KR20180029658A - Optical sheet and backlight unit having the optical sheet - Google Patents

Abstract

Disclosed is an optical sheet which includes a light converting layer which includes: a light transmitting resin and a nano-emitting body dispersed therein; first and second transparent films spaced apart from each other while interposing the light converting layer therebetween; and first and second barrier layers arranged between the light converting layer and the first transparent film and between the light converting layer and the second transparent film, respectively. In the optical sheet, the degree of dispersion of the nano-emitting body can be improved by forming the light transmitting resin by curing a polymer composition including a multifunctional photo-curable oligomer, a monofunctional photo-curable monomer, a multifunctional photo-curable monomer, and a photo-curing initiator. Accordingly, the present invention can improve a color gamut.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an optical sheet and a backlight unit including the optical sheet.

The present invention relates to an optical sheet and a backlight unit including the optical sheet, and more particularly, to an optical sheet for a display device and a backlight unit including the same.

Nano emitters including quantum dots and the like are semiconductor materials having a crystal structure of several to several tens of nanometers in size, and they are composed of several hundred to several thousands of atoms. Since the band gap of a nano emitter formed of the same material becomes smaller as the size of the nano emitter becomes smaller, the luminescent characteristics of the nano emitter vary depending on the size of the nano emitter. In addition, even if a nano emitter of the same size is used, the luminescent characteristics vary depending on the material to be formed. By controlling the characteristics of such a nano-luminous body, it is widely used in various light emitting devices and electronic devices.

However, since the nano luminous body is very vulnerable to ultraviolet rays, heat, and moisture, if the nano luminous body is applied to an electronic apparatus or the like, the lifetime of the electronic apparatus is shortened. In particular, various methods for protecting a nano-luminous body from ultraviolet rays, heat, moisture and the like have been proposed in a film or a sheet including a nano-luminous body. However, there is a limit in blocking moisture penetration into a film or sheet.

On the other hand, the display device generally uses a white light source that emits white light. By passing the white light through the color filter, a user observing the display device can view the color image. The white light source includes a blue LED chip (light-emitting diode chip) emitting blue light, and a light switcher finally emitting a white light using a blue light. YAG (Yttrium Aluminum Garnet), which is a phosphor, is mainly used as the light switching element. However, since the phosphors have a wide range of emission spectrum over the red light wavelength band and the green light wavelength band, there is a limit to increase the color purity of the color that the white light source using the phosphor passes through the color filter. In addition, the color reproducibility of the display device using the white light source to which the phosphor is applied is low.

In order to improve the color reproducibility of a display device, various studies are currently underway to apply a nano emitter having a luminescence spectrum with a narrow full width at half maximum (FWHM) and a high power density to a display device.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide an optical sheet capable of enhancing color reproducibility including a nano emitter and capable of stably protecting the nano emitter from ultraviolet rays, heat, .

Another object of the present invention is to provide a backlight unit that improves the color reproducibility of a display device by using the optical sheet.

An optical sheet according to an embodiment of the present invention includes a light conversion layer including a light transmitting resin and a nano emitter dispersed in the resin; First and second transparent films spaced apart from each other with the light conversion layer interposed therebetween; A first barrier layer disposed between the photo-conversion layer and the first transparent film; And a second barrier layer disposed between the photo-conversion layer and the second transparent film, wherein the translucent resin comprises a multifunctional photo-curable oligomer, a monofunctional photo-curable monomer, a multifunctional photo-curable monomer, and a photo-curable initiator Is formed by curing the polymer composition.

In one embodiment, the multifunctional photocurable oligomer is selected from the group consisting of urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, (Meth) acrylate, and melamine (meth) acrylate, and the monofunctional photocurable monomer may include isobonyl (meth) acrylate, isooctyl (meth) acrylate, (Meth) acrylate, n-hexyl (meth) acrylate, adamantyl acrylate and cyclopentyl acrylate (meth) acrylate, benzyl And the multifunctional photocurable monomer may include one or more monomers selected from the group consisting of iso Acrylate, norbornyl (meth) acrylate, cyclohexyl (meth) acrylate, n-hexyl (meth) acrylate, (Meth) acrylate, adamantyl acrylate, and cyclopentyl acrylate. In this case, the multifunctional photocurable oligomer may have an average molecular weight (Mw) of 100 to 10000, and the monofunctional photocurable monomer and the multifunctional photocurable monomer may have an average molecular weight of 200 to 400.

In one embodiment, the content of the multifunctional photocurable oligomer (C1), the content of the monofunctional photocurable monomer (C2), the content of the multifunctional photocurable monomer (C3) and the content of the photocurable initiator (C4 ) Can satisfy all the relations of the following expressions (1) and (2).

[Equation 1]

[Equation 2]

In one embodiment, the content (C1) of the multifunctional photocurable oligomer is selected from the content of the multifunctional photocurable oligomer (C1), the content of the monofunctional photocurable monomer (C2), the content of the multifunctional photocurable monomer (C 1 + C 2 + C 3 + C 4) of the content (C 3) of the photopolymerization initiator and the content (C 4) of the photocurable initiator.

In one embodiment, the content (C2) of the monofunctional photocurable monomer and the content (C3) of the multifunctional photocurable monomer may be in the range of about 85:15 to 50:50.

In one embodiment, the nano emitter may include a red quantum dot or a green quantum dot, and the nano emitter may be included in an amount of 0.5 wt.% To 3.0 wt.% Based on the total weight of the light conversion layer.

In one embodiment, the light conversion layer may further include light scattering beads dispersed in the transparent resin. In this case, the light scattering beads may be formed of titanium oxide (TiO 2), silicon oxide (SiO 2), aluminum oxide (Al 2 O 3), or zinc oxide (ZnO).

In one embodiment, the first barrier layer has a structure including at least one first barrier laminate structure composed of an overcoat layer, an inorganic film layer, and a hard coat layer successively stacked from the light conversion layer toward the first transparent film Or a second barrier laminated structure composed of an overcoat layer and an inorganic film layer continuously stacked from the light conversion layer in the direction of the first transparent film and has a structure comprising at least one of the first barrier laminate structure and the second barrier laminate structure, One or more of the second barrier laminate structures may have a laminated structure. In this case, the hard coating layer may comprise a polymer of a (meth) acrylate oligomer having a (meth) acrylate monomer and an epoxy group and having a weight average molecular weight (Mw) of 500 to 10,000, At least one element selected from the group consisting of aluminum (Al), indium (In), tin (Sn), zinc (Zn), titanium (Ti), copper (Cu), cerium (Ce) A nitride, a carbide, an oxynitride, an oxide carbide, a nitride carbide, or a oxynitride carbide containing a metal.

The hard coating layer may further include light scattering beads dispersed in the polymer of the (meth) acrylate oligomer and formed of titanium oxide (TiO2), silicon oxide (SiO2), aluminum oxide (Al2O3), or zinc oxide (ZnO) can do.

In one embodiment, the optical sheet includes a first optical layer disposed on an upper surface of the first transparent film and having a first light diffusion pattern formed on a surface thereof; And a second optical layer disposed on a lower surface of the second transparent film and having a second light diffusion pattern formed on a surface thereof.

A backlight unit according to an embodiment of the present invention includes a light emitting element for generating blue light; And a diffusion sheet for diffusing the blue light and converting at least part of the blue light into green light or red light. And the diffusion sheet comprises a light conversion layer including a light transmitting resin and a nano light emitter dispersed in the resin; First and second transparent films spaced apart from each other with the light conversion layer interposed therebetween; A first barrier layer disposed between the photo-conversion layer and the first transparent film; And a second barrier layer disposed between the photo-conversion layer and the second transparent film, wherein the translucent resin comprises a multifunctional photo-curable oligomer, a monofunctional photo-curable monomer, a multifunctional photo-curable monomer, and a photo-curable initiator And then curing the resulting polymer composition.

The light guide plate may further include a light guide plate disposed adjacent to the light emitting device and below the diffusion sheet and guiding the blue light generated from the light emitting device toward the diffusion sheet.

In one embodiment, the light emitting device may include a plurality of blue light emitting diodes arranged under the diffusion sheet.

According to the optical sheet of the present invention and the backlight unit including the optical sheet, the light conversion layer in which the nano light emitter is dispersed therein is made of a multifunctional photo-curable oligomer, a monofunctional photocurable monomer, a multifunctional photocurable monomer and a photo- , The dispersibility of the nano-luminous body can be improved while maintaining the mechanical properties of the light conversion layer. In addition, since the optical sheet includes first and second transparent films disposed above and below the light conversion layer and first and second barrier layers disposed between the first and second transparent films, respectively, the nano light emitters Can be stably protected from external moisture or oxygen.

1 is a cross-sectional view illustrating an optical sheet according to an embodiment of the present invention.
2A and 2B are sectional views for explaining embodiments of the optical sheet shown in FIG.
3 is a cross-sectional view illustrating a backlight unit according to an embodiment of the present invention.
4 is a cross-sectional view illustrating a backlight unit according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the intention is not to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In the accompanying drawings, the dimensions of the structures are shown enlarged or reduced from the actual size for the sake of clarity of the present invention.

The terms " first, second, " and the like can be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprises", "comprising", or "having" are used to specify that there is a stated feature, step, operation, component, It is to be understood that the foregoing does not preclude the presence or addition of one or more other features, steps, operations, elements, parts or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

As used herein, "functional compound" means a compound having a photocurable functional group, and "(meth) acrylate" means acrylate or methacrylate.

FIG. 1 is a cross-sectional view for explaining an optical sheet according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are sectional views for explaining embodiments of the optical sheet shown in FIG.

1, 2A, and 2B, an optical sheet 100 according to an embodiment of the present invention includes a light conversion layer 110, first and second transparent films 120 and 130, and first and second Barrier layer 140,150.

At least a part of the light of the first wavelength provided from the light source device of the light conversion layer 110 display device can be converted into light of the second wavelength larger than the first wavelength.

The light conversion layer 110 may include a light transmitting resin and a nano light emitting material dispersed in the light transmitting resin.

The light-transmissive resin is a transparent material that transmits light, and can be a base material that is cured by light to disperse the nano-luminous body. In one embodiment, the light transmitting resin may be formed by curing a polymer composition comprising a multifunctional photo-curable oligomer, a monofunctional photocurable monomer, a multifunctional photocurable monomer, and a photo-curing initiator.

The multifunctional photo-curable oligomer maintains the mechanical properties of the photo-conversion layer 110 to secure its stable reliability, and more effectively blocks moisture and oxygen from the outside to stabilize the nano-luminescent material, which is susceptible to moisture and oxygen. Can be improved. The multifunctional photocurable oligomer may comprise at least one oligomer having at least two acrylate functional groups or at least two methacrylate functional groups. For example, the multifunctional photo-curable oligomer can be selected from the group consisting of urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, acrylic (meth) acrylate, polybutadiene (Meth) acrylate, melamine (meth) acrylate, and the like.

In one embodiment, the multifunctional photo-curable oligomer may be an oligomer having an average molecular weight (Mw) of about 100 to 10000 and oligomers having a viscosity of about 2000 to 20,000 cPs at about 60 ° C.

The monofunctional photocurable monomer can improve the workability and moldability of the polymer composition by lowering the viscosity of the polymer composition and improve the initial dispersibility of the nano-emitter. In one embodiment, the monofunctional photocurable monomer is selected from the group consisting of isobonyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, benzyl (meth) acrylate, (Meth) acrylate, cyclohexyl (meth) acrylate, n-hexyl (meth) acrylate, adamantyl acrylate, cyclopentyl acrylate and the like. In one embodiment, the monofunctional light curable monomer may be a monomer having an average molecular weight (Mw) of about 200 to 400 and a viscosity of about 1 to 100 cPs at about 25 DEG C, among the above monomers.

The multifunctional photocurable monomer may be used in combination with the monofunctional photocurable monomer to further reduce the viscosity of the polymer composition to improve workability and moldability, as well as to improve the hardening property of the monofunctional photocurable monomer It is possible to effectively prevent penetration of external moisture or oxygen. The multifunctional photocurable monomer may comprise at least two acrylate functional groups or at least one monomer having two or more methacrylate functional groups. For example, the multifunctional photocurable monomer may be selected from the group consisting of isobonyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, benzyl (meth) acrylate, (Meth) acrylate, cyclohexyl (meth) acrylate, n-hexyl (meth) acrylate, adamantyl acrylate, cyclopentyl acrylate and the like. In one embodiment, the multifunctional photocurable monomer may be a monomer having an average molecular weight (Mw) of about 200 to 400 and a viscosity of about 1 to 100 cPs at about 25 DEG C of the above monomers.

On the other hand, the multifunctional photocurable monomer may have the same functional group as the monofunctional photocurable monomer. When the multifunctional photopolymerizable monomer has the same functional group as the monofunctional photopolymerizable monomer, the mechanical properties of the photoconversion layer 110 can be further improved after the photopolymerization.

In the polymer composition, the content (C1) of the multifunctional photocurable oligomer, the content (C2) of the monofunctional photopolymerizable monomer, the content (C3) of the multifunctional photopolymerizable monomer and the content ) Can satisfy all the relations of the following expressions (1) and (2).

[Equation 1]

[Equation 2]

Wherein the content (C1) of the multifunctional photo-curable oligomer is a content (C1) of the multifunctional photocurable oligomer, a content (C2) of the monofunctional photopolymerizable monomer, a content (C3) of the multifunctional photopolymerizable monomer, When the content of the initiator (C4) is less than 0.5 times the content (C1 + C2 + C3 + C4), the mechanical properties of the photoconversion layer 110 may be deteriorated. The content (C1) of the multifunctional photocurable oligomer (C1), the content of the monofunctional photocurable monomer (C2), the content of the multifunctional photocurable monomer (C3) and the content of the photocurable initiator (C4) (C1 + C2 + C3 + C4), the viscosity of the polymer composition becomes excessively high, so that the dispersibility of the nano-luminophore decreases, resulting in the problem that the nano-luminophors aggregate .

In one embodiment, in order to uniformly disperse the nano-luminous bodies in the light conversion layer 110 while preventing deterioration of the mechanical properties of the light conversion layer 110, and to improve the moldability and workability of the polymer composition, In the polymer composition, the content (C1) of the multifunctional photocurable oligomer is preferably in the range of the content (C1) of the multifunctional photocurable oligomer, the content (C2) of the monofunctional photocurable monomer, the content of the multifunctional photocurable monomer (C 1 + C 2 + C 3 + C 4) of the content (C 3) of the photopolymerization initiator and the content (C 4) of the photocuring initiator is preferably about 0.55 times or more and about 0.70 times or less.

Meanwhile, in one embodiment, the nano light emitters are uniformly dispersed in the light conversion layer 110 while the mechanical properties of the light conversion layer 110 are prevented from deteriorating, and the moldability and workability of the polymer composition are improved , The content (C2) of the monofunctional photocurable monomer and the content (C3) of the multifunctional photocurable monomer may be in the range of about 85:15 to 50:50. When the content ratio [C3 / (C2 + C3)] of the monofunctional photocurable monomer and the multifunctional photocurable monomer in the entire multifunctional photocurable monomer is less than 0.15, the degree of curing of the photoconversion layer decreases, When the content ratio [C3 / (C2 + C3)] exceeds 0.5, the hardness of the photo-conversion layer becomes excessively high, and cracks or the like may be generated inside due to an external impact have.

The nano-luminous body includes at least one of a green quantum dot having a maximum emission peak within a wavelength range of about 510 to 560 nm corresponding to green light and a red quantum dot having a maximum emission peak within a wavelength range of about 600 to 660 nm corresponding to red light can do. Since known quantum dots can be applied to the green quantum dot and the red quantum dot without any limitations, detailed description of the structure and material thereof is omitted.

The green quantum dot may have a full width at half maximum (FWHM) of about 55 nm or less, and the red quantum dot may have a half width of about 60 nm or less. In one embodiment, the nano emitter may be included in an amount of about 0.5 to 3.0 wt.% Based on the total weight of the light conversion layer 110.

In one embodiment of the present invention, the light conversion layer 110 may further include light scattering beads dispersed in the transparent resin. The light scattering beads may be formed of titanium oxide (TiO 2), silicon oxide (SiO 2), aluminum oxide (Al 2 O 3), zinc oxide (ZnO) or the like and may have a diameter of about 0.1 to 0.5 μm. In one embodiment, the light scattering beads may be included in an amount of about 0.1 to 5.0 wt.% Based on the total weight of the light conversion layer 110.

The first transparent film 120 may be disposed on the light conversion layer 110 and the second transparent film 130 may be disposed on the light conversion layer 110. The first and second transparent films 120 and 130 may have transmittance of about 60% or more, preferably about 90% or more, for light in the visible light region.

Each of the first and second transparent films 120 and 130 may be formed of polycarbonate (PC), polyimide (PI), polyethersulfone (PES), polyarylate (PAR) ), Polyethylene naphthalate (PEN), polyethylene terephthalate (PET), cycloolefin copolymer (COC), polymethylmethacrylate (PMMA), polyethylene terephthalate A thermoplastic resin such as polyethylene (PE), polypropylene (PP), methacrylic, or polyurethane, or a curable resin such as an acrylic resin, an epoxy resin, or an unsaturated polyester resin .

The first barrier layer 140 is disposed between the light conversion layer 110 and the first transparent film 120 and the second barrier layer 150 is disposed between the light conversion layer 110 and the second And may be disposed between the transparent films 130.

2A, each of the first and second barrier layers 140 and 150 is sequentially laminated in the direction of the transparent film 120 and 130 from the photo-conversion layer 110. In one embodiment, A first barrier laminate structure 140a or 150a made up of overcoat layers 141 and 151, inorganic film layers 142 and 152 and hard coat layers 143 and 153. 2B, each of the first and second barrier layers 140 and 150 may be formed continuously from the light conversion layer 110 in the direction of the transparent films 120 and 130 The second barrier laminated structure 140b or 150b may include at least one layered overcoat layer 141 or 151 and a second barrier laminate structure 140b or 150b made up of the inorganic film layers 142 and 152. In yet another embodiment, each of the first and second barrier layers 140 and 150 includes at least one of the first barrier laminate structure 140a and the at least one second barrier laminate structure 140b, May have a laminated structure.

The inorganic film layers 142 and 152 may be formed of at least one selected from the group consisting of Si, Al, In, Sn, Zn, Ti, Cu, A nitride, a carbide, an oxide nitride, an oxide carbide, a nitride carbide, an oxynitride carbide, or the like containing at least one metal selected from the group consisting of tantalum (Ta) and the like.

The overcoat layers 141 and 151 are formed by bonding the inorganic film layers 142 and 152 to the light conversion layer 110 to prevent the inorganic film layers 142 and 152 from being separated from the light conversion layer 110 , It is possible to prevent the inorganic film layers 142 and 152 from being damaged by supplementing the mechanical properties of the inorganic film layers 142 and 152. In one embodiment, the overcoat layers 141 and 151 are formed of a metal alkoxide, an organic acid curing accelerator, an inorganic acid, water, a (meth) acrylate monomer, a urethane group and a weight average molecular weight (Mw) ) Acrylate oligomer, a silicon alkoxide having a (meth) acrylate group, and an initiator.

In one embodiment, the metal alkoxide may include any one selected from metal alkoxides represented by the following Chemical Formulas 1 to 3, or a mixture of two or more thereof.

[Chemical Formula 1]

R1 _x M1 (OR2) _{4- x}

(2)

R1 _& lt _{; /} RTI > _y M2 (OR2) _{3- y}

(3)

R1 _z Nb (OR2) _{5 -z}

R 1 may be any one selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, a vinyl group, an allyl group, a (meth) acryloxy group, an epoxy group, and an amino group; And Ml may be a metal selected from the group consisting of Si, Ti, Zr, Ge, and Sn, and M2 may be a metal selected from the group consisting of Al, In, and Sb. And x may be an integer of 0 or more and 3 or less, y may be an integer of 0 or more and 2 or less, and z may be an integer of 0 or more and 4 or less.

The hard coating layers 143 and 153 are formed by bonding the inorganic film layers 142 and 152 to the transparent films 120 and 130 so that the inorganic film layers 142 and 152 and the transparent films 120 and 130 are separated from each other It is possible to prevent the inorganic film layers 142 and 152 from being broken by supplementing the mechanical properties of the inorganic film layers 142 and 152 together with the overcoat layers 141 and 151.

The hard coating layers 143 and 153 may be formed using a polymer composition having a (meth) acrylate monomer and an epoxy group and having a weight average molecular weight (Mw) of about 500 to 10,000 and a initiator in a solvent .

Each of the laminated structure of the first transparent film 120 and the first barrier layer 140 and the laminated structure of the second transparent film 130 and the second barrier layer 150 has a thickness of about 50 to 150 μm M2 / day / atm and a water vapor transmission rate of less than about 0.1 g / m2 / day. Lt; / RTI >

The optical sheet 100 according to the embodiment of the present invention includes a first optical layer 160 disposed on the upper surface of the first transparent film 120 and a second optical layer 160 disposed on the lower surface of the second transparent film 130 And a second optical layer 170 disposed on the second optical layer 170.

A light diffusion pattern may be formed on the surfaces of the first and second optical layers 160 and 170, respectively. The light diffusion pattern may include convex or concave patterns that protrude or sink from the surface to diffuse the light.

According to the optical sheet (100) of the present invention, the light conversion layer (110) in which the nano emitter is dispersed therein is formed by mixing a multifunctional photocurable oligomer, a monofunctional photocurable monomer, a multifunctional photocurable monomer, The dispersibility of the nano-luminous body can be improved while maintaining the mechanical properties of the light conversion layer 110. The optical sheet 100 may include first and second transparent films 120 and 130 disposed on upper and lower sides of the light conversion layer 110 and first and second barrier layers 140 and 140 disposed between the first and second transparent films 120 and 130, , 150), so that the nano light emitters in the light conversion layer 110 can be stably protected from external moisture or oxygen.

3 is a cross-sectional view illustrating a backlight unit according to an embodiment of the present invention.

3, a backlight unit 1000 according to an exemplary embodiment of the present invention includes a light emitting device 1100, a light guide plate 1200, a reflection plate 1300, a diffusion sheet 1400, a first condensing sheet 1500, and a second light-condensing sheet 1600.

The light emitting device 1100 may generate light and emit the light toward the light guide plate 1200.

In one embodiment, the light emitting device 1100 may be a blue light emitting device that emits blue light. In this case, the light emitting device 1100 includes a blue light emitting diode that generates blue light, and the blue light generated from the blue light emitting diode may be directly provided to the light guide plate 1200.

As another example, the light emitting device 1100 may be a white light emitting device that emits white light. In this case, the light emitting device 1100 may include a blue light emitting diode that generates blue light, and a light conversion layer that covers the blue light emitting diode and converts a part of the blue light into red light and green light.

The blue light emitting diode may generate blue light having a maximum emission peak within a range of about 430 to 470 nm, and the emission spectrum of the blue light generated by the blue light emitting diode may have a half width (FWHM) of about 45 nm or less. Preferably, the emission spectrum of the blue light may have a half width of about 25 nm or less.

The light guide plate 1200 may be disposed adjacent to the light emitting device 1100 to guide the light provided from the light emitting device 1100 toward the diffusion sheet 1400.

The reflection plate 1300 is disposed under the light guide plate 1200 and may reflect the light leaking to the lower portion of the light guide plate 1200 toward the light guide plate 1200 to increase the light utilization efficiency.

The diffusion sheet 1400 may be disposed on the light guide plate 1200. As the diffusion sheet 1400, the optical sheet 100 described with reference to FIGS. 1, 2A, and 2B can be used, so that a detailed description thereof will be omitted. Since the diffusion sheet 1400 includes the light conversion layer 110, it can emit red or green light by absorbing at least a part of the light emitted from the light guide plate 1200, And the light scattering beads dispersed in the light converting layer 110, so that the light emitted from the light guide plate 1200 can be diffused and emitted.

The first and second light collecting sheets 1500 and 1600 are disposed on the diffusion sheet 1400 to condense and emit light diffused and emitted from the diffusion sheet 1400 in the direction of a display panel have.

The first light collecting sheet 1500 may be disposed on the diffusion sheet 1400 and a first light collecting pattern including a plurality of protrusions may be formed on the surface of the first light collecting sheet 1500. The first condensing pattern may face the second condensing sheet 1600. The second light condensing sheet 1600 is disposed on the first light condensing sheet 1500 and the surface of the second light condensing sheet 1600 has substantially the same shape as the protruding portion formed on the first light condensing sheet 1500 And a second light converging pattern including a plurality of projecting portions having a plurality of projections may be formed. The second condensing pattern may face the display panel. The longitudinal direction of the protrusion of the first condensing pattern and the longitudinal direction of the protrusion of the second condensing pattern may intersect with each other. In this case, the angle of intersection of the longitudinal directions of the protrusions may be about 90 °.

4 is a cross-sectional view illustrating a backlight unit according to another embodiment of the present invention.

4, a backlight unit 2000 according to another embodiment of the present invention includes a light emitting device 2100, a reflection plate 2300, a diffusion plate 2400, a diffusion sheet 2450, a first condensing sheet 2500, And a second light condensing sheet 2600.

The backlight unit 2000 according to the present embodiment is characterized in that the light emitting device 2100 includes a plurality of light emitting diodes disposed under the diffusion plate 2400 and a diffusion sheet 2450 is formed on the diffusion plate 2400 3, and thus detailed description thereof will be omitted herein. [0120] As shown in FIG.

The backlight unit 2000 according to the present embodiment may be a direct type and the diffusion plate 2400 may be disposed on the light emitting device 2100. The diffusion sheet 2450 may be disposed on the diffusion plate 2400, As shown in FIG. As the diffusion plate 2400 or the diffusion sheet 2450, the optical sheet 100 described with reference to FIGS. 1, 2A, and 2B can be used, so that detailed description thereof will be omitted.

Since the diffusion plate 2400 or the diffusion sheet 2450 includes the light conversion layer 110, it can absorb at least a part of the blue light emitted from the light emitting device 2100 to emit red or green light The light scattering beads dispersed in the light conversion layer 110 and the optical layers 160 and 170 having the light diffusion patterns formed on the surface thereof can diffuse and emit the light emitted from the light emitting device 2100. [

Hereinafter, technical effects of the present invention will be described based on examples and comparative examples of the present invention. However, the following embodiments are only a few embodiments of the present invention, and the present invention should not be construed as being limited to the following embodiments.

[Examples 1 to 3]

Optical sheets according to Examples 1 to 3 were produced according to the following process.

First, the sum of the content (C1) of the multifunctional photocurable oligomer, the content (C2) of the monofunctional photopolymerizable monomer, the content (C3) of the multifunctional photopolymerizable monomer and the content (C4) C4) in a ratio of 55:45 (Example 1), 60:40 (Example 2) and 70:30 (Example 3), red and green quantum dots were added to the total weight of the polymer composition By weight based on the total weight of the polymer composition. As the multifunctional photo-curable oligomer, urethane (meth) acrylate is used, and the monofunctional photopolymerizable monomer, the multifunctional photopolymerizable monomer and the photopolymerization initiator include isobonyl (meth) acrylate, benzyl Meth) acrylate and TPO were respectively used.

Subsequently, a first barrier layer was formed on the first transparent film, and then the polymer composition for forming a photo-conversion layer was coated on the first barrier layer to form a photo-conversion layer. At this time, the first transparent film is formed of PET, and the first barrier layer is formed by sequentially forming a hard coating layer formed of urethane acrylate on the first transparent film, an inorganic film layer formed of SiOx, and an overcoat layer formed of silicon alkoxide .

Then, a second barrier layer is formed on the second transparent film, and the second barrier layer is disposed on the light conversion layer so as to contact the light conversion layer. Finally, ultraviolet light is irradiated to the light conversion layer, To thereby produce an optical sheet.

[Comparative Examples 1 and 2]

In Examples 1 to 3, except that the content ratio of the multifunctional photocurable oligomer, the monofunctional photocurable monomer, the multifunctional photocurable monomer and the photocuring initiator was varied in preparing the polymer composition for photoconversion layer formation, Optical sheets according to Comparative Examples 1 and 2 were prepared by the same process.

Specifically, the sum of the content (C1) of the multifunctional photocurable oligomer and the content (C2) of the monofunctional photopolymerizable monomer, the content (C3) of the multifunctional photopolymerizable monomer and the content (C4) (C2 + C3 + C4) ratio of 51:49 (Comparative Example 1) and 85:15, to prepare the polymer composition for forming a photo-conversion layer.

[Experimental Example 1]

The optical sheets of Examples 1 to 3 and Comparative Examples 1 and 2 were maintained at a temperature of 60 DEG C and a relative humidity of 95% for 1000 hours, and then the ratio of the initial luminance to the final luminance was measured. Respectively.

Final luminance (%) Example 1 90 Example 2 93 Example 3 89 Comparative Example 1 84 Comparative Example 1 81

Referring to Table 1, the optical sheets of Examples 1 to 3 exhibited a higher luminance than the optical sheets of Comparative Examples 1 and 2 even when they were maintained at a temperature of 60 ° C and 95% relative humidity for 1000 hours, Can be confirmed.

In the case of Comparative Example 1, the thickness of the light conversion layer formed by the low viscosity of the polymer composition is reduced, and when the thickness of the light conversion layer is reduced, the internal quantum dots are easily deteriorated by moisture or oxygen, The luminance decreases as time elapses. On the other hand, in the case of Comparative Example 2, since the polymer composition has high viscosity, the quantum dots are unevenly distributed in the light conversion layer formed thereby and the quantum dots are easily deteriorated by moisture or oxygen in the portion where the quantum dots are aggregated. So that the lowering of the luminance is increased.

[Experimental Example 2]

After the display devices to which the optical sheets of Examples 1 to 3 and Comparative Examples 1 and 2 were respectively applied, luminance, color recall, and color uniformity were measured, and the results are shown in Table 2. At this time, the chromaticity coordinates were measured for nine points in the display area of the display device, and then the difference between them was calculated and evaluated.

Luminance Color recall (%)
[DCI-P3 CIE1976 coverage] Color coordinate uniformity ? U ' ? V? Example 1 369 97.2 0.006 0.007 Example 2 380 97.8 0.003 0.005 Example 3 372 96.8 0.007 0.011 Comparative Example 1 363 97.1 0.009 0.015 Comparative Example 2 351 95.2 0.022 0.028

Referring to Table 2, it can be seen that display devices to which the optical sheets of Examples 1 to 3 are applied exhibit relatively higher brightness, higher color recall, and uniformity of color coordinates than display devices to which Comparative Examples 1 and 2 are applied. This is because the quantum dots in the optical sheets of Examples 1 to 3 are more uniformly dispersed in the light conversion layer in the optical sheets of Comparative Examples 1 and 2.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. It can be understood that it is possible.

100: optical sheet 110: photo-conversion layer
120: first transparent film 130: second transparent film
140: first barrier layer 150: second barrier layer
1000, 2000: backlight unit 1100, 2100: light emitting element
1200: light guide plate 1300, 2300: reflector
1400: diffusion sheet 2400: diffusion plate
1500, 2500: first condensing sheet 1600: second condensing sheet

Claims (23)

A light conversion layer comprising a light transmitting resin and a nano emitter dispersed in the resin;
First and second transparent films spaced apart from each other with the light conversion layer interposed therebetween;
A first barrier layer disposed between the photo-conversion layer and the first transparent film; And
And a second barrier layer disposed between the photo-conversion layer and the second transparent film,
Wherein the light transmitting resin is formed by curing a polymer composition comprising a multifunctional photocurable oligomer, a monofunctional photocurable monomer, a multifunctional photocurable monomer, and a photocuring initiator. The method according to claim 1,
The multifunctional photocurable oligomer may be at least one selected from the group consisting of urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, acryl (meth) acrylate, polybutadiene And at least one oligomer selected from the group consisting of melamine (meth) acrylate,
The monofunctional photocurable monomer may be selected from the group consisting of isobonyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, benzyl (meth) acrylate, ) Acrylate, n-hexyl (meth) acrylate, adamantyl acrylate, and cyclopentyl acrylate,
The multifunctional photocurable monomer may be at least one selected from the group consisting of isobonyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, benzyl (meth) acrylate, ) Acrylate, n-hexyl (meth) acrylate, adamantyl acrylate, and cyclopentyl acrylate. 3. The method of claim 2,
The multifunctional photocurable oligomer has an average molecular weight (Mw) of 100 to 10000,
Wherein the monofunctional photocurable monomer and the multifunctional photocurable monomer have an average molecular weight of 200 to 400. 3. The method of claim 2,
The content (C1) of the multifunctional photocurable oligomer, the content (C2) of the monofunctional photocurable monomer, the content (C3) of the multifunctional photocurable monomer and the content (C4) of the photocurable initiator satisfy the following formulas 2 < / RTI >:< RTI ID = 0.0 >
[Equation 1]

[Equation 2]

3. The method of claim 2,
(C1) of the multifunctional photocurable oligomer, the content (C2) of the monofunctional photocurable monomer, the content (C3) of the multifunctional photocurable monomer, and the content Is not less than 0.55 times and not more than 0.70 times the sum (C1 + C2 + C3 + C4) of the content (C4) of the initiator. 5. The method of claim 4,
Wherein the content (C2) of the monofunctional photocurable monomer and the content (C3) of the multifunctional photocurable monomer have a ratio within a range of 85:15 to 50:50. The method according to claim 1,
Wherein the nano emitter comprises a red quantum dot or a green quantum dot,
Wherein the nano emitter is contained in an amount of 0.5 wt.% To 3.0 wt.% Based on the total weight of the light conversion layer. The method according to claim 1,
Wherein the light conversion layer further comprises light scattering beads dispersed in the transparent resin. 9. The method of claim 8,
Wherein the light scattering beads are formed of titanium oxide (TiO2), silicon oxide (SiO2), aluminum oxide (Al2O3), or zinc oxide (ZnO). The method according to claim 1,
Wherein the first barrier layer has a structure including at least one first barrier laminate structure composed of an overcoat layer, an inorganic film layer, and a hard coat layer successively stacked from the light conversion layer in the direction of the first transparent film Sheet. The method according to claim 1,
Wherein the first barrier layer has a structure including at least one second barrier laminated structure composed of an overcoat layer and an inorganic film layer continuously stacked from the light conversion layer in the direction of the first transparent film. The method according to claim 1,
Wherein the first barrier layer comprises a first barrier laminate structure composed of an overcoat layer, an inorganic film layer, and a hard coat layer successively stacked in the direction of the first transparent film from the light conversion layer, and a second barrier laminate structure And a second barrier laminated structure composed of an overcoat layer and an inorganic film layer successively laminated. 13. The method according to any one of claims 10 to 12,
Wherein the hard coat layer comprises a polymer of a (meth) acrylate oligomer having a (meth) acrylate monomer and an epoxy group and having a weight average molecular weight (Mw) of 500 to 10,000,
Wherein the inorganic film layer is made of a material selected from the group consisting of Si, Al, In, Sn, Zn, Ti, Cu, An oxide, a nitride, a carbide, an oxynitride, an oxycarbide, a nitride carbide, or a oxynitride carbide containing at least one metal selected from the group consisting of oxides, nitrides, carbides, 14. The method of claim 13,
The hard coating layer further comprises light scattering beads dispersed in the polymer of the (meth) acrylate oligomer and formed of titanium oxide (TiO2), silicon oxide (SiO2), aluminum oxide (Al2O3) or zinc oxide (ZnO) Characterized by an optical sheet. 13. The method according to any one of claims 10 to 12,
(Meth) acrylate oligomer having a weight average molecular weight (Mw) of about 500 to 10,000, a (meth) acrylate oligomer having a (meth) acrylate monomer and a urethane group, Gt; and < RTI ID = 0.0 > a < / RTI > initiator. 16. The method of claim 15,
Wherein the metal alkoxide comprises any one selected from the group consisting of compounds represented by Chemical Formulas 1 to 3 or a mixture of two or more thereof:
[Chemical Formula 1]
R1 _x M1 (OR2) _4-x
(2)
R1 is selected from the group _{consisting of} M2 (OR2) _3-y
(3)
_{R1 z Nb (OR2) 5-} z
R1 is any one selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, a vinyl group, an allyl group, a (meth) acryloxy group, an epoxy group, and an amino group; M is a metal selected from the group consisting of Si, Ti, Zr, Ge, and Sn; M2 is a metal selected from the group consisting of Al, In, and Sb; x is an integer of 0 or more and 3 or less; y is An integer of 0 or more and 2 or less, and z is an integer of 0 or more and 4 or less. The method according to claim 1,
A first optical layer disposed on an upper surface of the first transparent film and having a first light diffusion pattern formed on a surface thereof; And
And a second optical layer disposed on a lower surface of the second transparent film and having a second light diffusion pattern formed on the surface thereof. A light emitting element for generating blue light; And a diffusion sheet for diffusing the blue light and converting at least part of the blue light into green light or red light,
Wherein the diffusion sheet
A light conversion layer comprising a light transmitting resin and a nano emitter dispersed in the resin;
First and second transparent films spaced apart from each other with the light conversion layer interposed therebetween;
A first barrier layer disposed between the photo-conversion layer and the first transparent film; And
And a second barrier layer disposed between the photo-conversion layer and the second transparent film,
Wherein the light transmitting resin is formed by curing a polymer composition comprising a multifunctional photocurable oligomer, a monofunctional photocurable monomer, a multifunctional photocurable monomer, and a photocuring initiator. 19. The method of claim 18,
And a light guide plate disposed adjacent to the light emitting element and below the diffusion sheet and guiding the blue light generated from the light emitting element toward the diffusion sheet. 19. The method of claim 18,
Wherein the light emitting device includes a plurality of blue light emitting diodes arranged under the diffusion sheet. 19. The method of claim 18,
The multifunctional photocurable oligomer may be at least one selected from the group consisting of urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, acryl (meth) acrylate, polybutadiene And at least one oligomer selected from the group consisting of melamine (meth) acrylate,
The monofunctional photocurable monomer may be selected from the group consisting of isobonyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, benzyl (meth) acrylate, ) Acrylate, n-hexyl (meth) acrylate, adamantyl acrylate, and cyclopentyl acrylate,
The multifunctional photocurable monomer may be at least one selected from the group consisting of isobonyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, benzyl (meth) acrylate, ) Acrylate, n-hexyl (meth) acrylate, adamantyl acrylate, and cyclopentyl acrylate. 22. The method of claim 21,
The content (C1) of the multifunctional photocurable oligomer, the content (C2) of the monofunctional photocurable monomer, the content (C3) of the multifunctional photocurable monomer and the content (C4) of the photocurable initiator satisfy the following formulas 2 < / RTI >:< RTI ID = 0.0 >
[Equation 1]

[Equation 2]

19. The method of claim 18,
Wherein the nano emitter comprises a red quantum dot or a green quantum dot,
Wherein the nano emitter is contained in an amount of 0.5 wt.% To 3.0 wt.% Based on the total weight of the light conversion layer.

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