KR20090045538A - Diffusion plate, backlight device comprising the same, and liquid crystal display device - Google Patents

Abstract

The present invention relates to a light diffusing plate comprising a base layer and a light collecting layer formed on at least one of upper and lower sides of the base layer, wherein the light diffusing plate includes a low refractive layer between the base layer and the light collecting layer. . According to the present invention, since the path of the light passing through the substrate layer is changed by the low refractive layer to increase the light diffusion and condensing effect, the front uniformity and brightness is improved, and the light diffusion is easy for the coating process. The plate can be provided.

Light diffuser, Direct backlight, Low refractive layer, Condensing layer

Description

Diffusion Plate, Backlight Device Comprising the Same, And Liquid Crystal Display Device}

The present invention relates to a light diffusion plate, a backlight device having the same, and a liquid crystal display device.

Since the liquid crystal display (LCD) does not have a shape of a self-luminous element, the LCD includes a device called a backlight unit (BLU) on its rear surface. The backlight unit can be largely divided into a direct type mainly applied to a large machine such as a television and an edge type mainly applied to a small machine such as a monitor and a notebook. In particular, in the case of the direct type, it is difficult to obtain uniform luminance on the front surface because a large number of light sources having a bar shape (CCFL) or a dot shape (LED) are used. Accordingly, the diffusion plate included in the backlight unit uniformly distributes the light over the entire liquid crystal display panel and includes one or more diffusion films and a prism sheet on the upper side of the diffusion plate, thereby changing the light propagation path in the vertical direction. It serves to condense to the front.

As described above, in the configuration of the backlight unit for improving the front uniformity and the brightness, it is inevitable to use one or more diffusion films and prism sheets in addition to the diffusion plate. However, this method not only has a problem that it is difficult to achieve low cost and high thickness of the backlight unit, but also shows a limitation in the case where high brightness of a 32-inch or larger liquid crystal display is required, in which the number of lamps is reduced and the demand is increasing. There is this.

In order to solve this problem, it is possible to improve the uniformity and brightness of the front surface by increasing the light diffusion and condensing effects by forming a prism pattern directly on the upper side of the diffusion plate, but improves the uniformity and brightness of the front surface without the air layer. There is a limit to letting.

In order to improve the above problems, it can be considered a method of manufacturing integrally by a method of including an air layer using a partition between the diffusion plate and the prism pattern, but the method is expensive to manufacture like foaming method This happens.

The present invention is to solve the above problems, by embedding a low refractive layer between the base layer and the light collecting layer so that the low refractive layer to replace the role of the air layer, thereby increasing the diffusion and light collecting effect of the light emitted from the light source It is an object of the present invention to improve the uniformity and brightness of the front surface, and to solve the difficulty of manufacturing an air layer, thereby providing a light diffusion plate that can achieve a thin thickness.

The present invention for achieving the above object is a light diffusing plate comprising a base layer and a light collecting layer formed on at least one side of the upper and lower sides of the base layer, the refractive index is between 1.29 ~ Provided is a light diffusing plate comprising a low refractive index layer of 1.49.

The present invention also provides a light diffusion plate comprising a base layer and a functional layer formed on at least one side of an upper side and a lower side of the base layer, and including a light collecting layer on at least one side of an upper side and a lower side of the functional layer. A light diffusion plate including a low refractive index layer having a refractive index of 1.29 to 1.49 is provided between the functional layer and the light collecting layer.

In addition, the low refractive layer provides a light diffusing plate, characterized in that containing a fluorine or silicon compound.

In addition, the refractive index of the low refractive index layer is less than 0.01 or less than the refractive index of the substrate layer or functional layer in contact with the low refractive index layer, the light diffusion plate, characterized in that less than 0.05 or less than the refractive index of the light collecting layer in contact with the low refractive layer. To provide.

In addition, the low refractive index layer is provided with a light diffusion plate, characterized in that 0.1 ~ 100㎛.

In addition, the base resin of the base layer or functional layer provides a light diffusing plate, characterized in that it contains at least one or more of acrylic, styrene-acrylic, styrene-based, styrene-acrylonitrile-based and polycarbonate-based structures.

In addition, the light collecting layer has a prism shape consisting of a pitch of 30 to 300㎛, a height of 30 to 150㎛, and an angle of the vertex of 60 to 120 ° or a pitch of 50 to 400 Μm, height provides a light diffusion plate, characterized in that the lenticular shape consisting of 30 ~ 200㎛.

In addition, at least one of the substrate layer, the functional layer, the low refractive layer and the light collecting layer provides a light diffusion plate comprising at least one of the group consisting of organic particles, inorganic particles and hollow particles.

The present invention also provides a backlight device having the light diffusing plate described above.

The present invention also provides a liquid crystal display device having the above-described backlight device.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings and examples. The following description is a description of some embodiments of the present invention, and the present invention is not limited by the following detailed description, and the scope of the present invention is determined by the matters described in the claims.

Light diffusing plate according to an embodiment of the present invention is characterized in that it comprises a low refractive index layer having a refractive index of 1.29 ~ 1.49 between the base layer and the light collecting layer.

1A to 1E illustrate a light diffusing plate according to an embodiment of the present invention.

1A and 1B, a light collecting layer 4 having a prism pattern is provided on at least one of an upper side and a lower side of the base layer 1, and a low refractive layer (B) between the base layer 1 and the light collecting layer 4 is provided. 3 shows a light diffusing plate formed. In FIG. 1C and FIG. 1D, a light collecting layer 4 having a lenticular pattern is provided on at least one side of an upper side and a lower side of the base layer 1, and a low refractive layer between the base layer 1 and the light collecting layer 4 is formed. 3 shows a light diffusing plate formed. In FIG. 1E, a light collecting layer 4 having a prism pattern on one side and a lenticular pattern on one side of the base layer 1 is provided between the base layer 1 and the light collecting layer 4. The light diffusion plate in which the low refractive layer 3 was formed is shown. Meanwhile, although not shown, a diffusion sheet, a light luminance polarizing sheet, and the like may be further included on the emission surface of the light diffusion plate, and all are included in the present invention. The light diffusion plate of the present invention also includes a light diffusion sheet. Here, the light diffusing agents such as the organic particles 11, the inorganic particles 21 and the hollow particles 31 may be selectively added or subtracted as necessary as an optional configuration.

The light diffusing plate according to the present invention includes a low refractive layer 3 between the base layer 1 and the light collecting layer 4 on at least one of the upper side and the lower side of the base layer 1, thereby spreading and collecting light. The effect can be increased to achieve high brightness as well as front uniformity.

This is an application of Snell's Law. When the light emitted from the light source passes through the base layer and then enters the low refractive layer, the refractive index of the low refractive layer is lower than that of the base layer. Refraction allows the light to spread evenly across the front of the liquid crystal panel. In addition, when light evenly spread on the front surface of the panel is incident on the light collecting layer, the light collecting layer having a high refractive index serves to reduce the divergence angle of the transmitted light, thereby achieving high brightness.

At this time, the refractive index of the low refractive index layer 3 is preferably 1.29 ~ 1.49. If the refractive index layer is less than 1.29, the manufacturing process is very difficult, and the price is increased. If the refractive index layer is more than 1.49, the light diffusion function is insufficient.

In addition, it is preferable that the refractive index of the low refractive layer 3 is smaller than 0.01 by the refractive index of the base layer 1 or the functional layer 2 in contact. When the refractive index of the low refractive index layer 3 is not smaller than 0.01 of the refractive index of the base layer 1 in contact with the light, the light may not be refracted and only the light transmitting property may cause a problem that light may not be diffused.

The refractive index of the low refractive layer 3 is preferably 0.05 or less smaller than the refractive index of the light collecting layer 4 in contact. In the above range, when the light passing through the low refractive layer 3 passes through the light collecting layer, the divergence angle may be narrowed to improve the light collecting characteristics.

It is preferable that the thickness of the said low refractive layer 3 is 0.01-100 micrometers. When the thickness of the low refractive index layer 3 is less than 0.01 μm, the light diffusing function may not be sufficiently exhibited, and when the thickness of the low refractive layer 3 is greater than 100 μm, luminance may decrease due to a decrease in transmittance.

The low refractive index layer 3 may be formed by coating on one side of the substrate layer 1 with a coating solution using a thermal curing or ultraviolet curing method, or may be prepared through an extrusion process.

The low refractive layer 3 according to the present invention comprises a silicon or fluorine compound. The silicon or fluorine compound is preferably one or more selected from the group consisting of silane, siloxane and fluorine materials. In addition, the low refractive index layer 3 is preferably made of 1 to 50 parts by weight of silicon or fluorine compound relative to the coating liquid and 100 weight of the coating liquid. When the content of the silicon or fluorine compound is less than 1 part by weight, the light diffusing effect is not exhibited because the low refractive index is not exhibited. When the content of the silicon or fluorine compound is greater than 50 parts by weight, the transmittance of light is reduced, thereby reducing the luminance.

Examples of the silane-based material include (meth) acryloxy alkyltrimethoxysilane, (meth) acryloxyalkyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxy Silane, silyl (meth) acrylate, (meth) acryloxyalkyltrichlorosilane, phenyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, glycid Oxyalkyltrimethoxysilane, glycidoxyalkyltriethoxysilane, glycidoxyalkyltrichlorosilane, perfluoroalkyltrialkoxysilane, perfluoromethylalkyltrialkoxysilane, perfluoroalkyltrichlorosilane and the like. Can be mentioned.

Examples of the siloxane-based material include polysiloxanes containing special functional groups (Tego, Phobe 1500N), low molecular weight modified polysiloxanes (Tego, HL 100), polyether siloxane copolymers (Tego, Glide 432, 435, 440, 450) , Polyether modified polydimethylsiloxane (BYK Chemie Co., Ltd. BYK-330, BYK-301, BYK-335), polyether modified polydimethylsiloxane (BYK Chemie Co., Ltd. BYK-302, BYK-331, BYK-332) and the like. have.

Examples of the fluorine-based material include fluoro aliphatic polymers (3M, FC-4430), fluoropolymers (3M, ECC-1000), methylnonafluoroisobutyl ether (3M, EGC-1000), and tetrafluoro Roethane, pentafluoroethane, perfluoroethane, pentafluoropropane, hexafluoropropane, heptafluoropropane, perfluoropropane, hexafluorobutane, heptafluorobutane, octafluorobutane, nonafluoro Robutane, perfluorobutane, heptafluoropentane, octafluoropentane, nonafluoropentane, decafluoropentane, undecafluoropentane, perfluoropentane, octafluorohexane, nonafluorohexane, deca Fluorohexane, undecafluorohexane, dodecafluorohexane, tridecafluorohexane, perfluorohexane, 3-chloro-1,1,1-trifluoropropane, 1,1,1,3, 3,5,5,5-octafluoropentane, 4-trifluoromethyl-1,1,1,2,2,3,3,5,5,5-deca Luoropentane, 4-trifluoromethyl-1,1,1,2,2,5,5,5-octafluoropentane, 4-trifluoromethyl-1,1,1,2,2,3 , 5,5,5-nonafluoropentane, 1,1,1,2,3,4,4,5,5,5-decafluoropentane, 1,1,1,2,2,3,3 , 4,4,5,6-undecafluorohexane, 1,1,2,2,3,3,4,4-octafluorobutane, 1,1,1,2,2,3,3, 4,4-nonafluorobutane-4-methyl ether, 1,1,1,2,2,3,4,4,4-nonafluoroisobutane-3-methyl ether, 1,1,1,2 , 2,3,3,4,4-nonafluorobutane-4-ethyl ether, 1,1,1,2,2,3,4,4,4-nonafluoroisobutane-3-ethyl ether, 1,1,2,2,3,3,4,5-octafluorocyclopentane, pentafluoroethane, dichloro-trifluoroethane, trichloro-tetrafluoropropane, dichloro-pentafluoropropane, dichloro Tetrafluoropropane, chloro-pentafluoropropane, chloro-tetrafluoropropane, chloro-hexafluoropropane, pentachloro-difluoropropane, tetrachloro-tri Luoropropane, trichloro-trifluoropropane, pentafluoropropane, nonafluorobutylethylene (PFBET), 2,2,3,3-tetrafluoropropylmethacrylate (TFPM), 2,2,3 , 4,4,4-hexafluorobutylacrylate (HFBA), 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFBM) and 2,2,3,3,4, 4,5,5-octafluoropentane acrylate (OFPA) etc. are mentioned.

As the base resin of the base layer 1, any material used in the art may be used. Preferably, all of the resins are inexpensive, have high light transmittance, and exhibit excellent durability, and particularly include acrylic resins, styrene-acrylic copolymer resins, styrene resins, styrene-acrylonitrile copolymer resins, and the like. It is good that it is 1 or more types chosen from polycarbonate resin.

In particular, the acrylic resin in the present invention is alkyl methacrylate such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate; Alkyl acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate; Methacrylic acid cycloalkyl esters such as cyclohexyl methacrylate, 2-methylcyclohexyl methacrylate and dicyclopentanyl methacrylate; Acrylic acid cycloalkyl esters such as cyclohexyl acrylate and 2-methylcyclohexyl acrylate; Methacrylic acid aryl esters such as phenyl methacrylate and benzyl methacrylate; It is preferable that it is any one homopolymer or their copolymers chosen from acrylic acid aryl esters, such as phenyl acrylate and benzyl acrylate.

The styrene-acrylic copolymer resin may include at least one selected from alkyl methacrylate, alkyl acrylate, cycloalkyl methacrylate, cycloalkyl acrylate, aryl methacrylate and aryl acrylate, and styrene and α-. It is preferably at least one copolymer selected from methyl styrene, m-methyl styrene, p-methyl styrene, and p-methoxy styrene.

In addition, the styrene resin is preferably any one homopolymer selected from styrene, α-methyl styrene, m-methyl styrene, p-methyl styrene, and p-methoxy styrene or a copolymer thereof.

Further, the styrene-acrylonitrile copolymer resin is preferably a copolymer of an acrylonitrile monomer with at least one selected from styrene, α-methylstyrene, m-methylstyrene, p-methylstyrene, and p-methoxystyrene. Do.

In addition, the polycarbonate resin is a linear and branched aromatic polycarbonate homopolymer, a polyester copolymer or a mixture of one or more thereof prepared by reacting dihydroxy phenol with phosgene or by reaction of dihydroxy phenol with a carbonate precursor. The group consisting of is preferred.

The thickness of the base layer 1 is not limited but is preferably in the range of about 0.1 to 4 mm. By having the thickness of the base material layer 1 to some extent, the rigidity required as a light-diffusion plate is acquired, and the transmittance | permeability can be adjusted.

The condensing layer 4 serves to condense the light diffused from the low refractive index layer 3 to improve brightness, and in particular, a structure having a prism shape or a lenticular shape is preferable. The prism shape of the condensing layer 4 is preferable. Silver pitch is 30 ~ 300um, height is 30 ~ 150um, vertex angle is 60 ~ 120 degree, and lenticular shape is pitch is 50 ~ 400um and height is When it is made of 30 ~ 200um has the highest brightness and ease of manufacture.

The light collecting layer 4 may be manufactured and used by various methods such as extrusion molding, vacuum molding, hot press molding, coextrusion molding, film lamination, solvent bonding, surface coating, ultraviolet curing, and thermal curing. .

In another embodiment, the present invention includes a functional layer 2 on at least one of the base layer 1 and an upper side and a lower side of the base layer 1, and the upper side or the lower side of the functional layer 2. In a light diffusing plate including a light collecting layer 4 on one side, a light diffusing plate including a low refractive layer 3 is provided between the functional layer 2 and the light collecting layer 4.

2A to 2B illustrate an example of a light diffusion plate according to another embodiment of the present invention. In FIG. 2A, the functional layer 2 is provided above and below the substrate layer 1, and the light diffusing plate includes a prism-shaped light collecting layer 4 on the upper layer of the functional layer 2. The light diffusing plate is provided with a low refractive index layer 3 between the layer 2 and the light collecting layer 4. In FIG. 2B, the functional layer 2 is provided above and below the base layer 1, and in the light diffusion plate including the lenticular light collecting layer 4 on the upper layer of the functional layer 2, the functional layer 2 is provided. The light diffusing plate is provided with a low refractive index layer 3 between the layer 2 and the light collecting layer 4.

As the base resin of the functional layer 2, the same resin as those listed as the base resin of the base layer 1 may be used, or different resins may be used.

The thickness of the functional layer 2 is not particularly limited, but is preferably in the range of 0.05 to 1.5 mm. In the case where the thickness of the functional layer 2 is within the above range, durability can be more effectively obtained, and light diffusion rate and haze can be achieved.

In the light diffusing plate according to the present invention, any one of the base layer 1, the functional layer 2, the low refractive layer 3, and the light collecting layer 4 may be organic particles 11, inorganic particles 21, hollow. Light diffusing agents, such as the soluble particle 31, can be applied. As the light diffusing agent, any material used in the art may be applied, and it is particularly preferable to use the organic particles 11, the inorganic particles 21, and / or the hollow particles 31 alone or in combination. .

Examples of the organic particles 11 and / or inorganic particles 21 include silicon-based, acrylic-based, styrene-based, methyl methacrylate-styrene copolymers, polycarbonate-based, olefin-based crosslinked or uncrosslinked fine particles, silica, talc, calcium carbonate, Barium sulfate, titanium dioxide (TiO ₂ ) and the like can be used.

The hollow particles 31 contain air or vacuum and are preferably made of a silicon compound. For example, siloxane compounds such as silica, glass, and silicon, and chlorosilanes, alkoxy silanes, amino silanes, and fluorine alkyl silanes. There are silane compounds, and preferably hollow particles made of silica or glass. The hollow particles 31 may not only exhibit high light diffusivity and total light transmittance in a small amount, but may also improve high hardness and heat resistance problems, which are durability problems of the backlight.

The size of the light diffusing agent is preferably in the range of 0.1 to 50㎛ that can increase the diffusion effect while reducing the content of the light diffusing agent, the amount of use is preferably 0.01 to 40 parts by weight relative to 100 weight of the base resin, more preferably 0.1-10 weight part is good. When the content of the light diffusing agent is less than 0.01 part by weight, the incident light cannot be diffused, and when the content of the light diffusing agent is more than 40 parts by weight, the transmittance of light is lowered and the dispersibility of the light diffusing agent is lowered, thereby not exerting high brightness.

In addition, the substrate layer, the functional layer, the low refractive layer, and the light collecting layer may further include additives such as ultraviolet light absorbers, light stabilizers, antioxidants, antistatic agents, and optical brighteners.

The light diffusion plate according to the present invention can be preferably applied to the backlight device. The backlight device is not particularly limited, and any backlight device known in the art may be applied and included in the present invention. The light source of the backlight device may be used without limitation, such as a hot cathode tube, a cold cathode tube, a light emitting diode (LED), an organic electroluminescent element (OLED), and the like.

The present invention also provides a liquid crystal display device having a backlight device having the light diffusing plate of the present invention. In particular, it is applied to a reflective, transmissive, transflective LCD or liquid crystal display device of various driving methods such as TN type, STN type, OCB type, HAN type, VA type, IPS type, etc. using the backlight device equipped with the light diffusion plate. It can be used preferably. The configuration of the liquid crystal display device is well known in the art, and thus description thereof is omitted.

The light diffusing plate according to the present invention includes a low refractive layer between the base layer and the light collecting layer, so that the light passing through the base layer changes the path so that the light diffusion and condensing effects are increased, thereby improving front uniformity and brightness. Can and coating process is easy.

Such a light diffusion plate of the present invention can be widely applied to lighting covers, various signages, and light diffusion plates for backlights of liquid crystal displays.

Hereinafter, the following examples are described to help practice the present invention.

(Example 1)

The light diffusing plate was manufactured in a multilayer structure consisting of a base layer, a functional layer formed on the upper side and a lower side of the base layer, a low refractive layer formed on the upper side of the functional layer, and a light collecting layer formed on the upper side of the low refractive layer.

A base layer of 1.9 mm was formed using 100 parts by weight of polystyrene (PS, refractive index: 1.59) as the base resin, 2 parts by weight of 10 μm organic particles (PMMA), and 0.5 parts by weight of 2 μm silicon-based particles.

A mixture of 10 parts by weight of 10 μm organic particles (PMMA) and 100 parts by weight of a polystyrene-methyl methacrylate copolymer (MS200, refractive index: 1.57), which is a base resin, was molded to a thickness of 0.05 mm on both sides of the substrate layer, respectively. Layered.

On the upper side of the functional layer, a fluorine-based low refractive layer (refractive index: 1.40) having a thickness of 30 μm was formed.

The light diffusing plate was manufactured by forming a prism-shaped light collecting layer (refractive index: 1.57, vertex angle: 90 degrees, pitch: 135 µm, and height: 68 µm) above the low refractive layer.

(Example 2)

A light diffusing plate was manufactured in the same manner as in Example 1 except that the refractive index of the low refractive layer was set to 1.45.

(Example 3)

A light diffusing plate was manufactured in the same manner as in Example 1 except that 10 μm organic particles (PMMA) were not used in the preparation of the functional layer.

(Example 4)

A light diffusing plate was manufactured in the same manner as in Example 1 except that the thickness of the low refractive layer was 10 μm.

(Example 5)

A light diffusing plate was manufactured in the same manner as in Example 1, except that polymethyl methacrylate (PMMA, refractive index: 1.49) was used as the base resin of the functional layer.

(Example 6)

A light diffusing plate was manufactured in the same manner as in Example 1 except that the light condensing layer (refractive index: 1.57, height: 100 μm, pitch: 270 μm) on the low refractive layer was formed in a lenticular shape.

(Example 7)

A light diffusing plate was manufactured in the same manner as in Example 1 except that the functional layer was not prepared.

(Comparative Example 1)

A base layer of 1.9 mm is formed using 100 parts by weight of polystyrene (PS, refractive index: 1.59) which is a base resin, 2 parts by weight of 10 μm organic particles (PMMA), and 0.5 parts by weight of 2 μm silicon-based particles.

A mixture of 100 parts by weight of a polystyrene-methyl methacrylate copolymer (MS200, refractive index: 1.57) and 10 parts by weight of 10 μm organic particles (PMMA), which is a base resin, was formed on both sides of the substrate layer, respectively, to form a functional layer having a thickness of 0.05 mm. To prepare a light diffusion plate.

(Comparative Example 2)

A light diffusion plate was manufactured in the same manner as in Example 1, except that the light condensing layer was formed directly on the functional layer without forming a low refractive layer.

Table 1

Base layer (parts by weight) Functional layer (parts by weight) Low refractive layer Condensing layer Suzy Diffuser Suzy Diffuser Refractive index Thickness (um) shape Refractive index Pitch (um) Organic particles Inorganic particles Organic particles Kinds Kinds content Kinds content Kinds Kinds content Example 1 PS PMMA 2 silicon 0.5 MS PMMA 10 1.40 30 prism 1.57 135 Example 2 PS PMMA 2 silicon 0.5 MS PMMA 10 1.45 30 prism 1.57 135 Example 3 PS PMMA 2 silicon 0.5 MS - - 1.40 30 prism 1.57 135 Example 4 PS PMMA 2 silicon 0.5 MS PMMA 10 1.40 10 prism 1.57 135 Example 5 PS PMMA 2 silicon 0.5 PMMA PMMA 10 1.40 30 prism 1.57 135 Example 6 PS PMMA 2 silicon 0.5 MS PMMA 10 1.40 30 Lenticular 1.57 270 Example 7 PS PMMA 2 silicon 0.5 - - - 1.40 30 prism 1.57 135 Comparative Example 1 PS PMMA 2 silicon 0.5 MS PMMA 10 - - - - - Comparative Example 2 PS PMMA 2 silicon 0.5 MS PMMA 10 - - prism 1.57 135

The optical properties of the light diffusing plates of Examples and Comparative Examples were measured using an optical simulation equipment (Optical Research Associates, Light Tools), the results are shown in Table 2 below.

Table 2

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Measured value (cd / m ² ) 6677.8 6590 6724.8 6589.4 6611.9 6244 6738.2 5931 6383.2 % Improvement compared to Comparative Example 1 12.6 11.1 13.4 11.1 11.5 5.3 13.6 - 6.6 Measures(%) 78.7 76.8 77.6 78.2 79.2 82.4 77.4 73.0 73.5 % Improvement compared to Comparative Example 1 7.8 5.2 6.3 7.1 8.5 12.9 6.0 - 0.7

As shown in Table 2 above,

The light diffusing plates of Examples 1 to 7 according to the present invention include the light diffusing plates of Comparative Example 1, which does not include the low refractive layer and the light collecting layer, and Comparative Example 2, which does not include the low refractive layer between the functional layer and the light collecting layer. In comparison, the front uniformity and brightness were improved. This is because the light passing through the substrate layer changes the path due to the low refractive index layer to increase the light diffusion and condensing effects.

The low refractive index layer of the present invention is also easy to manufacture because it can be manufactured using a thermal curing or ultraviolet curing method after the coating or through an extrusion process. This facilitates the manufacture of a light diffusion plate having improved front uniformity and brightness as compared with a conventional light diffusion plate.

1A to 1E are side cross-sectional views of a light diffusion plate according to an embodiment of the present invention,

2A to 2B are side cross-sectional views of a light diffusing plate according to another embodiment of the present invention.

** Description of the main symbols in the drawings **

1: base material layer 2: functional layer

3: low refractive layer 4: light collecting layer

11: organic particles 21: inorganic particles

31: hollow particles

Claims (11)

In the light diffusion plate comprising a base material layer and a light collecting layer formed on at least one of the upper side and the lower side of the base layer, And a low refractive index layer having a refractive index of 1.29 to 1.49 between the base layer and the light collecting layer. In the light diffusion plate comprising a base material layer and a functional layer formed on at least one side of the upper and lower sides of the base layer, and comprising a light collecting layer on at least one of the upper side and the lower side of the functional layer, And a low refractive index layer having a refractive index of 1.29 to 1.49 between the functional layer and the light collecting layer. The light diffusing plate according to claim 1 or 2, wherein the low refractive index layer contains a fluorine or silicon compound. The refractive index of claim 1 or 2, wherein the refractive index of the low refractive index layer is less than 0.01 or less than the refractive index of the base layer or functional layer in contact with the low refractive index layer, 0.05 or more than the refractive index of the light collecting layer in contact with the low refractive layer Light diffusion plate, characterized in that small. The light diffusing plate according to claim 1 or 2, wherein the low refractive index layer has a thickness of 0.1 to 100 µm. The light diffusing plate of claim 1 or 2, wherein the low refractive index layer is manufactured by a thermal curing method, an ultraviolet curing method, or an extrusion process. The base resin of claim 1 or 2, wherein the base resin of the base layer or the functional layer contains at least one or more of acrylic, styrene-acrylic, styrene, styrene-acrylonitrile and polycarbonate structures. Light diffusion plate. According to claim 1 or 2, wherein the light collecting layer has a pitch of 30 ~ 300㎛, the height (height) 30 ~ 150㎛, the angle of the vertex of the prism shape consisting of 60 ~ 120 ° or Light diffusion plate, characterized in that the lenticular shape consisting of 50 ~ 400㎛ pitch, 30 ~ 200㎛ pitch. The method of claim 1 or 2, wherein at least one of the base layer, the functional layer, the low refractive layer and the light collecting layer comprises at least one of the group consisting of organic particles, inorganic particles and hollow particles. Light diffusion plate. A backlight device comprising the light diffusing plate of claim 1. A liquid crystal display device comprising the backlight device of claim 10.

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