to Example 11.
< comparative example 16>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 60 degree, in addition, has made the polaroid of comparative example 16 according to method similarly to Example 11.
< comparative example 17>
The fast axle angulation making the absorption axle of polarizer and light transmissive film is 90 degree, in addition, has made the polaroid of comparative example 17 according to method similarly to Example 11.
Below, table 1 is shown the result in.
As shown in table 1, in comparative example 1, although daylight contrast is more excellent than the comparative example 2 as reference, and the transmittance under parallel-nicol state is higher than comparative example 2, fails to guarantee visuality.In addition, in comparative example 3 and 4, although the transmittance under parallel-nicol state is higher than comparative example 2, and also ensure that visuality to a certain degree, daylight contrast and comparative example 2 are equal or lower than comparative example 2.In comparative example 5, although the transmittance under parallel-nicol state is higher than comparative example 2, daylight contrast and comparative example 2 are equal or lower than comparative example 2, and fail to guarantee visuality.On the other hand, in embodiment 1 ~ 6, daylight contrast is better than the comparative example 2 as reference, and the transmittance under parallel-nicol state is also higher than comparative example 2.In addition, also ensure that to a certain degree above visuality.
In addition, as shown in table 1, in comparative example 6, although daylight contrast is better than the comparative example 7 as reference, and the transmittance under parallel-nicol state is higher than comparative example 7, fails to guarantee visuality.In addition, in comparative example 8, although the transmittance under parallel-nicol state is higher than comparative example 7, and also ensure that visuality to a certain degree, daylight contrast and comparative example 7 are equal or lower than comparative example 7.In comparative example 9, although the transmittance under parallel-nicol state is higher than comparative example 7, daylight contrast and comparative example 7 are equal or lower than comparative example 7, and also fail to guarantee visuality.On the other hand, in embodiment 7 and 8, daylight contrast is better than the comparative example 7 as reference, and the transmittance under parallel-nicol state is higher than comparative example 7.In addition, also ensure that to a certain degree above visuality.
In addition, as shown in table 1, in comparative example 10, although daylight contrast is better than the comparative example 11 as reference, and the transmittance under parallel-nicol state is higher than comparative example 11, fails to guarantee visuality.In addition, in comparative example 12, although the transmittance under parallel-nicol state is higher than comparative example 11, and also ensure that visuality to a certain degree, daylight contrast and comparative example 11 are equal or lower than comparative example 11.In comparative example 13, although the transmittance under parallel-nicol state is higher than comparative example 11, daylight contrast and comparative example 11 are equal or lower than comparative example 11, and fail to guarantee visuality.On the other hand, in embodiment 9 and 10, daylight contrast is better than the comparative example 11 as reference, and the transmittance under parallel-nicol state is higher than comparative example 11.In addition, also ensure that to a certain degree above visuality.
Further, as shown in table 1, in comparative example 14, although daylight contrast is better than the comparative example 15 as reference, and the transmittance under parallel-nicol state is higher than comparative example 11, fails to guarantee visuality.In addition, in comparative example 16, although the transmittance under parallel-nicol state is higher than comparative example 15, and also ensure that visuality to a certain degree, daylight contrast and comparative example 15 are equal or lower than comparative example 15.In comparative example 17, although the transmittance under parallel-nicol state is higher than comparative example 15, daylight contrast and comparative example 15 are equal or lower than comparative example 15, and fail to guarantee visuality.On the other hand, in embodiment 11 and 12, daylight contrast is better than the comparative example 15 as reference, and the transmittance under parallel-nicol state is also higher than comparative example 15.In addition, also ensure that to a certain degree above visuality.
It should be noted that, in the above-described embodiments, be the mode of positive dirction according to the fast axle in light transmissive film relative to the angle of the absorption axle of polarizer, namely the left side observing the fast axle of light transmissive film during polaroid from front configures relative to the mode that the absorption axle of polarizer is upside, but for being the mode of negative direction according to the fast axle in light transmissive film relative to the angle of the absorption axle of polarizer, namely the polaroid that the left side observing the fast axle of light transmissive film during polaroid from front configures relative to the mode that the absorption axle of polarizer is downside, carry out evaluation similar to the above and mensuration, have also been obtained the result same with above-described embodiment.
Symbol description
10 ... polaroid
11 ... polarizer
11A ... absorb direction of principal axis
12 ... light transmissive film
12A ... slow-axis direction
12B ... quick shaft direction
13 ... functional layer
14 ... polarized sunglasses
14A ... absorb direction of principal axis
20 ... image display device

Claims (9)

1. a polaroid, it is the polaroid of the light transmissive film in the face of the observer side possessing polarizer and be arranged at described polarizer, and this light transmissive film has birefringence in face, and the feature of described polaroid is,
Described polarizer is configured according to the light absorption direction of principal axis mode in the horizontal direction of described polarizer,
Using direction maximum for the refractive index in the face of described light transmissive film as slow-axis direction, using the direction intersected vertically with described slow-axis direction in described as quick shaft direction time, described light transmissive film is more than 5 degree according to described quick shaft direction relative to the axial angle of described absorption and the mode of less than 40 degree is configured.
2. polaroid as claimed in claim 1, wherein, described light transmissive film is polyester film.
3. polaroid as claimed in claim 1, wherein, described polaroid has functional layer further, this functional layer be formed in described light transmissive film with the face of opposition side, face being formed with described polarizer, further, the refractive index in the direction parallel with the quick shaft direction of described light transmissive film of this functional layer is lower than the refractive index of the quick shaft direction of described light transmissive film.
4. polaroid as claimed in claim 3, wherein, described functional layer is hard conating or antiglare layer.
5. an image display device, it possesses polaroid according to claim 1, and described polaroid is configured according to the absorption direction of principal axis mode in the horizontal direction of described polarizer.
6. image display device as claimed in claim 5, wherein, described image display device is the liquid crystal indicator of VA pattern or IPS pattern.
7. image display device as claimed in claim 5, it possesses light emitting diode as light source.
8. image display device as claimed in claim 5, wherein, described image display device is display of organic electroluminescence, in this display of organic electroluminescence, possess λ/4 phase difference film further, and described polaroid is configured according to than the mode of described λ/4 phase difference film closer to observer side.
9. an ameliorative way for the daylight contrast of image display device, is characterized in that, polaroid according to claim 1 is configured at image display device according to the absorption direction of principal axis mode in the horizontal direction of the described polarizer in described polaroid.
CN201410498557.2A 2013-09-26 2014-09-25 Polarizing plate, image display device, and improvement method of photopic contrast in image display device Pending CN104516043A (en)

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