CN102736144A - Light diffusion sheet, optical unit, backlight unit and liquid crystal display device - Google Patents
Light diffusion sheet, optical unit, backlight unit and liquid crystal display device Download PDFInfo
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- CN102736144A CN102736144A CN2012101055341A CN201210105534A CN102736144A CN 102736144 A CN102736144 A CN 102736144A CN 2012101055341 A CN2012101055341 A CN 2012101055341A CN 201210105534 A CN201210105534 A CN 201210105534A CN 102736144 A CN102736144 A CN 102736144A
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/02—Diffusing elements; Afocal elements
- G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
- G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
- G02B5/0226—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures having particles on the surface
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/04—Prisms
- G02B5/045—Prism arrays
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members
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- Organic Chemistry (AREA)
- Optical Elements Other Than Lenses (AREA)
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Abstract
The invention provides a light diffusion sheet which further achieves the high brightness and thinness of a liquid crystal display device, an optical unit having the light diffusion sheet, a backlight unit and a liquid crystal display device. The light diffusion sheet comprises a transparent base material layer and a light diffusion layer which is laminated on the surface of the base material layer. A binder contains resin beads which use beads with high refractive index. The refractive index of the binder ranges from 1.49 to 1.51, and the refractive index of the resin beads ranges from 1.52 to 1.59. A value generated by subtracting the refractive index of the binder from the refractive index of the resin beads can range from 0.06 to 0.08. The main polymer of the resin beads can be a copolymer of (methyl) acrylic monomer and styrene monomer.
Description
Technical field
The present invention relates to light diffusing sheet, comprise the optical unit of light diffusing sheet, the liquid crystal indicator that comprises the back light unit of optical unit and comprise back light unit.
Background technology
Characteristics such as that liquid crystal indicator effectively utilizes is slim, light weight and low power consumption, and be widely used as flat-panel monitor, and its purposes enlarges year by year are for example as the display device of mobile phone, portable information terminal device, personal computer and televisor etc.In recent years, the needed characteristic of liquid crystal indicator can be enumerated high briliancyization, wide viewing angleization, energy-conservationization and slim lightweight etc., particularly having relatively high expectations to high briliancyization.
Common in the past liquid crystal indicator has liquid crystal display cells and back light unit, and this back light unit is configured in the rear side (for example with reference to patent documentation 1: Jap.P. open communique spy open 2005-106959 number) of liquid crystal display cells.Liquid crystal display cells has liquid crystal cells is clamped in the structure between face side Polarizer and the rear side Polarizer, and with various display mode driving liquid crystal elements.Back light unit is from rear side irradiating liquid crystal display element, and what extensively popularize is the back light unit of edge-light type and full run-down type.These back light units in the past have: light source; LGP will be from light guiding liquid crystal display cells one side of light source; And optical unit, be configured on the surface of liquid crystal display cells one side of LGP.Optical unit is used for making the whole surface of injecting the liquid crystal display cells rear side from the light of LGP effectively and equably, for example comprises: light diffusing sheet makes the light diffusion from LGP; And prismatic lens, transmitted ray is reflected to the normal direction side.
Though liquid crystal indicator in the past so realized high briliancyization to a certain degree, further requires the high briliancyization of liquid crystal indicator owing to have aforesaid light diffusing sheet and prismatic lens etc. now.Based on the purposes such as briliancy that improve liquid crystal indicator, developed the high-gain prismatic lens.For example, the name of product of (strain) Sumitomo 3M corporate system is the high-gain prismatic lens commercialization of " BEF2-G2-MR-155 ".Above-mentioned high-gain prismatic lens is the prismatic lens that high-index material constitutes.Though the light diffusing sheet that cooperates with the high-gain prismatic lens is not developed in the commercialization of high-gain prismatic lens, do not given play to the effect of the raising briliancy that produces by the high-gain prismatic lens yet.In addition, also further require the liquid crystal indicator slimming now.
Summary of the invention
The object of the present invention is to provide the high briliancyization that is used for further realizing liquid crystal indicator and slimming light diffusing sheet, comprise the optical unit of this light diffusing sheet, the liquid crystal indicator that comprises the back light unit of this optical unit and further realized high briliancyization and slimming.
The present invention provides a kind of light diffusing sheet, and it comprises: transparent base material layer; And light diffusion layer, being laminated in the surface of said base material layer, and in cementing agent, having resin bead, said light diffusing sheet is characterised in that the refractive index of said resin bead is more than 1.50.
Because the refractive index of the resin bead of this light diffusing sheet is greater than the refractive index of the resin bead of light diffusing sheet in the past, so the reflection and the ratio of refraction of the light that is produced by resin bead were big in the past.Therefore, if this light diffusing sheet is assembled on the liquid crystal indicator, then with compared the briliancy that can improve liquid crystal indicator in the past.Its result can make the back light unit slimming, and then can realize the slimming of liquid crystal indicator.In addition, the cementing agent through adjusting this light diffusing sheet respectively and the refractive index of resin bead no matter have the high-gain prismatic lens of which type of refractive index, can realize utilizing the high-gain prismatic lens to make light upright towards vertical direction.
The refractive index of above-mentioned cementing agent can be more than 1.49 and below 1.51, and the refractive index of above-mentioned resin bead can be more than 1.52 and below 1.59.In this case, because the refractive index of the resin bead of this light diffusing sheet is greater than the refractive index of the resin bead of light diffusing sheet in the past,, thereby improved the briliancy of liquid crystal indicator so the reflection and the ratio of refraction of the light that is produced by resin bead were big in the past.
In this light diffusing sheet, the value that deducts from the refractive index of resin bead after the refractive index of cementing agent can be more than 0.06 and below 0.08.In this case, the reflection and the refraction of the light that is produced by resin bead further become big, thereby have further improved the briliancy of liquid crystal indicator.
The main polymer of above-mentioned resin bead can be the multipolymer of (methyl) acrylic monomer and styrene monomer.In this case, the refractive index that can easily make resin bead is more than 1.52 and below 1.59, or makes from the refractive index of resin bead and deduct value after the refractive index of cementing agent more than 0.06 and below 0.08.
Above-mentioned resin bead can be more than 40 mass parts and below 230 mass parts with respect to the amount of allocating into of 100 mass parts cementing agents.In this case, the reflection and the refraction of the light that is produced by resin bead further become big, thereby have further improved the briliancy of liquid crystal indicator.
The haze value of this light diffusing sheet can be more than 78% and below 93%.In this case, the reflection and the refraction of the light that is produced by resin bead further become big, thereby have further improved the briliancy of liquid crystal indicator.
The mean particle diameter of above-mentioned resin bead can be more than the 2 μ m and below 5 μ m.In this case, the reflection and the refraction of the light that is produced by resin bead further become big, thereby have further improved the briliancy of liquid crystal indicator.
Above-mentioned resin bead can be the pearl of polydispersity.In this case, the reflection and the refraction of the light that is produced by resin bead further become big, thereby have further improved the briliancy of liquid crystal indicator.
In order further to realize the high briliancyization and the slimming of liquid crystal indicator, can be with the textural element of following optical unit as liquid crystal indicator, that is, this optical unit comprises: above-mentioned light diffusing sheet; And a prismatic lens, being laminated in the face side of above-mentioned light diffusing sheet, the refractive index of above-mentioned prismatic lens is more than 1.50.Equally, in order further to realize the high briliancyization and the slimming of liquid crystal indicator, can be with the textural element of following optical unit as liquid crystal indicator, that is, this optical unit comprises: above-mentioned light diffusing sheet; And two prismatic lenses, being laminated in the face side of above-mentioned light diffusing sheet, two above-mentioned prismatic lenses are configured to crest line and intersect each other, and the refractive index of two above-mentioned prismatic lenses is more than 1.50.In this case, if the refractive index of each prismatic lens more than 1.55 and below 1.70, then can further improve the briliancy of liquid crystal indicator.In addition, can realize the slimming of liquid crystal indicator.
In addition, in order further to realize the high briliancyization and the slimming of liquid crystal indicator, can be with the textural element of following back light unit as liquid crystal indicator, that is, this back light unit comprises: light source; LGP, incident have the light from this light source, and the light of incident is penetrated; And above-mentioned optical unit, be laminated in the upside of above-mentioned LGP.
In addition, the present invention also provides a kind of liquid crystal indicator, and this liquid crystal indicator comprises: above-mentioned back light unit; And liquid crystal display cells, be configured in the top of the prismatic lens of above-mentioned back light unit.
The present invention can be provided for further realizing the high briliancyization of liquid crystal indicator and slimming light diffusing sheet, comprise the optical unit of this light diffusing sheet, the liquid crystal indicator that comprises the back light unit of this optical unit and further realized high briliancyization and slimming.
Description of drawings
Fig. 1 schematically shows the figure of the liquid crystal indicator section of embodiment of the present invention.
Fig. 2 is used for the figure that the light of the liquid crystal indicator of key diagram 1 advances.Description of reference numerals
1 liquid crystal indicator
10 liquid crystal display cells
11 face side Polarizers
12 liquid crystal cells
13 rear side reflection Polarizer
20 back light units
21 light sources
22 LGPs
23 optical units
31 light diffusing sheets
32 first prismatic lenses
33 second prismatic lenses
41 base material layers
42 light diffusion layers
43 adhesions prevent layer
51 resin bead
52 cementing agents
Embodiment
With reference to the accompanying drawings, embodiment of the present invention is described.
(structure of liquid crystal indicator)
The liquid crystal indicator 1 of Fig. 1 has liquid crystal display cells 10 and back light unit 20.Liquid crystal display cells 10 utilizes light to come display message, and has liquid crystal cells 12 is clamped in the structure between face side Polarizer 11 and the rear side reflection Polarizer 13.Rear side reflection Polarizer 13 makes the polarized light component transmission of a direction of light, and reflects remaining polarized light component.
First prismatic lens 32 is high-gain prismatic lenses, makes from the light refraction of light diffusing sheet 31 incidents and to second prismatic lens 33 to penetrate.Second prismatic lens 33 is high-gain prismatic lenses, so that the mode that the light that penetrates vertically advances with respect to liquid crystal display cells 10 back sides substantially makes from the light refraction of first prismatic lens, 32 incidents and to liquid crystal display cells 10 and penetrates.First prismatic lens 32 and second prismatic lens 33 comprise: base material layer; And projection row, constitute by a plurality of prominent bar prism portion that is layered in this matrix material laminar surface.
The thickness of first prismatic lens 32 and second prismatic lens 33 (from the back side to the height on the summit of prominent bar prism portion) is preferably more than the 50 μ m and below 200 μ m, more preferably more than the 100 μ m and below 180 μ m.In addition, the interval (pitch) between the prominent bar prism portion in first prismatic lens 32 and second prismatic lens 33 is preferably more than the 30 μ m and below 100 μ m, more preferably more than the 40 μ m and below 60 μ m.In addition, the drift angle of prominent bar prism portion is preferably more than 85 ° and below 95 °.The refractive index of first prismatic lens 32 and second prismatic lens 33 is more than 1.50, preferably more than 1.55 and below 1.70.In addition, the refractive index of prismatic lens is meant the refractive index of prism portion.Through prismatic lens 32,33 and this light diffusing sheet 31 of this structure of combination use, can further realize high briliancyization.In addition, first prismatic lens 32 and second prismatic lens 33 all overleaf side make from the face side refraction of the light that becomes 33～34 ° of left and right sides angle directions with substrate normal to normal.Prismatic lens in the past makes from the face side refraction of the light that becomes 30～31 ° of left and right sides angle directions with substrate normal to normal.That is, about making the vertically upright function of light with respect to the back side oblique incidence of substrate, first prismatic lens 32 and second prismatic lens 33 have higher ability than prismatic lens in the past.First prismatic lens 32 and second prismatic lens 33 for example are respectively the high-gain prismatic lens of the name of product of (strain) Sumitomo 3M corporate system for " BEF2-G2-MR-155 ".
(structure of light diffusing sheet)
Light diffusion layer 42 comprises: the resin bead 51 with high index of refraction; And cementing agent 52, be used for disperse state fixing resin pearl 51.Also decentralized configuration is on the surface of light diffusion layer 42 for resin bead 51, and thus, the surface of light diffusion layer 42 is provided with the concaveconvex shape of small and disorder.Utilize the interface of this concaveconvex shape and resin bead 51 and cementing agent 52, further obtained making the function of light diffusion.
The refractive index of resin bead 51 is more than 1.50, preferably more than 1.52 and below 1.59, more preferably more than 1.55 and below 1.57.Because the refractive index of the resin bead in the light diffusing sheet in the past is about 1.49, so the refractive index of the resin bead 51 of this embodiment is greater than in the past resin bead.
Form not special qualification of main polymer of resin bead 51; Can adopt acryl resin, acrylonitrile resin, polyurethane, PVC, polystyrene, polyacrylonitrile, polyamide etc.; But the preferred multipolymer that adopts (methyl) acrylic monomer and styrene monomer more preferably adopts crosslinked (methyl) acrylic acid-styrene copolymer that obtains from (methyl) acrylic monomer, styrene monomer and cross-linkable monomer.Through adopting the main polymer that the styrene skeleton is imported (methyl) acrylic backbone, can improve the refractive index of resin bead 51, and, can further improve refractive index through further making it become cross-linked structure.In addition, when in cementing agent 52, using acrylic resin (acrylic polyol etc.), owing to have identical acrylic backbone, thus resin bead 51 evenly dispersion in cementing agent 52, thus positive briliancy can further be improved.
Above-mentioned (methyl) acrylic monomer can be enumerated: acrylic acid; Acrylic acid derivant, for example methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid pentyl ester, Hexyl 2-propenoate, acrylic acid heptyl ester, 2-ethyl hexyl acrylate, acrylic acid ester in the ninth of the ten Heavenly Stems, decyl acrylate, acrylic acid undecyl ester, dodecylacrylate, glycidyl acrylate, acrylic acid methoxyl ethyl ester, acrylic acid propoxyl group ethyl ester, acrylic acid butoxy ethyl ester, acrylic acid methoxyl diglycol ester, acrylic acid ethoxydiglycol ester, acrylic acid methoxyl glycol ester, acrylic acid butoxy triglycol ester, acrylic acid methoxyl DPG ester, acrylic acid phenoxy ethyl, acrylic acid phenoxy group diglycol ester, acrylic acid phenoxy group tetraethylene glycol ester, benzyl acrylate, cyclohexyl acrylate, acrylic acid tetrahydrochysene glycosyl ester, acrylic acid dicyclopentenyl ester, acrylic acid dicyclopentenyl oxygen base ethyl ester, acrylic acid N-vinyl-2-Pyrrolidone base ester, hydroxy-ethyl acrylate, hydroxypropyl acrylate, acrylic acid hydroxy butyl ester, acrylic acid 2-hydroxyl-3-phenoxy group propyl ester, glycidyl acrylate, vinyl cyanide, acrylic amide, N hydroxymethyl acrylamide, diacetone acrylamide; Or methacrylic acid; The derivant of methacrylic acid, for example methyl methacrylate, Jia Jibingxisuanyizhi, propyl methacrylate, butyl methacrylate, methacrylic acid pentyl ester, hexyl methacrylate, metering system heptyl heptylate, 2-Propenoic acid, 2-methyl-, octyl ester, nonyl methacrylate, decyl-octyl methacrylate, methacrylic acid undecyl ester, lauryl methacrylate, GMA, methacrylic acid methoxy base ethyl ester, methacrylic acid propoxyl group ethyl ester, methacrylic acid butoxy ethyl ester, methacrylic acid methoxy base diglycol ester, methacrylic acid ethoxydiglycol ester, methacrylic acid methoxy ethyl glycol ester, methacrylic acid butoxy triglycol ester, methacrylic acid methoxy base DPG ester, methacrylic acid phenoxy ethyl, methacrylic acid phenoxy group diglycol ester, methacrylic acid phenoxy group tetraethylene glycol ester, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid tetrahydrochysene glycosyl ester, methacrylic acid dicyclopentenyl ester, methacrylic acid dicyclopentenyl oxygen base ethyl ester, methacrylic acid N-vinyl-2-Pyrrolidone base ester, methacrylonitrile, Methacrylamide, N-methylol methacrylamide, methacrylic acid 2-hydroxyl ethyl ester, hydroxy propyl methacrylate, methacrylic acid hydroxy butyl ester, methacrylic acid 2-hydroxyl-3-phenoxy group propyl ester etc.Can use above-mentioned one or more combination.
Above-mentioned styrene monomer can enumerate styrene, AMS, vinyl methylbenzene, to styrene derivatives such as t-butyl styrene.Can use above-mentioned one or more combination.
Cross-linkable monomer can be enumerated divinylbenzene, ethylene glycol dimethacrylate, 1; 3-butanediol dimethylacrylate, 1; 4-butanediol dimethylacrylate, 1; 5-pentanediol dimethylacrylate, 1,6-hexanediol dimethacrylate, neopentylglycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, tripropylene glycol dimethylacrylate etc.Can use above-mentioned one or more combination.
In the aforementioned body polymkeric substance, except comprising (methyl) acrylic monomer, styrene monomer and the cross-linkable monomer, can also comprising other monomers.Other monomers can be enumerated vinyl acetate, vinyl chloride, br dilute anhydride, maleic acid, maleate, fumaric acid, fumarate, cyanacrylate etc.
For example obtain the resin bead of above-mentioned multipolymer in the state low suspension polymerization that has polymerization initiator as main polymer through the potpourri that makes each monomer.This suspension polymerization can be carried out in the aqueous mediums such as potpourri of water or water and ethanol usually.
The shape of above-mentioned resin bead 51 is not special to be limited, and can enumerate spherical, cubic, needle-like, bar-shaped, spindle shape, tabular, flakey, fibrous etc., wherein good spherical of preferred light diffusivity.
The mean particle diameter of above-mentioned resin bead 51 is preferably more than the 2 μ m and below 5 μ m, more preferably more than the 2.5 μ m and below 4 μ m.Through using the particle of this mean particle diameter, can improve light diffusing etc.In addition, the mean particle diameter among the present invention is meant the mean particle diameter of 30 particles randomly drawing in the particle that the electron microscope of 1000 times of multiplying powers observes.In addition, particle diameter is by Fei Leite footpath (interval when clipping projected image by the parallel lines of certain orientation) definition.
The pearl of resin bead 51 preferred polydispersity, the coefficient of alteration of particle diameter are preferably more than 20% and below 40%.Through using the pearl of this polydispersity, can improve light diffusing, and then can improve positive briliancy etc.
In addition; In the light diffusion layer 42 contained resin bead 51 with respect to the amount of allocating into of 100 mass parts cementing agents 52 preferably more than 40 mass parts and below 230 mass parts; More preferably more than 45 mass parts and below 100 mass parts, below 60 mass parts.The amount of allocating into of resin bead 51 is confirmed according to the size of mean particle diameter with the mode of further performance light diffusing.
Above-mentioned cementing agent 52 is cured and obtains the matrix material polymkeric substance by hardening agent usually.Can also suitably allocate plastifier, spreading agent, various levelling agent, ultraviolet light absorber, anti-oxidant, viscosity modifier, lubricant and light stabilizer etc. in the above-mentioned cementing agent 52.The matrix material polymkeric substance that this cementing agent 52 utilizes as the primary structure key element is with the whole surface of resin bead 51 cardinal principle isodensity ground fixed configurations at base material layer 41.
Above-mentioned matrix material polymkeric substance is not special to be limited; Acrylic resin, polyurethane, polyester, fluorine-type resin, silicon resinoid, polyamide-imides, epoxy resin, ultraviolet curing resin etc. can be enumerated, one or more combination of above-mentioned polymkeric substance can be used.Particularly above-mentioned matrix material polymkeric substance preferred polyol, its processability is high, can utilize mode such as coating easily to form light diffusion layer 42.In addition, because the matrix material polymkeric substance that cementing agent 52 uses needs transmitted ray, institute thinks transparent, preferred especially water white transparency.
Above-mentioned polyvalent alcohol preferred polyester polyvalent alcohol or (methyl) acrylic polyol, more preferably (methyl) acrylic polyol.These polyester polyols or acrylic polyol are high as the weatherability of the cementing agent 52 of matrix material polymkeric substance, can suppress light diffusion layer 42 flavescence etc.In addition, use under the situation of the multipolymer that contains above-mentioned (methyl) acrylic monomer,, can improve dispersiveness, and can improve positive briliancy etc. through using (methyl) acrylic polyol in resin bead 51.In addition, any side in the pure and mild acrylic polyol of this polyester polyols can be used, also both sides can be used.
The number of the hydroxyl in above-mentioned polyester polyols pure and mild (methyl) acrylic polyol does not just have special qualification so long as each molecule has more than two; If but the hydroxyl value in the solid constituent is below 10; Then number of crosslinks reduces, and has the tendency of the rerum natura decline of overlay films such as solvent resistance, water tolerance, thermotolerance, skin hardness.
As stated; Adopt at the matrix material polymkeric substance under the situation of polyvalent alcohol; The preferred hexamethylene diisocyanate of hardening agent, IPDI and XDI, more preferably hexamethylene diisocyanate, the especially preferably hexamethylene diisocyanate of add-on type.If use these hardening agent, then the curing reaction speed of polymer composition becomes big.The raising of this curing reaction speed helps resin bead uniformly dispersed in cementing agent.In addition, uniformly dispersed etc. in order further to improve, more preferably the pure and mild hexamethylene diisocyanate of (methyl) acrylic acid multielement is used in combination.
The refractive index of cementing agent 52 is preferably more than 1.49 and below 1.51.In addition, deduct value after the refractive index of above-mentioned cementing agent 52 preferably more than 0.06 and from the refractive index of above-mentioned resin bead 51 below 0.08.
Adhesion prevents that layer 43 from being made up of cementing agent and the pearl that is dispersed in this cementing agent.The composition of this cementing agent also can be identical with the cementing agent 52 of above-mentioned light diffusion layer 42.In addition, the material of pearl can be enumerated inorganic pearl and organic pearl.In addition, this adhesion prevents not special qualification of thickness (thickness of the cementing agent part except that pearl) of layer 43, for example can be more than the 1 μ m and below 10 μ m.
This adhesion prevents the amount of allocating into of the pearl in the layer 43 for more a small amount of, and pearl is dispersed in the cementing agent with being separated from each other, and most pearl is that its lower end is outstanding from the cementing agent minute quantity.Therefore, if this light diffusing sheet 31 is laminated in LGP 22, the lower end of then outstanding pearl is connected to the surface of LGP 22, the whole surface at light diffusing sheet 31 back sides not can with LGP 22 butts.Thus, prevent the adhesion of light diffusing sheet 31 and LGP 22, can suppress the luminance nonuniformity of liquid crystal indicator picture.
The manufacturing approach of light diffusing sheet 31 below is described.The manufacturing approach of this light diffusing sheet 31 for example comprises following operation: (a) through hybrid resin pearl 51 in the composition (matrix material polymkeric substance and hardening agent etc.) that constitutes cementing agent 52, and make light diffusion layer with applying liquid; (b) through this light diffusion layer is coated on the surface of base material layer 41 with coating liquid, and range upon range of light diffusion layer 42; (c) through mixed bead in the polymer composition that constitutes cementing agent, prevent that layer is with applying liquid and make to adhere to; (d) through this adhesion being prevented layer is coated on the back side of base material layer 41 with coating liquid, and range upon range of adhesion prevents layers 43.
(advancing of light)
Then, advancing of light in the liquid crystal indicator 1 of this embodiment is described.Light is by light source 21 luminous generations, and is as shown in Figure 2, from the light A of light source 21 by LGP 22 to optical unit 23 guiding, and injected first prismatic lens 32 from the whole surface at first prismatic lens, 32 back sides by light diffusing sheet 31 scatterings of optical unit 23.The light A that injects first prismatic lens 32 is by 32 refractions of first prismatic lens, and is upright towards the direction vertical with liquid crystal display cells 10 back sides thus, and advances to second prismatic lens 33.The light A that advances to second prismatic lens 33 further uprightly, is in fact vertically injected the back side of liquid crystal display cells 10 by 33 refractions of second prismatic lens.Thus, the light A from back light unit 20 injects liquid crystal display cells 10.
Because the rear side at liquid crystal display cells 10 is provided with rear side reflection Polarizer 13, thus inject a part of transmission rear side reflection Polarizer 13 of the light A of liquid crystal display cells 10, and remainder is reflected to back light unit 20 1 sides.Light A behind the transmission rear side reflection Polarizer 13 is transflective liquid crystal unit 12 and face side Polarizer 11 and penetrate to the face side of liquid crystal indicator 1 successively.Light A to back light unit 20 1 lateral reflections is reflected by the reflecting member of LGP 22, and as stated, liquid crystal display cells 10 is also injected once more in transmission optics unit 23.
(effect)
As stated, the light diffusing sheet 31 of this embodiment has light diffusion layer 42, and this light diffusion layer 42 comprises: the resin bead 51 with high index of refraction; And refractive index is preferably more than 1.49 and at the cementing agent below 1.51 52.Because the refractive index of the resin bead in the light diffusing sheet in the past is about 1.49 as stated, so the refractive index of the resin bead 51 of this embodiment is greater than in the past resin bead.The reflection or the ratio of refraction of the light that therefore, is produced by the resin bead of this embodiment 51 were big in the past.Its result, the light diffusing sheet 31 of this embodiment can cooperate with first prismatic lens 32 and second prismatic lens 33 as the high-gain prismatic lens, and performance is by the effect of the raising briliancy of first prismatic lens 32 and 33 generations of second prismatic lens.Therefore, the luminance ratio of the liquid crystal indicator 1 of this embodiment was high in the past, thereby had realized needed high briliancyization.
In addition, because first prismatic lens 32 and second prismatic lens 33 are the high-gain prismatic lenses that are made up of high-index material, so in the light that advances in this prismatic lens back side, the ratio of the light that is reflected uprises.But, according to this light diffusing sheet 31, because the reflection of the light that resin bead 51 produces or refraction are bigger, so reflexed to first prismatic lens 32 and second prismatic lens, 33 1 sides to the light of light diffusion layer 42 1 lateral reflections once more by light diffusion layer 42 by prismatic lens.Therefore, and compare the utilization ratio that has improved light in the past, and further realized the high briliancyization of liquid crystal indicator 1.
And, owing to realized the high briliancyization of liquid crystal indicator, thus can make back light unit 20 slimmings, and then can realize the slimming of liquid crystal indicator.In addition, utilize the light diffusing sheet 31 of this embodiment, the briliancy of liquid crystal indicator 1 that makes this embodiment is to keep higher state homogenising in picture.Therefore, can block back light unit 20 from face side.In addition, the cementing agent through adjusting light diffusing sheet 31 respectively and the refractive index of resin bead no matter have the high-gain prismatic lens of which type of refractive index, can realize utilizing the high-gain prismatic lens to make light upright towards vertical direction.
The haze value of this light diffusing sheet more preferably more than 80% and below 90%, through having this higher haze value, has further improved the positive briliancy of liquid crystal indicator 1 preferably more than 78% and below 93%.In addition, haze value is to be the value that benchmark is measured with JIS-K-7105.
As stated, because the liquid crystal indicator 1 of this embodiment has light diffusing sheet 31, this light diffusing sheet 31 comprises the resin bead 51 of the high index of refraction bigger than the refractive index of resin bead in the past, so further realized needed high briliancyization.Therefore, the liquid crystal indicator 1 of this embodiment can be as comprising the for example high briliancy display device from 2 inches to 22 inches all sizes.That is, the liquid crystal indicator 1 of this embodiment can be used as the display device of mobile phone, smart mobile phone, vehicle-mounted machine, game machine, panel computer, portable personal computer, notebook computer and monitor etc.
(variation)
In addition, in the above-described embodiment, optical unit 23 has first prismatic lens 32 and second prismatic lens 33.But optical unit 23 also can only have first prismatic lens 32 as prismatic lens.In addition, this light diffusing sheet also can not have to adhere to and prevents layer.
In addition, in the above-described embodiment, back light unit 20 is back light units of edge-light type.But back light unit 20 also can be the back light unit of full run-down type.Be under the situation of back light unit of full run-down type at back light unit 20,, light spread very bigly even optical unit 23 only has first prismatic lens 32 as prismatic lens.Its result can realize the high briliancyization of needed liquid crystal indicator.
In addition, in the above-described embodiment, light source 21 is arranged a plurality of light emitting diodes on straight line, but light source 21 also can be bar-shaped cold-cathode tube.In addition, in the above-described embodiment, LGP 22 is a wedge shape, but LGP 22 also can be plate.Thus, the form that comprises the back light unit 20 of light source 21 and LGP 22 is not limited to above-mentioned form.
In addition, in the above-described embodiment, liquid crystal display cells 10 has rear side reflection Polarizer 13, but liquid crystal display cells 10 also can adopt the Polarizer that does not possess reflection function to substitute rear side reflection Polarizer 13.
(embodiment)
Below the present invention is elaborated but the record of this embodiment and be not used in qualification the present invention based on embodiment.
[embodiment 1]
It is the transparent polyethylene terephthalate made membrane of 100 μ m that base material layer adopts thickness.The polymer composition that light diffusion layer adopts 100 parts of cementing agents (the hexamethylene diisocyanate class hardening agent of the pure and mild add-on type of acrylic acid multielement), 50 parts on resin system pearl and solvent to constitute with polymer composition.The umber of representing the amount of allocating into of each component is the mass ratio that solid content converts.Through utilizing the gravure coating method to use polymer composition with the range upon range of light diffusion layer of 5g/m2 (solid content conversion), obtain the light diffusing sheet of embodiment 1 at this matrix material laminar surface.The refractive index of above-mentioned cementing agent is 1.49, and crosslinked (methyl) acrylic acid-styrene copolymer that above-mentioned resin system pearl obtains with suspension polymerization is a main polymer.The refractive index of this resin bead is 1.56, mean particle diameter is 3.0 μ m (coefficients of alteration 30%).
[embodiment 2～10]
Except adopting the cementing agent of refractive index shown in the table 1, and beyond the resin bead of refractive index shown in the table 1, mean particle diameter and umber, likewise obtain the light diffusing sheet of embodiment 2～10 with embodiment 1.
[comparative example 1]
Except resin bead adopts the acrylic resin pearl (refractive index is 1.49) that suspension polymerization forms, likewise obtain the light diffusing sheet of comparative example 1 with the foregoing description 1.
[comparative example 2]
Except the amount of allocating into of resin bead is 100 mass parts, likewise obtain the light diffusing sheet of comparative example 2 with above-mentioned comparative example 1.
[comparative example 3]
Except adopting refractive index is 1.42 the cementing agent, likewise obtains the light diffusing sheet of comparative example 3 with above-mentioned comparative example 1.
[evaluating characteristics]
Adopt the light diffusing sheet of the foregoing description 1～10 and the light diffusing sheet of comparative example 1～3, measure the haze value of these light diffusing sheets.In addition, these light diffusing sheet actual assembled to the edge-light type back light unit, and have been measured positive briliancy.The result is shown in below table 1.In addition, this back light unit is at range upon range of two prismatic lenses of the face side of above-mentioned light diffusing sheet, and two prismatic lenses are configured to crest line and intersect each other.In addition, above-mentioned prismatic lens uses " BEF2-G2-MR-155 " of (strain) Sumitomo 3M corporate system.Evaluation result is as shown in table 1.In addition, positive briliancy is represented embodiment 1 as 100.0% relative value.
Table 1
Shown in above-mentioned table 1, the light diffusing sheet of embodiment 1～10 is compared with adopting in the past the light diffusing sheet of the comparative example of pearl, has shown high haze value and positive briliancy, has good optical characteristics.
(industrial applicibility)
Light diffusing sheet of the present invention, optical unit and back light unit can be as the structural elements of liquid crystal indicator.In addition, liquid crystal indicator of the present invention can be as the display device of mobile phone and personal computer etc.
Claims (13)
1. a light diffusing sheet comprises: transparent base material layer; And light diffusion layer, being laminated in the surface of said base material layer, and in cementing agent, having resin bead, said light diffusing sheet is characterised in that,
The refractive index of said resin bead is more than 1.50.
2. light diffusing sheet according to claim 1 is characterized in that,
The refractive index of said cementing agent is more than 1.49 and below 1.51,
The refractive index of said resin bead is more than 1.52 and below 1.59.
3. light diffusing sheet according to claim 1 is characterized in that, deducts value after the refractive index of said cementing agent from the refractive index of said resin bead more than 0.06 and below 0.08.
4. light diffusing sheet according to claim 1 is characterized in that, the main polymer of said resin bead is the multipolymer of (methyl) acrylic monomer and styrene monomer.
5. light diffusing sheet according to claim 1 is characterized in that, said resin bead with respect to the amount of allocating into of 100 mass parts cementing agents more than 40 mass parts and below 230 mass parts.
6. light diffusing sheet according to claim 1 is characterized in that, the haze value of said light diffusing sheet is more than 78% and below 93%.
7. light diffusing sheet according to claim 1 is characterized in that, the mean particle diameter of said resin bead is more than the 2 μ m and below 5 μ m.
8. light diffusing sheet according to claim 1 is characterized in that, said resin bead is the pearl of polydispersity.
9. optical unit is characterized in that comprising:
The described light diffusing sheet of claim 1; And
A prismatic lens is laminated in the face side of said light diffusing sheet,
The refractive index of said prismatic lens is more than 1.50.
10. optical unit is characterized in that comprising:
The described light diffusing sheet of claim 1; And
Two prismatic lenses are laminated in the face side of said light diffusing sheet,
Two said prismatic lenses are configured to crest line and intersect each other,
The refractive index of two said prismatic lenses is more than 1.50.
11., it is characterized in that the refractive index of said prismatic lens is more than 1.55 and below 1.70 according to claim 9 or 10 described optical units.
12. a back light unit is characterized in that comprising:
Light source;
LGP, incident have the light from said light source, and the said light of incident is penetrated; And
Claim 9 or 10 described optical units are laminated in the upside of said LGP.
13. a liquid crystal indicator is characterized in that comprising:
The described back light unit of claim 12; And
Liquid crystal display cells is configured in the top of the said prismatic lens of said back light unit.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
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| JP2011088697 | 2011-04-12 | ||
| JP2011-088697 | 2011-04-12 | ||
| JP2012-087862 | 2012-04-06 | ||
| JP2012087862A JP6046367B2 (en) | 2011-04-12 | 2012-04-06 | Optical unit, backlight unit, and liquid crystal display device |
Publications (2)
| Publication Number | Publication Date |
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| CN102736144A true CN102736144A (en) | 2012-10-17 |
| CN102736144B CN102736144B (en) | 2015-03-11 |
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| CN201210105534.1A Active CN102736144B (en) | 2011-04-12 | 2012-04-11 | Light diffusion sheet, optical unit, backlight unit and liquid crystal display device |
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| CN103913782A (en) * | 2012-12-28 | 2014-07-09 | 惠和株式会社 | Optical sheet and backlight unit |
| CN103939844A (en) * | 2013-01-17 | 2014-07-23 | 鸿富锦精密工业（深圳）有限公司 | Diffusion sheet and backlight module |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN102736144B (en) | 2015-03-11 |
| KR101362112B1 (en) | 2014-02-12 |
| KR20120116359A (en) | 2012-10-22 |
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