KR20160056499A - Optical sheet and optical display device comprising the same - Google Patents

Abstract

The present invention relates to an optical sheet having a substrate layer, a prism pattern layer formed on one side of the substrate layer, and an uneven pattern formed on the other side of the substrate layer and, more specifically, to an optical sheet which is characterized in that, when the optical sheet is fixed on a position apart from a circular optical source with a diameter (D) of 8mm by 110mm, an imaging device is attached closely to the optical sheet to take an electronic image of the optical sheet, and a distribution curve of a gray value according to a distance (x) extracted from the taken electronic image is obtained. A diffusion width (DFW) is 14-25mm and there is no inflection point in the DFW with respect to a gray value of 50 over the distribution curve. Since the optical sheet according to the present invention does not use a light diffusion particle, the optical sheet is environmentally-friendly and easy to be hidden and brightness of the optical sheet is improved.

Description

Technical Field [0001] The present invention relates to an optical sheet and an optical display device including the optical sheet.

The present invention relates to an optical sheet and an optical display device including the optical sheet.

A liquid crystal display (LCD), which is one of the fields to which the present invention can be applied, generally includes an upper substrate on which a common electrode and a color filter are formed, a lower substrate on which a thin film transistor and a pixel electrode are formed A liquid crystal material is injected and an electric field is formed by applying different electric potentials to the pixel electrode and the common electrode to change the arrangement of the liquid crystal molecules and control the transmittance of light through the liquid crystal molecules. Since the liquid crystal display device is a light receiving element that can not emit light by itself, a backlight unit for supplying light is required.

In general, the surface of a display device of a liquid crystal display (LCD) must be able to diffuse a certain amount of emitted light in order to prevent glare caused by light emitted from the inside. In addition, the display surface may reflect light incident from the outside to form an image on the surface. If the image is clear, the display image may be affected by the reflected image. For example, when the display device is used outdoors and under a bright illumination, external light such as sunlight and fluorescent light may be reflected on the surface of the display, which may cause reflection, so it is necessary to secure concealment.

In order to secure such concealment, a light diffusion layer may be formed on one side of the base layer of the optical sheet. The light diffusion layer may be formed by forming a coating layer using a resin including light diffusion particles using a wet coating method such as Microgravure or Slot Die , And can be formed by UV and heat treatment.

In this case, the light diffusion effect is caused by the light scattering effect due to the surface protrusion caused by the surface protrusion of the light diffusion particles and the internal refraction due to the difference in refractive index between the light diffusion particles and the resin having different refractive indexes. At this time, at least one or more kinds of light diffusing particles to be used are used, and the size of the light diffusing particles is in the range of sub to several tens of micrometers, and the amount of the light diffusing particles used is several to several tens of weight percent.

In addition, at least one organic solvent is used for controlling the viscosity and appearance of the wet coating method. Volatile organic solvents having a relatively low boiling point are used, and the used amount is several to several hundred weight% do. At this time, the light diffusion particles to be used are used in a state of being dispersed in a mixture of the resin and the organic solvent. If the stability of the dispersion state of the light diffusion particles is deteriorated due to coating conditions and time, ≪ / RTI >

In addition, environmental pollution caused by light diffusion particles and organic solvents in the manufacturing process and health problems of workers may be caused.

A problem to be solved by the present invention is to provide an optical sheet excellent in visual sensitivity.

Another problem to be solved by the present invention is to provide an optical sheet having a light diffusion layer using light diffusing particles, which has a low haze value and an internal diffusion effect to improve the hiding power and improve the brightness, The present invention also provides an optical sheet that can be used as an optical sheet.

Another object to be solved by the present invention is to provide an optical sheet which is environmentally friendly, safe, and economical by not using light diffusion particles and organic solvent.

The above and other objects of the present invention can be achieved by the present invention described below.

One aspect of the present invention is an optical sheet including a base layer, a prism pattern layer formed on one side of the base layer, and a concavo-convex pattern formed on the other side of the base layer, wherein the optical sheet has a position spaced by 110 mm from a circular light source having a diameter D of 8 mm When the gray value on the distribution curve of the gray value according to the distance (distance, x) extracted from the photographed electronic image closely attached to the optical sheet after fixing the optical sheet to the optical sheet is 50, (DFW) of 14 mm to 25 mm and no inflection point within the diffusion distance.

The optical sheets may not have the same gray value or the same gray value twice in the diffusion distance on the distribution curve of the gray value according to the distance.

The optical sheet may have a haze value of 9 to 60%.

The surface roughness Rz of the concavo-convex pattern may be 0.8 to 2.7 mu m.

The substrate layer may be formed of at least one of a polyacetal resin, a polyacrylic resin, a polystyrene resin, a polycarbonate resin, a polysulfone resin, a polyvinyl chloride resin, a polyvinyl alcohol resin, a polynorbornene resin, Based resin, a vinyl-based resin, a polyphenylene ether-based resin, a polyolefin-based resin, a cycloolefin-based resin, an acrylonitrile-butadiene-styrene-based copolymer resin, a polyarylsulfone- , A polyethylene naphthalate resin, or a fluorine resin.

The prism pattern layer may be a cured product of an ultraviolet curable resin containing at least one member selected from the group consisting of urethane acrylic, polyester acrylic, silicone acrylic, unsaturated polyester, and polyether acrylic.

The thickness of the base layer may be 38 to 300 mu m, and the thickness of the prism pattern layer may be 10 to 50 mu m.

The surface roughness Ra of the concavo-convex pattern may be 0.09 to 0.32 mu m, and Ry may be 0.8 to 2.7 mu m.

The pitch of the unit prisms constituting the prism pattern layer may be 20 to 60 탆 and the height may be 10 to 30 탆.

Another aspect of the present invention relates to an optical display device including the optical sheet.

The optical sheet of the present invention does not use light-diffusing particles and is eco-friendly, and has excellent properties such as brightness and hiding.

Figs. 1 (a) and 1 (b) illustrate a visual evaluation method according to one embodiment of the present invention.
2 is a graph showing a gray value distribution according to a distance extracted from an electronic image.
3 is a perspective view of an optical sheet according to an embodiment of the present invention.
4 is a cross-sectional view of an optical sheet according to one embodiment of the present invention.
5 is a conceptual diagram of an optical sheet manufacturing process according to one embodiment of the present invention.
6 shows a perspective view of an optical display device including an optical sheet according to an embodiment of the present invention.
Fig. 7 (a) is an electrophotograph obtained by photographing a light source transmitted through the optical sheet of Example 1, and Fig. 7 (b) is an electrophotograph obtained by photographing a light source transmitted through the optical sheet of Comparative Example 1. Fig.

Embodiments of the present application will now be described in more detail with reference to the accompanying drawings. However, the techniques disclosed in this application are not limited to the embodiments described herein but may be embodied in other forms. It should be understood, however, that the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the width, thickness, and the like of the components are enlarged in order to clearly illustrate the components of each device. Like numbers refer to like elements throughout the several views.

The terms "upper" and "lower" in this specification are defined with reference to the drawings, wherein "upper" may be changed to "lower", "lower" What is referred to as "on" may include not only superposition, but also intervening other structures in the middle.

In the present invention, the term " sensation "refers to a degree of glare caused by light emitted from the inside of the display optical sheet or a sharpness of a reflected image due to a light source or an external object incident from the outside when the user views the display device at a certain distance . It is defined as an optical sheet having superior visibility as the effect of concealing reflected image is reduced by reducing the glare of the reflection image or the sharpness of the reflection image.

In the present invention, the "inflection point" is defined as an area in which the same gray value appears more than three times according to the distance on the distribution curve of the gray value according to the distance. Therefore, the expression "no inflection point exists" means that the same gray value does not appear according to the distance on the distribution curve, or that there exists an area where the same gray value appears twice.

Optical sheet

The optical sheet of the present invention comprises a base layer, a prism pattern layer formed on one side of the base layer, and a concavo-convex pattern formed on the other side of the base layer, wherein the optical sheet has a position spaced by 110 mm from a circular light source having a diameter D of 8 mm The gray value on the distribution curve of the gray value according to the distance (x, y) extracted from the photographed electronic image by closely contacting the optical device to the optical sheet after fixing the optical sheet is 50 days , The diffusion distance (DFW) is 14 mm to 25 mm, and no inflection point exists within the diffusion distance.

Figs. 1 (a) and 1 (b) illustrate a visual evaluation method according to an embodiment of the present invention. Referring to FIG. 1, the optical sheet is fixed at a position separated by 110 mm from the circular light source having a diameter of 8 mm emitted from the backlight unit BLU by a distance of 110 mm, the optical device is brought into close contact with the optical sheet, Take the transmitted light source. Thereafter, the photographed electronic image is analyzed by extracting gray values and distribution curves of the software such as Adobe Photoshop program and the distance according to the distance, and analyzing the extracted data, It can be quantified and quantified.

Figure 2 illustrates a distribution curve of gray values according to distance extracted from an ensured electronic image, according to one embodiment of the present invention. Referring to FIG. 2 (a), the x axis of the distribution curve of the gray value according to the distance means a distance or the number of pixels, and the y axis indicates the gray value measured at the corresponding distance (gray value).

In one embodiment, the optical sheet of the present invention is characterized in that when the gray value on the distribution curve of the gray value according to the distance is 50 (y = 50), the distance between the intersections on the x- That is, the diffusion distance (DFW) may be 14 mm to 25 nm, specifically 15.6 mm to 24.2 mm. For example, 20 to 25 mm. When the inflection point condition and the DFW value range are satisfied, excellent hiding ability can be ensured.

Further, the optical sheet according to one embodiment of the present invention has no inflection point within the diffusion distance DFW. Specifically, the optical sheet may not show the same gray value within the diffusion distance, or the same gray value may appear twice. When there is no inflection point under the above condition, the hiding power is excellent, and the phenomenon of reflection of objects on the display surface or reflection phenomenon can be prevented.

Referring again to FIG. 1 (a), a black sheet having a circular hole with a diameter of 8 mm is closely contacted with the backlight unit to specify a circular light source emitted from the backlight unit, thereby specifying an object to be measured.

The imaging device can be used without limitation as long as it is an apparatus device capable of converting an image formed on the optical sheet into an electronic image.

The illuminance of the backlight unit may be 1000 to 3000 lux, specifically 1400 to 2300 lux. When the illuminance exceeds 3000 lux, the illuminance of the transmitted light becomes too high to distinguish the hiding power itself, and when the illuminance is 1000 lux or less, the illuminance of the diffused light is weak,

The black sheet may be an acrylic sheet containing a black dye or a transparent substrate coated with a black ink, but is not necessarily limited thereto.

In yet another embodiment, the optical sheet of the present invention may have a haze value of 9 to 60%, specifically 12 to 50%. Since the haze value and the internal diffusion effect of the optical sheet of the present invention are lower than those of the conventional optical sheet (bead type) using the light diffusing particles, it is possible to improve the hiding power and improve the brightness, It is possible to eliminate the sparkling phenomenon that may appear due to the presence of the gas.

FIG. 3 is a perspective view of an optical sheet according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view of an optical sheet taken along the line X-X 'in FIG.

3 and 4, the optical sheet 100 includes a base layer 110, a prism pattern layer 120 formed on one surface of the base layer 110, and a concavo-convex pattern 130 formed on the other surface of the base layer 110. [ .

The substrate layer 110 is formed of a resin such as a polyacetal resin, a polyacrylic resin, a polystyrene resin, a polycarbonate resin, a polysulfone resin, a polyvinyl chloride resin, a polyvinyl alcohol resin, a polynorbornene resin, But are not limited to, resins, vinyl resins, polyphenylene ether resins, polyolefin resins, cycloolefin resins, acrylonitrile-butadiene-styrene copolymer resins, polyaryl sulfone resins, polyether sulfone resins, Based resin, a polyethylene naphthalate-based resin, and a fluorine-based resin.

The thickness (D) of the base layer 110 may be 38 to 300 mu m, but is not limited thereto.

Referring to FIG. 4, the prism pattern layer 120 includes a plurality of unit prisms successively arranged on one surface of the base layer 110.

The height H of the unit prisms may be equal to or different from each other, and may be about 10 to about 30 탆, and there may be no moiré in the above range and a condensing effect. The pitches P of the unit prisms may be the same or different from each other. Specifically, the pitch may be about 20 to about 60 占 퐉. In this range, there is no moire and the light converging effect may be obtained. The apex angle of the unit prism may be about 80 to about 100, and the luminance may be improved in the above range.

In one embodiment of the present invention, the refractive index of the prism pattern layer 120 may be 1.48 to 1.67, specifically 1.50 to 1.65. There is an advantage that light incident at the above-mentioned range can be emitted with high luminance.

The prism pattern layer 120 may be formed on one surface of the base layer 110 by an ultraviolet curing method in which the prism pattern layer 120 is compression-molded. For example, a transparent resin composition is injected between the pulling roll and a base layer in a state where one side of the base layer is in contact with a mold pulling roll on which a prism pattern is imprinted, and cured to form a transparent resin composition coating layer Can be formed separately from the pull roll.

The prism pattern layer 120 may be a transparent material in the visible light region and may be formed of a UV curable resin or a composition containing the UV curable resin. For example, the ultraviolet curable resin may include at least one selected from the group consisting of urethane acrylic, polyester acrylic, silicone acrylic, unsaturated polyester, and polyether acrylic.

The optical sheet 100 may include a pattern for light diffusing function on the other surface of the base layer 110, and concretely, the concavo-convex pattern 130 not including the light diffusion particles may be formed.

The concavo-convex pattern 130 has a surface roughness Ra of about 0.09 to 0.32 占 퐉, preferably 0.11 to 0.28 占 퐉, a Rz of about 0.8 to 2.7 占 퐉, preferably 1.0 to 2.4 占 퐉, as measured by a three- About 0.8 to 2.7 占 퐉, preferably 1.0 to 2.3 占 퐉. In this range, the diffusion efficiency due to surface scattering increases and the shielding force can be improved. The surface roughness can be measured by the standard of JIS B0601: 1994. Specifically, the surface roughness of the measuring device can be measured using a VK-9700 manufactured by Keyence. At this time, the surface roughness can be measured by setting the measurement magnification to 1000 magnification and the Z-axis pitch to 1 mu m.

The concavo-convex pattern 130 may be formed on the other surface of the base layer 110 by sandblasting, for example.

First, a pattern is formed on a metal mold, preferably a metal roll, by a method such as sand blasting. The metal mold may be a roll including at least one metal selected from the group consisting of steel, aluminum, and alloys thereof, or plated with nickel, copper, chromium, aluminum, ceramics or DLC. In particular, the plated layer of double nickel or copper has a relatively low hardness as compared with steel, so that it is easy to form a pattern by sandblast, and therefore, it is easy to control the haze according to the application. As the metal, a single component metal may be used, or an alloy of two or more components may be used. The metal rolls must be patterned effectively by sand blasting, etching, laser machining, drilling, etc., and must be reused depending on the application. Thus, the metal rolls can be reused by plating It is preferable to use it afterwards.

The method may further include forming a metal coating layer on the metal mold having the pattern formed thereon. There is a case where a metal coating layer having high strength is plated to improve the durability of the patterned metal mold and to improve the surface roughness. The metal coating layer may be made of nickel, chromium, ceramics, or an alloy thereof, or an alloy of a single metal or two or more metals may be used. The thickness of the coating layer is preferably 0.1 to 1000 占 퐉, and may be a single layer or a plurality of layers formed of single or different metals.

The sandblast may be treated 1 to 50 times with at least one bead of organic, inorganic or organic composite beads.

The bead particles may be used singly or in combination of two or more species having an average size of 0.1 to 1000 탆. The bead material may be an organic material such as ester, olefin, acrylic, urethane, acryl-urethane, epoxy, , And inorganic beads such as ceramics.

The surface roughness and the haze value of the surface on which the light diffusion pattern is formed can be easily controlled by controlling the conditions of the sandblast such as the type, size, injection pressure, and number of particles used in the sandblast.

5 is a conceptual diagram of a process of forming a concavo-convex pattern and an optical sheet according to an embodiment of the present invention. The pattern of the metal roll I is transferred onto one side of the base layer while the base film 110 or the base layer 110 is in contact with the patterned metal roll I to form the uneven pattern 130, Is in contact with the pull roll II for forming a prism pattern, the prism pattern layer 120 is formed and the optical sheet can be completed. On the other hand, the order of the irregular pattern formation and the prism pattern layer formation can be changed. However, it is not always necessary to carry out the process of forming the concave-convex pattern and the forming of the prism pattern layer in succession with the metal roll for forming the concave-convex pattern and the pull roll for forming the prism pattern layer. However, The metal roll for forming the concavo-convex pattern and the pull roll for forming the prism pattern layer may be simultaneously contacted.

Optical display device

The optical display device, which is another aspect of the present invention, may include the optical sheet. In the optical display member, the optical sheet may be comprised of a prism sheet, a diffusion sheet, or a light guide plate. The optical display device may include a liquid crystal display, and the light source in the liquid crystal display may include an LED lamp or a CCFL.

6, an optical display device 300 according to an exemplary embodiment of the present invention includes a light source 210, a light guide plate 220 for guiding light emitted from the light source 210, a light guide plate A diffusion sheet 240 disposed on the upper side of the light guide plate 220 and an optical sheet 100 disposed on the upper side of the diffusion sheet 240.

In addition, a light source cover 210a may be disposed outside the light source 210 of the backlight unit. Here, although not shown, a liquid crystal display panel and an antireflection layer are sequentially stacked on the optical display device 300 to form a liquid crystal display device.

The light source 210 generates light, and various light sources such as a linear light source lamp, a planar light source lamp, a CCFL, or an LED may be used.

The light guide plate 220 guides the light generated from the light source 210 to the diffusion sheet 240, and may be omitted when a direct-type light source is employed.

The reflective sheet 230 reflects light generated from the light source 210 and supplies the light to the diffusion sheet 240.

The diffusion sheet 240 diffuses and scatters light incident through the light guide plate 220 and supplies the light to the optical sheet 100.

The optical sheet 100 refracts the light incident through the diffusion sheet 240 and focuses the light on the plane of the liquid crystal display panel (not shown). The optical sheet can be modified and combined with various design values such as the shape of the light collecting part and the angle of the inclined surface of the light collecting part according to various design goals, such as high condensing efficiency, wide viewing angle, prevention of moire phenomenon and prevention of optical outflow And is being applied commercially.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. However, the following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples. The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Examples 1-3 and Comparative Examples 1-3

Example 1

Using a polydisperse glass bead having a particle size of 45 to 63 mu m in a copper-plated steel roll, the pattern was formed by sandblasting back and forth seven times at an injection pressure of 300 kPa. A nickel plated layer of 5-8 μm was formed on the patterned steel roll at 130 A for 16 minutes and then plated. This was transferred to one surface of a PET base layer (TAK XG7PH2) having a thickness of 250 mu m using a UV curable resin to form a concavo-convex pattern.

 The PET base layer was coated with a gravure roll having a prism pattern cut on the other side, and then cured by ultraviolet rays to form a prism pattern layer. The height of the unit prism constituting the prepared prism pattern layer was 12 占 퐉 and the pitch was 24 占 퐉

The physical properties of the prepared optical sheet were measured and are shown in Table 1 below.

Example 2

Using a polydisperse glass bead having a particle size of 45 to 63 占 퐉, a bronze-plated steel roll was sandblasted five times reciprocally at an injection pressure of 300 kPa to form a pattern. A nickel plated layer of 3 to 5 μm was formed on the patterned steel roll at 130 A for 10.5 minutes to perform post plating. This was transferred to one surface of a PET base layer (TAK XG7PH2) having a thickness of 250 mu m using a UV curable resin to form a concavo-convex pattern.

The PET base layer was coated with a gravure roll having a prism pattern cut on the other side, and then cured by ultraviolet rays to form a prism pattern layer. The height of the unit prism constituting the prepared prism pattern layer was 12 mu m and the pitch was 24 mu m.

The physical properties of the prepared optical sheet were measured and are shown in Table 1 below.

Example 3

Using a polydisperse glass bead having a particle size of 45 to 63 mu m in a copper-plated steel roll, the pattern was formed by sandblasting back and forth seven times at an injection pressure of 300 kPa. A nickel plating layer having a thickness of 1 to 3 μm was formed on the nickel plated steel roll having a pattern formed thereon at 130 A for 4 minutes to perform post plating. This was transferred to one surface of a PET base layer (TAK XG7PH2) having a thickness of 250 mu m using a UV curable resin to form a concavo-convex pattern.

The PET base layer was coated with a gravure roll having a prism pattern cut on the other side, and then cured by ultraviolet rays to form a prism pattern layer. The height of the unit prism constituting the prepared prism pattern layer was 12 mu m and the pitch was 24 mu m.

The physical properties of the prepared optical sheet were measured and are shown in Table 1 below.

Comparative Example 1

Using a polydisperse glass bead having a particle size of 1 to 40 占 퐉, the copper-plated steel roll was sandblasted five times reciprocally at an injection pressure of 130 kPa to form a pattern. A nickel coating layer of 2 to 4 μm was formed on the patterned steel roll at 130 A for 7.5 minutes, and then subjected to post-plating. This was transferred to one surface of a PET base layer (TAK XG7PH2) having a thickness of 250 mu m using a UV curable resin to form a concavo-convex pattern.

The PET base layer was coated with a gravure roll having a prism pattern cut on the other side, and then cured by ultraviolet rays to form a prism pattern layer. The height of the unit prism constituting the prepared prism pattern layer was 12 mu m and the pitch was 24 mu m.

The physical properties of the prepared optical sheet were measured and are shown in Table 1 below.

Comparative Example 2

Using a polydisperse glass bead having a particle size of 1 to 40 占 퐉 in a nickel-plated steel roll, a pattern was formed by sandblasting back and forth eight times at an injection pressure of 200 kPa. A nickel plating layer having a thickness of 2 to 4 μm was formed on the patterned nickel steel roll at 130 A for 7.5 minutes, and the plating was carried out. This was transferred to one surface of a PET base layer (TAK XG7PH2) having a thickness of 250 mu m using a UV curable resin to form a concavo-convex pattern.

The PET base layer was coated with a gravure roll having a prism pattern cut on the other side, and then cured by ultraviolet rays to form a prism pattern layer. The height of the unit prism constituting the prepared prism pattern layer was 12 mu m and the pitch was 24 mu m.

The physical properties of the prepared optical sheet were measured and are shown in Table 1 below.

Comparative Example 3

40% by weight of neutralized PMMA (Advanced Chemical MAX50) and 60% by weight of an organic solvent mixed with methyl ethyl ketone (MEK) and toluene in a ratio of 1: 1 were mixed and sufficiently dispersed using a dispersing device to prepare a polymer resin solution . Using this, a 250 μm thick PET substrate layer (TAK XG7PH2) was coated on one side with a microgravure coater and UV-cured to form a light diffusion layer.

The PET base layer was coated with a gravure roll having a prism pattern cut on the other side, and then cured by ultraviolet rays to form a prism pattern layer. The height of the unit prism constituting the prepared prism pattern layer was 12 mu m and the pitch was 24 mu m.

The physical properties of the prepared optical sheet were measured and are shown in Table 1 below.

Property evaluation method

1. Haze value (%):

The haze of the optical sheet was measured in the ISO mode using a haze guard II manufactured by Toyo Seiki Seisakusho Co., Ltd.

2. Surface roughness Rz (탆):

Measured using a VK-9700 from Keyence, in accordance with JIS B0601: 1994.

3. Diffusion distance (DFW) and presence or absence of inflection points:

As shown in Figure 1, The optical sheets of the examples and comparative examples were fixed at positions separated from each other by a distance of 110 mm from a light source having a diameter of 8 mm emitted from a backlight unit (BLU, 190M2 19 inch, CCFL 2 lamp), and then a digital camera (Cannon EOS 600D and exposure distance of 15 mm) were closely contacted to obtain a distribution curve of a gray value according to the distance. The distance between the intersections on the x-axis is measured as a diffusion distance DFW (nm) when the gray value of the gray value is 50 (y = 50), and the inflection point on the distribution curve of the gray value And whether or not it occurred.

4. Visual assessment :

The electronic image of the photographed optical sheet was visually observed and evaluated based on whether or not the boundary line of the circular light source was observed clearly (hiding power is very good: good, good: O: poor: X).

7 (a) is an electrophotograph obtained by photographing a light source transmitted through the optical sheet of Example 1, and Fig. 7 (b) is a photograph illustrating an electrophotograph obtained by photographing a light source transmitted through the optical sheet of Comparative Example 1, It can be confirmed that the optical sheet of Example 1 has no inflection point within the diffusion distance, while the optical sheet of Comparative Example 1 has an inflection point within the diffusion distance.

In addition, as shown in the results of Table 1, the optical sheets of Examples 1 to 3 have a distribution value DFW of a gray value distribution curve with a distance of 14 mm to 25 mm, When the gray value is 50, the diffusing distance DFW is 14 mm to 25 mm and the hiding power is excellent compared to the optical sheets of Comparative Examples 1 to 3 in which the inflection point on the distribution curve of the gray value according to the distance is present, Is excellent.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

An optical sheet comprising a substrate layer, a prism pattern layer formed on one surface of the substrate layer, and a concavo-convex pattern formed on the other surface of the substrate layer,
After fixing the optical sheet at a position spaced 110 mm from a circular light source having a diameter D of 8 mm, a gray value according to distance (x, y) extracted from the photographed electronic image, Wherein the diffusion distance DFW is from 14 mm to 25 mm when the gray value on the distribution curve is 50, and no inflection point exists within the diffusion distance. The method according to claim 1,
Wherein the same gray value does not appear or the same gray value appears twice according to the distance within the diffusion distance on the distribution curve of the gray value according to the distance. The method according to claim 1,
And a haze value of 9 to 60%. The method according to claim 1,
And the surface roughness Rz of the uneven pattern is 0.8 to 2.7 占 퐉. The method according to claim 1,
The substrate layer may be formed of at least one of a polyacetal resin, a polyacrylic resin, a polystyrene resin, a polycarbonate resin, a polysulfone resin, a polyvinyl chloride resin, a polyvinyl alcohol resin, a polynorbornene resin, Based resin, a vinyl-based resin, a polyphenylene ether-based resin, a polyolefin-based resin, a cycloolefin-based resin, an acrylonitrile-butadiene-styrene-based copolymer resin, a polyarylsulfone- , A polyethylene naphthalate-based resin, or a fluorine-based resin. The method according to claim 1,
Wherein the prism pattern layer is a cured product of an ultraviolet curable resin comprising at least one member selected from the group consisting of urethane acrylic, polyester acrylic, silicone acrylic, unsaturated polyester, and polyether acrylic. The method according to claim 1,
The thickness of the base layer is 38 to 300 탆,
Wherein the prism pattern layer has a thickness of 10 to 50 占 퐉. 5. The method of claim 4,
Wherein the surface roughness Ra of the concavo-convex pattern is 0.09 to 0.32 占 퐉, and Ry is 0.8 to 2.7 占 퐉. The method according to claim 1,
Wherein a pitch of the unit prisms constituting the prism pattern layer is 20 to 60 占 퐉 and a height is 10 to 30 占 퐉. An optical display device comprising the optical sheet according to any one of claims 1 to 9.

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