KR20110067408A - Light diffusion plate, backlight unit having the same, liquid crystal display device and lighting device - Google Patents

Abstract

PURPOSE: A light diffusion plate, a backlight unit including the same, a liquid crystal display, and a lighting device are provided to obtain luminance and uniformity by vertically arranging a protrusion of a first base material layer and a protrusion of a second material layer to each other. CONSTITUTION: A light incidence surface(112) is formed to receive incident light from a light source through a bottom surface. A cross section of an upper side has an elliptic shape. Protrusions formed in a lateral direction are continuously formed in a longitudinal direction. Each of first and second base material layers includes a light emission surface(113) through which the light is emitted to the outside of the protrusion. A protrusion of a first base material layer(110) and a protrusion of a second base material layer are arranged perpendicularly to each other.

Description

Light Diffusion Plate, Backlight Unit, Liquid Crystal Display and Lighting Device {Light Diffusion Plate, Backlight Unit Having the Same, Liquid Crystal Display Device And Lighting Device}

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

In the case of a liquid crystal display, since it is not a self-light emitting device, a backlight unit is provided on a rear surface of the liquid crystal display. Such a backlight unit may be broadly classified into a direct type that is mainly applied to a large size such as a TV and a digital information display (DID), and an edge type that is mainly applied to a small size such as a monitor and a notebook.

In the case of the direct type method, it is difficult to obtain uniform luminance on the front surface because a plurality of light sources having a bar shape (Cold Cathode Fluorescent Lamp, External Electrode Fluorescent Lighting) or dot shape (Light Emitting Diode) are used. Therefore, light is uniformly distributed over the entire liquid crystal display using a light diffusing plate, and then a diffuser sheet, a prism sheet, a micro lens sheet or a light luminance polarizing sheet is arranged on the uppermost side of the light diffusing plate above, if necessary. This is solved by uniformly emitting or condensing light to the front. However, such a backlight unit still faces a problem of improving the uniformity of luminance.

An object of the present invention is to provide a light diffusion plate having excellent brightness and uniformity, a backlight unit having the same, a liquid crystal display, and an illumination device.

The light diffusing plate according to the present invention for achieving the above object is provided with a light incidence surface in which light is incident from the light source on the bottom surface, the projection is formed in the longitudinal direction of the elliptical shape in the longitudinal direction is formed continuously in the longitudinal direction The outer side of the protrusion includes a first and a second substrate layer including a light exit surface for emitting light, and a second substrate layer is formed on the upper surface of the first substrate layer, the first substrate The projections of the layer and the projections of the second substrate layer are characterized in that they are arranged to be perpendicular to each other.

The elliptical protrusions of the first and second base layers preferably have a short radius a, a long radius b, a height h, and a pitch p satisfying the following equation.

&Quot; (1) "

1000 μm ≥ 2b> 2a> p> h ≥100 μm

The short radius a of the elliptical protrusions of the first and second base layers is 125 µm to 250 µm, the long radius b is 250 µm to 500 µm, the height h is 100 µm to 300 µm, and the pitch p is 200 µm to 300 µm. Is preferably.

Roughness may be further formed on at least one of the light incident surface and the light exit surface of the first and second substrate layers.

A functional layer may be further provided on at least one of the light incident surface or the light exit surface of the first and second substrate layers, and at least one of the base layer and the functional layer may be formed of a transparent resin and a light diffusing agent. It may be. At least one of the base layer and the functional layer may include at least one selected from among ultraviolet absorbers, heat stabilizers, antioxidants, antistatic agents, fluorescent brighteners, and release agents.

The backlight unit according to the invention is characterized in that it comprises the light diffusion plate according to the invention described above.

Lighting device according to the invention is characterized in that it comprises a light diffusing plate according to the invention described above.

In the light diffusion plate according to the present invention, the projection of the first substrate layer and the projection of the second substrate layer are arranged when the first substrate layer and the second substrate layer are arranged in a longitudinal direction, and the projections formed in the longitudinal direction are elongated in the longitudinal direction. By arranging the vertically perpendicular to each other, it is possible to obtain excellent characteristics of brightness and uniformity. Accordingly, the light diffusion plate may be usefully applied to a backlight unit, a liquid crystal display, and an illumination device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

1 is an exploded perspective view of a light diffusion plate according to an embodiment of the present invention, Figure 2 is a cross-sectional view of the substrate layer shown in FIG.

As shown in FIGS. 1 and 2, the light diffusion plate 100 includes a first substrate layer 110 and a second substrate layer 110a. In this case, the first base layer 110 and the second base layer 110a have the same configuration. Therefore, in the following description, except for a special case, the configuration of the first base layer will be described.

The first and second base layers 110 and 110a are both provided with a light incident surface 112 through which light is incident from a light source on a bottom surface thereof, and an upper surface of the first and second base layers 110 and 110a has an elliptical shape having a longitudinal cross section. It is formed continuously, the outer side of the protrusion 111 is made to include a light exit surface 113, the light is emitted.

According to the present invention, the second substrate layer 110a is formed on the upper surface of the first substrate layer 110, and the protrusions 111 and the projections of the second substrate layer 110a of the first substrate layer 110 are formed. 111a is characterized in that it is arranged to be perpendicular to each other. As such, when the protrusions 111 of the first base layer 110 and the protrusions 111a of the second base layer 110a are arranged to be perpendicular to each other, luminance and uniformity are excellent.

The thickness of the first and second substrate layers 110 and 110a is not limited, but may be 0.1 mm to 4.0 mm. When the thicknesses of the first and second substrate layers 110 and 110a are less than 0.1 mm, the light diffusion plate 100 may have difficulty in maintaining a constant rigidity. Therefore, the first and second base layers 110 and 110a have a certain thickness, so that the necessary rigidity as the light diffusion plate 100 is obtained and the optical auxiliary material must be protected from heat generated from the light source. . When the thickness of the first and second substrate layers 110 and 110a exceeds 4 mm, the amount of raw and subsidiary materials increases, thereby increasing the manufacturing cost of the light diffusion plate 100. In addition, as the thickness increases, the weight of the direct backlight unit increases.

The first and second base layers 110 and 110a may include a transparent resin and a light diffusing agent having a diffusion function.

The transparent resin is at least one selected from an acrylic resin, a styrene-acrylic copolymer resin, a styrene resin, a styrene-acrylonitrile resin, and a polycarbonate resin, which is inexpensive and has high light transmittance and shows excellent durability. desirable.

The acrylic resin may be a methacrylic acid alkyl ester such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, or 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 2 or more types of copolymers chosen from acrylic acid aryl ester, such as phenyl acrylate and benzyl acrylate.

The styrene-acrylic copolymer resin may include at least one selected from methacrylic acid alkyl ester, acrylic acid alkyl ester, methacrylic acid cycloalkyl ester, acrylic acid cycloalkyl ester, methacrylic acid aryl ester and acrylic acid aryl ester, and styrene and α-methyl. Preference is given to at least one copolymer selected from styrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene.

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

Polycarbonate resins are also groups of linear and branched aromatic polycarbonate homopolymers, polyester copolymers, or mixtures of one or more thereof, prepared by reacting dihydroxy phenol with phosgene or by reaction of dihydroxy phenol with a carbonate precursor. This is preferred.

The light diffusing agent is preferably used alone or in combination of one or more of organic particles and inorganic particles. For example, silicone-based, acrylic, styrene-based, methyl methacrylate / styrene copolymer-based, polycarbonate-based, butyl acrylate, olefin-based crosslinked or uncrosslinked fine particles, silica, talc, calcium carbonate, barium sulfate, titanium dioxide (TiO ₂ ) and the like can be used. In addition to the use of a material, the light diffusing agent includes all components applied for light diffusion, such as forming pores in the first and second base layers 110 and 110a.

The size of the light diffusing agent is suitably 0.5 μm to 50 μm. Preferably, the light diffusing agent is suitably 0.8 μm to 35 μm. When the size of the light diffusing agent is less than 0.5 μm, there is a problem in that the dispersibility with the transparent resin is poor. If the size of the light diffusing agent exceeds 50㎛ has a disadvantage in that the light diffusion performance is reduced compared to the same amount of light can not diffuse.

The light diffusing agent may be used in an amount of about 0.001 parts by weight to 5 parts by weight based on 100 parts by weight of the transparent resin used in the first and second base layers 110 and 110a, and more preferably 0.01 part by weight to 2 parts by weight. good. When the light diffusing agent is less than 0.01 part by weight, the incident light cannot be diffused, and when the light diffusing agent is more than 2 parts by weight, the transmittance of the light is lowered, thereby lowering the luminance.

The first and second substrate layers 110 and 110a may further include at least one selected from ultraviolet absorbers, heat stabilizers, antioxidants, antistatic agents, fluorescent brighteners, and release agents known in the art.

The ultraviolet absorbers include benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, and formamidine ultraviolet absorbers, and these may be used alone or in combination of two or more. The content of the ultraviolet absorbent is not limited, but is 0.001 to 5 parts by weight, preferably 0.01 to 2 parts by weight based on 100 parts by weight of the transparent resin used for the first and second base layers 110 and 110a. When the ultraviolet absorbent is included in the above range on the basis of the above may provide a light diffusion plate 100 stable to the ultraviolet.

The thermal stabilizers include piperidinyl esters, oxazolidines and piperidino oxazolidines, pyrridispyroacetals, and diazacycloalkanones, which may be used alone or in combination of two or more thereof. Can be. The content of the thermal stabilizer is not limited, but is 0.001 to 5 parts by weight, preferably 0.01 to 2 parts by weight based on 100 parts by weight of the transparent resin used for the first and second base layers 110 and 110a. When the heat stabilizer is included in the above range on the basis of the above, it is possible to provide a light diffusion plate 100 that is stable at high temperatures.

As said antioxidant, a phenolic antioxidant, phosphorus antioxidant, sulfur-type antioxidant, etc. are mentioned, Among these, a phenolic antioxidant and phosphorus antioxidant are preferable. In particular, the phenolic antioxidant can be most preferably used because it can prevent coloring of the molded body due to heat, oxidative degradation, or the like, without lowering transparency, heat resistance, or the like. The content of the antioxidant is 0.001 to 5 parts by weight, preferably 0.01 to 2 parts by weight based on 100 parts by weight of the transparent resin used for the first and second base layers 110 and 110a. When the antioxidant is included in the above range on the basis of the above can provide a light diffusion plate 100 excellent in antioxidant properties.

Examples of the antistatic agent include water-soluble metal oxide particles, conductive polymers, surfactants, hydrophilic monomers, and ion conductive monomers. Among them, conductive polymers having excellent heat resistance and surfactants having excellent permeability and antistatic properties are preferably used. Can be used. More preferably, a cationic surfactant having a quaternary amine salt structure having advantages of excellent antistatic properties and dispersibility is preferable. In general, in order to show the antistatic performance, the surface resistivity should show 10 ¹¹ Ω / ㎠ or less, and the content can be appropriately adjusted in consideration of this. In addition, in the case of the light diffusion plate 100, it is important to form a transparent film, so it is good to adjust the material and content in consideration of this.

The protrusion 111 serves to diffuse light from a light source and increase light condensing efficiency. Of course, the front uniformity and brightness with respect to light are thus improved. In addition, cost can be reduced by minimizing the use of optical subsidiary materials.

In general, when using multiple lamps, the image of the lamp is visually identified by the difference between the light and dark areas. If the image of the lamp is visually identified, the quality of the liquid crystal display deteriorates, requiring the use of optical subsidiary materials, which in turn raises the cost. In addition, when a plurality of lamps are used, the amount of power increases, which increases the power consumption of the liquid crystal display.

However, when the second substrate layer 110a having the same shape is arranged on the first substrate layer 110 formed in the longitudinal direction, the projection 111 having an elliptical shape and having a longitudinal cross-section as in the present invention is formed. The protrusion 111 of the first base layer 110 and the protrusion 111a of the second base layer 110a are arranged to be perpendicular to each other to exhibit excellent luminance and uniformity. Therefore, the number of lamps can be reduced, and the use of optical subsidiary materials can be minimized.

In this case, the elliptical protrusions 111 and 111a formed on the first and second base layers 110 and 110a preferably have a short radius a, a long radius b, a height h, and a pitch p satisfying the relationship of the following equation based on the longitudinal section. Do.

&Quot; (1) "

1000 μm ≥ 2b> 2a> p> h ≥100 μm

Projections 111 and 111a of the first and second base layers 110 and 110a have a short radius a of 125 μm to 250 μm, a long radius b of 250 μm to 500 μm, and a height h of 100 μm to 300. It is preferable that it is micrometer and pitch p is 200 micrometers-300 micrometers.

The short radius a, the long radius b, the height h and the pitch p are mutually influential data, and it is difficult to clearly define the critical effect. However, it is important to note that the projections 111 and 111a formed on the first and second base layers 110 and 110a have a problem in that an image of a lamp is seen when the short radius a is greater than or equal to the long radius b. There is a problem with this deterioration.

Although it is difficult to clarify the range and critical significance as data affecting each other, in general, when the short radius a of the protrusions 111 and 111a is less than 125 μm, it is difficult to manufacture a shape roll for manufacturing the protrusions and the protrusions 111 and 111. If the short radius a of a) exceeds 250 µm, projections may be recognized on the screen of the liquid crystal display, and the quality may be degraded. Similarly, when the long radius b of the protrusions 111 and 111a is less than 250 μm, it is difficult to produce a shape roll for manufacturing the same. If the long radius b of the protrusions 111 and 111 a exceeds 500 μm, the protrusions are recognized on the screen of the LCD. As a result, the quality may be degraded. When the height h of the protrusions 111 and 111a is less than 100 μm, it is difficult to form a shape roll for manufacturing the protrusions. When the height h of the protrusions 111 and 111a exceeds 300 μm, the protrusions are recognized on the screen of the liquid crystal display. Quality may be degraded. In addition, when the pitch p, which is the distance between the protrusions 111 and 111a and the adjacent protrusions, is less than 200 μm, it is difficult to manufacture a shape roll for manufacturing the same, and the pitch that is the distance between the protrusions 111 and 111a and the adjacent protrusions is If the thickness exceeds 300 μm, projections may be recognized on the screen of the LCD, thereby degrading the quality.

Forming method for producing the first and second substrate layer (110,110a) is not limited, extrusion molding, vacuum molding, hot press molding, co-extrusion molding, film lamination method, solvent bonding method, surface coating method, ultraviolet light Various methods, such as a hardening method and a thermosetting method, can be used. The easiest way of manufacturing is extruded. In addition, although not shown in the drawings, the protrusions 111 and 111a may be manufactured by cutting the cylindrical roll to form the same shape as the protrusion in an intaglio shape.

3 illustrates a cross section of a substrate layer according to another embodiment of the present invention.

As shown in FIG. 3, the substrate layer 210 according to another embodiment of the present invention has a light incident surface 212 on which light is incident from a light source, and has an elliptical shape in the upper surface thereof and is long in the transverse direction. The formed protrusions 211 are continuously formed in the longitudinal direction, and the outer side of the protrusions 211 includes a light exit surface 213 through which light is emitted.

In this case, functional layers 214 and 215 may be further formed on at least one of the light incident surface 212 and the light exit surface 213 to improve durability and weather resistance.

The thickness of the functional layers 214 and 215 is not limited but is preferably 0.05 mm to 1.5 mm. When the thicknesses of the functional layers 214 and 215 fall within the above ranges, good durability can be obtained and excellent light diffusion rate can be achieved.

When the functional layers 214 and 215 are formed on both the light incident surface 212 and the light exit surface 213, the thickness of the functional layer 214 formed on the light incident surface 212 and the light exit surface 213 The thickness of the functional layer 215 is formed may be the same, but may be formed differently. For example, when the thickness of the functional layer 214 formed on the light incident surface 212 is t1, the thickness t1 may be 0.01 mm to 0.1 mm. In addition, when the thickness of the functional layer 215 formed on the light exit surface 213 is t2, the thickness t2 may be 0.0025mm to 0.1mm.

Typically, the light exit surface 213 of the light diffusion plate has an increased surface area compared to the light incident surface 212. In this case, when the same amount of extrusion of the functional layers 214 and 215 of the light exit surface 213 and the light incident surface 212 is manufactured in the same way, the portion where the surface area is increased becomes relatively thin and the portion where the surface area is relatively small is relatively The thickness is formed thick. In addition, in the direct type backlight unit, the light incident surface 212 is directly irradiated with ultraviolet rays emitted from the lamp. Therefore, the thickness t1 is preferably formed thicker than the thickness t2.

The functional layers 214 and 215 may be made of a transparent resin, and preferably, may further include light diffusing agents 214a and 215a.

The transparent resin used for the functional layers 214 and 215 is not limited, and preferably the same resin as the above-described first and second base layers may be used.

In addition, the light diffusing agents 214a and 215a used in the functional layers 214 and 215 may be the same as those described above as the light diffusing agents of the first and second base layers, and the size thereof is 10 μm to 35 μm. Is preferably. Good functional layers 214 and 215 can be obtained when the roughness 214b and 215b is in the range.

The light diffusing agents 214a and 215a may preferably use about 0.5 parts by weight to 25 parts by weight based on 100 parts by weight of the transparent resin used for the functional layers 214 and 215. When the light diffusing agents 214a and 215a are included in the above ranges based on the above criteria, a light diffusing plate of good quality having excellent light dispersion efficiency can be obtained.

If necessary, the functional layers 214 and 215 may further include at least one selected from ultraviolet absorbers, heat stabilizers, antioxidants, antistatic agents, fluorescent brighteners, and release agents as described in the first and second substrate layers described above. Can be.

The functional layers 214 and 215 may be formed by applying a coating method to at least one of the light incident surface 212 or the light exit surface 213 of the base layer 210, or may be manufactured in a sheet form and then bonded. It can be formed, which can be easily carried out by those skilled in the art. Particularly preferably, the functional layers 214 and 215 may be formed through an extrusion process or a coating process.

According to the present invention, roughnesses 214b and 215b may be further formed on at least one of the light incident surface 212 and the light exit surface 213 of the base layer 210. The roughness 214b and 215b may allow the functional layers 214 and 215 to include the light diffusing agents 214a and 215a to naturally form the predetermined roughness 214b and 215b. The roughnesses 214b and 215b serve to diffuse light. In addition, the roughness 214b and 215b cancels the light so as to cancel the image of the lamp to obtain a uniform image.

In general, when a scratch is generated on the light diffusion plate, light may not be diffused normally, thereby degrading the quality of the liquid crystal display. In order to prevent this, a protective film is additionally required. However, when the predetermined roughnesses 214b and 215b are formed as in the present invention, light may be prevented from being deteriorated due to the diffusion of light due to the predetermined roughnesses 214b and 215b. As a result, there is no need to add a protective film, thereby preventing cost increases.

In more detail, the roughness 214b and 215b herein means the degree of minute unevenness occurring on the surfaces of the functional layers 214 and 215. Representative values can be represented by the centerline average roughness (Arithmetic average roughness, centerline average roughness), which is the average height from the centerline to the cross-sectional curve.

The center line average roughness Ra value of the predetermined roughness 214b formed on the functional layer 214 formed on the light incident surface 212 is not limited, but may be in a range of about 1 μm to 20 μm. Preferably, the centerline average roughness Ra is 3 µm to 15 µm. When the center line average roughness Ra of the functional layer 214 is less than 1 μm, light cannot be diffused, and when a scratch occurs, it is easily identified with the naked eye, so that the quality of the liquid crystal display device may be degraded and productivity may be reduced. In addition, when the center line average roughness Ra of the functional layer 214 exceeds 20 μm, light may not be evenly diffused, and thus the quality of the liquid crystal display may be degraded.

By forming a predetermined roughness 214b in a predetermined range on the functional layer 214 of the light incident surface 212 as described above, it is possible to provide a light diffusion plate that is resistant to scratches and has good light efficiency. Of course, by providing a light diffusion plate resistant to scratches, the light diffusion plate according to the present invention does not need to attach a protective film to the light incident surface 212 of the base layer 210. In other words, when the centerline average roughness Ra is less than 3 µm, scratches are more likely to occur, and when scratches occur, quality degradation may occur. Therefore, in order to prevent this, a protective film may be attached to prevent quality deterioration. However, attaching a protective film causes a cost increase. However, when a predetermined roughness 214b having a centerline average roughness Ra of 3 μm or more is formed on the light incident surface 212 of the base layer 210 as in the present invention, a light diffusion plate that is resistant to scratches without attaching a protective film. Will be provided. This means that it is possible to prevent the cost increase by helping to improve the quality of the backlight unit liquid crystal display device or general lighting device.

In addition, roughness 215b may be formed on the light exit surface 213. If a predetermined roughness 215b is formed on the light exit surface 213, the light diffusion efficiency may be further increased. In addition, by forming a predetermined roughness 215b, it is possible to prevent a decrease in visibility when a scratch occurs, and to provide a light diffusion plate having excellent quality. Of course, by providing a light diffusion plate that is resistant to scratches, a protective film is not required on the uppermost surface, and thus a cost increase can be suppressed. Therefore, the backlight unit and the liquid crystal display device employing the light diffusing plate can also prevent cost increase.

The method of forming the roughness 214b and 215b on the light incident surface 212 or the light exit surface 213 is naturally roughened by the light diffusing agents 214a and 215a added to the functional layers 214 and 215b. ) May be formed, or after the functional layers 214 and 215 are formed, the roughness 214b and 215b may be formed through additional processes. For example, the roughness 214b and 215b may be formed by using a shape roll having a predetermined roughness, and the roll may engrav the surface of the roll by using an energy-controlled laser, or apply a fine ball metal to the roll. It can be produced by spraying.

The backlight unit according to the present invention includes the light diffusing plate according to the present invention described above. In addition, the liquid crystal display according to the present invention includes the backlight unit and the light source.

The backlight unit may be used in both a direct type and an edge type, but is preferably applied to the direct type.

The light source 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. Preferably LEDs can be used.

The liquid crystal display device may be a reflection type, transmissive type, transflective type LCD, or a liquid crystal display device having various driving methods such as TN type, STN type, OCB type, HAN type, VA type, and IPS type. Configurations are well known in the art and thus detailed descriptions are omitted.

The lighting apparatus according to the present invention includes the light diffusing plate and the light source according to the present invention described above. The lighting device is not particularly limited, and any lighting device known in the art may be applied and included in the present invention. As a light source of the lighting device, a hot cathode tube, a cold cathode tube, a light emitting diode (LED), an organic electroluminescent element (OLED), or the like may be used without limitation. Preferably LEDs can be used. Since the above-described configuration of the lighting apparatus is well known in the art, a detailed description thereof will be omitted.

Hereinafter, the present invention will be described in detail with reference to the following examples. However, these are presented to aid the understanding of the present invention, and the present invention is not limited thereto.

<Production Examples 1 to 5>

As described in Table 1, using a composition consisting of a transparent resin and a light diffusing agent (size: 5㎛) to form a base layer having a projection on the surface, the bottom and top of the base layer as shown in Table 1 Base resin was applied in thickness.

In this case, the protrusions have a shape as shown in FIGS. 1 and 2, and a 150 μm, b is 600 μm, pitch p is 270 μm, and height is 160 μm in an elliptical shape of the longitudinal section.

division Diffusion Base Layer Functional layer Base resin Light diffusing agent Thickness (mm) Base resin Thickness (mm) PC (part by weight) PMMA (parts by weight) PC (part by weight) Preparation Example 1 100 0.5 1.9 100 0.05 Production Example 2 100 1.0 1.9 100 0.05 Production Example 3 100 1.5 1.9 100 0.05 Preparation Example 4 100 1.0 1.9 100 0.05

<Examples 1 to 4>

Two substrate layers prepared in Preparation Examples 1 to 4 were laminated, but light projection plates were prepared by arranging protrusions formed in each of the substrate layers to be perpendicular to each other.

Comparative Example 1

The base material layer manufactured by the said manufacture example 4 was used as the light-diffusion plate.

Experimental Example

After attaching the light diffusing plate prepared in the above Examples and Comparative Examples to the 42-inch backlight unit, the brightness and uniformity measurement and lamp image visual test were performed as shown below, and the results are shown in Table 2 below.

In this case, as a light source of the backlight unit, an LED (normal type) is arranged as shown in FIG.

-Luminance and uniformity test

A light diffuser plate was mounted on a 42-inch backlight unit and measured with a luminance meter (RISA-COLOR8, HI-LAND).

Luminance was determined by the tread of the emitted light per unit area (cd / m2), and uniformity was determined by the ratio of the lightest and darkest parts (uniformity (%) = (minimum luminance / maximum luminance) * 100). Judgment on the measurement can be used as the maximum luminance / minimum luminance and the criteria can be applied in the same manner without being different.

At this time, the distance between the light source (LED) and the diffusion plate was 20mm, and the distance between the light sources was horizontal (15.42mm) and vertical (15.75mm).

-Visual test of lamp image

A visual diffuser plate was mounted on a 42-inch backlight unit to measure visual inspection.

-Check lamp image

After mounting the light diffusion plate in the 42-inch backlight unit was photographed the surface and the results are shown in Figure 5a to 5d. 5A shows Example 1, FIG. 5B shows Example 2, FIG. 5C shows Example 3 and FIG. 5D shows the results of Comparative Example 1, respectively.

Luminance [nit] Luminance uniformity
(min / max [%]) Lamp Image Visual Test Example 1 9314 65 Good Example 2 8572 66 Good Example 3 8465 66 Good Comparative Example 1 7998 61 Bad

As shown in Table 2, in accordance with the present invention, the two substrate layers were stacked, but in Examples 1 to 3 in which the protrusions were arranged in the vertical direction, the luminance and the luminance uniformity were excellent, and the lamp image visual test result was also excellent. It can confirm that it is favorable. In particular, as shown in Figure 5a to 5d in the case of the embodiment according to the invention it can be seen that the lamp image does not enter the outside compared to the comparative example.

1 is an exploded perspective view of a light diffusing plate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the substrate layer shown in FIG. 1.

3 illustrates a cross section of a substrate layer according to another embodiment of the present invention.

4 is a photograph illustrating an example of a light source of the backlight unit.

5A to 5D are photographs showing images of the light diffusion plates manufactured in Examples 1 to 3 and Comparative Example 1 mounted on the backlight unit.

<Description of the symbols for the main parts of the drawings>

100: light diffusion plate 110: first substrate layer

111: projection 112: light incident surface 113: light exit surface

120: second base layer 121: projection

210: first substrate layer or second substrate layer

211: projection 212: light incident surface 213: light exit surface

214,215: functional layer 214a, 215a, 216: light diffusing agent

214b, 215b: Roughness

Claims (12)

The bottom surface is provided with a light incidence surface through which light is incident from a light source, and the upper surface has an elliptical shape having a longitudinal cross section, and projections formed in the transverse direction are continuously formed in the longitudinal direction, and the outer surface of the projection includes a light emission surface on which light is emitted. It comprises a first and second substrate layer made of And a second substrate layer formed on an upper surface of the first substrate layer, wherein the protrusions of the first substrate layer and the protrusions of the second substrate layer are arranged to be perpendicular to each other. The light diffusing plate according to claim 1, wherein the elliptical protrusions of the first and second base layers have a short radius a, a long radius b, a height h, and a pitch p satisfying the following equation. &Quot; (1) &quot; 1000 μm ≥ 2b> 2a> p> h ≥100 μm The light diffusing plate of claim 2, wherein the short radius a of the elliptical protrusions of the first and second base layers is 125 μm to 250 μm. The light diffusing plate of claim 1, wherein the long radius b of the elliptical protrusions of the first and second base layers is 250 μm to 500 μm. The light diffusing plate of claim 1, wherein the height h of the elliptical protrusions of the first and second base layers is 100 μm to 300 μm. The light diffusing plate of claim 1, wherein the pitch p of the elliptical protrusions of the first and second base layers is 200 μm to 300 μm. The light diffusing plate according to claim 1, wherein roughness is further formed on at least one of the light incident surface and the light exit surface of the first and second substrate layers. The light diffusing plate according to claim 1, wherein the functional layer is further provided on at least one of the light incident surface and the light exit surface of the first and second substrate layers. The light diffusing plate according to claim 8, wherein at least one of the base layer and the functional layer is made of a transparent resin and a light diffusing agent. 10. The method of claim 9, wherein at least one of the base layer and the functional layer comprises a light diffusion, at least one selected from among ultraviolet absorbers, heat stabilizers, antioxidants, antistatic agents, optical brighteners, release agents. plate. A backlight unit comprising the light diffusion plate of any one of claims 1 to 10. An illumination device comprising the light diffusing plate of any one of claims 1 to 10.

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